WorldWideScience

Sample records for cumulative logit models

  1. MULTINOMINAL LOGIT MODEL OF BICYCLIST ROUTE CHOICE

    Directory of Open Access Journals (Sweden)

    O. Chernyshova

    2016-06-01

    Full Text Available The paper presents the multinominal logit discrete choice model that allows determining parameters coefficients of the cyclists’ route. The basic model includes six parameters, however, only a number of signalized intersections, speed of motorized traffic and total physical work required from cyclist prove to be significant factors. The model provides a better understanding about cyclist traffic assignment.

  2. Interpreting Results from the Multinomial Logit Model

    DEFF Research Database (Denmark)

    Wulff, Jesper

    2015-01-01

    This article provides guidelines and illustrates practical steps necessary for an analysis of results from the multinomial logit model (MLM). The MLM is a popular model in the strategy literature because it allows researchers to examine strategic choices with multiple outcomes. However, there see...

  3. A nested recursive logit model for route choice analysis

    DEFF Research Database (Denmark)

    Mai, Tien; Frejinger, Emma; Fosgerau, Mogens

    2015-01-01

    We propose a route choice model that relaxes the independence from irrelevant alternatives property of the logit model by allowing scale parameters to be link specific. Similar to the recursive logit (RL) model proposed by Fosgerau et al. (2013), the choice of path is modeled as a sequence of link...

  4. A nested recursive logit model for route choice analysis

    DEFF Research Database (Denmark)

    Mai, Tien; Frejinger, Emma; Fosgerau, Mogens

    2015-01-01

    We propose a route choice model that relaxes the independence from irrelevant alternatives property of the logit model by allowing scale parameters to be link specific. Similar to the recursive logit (RL) model proposed by Fosgerau et al. (2013), the choice of path is modeled as a sequence of link...

  5. Profile construction in experimental choice designs for mixed logit models

    NARCIS (Netherlands)

    Sandor, Z; Wedel, M

    2002-01-01

    A computationally attractive model for the analysis of conjoint choice experiments is the mixed multinomial logit model, a multinomial logit model in which it is assumed that the coefficients follow a (normal) distribution across subjects. This model offers the advantage over the standard

  6. A Logit Model with Interactions for Predicting Major Gift Donors.

    Science.gov (United States)

    Lindahl, Wesley E.; Winship, Christopher

    1994-01-01

    A new statistical model based for identifying potential major donors was developed from a portion (n=53,276) of the Northwestern University (Illinois) alumni database. The model, utilizing logit analysis, found that the most critical measure was individuals' past giving records. Results indicate prospects with a low past giving level will rarely…

  7. STAS and Logit Modeling of Advertising and Promotion Effects

    DEFF Research Database (Denmark)

    Hansen, Flemming; Yssing Hansen, Lotte; Grønholdt, Lars

    2002-01-01

    This paper describes the preliminary studies of the effect of advertising and promotion on purchases using the British single-source database Adlab. STAS and logit modeling are the two measures studied. Results from the two measures have been compared to determine the extent to which, they give...

  8. Romanian farmers’ market. A multinomial logit model approach

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    Vincenţiu Vereş

    2007-12-01

    Full Text Available This paper analyzes the nature of the farmers’ market in Romania and its position regarding the main rivals: the specialized stores and the supermarkets. We use a multinomial logit model to estimate the consumers’ characteristics which determine their preference for a certain commercialization form of the fresh agricultural products. The estimations of the model show that farmers’ market can keep asegment of consumers relatively stable, since it dominates its competitors through prices, proximity to the consumers, freshness and diversity of the products

  9. The Reduced RUM as a Logit Model: Parameterization and Constraints.

    Science.gov (United States)

    Chiu, Chia-Yi; Köhn, Hans-Friedrich

    2016-06-01

    Cognitive diagnosis models (CDMs) for educational assessment are constrained latent class models. Examinees are assigned to classes of intellectual proficiency defined in terms of cognitive skills called attributes, which an examinee may or may not have mastered. The Reduced Reparameterized Unified Model (Reduced RUM) has received considerable attention among psychometricians. Markov Chain Monte Carlo (MCMC) or Expectation Maximization (EM) are typically used for estimating the Reduced RUM. Commercial implementations of the EM algorithm are available in the latent class analysis (LCA) routines of Latent GOLD and Mplus, for example. Fitting the Reduced RUM with an LCA routine requires that it be reparameterized as a logit model, with constraints imposed on the parameters. For models involving two attributes, these have been worked out. However, for models involving more than two attributes, the parameterization and the constraints are nontrivial and currently unknown. In this article, the general parameterization of the Reduced RUM as a logit model involving any number of attributes and the associated parameter constraints are derived. As a practical illustration, the LCA routine in Mplus is used for fitting the Reduced RUM to two synthetic data sets and to a real-world data set; for comparison, the results obtained by using the MCMC implementation in OpenBUGS are also provided.

  10. A Maximum Entropy Estimator for the Aggregate Hierarchical Logit Model

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    Pedro Donoso

    2011-08-01

    Full Text Available A new approach for estimating the aggregate hierarchical logit model is presented. Though usually derived from random utility theory assuming correlated stochastic errors, the model can also be derived as a solution to a maximum entropy problem. Under the latter approach, the Lagrange multipliers of the optimization problem can be understood as parameter estimators of the model. Based on theoretical analysis and Monte Carlo simulations of a transportation demand model, it is demonstrated that the maximum entropy estimators have statistical properties that are superior to classical maximum likelihood estimators, particularly for small or medium-size samples. The simulations also generated reduced bias in the estimates of the subjective value of time and consumer surplus.

  11. Box-Cox Mixed Logit Model for Travel Behavior Analysis

    Science.gov (United States)

    Orro, Alfonso; Novales, Margarita; Benitez, Francisco G.

    2010-09-01

    To represent the behavior of travelers when they are deciding how they are going to get to their destination, discrete choice models, based on the random utility theory, have become one of the most widely used tools. The field in which these models were developed was halfway between econometrics and transport engineering, although the latter now constitutes one of their principal areas of application. In the transport field, they have mainly been applied to mode choice, but also to the selection of destination, route, and other important decisions such as the vehicle ownership. In usual practice, the most frequently employed discrete choice models implement a fixed coefficient utility function that is linear in the parameters. The principal aim of this paper is to present the viability of specifying utility functions with random coefficients that are nonlinear in the parameters, in applications of discrete choice models to transport. Nonlinear specifications in the parameters were present in discrete choice theory at its outset, although they have seldom been used in practice until recently. The specification of random coefficients, however, began with the probit and the hedonic models in the 1970s, and, after a period of apparent little practical interest, has burgeoned into a field of intense activity in recent years with the new generation of mixed logit models. In this communication, we present a Box-Cox mixed logit model, original of the authors. It includes the estimation of the Box-Cox exponents in addition to the parameters of the random coefficients distribution. Probability of choose an alternative is an integral that will be calculated by simulation. The estimation of the model is carried out by maximizing the simulated log-likelihood of a sample of observed individual choices between alternatives. The differences between the predictions yielded by models that are inconsistent with real behavior have been studied with simulation experiments.

  12. Ordered LOGIT Model approach for the determination of financial distress.

    Science.gov (United States)

    Kinay, B

    2010-01-01

    Nowadays, as a result of the global competition encountered, numerous companies come up against financial distresses. To predict and take proactive approaches for those problems is quite important. Thus, the prediction of crisis and financial distress is essential in terms of revealing the financial condition of companies. In this study, financial ratios relating to 156 industrial firms that are quoted in the Istanbul Stock Exchange are used and probabilities of financial distress are predicted by means of an ordered logit regression model. By means of Altman's Z Score, the dependent variable is composed by scaling the level of risk. Thus, a model that can compose an early warning system and predict financial distress is proposed.

  13. Cumulative fatigue damage models

    Science.gov (United States)

    Mcgaw, Michael A.

    1988-01-01

    The problem of calculating expected component life under fatigue loading conditions is complicated by the fact that component loading histories contain, in many cases, cyclic loads of widely varying amplitudes. In such a case a cumulative damage model is required, in addition to a fatigue damage criterion, or life relationship, in order to compute the expected fatigue life. The traditional cumulative damage model used in design is the linear damage rule. This model, while being simple to use, can yield grossly unconservative results under certain loading conditions. Research at the NASA Lewis Research Center has led to the development of a nonlinear cumulative damage model, named the double damage curve approach (DDCA), that has greatly improved predictive capability. This model, which considers the life (or loading) level dependence of damage evolution, was applied successfully to two polycrystalline materials, 316 stainless steel and Haynes 188. The cumulative fatigue behavior of the PWA 1480 single-crystal material is currently being measured to determine the applicability of the DDCA for this material.

  14. Essays on pricing dynamics, price dispersion, and nested logit modelling

    Science.gov (United States)

    Verlinda, Jeremy Alan

    The body of this dissertation comprises three standalone essays, presented in three respective chapters. Chapter One explores the possibility that local market power contributes to the asymmetric relationship observed between wholesale costs and retail prices in gasoline markets. I exploit an original data set of weekly gas station prices in Southern California from September 2002 to May 2003, and take advantage of highly detailed station and local market-level characteristics to determine the extent to which spatial differentiation influences price-response asymmetry. I find that brand identity, proximity to rival stations, bundling and advertising, operation type, and local market features and demographics each influence a station's predicted asymmetric relationship between prices and wholesale costs. Chapter Two extends the existing literature on the effect of market structure on price dispersion in airline fares by modeling the effect at the disaggregate ticket level. Whereas past studies rely on aggregate measures of price dispersion such as the Gini coefficient or the standard deviation of fares, this paper estimates the entire empirical distribution of airline fares and documents how the shape of the distribution is determined by market structure. Specifically, I find that monopoly markets favor a wider distribution of fares with more mass in the tails while duopoly and competitive markets exhibit a tighter fare distribution. These findings indicate that the dispersion of airline fares may result from the efforts of airlines to practice second-degree price discrimination. Chapter Three adopts a Bayesian approach to the problem of tree structure specification in nested logit modelling, which requires a heavy computational burden in calculating marginal likelihoods. I compare two different techniques for estimating marginal likelihoods: (1) the Laplace approximation, and (2) reversible jump MCMC. I apply the techniques to both a simulated and a travel mode

  15. Multinomial Logit Model of Pedestrian Crossing Behaviors at Signalized Intersections

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    Zhu-Ping Zhou

    2013-01-01

    Full Text Available Pedestrian crashes, making up a large proportion of road casualties, are more likely to occur at signalized intersections in China. This paper aims to study the different pedestrian behaviors of regular users, late starters, sneakers, and partial sneakers. Behavior information was observed manually in the field study. After that, the survey team distributed a questionnaire to the same participant who has been observed, to acquire detailed demographic and socioeconomic characteristics as well as attitude and preference indicators. Totally, 1878 pedestrians were surveyed at 16 signalized intersections in Nanjing. First, correlation analysis is performed to analyze each factor’s effect. Then, five latent variables including safety, conformity, comfort, flexibility, and fastness are obtained by structure equation modeling (SEM. Moreover, based on the results of SEM, a multinomial logit model with latent variables is developed to describe how the factors influence pedestrians’ behavior. Finally, some conclusions are drawn from the model: (1 for the choice of being late starters, arrival time, the presence of oncoming cars, and crosswalk length are the most important factors; (2 gender has the most significant effect on the pedestrians to be sneakers; and (3 age is the most important factor when pedestrians choose to be partial sneakers.

  16. Street Choice Logit Model for Visitors in Shopping Districts

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    Ko Kawada

    2014-07-01

    Full Text Available In this study, we propose two models for predicting people’s activity. The first model is the pedestrian distribution prediction (or postdiction model by multiple regression analysis using space syntax indices of urban fabric and people distribution data obtained from a field survey. The second model is a street choice model for visitors using multinomial logit model. We performed a questionnaire survey on the field to investigate the strolling routes of 46 visitors and obtained a total of 1211 street choices in their routes. We proposed a utility function, sum of weighted space syntax indices, and other indices, and estimated the parameters for weights on the basis of maximum likelihood. These models consider both street networks, distance from destination, direction of the street choice and other spatial compositions (numbers of pedestrians, cars, shops, and elevation. The first model explains the characteristics of the street where many people tend to walk or stay. The second model explains the mechanism underlying the street choice of visitors and clarifies the differences in the weights of street choice parameters among the various attributes, such as gender, existence of destinations, number of people, etc. For all the attributes considered, the influences of DISTANCE and DIRECTION are strong. On the other hand, the influences of Int.V, SHOPS, CARS, ELEVATION, and WIDTH are different for each attribute. People with defined destinations tend to choose streets that “have more shops, and are wider and lower”. In contrast, people with undefined destinations tend to choose streets of high Int.V. The choice of males is affected by Int.V, SHOPS, WIDTH (positive and CARS (negative. Females prefer streets that have many shops, and couples tend to choose downhill streets. The behavior of individual persons is affected by all variables. The behavior of people visiting in groups is affected by SHOP and WIDTH (positive.

  17. Unobserved Heterogeneity in the Binary Logit Model with Cross-Sectional Data and Short Panels

    DEFF Research Database (Denmark)

    Holm, Anders; Jæger, Mads Meier; Pedersen, Morten

    This paper proposes a new approach to dealing with unobserved heterogeneity in applied research using the binary logit model with cross-sectional data and short panels. Unobserved heterogeneity is particularly important in non-linear regression models such as the binary logit model because, unlike...... in linear regression models, estimates of the effects of observed independent variables are biased even when omitted independent variables are uncorrelated with the observed independent variables. We propose an extension of the binary logit model based on a finite mixture approach in which we conceptualize...

  18. Study on the Degree of Rural Empty Nesters’ Satisfaction with Life Quality Based on Ordered Logit-ISM Model

    Institute of Scientific and Technical Information of China (English)

    Huanan; ZHANG; Jin; FANG; Hongxia; BI

    2015-01-01

    It is an ultimate objective to solve the rural supporting problems to improve life satisfaction of empty nesters in rural areas. Based on data of 546 empty nesters in rural areas,the factors influencing life quality satisfaction of empty nesters in rural areas are firstly analyzed using ordered logit model,and then the relationship between various influencing factors is analyzed using ISM. Study shows that health condition,degree of participation in cultural and sports activities,spouse status,family harmony degree,annual family income,degree of worry about life,degree of government and social care and pension mode,have a significant impact on the life quality satisfaction of empty nesters in rural areas.The degree of worry about life,degree of government and social care are surface direct factors; degree of participation in cultural and sports activities,family harmony degree,pension mode are intermediate indirect factors; health condition,spouse status and annual family income are deep root factors.

  19. Estimating growth of SMES using a logit model: Evidence from manufacturing companies in Italy

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    Amith Vikram Megaravalli

    2017-03-01

    Full Text Available In this paper, an effort has been put to develop a model for estimating growth based on logit re-gression (logit and implemented the model to Italian manufacturing companies. Our data set consists of 8232 SMEs of Italy. To estimate the growth of the firm an innovative approach that considers annual statements issued the year before the accelerated growth has been considered as the effective estimators of firm growth. The result of the logit showed that return on asset, log (cash flow and log (Inventory positively affect in estimating the growth of the high growth firm whereas working capital turnover times negatively affects in estimating the growth of the firm. The discriminant power of the model using Receiver Operating Characteristics curve shows 72.35%, which means the model is fair in terms of estimating the growth.

  20. DETEKSI DINI KRISIS PERBANKAN INDONESIA: IDENTIFIKASI VARIABEL MAKRO DENGAN MODEL LOGIT

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    Shanty Oktavilia

    2012-01-01

    Full Text Available Indonesia suffered from banking crisis for several times. It was the effect of the worst crisis occurredin 1997. Actually, Bath Thailand which plunged into 27,8% at the third quarter of the year 1997 was thebeginning problem that caused Asia currency crisis. This study analyzes the influence of macro indicatoras an early warning system by using logit econometrics model for predicting the possibilities of bankingcrisis that may occur in Indonesia.Kewords: Banking Crisis, macro economic indicator, EWS-logit model

  1. Another Look at the Method of Y-Standardization in Logit and Probit Models

    DEFF Research Database (Denmark)

    Karlson, Kristian Bernt

    2015-01-01

    assuming that the logit or probit fixes the variance of the latent error at a known constant, it suffices to assume that the variance of the error is unknown. A further result suggests that using Y-standardization for cross-model comparisons is likely to be biased by model differences in the fit...

  2. Another Look at the Method of Y-Standardization in Logit and Probit Models

    DEFF Research Database (Denmark)

    Karlson, Kristian Bernt

    2015-01-01

    This paper takes another look at the derivation of the method of Y-standardization used in sociological analysis involving comparisons of coefficients across logit or probit models. It shows that the method can be derived under less restrictive assumptions than hitherto suggested. Rather than...

  3. Modeling school bus seat belt usage: Nested and mixed logit approaches.

    Science.gov (United States)

    Mehta, Gaurav; Lou, Yingyan

    2013-03-01

    School bus seat belt usage has been of great interest to the school transportation community. Understanding factors that influence students' decisions about wearing seat belts or not is important in determining the most cost-effective ways to improve belt usage rate, and thus the seat belt safety benefits. This paper presents a rigorous empirical analysis on data from Alabama School Bus Pilot Project using discrete choice modeling framework. In order to collect relevant information on individual student-trips, a new data collection protocol is adopted. Three choice alternatives are considered in the study: wearing, not wearing, and improperly wearing seat belts. A student's choice probabilities of these alternatives are modeled as functions of the student's characteristics and trip attributes. The coefficients of the variables in the functions are estimated first using standard multinomial logit model. Moreover, to account for potential correlations among the three choice alternatives and individual-level preference and response heterogeneity among users, nested and mixed logit models are employed in the investigation. Eight significant influence factors are identified by the final models. Their relative impacts are also quantified. The factors include age, gender and the home county of a student, a student's trip length, time of day, seat location, presence and active involvement of bus aide, and two levels of bus driver involvement. The impact of the seat location on students' seat belt usage is revealed for the first time by this study. Both hypotheses that some of the choice alternatives are correlated and that individual-level heterogeneity exists are tested statistically significant. In view of this, the nested and the mixed logit model are recommended over the standard multinomial logit model to describe and predict students' seat belt usage behaviors. The final nested logit model uncovers a correlation between improper wearing and not wearing, indicating

  4. An Empirical Analysis of Television Commercial Ratings in Alternative Competitive Environments Using Multinomial Logit Model

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    Dilek ALTAŞ

    2013-05-01

    Full Text Available Watching the commercials depends on the choice of the viewer. Most of the television viewing takes place during “Prime-Time” unfortunately; many viewers opt to zap to other channels when commercials start. The television viewers’ demographic characteristics may indicate the likelihood of the zapping frequency. Analysis made by using Multinomial Logit Model indicates how effective the demographic variables are in the watching rate of the first minute of the television commercials.

  5. Interpreting Marginal Effects in the Multinomial Logit Model

    DEFF Research Database (Denmark)

    Wulff, Jesper

    2014-01-01

    This paper presents the challenges when researchers interpret results about relationships between variables from discrete choice models with multiple outcomes. The recommended approach is demonstrated by testing predictions from transaction cost theory on a sample of 246 Scandinavian firms that h...

  6. An Research on Electrical Vehicle'S Charge-Discharge Behavior Based on Logit Model

    Science.gov (United States)

    Xiaoyin, Wang; Junyong, Liu

    Electric Vehicle is the future trend of the automobile industry, and the energy exchanging between the electrical vehicles and the grid through the vehicle-to-grid (V2G) technology becomes possiable. V2G leads to a rapid load growth effecting the benefit of the grid, which wasn't discussed. The charge and discharge model of the electrical vehicles is discussed using the multinomial logit model based on the discrete choice theory, then preliminarily evaluates the effects of economic benefit both on the motorist and the grid. Finally, suggestions on period division and electricity pricing for charge and discharge of the electrical vehicle are given.

  7. A Microeconomic Interpretation of the Maximum Entropy Estimator of Multinomial Logit Models and Its Equivalence to the Maximum Likelihood Estimator

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    Louis de Grange

    2010-09-01

    Full Text Available Maximum entropy models are often used to describe supply and demand behavior in urban transportation and land use systems. However, they have been criticized for not representing behavioral rules of system agents and because their parameters seems to adjust only to modeler-imposed constraints. In response, it is demonstrated that the solution to the entropy maximization problem with linear constraints is a multinomial logit model whose parameters solve the likelihood maximization problem of this probabilistic model. But this result neither provides a microeconomic interpretation of the entropy maximization problem nor explains the equivalence of these two optimization problems. This work demonstrates that an analysis of the dual of the entropy maximization problem yields two useful alternative explanations of its solution. The first shows that the maximum entropy estimators of the multinomial logit model parameters reproduce rational user behavior, while the second shows that the likelihood maximization problem for multinomial logit models is the dual of the entropy maximization problem.

  8. The use of mixed logit models to reflect heterogeneity in capture-recapture studies.

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    Coull, B A; Agresti, A

    1999-03-01

    We examine issues in estimating population size N with capture-recapture models when there is variable catchability among subjects. We focus on a logistic-normal mixed model, for which the logit of the probability of capture is an additive function of a random subject and a fixed sampling occasion parameter. When the probability of capture is small or the degree of heterogeneity is large, the log-likelihood surface is relatively flat and it is difficult to obtain much information about N. We also discuss a latent class model and a log-linear model that account for heterogeneity and show that the log-linear model has greater scope. Models assuming homogeneity provide much narrower intervals for N but are usually highly overly optimistic, the actual coverage probability being much lower than the nominal level.

  9. Bayesian nonparametric estimation and consistency of mixed multinomial logit choice models

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    De Blasi, Pierpaolo; Lau, John W; 10.3150/09-BEJ233

    2011-01-01

    This paper develops nonparametric estimation for discrete choice models based on the mixed multinomial logit (MMNL) model. It has been shown that MMNL models encompass all discrete choice models derived under the assumption of random utility maximization, subject to the identification of an unknown distribution $G$. Noting the mixture model description of the MMNL, we employ a Bayesian nonparametric approach, using nonparametric priors on the unknown mixing distribution $G$, to estimate choice probabilities. We provide an important theoretical support for the use of the proposed methodology by investigating consistency of the posterior distribution for a general nonparametric prior on the mixing distribution. Consistency is defined according to an $L_1$-type distance on the space of choice probabilities and is achieved by extending to a regression model framework a recent approach to strong consistency based on the summability of square roots of prior probabilities. Moving to estimation, slightly different te...

  10. A smooth transition logit model of the effects of deregulation in the electricity market

    DEFF Research Database (Denmark)

    Hurn, A. Stan; Silvennoinen, Annastiina; Teräsvirta, Timo

    2016-01-01

    This paper introduces the smooth transition logit (STL) model that is designed to detect and model situations in which there is structural change in the behaviour underlying the latent index from which the binary dependent variable is constructed. The maximum likelihood estimators of the paramete......’ behaviour to change gradually over time. The main results provide clear evidence in support of a structural change in the nature of price events, and the endogenously determined timing of the change is consistent with the process of deregulation in Queensland....... and ascertain whether increased competition has resulted in significant changes in the behaviour of the spot price of electricity, specifically with respect to the occurrence of periodic abnormally high prices. The model allows the timing of any change to be endogenously determined and also market participants...

  11. Forecasting Paratransit Utility by Using Multinomial Logit Model: A Case Study

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    Waikhom Victory

    2016-10-01

    Full Text Available Paratransit plays an important role in the urban passenger transportation system in the developing countries. Three cities viz. Imphal East, Imphal West and Silchar in India have been undertaken for the study. Household survey and traffic survey have been employed to collect data for the paratransit users. Modelling techniques and tools also have been used to forecast the utility of paratransit in the region. For this purpose, a Multinomial Logit Model (MNL had been used. A total of seven variables were considered in the model estimation of which three are quantitative i.e. trip length (km, travel cost (rupees and travel time (minutes and four are qualitative variables i.e. reliability, comfort, road condition and convenience.

  12. Airport Choice in Sao Paulo Metropolitan Area: An Application of the Conditional Logit Model

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    Moreno, Marcelo Baena; Muller, Carlos

    2003-01-01

    Using the conditional LOGIT model, this paper addresses the airport choice in the Sao Paulo Metropolitan Area. In this region, Guarulhos International Airport (GRU) and Congonhas Airport (CGH) compete for passengers flying to several domestic destinations. The airport choice is believed to be a result of the tradeoff passengers perform considering airport access characteristics, airline level of service characteristics and passenger experience with the analyzed airports. It was found that access time to the airports better explain the airport choice than access distance, whereas direct flight frequencies gives better explanation to the airport choice than the indirect (connections and stops) and total (direct plus indirect) flight frequencies. Out of 15 tested variables, passenger experience with the analyzed airports was the variable that best explained the airport choice in the region. Model specifications considering 1, 2 or 3 variables were tested. The model specification most adjusted to the observed data considered access time, direct flight frequencies in the travel period (morning or afternoon peak) and passenger experience with the analyzed airports. The influence of these variables was therefore analyzed across market segments according to departure airport and flight duration criteria. The choice of GRU (located neighboring Sao Paulo city) is not well explained by the rationality of access time economy and the increase of the supply of direct flight frequencies, while the choice of CGH (located inside Sao Paulo city) is. Access time was found to be more important to passengers flying shorter distances while direct flight frequencies in the travel period were more significant to those flying longer distances. Keywords: Airport choice, Multiple airport region, Conditional LOGIT model, Access time, Flight frequencies, Passenger experience with the analyzed airports, Transportation planning

  13. Associating Crash Avoidance Maneuvers with Driver Attributes and Accident Characteristics: A Mixed Logit Model Approach

    DEFF Research Database (Denmark)

    Kaplan, Sigal; Prato, Carlo Giacomo

    2012-01-01

    This study focuses on the propensity of drivers to engage in crash avoidance maneuvers in relation to driver attributes, critical events, crash characteristics, vehicles involved, road characteristics and environmental attributes. Five alternative actions involving emergency lateral and speed...... as from the key role of the ability of drivers to perform effective corrective maneuvers for the success of automated in-vehicle warning and driver assistance systems. The analysis is conducted by means of a mixed logit model that accommodates correlations across alternatives and heteroscedasticity. Data...... for the analysis are retrieved from the General Estimates System (GES) crash database for the year 2009. Results show that (i) the nature of the critical event that made the crash imminent influences the choice of crash avoidance maneuvers, (ii) women and elderly have a lower propensity to conduct crash avoidance...

  14. Analysis of Internet Usage Intensity in Iraq: An Ordered Logit Model

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    Almas Heshmati

    2013-06-01

    Full Text Available Intensity of Internet use is significantly influenced by government policies, people’s levels of income, education, employment and general development and economic conditions. Iraq has very low Internet usage levels compared to the region and the world. This study uses an ordered logit model to analyse the intensity of Internet use in Iraq. The results showed that economic reasons (internet cost and income level were key cause for low level usage intensity rates. About 68% of the population revealed that Internet access at homes is costly. Thus, it is no wonder that Internet cafés is the most commonly used mode of Internet use followed by broadband and dial-up connections. Iraq has to develop proper strategies to enhance the rate of Internet use in the country. These strategies need to focus on decreasing internet access prices, increasing awareness about the importance of the technology and internet education in schools and universities.

  15. A generalized nonlinear model-based mixed multinomial logit approach for crash data analysis.

    Science.gov (United States)

    Zeng, Ziqiang; Zhu, Wenbo; Ke, Ruimin; Ash, John; Wang, Yinhai; Xu, Jiuping; Xu, Xinxin

    2017-02-01

    The mixed multinomial logit (MNL) approach, which can account for unobserved heterogeneity, is a promising unordered model that has been employed in analyzing the effect of factors contributing to crash severity. However, its basic assumption of using a linear function to explore the relationship between the probability of crash severity and its contributing factors can be violated in reality. This paper develops a generalized nonlinear model-based mixed MNL approach which is capable of capturing non-monotonic relationships by developing nonlinear predictors for the contributing factors in the context of unobserved heterogeneity. The crash data on seven Interstate freeways in Washington between January 2011 and December 2014 are collected to develop the nonlinear predictors in the model. Thirteen contributing factors in terms of traffic characteristics, roadway geometric characteristics, and weather conditions are identified to have significant mixed (fixed or random) effects on the crash density in three crash severity levels: fatal, injury, and property damage only. The proposed model is compared with the standard mixed MNL model. The comparison results suggest a slight superiority of the new approach in terms of model fit measured by the Akaike Information Criterion (12.06 percent decrease) and Bayesian Information Criterion (9.11 percent decrease). The predicted crash densities for all three levels of crash severities of the new approach are also closer (on average) to the observations than the ones predicted by the standard mixed MNL model. Finally, the significance and impacts of the contributing factors are analyzed.

  16. Nonlinear cumulative damage model for multiaxial fatigue

    Institute of Scientific and Technical Information of China (English)

    SHANG De-guang; SUN Guo-qin; DENG Jing; YAN Chu-liang

    2006-01-01

    On the basis of the continuum fatigue damage theory,a nonlinear uniaxial fatigue cumulative damage model is first proposed.In order to describe multiaxial fatigue damage characteristics,a nonlinear multiaxial fatigue cumulative damage model is developed based on the critical plane approach,The proposed model can consider the multiaxial fatigue limit,mean hydrostatic pressure and the unseparated characteristic for the damage variables and loading parameters.The recurrence formula of fatigue damage model was derived under multilevel loading,which is used to predict multiaxial fatigue life.The results showed that the proposed nonlinear multiaxial fatigue cumulative damage model is better than Miner's rule.

  17. A Comparison between Robust z and 0.3-Logit Difference Procedures in Assessing Stability of Linking Items for the Rasch Model

    Science.gov (United States)

    Huynh, Huynh; Rawls, Anita

    2011-01-01

    There are at least two procedures to assess item difficulty stability in the Rasch model: robust z procedure and "0.3 Logit Difference" procedure. The robust z procedure is a variation of the z statistic that reduces dependency on outliers. The "0.3 Logit Difference" procedure is based on experiences in Rasch linking for tests…

  18. Model-based Clustering of Categorical Time Series with Multinomial Logit Classification

    Science.gov (United States)

    Frühwirth-Schnatter, Sylvia; Pamminger, Christoph; Winter-Ebmer, Rudolf; Weber, Andrea

    2010-09-01

    A common problem in many areas of applied statistics is to identify groups of similar time series in a panel of time series. However, distance-based clustering methods cannot easily be extended to time series data, where an appropriate distance-measure is rather difficult to define, particularly for discrete-valued time series. Markov chain clustering, proposed by Pamminger and Frühwirth-Schnatter [6], is an approach for clustering discrete-valued time series obtained by observing a categorical variable with several states. This model-based clustering method is based on finite mixtures of first-order time-homogeneous Markov chain models. In order to further explain group membership we present an extension to the approach of Pamminger and Frühwirth-Schnatter [6] by formulating a probabilistic model for the latent group indicators within the Bayesian classification rule by using a multinomial logit model. The parameters are estimated for a fixed number of clusters within a Bayesian framework using an Markov chain Monte Carlo (MCMC) sampling scheme representing a (full) Gibbs-type sampler which involves only draws from standard distributions. Finally, an application to a panel of Austrian wage mobility data is presented which leads to an interesting segmentation of the Austrian labour market.

  19. Patterns of Dupuytren disease in fingers: studying correlations with a multivariate ordinal logit model.

    Science.gov (United States)

    Lanting, Rosanne; Nooraee, Nazanin; Werker, Paul M N; van den Heuvel, Edwin R

    2014-09-01

    Dupuytren disease affects fingers in a variable fashion. Knowledge about specific disease patterns (phenotype) based on location and severity of the disease is lacking. In this cross-sectional study, 344 primary affected hands with Dupuytren disease were physically examined. The Pearson correlation coefficient between the coexistence of Dupuytren disease in pairs of fingers was calculated, and agglomerative hierarchical clustering was applied to identify possible clusters of affected fingers. With a multivariate ordinal logit model, the authors studied the correlation on severity, taking into account age and sex, and tested hypotheses on independence between groups of fingers. The ring finger was most frequently affected by Dupuytren disease, and contractures were seen in 15.1 percent of affected rays. The severity of thumb and index finger, middle and ring fingers, and middle and little fingers was significantly correlated. Occurrences in pairs of fingers were highest in the middle and ring fingers and lowest in the thumb and index finger. Correlation between the ring and little fingers and a correlation between fingers from the ulnar and radial sides could not be demonstrated. Rays on the ulnar side of the hand are predominantly affected. The middle finger is substantially correlated with other fingers on the ulnar side, and the thumb and index finger are correlated; however, there was no evidence that the ulnar side and the radial side were correlated in any way, which suggests that occurrence on one side of the hand does not predict Dupuytren disease on the other side of the hand. Risk, III.

  20. Analysis of the Purpose of Using Internet in Iraq: A Multinomial Logit Model

    Directory of Open Access Journals (Sweden)

    Firas H. Al-Hammadany

    2011-10-01

    Full Text Available Internet accessibility is positively correlated with infrastructure development and nature of government policies. Though Iraq has shown considerable increase in Internet connectivity, it constitutes only 10 % of its population. In this study, the significant factors determining the use and non-use of Internet have been identified and analyzed. The results revealed that human development, human capital, institutional and legal environment, existing technologies, government policy making and income levels affect the Internet accessibility. The non-Internet users mainly comprised from 12-25 years age group. Similarly, high school and diploma students constituted significant proportion of non-Internet users. Lack of awareness and poor access to Internet facility were quoted as the most significant factors that resulted in the poor Internet accessibility which were supported by the used multinomial logit model. Low income level of the people resulted in non-use of Internet.The use of Internet was found to be highest among those with high level of education. Hence, the measures like provision of ICT based training programs, effective government policy for prioritizing Internet in education sector and allowing most advanced Internet technologies in e-governance and increased efforts for enhancing human development and human capital would enhance the rate of Internet accessibility in Iraq.

  1. Evaluation of the SMEs’ Loans in the Iranian Banking System: An Application of a Logit Model

    Directory of Open Access Journals (Sweden)

    Mahshid Shahchera

    2012-01-01

    Full Text Available One of the main problems of SMEs is how to finance their investments. The role of banks in this regard is crucial, since they can be a type of sources of financing through lending credits directly to SMEs. The key role of the paper thus relies on analyzing the effect of SMEs financing by the Iranian banking system. The objective of this paper is to determine the influence of loans demanded by the SMEs on finance performance of the various Iranian banks. In addition, it studies the role of other important characters related to lending, bank efficiency, and economic performance in finance to SMEs through the banking system.It is motivated by the hypothesis that macroeconomic-cyclical indicators and bank-specific variables influence the nonperforming loans in the banking system. This is carried out by an application to a logit model. Our findings indicate that several variables have significant effects on nonperforming loans in the Iranian banking system. Return of asset, equity return, SME loan to total loan ratio, inflation, current asset to current liabilities ratio, total SMEs’ loans to total liabilities ratio and total SMEs’ loans to total assets ratio have the pronounced significant impacts on nonperforming loans of the Iranian banking. The coefficient of loans to SMEs is significantly positive, which implies that a loan to SMEs increases nonperforming loans method while raising risks to the banking system.

  2. A multinomial logit model-Bayesian network hybrid approach for driver injury severity analyses in rear-end crashes.

    Science.gov (United States)

    Chen, Cong; Zhang, Guohui; Tarefder, Rafiqul; Ma, Jianming; Wei, Heng; Guan, Hongzhi

    2015-07-01

    Rear-end crash is one of the most common types of traffic crashes in the U.S. A good understanding of its characteristics and contributing factors is of practical importance. Previously, both multinomial Logit models and Bayesian network methods have been used in crash modeling and analysis, respectively, although each of them has its own application restrictions and limitations. In this study, a hybrid approach is developed to combine multinomial logit models and Bayesian network methods for comprehensively analyzing driver injury severities in rear-end crashes based on state-wide crash data collected in New Mexico from 2010 to 2011. A multinomial logit model is developed to investigate and identify significant contributing factors for rear-end crash driver injury severities classified into three categories: no injury, injury, and fatality. Then, the identified significant factors are utilized to establish a Bayesian network to explicitly formulate statistical associations between injury severity outcomes and explanatory attributes, including driver behavior, demographic features, vehicle factors, geometric and environmental characteristics, etc. The test results demonstrate that the proposed hybrid approach performs reasonably well. The Bayesian network reference analyses indicate that the factors including truck-involvement, inferior lighting conditions, windy weather conditions, the number of vehicles involved, etc. could significantly increase driver injury severities in rear-end crashes. The developed methodology and estimation results provide insights for developing effective countermeasures to reduce rear-end crash injury severities and improve traffic system safety performance.

  3. Valuing Non-market Benefits of Rehabilitation of Hydrologic Cycle Improvements in the Anyangcheon Watershed: Using Mixed Logit Models

    Science.gov (United States)

    Yoo, J.; Kong, K.

    2010-12-01

    This research the findings from a discrete-choice experiment designed to estimate the economic benefits associated with the Anyangcheon watershed improvements in Rep. of Korea. The Anyangcheon watershed has suffered from streamflow depletion and poor stream quality, which often negatively affect instream and near-stream ecologic integrity, as well as water supply. Such distortions in the hydrologic cycle mainly result from rapid increase of impermeable area due to urbanization, decreases of baseflow runoff due to groundwater pumping, and reduced precipitation inputs driven by climate forcing. As well, combined sewer overflows and increase of non-point source pollution from urban regions decrease water quality. The appeal of choice experiments (CE) in economic analysis is that it is based on random utility theory (McFadden, 1974; Ben-Akiva and Lerman, 1985). In contrast to contingent valuation method (CVM), which asks people to choose between a base case and a specific alternative, CE asks people to choice between cases that are described by attributes. The attributes of this study were selected from hydrologic vulnerability components that represent flood damage possibility, instreamflow depletion, water quality deterioration, form of the watershed and tax. Their levels were divided into three grades include status quo. Two grades represented the ideal conditions. These scenarios were constructed from a 35 orthogonal main effect design. This design resulted in twenty-seven choice sets. The design had nine different choice scenarios presented to each respondent. The most popular choice models in use are the conditional logit (CNL). This model provides closed-form choice probability calculation. The shortcoming of CNL comes from irrelevant alternatives (IIA). In this paper, the mixed logit (ML) is applied to allow the coefficient’s variation for random taste heterogeneity in the population. The mixed logit model(with normal distributions for the attributes) fit the

  4. A EVALUATION OF CONSUMER’S PREFERENCES IN THE CLUJ-NAPOCA RETAIL MARKET BASED ON A MULTINOMIAL LOGIT MODEL

    Directory of Open Access Journals (Sweden)

    Ciprian Marcel POP

    2009-01-01

    Full Text Available A long period of time investors were interested in the Bucharest market, butthe need for investment in the rest of the country, coupled with the highpotential markets present there, resulted in increasingly more investorsinterested in Romania, switching to provincial cities. The applicationpresented in this paper involves clients of several types of retail storespresent in the commercial area of Cluj-Napoca. The results obtained in thestudy, through the multinomial logit model, show different aspects of theclient’s behaviour from the Romanian retail market.

  5. A multinomial-logit ordered-probit model for jointly analyzing crash avoidance maneuvers and crash severity

    DEFF Research Database (Denmark)

    Kaplan, Sigal; Prato, Carlo Giacomo

    the United States National Automotive Sampling System General Estimates System (GES) crash database for the years 2005-2009. Results show (i) the correlation between crash avoidance maneuvers and crash severity, and (ii) the link between drivers' attributes, risky driving behavior, road characteristics......Effective crash avoidance maneuvers in response to critical unexpected traffic events provide the opportunity to avoid crash occurrence and to minimize crash severity. The current study employs a joint multinomial-logit ordered-probit model (MNL-OR) for associating crash severity with drivers...

  6. Comparing Johnson’s SBB, Weibull and Logit-Logistic bivariate distributions for modeling tree diameters and heights using copulas

    Directory of Open Access Journals (Sweden)

    Jose Javier Gorgoso-Varela

    2016-04-01

    Full Text Available Aim of study: In this study we compare the accuracy of three bivariate distributions: Johnson’s SBB, Weibull-2P and LL-2P functions for characterizing the joint distribution of tree diameters and heights.Area of study: North-West of Spain.Material and methods: Diameter and height measurements of 128 plots of pure and even-aged Tasmanian blue gum (Eucalyptus globulus Labill. stands located in the North-west of Spain were considered in the present study. The SBB bivariate distribution was obtained from SB marginal distributions using a Normal Copula based on a four-parameter logistic transformation. The Plackett Copula was used to obtain the bivariate models from the Weibull and Logit-logistic univariate marginal distributions. The negative logarithm of the maximum likelihood function was used to compare the results and the Wilcoxon signed-rank test was used to compare the related samples of these logarithms calculated for each sample plot and each distribution.Main results: The best results were obtained by using the Plackett copula and the best marginal distribution was the Logit-logistic.Research highlights: The copulas used in this study have shown a good performance for modeling the joint distribution of tree diameters and heights. They could be easily extended for modelling multivariate distributions involving other tree variables, such as tree volume or biomass.

  7. Understanding Visitors’ Responses to Intelligent Transportation System in a Tourist City with a Mixed Ranked Logit Model

    Directory of Open Access Journals (Sweden)

    Yang Liu

    2017-01-01

    Full Text Available One important function of Intelligent Transportation System (ITS applied in tourist cities is to improve visitors’ mobility by releasing real-time transportation information and then shifting tourists from individual vehicles to intelligent public transit. The objective of this research is to quantify visitors’ psychological and behavioral responses to tourism-related ITS. Designed with a Mixed Ranked Logit Model (MRLM with random coefficients that was capable of evaluating potential effects from information uncertainty and other relevant factors on tourists’ transport choices, an on-site and a subsequent web-based stated preference survey were conducted in a representative tourist city (Chengde, China. Simulated maximum-likelihood procedure was used to estimate random coefficients. Results indicate that tourists generally perceive longer travel time and longer wait time if real-time information is not available. ITS information is able to reduce tourists’ perceived uncertainty and stimulating transport modal shifts. This novel MRLM contributes a new derivation model to logit model family and for the first time proposes an applicable methodology to assess useful features of ITS for tourists.

  8. Non-Linear Mixed Logit

    DEFF Research Database (Denmark)

    Andersen, Steffen; Harrison, Glenn W.; Hole, Arne Risa

    2012-01-01

    We develop an extension of the familiar linear mixed logit model to allow for the direct estimation of parametric non-linear functions defined over structural parameters. Classic applications include the estimation of coefficients of utility functions to characterize risk attitudes and discountin...

  9. Contract Farming Preferences of Smallholder Rice Producers in Benin: A Stated Choice Model Using Mixed Logit Erodibility

    Directory of Open Access Journals (Sweden)

    Arouna, A.

    2017-01-01

    Full Text Available In developing countries, smallholder farmers face many constraints including lack of information, and lack of access to credit and markets. To overcome these constraints, smallholder farmers can engage in contract farming. However, contract farming needs to meet farmers' preferences in order to be sustainable. This study aimed to analyze rice farmers' preferences for contract farming in Benin. Stated choice data were collected from 574 rice farmers. To account for heterogeneity, data were analyzed using a mixed logit model. Producers preferred contracts with seven major attributes: short term, payment on delivery, collective selling, agreement on quantity, no provision of credit, application of the market price, and no control by the partner. However, there was heterogeneity in the contract preferences of rice farmers. The study suggests that these differences and the preferred attributes are important in the design of best-fit contract farming models by agribusiness firms and policy-makers.

  10. A copula-based closed-form binary logit choice model for accommodating spatial correlation across observational units

    Science.gov (United States)

    Bhat, Chandra R.; Sener, Ipek N.

    2009-09-01

    This study focuses on accommodating spatial dependency in data indexed by geographic location. In particular, the emphasis is on accommodating spatial error correlation across observational units in binary discrete choice models. We propose a copula-based approach to spatial dependence modeling based on a spatial logit structure rather than a spatial probit structure. In this approach, the dependence between the logistic error terms of different observational units is directly accommodated using a multivariate logistic distribution based on the Farlie-Gumbel-Morgenstein (FGM) copula. The approach represents a simple and powerful technique that results in a closed-form analytic expression for the joint probability of choice across observational units, and is straightforward to apply using a standard and direct maximum likelihood inference procedure. There is no simulation machinery involved, leading to substantial computation gains relative to current methods to address spatial correlation. The approach is applied to teenagers’ physical activity participation levels, a subject of considerable interest in the public health, transportation, sociology, and adolescence development fields. The results indicate that failing to accommodate heteroscedasticity and spatial correlation can lead to inconsistent and inefficient parameter estimates, as well as incorrect conclusions regarding the elasticity effects of exogenous variables.

  11. Airline Choice for Domestic Flights in Sao Paulo Metropolitan Area: An Application of the Conditional Logit Model

    Science.gov (United States)

    Moreno, Marcelo Baena

    2006-01-01

    Using the conditional (multinomial) LOGIT model, this paper addresses airline choice in the S o Paulo Metropolitan Area. There are two airports in this region, where two, three or even four airlines compete for passengers flying to an array of domestic destinations. The airline choice is believed to be a result of the tradeoff passengers face among flight cost, flight frequency and airline performance. It was found that the lowest fare better explains airline choice than the highest fare, whereas direct flight frequencies give better explanation to airline choice than indirect (connections and stops) and total (direct plus indirect) ones. Out of 15 variables tested, the lowest fare was the variable that best explained airline choice. However, its signal was counterintuitive (positive) possibly because the cheapest airline was offering few flights, so passengers overwhelmingly failed to choose the cheapest airline. The model specification most adjusted to the data considered the lowest fare, direct flight frequency in the travel day and period (morning or afternoon peak) and airline age. Passengers departing from S o Paulo-Guarulhos International Airport (GRU) airport make their airline choice in terms of cost whereas those from Sao Paulo-Congonhas Airport (CGH) airport do not. Finally, senior passengers place more importance on airline age than junior passengers.

  12. An econometric analysis of changes in arable land utilization using multinomial logit model in Pinggu district, Beijing, China.

    Science.gov (United States)

    Xu, Yueqing; McNamara, Paul; Wu, Yanfang; Dong, Yue

    2013-10-15

    Arable land in China has been decreasing as a result of rapid population growth and economic development as well as urban expansion, especially in developed regions around cities where quality farmland quickly disappears. This paper analyzed changes in arable land utilization during 1993-2008 in the Pinggu district, Beijing, China, developed a multinomial logit (MNL) model to determine spatial driving factors influencing arable land-use change, and simulated arable land transition probabilities. Land-use maps, as well as social-economic and geographical data were used in the study. The results indicated that arable land decreased significantly between 1993 and 2008. Lost arable land shifted into orchard, forestland, settlement, and transportation land. Significant differences existed for arable land transitions among different landform areas. Slope, elevation, population density, urbanization rate, distance to settlements, and distance to roadways were strong drivers influencing arable land transition to other uses. The MNL model was proved effective for predicting transition probabilities in land use from arable land to other land-use types, thus can be used for scenario analysis to develop land-use policies and land-management measures in this metropolitan area.

  13. Revealing additional preference heterogeneity with an extended random parameter logit model: the case of extra virgin olive oil

    Directory of Open Access Journals (Sweden)

    Ahmed Yangui

    2014-07-01

    Full Text Available Methods that account for preference heterogeneity have received a significant amount of attention in recent literature. Most of them have focused on preference heterogeneity around the mean of the random parameters, which has been specified as a function of socio-demographic characteristics. This paper aims at analyzing consumers’ preferences towards extra-virgin olive oil in Catalonia using a methodological framework with two novelties over past studies: 1 it accounts for both preference heterogeneity around the mean and the variance; and 2 it considers both socio-demographic characteristics of consumers as well as their attitudinal factors. Estimated coefficients and moments of willingness to pay (WTP distributions are compared with those obtained from alternative Random Parameter Logit (RPL models. Results suggest that the proposed framework increases the goodness-of-fit and provides more useful insights for policy analysis. The most important attributes affecting consumers’ preferences towards extra virgin olive oil are the price and the product’s origin. The consumers perceive the organic olive oil attribute negatively, as they think that it is not worth paying a premium for a product that is healthy in nature.

  14. Impact of Labor Transfer on Agricultural Land Use Conversion at Rural Household Level Based on Logit Model

    Institute of Scientific and Technical Information of China (English)

    ZHONG Taiyang; ZHANG Xiuying; HUANG Xianjin

    2008-01-01

    Since land and labor force are primary resources to be used and controlled by rural households, the alloca-tion of labor forces will influence land uses, and further lead to land use conversion. The present study used the Binary Logit model to investigate the influence of labor force transfer, characteristics of rural households, location, and land market on agricultural land use conversion at rural household level. This study was conducted based on 329 valid questionnaires, which were obtained in Changshu, Rudong, and Tongshan counties, respectively representing the southern, middle and northern areas of Jiangsu Province. The results showed that land market participation, location, zonal difference and labor transfer had strong influences on agricultural land use conversion. The participation of land market had a strong positive effect on land use conversion, especially for the farmland converted to the fishpond. The nearer to the county seat, the more conversion of land use occurred. Particularly, the labor force transfer caused by wage employment decreased this conversion probability, while the labor transfer caused by self-employment led to more conversion; and the increasing of income from labor transfer increased the conversion. Moreover, land use con-versions demonstrated zonal difference, which were more in Rudong and Changshu counties than in Tongshan County, and the factors influencing this conversion were different in the three regions.

  15. A dynamic random effects multinomial logit model of household car ownership

    DEFF Research Database (Denmark)

    Bue Bjørner, Thomas; Leth-Petersen, Søren

    2007-01-01

    Using a large household panel we estimate demand for car ownership by means of a dynamic multinomial model with correlated random effects. Results suggest that the persistence in car ownership observed in the data should be attributed to both true state dependence and to unobserved heterogeneity ...

  16. What, Where, and Which? A Nested Logit Model for Dutch Housing Choice

    NARCIS (Netherlands)

    Blijie, B.; De Vries, J.J.

    2006-01-01

    In the Netherlands, changes on the housing market and overloading of the transport system require a policy that pays attention to both sides of the coin. To make projections of possible scenarios, under different policies, models are developed to study the transport system, the housing market and th

  17. A Smooth Transition Logit Model of the Effects of Deregulation in the Electricity Market

    DEFF Research Database (Denmark)

    Hurn, A.S.; Silvennoinen, Annastiina; Teräsvirta, Timo

    is illustrated by two applications. In the first one, the dynamic relationship between the US gasoline price and consumption is studied and possible asymmetries in it considered. The second application consists of modelling two well known Icelandic riverflow series, previously considered by many hydrologists...

  18. A Bayesian Approach for Nonlinear Structural Equation Models with Dichotomous Variables Using Logit and Probit Links

    Science.gov (United States)

    Lee, Sik-Yum; Song, Xin-Yuan; Cai, Jing-Heng

    2010-01-01

    Analysis of ordered binary and unordered binary data has received considerable attention in social and psychological research. This article introduces a Bayesian approach, which has several nice features in practical applications, for analyzing nonlinear structural equation models with dichotomous data. We demonstrate how to use the software…

  19. Logit Model of Motorcycle Accidents in the Philippines Considering Personal and Environmental Factors

    Directory of Open Access Journals (Sweden)

    Rosemary R. Seva

    2013-06-01

    Full Text Available The study aims to determine significant personal and environmental variables in predicting motorcycle accidents in the Philippines, compare the results with findings in other countries, and propose possible government interventions. Data were gathered from 177 participants through the use of a survey in a licensing center in the largest city in Metro Manila. Logistic regression was used to predict the likelihood of an accident from variables considered in the model. Three variables were found to be significant predictors of motorcycle accidents: age, driving behavior, and junction type. Younger drivers are more likely to be involved in accidents. The significance of age was unexpected because similar models found this to be insignificant. Driving behavior, specifically, committing violation predicts accident likelihood. Driving at t- and y-junctions also predicts motorcycle accidents. In the Philippines, a unique set of variables were found to predict motorcycle accidents. Although previous studies have established the effect of these variables to accident likelihood, the combination was unforeseen. Government agencies can focus on interventions directed at these three variables.

  20. Integrating geographic information systems and remote sensing with spatial econometric and mixed logit models for environmental valuation

    Science.gov (United States)

    Wells, Aaron Raymond

    This research focuses on the Emory and Obed Watersheds in the Cumberland Plateau in Central Tennessee and the Lower Hatchie River Watershed in West Tennessee. A framework based on market and nonmarket valuation techniques was used to empirically estimate economic values for environmental amenities and negative externalities in these areas. The specific techniques employed include a variation of hedonic pricing and discrete choice conjoint analysis (i.e., choice modeling), in addition to geographic information systems (GIS) and remote sensing. Microeconomic models of agent behavior, including random utility theory and profit maximization, provide the principal theoretical foundation linking valuation techniques and econometric models. The generalized method of moments estimator for a first-order spatial autoregressive function and mixed logit models are the principal econometric methods applied within the framework. The dissertation is subdivided into three separate chapters written in a manuscript format. The first chapter provides the necessary theoretical and mathematical conditions that must be satisfied in order for a forest amenity enhancement program to be implemented. These conditions include utility, value, and profit maximization. The second chapter evaluates the effect of forest land cover and information about future land use change on respondent preferences and willingness to pay for alternative hypothetical forest amenity enhancement options. Land use change information and the amount of forest land cover significantly influenced respondent preferences, choices, and stated willingness to pay. Hicksian welfare estimates for proposed enhancement options ranged from 57.42 to 25.53, depending on the policy specification, information level, and econometric model. The third chapter presents economic values for negative externalities associated with channelization that affect the productivity and overall market value of forested wetlands. Results of robust

  1. Logit dynamic for continuous strategy games: existence of solutions

    OpenAIRE

    Lahkar, R.

    2007-01-01

    We define the logit dynamic in the space of probability measures for a game with a compact and continuous strategy set. The original Burdett and Judd (1983) model of price dispersion comes under this framework. We then show that if the payoff functions of the game satisfy Lipschitz continuity under the strong topology in the space of signed measures, the logit dynamic admits a unique solution in the space of probability measures. As a corollary, we obtain that logit dynamic gen...

  2. Logit Analysis of Graduate Student Retention and Graduation.

    Science.gov (United States)

    Ott, Mary Diederich; Markewich, Theodore S.

    Logit analysis coupled with the BMDP4F computer program (Brown, 1983) was used to derive an appropriate model for the study of student retention and graduation. The model was then applied to graduate student retention and graduation data from the University of Maryland, College Park (UMCP). Logit analysis is a method of determining what effects…

  3. How do patient characteristics influence informal payments for inpatient and outpatient health care in Albania: Results of logit and OLS models using Albanian LSMS 2005

    Directory of Open Access Journals (Sweden)

    Tomini Sonila

    2011-05-01

    Full Text Available Abstract Background Informal payments for health care are common in most former communist countries. This paper explores the demand side of these payments in Albania. By using data from the Living Standard Measurement Survey 2005 we control for individual determinants of informal payments in inpatient and outpatient health care. We use these results to explain the main factors contributing to the occurrence and extent of informal payments in Albania. Methods Using multivariate methods (logit and OLS we test three models to explain informal payments: the cultural, economic and governance model. The results of logit models are presented here as odds ratios (OR and results from OLS models as regression coefficients (RC. Results Our findings suggest differences in determinants of informal payments in inpatient and outpatient care. Generally our results show that informal payments are dependent on certain characteristics of patients, including age, area of residence, education, health status and health insurance. However, they are less dependent on income, suggesting homogeneity of payments across income categories. Conclusions We have found more evidence for the validity of governance and economic models than for the cultural model.

  4. Analysis of sensory ratings data with cumulative link models

    DEFF Research Database (Denmark)

    Christensen, Rune Haubo Bojesen; Brockhoff, Per B.

    2013-01-01

    Examples of categorical rating scales include discrete preference, liking and hedonic rating scales. Data obtained on these scales are often analyzed with normal linear regression methods or with omnibus Pearson chi2 tests. In this paper we propose to use cumulative link models that allow...... for regression methods similar to linear models while respecting the categorical nature of the observations. We describe how cumulative link models are related to the omnibus chi2 tests and how they can lead to more powerful tests in the non-replicated setting. For replicated categorical ratings data we present...... a quasi-likelihood approach and a mixed effects approach both being extensions of cumulative link models. We contrast population-average and subject-specific interpretations based on these models and discuss how different approaches lead to different tests. In replicated settings, naive tests that ignore...

  5. The proportional odds cumulative incidence model for competing risks

    DEFF Research Database (Denmark)

    Eriksson, Frank; Li, Jianing; Scheike, Thomas

    2015-01-01

    We suggest an estimator for the proportional odds cumulative incidence model for competing risks data. The key advantage of this model is that the regression parameters have the simple and useful odds ratio interpretation. The model has been considered by many authors, but it is rarely used in pr...

  6. A metric for cross-sample comparisons using logit and probit

    DEFF Research Database (Denmark)

    Karlson, Kristian Bernt

    The logit model is a widely used regression technique in social research. However, the use and interpretation of coefficients from logit models have proven contentious. Problems arise because the mean and the variance of discrete variables cannot be separated. Logit coefficients are identified...... relative to an arbitrary scale, which makes the coefficients difficult both to interpret and to compare across groups or samples. Do differences in coefficients reflect true differences or differences in scales? This cross-sample comparison problem raises concerns for comparative research. However, we...... suggest a new correlation metric, derived from logit models, which gives new interpretation to the estimates of logit models (log odds-ratios). The metric leads the way to a reorientation of the use of logit models, because it helps to clarify what logit coefficients are and how and when logit...

  7. Study on Commercialization of Biogasification Systems in Ishikari Bay New Port Area - Proposal of Estimation Method of Collectable Amount of Food Waste by using Binary Logit Model -

    Science.gov (United States)

    Watanabe, Sho; Furuichi, Toru; Ishii, Kazuei

    This study proposed an estimation method for collectable amount of food waste considering the food waste generator's cooperation ratio ant the amount of food waste generation, and clarified the factors influencing the collectable amount of food waste. In our method, the cooperation ratio was calculated by using the binary logit model which is often used for the traffic multiple choice question. In order to develop a more precise binary logit model, the factors influencing on the cooperation ratio were extracted by a questionnaire survey asking food waste generator's intention, and the preference investigation was then conducted at the second step. As a result, the collectable amount of food waste was estimated to be 72 [t/day] in the Ishikari bay new port area under a condition of current collection system by using our method. In addition, the most critical factor influencing on the collectable amount of food waste was the treatment fee for households, and was the permitted mixture degree of improper materials for retail trade and restaurant businesses

  8. LOGIT and PROBIT Models in the Probability Analysis: Change in the Probability of Death from Celiac Disease Patients

    Directory of Open Access Journals (Sweden)

    Ondřej Šimpach

    2012-12-01

    Full Text Available It is estimated, that in the Czech Republic live about 40 000–50 000 people suffering from celiac disease, which is a disease of gluten intolerance. At the beginning of the independent Czech Republic, the life expectancy at birth of these people was quite low, because just in this period detailed diagnosis of this disease came fromabroad. With an increasing age the probability of death of these people grew faster than that of total population. The aim of this study is to analyse the probability of death of x-year old persons during next five years after the general medical examination in 1990 and 1995. Both analyses will be solved using LOGIT and PROBITmodels and the hypothesis claiming, that probability of death of x-year old person suffering from celiac disease decreased few years after the gaining of new medical knowledge from abroad will be confirmed or refused.

  9. A cumulative entropy method for distribution recognition of model error

    Science.gov (United States)

    Liang, Yingjie; Chen, Wen

    2015-02-01

    This paper develops a cumulative entropy method (CEM) to recognize the most suitable distribution for model error. In terms of the CEM, the Lévy stable distribution is employed to capture the statistical properties of model error. The strategies are tested on 250 experiments of axially loaded CFT steel stub columns in conjunction with the four national building codes of Japan (AIJ, 1997), China (DL/T, 1999), the Eurocode 4 (EU4, 2004), and United States (AISC, 2005). The cumulative entropy method is validated as more computationally efficient than the Shannon entropy method. Compared with the Kolmogorov-Smirnov test and root mean square deviation, the CEM provides alternative and powerful model selection criterion to recognize the most suitable distribution for the model error.

  10. A comparison of corporate distress prediction models in Brazil: hybrid neural networks, logit models and discriminant analysis

    Directory of Open Access Journals (Sweden)

    Juliana Yim

    2009-06-01

    Full Text Available This paper looks at the ability of a relatively new technique, hybrid ANN’s, to predict corporate distress in Brazil. These models are compared with traditional statistical techniques and conventional ANN models. The results suggest that hybrid neural networks outperform all other models in predicting firms in financial distress one year prior to the event. This suggests that for researchers, policymakers and others interested in early warning systems, hybrid networks may be a useful tool for predicting firm failure.

  11. A comparison of corporate distress prediction models in Brazil: hybrid neural networks, logit models and discriminant analysis

    Directory of Open Access Journals (Sweden)

    Juliana Yim

    2005-01-01

    Full Text Available This paper looks at the ability of a relatively new technique, hybrid ANN's, to predict corporate distress in Brazil. These models are compared with traditional statistical techniques and conventional ANN models. The results suggest that hybrid neural networks outperform all other models in predicting firms in financial distress one year prior to the event. This suggests that for researchers, policymakers and others interested in early warning systems, hybrid networks may be a useful tool for predicting firm failure.

  12. Cumulative Incidence Association Models for Bivariate Competing Risks Data.

    Science.gov (United States)

    Cheng, Yu; Fine, Jason P

    2012-03-01

    Association models, like frailty and copula models, are frequently used to analyze clustered survival data and evaluate within-cluster associations. The assumption of noninformative censoring is commonly applied to these models, though it may not be true in many situations. In this paper, we consider bivariate competing risk data and focus on association models specified for the bivariate cumulative incidence function (CIF), a nonparametrically identifiable quantity. Copula models are proposed which relate the bivariate CIF to its corresponding univariate CIFs, similarly to independently right censored data, and accommodate frailty models for the bivariate CIF. Two estimating equations are developed to estimate the association parameter, permitting the univariate CIFs to be estimated either parametrically or nonparametrically. Goodness-of-fit tests are presented for formally evaluating the parametric models. Both estimators perform well with moderate sample sizes in simulation studies. The practical use of the methodology is illustrated in an analysis of dementia associations.

  13. Estimating wetland vegetation abundance from Landsat-8 operational land imager imagery: a comparison between linear spectral mixture analysis and multinomial logit modeling methods

    Science.gov (United States)

    Zhang, Min; Gong, Zhaoning; Zhao, Wenji; Pu, Ruiliang; Liu, Ke

    2016-01-01

    Mapping vegetation abundance by using remote sensing data is an efficient means for detecting changes of an eco-environment. With Landsat-8 operational land imager (OLI) imagery acquired on July 31, 2013, both linear spectral mixture analysis (LSMA) and multinomial logit model (MNLM) methods were applied to estimate and assess the vegetation abundance in the Wild Duck Lake Wetland in Beijing, China. To improve mapping vegetation abundance and increase the number of endmembers in spectral mixture analysis, normalized difference vegetation index was extracted from OLI imagery along with the seven reflective bands of OLI data for estimating the vegetation abundance. Five endmembers were selected, which include terrestrial plants, aquatic plants, bare soil, high albedo, and low albedo. The vegetation abundance mapping results from Landsat OLI data were finally evaluated by utilizing a WorldView-2 multispectral imagery. Similar spatial patterns of vegetation abundance produced by both fully constrained LSMA algorithm and MNLM methods were observed: higher vegetation abundance levels were distributed in agricultural and riparian areas while lower levels in urban/built-up areas. The experimental results also indicate that the MNLM model outperformed the LSMA algorithm with smaller root mean square error (0.0152 versus 0.0252) and higher coefficient of determination (0.7856 versus 0.7214) as the MNLM model could handle the nonlinear reflection phenomenon better than the LSMA with mixed pixels.

  14. Examining driver behavior at the onset of yellow in a traffic simulator environment: Comparisons between random parameters and latent class logit models.

    Science.gov (United States)

    Savolainen, Peter T

    2016-11-01

    This study involves an examination of driver behavior at the onset of a yellow signal indication. Behavioral data were obtained from a driving simulator study that was conducted through the National Advanced Driving Simulator (NADS) laboratory at the University of Iowa. These data were drawn from a series of events during which study participants drove through a series of intersections where the traffic signals changed from the green to yellow phase. The resulting dataset provides potential insights into how driver behavior is affected by distracted driving through an experimental design that alternated handheld, headset, and hands-free cell phone use with "normal" baseline driving events. The results of the study show that male drivers ages 18-45 were more likely to stop. Participants were also more likely to stop as they became more familiar with the simulator environment. Cell phone use was found to some influence on driver behavior in this setting, though the effects varied significantly across individuals. The study also demonstrates two methodological approaches for dealing with unobserved heterogeneity across drivers. These include random parameters and latent class logit models, each of which analyze the data as a panel. The results show each method to provide significantly better fit than a pooled, fixed parameter model. Differences in terms of the context of these two approaches are discussed, providing important insights as to the differences between these modeling frameworks.

  15. Modelling the evolution and diversity of cumulative culture

    Science.gov (United States)

    Enquist, Magnus; Ghirlanda, Stefano; Eriksson, Kimmo

    2011-01-01

    Previous work on mathematical models of cultural evolution has mainly focused on the diffusion of simple cultural elements. However, a characteristic feature of human cultural evolution is the seemingly limitless appearance of new and increasingly complex cultural elements. Here, we develop a general modelling framework to study such cumulative processes, in which we assume that the appearance and disappearance of cultural elements are stochastic events that depend on the current state of culture. Five scenarios are explored: evolution of independent cultural elements, stepwise modification of elements, differentiation or combination of elements and systems of cultural elements. As one application of our framework, we study the evolution of cultural diversity (in time as well as between groups). PMID:21199845

  16. Modelling the evolution and diversity of cumulative culture.

    Science.gov (United States)

    Enquist, Magnus; Ghirlanda, Stefano; Eriksson, Kimmo

    2011-02-12

    Previous work on mathematical models of cultural evolution has mainly focused on the diffusion of simple cultural elements. However, a characteristic feature of human cultural evolution is the seemingly limitless appearance of new and increasingly complex cultural elements. Here, we develop a general modelling framework to study such cumulative processes, in which we assume that the appearance and disappearance of cultural elements are stochastic events that depend on the current state of culture. Five scenarios are explored: evolution of independent cultural elements, stepwise modification of elements, differentiation or combination of elements and systems of cultural elements. As one application of our framework, we study the evolution of cultural diversity (in time as well as between groups).

  17. A bivariate optimal replacement policy with cumulative repair cost limit under cumulative damage model

    Indian Academy of Sciences (India)

    MIN-T SAI LAI; SHIH-CHIH CHEN

    2016-05-01

    In this paper, a bivariate replacement policy (n, T) for a cumulative shock damage process is presented that included the concept of cumulative repair cost limit. The arrival shocks can be divided into two kinds of shocks. Each type-I shock causes a random amount of damage and these damages are additive. When the total damage exceeds a failure level, the system goes into serious failure. Type-II shock causes the system into minor failure and such a failure can be corrected by minimal repair. When a minor failure occurs, the repaircost will be evaluated and minimal repair is executed if the accumulated repair cost is less than a predetermined limit L. The system is replaced at scheduled time T, at n-th minor failure, or at serious failure. The long-term expected cost per unit time is derived using the expected costs as the optimality criterion. The minimum-cost policy is derived, and existence and uniqueness of the optimal n* and T* are proved. This bivariate optimal replacement policy (n, T) is showed to be better than the optimal T* and the optimal n* policy.

  18. Research on Online Shopping Choice Behavior Based on Nested Logit Model%基于巢式Logit模型的网上购物选择行为研究

    Institute of Scientific and Technical Information of China (English)

    蔡敏; 商滔

    2015-01-01

    基于Gumbel分布和多项Logit模型,提出建立顾客网上购物选择行为的巢式Logit模型,在SERVQUAL五维量表的基础上,设计了影响顾客购物选择行为的18个相关因素,同时将顾客购买行为分成共性部分和差异部分,采用极大似然法求解模型参数. 相比传统模型而言,巢式Logit模型具有更好的解释能力和稳定性,通过实例分析演示了模型的应用方法,为网上店铺优化服务质量提供了具体参考.%The nested Logit model of online shopping choice behavior is proposed based on Gumbel distribution and multinomial Logit model,and 18 related factors which affect customer's choice behavior are designed on the basis of five dimensional SERVQUAL scale.The shopping behavior is divided into common part and different part,maximum likelihood is used to solve the model parameters.Comparing to the traditional model,nested Logit model has better explanatory power and stability,through case study,the application of this model is demonstrated,which provide specific reference to optimize the quality of service for online stores.

  19. Model-checking techniques based on cumulative residuals.

    Science.gov (United States)

    Lin, D Y; Wei, L J; Ying, Z

    2002-03-01

    Residuals have long been used for graphical and numerical examinations of the adequacy of regression models. Conventional residual analysis based on the plots of raw residuals or their smoothed curves is highly subjective, whereas most numerical goodness-of-fit tests provide little information about the nature of model misspecification. In this paper, we develop objective and informative model-checking techniques by taking the cumulative sums of residuals over certain coordinates (e.g., covariates or fitted values) or by considering some related aggregates of residuals, such as moving sums and moving averages. For a variety of statistical models and data structures, including generalized linear models with independent or dependent observations, the distributions of these stochastic processes tinder the assumed model can be approximated by the distributions of certain zero-mean Gaussian processes whose realizations can be easily generated by computer simulation. Each observed process can then be compared, both graphically and numerically, with a number of realizations from the Gaussian process. Such comparisons enable one to assess objectively whether a trend seen in a residual plot reflects model misspecification or natural variation. The proposed techniques are particularly useful in checking the functional form of a covariate and the link function. Illustrations with several medical studies are provided.

  20. Mathematical modeling of detonation initiation via flow cumulation effects

    Science.gov (United States)

    Semenov, I.; Utkin, P.; Akhmedyanov, I.

    2016-07-01

    The paper concerns two problems connected with the idea of gaseous detonation initiation via flow cumulation effects and convergence of relatively weak shock waves (SW). The first one is the three-dimensional (3D) numerical investigation of shock-to-detonation transition (SDT) in methane-air mixture in a tube with parabolic contraction followed by the tube section of narrow diameter and conical expansion. The second problem is the numerical study of the start-up of the model small-scale hydrogen electrochemical pulse detonation engine with the use of electrical discharge generating the toroidal SW. The investigation is performed by means of numerical simulation with the use of modern high-performance computing systems.

  1. An empirical assessment of fixed and random parameter logit models using crash- and non-crash-specific injury data.

    Science.gov (United States)

    Ch Anastasopoulos, Panagiotis; Mannering, Fred L

    2011-05-01

    Traditional crash-severity modeling uses detailed data gathered after a crash has occurred (number of vehicles involved, age of occupants, weather conditions at the time of the crash, types of vehicles involved, crash type, occupant restraint use, airbag deployment, etc.) to predict the level of occupant injury. However, for prediction purposes, the use of such detailed data makes assessing the impact of alternate safety countermeasures exceedingly difficult due to the large number of variables that need to be known. Using 5-year data from interstate highways in Indiana, this study explores fixed and random parameter statistical models using detailed crash-specific data and data that include the injury outcome of the crash but not other detailed crash-specific data (only more general data are used such as roadway geometrics, pavement condition and general weather and traffic characteristics). The analysis shows that, while models that do not use detailed crash-specific data do not perform as well as those that do, random parameter models using less detailed data still can provide a reasonable level of accuracy.

  2. 混合logit模型及其在合作医疗保险模式选择中的应用%Mixed logit model and its application in insurance choices of the new rural cooperative medical system

    Institute of Scientific and Technical Information of China (English)

    贾伟娜; 王金金; 沈其君; 陈明; 张彦超; 朱胜军

    2011-01-01

    Objective To apply mixed logit model for analyzing the data of new rural cooperative medical with suitability and identify the factors affecting the residents' choices of insurance mode. Methods Hypothesis test of IIA was performed using the mogtest module of StatalO.O to test the eligibility of the condition. The mixed logit model was established to allow the parameters to vary in the population using SAS9.1 MDC module. Results The data in this study did not satisfy the HA assumption (P<0.01), so that the multinomial logit model was not applicable. The adjusted Estrella of the mixed logit model was 0.6658. Conclusion The mixed logit approach does not rely on the restrictive IIA assumption and allows for correlation patterns between choices and individual variation. This approach can help in the determination of the choices in new rural cooperative medical system.%目的 针对独立不相关(ILA)假设的限制,探讨混合logit模型在新型农村合作医疗中的适用性,并分析居民新型农村合作医疗保险模式选择的影响因素.方法 从选择项服从IIA假设人手,分析多项logit模型是否符合IIA假设条件.调用stata10.0软件的mlogtest模块进行IIA假设检验.再调用SAS9.1软件的MDC模块,建立了随机参数的混合logit模型.结果 在本次研究中,资料不能满足IIA假设(P<0.01),不能应用多项logit模型进行分析;建立的混合logit模型的调整Estrella值为0.6658.结论 混合logit方法完全摆脱了ILA假设的限制,允许选项之间存在相关性,同时可以体现不同居民保险模式选择的异质性,该方法在新型农村合作医疗中具有一定的适用性.

  3. Predicting Cumulative Watershed Effects using Spatially Explicit Models

    Science.gov (United States)

    MacDonald, L. H.; Litschert, S.

    2004-12-01

    Cumulative watershed effects /(CWEs/) result from the combined effects of land disturbances distributed over both space and time. They are of concern because changes in flow and sediment yields can adversely affect aquatic habitat, channel morphology, water yields, and water quality. The assessment procedures currently used by agencies such as the U.S. Forest Service generally rely on a lumped approach to quantify disturbance, despite the widespread recognition that site conditions and location do matter! The overall goal of our work is to develop spatially-explicit models to quantify changes in flow and sediment yields. Key objectives include: use of readily available GIS data; ease of use for resource managers with minimal GIS experience; modularity so that models can be added or updated; and allowing users to select the models and values for key parameters. The DeltaQ model calculates changes in peak, median, and low flows due to forest management activities and fires. Inputs include GIS data with disturbance polygons, an initial change in flow rate, and the time to recovery. Data from paired watershed studies are provided to help guide the user. The initial version of FORest Erosion Simulation Tools /(FOREST/) calculates sediment production from forest harvest, fires, and unpaved roads. Additional modules are being developed to deliver this sediment to the stream channel and route it to downstream locations. In accordance with our objectives, the user can predict sediment production rates using different empirical equations, assign an initial sediment production rate and a specified linear recovery period, or develop a look-up table based on local knowledge, published values, or data from other models such as WEPP. The required GIS layers vary according to the model/(s/) selected, but generally include past disturbances /(e.g., fires and timber harvest/), roads, and elevation. Outputs include GIS layers and text files that can be subjected to additional

  4. Winning in retail market games: relative profit and logit demand

    NARCIS (Netherlands)

    J. Hoogland (Jasper); M.M. de Weerdt (Mathijs); J.A. La Poutré (Han)

    2016-01-01

    textabstractWe examine retailers that maximize their relative profit, which is the (absolute) profit relative to the average profit of the other retailers. Customer behavior is modelled by a multinomial logit (MNL) demand model. Although retailers with low retail prices attract more customers than

  5. Reseacr h on the influence factors of private cars travel behavior based on the logit model%基于 Logit 模型的私家车出行影响因素分析

    Institute of Scientific and Technical Information of China (English)

    王志建; 王力; 刘小明

    2014-01-01

    文章旨在分析影响人们出行需求及行为的因素,并寻找其内在的规律性。在进行大量数据调查及分析的基础上,通过SPSS软件运用Logistic回归模型分析得出相关影响因素,并对相关影响因素进行分析,得出动态交通信息服务在一定程度上能够决定私家车出行路线选择,交通信息发布的实时性和准确性有待进一步提高,而且出行者更不愿意遇到交通事故或交通拥堵。通过分析动态交通信息背景下出行者交通出行行为的变化趋势,可以更好的缓解北京的交通拥堵情况。%The purpose of this paper is to analyze what factors were influencing people's travel demand and behavior , and find its inherent regularity.Based on a large amount of data investigations and analyses , and using the SPSS software and the Logistic Regression model , the related factors influencing traveler behavior are derived and analyzed .It has been concluded that the dynamic traffic information service decides the choice of the private car travel route to a certain ex-tent, the accuracy and real-time performance of released traffic information need to be further improved , and travelers are more reluctant to encounter a traffic accident or traffic jams .Through analysis of how to more effectively change travelers ’ behavior in the background of dynamic traffic information ,we can better alleviate traffic congestion in Beijing .

  6. A Cumulative Damage Reliability Model on the Basis of Contact Fatigue of the Rolling Bearing

    Institute of Scientific and Technical Information of China (English)

    HUANG Li

    2006-01-01

    A cumulative damage reliability model of contact fatigue of the rolling bearing is more identical with the actual conditions. It is put forward on the basis of contact fatigue life probability distribution of the rolling bearing that obey Weibull distribution and rest on the Miner cumulative damage theory. Finally a case is given to predict the reliability of bearing roller by using these models.

  7. Robust user equilibrium model based on cumulative prospect theory under distribution-free travel time

    Institute of Scientific and Technical Information of China (English)

    王伟; 孙会君; 吴建军

    2015-01-01

    The assumption widely used in the user equilibrium model for stochastic network was that the probability distributions of the travel time were known explicitly by travelers. However, this distribution may be unavailable in reality. By relaxing the restrictive assumption, a robust user equilibrium model based on cumulative prospect theory under distribution-free travel time was presented. In the absence of the cumulative distribution function of the travel time, the exact cumulative prospect value (CPV) for each route cannot be obtained. However, the upper and lower bounds on the CPV can be calculated by probability inequalities. Travelers were assumed to choose the routes with the best worst-case CPVs. The proposed model was formulated as a variational inequality problem and solved via a heuristic solution algorithm. A numerical example was also provided to illustrate the application of the proposed model and the efficiency of the solution algorithm.

  8. Cumulative t-link threshold models for the genetic analysis of calving ease scores

    Directory of Open Access Journals (Sweden)

    Tempelman Robert J

    2003-09-01

    Full Text Available Abstract In this study, a hierarchical threshold mixed model based on a cumulative t-link specification for the analysis of ordinal data or more, specifically, calving ease scores, was developed. The validation of this model and the Markov chain Monte Carlo (MCMC algorithm was carried out on simulated data from normally and t4 (i.e. a t-distribution with four degrees of freedom distributed populations using the deviance information criterion (DIC and a pseudo Bayes factor (PBF measure to validate recently proposed model choice criteria. The simulation study indicated that although inference on the degrees of freedom parameter is possible, MCMC mixing was problematic. Nevertheless, the DIC and PBF were validated to be satisfactory measures of model fit to data. A sire and maternal grandsire cumulative t-link model was applied to a calving ease dataset from 8847 Italian Piemontese first parity dams. The cumulative t-link model was shown to lead to posterior means of direct and maternal heritabilities (0.40 ± 0.06, 0.11 ± 0.04 and a direct maternal genetic correlation (-0.58 ± 0.15 that were not different from the corresponding posterior means of the heritabilities (0.42 ± 0.07, 0.14 ± 0.04 and the genetic correlation (-0.55 ± 0.14 inferred under the conventional cumulative probit link threshold model. Furthermore, the correlation (> 0.99 between posterior means of sire progeny merit from the two models suggested no meaningful rerankings. Nevertheless, the cumulative t-link model was decisively chosen as the better fitting model for this calving ease data using DIC and PBF.

  9. Flexible parametric modelling of cause-specific hazards to estimate cumulative incidence functions

    Science.gov (United States)

    2013-01-01

    Background Competing risks are a common occurrence in survival analysis. They arise when a patient is at risk of more than one mutually exclusive event, such as death from different causes, and the occurrence of one of these may prevent any other event from ever happening. Methods There are two main approaches to modelling competing risks: the first is to model the cause-specific hazards and transform these to the cumulative incidence function; the second is to model directly on a transformation of the cumulative incidence function. We focus on the first approach in this paper. This paper advocates the use of the flexible parametric survival model in this competing risk framework. Results An illustrative example on the survival of breast cancer patients has shown that the flexible parametric proportional hazards model has almost perfect agreement with the Cox proportional hazards model. However, the large epidemiological data set used here shows clear evidence of non-proportional hazards. The flexible parametric model is able to adequately account for these through the incorporation of time-dependent effects. Conclusion A key advantage of using this approach is that smooth estimates of both the cause-specific hazard rates and the cumulative incidence functions can be obtained. It is also relatively easy to incorporate time-dependent effects which are commonly seen in epidemiological studies. PMID:23384310

  10. Factors Influencing the Insured Wishes of Shaanxi Farmers Based on the Logit Model%基于Logit模型下影响陕西农民参保意愿的因素分析

    Institute of Scientific and Technical Information of China (English)

    李京芯; 夏显力

    2015-01-01

    From the factors affecting farmers' insured wishes for micro-insurance in Shaanxi Province, this paper conducted questionnaire, established Logit model and analyzed the main influencing factors. The results showed that, Shaanxi farmer's age, education level, cognitive level for insurance and risk profile in recent years had significant effect on the insured wishes of farmers, in which the age and education level had a negative correlation with the insured wishes and other factors had a positive correlation.%从影响陕西省农民参加小额保险影响因素出发,进行问卷调查,建立Logit模型,分析影响陕西省农民参保意愿的主要因素。研究结果表明,陕西农民的年龄、接受教育程度的高低、对于保险的认知水平和近三年风险状况等因素对农民的参保意愿影响显著,其中年龄和接受教育的程度的影响为负相关,其他影响因素为正相关。

  11. Cumulants of the three-state Potts model and of nonequilibrium models with C{sub 3v} symmetry

    Energy Technology Data Exchange (ETDEWEB)

    Tome, Tania [Instituto de Fisica, Universidade de Sao Paulo, Sao Paulo, SP (Brazil); Petri, Alberto [Istituto di Acustica O M Corbino, Consiglio Nazionale delle Ricerche, Via del Fosso del Cavaliere, Rome (Italy)

    2002-07-05

    The critical behaviour of two-dimensional stochastic lattice gas models with C{sub 3v} symmetry is analysed. We study the cumulants of the order parameter for the three-state (equilibrium) Potts model and for two irreversible models whose dynamic rules are invariant under the symmetry operations of the point group C{sub 3v}. By means of extensive numerical analysis of the phase transition we show that irreversibility does not affect the critical behaviour of the systems. In particular, we find that the Binder reduced fourth-order cumulant takes a universal value U* which is the same for the three-state Potts model and for the irreversible models. The same universal behaviour is observed for the reduced third-order cumulant. (author)

  12. Checking Fine and Gray subdistribution hazards model with cumulative sums of residuals

    DEFF Research Database (Denmark)

    Li, Jianing; Scheike, Thomas; Zhang, Mei Jie

    2015-01-01

    Recently, Fine and Gray (J Am Stat Assoc 94:496–509, 1999) proposed a semi-parametric proportional regression model for the subdistribution hazard function which has been used extensively for analyzing competing risks data. However, failure of model adequacy could lead to severe bias in parameter...... estimation, and only a limited contribution has been made to check the model assumptions. In this paper, we present a class of analytical methods and graphical approaches for checking the assumptions of Fine and Gray’s model. The proposed goodness-of-fit test procedures are based on the cumulative sums...

  13. Modelling the cumulative risk of a false-positive screening test.

    Science.gov (United States)

    Hubbard, Rebecca A; Miglioretti, Diana L; Smith, Robert A

    2010-10-01

    The goal of a screening test is to reduce morbidity and mortality through the early detection of disease; but the benefits of screening must be weighed against potential harms, such as false-positive (FP) results, which may lead to increased healthcare costs, patient anxiety, and other adverse outcomes associated with diagnostic follow-up procedures. Accurate estimation of the cumulative risk of an FP test after multiple screening rounds is important for program evaluation and goal setting, as well as informing individuals undergoing screening what they should expect from testing over time. Estimation of the cumulative FP risk is complicated by the existence of censoring and possible dependence of the censoring time on the event history. Current statistical methods for estimating the cumulative FP risk from censored data follow two distinct approaches, either conditioning on the number of screening tests observed or marginalizing over this random variable. We review these current methods, identify their limitations and possibly unrealistic assumptions, and propose simple extensions to address some of these limitations. We discuss areas where additional extensions may be useful. We illustrate methods for estimating the cumulative FP recall risk of screening mammography and investigate the appropriateness of modelling assumptions using 13 years of data collected by the Breast Cancer Surveillance Consortium (BCSC). In the BCSC data we found evidence of violations of modelling assumptions of both classes of statistical methods. The estimated risk of an FP recall after 10 screening mammograms varied between 58% and 77% depending on the approach used, with an estimate of 63% based on what we feel are the most reasonable modelling assumptions.

  14. 离散选择高阶段Logit模型的建模与预测--以上海城市外围大型居住社区为例%Advanced discrete choice Logit models and estimation and forecast:Case in large scale residential area on Shanghai city periphery

    Institute of Scientific and Technical Information of China (English)

    关金平; 杨东援

    2015-01-01

    The series of discrete choice Logit models, from basic to advanced are:binominal, multinomial, nested, cross nested, mixed Logit model, latent class model and hybrid choice model with latent variables and dynamic Logit model. Developing and using advanced Logit models is the latest key technique when the residents’mode choice is studied in the rapid urbanization process. As a professor at University of California, Berkeley, Daniel L McFadden contributes to the dis-crete choice theory and method and won the Nobel Economic Prize in 2000. From year 2012 to 2014, the author worked with Joan Walker and Kenneth Train seized the opportunity of learning the series of Logit models in-depth. With theory applying to practice, this paper presents the advanced Logit models and the results in the case of the large scale residential area on Shanghai city periphery in the period of Chinese“the Twelfth Five-Year Plan”and the process of rapid urbanization. With the data from the residents in the large scale residential area on Shanghai city periphery, an advanced Logit mode choice model’s estimation and forecast are developed. Results show that in the six policy scenarios, building retails closer improves the residents’travel quality the most and supports transit priority. Combining theory with practice, advanced Logit model can support policy decision making process quantitatively and excellently.%离散选择Logit系列模型的发展层次顺序是:二项、多项、巢式与交叉巢式、混合Logit(连续及离散潜在种类模型)、嵌入潜在变量的混合选择模型、动态Logit模型。建立高阶段Logit模型算法是当前研究快速城市化进程中居民交通方式选择与预测的最新技术手段。2000年,Daniel M教授,以“对分析离散选择的原理和方法所做出的发展和贡献”获诺贝尔经济学奖。2012—2014年,作者深入学习了离散选择Logit系列模型及标定预测,结合上海城市外围大

  15. Licensing to Market with Logit Demand Functions

    Institute of Scientific and Technical Information of China (English)

    YAN Qing-you; ZHU Li-li

    2009-01-01

    This paper studies the licensing of a brand innovation to a monopoly in an uncovered market characterized by a logit demand framework. The innovator is an outsider to the market and sells the license via fixed-fee, royalty or their combinations. It is shown that the license occurs irrespective of whether the utility of the new brand is improved or not, and that the optimal licensing policy for the innovator is fixed-fee only. Ultimately, the monopoly produces both the old and the new brand products, even in the case of utility-improving brand innovation. In addition, the incentive for the innovator was examined.

  16. Walking Affect Area of Rail Transit Station Based on Multinomial Logit Model%基于多项Logit模型的轨道交通站点步行接驳范围

    Institute of Scientific and Technical Information of China (English)

    张宁; 戴洁; 张晓军

    2012-01-01

    To determine the reasonable walking access area of rail transport station, it is necessary to analyze the walking environment, travel time, cost, comfort and other factors. The multinomial Logit model is used to establishment a model of transportation choice which will link all the factors and determine the pedestrian area of rail transit station based on the principle of equal utility. On the surveyed data of a rail transit station in Nanjing City, and by using the TRANSCAD software, the walking area of metro station is calculated. Through a comparison between the traditional walking areas and the surveyed data, it is clear that the model is effective and reasonable, and could provide references for the planning, selection and evaluation of urban rail transit.%在分析步行环境、出行时间、出行费用等出行特征影响因素的基础上,运用多项Logit模型建立了居民出行方式选择模型,根据效用相当原则确定城市轨道交通步行接驳范围.根据某城市的某个轨道交通站点的调查数据,利用本文提出的方法计算该站点的步行接驳范围,与传统的接驳范围经验取值及意向调查结果进行比较,发现计算结果与调查统计结果较为一致.计算结果表明,该计算方法是有效合理的,能够为城市轨道交通站点的规划、选址和评价提供依据.

  17. Using continuation-ratio logits to analyze the variation of the age composition of fish catches

    DEFF Research Database (Denmark)

    Kvist, Trine; Gislason, Henrik; Thyregod, Poul

    2000-01-01

    continuation- ratio logits and the theory for generalized linear mixed models. Continuation-ratio logits are designed far ordered multinomial response and have the feature that the associated log-likelihood splits into separate terms for each category levels, Thus, generalized linear mixed models can...... of the sampling is desirable, because it leads to better estimates of the age composition, and the corresponding variances and covariances. The analysis is impeded by the fact that the response is ordered categorical. This paper introduces an easily applicable method to analyze such data. The method combines...... be applied separately to each level of the logits. The method is illustrated by the analysis of age-composition data collected from the Danish sandeel fishery in the North Sea in 1993. The significance of possible sources of variation is evaluated, and formulae for estimating the proportions of each age...

  18. Effects of task complexity and time pressure on activity-travel choices: heteroscedastic logit model and activity-travel simulator experiment

    NARCIS (Netherlands)

    Chen, C.; Chorus, C.G.; Molin, E.J.E.; Van Wee, G.P.

    2015-01-01

    This paper derives, estimates and applies a discrete choice model of activity-travel behaviour that accommodates potential effects of task complexity and time pressure on decision-making. To the best of our knowledge, this is the first time that both factors (task complexity and time pressure) are

  19. Effects of task complexity and time pressure on activity-travel choices: heteroscedastic logit model and activity-travel simulator experiment

    NARCIS (Netherlands)

    Chen, C.; Chorus, C.G.; Molin, E.J.E.; Van Wee, G.P.

    2015-01-01

    This paper derives, estimates and applies a discrete choice model of activity-travel behaviour that accommodates potential effects of task complexity and time pressure on decision-making. To the best of our knowledge, this is the first time that both factors (task complexity and time pressure) are j

  20. An analytical model for cumulative infiltration into a dual-permeability media

    Science.gov (United States)

    Peyrard, Xavier; Lassabatere, Laurent; Angulo-Jaramillo, Rafael; Simunek, Jiri

    2010-05-01

    Modeling of water infiltration into the vadose zone is important for better understanding of movement of water-transported contaminants. There is a great need to take into account the soil heterogeneity and, in particular, the presence of macropores or cracks that could generate preferential flow. Several mathematical models have been proposed to describe unsaturated flow through heterogeneous soils. The dual-permeability model assumes that flow is governed by Richards equation in both porous regions (matrix and fractures). Water can be exchanged between the two regions following a first-order rate law. A previous study showed that the influence of the hydraulic conductivity of the matrix/macropore interface had a little influence on cumulative infiltration at the soil surface. As a result, one could consider the surface infiltration for a specific case of no water exchange between the fracture and matrix regions (a case of zero interfacial hydraulic conductivity). In such a case, water infiltration can be considered to be the sum of the cumulative infiltrations into the matrix and the fractures. On the basis of analytical models for each sub domain (matrix and fractures), an analytical model is proposed for the entire dual-porosity system. A sensitivity analysis is performed to characterize the influence of several factors, such as the saturated hydraulic conductivity ratio, the water pressure scale parameter ratio, and the saturated volumetric water content scale ratio, on the total cumulative infiltration. Such an analysis greatly helps in quantifying the impact of macroporosity and fractures on water infiltration, which can be of great interest for hydrological models.

  1. On scheduling models for the frequency interval assignment problem with cumulative interferences

    Science.gov (United States)

    Kiatmanaroj, Kata; Artigues, Christian; Houssin, Laurent

    2016-05-01

    In this article, models and methods for solving a real-life frequency assignment problem based on scheduling theory are investigated. A realistic frequency assignment problem involving cumulative interference constraints in which the aim is to maximize the number of assigned users is considered. If interferences are assumed to be binary, a multiple carrier frequency assignment problem can be treated as a disjunctive scheduling problem since a user requesting a number of contiguous frequencies can be considered as a non-preemptive task with a processing time, and two interfering users can be modelled through a disjunctive constraint on the corresponding tasks. A binary interference version of the problem is constructed and a disjunctive scheduling model is derived. Based on the binary representation, two models are proposed. The first one relies on an interference matrix and the second one considers maximal cliques. A third, cumulative, model that yields a new class of scheduling problems is also proposed. Computational experiments show that the case-study frequency assignment problem can be solved efficiently with disjunctive scheduling techniques.

  2. 基于 Logi t模型的体育产业上市公司再融资研究%Study on Sports Industry Corporate Refinancing Based on the Logit Model

    Institute of Scientific and Technical Information of China (English)

    张易; 李隋; 熊燕

    2014-01-01

    By building Logit models ,empirically studies the influencing factors of sports industry companies refinancing and refinancing differences impact on company performance .The result shows that when the quoted companies choose equity financing ,cash flow ,net profit and indus-tries will affect it ;quoted companies whether debt financing primarily affected by company size and debt ratio .Meanwhile debt financing of quoted companies would have a negative impact on company performance ,equity financing no significant impact on its performance ,sports quoted companies to get out of the current financial difficulties need more ways to use equity financing to raise funds .%通过构建Logit模型,实证研究再融资过程中,体育产业公司再融资方式的影响因素及再融资方式差异性对公司业绩的影响。研究发现,体育产业上市公司选择股权融资时,公司的现金流、净利润及行业属性等因素会对其产生影响;上市公司是否进行债权融资主要受到公司规模以及负债率的影响。体育类上市公司进行债权融资会对公司业绩产生负面影响,股权融资对其绩效没有显著性影响,体育类上市公司要走出当前财务困境需要多使用股权融资的方式筹集资金。

  3. Modeling Joint Exposures and Health Outcomes for Cumulative Risk Assessment: The Case of Radon and Smoking

    Directory of Open Access Journals (Sweden)

    Jonathan I. Levy

    2011-09-01

    Full Text Available Community-based cumulative risk assessment requires characterization of exposures to multiple chemical and non-chemical stressors, with consideration of how the non-chemical stressors may influence risks from chemical stressors. Residential radon provides an interesting case example, given its large attributable risk, effect modification due to smoking, and significant variability in radon concentrations and smoking patterns. In spite of this fact, no study to date has estimated geographic and sociodemographic patterns of both radon and smoking in a manner that would allow for inclusion of radon in community-based cumulative risk assessment. In this study, we apply multi-level regression models to explain variability in radon based on housing characteristics and geological variables, and construct a regression model predicting housing characteristics using U.S. Census data. Multi-level regression models of smoking based on predictors common to the housing model allow us to link the exposures. We estimate county-average lifetime lung cancer risks from radon ranging from 0.15 to 1.8 in 100, with high-risk clusters in areas and for subpopulations with high predicted radon and smoking rates. Our findings demonstrate the viability of screening-level assessment to characterize patterns of lung cancer risk from radon, with an approach that can be generalized to multiple chemical and non-chemical stressors.

  4. The early origins of the logit model

    NARCIS (Netherlands)

    Cramer, J.S.

    2004-01-01

    This paper describes the origins of the logistic function and its history up to its adoption in bio-assay and the beginning of its wider acceptance in statistics, ca. 1950. The function was probably first invented in 1838 to describe population growth by the Belgian mathematician Verhulst, who gave

  5. BLIND AND COMPLETE MODELING OF LINEAR SYSTEMS USING THIRD ORDER CUMULANTS

    Institute of Scientific and Technical Information of China (English)

    2007-01-01

    This paper presents a novel approach to structure determination of linear systems along with the choice of system orders and parameters. AutoRegressive (AR), Moving Average (MA) or AutoRegressive-Moving Average (ARMA) model structure can be extracted blindly from the Third Order Cumulants (TOC) of the system output measurements, where the unknown system is driven by an unobservable stationary independent identically distributed (i.i.d.) non-Gaussian signal. By means of the system order recursion, whether the system has an AR structure or has AR part of an ARMA structure is firstly investigated. MA features in the TOC domain is then applied as a threshold to decide if the system is an MA model or has MA part of an ARMA model. Numerical simulations illustrate the generality of the proposed blind structure identification methodology that may serve as a guideline for blind linear system modeling.

  6. Modeling the cumulative genetic risk for multiple sclerosis from genome-wide association data.

    Science.gov (United States)

    Wang, Joanne H; Pappas, Derek; De Jager, Philip L; Pelletier, Daniel; de Bakker, Paul Iw; Kappos, Ludwig; Polman, Chris H; Chibnik, Lori B; Hafler, David A; Matthews, Paul M; Hauser, Stephen L; Baranzini, Sergio E; Oksenberg, Jorge R

    2011-01-18

    Multiple sclerosis (MS) is the most common cause of chronic neurologic disability beginning in early to middle adult life. Results from recent genome-wide association studies (GWAS) have substantially lengthened the list of disease loci and provide convincing evidence supporting a multifactorial and polygenic model of inheritance. Nevertheless, the knowledge of MS genetics remains incomplete, with many risk alleles still to be revealed. We used a discovery GWAS dataset (8,844 samples, 2,124 cases and 6,720 controls) and a multi-step logistic regression protocol to identify novel genetic associations. The emerging genetic profile included 350 independent markers and was used to calculate and estimate the cumulative genetic risk in an independent validation dataset (3,606 samples). Analysis of covariance (ANCOVA) was implemented to compare clinical characteristics of individuals with various degrees of genetic risk. Gene ontology and pathway enrichment analysis was done using the DAVID functional annotation tool, the GO Tree Machine, and the Pathway-Express profiling tool. In the discovery dataset, the median cumulative genetic risk (P-Hat) was 0.903 and 0.007 in the case and control groups, respectively, together with 79.9% classification sensitivity and 95.8% specificity. The identified profile shows a significant enrichment of genes involved in the immune response, cell adhesion, cell communication/signaling, nervous system development, and neuronal signaling, including ionotropic glutamate receptors, which have been implicated in the pathological mechanism driving neurodegeneration. In the validation dataset, the median cumulative genetic risk was 0.59 and 0.32 in the case and control groups, respectively, with classification sensitivity 62.3% and specificity 75.9%. No differences in disease progression or T2-lesion volumes were observed among four levels of predicted genetic risk groups (high, medium, low, misclassified). On the other hand, a significant

  7. EPA's SHEDS-multimedia model: children's cumulative pyrethroid exposure estimates and evaluation against NHANES biomarker data.

    Science.gov (United States)

    Xue, Jianping; Zartarian, Valerie; Tornero-Velez, Rogelio; Tulve, Nicolle S

    2014-12-01

    The U.S. EPA's SHEDS-Multimedia model was applied to enhance the understanding of children's exposures and doses to multiple pyrethroid pesticides, including major contributing chemicals and pathways. This paper presents combined dietary and residential exposure estimates and cumulative doses for seven commonly used pyrethroids, and comparisons of model evaluation results with NHANES biomarker data for 3-PBA and DCCA metabolites. Model input distributions were fit to publicly available pesticide usage survey data, NHANES, and other studies, then SHEDS-Multimedia was applied to estimate total pyrethroid exposures and doses for 3-5 year olds for one year variability simulations. For dose estimations we used a pharmacokinetic model and two approaches for simulating dermal absorption. SHEDS-Multimedia predictions compared well to NHANES biomarker data: ratios of 3-PBA observed data to SHEDS-Multimedia modeled results were 0.88, 0.51, 0.54 and 1.02 for mean, median, 95th, and 99th percentiles, respectively; for DCCA, the ratios were 0.82, 0.53, 0.56, and 0.94. Modeled time-averaged cumulative absorbed dose of the seven pyrethroids was 3.1 nmol/day (versus 8.4 nmol/day for adults) in the general population (residential pyrethroid use and non-use homes) and 6.7 nmol/day (versus 10.5 nmol/day for adults) in the simulated residential pyrethroid use population. For the general population, contributions to modeled cumulative dose by chemical were permethrin (60%), cypermethrin (22%), and cyfluthrin (16%); for residential use homes, contributions were cypermethrin (49%), permethrin (29%), and cyfluthrin (17%). The primary exposure route for 3-5 year olds in the simulated residential use population was non-dietary ingestion exposure; whereas for the simulated general population, dietary exposure was the primary exposure route. Below the 95th percentile, the major exposure pathway was dietary for the general population; non-dietary ingestion was the major pathway starting below

  8. [Assessment on the ecological suitability in Zhuhai City, Guangdong, China, based on minimum cumulative resistance model].

    Science.gov (United States)

    Li, Jian-fei; Li, Lin; Guo, Luo; Du, Shi-hong

    2016-01-01

    Urban landscape has the characteristics of spatial heterogeneity. Because the expansion process of urban constructive or ecological land has different resistance values, the land unit stimulates and promotes the expansion of ecological land with different intensity. To compare the effect of promoting and hindering functions in the same land unit, we firstly compared the minimum cumulative resistance value of promoting and hindering functions, and then looked for the balance of two landscape processes under the same standard. According to the ecology principle of minimum limit factor, taking the minimum cumulative resistance analysis method under two expansion processes as the evaluation method of urban land ecological suitability, this research took Zhuhai City as the study area to estimate urban ecological suitability by relative evaluation method with remote sensing image, field survey, and statistics data. With the support of ArcGIS, five types of indicators on landscape types, ecological value, soil erosion sensitivity, sensitivity of geological disasters, and ecological function were selected as input parameters in the minimum cumulative resistance model to compute urban ecological suitability. The results showed that the ecological suitability of the whole Zhuhai City was divided into five levels: constructive expansion prohibited zone (10.1%), constructive expansion restricted zone (32.9%), key construction zone (36.3%), priority development zone (2.3%), and basic cropland (18.4%). Ecological suitability of the central area of Zhuhai City was divided into four levels: constructive expansion prohibited zone (11.6%), constructive expansion restricted zone (25.6%), key construction zone (52.4%), priority development zone (10.4%). Finally, we put forward the sustainable development framework of Zhuhai City according to the research conclusion. On one hand, the government should strictly control the development of the urban center area. On the other hand, the

  9. Cumulative atomic multipole moments complement any atomic charge model to obtain more accurate electrostatic properties

    Science.gov (United States)

    Sokalski, W. A.; Shibata, M.; Ornstein, R. L.; Rein, R.

    1992-01-01

    The quality of several atomic charge models based on different definitions has been analyzed using cumulative atomic multipole moments (CAMM). This formalism can generate higher atomic moments starting from any atomic charges, while preserving the corresponding molecular moments. The atomic charge contribution to the higher molecular moments, as well as to the electrostatic potentials, has been examined for CO and HCN molecules at several different levels of theory. The results clearly show that the electrostatic potential obtained from CAMM expansion is convergent up to R-5 term for all atomic charge models used. This illustrates that higher atomic moments can be used to supplement any atomic charge model to obtain more accurate description of electrostatic properties.

  10. Cumulative Impact Evaluation in Central Part of Liepaja with Comulative Pollution Index Method and Air Pollution Dispersion Modelling

    Directory of Open Access Journals (Sweden)

    Kalniņš Viesturs

    2015-07-01

    Full Text Available Cumulative impact evaluation is one of the most actual problems in air quality monitoring. At the same time, it is also the most problematic factor to evaluate due to lack of appropriate methodology. The aim of this study was to assess the opportunity to use a new method – Cumulative Pollution Index (CPI in cumulative impact calculation from two different sets of data – bioindication survey with Index of Atmospheric Purity method and air pollution dispersion modelling. Results show that the usage of modelling data, instead of measurements, in cumulative impact evaluation can be quite difficult due to the fact that dispersion models not always give sufficiently accurate data. Despite the issues with modelling specifics, the use of dispersion modelling in CPI calculation shows that the use of this approach not only gives plausible data – obtained values correlate with pollution level and forming strong clustering in spatial distribution, but also reveals new facts about cumulative impact – demonstrates the city microclimate importance in forming of cumulative effect due to geometry of street canyons.

  11. Fast and accurate calculations for cumulative first-passage time distributions in Wiener diffusion models

    DEFF Research Database (Denmark)

    Blurton, Steven Paul; Kesselmeier, M.; Gondan, Matthias

    2012-01-01

    related work on the density of first-passage times [Navarro, D.J., Fuss, I.G. (2009). Fast and accurate calculations for first-passage times in Wiener diffusion models. Journal of Mathematical Psychology, 53, 222-230]. Two representations exist for the distribution, both including infinite series. We......We propose an improved method for calculating the cumulative first-passage time distribution in Wiener diffusion models with two absorbing barriers. This distribution function is frequently used to describe responses and error probabilities in choice reaction time tasks. The present work extends...... derive upper bounds for the approximation error resulting from finite truncation of the series, and we determine the number of iterations required to limit the error below a pre-specified tolerance. For a given set of parameters, the representation can then be chosen which requires the least...

  12. Performance of cumulant-based rank reduction estimator in presence of unexpected modeling errors

    Institute of Scientific and Technical Information of China (English)

    王鼎

    2015-01-01

    Compared with the rank reduction estimator (RARE) based on second-order statistics (called SOS-RARE), the RARE based on fourth-order cumulants (referred to as FOC-RARE) can handle more sources and restrain the negative impacts of the Gaussian colored noise. However, the unexpected modeling errors appearing in practice are known to significantly degrade the performance of the RARE. Therefore, the direction-of-arrival (DOA) estimation performance of the FOC-RARE is quantitatively derived. The explicit expression for direction-finding (DF) error is derived via the first-order perturbation analysis, and then the theoretical formula for the mean square error (MSE) is given. Simulation results demonstrate the validation of the theoretical analysis and reveal that the FOC-RARE is more robust to the unexpected modeling errors than the SOS-RARE.

  13. Comparison of competing risks models based on cumulative incidence function in analyzing time to cardiovascular diseases.

    Science.gov (United States)

    Dianatkhah, Minoo; Rahgozar, Mehdi; Talaei, Mohammad; Karimloua, Masoud; Sadeghi, Masoumeh; Oveisgharan, Shahram; Sarrafzadegan, Nizal

    2014-01-01

    Competing risks arise when the subject is exposed to more than one cause of failure. Data consists of the time that the subject failed and an indicator of which risk caused the subject to fail. With three approaches consisting of Fine and Gray, binomial, and pseudo-value, all of which are directly based on cumulative incidence function, cardiovascular disease data of the Isfahan Cohort Study were analyzed. Validity of proportionality assumption for these approaches is the basis for selecting appropriate models. Such as for the Fine and Gray model, establishing proportionality assumption is necessary. In the binomial approach, a parametric, non-parametric, or semi-parametric model was offered according to validity of assumption. However, pseudo-value approaches do not need to establish proportionality. Following fitting the models to data, slight differences in parameters and variances estimates were seen among models. This showed that semi-parametric multiplicative model and the two models based on pseudo-value approach could be used for fitting this kind of data. We would recommend considering the use of competing risk models instead of normal survival methods when subjects are exposed to more than one cause of failure.

  14. Constrained parametric model for simultaneous inference of two cumulative incidence functions.

    Science.gov (United States)

    Shi, Haiwen; Cheng, Yu; Jeong, Jong-Hyeon

    2013-01-01

    We propose a parametric regression model for the cumulative incidence functions (CIFs) commonly used for competing risks data. The model adopts a modified logistic model as the baseline CIF and a generalized odds-rate model for covariate effects, and it explicitly takes into account the constraint that a subject with any given prognostic factors should eventually fail from one of the causes such that the asymptotes of the CIFs should add up to one. This constraint intrinsically holds in a nonparametric analysis without covariates, but is easily overlooked in a semiparametric or parametric regression setting. We hence model the CIF from the primary cause assuming the generalized odds-rate transformation and the modified logistic function as the baseline CIF. Under the additivity constraint, the covariate effects on the competing cause are modeled by a function of the asymptote of the baseline distribution and the covariate effects on the primary cause. The inference procedure is straightforward by using the standard maximum likelihood theory. We demonstrate desirable finite-sample performance of our model by simulation studies in comparison with existing methods. Its practical utility is illustrated in an analysis of a breast cancer dataset to assess the treatment effect of tamoxifen, adjusting for age and initial pathological tumor size, on breast cancer recurrence that is subject to dependent censoring by second primary cancers and deaths.

  15. Generalized linear models for categorical and continuous limited dependent variables

    CERN Document Server

    Smithson, Michael

    2013-01-01

    Introduction and OverviewThe Nature of Limited Dependent VariablesOverview of GLMsEstimation Methods and Model EvaluationOrganization of This BookDiscrete VariablesBinary VariablesLogistic RegressionThe Binomial GLMEstimation Methods and IssuesAnalyses in R and StataExercisesNominal Polytomous VariablesMultinomial Logit ModelConditional Logit and Choice ModelsMultinomial Processing Tree ModelsEstimation Methods and Model EvaluationAnalyses in R and StataExercisesOrdinal Categorical VariablesModeling Ordinal Variables: Common Practice versus Best PracticeOrdinal Model AlternativesCumulative Mod

  16. Flexible parametric modelling of the cause-specific cumulative incidence function.

    Science.gov (United States)

    Lambert, Paul C; Wilkes, Sally R; Crowther, Michael J

    2016-12-22

    Competing risks arise with time-to-event data when individuals are at risk of more than one type of event and the occurrence of one event precludes the occurrence of all other events. A useful measure with competing risks is the cause-specific cumulative incidence function (CIF), which gives the probability of experiencing a particular event as a function of follow-up time, accounting for the fact that some individuals may have a competing event. When modelling the cause-specific CIF, the most common model is a semi-parametric proportional subhazards model. In this paper, we propose the use of flexible parametric survival models to directly model the cause-specific CIF where the effect of follow-up time is modelled using restricted cubic splines. The models provide smooth estimates of the cause-specific CIF with the important advantage that the approach is easily extended to model time-dependent effects. The models can be fitted using standard survival analysis tools by a combination of data expansion and introducing time-dependent weights. Various link functions are available that allow modelling on different scales and have proportional subhazards, proportional odds and relative absolute risks as particular cases. We conduct a simulation study to evaluate how well the spline functions approximate subhazard functions with complex shapes. The methods are illustrated using data from the European Blood and Marrow Transplantation Registry showing excellent agreement between parametric estimates of the cause-specific CIF and those obtained from a semi-parametric model. We also fit models relaxing the proportional subhazards assumption using alternative link functions and/or including time-dependent effects. Copyright © 2016 John Wiley & Sons, Ltd.

  17. A semiparametric censoring bias model for estimating the cumulative risk of a false-positive screening test under dependent censoring.

    Science.gov (United States)

    Hubbard, Rebecca A; Miglioretti, Diana L

    2013-03-01

    False-positive test results are among the most common harms of screening tests and may lead to more invasive and expensive diagnostic testing procedures. Estimating the cumulative risk of a false-positive screening test result after repeat screening rounds is, therefore, important for evaluating potential screening regimens. Existing estimators of the cumulative false-positive risk are limited by strong assumptions about censoring mechanisms and parametric assumptions about variation in risk across screening rounds. To address these limitations, we propose a semiparametric censoring bias model for cumulative false-positive risk that allows for dependent censoring without specifying a fixed functional form for variation in risk across screening rounds. Simulation studies demonstrated that the censoring bias model performs similarly to existing models under independent censoring and can largely eliminate bias under dependent censoring. We used the existing and newly proposed models to estimate the cumulative false-positive risk and variation in risk as a function of baseline age and family history of breast cancer after 10 years of annual screening mammography using data from the Breast Cancer Surveillance Consortium. Ignoring potential dependent censoring in this context leads to underestimation of the cumulative risk of false-positive results. Models that provide accurate estimates under dependent censoring are critical for providing appropriate information for evaluating screening tests.

  18. Estimating multi-factor cumulative watershed effects on fish populations with an individual-based model

    Science.gov (United States)

    Bret C. Harvey; Steven F. Railsback

    2007-01-01

    While the concept of cumulative effects is prominent in legislation governing environmental management, the ability to estimate cumulative effects remains limited. One reason for this limitation is that important natural resources such as fish populations may exhibit complex responses to changes in environmental conditions, particularly to alteration of multiple...

  19. 基于多项Logit选择模型的在线渠道价格促销效应实证研究%Empirical Study on Online Channel Price Promotion Effect Based on Multinomial Logit Model

    Institute of Scientific and Technical Information of China (English)

    向禹辰; 陈洁; 赵昕

    2011-01-01

    在线渠道下,不同品牌的价格折扣促销的差异性会引起在线消费者品牌选择行为变化.同时,在线的价格比较机制也增加了消费者价格敏感度,如果不分离出这一重要的促销效应,那么会产生估计偏差,影响模型的预测能力.本文首先回顾品牌选择的离散模型中价格促销的研究脉络;然后构建在线渠道消费者品牌选择离散Logit模型;接着在对中国某电子商务公司的消费者实际购买可乐的面板数据分析的基础上,研究价格折扣对于该公司消费者品牌选择行为的影响效应,研究发现:(1)如果不引入价格折扣促销因素,将会过高估计价格的影响;(2)价格折扣促销对于消费者网上品牌选择有显著的影响,且影响为正效应.文章最后剖析价格折扣对在线渠道的消费者品牌选择的行为影响机理,并提出未来的研究方向.%The difference of various brands of promotional price discounts, in online channels, results in online consumers' changes in brand choice behavior.Online price comparison mechanism aids the consumer price sensitivity,meanwhile the lack of this important promotional effect leads to estimation bias as well as impact on model forecasting ability.First of all, this paper recalls the context of pricing promotion by the discrete model of brand choice, establishes Multinomial Logit discrete choice model for online consumers, studies the impact of price discounts for online consumers' brand choice, whose results are presented using the panel data analysis of actual Cola purchasing by consumers in one e-commerce company in China.Our results reveal the following.(1) Overestimation on the effect of price will be caused without considering promotional factors of price discounts.(2) Price discount has significant effect on brand choice of online consumers.A behavior-impacting mechanism is listed on the online consumer brand choice of by price discounts, with future research direction.

  20. Consumer’s revealed preferences for yogurt purchase in Catalonia: A Generalized Multinomial Logit Approach

    OpenAIRE

    Hellai, Wajdi; Kallas, Zein; Gil Roig, José María

    2015-01-01

    The revealed-preferences of yogurt consumption in Catalonia was analyzed in order to identify the attributes affecting the purchase behavior and to suggest reliable marketing strategies for the yogurt industry. The Discrete Choice Modelling was applied using the Generalized Multinomial Logit Model (G-MNL) calibrated on 52 weeks of yogurt purchases by 987 households that belongs to the home-scan database of ©Kantar World panel during 2012. Eight different yogurt categories were created w...

  1. Logit-log evaluation of planar yeast estrogen screens.

    Science.gov (United States)

    Schick, Dinah; Schwack, Wolfgang

    2017-08-04

    Receptor assays like the yeast estrogen screen (YES) performed in microtiter plates normally provide dose-response curves with a sigmoidal shape in semi-log plots. Such sigmoidal plots can be linearized by the logit function resulting in logit-log plots, as mainly known for the evaluation of enzyme-linked immunosorbent assays and radioimmunoassays. Since the planar yeast estrogen screen (pYES) represents the transfer of the receptor assay YES to high-performance thin-layer chromatography (HPTLC), it was assumed to obtain sigmoidal shaped dose-response curves from the measured signals, which subsequently could be used to generate logit-log plots. However, it was observed that typical sigmoidal curves were not obtained, when peak areas were plotted against the applied amount on a logarithmic scale (log amount). Therefore, peak heights were examined in the present study, which revealed proper dose-response curves when plotted against the log amount. The presence of sigmoidal dose-response curves from HPTLC-pYES made it possible to transform the signals into logits and, therefore, to create logit-log plots with linear correlations. The logit-log plots for the estrogen active compounds (EAC) 17β-estradiol (E2) and 17α-ethinylestradiol (EE2) provided a working range up to 500pg/zone. Applying logit-log plots, mean recovery rates for E2 and EE2 from spiked water samples (2-20ng/L) were determined to 90% and 108%, respectively, with ≤24% RSD. Moreover, the linear graphs allowed an easy determination of the half maximal effect dose (ED50) of EAC, since the intersection of the graph with the abscissa represents the ED50. Additionally, with the knowledge of the ED50 values, the estrogenic potential of EAC in terms of estradiol equivalent factors (EEF) could be determined, resulting in 0.64 for EE2. Copyright © 2017 Elsevier B.V. All rights reserved.

  2. A Longitudinal Study of Reading Comprehension Achievement from Grades 3 to 10: Investigating Models of Stability, Cumulative Growth, and Compensation

    Science.gov (United States)

    Kwiatkowska-White, Bozena; Kirby, John R.; Lee, Elizabeth A.

    2016-01-01

    This longitudinal study of 78 Canadian English-speaking students examined the applicability of the stability, cumulative, and compensatory models in reading comprehension development. Archival government-mandated assessments of reading comprehension at Grades 3, 6, and 10, and the Canadian Test of Basic Skills measure of reading comprehension…

  3. When Two Isn't Better than One: Predictors of Early Sexual Activity in Adolescence Using a Cumulative Risk Model

    Science.gov (United States)

    Price, Myeshia N.; Hyde, Janet Shibley

    2009-01-01

    This study explored factors that may be associated with early initiation of sexual activity among adolescents. Using the cumulative risk model, we hypothesized that as exposure to risk factors increases, so does the likelihood of early sexual debut. A sample of 273 (53% girls, 90% European American) adolescents was followed longitudinally from age…

  4. A cumulative risk factor model for early identification of academic difficulties in premature and low birth weight infants

    NARCIS (Netherlands)

    Roberts, G.; Bellinger, D.; McCormick, Marie C.

    2007-01-01

    Objectives: Premature and low birth weight children have a high prevalence of academic difficulties. This study examines a model comprised of cumulative risk factors that allows early identification of these difficulties. Methods: This is a secondary analysis of data from a large cohort of premature

  5. Testing of a cumulative and aggregate exposure model using biomonitoring studies and dietary records for Italian vineyard spray operators.

    NARCIS (Netherlands)

    Kennedy, M.C.; Glass, C.R.; Fustinoni, S.; Moretto, A.; Mandic-Rajcevic, S.; Riso, P.; Turrini, A.; Voet, van der H.; Hetmanski, M.T.; Fussel, R.J.; Klaveren, van J.D.

    2015-01-01

    The need for improved tools to estimate the cumulative and aggregate exposure to compounds such as plant protection products (PPPs) is recognised in the EU Regulation 1107/2009. A new model has been developed to estimate the exposure within a population to single compounds or compounds within a Cumu

  6. A Longitudinal Study of Reading Comprehension Achievement from Grades 3 to 10: Investigating Models of Stability, Cumulative Growth, and Compensation

    Science.gov (United States)

    Kwiatkowska-White, Bozena; Kirby, John R.; Lee, Elizabeth A.

    2016-01-01

    This longitudinal study of 78 Canadian English-speaking students examined the applicability of the stability, cumulative, and compensatory models in reading comprehension development. Archival government-mandated assessments of reading comprehension at Grades 3, 6, and 10, and the Canadian Test of Basic Skills measure of reading comprehension…

  7. Linking turbine collision risks with population models to assess cumulative impacts of multiple wind farms on threatened birds

    Energy Technology Data Exchange (ETDEWEB)

    Smales, Ian; Muir, Stuart; Meredith, Charles; Baird, Robert

    2011-07-01

    Full text: Assessment of the effects on birds of wind turbine collisions has generally been focussed on the number of individuals that might be killed at a particular facility. However, this measure, of itself, may have little relevance to evaluating the potential or real effects on conservation status of threatened species. Determination of the overall effect any such mortality may have on the functioning of these populations will provide a better basis for decisions that have a strong foundation in ecology. For species with sufficient demographic information, we have developed and applied an approach combining collision risk modelling for all wind farms within the range of a threatened species with population modelling. This permits population-level evaluation of potential cumulative impacts of multiple wind farms. In Australia, regulatory authorities are increasingly interested in the cumulative risk to threatened species that may be posed by multiple wind energy facilities within a species. range. The approach outlined here has been applied in the pre-construction approval stage using collision risk modelling, and can be applied to operational facilities using data on actual mortalities. Cumulative modelling of risk posed by multiple wind farms requires different approaches for sedentary and migratory species. For sedentary species the cumulative effect will be the sum of the impact experienced by those parts of the population whose range intersects with wind farms. Cumulative impact is derived for migratory species by assessing the probability of birds surviving encounters with one wind farm after another on the migratory route and is thus the product of their survivorship rates for the relevant wind farms. The collision risk modelling used will be outlined along with the method in which it is integrated with a population model. Case studies for a crane (Brolga Grus rubicundus) and a parrot (orange- bellied parrot Neophema chrysogaster) species will be

  8. Evaluation of Inference Adequacy in Cumulative Logistic Regression Models: An Empirical Validation of ISWRidge Relationships

    Institute of Scientific and Technical Information of China (English)

    Cheng-Wu CHEN; Hsien-Chueh Peter YANG; Chen-Yuan CHEN; Alex Kung-Hsiung CHANG; Tsung-Hao CHEN

    2008-01-01

    Internal solitary wave propagation over a submarine ridge results in energy dissipation, in which the hydrodynamic interaction between a wave and ridge affects marine environment. This study analyzes the effects of ridge height and potential energy during wave-ridge interaction with a binary and cumulative logistic regression model. In testing the Global Null Hypothesis, all values are p<0.001, with three statistical methods, such as Likelihood Ratio, Score, and Wald. While comparing with two kinds of models, tests values obtained by cumulative logistic regression models are better than those by binary logistic regression models. Although this study employed cumulative logistic regression model, three probability functions 1, 2 and 3, are utilized for investigating the weighted influence of factors on wave reflection. Deviance and Pearson tests are applied to check the goodness-of-fit of the proposed model. The analytical results demonstrated that both ridge height (X1) and potential energy (X2) significantly impact (p<0.0001) the amplitude-based reflected rate; the P-values for the deviance and Pearson are all >0.05 (0.2839, 0.3438, respectively). That is, the goodness-of-fit between ridge height (X1) and potential energy (X2) can further predict parameters under the scenario of the best parsimonious model.Investigation of 6 predictive powers (R2, Max-rescaled R2, Somers'D, Gamma, Tau-a, and c, respectively) indicate that these predictive estimates of the proposed model have better predictive ability than ridge height alone, and are very similar to the interaction of ridge height and potential energy. It can be concluded that the goodness-of-fit and prediction ability of the cumulative logistic regression model are better than that of the binary logistic regression model.

  9. Valoração de contingente pelas modelagens logit e análise multivariada: um estudo de caso da disposição a aceitar compensação dos cafeicultores vinculados ao PRO-CAFÉ de Viçosa - MG Contingent valuation with modeling logit and multivariate analyses: a case study of the willingness of coffee planters linked to the PRO-COFFEE of Viçosa - MG to accept compensation

    Directory of Open Access Journals (Sweden)

    Pedro Silveira Máximo

    2009-12-01

    Full Text Available O objetivo deste estudo foi, justamente, identificar, entre os métodos LOGIT e a análise multivariada, qual a mais eficaz para estimar a Disposição a Aceitar Compensação (DAC dos cafeicultores quando o viés da utilidade marginal é passível de ocorrência. Para tal, foi elaborado um formulário com 33 perguntas envolvendo informações sobre características socioeconômicas dos cafeicultores, o uso da metodologia de valoração de contingente (MVC e do veículo de pagamento dos "Jogos de Lances", que revelou a Disposição a Aceitar uma Compensação (DAC na troca de um hectare de café por um hectare de mata. Como esperado, por causa do viés da utilidade marginal o método LOGIT foi incapaz de produzir resultados consistentes. Já a estimação da DAC pela análise multivariada mostrou que, caso o governo estivesse disposto a aumentar a provisão de mata em 70 ha, ele deveria despender 254.200 reais por ano, tratando apenas dos cafeicultores vinculados ao programa do PRO-CAFÉ.The object of this study was to identify which method, either LOGIT or multivariate analyses, was the most efficient to estimate the coffee planters' Willingness to Accept a Compensation, when there was a possibility of occurrence of marginal utility. For such, a questionnaire was formulated, with 33 questions involving information on coffee planters' socio - economic characteristics, the use of the methodology of contingent valuation (MCV, and the payment of the "offer game" that reveled the willingness to accept a compensation (WAC, by exchanging a hectare of coffee by a hectare of forest. As expected, because of the marginal utility's bias, the LOGIT method was unable to produce consistent results. However, when the WAC was estimated by multivariate analyses, the results showed that if the government is willing to increase the provision of forest to 70 hectares, it should pay out 254,200 reais (around 116,000 dollars, dealing only with the coffee planters

  10. Making the case for cumulative impacts assessment : modelling the potential impacts of climate change, harvesting, oil and gas, and fire

    Energy Technology Data Exchange (ETDEWEB)

    Yamasaki, S.H.; Duchesneau, R.; Doyon, F. [Inst. quebecois d' Amenagement de la Foret feuillue, Ripon, PQ (Canada); Russell, J.S. [Millar Western Forest Products Ltd., Whitecourt, AB (Canada); Gooding, T. [Forestry Corp., Edmonton, AB (Canada)

    2008-05-15

    Oil and gas activities and wildfires are altering the composition, age-class structure, and spatial configuration of Alberta's forests. Climate change may also be modifying forest dynamics which will lead to important changes in the future. This paper presented a landscape model designed to simulate the long-term cumulative effects of forestry, oil and gas activities, climate change, wildlife, and demographic change for the Whitecourt forest management area. Various landscape scenarios were presented for the forest, and key indicators for biodiversity and forest productivity were evaluated. Multiple disturbance agents were simulated in order to detect potential interactions among disturbance agents. Results of the study showed that climate and demographic changes will intensify the impacts of fires on timber supplies. It was concluded that cumulative impacts assessments and spatial and temporal stochastic modelling should be included in forest management practices. 34 refs., 2 tabs., 22 figs.

  11. Who Is Overeducated and Why? Probit and Dynamic Mixed Multinomial Logit Analyses of Vertical Mismatch in East and West Germany

    Science.gov (United States)

    Boll, Christina; Leppin, Julian Sebastian; Schömann, Klaus

    2016-01-01

    Overeducation potentially signals a productivity loss. With Socio-Economic Panel data from 1984 to 2011 we identify drivers of educational mismatch for East and West medium and highly educated Germans. Addressing measurement error, state dependence and unobserved heterogeneity, we run dynamic mixed multinomial logit models for three different…

  12. Empirical Study of Risk Assessment of Personal Loan Bussiness Bassed on Logit Model in China’s Commercal Banks%基于Logit模型的商业银行个人贷款业务风险成因实证研究

    Institute of Scientific and Technical Information of China (English)

    张婧

    2014-01-01

    运用logit模型对我国商业银行个人贷款业务风险成因进行了实证研究。结果表明,受教育程度与经济状况对个人贷款违约率有显著影响,商业银行在发放个人贷款业务前除了考察年龄、婚姻状况等因素外,应重点考察这两个因素。%This paper uses the logit model to empirically study on risk factors of personal loan business of commercial banks in China, found that the level of education and economy rate has a significant impact on the personal loan default, commercial banks in the issuance of the personal loan business before except factors age, marital status, should focus on these two factors.

  13. Instrumental variables estimation of exposure effects on a time-to-event response using structural cumulative survival models

    DEFF Research Database (Denmark)

    Martinussen, T.; Vansteelandt, S.; Tchetgen, E. J. Tchetgen;

    2016-01-01

    of complications due to censoring and survivorship bias. In this paper, we make a novel proposal under a class of structural cumulative survival models which parameterize time-varying effects of a point exposure directly on the scale of the survival function; these models are essentially equivalent with a semi......-parametric variant of the instrumental variables additive hazards model. We propose a class of recursive instrumental variable estimators for these exposure effects, and derive their large sample properties along with inferential tools. We examine the performance of the proposed method in simulation studies...

  14. Cumulative dietary exposure to a selected group of pesticides of the triazole group in different European countries according to the EFSA guidance on probabilistic modelling

    DEFF Research Database (Denmark)

    Boon, Polly E.; van Donkersgoed, Gerda; Christodoulou, Despo

    2015-01-01

    The practicality was examined of performing a cumulative dietary exposure assessment according to the requirements of the EFSA guidance on probabilistic modelling. For this the acute and chronic cumulative exposure to triazole pesticides was estimated using national food consumption and monitorin...

  15. Un procedimiento para selección de los modelos Logit Mixtos

    OpenAIRE

    Ruíz Gallegos, José de Jesús

    2004-01-01

    En el presente trabajo se hace una revisión de dos modelos que han tenido una fuerte aplicabilidad en los problemas de elecciones discretas: El modelo Logit y el modelo Logit Mixto. Además, se propone el uso del estadístico de Cox para seleccionar modelos, en el modelo Logit Mixto.

  16. Un procedimiento para selección de los modelos Logit Mixtos

    OpenAIRE

    Ruíz Gallegos, José de Jesús

    2004-01-01

    En el presente trabajo se hace una revisión de dos modelos que han tenido una fuerte aplicabilidad en los problemas de elecciones discretas: El modelo Logit y el modelo Logit Mixto. Además, se propone el uso del estadístico de Cox para seleccionar modelos, en el modelo Logit Mixto.

  17. Testing a cumulative and aggregate exposure model using biomonitoring studies and dietary records for Italian vineyard spray operators.

    Science.gov (United States)

    Kennedy, Marc C; Glass, C Richard; Fustinoni, Silvia; Moretto, Angelo; Mandic-Rajcevic, Stefan; Riso, Patrizia; Turrini, Aida; van der Voet, Hilko; Hetmanski, Michel T; Fussell, Richard J; van Klaveren, Jacob D

    2015-05-01

    The need for improved tools to estimate the cumulative and aggregate exposure to compounds such as plant protection products (PPPs) is recognised in the EU Regulation 1107/2009. A new model has been developed to estimate the exposure within a population to single compounds or compounds within a Cumulative Action Group, considering dietary and non-dietary sources and multiple exposure routes. To test the model a field study was carried out in Italy with operators applying tebuconazole fungicides, with measurements of dermal exposure collected. Whole urine samples were collected and analysed to provide values for the absorbed dose of tebuconazole, with duplicate diet samples collected and analysed as a measure of dietary exposures. The model provided predicted values of exposure for combined dietary and non-dietary routes of exposures which were compared to the measured absorbed dose values based on urinary analysis. The model outputs provided mean daily exposure values of 1.77 (± 1.96) µg a.s./kg BW which are comparable to measured mean values from the biomonitoring field study of 1.73 (± 1.31) µg a.s./kg BW. To supplement the limited measurement data available, comparisons against other models were also made and found to be comparable.

  18. The hairless guinea-pig as a model for treatment of cumulative irritation in humans

    DEFF Research Database (Denmark)

    Andersen, F; Hedegaard, K; Petersen, Thomas Kongsted

    2006-01-01

    BACKGROUND: The effect of six skin-care formulations (SCFs) on experimentally induced cumulative irritation was studied in hairless guinea-pigs (HLGPs) and in human volunteers (HVs). The formulations were a basic cream, a carbomer cream and four modifications of the carbomer cream, containing...... either 10% isopropyl palmitate (IPP cream), 10% glycerol (glycerol cream), 19.5% canola oil (canola oil cream) or 0.5% (-)-alpha-bisabolol (bisabolol cream). METHODS: In HLGP, irritant dermatitis was induced with 30 min daily exposure for 4 days to 0.5% sodium lauryl sulfate aq. (SLS). In HVs, irritant...... measured at baseline (day 0) in the middle and at the end of treatment. Treatments were applied twice daily. The basic cream and the IPP cream were excluded from testing in HLGP because they were known from previous studies to be irritant in HLGP, while all formulations were known to be equally and well...

  19. Measurement error correction for the cumulative average model in the survival analysis of nutritional data: application to Nurses' Health Study.

    Science.gov (United States)

    Qiu, Weiliang; Rosner, Bernard

    2010-01-01

    The use of the cumulative average model to investigate the association between disease incidence and repeated measurements of exposures in medical follow-up studies can be dated back to the 1960s (Kahn and Dawber, J Chron Dis 19:611-620, 1966). This model takes advantage of all prior data and thus should provide a statistically more powerful test of disease-exposure associations. Measurement error in covariates is common for medical follow-up studies. Many methods have been proposed to correct for measurement error. To the best of our knowledge, no methods have been proposed yet to correct for measurement error in the cumulative average model. In this article, we propose a regression calibration approach to correct relative risk estimates for measurement error. The approach is illustrated with data from the Nurses' Health Study relating incident breast cancer between 1980 and 2002 to time-dependent measures of calorie-adjusted saturated fat intake, controlling for total caloric intake, alcohol intake, and baseline age.

  20. An Integrated Modeling Framework Forecasting Ecosystem Exposure-- A Systems Approach to the Cumulative Impacts of Multiple Stressors

    Science.gov (United States)

    Johnston, J. M.

    2013-12-01

    Freshwater habitats provide fishable, swimmable and drinkable resources and are a nexus of geophysical and biological processes. These processes in turn influence the persistence and sustainability of populations, communities and ecosystems. Climate change and landuse change encompass numerous stressors of potential exposure, including the introduction of toxic contaminants, invasive species, and disease in addition to physical drivers such as temperature and hydrologic regime. A systems approach that includes the scientific and technologic basis of assessing the health of ecosystems is needed to effectively protect human health and the environment. The Integrated Environmental Modeling Framework 'iemWatersheds' has been developed as a consistent and coherent means of forecasting the cumulative impact of co-occurring stressors. The Framework consists of three facilitating technologies: Data for Environmental Modeling (D4EM) that automates the collection and standardization of input data; the Framework for Risk Assessment of Multimedia Environmental Systems (FRAMES) that manages the flow of information between linked models; and the Supercomputer for Model Uncertainty and Sensitivity Evaluation (SuperMUSE) that provides post-processing and analysis of model outputs, including uncertainty and sensitivity analysis. Five models are linked within the Framework to provide multimedia simulation capabilities for hydrology and water quality processes: the Soil Water Assessment Tool (SWAT) predicts surface water and sediment runoff and associated contaminants; the Watershed Mercury Model (WMM) predicts mercury runoff and loading to streams; the Water quality Analysis and Simulation Program (WASP) predicts water quality within the stream channel; the Habitat Suitability Index (HSI) model scores physicochemical habitat quality for individual fish species; and the Bioaccumulation and Aquatic System Simulator (BASS) predicts fish growth, population dynamics and bioaccumulation

  1. A geographic model to assess and limit cumulative ecological degradation from Marcellus Shale exploitation in New York, USA

    Science.gov (United States)

    Davis, John B.; Robinson, George R.

    2012-01-01

    When natural resources are exploited, environmental costs and economic benefits are often asymmetric. An example is apparent in the environmental impacts from fossil fuel extraction by hydraulic fracturing. So far, most scrutiny has been focused on water quality in affected aquifers, with less attention paid to broader ecological impacts beyond individual drilling operations. Marcellus Shale methane exploitation in New York State, USA, has been delayed because of a regulatory moratorium, pending evaluation that has been directed primarily at localized impacts. We developed a GIS-based model, built on a hexagonal grid underlay nested within the U.S. Environmental Protection Agency’s EMAP system, to examine potential cumulative ecological impacts. In a two-step process, we characterized > 19,000 hexagons, each sized to approximate the footprint of one drilling site (2.57 km²), using ecological attributes; we then developed a method for apportioning resource access that includes assessments of cumulative ecological costs. Over one-quarter of the hexagons were excluded as off-limits on the basis of six criteria: slope suitability, regulated wetland cover, protected-land cover, length of high-quality streams, mapped road density, and open water cover. Three additional criteria were applied to assess the estimated conservation vulnerability of the remaining sites: density of grassland birds (North American Breeding Bird Survey), percent core forest (Coastal Change Analysis Program), and total density of all state-mapped streams; these were determined and used in combination to rank the 14,000 potentially accessible sites. In a second step, an iterative process was used to distribute potential site access among all towns (sub-county governments) within the Marcellus Shale Formation. At each iteration, one site was selected per town, either randomly or in rank order of increasing vulnerability. Results were computed as percent cumulative impact versus the number of

  2. A Geographic Model to Assess and Limit Cumulative Ecological Degradation from Marcellus Shale Exploitation in New York, USA

    Directory of Open Access Journals (Sweden)

    George R. Robinson

    2012-06-01

    Full Text Available When natural resources are exploited, environmental costs and economic benefits are often asymmetric. An example is apparent in the environmental impacts from fossil fuel extraction by hydraulic fracturing. So far, most scrutiny has been focused on water quality in affected aquifers, with less attention paid to broader ecological impacts beyond individual drilling operations. Marcellus Shale methane exploitation in New York State, USA, has been delayed because of a regulatory moratorium, pending evaluation that has been directed primarily at localized impacts. We developed a GIS-based model, built on a hexagonal grid underlay nested within the U.S. Environmental Protection Agency’s EMAP system, to examine potential cumulative ecological impacts. In a two-step process, we characterized > 19,000 hexagons, each sized to approximate the footprint of one drilling site (2.57 km², using ecological attributes; we then developed a method for apportioning resource access that includes assessments of cumulative ecological costs. Over one-quarter of the hexagons were excluded as off-limits on the basis of six criteria: slope suitability, regulated wetland cover, protected-land cover, length of high-quality streams, mapped road density, and open water cover. Three additional criteria were applied to assess the estimated conservation vulnerability of the remaining sites: density of grassland birds (North American Breeding Bird Survey, percent core forest (Coastal Change Analysis Program, and total density of all state-mapped streams; these were determined and used in combination to rank the 14,000 potentially accessible sites. In a second step, an iterative process was used to distribute potential site access among all towns (sub-county governments within the Marcellus Shale Formation. At each iteration, one site was selected per town, either randomly or in rank order of increasing vulnerability. Results were computed as percent cumulative impact versus

  3. Regression Modeling of Competing Risks Data Based on Pseudovalues of the Cumulative Incidence Function

    DEFF Research Database (Denmark)

    Klein, John P.; Andersen, Per Kragh

    2005-01-01

    Bone marrow transplantation; Generalized estimating equations; Jackknife statistics; Regression models......Bone marrow transplantation; Generalized estimating equations; Jackknife statistics; Regression models...

  4. Research on Industry Factors of the Distinguish Effect of Comprehensive Risk-warning Model---A Case Study of Logit Model Based on Principal Component Analysis%行业因素对综合预警模型的判别效果的影响研究--以基于主成分分析的Logit模型为例

    Institute of Scientific and Technical Information of China (English)

    朱卫东; 李玲玲; 刘珍珍

    2015-01-01

    Taking indebted ST listed companies and twice as many the non -ST of Shanghai and Shenzhen A -share from 2010 to 2012 as sample , the paper divides the sample into different kinds according to industry characteristics . Then we select 30 financial indica-tors that can reflect the business profitability , profitability of shareholders , cash flow capacity , operational capacity , development capacity and debt solvency . Finally , a Logit model based on principal component analysis method is proposed to analyze the predictive performance of the model for default probabilities and distinguish accuracy in different industries . The results show that there were significant differences and common features in default probabilities and distinguish accuracy of different industries .%以2010~2012年期间我国沪深A股因财务困境陷入ST的公司和按照1∶2比例配比的正常公司作为研究对象,并根据行业特点对样本进行划分。同时,选取能够反映企业盈利能力、股东获利能力、现金流量能力、营运能力、发展能力、偿债能力的30个财务指标,在主成分分析的基础上构建各年度的Logit模型,对各行业的违约概率和判别准确度分别进行分析。结果表明,不同行业的违约概率和判别准确度均存在显著差异且存在共性特征。

  5. Assessing cumulative impacts of forest development on the distribution of furbearers using expert-based habitat modeling.

    Science.gov (United States)

    Bridger, M C; Johnson, C J; Gillingham, M P

    2016-03-01

    Cumulative impacts of anthropogenic landscape change must be considered when managing and conserving wildlife habitat. Across the central-interior of British Columbia, Canada, industrial activities are altering the habitat of furbearer species. This region has witnessed unprecedented levels of anthropogenic landscape change following rapid development in a number of resource sectors, particularly forestry. Our objective was to create expert-based habitat models for three furbearer species: fisher (Pekania pennanti), Canada lynx (Lynx canadensis), and American marten (Martes americana) and quantify habitat change for those species. We recruited 10 biologist and 10 trapper experts and then used the analytical hierarchy process to elicit expert knowledge of habitat variables important to each species. We applied the models to reference landscapes (i.e., registered traplines) in two distinct study areas and then quantified the change in habitat availability from 1990 to 2013. There was strong agreement between expert groups in the choice of habitat variables and associated scores. Where anthropogenic impacts had increased considerably over the study period, the habitat models showed substantial declines in habitat availability for each focal species (78% decline in optimal fisher habitat, 83% decline in optimal lynx habitat, and 79% decline in optimal marten habitat). For those traplines with relatively little forest harvesting, the habitat models showed no substantial change in the availability of habitat over time. The results suggest that habitat for these three furbearer species declined significantly as a result of the cumulative impacts of forest harvesting. Results of this study illustrate the utility of expert knowledge for understanding large-scale patterns of habitat change over long time periods.

  6. Predicting Cumulative Incidence Probability by Direct Binomial Regression

    DEFF Research Database (Denmark)

    Scheike, Thomas H.; Zhang, Mei-Jie

    Binomial modelling; cumulative incidence probability; cause-specific hazards; subdistribution hazard......Binomial modelling; cumulative incidence probability; cause-specific hazards; subdistribution hazard...

  7. A new Cumulative Damage Model for Fatigue Life Prediction under Shot Peening Treatment

    Directory of Open Access Journals (Sweden)

    Abdul-Jabar H. Ali

    2015-07-01

    Full Text Available In this paper, fatigue damage accumulation were studied using many methods i.e.Corton-Dalon (CD,Corton-Dalon-Marsh(CDM, new non-linear model and experimental method. The prediction of fatigue lifetimes based on the two classical methods, Corton-Dalon (CDandCorton-Dalon-Marsh (CDM, are uneconomic and non-conservative respectively. However satisfactory predictions were obtained by applying the proposed non-linear model (present model for medium carbon steel compared with experimental work. Many shortcomings of the two classical methods are related to their inability to take into account the surface treatment effect as shot peening. It is clear that the new model shows that a much better and conservative prediction of fatigue life in comparison with CD and CDM methods. The prediction of the present model gave slightly below the experimental data while the CDM gave overestimate prediction and CD showed strongly underestimates the life of specimens.

  8. EPA's SHEDS-multimedia model: children's cumulative pyrethroid exposure estimates and evaluation against NHANES biomarker data

    Science.gov (United States)

    The U.S. EPA's SHEDS-Multimedia model was applied to enhance the understanding of children's exposures and doses to multiple pyrethroid pesticides, including major contributing chemicals and pathways. This paper presents combined dietary and residential exposure estimates and cum...

  9. Modeling larval malaria vector habitat locations using landscape features and cumulative precipitation measures

    NARCIS (Netherlands)

    Mc Cann, R.S.; Messina, J.P.; MacFarlane, D.W.; Bayoh, M.N.; Vulule, J.M.; Gimnig, J.E.; Walker, E.D.

    2014-01-01

    BACKGROUND: Predictive models of malaria vector larval habitat locations may provide a basis for understanding the spatial determinants of malaria transmission. METHODS: We used four landscape variables (topographic wetness index [TWI], soil type, land use-land cover, and distance to stream) and acc

  10. Using Marginal Structural Modeling to Estimate the Cumulative Impact of an Unconditional Tax Credit on Self-Rated Health.

    Science.gov (United States)

    Pega, Frank; Blakely, Tony; Glymour, M Maria; Carter, Kristie N; Kawachi, Ichiro

    2016-02-15

    In previous studies, researchers estimated short-term relationships between financial credits and health outcomes using conventional regression analyses, but they did not account for time-varying confounders affected by prior treatment (CAPTs) or the credits' cumulative impacts over time. In this study, we examined the association between total number of years of receiving New Zealand's Family Tax Credit (FTC) and self-rated health (SRH) in 6,900 working-age parents using 7 waves of New Zealand longitudinal data (2002-2009). We conducted conventional linear regression analyses, both unadjusted and adjusted for time-invariant and time-varying confounders measured at baseline, and fitted marginal structural models (MSMs) that more fully adjusted for confounders, including CAPTs. Of all participants, 5.1%-6.8% received the FTC for 1-3 years and 1.8%-3.6% for 4-7 years. In unadjusted and adjusted conventional regression analyses, each additional year of receiving the FTC was associated with 0.033 (95% confidence interval (CI): -0.047, -0.019) and 0.026 (95% CI: -0.041, -0.010) units worse SRH (on a 5-unit scale). In the MSMs, the average causal treatment effect also reflected a small decrease in SRH (unstabilized weights: β = -0.039 unit, 95% CI: -0.058, -0.020; stabilized weights: β = -0.031 unit, 95% CI: -0.050, -0.007). Cumulatively receiving the FTC marginally reduced SRH. Conventional regression analyses and MSMs produced similar estimates, suggesting little bias from CAPTs.

  11. Bivariate cumulative probit model for the comparison of neuronal encoding hypotheses.

    Science.gov (United States)

    Hillmann, Julia; Kneib, Thomas; Koepcke, Lena; Juárez Paz, León M; Kretzberg, Jutta

    2014-01-01

    Understanding the way stimulus properties are encoded in the nerve cell responses of sensory organs is one of the fundamental scientific questions in neurosciences. Different neuronal coding hypotheses can be compared by use of an inverse procedure called stimulus reconstruction. Here, based on different attributes of experimentally recorded neuronal responses, the values of certain stimulus properties are estimated by statistical classification methods. Comparison of stimulus reconstruction results then allows to draw conclusions about relative importance of covariate features. Since many stimulus properties have a natural order and can therefore be considered as ordinal, we introduce a bivariate ordinal probit model to obtain classifications for the combination of light intensity and velocity of a visual dot pattern based on different covariates extracted from recorded spike trains. For parameter estimation, we develop a Bayesian Gibbs sampler and incorporate penalized splines to model nonlinear effects. We compare the classification performance of different individual cell covariates and simple features of groups of neurons and find that the combination of at least two covariates increases the classification performance significantly. Furthermore, we obtain a non-linear effect for the first spike latency. The model is compared to a naïve Bayesian stimulus estimation method where it yields comparable misclassification rates for the given dataset. Hence, the bivariate ordinal probit model is shown to be a helpful tool for stimulus reconstruction particularly thanks to its flexibility with respect to the number of covariates as well as their scale and effect type. © 2013 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  12. Development of a "Hydrologic Equivalent Wetland" Concept for Modeling Cumulative Effects of Wetlands on Watershed Hydrology

    Science.gov (United States)

    Wang, X.; Liu, T.; Li, R.; Yang, X.; Duan, L.; Luo, Y.

    2012-12-01

    Wetlands are one of the most important watershed microtopographic features that affect, in combination rather than individually, hydrologic processes (e.g., routing) and the fate and transport of constituents (e.g., sediment and nutrients). Efforts to conserve existing wetlands and/or to restore lost wetlands require that watershed-level effects of wetlands on water quantity and water quality be quantified. Because monitoring approaches are usually cost or logistics prohibitive at watershed scale, distributed watershed models, such as the Soil and Water Assessment Tool (SWAT), can be a best resort if wetlands can be appropriately represented in the models. However, the exact method that should be used to incorporate wetlands into hydrologic models is the subject of much disagreement in the literature. In addition, there is a serious lack of information about how to model wetland conservation-restoration effects using such kind of integrated modeling approach. The objectives of this study were to: 1) develop a "hydrologic equivalent wetland" (HEW) concept; and 2) demonstrate how to use the HEW concept in SWAT to assess effects of wetland restoration within the Broughton's Creek watershed located in southwestern Manitoba of Canada, and of wetland conservation within the upper portion of the Otter Tail River watershed located in northwestern Minnesota of the United States. The HEWs were defined in terms of six calibrated parameters: the fraction of the subbasin area that drains into wetlands (WET_FR), the volume of water stored in the wetlands when filled to their normal water level (WET_NVOL), the volume of water stored in the wetlands when filled to their maximum water level (WET_MXVOL), the longest tributary channel length in the subbasin (CH_L1), Manning's n value for the tributary channels (CH_N1), and Manning's n value for the main channel (CH_N2). The results indicated that the HEW concept allows the nonlinear functional relations between watershed processes

  13. Effects of volume corrections and resonance decays on cumulants of net-charge distributions in a Monte Carlo hadron resonance gas model

    Science.gov (United States)

    Xu, Hao-jie

    2017-02-01

    The effects of volume corrections and resonance decays (the resulting correlations between positive charges and negative charges) on cumulants of net-proton distributions and net-charge distributions are investigated by using a Monte Carlo hadron resonance gas (MCHRG) model. The required volume distributions are generated by a Monte Carlo Glauber (MC-Glb) model. Except the variances of net-charge distributions, the MCHRG model with more realistic simulations of volume corrections, resonance decays and acceptance cuts can reasonably explain the data of cumulants of net-proton distributions and net-charge distributions reported by the STAR collaboration. The MCHRG calculations indicate that both the volume corrections and resonance decays make the cumulant products of net-charge distributions deviate from the Skellam expectations: the deviations of Sσ and κσ2 are dominated by the former effect while the deviations of ω are dominated by the latter one.

  14. Managing the Cumulative Impacts of Land Uses in the Western Canadian Sedimentary Basin: A Modeling Approach

    Directory of Open Access Journals (Sweden)

    Richard, R. Schneider

    2003-07-01

    Full Text Available This case study from northeastern Alberta, Canada, demonstrates a fundamentally different approach to forest management in which stakeholders balance conservation and economic objectives by weighing current management options from the point of view of their long-term effects on the forest. ALCES®, a landscape-scale simulation model, is used to quantify the effects of the current regulatory framework and typical industrial practices on a suite of ecological and economic indicators over the next 100 yr. These simulations suggest that, if current practices continue, the combined activities of the energy and forestry industries in our 59,000 km2 study area will cause the density of edge of human origin to increase from 1.8 km/km 2 to a maximum of 8.0 km/km2. We also predict that older age classes of merchantable forest stands will be largely eliminated from the landscape, habitat availability for woodland caribou will decline from 43 to 6%, and there will be a progressive shortfall in the supply of softwood timber beginning in approximately 60 yr. Additional simulations involving a suite of "best practices" demonstrate that substantial improvements in ecological outcome measures could be achieved through alternative management scenarios while still maintaining a sustainable flow of economic benefits. We discuss the merits of our proposed approach to land use planning and apply it to the Western Canadian Sedimentary Basin.

  15. Cumulative Intracranial Tumor Volume (CITV) Enhances the Prognostic Value of the Lung-Specific Graded Prognostic Assessment (GPA) Model.

    Science.gov (United States)

    Marcus, Logan P; Marshall, Deborah; Hirshman, Brian R; McCutcheon, Brandon A; Gonda, David D; Koiso, Takao; Hattangadi-Gluth, Jona A; Carter, Bob S; Yamamoto, Masaaki; Chen, Clark C

    2016-08-01

    Management of patients afflicted with brain metastasis requires tailoring of therapeutic strategies based on survival expectations. Therefore, the development of prognostic indices is of critical importance in this patient population. To determine whether the cumulative intracranial tumor volume (CITV) of brain metastasis augments the prognostic value of the lung-specific Graded Prognostic Assessment (GPA) index. Patient data were derived from 365 lung cancer patients with brain metastasis who were consecutively treated with stereotactic radiosurgery at the University of California, San Diego/San Diego Gamma Knife Center. CITV was analyzed to determine the volume cutoff that maximized sensitivity and specificity for 1-year survival. Multivariate Cox proportional hazard modeling was performed, and overall survival was estimated by the Kaplan-Meier method risk stratifying with or without this optimal CITV. The prognostic value of these models (lung-specific GPA ± CITV) was quantitatively compared with the use of net reclassification improvement (>0) and integrated discrimination improvement. For the University of California, San Diego/San Diego Gamma Knife Center cohort, the CITV cutoff that had the greatest survival discrimination at 1 year was 4 cm. The addition of CITV to the lung-specific GPA indexes significantly improved the prognostic value of lung-specific GPA, with net reclassification improvement >0 of 0.430 (95% confidence interval, 0.228-0.629) and integrated discrimination improvement of 0.029 (95% confidence interval, 0.004-0.073). These findings were validated in an independent cohort of 1638 lung cancer patients with brain metastasis who were treated with stereotactic radiosurgery at the Katsuta Hospital Mito Gamma House in Japan. In independent cohorts, the addition of CITV to the lung-specific GPA index significantly improved the prognostic value of this index. AUC, area under the receiver-operating characteristic curveBM, brain metastasis

  16. DOSE-RESPONSE MODELING FOR THE ASSESSMENT OF CUMULATIVE RISK DUE TO EXPOSURE TO N-METHYL CARBAMATE PESTICIDES

    Science.gov (United States)

    The US EPAs N-Methyl Carbamate Cumulative Risk Assessment (NMCRA) assesses the effect on acetylcholine esterase (AChE) activity of exposure to 10 N-methyl carbamate (NMC) pesticides through dietary, drinking water, and residential exposures.

  17. The Soft Cumulative Constraint

    CERN Document Server

    Petit, Thierry

    2009-01-01

    This research report presents an extension of Cumulative of Choco constraint solver, which is useful to encode over-constrained cumulative problems. This new global constraint uses sweep and task interval violation-based algorithms.

  18. 基于Logit模型的产品组合策略研究--以“三国杀”道具选择为例%Based on the Logit model product portfolio strategy research-- "three kingdoms" props choice, for example

    Institute of Scientific and Technical Information of China (English)

    魏宇鹏

    2015-01-01

    随着互联网经济的发展,游戏道具越来越受到企业家、政府机关、学者以及社会各界的广泛关注,然而产品组合问题也日益凸显。本文以三国杀为例,选取性别、年龄、收入、伙伴有无等个人属性参数和掌控性、快乐感、满意度等心理属性参数对四种道具的购买进行Logit模型分析得出相应结论:消费者对三国杀不同道具的掌控性、快乐感和满意度各不相同。结合实证结论针对武将、功能、装扮、皮肤分别采取收获策略、培植策略、维持策略、转换策略。%With the development of the Internet economy, game props by entrepreneurs, government agencies, academics and social widespread attention from all walks of life, the product mix problem, however, is growing. Selection based on The Three Kingdoms, for example, gender, age, income, and partners have personal property parameters and mastery, happiness, satisfaction and other psychological attribute parameter Logit model analysis was carried out on the four props purchase corresponding conclusions: consumers' mastery of The Three Kingdoms kill different props, happiness and satisfaction. Combined with empirical conclusions, function, dress up, skin respectively for military commanders to harvest strategy, cultivating strategy, maintenance strategy, the conversion strategy.

  19. Analysis of the liquidity risk in credit unions: a logit multinomial approach

    Directory of Open Access Journals (Sweden)

    Rosiane Maria Lima Gonçalves

    2008-10-01

    Full Text Available Liquidity risk in financial institutions is associated to balance between working capital and financial demands. Other factors that affect credit union liquidity are an unanticipated increase of withdrawals without an offsetting amount of new deposits, and the lack of ability in promoting the product geographical diversification. The objective of this study is to analyze Minas Gerais state credit union liquidity risk and its factor determinants. Financial ratios and the multinomial logit model are used. The cooperatives were classified in five categories of liquidity risk: very low, low, medium, high and very high. The empirical results indicate that high levels of liquidity are related to smaller values of the outsourcing capital use, immobilization of the turnover capital, and provision ratios. So, they are associated to larger values of the deposit total/credit operations, and asset growth ratios.

  20. Cumulants of Net-Proton, Net-Kaon and Net-Charge Multiplicity Distributions in Au+Au Collisions at RHIC BES Energies from UrQMD Model

    CERN Document Server

    Xu, Ji; Liu, Feng; Luo, Xiaofeng

    2016-01-01

    Fluctuations of conserved quantities are sensitive observables to probe the signature of QCD phase transition and critical point in heavy-ion collisions. With the UrQMD model, we have studied the centrality and energy dependence of various order cumulants and cumulant ratios (up to fourth order) of net-proton,net-charge and net-kaon multiplicity distributions in Au+Au collisions at $\\sqrt{s_{NN}}$= 7.7, 11.5, 19.6, 27, 39, 62.4, 200 GeV. The model results show that the production mechanism of the particles and anti-particles have significant impacts on the cumulants of net-particles multiplicity distributions and show strong energy dependence. We also made comparisons between model calculations and experimental data measured in the first phase of the beam energy scan (BES) program by the STAR experiment at RHIC. The comparisons indicate that the baryon conservation effect strongly suppress the cumulants of net-proton distributions at low energies and the non-monotonic energy dependence for the net-proton {\\KV...

  1. Three essays on resource economics. Demand systems for energy forecasting: Practical considerations for estimating a generalized logit model, To borrow or not to borrow: A variation on the MacDougal-Kemp theme, and, Valuing reduced risk for households with children or the retired

    Science.gov (United States)

    Weng, Weifeng

    This thesis presents papers on three areas of study within resource and environmental economics. "Demand Systems For Energy Forecasting" provides some practical considerations for estimating a Generalized Logit model. The main reason for using this demand system for energy and other factors is that the derived price elasticities are robust when expenditure shares are small. The primary objective of the paper is to determine the best form of the cross-price weights, and a simple inverse function of the expenditure share is selected. A second objective is to demonstrate that the estimated elasticities are sensitive to the units specified for the prices, and to show how price scales can be estimated as part of the model. "To Borrow or Not to Borrow: A Variation on the MacDougal-Kemp Theme" studies the impact of international capital movements on the conditional convergence of economies differing from each other only in initial wealth. We found that in assets, income, consumption and utility, convergence obtains, with and only with, the absence of international capital movement. When a rich country invests in a poor country, the balance of debt increases forever. Asset ownership is increased in all periods for the lender, and asset ownership of the borrower is deceased. Also, capital investment decreases the lender's utility for early periods, but increases it forever after a cross-over point. In contrast, the borrower's utility increases for early periods, but then decreases forever. "Valuing Reduced Risk for Households with Children or the Retired" presents a theoretical model of how families value risk and then exams family automobile purchases to impute the average Value of a Statistical Life (VSL) for each type of family. Data for fatal accidents are used to estimate survival rates for individuals in different types of accidents, and the probabilities of having accidents for different types of vehicle. These models are used to determine standardized risks for

  2. [Reconstruction of urban land space based on minimum cumulative resistance model: a case study of Xintang Town, Guangzhou City].

    Science.gov (United States)

    Zhong, Shi-Yu; Wu, Qing; Li, Yu; Cheng, Jin-Ping

    2012-11-01

    Based on the source-sink landscape theory and the principles of ecosystem services, the minimum cumulative resistance (MCR) model was modified, where the urban center construction land was taken as the expansion source, and the contribution rate of ecological land ecosystem services value was considered as the resistance coefficient. With the modified MCR, the urban spatial expansion process of Xintang Town, Guangzhou City was successfully simulated, and, based on the protection of ecological security pattern, the optimum path for reconstructing urban land space was put forward. The simulated urban spatial expansion short path in 1988-2008 was in accordance with the real situation. By the modified MCR, the urban space was divided into four zones of high, higher, medium, and low resistance, with the area of 80.84, 78.90, 24.26, and 61.88 km2, respectively. The expansion path of the urban space was along the route from low to medium and then to high resistance zones successively. The land suitable for eco-protection and construction had an area of 159.74 km2 and 86.14 km2, while the ecological conflict area (17.37 km2) was mainly located in higher and high resistance zones, being 10.38 and 6.99 km2, respectively. The modified MCR could not only effectively reflect the distribution area of urban land use and the conflict relationship between urban construction and ecological protection, but also reasonably judge the best developmental short path for urban spatial expansion.

  3. Using Physiologically-Based Pharmacokinetic Models to Incorporate Chemical and Non-Chemical Stressors into Cumulative Risk Assessment: A Case Study of Pesticide Exposures

    Directory of Open Access Journals (Sweden)

    Jonathan I. Levy

    2012-05-01

    Full Text Available Cumulative risk assessment has been proposed as an approach to evaluate the health risks associated with simultaneous exposure to multiple chemical and non-chemical stressors. Physiologically based pharmacokinetic/pharmacodynamic (PBPK/PD models can allow for the inclusion and evaluation of multiple stressors, including non-chemical stressors, but studies have not leveraged PBPK/PD models to jointly consider these disparate exposures in a cumulative risk context. In this study, we focused on exposures to organophosphate (OP pesticides for children in urban low-income environments, where these children would be simultaneously exposed to other pesticides (including pyrethroids and non-chemical stressors that may modify the effects of these exposures (including diet. We developed a methodological framework to evaluate chemical and non-chemical stressor impacts on OPs, utilizing an existing PBPK/PD model for chlorpyrifos. We evaluated population-specific stressors that would influence OP doses or acetylcholinesterase (AChE inhibition, the relevant PD outcome. We incorporated the impact of simultaneous exposure to pyrethroids and dietary factors on OP dose through the compartments of metabolism and PD outcome within the PBPK model, and simulated combinations of stressors across multiple exposure ranges and potential body weights. Our analyses demonstrated that both chemical and non-chemical stressors can influence the health implications of OP exposures, with up to 5-fold variability in AChE inhibition across combinations of stressor values for a given OP dose. We demonstrate an approach for modeling OP risks in the presence of other population-specific environmental stressors, providing insight about co-exposures and variability factors that most impact OP health risks and contribute to children’s cumulative health risk from pesticides. More generally, this framework can be used to inform cumulative risk assessment for any compound impacted by

  4. A Research on Influencing Factors of Collaborative Innovation of Enterprises, Universities and Research Institutes in China-An Empirical Analysis Base on Ordered Logit Model%我国产学研协同创新影响因素研究--基于Ordered Logit模型实证分析

    Institute of Scientific and Technical Information of China (English)

    何海燕; 王子文; 姜李丹; 蔡静静

    2014-01-01

    Through questionnaires and interviews of 231 main participants in collaborative innovation of enterprises,universi-ties and research institutes, and in view of the development characteristics of collaborative innovation at the present stage in China, the paper makes an empirical analysis on its influencing factors. It also estimates the impact degrees of six factors on the development of collaborative innovation of enterprises, universities and research institutes by applying Ordered Logit pre-diction model. The research shows that,supporting degree of policies and regulations,protection of intellectual property rights and transformation of scientific and technological achievements,“win-win”benefit distribution mechanism and improvement of financing channels have significant effects on main obstacles of collaborative innovation development of enterprises,universi-ties and research institutes;the impact of the enhancement of service capabilities of science and technology agency on the de-velopment demands of main innovation bodies is not remarkable.%文章通过对全国231家产学研协同创新主要参与主体的问卷调查,针对现阶段我国产学研协同创新发展特点,对其影响因素进行实证分析,运用Ordered Logit预测模型估计了六个影响因素对现阶段产学研协同创新发展问题的影响程度。研究显示,因素“政策法规的支持程度”、“知识产权保护和科技成果转化”、“多赢的合作利益分配机制”和“产学研协同创新融资渠道完善”对我国产学研协同创新发展面临的主要问题有显著影响;因素“科技中介机构服务能力提升”对“创新主体发展需求问题”的影响并不显著。

  5. Analysis on the Willingness and Influence Factors of College Students’ Profession Selection Based on Logit Model:Take the School of Management of One University for Example%基于Logit模型的高校学生专业选择和影响因素--以某大学管理学院为例

    Institute of Scientific and Technical Information of China (English)

    陈莉; 王清

    2014-01-01

    The paper analyzes the actual survey data about the students of 2012 who major in accounting in the school of management of a university based on the Logit model.The analyzed results show that the views of the parents and family members, future employment opportunities and personal interest are the main influence factors in their major selection.On the other hand, the impact of gender, academic record and birthplace of students’ are not significant.According to the results, universities should establish the Information & Research Depart-ment, strengthen the guidance and coordination of students and channel students’ major selection based on com-prehensive evaluation.By these methods, the blindness of the selection of students will be greatly reduced, the educational resources will get optimal utilization.Thus the management performance of the school can be guaran-teed and the long-term development of majors can be stable.%基于Logit模型,分析某大学管理学院2012级财会专业调查数据,结果显示:父母和家人的意见、未来的就业机会及个人兴趣是学生选择财会专业的主要影响因素,而性别、成绩、出生地对学生选择财会专业影响并不显著。基于此,学校应建立相关信息调研部门,加强对学生的指导协调,进行综合考评后再分流,这样可以较大程度降低学生专业选择的盲目性,使教育资源得到优化利用,进而确保办学效益及各专业长远的稳定发展。

  6. Research on the influencing factors of the high transfer of the GEM Listed companies--Based on Logit Model Analysis%影响创业板上市公司进行高送转的因素--基于Logit模型分析

    Institute of Scientific and Technical Information of China (English)

    王鹏; 孔刘柳

    2016-01-01

    Related to the Chinese main board market listing corporation to carry out high transfer of the impact factors, the academic community generally believe that the following aspects are the reasons for the decision of high transfer:the size of the company's share price, the size of the company's equity, the earnings per share, whether the company for the new shares and the net profit of the company for the last year. But the research on the impact factors of the high transfer of the GEM listed companies is relatively small. This paper analyzes the impact factors of high transfer of the GEM listed companies by using the behavior characteristics of the GEM listed companies in recent years to carry on the high transfer and the motivation of the high transfer. And using the Logit model to study the company’s stock price and the company’s total market value has a significant impact on the high transfer, to provide reference for the future of the company’s high transfer of the GEM.%对中国主板市场上市公司进行高送转的影响因素,学术界普遍认为:公司的股价大小;公司的股本规模;股票的每股收益;公司是否为次新股;公司上一年度的净利润等;是决定是否高送转的原因,但专门针对创业板上市公司进行高送转的影响因素研究还比较少。利用近年来创业板上市公司进行高送转的行为特征以及进行高送转的动机,分析可能影响公司进行是否高送转的影响因素,运用Logit模型实证研究公司股价和公司总市值对高送转有着显著影响,给与投资在未来选择创业板上市公司高送转的预期提供参考。

  7. Modeling cumulative effects in life cycle assessment: the case of fertilizer in wheat production contributing to the global warming potential.

    Science.gov (United States)

    Laratte, Bertrand; Guillaume, Bertrand; Kim, Junbeum; Birregah, Babiga

    2014-05-15

    This paper aims at presenting a dynamic indicator for life cycle assessment (LCA) measuring cumulative impacts over time of greenhouse gas (GHG) emissions from fertilizers used for wheat cultivation and production. Our approach offers a dynamic indicator of global warming potential (GWP), one of the most used indicator of environmental impacts (e.g. in the Kyoto Protocol). For a case study, the wheat production in France was selected and considered by using data from official sources about fertilizer consumption and production of wheat. We propose to assess GWP environmental impact based on LCA method. The system boundary is limited to the fertilizer production for 1 ton of wheat produced (functional unit) from 1910 to 2010. As applied to wheat production in France, traditional LCA shows a maximum GWP impact of 500 kg CO2-eq for 1 ton of wheat production, whereas the GWP impact of wheat production over time with our approach to dynamic LCA and its cumulative effects increases to 18,000 kg CO2-eq for 1 ton of wheat production. In this paper, only one substance and one impact assessment indicator are presented. However, the methodology can be generalized and improved by using different substances and indicators.

  8. A model for developing job rotation schedules that eliminate sequential high workloads and minimize between-worker variability in cumulative daily workloads: Application to automotive assembly lines.

    Science.gov (United States)

    Yoon, Sang-Young; Ko, Jeonghan; Jung, Myung-Chul

    2016-07-01

    The aim of study is to suggest a job rotation schedule by developing a mathematical model in order to reduce cumulative workload from the successive use of the same body region. Workload assessment using rapid entire body assessment (REBA) was performed for the model in three automotive assembly lines of chassis, trim, and finishing to identify which body part exposed to relatively high workloads at workstations. The workloads were incorporated to the model to develop a job rotation schedule. The proposed schedules prevent the exposure to high workloads successively on the same body region and minimized between-worker variance in cumulative daily workload. Whereas some of workers were successively assigned to high workload workstation under no job rotation and serial job rotation. This model would help to reduce the potential for work-related musculoskeletal disorders (WMSDs) without additional cost for engineering work, although it may need more computational time and relative complex job rotation sequences. Copyright © 2016 Elsevier Ltd and The Ergonomics Society. All rights reserved.

  9. C -IBI: Targeting cumulative coordination within an iterative protocol to derive coarse-grained models of (multi-component) complex fluids

    Science.gov (United States)

    de Oliveira, Tiago E.; Netz, Paulo A.; Kremer, Kurt; Junghans, Christoph; Mukherji, Debashish

    2016-05-01

    We present a coarse-graining strategy that we test for aqueous mixtures. The method uses pair-wise cumulative coordination as a target function within an iterative Boltzmann inversion (IBI) like protocol. We name this method coordination iterative Boltzmann inversion ( C -IBI). While the underlying coarse-grained model is still structure based and, thus, preserves pair-wise solution structure, our method also reproduces solvation thermodynamics of binary and/or ternary mixtures. Additionally, we observe much faster convergence within C -IBI compared to IBI. To validate the robustness, we apply C -IBI to study test cases of solvation thermodynamics of aqueous urea and a triglycine solvation in aqueous urea.

  10. The cumulative effect of assisted reproduction procedures on placental development and epigenetic perturbations in a mouse model.

    Science.gov (United States)

    de Waal, Eric; Vrooman, Lisa A; Fischer, Erin; Ord, Teri; Mainigi, Monica A; Coutifaris, Christos; Schultz, Richard M; Bartolomei, Marisa S

    2015-12-15

    Assisted reproductive technologies (ART) are associated with several complications including low birth weight, abnormal placentation and increased risk for rare imprinting disorders. Indeed, experimental studies demonstrate ART procedures independent of existing infertility induce epigenetic perturbations in the embryo and extraembryonic tissues. To test the hypothesis that these epigenetic perturbations persist and result in adverse outcomes at term, we assessed placental morphology and methylation profiles in E18.5 mouse concepti generated by in vitro fertilization (IVF) in two different genetic backgrounds. We also examined embryo transfer (ET) and superovulation procedures to ascertain if they contribute to developmental and epigenetic effects. Increased placental weight and reduced fetal-to-placental weight ratio were observed in all ART groups when compared with naturally conceived controls, demonstrating that non-surgical embryo transfer alone can impact placental development. Furthermore, superovulation further induced overgrowth of the placental junctional zone. Embryo transfer and superovulation defects were limited to these morphological changes, as we did not observe any differences in epigenetic profiles. IVF placentae, however, displayed hypomethylation of imprinting control regions of select imprinted genes and a global reduction in DNA methylation levels. Although we did not detect significant differences in DNA methylation in fetal brain or liver samples, rare IVF concepti displayed very low methylation and abnormal gene expression from the normally repressed allele. Our findings suggest that individual ART procedures cumulatively increase placental morphological abnormalities and epigenetic perturbations, potentially causing adverse neonatal and long-term health outcomes in offspring.

  11. Modelling the changing cumulative vulnerability to climate-related hazards for river basin management using a GIS-based multicriteria decision approach

    Science.gov (United States)

    Hung, Hung-Chih; Wu, Ju-Yu; Hung, Chih-Hsuan

    2017-04-01

    1. Background Asia-Pacific region is one of the most vulnerable areas of the world to climate-related hazards and extremes due to rapid urbanization and over-development in hazard-prone areas. It is thus increasingly recognized that the management of land use and reduction of hazard risk are inextricably linked. This is especially critical from the perspective of integrated river basin management. A range of studies has targeted existing vulnerability assessments. However, limited attention has been paid to the cumulative effects of multiple vulnerable factors and their dynamics faced by local communities. This study proposes a novel methodology to access the changing cumulative vulnerability to climate-related hazards, and to examine the relationship between the attraction factors relevant to the general process of urbanization and vulnerability variability with a focus on a river basin management unit. 2. Methods and data The methods applied in this study include three steps. First, using Intergovernmental Panel on Climate Change's (IPCC) approach, a Cumulative Vulnerability Assessment Framework (CVAF) is built with a goal to characterize and compare the vulnerability to climate-related hazards within river basin regions based on a composition of multiple indicators. We organize these indicator metrics into three categories: (1) hazard exposure; (2) socioeconomic sensitivity, and (3) adaptive capacity. Second, the CVAF is applied by combining a geographical information system (GIS)-based spatial statistics technique with a multicriteria decision analysis (MCDA) to assess and map the changing cumulative vulnerability, comparing conditions in 1996 and 2006 in Danshui River Basin, Taiwan. Third, to examine the affecting factors of vulnerability changing, we develop a Vulnerability Changing Model (VCM) using four attraction factors to reflect how the process of urban developments leads to vulnerability changing. The factors are transport networks, land uses

  12. Cumulant expansions for atmospheric flows

    CERN Document Server

    Ait-Chaalal, Farid; Meyer, Bettina; Marston, J B

    2015-01-01

    The equations governing atmospheric flows are nonlinear, and consequently the hierarchy of cumulant equations is not closed. But because atmospheric flows are inhomogeneous and anisotropic, the nonlinearity may manifests itself only weakly through interactions of mean fields with disturbances such as thermals or eddies. In such situations, truncations of the hierarchy of cumulant equations hold promise as a closure strategy. We review how truncations at second order can be used to model and elucidate the dynamics of turbulent atmospheric flows. Two examples are considered. First, we study the growth of a dry convective boundary layer, which is heated from below, leading to turbulent upward energy transport and growth of the boundary layer. We demonstrate that a quasilinear truncation of the equations of motion, in which interactions of disturbances among each other are neglected but interactions with mean fields are taken into account, can successfully capture the growth of the convective boundary layer. Seco...

  13. Repeated mild lateral fluid percussion brain injury in the rat causes cumulative long-term behavioral impairments, neuroinflammation, and cortical loss in an animal model of repeated concussion.

    Science.gov (United States)

    Shultz, Sandy R; Bao, Feng; Omana, Vanessa; Chiu, Charlotte; Brown, Arthur; Cain, Donald Peter

    2012-01-20

    There is growing evidence that repeated brain concussion can result in cumulative and long-term behavioral symptoms, neuropathological changes, and neurodegeneration. Little is known about the factors and mechanisms that contribute to these effects. The current study addresses the need to investigate and better understand the effects of repeated concussion through the development of an animal model. Male Long-Evans rats received 1, 3, or 5 mild lateral fluid percussion injuries or sham injuries spaced 5 days apart. After the final injury, rats received either a short (24 h) or long (8 weeks) post-injury recovery period, followed by a detailed behavioral analysis consisting of tests for rodent anxiety-like behavior, cognition, social behavior, sensorimotor function, and depression-like behavior. Brains were examined immunohistochemically to assess neuroinflammation and cortical damage. Rats given 1, 3, or 5 mild percussion injuries displayed significant short-term cognitive impairments. Rats given repeated mild percussion injuries displayed significantly worse short- and long-term cognitive impairments. Rats given 5 mild percussion injuries also displayed increased anxiety- and depression-like behaviors. Neuropathological analysis revealed short-term neuroinflammation in 3-injury rats, and both short- and long-term neuroinflammation in 5-injury rats. There was also evidence that repeated injuries induced short- and long-term cortical damage. These cumulative and long-term changes are consistent with findings in human patients suffering repeated brain concussion, provide support for the use of repeated mild lateral fluid percussion injuries to study repeated concussion in the rat, and suggest that neuroinflammation may be important for understanding the cumulative and chronic effects of repeated concussion.

  14. Improving the prognostic value of disease specific Graded Prognostic Assessment (ds-GPA) model for renal cell carcinoma by incorporation of Cumulative Intracranial Tumor Volume (CITV).

    Science.gov (United States)

    Ali, Mir Amaan; Hirshman, Brian R; Wilson, Bayard; Schupper, Alexander J; Joshi, Rushikesh; Proudfoot, James A; Goetsch, Steven J; Alksne, John F; Ott, Kenneth; Aiyama, Hitoshi; Nagano, Osamu; Carter, Bob S; Chiang, Veronica; Serizawa, Toru; Yamamoto, Masaaki; Chen, Clark C

    2017-07-25

    We tested the prognostic value of cumulative intracranial tumor volume (CITV) in the context of ds-GPA model for renal cell carcinoma (RCC) patients with brain metastasis (BM) treated with stereotactic radiosurgery (SRS). Patient and tumor characteristics were collected from RCC cohorts with newly BM who underwent SRS. Univariable and multivariable logistic regression model was used to test the prognostic value of CITV, Karnofsky Performance Score (KPS), and the number of BM. Net reclassification improvement (NRI) and integrated discrimination improvement (IDI) were used to assess whether CITV improved the prognostic utility of RCC ds-GPA. In univariable logistic regression models, CITV, KPS, and the number of BM independently associated with RCC patient survival. In a multivariable Cox proportional hazard model, the association between CITV and survival remained robust after controlling for KPS and the number of BM (P=.042). The incorporation of the cumulative intracranial tumor volume (CITV) into the RCC ds-GPA model (consisting of KPS and number of BM) improved prognostic accuracy with NRI>0 of 0.3156 (95% CI: 0.0883-0.5428, P=.0065) and integrated discrimination improvement (IDI) of 0.0151 (95% CI: 0.0036-0.0277, P=.0183). These findings were validated in an independent cohort of 107 SRS-treated RCC BM patients. CITV is an important prognostic variable in SRS-treated RCC patients with BM. The prognostic value of the ds-GPA scale for RCC brain metastasis was enhanced by the incorporation of CITV. Copyright © 2017 Elsevier Inc. All rights reserved.

  15. Multiple steady states, limit cycles and chaotic attractors in evolutionary games with Logit Dynamics

    NARCIS (Netherlands)

    C.H. Hommes; M.I. Ochea

    2010-01-01

    This paper investigates, by means of simple, three and four strategy games, the occurrence of periodic and chaotic behaviour in a smooth version of the Best Response Dynamics, the Logit Dynamics. The main finding is that, unlike Replicator Dynamics, generic Hopf bifurcation and thus, stable limit cy

  16. Multiple equilibria and limit cycles in evolutonary games with Logit Dynamics

    NARCIS (Netherlands)

    C.H. Hommes; M.I. Ochea

    2012-01-01

    This note shows, by means of two simple, three-strategy games, the existence of stable periodic orbits and of multiple, interior steady states in a smooth version of the Best-Response Dynamics, the Logit Dynamics. The main finding is that, unlike Replicator Dynamics, generic Hopf bifurcation and thu

  17. FACTORS THAT AFFECT TRANSPORT MODE PREFERENCE FOR GRADUATE STUDENTS IN THE NATIONAL UNIVERSITY OF MALAYSIA BY LOGIT METHOD

    Directory of Open Access Journals (Sweden)

    ALI AHMED MOHAMMED

    2013-06-01

    Full Text Available A study was carried out to examine the perceptions and preferences of students on choosing the type of transportation for their travels in university campus. This study focused on providing personal transport users road transport alternatives as a countermeasure aimed at shifting car users to other modes of transportation. Overall 456 questionnaires were conducted to develop a choice of transportation mode preferences. Consequently, Logit model and SPSS were used to identify the factors that affect the determination of the choice of transportation mode. Results indicated that by reducing travel time by 70% the amount of private cars users will be reduced by 84%, while reduction the travel cost was found to be highly improving the public modes of utilization. This study revealed positive aspects is needed to shift travellers from private modes to public. The positive aspect contributes to travel time and travel cost reduction, hence improving the services, whereby contributing to sustainability.

  18. C-IBI: Targeting cumulative coordination within an iterative protocol to derive coarse-grained models of (multi-component) complex fluids.

    Science.gov (United States)

    de Oliveira, Tiago E; Netz, Paulo A; Kremer, Kurt; Junghans, Christoph; Mukherji, Debashish

    2016-05-01

    We present a coarse-graining strategy that we test for aqueous mixtures. The method uses pair-wise cumulative coordination as a target function within an iterative Boltzmann inversion (IBI) like protocol. We name this method coordination iterative Boltzmann inversion (C-IBI). While the underlying coarse-grained model is still structure based and, thus, preserves pair-wise solution structure, our method also reproduces solvation thermodynamics of binary and/or ternary mixtures. Additionally, we observe much faster convergence within C-IBI compared to IBI. To validate the robustness, we apply C-IBI to study test cases of solvation thermodynamics of aqueous urea and a triglycine solvation in aqueous urea.

  19. A Resource Cost Aware Cumulative

    Science.gov (United States)

    Simonis, Helmut; Hadzic, Tarik

    We motivate and introduce an extension of the well-known cumulative constraint which deals with time and volume dependent cost of resources. Our research is primarily interested in scheduling problems under time and volume variable electricity costs, but the constraint equally applies to manpower scheduling when hourly rates differ over time and/or extra personnel incur higher hourly rates. We present a number of possible lower bounds on the cost, including a min-cost flow, different LP and MIP models, as well as greedy algorithms, and provide a theoretical and experimental comparison of the different methods.

  20. Physics-Based Stress Corrosion Cracking Component Reliability Model cast in an R7-Compatible Cumulative Damage Framework

    Energy Technology Data Exchange (ETDEWEB)

    Unwin, Stephen D.; Lowry, Peter P.; Layton, Robert F.; Toloczko, Mychailo B.; Johnson, Kenneth I.; Sanborn, Scott E.

    2011-07-01

    This is a working report drafted under the Risk-Informed Safety Margin Characterization pathway of the Light Water Reactor Sustainability Program, describing statistical models of passives component reliabilities.

  1. A paradox of cumulative culture.

    Science.gov (United States)

    Kobayashi, Yutaka; Wakano, Joe Yuichiro; Ohtsuki, Hisashi

    2015-08-21

    Culture can grow cumulatively if socially learnt behaviors are improved by individual learning before being passed on to the next generation. Previous authors showed that this kind of learning strategy is unlikely to be evolutionarily stable in the presence of a trade-off between learning and reproduction. This is because culture is a public good that is freely exploited by any member of the population in their model (cultural social dilemma). In this paper, we investigate the effect of vertical transmission (transmission from parents to offspring), which decreases the publicness of culture, on the evolution of cumulative culture in both infinite and finite population models. In the infinite population model, we confirm that culture accumulates largely as long as transmission is purely vertical. It turns out, however, that introduction of even slight oblique transmission drastically reduces the equilibrium level of culture. Even more surprisingly, if the population size is finite, culture hardly accumulates even under purely vertical transmission. This occurs because stochastic extinction due to random genetic drift prevents a learning strategy from accumulating enough culture. Overall, our theoretical results suggest that introducing vertical transmission alone does not really help solve the cultural social dilemma problem. Copyright © 2015 Elsevier Ltd. All rights reserved.

  2. Cumulative Timers for Microprocessors

    Science.gov (United States)

    Battle, John O.

    2007-01-01

    It has been proposed to equip future microprocessors with electronic cumulative timers, for essentially the same reasons for which land vehicles are equipped with odometers (total-distance-traveled meters) and aircraft are equipped with Hobbs meters (total-engine-operating time meters). Heretofore, there has been no way to determine the amount of use to which a microprocessor (or a product containing a microprocessor) has been subjected. The proposed timers would count all microprocessor clock cycles and could only be read by means of microprocessor instructions but, like odometers and Hobbs meters, could never be reset to zero without physically damaging the chip.

  3. Cumulative Vehicle Routing Problems

    OpenAIRE

    Kara, &#;mdat; Kara, Bahar Yeti&#;; Yeti&#;, M. Kadri

    2008-01-01

    This paper proposes a new objective function and corresponding formulations for the vehicle routing problem. The new cost function defined as the product of the distance of the arc and the flow on that arc. We call a vehicle routing problem with this new objective function as the Cumulative Vehicle Routing Problem (CumVRP). Integer programming formulations with O(n2) binary variables and O(n2) constraints are developed for both collection and delivery cases. We show that the CumVRP is a gener...

  4. Determinants of food insecurity among farming households in Katsina State, north western Nigeria: An ordinal logit regression approach

    Directory of Open Access Journals (Sweden)

    Ibrahim Hussaini Y.

    2016-01-01

    Full Text Available The study identified the determinants of food insecurity among farming households in Katsina State, north western Nigeria. A cross sectional sample survey design was used to select a total of 150 small-holder farmers from 15 communities across 10 Local Government Areas of the state. A structured questionnaire, Focus Group Discussion and Key Informant Interview were used for data collection. The coping strategy index was used to determine the food security status of the household and the ordered logit regression was used to identify the determinants of food insecurity among the households. The majority (73% were found to be food insecure. In terms of food insecurity status, 44% of the respondents were less food insecure, while 17% and 12% were moderately food insecure and severely food insecure respectively. Eating the less preferred meal, purchasing food on credit and reducing the quantity of food consumed were the major coping strategies adopted by the food insecure households. The result of the ordered logit model shows that the total quantity of cereal saved, number of income sources and dependency ratio were significant for both the moderately and severely food insecure groups at p<0.05 while access to credit was also significant for the two groups but at p<0.01. The output of other crops was significant at p=0.10 but only for the severely food insecure group. The study concluded that food insecurity was high in the study area and therefore recommended that the farming households be provided with opportunities to diversify their livelihood activities.

  5. Using simulation models to investigate the cumulative effects of sowing rate, sowing date and cultivar choice on weed competition.

    Science.gov (United States)

    Andrew, Izzadora K S; Storkey, Jonathan

    2017-05-01

    With the increasing pressure on crop production from the evolution of herbicide resistance, farmers are increasingly adopting Integrated Weed Management (IWM) strategies to augment their weed control. These include measures to increase the competitiveness of the crop canopy such as increased sowing rate and the use of more competitive cultivars. While there are data on the relative impact of these non-chemical weed control methods assessed in isolation, there is uncertainty about their combined contribution, which may be hindering their adoption. In this article, the INTERCOM simulation model of crop/weed competition was used to examine the combined impact of crop density, sowing date and cultivar choice on the outcomes of competition between wheat (Triticum aestivum) and Alopecurus myosuroides. Alopecurus myosuroides is a problematic weed of cereal crops in North-Western Europe and the primary target for IWM in the UK because it has evolved resistance to a range of herbicides. The model was parameterised for two cultivars with contrasting competitive ability, and simulations run across 10 years at different crop densities and two sowing dates. The results suggest that sowing date, sowing density and cultivar choice largely work in a complementary fashion, allowing enhanced competitive ability against weeds when used in combination. However, the relative benefit of choosing a more competitive cultivar decreases at later sowing dates and higher crop densities. Modeling approaches could be further employed to examine the effectiveness of IWM, reducing the need for more expensive and cumbersome long-term in situ experimentation.

  6. 基于累积前景理论的拥挤阈值计算模型%Calculation Model of Congestion Threshold Based on Cumulative Prospect Theory

    Institute of Scientific and Technical Information of China (English)

    冯川; 戢晓峰; 刘敏

    2014-01-01

    信息诱导是缓解交通拥挤的有效途径,为了描述道路拥挤程度对出行者路径选择决策的影响机理,基于累积前景理论分析了出行者的出行决策过程,分析了出行者拥挤认知模式以及不同出行方式的拥挤信息需求。解析了拥挤阈值的概念,将行程时间作为累积前景理论决策指标建立了拥挤阈值的计算模型,以1个简单路网进行算例分析,模拟驾驶员的拥挤认知及出行活动决策。算例结果揭示了拥挤阈值对路径选择决策行为的影响,同时验证了拥挤阈值是出行者在决策过程中的决策变化分界点。出行时间在拥挤阈值内出行者不改变出行路径;出行时间超过拥挤阈值,出行者将改变出行路径。%Releasing travel information to guide travelers'travel choice is an effective way to relieve traffic conges-tion .In order to describe the influence mechanism between road congestion extent and travelers'route choice decisions , the cumulative prospect theory is used to model travelers'decision-making process ,and the travelers'different congestion cognitive model s and congestion information demand are analyzed .The concept of road network congestion threshold is analyzed ,and the calculation model of road network congestion threshold is constructed based on Cumulative Prospect Theory (CPT) with travel time as decision index .In the numerical example part ,travelers congestion cognition and travel decisions are modeled with a simple road network .The result of numerical example reveals congestion threshold's influ-ence on route choice decisions ,and verifies that the congestion threshold is the cut-off point of decision change in travelers'decision-making process .Travelers will not change route when travel time is within congestion threshold ;when travel time exceeds the congestion threshold ,traveler will choose another route to travel .

  7. Cumulative cultural evolution: the role of teaching.

    Science.gov (United States)

    Castro, Laureano; Toro, Miguel A

    2014-04-21

    In humans, cultural transmission occurs usually by cumulative inheritance, generating complex adaptive behavioral features. Cumulative culture requires key psychological processes (fundamentally imitation and teaching) that are absent or impoverished in non-human primates. In this paper we analyze the role that teaching has played in human cumulative cultural evolution. We assume that a system of cumulative culture generates increasingly adaptive behaviors, that are also more complex and difficult to imitate. Our thesis is that, as cultural traits become more complex, cumulative cultural transmission requires teaching to ensure accurate transmission from one generation to the next. In an increasingly complex cultural environment, we consider that individuals commit errors in imitation. We develop a model of cumulative cultural evolution in a changing environment and show that these errors hamper the process of cultural accumulation. We also show that a system of teaching between parents and offspring that increases the fidelity of imitation unblocks the accumulation and becomes adaptive whenever the gain in fitness compensates the cost of teaching.

  8. Cumulative environmental effects. Summary

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    2012-07-01

    This report presents a compilation of knowledge about the state of the environment and human activity in the Norwegian part of the North Sea and Skagerrak. The report gives an overview of pressures and impacts on the environment from normal activity and in the event of accidents. This is used to assess the cumulative environmental effects, which factors have most impact and where the impacts are greatest, and to indicate which problems are expected to be most serious in the future. The report is intended to provide relevant information that can be used in the management of the marine area in the future. It also provides input for the identification of environmental targets and management measures for the North Sea and Skagerrak.(Author)

  9. Deterministic modelling of the cumulative impacts of underground structures on urban groundwater flow and the definition of a potential state of urban groundwater flow: example of Lyon, France

    Science.gov (United States)

    Attard, Guillaume; Rossier, Yvan; Winiarski, Thierry; Cuvillier, Loann; Eisenlohr, Laurent

    2016-08-01

    Underground structures have been shown to have a great influence on subsoil resources in urban aquifers. A methodology to assess the actual and the potential state of the groundwater flow in an urban area is proposed. The study develops a three-dimensional modeling approach to understand the cumulative impacts of underground infrastructures on urban groundwater flow, using a case in the city of Lyon (France). All known underground structures were integrated in the numerical model. Several simulations were run: the actual state of groundwater flow, the potential state of groundwater flow (without underground structures), an intermediate state (without impervious structures), and a transient simulation of the actual state of groundwater flow. The results show that underground structures fragment groundwater flow systems leading to a modification of the aquifer regime. For the case studied, the flow systems are shown to be stable over time with a transient simulation. Structures with drainage systems are shown to have a major impact on flow systems. The barrier effect of impervious structures was negligible because of the small hydraulic gradient of the area. The study demonstrates that the definition of a potential urban groundwater flow and the depiction of urban flow systems, which involves understanding the impact of underground structures, are important issues with respect to urban underground planning.

  10. An Axiomatization of Cumulative Prospect Theory

    NARCIS (Netherlands)

    Wakker, P.P.; Tversky, A.

    1993-01-01

    This paper presents a method for axiomatizing a variety of models for decision making under uncertainty, including Expected Utility and Cumulative Prospect Theory. This method identifies, for each model, the situations that permit consistent inferences about the ordering of value differences. Exampl

  11. A semi-parametric censoring bias model for estimating the cumulative risk of a false-positive screening test under dependent censoring

    OpenAIRE

    Hubbard, Rebecca A.; Miglioretti, Diana L.

    2013-01-01

    False-positive test results are among the most common harms of screening tests and may lead to more invasive and expensive diagnostic testing procedures. Estimating the cumulative risk of a false-positive screening test result after repeat screening rounds is therefore important for evaluating potential screening regimens. Existing estimators of the cumulative false-positive risk are limited by strong assumptions about censoring mechanisms and parametric assumptions about variation in risk ac...

  12. UBIQUITOUS POLLUTANTS FROM CUMULATIVE ...

    Science.gov (United States)

    The occurrence of pharmaceuticals and personal care products (PPCPS) as environmental pollutants is a multifaceted issue whose scope continues to become better delineated since the escalation of concerted attention beginning in the 1980s. PPCPs typically occur as trace environmental pollutants (primarily in surface but also in ground waters) as a result of their widespread, continuous, combined usage in a broad range of human and veterinary therapeutic activities and practices. With respect to the risk-assessment paradigm, the growing body of published work has focused primarily on the origin and occurrence of these substances. Comparatively less is known about human and ecological exposure, and even less about the known or even potential hazards associated with exposure to these anthropogenic substances, many of which are highly bioactive. The continually growing, worldwide importance of freshwater resources underscores the need for ensuring that any aggregate or cumulative impacts on water supplies and resultant potential for human or ecological exposure be minimized. This has prompted the more recent investigations on waste treatment processes for one of the major sources of environmental disposition, namely sewage. Despite the paucity of health effects data for long-term, simultaneous exposure to multiple xenobiotics (particularly PPCPS) at low doses (a major toxicological issue that can be described by the

  13. Establishment and Analysis of Noise Model for Cumulative Flight Events%累积飞行事件噪声模型的建立和分析

    Institute of Scientific and Technical Information of China (English)

    闫国华; 王迪; 魏晓飞; 王彪

    2013-01-01

      多年来,凡是存在机场噪声问题的国家都已先后发展起自己的评价参数,但大多是选取单次飞行事件作为研究对象,而对长期连续的飞行事件还需要考虑飞行事件的次数、飞行时间等因素.由此,基于累积飞行事件的多项数据,建立计权参数模型和最大声级估算模型.其中,对最大声级的估算,根据不同的度量指标采用了多种不同的方法.并采用Delphi7.0软件编程实现航迹的绘制和各参数的计算.研究的结果对于机场的噪声评价有一定的参考价值.%In recent decades, many countries with the problem of airport noise have developed their own evaluation parameters, but most of them selected single flight events as the research objects. However, for the long-term continuous flight events, the number of flight events, flight time and some other factors also need to be considered. In this paper, some of the parametric models based on the data of cumulative flight events were presented, including weighting parameter model and maximum sound level estimation model. Delphi7.0 software was used to draw flight traces and calculate various parameters. Results of this work provide some reference value for airport noise evaluation.

  14. Pricing and lot sizing optimization in a two-echelon supply chain with a constrained Logit demand function

    Directory of Open Access Journals (Sweden)

    Yeison Díaz-Mateus

    2017-07-01

    Full Text Available Decision making in supply chains is influenced by demand variations, and hence sales, purchase orders and inventory levels are therefore concerned. This paper presents a non-linear optimization model for a two-echelon supply chain, for a unique product. In addition, the model includes the consumers’ maximum willingness to pay, taking socioeconomic differences into account. To do so, the constrained multinomial logit for discrete choices is used to estimate demand levels. Then, a metaheuristic approach based on particle swarm optimization is proposed to determine the optimal product sales price and inventory coordination variables. To validate the proposed model, a supply chain of a technological product was chosen and three scenarios are analyzed: discounts, demand segmentation and demand overestimation. Results are analyzed on the basis of profits, lotsizing and inventory turnover and market share. It can be concluded that the maximum willingness to pay must be taken into consideration, otherwise fictitious profits may mislead decision making, and although the market share would seem to improve, overall profits are not in fact necessarily better.

  15. Injury Severity of Motorcycle Riders Involved in Traffic Crashes in Hunan, China: A Mixed Ordered Logit Approach

    Directory of Open Access Journals (Sweden)

    Fangrong Chang

    2016-07-01

    Full Text Available Issues related to motorcycle safety in China have not received enough research attention. As such, the causal relationship between injury outcomes of motorcycle crashes and potential risk factors remains unknown. This study intended to investigate the injury risk of motorcyclists involved in road traffic crashes in China. To account for the ordinal nature of response outcomes and unobserved heterogeneity, a mixed ordered logit model was employed. Given that the crash occurrence process is different between intersections and non-intersections, separate models were developed for these locations to independently estimate the impacts of various contributing factors on motorcycle riders’ injury severity. The analysis was based on the police-reported crash dataset obtained from the Traffic Administration Bureau of Hunan Provincial Public Security Ministry. Factors associated with a substantially higher probability of fatalities and severe injuries included motorcycle riders older than 60 years, the absence of helmets, motorcycle riders identified to be equal duty, and when a motorcycle collided with a heavy vehicle during the night time without lighting. Crashes occurred along county roads with curve and slope alignment or at regions with higher GDP were associated with an elevated risk of fatality of motorcycle riders, while unsignalized intersections were related to less severe injuries. Findings of this study are beneficial in forming several targeted countermeasures for motorcycle safety in China, including designing roads with appropriate road delineation and street lighting, strict enforcement for speeding and red light violations, promoting helmet usage, and improving the conspicuity of motorcyclists.

  16. Injury Severity of Motorcycle Riders Involved in Traffic Crashes in Hunan, China: A Mixed Ordered Logit Approach.

    Science.gov (United States)

    Chang, Fangrong; Li, Maosheng; Xu, Pengpeng; Zhou, Hanchu; Haque, Md Mazharul; Huang, Helai

    2016-07-14

    Issues related to motorcycle safety in China have not received enough research attention. As such, the causal relationship between injury outcomes of motorcycle crashes and potential risk factors remains unknown. This study intended to investigate the injury risk of motorcyclists involved in road traffic crashes in China. To account for the ordinal nature of response outcomes and unobserved heterogeneity, a mixed ordered logit model was employed. Given that the crash occurrence process is different between intersections and non-intersections, separate models were developed for these locations to independently estimate the impacts of various contributing factors on motorcycle riders' injury severity. The analysis was based on the police-reported crash dataset obtained from the Traffic Administration Bureau of Hunan Provincial Public Security Ministry. Factors associated with a substantially higher probability of fatalities and severe injuries included motorcycle riders older than 60 years, the absence of helmets, motorcycle riders identified to be equal duty, and when a motorcycle collided with a heavy vehicle during the night time without lighting. Crashes occurred along county roads with curve and slope alignment or at regions with higher GDP were associated with an elevated risk of fatality of motorcycle riders, while unsignalized intersections were related to less severe injuries. Findings of this study are beneficial in forming several targeted countermeasures for motorcycle safety in China, including designing roads with appropriate road delineation and street lighting, strict enforcement for speeding and red light violations, promoting helmet usage, and improving the conspicuity of motorcyclists.

  17. Population dynamics models based on cumulative density dependent feedback: A link to the logistic growth curve and a test for symmetry using aphid data

    NARCIS (Netherlands)

    Matis, J.H.; Kiffe, T.R.; Werf, van der W.; Costamagna, A.C.; Matis, T.I.; Grant, W.E.

    2009-01-01

    Density dependent feedback, based on cumulative population size, has been advocated to explain and mathematically characterize “boom and bust” population dynamics. Such feedback results in a bell-shaped population trajectory of the population density. Here, we note that this trajectory is mathematic

  18. A multinomial logit analysis of risk factors influencing road traffic injury severities in the Erzurum and Kars Provinces of Turkey.

    Science.gov (United States)

    Çelik, Ali Kemal; Oktay, Erkan

    2014-11-01

    A retrospective cross-sectional study is conducted analysing 11,771 traffic accidents reported by the police between January 2008 and December 2013 which are classified into three injury severity categories: fatal, injury, and no injury. Based on this classification, a multinomial logit analysis is performed to determine the risk factors affecting the severity of traffic injuries. The estimation results reveal that the following factors increase the probability of fatal injuries: drivers over the age of 65; primary-educated drivers; single-vehicle accidents; accidents occurring on state routes, highways or provincial roads; and the presence of pedestrian crosswalks. The results also indicate that accidents involving cars or private vehicles or those occurring during the evening peak, under clear weather conditions, on local city streets or in the presence of traffic lights decrease the probability of fatal injuries. This study comprises the most comprehensive database ever created for a Turkish sample. This study is also the first attempt to use an unordered response model to determine risk factors influencing the severity of traffic injuries in Turkey.

  19. Multinomial Logit Analysis of Small-Scale Farmers’ Choice of Organic Soil Management Practices in Bungoma County, Kenya

    Directory of Open Access Journals (Sweden)

    Oscar I. Ayuya

    2012-07-01

    Full Text Available Bungoma County is one of the areas in Kenya where maize is produced on small-scale basis; however, the County isfacing soil nutrient depletion due to continuous and unsustainable cultivation of land. Various interventions have sensitized farmers into adopting organic soil management techniques of enhancing soil fertility and upholding environmental sustainability. The study was aimedatestablishing the most preferred organic soil managementtechniques among farmers and the factors influencing the choice of these techniques. This wasbased on an exploratory study of small-scale organic maize farmers in Bungoma County.Asimple random sampling approach was used to select a sample of 150 smallholder maize farmers and primary data was collected using a semistructured questionnaire. In the analyses, descriptive statistics and a multinomial Logit model were employed using STATA computer program. The results indicated that extension, farm size household size, gender, age, education, credit, group membership, land tenure, farm distance and slope of land significantly influenced the choice of different techniques. Therefore the study recommends that policies in support of organic soil management should disaggregate farmers according to their socioeconomic, farmer and farm characteristics in order to achieve their intended objectives. Further there is need to increase extension visits to improve farmer awareness on the advantages of the various techniques.

  20. Research on sand pile model of cumulative fatigue damage%沙堆疲劳损伤累积模型的研究

    Institute of Scientific and Technical Information of China (English)

    温洁明; 陈国军; 陈家权; 吴燕瑞; 赵政飞

    2011-01-01

    由于材料具有循环硬化与软化、循环蠕变与松弛等特性,导致其在变幅循环应力作用下的疲劳损伤与加载顺序密切相关.国内外研究者提出了许多损伤累积模型,但有些模型未明确地阐述加载顺序的影响.通过分析影响疲劳损伤的重要因素,提出伴随损伤、视在损伤和耦合损伤新概念,结合模糊理论定量计算由耦合效应引起的耦合损伤,建立了一个能考虑加载顺序对疲劳损伤累积影响的沙堆疲劳损伤累积模型.选取16Mn和316L不锈钢材料的试验数据进行疲劳寿命预测,分析结果表明,所建立的模型能适用于不同加载顺序下的疲劳损伤累积计算,L-H和H-L两种加载顺序下疲劳寿命的预测结果与试验结果吻合良好,其寿命预测误差分散带基本在2倍因子内,预测精度高,便于工程应用.%The fatigue damage under variable amplitude cyclic stress is closely related with the loading sequence because of the cyclic hardening and softening cyclic creep and relaxation, and other characteristics of materials. Many domestic and foreign researchers have proposed models of damage accumulation, but some models are not explicitly described effect of the loading sequence.Therefore, new concepts of the adjoining damage, apparent damage and coupled damage were proposed by analyzing key factors affecting fatigue damage. Coupled damage produced by coupled effect was calculated quantitatively with the fuzzy theory. The sand pile model of cumulative fatigue damage is built by taking into account the effects of fatigue damage accumulation of loading sequence.Fatigue lives of 16Mn and 316L stainless steel were predicted and compared with test data. The results showed that the model can be applied to different loading sequence for calculating accumulative fatigue damage. Predicted results of fatigue life under two sequences of L-H and H-L were in good agreement with experimental ones. Scatter band of predicted

  1. Pavlovian conditioning and cumulative reinforcement rate.

    Science.gov (United States)

    Harris, Justin A; Patterson, Angela E; Gharaei, Saba

    2015-04-01

    In 5 experiments using delay conditioning of magazine approach with rats, reinforcement rate was varied either by manipulating the mean interval between onset of the conditioned stimulus (CS) and unconditioned stimulus (US) or by manipulating the proportion of CS presentations that ended with the US (trial-based reinforcement rate). Both manipulations influenced the acquisition of responding. In each experiment, a specific comparison was made between 2 CSs that differed in their mean CS-US interval and in their trial-based reinforcement rate, such that the cumulative reinforcement rate-the cumulative duration of the CS between reinforcements-was the same for the 2 CSs. For example, a CS reinforced on 100% of trials with a mean CS-US interval of 60 s was compared with a CS reinforced on 33% of trials and a mean duration of 20 s. Across the 5 experiments, conditioning was virtually identical for the 2 CSs with matched cumulative reinforcement rate. This was true as long as the timing of the US was unpredictable and, thus, response rates were uniform across the length of the CS. We conclude that the effects of CS-US interval and of trial-based reinforcement rate are reducible entirely to their common effect on cumulative reinforcement rate. We discuss the implications of this for rate-based, trial-based, and real-time associative models of conditioning.

  2. Complexity and demographic explanations of cumulative culture.

    Directory of Open Access Journals (Sweden)

    Adrien Querbes

    Full Text Available Formal models have linked prehistoric and historical instances of technological change (e.g., the Upper Paleolithic transition, cultural loss in Holocene Tasmania, scientific progress since the late nineteenth century to demographic change. According to these models, cumulation of technological complexity is inhibited by decreasing--while favoured by increasing--population levels. Here we show that these findings are contingent on how complexity is defined: demography plays a much more limited role in sustaining cumulative culture in case formal models deploy Herbert Simon's definition of complexity rather than the particular definitions of complexity hitherto assumed. Given that currently available empirical evidence doesn't afford discriminating proper from improper definitions of complexity, our robustness analyses put into question the force of recent demographic explanations of particular episodes of cultural change.

  3. Lattice QCD results on cumulant ratios at freeze-out

    CERN Document Server

    Karsch, Frithjof

    2016-01-01

    Ratios of cumulants of net proton-number fluctuations measured by the STAR Collaboration show strong deviations from a skellam distribution, which should describe thermal properties of cumulant ratios, if proton-number fluctuations are generated in equilibrium and a hadron resonance gas (HRG) model would provide a suitable description of thermodynamics at the freeze-out temperature. We present some results on sixth order cumulants entering the calculation of the QCD equation of state at non-zero values of the baryon chemical potential (mu_B) and discuss limitations on the applicability of HRG thermodynamics deduced from a comparison between QCD and HRG model calculations of cumulants of conserved charge fluctuations. We show that basic features of the $\\mu_B$-dependence of skewness and kurtosis ratios of net proton-number fluctuations measured by the STAR Collaboration resemble those expected from a O(mu_B^2) QCD calculation of the corresponding net baryon-number cumulant ratios.

  4. Investigating the gender differences on bicycle-vehicle conflicts at urban intersections using an ordered logit methodology.

    Science.gov (United States)

    Stipancic, Joshua; Zangenehpour, Sohail; Miranda-Moreno, Luis; Saunier, Nicolas; Granié, Marie-Axelle

    2016-12-01

    In the literature, a crash-based modeling approach has long been used to evaluate the factors that contribute to cyclist injury risk at intersections. However, this approach has been criticized as crashes are required to occur before contributing factors can be identified and countermeasures can be implemented. Moreover, human factors related to dangerous behaviors are difficult to evaluate using crash-based methods. As an alternative, surrogate safety measures have been developed to address the issue of reliance on crash data. Despite recent developments, few methodologies and little empirical evidence exist on bicycle-vehicle interactions at intersections using video-based data and statistical analyses to identify associated factors. This study investigates bicycle-vehicle conflict severity and evaluates the impact of different factors, including gender, on cyclist risk at urban intersections with cycle tracks. A segmented ordered logit model is used to evaluate post-encroachment time between cyclists and vehicles. Video data was collected at seven intersections in Montreal, Canada. Road user trajectories were automatically extracted, classified, and filtered using a computer vision software to yield 1514 interactions. The discrete choice variable was generated by dividing post-encroachment time into normal interactions, conflicts, and dangerous conflicts. Independent variables reflecting attributes of the cyclist, vehicle, and environment were extracted either automatically or manually. Results indicated that an ordered model is appropriate for analyzing traffic conflicts and identifying key factors. Furthermore, exogenous segmentation was beneficial in comparing different segments of the population within a single model. Male cyclists, with all else being equal, were less likely than female cyclists to be involved in conflicts and dangerous conflicts at the studied intersections. Bicycle and vehicle speed, along with the time of the conflict relative to the red

  5. The consumer’s choice among television displays: A multinomial logit approach

    Directory of Open Access Journals (Sweden)

    Carlos Giovanni González Espitia

    2013-07-01

    Full Text Available The consumer’s choice over a bundle of products depends on observable and unobservable characteristics of goods and consumers. This choice is made in order to maximize utility subject to a budget constraint. At the same time, firms make product differentiation decisions to maximize profit. Quality is a form of differentiation. An example of this occurs in the TV market, where several displays are developed. Our objective is to determine the probability for a consumer of choosing a type of display from among five kinds: standard tube, LCD, plasma, projection and LED. Using a multinomial logit approach, we find that electronic appliances like DVDs and audio systems, as well as socioeconomic status, increase the probability of choosing a high-tech television display. Our empirical approximation contributes to further understanding rational consumer behavior through the theory of utility maximization and highlights the importance of studying market structure and analyzing changes in welfare and efficiency.

  6. Stability of Mixed-Strategy-Based Iterative Logit Quantal Response Dynamics in Game Theory

    CERN Document Server

    Zhuang, Qian; Wu, Jinshan

    2013-01-01

    Using the Logit quantal response form as the response function in each step, the original definition of static quantal response equilibrium (QRE) is extended into an iterative evolution process. QREs remain as the fixed points of the dynamic process. However, depending on whether such fixed points are the long-term solutions of the dynamic process, they can be classified into stable (SQREs) and unstable (USQREs) equilibriums. This extension resembles the extension from static Nash equilibriums (NEs) to evolutionary stable solutions in the framework of evolutionary game theory. The relation between SQREs and other solution concepts of games, including NEs and QREs, is discussed. Using experimental data from other published papers, we perform a preliminary comparison between SQREs, NEs, QREs and the observed behavioral outcomes of those experiments. For certain games, we determine that SQREs have better predictive power than QREs and NEs.

  7. Sample size determination for logistic regression on a logit-normal distribution.

    Science.gov (United States)

    Kim, Seongho; Heath, Elisabeth; Heilbrun, Lance

    2017-06-01

    Although the sample size for simple logistic regression can be readily determined using currently available methods, the sample size calculation for multiple logistic regression requires some additional information, such as the coefficient of determination ([Formula: see text]) of a covariate of interest with other covariates, which is often unavailable in practice. The response variable of logistic regression follows a logit-normal distribution which can be generated from a logistic transformation of a normal distribution. Using this property of logistic regression, we propose new methods of determining the sample size for simple and multiple logistic regressions using a normal transformation of outcome measures. Simulation studies and a motivating example show several advantages of the proposed methods over the existing methods: (i) no need for [Formula: see text] for multiple logistic regression, (ii) available interim or group-sequential designs, and (iii) much smaller required sample size.

  8. Stability of mixed-strategy-based iterative logit quantal response dynamics in game theory.

    Science.gov (United States)

    Zhuang, Qian; Di, Zengru; Wu, Jinshan

    2014-01-01

    Using the Logit quantal response form as the response function in each step, the original definition of static quantal response equilibrium (QRE) is extended into an iterative evolution process. QREs remain as the fixed points of the dynamic process. However, depending on whether such fixed points are the long-term solutions of the dynamic process, they can be classified into stable (SQREs) and unstable (USQREs) equilibriums. This extension resembles the extension from static Nash equilibriums (NEs) to evolutionary stable solutions in the framework of evolutionary game theory. The relation between SQREs and other solution concepts of games, including NEs and QREs, is discussed. Using experimental data from other published papers, we perform a preliminary comparison between SQREs, NEs, QREs and the observed behavioral outcomes of those experiments. For certain games, we determine that SQREs have better predictive power than QREs and NEs.

  9. Structural Vibration Monitoring Using Cumulative Spectral Analysis

    Directory of Open Access Journals (Sweden)

    Satoru Goto

    2013-01-01

    Full Text Available This paper describes a resonance decay estimation for structural health monitoring in the presence of nonstationary vibrations. In structural health monitoring, the structure's frequency response and resonant decay characteristics are very important for understanding how the structure changes. Cumulative spectral analysis (CSA estimates the frequency decay by using the impulse response. However, measuring the impulse response of buildings is impractical due to the need to shake the building itself. In a previous study, we reported on system damping monitoring using cumulative harmonic analysis (CHA, which is based on CSA. The current study describes scale model experiments on estimating the hidden resonance decay under non-stationary noise conditions by using CSA for structural condition monitoring.

  10. A Monte Carlo simulation study comparing linear regression, beta regression, variable-dispersion beta regression and fractional logit regression at recovering average difference measures in a two sample design.

    Science.gov (United States)

    Meaney, Christopher; Moineddin, Rahim

    2014-01-24

    In biomedical research, response variables are often encountered which have bounded support on the open unit interval--(0,1). Traditionally, researchers have attempted to estimate covariate effects on these types of response data using linear regression. Alternative modelling strategies may include: beta regression, variable-dispersion beta regression, and fractional logit regression models. This study employs a Monte Carlo simulation design to compare the statistical properties of the linear regression model to that of the more novel beta regression, variable-dispersion beta regression, and fractional logit regression models. In the Monte Carlo experiment we assume a simple two sample design. We assume observations are realizations of independent draws from their respective probability models. The randomly simulated draws from the various probability models are chosen to emulate average proportion/percentage/rate differences of pre-specified magnitudes. Following simulation of the experimental data we estimate average proportion/percentage/rate differences. We compare the estimators in terms of bias, variance, type-1 error and power. Estimates of Monte Carlo error associated with these quantities are provided. If response data are beta distributed with constant dispersion parameters across the two samples, then all models are unbiased and have reasonable type-1 error rates and power profiles. If the response data in the two samples have different dispersion parameters, then the simple beta regression model is biased. When the sample size is small (N0 = N1 = 25) linear regression has superior type-1 error rates compared to the other models. Small sample type-1 error rates can be improved in beta regression models using bias correction/reduction methods. In the power experiments, variable-dispersion beta regression and fractional logit regression models have slightly elevated power compared to linear regression models. Similar results were observed if the

  11. Transient and cumulative memory impairments induced by GSM 1.8 GHz cell phone signal in a mouse model.

    Science.gov (United States)

    Ntzouni, Maria P; Skouroliakou, Aikaterini; Kostomitsopoulos, Nikolaos; Margaritis, Lukas H

    2013-03-01

    This study was designed to investigate the transient and cumulative impairments in spatial and non-spatial memory of C57Bl/6J mice exposed to GSM 1.8 GHz signal for 90 min daily by a typical cellular (mobile) phone at a specific absorption rate value of 0.11 W/kg. Free-moving male mice 2 months old were irradiated in two experimental protocols, lasting for 66 and for 148 days respectively. Each protocol used three groups of animals (n = 8 each for exposed, sham exposed and controls) in combination with two behavioural paradigms, the object recognition task and the object location task sequentially applied at different time points. One-way analysis of variance revealed statistically significant impairments of both types of memory gradually accumulating, with more pronounced effects on the spatial memory. The impairments persisted even 2 weeks after interruption of the 8 weeks daily exposure, whereas the memory of mice as detected by both tasks showed a full recovery approximately 1 month later. Intermittent every other day exposure for 1 month had no effect on both types of memory. The data suggest that visual information processing mechanisms in hippocampus, perirhinal and entorhinal cortex are gradually malfunctioning upon long-term daily exposure, a phenotype that persists for at least 2 weeks after interruption of radiation, returning to normal memory performance levels 4 weeks later. It is postulated that cellular repair mechanisms are operating to eliminate the memory affecting molecules. The overall contribution of several possible mechanisms to the observed cumulative and transient impairments in spatial and non-spatial memory is discussed.

  12. Expansive Soil Crack Depth under Cumulative Damage

    Directory of Open Access Journals (Sweden)

    Bei-xiao Shi

    2014-01-01

    Full Text Available The crack developing depth is a key problem to slope stability of the expansive soil and its project governance and the crack appears under the roles of dry-wet cycle and gradually develops. It is believed from the analysis that, because of its own cohesion, the expansive soil will have a certain amount of deformation under pulling stress but without cracks. The soil body will crack only when the deformation exceeds the ultimate tensile strain that causes cracks. And it is also believed that, due to the combined effect of various environmental factors, particularly changes of the internal water content, the inherent basic physical properties of expansive soil are weakened, and irreversible cumulative damages are eventually formed, resulting in the development of expansive soil cracks in depth. Starting from the perspective of volumetric strain that is caused by water loss, considering the influences of water loss rate and dry-wet cycle on crack developing depth, the crack developing depth calculation model which considers the water loss rate and the cumulative damages is established. Both the proposal of water loss rate and the application of cumulative damage theory to the expansive soil crack development problems try to avoid difficulties in matrix suction measurement, which will surely play a good role in promoting and improving the research of unsaturated expansive soil.

  13. Innovativeness, population size and cumulative cultural evolution.

    Science.gov (United States)

    Kobayashi, Yutaka; Aoki, Kenichi

    2012-08-01

    Henrich [Henrich, J., 2004. Demography and cultural evolution: how adaptive cultural processes can produce maladaptive losses-the Tasmanian case. Am. Antiquity 69, 197-214] proposed a model designed to show that larger population size facilitates cumulative cultural evolution toward higher skill levels. In this model, each newborn attempts to imitate the most highly skilled individual of the parental generation by directly-biased social learning, but the skill level he/she acquires deviates probabilistically from that of the exemplar (cultural parent). The probability that the skill level of the imitator exceeds that of the exemplar can be regarded as the innovation rate. After reformulating Henrich's model rigorously, we introduce an overlapping-generations analog based on the Moran model and derive an approximate formula for the expected change per generation of the highest skill level in the population. For large population size, our overlapping-generations model predicts a much larger effect of population size than Henrich's discrete-generations model. We then investigate by way of Monte Carlo simulations the case where each newborn chooses as his/her exemplar the most highly skilled individual from among a limited number of acquaintances. When the number of acquaintances is small relative to the population size, we find that a change in the innovation rate contributes more than a proportional change in population size to the cumulative cultural evolution of skill level.

  14. Electro-cumulation CNF project

    CERN Document Server

    Grishin, V G

    2000-01-01

    bound or free ion current within solid substances; non-plain symmetry; cumulation of the ion interaction. Experimental result: an Ice SuperPolarization. Cold nuclear fusion ? At http://www.shortway.to/to2084 . Keywords: ion, current, solid, symmetry, cumulation, cold nuclear fusion, polarization, depolarization, ionic conductor, superionic conductor, ice, crystal, strain, V-center, V-centre, doped crystal, interstitial impurity, intrinsic color center, high pressure technology, Bridgman, experiment, crowdion, dielectric, proton, layer, defect, lattice, dynamics, electromigration, mobility, muon catalysis, concentration, doping, dopant, conductivity, pycnonuclear reaction, permittivity, dielectric constant, point defects, interstitials, polarizability, imperfection, defect centers, glass, epitaxy, sodium hydroxide, metallic substrate, crystallization, point, tip, susceptibility, ferroelectric, ordering, force, correlation, collective, shift, distortion, coalescence, crowdions, electrolysis.

  15. Cumulative Paired φ-Entropy

    Directory of Open Access Journals (Sweden)

    Ingo Klein

    2016-07-01

    Full Text Available A new kind of entropy will be introduced which generalizes both the differential entropy and the cumulative (residual entropy. The generalization is twofold. First, we simultaneously define the entropy for cumulative distribution functions (cdfs and survivor functions (sfs, instead of defining it separately for densities, cdfs, or sfs. Secondly, we consider a general “entropy generating function” φ, the same way Burbea et al. (IEEE Trans. Inf. Theory 1982, 28, 489–495 and Liese et al. (Convex Statistical Distances; Teubner-Verlag, 1987 did in the context of φ-divergences. Combining the ideas of φ-entropy and cumulative entropy leads to the new “cumulative paired φ-entropy” ( C P E φ . This new entropy has already been discussed in at least four scientific disciplines, be it with certain modifications or simplifications. In the fuzzy set theory, for example, cumulative paired φ-entropies were defined for membership functions, whereas in uncertainty and reliability theories some variations of C P E φ were recently considered as measures of information. With a single exception, the discussions in the scientific disciplines appear to be held independently of each other. We consider C P E φ for continuous cdfs and show that C P E φ is rather a measure of dispersion than a measure of information. In the first place, this will be demonstrated by deriving an upper bound which is determined by the standard deviation and by solving the maximum entropy problem under the restriction of a fixed variance. Next, this paper specifically shows that C P E φ satisfies the axioms of a dispersion measure. The corresponding dispersion functional can easily be estimated by an L-estimator, containing all its known asymptotic properties. C P E φ is the basis for several related concepts like mutual φ-information, φ-correlation, and φ-regression, which generalize Gini correlation and Gini regression. In addition, linear rank tests for scale that

  16. Some Characterization Results on Dynamic Cumulative Residual Tsallis Entropy

    Directory of Open Access Journals (Sweden)

    Madan Mohan Sati

    2015-01-01

    Full Text Available We propose a generalized cumulative residual information measure based on Tsallis entropy and its dynamic version. We study the characterizations of the proposed information measure and define new classes of life distributions based on this measure. Some applications are provided in relation to weighted and equilibrium probability models. Finally the empirical cumulative Tsallis entropy is proposed to estimate the new information measure.

  17. Steps and pips in the history of the cumulative recorder.

    OpenAIRE

    Lattal, Kennon A.

    2004-01-01

    From its inception in the 1930s until very recent times, the cumulative recorder was the most widely used measurement instrument in the experimental analysis of behavior. It was an essential instrument in the discovery and analysis of schedules of reinforcement, providing the first real-time analysis of operant response rates and patterns. This review traces the evolution of the cumulative recorder from Skinner's early modified kymographs through various models developed by Skinner and his co...

  18. Climate mitigation: sustainable preferences and cumulative carbon

    Science.gov (United States)

    Buckle, Simon

    2010-05-01

    We develop a stylized AK growth model with both climate damages to ecosystem goods and services and sustainable preferences that allow trade-offs between present discounted utility and long-run climate damages. The simplicity of the model permits analytical solutions. Concern for the long-term provides a strong driver for mitigation action. One plausible specification of sustainable preferences leads to the result that, for a range of initial parameter values, an optimizing agent would choose a level of cumulative carbon dioxide (CO2) emissions independent of initial production capital endowment and CO2 levels. There is no technological change so, for economies with sufficiently high initial capital and CO2 endowments, optimal mitigation will lead to disinvestment. For lower values of initial capital and/or CO2 levels, positive investment can be optimal, but still within the same overall level of cumulative emissions. One striking aspect of the model is the complexity of possible outcomes, in addition to these optimal solutions. We also identify a resource constrained region and several regions where climate damages exceed resources available for consumption. Other specifications of sustainable preferences are discussed, as is the case of a hard constraint on long-run damages. Scientists are currently highlighting the potential importance of the cumulative carbon emissions concept as a robust yet flexible target for climate policymakers. This paper shows that it also has an ethical interpretation: it embodies an implicit trade off in global welfare between present discounted welfare and long-term climate damages. We hope that further development of the ideas presented here might contribute to the research and policy debate on the critical areas of intra- and intergenerational welfare.

  19. Development of a prediction model and estimation of cumulative risk for upper aerodigestive tract cancer on the basis of the aldehyde dehydrogenase 2 genotype and alcohol consumption in a Japanese population

    Science.gov (United States)

    Koyanagi, Yuriko N.; Ito, Hidemi; Oze, Isao; Hosono, Satoyo; Tanaka, Hideo; Abe, Tetsuya; Shimizu, Yasuhiro; Hasegawa, Yasuhisa

    2017-01-01

    Alcohol consumption and the aldehyde dehydrogenase 2 (ALDH2) polymorphism are associated with the risk of upper aerodigestive tract cancer, and a significant gene–environment interaction between the two has been confirmed in a Japanese population. To aid the development of a personalized prevention strategy, we developed a risk-prediction model and estimated absolute risks stratified by a combination of the ALDH2 genotype and alcohol consumption. We carried out two age-matched and sex-matched case–control studies: one (630 cases and 1260 controls) for model derivation and the second (654 cases and 654 controls) for external validation. On the basis of data from the derivation study, a prediction model was developed by fitting a conditional logistic regression model using the following predictors: age, sex, smoking, drinking, and the ALDH2 genotype. The risk model, including a combination of the ALDH2 genotype and alcohol consumption, provided high discriminatory accuracy and good calibration in both the derivation and the validation studies: C statistics were 0.82 (95% confidence interval 0.80–0.84) and 0.83 (95% confidence interval 0.81–0.85), respectively, and the calibration plots of both studies remained close to the ideal calibration line. Cumulative risks were obtained by combining odds ratios estimated from the risk model with the age-specific incidence rate and population size. For heavy drinkers with a heterozygous genotype, the cumulative risk at age 80 was above 20%. In contrast, risk in the other groups was less than 5%. In conclusion, modification of alcohol consumption according to the ALDH2 genotype will have a major impact on upper aerodigestive tract cancer prevention. These findings represent a simple and practical model for personalized cancer prevention. PMID:26862830

  20. The Algebra of the Cumulative Percent Operation.

    Science.gov (United States)

    Berry, Andrew J.

    2002-01-01

    Discusses how to help students avoid some pervasive reasoning errors in solving cumulative percent problems. Discusses the meaning of ."%+b%." the additive inverse of ."%." and other useful applications. Emphasizes the operational aspect of the cumulative percent concept. (KHR)

  1. Adaptive strategies for cumulative cultural learning.

    Science.gov (United States)

    Ehn, Micael; Laland, Kevin

    2012-05-21

    The demographic and ecological success of our species is frequently attributed to our capacity for cumulative culture. However, it is not yet known how humans combine social and asocial learning to generate effective strategies for learning in a cumulative cultural context. Here we explore how cumulative culture influences the relative merits of various pure and conditional learning strategies, including pure asocial and social learning, critical social learning, conditional social learning and individual refiner strategies. We replicate the Rogers' paradox in the cumulative setting. However, our analysis suggests that strategies that resolved Rogers' paradox in a non-cumulative setting may not necessarily evolve in a cumulative setting, thus different strategies will optimize cumulative and non-cumulative cultural learning.

  2. "Buddha's Light" of Cumulative Particles

    CERN Document Server

    Kopeliovich, Vladimir B; Potashnikova, Irina K

    2014-01-01

    We show analytically that in the cumulative particles production off nuclei multiple interactions lead to a glory-like backward focusing effect. Employing the small phase space method we arrived at a characteristic angular dependence of the production cross section $d\\sigma \\sim 1/ \\sqrt {\\pi - \\theta}$ near the strictly backward direction. This effect takes place for any number $n\\geq 3 $ of interactions of rescattered particle, either elastic or inelastic (with resonance excitations in intermediate states), when the final particle is produced near corresponding kinematical boundary. Such a behaviour of the cross section near the backward direction is in qualitative agreement with some of available data.

  3. The effect evaluation of the cumulative assessment model in nursing safety control%累计考核管理模式在护理安全管理中应用的效果评价

    Institute of Scientific and Technical Information of China (English)

    谢惠兰; 罗敏; 欧阳庆; 刘玉娥; 成放群; 周利华; 胡碧波; 周扬飞; 张晓玲

    2014-01-01

    目的 探索累计考核管理模式在护理安全管理中的应用及效果评价.方法 在原有“累计扣分制”被动处罚式的管理模式的基础上逐步建立主动预防式的安全管理模式.以5个试点病房为研究对象,比较实施前后护士安全意识及患者安全文化的认知、不良事件主动报告、护理质量及患者满意度的变化情况.结果 5个试点病房的护理人员安全意识及患者安全文化的认知度提高,不良事件主动呈报率较前增多,护理质量及患者满意度提高.结论 通过建立累计考核管理模式改变了以前“扣分、批评、通报、处罚”的管理模式,强化了护士的安全认知和安全行为,构建了积极的患者安全文化氛围,采用“不惩罚”及“保密”的原则,系统地收集、分析、梳理、总结、共享不良事件信息,并着重分析系统层面、管理因素、环境因素的综合成因,逐步实现从系统的角度处理安全隐患的风险管理策略,达到前馈控制安全事件的发生,形成一个利用差错信息来提高护理质量和患者安全的主动预防式管理模式.%Objective To explore the application and the effect evaluation of cumulative assessment management model in nursing safety control.Methods The original passive punishment management such as "cumulative deduction model" was gradually transformed into active precaution safety management model.The objects of research were 5 wards that the cumulative assessment model was applied to.The results were used to compare the changes of the nurses' safety consciousness,patients' safety culture cognition,spontaneous reporting of the adverse events,nursing quality and patients satisfaction before and after the implementation of active precaution safety management.Results In the 5 wards,nurses' safety consciousness and patients' safety culture cognition were improved; the spontaneous reporting of the adverse events increased and the nursing

  4. INCLUSION OF THE LATENT PERSONALITY VARIABLE IN MULTINOMIAL LOGIT MODELS USING THE 16PF PSYCHOMETRIC TEST

    Directory of Open Access Journals (Sweden)

    JORGE E. CÓRDOBA MAQUILÓN

    2012-01-01

    Full Text Available Los modelos de demanda de viajes utilizan principalmente los atributos modales y las características socioeconómicas como variables explicativas. También se ha establecido que las actitudes y percepciones influyen en el comportamiento de los usuarios. Sin embargo, las variables psicológicas del individuo condicionan la conducta del usuario. En este estudio se incluyó la variable latente personalidad, en la estimación del modelo híbrido de elección discreta, el cual constituye una buena alternativa para incorporar los efectos de los factores subjetivos. La variable latente personalidad se evaluó con la prueba psicométrica 16PF de validez internacional. El artículo analiza los resultados de la aplicación de este modelo a una población de empleados y docentes universitarios, y también propone un camino para la utilización de pruebas psicométricas en los modelos híbridos de elección discreta. Nuestros resultados muestran que los modelos híbridos que incluyen variables latentes psicológicas son superiores a los modelos tradicionales que ignoran los efectos de la conducta de los usuarios.

  5. Minimum Wages and Teenagers' Enrollment--Employment Outcomes: A Multinominal Logit Model.

    Science.gov (United States)

    Ehrenberg, Ronald G.; Marcus, Alan J.

    1982-01-01

    This paper tests the hypothesis that the effect of minimum wage legislation on teenagers' education decisions is asymmetrical across family income classes, with the legislation inducing children from low-income families to reduce their levels of schooling and children from higher-income families to increase their educational attainment. (Author)

  6. Associating crash avoidance maneuvers with driver attributes and accident characteristics: a mixed logit model approach

    DEFF Research Database (Denmark)

    Kaplan, Sigal; Prato, Carlo Giacomo

    2012-01-01

    from the key role of proactive and state-aware road users within the concept of sustainable safety systems, as well as from the key role of effective corrective maneuvers in the success of automated in-vehicle warning and driver assistance systems. Methods: The analysis is conducted by means of a mixed...... the propensity to perform crash avoidance maneuvers, and (5) visual obstruction and artificial illumination decrease the probability to carry out crash avoidance maneuvers. Conclusions: The results emphasize the need for public awareness campaigns to promote safe driving style for senior drivers and warning...

  7. Patterns of dupuytren disease in fingers : studying correlations with a multivariate ordinal logit model

    NARCIS (Netherlands)

    Lanting, Rosanne M.D.; Nooraee, Nazanin; Werker, Paul M.N.; van den Heuvel, Edwin R.

    BACKGROUND: Dupuytren disease affects fingers in a variable fashion. Knowledge about specific disease patterns (phenotype) based on location and severity of the disease is lacking. METHODS: In this cross-sectional study, 344 primary affected hands with Dupuytren disease were physically examined. The

  8. Risk factors associated with bus accident severity in the United States: A generalized ordered logit model

    DEFF Research Database (Denmark)

    Kaplan, Sigal; Prato, Carlo Giacomo

    2012-01-01

    Introduction: Recent years have witnessed a growing interest in improving bus safety operations worldwide. While in the United States buses are considered relatively safe, the number of bus accidents is far from being negligible, triggering the introduction of the Motor-coach Enhanced Safety Act...... that accident severity increases: (i) for young bus drivers under the age of 25; (ii) for drivers beyond the age of 55, and most prominently for drivers over 65 years old; (iii) for female drivers; (iv) for very high (over 65 mph) and very low (under 20 mph) speed limits; (v) at intersections; (vi) because...

  9. Patterns of dupuytren disease in fingers : studying correlations with a multivariate ordinal logit model

    NARCIS (Netherlands)

    Lanting, Rosanne M.D.; Nooraee, Nazanin; Werker, Paul M.N.; van den Heuvel, Edwin R.

    2014-01-01

    BACKGROUND: Dupuytren disease affects fingers in a variable fashion. Knowledge about specific disease patterns (phenotype) based on location and severity of the disease is lacking. METHODS: In this cross-sectional study, 344 primary affected hands with Dupuytren disease were physically examined. The

  10. A PHYSIOLOGICALLY BASED PHARMACOKINETIC/PHARMACODYNAMIC (PBPK/PD) MODEL FOR ESTIMATION OF CUMULATIVE RISK FROM EXPOSURE TO THREE N-METHYL CARBAMATES: CARBARYL, ALDICARB, AND CARBOFURAN

    Science.gov (United States)

    A physiologically-based pharmacokinetic (PBPK) model for a mixture of N-methyl carbamate pesticides was developed based on single chemical models. The model was used to compare urinary metabolite concentrations to levels from National Health and Nutrition Examination Survey (NHA...

  11. KINETICS OF CORTISOL METABOLISM AND EXCRETION - A HYPOTHETICAL MODEL BASED ON THE CUMULATIVE URINARY RADIOACTIVITY IN 8 MULTIPLE PITUITARY DEFICIENT PATIENTS

    NARCIS (Netherlands)

    KRAAN, GPB; DRAYER, NM; DEBRUIN, R

    A new model is proposed to study the kinetics of [H-3]cortisol metabolism by using urinary data only. The model consists of 5 pools, in which changes of the fractions of dose are given by a system of 5 ordinary differential equations. After i.v. administration of [H-3]cortisol to 8 multiple

  12. Completing the Remedial Sequence and College-Level Credit-Bearing Math: Comparing Binary, Cumulative, and Continuation Ratio Logistic Regression Models

    Science.gov (United States)

    Davidson, J. Cody

    2016-01-01

    Mathematics is the most common subject area of remedial need and the majority of remedial math students never pass a college-level credit-bearing math class. The majorities of studies that investigate this phenomenon are conducted at community colleges and use some type of regression model; however, none have used a continuation ratio model. The…

  13. KINETICS OF CORTISOL METABOLISM AND EXCRETION - A HYPOTHETICAL MODEL BASED ON THE CUMULATIVE URINARY RADIOACTIVITY IN 8 MULTIPLE PITUITARY DEFICIENT PATIENTS

    NARCIS (Netherlands)

    KRAAN, GPB; DRAYER, NM; DEBRUIN, R

    1992-01-01

    A new model is proposed to study the kinetics of [H-3]cortisol metabolism by using urinary data only. The model consists of 5 pools, in which changes of the fractions of dose are given by a system of 5 ordinary differential equations. After i.v. administration of [H-3]cortisol to 8 multiple pituitar

  14. Completing the Remedial Sequence and College-Level Credit-Bearing Math: Comparing Binary, Cumulative, and Continuation Ratio Logistic Regression Models

    Science.gov (United States)

    Davidson, J. Cody

    2016-01-01

    Mathematics is the most common subject area of remedial need and the majority of remedial math students never pass a college-level credit-bearing math class. The majorities of studies that investigate this phenomenon are conducted at community colleges and use some type of regression model; however, none have used a continuation ratio model. The…

  15. Association between diastolic blood pressure and cumulative work time

    Directory of Open Access Journals (Sweden)

    Ricardo Cordeiro

    1999-01-01

    Full Text Available Diastolic blood pressure was viewed as a generic indicator of aging, and its association with cumulative work time was studied after controlling for age as a potential confounding factor. The study was conducted among production line workers at a Brazilian tannery in July 1993. The association between diastolic blood pressure and cumulative work time was verified by fitting a second-order linear regression model, where diastolic blood pressure was a function of worker's age and cumulative work time. By fitting the model, one can predict that, in the beginning of working life at the tannery, on average each 1-year period is associated with an increase of about 1.5 mmHg in diastolic blood pressure. The fit obtained highlights one component directly associated with work as part of the rate of pressure increase in the study group. This component is twice as high as that directly associated with age.

  16. Session: What do we know about cumulative or population impacts

    Energy Technology Data Exchange (ETDEWEB)

    Kerlinger, Paul; Manville, Al; Kendall, Bill

    2004-09-01

    This session at the Wind Energy and Birds/Bats workshop consisted of a panel discussion followed by a discussion/question and answer period. The panelists were Paul Kerlinger, Curry and Kerlinger, LLC, Al Manville, U.S. Fish and Wildlife Service, and Bill Kendall, US Geological Service. The panel addressed the potential cumulative impacts of wind turbines on bird and bat populations over time. Panel members gave brief presentations that touched on what is currently known, what laws apply, and the usefulness of population modeling. Topics addressed included which sources of modeling should be included in cumulative impacts, comparison of impacts from different modes of energy generation, as well as what research is still needed regarding cumulative impacts of wind energy development on bird and bat populations.

  17. Cumulant dynamics in a finite population linkage equilibrium theory

    CERN Document Server

    Rattray, M; Rattray, Magnus; Shapiro, Jonathan L.

    1999-01-01

    The evolution of a finite population at linkage equilibrium is described in terms of the dynamics of phenotype distribution cumulants. This provides a powerful method for describing evolutionary transients and we elucidate the relationship between the cumulant dynamics and the diffusion approximation. A separation of time-scales between the first and higher cumulants for low mutation rates is demonstrated in the diffusion limit and provides a significant simplification of the dynamical system. However, the diffusion limit may not be appropriate for strong selection as the standard Fisher-Wright model of genetic drift can break down in this case. Two novel examples of this effect are considered: we shown that the dynamics may depend on the number of loci under strong directional selection and that environmental variance results in a reduced effective population size. We also consider a simple model of a changing environment which cannot be described by a diffusion equation and we derive the optimal mutation ra...

  18. Cumulative Advantage and Success-Breeds-Success: The Value of Time Pattern Analysis.

    Science.gov (United States)

    Huber, John C.

    1998-01-01

    For the case of the distribution of papers across authors, the Success-Breeds-Success or Cumulative Advantage model is a popular candidate for informetrics. The method of time pattern of publication for individual authors can be used to discriminate between Cumulative Advantage and non-uniform giftedness models. The non-uniform giftedness model is…

  19. The selective neuronal nitric oxide synthase inhibitor 7-nitroindazole has acute analgesic but not cumulative effects in a rat model of peripheral neuropathy

    Directory of Open Access Journals (Sweden)

    Henry JL

    2011-03-01

    Full Text Available Liliane J Dableh, James L HenryDepartment of Psychiatry and Behavioural Neurosciences, McMaster University, Hamilton, Ontario, CanadaAbstract: Chronic neuropathic pain that may arise from various nerve injuries or insults remains notoriously difficult to manage. The neuronal isoform of the enzyme nitric oxide synthase (nNOS has been shown to be involved in the spinal transmission of nociception in animal models of chronic pain. The aim of this study is to evaluate the effect of single dose and repeated administration of a selective nNOS inhibitor. Rats were unilaterally implanted with a 2-mm polyethylene cuff around the sciatic nerve. Paw withdrawal thresholds were measured using von Frey filament stimulation. Rats were given 10, 20, or 30 mg/kg of 7-nitroindazole (7-NI, or vehicle, on days 2, 5, and 7 after model induction, respectively. Paw withdrawal thresholds were measured before and at 30 and 60 min after injection. 7-NI significantly increased paw withdrawal thresholds at 60 min at the 20 and 30 mg/kg dosages. In the second part of this study, rats were given 20 mg/kg 7-NI daily for five days starting immediately after cuff implantation (days 0 to 4, and the cuff was removed on day 4. Withdrawal thresholds were measured intermittently over a 24-day observation period. No differences in withdrawal thresholds were observed between drug and vehicle-treated rats. Therefore, early and repeated administration of 7-NI did not affect the development or progression of the model. In conclusion, inhibition of nNOS had an analgesic but not a pre-emptive effect in this model of peripheral neuropathic pain.Keywords: neuronal nitric oxide synthase, nitric oxide, 7-nitroindazole, neuropathic pain, peripheral nerve injury, nociception 

  20. Cumulate Fragments in Silicic Ignimbrites

    Science.gov (United States)

    Bachmann, O.; Ellis, B. S.; Wolff, J.

    2014-12-01

    Increasingly, studies are concluding that silicic ignimbrites are the result of the amalgamation of multiple discrete magma batches. Yet the existence of discrete batches presents a conundrum for magma generation and storage; if silicic magma batches are not generated nearly in situ in the upper crust, they must traverse, and reside within, a thermally hostile environment with large temperature gradients, resulting in low survivability in their shallow magmatic hearths. The Snake River Plain (Idaho, USA) is a type example of this 'multi-batch' assembly with ignimbrites containing multiple populations of pyroxene crystals, glass shards, and crystal aggregates. The ubiquitous crystal aggregates hint at a mechanism to facilitate the existence of multiple, relatively small batches of rhyolite in the upper crust. These aggregates contain the same plagioclase, pyroxene, and oxide mineral compositions as single phenocrysts of the same minerals in their host rocks, but they have significantly less silicic bulk compositions and lack quartz and sanidine, which occur as single phenocrysts in the deposits. This implies significant crystallization followed by melt extraction from mushy reservoir margins. The extracted melt then continues to evolve (crystallizing sanidine and quartz) while the melt-depleted margins provide an increasingly rigid and refractory network segregating the crystal-poor batches of magma. The hot, refractory, margins insulate the crystal-poor lenses, allowing (1) extended residence in the upper crust, and (2) preservation of chemical heterogeneities among batches. In contrast, systems that produce cumulates richer in low-temperature phases (quartz, K-feldspars, and/or biotite) favour remelting upon recharge, leading to less segregation of eruptible melt pockets and the formation of gradationally zoned ignimbrites. The occurrence of similar crystal aggregates from a variety of magmatic lineages suggests the generality of this process.

  1. Latino Mothers' Cumulative Food Insecurity Exposure and Child Body Composition.

    Science.gov (United States)

    Hernandez, Daphne C

    2016-01-01

    To document whether an intergenerational transmission of food insecurity is occurring by assessing low-income foreign-born Latino mothers' experiences with food insecurity as none, once (either childhood or adulthood) or twice (during both childhood and adulthood). Also the association between maternal cumulative food insecurity and children's body composition was examined. Maternal self-reported surveys on retrospective measures of food insecurity during childhood, current measures of food insecurity, and demographics were collected from Houston-area community centers (N = 96). Children's body mass index (BMI) and waist circumference (WC) were directly assessed. Covariate-adjusted logistic regression models analyzed the association between cumulative food insecurity experiences and children's body composition. Fifty-eight percent of mothers experienced food insecurity both as a child and as an adult and 31% of the mothers experienced food insecurity either as a child or adult. Maternal cumulative exposure to food insecurity was unrelated to BMI but was negatively related to elevated WC. Although an intergenerational transmission of food insecurity does exist, maternal cumulative exposure to food insecurity does not impact children's body composition negatively in the short term. Studying the long-term effects of cumulative food insecurity exposure can provide information for the development and timing of obesity interventions.

  2. Hydrolytic Cleavage Products of Globin Adducts in Urine as Possible Biomarkers of Cumulative Dose: Proof of Concept Using Styrene Oxide as a Model Adduct-Forming Compound.

    Science.gov (United States)

    Mráz, Jaroslav; Hanzlíková, Iveta; Moulisová, Alena; Dušková, Šárka; Hejl, Kamil; Bednářová, Aneta; Dabrowská, Ludmila; Linhart, Igor

    2016-04-18

    A new experimental model was designed to study the fate of globin adducts with styrene 7,8-oxide (SO), a metabolic intermediate of styrene and a model electrophilic compound. Rat erythrocytes were incubated with SO at 7 or 22 °C. Levels of specific amino acid adducts in globin were determined by LC/MS analysis of the globin hydrolysate, and erythrocytes with known adduct content were administered intravenously to recipient rats. The course of adduct elimination from the rat blood was measured over the following 50 days. In the erythrocytes incubated at 22 °C, a rapid decline in the adduct levels on the first day post-transfusion followed by a slow phase of elimination was observed. In contrast, the adduct elimination in erythrocytes incubated at 7 °C was nearly linear, copying elimination of intact erythrocytes. In the urine of recipient rats, regioisomeric SO adducts at cysteine, valine, lysine, and histidine in the form of amino acid adducts and/or their acetylated metabolites as well as SO-dipeptide adducts were identified by LC/MS supported by synthesized reference standards. S-(2-Hydroxy-1-phenylethyl)cysteine and S-(2-hydroxy-2-phenylethyl)cysteine, the most abundant globin adducts, were excreted predominantly in the form of the corresponding urinary mercapturic acids (HPEMAs). Massive elimination of HPEMAs via urine occurred within the first day from the erythrocytes incubated at both 7 and 22 °C. However, erythrocytes incubated at 7 °C also showed a slow second phase of elimination such that HPEMAs were detected in urine up to 50 days post-transfusion. These results indicate for the first time that globin adducts can be cleaved in vivo to modified amino acids and dipeptides. The cleavage products and/or their predictable metabolites are excreted in urine over the whole life span of erythrocytes. Some of the urinary adducts may represent a new type of noninvasive biomarker for exposure to adduct-forming chemicals.

  3. Cumulative human impacts on marine predators

    DEFF Research Database (Denmark)

    Maxwell, Sara M; Hazen, Elliott L; Bograd, Steven J

    2013-01-01

    Stressors associated with human activities interact in complex ways to affect marine ecosystems, yet we lack spatially explicit assessments of cumulative impacts on ecologically and economically key components such as marine predators. Here we develop a metric of cumulative utilization and impact...

  4. Cumulative pion production via successive collisions in nuclear medium

    CERN Document Server

    Motornenko, A

    2016-01-01

    Production of pions in proton-nucleus (p+A) reactions outside of a kinematical boundary of proton-nucleon collisions, the so-called cumulative effect, is studied. The kinematical restrictions on pions emitted in backward direction in the target rest frame are analyzed. It is shown that cumulative pion production requires a presence of massive baryonic resonances that are produced during successive collisions of projectile with nuclear nucleons. After each successive collision the mass of created resonance may increase and, simultaneously, its longitudinal velocity decreases. Simulations within Ultra relativistic Quantum Molecular Dynamics model reveals that successive collisions of baryonic resonances with nuclear nucleons plays the dominant role in cumulative pion production in p+A reactions.

  5. Effect of correlation on cumulants in heavy-ion collisions

    CERN Document Server

    Mishra, D K; Netrakanti, P K

    2015-01-01

    We study the effects of correlation on cumulants and their ratios of net-proton multiplicity distribution which have been measured for central (0-5\\%) Au+Au collisions at Relativistic Heavy Ion Collider (RHIC). This effect has been studied assuming individual proton and anti-proton distributions as Poisson or Negative Binomial Distribution (NBD). In-spite of significantly correlated production due to baryon number, electric charge conservation and kinematical correlations of protons and anti-protons, the measured cumulants of net-proton distribution follow the independent production model. In the present work we demonstrate how the introduction of correlations will affect the cumulants and their ratios for the difference distributions. We have also demonstrated this study using the proton and anti-proton distributions obtained from HIJING event generator.

  6. A Mixed Model Approach to Meta-Analysis of Diagnostic Studies with Binary Test Outcome

    Science.gov (United States)

    Doebler, Philipp; Holling, Heinz; Bohning, Dankmar

    2012-01-01

    We propose 2 related models for the meta-analysis of diagnostic tests. Both models are based on the bivariate normal distribution for transformed sensitivities and false-positive rates. Instead of using the logit as a transformation for these proportions, we employ the "t"[subscript alpha] family of transformations that contains the log, logit,…

  7. A Parametric Cumulative Sum Statistic for Person Fit

    Science.gov (United States)

    Armstrong, Ronald D.; Shi, Min

    2009-01-01

    This article develops a new cumulative sum (CUSUM) statistic to detect aberrant item response behavior. Shifts in behavior are modeled with quadratic functions and a series of likelihood ratio tests are used to detect aberrancy. The new CUSUM statistic is compared against another CUSUM approach as well as traditional person-fit statistics. A…

  8. Hierarchical Bayesian parameter estimation for cumulative prospect theory

    NARCIS (Netherlands)

    Nilsson, H.; Rieskamp, J.; Wagenmakers, E.-J.

    2011-01-01

    Cumulative prospect theory (CPT Tversky & Kahneman, 1992) has provided one of the most influential accounts of how people make decisions under risk. CPT is a formal model with parameters that quantify psychological processes such as loss aversion, subjective values of gains and losses, and

  9. A Parametric Cumulative Sum Statistic for Person Fit

    Science.gov (United States)

    Armstrong, Ronald D.; Shi, Min

    2009-01-01

    This article develops a new cumulative sum (CUSUM) statistic to detect aberrant item response behavior. Shifts in behavior are modeled with quadratic functions and a series of likelihood ratio tests are used to detect aberrancy. The new CUSUM statistic is compared against another CUSUM approach as well as traditional person-fit statistics. A…

  10. Cumulative Interarrival Time Distributions of Freeway Entrance Ramp Traffic for Traffic Simulations

    Directory of Open Access Journals (Sweden)

    Erdinç Öner

    2013-02-01

    Full Text Available Cumulative interarrival time (IAT distributions for signalized and non-signalized freeway entrance ramps were developed to be used in digital computer traffic simulation models. The data from four different non-signalized entrance ramps (three ramps with a single lane, one ramp with two lanes and two different signalized entrance ramps (both with a single lane were used for developing the cumulative IAT distributions. The cumulative IAT distributions for the signalized and non-signalized entrance ramps were compared with each other and with the cumulative IAT distributions of the lanes for freeways. The comparative results showed that the cumulative IAT distributions for non-signalized entrance ramps are very close to the leftmost lane of a 3-lane freeway where the maximum absolute difference between the cumulative IAT distribution of the leftmost lane of a 3-lane freeway and the entrance ramps cumulative IAT distribution was 3%. The cumulative IAT distribution for the signalized entrance ramps was found to be different from the non-signalized entrance ramp cumulative IAT distribution. The approximated cumulative IAT distributions for signalized and non-signalized entrance ramp traffic for any hourly traffic volume from a few vehicles/hour up to 2,500 vehicles/hour can be obtained at http://www.ohio.edu/orite/research/uitds.cfm.

  11. Sufficient Sample Size and Power in Multilevel Ordinal Logistic Regression Models

    Directory of Open Access Journals (Sweden)

    Sabz Ali

    2016-01-01

    Full Text Available For most of the time, biomedical researchers have been dealing with ordinal outcome variable in multilevel models where patients are nested in doctors. We can justifiably apply multilevel cumulative logit model, where the outcome variable represents the mild, severe, and extremely severe intensity of diseases like malaria and typhoid in the form of ordered categories. Based on our simulation conditions, Maximum Likelihood (ML method is better than Penalized Quasilikelihood (PQL method in three-category ordinal outcome variable. PQL method, however, performs equally well as ML method where five-category ordinal outcome variable is used. Further, to achieve power more than 0.80, at least 50 groups are required for both ML and PQL methods of estimation. It may be pointed out that, for five-category ordinal response variable model, the power of PQL method is slightly higher than the power of ML method.

  12. Sufficient Sample Size and Power in Multilevel Ordinal Logistic Regression Models

    Science.gov (United States)

    Ali, Amjad; Khan, Sajjad Ahmad; Hussain, Sundas

    2016-01-01

    For most of the time, biomedical researchers have been dealing with ordinal outcome variable in multilevel models where patients are nested in doctors. We can justifiably apply multilevel cumulative logit model, where the outcome variable represents the mild, severe, and extremely severe intensity of diseases like malaria and typhoid in the form of ordered categories. Based on our simulation conditions, Maximum Likelihood (ML) method is better than Penalized Quasilikelihood (PQL) method in three-category ordinal outcome variable. PQL method, however, performs equally well as ML method where five-category ordinal outcome variable is used. Further, to achieve power more than 0.80, at least 50 groups are required for both ML and PQL methods of estimation. It may be pointed out that, for five-category ordinal response variable model, the power of PQL method is slightly higher than the power of ML method.

  13. Cumulative Damage Model for Advanced Composite Materials.

    Science.gov (United States)

    1982-07-01

    ultimately used an exponential in the present example for added simplicity) and we norma - lize the function so that it becomes the modifier that determines...Testing and Design (Second Conference), ASTM STP 497, ASTM (1972) pp. 170-188. 5. Halpin, J. C., et al., "Characterization of Composites for the...Graphite Epoxy Composites," Proc. Symposium on Composite Materials: Testing and Design, ASTM , (Ma’rch 20, 1978) New Orleans, LA. 18. Hashin, Z. and Rotem

  14. Variable cultural acquisition costs constrain cumulative cultural evolution.

    Directory of Open Access Journals (Sweden)

    Alex Mesoudi

    Full Text Available One of the hallmarks of the human species is our capacity for cumulative culture, in which beneficial knowledge and technology is accumulated over successive generations. Yet previous analyses of cumulative cultural change have failed to consider the possibility that as cultural complexity accumulates, it becomes increasingly costly for each new generation to acquire from the previous generation. In principle this may result in an upper limit on the cultural complexity that can be accumulated, at which point accumulated knowledge is so costly and time-consuming to acquire that further innovation is not possible. In this paper I first review existing empirical analyses of the history of science and technology that support the possibility that cultural acquisition costs may constrain cumulative cultural evolution. I then present macroscopic and individual-based models of cumulative cultural evolution that explore the consequences of this assumption of variable cultural acquisition costs, showing that making acquisition costs vary with cultural complexity causes the latter to reach an upper limit above which no further innovation can occur. These models further explore the consequences of different cultural transmission rules (directly biased, indirectly biased and unbiased transmission, population size, and cultural innovations that themselves reduce innovation or acquisition costs.

  15. Cumulative cultural learning: Development and diversity.

    Science.gov (United States)

    Legare, Cristine H

    2017-07-24

    The complexity and variability of human culture is unmatched by any other species. Humans live in culturally constructed niches filled with artifacts, skills, beliefs, and practices that have been inherited, accumulated, and modified over generations. A causal account of the complexity of human culture must explain its distinguishing characteristics: It is cumulative and highly variable within and across populations. I propose that the psychological adaptations supporting cumulative cultural transmission are universal but are sufficiently flexible to support the acquisition of highly variable behavioral repertoires. This paper describes variation in the transmission practices (teaching) and acquisition strategies (imitation) that support cumulative cultural learning in childhood. Examining flexibility and variation in caregiver socialization and children's learning extends our understanding of evolution in living systems by providing insight into the psychological foundations of cumulative cultural transmission-the cornerstone of human cultural diversity.

  16. Calculating Cumulative Binomial-Distribution Probabilities

    Science.gov (United States)

    Scheuer, Ernest M.; Bowerman, Paul N.

    1989-01-01

    Cumulative-binomial computer program, CUMBIN, one of set of three programs, calculates cumulative binomial probability distributions for arbitrary inputs. CUMBIN, NEWTONP (NPO-17556), and CROSSER (NPO-17557), used independently of one another. Reliabilities and availabilities of k-out-of-n systems analyzed. Used by statisticians and users of statistical procedures, test planners, designers, and numerical analysts. Used for calculations of reliability and availability. Program written in C.

  17. Origin of path independence between cumulative CO2 emissions and global warming

    Science.gov (United States)

    Seshadri, Ashwin K.

    2017-02-01

    Observations and GCMs exhibit approximate proportionality between cumulative carbon dioxide (CO2 ) emissions and global warming. Here we identify sufficient conditions for the relationship between cumulative CO2 emissions and global warming to be independent of the path of CO2 emissions; referred to as "path independence". Our starting point is a closed form expression for global warming in a two-box energy balance model (EBM), which depends explicitly on cumulative emissions, airborne fraction and time. Path independence requires that this function can be approximated as depending on cumulative emissions alone. We show that path independence arises from weak constraints, occurring if the timescale for changes in cumulative emissions (equal to ratio between cumulative emissions and emissions rate) is small compared to the timescale for changes in airborne fraction (which depends on CO2 uptake), and also small relative to a derived climate model parameter called the damping-timescale, which is related to the rate at which deep-ocean warming affects global warming. Effects of uncertainties in the climate model and carbon cycle are examined. Large deep-ocean heat capacity in the Earth system is not necessary for path independence, which appears resilient to climate modeling uncertainties. However long time-constants in the Earth system carbon cycle are essential, ensuring that airborne fraction changes slowly with timescale much longer than the timescale for changes in cumulative emissions. Therefore path independence between cumulative emissions and warming cannot arise for short-lived greenhouse gases.

  18. Asymptotic growth of cumulative and regenerative beam break-up instabilities in accelerators

    Science.gov (United States)

    Lau, Y. Y.

    1988-06-01

    It is found that the asymptotic growth of the cumulative beam break up instability is independent of the focusing magnetic field, according to the model of Panofsky and Bander. The analysis is extended to include the transition from the cumulative to the regenerative type, both in the presence and absence of a focusing magnetic field.

  19. Human cumulative culture: a comparative perspective.

    Science.gov (United States)

    Dean, Lewis G; Vale, Gill L; Laland, Kevin N; Flynn, Emma; Kendal, Rachel L

    2014-05-01

    Many animals exhibit social learning and behavioural traditions, but human culture exhibits unparalleled complexity and diversity, and is unambiguously cumulative in character. These similarities and differences have spawned a debate over whether animal traditions and human culture are reliant on homologous or analogous psychological processes. Human cumulative culture combines high-fidelity transmission of cultural knowledge with beneficial modifications to generate a 'ratcheting' in technological complexity, leading to the development of traits far more complex than one individual could invent alone. Claims have been made for cumulative culture in several species of animals, including chimpanzees, orangutans and New Caledonian crows, but these remain contentious. Whilst initial work on the topic of cumulative culture was largely theoretical, employing mathematical methods developed by population biologists, in recent years researchers from a wide range of disciplines, including psychology, biology, economics, biological anthropology, linguistics and archaeology, have turned their attention to the experimental investigation of cumulative culture. We review this literature, highlighting advances made in understanding the underlying processes of cumulative culture and emphasising areas of agreement and disagreement amongst investigators in separate fields.

  20. Effective Carrier Sensing in CSMA Networks under Cumulative Interference

    CERN Document Server

    Fu, Liqun; Huang, Jianwei

    2009-01-01

    This paper proposes and investigates the concept of a safe carrier-sensing range that can guarantee interference safe (also termed hidden-node-free) transmissions in CSMA networks under the cumulative interference model. Compared with the safe carrier-sensing range under the commonly assumed but less realistic pairwise interference model, we show that the safe carrier-sensing range required under the cumulative interference model is larger by a constant multiplicative factor. The concept of a safe carrier-sensing range, although amenable to elegant analytical results, is inherently not compatible with the conventional power threshold carrier-sensing mechanism (e.g., that used in IEEE 802.11). Specifically, the absolute power sensed by a node in the conventional mechanism does not contain enough information for it to derive its distances from other concurrent transmitter nodes. We show that, fortunately, a carrier-sensing mechanism called Incremental-Power Carrier-Sensing (IPCS) can realize the carrier-sensing...

  1. Analysis on Influent Factors Affecting Vocational School Students' Mathematics Learning Based on Cumulative Logistic Model%职校生数学成绩影响因素的累积LOGISTIC模型分析

    Institute of Scientific and Technical Information of China (English)

    张旭; 刘玉春; 杨志红; 霍素凤

    2012-01-01

    利用累积Logistic模型对影响职校生数学成绩的因素进行了实证分析,研究结论显示,影响职校生数学成绩的主要因素是学生的计算能力、学习主动性以及家长对学生学习的关注,这与职业学校生源的复杂性和职业学校数学教育的特殊性有关.ROC分析表明,利用计算能力、学习主动性、家长的关注三个因素诊断学生数学成绩是合适的,提示教师要特别关注学生计算能力、学习能力的培养,督促家长关注孩子的学习.%Cumulative Logistic model is introduced to analyze influent factors impacting vocational school students' math learning. Results show that ability to calculate,active learning and concern of parents are major factors affecting vocational school students' math learning,it is related to the complexity of students and the special nature of math education in vocational schools. ROC analysis shows that it is appropriate to use computing power of students,active learning and concern of parents to diagnose students' math scores,and suggests that teachers should pay special attention to train students' computing ability and learning ability,and urge parents to concern about children's learning.

  2. Cumulative dietary exposure of the population of Denmark to pesticides

    DEFF Research Database (Denmark)

    Jensen, Bodil Hamborg; Petersen, Annette; Nielsen, Elsa

    2015-01-01

    We used the Hazard Index (HI) method to carry out a cumulative risk assessment after chronic dietary exposure to all monitored pesticides in fruit, vegetables and cereals for various consumer groups in Denmark. Residue data for all the pesticides were obtained from the Danish monitoring programme...... that included processing factors and set non-detects to ½ LOR, but limited the correction (Model 3), gave the most realistic exposure estimate. With Model 3 the HI was calculated to be 0.44 for children and 0.18 for adults, indicating that there is no risk of adverse health effects following chronic cumulative...... exposure to the pesticides found in fruit, vegetables and cereals on the Danish market. The HI was below 1 even for consumers who eat more than 550 g of fruit and vegetables per day, corresponding to 1/3 of the population. Choosing Danish-produced commodities whenever possible could reduce the HI...

  3. Cumulative Culture and Future Thinking: Is Mental Time Travel a Prerequisite to Cumulative Cultural Evolution?

    Science.gov (United States)

    Vale, G. L.; Flynn, E. G.; Kendal, R. L.

    2012-01-01

    Cumulative culture denotes the, arguably, human capacity to build on the cultural behaviors of one's predecessors, allowing increases in cultural complexity to occur such that many of our cultural artifacts, products and technologies have progressed beyond what a single individual could invent alone. This process of cumulative cultural evolution…

  4. Cumulative Effect of Depression on Dementia Risk

    Directory of Open Access Journals (Sweden)

    J. Olazarán

    2013-01-01

    Full Text Available Objective. To analyze a potential cumulative effect of life-time depression on dementia and Alzheimer’s disease (AD, with control of vascular factors (VFs. Methods. This study was a subanalysis of the Neurological Disorders in Central Spain (NEDICES study. Past and present depression, VFs, dementia status, and dementia due to AD were documented at study inception. Dementia status was also documented after three years. Four groups were created according to baseline data: never depression (nD, past depression (pD, present depression (prD, and present and past depression (prpD. Logistic regression was used. Results. Data of 1,807 subjects were investigated at baseline (mean age 74.3, 59.3% women, and 1,376 (81.6% subjects were evaluated after three years. The prevalence of dementia at baseline was 6.7%, and dementia incidence was 6.3%. An effect of depression was observed on dementia prevalence (OR [CI 95%] 1.84 [1.01–3.35] for prD and 2.73 [1.08–6.87] for prpD, and on dementia due to AD (OR 1.98 [0.98–3.99] for prD and OR 3.98 [1.48–10.71] for prpD (fully adjusted models, nD as reference. Depression did not influence dementia incidence. Conclusions. Present depression and, particularly, present and past depression are associated with dementia at old age. Multiple mechanisms, including toxic effect of depression on hippocampal neurons, plausibly explain these associations.

  5. 4D Near-Field Source Localization Using Cumulant

    Directory of Open Access Journals (Sweden)

    Zhao Feng

    2007-01-01

    Full Text Available This paper proposes a new cumulant-based algorithm to jointly estimate four-dimensional (4D source parameters of multiple near-field narrowband sources. Firstly, this approach proposes a new cross-array, and constructs five high-dimensional Toeplitz matrices using the fourth-order cumulants of some properly chosen sensor outputs; secondly, it forms a parallel factor (PARAFAC model in the cumulant domain using these matrices, and analyzes the unique low-rank decomposition of this model; thirdly, it jointly estimates the frequency, two-dimensional (2D directions-of-arrival (DOAs, and range of each near-field source from the matrices via the low-rank three-way array (TWA decomposition. In comparison with some available methods, the proposed algorithm, which efficiently makes use of the array aperture, can localize sources using sensors. In addition, it requires neither pairing parameters nor multidimensional search. Simulation results are presented to validate the performance of the proposed method.

  6. 4D Near-Field Source Localization Using Cumulant

    Directory of Open Access Journals (Sweden)

    Junying Zhang

    2007-01-01

    Full Text Available This paper proposes a new cumulant-based algorithm to jointly estimate four-dimensional (4D source parameters of multiple near-field narrowband sources. Firstly, this approach proposes a new cross-array, and constructs five high-dimensional Toeplitz matrices using the fourth-order cumulants of some properly chosen sensor outputs; secondly, it forms a parallel factor (PARAFAC model in the cumulant domain using these matrices, and analyzes the unique low-rank decomposition of this model; thirdly, it jointly estimates the frequency, two-dimensional (2D directions-of-arrival (DOAs, and range of each near-field source from the matrices via the low-rank three-way array (TWA decomposition. In comparison with some available methods, the proposed algorithm, which efficiently makes use of the array aperture, can localize N−3 sources using N sensors. In addition, it requires neither pairing parameters nor multidimensional search. Simulation results are presented to validate the performance of the proposed method.

  7. Is cumulated pyrethroid exposure associated with prediabetes?

    DEFF Research Database (Denmark)

    Hansen, Martin Rune; Jørs, Erik; Lander, Flemming;

    2014-01-01

    , cumulative exposure) was assessed from questionnaire data. Participants were asked about symptoms of diabetes. Blood samples were analyzed for glycosylated hemoglobin (HbA1c), a measure of glucose regulation. No association was found between pyrethroid exposure and diabetes symptoms. The prevalence...

  8. Cumulative Disadvantage among the Highly Ambitious.

    Science.gov (United States)

    McClelland, Katherine

    1990-01-01

    Using a social reproduction theory framework, analyzes the process by which high school seniors aspiring to high-level positions are sorted out after graduation. Analyzes early educational attainments and changes in occupational expectations. Shows a process of cumulative disadvantage in which White males are more likely to achieve their goals.…

  9. Cumulative Disadvantage among the Highly Ambitious.

    Science.gov (United States)

    McClelland, Katherine

    1990-01-01

    Using a social reproduction theory framework, analyzes the process by which high school seniors aspiring to high-level positions are sorted out after graduation. Analyzes early educational attainments and changes in occupational expectations. Shows a process of cumulative disadvantage in which White males are more likely to achieve their goals.…

  10. Analisis Probabilitas Perpindahan Moda Dari Bus Ke Kereta Api Siliwangi Jurusan Sukabumi-Cianjur Menggunakan Analisis Regresi Logit Biner

    Directory of Open Access Journals (Sweden)

    Muhammad Fatoni Nurdiansyah

    2015-03-01

    Full Text Available Pemerintah mulai mengaktifkan kembali jalur kereta api jurusan Sukabumi – Cianjur, pengaktifan KA Siliwangi diharapkan mampu memaksimalkan pengangkutan dan pelayanan terhadap penumpang dan barang serta memberikan alternatif pilihan moda kepada warga Sukabumi dan Cianjur. Sehingga dengan menggunakan KA Siliwangi diharapkan bisa menghindari masalah yang dialami oleh pengguna akses jalan raya, seperti kemacetan yang disebabkan oleh perbaikan jalan dan aktifitas industri yang sering dialami oleh pengguna kendaraan pribadi dan kendaraan umum di jalan Sukabumi-Cianjur. Teknik Stated Preference digunakan untuk mendapatkan data primer dengan penyebaran kuisioner kepada penumpang bus jurusan Sukabumi –Cianjur. Data yang diperoleh dari penyebaran kuisioner kemudian dianalisa. Hal yang dianalisa yaitu karakteristik penumpang bus serta kesediaan penumpang bus untuk beralih menggunakan moda kereta api. Untuk menganalisa probabilitas digunakan logit biner untuk memudahkan proses analisa. Dengan analisa regresi logistik biner diharapkan probabilitas perpindahan moda dapat diketahui. Dari hasil regresi didapatkan dari analisa regresi logistik biner didapatkan penumpang 61,92% dari 239 responden yang bersedia pindah dari bus ke KA Siliwangi tujuan Sukabumi-Cianjur, dengan 53 orang responden (39,3% yang menginginkan tarif sebesar Rp 20.000 dan 135 orang responden (56,5% waktu tempuh yang diharapkan selama 60 menit menggunakan KA Siliwangi

  11. Seasonal climate change patterns due to cumulative CO2 emissions

    Science.gov (United States)

    Partanen, Antti-Ilari; Leduc, Martin; Damon Matthews, H.

    2017-07-01

    Cumulative CO2 emissions are near linearly related to both global and regional changes in annual-mean surface temperature. These relationships are known as the transient climate response to cumulative CO2 emissions (TCRE) and the regional TCRE (RTCRE), and have been shown to remain approximately constant over a wide range of cumulative emissions. Here, we assessed how well this relationship holds for seasonal patterns of temperature change, as well as for annual-mean and seasonal precipitation patterns. We analyzed an idealized scenario with CO2 concentration growing at an annual rate of 1% using data from 12 Earth system models from the Coupled Model Intercomparison Project Phase 5 (CMIP5). Seasonal RTCRE values for temperature varied considerably, with the highest seasonal variation evident in the Arctic, where RTCRE was about 5.5 °C per Tt C for boreal winter and about 2.0 °C per Tt C for boreal summer. Also the precipitation response in the Arctic during boreal winter was stronger than during other seasons. We found that emission-normalized seasonal patterns of temperature change were relatively robust with respect to time, though they were sub-linear with respect to emissions particularly near the Arctic. Moreover, RTCRE patterns for precipitation could not be quantified robustly due to the large internal variability of precipitation. Our results suggest that cumulative CO2 emissions are a useful metric to predict regional and seasonal changes in precipitation and temperature. This extension of the TCRE framework to seasonal and regional climate change is helpful for communicating the link between emissions and climate change to policy-makers and the general public, and is well-suited for impact studies that could make use of estimated regional-scale climate changes that are consistent with the carbon budgets associated with global temperature targets.

  12. Finite-volume cumulant expansion in QCD-colorless plasma

    Energy Technology Data Exchange (ETDEWEB)

    Ladrem, M. [Taibah University, Physics Department, Faculty of Science, Al-Madinah, Al-Munawwarah (Saudi Arabia); Physics Department, Algiers (Algeria); ENS-Vieux Kouba (Bachir El-Ibrahimi), Laboratoire de Physique et de Mathematiques Appliquees (LPMA), Algiers (Algeria); Ahmed, M.A.A. [Taibah University, Physics Department, Faculty of Science, Al-Madinah, Al-Munawwarah (Saudi Arabia); ENS-Vieux Kouba (Bachir El-Ibrahimi), Laboratoire de Physique et de Mathematiques Appliquees (LPMA), Algiers (Algeria); Taiz University in Turba, Physics Department, Taiz (Yemen); Alfull, Z.Z. [Taibah University, Physics Department, Faculty of Science, Al-Madinah, Al-Munawwarah (Saudi Arabia); Cherif, S. [ENS-Vieux Kouba (Bachir El-Ibrahimi), Laboratoire de Physique et de Mathematiques Appliquees (LPMA), Algiers (Algeria); Ghardaia University, Sciences and Technologies Department, Ghardaia (Algeria)

    2015-09-15

    Due to the finite-size effects, the localization of the phase transition in finite systems and the determination of its order, become an extremely difficult task, even in the simplest known cases. In order to identify and locate the finite-volume transition point T{sub 0}(V) of the QCD deconfinement phase transition to a colorless QGP, we have developed a new approach using the finite-size cumulant expansion of the order parameter and the L{sub mn}-method. The first six cumulants C{sub 1,2,3,4,5,6} with the corresponding under-normalized ratios (skewness Σ, kurtosis κ, pentosis Π{sub ±}, and hexosis H{sub 1,2,3}) and three unnormalized combinations of them, (O = σ{sup 2}κΣ{sup -1},U = σ{sup -2}Σ{sup -1},N = σ{sup 2}κ) are calculated and studied as functions of (T, V). A new approach, unifying in a clear and consistent way the definitions of cumulant ratios, is proposed.Anumerical FSS analysis of the obtained results has allowed us to locate accurately the finite-volume transition point. The extracted transition temperature value T{sub 0}(V) agrees with that expected T{sub 0}{sup N}(V) from the order parameter and the thermal susceptibility χ{sub T} (T, V), according to the standard procedure of localization to within about 2%. In addition to this, a very good correlation factor is obtained proving the validity of our cumulants method. The agreement of our results with those obtained by means of other models is remarkable. (orig.)

  13. Spatial layout optimization for ecological land based on minimum cumulative resistance model%基于最小累计阻力模型的生态用地空间布局优化

    Institute of Scientific and Technical Information of China (English)

    程迎轩; 王红梅; 刘光盛; 郑标; 王海云; 刘翠霞

    2016-01-01

    With the urban unlimited expansion, the ecological land excessive reclamation, and the resources and environment deteriorating, the conflict between cultivated land protection, ecological protection and increasing demand of construction land is increasingly intensified. Therefore, there is an urgent need to coordinate the contradiction between socio-economic development and ecological protection by analyzing the key ecological space, the potential for expansion and the policy constraints of farmland protection comprehensively. Coordinating the contradiction between social-economic development and ecological protection also has important significance for regional economy health and stable growth. In this paper, based on the landscape security pattern theory and GIS (geographic information system) technology, 4 critical security patterns including water security, biodiversity protection, disaster control, and landscape recreation were constructed by using the method of ecological space evaluation and landscape security pattern analysis. The method of “adjusted summation” was used to identify the ecological security patterns of the key ecological elements based on the census geographic conditions, land use data and statistical data. With the method of “adjusted summation”, the regional ecological security pattern expressed the agglomeration characteristics of multiple ecosystem services in space or time preferably. The resistance for ecological protection was assigned with a value according to the ecosystem service function and ecological value, the economic suitability of construction land and the policy of basic farmland protection. Taking the core ecological land as the protection sources, the minimum cumulative resistance model (MCRM) was used to calculate the minimum cumulative resistance value of ecological land. Ecological protection was graded to 4 zones using the method of natural breaks, namely ecological core zone, ecological control zone

  14. Structure functions and particle production in the cumulative region two different exponentials

    CERN Document Server

    Braun, M

    1996-01-01

    In the framework of the recently proposed QCD based parton model for the cumulative phenomena in the interactions with nuclei two mechanisms for particle production, direct and spectator ones, are analysed. It is shown that due to final state interactions the leading terms of the direct mechanism contribution are cancelled and the spectator mechanism is the dominant one. It leads to a smaller slope of the cumulative particle production rates compared to the slope of the nuclear structure function in the cumulative region x>1, in agreement with the recent experimental data.

  15. Avoiding Program-Induced Cumulative Overload (PICO).

    Science.gov (United States)

    Orr, Robin; Knapik, Joseph J; Pope, Rodney

    2016-01-01

    This article defines the concept of program-induced cumulative overload (PICO), provides examples, and advises ways to mitigate the adverse effects. PICO is the excessive cumulative physical workload that can be imparted to military personnel by a military training program with an embedded physical training component. PICO can be acute (accumulating within a single day) or chronic (accumulating across the entirety of the program) and results in adverse outcomes for affected personnel, including detrimental fatigue, performance degradation, injuries, or illness. Strategies to mitigate PICO include focusing administration and logistic practices during the development and ongoing management of a trainee program and implementing known musculoskeletal injury prevention strategies. More training is not always better, and trainers need to consider the total amount of physical activity that military personnel experience across both operational training and physical training if PICO is to be mitigated.

  16. Sharing a quota on cumulative carbon emissions

    Science.gov (United States)

    Raupach, Michael R.; Davis, Steven J.; Peters, Glen P.; Andrew, Robbie M.; Canadell, Josep G.; Ciais, Philippe; Friedlingstein, Pierre; Jotzo, Frank; van Vuuren, Detlef P.; Le Quéré, Corinne

    2014-10-01

    Any limit on future global warming is associated with a quota on cumulative global CO2 emissions. We translate this global carbon quota to regional and national scales, on a spectrum of sharing principles that extends from continuation of the present distribution of emissions to an equal per-capita distribution of cumulative emissions. A blend of these endpoints emerges as the most viable option. For a carbon quota consistent with a 2 °C warming limit (relative to pre-industrial levels), the necessary long-term mitigation rates are very challenging (typically over 5% per year), both because of strong limits on future emissions from the global carbon quota and also the likely short-term persistence in emissions growth in many regions.

  17. Cumulative carbon emissions and the Green Paradox

    OpenAIRE

    Ploeg, Frederick Van der

    2013-01-01

    The green paradox states that a gradually more ambitious climate policy such as a renewables subsidy or an anticipated carbon tax induces fossil fuel owners to extract more rapidly and accelerate global warming. However, if extraction becomes more costly as reserves are depleted, such policies also shorten the fossil fuel era, induce more fossil fuel to be left in the earth, and thus curb cumulative carbon emissions. These consequences are relevant, as global warming depends primarily on cumu...

  18. EPA Workshop on Epigenetics and Cumulative Risk ...

    Science.gov (United States)

    Agenda Download the Workshop Agenda (PDF) The workshop included presentations and discussions by scientific experts pertaining to three topics (i.e., epigenetic changes associated with diverse stressors, key science considerations in understanding epigenetic changes, and practical application of epigenetic tools to address cumulative risks from environmental stressors), to address several questions under each topic, and included an opportunity for attendees to participate in break-out groups, provide comments and ask questions. Workshop Goals The workshop seeks to examine the opportunity for use of aggregate epigenetic change as an indicator in cumulative risk assessment for populations exposed to multiple stressors that affect epigenetic status. Epigenetic changes are specific molecular changes around DNA that alter expression of genes. Epigenetic changes include DNA methylation, formation of histone adducts, and changes in micro RNAs. Research today indicates that epigenetic changes are involved in many chronic diseases (cancer, cardiovascular disease, obesity, diabetes, mental health disorders, and asthma). Research has also linked a wide range of stressors including pollution and social factors with occurrence of epigenetic alterations. Epigenetic changes have the potential to reflect impacts of risk factors across multiple stages of life. Only recently receiving attention is the nexus between the factors of cumulative exposure to environmental

  19. Cumulative dietary exposure of the population of Denmark to pesticides.

    Science.gov (United States)

    Jensen, Bodil Hamborg; Petersen, Annette; Nielsen, Elsa; Christensen, Tue; Poulsen, Mette Erecius; Andersen, Jens Hinge

    2015-09-01

    We used the Hazard Index (HI) method to carry out a cumulative risk assessment after chronic dietary exposure to all monitored pesticides in fruit, vegetables and cereals for various consumer groups in Denmark. Residue data for all the pesticides were obtained from the Danish monitoring programme during the period 2004-2011. Food consumption data were obtained from DANSDA (the DAnish National Survey of Diet and physical Activity) for the period 2005-2008. The calculations were made using three different models to cope with residues below the limit of reporting (LOR). We concluded that a model that included processing factors and set non-detects to ½ LOR, but limited the correction (Model 3), gave the most realistic exposure estimate. With Model 3 the HI was calculated to be 0.44 for children and 0.18 for adults, indicating that there is no risk of adverse health effects following chronic cumulative exposure to the pesticides found in fruit, vegetables and cereals on the Danish market. The HI was below 1 even for consumers who eat more than 550 g of fruit and vegetables per day, corresponding to 1/3 of the population. Choosing Danish-produced commodities whenever possible could reduce the HI by a factor of 2.

  20. Mapping cumulative noise from shipping to inform marine spatial planning.

    Science.gov (United States)

    Erbe, Christine; MacGillivray, Alexander; Williams, Rob

    2012-11-01

    Including ocean noise in marine spatial planning requires predictions of noise levels on large spatiotemporal scales. Based on a simple sound transmission model and ship track data (Automatic Identification System, AIS), cumulative underwater acoustic energy from shipping was mapped throughout 2008 in the west Canadian Exclusive Economic Zone, showing high noise levels in critical habitats for endangered resident killer whales, exceeding limits of "good conservation status" under the EU Marine Strategy Framework Directive. Error analysis proved that rough calculations of noise occurrence and propagation can form a basis for management processes, because spending resources on unnecessary detail is wasteful and delays remedial action.

  1. The Challenge of Developing Social Indicators for Cumulative Effects Assessment and Land Use Planning

    Directory of Open Access Journals (Sweden)

    John R. Parkins

    2011-06-01

    Full Text Available This paper provides a synopsis on social indicators as relevant to cumulative effects assessment and land use planning. Although much has been done to better understand the social dimensions of environmental assessment, empirical work has been lacking on social indicators that could be used either as measurable inputs or outputs for cumulative effects assessment and land use planning in different kinds of communities and regions. Cumulative effects models currently in practice often fail to address deeper issues of community and regional well-being. Against this gap, social scientists are being asked to make reliable generalizations about functional, measurable relationships between certain social indicators and land use change or scenarios. To address this challenge, the Alberta Research Council held a two-day workshop in 2005 with social scientists. The workshop resulted in a list of prioritized social indicators that could be included in cumulative effects modeling/assessments and land use planning. The top five social indicators included population growth rate, education attainment, self-assessed quality of life, equity, i.e., distribution of benefits, and locus of control. Although consensus on social indicators and social thresholds for cumulative effects models was not reached, the insight gained from the workshop will help inform future cumulative effects assessment and land use planning.

  2. a binary logit approach

    African Journals Online (AJOL)

    User

    2School of Economics, Faculty of Economics and Business, National University of Malaysia. (UKM). ABSTRACT: ... are an important ingredient to overall economic growth (Deininger, 2003). ..... insights for shaping an effective policy that will improve educational ... tional Bureau of Economic Research, New. York. Birdsall, N.

  3. Cumulative risks of foster care placement for Danish children

    National Research Council Canada - National Science Library

    Fallesen, Peter; Emanuel, Natalia; Wildeman, Christopher

    2014-01-01

    Although recent research suggests that the cumulative risk of foster care placement is far higher for American children than originally suspected, little is known about the cumulative risk of foster...

  4. Recursive Numerical Evaluation of the Cumulative Bivariate Normal Distribution

    CERN Document Server

    Meyer, Christian

    2010-01-01

    We propose an algorithm for evaluation of the cumulative bivariate normal distribution, building upon Marsaglia's ideas for evaluation of the cumulative univariate normal distribution. The algorithm is mathematically transparent, delivers competitive performance and can easily be extended to arbitrary precision.

  5. A Cumulant-based Analysis of Nonlinear Magnetospheric Dynamics

    Energy Technology Data Exchange (ETDEWEB)

    Jay R. Johnson; Simon Wing

    2004-01-28

    Understanding magnetospheric dynamics and predicting future behavior of the magnetosphere is of great practical interest because it could potentially help to avert catastrophic loss of power and communications. In order to build good predictive models it is necessary to understand the most critical nonlinear dependencies among observed plasma and electromagnetic field variables in the coupled solar wind/magnetosphere system. In this work, we apply a cumulant-based information dynamical measure to characterize the nonlinear dynamics underlying the time evolution of the Dst and Kp geomagnetic indices, given solar wind magnetic field and plasma input. We examine the underlying dynamics of the system, the temporal statistical dependencies, the degree of nonlinearity, and the rate of information loss. We find a significant solar cycle dependence in the underlying dynamics of the system with greater nonlinearity for solar minimum. The cumulant-based approach also has the advantage that it is reliable even in the case of small data sets and therefore it is possible to avoid the assumption of stationarity, which allows for a measure of predictability even when the underlying system dynamics may change character. Evaluations of several leading Kp prediction models indicate that their performances are sub-optimal during active times. We discuss possible improvements of these models based on this nonparametric approach.

  6. Long and Short Term Cumulative Structural Priming Effects

    OpenAIRE

    Kaschak, Michael P.; Kutta, Timothy J.; Coyle, Jacqueline M.

    2012-01-01

    We present six experiments that examine cumulative structural priming effects (i.e., structural priming effects that accumulate across many utterances). Of particular interest is whether (1) cumulative priming effects transfer across language production tasks and (2) the transfer of cumulative priming effects across tasks persists over the course of a week. Our data suggest that cumulative structural priming effects do transfer across language production tasks (e.g., from written stem complet...

  7. Preserved cumulative semantic interference despite amnesia

    Directory of Open Access Journals (Sweden)

    Gary Michael Oppenheim

    2015-05-01

    As predicted by Oppenheim et al’s (2010 implicit incremental learning account, WRP’s BCN RTs demonstrated strong (and significant repetition priming and semantic blocking effects (Figure 1. Similar to typical results from neurally intact undergraduates, WRP took longer to name pictures presented in semantically homogeneous blocks than in heterogeneous blocks, an effect that increased with each cycle. This result challenges accounts that ascribe cumulative semantic interference in this task to explicit memory mechanisms, instead suggesting that the effect has the sort of implicit learning bases that are typically spared in hippocampal amnesia.

  8. Cumulant matching for independent source extraction.

    Science.gov (United States)

    Phlypo, Ronald; Zarzoso, Vicente; Comon, Pierre; Lemahieu, Ignace

    2008-01-01

    In this work we show how one can make use of priors on signal statistics under the form of cumulant guesses to extract an independent source from an observed mixture. The advantage of using statistical priors on the signal lies in the fact that no specific knowledge is needed about its temporal behavior, neither about its spatial distribution. We show that these statistics can be obtained either by reasoning on the theoretical values of a supposed waveform, either by using a subset of the observations from which we know that their statistics are merely hindered by interferences. Results on an electro-cardiographic recording confirm the above assumptions.

  9. A Missing Link in the Evolution of the Cumulative Recorder

    Science.gov (United States)

    Asano, Toshio; Lattal, Kennon A.

    2012-01-01

    A recently recovered cumulative recorder provides a missing link in the evolution of the cumulative recorder from a modified kymograph to a reliably operating, scientifically and commercially successful instrument. The recorder, the only physical evidence of such an early precommercial cumulative recorder yet found, was sent to Keio University in…

  10. Original and cumulative prospect theory: a discussion of empirical differences

    NARCIS (Netherlands)

    P.P. Wakker; H. Fennema

    1997-01-01

    This note discusses differences between prospect theory and cumulative prospect theory. It shows that cumulative prospect theory is not merely a formal correction of some theoretical problems in prospect theory, but it also gives different predictions. Experiments are described that favor cumulative

  11. The Bubbles of China Stock Market Based on Return Decomposition and Cumulative Return

    Institute of Scientific and Technical Information of China (English)

    ZHANG Xiao-xia; WU Chong-feng

    2006-01-01

    Using Capital Asset Pricing Model Integrating both Firm and Market (CAPMIFM), we first decompose the asset return into two components. One is called the fundamental return,which is related to the intrinsic value of the asset. The other is called bubble return, which is derived from the asset bubbles. Then a stock bubble return model bused on cumulative return is proposed. The model exhibits characterizing log-periodic oscillations and a power law acceleration of the cumulative return. Empirical results suggest that the model has a good fit for the bubbles of China stock market.

  12. Cumulative Environmental Management Association : Wood Buffalo Region

    Energy Technology Data Exchange (ETDEWEB)

    Friesen, B. [Syncrude Canada Ltd., Edmonton, AB (Canada)

    2001-07-01

    The recently announced oil sands development of the Wood Buffalo Region in Alberta was the focus of this power point presentation. Both mining and in situ development is expected to total $26 billion and 2.6 million barrels per day of bitumen production. This paper described the economic, social and environmental challenges facing the resource development of this region. In addition to the proposed oil sands projects, this region will accommodate the needs of conventional oil and gas production, forestry, building of pipelines and power lines, municipal development, recreation, tourism, mining exploration and open cast mining. The Cumulative Environmental Management Association (CEMA) was inaugurated as a non-profit association in April 2000, and includes 41 members from all sectors. Its major role is to ensure a sustainable ecosystem and to avoid any cumulative impacts on wildlife. Other work underway includes the study of soil and plant species diversity, and the effects of air emissions on human health, wildlife and vegetation. The bioaccumulation of heavy metals and their impacts on surface water and fish is also under consideration to ensure the quality and quantity of surface water and ground water. 3 figs.

  13. Cumulative environmental management and the oil sands

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    2005-07-01

    In response to concerns regarding the cumulative environmental impacts of oil sands development within the Athabasca oil sands deposit, the government of Alberta established a Regional Sustainable Development Strategy (RSDS) to balance development with environmental protection. The environmental issues identified through the RSDS were addressed by the Cumulative Environmental Management Association (CEMA). CEMA's boundary is the Wood Buffalo region of northeastern Alberta. It identifies existing and future environmental effects in the region and proposes recommendations to regulatory bodies for reducing environmental impacts associated with oil sands development. This presentation outlined some of the 55 stakeholder representatives of CEMA, including Alberta government departments associated with resource development, oil sand developers within the region, and Aboriginal communities and First Nations. These stakeholders provide input on sector priorities and agree on environmental thresholds. Established working groups also address technical and scientific research issues identified in the RSDS such as sustainable ecosystems; surface waters; trace metals and air contaminants; nitrogen oxides and sulphur dioxides; and land reclamation. To date, CEMA has submitted more than 50 reports and has made 4 major environmental recommendations for trace metal management, ecosystem management tools, a framework for acid deposition management, and a landscape design checklist. tabs., figs.

  14. Higher Order Cumulants in Colorless Partonic Plasma

    CERN Document Server

    Cherif, S; Ladrem, M

    2016-01-01

    Any physical system considered to study the QCD deconfinement phase transition certainly has a finite volume, so the finite size effects are inevitably present. This renders the location of the phase transition and the determination of its order as an extremely difficult task, even in the simplest known cases. In order to identify and locate the colorless QCD deconfinement transition point in finite volume $T_{0}(V)$, a new approach based on the finite-size cumulant expansion of the order parameter and the $\\mathscr{L}_{m,n}$-Method is used.We have shown that both cumulants of higher order and their ratios, associated to the thermodynamical fluctuations of the order parameter, in QCD deconfinement phase transition behave in a particular enough way revealing pronounced oscillations in the transition region. The sign structure and the oscillatory behavior of these in the vicinity of the deconfinement phase transition point might be a sensitive probe and may allow one to elucidate their relation to the QCD phase...

  15. LOGIT and PROBIT Models in the Probability Analysis: Change in the Probability of Death from Celiac Disease Patients

    OpenAIRE

    Ondřej Šimpach

    2012-01-01

    It is estimated, that in the Czech Republic live about 40 000–50 000 people suffering from celiac disease, which is a disease of gluten intolerance. At the beginning of the independent Czech Republic, the life expectancy at birth of these people was quite low, because just in this period detailed diagnosis of this disease came fromabroad. With an increasing age the probability of death of these people grew faster than that of total population. The aim of this study is to analyse the probabili...

  16. FITTING OF NESTED LOGIT MODEL IN STATA SOFTWARE%嵌套logit模型在Stata软件中的拟合

    Institute of Scientific and Technical Information of China (English)

    王静; 叶冬青

    2007-01-01

    [目的]掌握嵌套logit模型的原理及其在Stata软件中的拟合过程. [方法]运用实例来介绍该模型的拟合过程. [结果]在Stata软件中的拟合过程中,需注意数据结构的正确性、构建模型中的各层次及解释变量、检验IIA假设.最后采用nlogit模块进行嵌套logit模型的拟合. [结论]嵌套logit模型可以解决反应变量的各个类别之间的相关性问题,正确分析因素对反应变量的影响效应.

  17. Fused lasso algorithm for Cox' proportional hazards and binomial logit models with application to copy number profiles

    NARCIS (Netherlands)

    Chaturvedi, N.; Menezes, R.X. de; Goeman, J.J.

    2014-01-01

    This paper presents an efficient algorithm based on the combination of Newton Raphson and Gradient Ascent, for using the fused lasso regression method to construct a genome-based classifier. The characteristic structure of copy number data suggests that feature selection should take genomic location

  18. Fused lasso algorithm for Cox' proportional hazards and binomial logit models with application to copy number profiles.

    Science.gov (United States)

    Chaturvedi, Nimisha; de Menezes, Renée X; Goeman, Jelle J

    2014-05-01

    This paper presents an efficient algorithm based on the combination of Newton Raphson and Gradient Ascent, for using the fused lasso regression method to construct a genome-based classifier. The characteristic structure of copy number data suggests that feature selection should take genomic location into account for producing more interpretable results for genome-based classifiers. The fused lasso penalty, an extension of the lasso penalty, encourages sparsity of the coefficients and their differences by penalizing the L1-norm for both of them at the same time, thus using genomic location. The major advantage of the algorithm over other existing fused lasso optimization techniques is its ability to predict binomial as well as survival response efficiently. We apply our algorithm to two publicly available datasets in order to predict survival and binary outcomes.

  19. The seven-year cumulative survival rate of Osstem implants

    Science.gov (United States)

    Kim, Young-Kyun; Kim, Bum-Su; Yun, Pil-Young; Mun, Sang-Un; Yi, Yang-Jin; Jeong, Kyung-In

    2014-01-01

    Objectives This study was performed to analyze the cumulative survival rate of Osstem implants (Osstem Implant Co., Ltd.) over a seven-year period. Materials and Methods A total of 105 patients who had 467 Osstem implants that were placed at the Section of Dentistry, Seoul National University Bundang Hospital (Seongnam, Korea) from June 2003 through December 2005 were analyzed. The life table method and a cross-tubulation analysis, log rank test were used to evaluate the survival curve and the influence that the prognostic factors. The prognostic factors, i.e., age and gender of patients, diameter and length, type of implants, bone graft history and loading time were determined with a Cox proportional hazard model based on logistic regression analysis. Results The seven-year cumulative survival rate of Osstem implants was 95.37%. The Cox proportional hazard model revealed that the following factors had a significant influence on survival rate; increased diameter, reduced prosthetic loading period and performance of bone grafting. Conclusion The osstem implants showed satisfactory results over the seven-year study period. PMID:24868503

  20. Analysis of the Factors Influencing Breeding Record Establishment of Sheep-raising Households or Farms Based on Logit-ISM:Based on 849 Questionnaires from 17 Cities in Shandong Province

    Institute of Scientific and Technical Information of China (English)

    Shiping; ZHU; Shimin; SUN; Limin; HAN

    2015-01-01

    Breeding record is an important way to implement standardized sheep raising,trace major sheep raising epidemic information and ensure the quality and safety of products for sheep-raising households or farms.Based on 849 questionnaires from 17 cities of Shandong Province,the paper firstly used the binary discrete model of Logit to analyze the factors influencing the establishing behavior of breeding records of sheep-raising households or farms and then used the ISM model to explain the relationship and hierarchy of each influencing factor.The result showed that seven factors including the education level of the deciders,farming scale,fixed number of farming years,degree of specialization,support of the government,whether to join the industrialization organization and the recognition of the breeding records have a significant impact on the establishing behavior of breeding records of the sheep-raising households or farms.Among them,the support of the government and the recognition of breeding records are the surface direct factors,degree of specialization and whether to join the industrialization organization are the middle indirect factors,the education level of the deciders,the farming scale and the fixed number of farming years are deep source factors.

  1. Ion cumulation by conical cathode electrolysis.

    CERN Document Server

    Grishin, V G

    2002-01-01

    Results of solid-state sodium stearate electrolysis with conical and cylindrical cathodes is presented here. Both electric measurement and conical samples destruction can be explained if a stress developing inside the conical sample is much bigger than in the cylindrical case and there is its unlimited amplification along cone slopes. OTHER KEYWORDS: ion, current, solid, symmetry, cumulation, polarization, depolarization, ionic conductor,superionic conductor, ice, crystal, strain, V-center, V-centre, doped crystal, interstitial impurity, intrinsic color center, high pressure technology, Bridgman, anvil, experiment, crowdion, dielectric, proton, layer, defect, lattice, dynamics, electromigration, mobility, muon catalysis, concentration, doping, dopant, conductivity, pycnonuclear reaction, permittivity, dielectric constant, point defects, interstitials, polarizability, imperfection, defect centers, glass, epitaxy, sodium hydroxide, metallic substrate, crystallization, point, tip, susceptibility, ferroelectric, ...

  2. [Cumulative trauma disorders: work or professional disease?].

    Science.gov (United States)

    de Carvalho, Marcus Vitor Diniz; Cavalcanti, Francisco Ivo Dantas; Soriano, Evelyne Pessoa; de Miranda, Hênio Ferreira

    2009-06-01

    This study aimed at reviewing the Brazilian legislation applied to occupational health. It refers to the diseases embodied in the Repetition Strain Injury (RSI) and Cumulative Trauma Disorders (CTD) regarded as work or professional diseases. This analysis allowed to perform the historical evolution of legislation concerning the issue, noting that the state of the art of regulation on RSI-CTD is anchored in specific regulation present in the Normative Instruction 98/2003, that establishes the diagnostic criteria and classification of RSI-CTD. It was concluded that according to the existing legislation in Brazil, the pathologies related to RSI-CTD are considered as work diseases and their legal effects are similar to the work-related accidents.

  3. Prefiltering and Cumulant Based Harmonic Retrieval in Mixed ARMA Noises

    Institute of Scientific and Technical Information of China (English)

    LIShenghong; LIJianhua; XUEZhi; CHENLiya

    2005-01-01

    Harmonic retrieval is an important issue in the the field of statistical signal processing. However, in the case of harmonic retrieval in mixed colored Gaussian and Non-Gaussian Autoregressive movingaverage (ARMA) noises, the corresponding existing approaches can not retrieve a harmonic signal either with quadratic phase coupling components, or with cubic phase coupling components, or when the colored non-Gaussian ARMA noise is symmetrically distributed. In this paper, a new general approach is proposed to retrieve a one-dimensional real harmonic signal in the above mixed ARMA noises. A suitable filter is first used to remove all the sharp power spectrum peaks of the noisy observed process, then some kind of fourth-order cumulant is employed to identify the Autoregressive (AR) parameter values of the colored non-Gaussian ARMA noise model. After the real noisy observed data are filtered with the identified AR parameter values again, cumulant based methods can be made use of to retrieve the harmonics. The proposed new approach can be applied to retrieve a one-dimensional real harmonic signal in the above mixed colored Gaussian and non-Gaussian ARMA noises with no restrictions on the phase coupling of the harmonics and the distribution of the colored non-Gaussian ARMA noise. Simulation examples are presented to demonstrate its effectiveness.

  4. Cumulative Laws,Team Assembling Mechanisms Determining Network Structure

    Institute of Scientific and Technical Information of China (English)

    WU Bin; LIU Qi; YE Qi

    2008-01-01

    A number of researching works have shed light on the field of complex networks recently.We investigate a wide range of real-world networks and find several interesting phenomena.Firstly,almost all of these networks evolve by overlapping new small graphs on former networks.Secondly,not only the degree sequence of the mature network follows a power-law distribution,but also the distribution of the cumulative occurrence times during the growing process are revealed to have a heavy tail.Existing network evolving models do not provide interpretation to these phenomena.We suggest a model based on the team assembling mechanism,which is extracted from the growing processes of real-world networks and requires simple parameters,and produces networks exhibiting these properties observed in the present study and in previous works.

  5. EXPERIMENTAL VALIDATION OF CUMULATIVE SURFACE LOCATION ERROR FOR TURNING PROCESSES

    Directory of Open Access Journals (Sweden)

    Adam K. Kiss

    2016-02-01

    Full Text Available The aim of this study is to create a mechanical model which is suitable to investigate the surface quality in turning processes, based on the Cumulative Surface Location Error (CSLE, which describes the series of the consecutive Surface Location Errors (SLE in roughing operations. In the established model, the investigated CSLE depends on the currently and the previously resulted SLE by means of the variation of the width of cut. The phenomenon of the system can be described as an implicit discrete map. The stationary Surface Location Error and its bifurcations were analysed and flip-type bifurcation was observed for CSLE. Experimental verification of the theoretical results was carried out.

  6. Cumulative protons in 12C fragmentation at intermediate energy

    Directory of Open Access Journals (Sweden)

    Abramov B.M.

    2014-03-01

    Full Text Available In the FRAGM experiment at heavy ion accelerator complex TWAC-ITEP, the proton yields at an angle 3.5° have been measured in fragmentation of carbon ions at T0 = 0.3, 0.6, 0.95 and 2.0 GeV/nucleon on beryllium target. The data are presented as invariant proton yields on cumulative variable x in the range 0.9 < x < 2.4. Proton spectra cover six orders of invariant cross section magnitude. They have been analyzed in the framework of quark cluster fragmentation model. Fragmentation functions of quarkgluon string model are used. The probabilities of the existence of multi-quark clusters in carbon nuclei are estimated to be 8–12% for six-quark clusters and 0.2–0.6% for ninequark clusters.

  7. "Logits and Tigers and Bears, Oh My! A Brief Look at the Simple Math of Logistic Regression and How It Can Improve Dissemination of Results"

    Directory of Open Access Journals (Sweden)

    Jason W. Osborne

    2012-06-01

    Full Text Available Logistic regression is slowly gaining acceptance in the social sciences, and fills an important niche in the researcher's toolkit: being able to predict important outcomes that are not continuous in nature. While OLS regression is a valuable tool, it cannot routinely be used to predict outcomes that are binary or categorical in nature. These outcomes represent important social science lines of research: retention in, or dropout from school, using illicit drugs, underage alcohol consumption, antisocial behavior, purchasing decisions, voting patterns, risky behavior, and so on. The goal of this paper is to briefly lead the reader through the surprisingly simple mathematics that underpins logistic regression: probabilities, odds, odds ratios, and logits. Anyone with spreadsheet software or a scientific calculator can follow along, and in turn, this knowledge can be used to make much more interesting, clear, and accurate presentations of results (especially to non-technical audiences. In particular, I will share an example of an interaction in logistic regression, how it was originally graphed, and how the graph was made substantially more user-friendly by converting the original metric (logits to a more readily interpretable metric (probability through three simple steps.

  8. Probabilistic cumulative risk assessment of anti-androgenic pesticides in food

    DEFF Research Database (Denmark)

    Müller, Anne Kirstine; Nielsen, Elsa

    2008-01-01

    A cumulative risk assessment of three anti-androgenic pesticides vinclozolin, procymidone and prochloraz in combination has been carried out using an Integrated Probabilistic Risk Assessment (IPRA) model. In the model, variability in both exposure and sensitivity between individuals were combined...

  9. Learning curve of vitrification assessed by cumulative summation test for learning curve (LC-CUSUM).

    Science.gov (United States)

    Dessolle, Lionel; Biau, David J; de Larouzière, Vanina; Ravel, Célia; Antoine, Jean-Marie; Daraï, Emile; Mandelbaum, Jacqueline

    2009-09-01

    We used the cumulative summation test for learning curve (LC-CUSUM), a specifically designed statistical tool, to evaluate the first 50 procedures performed by a trainee in vitrification and to provide a usable model for monitoring the learning process of this technique. Given the lack of models to evaluate IVF technologies, the CUSUM methodology could prove useful for quality control in laboratories.

  10. Description of quasiparticle and satellite properties via cumulant expansions of the retarded one-particle Green's function

    Science.gov (United States)

    Mayers, Matthew Z.; Hybertsen, Mark S.; Reichman, David R.

    2016-08-01

    A cumulant-based G W approximation for the retarded one-particle Green's function is proposed, motivated by an exact relation between the improper Dyson self-energy and the cumulant generating function. Qualitative aspects of this method are explored within a simple one-electron independent phonon model, where it is seen that the method preserves the energy moment of the spectral weight while also reproducing the exact Green's function in the weak-coupling limit. For the three-dimensional electron gas, this method predicts multiple satellites at the bottom of the band, albeit with inaccurate peak spacing. However, its quasiparticle properties and correlation energies are more accurate than both previous cumulant methods and standard G0W0 . Our results point to features that may be exploited within the framework of cumulant-based methods and suggest promising directions for future exploration and improvements of cumulant-based G W approaches.

  11. Universal Off-Equilibrium Scaling of Critical Cumulants in the QCD Phase Diagram

    Science.gov (United States)

    Mukherjee, Swagato; Venugopalan, Raju; Yin, Yi

    2016-11-01

    Exploiting the universality between the QCD critical point and the three-dimensional Ising model, closed form expressions derived for nonequilibrium critical cumulants on the crossover side of the critical point reveal that they can differ in both magnitude and sign from equilibrium expectations. We demonstrate here that key elements of the Kibble-Zurek framework of nonequilibrium phase transitions can be employed to describe the dynamics of these critical cumulants. Our results suggest that observables sensitive to critical dynamics in heavy-ion collisions should be expressible as universal scaling functions, thereby providing powerful model-independent guidance in searches for the QCD critical point.

  12. Long and Short Term Cumulative Structural Priming Effects.

    Science.gov (United States)

    Kaschak, Michael P; Kutta, Timothy J; Coyle, Jacqueline M

    We present six experiments that examine cumulative structural priming effects (i.e., structural priming effects that accumulate across many utterances). Of particular interest is whether (1) cumulative priming effects transfer across language production tasks and (2) the transfer of cumulative priming effects across tasks persists over the course of a week. Our data suggest that cumulative structural priming effects do transfer across language production tasks (e.g., from written stem completion to picture description, and from picture description to written stem completion), but only when both tasks are presented in the same experimental session. When cumulative priming effects are established in one task, and the second (changed) task is not presented until a week later, the cumulative priming effects are not observed.

  13. Why Veterinary Medical Educators Should Embrace Cumulative Final Exams.

    Science.gov (United States)

    Royal, Kenneth D

    2017-01-03

    The topic of cumulative final examinations often elicits polarizing opinions from veterinary medical educators. While some faculty prefer cumulative finals, there are many who perceive these types of examinations as problematic. Specifically, faculty often cite cumulative examinations are more likely to cause students' greater stress, which may in turn result in negative student evaluations of teaching. Cumulative finals also restrict the number of items one may present to students on most recent material. While these cited disadvantages may have some merit, the advantages of cumulative examinations far exceed the disadvantages. The purpose of this article is to discuss the advantages of cumulative examinations with respect to learning evidence, grade/score validity, fairness issues, and implications for academic policy.

  14. Investigating the effect among size, growth opportunity and cumulative abnormal returns of the companies

    Directory of Open Access Journals (Sweden)

    Khalil bevali behbahani

    2016-09-01

    Full Text Available The stockholders and investors require identifying main variables that explain stock return. Being aware of variables and achieving an appropriate model can lead to improve their investment and considering that each wise and economic person’s goal is obtain high and more returns, the current research is sought to investigate the effect of company’s characteristics and the ratio of investment on company’s cumulative abnormal returns. Statistical sample which has been used in current research includes 256 listed companies in Tehran Stock Exchange during 2002 to 2013. Dependent variable of current research is cumulative abnormal return. The independent variables whose effects are investigated on cumulative abnormal return include company’s size, growth opportunity. The data are collected and were inserted in Excel file as information database. Testing hypotheses also has been done from multi-variable regression models based on combined data technique using econometric software Eviews. The findings of the research show that there is a positive and significant relationship between company’s size and company’s cumulative abnormal return. There is also a negative and significant relationship between growth opportunities and company’s cumulative abnormal return.

  15. Analysis of experimental data on correlations between cumulative particles

    Energy Technology Data Exchange (ETDEWEB)

    Vlasov, A.V.; Doroshkevich, E.A.; Leksin, G.A. [Institute of Theoretical and Experimental Physics, Moscow (Russian Federation)] [and others

    1995-04-01

    Experimental data on correlations between cumulative particles are analyzed. A space-time and energy-transfer pattern of hadron-nucleus interaction based on both correlation data and data on the inclusive spectra of cumulative particles is considered. A new variable that is convenient for describing the production of cumulative particles is proposed using the concept of symmetry between the one-particle and multiparticle distributions. 32 refs., 9 figs., 1 tab.

  16. Quasi-gaussian fixed points and factorial cumulants in nuclear multifragmentation

    CERN Document Server

    Lacroix, D

    1996-01-01

    We re-analyze the conditions for the phenomenon of intermittency (self-similar fluctuations) to occur in models of multifragmentation. Analyzing two different mechanisms, the bond-percolation and the ERW (Elattari, Richert and Wagner) statistical fragmentation models, we point out a common quasi-gaussian shape of the total multiplicity distribution in the critical range. The fixed-point property is also observed for the multiplicity of the second bin. Fluctuations are studied using scaled factorial cumulants instead of scaled factorial moments. The second-order cumulant displays the intermittency signal while higher order cumulants are equal to zero, revealing a large information redundancy in scaled factorial moments. A practical criterion is proposed to identify the gaussian feature of light-fragment production, distinguishing between a self-similarity mechanism (ERW) and the superposition of independent sources (percolation).

  17. Estimating health state utility values from discrete choice experiments--a QALY space model approach.

    Science.gov (United States)

    Gu, Yuanyuan; Norman, Richard; Viney, Rosalie

    2014-09-01

    Using discrete choice experiments (DCEs) to estimate health state utility values has become an important alternative to the conventional methods of Time Trade-Off and Standard Gamble. Studies using DCEs have typically used the conditional logit to estimate the underlying utility function. The conditional logit is known for several limitations. In this paper, we propose two types of models based on the mixed logit: one using preference space and the other using quality-adjusted life year (QALY) space, a concept adapted from the willingness-to-pay literature. These methods are applied to a dataset collected using the EQ-5D. The results showcase the advantages of using QALY space and demonstrate that the preferred QALY space model provides lower estimates of the utility values than the conditional logit, with the divergence increasing with worsening health states. Copyright © 2014 John Wiley & Sons, Ltd.

  18. Analysis of Memory Codes and Cumulative Rehearsal in Observational Learning

    Science.gov (United States)

    Bandura, Albert; And Others

    1974-01-01

    The present study examined the influence of memory codes varying in meaningfulness and retrievability and cumulative rehearsal on retention of observationally learned responses over increasing temporal intervals. (Editor)

  19. Continuously Cumulating Meta-Analysis and Replicability.

    Science.gov (United States)

    Braver, Sanford L; Thoemmes, Felix J; Rosenthal, Robert

    2014-05-01

    The current crisis in scientific psychology about whether our findings are irreproducible was presaged years ago by Tversky and Kahneman (1971), who noted that even sophisticated researchers believe in the fallacious Law of Small Numbers-erroneous intuitions about how imprecisely sample data reflect population phenomena. Combined with the low power of most current work, this often leads to the use of misleading criteria about whether an effect has replicated. Rosenthal (1990) suggested more appropriate criteria, here labeled the continuously cumulating meta-analytic (CCMA) approach. For example, a CCMA analysis on a replication attempt that does not reach significance might nonetheless provide more, not less, evidence that the effect is real. Alternatively, measures of heterogeneity might show that two studies that differ in whether they are significant might have only trivially different effect sizes. We present a nontechnical introduction to the CCMA framework (referencing relevant software), and then explain how it can be used to address aspects of replicability or more generally to assess quantitative evidence from numerous studies. We then present some examples and simulation results using the CCMA approach that show how the combination of evidence can yield improved results over the consideration of single studies.

  20. Effects of Surface Emitting and Cumulative Collisions on Elliptic Flow

    Institute of Scientific and Technical Information of China (English)

    LIU Jian-Li; WU Feng-Juan; ZHANG Jing-Bo; TANG Gui-Xin; HUO Lei

    2008-01-01

    @@ The integral and differential elliptic flow of partons is calculated using the multiphase transport model for Au+Au collisions at centre-of-mass energy √SNN=200 GeV.It is shown that elliptic flow of partons freezing out at early time,which is affected mainly by surface emittance,decreases with time and elliptic flow of partons freezing out at late time,which is dominated by cumulative collisions,increases with time.The elliptic flow of partons freezing out early has a large contribution to the flatting of curve of final differential elliptic flow at large transverse momentum.It is argued that the effect of surface emittance is not neglectable.

  1. The cumulative effect of risk compensation on infection preventive measures.

    Science.gov (United States)

    Maxin, Daniel; Sega, Laurentiu; Eaton, Lisa

    2016-12-01

    We study several epidemic models (with and without gender structure) that incorporate risk compensation behavior in response to a lower chance of acquiring the infection as a result of preventive measures that are only partially effective. We show that the cumulative risk compensation that occurs between a high risk susceptible and infectious individual may play an important role in whether the implementation of these measures is successful in lowering the epidemic reproductive number. In addition, we show that certain levels of risk compensation may cancel the benefit of the low infection risk practiced by diagnosed infectious individuals when the goal is a reduction of the epidemic reproductive number. Copyright © 2016 Elsevier Inc. All rights reserved.

  2. Cumulative Stress and Cortisol Disruption among Black and Hispanic Pregnant Women in an Urban Cohort

    Science.gov (United States)

    Suglia, Shakira Franco; Staudenmayer, John; Cohen, Sheldon; Enlow, Michelle Bosquet; Rich-Edwards, Janet W.; Wright, Rosalind J.

    2010-01-01

    While adult hypothalamic-pituitary-adrenocortical (HPA) axis functioning is thought to be altered by traumatic experiences, little data exist on the effects of cumulative stress on HPA functioning among pregnant women or among specific racial and ethnic groups. Individuals may be increasingly vulnerable to physiological alterations when experiencing cumulative effects of multiple stressors. These effects may be particularly relevant in urban poor communities where exposure to multiple stressors is more prevalent. The goal of this study was to explore the effects of multiple social stressors on HPA axis functioning in a sample of urban Black (n = 68) and Hispanic (n = 132) pregnant women enrolled in the Asthma Coalition on Community, Environment, and Social Stress (ACCESS). Pregnant women were administered the Revised Conflict Tactics Scale (R-CTS) survey to assess interpersonal violence, the Experiences of Discrimination (EOD) survey, the Crisis in Family Systems-Revised (CRISYS-R) negative life events survey, and the My Exposure to Violence (ETV) survey, which ascertains exposure to community violence. A cumulative stress measure was derived from these instruments. Salivary cortisol samples were collected five times per day over three days to assess area under the curve (AUC), morning change, and basal awakening response in order to characterize diurnal salivary cortisol patterns. Repeated measures mixed models, stratified by race/ethnicity, were performed adjusting for education level, age, smoking status, body mass index and weeks pregnant at time of cortisol sampling. The majority of Hispanic participants (57%) had low cumulative stress exposure, while the majority of Black participants had intermediate (35%) or high (41%) cumulative stress exposure. Results showed that among Black but not Hispanic women, cumulative stress was associated with lower morning cortisol levels, including a flatter waking to bedtime rhythm. These analyses suggest that the combined

  3. Cumulative Stress and Cortisol Disruption among Black and Hispanic Pregnant Women in an Urban Cohort.

    Science.gov (United States)

    Suglia, Shakira Franco; Staudenmayer, John; Cohen, Sheldon; Enlow, Michelle Bosquet; Rich-Edwards, Janet W; Wright, Rosalind J

    2010-12-01

    While adult hypothalamic-pituitary-adrenocortical (HPA) axis functioning is thought to be altered by traumatic experiences, little data exist on the effects of cumulative stress on HPA functioning among pregnant women or among specific racial and ethnic groups. Individuals may be increasingly vulnerable to physiological alterations when experiencing cumulative effects of multiple stressors. These effects may be particularly relevant in urban poor communities where exposure to multiple stressors is more prevalent. The goal of this study was to explore the effects of multiple social stressors on HPA axis functioning in a sample of urban Black (n = 68) and Hispanic (n = 132) pregnant women enrolled in the Asthma Coalition on Community, Environment, and Social Stress (ACCESS). Pregnant women were administered the Revised Conflict Tactics Scale (R-CTS) survey to assess interpersonal violence, the Experiences of Discrimination (EOD) survey, the Crisis in Family Systems-Revised (CRISYS-R) negative life events survey, and the My Exposure to Violence (ETV) survey, which ascertains exposure to community violence. A cumulative stress measure was derived from these instruments. Salivary cortisol samples were collected five times per day over three days to assess area under the curve (AUC), morning change, and basal awakening response in order to characterize diurnal salivary cortisol patterns. Repeated measures mixed models, stratified by race/ethnicity, were performed adjusting for education level, age, smoking status, body mass index and weeks pregnant at time of cortisol sampling. The majority of Hispanic participants (57%) had low cumulative stress exposure, while the majority of Black participants had intermediate (35%) or high (41%) cumulative stress exposure. Results showed that among Black but not Hispanic women, cumulative stress was associated with lower morning cortisol levels, including a flatter waking to bedtime rhythm. These analyses suggest that the combined

  4. County-level cumulative environmental quality associated with cancer incidence.

    Science.gov (United States)

    Jagai, Jyotsna S; Messer, Lynne C; Rappazzo, Kristen M; Gray, Christine L; Grabich, Shannon C; Lobdell, Danelle T

    2017-08-01

    Individual environmental exposures are associated with cancer development; however, environmental exposures occur simultaneously. The Environmental Quality Index (EQI) is a county-level measure of cumulative environmental exposures that occur in 5 domains. The EQI was linked to county-level annual age-adjusted cancer incidence rates from the Surveillance, Epidemiology, and End Results (SEER) Program state cancer profiles. All-site cancer and the top 3 site-specific cancers for male and female subjects were considered. Incident rate differences (IRDs; annual rate difference per 100,000 persons) and 95% confidence intervals (CIs) were estimated using fixed-slope, random intercept multilevel linear regression models. Associations were assessed with domain-specific indices and analyses were stratified by rural/urban status. Comparing the highest quintile/poorest environmental quality with the lowest quintile/best environmental quality for overall EQI, all-site county-level cancer incidence rate was positively associated with poor environmental quality overall (IRD, 38.55; 95% CI, 29.57-47.53) and for male (IRD, 32.60; 95% CI, 16.28-48.91) and female (IRD, 30.34; 95% CI, 20.47-40.21) subjects, indicating a potential increase in cancer incidence with decreasing environmental quality. Rural/urban stratified models demonstrated positive associations comparing the highest with the lowest quintiles for all strata, except the thinly populated/rural stratum and in the metropolitan/urbanized stratum. Prostate and breast cancer demonstrated the strongest positive associations with poor environmental quality. We observed strong positive associations between the EQI and all-site cancer incidence rates, and associations differed by rural/urban status and environmental domain. Research focusing on single environmental exposures in cancer development may not address the broader environmental context in which cancers develop, and future research should address cumulative environmental

  5. Cumulative social disadvantage and child health.

    Science.gov (United States)

    Bauman, Laurie J; Silver, Ellen J; Stein, Ruth E K

    2006-04-01

    Disparities in child health are a major public health concern. However, it is unclear whether these are predominantly the result of low income, race, or other social risk factors that may contribute to their health disadvantage. Although others have examined the effects of the accumulation of risk factors, this methodology has not been applied to child health. We tested 4 social risk factors (poverty, minority race/ethnicity, low parental education, and not living with both biological parents) to assess whether they have cumulative effects on child health and examined whether access to health care reduced health disparities. We analyzed data on 57,553 children low parental education, and single-parent household) were consistently associated with child health. These were summed, generating the Social Disadvantage Index (range: 0-3). A total of 43.6% of children had no social disadvantages, 30.8% had 1, 15.6% had 2, and 10.0% had all 3. Compared with those with no social disadvantages, the odds ratios (ORs) of being in "good, fair, or poor health" (versus "excellent or very good") were 1.95 for 1 risk, 3.22 for 2 risks, and 4.06 for 3 risks. ORs of having a chronic condition increased from 1.25 (1 risk) to 1.60 (2 risks) to 2.11 (3 risks). ORs for activity limitation were 1.51 (1 risk) to 2.14 (2 risks) and 2.88 (3 risks). Controlling for health insurance did not affect these findings. The accumulation of social disadvantage among children was strongly associated with poorer child health and having insurance did not reduce the observed health disparities.

  6. Behavior and finite-size effects of the sixth order cumulant in the three-dimensional Ising universality class

    Science.gov (United States)

    Pan, Xue; Chen, Li-Zhu; Wu, Yuan-Fang

    2016-09-01

    The high-order cumulants of conserved charges are suggested to be sensitive observables to search for the critical point of Quantum Chromodynamics (QCD). This has been calculated to the sixth order in experiments. Corresponding theoretical studies on the sixth order cumulant are necessary. Based on the universality of the critical behavior, we study the temperature dependence of the sixth order cumulant of the order parameter using the parametric representation of the three-dimensional Ising model, which is expected to be in the same universality class as QCD. The density plot of the sign of the sixth order cumulant is shown on the temperature and external magnetic field plane. We found that at non-zero external magnetic field, when the critical point is approached from the crossover side, the sixth order cumulant has a negative valley. The width of the negative valley narrows with decreasing external field. Qualitatively, the trend is similar to the result of Monte Carlo simulation on a finite-size system. Quantitatively, the temperature of the sign change is different. Through Monte Carlo simulation of the Ising model, we calculated the sixth order cumulant of different sizes of systems. We discuss the finite-size effects on the temperature at which the cumulant changes sign. Supported by Fund Project of Sichuan Provincial Department of Education (16ZB0339), Fund Project of Chengdu Technological University for Doctor (2016RC004), Major State Basic Research Development Program of China (2014CB845402) and National Natural Science Foundation of China (11405088, 11221504)

  7. Sensitivity Tests for Cumulative Damage Function (CDF) for the PGSFR

    Energy Technology Data Exchange (ETDEWEB)

    Choi, Chiwoong; Ha, Kwiseok [Korea Atomic Energy Research Institute, Daejeon (Korea, Republic of)

    2014-10-15

    A safety analysis including the design basis and beyond design basis events has been conducted using MARS-LMR. Previous safety limits were based on temperature and the duration time. However, the cumulative damage function (CDF) will be used as the safety limit to evaluate the fuel cladding integrity. Recently, a 4S reactor developed by Toshiba used the same approach for a safety analysis. Therefore, the development a CDF is necessary to evaluate the safety limit for the PGSFR safety analyses. The major keys in the CDF model are behavior of fuel and cladding. It is not easy to obtain a metallic fuel database for a CDF model including the cladding materials. Argonne National Laboratory (ANL) in the United States is the only major leading group for metallic fuel experiments. They conducted various experiments with various facilities and experimental reactors, for example, EBR-II, FFTF, and TREAT. In addition, they have recently been trying to extend their oxide fuel based a severe accident code, SAS4A/SASSYS, to a metallic fuel version using their metallic fuel database. In this study, the preliminary CDF model was supplemented in the MARS-LMR code. The major source was the SAS4A/SASSYS modules related to fuel and cladding transient behaviors.. In addition, a sensitivity test for some parameters in the CDF model was conducted to evaluate the capability of these models and to find the major parameter of fuel failure. The Cumulative Damage Function is a good indicator for a fuel failure. The major parameters for the CDF model are selected including cladding and fuel temperatures, initial pressure and volume in the gas plenum, clad thickness, and fission power in the fuel pin. The most sensitive parameter is the cladding temperature. Also, cladding thickness and gas pressure in the fuel pin are effective parameters on the CDF. During an actual transient, various parameter including sensitivity test parameters in this study will be changed simultaneously. This study can

  8. A Passenger Travel Demand Model for Copenhagen

    DEFF Research Database (Denmark)

    Overgård, Christian Hansen; Jovicic, Goran

    2003-01-01

    The passenger travel model for Copenhagen is a state-of-practice nested logit model in which the sub-models - i.e. generation, distribution and mode choice models - are connected via measure of accessibility. The model includes in its structure a large set of explanatory variables at all three...

  9. A Framework for Treating Cumulative Trauma with Art Therapy

    Science.gov (United States)

    Naff, Kristina

    2014-01-01

    Cumulative trauma is relatively undocumented in art therapy practice, although there is growing evidence that art therapy provides distinct benefits for resolving various traumas. This qualitative study proposes an art therapy treatment framework for cumulative trauma derived from semi-structured interviews with three art therapists and artistic…

  10. Cumulative Effects of Human Activities on Marine Mammal Populations

    Science.gov (United States)

    2015-09-30

    1 DISTRIBUTION STATEMENT A. Approved for public release; distribution is unlimited. Cumulative Effects of Human Activities on Marine Mammal ...marine mammals . OBJECTIVES The National Academies of Sciences, Engineering, and Medicine has convened a volunteer committee that will...Review the present scientific understanding of cumulative effects of anthropogenic stressors on marine mammals with a focus on anthropogenic sound

  11. A Framework for Treating Cumulative Trauma with Art Therapy

    Science.gov (United States)

    Naff, Kristina

    2014-01-01

    Cumulative trauma is relatively undocumented in art therapy practice, although there is growing evidence that art therapy provides distinct benefits for resolving various traumas. This qualitative study proposes an art therapy treatment framework for cumulative trauma derived from semi-structured interviews with three art therapists and artistic…

  12. Cumulative Estrogen Exposure and Prospective Memory in Older Women

    Science.gov (United States)

    Hesson, Jacqueline

    2012-01-01

    This study looked at cumulative lifetime estrogen exposure, as estimated with a mathematical index (Index of Cumulative Estrogen Exposure (ICEE)) that included variables (length of time on estrogen therapy, age at menarche and menopause, postmenopausal body mass index, time since menopause, nulliparity and duration of breastfeeding) known to…

  13. Determinantes de la búsqueda de empleo desde la ocupación: una estimación Logit Multinomial

    Directory of Open Access Journals (Sweden)

    Rogelio Varela Llamas

    2015-01-01

    Full Text Available En el presente documento se analiza el efecto que tienen un conjunto de atributos personales y características de la ocupación del trabajador en la búsqueda de empleo. Se estima un modelo logit multinomial para el primer trimestre del año 2009 y 2012, ambos periodos corresponden a un periodo de crisis y recuperación económica respectivamente. Se utilizan datos de la Encuesta Nacional de Ocupación y Empleo ( ENOE . Los resultados indican que la variable sexo, edad, nivel de escolaridad, sector económico e ingresos, explican los motivos de búsqueda en forma significativa.

  14. Estimation of cumulative exposures to naphtha at an automobile fuel-injector manufacturing plant.

    Science.gov (United States)

    Rocskay, A Z; Robins, T G; Echeverria, D; Schork, M A; Seixas, N S; White, R F; Proctor, S P

    1993-09-01

    As part of an epidemiologic study of neuropsychological and renal effects of occupational exposure to organic solvents, estimates of cumulative exposure to naphtha were derived for workers at an automobile fuel-injector manufacturing plant. The approach to exposure estimation was relatively unusual in three respects: (1) a marked association between indoor naphtha air concentration and outdoor temperature was modeled and applied to detailed historical temperature data to calculate cumulative exposure estimates; (2) the large number of investigator-generated air samples allowed the use of analyses of variance to compare alternative job-grouping schemes; and (3) the young age of the plant and few process changes allowed for historical exposure estimates with a high degree of confidence. The derived estimates of cumulative exposure appear to offer a firm basis for epidemiologic analyses of exposure-health outcome relationships.

  15. Effects of multiple context and cumulative stress on urban children's adjustment in elementary school.

    Science.gov (United States)

    Morales, Julie R; Guerra, Nancy G

    2006-01-01

    Using longitudinal data collected over 2 years on a sample of 2,745 urban elementary school children (1st-6th graders, ages 6-11 years) from economically disadvantaged communities, effects of stressful experiences within 3 contexts (school, family, neighborhood), cumulative stress, and multiple context stress on 3 indices of children's adjustment (achievement, depression, and aggression) were examined. All 3 stressor contexts were related contemporaneously and longitudinally to negative outcomes across adjustment measures, with differential paths in each predictive model. Cumulative stress was linearly related to increases in adjustment problems but multiple context stress was not related to problematic adjustment beyond effects of cumulative stress alone. The important influence of life events stress on children's adjustment in disadvantaged communities is discussed.

  16. A new family of cumulative indexes for measuring scientific performance.

    Directory of Open Access Journals (Sweden)

    Marcin Kozak

    Full Text Available In this paper we propose a new family of cumulative indexes for measuring scientific performance which can be applied to many metrics, including h index and its variants (here we apply it to the h index, h(2 index and Google Scholar's i10 index. These indexes follow the general principle of repeating the index calculation for the same publication set. Using bibliometric data and reviewer scores for accepted and rejected fellowship applicants we examine how valid the cumulative variant is compared to the original variant. These analyses showed that the cumulative indexes result in higher correlations with the reviewer scores than their original variants. Thus, the cumulative indexes better reflect the assessments by peers than the original variants and are useful extensions of the original indexes. In contrast to many other measures of scientific performance proposed up to now, the cumulative indexes seem not only to be effective, but they are also easy to understand and calculate.

  17. Probabilistic cumulative risk assessment of anti-androgenic pesticides in food.

    NARCIS (Netherlands)

    Müller, A.K.; Bosgra, S.; Boon, P.E.; van der Voet, H.; Nielsen, E.; Ladefoged, O.

    2009-01-01

    In this paper, we present a cumulative risk assessment of three anti-androgenic pesticides (vinclozolin, procymidone and prochloraz) using the relative potency factor (RPF) approach and an integrated probabilistic risk assessment (IPRA) model. RPFs for each substance were estimated for three reprodu

  18. Probabilistic cumulative risk assessment of anti-androgenic pesticides in food

    NARCIS (Netherlands)

    Muller, A.K.; Bosgra, S.; Boon, P.E.; Voet, van der H.; Nielsen, E.; Ladefoged, O.

    2009-01-01

    In this paper, we present a cumulative risk assessment of three anti-androgenic pesticides (vinclozolin, procymidone and prochloraz) using the relative potency factor (RPF) approach and an integrated probabilistic risk assessment (IPRA) model. RPFs for each substance were estimated for three reprodu

  19. Scenario dependency of the transient climate response to cumulative emissions

    Science.gov (United States)

    Turner, Katherine; Williams, Ric; Oschlies, Andreas

    2017-04-01

    The transient climate response to emissions (TCRE), in relating surface temperature changes to cumulative carbon emissions, provides a means of estimating carbon budgets from global warming benchmarks. Current Earth System Model results indicate that the TCRE is linear and scenario-independent. We explore the sensitivity of the TCRE to scenario and model parameter uncertainties using 8 configurations of the UVic Earth System Model of Intermediate Complexity, forced by 2 twenty-first-century emissions scenarios (RCP 4.5 and 8.5). We find that the TCRE is higher under RCP 4.5 than 8.5 by 0.3-0.8 K/1000 Pg C and shows opposing nonlinear tendencies in these scenarios: an increase of 0.15-0.5 K/1000 Pg C over RCP 4.5 and a decrease of 0-0.7 K/1000 Pg C over RCP 8.5. These differences are robust across model configurations with perturbed land and ocean parametrizations and are the result of the decreased efficiency of heat transport into the deep ocean under decelerating emissions.

  20. Longhi Games, Internal Reservoirs, and Cumulate Porosity

    Science.gov (United States)

    Morse, S. A.

    2009-05-01

    Fe in plagioclase at an early age, T-rollers (or not) on the Di-Trid boundary in Fo-Di-Sil, the mantle solidus, origins of anorthosites, esoteric uses of Schreinemakers rules and many more topics are all fresh and pleasant memories of John Longhi's prolific and creative work. The Fram-Longhi experimental effect of pressure on plagioclase partitioning with liquid in mafic rocks became essential to an understanding of multiphase Rayleigh fractionation of plagioclase in big layered intrusions. Only by using the pressure effect could I find a good equation through the data for the Kiglapait intrusion, and that result among others required the existence with probability 1.0 of an internal reservoir (Morse, JPet 2008). Knowledge of cumulate porosity is a crucial key to the understanding of layered igneous rocks. We seek both the initial (inverse packing fraction) and residual porosity to find the time and process path from sedimentation to solidification. In the Kiglapait Lower Zone we have a robust estimate of mean residual porosity from the modes of the excluded phases augite, oxides, sulfide, and apatite. To this we apply the maximum variance of plagioclase composition (the An range) to find an algorithm that extends through the Upper Zone and to other intrusions. Of great importance is that all these measurements were made in grain mounts concentrated from typically about 200 g of core or hand specimen, hence the represented sample volume is thousands of times greater than for a thin section. The resulting distribution and scatter of the An range is novel and remarkable. It is V-shaped in the logarithmic representation of stratigraphic height, running from about 20 mole % at both ends (base to top of the Layered Series) to near-zero at 99 PCS. The intercept of the porosity-An range relation gives An range = 3.5 % at zero residual porosity. Petrographic analysis reveals that for PCS less than 95 and greater than 99.9, the An range is intrinsic, i.e. pre-cumulus, for

  1. Comparative and Cumulative Energetic Costs of Odontocete Responses to Anthropogenic Disturbance

    Science.gov (United States)

    2014-09-30

    predictive bioenergetic model of the metabolic costs of sound production across several cetacean species from the determination of the mass of sound...click sound production and the cost of sound production bioenergetic model will be completed, the estimates of cumulative impacts will be initiated...Consulting, Inc., and Maureen (Moe) Flannery at the California Academy of Sciences. These data will then be incorporated into a bioenergetic model

  2. A validation of a posture matching approach for the determination of 3D cumulative back loads.

    Science.gov (United States)

    Sutherland, Chad A; Albert, Wayne J; Wrigley, Allan T; Callaghan, Jack P

    2008-03-01

    The purpose of this project was to investigate the amount of error in calculating cumulative lumbar spine kinetics using a posture matching approach (3DMatch) compared to a 3D coordinate electromagnetic tracking approach (FASTRAK). Six subjects were required to perform five repeats each of two symmetrical and two asymmetrical lifts while being simultaneously recorded from 4 camera views at viewing angles of 0 degrees , 45 degrees , 60 degrees and 90 degrees to the sagittal plane while wearing eight FASTRAK sensors to define an 8 segment rigid link model (RLM) of the head, arms, and trunk. Four hundred and eighty lifts (6 subjects x20 lifts x4 camera views) were analyzed using the 3DMatch posture-matching program to calculate the following cumulative loads at the L4/L5 joint: compression, anterior shear, posterior shear, reaction shear and extension moment. The errors in cumulative load calculation were determined as the difference between the values calculated for the same lifts using a 3D RLM that used electromagnetic motion tracking sensors (FASTRAK) positioned at the segment center of masses as model inputs. No significant difference (pposture matching by trained users can provide reasonable 3D data to calculate cumulative low back loads with a biomechanical model.

  3. High selection pressure promotes increase in cumulative adaptive culture.

    Directory of Open Access Journals (Sweden)

    Carolin Vegvari

    Full Text Available The evolution of cumulative adaptive culture has received widespread interest in recent years, especially the factors promoting its occurrence. Current evolutionary models suggest that an increase in population size may lead to an increase in cultural complexity via a higher rate of cultural transmission and innovation. However, relatively little attention has been paid to the role of natural selection in the evolution of cultural complexity. Here we use an agent-based simulation model to demonstrate that high selection pressure in the form of resource pressure promotes the accumulation of adaptive culture in spite of small population sizes and high innovation costs. We argue that the interaction of demography and selection is important, and that neither can be considered in isolation. We predict that an increase in cultural complexity is most likely to occur under conditions of population pressure relative to resource availability. Our model may help to explain why culture change can occur without major environmental change. We suggest that understanding the interaction between shifting selective pressures and demography is essential for explaining the evolution of cultural complexity.

  4. New tests of cumulative prospect theory and the priority heuristic

    Directory of Open Access Journals (Sweden)

    Michael H. Birnbaum

    2008-04-01

    Full Text Available Previous tests of cumulative prospect theory (CPT and of the priority heuristic (PH found evidence contradicting these two models of risky decision making. However, those tests were criticized because they had characteristics that might ``trigger'' use of other heuristics. This paper presents new tests that avoid those characteristics. Expected values of the gambles are nearly equal in each choice. In addition, if a person followed expected value (EV, expected utility (EU, CPT, or PH in these tests, she would shift her preferences in the same direction as shifts in EV or EU. In contrast, the transfer of attention exchange model (TAX and a similarity model predict that people will reverse preferences in the opposite direction. Results contradict the PH, even when PH is modified to include a preliminary similarity evaluation using the PH parameters. New tests of probability-consequence interaction were also conducted. Strong interactions were observed, contrary to PH. These results add to the growing bodies of evidence showing that neither CPT nor PH is an accurate description of risky decision making.

  5. Cumulative stress and autonomic dysregulation in a community sample.

    Science.gov (United States)

    Lampert, Rachel; Tuit, Keri; Hong, Kwang-Ik; Donovan, Theresa; Lee, Forrester; Sinha, Rajita

    2016-05-01

    Whether cumulative stress, including both chronic stress and adverse life events, is associated with decreased heart rate variability (HRV), a non-invasive measure of autonomic status which predicts poor cardiovascular outcomes, is unknown. Healthy community dwelling volunteers (N = 157, mean age 29 years) participated in the Cumulative Stress/Adversity Interview (CAI), a 140-item event interview measuring cumulative adversity including major life events, life trauma, recent life events and chronic stressors, and underwent 24-h ambulatory ECG monitoring. HRV was analyzed in the frequency domain and standard deviation of NN intervals (SDNN) calculated. Initial simple regression analyses revealed that total cumulative stress score, chronic stressors and cumulative adverse life events (CALE) were all inversely associated with ultra low-frequency (ULF), very low-frequency (VLF) and low-frequency (LF) power and SDNN (all p stress and chronic stress each was significantly associated with SDNN and ULF even after the highly significant contributions of age and sex, with no other covariates accounting for additional appreciable variance. For VLF and LF, both total cumulative stress and chronic stress significantly contributed to the variance alone but were not longer significant after adjusting for race and health behaviors. In summary, total cumulative stress, and its components of adverse life events and chronic stress were associated with decreased cardiac autonomic function as measured by HRV. Findings suggest one potential mechanism by which stress may exert adverse effects on mortality in healthy individuals. Primary preventive strategies including stress management may prove beneficial.

  6. Cumulative asbestos exposure for US automobile mechanics involved in brake repair (circa 1950s-2000).

    Science.gov (United States)

    Finley, Brent L; Richter, Richard O; Mowat, Fionna S; Mlynarek, Steve; Paustenbach, Dennis J; Warmerdam, John M; Sheehan, Patrick J

    2007-11-01

    We analyzed cumulative lifetime exposure to chrysotile asbestos experienced by brake mechanics in the US during the period 1950-2000. Using Monte Carlo methods, cumulative exposures were calculated using the distribution of 8-h time-weighted average exposure concentrations for brake mechanics and the distribution of job tenure data for automobile mechanics. The median estimated cumulative exposures for these mechanics, as predicted by three probabilistic models, ranged from 0.16 to 0.41 fibers per cubic centimeter (f/cm(3)) year for facilities with no dust-control procedures (1970s), and from 0.010 to 0.012 f/cm(3) year for those employing engineering controls (1980s). Upper-bound (95%) estimates for the 1970s and 1980s were 1.96 to 2.79 and 0.07-0.10 f/cm(3) year, respectively. These estimates for US brake mechanics are consistent with, but generally slightly lower than, those reported for European mechanics. The values are all substantially lower than the cumulative exposure of 4.5 f/cm(3) year associated with occupational exposure to 0.1 f/cm(3) of asbestos for 45 years that is currently permitted under the current occupational exposure limits in the US. Cumulative exposures were usually about 100- to 1,000-fold less than those of other occupational groups with asbestos exposure for similar time periods. The cumulative lifetime exposure estimates presented here, combined with the negative epidemiology data for brake mechanics, could be used to refine the risk assessments for chrysotile-exposed populations.

  7. Entanglement entropy and particle number cumulants of disordered fermions

    Science.gov (United States)

    Burmistrov, I. S.; Tikhonov, K. S.; Gornyi, I. V.; Mirlin, A. D.

    2017-08-01

    We study the entanglement entropy and particle number cumulants for a system of disordered noninteracting fermions in d dimensions. We show, both analytically and numerically, that for a weak disorder the entanglement entropy and the second cumulant (particle number variance) are proportional to each other with a universal coefficient. The corresponding expressions are analogous to those in the clean case but with a logarithmic factor regularized by the mean free path rather than by the system size. We also determine the scaling of higher cumulants by analytical (weak disorder) and numerical means. Finally, we predict that the particle number variance and the entanglement entropy are nonanalytic functions of disorder at the Anderson transition.

  8. Relative Pesticide and Exposure Route Contribution to Aggregate and Cumulative Dose in Young Farmworker Children

    Directory of Open Access Journals (Sweden)

    Asa Bradman

    2012-01-01

    Full Text Available The Child-Specific Aggregate Cumulative Human Exposure and Dose (CACHED framework integrates micro-level activity time series with mechanistic exposure equations, environmental concentration distributions, and physiologically-based pharmacokinetic components to estimate exposure for multiple routes and chemicals. CACHED was utilized to quantify cumulative and aggregate exposure and dose estimates for a population of young farmworker children and to evaluate the model for chlorpyrifos and diazinon. Micro-activities of farmworker children collected concurrently with residential measurements of pesticides were used in the CACHED framework to simulate 115,000 exposure scenarios and quantify cumulative and aggregate exposure and dose estimates. Modeled metabolite urine concentrations were not statistically different than concentrations measured in the urine of children, indicating that CACHED can provide realistic biomarker estimates. Analysis of the relative contribution of exposure route and pesticide indicates that in general, chlorpyrifos non-dietary ingestion exposure accounts for the largest dose, confirming the importance of the micro-activity approach. The risk metrics computed from the 115,000 simulations, indicate that greater than 95% of these scenarios might pose a risk to children’s health from aggregate chlorpyrifos exposure. The variability observed in the route and pesticide contributions to urine biomarker levels demonstrate the importance of accounting for aggregate and cumulative exposure in establishing pesticide residue tolerances in food.

  9. Simulation of the cumulative hydrological response to green infrastructure

    Science.gov (United States)

    Avellaneda, P. M.; Jefferson, A. J.; Grieser, J. M.; Bush, S. A.

    2017-04-01

    In this study, we evaluated the cumulative hydrologic performance of green infrastructure in a residential area of the city of Parma, Ohio, draining to a tributary of the Cuyahoga River. Green infrastructure included the following spatially distributed devices: 16 street-side bioretention cells, 7 rain gardens, and 37 rain barrels. Data consisted of rainfall and outfall flow records for a wide range of storm events, including pretreatment and treatment periods. The Stormwater Management Model was calibrated and validated to predict the hydrologic response of green infrastructure. The calibrated model was used to quantify annual water budget alterations and discharge frequency over a 6 year simulation period. For the study catchment, we observed a treatment effect with increases of 1.4% in evaporation, 7.6% in infiltration, and a 9.0% reduction in surface runoff. The hydrologic performance of green infrastructure was evaluated by comparing the flow duration curve for pretreatment and treatment outfall flow scenarios. The flow duration curve shifted downward for the green infrastructure scenario. Discharges with a 0.5, 1, 2, and 5 year return period were reduced by an average of 29%. Parameter and predictive uncertainties were inspected by implementing a Bayesian statistical approach.

  10. A shock process with a non-cumulative damage

    Energy Technology Data Exchange (ETDEWEB)

    Finkelstein, M.S.; Zarudnij, V.I

    2001-01-01

    Two types of non-cumulative damage shock models are considered. Based on the distribution of damage, caused by a shock effecting a system, the intervals with small, intermediate and large damage are introduced. The initial homogeneous Poisson shock process is split into three homogeneous Poisson processes and studied independently. Several criteria of failure are considered, based on the assumption that shocks with a small level of damage are harmless for a system, shocks with a large level of damage results in the system's failure and shocks with an intermediate level of damage can result in the system's failure only with some probability. The second model is based on an assumption that shocks with a small level of damage are harmless to a system, if they are not too close to each other. The probability of the system's failure-free performance in [0,t) is derived explicitly. Simple asymptotic exponential approximations are obtained The accuracy of this method is analyzed. Possible generalizations are discussed.

  11. Cumulative creep fatigue damage in 316 stainless steel

    Science.gov (United States)

    Mcgaw, Michael A.

    1989-01-01

    The cumulative creep-fatigue damage behavior of 316 stainless steel at 1500 F was experimentally established for the two-level loading cases of fatigue followed by fatigue, creep fatigue followed by fatigue, and fatigue followed by creep fatigue. The two-level loadings were conducted such that the lower life (high strain) cycling was applied first for a controlled number of cycles and the higher life (low strain) cycling was conducted as the second level to failure. The target life levels in this study were 100 cycles to failure for both the fatigue and creep-fatigue lowlife loading, 5000 cycles to failure for the higher life fatigue loading and 10,000 cycles to failure for the higher life creep-fatigue loading. The failed specimens are being examined both fractographically and metallographically to ascertain the nature of the damaging mechanisms that produced failure. Models of creep-fatigue damage accumulation are being evaluated and knowledge of the various damaging mechanisms is necessary to ensure that predictive capability is instilled in the final failure model.

  12. Studying cumulative ozone exposures in Europe during a 7-year period

    Science.gov (United States)

    Bastrup-Birk, Annemarie; Brandt, JøRgen; Zlatev, Zahari; Uria, Ignacio

    1997-10-01

    Ozone is one of the most harmful pollutants in the troposphere. High ozone concentrations can damage plants, animals and humans. The damaging effects depend on the magnitude of a critical level of a special parameter, the cumulative ozone exposure. This is why cumulative ozone exposures must be carefully studied. It is important to determine the relationships between relevant emissions (NOx emissions, human-made VOC emissions, and/or a combination of NOx emissions and human-made VOC emissions) and cumulative ozone exposures. All these issues are discussed in this paper. Meteorological data from seven consecutive years, from 1989 to 1995, have been used in the experiments with different scenarios for varying the emissions (the NOx emissions, the human-made VOC emissions, as well as both the NOx emissions and the human-made VOC emissions). The particular air pollution model used in this study is the Danish Eulerian Model. Several hundred runs with different input data (meteorological data and/or emission data) have been performed. Advanced visualization techniques are used to interpret the large amount of digital data collected in these runs and to show clearly different trends and relationships that are normally hidden behind millions and millions of numbers. The model results were compared with measurements taken at more than 80 stations located in different European countries. The experiments indicate that it is sufficient to carry out computations over 5 consecutive years in order to eliminate the influence of extreme meteorological conditions (very warm or very cold summer months) on the cumulative ozone exposures, while this effect is clearly seen if less than 5 years are used in the experiments. It is shown that the relationship between the emissions (NOx and/or human-made VOC emissions) and the cumulative ozone exposures is in general nonlinear. Finally, it is illustrated that the critical values for ozone exposures are exceeded in most of Europe (in many

  13. Online Scheduling in Manufacturing A Cumulative Delay Approach

    CERN Document Server

    Suwa, Haruhiko

    2013-01-01

    Online scheduling is recognized as the crucial decision-making process of production control at a phase of “being in production" according to the released shop floor schedule. Online scheduling can be also considered as one of key enablers to realize prompt capable-to-promise as well as available-to-promise to customers along with reducing production lead times under recent globalized competitive markets. Online Scheduling in Manufacturing introduces new approaches to online scheduling based on a concept of cumulative delay. The cumulative delay is regarded as consolidated information of uncertainties under a dynamic environment in manufacturing and can be collected constantly without much effort at any points in time during a schedule execution. In this approach, the cumulative delay of the schedule has the important role of a criterion for making a decision whether or not a schedule revision is carried out. The cumulative delay approach to trigger schedule revisions has the following capabilities for the ...

  14. Cumulative Risks of Foster Care Placement for Danish Children

    DEFF Research Database (Denmark)

    Fallesen, Peter; Emanuel, Natalia; Wildeman, Christopher

    2014-01-01

    Although recent research suggests that the cumulative risk of foster care placement is far higher for American children than originally suspected, little is known about the cumulative risk of foster care placement in other countries, which makes it difficult to gauge the degree to which factor...... is for Danish children. Results suggest that at the beginning of the study period (in 1998) the cumulative risk of foster care placement for Danish children was roughly in line with the risk for American children. Yet, by the end of the study period (2010), the risk had declined to half the risk for American...... foster care placement is salient in other contexts. In this article, we provide companion estimates to those provided in recent work on the US by using Danish registry data and synthetic cohort life tables to show how high and unequally distributed the cumulative risk of foster care placement...

  15. Mapping cumulative human impacts in the eastern North Sea

    DEFF Research Database (Denmark)

    Stock, A.; Andersen, Jesper; Heinänen, S.

    of the MSFD; and 3) to deepen the understanding of how errors in expert judgment affect the resulting cumulative human impact maps by means of Monte Carlo simulations. We combined existing data sets on the spatial distribution of 33 anthropogenic stressors (linked to the MSFD pressures) and 28 key habitats....... In contrast, the predicted impacts for much of the Norwegian EEZ and areas far offshore were lower. The Monte Carlo simulations confirmed earlier findings that mapping cumulative impacts is generally "robust", but also showed that specific combinations of errors can seriously change local and regional...... on marine ecosystems have only recently been developed. The aims of our study were: 1) to develop a map of cumulative human impacts for the Danish, Swedish, Norwegian and German parts of the Greater North Sea; 2) to adjust the existing methods for mapping cumulative human impacts to fit the requirements...

  16. Cumulative Production Per Township - SaMiRa

    Data.gov (United States)

    U.S. Geological Survey, Department of the Interior — This dataset contains a selected township grid within the Sagebrush Mineral Resource Assessment project (SaMiRa) study area attributed with cumulative oil and gas...

  17. Cumulative radiation exposure in children with cystic fibrosis.

    LENUS (Irish Health Repository)

    O'Reilly, R

    2010-02-01

    This retrospective study calculated the cumulative radiation dose for children with cystic fibrosis (CF) attending a tertiary CF centre. Information on 77 children with a mean age of 9.5 years, a follow up time of 658 person years and 1757 studies including 1485 chest radiographs, 215 abdominal radiographs and 57 computed tomography (CT) scans, of which 51 were thoracic CT scans, were analysed. The average cumulative radiation dose was 6.2 (0.04-25) mSv per CF patient. Cumulative radiation dose increased with increasing age and number of CT scans and was greater in children who presented with meconium ileus. No correlation was identified between cumulative radiation dose and either lung function or patient microbiology cultures. Radiation carries a risk of malignancy and children are particularly susceptible. Every effort must be made to avoid unnecessary radiation exposure in these patients whose life expectancy is increasing.

  18. Macroscopic cumulative fatigue damage of material under nonsymmetrical cycle

    Institute of Scientific and Technical Information of China (English)

    盖秉政

    2002-01-01

    Hashin's macroscopic theory of fatigue damage is further discussed and a new method has been proposed for prediction of cumulative fatigue damage of material and its lifetime under nonsymmetrical cyclic loading.

  19. Translation-Invariant Representation for Cumulative Foot Pressure Images

    CERN Document Server

    Zheng, Shuai; Tan, Tieniu

    2010-01-01

    Human can be distinguished by different limb movements and unique ground reaction force. Cumulative foot pressure image is a 2-D cumulative ground reaction force during one gait cycle. Although it contains pressure spatial distribution information and pressure temporal distribution information, it suffers from several problems including different shoes and noise, when putting it into practice as a new biometric for pedestrian identification. In this paper, we propose a hierarchical translation-invariant representation for cumulative foot pressure images, inspired by the success of Convolutional deep belief network for digital classification. Key contribution in our approach is discriminative hierarchical sparse coding scheme which helps to learn useful discriminative high-level visual features. Based on the feature representation of cumulative foot pressure images, we develop a pedestrian recognition system which is invariant to three different shoes and slight local shape change. Experiments are conducted on...

  20. Stochastic Dynamic User Optimum Model with Departure Time Choice Based on Cumulative Prospect Theory%基于累积前景理论的出发时间选择SDUO模型

    Institute of Scientific and Technical Information of China (English)

    张波; 隽志才; 林徐勋

    2013-01-01

    The existing dynamic traffic assignment models that deal with departure time choice generally construct utility or disutility functions based on the concepts of time-window and schedule delay. Travelers are assumed to be entirely rational and have full access to the information of dynamic traffic system. The reference points and the difference between arrival times within time-window are not considered in our assumption. There are often systematical deviations between traffic assignment results and real traffic (low. Traffic system is an uncertain dynamic system characterized as time-varying and stochastic. Constrained by the compound effect of imperfect traffic information, limited cognitive capability, value orientations and the degree of rationality, travelers are rarely able to perform their travel decisions with entire rationality. Researches of psychology and behavior science demonstrate that decisions under uncertainty appear to be bounded rational. As a descriptive theory, the Prospect Theory reveals psychological and behavioral mechanisms of people with bounded rationality, and demonstrates the patterns and human decision-making characteristics under risk. A few empirical studies experimenting on travelers have shown that travel behaviors under uncertainty, especially in the choices of departure time and route, and their attitude towards risk coincide with the main assumptions of Prospect Theory. Focused oncommuting trips during peak hours in the morning, this paper explores the usefulness of Prospect Theory in the dynamic traffic assignment. First, commuters are classified into early arrivals and late arrivals according to when they arrive at their workplace. The reference points for departure time and route choices are defined in a dynamic stochastic traffic network. The continuous functions of Prospect Theory for departure time and route choices in the condition of continuous traffic flow are constructed. A Stochastic Dynamic User Optimum (SDUO) model

  1. Childhood Cumulative Risk Exposure and Adult Amygdala Volume and Function.

    Science.gov (United States)

    Evans, Gary W; Swain, James E; King, Anthony P; Wang, Xin; Javanbakht, Arash; Ho, S Shaun; Angstadt, Michael; Phan, K Luan; Xie, Hong; Liberzon, Israel

    2016-06-01

    Considerable work indicates that early cumulative risk exposure is aversive to human development, but very little research has examined the neurological underpinnings of these robust findings. This study investigates amygdala volume and reactivity to facial stimuli among adults (mean 23.7 years of age, n = 54) as a function of cumulative risk exposure during childhood (9 and 13 years of age). In addition, we test to determine whether expected cumulative risk elevations in amygdala volume would mediate functional reactivity of the amygdala during socioemotional processing. Risks included substandard housing quality, noise, crowding, family turmoil, child separation from family, and violence. Total and left hemisphere adult amygdala volumes were positively related to cumulative risk exposure during childhood. The links between childhood cumulative risk exposure and elevated amygdala responses to emotionally neutral facial stimuli in adulthood were mediated by the corresponding amygdala volumes. Cumulative risk exposure in later adolescence (17 years of age), however, was unrelated to subsequent adult amygdala volume or function. Physical and socioemotional risk exposures early in life appear to alter amygdala development, rendering adults more reactive to ambiguous stimuli such as neutral faces. These stress-related differences in childhood amygdala development might contribute to the well-documented psychological distress as a function of early risk exposure.

  2. From cultural traditions to cumulative culture: parameterizing the differences between human and nonhuman culture.

    Science.gov (United States)

    Kempe, Marius; Lycett, Stephen J; Mesoudi, Alex

    2014-10-21

    Diverse species exhibit cultural traditions, i.e. population-specific profiles of socially learned traits, from songbird dialects to primate tool-use behaviours. However, only humans appear to possess cumulative culture, in which cultural traits increase in complexity over successive generations. Theoretically, it is currently unclear what factors give rise to these phenomena, and consequently why cultural traditions are found in several species but cumulative culture in only one. Here, we address this by constructing and analysing cultural evolutionary models of both phenomena that replicate empirically attestable levels of cultural variation and complexity in chimpanzees and humans. In our model of cultural traditions (Model 1), we find that realistic cultural variation between populations can be maintained even when individuals in different populations invent the same traits and migration between populations is frequent, and under a range of levels of social learning accuracy. This lends support to claims that putative cultural traditions are indeed cultural (rather than genetic) in origin, and suggests that cultural traditions should be widespread in species capable of social learning. Our model of cumulative culture (Model 2) indicates that both the accuracy of social learning and the number of cultural demonstrators interact to determine the complexity of a trait that can be maintained in a population. Combining these models (Model 3) creates two qualitatively distinct regimes in which there are either a few, simple traits, or many, complex traits. We suggest that these regimes correspond to nonhuman and human cultures, respectively. The rarity of cumulative culture in nature may result from this interaction between social learning accuracy and number of demonstrators.

  3. Cumulative production of pions by heavy baryonic resonances in proton-nucleus collisions

    Science.gov (United States)

    Motornenko, A.; Gorenstein, M. I.

    2017-02-01

    Pion production in proton-nucleus (p+A) collisions outside the kinematical boundary of proton-nucleon (p+N) reactions and the so-called cumulative effect are studied. Restrictions from energy-momentum conservation of the energy of pions emitted in the backward direction in the target rest frame are analyzed. It is assumed that the cumulative pions are produced in p+A reactions by heavy baryonic resonances. The baryonic resonances are first created in p+N reactions. Due to successive collisions with nuclear nucleons, the masses of these resonances may then increase and, simultaneously, their longitudinal velocities decrease. We also use the ultra relativistic quantum molecular dynamics model to reveal the key role of successive collisions of baryonic resonances with nuclear nucleons for cumulative pion production in p+A reactions. Further experimental studies of cumulative hadron production in p+A reactions at high collision energies are needed to search for heavy hadron-like objects and investigate their properties.

  4. Evaluation of Cumulative Ecosystem Response to Restoration Projects in the Lower Columbia River and Estuary, 2010

    Energy Technology Data Exchange (ETDEWEB)

    Johnson, Gary E.; Diefenderfer, Heida L.; Thom, Ronald M.; Roegner, G. Curtis; Ebberts, Blaine D.; Skalski, John R.; Borde, Amy B.; Dawley, Earl; Coleman, Andre M.; Woodruff, Dana L.; Breithaupt, Stephen A.; Cameron, April; Corbett, C.; Donley, Erin E.; Jay, D. A.; Ke, Yinghai; Leffler, K.; McNeil, C.; Studebaker, Cindy; Tagestad, Jerry D.

    2012-05-01

    This is the seventh and final annual report of a project (2004–2010) addressing evaluation of the cumulative effects of habitat restoration actions in the 235-km-long lower Columbia River and estuary. The project, called the Cumulative Effects (CE) study, was conducted for the U.S. Army Corps of Engineers Portland District by a collaboration of research agencies led by the Pacific Northwest National Laboratory. We achieved the primary goal of the CE study to develop a methodology to evaluate the cumulative effects of habitat actions in the Columbia Estuary Ecosystem Restoration Program. We delivered 1) standard monitoring protocols and methods to prioritize monitoring activities; 2) the theoretical and empirical basis for a CE methodology using levels-of-evidence; 3) evaluations of cumulative effects using ecological relationships, geo-referenced data, hydrodynamic modeling, and meta-analyses; and 4) an adaptive management process to coordinate and coalesce restoration efforts in the LCRE. A solid foundation has been laid for future comprehensive evaluations of progress made by the Columbia Estuary Ecosystem Restoration Program to understand, conserve, and restore ecosystems in the lower Columbia River and estuary.

  5. A probabilistic analysis of cumulative carbon emissions and long-term planetary warming

    Science.gov (United States)

    Fyke, Jeremy; Damon Matthews, H.

    2015-11-01

    Efforts to mitigate and adapt to long-term climate change could benefit greatly from probabilistic estimates of cumulative carbon emissions due to fossil fuel burning and resulting CO2-induced planetary warming. Here we demonstrate the use of a reduced-form model to project these variables. We performed simulations using a large-ensemble framework with parametric uncertainty sampled to produce distributions of future cumulative emissions and consequent planetary warming. A hind-cast ensemble of simulations captured 1980-2012 historical CO2 emissions trends and an ensemble of future projection simulations generated a distribution of emission scenarios that qualitatively resembled the suite of Representative and Extended Concentration Pathways. The resulting cumulative carbon emission and temperature change distributions are characterized by 5-95th percentile ranges of 0.96-4.9 teratonnes C (Tt C) and 1.4 °C-8.5 °C, respectively, with 50th percentiles at 3.1 Tt C and 4.7 °C. Within the wide range of policy-related parameter combinations that produced these distributions, we found that low-emission simulations were characterized by both high carbon prices and low costs of non-fossil fuel energy sources, suggesting the importance of these two policy levers in particular for avoiding dangerous levels of climate warming. With this analysis we demonstrate a probabilistic approach to the challenge of identifying strategies for limiting cumulative carbon emissions and assessing likelihoods of surpassing dangerous temperature thresholds.

  6. Cumulative violence exposure, emotional nonacceptance, and mental health symptoms in a community sample of women.

    Science.gov (United States)

    Sundermann, Jane M; Chu, Ann T; DePrince, Anne P

    2013-01-01

    Women exposed to more types of violence (e.g., emotional, physical, or sexual violence)--referred to here as cumulative violence exposure--are at risk for more severe mental health symptoms compared to women who are exposed to a single type of violence or no violence. Women exposed to violence may also experience greater emotional nonacceptance compared to women with no exposure to violence. Emotional nonacceptance refers to an unwillingness to experience emotional states, including cognitive and behavioral attempts to avoid experiences of emotion. Given the links between cumulative violence exposure, emotional nonacceptance, and mental health symptoms among female victims of violence, the current study tested victims' emotional nonacceptance as a partial mediator between cumulative violence exposure and the severity of 3 types of symptoms central to complex trauma responses: depression, dissociation, and posttraumatic stress disorder (PTSD) symptoms. A non-treatment-seeking community sample of women (N = 89; M age = 30.70 years) completed self-report questionnaires and interviews. Bootstrap procedures were then used to test 3 mediation models for the separate predictions of depression, dissociation, and PTSD symptoms. Results supported our hypotheses that emotional nonacceptance would mediate the relationship between women's cumulative violence exposure and severity for all symptom types. The current findings highlight the role that emotional nonacceptance may play in the development of mental health symptoms for chronically victimized women and point to the need for longitudinal research in such populations.

  7. Regional estimates of the transient climate response to cumulative CO2 emissions

    Science.gov (United States)

    Leduc, Martin; Matthews, H. Damon; de Elía, Ramón

    2016-05-01

    The Transient Climate Response to cumulative carbon Emissions (TCRE) measures the response of global temperatures to cumulative CO2 emissions. Although the TCRE is a global quantity, climate impacts manifest predominantly in response to local climate changes. Here we quantify the link between CO2 emissions and regional temperature change, showing that regional temperatures also respond approximately linearly to cumulative CO2 emissions. Using an ensemble of twelve Earth system models, we present a novel application of pattern scaling to define the regional pattern of temperature change per emission of CO2. Ensemble mean regional TCRE values range from less than 1 °C per TtC for some ocean regions, to more than 5 °C per TtC in the Arctic, with a pattern of higher values over land and at high northern latitudes. We find also that high-latitude ocean regions deviate more strongly from linearity as compared to land and lower-latitude oceans. This suggests that ice-albedo and ocean circulation feedbacks are important contributors to the overall negative deviation from linearity of the global temperature response to high levels of cumulative emissions. The strong linearity of the regional climate response over most land regions provides a robust way to quantitatively link anthropogenic CO2 emissions to local-scale climate impacts.

  8. Cumulative effects of early poverty on cortisol in young children: moderation by autonomic nervous system activity.

    Science.gov (United States)

    Blair, Clancy; Berry, Daniel; Mills-Koonce, Roger; Granger, Douglas

    2013-11-01

    The relation of the cumulative experience of poverty in infancy and early childhood to child cortisol at age 48 months was examined in a prospective longitudinal sample of children and families (N=1292) in predominantly low-income and rural communities in two distinct regions of the United States. Families were seen in the home for data collection and cumulative experience of poverty was indexed by parent reported income-to-need ratio and household chaos measures collected between child ages 2 months and 48 months. For the analysis presented here, three saliva samples were also collected over an approximate 90 min interval at child age 48 months and were assayed for cortisol. ECG data were also collected during a resting period and during the administration of a mildly challenging battery of cognitive tasks. Mixed model analysis indicated that child cortisol at 48 months decreased significantly over the sampling time period and that cumulative time in poverty (number of years income-to-need less than or equal to 1) and cumulative household chaos were significantly related to a flatter trajectory for cortisol change and to an overall higher level of cortisol, respectively. Findings also indicated that respiratory sinus arrhythmia derived from the ECG data moderated the association between household chaos and child cortisol and that increase in respiratory sinus arrhythmia during the cognitive task was associated with an overall lower level of cortisol at 48 months.

  9. Microcanonical thermostatistics analysis without histograms: cumulative distribution and Bayesian approaches

    CERN Document Server

    Alves, Nelson A; Rizzi, Leandro G

    2015-01-01

    Microcanonical thermostatistics analysis has become an important tool to reveal essential aspects of phase transitions in complex systems. An efficient way to estimate the microcanonical inverse temperature $\\beta(E)$ and the microcanonical entropy $S(E)$ is achieved with the statistical temperature weighted histogram analysis method (ST-WHAM). The strength of this method lies on its flexibility, as it can be used to analyse data produced by algorithms with generalised sampling weights. However, for any sampling weight, ST-WHAM requires the calculation of derivatives of energy histograms $H(E)$, which leads to non-trivial and tedious binning tasks for models with continuous energy spectrum such as those for biomolecular and colloidal systems. Here, we discuss two alternative methods that avoid the need for such energy binning to obtain continuous estimates for $H(E)$ in order to evaluate $\\beta(E)$ by using ST-WHAM: (i) a series expansion to estimate probability densities from the empirical cumulative distrib...

  10. The cumulative energy effect for improved ignition timing

    Energy Technology Data Exchange (ETDEWEB)

    Markhotok, A., E-mail: amarhotk@phys.washington.edu [Physics Department, Old Dominion University, Norfolk, Virginia 23529 (United States)

    2015-04-15

    A technique capable of improving timing in ignition applications is proposed. It is based on the use of shock waves propagating in a specific medium that allows achieving extremely high speeds and energies. The model uses the energy cumulation effect in the presence of the shock wave refraction on an interface with plasma. The problem was solved analytically and the effects were demonstrated for a cylindrically symmetrical geometry. Numerical results show very quick and uneven acceleration of different portions of the shock front. Its strong distortions lead to formation of a sharply focused jet near the axis of symmetry. The ability of the shock to achieve extremely high speeds and energies can be useful in design of efficient combustors for hypersonic systems, and possibly offers an alternative way of construction of a nuclear fusion reactor. Recommendations are given in terms of adjustment parameters and can be applied at any problem scale and for various combinations of the strengths of the effects involved in the problem.

  11. Multi-agent fare optimization model of two modes problem and its analysis based on edge of chaos

    Science.gov (United States)

    Li, Xue-yan; Li, Xue-mei; Li, Xue-wei; Qiu, He-ting

    2017-03-01

    This paper proposes a new framework of fare optimization & game model for studying the competition between two travel modes (high speed railway and civil aviation) in which passengers' group behavior is taken into consideration. The small-world network is introduced to construct the multi-agent model of passengers' travel mode choice. The cumulative prospect theory is adopted to depict passengers' bounded rationality, the heterogeneity of passengers' reference point is depicted using the idea of group emotion computing. The conceptions of "Langton parameter" and "evolution entropy" in the theory of "edge of chaos" are introduced to create passengers' "decision coefficient" and "evolution entropy of travel mode choice" which are used to quantify passengers' group behavior. The numerical simulation and the analysis of passengers' behavior show that (1) the new model inherits the features of traditional model well and the idea of self-organizing traffic flow evolution fully embodies passengers' bounded rationality, (2) compared with the traditional model (logit model), when passengers are in the "edge of chaos" state, the total profit of the transportation system is higher.

  12. Development and estimation of a semi-compensatory model with flexible error structure

    DEFF Research Database (Denmark)

    Kaplan, Sigal; Shiftan, Yoram; Bekhor, Shlomo

    -response model and the utility-based choice by alternatively (i) a nested-logit model and (ii) an error-component logit. In order to test the suggested methodology, the model was estimated for a sample of 1,893 ranked choices and respective threshold values from 631 students who participated in a web-based two......, a disadvantage of current semi-compensatory models versus compensatory models is their behaviorally non-realistic assumption of an independent error structure. This study proposes a novel semi-compensatory model incorporating a flexible error structure. Specifically, the model represents a sequence...

  13. On the duration and intensity of cumulative advantage competitions

    Science.gov (United States)

    Jiang, Bo; Sun, Liyuan; Figueiredo, Daniel R.; Ribeiro, Bruno; Towsley, Don

    2015-11-01

    Network growth can be framed as a competition for edges among nodes in the network. As with various other social and physical systems, skill (fitness) and luck (random chance) act as fundamental forces driving competition dynamics. In the context of networks, cumulative advantage (CA)—the rich-get-richer effect—is seen as a driving principle governing the edge accumulation process. However, competitions coupled with CA exhibit non-trivial behavior and little is formally known about duration and intensity of CA competitions. By isolating two nodes in an ideal CA competition, we provide a mathematical understanding of how CA exacerbates the role of luck in detriment of skill. We show, for instance, that when nodes start with few edges, an early stroke of luck can place the less skilled in the lead for an extremely long period of time, a phenomenon we call ‘struggle of the fittest’. We prove that duration of a simple skill and luck competition model exhibit power-law tails when CA is present, regardless of skill difference, which is in sharp contrast to the exponential tails when fitness is distinct but CA is absent. We also prove that competition intensity is always upper bounded by an exponential tail, irrespective of CA and skills. Thus, CA competitions can be extremely long (infinite mean, depending on fitness ratio) but almost never very intense. The theoretical results are corroborated by extensive numerical simulations. Our findings have important implications to competitions not only among nodes in networks but also in contexts that leverage socio-physical models embodying CA competitions.

  14. Cumulative risks of foster care placement for Danish children.

    Science.gov (United States)

    Fallesen, Peter; Emanuel, Natalia; Wildeman, Christopher

    2014-01-01

    Although recent research suggests that the cumulative risk of foster care placement is far higher for American children than originally suspected, little is known about the cumulative risk of foster care placement in other countries, which makes it difficult to gauge the degree to which factor foster care placement is salient in other contexts. In this article, we provide companion estimates to those provided in recent work on the US by using Danish registry data and synthetic cohort life tables to show how high and unequally distributed the cumulative risk of foster care placement is for Danish children. Results suggest that at the beginning of the study period (in 1998) the cumulative risk of foster care placement for Danish children was roughly in line with the risk for American children. Yet, by the end of the study period (2010), the risk had declined to half the risk for American children. Our results also show some variations by parental ethnicity and sex, but these differences are small. Indeed, they appear quite muted relative to racial/ethnic differences in these risks in the United States. Last, though cumulative risks are similar between Danish and American children (especially at the beginning of the study period), the age-specific risk profiles are markedly different, with higher risks for older Danish children than for older American children.

  15. USING CUMULATIVE NUMBER DENSITIES TO COMPARE GALAXIES ACROSS COSMIC TIME

    Energy Technology Data Exchange (ETDEWEB)

    Behroozi, Peter S.; Wechsler, Risa H. [Kavli Institute for Particle Astrophysics and Cosmology, SLAC National Accelerator Laboratory, Stanford, CA 94305 (United States); Marchesini, Danilo [Department of Physics and Astronomy, Tufts University, Medford, MA 02155 (United States); Muzzin, Adam [Leiden Observatory, Leiden University, P.O. Box 9513, 2300 RA Leiden (Netherlands); Papovich, Casey [Department of Physics and Astronomy, Texas A and M University, College Station, TX 77843 (United States); Stefanon, Mauro [Physics and Astronomy Department, University of Missouri, Columbia, MO 65211 (United States)

    2013-11-01

    Comparing galaxies across redshifts at fixed cumulative number density is a popular way to estimate the evolution of specific galaxy populations. This method ignores scatter in mass accretion histories and galaxy-galaxy mergers, which can lead to errors when comparing galaxies over large redshift ranges (Δz > 1). We use abundance matching in the ΛCDM paradigm to estimate the median change in cumulative number density with redshift and provide a simple fit (+0.16 dex per unit Δz) for progenitors of z = 0 galaxies. We find that galaxy descendants do not evolve in the same way as galaxy progenitors, largely due to scatter in mass accretion histories. We also provide estimates for the 1σ range of cumulative number densities corresponding to galaxy progenitors and descendants. Finally, we discuss some limits on cumulative number density comparisons, which arise due to difficulties measuring physical quantities (e.g., stellar mass) consistently across redshifts. A public tool to calculate cumulative number density evolution for galaxies, as well as approximate halo masses, is available online.

  16. Maintenance hemodialysis patients have high cumulative radiation exposure.

    LENUS (Irish Health Repository)

    Kinsella, Sinead M

    2010-10-01

    Hemodialysis is associated with an increased risk of neoplasms which may result, at least in part, from exposure to ionizing radiation associated with frequent radiographic procedures. In order to estimate the average radiation exposure of those on hemodialysis, we conducted a retrospective study of 100 patients in a university-based dialysis unit followed for a median of 3.4 years. The number and type of radiological procedures were obtained from a central radiology database, and the cumulative effective radiation dose was calculated using standardized, procedure-specific radiation levels. The median annual radiation dose was 6.9 millisieverts (mSv) per patient-year. However, 14 patients had an annual cumulative effective radiation dose over 20 mSv, the upper averaged annual limit for occupational exposure. The median total cumulative effective radiation dose per patient over the study period was 21.7 mSv, in which 13 patients had a total cumulative effective radiation dose over 75 mSv, a value reported to be associated with a 7% increased risk of cancer-related mortality. Two-thirds of the total cumulative effective radiation dose was due to CT scanning. The average radiation exposure was significantly associated with the cause of end-stage renal disease, history of ischemic heart disease, transplant waitlist status, number of in-patient hospital days over follow-up, and death during the study period. These results highlight the substantial exposure to ionizing radiation in hemodialysis patients.

  17. Universal off-equilibrium scaling of critical cumulants in the QCD phase diagram

    CERN Document Server

    Mukherjee, Swagato; Yin, Yi

    2016-01-01

    Exploiting the universality between the QCD critical point and the three dimensional Ising model, closed form expressions derived (arXiv:1506.00645 ) for non-equilibrium critical cumulants on the crossover side of the critical point reveal that they can differ both in magnitude and sign from equilibrium expectations. We demonstrate here that key elements of the Kibble-Zurek framework of non-equilibrium phase transitions can be employed to describe the dynamics of these critical cumulants. Our results suggest that observables sensitive to critical dynamics in heavy-ion collisions should be expressible as universal scaling functions, thereby providing powerful model independent guidance in searches for the QCD critical point.

  18. The 'cumulative' formulation of (physiologically) structured population models

    NARCIS (Netherlands)

    Diekmann, O.; Gyllenberg, M.; Metz, J.A.J.; Thieme, H.R.; Clément, P.P.; Lumer, G.

    1994-01-01

    bibliographical data to be processed -- Evolution equations, control theory, and biomathematics (Han sur Lesse, 1991) Pages: 145--154 Series: Lecture Notes in Pure and Appl. Math. Vol: 155 -- Dekker (New York) -- 9

  19. Cumulative Trauma Among Mayas Living in Southeast Florida.

    Science.gov (United States)

    Millender, Eugenia I; Lowe, John

    2016-01-04

    Mayas, having experienced genocide, exile, and severe poverty, are at high risk for the consequences of cumulative trauma that continually resurfaces through current fear of an uncertain future. Little is known about the mental health and alcohol use status of this population. This correlational study explored t/he relationship of cumulative trauma as it relates to social determinants of health (years in the United States, education, health insurance status, marital status, and employment), psychological health (depression symptoms), and health behaviors (alcohol use) of 102 Guatemalan Mayas living in Southeast Florida. The results of this study indicated that, as specific social determinants of health and cumulative trauma increased, depression symptoms (particularly among women) and the risk for harmful alcohol use (particularly among men) increased. Identifying risk factors at an early stage before serious disease or problems are manifest provides room for early screening leading to early identification, early treatment, and better outcomes.

  20. Solid-state electro-cumulation effect numerical simulation

    CERN Document Server

    Grishin, V G

    2001-01-01

    It is an attempt to simulate as really as possible a crystal's interatomic interaction under conditions of "Solid-state electro-cumulation (super-polarization) effect". Some theoretical and experimental reasons to believe that within solid substances an interparticles interaction could concentrate from the surface to a centre were given formerly. Now, numerical results show the conditions that could make the cumulation more effective. Another keywords: ion, current, solid, symmetry, cumulation, polarization, depolarization, ionic conductor,superionic conductor, ice, crystal, strain, V-center, V-centre, doped crystal, interstitial impurity, intrinsic color center, high pressure technology, Bridgman, anvil, experiment, crowdion, dielectric, proton, layer, defect, lattice, dynamics, electromigration, mobility, muon catalysis, concentration, doping, dopant, conductivity, pycnonuclear reaction, permittivity, dielectric constant, point defects, interstitials, polarizability, imperfection, defect centers, glass, epi...

  1. Baltic Sea biodiversity status vs. cumulative human pressures

    DEFF Research Database (Denmark)

    Andersen, Jesper H.; Halpern, Benjamin S.; Korpinen, Samuli

    2015-01-01

    Abstract Many studies have tried to explain spatial and temporal variations in biodiversity status of marine areas from a single-issue perspective, such as fishing pressure or coastal pollution, yet most continental seas experience a wide range of human pressures. Cumulative impact assessments have...... been developed to capture the consequences of multiple stressors for biodiversity, but the ability of these assessments to accurately predict biodiversity status has never been tested or ground-truthed. This relationship has similarly been assumed for the Baltic Sea, especially in areas with impaired...... status, but has also never been documented. Here we provide a first tentative indication that cumulative human impacts relate to ecosystem condition, i.e. biodiversity status, in the Baltic Sea. Thus, cumulative impact assessments offer a promising tool for informed marine spatial planning, designation...

  2. Cumulative risk effects in the bullying of children and young people with autism spectrum conditions.

    Science.gov (United States)

    Hebron, Judith; Oldfield, Jeremy; Humphrey, Neil

    2017-04-01

    Students with autism are more likely to be bullied than their typically developing peers. However, several studies have shown that their likelihood of being bullied increases in the context of exposure to certain risk factors (e.g. behaviour difficulties and poor peer relationships). This study explores vulnerability to bullying from a cumulative risk perspective, where the number of risks rather than their nature is considered. A total of 722 teachers and 119 parents of young people with autism spectrum conditions participated in the study. Established risk factors were summed to form a cumulative risk score in teacher and parent models. There was evidence of a cumulative risk effect in both models, suggesting that as the number of risks increased, so did exposure to bullying. A quadratic effect was found in the teacher model, indicating that there was a disproportionate increase in the likelihood of being bullied in relation to the number of risk factors to which a young person was exposed. In light of these findings, it is proposed that more attention needs to be given to the number of risks to which children and young people with autism spectrum conditions are exposed when planning interventions and providing a suitable educational environment.

  3. Cumulative creep-fatigue damage evolution in an austenitic stainless steel

    Science.gov (United States)

    Mcgaw, Michael A.

    1992-01-01

    A model of cumulative creep-fatigue damage has been developed which is based on the use of damage curve equations to describe the evolution of creep-fatigue damage for four basic creep-fatigue cycle types. These cycle types correspond to the four fundamental cycles of the Strain Range Partitioning Life Prediction approach of Manson, Halford, and Hirschberg. A concept referred to as Damage Coupling is introduced to analytically account for the differences in the nature of the damage introduced by each cycle type. For application of this model, the cumulative creep-fatigue damage behavior of type 316 stainless steel at 816 C has been experimentally established for the two-level loading cases involving fatigue and creep-fatigue, in various permutations. The tests were conducted such that the lower life (high strain) cycling was applied first, for a controlled number of cycles, and the higher life (lower strain) cycling was conducted at the second level, to failure. The proposed model correlated the majority of the observed cumulative creep-fatigue data.

  4. System Dynamics and Modified Cumulant Neglect Closure Schemes

    DEFF Research Database (Denmark)

    Köylüoglu, H. Ugur; Nielsen, Søren R.K.

    Dealing with multipeaked problems, the goal of the paper is to improve the quality of the approximations for the expectations appearing in the differential equations written for the statistical moments of the state vector, guided by insight in the system dynamics. For systems with polynomial non......-linearities, modifications in the cumulant neglect closure scheme are suggested. The methodology is illustrated using the two wells oscillator. An error analysis is performed to compare the modified and ordinary cumulant neglect closure schemes applied at the second and fourth order levels with the exact results available....

  5. Baltic Sea biodiversity status vs. cumulative human pressures

    DEFF Research Database (Denmark)

    Andersen, Jesper H.; Halpern, Benjamin S.; Korpinen, Samuli

    2015-01-01

    been developed to capture the consequences of multiple stressors for biodiversity, but the ability of these assessments to accurately predict biodiversity status has never been tested or ground-truthed. This relationship has similarly been assumed for the Baltic Sea, especially in areas with impaired...... status, but has also never been documented. Here we provide a first tentative indication that cumulative human impacts relate to ecosystem condition, i.e. biodiversity status, in the Baltic Sea. Thus, cumulative impact assessments offer a promising tool for informed marine spatial planning, designation...

  6. Aspect of cumulative fatigue damage under multiaxial strain cycling.

    Science.gov (United States)

    Zamrik, S. Y.; Tang, P. Y.

    1972-01-01

    The concept of order of loading and its effect on cumulative fatigue damage under multiaxial strain cyclings was investigated. The effect is illustrated through nonlinear relationships between biaxial fatigue damage and cycle-ratio diagrams. Uniaxial theories such as Miner's method, the convergence method, and the double linear damage rule in its special and generalized form, were examined and extended to the biaxial case through the octahedral shear strain theory. The generalized double linear damage rule was found more applicable to biaxial cumulative fatigue damage.

  7. Cumulative Incidence of Cancer After Solid Organ Transplantation

    Science.gov (United States)

    Hall, Erin C.; Pfeiffer, Ruth M.; Segev, Dorry L.; Engels, Eric A.

    2014-01-01

    BACKGROUND Solid organ transplantation recipients have elevated cancer incidence. Estimates of absolute cancer risk after transplantation can inform prevention and screening. METHODS The Transplant Cancer Match Study links the US transplantation registry with 14 state/regional cancer registries. The authors used nonparametric competing risk methods to estimate the cumulative incidence of cancer after transplantation for 2 periods (1987–1999 and 2000–2008). For recipients from 2000 to 2008, the 5-year cumulative incidence, stratified by organ, sex, and age at transplantation, was estimated for 6 preventable or screen-detectable cancers. For comparison, the 5-year cumulative incidence was calculated for the same cancers in the general population at representative ages using Surveillance, Epidemiology, and End Results data. RESULTS Among 164,156 recipients, 8520 incident cancers were identified. The absolute cancer risk was slightly higher for recipients during the period from 2000 to 2008 than during the period from 1987 to 1999 (5-year cumulative incidence: 4.4% vs 4.2%; P =.006); this difference arose from the decreasing risk of competing events (5-year cumulative incidence of death, graft failure, or retransplantation: 26.6% vs 31.9%; P 50 years; range, 0.36%–2.22%). For recipients aged >50 years, the 5-year cumulative incidence was higher for colorectal cancer (range, 0.33%–1.94%) than for the general population at the recommended screening age (aged 50 years: range, 0.25%–0.33%). For recipients aged >50 years, the 5-year cumulative incidence was high for lung cancer among thoracic organ recipients (range, 1.16%–3.87%) and for kidney cancer among kidney recipients (range, 0.53%–0.84%). The 5-year cumulative incidence for prostate cancer and breast cancer was similar or lower in transplantation recipients than at the recommended ages of screening in the general population. CONCLUSIONS Subgroups of transplantation recipients have a high absolute risk

  8. A study of cumulative fatigue damage in AISI 4130 steel

    Science.gov (United States)

    Jeelani, S.; Musial, M.

    1986-01-01

    Experimental data were obtained using AISI 4130 steel under stress ratios of -1 and 0. A study of cumulative fatigue damage using Miner's and Kramer's equations for stress ratios of -1 and 0 for low-high, low-high-mixed, high-low, and high-low-mixed stress sequences has revealed that there is a close agreement between the theoretical and experimental values of fatigue damage and fatigue life. Kramer's equation predicts less conservative and more realistic cumulative fatigue damage than the popularly used Miner's rule does.

  9. A Plug-in Hybrid Consumer Choice Model with Detailed Market Segmentation

    Energy Technology Data Exchange (ETDEWEB)

    Lin, Zhenhong [ORNL; Greene, David L [ORNL

    2010-01-01

    This paper describes a consumer choice model for projecting U.S. demand for plug-in hybrid electric vehicles (PHEV) in competition among 13 light-duty vehicle technologies over the period 2005-2050. New car buyers are disaggregated by region, residential area, attitude toward technology risk, vehicle usage intensity, home parking and work recharging. The nested multinomial logit (NMNL) model of vehicle choice incorporates daily vehicle usage distributions, refueling and recharging availability, technology learning by doing, and diversity of choice among makes and models. Illustrative results are presented for a Base Case, calibrated to the Annual Energy Outlook (AEO) 2009 Reference Updated Case, and an optimistic technology scenario reflecting achievement of U.S. Department of Energy s (DOE s) FreedomCAR goals. PHEV market success is highly dependent on the degree of technological progress assumed. PHEV sales reach one million in 2037 in the Base Case but in 2020 in the FreedomCARGoals Case. In the FreedomCARGoals Case, PHEV cumulative sales reach 1.5 million by 2015. Together with efficiency improvements in other technologies, petroleum use in 2050 is reduced by about 45% from the 2005 level. After technological progress, PHEV s market success appears to be most sensitive to recharging availability, consumers attitudes toward novel echnologies, and vehicle usage intensity. Successful market penetration of PHEVs helps bring down battery costs for electric vehicles (EVs), resulting in a significant EV market share after 2040.

  10. Cumulative Risk and Adolescent's Internalizing and Externalizing Problems: The Mediating Roles of Maternal Responsiveness and Self-Regulation

    Science.gov (United States)

    Doan, Stacey N.; Fuller-Rowell, Thomas E.; Evans, Gary W.

    2012-01-01

    The purpose of the present study was to examine longitudinal associations among maternal responsiveness, self-regulation, and behavioral adjustment in adolescents. The authors used structural equation modeling to test a model that demonstrates that the effects of early cumulative risk on behavioral problems is mediated by maternal responsiveness…

  11. Cumulative effects of fecal contamination from combined sewer overflows: Management for source water protection.

    Science.gov (United States)

    Jalliffier-Verne, Isabelle; Heniche, Mourad; Madoux-Humery, Anne-Sophie; Galarneau, Martine; Servais, Pierre; Prévost, Michèle; Dorner, Sarah

    2016-06-01

    The quality of a drinking water source depends largely on upstream contaminant discharges. Sewer overflows can have a large influence on downstream drinking water intakes as they discharge untreated or partially treated wastewaters that may be contaminated with pathogens. This study focuses on the quantification of Escherichia coli discharges from combined sewer overflows (CSOs) and the dispersion and diffusion in receiving waters in order to prioritize actions for source water protection. E. coli concentrations from CSOs were estimated from monitoring data at a series of overflow structures and then applied to the 42 active overflow structures between 2009 and 2012 using a simple relationship based upon the population within the drainage network. From these estimates, a transport-dispersion model was calibrated with data from a monitoring program from both overflow structures and downstream drinking water intakes. The model was validated with 15 extreme events such as a large number of overflows (n > 8) or high concentrations at drinking water intakes. Model results demonstrated the importance of the cumulative effects of CSOs on the degradation of water quality downstream. However, permits are typically issued on a discharge point basis and do not consider cumulative effects. Source water protection plans must consider the cumulative effects of discharges and their concentrations because the simultaneous discharge of multiple overflows can lead to elevated E. coli concentrations at a drinking water intake. In addition, some CSOs have a disproportionate impact on peak concentrations at drinking water intakes. As such, it is recommended that the management of CSOs move away from frequency based permitting at the discharge point to focus on the development of comprehensive strategies to reduce cumulative and peak discharges from CSOs upstream of drinking water intakes.

  12. Cumulative Effects of Barriers on the Movements of Forest Birds

    Directory of Open Access Journals (Sweden)

    Marc Bélisle

    2002-01-01

    Full Text Available Although there is a consensus of opinion that habitat fragmentation has deleterious effects on animal populations, primarily by inhibiting dispersal among remaining patches, there have been few explicit demonstrations of the ways by which degraded habitats actually constrain individual movement. Two impediments are primarily responsible for this paucity: it is difficult to separate the effects of habitat fragmentation (configuration from habitat loss (composition, and conventional measures of fragmented habitats are assumed to be, but probably are not, isotropic. We addressed these limitations by standardizing differences in forest cover in a clearly anisotropic configuration of habitat fragmentation by conducting a homing experiment with three species of forest birds in the Bow Valley of Banff National Park, Canada. Birds were translocated (1.2-3.5  km either parallel or perpendicular to four/five parallel barriers that are assumed to impede the cross-valley travel of forest-dependent animals. Taken together, individuals exhibited longer return times when they were translocated across these barriers, but differences among species suggest a more complex interpretation. A long-distance migrant (Yellow-rumped Warbler, Dendroica coronata behaved as predicted, but a short-distance migrant (Golden-crowned Kinglet, Regulus satrapa was indifferent to barrier configuration. A resident (Red-breasted Nuthatch, Sitta canadensis exhibited longer return times when it was translocated parallel to the barriers. Our results suggest that an anisotropic arrangement of small, open areas in fragmented landscapes can have a cumulative barrier effect on the movement of forest animals, but that both modelers and managers will have to acknowledge potentially counterintuitive differences among species to predict the effect that these may have on individual movement and, ultimately, dispersal.

  13. Cumulative childhood trauma and psychological maladjustment of sexually abused children in Korea: mediating effects of emotion regulation.

    Science.gov (United States)

    Choi, Ji Young; Oh, Kyung Ja

    2014-02-01

    The purpose of the present study was to identify the mediating effects of emotion regulation on the association between cumulative childhood trauma and behavior problems in sexually abused children in Korea, using structural equation modeling (SEM). Data were collected on 171 children (ages 6-13 years) referred to a public counseling center for sexual abuse in Seoul, Korea. Cumulative childhood traumas were defined on the basis of number of traumas (physical abuse, witnessing domestic violence, neglect, traumatic separation from parent, and sexual abuse) and the severity and duration of traumas. Children were evaluated by their parents on emotion regulation using the Emotion Regulation Checklist and internalizing and externalizing behavior problems using the Korean-Child Behavior Checklist. SEM analyses confirmed the complete mediation model, in which emotion dysregulation fully mediates the relationship between cumulative childhood traumas and internalizing/externalizing behavior problems. These findings indicate that emotion regulation is an important mechanism that can explain the negative effects of cumulative childhood traumas and that there is a need to focus on emotion regulation in sexually abused children exposed to cumulative trauma. Copyright © 2013 Elsevier Ltd. All rights reserved.

  14. Ductility and Strength Reduction Factors for Degrading Structures Considering Cumulative Damage

    Directory of Open Access Journals (Sweden)

    Edén Bojórquez

    2014-01-01

    Full Text Available The effect of cumulative damage on the strength requirements of degrading structures is assessed through the evaluation of the target ductility and corresponding strength reduction factors of simple degrading structures. While the reduction on ductility is established through the use of Park and Ang index, the suggestions given by Bojórquez and Rivera are used to model the degradation of the structural properties of the simple systems. Target ductilities and their corresponding reduced strength reduction factors are established for five sets of ground motions; most of them are recorded in California. The results given in this paper provide insight into all relevant parameters that should be considered during seismic design of earthquake-resistant structures. Finally, some recommendations to evaluate the effect of cumulative damage on seismic design are suggested.

  15. Cumulative (DisAdvantage and the Matthew Effect in Life-Course Analysis.

    Directory of Open Access Journals (Sweden)

    Miia Bask

    Full Text Available To foster a deeper understanding of the mechanisms behind inequality in society, it is crucial to work with well-defined concepts associated with such mechanisms. The aim of this paper is to define cumulative (disadvantage and the Matthew effect. We argue that cumulative (disadvantage is an intra-individual micro-level phenomenon, that the Matthew effect is an inter-individual macro-level phenomenon and that an appropriate measure of the Matthew effect focuses on the mechanism or dynamic process that generates inequality. The Matthew mechanism is, therefore, a better name for the phenomenon, where we provide a novel measure of the mechanism, including a proof-of-principle analysis using disposable personal income data. Finally, because socio-economic theory should be able to explain cumulative (disadvantage and the Matthew mechanism when they are detected in data, we discuss the types of models that may explain the phenomena. We argue that interactions-based models in the literature traditions of analytical sociology and statistical mechanics serve this purpose.

  16. A Prototypical Model for Estimating High Tech Navy Recruiting Markets

    Science.gov (United States)

    1991-12-01

    Probability, Logit, and Probit Models, New York, New York 1990, p. 73. 37 Gujarati , D., ibid, p. 500. 31 V. MODELS ESTIMATION A. MODEL I ESTIMATION OF...Company, New York, N.Y., 1990. Gujarati , Damodar N., Basic Econometrics, Second Edition, McGraw-Hill Book Company, New York, N.Y., 1988. Jehn, Christopher

  17. Mode choice model parameters estimation

    OpenAIRE

    Strnad, Irena

    2010-01-01

    The present work focuses on parameter estimation of two mode choice models: multinomial logit and EVA 2 model, where four different modes and five different trip purposes are taken into account. Mode choice model discusses the behavioral aspect of mode choice making and enables its application to a traffic model. Mode choice model includes mode choice affecting trip factors by using each mode and their relative importance to choice made. When trip factor values are known, it...

  18. RECURSIVE CLASSIFICATION OF MQAM SIGNALS BASED ON HIGHER ORDER CUMULANTS

    Institute of Scientific and Technical Information of China (English)

    Chen Weidong; Yang Shaoquan

    2002-01-01

    A new feature based on higher order cumulants is proposed for classification of MQAM signals. Theoretical analysis justify that the new feature is invariant with respect to translation (shift), scale and rotation transform of signal constellations, and can suppress color or white additive Gaussian noise. Computer simulation shows that the proposed recursive orderreduction based classification algorithm can classify MQAM signals with any order.

  19. Cumulative psychosocial stress, coping resources, and preterm birth.

    Science.gov (United States)

    McDonald, Sheila W; Kingston, Dawn; Bayrampour, Hamideh; Dolan, Siobhan M; Tough, Suzanne C

    2014-12-01

    Preterm birth constitutes a significant international public health issue, with implications for child and family well-being. High levels of psychosocial stress and negative affect before and during pregnancy are contributing factors to shortened gestation and preterm birth. We developed a cumulative psychosocial stress variable and examined its association with early delivery controlling for known preterm birth risk factors and confounding environmental variables. We further examined this association among subgroups of women with different levels of coping resources. Utilizing the All Our Babies (AOB) study, an ongoing prospective pregnancy cohort study in Alberta, Canada (n = 3,021), multinomial logistic regression was adopted to examine the independent effect of cumulative psychosocial stress and preterm birth subgroups compared to term births. Stratified analyses according to categories of perceived social support and optimism were undertaken to examine differential effects among subgroups of women. Cumulative psychosocial stress was a statistically significant risk factor for late preterm birth (OR = 1.73; 95 % CI = 1.07, 2.81), but not for early preterm birth (OR = 2.44; 95 % CI = 0.95, 6.32), controlling for income, history of preterm birth, pregnancy complications, reproductive history, and smoking in pregnancy. Stratified analyses showed that cumulative psychosocial stress was a significant risk factor for preterm birth at psychosocial stress on the risk for early delivery.

  20. Is learning in problem-based learning cumulative?

    NARCIS (Netherlands)

    E.H.J. Yew (Elaine); E. Chng (Esther); H.G. Schmidt (Henk)

    2011-01-01

    textabstractProblem-based learning (PBL) is generally organized in three phases, involving collaborative and self-directed learning processes. The hypothesis tested here is whether learning in the different phases of PBL is cumulative, with learning in each phase depending on that of the previous ph

  1. Cumulative assessment : Strategic choices to influence students' study effort

    NARCIS (Netherlands)

    Kerdijk, Wouter; Tio, Rene A.; Mulder, B. Florentine; Cohen-Schotanus, Janke

    2013-01-01

    Background: It has been asserted that assessment can and should be used to drive students' learning. In the current study, we present a cumulative assessment program in which test planning, repeated testing and compensation are combined in order to influence study effort. The program is aimed at hel

  2. Repeated mild injury causes cumulative damage to hippocampal cells

    NARCIS (Netherlands)

    E.J. Matser (Amy); C.I. de Zeeuw (Chris); J.T. Weber (John)

    2002-01-01

    textabstractAn interesting hypothesis in the study of neurotrauma is that repeated traumatic brain injury may result in cumulative damage to cells of the brain. However, post-injury sequelae are difficult to address at the cellular level in vivo. Therefore, it is necessary to compl

  3. The effects of cumulative practice on mathematics problem solving.

    Science.gov (United States)

    Mayfield, Kristin H; Chase, Philip N

    2002-01-01

    This study compared three different methods of teaching five basic algebra rules to college students. All methods used the same procedures to teach the rules and included four 50-question review sessions interspersed among the training of the individual rules. The differences among methods involved the kinds of practice provided during the four review sessions. Participants who received cumulative practice answered 50 questions covering a mix of the rules learned prior to each review session. Participants who received a simple review answered 50 questions on one previously trained rule. Participants who received extra practice answered 50 extra questions on the rule they had just learned. Tests administered after each review included new questions for applying each rule (application items) and problems that required novel combinations of the rules (problem-solving items). On the final test, the cumulative group outscored the other groups on application and problem-solving items. In addition, the cumulative group solved the problem-solving items significantly faster than the other groups. These results suggest that cumulative practice of component skills is an effective method of training problem solving.

  4. Cumulative index 1981-1985, Volumes 138-157.

    Science.gov (United States)

    1985-01-01

    This cumulative index also includes listings of all major papers from the American Journal of Neuroradiology, American Journal of Roentgenology, Clinics in Diagnostic Ultrasound, Journal of Computer Assisted Tomography, Journal of Ultrasound in Medicine, RadioGraphics, Radiologic Clinics of North America, Seminars in Nuclear Medicine, Seminars in Roentgenology, and Seminars in Ultrasound, CT and MR.

  5. Cumulative index 1981-1985, Volumes 138-157

    Energy Technology Data Exchange (ETDEWEB)

    1985-01-01

    This cumulative index also includes listings of all major papers from the American Journal of Neuroradiology, American Journal of Roentgenology, Clinics in Diagnostic Ultrasound, Journal of Computer Assisted Tomography, Journal of Ultrasound in Medicine, RadioGraphics, Radiologic Clinics of North America, Seminars in Nuclear Medicine, Seminars in Roentgenology, and Seminars in Ultrasound, CT and MR.

  6. CUMULANTS OF STOCHASTIC RESPONSE FOR A CLASS OF SPECIAL NONHOLONOMIC SYSTEMS

    Institute of Scientific and Technical Information of China (English)

    SHANG MEI; ZHANG YI

    2001-01-01

    This paper studies the response cumulants for a kind of special nonholonomic systems under non-Gaussian, delta- correlated excitations. We present a new methodology for formulating the equations governing the evolution of the response cumulants of the stochastic dynamic systems. The response cumulant differential equations (CDEs) derived can be used to calculate the response cumulants for both linear and nonlinear systems. One example is given to illustrate how to use the CDEs for calculating response cumulants.

  7. Behavior and finite-size effects of the sixth order cumulant in the three-dimensional Ising universality class

    CERN Document Server

    Pan, Xue; Wu, Yuan-Fang

    2016-01-01

    The high-order cumulants of conserved charges are suggested to be sensitive observables to search for the critical point of Quantum Chromodynamics (QCD). The order has been calculated to the sixth one at experiments. The corresponding theoretical studies on the sixth order cumulant are necessary. Based on the universality of the critical behavior, we study the temperature dependence of the sixth order cumulant of the order parameter using the parametric representation of the three-dimensional Ising model, which is expected to be in the same universality class with QCD. The density plot of the sign of the sixth order cumulant is shown on the temperature and external magnetic field plane. We found that when the critical point is approached from the crossover side, the sixth order cumulant is negative. Qualitatively, the trend is similar to the result of Monte Carlo simulation on a finite-size system. Quantitatively, the temperature of the sign change is different. Through Monte Carlo simulation of the Ising mod...

  8. Cumulative Doses of T-Cell Depleting Antibody and Cancer Risk after Kidney Transplantation.

    Directory of Open Access Journals (Sweden)

    Jenny H C Chen

    Full Text Available T-cell depleting antibody is associated with an increased risk of cancer after kidney transplantation, but a dose-dependent relationship has not been established. This study aimed to determine the association between cumulative doses of T-cell depleting antibody and the risk of cancer after kidney transplantation. Using data from the Australian and New Zealand Dialysis and Transplant Registry between 1997-2012, we assessed the risk of incident cancer and cumulative doses of T-cell depleting antibody using adjusted Cox regression models. Of the 503 kidney transplant recipients with 2835 person-years of follow-up, 276 (55%, 209 (41% and 18 (4% patients received T-cell depleting antibody for induction, rejection or induction and rejection respectively. The overall cancer incidence rate was 1,118 cancers per 100,000 patient-years, with 975, 1093 and 1377 cancers per 100,000 patient-years among those who had received 1-5 doses, 6-10 doses and >10 doses, respectively. There was no association between cumulative doses of T cell depleting antibody and risk of incident cancer (1-5: referent, 6-10: adjusted hazard ratio (HR 1.19, 95%CI 0.48-2.95, >10: HR 1.42, 95%CI 0.50-4.02, p = 0.801. This lack of association is contradictory to our hypothesis and is likely attributed to the low event rates resulting in insufficient power to detect significant differences.

  9. Analysis of grain boundary dynamics using event detection and cumulative averaging

    Energy Technology Data Exchange (ETDEWEB)

    Gautam, A.; Ophus, C. [National Center for Electron Microscopy, LBNL, Berkeley, CA 94720 (United States); Lançon, F. [Laboratoire de Simulation Atomistique L-Sim, SP2M, INAC, CEA, 38054 Grenoble (France); Denes, P. [National Center for Electron Microscopy, LBNL, Berkeley, CA 94720 (United States); Dahmen, U., E-mail: udahmen@lbl.gov [National Center for Electron Microscopy, LBNL, Berkeley, CA 94720 (United States)

    2015-04-15

    To analyze extended time series of high resolution images, we have employed automated frame-by-frame comparisons that are able to detect dynamic changes in the structure of a grain boundary in Au. Using cumulative averaging of images between events allowed high resolution measurements of the atomic relaxation in the interface with sufficient accuracy for comparison with atomistic models. Cumulative averaging was also used to observe the structural rearrangement of atomic columns at a moving step in the grain boundary. The technique of analyzing changing features in high resolution images by averaging between incidents can be used to deconvolute stochastic events that occur at random intervals and on time scales well beyond that accessible to single-shot imaging. - Highlights: • We have observed dynamic structural changes in extended time series of atomic resolution images. • Application of edge detection in the time domain isolates stochastic events in dynamic observations. • Splitting time series at stochastic events highlights changes in local atomic structure. • Cumulative averaging between events generates precise atomic resolution structural images.

  10. Non-Gaussian wave packet dynamics in anharmonic potential: Cumulant expansion treatment

    Science.gov (United States)

    Toutounji, Mohamad

    2015-03-01

    This manuscript utilizes cumulant expansion as an alternative algebraic approach to evaluating integrals and solving a system of nonlinear differential equations for probing anharmonic dynamics in condensed phase systems using Morse oscillator. These integrals and differential equations become harder to solve as the anharmonicity of the system goes beyond that of Morse oscillator description. This algebraic approach becomes critically important in case of Morse oscillator as it tends to exhibit divergent dynamics and numerical uncertainties at low temperatures. The autocorrelation function is calculated algebraically and compared to the exact one for they match perfectly. It is also compared to the approximate autocorrelation function using the differential equations technique reported in Toutounji (2014) for weak and strong electron-phonon coupling cases. It is found that the present cumulant method is more efficient, and easier to use, than the exact expression. Deviation between the approximate autocorrelation function and the exact autocorrelation function starts to arise as the electron-phonon coupling strength increases. The autocorrelation function obtained using cumulants identically matches the exact autocorrelation function, thereby surpassing the approach presented in Toutounji (2014). The advantage of the present methodology is its applicability to various types of electron-phonon coupling cases. Additionally, the herein approach only uses algebraic techniques, thereby avoiding both the divergence integral and solving a set of linear first- and second-order partial differential equations as was done in previous work. Model calculations are presented to demonstrate the accuracy of the herein work.

  11. Single-word predictions of upcoming language during comprehension: Evidence from the cumulative semantic interference task.

    Science.gov (United States)

    Kleinman, Daniel; Runnqvist, Elin; Ferreira, Victor S

    2015-06-01

    Comprehenders predict upcoming speech and text on the basis of linguistic input. How many predictions do comprehenders make for an upcoming word? If a listener strongly expects to hear the word "sock", is the word "shirt" partially expected as well, is it actively inhibited, or is it ignored? The present research addressed these questions by measuring the "downstream" effects of prediction on the processing of subsequently presented stimuli using the cumulative semantic interference paradigm. In three experiments, subjects named pictures (sock) that were presented either in isolation or after strongly constraining sentence frames ("After doing his laundry, Mark always seemed to be missing one…"). Naming sock slowed the subsequent naming of the picture shirt - the standard cumulative semantic interference effect. However, although picture naming was much faster after sentence frames, the interference effect was not modulated by the context (bare vs. sentence) in which either picture was presented. According to the only model of cumulative semantic interference that can account for such a pattern of data, this indicates that comprehenders pre-activated and maintained the pre-activation of best sentence completions (sock) but did not maintain the pre-activation of less likely completions (shirt). Thus, comprehenders predicted only the most probable completion for each sentence.

  12. Covariate adjustment of cumulative incidence functions for competing risks data using inverse probability of treatment weighting.

    Science.gov (United States)

    Neumann, Anke; Billionnet, Cécile

    2016-06-01

    In observational studies without random assignment of the treatment, the unadjusted comparison between treatment groups may be misleading due to confounding. One method to adjust for measured confounders is inverse probability of treatment weighting. This method can also be used in the analysis of time to event data with competing risks. Competing risks arise if for some individuals the event of interest is precluded by a different type of event occurring before, or if only the earliest of several times to event, corresponding to different event types, is observed or is of interest. In the presence of competing risks, time to event data are often characterized by cumulative incidence functions, one for each event type of interest. We describe the use of inverse probability of treatment weighting to create adjusted cumulative incidence functions. This method is equivalent to direct standardization when the weight model is saturated. No assumptions about the form of the cumulative incidence functions are required. The method allows studying associations between treatment and the different types of event under study, while focusing on the earliest event only. We present a SAS macro implementing this method and we provide a worked example.

  13. INTERNAL AND EXTERNAL DETERMINANTS OF INNOVATION CAPABILITY IN PORTUGUESE SERVICES FIRMS: A LOGIT APPROACH DETERMINANTES INTERNOS Y EXTERNOS DE LA CAPACIDAD DE INNOVAR DE LAS EMPRESAS DE SERVICIOS PORTUGUESAS: MODELO LOGIT DETERMINANTES INTERNOS E EXTERNOS DA CAPACIDADE INOVADORA DAS EMPRESAS DE SERVIÇOS PORTUGUESAS: MODELO LOGIT

    Directory of Open Access Journals (Sweden)

    Maria José Silva

    2013-01-01

    Full Text Available This research examined the degree of importance of factors internal and external determinants of innovative company, under the Portuguese service companies. Based on the literature has built up a conceptual model and hypotheses were formulated several research have been tested empirically, using the secondary data provided by the Center for Science  and Higher Education (OCES, belonging to the 4th Community Innovation Survey (CIS 4, supervised by EUROSTAT. The method was to use logistic regression. According to the results, as greater financial investment in internal  research activities and development in acquisition of external knowledge and marketing activities in the greater propensity of firms to innovate at the level of services. The results allow a joint analysis of the factors that promote and restrict the innovative capacity of service companies, which identify the main determinants and improve the knowledge on innovation in services. The contribution of the results refers to the identification of which factors are really important in stimulating innovation in service firms.Esta investigación analizó el grado de importancia de los factores internos y externos determinantes de la capacidad innovadora empresarial en el ámbito de las empresas de servicios portuguesas. Con base en la literatura se construyó un  modelo conceptual y se formularon varias hipótesis de investigación que fueron testadas empíricamente, utilizándose los datos secundarios facultados por el “Observatorio de Ciencia y de la Enseñanza Superior” (OCES, pertenecientes a la 4ª Indagación Comunitaria a la Innovación (CIS 4, bajo la supervisión de EUROSTAT. El método utilizado fue la regresión logística. De acuerdo con los resultados obtenidos, cuanto mayores sean las inversiones financieras en actividades internas de investigación y desarrollo, en adquisición de conocimientos externos y en actividades de marketing, mayor es la

  14. Evaluation of cumulative PCB exposure estimated by a job exposure matrix versus PCB serum concentrations.

    Science.gov (United States)

    Hopf, Nancy B; Ruder, Avima M; Succop, Paul; Waters, Martha A

    2014-05-01

    Although polychlorinated biphenyls (PCBs) have been banned in many countries for more than three decades, exposures to PCBs continue to be of concern due to their long half-lives and carcinogenic effects. In National Institute for Occupational Safety and Health studies, we are using semiquantitative plant-specific job exposure matrices (JEMs) to estimate historical PCB exposures for workers (n = 24,865) exposed to PCBs from 1938 to 1978 at three capacitor manufacturing plants. A subcohort of these workers (n = 410) employed in two of these plants had serum PCB concentrations measured at up to four times between 1976 and 1989. Our objectives were to evaluate the strength of association between an individual worker's measured serum PCB levels and the same worker's cumulative exposure estimated through 1977 with the (1) JEM and (2) duration of employment, and to calculate the explained variance the JEM provides for serum PCB levels using (3) simple linear regression. Consistent strong and statistically significant associations were observed between the cumulative exposures estimated with the JEM and serum PCB concentrations for all years. The strength of association between duration of employment and serum PCBs was good for highly chlorinated (Aroclor 1254/HPCB) but not less chlorinated (Aroclor 1242/LPCB) PCBs. In the simple regression models, cumulative occupational exposure estimated using the JEMs explained 14-24% of the variance of the Aroclor 1242/LPCB and 22-39% for Aroclor 1254/HPCB serum concentrations. We regard the cumulative exposure estimated with the JEM as a better estimate of PCB body burdens than serum concentrations quantified as Aroclor 1242/LPCB and Aroclor 1254/HPCB.

  15. A prospective study of cumulative job stress in relation to mental health

    Science.gov (United States)

    Godin, Isabelle; Kittel, France; Coppieters, Yves; Siegrist, Johannes

    2005-01-01

    Background This study tests associations between psychosocial stress at work measured by the effort-reward imbalance model in a dynamic perspective, and multiple indicators of poor mental health, in a prospective design. Methods 1986 male and female employees from four Belgian enterprises were followed-up over one year within the framework of the Somstress study. Based on two consecutive measurements, an index of cumulative job stress was constructed and its associations with five indicators of mental health were studied, excluding caseness at entry (for depression, anxiety, somatisation, chronic fatigue and psychotropic drug consumption respectively). Taking into account the longitudinal design, four categories of job stress are defined: 1) employees free from stress at both measures, 2) job stress present at first measure but not at the second one, 3) recent onset of job stress as evidenced by second measure 4) workers exposed to stress at both measures. Multivariate logistic regression with appropriate adjustments was applied. Results In bivariate analysis, a clear graded association of cumulative job stress with all five mental health indicators is observed, both in men and women. In multivariate logistic regression analysis, recent onset of stress is strongly associated with poor mental health among men (odds ratios ranging from 1.8 to 4.6), while cumulative stress shows strongest effects on mental health in women (odds ratios ranging from 1.4 to 7.1). Conclusion Cumulative experience and recent onset of job stress in terms of high effort spent and low reward received is associated with elevated risk of all five indicators of poor mental health at follow-up in a large cohort of employees. PMID:15958170

  16. A prospective study of cumulative job stress in relation to mental health

    Directory of Open Access Journals (Sweden)

    Coppieters Yves

    2005-06-01

    Full Text Available Abstract Background This study tests associations between psychosocial stress at work measured by the effort-reward imbalance model in a dynamic perspective, and multiple indicators of poor mental health, in a prospective design. Methods 1986 male and female employees from four Belgian enterprises were followed-up over one year within the framework of the Somstress study. Based on two consecutive measurements, an index of cumulative job stress was constructed and its associations with five indicators of mental health were studied, excluding caseness at entry (for depression, anxiety, somatisation, chronic fatigue and psychotropic drug consumption respectively. Taking into account the longitudinal design, four categories of job stress are defined: 1 employees free from stress at both measures, 2 job stress present at first measure but not at the second one, 3 recent onset of job stress as evidenced by second measure 4 workers exposed to stress at both measures. Multivariate logistic regression with appropriate adjustments was applied. Results In bivariate analysis, a clear graded association of cumulative job stress with all five mental health indicators is observed, both in men and women. In multivariate logistic regression analysis, recent onset of stress is strongly associated with poor mental health among men (odds ratios ranging from 1.8 to 4.6, while cumulative stress shows strongest effects on mental health in women (odds ratios ranging from 1.4 to 7.1. Conclusion Cumulative experience and recent onset of job stress in terms of high effort spent and low reward received is associated with elevated risk of all five indicators of poor mental health at follow-up in a large cohort of employees.

  17. 基于累积 Logistic 模型的居民通货膨胀异质性感受的因素研究%Empirical Analysis of Factors Leading to the Heterogeneity of Inflation Perceptions Based on the Cumulative Logistic Model

    Institute of Scientific and Technical Information of China (English)

    段进; 段妍; 朱静平

    2015-01-01

    通过调查问卷获取居民的通货膨胀感受及相关的个人特征等数据,运用累积 Logistic 模型,从心理层面和外部信息层面考量影响居民通货膨胀感受异质性的因素。结果表明,收入满意程度、食品价格、房租价格以及促销手段等是导致我国居民通胀感受异质性的主要因素。鉴此,政府应该提高收入满意度、稳定物价以及调节房价,以期降低通货膨胀感受的异质性。%Data related to inflation perceptions and personal characteristics are acquired through a questionnaire.By using the idea of cumulative logistic model as the empirical methodo-logical approach,this paper empirically analyzes the factors that lead to the heterogeneity of infla-tion perceptions through the psychological and external information aspects of the formation of inflation perceptions.The results show that income satisfaction,food price,rent and marketing are the factors with significant effects on the heterogeneity of inflation perceptions.The govern-ment should enhance income satisfaction,stabilize prices and regulate houses price and rent in or-der to decrease the heterogeneity of inflation perception.

  18. Expansion of the Glauber equation of motion in terms of cumulants powers. Statistical properties of the Glauber equation of motion

    Science.gov (United States)

    Bury, T.

    2012-01-01

    We present an expansion of the Glauber equation of motion in terms of cumulants of the effective fields. We show that we recover a part of the fluctuations with a simple third order expansion. We illustrate the method with an application to the 2D square lattice Ising model with nearest neighbors. For the special case of perturbed non gaussian effective fields, we show that only the first cumulants are significative. Furthermore it can be shown that the resulting distribution is closer to the normal distribution than the unperturbed fields one. It leads to the conclusion that we can consistently truncate the expansion of the exact Glauber equation of motion.

  19. Do Stochastic Traffic Assignment Models Consider Differences in Road Users Utility Functions?

    DEFF Research Database (Denmark)

    Nielsen, Otto Anker

    1996-01-01

    The early stochastic traffic assignment models (e.g. Dial, 1971) build on the assump-tion that different routes are independent (the logit-model concept). Thus, the models gave severe problems in networks with overlapping routes. Daganzo & Sheffi (1977) suggested to use probit based models...

  20. Experience of cumulative effects assessment in the UK

    Directory of Open Access Journals (Sweden)

    Piper Jake

    2004-01-01

    Full Text Available Cumulative effects assessment (CEA is a development of environmental impact assessment which attempts to take into account the wider picture of what impacts may affect the environment as a result of either multiple or linear projects, or development plans. CEA is seen as a further valuable tool in promoting sustainable development. The broader canvas upon which the assessment is made leads to a suite of issues such as complexity in methods and assessment of significance, the desirability of co-operation between developers and other parties, new ways of addressing mitigation and monitoring. After outlining the legislative position and the process of CEA, this paper looks at three cases studies in the UK where cumulative assessment has been carried out - the cases concern wind farms, major infrastructure and off-shore developments.

  1. Petrogenesis of the nakhlite meteorites - Evidence from cumulate mineral zoning

    Science.gov (United States)

    Harvey, Ralph P.; Mcsween, Harry Y., Jr.

    1992-01-01

    Attention is given to a simple igneous petrogenesis for the meteorite Nakhla, which was previously called into question because Mg/Fe ratios in olivine indicate substantial disequilibrium between the predominant cumulus minerals (olivine and augite). Comparative analyses of simulated diffusive zoning and the observed cumulus mineral zoning for all three nakhlites (Nakhla, Governador Valadares, and Lafayette) show that their current compositions do not necessarily reflect parental magma compositions. Diffusion has altered primary cumulus compositions to varying degrees, Nakhla being the least affected, and Lafayette being almost completely reequilibrated. Since mineral zoning in each meteorite is strongly concentric around mesostasis areas, it is inferred that reaction with intercumulus liquid has controlled the observed zoning. It is argued that the nakhlites appear to be a series of relatively simple cumulate rocks which have undergone various amounts of late-magmatic and subsolidus diffusion, possibly reflecting their relative positions in a cooling cumulate pile.

  2. Determination of radionuclides and pathways contributing to cumulative dose

    Energy Technology Data Exchange (ETDEWEB)

    Napier, B.A.

    1992-12-01

    A series of scoping calculations has been undertaken to evaluate the absolute and relative contributions of different radionuclides and exposure pathways to doses that may have been received by individuals living in the vicinity of the Hanford Site. This scoping calculation (Calculation 004) examined the contributions of numerous radionuclides to cumulative dose via environmental exposures and accumulation in foods. Addressed in this calculation were the contributions to organ and effective dose of infants and adults from (1) air submersion and groundshine external dose, (2) inhalation, (3) ingestion of soil by humans, (4) ingestion of leafy vegetables, (5) ingestion of other vegetables and fruits, (6) ingestion of meat, (7) ingestion of eggs, and (8) ingestion of cows' milk from Feeding Regime 1, as described in calculation 002. This calculation specifically addresses cumulative radiation doses to infants and adults resulting from releases occurring over the period 1945 through 1972.

  3. Cumulative impacts of oil fields on northern alaskan landscapes.

    Science.gov (United States)

    Walker, D A; Webber, P J; Binnian, E F; Everett, K R; Lederer, N D; Nordstrand, E A; Walker, M D

    1987-11-06

    Proposed further developments on Alaska's Arctic Coastal Plain raise questions about cumulative effects on arctic tundra ecosystems of development of multiple large oil fields. Maps of historical changes to the Prudhoe Bay Oil Field show indirect impacts can lag behind planned developments by many years and the total area eventually disturbed can greatly exceed the planned area of construction. For example, in the wettest parts of the oil field (flat thaw-lake plains), flooding and thermokarst covered more than twice the area directly affected by roads and other construction activities. Protecting critical wildlife habitat is the central issue for cumulative impact analysis in northern Alaska. Comprehensive landscape planning with the use of geographic information system technology and detailed geobotanical maps can help identify and protect areas of high wildlife use.

  4. Cumulants and Correlation Functions vs the QCD phase diagram

    CERN Document Server

    Bzdak, Adam; Strodthoff, Nils

    2016-01-01

    In this note we discuss the relation of particle number cumulants and correlation functions related to them. It is argued that measuring couplings of the genuine correlation functions could provide cleaner information on possible non-trivial dynamics in heavy-ion collisions. We extract integrated multi-particle correlation functions from the presently available experimental data on proton cumulants. We find that the STAR data contain significant four-particle correlations, at least at the lower energies, with indication of changing dynamics in central collisions. We also find that these correlations are rather long-ranged in rapidity. Finally based on the signs of genuine correlation functions we provide exclusion plots for the QCD phase diagram.

  5. Cumulants of heat transfer across nonlinear quantum systems

    Science.gov (United States)

    Li, Huanan; Agarwalla, Bijay Kumar; Li, Baowen; Wang, Jian-Sheng

    2013-12-01

    We consider thermal conduction across a general nonlinear phononic junction. Based on two-time observation protocol and the nonequilibrium Green's function method, heat transfer in steady-state regimes is studied, and practical formulas for the calculation of the cumulant generating function are obtained. As an application, the general formalism is used to study anharmonic effects on fluctuation of steady-state heat transfer across a single-site junction with a quartic nonlinear on-site pinning potential. An explicit nonlinear modification to the cumulant generating function exact up to the first order is given, in which the Gallavotti-Cohen fluctuation symmetry is found still valid. Numerically a self-consistent procedure is introduced, which works well for strong nonlinearity.

  6. Heavy metal cumulation in crops after the sewage sludge application

    Directory of Open Access Journals (Sweden)

    Gondová Andrea

    1998-12-01

    Full Text Available During 1995 - 1996 the crops samples after the sewage sludge application were collected. The heavy metals cumulation in investigated crops from Bardejov increased in order: Zn > Cu > Pb > Ni > Cr > Cd and Banská Bystrica : Zn > Cu > Cr > Ni > Pb > Cd. Heavy metals contents after the sewage sludge application were increased in comparison with the highest admissible concentration in eatable part of crops. The sewage sludge application were not recommended in soils for the growth of vegetables

  7. The cumulation of methylmercury in fish (Poecilia reticulata)

    Energy Technology Data Exchange (ETDEWEB)

    Stary, J.; Kratzer, K.; Havlik, B.; Prasilova, J.; Hanusova, J.

    1980-01-01

    Methylmercury labelled with mercury-203 was used for the investigation of the uptake and the release of methylmercury in fish. It has been found that methylmercury compounds adsorbed on fish food remain completely in fish and that they are released with the biological half-time of 110 days. The cumulation of methylmercury from water is very rapid. Equations for the calculation of the concentration of methylmercury in fish were derived and compared with the uptake of phenylmercury and inorganic mercury.

  8. Erupted cumulate fragments in rhyolites from Lipari (Aeolian Islands)

    Science.gov (United States)

    Forni, Francesca; Ellis, Ben S.; Bachmann, Olivier; Lucchi, Federico; Tranne, Claudio A.; Agostini, Samuele; Dallai, Luigi

    2015-12-01

    Over the last ~267 ky, the island of Lipari has erupted magmas ranging in compositions from basaltic andesites to rhyolites, with a notable compositional gap in the dacite field. Bulk geochemical and isotopic compositions of the volcanic succession, in conjunction with major and trace elemental compositions of minerals, indicate that the rhyolites were dominantly generated via crystal fractionation processes, with subordinate assimilation. Radiogenic (Sr, Nd, and Pb) and stable (O) isotopes independently suggest ≤30 % of crustal contamination with the majority of it occurring in mafic compositions, likely relatively deep in the system. Within the rhyolites, crystal-rich, K2O-rich enclaves are common. In contrast to previous interpretations, we suggest that these enclaves represent partial melting, remobilization and eruption of cumulate fragments left-over from rhyolite melt extraction. Cumulate melting and remobilization is supported by the presence of (1) resorbed, low-temperature minerals (biotite and sanidine), providing the potassic signature to these clasts, (2) reacted Fo-rich olivine, marking the presence of mafic recharge, (3) An38-21 plagioclase, filling the gap in feldspar composition between the andesites and the rhyolites and (4) strong enrichment in Sr and Ba in plagioclase and sanidine, suggesting crystallization from a locally enriched melt. Based on Sr-melt partitioning, the high-Sr plagioclase would require ~2300 ppm Sr in the melt, a value far in excess of Sr contents in Lipari and Vulcano magmas (50-1532 ppm) but consistent with melting of a feldspar-rich cumulate. Due to the presence of similar crystal-rich enclaves within the rhyolites from Vulcano, we propose that the eruption of remobilized cumulates associated with high-SiO2 rhyolites may be a common process at the Aeolian volcanoes, as already attested for a variety of volcanic systems around the world.

  9. [Cumulative effect of Coriolis acceleration on coronary hemodynamics].

    Science.gov (United States)

    Lapaev, E V; Bednenko, V S

    1985-01-01

    Time-course variations in coronary circulation and cardiac output were measured in 29 healthy test subjects who performed tests with a continuous cumulation of Coriolis accelerations and in 12 healthy test subjects who were exposed to Coriolis accelerations combined with acute hypoxia. Adaptive changes in coronary circulation were seen. It is recommended to monitor coronary circulation during vestibulometric tests as part of medical expertise of the flying personnel.

  10. Cumulative Risk Assessment Toolbox: Methods and Approaches for the Practitioner

    Directory of Open Access Journals (Sweden)

    Margaret M. MacDonell

    2013-01-01

    Full Text Available The historical approach to assessing health risks of environmental chemicals has been to evaluate them one at a time. In fact, we are exposed every day to a wide variety of chemicals and are increasingly aware of potential health implications. Although considerable progress has been made in the science underlying risk assessments for real-world exposures, implementation has lagged because many practitioners are unaware of methods and tools available to support these analyses. To address this issue, the US Environmental Protection Agency developed a toolbox of cumulative risk resources for contaminated sites, as part of a resource document that was published in 2007. This paper highlights information for nearly 80 resources from the toolbox and provides selected updates, with practical notes for cumulative risk applications. Resources are organized according to the main elements of the assessment process: (1 planning, scoping, and problem formulation; (2 environmental fate and transport; (3 exposure analysis extending to human factors; (4 toxicity analysis; and (5 risk and uncertainty characterization, including presentation of results. In addition to providing online access, plans for the toolbox include addressing nonchemical stressors and applications beyond contaminated sites and further strengthening resource accessibility to support evolving analyses for cumulative risk and sustainable communities.

  11. Finite Volume Cumulant Expansion in QCD-Colorless Plasma

    CERN Document Server

    Ladrem, M; Al-Full, Z; Cherif, S

    2015-01-01

    Due to the finite size effects, the localisation of the phase transition in finite systems and the determination of its order, become an extremely difficult task, even in the simplest known cases. In order to identify and locate the finite volume transition point $T_{0}(V)$ of the QCD deconfinement phase transition to a Colorless QGP, we have developed a new approach using the finite size cumulant expansion of the order parameter and the $L_{mn}$-method. The first six cumulants $C_{1,2,3,4,5,6}$ with the corresponding under-normalized ratios(skewness $\\Sigma$, kurtosis $\\kappa$ ,pentosis $\\Pi_{\\pm}$ and hexosis $\\mathcal{H}_{1,2,3}$) and three unnormalized combinations of them ($\\mathcal{O}={\\mathcal{\\sigma }^{2} \\mathcal{\\kappa } }{\\mathbf{\\Sigma }^{-1} }$, $\\mathcal{U} ={\\mathcal{\\sigma }^{-2} \\mathbf{\\Sigma }^{-1} }$, $\\mathcal{N} = \\mathcal{\\sigma }^{2} \\mathcal{\\kappa }$) are calculated and studied as functions of $(T,V)$. A new approach, unifying in a clear and consistent way the definitions of cumulant...

  12. Cumulative Risk Assessment Toolbox: Methods and Approaches for the Practitioner

    Science.gov (United States)

    MacDonell, Margaret M.; Haroun, Lynne A.; Teuschler, Linda K.; Rice, Glenn E.; Hertzberg, Richard C.; Butler, James P.; Chang, Young-Soo; Clark, Shanna L.; Johns, Alan P.; Perry, Camarie S.; Garcia, Shannon S.; Jacobi, John H.; Scofield, Marcienne A.

    2013-01-01

    The historical approach to assessing health risks of environmental chemicals has been to evaluate them one at a time. In fact, we are exposed every day to a wide variety of chemicals and are increasingly aware of potential health implications. Although considerable progress has been made in the science underlying risk assessments for real-world exposures, implementation has lagged because many practitioners are unaware of methods and tools available to support these analyses. To address this issue, the US Environmental Protection Agency developed a toolbox of cumulative risk resources for contaminated sites, as part of a resource document that was published in 2007. This paper highlights information for nearly 80 resources from the toolbox and provides selected updates, with practical notes for cumulative risk applications. Resources are organized according to the main elements of the assessment process: (1) planning, scoping, and problem formulation; (2) environmental fate and transport; (3) exposure analysis extending to human factors; (4) toxicity analysis; and (5) risk and uncertainty characterization, including presentation of results. In addition to providing online access, plans for the toolbox include addressing nonchemical stressors and applications beyond contaminated sites and further strengthening resource accessibility to support evolving analyses for cumulative risk and sustainable communities. PMID:23762048

  13. Cumulative risk: toxicity and interactions of physical and chemical stressors.

    Science.gov (United States)

    Rider, Cynthia V; Boekelheide, Kim; Catlin, Natasha; Gordon, Christopher J; Morata, Thais; Selgrade, Maryjane K; Sexton, Kenneth; Simmons, Jane Ellen

    2014-01-01

    Recent efforts to update cumulative risk assessment procedures to incorporate nonchemical stressors ranging from physical to psychosocial reflect increased interest in consideration of the totality of variables affecting human health and the growing desire to develop community-based risk assessment methods. A key roadblock is the uncertainty as to how nonchemical stressors behave in relationship to chemical stressors. Physical stressors offer a reasonable starting place for measuring the effects of nonchemical stressors and their modulation of chemical effects (and vice versa), as they clearly differ from chemical stressors; and "doses" of many physical stressors are more easily quantifiable than those of psychosocial stressors. There is a commonly held belief that virtually nothing is known about the impact of nonchemical stressors on chemically mediated toxicity or the joint impact of coexposure to chemical and nonchemical stressors. Although this is generally true, there are several instances where a substantial body of evidence exists. A workshop titled "Cumulative Risk: Toxicity and Interactions of Physical and Chemical Stressors" held at the 2013 Society of Toxicology Annual Meeting provided a forum for discussion of research addressing the toxicity of physical stressors and what is known about their interactions with chemical stressors, both in terms of exposure and effects. Physical stressors including sunlight, heat, radiation, infectious disease, and noise were discussed in reference to identifying pathways of interaction with chemical stressors, data gaps, and suggestions for future incorporation into cumulative risk assessments.

  14. Childhood poverty and health: cumulative risk exposure and stress dysregulation.

    Science.gov (United States)

    Evans, Gary W; Kim, Pilyoung

    2007-11-01

    A massive literature documents the inverse association between poverty or low socioeconomic status and health, but little is known about the mechanisms underlying this robust relation. We examined longitudinal relations between duration of poverty exposure since birth, cumulative risk exposure, and physiological stress in two hundred seven 13-year-olds. Chronic stress was assessed by basal blood pressure and overnight cortisol levels; stress regulation was assessed by cardiovascular reactivity to a standard acute stressor and recovery after exposure to this stressor. Cumulative risk exposure was measured by multiple physical (e.g., substandard housing) and social (e.g., family turmoil) risk factors. The greater the number of years spent living in poverty, the more elevated was overnight cortisol and the more dysregulated was the cardiovascular response (i.e., muted reactivity). Cardiovascular recovery was not affected by duration of poverty exposure. Unlike the duration of poverty exposure, concurrent poverty (i.e., during adolescence) did not affect these physiological stress outcomes. The effects of childhood poverty on stress dysregulation are largely explained by cumulative risk exposure accompanying childhood poverty.

  15. Multiway Filtering Based on Fourth-Order Cumulants

    Directory of Open Access Journals (Sweden)

    Salah Bourennane

    2005-05-01

    Full Text Available We propose a new multiway filtering based on fourth-order cumulants for the denoising of noisy data tensor with correlated Gaussian noise. The classical multiway filtering is based on the TUCKALS3 algorithm that computes a lower-rank tensor approximation. The presented method relies on the statistics of the analyzed multicomponent signal. We first recall how the well-known lower rank-(K1,…,KN tensor approximation processed by TUCKALS3 alternating least square algorithm exploits second-order statistics. Then, we propose to introduce the fourth-order statistics in the TUCKALS3-based method. Indeed, the use of fourth-order cumulants enables to remove the Gaussian components of an additive noise. In the presented method the estimation of the n-mode projector on the n-mode signal subspace are built from the eigenvectors associated with the largest eigenvalues of a fourth-order cumulant slice matrix instead of a covariance matrix. Each projector is applied by means of the n-mode product operator on the n-mode of the data tensor. The qualitative results of the improved multiway TUCKALS3-based filterings are shown for the case of noise reduction in a color image and multicomponent seismic data.

  16. Cumulative risk hypothesis: Predicting and preventing child maltreatment recidivism.

    Science.gov (United States)

    Solomon, David; Åsberg, Kia; Peer, Samuel; Prince, Gwendolyn

    2016-08-01

    Although Child Protective Services (CPS) and other child welfare agencies aim to prevent further maltreatment in cases of child abuse and neglect, recidivism is common. Having a better understanding of recidivism predictors could aid in preventing additional instances of maltreatment. A previous study identified two CPS interventions that predicted recidivism: psychotherapy for the parent, which was related to a reduced risk of recidivism, and temporary removal of the child from the parent's custody, which was related to an increased recidivism risk. However, counter to expectations, this previous study did not identify any other specific risk factors related to maltreatment recidivism. For the current study, it was hypothesized that (a) cumulative risk (i.e., the total number of risk factors) would significantly predict maltreatment recidivism above and beyond intervention variables in a sample of CPS case files and that (b) therapy for the parent would be related to a reduced likelihood of recidivism. Because it was believed that the relation between temporary removal of a child from the parent's custody and maltreatment recidivism is explained by cumulative risk, the study also hypothesized that that the relation between temporary removal of the child from the parent's custody and recidivism would be mediated by cumulative risk. After performing a hierarchical logistic regression analysis, the first two hypotheses were supported, and an additional predictor, psychotherapy for the child, also was related to reduced chances of recidivism. However, Hypothesis 3 was not supported, as risk did not significantly mediate the relation between temporary removal and recidivism.

  17. A framework for adaptive monitoring of the cumulative effects of human footprint on biodiversity.

    Science.gov (United States)

    Burton, A Cole; Huggard, David; Bayne, Erin; Schieck, Jim; Sólymos, Péter; Muhly, Tyler; Farr, Dan; Boutin, Stan

    2014-06-01

    Effective ecological monitoring is imperative in a human-dominated world, as our ability to manage functioning ecosystems will depend on understanding biodiversity responses to anthropogenic impacts. Yet, most monitoring efforts have either been narrowly focused on particular sites, species and stressors - thus inadequately considering the cumulative effects of multiple, interacting impacts at scales of management relevance - or too unfocused to provide specific guidance. We propose a cumulative effects monitoring framework that integrates multi-scaled surveillance of trends in biodiversity and land cover with targeted evaluation of hypothesized drivers of change. The framework is grounded in a flexible conceptual model and uses monitoring to generate and test empirical models that relate the status of diverse taxonomic groups to the nature and extent of human "footprint" and other landscape attributes. An adaptive cycle of standardized sampling, model development, and model evaluation provides a means to learn about the system and guide management. Additional benefits of the framework include standardized data on status and trend for a wide variety of biodiversity elements, spatially explicit models for regional planning and scenario evaluation, and identification of knowledge gaps for complementary research. We describe efforts to implement the framework in Alberta, Canada, through the Alberta Biodiversity Monitoring Institute, and identify key challenges to be addressed.

  18. Modeling patterns in count data using loglinear and related models

    Energy Technology Data Exchange (ETDEWEB)

    Atwood, C.L.

    1995-12-01

    This report explains the use of loglinear and logit models, for analyzing Poisson and binomial counts in the presence of explanatory variables. The explanatory variables may be unordered categorical variables or numerical variables, or both. The report shows how to construct models to fit data, and how to test whether a model is too simple or too complex. The appropriateness of the methods with small data sets is discussed. Several example analyses, using the SAS computer package, illustrate the methods.

  19. El Carreto o Cumulá - Aspidosperma Dugandii Standl El Carreto o Cumulá - Aspidosperma Dugandii Standl

    Directory of Open Access Journals (Sweden)

    Dugand Armando

    1944-03-01

    Full Text Available Nombres vulgares: Carreto (Atlántico, Bolívar, Magdalena; Cumulá, Cumulá (Cundinamarca, ToIima. Según el Dr. Emilio Robledo (Lecciones de Bot. ed. 3, 2: 544. 1939 el nombre Carreto también es empleado en Puerto Berrío (Antioquia. El mismo autor (loc. cit. da el nombre Comulá para una especie indeterminada de Viburnum en Mariquita (Tolima y J. M. Duque, refiriendose a la misma planta y localidad (en Bot. Gen. Colomb. 340, 356. 1943 atribuye este nombre vulgar al Aspidosperma ellipticum Rusby.  Sin embargo, las muestras de madera de Cumulá o Comulá que yo he examinado, procedentes de la región de Mariquita -una de las cuales me fue recientemente enviada por el distinguido ictiólogo Sr. Cecil Miles- pertenecen sin duda alguna al A. Dugandii StandI. Por otra parte, Santiago Cortés (FI. Colomb. 206. 1898; ed, 2: 239. 1912 cita el Cumulá "de Anapoima y otros lugares del (rio Magdalena" diciendo que pertenece a las Leguminosas, pero la brevísima descripción que este autor hace de la madera "naranjada y notable por densidad, dureza y resistencia a la humedad", me induce a creer que se trata del mismo Cumula coleccionado recientemente en Tocaima, ya que esta población esta situada a pocos kilómetros de Anapoima. Nombres vulgares: Carreto (Atlántico, Bolívar, Magdalena; Cumulá, Cumulá (Cundinamarca, ToIima. Según el Dr. Emilio Robledo (Lecciones de Bot. ed. 3, 2: 544. 1939 el nombre Carreto también es empleado en Puerto Berrío (Antioquia. El mismo autor (loc. cit. da el nombre Comulá para una especie indeterminada de Viburnum en Mariquita (Tolima y J. M. Duque, refiriendose a la misma planta y localidad (en Bot. Gen. Colomb. 340, 356. 1943 atribuye este nombre vulgar al Aspidosperma ellipticum Rusby.  Sin embargo, las muestras de madera de Cumulá o Comulá que yo he examinado, procedentes de la región de Mariquita -una de las cuales me fue recientemente enviada por el distinguido ictiólogo Sr. Cecil Miles- pertenecen sin

  20. Evaluating Cumulative Ecosystem Response to Restoration Projects in the Columbia River Estuary, Annual Report 2004

    Energy Technology Data Exchange (ETDEWEB)

    Diefenderfer, Heida L.; Roegner, Curtis; Thom, Ronald M.; Dawley, Earl M.; Whiting, Allan H.; Johnson, Gary E.; Sobocinski, Kathryn L.; Anderson, Michael G.; Ebberts, Blaine

    2005-12-15

    The restoration of wetland salmon habitat in the tidal portion of the Columbia River is occurring at an accelerating pace and is anticipated to improve habitat quality and effect hydrological reconnection between existing and restored habitats. Currently multiple groups are applying a variety of restoration strategies in an attempt to emulate historic estuarine processes. However, the region lacks both a standardized means of evaluating the effectiveness of individual projects as well as methods for determining the cumulative effects of all restoration projects on a regional scale. This project is working to establish a framework to evaluate individual and cumulative ecosystem responses to restoration activities in order to validate the effectiveness of habitat restoration activities designed to benefit salmon through improvements to habitat quality and habitat opportunity (i.e. access) in the Columbia River from Bonneville Dam to the ocean. The review and synthesis of approaches to measure the cumulative effects of multiple restoration projects focused on defining methods and metrics of relevance to the CRE, and, in particular, juvenile salmon use of this system. An extensive literature review found no previous study assessing the cumulative effects of multiple restoration projects on the fundamental processes and functions of a large estuarine system, although studies are underway in other large land-margin ecosystems including the Florida Everglades and the Louisiana coastal wetlands. Literature from a variety of scientific disciplines was consulted to identify the ways that effects can accumulate (e.g., delayed effects, cross-boundary effects, compounding effects, indirect effects, triggers and thresholds) as well as standard and innovative tools and methods utilized in cumulative effects analyses: conceptual models, matrices, checklists, modeling, trends analysis, geographic information systems, carrying capacity analysis, and ecosystem analysis. Potential

  1. The impact of physical activity on cumulative cardiovascular disease risk factors among Malaysian adults.

    Science.gov (United States)

    Rasiah, Rajah; Thangiah, Govindamal; Yusoff, Khalid; Manikam, Rishya; Chandrasekaran, Sankara Kumar; Mustafa, Rujhan; Bakar, Najmin Binti Abu

    2015-12-16

    Numerous studies have shown the importance of physical activity in reducing the morbidity and mortality rates caused by cardiovascular disease (CVD). However, most of these studies emphasise little on the cumulative effect of CVD risk factors. Hence, this study investigates the association between physical exercise and cumulative CVD risk factors among adults in three different age groups. Using a sample of 7276 respondents drawn from community centers, the REDISCOVER team gathered information on physical activity, CVD risk factors (obesity, diabetes, hypertension, hypercholesterolemia, tobacco use) and socioeconomic and demographic variables in Malaysia. Because the study required medical examination, a convenience sampling frame was preferred in which all volunteers were included in the study. Fasting blood samples and anthropometric (height, weight and more) measurements were collected by trained staffs. Socio-demographic and physical activity variables were recorded through questionnaires. A Chi-square test was performed to identify the bivariate association between the covariates (socioeconomic variables, demographic variables and physical activity) and outcome variable. The association between the main exposure, physical activity, and the outcome variable, cumulative CVD risk factors, was assessed using an ordinal logistic regression model, controlling for socioeconomic status and demographic influences in three different age groups, 35-49, 50-64 and 65 and above. The mean age of participants is 51.8 (SD = 9.4). Respondents in the age groups of 35-49 (aORmoderate = 0.12; 95 % CI: 0.02 - 0.53 ) and 65 and above (aORhigh = 0.58; 95 % CI: 0.24, 0.78) showed a statistically significant inverse relationship between physical activity and cumulative CVD risk factors. However, this relationship was not significant among respondents in the 50-64 age group suggesting the possible influence of other variables, such as stress and environment. The

  2. Cumulative Effects of Coastal Habitat Alterations on Fishery Resources: toward Prediction at Regional Scales

    Directory of Open Access Journals (Sweden)

    Stephen J. Jordan

    2009-06-01

    Full Text Available Coastal habitat alterations such as the loss of submersed aquatic vegetation (SAV and hardening of shorelines could have cumulative effects on valuable fishery resources. To investigate this effect, we developed a multiscale modeling framework for blue crab (Callinectes sapidus in the northern Gulf of Mexico. Areal coverage of shoreline land cover and SAV for Mobile Bay, Alabama, were combined with information from small-scale biological studies and long-term, large-scale commercial fishery data to model the potential effects of marginal habitat losses on the blue crab fishery. We applied stochastic variation in annual recruitment to the fishery to estimate probabilities for sustainable harvests under scenarios of habitat loss. The simulations suggested that, accumulated over large areas, relatively small local losses of estuarine marsh edge and SAV habitats could have long-term negative effects on the sustainability of the fishery. Spatially extensive models are required to investigate the cumulative ecological effects of many local environmental changes. The requisite scaling adds uncertainty and reduces precision, but if model parameters are accurate at each scale, accurate predictions of long-term outcomes and probabilities are possible.

  3. Social organization and the evolution of cumulative technology in apes and hominins.

    Science.gov (United States)

    Pradhan, Gauri R; Tennie, Claudio; van Schaik, Carel P

    2012-07-01

    Culturally supported accumulation (or ratcheting) of technological complexity is widely seen as characterizing hominin technology relative to that of the extant great apes, and thus as representing a threshold in cultural evolution. To explain this divide, we modeled the process of cultural accumulation of technology, which we defined as adding new actions to existing ones to create new functional combinations, based on a model for great ape tool use. The model shows that intraspecific and interspecific variation in the presence of simple and cumulative technology among extant orangutans and chimpanzees is largely due to variation in sociability, and hence opportunities for social learning. The model also suggests that the adoption of extensive allomaternal care (cooperative breeding) in early Pleistocene Homo, which led to an increase in sociability and to teaching, and hence increased efficiency of social learning, was enough to facilitate technological ratcheting. Hence, socioecological changes, rather than advances in cognitive abilities, can account for the cumulative cultural changes seen until the origin of the Acheulean. The consequent increase in the reliance on technology could have served as the pacemaker for increased cognitive abilities. Our results also suggest that a more important watershed in cultural evolution was the rise of donated culture (technology or concepts), in which technology or concepts was transferred to naïve individuals, allowing them to skip many learning steps, and specialization arose, which allowed individuals to learn only a subset of the population's skills. Copyright © 2012 Elsevier Ltd. All rights reserved.

  4. Cumulative biological impacts framework for solar energy projects in the California Desert

    Science.gov (United States)

    Davis, Frank W.; Kreitler, Jason R.; Soong, Oliver; Stoms, David M.; Dashiell, Stephanie; Hannah, Lee; Wilkinson, Whitney; Dingman, John

    2013-01-01

    This project developed analytical approaches, tools and geospatial data to support conservation planning for renewable energy development in the California deserts. Research focused on geographical analysis to avoid, minimize and mitigate the cumulative biological effects of utility-scale solar energy development. A hierarchical logic model was created to map the compatibility of new solar energy projects with current biological conservation values. The research indicated that the extent of compatible areas is much greater than the estimated land area required to achieve 2040 greenhouse gas reduction goals. Species distribution models were produced for 65 animal and plant species that were of potential conservation significance to the Desert Renewable Energy Conservation Plan process. These models mapped historical and projected future habitat suitability using 270 meter resolution climate grids. The results were integrated into analytical frameworks to locate potential sites for offsetting project impacts and evaluating the cumulative effects of multiple solar energy projects. Examples applying these frameworks in the Western Mojave Desert ecoregion show the potential of these publicly-available tools to assist regional planning efforts. Results also highlight the necessity to explicitly consider projected land use change and climate change when prioritizing areas for conservation and mitigation offsets. Project data, software and model results are all available online.

  5. Spectral distortion of the CMB by the cumulative CO emission from galaxies throughout cosmic history

    Science.gov (United States)

    Mashian, Natalie; Loeb, Abraham; Sternberg, Amiel

    2016-05-01

    We show that the cumulative CO emission from galaxies throughout cosmic history distorts the spectrum of the cosmic microwave background at a level that is well above the detection limit of future instruments, such as the Primordial Inflation Explorer. The modelled CO signal has a prominent bump in the frequency interval 100-200 GHz, with a characteristic peak intensity of ˜2 × 10-23 W m-2 Hz-1 sr-1. Most of the CO foreground originates from modest redshifts, z ˜ 2-5, and needs to be efficiently removed for more subtle distortions from the earlier Universe to be detected.

  6. Importance of separated efficiencies between positively and negatively charged particles for cumulant calculations

    CERN Document Server

    Nonaka, Toshihiro; Esumi, ShinIchi; Masui, Hiroshi; Luo, Xiaofeng

    2016-01-01

    We show the importance of separated efficiency corrections between positively and negatively charged particles for cumulant calculations by Monte Carlo toy models and analytical calculations. Our results indicate that S{\\sigma} in published net-proton results from the STAR experiment will be suppressed about 5 to 10% in central collisions, and 10 to 20% in peripheral collisions at the beam energy of \\sqrt s_{NN} = 62.4 and 200 GeV if the separated efficiencies are used to efficiency correction.

  7. Probabilistic cumulative risk assessment of anti-androgenic pesticides in food

    DEFF Research Database (Denmark)

    Müller, Anne Kirstine; Bosgra, Sieto; Boon, Polly E.;

    2009-01-01

    reproductive endpoints (ano-genital distance, and weights of the seminal vesicles and the musculus levator ani/bulbocavernosus) in male rat foetuses exposed in utero. The cumulative dietary intake was estimated based on consumption data and residue data from the Netherlands. The IPRA model combines variability...... in both exposure and sensitivity between individuals into a distribution of individual margins of exposures (IMoEs) and IMoEs of 1 or less indicate a possible concern. The assessment did not result in IMoEs ≤ 1. The endpoint ‘weight of seminal vesicles’ resulted in the lowest IMoEs (0.1th percentile: 198...

  8. Cumulants of multiplicity distributions in most-central heavy-ion collisions

    Science.gov (United States)

    Xu, Hao-jie

    2016-11-01

    I investigate the volume corrections on cumulants of total charge distributions and net proton distributions. The required volume information is generated by an optical Glauber model. I find that the corrected statistical expectations of multiplicity distributions mimic the negative binomial distributions at noncentral collisions, and they tend to approach the Poisson ones at most-central collisions due to the "boundary effects," which suppress the volume corrections. However, net proton distributions and reference multiplicity distributions are sensitive to the external volume fluctuations at most-central collisions, which imply that one has to consider the details of volume distributions in event-by-event multiplicity fluctuation studies.

  9. Mismatch or cumulative stress : Toward an integrated hypothesis of programming effects

    NARCIS (Netherlands)

    Nederhof, Esther; Schmidt, Mathias V.

    2012-01-01

    This paper integrates the cumulative stress hypothesis with the mismatch hypothesis, taking into account individual differences in sensitivity to programming. According to the cumulative stress hypothesis, individuals are more likely to suffer from disease as adversity accumulates. According to the

  10. Cumulative Radiative Forcing Implications of Deployment Strategies for Carbon Capture and Storage

    Science.gov (United States)

    Sathre, R. C.; Masanet, E.

    2011-12-01

    Carbon capture and storage (CCS) is increasingly discussed as a potential means of mitigating the climate disruption associated with fossil fuel use. Some technologies for capturing, transporting, and sequestering carbon dioxide (CO2) are already mature, while others technologies under development may lead to more cost- and energy-efficient CCS systems. Various elements of CCS systems are currently in operation at relatively small scale, but will need to be scaled up very substantially in order to make a significant contribution to climate change mitigation. Because the rate of fossil fuel CO2 emission is continuing to increase and the emitted CO2 will remain in the atmosphere for long time periods, the speed at which CCS is deployed will strongly affect the cumulative CO2 emission and the climate impacts. To better understand these issues, in this analysis we integrate scenario forecasting of energy supply systems, life cycle emission modeling, and time-dependent calculations of cumulative radiative forcing. We develop a series of CCS deployment scenarios that describe plausible future trajectories for CCS implementation in the US electric power plant fleet. The scenarios incorporate dimensions such as speed of deployment build-out, year of initiating deployment, efficiency of capture technology, and installation in new power plants vs. retrofitting existing plants. We conduct life cycle greenhouse gas (GHG) emissions analyses of each scenario to estimate annual emission profiles of CO2, CH4, and N2O over a 90-year time horizon, from 2010 to 2100. We then model the atmospheric dynamics of the emitted GHGs including atmospheric decay and instantaneous radiative forcing patterns over time. Finally, we determine the cumulative radiative forcing of each scenario, which we use as a proxy for surface temperature change and resulting disruption to physical, ecological and social systems. The results show strong climate mitigation benefits of early, aggressive

  11. Procedures for assessment of cumulative impacts of coal mining on the hydrologic balance

    Science.gov (United States)

    Lumb, Alan M.

    1982-01-01

    Techniques were developed to assess the probable cumulative impacts of anticipated surface mining upon the hydrology of and area. An activity profile of cumulative drainage area versus river miles downstream from the surface mining site is constructed that shows major water uses, flood prone areas, and stream classifications. From the summary shown by the activity profile, an impact matrix is used as a checklist for the importance of the impacts under categories such as water supply, flood prone areas, water contact recreation, etc. Based on the categories checked on the impact matrix, a simple, less accurate model or a more comprehensive and accurate one can be used to quantify the impacts. Quantified impacts are then displayed on an impact profile showing the percentage change in a hydrologic characteristic versus distance downstream of the surface mining site. The simple model for quantification considers only dilution from tributary areas during critical periods whereas the comprehensive model routes flows and quality of water continuously through the year and considers, in addition to dilution, instream processes such as settling, biological uptake , and chemical reactions. (USGS)

  12. The Carvedilol Prospective Randomized Cumulative Survival (COPERNICUS) trial.

    Science.gov (United States)

    Eichhorn, Eric J; Bristow, Michael R

    2001-01-01

    Previous trials (Metoprolol CR/XL Randomised Intervention Trial in Congestive Heart Failure [MERIT-HF], Cardiac Insufficiency Bisoprolol Study [CIBIS] II) have demonstrated a mortality benefit of beta-adrenergic blockade in patients with mild to moderate heart failure. The recent Carvedilol Prospective Randomized Cumulative Survival (COPERNICUS) trial has extended these results to a more advanced patient population. This trial did not, however, include patients who could not reach compensation, patients with far advanced heart failure symptoms, or a significant number of black patients. Future studies of beta-blockade may focus on these patients or patients with asymptomatic left ventricular dysfunction.

  13. Neutron source capability assessment for cumulative fission yields measurements

    Energy Technology Data Exchange (ETDEWEB)

    Descalle, M A; Dekin, W; Kenneally, J

    2011-04-06

    A recent analysis of high-quality cumulative fission yields data for Pu-239 published in the peer-reviewed literature showed that the quoted experimental uncertainties do not allow a clear statement on how the fission yields vary as a function of energy. [Prussin2009] To make such a statement requires a set of experiments with well 'controlled' and understood sources of experimental errors to reduce uncertainties as low as possible, ideally in the 1 to 2% range. The Inter Laboratory Working Group (ILWOG) determined that Directed Stockpile Work (DSW) would benefit from an experimental program with the stated goal to reduce the measurement uncertainties significantly in order to make a definitive statement of the relationship of energy dependence to the cumulative fission yields. Following recent discussions between Lawrence Livermore National Laboratory (LLNL) and Los Alamos National Laboratory (LANL), there is a renewed interest in developing a concerted experimental program to measure fission yields in a neutron energy range from thermal energy (0.025 eV) to 14 MeV with an emphasis on discrete energies from 0.5 to 4 MeV. Ideally, fission yields would be measured at single energies, however, in practice there are only 'quasi-monoenergetic' neutrons sources of finite width. This report outlines a capability assessment as of June 2011 of available neutron sources that could be used as part of a concerted experimental program to measure cumulative fission yields. In a framework of international collaborations, capabilities available in the United States, at the Atomic Weapons Establishment (AWE) in the United Kingdom and at the Commissariat Energie Atomique (CEA) in France are listed. There is a need to develop an experimental program that will reduce the measurement uncertainties significantly in order to make a definitive statement of the relationship of energy dependence to the cumulative fission yields. Fission and monoenergetic neutron sources

  14. The Carvedilol Prospective Randomized Cumulative Survival (COPERNICUS trial

    Directory of Open Access Journals (Sweden)

    Bristow Michael R

    2001-02-01

    Full Text Available Abstract Previous trials (Metoprolol CR/XL Randomised Intervention Trial in Congestive Heart Failure [MERIT-HF], Cardiac Insufficiency Bisoprolol Study [CIBIS] II have demonstrated a mortality benefit of β-adrenergic blockade in patients with mild to moderate heart failure. The recent Carvedilol Prospective Randomized Cumulative Survival (COPERNICUS trial has extended these results to a more advanced patient population. This trial did not, however, include patients who could not reach compensation, patients with far advanced heart failure symptoms, or a significant number of black patients. Future studies of β-blockade may focus on these patients or patients with asymptomatic left ventricular dysfunction.

  15. Generalized Cumulative Residual Entropy for Distributions with Unrestricted Supports

    Directory of Open Access Journals (Sweden)

    Noomane Drissi

    2008-01-01

    Full Text Available We consider the cumulative residual entropy (CRE a recently introduced measure of entropy. While in previous works distributions with positive support are considered, we generalize the definition of CRE to the case of distributions with general support. We show that several interesting properties of the earlier CRE remain valid and supply further properties and insight to problems such as maximum CRE power moment problems. In addition, we show that this generalized CRE can be used as an alternative to differential entropy to derive information-based optimization criteria for system identification purpose.

  16. Influence of Consumer Demographics on the Demand for Locally Grown Ethnic Greens and Herbs Because of Food Miles Concerns: A Logit Model Analysis

    OpenAIRE

    Govindasamy, Ramu; Purduri, Venkata; Kelley, Kathleen; Simon, James E.

    2012-01-01

    This project was supported by the Specialty Crop Research Initiative of the National Institute of Food and Agriculture, USDA, Grant # 2009-51181-06035. Trade in fresh fruits and vegetables has raised concerns about the distance food travels, food cost, freshness, and climate change associated with the transport. The term food mile refers to the distance or the number of miles that food travels from producer to consumer through its supply chain. Purchasing directly from local farmers may reduc...

  17. Determining source cumulants in femtoscopy with Gram-Charlier and Edgeworth series

    DEFF Research Database (Denmark)

    Eggers, H. C.; De Kock, M. B.; Schmiegel, Jürgen

    2011-01-01

    Lowest-order cumulants provide important information on the shape of the emission source in femtoscopy. For the simple case of noninteracting identical particles, we show how the fourth-order source cumulant can be determined from measured cumulants in momentum space. The textbook Gram–Charlier s...

  18. High-resolution harmonic retrieval using the full fourth-order cumulant

    NARCIS (Netherlands)

    Vossen, S.H.J.A.; Naus, H.W.L.; Zwamborn, A.P.M.

    2010-01-01

    The harmonic retrieval (HR) problem concerns the estimation of the frequencies in a sum of real or complex harmonics. Both correlation and cumulant-based approaches are used for this purpose. Cumulant-based HR algorithms use a single 1-D slice of the fourth-order cumulant that is estimated directly

  19. 75 FR 69662 - Workshop: Cumulative Mixtures Risk of Six Selected Phthalates in Support of Summary Information...

    Science.gov (United States)

    2010-11-15

    ... AGENCY Workshop: Cumulative Mixtures Risk of Six Selected Phthalates in Support of Summary Information on...: Notice of Peer Consultation Workshop on the Cumulative Mixtures Risk of Six Selected Phthalates; Request... phthalates as set forth in the National Academies of Science (NAS) report ``Phthalates and Cumulative...

  20. Trimmed Likelihood-based Estimation in Binary Regression Models

    NARCIS (Netherlands)

    Cizek, P.

    2005-01-01

    The binary-choice regression models such as probit and logit are typically estimated by the maximum likelihood method.To improve its robustness, various M-estimation based procedures were proposed, which however require bias corrections to achieve consistency and their resistance to outliers is rela

  1. Cumulative human threats on fish biodiversity components in Tunisian waters

    Directory of Open Access Journals (Sweden)

    F. BEN RAIS LASRAM

    2015-02-01

    Full Text Available Human activities are increasingly impacting biodiversity. To improve conservation planning measures in an ecosystem-based management context, we need to explore how the effects of these activities interact with different biodiversity components. In this study, we used a semi-quantitative method to assess the cumulative impacts of human activities on three biodiversity components (species richness, phylogenetic diversity, and functional diversity in Tunisia’s exclusive economic zone. For each of the nine activities considered, we developed an understanding of their effects from local studies and the expert opinion of stakeholders with country-specific experience. We mapped the cumulative effects and the three biodiversity components and then assessed the degree to which these elements overlapped using an overlap index. This is the first time such an assessment has been made for Tunisia’s marine ecosystems and our assessment highlight the inappropriateness of current conservation measures. The results of this study have specific application for the prioritization of future management actions.

  2. Cumulative human threats on fish biodiversity components in Tunisian waters

    Directory of Open Access Journals (Sweden)

    F. BEN RAIS LASRAM

    2014-06-01

    Full Text Available Human activities are increasingly impacting biodiversity. To improve conservation planning measures in an ecosystem-based management context, we need to explore how the effects of these activities interact with different biodiversity components. In this study, we used a semi-quantitative method to assess the cumulative impacts of human activities on three biodiversity components (species richness, phylogenetic diversity, and functional diversity in Tunisia’s exclusive economic zone. For each of the nine activities considered, we developed an understanding of their effects from local studies and the expert opinion of stakeholders with country-specific experience. We mapped the cumulative effects and the three biodiversity components and then assessed the degree to which these elements overlapped using an overlap index. This is the first time such an assessment has been made for Tunisia’s marine ecosystems and our assessment highlight the inappropriateness of current conservation measures. The results of this study have specific application for the prioritization of future management actions.

  3. Extraction of Facial Feature Points Using Cumulative Histogram

    CERN Document Server

    Paul, Sushil Kumar; Bouakaz, Saida

    2012-01-01

    This paper proposes a novel adaptive algorithm to extract facial feature points automatically such as eyebrows corners, eyes corners, nostrils, nose tip, and mouth corners in frontal view faces, which is based on cumulative histogram approach by varying different threshold values. At first, the method adopts the Viola-Jones face detector to detect the location of face and also crops the face region in an image. From the concept of the human face structure, the six relevant regions such as right eyebrow, left eyebrow, right eye, left eye, nose, and mouth areas are cropped in a face image. Then the histogram of each cropped relevant region is computed and its cumulative histogram value is employed by varying different threshold values to create a new filtering image in an adaptive way. The connected component of interested area for each relevant filtering image is indicated our respective feature region. A simple linear search algorithm for eyebrows, eyes and mouth filtering images and contour algorithm for nos...

  4. Cumulative Effects Assessment: Linking Social, Ecological, and Governance Dimensions

    Directory of Open Access Journals (Sweden)

    Marian Weber

    2012-06-01

    Full Text Available Setting social, economic, and ecological objectives is ultimately a process of social choice informed by science. In this special feature we provide a multidisciplinary framework for the use of cumulative effects assessment in land use planning. Forest ecosystems are facing considerable challenges driven by population growth and increasing demands for resources. In a suite of case studies that span the boreal forest of Western Canada to the interior Atlantic forest of Paraguay we show how transparent and defensible methods for scenario analysis can be applied in data-limited regions and how social dimensions of land use change can be incorporated in these methods, particularly in aboriginal communities that have lived in these ecosystems for generations. The case studies explore how scenario analysis can be used to evaluate various land use options and highlight specific challenges with identifying social and ecological responses, determining thresholds and targets for land use, and integrating local and traditional knowledge in land use planning. Given that land use planning is ultimately a value-laden and often politically charged process we also provide some perspective on various collective and expert-based processes for identifying cumulative impacts and thresholds. The need for good science to inform and be informed by culturally appropriate democratic processes calls for well-planned and multifaceted approaches both to achieve an informed understanding of both residents and governments of the interactive and additive changes caused by development, and to design action agendas to influence such change at the ecological and social level.

  5. Cumulative hierarchies and computability over universes of sets

    Directory of Open Access Journals (Sweden)

    Domenico Cantone

    2008-05-01

    Full Text Available Various metamathematical investigations, beginning with Fraenkel’s historical proof of the independence of the axiom of choice, called for suitable definitions of hierarchical universes of sets. This led to the discovery of such important cumulative structures as the one singled out by von Neumann (generally taken as the universe of all sets and Godel’s universe of the so-called constructibles. Variants of those are exploited occasionally in studies concerning the foundations of analysis (according to Abraham Robinson’s approach, or concerning non-well-founded sets. We hence offer a systematic presentation of these many structures, partly motivated by their relevance and pervasiveness in mathematics. As we report, numerous properties of hierarchy-related notions such as rank, have been verified with the assistance of the ÆtnaNova proof-checker.Through SETL and Maple implementations of procedures which effectively handle the Ackermann’s hereditarily finite sets, we illustrate a particularly significant case among those in which the entities which form a universe of sets can be algorithmically constructed and manipulated; hereby, the fruitful bearing on pure mathematics of cumulative set hierarchies ramifies into the realms of theoretical computer science and algorithmics.

  6. Petrogenesis of the nakhlite meteorites: Evidence from cumulate mineral zoning

    Energy Technology Data Exchange (ETDEWEB)

    Harvey, R.P.; McSween, H.Y. Jr. (Univ. of Tennessee, Knoxville (United States))

    1992-04-01

    A simple igneous petrogenesis for the meteorite Nakhla has previously been called into question because Mg/Fe ratios in olivine indicate substantial disequilibrium between the predominant cumulus minerals (olivine and augite). Comparative analyses of simulated diffusive zoning and the observed cumulus mineral zoning for all three nakhlites (Nakhla, Governador Valadares, and Lafayette) show that their current compositions do not necessarily reflect parental magma compositions. Instead, diffusion has altered primary cumulus compositions to varying degrees, Nakhla being the least affected, and Lafayette being almost completely re-equilibrated. Only the cores of augite grains in Nakhla and Governador Valadares appear to have preserved their original compositions. Mineral zoning in each meteorite is strongly concentric around mesostasis areas, suggesting that reaction with intercumulus liquid has controlled the observed zoning. The presence of pigeonite and orthopyroxene overgrowths in Nakhla and Governador Valadares, and of poikilitic orthopyroxene enclosing olivine relicts in Lafayette, indicate substantial late-magmatic reactions. Two-pyroxene geothermometry for Lafayette indicates temperatures around 95C, suggesting subsolidus equilibration as well. The nakhlites appear to be a series of relatively simple cumulate rocks which have undergone various amounts of late-magmatic and subsolidus diffusion, possibly reflecting their relative positions in a cooling cumulate pile.

  7. Analysis and modeling of parking behavior

    Institute of Scientific and Technical Information of China (English)

    2001-01-01

    Analyzes the spatial structure of parking behavior and establishes a basic parking behavior model to represent the parking problem in downtown, and establishes a parking pricing model to analyze the parking equilibrium with a positive parking fee and uses a paired combinatorial logit model to analyze the effect of trip integrative cost on parking behavior and concludes from empirical results that the parking behavior model performs well.

  8. Projecting Cumulative Benefits of Multiple River Restoration Projects: An Example from the Sacramento-San Joaquin River System in California

    Science.gov (United States)

    Kondolf, G. Mathias; Angermeier, Paul L.; Cummins, Kenneth; Dunne, Thomas; Healey, Michael; Kimmerer, Wim; Moyle, Peter B.; Murphy, Dennis; Patten, Duncan; Railsback, Steve; Reed, Denise J.; Spies, Robert; Twiss, Robert

    2008-12-01

    Despite increasingly large investments, the potential ecological effects of river restoration programs are still small compared to the degree of human alterations to physical and ecological function. Thus, it is rarely possible to “restore” pre-disturbance conditions; rather restoration programs (even large, well-funded ones) will nearly always involve multiple small projects, each of which can make some modest change to selected ecosystem processes and habitats. At present, such projects are typically selected based on their attributes as individual projects (e.g., consistency with programmatic goals of the funders, scientific soundness, and acceptance by local communities), and ease of implementation. Projects are rarely prioritized (at least explicitly) based on how they will cumulatively affect ecosystem function over coming decades. Such projections require an understanding of the form of the restoration response curve, or at least that we assume some plausible relations and estimate cumulative effects based thereon. Drawing on our experience with the CALFED Bay-Delta Ecosystem Restoration Program in California, we consider potential cumulative system-wide benefits of a restoration activity extensively implemented in the region: isolating/filling abandoned floodplain gravel pits captured by rivers to reduce predation of outmigrating juvenile salmon by exotic warmwater species inhabiting the pits. We present a simple spreadsheet model to show how different assumptions about gravel pit bathymetry and predator behavior would affect the cumulative benefits of multiple pit-filling and isolation projects, and how these insights could help managers prioritize which pits to fill.

  9. A hybrid finite mixture model for exploring heterogeneous ordering patterns of driver injury severity.

    Science.gov (United States)

    Ma, Lu; Wang, Guan; Yan, Xuedong; Weng, Jinxian

    2016-04-01

    Debates on the ordering patterns of crash injury severity are ongoing in the literature. Models without proper econometrical structures for accommodating the complex ordering patterns of injury severity could result in biased estimations and misinterpretations of factors. This study proposes a hybrid finite mixture (HFM) model aiming to capture heterogeneous ordering patterns of driver injury severity while enhancing modeling flexibility. It attempts to probabilistically partition samples into two groups in which one group represents an unordered/nominal data-generating process while the other represents an ordered data-generating process. Conceptually, the newly developed model offers flexible coefficient settings for mining additional information from crash data, and more importantly it allows the coexistence of multiple ordering patterns for the dependent variable. A thorough modeling performance comparison is conducted between the HFM model, and the multinomial logit (MNL), ordered logit (OL), finite mixture multinomial logit (FMMNL) and finite mixture ordered logit (FMOL) models. According to the empirical results, the HFM model presents a strong ability to extract information from the data, and more importantly to uncover heterogeneous ordering relationships between factors and driver injury severity. In addition, the estimated weight parameter associated with the MNL component in the HFM model is greater than the one associated with the OL component, which indicates a larger likelihood of the unordered pattern than the ordered pattern for driver injury severity.

  10. Towards a framework for assessment and management of cumulative human impacts on marine food webs.

    Science.gov (United States)

    Giakoumi, Sylvaine; Halpern, Benjamin S; Michel, Loïc N; Gobert, Sylvie; Sini, Maria; Boudouresque, Charles-François; Gambi, Maria-Cristina; Katsanevakis, Stelios; Lejeune, Pierre; Montefalcone, Monica; Pergent, Gerard; Pergent-Martini, Christine; Sanchez-Jerez, Pablo; Velimirov, Branko; Vizzini, Salvatrice; Abadie, Arnaud; Coll, Marta; Guidetti, Paolo; Micheli, Fiorenza; Possingham, Hugh P

    2015-08-01

    Effective ecosystem-based management requires understanding ecosystem responses to multiple human threats, rather than focusing on single threats. To understand ecosystem responses to anthropogenic threats holistically, it is necessary to know how threats affect different components within ecosystems and ultimately alter ecosystem functioning. We used a case study of a Mediterranean seagrass (Posidonia oceanica) food web and expert knowledge elicitation in an application of the initial steps of a framework for assessment of cumulative human impacts on food webs. We produced a conceptual seagrass food web model, determined the main trophic relationships, identified the main threats to the food web components, and assessed the components' vulnerability to those threats. Some threats had high (e.g., coastal infrastructure) or low impacts (e.g., agricultural runoff) on all food web components, whereas others (e.g., introduced carnivores) had very different impacts on each component. Partitioning the ecosystem into its components enabled us to identify threats previously overlooked and to reevaluate the importance of threats commonly perceived as major. By incorporating this understanding of system vulnerability with data on changes in the state of each threat (e.g., decreasing domestic pollution and increasing fishing) into a food web model, managers may be better able to estimate and predict cumulative human impacts on ecosystems and to prioritize conservation actions. © 2015 Society for Conservation Biology.

  11. Estimating the Cumulative Ecological Effect of Local Scale Landscape Changes in South Florida

    Science.gov (United States)

    Hogan, Dianna M.; Labiosa, William; Pearlstine, Leonard; Hallac, David; Strong, David; Hearn, Paul; Bernknopf, Richard

    2012-01-01

    Ecosystem restoration in south Florida is a state and national priority centered on the Everglades wetlands. However, urban development pressures affect the restoration potential and remaining habitat functions of the natural undeveloped areas. Land use (LU) planning often focuses at the local level, but a better understanding of the cumulative effects of small projects at the landscape level is needed to support ecosystem restoration and preservation. The South Florida Ecosystem Portfolio Model (SFL EPM) is a regional LU planning tool developed to help stakeholders visualize LU scenario evaluation and improve communication about regional effects of LU decisions. One component of the SFL EPM is ecological value (EV), which is evaluated through modeled ecological criteria related to ecosystem services using metrics for (1) biodiversity potential, (2) threatened and endangered species, (3) rare and unique habitats, (4) landscape pattern and fragmentation, (5) water quality buffer potential, and (6) ecological restoration potential. In this article, we demonstrate the calculation of EV using two case studies: (1) assessing altered EV in the Biscayne Gateway area by comparing 2004 LU to potential LU in 2025 and 2050, and (2) the cumulative impact of adding limestone mines south of Miami. Our analyses spatially convey changing regional EV resulting from conversion of local natural and agricultural areas to urban, industrial, or extractive use. Different simulated local LU scenarios may result in different alterations in calculated regional EV. These case studies demonstrate methods that may facilitate evaluation of potential future LU patterns and incorporate EV into decision making.

  12. Cumulative effects of noise and odour annoyances on environmental and health related quality of life.

    Science.gov (United States)

    Oiamo, Tor H; Luginaah, Isaac N; Baxter, Jamie

    2015-12-01

    Noise and odour annoyances are important considerations in research on health effects of air pollution and traffic noise. Cumulative exposures can occur via several chemical hazards or a combination of chemical and stressor-based hazards, and related health outcomes can be generalized as manifestations of physiological and/or psychological stress responses. A major research challenge in this field is to understand the combined health effects of physiological and psychological responses to exposure. The SF-12 Health Survey is a health related quality of life (HRQoL) instrument designed for the assessment of functional mental and physical health in clinical practice and therefore well suited to research on physiological health outcomes of exposure. However, previous research has not assessed its sensitivity to psychological stress as measured by noise annoyance and odour annoyance. The current study validated and tested this application of the SF-12 Health Survey in a cross-sectional study (n = 603) that included exposure assessment for traffic noise and air pollution in Windsor, Ontario, Canada. The results indicated that SF-12 scores in Windsor were lower than Canadian normative data. A structural equation model demonstrated that this was partially due to noise and odour annoyances, which were associated with covarying exposures to ambient nitrogen dioxide and traffic noise. More specifically, noise annoyance had a significant and negative effect on both mental and physical health factors of the SF-12 and there was a significant covariance between noise annoyance and odour annoyance. The study confirmed a significant effect of psychological responses to cumulative exposures on HRQoL. The SF-12 Health Survey shows promise with respect to assessing the cumulative health effects of outdoor air pollution and traffic noise.

  13. 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...... developed for two compounds, tebuconazole and prochloraz, and a binary mixture of these compounds in two species, rat and human. PBTK models can be used to estimate the concentration levels (internal doses) of toxic substances and their metabolites in blood and tissue, by a collection of differential...... the models. Exposure scenarios were constructed based on findings of pesticide residues in food of ordinary consumers, and assessment of dermal exposure of professional workers. PBTK simulations were carried using these scenarios....

  14. Use of a Cumulative Risk Scale to Predict Poor Intellectual and Academic Outcomes in Childhood Epilepsy.

    Science.gov (United States)

    Kavanaugh, Brian C; Scarborough, Vanessa Ramos; Salorio, Cynthia F

    2016-06-01

    Discrete risk factors for poor outcomes in childhood epilepsy have been identified, but it is unclear whether the combined effect of several risk factors better predicts outcome. The Epilepsy Cumulative Risk Scale was developed to quantify cumulative risk for poor outcomes in childhood epilepsy. Participants included 156 clinic-referred children with epilepsy. The Epilepsy Cumulative Risk Scale was developed using variables previously associated with functional outcomes. Scale utility was examined through its association with intellectual and academic functioning. All Epilepsy Cumulative Risk Scale variables were significantly associated with functioning. The Total Score (ie, cumulative effect) was most strongly correlated with cognition and academic skills. A Total Score ≥ 5 had the best sensitivity and specificity for differentiating those at high risk for poor outcomes. The Epilepsy Cumulative Risk Scale shows promise as a practical, data-driven tool for quantification of cumulative risk for poor outcomes in childhood epilepsy and may be helpful in detecting those needing referral for additional services.

  15. Assessing the implications of human land-use change for the transient climate response to cumulative carbon emissions

    Science.gov (United States)

    Simmons, C. T.; Matthews, H. D.

    2016-03-01

    Recent research has shown evidence of a linear climate response to cumulative CO2 emissions, which implies that the source, timing, and amount of emissions does not significantly influence the climate response per unit emission. Furthermore, these analyses have generally assumed that the climate response to land-use CO2 emissions is equivalent to that of fossil fuels under the assumption that, once in the atmosphere, the radiative forcing induced by CO2 is not sensitive to the emissions source. However, land-cover change also affects surface albedo and the strength of terrestrial carbon sinks, both of which have an additional climate effect. In this study, we use a coupled climate-carbon cycle model to assess the climate response to historical and future cumulative land-use CO2 emissions, in order to compare it to the response to fossil fuel CO2. We find that when we isolate the CO2-induced (biogeochemical) temperature changes associated with land-use change, then the climate response to cumulative land-use emissions is equivalent to that of fossil fuel CO2. We show further that the globally-averaged albedo-induced biophysical cooling from land-use change is non-negligible and may be of comparable magnitude to the biogeochemical warming, with the result that the net climate response to land-use change is substantially different from a linear response to cumulative emissions. However, our new simulations suggest that the biophysical cooling from land-use change follows its own independent (negative) linear response to cumulative net land-use CO2 emissions, which may provide a useful scaling factor for certain applications when evaluating the full transient climate response to emissions.

  16. Cumulative approaches to track formation under swift heavy ion (SHI) irradiation: Phenomenological correlation with formation energies of Frenkel pairs

    Energy Technology Data Exchange (ETDEWEB)

    Crespillo, M.L., E-mail: mcrespil@utk.edu [Centro de Microanálisis de Materiales, CMAM-UAM, Cantoblanco, Madrid 28049 (Spain); Department of Materials Science & Engineering, University of Tennessee, Knoxville, TN 37996 (United States); Agulló-López, F., E-mail: fal@uam.es [Centro de Microanálisis de Materiales, CMAM-UAM, Cantoblanco, Madrid 28049 (Spain); Zucchiatti, A. [Centro de Microanálisis de Materiales, CMAM-UAM, Cantoblanco, Madrid 28049 (Spain)

    2017-03-01

    Highlights: • Extensive survey formation energies Frenkel pairs and electronic stopping thresholds. • Correlation: track formation thresholds and the energies for Frenkel pair formation. • Formation energies Frenkel pairs discussed in relation to the cumulative mechanisms. • Amorphous track formation mechanisms: defect accumulation models versus melting. • Advantages cumulative models to deal with new hot topics: nuclear-electronic synergy. - Abstract: An extensive survey for the formation energies of Frenkel pairs, as representative candidates for radiation-induced point defects, is presented and discussed in relation to the cumulative mechanisms (CM) of track formation in dielectric materials under swift heavy ion (SHI) irradiation. These mechanisms rely on the generation and accumulation of point defects during irradiation followed by collapse of the lattice once a threshold defect concentration is reached. The physical basis of those approaches has been discussed by Fecht as a defect-assisted transition to an amorphous phase. Although a first quantitative analysis of the CM model was previously performed for LiNbO{sub 3} crystals, we have, here, adopted a broader phenomenological approach. It explores the correlation between track formation thresholds and the energies for Frenkel pair formation for a broad range of materials. It is concluded that the threshold stopping powers can be roughly scaled with the energies required to generate a critical Frenkel pair concentration in the order of a few percent of the total atomic content. Finally, a comparison with the predictions of the thermal spike model is discussed within the analytical Szenes approximation.

  17. Cumulative risk effects for the development of behaviour difficulties in children and adolescents with special educational needs and disabilities.

    Science.gov (United States)

    Oldfield, Jeremy; Humphrey, Neil; Hebron, Judith

    2015-01-01

    Research has identified multiple risk factors for the development of behaviour difficulties. What have been less explored are the cumulative effects of exposure to multiple risks on behavioural outcomes, with no study specifically investigating these effects within a population of young people with special educational needs and disabilities (SEND). Furthermore, it is unclear whether a threshold or linear risk model better fits the data for this population. The sample included 2660 children and 1628 adolescents with SEND. Risk factors associated with increases in behaviour difficulties over an 18-month period were summed to create a cumulative risk score, with this explanatory variable being added into a multi-level model. A quadratic term was then added to test the threshold model. There was evidence of a cumulative risk effect, suggesting that exposure to higher numbers of risk factors, regardless of their exact nature, resulted in increased behaviour difficulties. The relationship between risk and behaviour difficulties was non-linear, with exposure to increasing risk having a disproportionate and detrimental impact on behaviour difficulties in child and adolescent models. Interventions aimed at reducing behaviour difficulties need to consider the impact of multiple risk variables. Tailoring interventions towards those exposed to large numbers of risks would be advantageous.

  18. Methodological Considerations in Screening for Cumulative Environmental Health Impacts: Lessons Learned from a Pilot Study in California

    Directory of Open Access Journals (Sweden)

    Lauren Zeise

    2012-08-01

    Full Text Available Polluting facilities and hazardous sites are often concentrated in low-income communities of color already facing additional stressors to their health. The influence of socioeconomic status is not considered in traditional models of risk assessment. We describe a pilot study of a screening method that considers both pollution burden and population characteristics in assessing the potential for cumulative impacts. The goal is to identify communities that warrant further attention and to thereby provide actionable guidance to decision- and policy-makers in achieving environmental justice. The method uses indicators related to five components to develop a relative cumulative impact score for use in comparing communities: exposures, public health effects, environmental effects, sensitive populations and socioeconomic factors. Here, we describe several methodological considerations in combining disparate data sources and report on the results of sensitivity analyses meant to guide future improvements in cumulative impact assessments. We discuss criteria for the selection of appropriate indicators, correlations between them, and consider data quality and the influence of choices regarding model structure. We conclude that the results of this model are largely robust to changes in model structure.

  19. Practical management of cumulative anthropogenic impacts with working marine examples

    DEFF Research Database (Denmark)

    Kyhn, Line Anker; Wright, Andrew J.

    2014-01-01

    for petroleum. Human disturbances, including the noise almost ubiquitously associated with human activity, are likely to increase the incidence, magnitude, and duration of adverse effects on marine life, including stress responses. Stress responses have the potential to induce fitness consequences...... for individuals, which add to more obvious directed takes (e.g., hunting or fishing) to increase the overall population-level impact. To meet the requirements of marine spatial planning and ecosystem-based management, many efforts are ongoing to quantify the cumulative impacts of all human actions on marine...... species or populations. Meanwhile, regulators face the challenge of managing these accumulating and interacting impacts with limited scientific guidance. We believe there is scientific support for capping the level of impact for (at a minimum) populations in decline or with unknown statuses. This cap...

  20. Ratcheting up the ratchet: on the evolution of cumulative culture.

    Science.gov (United States)

    Tennie, Claudio; Call, Josep; Tomasello, Michael

    2009-08-27

    Some researchers have claimed that chimpanzee and human culture rest on homologous cognitive and learning mechanisms. While clearly there are some homologous mechanisms, we argue here that there are some different mechanisms at work as well. Chimpanzee cultural traditions represent behavioural biases of different populations, all within the species' existing cognitive repertoire (what we call the 'zone of latent solutions') that are generated by founder effects, individual learning and mostly product-oriented (rather than process-oriented) copying. Human culture, in contrast, has the distinctive characteristic that it accumulates modifications over time (what we call the 'ratchet effect'). This difference results from the facts that (i) human social learning is more oriented towards process than product and (ii) unique forms of human cooperation lead to active teaching, social motivations for conformity and normative sanctions against non-conformity. Together, these unique processes of social learning and cooperation lead to humans' unique form of cumulative cultural evolution.

  1. Cumulative early life adversity predicts longevity in wild baboons.

    Science.gov (United States)

    Tung, Jenny; Archie, Elizabeth A; Altmann, Jeanne; Alberts, Susan C

    2016-04-19

    In humans and other animals, harsh circumstances in early life predict morbidity and mortality in adulthood. Multiple adverse conditions are thought to be especially toxic, but this hypothesis has rarely been tested in a prospective, longitudinal framework, especially in long-lived mammals. Here we use prospective data on 196 wild female baboons to show that cumulative early adversity predicts natural adult lifespan. Females who experience ≥3 sources of early adversity die a median of 10 years earlier than females who experience ≤1 adverse circumstances (median lifespan is 18.5 years). Females who experience the most adversity are also socially isolated in adulthood, suggesting that social processes partially explain the link between early adversity and adult survival. Our results provide powerful evidence for the developmental origins of health and disease and indicate that close ties between early adversity and survival arise even in the absence of health habit and health care-related explanations.

  2. Cumulative semantic interference for associative relations in language production.

    Science.gov (United States)

    Rose, Sebastian Benjamin; Abdel Rahman, Rasha

    2016-07-01

    Associations between conceptual representations and thematic relations play an important role in the organization of semantic memory. However, language production research on semantic context effects shows that associative (e.g., dog and bone) and categorical relations (dog and horse) seem to diverge. While categorical contexts typically induce semantic interference that has traditionally been taken to reflect competitive lexical selection, evidence for comparable associative modulations is rare. In three experiments we tested whether thematic associations between objects induce cumulative interference in the continuous naming paradigm, assuming that this paradigm hampers lexical selection via the activation of highly active lexical cohorts steadily increasing in size. Indeed, naming times increased linearly with each newly named member of thematic contexts irrespective of the pre-activation of associations before the naming task (Experiment 1), and irrespective of whether categorical links were partially included (Experiments 1 and 2) or entirely absent (Experiment 3). These findings demonstrate that different types of semantic relations induce interference.

  3. The modified cumulant expansion for two-dimensional isotropic turbulence

    Science.gov (United States)

    Tatsumi, T.; Yanase, S.

    1981-09-01

    The two-dimensional isotropic turbulence in an incompressible fluid is investigated using the modified zero fourth-order cumulant approximation. The dynamical equation for the energy spectrum obtained under this approximation is solved numerically and the similarity laws governing the solution in the energy-containing and enstrophy-dissipation ranges are derived analytically. At large Reynolds numbers the numerical solutions yield the k to the -3rd power inertial subrange spectrum which was predicted by Kraichnan (1967), Leith (1968) and Batchelor (1969), assuming a finite enstrophy dissipation in the inviscid limit. The energy-containing range is found to satisfy an inviscid similarity while the enstrophy-dissipation range is governed by the quasi-equilibrium similarity with respect to the enstrophy dissipation as proposed by Batchelor (1969). There exists a critical time which separates the initial period and the similarity period in which the enstrophy dissipation vanishes and remains non-zero respectively in the inviscid limit.

  4. The Role of Sister Cities’ Staff Exchanges in Developing “Learning Cities”: Exploring Necessary and Sufficient Conditions in Social Capital Development Utilizing Proportional Odds Modeling

    Directory of Open Access Journals (Sweden)

    Patrick Henry Buckley

    2015-06-01

    Full Text Available In the last half century former international adversaries have become cooperators through networking and knowledge sharing for decision making aimed at improving quality of life and sustainability; nowhere has this been more striking then at the urban level where such activity is seen as a key component in building “learning cities” through the development of social capital. Although mega-cities have been leaders in such efforts, mid-sized cities with lesser resource endowments have striven to follow by focusing on more frugal sister city type exchanges. The underlying thesis of our research is that great value can be derived from city-to-city exchanges through social capital development. However, such a study must differentiate between necessary and sufficient conditions. Past studies assumed necessary conditions were met and immediately jumped to demonstrating the existence of structural relationships by measuring networking while further assuming that the existence of such demonstrated a parallel development of cognitive social capital. Our research addresses this lacuna by stepping back and critically examining these assumptions. To accomplish this goal we use a Proportional Odds Modeling with a Cumulative Logit Link approach to demonstrate the existence of a common latent structure, hence asserting that necessary conditions are met.

  5. Is uveitis associated with topiramate use? A cumulative review

    Directory of Open Access Journals (Sweden)

    Goldberg JL

    2016-08-01

    Full Text Available Jeffrey L Goldberg,1 Amy G Lau,2 Bo Fan,2 Lisa Ford,3 Howard E Greenberg3 1Byers Eye Institute, Stanford University, Palo Alto, CA, 2Janssen Research & Development, LLC, Horsham, PA, 3Janssen Research & Development, LLC, Titusville, NJ, USA Abstract: Occasional reports of uveitis following topiramate use necessitated an investigation of relevant cases from safety databases and published biomedical literature. Data mining of the Food and Drug Administration Adverse Event Reporting System and cumulative review of cases from the global safety database (sponsor database and published literature were conducted to assess association between topiramate use and uveitis. The Food and Drug Administration Adverse Event Reporting System search identified disproportional reporting of uveitis (n=23 and related terms (choroidal detachment, n=25; iridocyclitis, n=17. The postmarketing reporting frequency of uveitis and related events from the global safety database and based on an estimated topiramate exposure of 11,185,740 person-years from launch to April 2015 was 0.38 per 100,000 person-years and assigned as very rare. A total of 14 potential uveitis cases were identified from the cumulative review. Seven of these 14 cases were complicated by inadequate documentation, appearance of uveitic signs following drug withdrawal, or concurrent use of other sulfonamides. In acute angle-closure glaucoma and uveal effusions cases, insufficient evidence for underlying inflammation suggested that uveitis was not a component. Only seven of 14 cases were well documented, potentially topiramate-associated uveitis cases. Uveitis may occur in the setting of topiramate use only in very rare instances. Current evidence did not reveal a dose- or duration-dependent relationship between uveitis and topiramate use. Keywords: topiramate, uveitis, acute angle-closure glaucoma, drug safety, Food and Drug Administration Adverse Event Reporting System, postmarketing 

  6. Economic and policy implications of the cumulative carbon budget

    Science.gov (United States)

    Allen, M. R.; Otto, F. E. L.; Otto, A.; Hepburn, C.

    2014-12-01

    The importance of cumulative carbon emissions in determining long-term risks of climate change presents considerable challenges to policy makers. The traditional notion of "total CO2-equivalent emissions", which forms the backbone of agreements such as the Kyoto Protocol and the European Emissions Trading System, is fundamentally flawed. Measures to reduce short-lived climate pollutants benefit the current generation, while measures to reduce long-lived climate pollutants benefit future generations, so there is no sense in which they can ever be considered equivalent. Debates over the correct metric used to compute CO2-equivalence are thus entirely moot: both long-lived and short-lived emissions will need to be addressed if all generations are to be protected from dangerous climate change. As far as long-lived climate pollutants are concerned, the latest IPCC report highlights the overwhelming importance of carbon capture and storage in determining the cost of meeting the goal of limiting anthropogenic warming to two degrees. We will show that this importance arises directly from the cumulative carbon budget and the role of CCS as the technology of last resort before economic activity needs to be restricted to meet ambitious climate targets. It highlights the need to increase the rate of CCS deployment by orders of magnitude if the option of avoiding two degrees is to be retained. The difficulty of achieving this speed of deployment through conventional incentives and carbon-pricing mechanisms suggests a need for a much more direct mandatory approach. Despite their theoretical economic inefficiency, the success of recent regulatory measures in achieving greenhouse gas emissions reductions in jurisdictions such as the United States suggests an extension of the regulatory approach could be a more effective and politically acceptable means of achieving adequately rapid CCS deployment than conventional carbon taxes or cap-and-trade systems.

  7. The dependence of cumulative 238U(n,f) fission yield on incident-neutron energy

    Institute of Scientific and Technical Information of China (English)

    ZHENG Na; ZHONG Chunlai; MA Liyong; CHEN Zhongjing; LI Xiangqing; LIU Tingjin; CHEN Jinxiang; FAN Tieshuan

    2009-01-01

    This work is aim at studying the dependence of fission yields on incident neutron energy,so as to produce evaluated yield sets of the energy dependence.Experimental data at different neutron energies for gas fission products 85m,87,88Kr and 138Xe resulting from the 238U(n,f) reaction are processed using codes AVERAGE for weighed average and ZOTT for simultaneous evaluation.Energy dependence of the cumulative fission product yields on the incident neutron is presented.The evaluated curve of product yield is compared with the results calculated by the TALYS-0.64 code.The present evaluation is consistent with other main libraries in error permission.The fit curve of 87,88Kr can be recommended to predict the unmeasured fission yields.Comparisons of the evaluated energy dependence curves with theoretical calculated results show that the predictions using purely theoretical model for the fission process are not sufficiently accurate and reliable for the calculations of the cumulative fission yields for the 238U(n,f).

  8. Brains striving for coherence: Long-term cumulative plot formation in the default mode network.

    Science.gov (United States)

    Tylén, K; Christensen, P; Roepstorff, A; Lund, T; Østergaard, S; Donald, M

    2015-11-01

    Many everyday activities, such as engaging in conversation or listening to a story, require us to sustain attention over a prolonged period of time while integrating and synthesizing complex episodic content into a coherent mental model. Humans are remarkably capable of navigating and keeping track of all the parallel social activities of everyday life even when confronted with interruptions or changes in the environment. However, the underlying cognitive and neurocognitive mechanisms of such long-term integration and profiling of information remain a challenge to neuroscience. While brain activity is generally traceable within the short time frame of working memory (milliseconds to seconds), these integrative processes last for minutes, hours or even days. Here we report two experiments on story comprehension. Experiment I establishes a cognitive dissociation between our comprehension of plot and incidental facts in narratives: when episodic material allows for long-term integration in a coherent plot, we recall fewer factual details. However, when plot formation is challenged, we pay more attention to incidental facts. Experiment II investigates the neural underpinnings of plot formation. Results suggest a central role for the brain's default mode network related to comprehension of coherent narratives while incoherent episodes rather activate the frontoparietal control network. Moreover, an analysis of cortical activity as a function of the cumulative integration of narrative material into a coherent story reveals to linear modulations of right hemisphere posterior temporal and parietal regions. Together these findings point to key neural mechanisms involved in the fundamental human capacity for cumulative plot formation.

  9. Cumulant Based Harmonic Retrieval in Mixed Colored Gaussian and Non-Gaussian ARMA Noises

    Institute of Scientific and Technical Information of China (English)

    LI Shenghong; ZHU Hongwen

    2001-01-01

    This paper studies the problem of retrieving one-dimensional real harmonic signals in presence of mixed colored Gaussian and non-Gaussian autoregressive moving-average (ARMA) noises, and proposes a new approach to harmonic retrieval. In the approach, Hilbert transform is first used to transform the real noisy observed data into their complex form; and then, some kind of fourth-order cumulant,which is defined particularly, is employed to identify the autoregressive (AR) parameters of the colored non-Gaussian ARMA noise model; after the real noisy observed data are filtered with the identified AR parameters, cumulant based methods can be used to compute the frequencies and the amplitudes of the harmonics. The proposed new approach can be applied to retrieve one-dimensional real harmonic signals in mixed colored Gaussian and non-Gaussian ARMA noises, no matter whether there is quadratic phase coupling or not in the harmonic signals and no matter whether the distribution of the colored non-Gaussian ARMA noise is symmetrical or not. Simulation examples are presented to demonstrate its effectiveness.

  10. Variability of exposure and estimation of cumulative exposure in a manually operated coal mine

    Energy Technology Data Exchange (ETDEWEB)

    Mamuya, S.H.D.; Bratveit, M.; Mwaiselage, J.; Moen, B.E. [University of Bergen, Bergen (Norway). Center for International Health

    2006-10-15

    This study aims at estimating variability in exposure to respirable dust and assessing whether the a priori grouping by job team is appropriate for an exposure-response study on respiratory effects among workers in a manually operated coal mine in Tanzania. Furthermore, estimated exposure levels were used to calculate cumulative exposure. Full-shift personal respirable dust samples (n = 204) were collected from 141 randomly chosen workers at underground and surface work sites. The geometric mean exposure for respirable dust varied from 0.07 mg m{sup -3} for office workers to 1.96 mg m{sup -3} for the development team. The analogous range of respirable quartz exposure was 0.006-0.073 mg m{sup -3}. Variance components were estimated using random effect models. For most job teams the within-worker variance component was considerably higher than the between-worker variance component. For respirable dust the estimated attenuation of the linear exposure-response relationship was low (5.9%) when grouping by job team. Grouping by job team was considered appropriate for studying the association between current dust exposure and respiratory effects. Based on the estimated worker-specific mean exposure in the job teams, the arithmetic mean cumulative exposure for the 299 workers who participated in the epidemiological part of the study was 38.1 mg. yr m{sup -3} for respirable dust and 2.0 mg. yr m{sup -3} for quartz.

  11. Hunter-gatherer inter-band interaction rates: implications for cumulative culture.

    Directory of Open Access Journals (Sweden)

    Kim R Hill

    Full Text Available Our species exhibits spectacular success due to cumulative culture. While cognitive evolution of social learning mechanisms may be partially responsible for adaptive human culture, features of early human social structure may also play a role by increasing the number potential models from which to learn innovations. We present interview data on interactions between same-sex adult dyads of Ache and Hadza hunter-gatherers living in multiple distinct residential bands (20 Ache bands; 42 Hadza bands; 1201 dyads throughout a tribal home range. Results show high probabilities (5%-29% per year of cultural and cooperative interactions between randomly chosen adults. Multiple regression suggests that ritual relationships increase interaction rates more than kinship, and that affinal kin interact more often than dyads with no relationship. These may be important features of human sociality. Finally, yearly interaction rates along with survival data allow us to estimate expected lifetime partners for a variety of social activities, and compare those to chimpanzees. Hadza and Ache men are estimated to observe over 300 men making tools in a lifetime, whereas male chimpanzees interact with only about 20 other males in a lifetime. High intergroup interaction rates in ancestral humans may have promoted the evolution of cumulative culture.

  12. Hunter-gatherer inter-band interaction rates: implications for cumulative culture.

    Science.gov (United States)

    Hill, Kim R; Wood, Brian M; Baggio, Jacopo; Hurtado, A Magdalena; Boyd, Robert T

    2014-01-01

    Our species exhibits spectacular success due to cumulative culture. While cognitive evolution of social learning mechanisms may be partially responsible for adaptive human culture, features of early human social structure may also play a role by increasing the number potential models from which to learn innovations. We present interview data on interactions between same-sex adult dyads of Ache and Hadza hunter-gatherers living in multiple distinct residential bands (20 Ache bands; 42 Hadza bands; 1201 dyads) throughout a tribal home range. Results show high probabilities (5%-29% per year) of cultural and cooperative interactions between randomly chosen adults. Multiple regression suggests that ritual relationships increase interaction rates more than kinship, and that affinal kin interact more often than dyads with no relationship. These may be important features of human sociality. Finally, yearly interaction rates along with survival data allow us to estimate expected lifetime partners for a variety of social activities, and compare those to chimpanzees. Hadza and Ache men are estimated to observe over 300 men making tools in a lifetime, whereas male chimpanzees interact with only about 20 other males in a lifetime. High intergroup interaction rates in ancestral humans may have promoted the evolution of cumulative culture.

  13. Bayesian mixture models for spectral density estimation

    OpenAIRE

    Cadonna, Annalisa

    2017-01-01

    We introduce a novel Bayesian modeling approach to spectral density estimation for multiple time series. Considering first the case of non-stationary timeseries, the log-periodogram of each series is modeled as a mixture of Gaussiandistributions with frequency-dependent weights and mean functions. The implied model for the log-spectral density is a mixture of linear mean functionswith frequency-dependent weights. The mixture weights are built throughsuccessive differences of a logit-normal di...

  14. Pteropods on the edge: Cumulative effects of ocean acidification, warming, and deoxygenation

    Science.gov (United States)

    Bednaršek, Nina; Harvey, Chris J.; Kaplan, Isaac C.; Feely, Richard A.; Možina, Jasna

    2016-06-01

    We review the state of knowledge of the individual and community responses of euthecosome (shelled) pteropods in the context of global environmental change. In particular, we focus on their responses to ocean acidification, in combination with ocean warming and ocean deoxygenation, as inferred from a growing body of empirical literature, and their relatively nascent place in ecosystem-scale models. Our objectives are: (1) to summarize the threats that these stressors pose to pteropod populations; (2) to demonstrate that pteropods are strong candidate indicators for cumulative effects of OA, warming, and deoxygenation in marine ecosystems; and (3) to provide insight on incorporating pteropods into population and ecosystem models, which will help inform ecosystem-based management of marine resources under future environmental regimes.

  15. Quark cluster contribution to cumulative proton emission in fragmentation of carbon ions

    CERN Document Server

    Abramov, B M; Borodin, Yu A; Bulychjov, S A; Dukhovskoy, I A; Khanov, A I; Krutenkova, A P; Kulikov, V V; Martemyanov, M A; Matsyuk, M A; Turdakina, E N

    2013-01-01

    In the FRAGM experiment at heavy ion accelerator complex TWAC-ITEP, the proton yields at an angle 3.5$^\\circ$ have been measured at fragmentation of carbon ions at $T_0 = $ 0.6, 0.95 and 2.0 GeV/nucleon on beryllium target. The data are presented as invariant proton yields on cumulative variable $x$ in the range 0.9 < $x$ < 2.4. Proton spectra cover six orders of invariant cross section magnitude. They have been analyzed in the framework of quark cluster fragmentation model. Fragmentation functions of quark-gluon string model are used. The probabilities of the existence of multi-quark clusters in carbon nuclei are estimated to be 8--12% for six-quark clusters and 0.2--0.6% for nine-quark clusters.

  16. Comparison on models for genetic evaluation of non-return rate and success in first insemination of the Danish Holstein cow

    DEFF Research Database (Denmark)

    Sun, C; Su, G

    2010-01-01

    The aim of is study was to compare a linear Gaussian model with logit model and probit model for genetic evaluation of non-return rate within 56 d after first-insemination (NRR56) and success in first insemination (SFI). The whole dataset used in the analysis contained 471,742 records from...

  17. Role of baseline antral follicle count and anti-Mullerian hormone in prediction of cumulative live birth in the first in vitro fertilisation cycle: a retrospective cohort analysis.

    Science.gov (United States)

    Li, Hang Wun Raymond; Lee, Vivian Chi Yan; Lau, Estella Yee Lan; Yeung, William Shu Biu; Ho, Pak Chung; Ng, Ernest Hung Yu

    2013-01-01

    This retrospective study determined for the first time the role of baseline antral follicle count (AFC) and serum anti-Mullerian hormone (AMH) level in the first in-vitro fertilisation (IVF) cycle in predicting cumulative live birth from one stimulation cycle. We studied 1,156 women (median age 35 years) undergoing the first IVF cycle. Baseline AFC and AMH level on the day before ovarian stimulation were analysed. The main outcome measure was cumulative live birth in the fresh plus all the frozen embryo transfers after the same stimulation cycle. Serum AMH was significantly correlated with AFC. Both AMH and AFC showed significant correlation with age and ovarian response in the stimulated cycle and total number of transferrable embryos. Baseline AFC and serum AMH were significantly higher in subjects attaining a live birth than those who did not in the fresh stimulated cycle, as well as those attaining cumulative live birth. There was a significant trend of higher cumulative live birth rate in women with higher AMH or AFC. However, logistic regression revealed that both AMH and AFC were not significant predictors of cumulative live birth after adjusting for age and number of embryos available for transfer. Considering only one single predictor, the areas under the ROC curves for AMH (0.646, 95% CI 0.616-0.675) and age (0.648, 95% CI 0.618-0.677) were slightly higher than that for AFC (0.617, 95% CI 0.587-0.647) in predicting cumulative live birth. However, a model combining AMH (with or without AFC) and age of the women only classified an addition of less than 2% of subjects correctly compared to the model with age alone. Baseline AFC and serum AMH have only modest predictive performance on the occurrence of cumulative live birth, and may not give additional value on top of the women's age.

  18. On the proportionality between global temperature change and cumulative CO2 emissions during periods of net negative CO2 emissions

    Science.gov (United States)

    Zickfeld, Kirsten; MacDougall, Andrew H.; Damon Matthews, H.

    2016-05-01

    Recent research has demonstrated that global mean surface air warming is approximately proportional to cumulative CO2 emissions. This proportional relationship has received considerable attention, as it allows one to calculate the cumulative CO2 emissions (‘carbon budget’) compatible with temperature targets and is a useful measure for model inter-comparison. Here we use an Earth system model to explore whether this relationship persists during periods of net negative CO2 emissions. Negative CO2 emissions are required in the majority of emissions scenarios limiting global warming to 2 °C above pre-industrial, with emissions becoming net negative in the second half of this century in several scenarios. We find that for model simulations with a symmetric 1% per year increase and decrease in atmospheric CO2, the temperature change (ΔT) versus cumulative CO2 emissions (CE) relationship is nonlinear during periods of net negative emissions, owing to the lagged response of the deep ocean to previously increasing atmospheric CO2. When corrected for this lagged response, or if the CO2 decline is applied after the system has equilibrated with the previous CO2 increase, the ΔT versus CE relationship is close to linear during periods of net negative CO2 emissions. A proportionality constant—the transient climate response to cumulative carbon emissions (TCRE)- can therefore be calculated for both positive and net negative CO2 emission periods. We find that in simulations with a symmetric 1% per year increase and decrease in atmospheric CO2 the TCRE is larger on the upward than on the downward CO2 trajectory, suggesting that positive CO2 emissions are more effective at warming than negative emissions are at subsequently cooling. We also find that the cooling effectiveness of negative CO2 emissions decreases if applied at higher atmospheric CO2 concentrations.

  19. Quantifying process-based mitigation strategies in historical context: separating multiple cumulative effects on river meander migration.

    Directory of Open Access Journals (Sweden)

    Alexander K Fremier

    Full Text Available Environmental legislation in the US (i.e. NEPA requires defining baseline conditions on current rather than historical ecosystem conditions. For ecosystems with long histories of multiple environmental impacts, this baseline method can subsequently lead to a significantly altered environment; this has been termed a 'sliding baseline'. In river systems, cumulative effects caused by flow regulation, channel revetment and riparian vegetation removal significantly impact floodplain ecosystems by altering channel dynamics and precluding subsequent ecosystem processes, such as primary succession. To quantify these impacts on floodplain development processes, we used a model of river channel meander migration to illustrate the degree to which flow regulation and riprap impact migration rates, independently and synergistically, on the Sacramento River in California, USA. From pre-dam conditions, the cumulative effect of flow regulation alone on channel migration is a reduction by 38%, and 42-44% with four proposed water diversion project scenarios. In terms of depositional area, the proposed water project would reduce channel migration 51-71 ha in 130 years without current riprap in place, and 17-25 ha with riprap. Our results illustrate the utility of a modeling approach for quantifying cumulative impacts. Model-based quantification of environmental impacts allow scientists to separate cumulative and synergistic effects to analytically define mitigation measures. Additionally, by selecting an ecosystem process that is affected by multiple impacts, it is possible to consider process-based mitigation scenarios, such as the removal of riprap, to allow meander migration and create new floodplains and allow for riparian vegetation recruitment.

  20. Effects of the hydraulic conductivity of the matrix/macropore interface on cumulative infiltrations into dual-permeability media

    Science.gov (United States)

    Lassabatere, L.; Peyrard, X.; Angulo-Jaramillo, R.; Simunek, J.

    2009-12-01

    Modeling of water infiltration into the vadose zone is important for better understanding of movement of water-transported contaminants. There is a great need to take into account the soil heterogeneity and, in particular, the presence of macropores or cracks that could generate preferential flow. Several mathematical models have been proposed to describe unsaturated flow through heterogeneous soils. The dual-permeability model (referred to as the 2K model) assumes that flow is governed by Richards equation in both porous regions (matrix and macropores). Water can be exchanged between the two regions following a first-order rate law. Although several studies have dealt with such modeling, no study has evaluated the influence of the hydraulic conductivity of the matrix/macropore interface on water cumulative infiltration. And this is the focus of this study. An analytical scaling method reveals the role of the following main parameters for given boundary and initial conditions: the saturated hydraulic conductivity ratio (R_Ks), the water pressure scale parameter ratio (R_hg), the saturated volumetric water content ratio (R_θs), and the shape parameters of the water retention and hydraulic conductivity functions. The last essential parameter is related to the interfacial hydraulic conductivity (Ka) between the macropore and matrix regions. The scaled 2K flow equations were solved using HYDRUS-1D 4.09 for the specific case of water infiltrating into an initially uniform soil profile and a zero pressure head at the soil surface. A sensitivity of water infiltration was studied for different sets of scale parameters (R_Ks, R_hg, R_θs, and shape parameters) and the scaled interfacial conductivity (Ka). Numerical results illustrate two extreme behaviors. When the interfacial conductivity is zero (i.e., no water exchange), water infiltrates separately into matrix and macropore regions, producing a much deeper moisture front in the macropore domain. In the opposite case