Formal Derivation of Lotka-Volterra-Haken Amplitude Equations of Task-Related Brain Activity in Multiple, Consecutively Performed Tasks

NASA Astrophysics Data System (ADS)

Frank, T. D.

The Lotka-Volterra-Haken equations have been frequently used in ecology and pattern formation. Recently, the equations have been proposed by several research groups as amplitude equations for task-related patterns of brain activity. In this theoretical study, the focus is on the circular causality aspect of pattern formation systems as formulated within the framework of synergetics. Accordingly, the stable modes of a pattern formation system inhibit the unstable modes, whereas the unstable modes excite the stable modes. Using this circular causality principle it is shown that under certain conditions the Lotka-Volterra-Haken amplitude equations can be derived from a general model of brain activity akin to the Wilson-Cowan model. The model captures the amplitude dynamics for brain activity patterns in experiments involving several consecutively performed multiple-choice tasks. This is explicitly demonstrated for two-choice tasks involving grasping and walking. A comment on the relevance of the theoretical framework for clinical psychology and schizophrenia is given as well.

Controlling factors of the parental safety perception on children's travel mode choice.

PubMed

Nevelsteen, Kristof; Steenberghen, Thérèse; Van Rompaey, Anton; Uyttersprot, Liesbeth

2012-03-01

The travel mode of children changed significantly over the last 20 years, with a decrease of children travelling as pedestrians or cyclists. This study focuses on six to twelve year old children. Parents determine to a large extent the mode choice of children in this age category. Based on the analysis of an extensive survey, the research shows that traffic infrastructure has a significant impact on parental decision making concerning children's travel mode choice, by affecting both the real and the perceived traffic safety. Real traffic safety is quantified in terms of numbers of accidents and road infrastructure. For the perceived traffic safety a parental allowance probability is calculated per road type to show that infrastructure characteristics influence parental decision making on the children's mode choice. A binary logistic model shows that this allowance is determined by age, gender and traffic infrastructure near the child's home or near destinations frequently visited by children. Since both real and perceived traffic safety are influenced by infrastructure characteristics, a spatial analysis of parental perception and accident statistics can be used to indicate the locations where infrastructure improvements will be most effective to increase the number of children travelling - safely - as pedestrians or cyclists. Copyright © 2011 Elsevier Ltd. All rights reserved.

The role of consensus and culture in children's imitation of inefficient actions.

PubMed

DiYanni, Cara J; Corriveau, Kathleen H; Kurkul, Katelyn; Nasrini, Jad; Nini, Deniela

2015-09-01

A significant body of work has demonstrated children's imitative abilities when learning novel actions. Although some research has examined the role of cultural background in children's imitation of inefficient actions, to our knowledge no research has explored how culture and conformity interact when engaging in imitation. In Study 1, 87 Caucasian American and Chinese American preschoolers were presented with either one model or three models performing an inefficient action. Whereas there were no cultural differences in imitation in the Single Model condition, Chinese Americans were significantly more likely to copy the model's preference for an inefficient tool in the Consensus condition. Children's tool choice was associated with their justification for their choice as well as their memory for the model's action. Study 2 explored the impact of immigration status on the cultural differences in children's tool choice by including 16 first-generation Caucasian American children. When comparing the findings with the rates from Study 1, both groups of Caucasian American preschoolers imitated at rates significantly lower than the Chinese American preschoolers. We suggest that the tool choices of Caucasian American children relate to a tendency to engage in a perceptually driven mode of learning, whereas the choices of the Chinese American children reflect a greater likelihood to use a socially driven mode. Copyright © 2015 Elsevier Inc. All rights reserved.

Freight Demand Characteristics and Mode Choice: An Analysis of the Results of Modeling with Disaggregate Revealed Preference Data

DOT National Transportation Integrated Search

1999-12-01

This paper analyzes the freight demand characteristics that drive modal choice by means of a large scale, national, disaggregate revealed preference database for shippers in France in 1988, using a nested logit. Particular attention is given to priva...

Development of weekend travel demand and mode choice models : final report, June 2009.

DOT National Transportation Integrated Search

2010-06-30

Travel demand models are widely used for forecasting and analyzing policies for automobile and transit travel. However, these models are typically developed for average weekday travel when regular activities are routine. The weekday models focus prim...

Lesions of dorsal striatum eliminate lose-switch responding but not mixed-response strategies in rats.

PubMed

Skelin, Ivan; Hakstol, Rhys; VanOyen, Jenn; Mudiayi, Dominic; Molina, Leonardo A; Holec, Victoria; Hong, Nancy S; Euston, David R; McDonald, Robert J; Gruber, Aaron J

2014-05-01

We used focal brain lesions in rats to examine how dorsomedial (DMS) and dorsolateral (DLS) regions of the striatum differently contribute to response adaptation driven by the delivery or omission of rewards. Rats performed a binary choice task under two modes: one in which responses were rewarded on half of the trials regardless of choice; and another 'competitive' one in which only unpredictable choices were rewarded. In both modes, control animals were more likely to use a predictable lose-switch strategy than animals with lesions of either DMS or DLS. Animals with lesions of DMS presumably relied more on DLS for behavioural control, and generated repetitive responses in the first mode. These animals then shifted to a random response strategy in the competitive mode, thereby performing better than controls or animals with DLS lesions. Analysis using computational models of reinforcement learning indicated that animals with striatal lesions, particularly of the DLS, had blunted reward sensitivity and less stochasticity in the choice mechanism. These results provide further evidence that the rodent DLS is involved in rapid response adaptation that is more sophisticated than that embodied by the classic notion of habit formation driven by gradual stimulus-response learning. © 2014 Federation of European Neuroscience Societies and John Wiley & Sons Ltd.

Cargo Logistics Airlift Systems Study (CLASS). Volume 2: Case study approach and results

NASA Technical Reports Server (NTRS)

Burby, R. J.; Kuhlman, W. H.

1978-01-01

Models of transportation mode decision making were developed. The user's view of the present and future air cargo systems is discussed. Issues summarized include: (1) organization of the distribution function; (2) mode choice decision making; (3) air freight system; and (4) the future of air freight.

Integrated Mode Choice, Small Aircraft Demand, and Airport Operations Model User's Guide

NASA Technical Reports Server (NTRS)

Yackovetsky, Robert E. (Technical Monitor); Dollyhigh, Samuel M.

2004-01-01

A mode choice model that generates on-demand air travel forecasts at a set of GA airports based on changes in economic characteristics, vehicle performance characteristics such as speed and cost, and demographic trends has been integrated with a model to generate itinerate aircraft operations by airplane category at a set of 3227 airports. Numerous intermediate outputs can be generated, such as the number of additional trips diverted from automobiles and schedule air by the improved performance and cost of on-demand air vehicles. The total number of transported passenger miles that are diverted is also available. From these results the number of new aircraft to service the increased demand can be calculated. Output from the models discussed is in the format to generate the origin and destination traffic flow between the 3227 airports based on solutions to a gravity model.

An integrated framework for modeling freight mode and route choice.

DOT National Transportation Integrated Search

2013-10-01

A number of statewide travel demand models have included freight as a separate component in analysis. Unlike : passenger travel, freight has not gained equivalent attention because of lack of data and difficulties in modeling. In : the current state ...

Applications manual for logit modes of express bus-fringe parking choices.

DOT National Transportation Integrated Search

1976-01-01

Manual computations and computerized applications of logit models are described. The models demonstrated reflect travel behavior concerning express bus-fringe parking transit. The specific travel issues addressed include the basic automobile vs. expr...

Do labeled versus unlabeled treatments of alternatives' names influence stated choice outputs? Results from a mode choice study.

PubMed

Jin, Wen; Jiang, Hai; Liu, Yimin; Klampfl, Erica

2017-01-01

Discrete choice experiments have been widely applied to elicit behavioral preferences in the literature. In many of these experiments, the alternatives are named alternatives, meaning that they are naturally associated with specific names. For example, in a mode choice study, the alternatives can be associated with names such as car, taxi, bus, and subway. A fundamental issue that arises in stated choice experiments is whether to treat the alternatives' names as labels (that is, labeled treatment), or as attributes (that is, unlabeled treatment) in the design as well as the presentation phases of the choice sets. In this research, we investigate the impact of labeled versus unlabeled treatments of alternatives' names on the outcome of stated choice experiments, a question that has not been thoroughly investigated in the literature. Using results from a mode choice study, we find that the labeled or the unlabeled treatment of alternatives' names in either the design or the presentation phase of the choice experiment does not statistically affect the estimates of the coefficient parameters. We then proceed to measure the influence toward the willingness-to-pay (WTP) estimates. By using a random-effects model to relate the conditional WTP estimates to the socioeconomic characteristics of the individuals and the labeled versus unlabeled treatments of alternatives' names, we find that: a) Given the treatment of alternatives' names in the presentation phase, the treatment of alternatives' names in the design phase does not statistically affect the estimates of the WTP measures; and b) Given the treatment of alternatives' names in the design phase, the labeled treatment of alternatives' names in the presentation phase causes the corresponding WTP estimates to be slightly higher.

Do labeled versus unlabeled treatments of alternatives’ names influence stated choice outputs? Results from a mode choice study

PubMed Central

Jin, Wen; Jiang, Hai; Liu, Yimin; Klampfl, Erica

2017-01-01

Discrete choice experiments have been widely applied to elicit behavioral preferences in the literature. In many of these experiments, the alternatives are named alternatives, meaning that they are naturally associated with specific names. For example, in a mode choice study, the alternatives can be associated with names such as car, taxi, bus, and subway. A fundamental issue that arises in stated choice experiments is whether to treat the alternatives’ names as labels (that is, labeled treatment), or as attributes (that is, unlabeled treatment) in the design as well as the presentation phases of the choice sets. In this research, we investigate the impact of labeled versus unlabeled treatments of alternatives’ names on the outcome of stated choice experiments, a question that has not been thoroughly investigated in the literature. Using results from a mode choice study, we find that the labeled or the unlabeled treatment of alternatives’ names in either the design or the presentation phase of the choice experiment does not statistically affect the estimates of the coefficient parameters. We then proceed to measure the influence toward the willingness-to-pay (WTP) estimates. By using a random-effects model to relate the conditional WTP estimates to the socioeconomic characteristics of the individuals and the labeled versus unlabeled treatments of alternatives’ names, we find that: a) Given the treatment of alternatives’ names in the presentation phase, the treatment of alternatives’ names in the design phase does not statistically affect the estimates of the WTP measures; and b) Given the treatment of alternatives’ names in the design phase, the labeled treatment of alternatives’ names in the presentation phase causes the corresponding WTP estimates to be slightly higher. PMID:28806764

A high resolution agent-based model to support walk-bicycle infrastructure investment decisions: A case study with New York City

DOE PAGES

Aziz, H. M. Abdul; Park, Byung H.; Morton, April M.; ...

2017-11-24

Active transportation modes--walk and bicycle--are central for low carbon transport, healthy living, and complete streets initiative. Building a community with amenable walk and bicycle facilities asks for smart planning and investments. It is critical to investigate the impact of infrastructure building or expansion on the overall walk and bicycle mode usage prior to making investment choices utilizing public tax money. This research developed an agent-based model to support investment decisions that allows to assess the impact of changes in walk-bike infrastructures at a high spatial resolution (e.g., block group level). The agent-based model (ABM) utilizes data from a synthetic populationmore » simulator generating agents with corresponding socio-demographic characteristics, and integrates facility attributes regarding walking and bicycling (e.g., sidewalk width, bike lane length) into the mode choice decision making process. Moreover, the ABM accounts for the effect of social interactions among agents who live and work at the same geographic locations. Finally, GIS-based maps are developed at block group resolution that allows exploring the effect of walk-bike infrastructure related investments. The results from New York City case study indicate that infrastructure investments such as widening sidewalk and increasing bike lane network can positively influence the active transportation mode choices. In addition, the level of impact varies with geographic locations--different boroughs of New York City will have different impacts. Lastly, social promotions resulting in higher social interaction among agents can reinforce the impacts of infrastructure changes.« less

A high resolution agent-based model to support walk-bicycle infrastructure investment decisions: A case study with New York City

DOE Office of Scientific and Technical Information (OSTI.GOV)

Aziz, H. M. Abdul; Park, Byung H.; Morton, April M.

Active transportation modes--walk and bicycle--are central for low carbon transport, healthy living, and complete streets initiative. Building a community with amenable walk and bicycle facilities asks for smart planning and investments. It is critical to investigate the impact of infrastructure building or expansion on the overall walk and bicycle mode usage prior to making investment choices utilizing public tax money. This research developed an agent-based model to support investment decisions that allows to assess the impact of changes in walk-bike infrastructures at a high spatial resolution (e.g., block group level). The agent-based model (ABM) utilizes data from a synthetic populationmore » simulator generating agents with corresponding socio-demographic characteristics, and integrates facility attributes regarding walking and bicycling (e.g., sidewalk width, bike lane length) into the mode choice decision making process. Moreover, the ABM accounts for the effect of social interactions among agents who live and work at the same geographic locations. Finally, GIS-based maps are developed at block group resolution that allows exploring the effect of walk-bike infrastructure related investments. The results from New York City case study indicate that infrastructure investments such as widening sidewalk and increasing bike lane network can positively influence the active transportation mode choices. In addition, the level of impact varies with geographic locations--different boroughs of New York City will have different impacts. Lastly, social promotions resulting in higher social interaction among agents can reinforce the impacts of infrastructure changes.« less

Multimodal Likelihoods in Educational Assessment: Will the Real Maximum Likelihood Score Please Stand up?

ERIC Educational Resources Information Center

Wothke, Werner; Burket, George; Chen, Li-Sue; Gao, Furong; Shu, Lianghua; Chia, Mike

2011-01-01

It has been known for some time that item response theory (IRT) models may exhibit a likelihood function of a respondent's ability which may have multiple modes, flat modes, or both. These conditions, often associated with guessing of multiple-choice (MC) questions, can introduce uncertainty and bias to ability estimation by maximum likelihood…

Nurse/physician conflict management mode choices: implications for improved collaborative practice.

PubMed

Hendel, Tova; Fish, Miri; Berger, Ornit

2007-01-01

In today's complex healthcare organizations, conflicts between physicians and nurses occur daily. Consequently, organizational conflict has grown into a major subfield of organizational behavior. Researchers have claimed that conflict has a beneficial effect on work group function and identified collaboration as one of the intervening variables that may explain the relationship between magnet hospitals and positive patient outcomes. The purpose of this study was to identify and compare conflict mode choices of physicians and head nurses in acute care hospitals and examine the relationship of conflict mode choices with their background characteristics. In a cross-sectional correlational study, 75 physicians and 54 head nurses in 5 hospitals were surveyed, using the Thomas-Kilmann Conflict Mode Instrument. No difference was found between physicians and nurses in choice of the most frequently used mode in conflict management. The compromising mode was found to be the significantly most commonly chosen mode (P = .00) by both. Collaborating was chosen significantly more frequently among head nurses (P = .001) and least frequently among physicians (P = .00). Most of the respondents' characteristics were not found to be correlated with mode choices. The findings indicate a need to enhance partnerships in the clinical environment to ensure quality patient care and staff satisfaction.

Incorporating social impact on new product adoption in choice modeing: A case study in green vehicles

DOE Office of Scientific and Technical Information (OSTI.GOV)

He, Lin; Wang, Mingxian; Chen, Wei

While discrete choice analysis is prevalent in capturing consumer preferences and describing their choice behaviors in product design, the traditional choice modeling approach assumes that each individual makes independent decisions, without considering the social impact. However, empirical studies show that choice is social - influenced by many factors beyond engineering performance of a product and consumer attributes. To alleviate this limitation, we propose a new choice modeling framework to capture the dynamic influence from social networks on consumer adoption of new products. By introducing social influence attributes into a choice utility function, social network simulation is integrated with the traditionalmore » discrete choice analysis in a three-stage process. Our study shows the need for considering social impact in forecasting new product adoption. Using hybrid electric vehicles as an example, our work illustrates the procedure of social network construction, social influence evaluation, and choice model estimation based on data from the National Household Travel Survey. Our study also demonstrates several interesting findings on the dynamic nature of new technology adoption and how social networks may influence hybrid electric vehicle adoption. (C) 2014 Elsevier Ltd. All rights reserved« less

Exploring the impact of walk–bike infrastructure, safety perception, and built-environment on active transportation mode choice: a random parameter model using New York City commuter data

DOE PAGES

Aziz, H. M. Abdul; Nagle, Nicholas N.; Morton, April M.; ...

2017-02-06

Here, this study finds the effects of traffic safety, walk-bike network facilities, and land use attributes on walk and bicycle mode choice decision in the New York City for home-to-work commute. Applying the flexible econometric structure of random parameter models, we capture the heterogeneity in the decision making process and simulate scenarios considering improvement in walk-bike infrastructure such as sidewalk width and length of bike lane. Our results indicate that increasing sidewalk width, total length of bike lane, and proportion of protected bike lane will increase the likelihood of more people taking active transportation mode This suggests that the localmore » authorities and planning agencies to invest more on building and maintaining the infrastructure for pedestrians. Furthermore, improvement in traffic safety by reducing traffic crashes involving pedestrians and bicyclists will increase the likelihood of taking active transportation modes. Our results also show positive correlation between number of non-motorized trips by the other family members and the likelihood to choose active transportation mode. The findings will help to make smart investment decisions in context of building sustainable transportation systems accounting for active transportation.« less

Exploring the impact of walk–bike infrastructure, safety perception, and built-environment on active transportation mode choice: a random parameter model using New York City commuter data

DOE Office of Scientific and Technical Information (OSTI.GOV)

Aziz, H. M. Abdul; Nagle, Nicholas N.; Morton, April M.

Here, this study finds the effects of traffic safety, walk-bike network facilities, and land use attributes on walk and bicycle mode choice decision in the New York City for home-to-work commute. Applying the flexible econometric structure of random parameter models, we capture the heterogeneity in the decision making process and simulate scenarios considering improvement in walk-bike infrastructure such as sidewalk width and length of bike lane. Our results indicate that increasing sidewalk width, total length of bike lane, and proportion of protected bike lane will increase the likelihood of more people taking active transportation mode This suggests that the localmore » authorities and planning agencies to invest more on building and maintaining the infrastructure for pedestrians. Furthermore, improvement in traffic safety by reducing traffic crashes involving pedestrians and bicyclists will increase the likelihood of taking active transportation modes. Our results also show positive correlation between number of non-motorized trips by the other family members and the likelihood to choose active transportation mode. The findings will help to make smart investment decisions in context of building sustainable transportation systems accounting for active transportation.« less

On the development of a semi-nonparametric generalized multinomial logit model for travel-related choices

PubMed Central

Ye, Xin; Pendyala, Ram M.; Zou, Yajie

2017-01-01

A semi-nonparametric generalized multinomial logit model, formulated using orthonormal Legendre polynomials to extend the standard Gumbel distribution, is presented in this paper. The resulting semi-nonparametric function can represent a probability density function for a large family of multimodal distributions. The model has a closed-form log-likelihood function that facilitates model estimation. The proposed method is applied to model commute mode choice among four alternatives (auto, transit, bicycle and walk) using travel behavior data from Argau, Switzerland. Comparisons between the multinomial logit model and the proposed semi-nonparametric model show that violations of the standard Gumbel distribution assumption lead to considerable inconsistency in parameter estimates and model inferences. PMID:29073152

On the development of a semi-nonparametric generalized multinomial logit model for travel-related choices.

PubMed

Wang, Ke; Ye, Xin; Pendyala, Ram M; Zou, Yajie

2017-01-01

A semi-nonparametric generalized multinomial logit model, formulated using orthonormal Legendre polynomials to extend the standard Gumbel distribution, is presented in this paper. The resulting semi-nonparametric function can represent a probability density function for a large family of multimodal distributions. The model has a closed-form log-likelihood function that facilitates model estimation. The proposed method is applied to model commute mode choice among four alternatives (auto, transit, bicycle and walk) using travel behavior data from Argau, Switzerland. Comparisons between the multinomial logit model and the proposed semi-nonparametric model show that violations of the standard Gumbel distribution assumption lead to considerable inconsistency in parameter estimates and model inferences.

Discrete-choice modelling of patient preferences for modes of drug administration.

PubMed

Tetteh, Ebenezer Kwabena; Morris, Steve; Titcheneker-Hooker, Nigel

2017-12-01

The administration of (biologically-derived) drugs for various disease conditions involves consumption of resources that constitutes a direct monetary cost to healthcare payers and providers. An often ignored cost relates to a mismatch between patients' preferences and the mode of drug administration. The "intangible" benefits of giving patients what they want in terms of the mode of drug delivery is seldom considered. This study aims to evaluate, in monetary terms, end-user preferences for the non-monetary attributes of different modes of drug administration using a discrete-choice experiment. It provides empirical support to the notion that there are significant benefits from developing patient-friendly approaches to drug delivery. The gross benefits per patient per unit administration is in the same order of magnitude as the savings in resource costs of administering drugs. The study argues that, as long as the underlying manufacturing science is capable, a patient-centred approach to producing drug delivery systems should be encouraged and pursued.

Selection of experimental modal data sets for damage detection via model update

NASA Technical Reports Server (NTRS)

Doebling, S. W.; Hemez, F. M.; Barlow, M. S.; Peterson, L. D.; Farhat, C.

1993-01-01

When using a finite element model update algorithm for detecting damage in structures, it is important that the experimental modal data sets used in the update be selected in a coherent manner. In the case of a structure with extremely localized modal behavior, it is necessary to use both low and high frequency modes, but many of the modes in between may be excluded. In this paper, we examine two different mode selection strategies based on modal strain energy, and compare their success to the choice of an equal number of modes based merely on lowest frequency. Additionally, some parameters are introduced to enable a quantitative assessment of the success of our damage detection algorithm when using the various set selection criteria.

Workshop presentation.

DOT National Transportation Integrated Search

2013-12-01

On December 18, 2013, the research team hosted a workshop at CTR to gather feedback on and : generate discussion of the mode choice model that was developed. : Attendees included the project monitoring committee (PMC) and TTI personnel who staff a he...

Cost and performance tradeoffs between mail and internet survey modes in a nonmarket valuation study

Treesearch

Robert M. Campbell; Tyron Venn; Nathaniel M. Anderson

2018-01-01

Using the results of a choice modeling survey, internet, mail-only and mixed internet and mail survey modes were examined with regards to their cost-effectiveness, representativeness, and willingness to pay (WTP). The topical focus of the study was biomass energy generation preferences of the residents of Montana, Colorado and Arizona, USA. Compared to the mail and...

Vehicle emissions during children's school commuting: impacts of education policy.

PubMed

Marshall, Julian D; Wilson, Ryan D; Meyer, Katie L; Rajangam, Santhosh K; McDonald, Noreen C; Wilson, Elizabeth J

2010-03-01

We explore how school policies influence the environmental impacts of school commutes. Our research is motivated by increased interest in school choice policies (in part because of the U.S. "No Child Left Behind" Act) and in reducing bus service to address recent budget shortfalls. Our analysis employs two samples of elementary-age children, age 5-12: a travel survey (n = 1246 respondents) and a school enrollment data set (n = 19,655 students). Multinomial logistic regression modeled the determinants of travel mode (automobile, school bus, and walking; n = 803 students meeting selection criteria). Travel distance has the single greatest effect on travel mode, though school choice, trip direction (to- or from-school), and grade play a role. Several policies were investigated quantitatively to predict the impact on school travel, vehicle emissions, and costs. We find that eliminating district-wide school choice (i.e., returning to a system with neighborhood schools only) would have significant impacts on transport modes and emissions, whereas in many cases proposed shifts in school choice and bus-provision policies would have only modest impacts. Policies such as school choice and school siting may conflict with the goal of increasing rates of active (i.e., nonmotorized) school commuting. Policies that curtail bus usage may reduce bus emissions but yield even larger increases in private-vehicle emissions. Our findings underscore the need to critically evaluate transportation-related environmental and health impacts of currently proposed changes in school policy.

Effect of a School Choice Policy Change on Active Commuting to Elementary School.

PubMed

Sirard, John R; McDonald, Kelsey; Mustain, Patrick; Hogan, Whitney; Helm, Alison

2015-01-01

The purposes of this study were to assess the effect of restricting school choice on changes in travel distance to school and transportation mode for elementary school students. Study design was pre-post (spring 2010-fall 2010) quasi-experimental. Study setting was all public elementary schools in Minneapolis, Minnesota. Subjects comprised approximately 20,500 students across 39 schools. Study assessed a school choice policy change that restricted school choice to a school closer to the family's home. School district transportation data were used to determine distance to school. Direct observations of student travel modes (two morning and two afternoon commutes at each time point) were used to assess transportation mode. Chi-square and independent-sample t-tests were calculated to describe the schools. Repeated measures general linear models were used to assess changes in travel distance to school and observed commuting behavior. Distance to school significantly decreased (1.83 ± .48 miles to 1.74 ± .46 miles; p = .002). We failed to observe any significant changes in morning (+.7%) or afternoon (-.7%) active commuting (both p = .08) or the number of automobiles in the morning (-7 autos per school; p = .06) or afternoon (+3 autos per school; p = .14). The more restrictive school choice policy decreased distance to school but had no significant effect on active commuting. Policy interventions designed to increase active commuting to school may require additional time to gain traction and programmatic support to induce changes in behavior.

A preliminary survey on mode choice and its effect in users’ satisfaction on their journey to the railway station

NASA Astrophysics Data System (ADS)

Ali, Nur Fahriza Mohd; Sadullah, Ahmad Farhan Mohd; Zulkiple, Adnan

2018-04-01

This paper focuses on two lines of investigation with regard to mode choice to Klang Komuter Station. Firstly, the profile of the access modes on journeys to the railway station is analysed. Secondly, the relationship of users’ mode choice towards overall perception on traveling from home to the railway station is estimated. The data collection was conducted via Revealed Preferences / Stated Preferences (RP/SP) Survey. Meanwhile, the analysis that was implemented in this study was correspondence analysis. This paper discussed more on journey purposes and the effects of distances from home to the railway, users’ trip purposes and travel time between car and bus that was found to have an important effect on the users’ mode choice and their satisfaction on their journey to the railway station. The results show that users were more satisfied to reach the station by car instead of the bus.

A dynamic framework on travel mode choice focusing on utilitarian walking based on the integration of current knowledge.

PubMed

Yang, Yong

2016-09-01

Recently, research on utilitarian walking has gained momentum due to its benefits on both health and the environment. However, our overall understanding of how built and social environments affect travel mode choice (walking or not) is still limited, and most existing frameworks on travel mode choice lack dynamic processes. After a review of several mainstream theories and a number of frameworks, we propose an integrated framework. The basic constructs in the travel mode choice function are utilities, constraints, attitudes, and habits. With a hierarchical structure and heuristic rules, the travel mode choice function is modified by individual characteristics and travel characteristics. The framework explicitly presents several dynamic processes, including the perception process on the environment, attitude formation process, habit formation process, interactions among an individual's own behaviors, interactions among travelers, feedback from travel to the built and social environments, and feedback from other behaviors to the built and social environments. For utilitarian walking, the framework may contribute to the study design, data collection, adoption of new research methods, and provide indications for policy interventions.

A dynamic framework on travel mode choice focusing on utilitarian walking based on the integration of current knowledge

PubMed Central

Yang, Yong

2016-01-01

Recently, research on utilitarian walking has gained momentum due to its benefits on both health and the environment. However, our overall understanding of how built and social environments affect travel mode choice (walking or not) is still limited, and most existing frameworks on travel mode choice lack dynamic processes. After a review of several mainstream theories and a number of frameworks, we propose an integrated framework. The basic constructs in the travel mode choice function are utilities, constraints, attitudes, and habits. With a hierarchical structure and heuristic rules, the travel mode choice function is modified by individual characteristics and travel characteristics. The framework explicitly presents several dynamic processes, including the perception process on the environment, attitude formation process, habit formation process, interactions among an individual’s own behaviors, interactions among travelers, feedback from travel to the built and social environments, and feedback from other behaviors to the built and social environments. For utilitarian walking, the framework may contribute to the study design, data collection, adoption of new research methods, and provide indications for policy interventions. PMID:27747158

Multibody dynamics: Modeling component flexibility with fixed, free, loaded, constraint, and residual modes

NASA Technical Reports Server (NTRS)

Spanos, John T.; Tsuha, Walter S.

1989-01-01

The assumed-modes method in multibody dynamics allows the elastic deformation of each component in the system to be approximated by a sum of products of spatial and temporal functions commonly known as modes and modal coordinates respectively. The choice of component modes used to model articulating and non-articulating flexible multibody systems is examined. Attention is directed toward three classical Component Mode Synthesis (CMS) methods whereby component normal modes are generated by treating the component interface (I/F) as either fixed, free, or loaded with mass and stiffness contributions from the remaining components. The fixed and free I/F normal modes are augmented by static shape functions termed constraint and residual modes respectively. A mode selection procedure is outlined whereby component modes are selected from the Craig-Bampton (fixed I/F plus constraint), MacNeal-Rubin (free I/F plus residual), or Benfield-Hruda (loaded I/F) mode sets in accordance with a modal ordering scheme derived from balance realization theory. The success of the approach is judged by comparing the actuator-to-sensor frequency response of the reduced order system with that of the full order system over the frequency range of interest. A finite element model of the Galileo spacecraft serves as an example in demonstrating the effectiveness of the proposed mode selection method.

Cycles till failure of silver-zinc cells with completing failures modes: Preliminary data analysis

NASA Technical Reports Server (NTRS)

Sidik, S. M.; Leibecki, H. F.; Bozek, J. M.

1980-01-01

One hundred and twenty nine cells were run through charge-discharge cycles until failure. The experiment design was a variant of a central composite factorial in five factors. Preliminary data analysis consisted of response surface estimation of life. Batteries fail under two basic modes; a low voltage condition and an internal shorting condition. A competing failure modes analysis using maximum likelihood estimation for the extreme value life distribution was performed. Extensive diagnostics such as residual plotting and probability plotting were employed to verify data quality and choice of model.

Hyperpolarized 13C pyruvate mouse brain metabolism with absorptive-mode EPSI at 1 T

NASA Astrophysics Data System (ADS)

Miloushev, Vesselin Z.; Di Gialleonardo, Valentina; Salamanca-Cardona, Lucia; Correa, Fabian; Granlund, Kristin L.; Keshari, Kayvan R.

2017-02-01

The expected signal in echo-planar spectroscopic imaging experiments was explicitly modeled jointly in spatial and spectral dimensions. Using this as a basis, absorptive-mode type detection can be achieved by appropriate choice of spectral delays and post-processing techniques. We discuss the effects of gradient imperfections and demonstrate the implementation of this sequence at low field (1.05 T), with application to hyperpolarized [1-13C] pyruvate imaging of the mouse brain. The sequence achieves sufficient signal-to-noise to monitor the conversion of hyperpolarized [1-13C] pyruvate to lactate in the mouse brain. Hyperpolarized pyruvate imaging of mouse brain metabolism using an absorptive-mode EPSI sequence can be applied to more sophisticated murine disease and treatment models. The simple modifications presented in this work, which permit absorptive-mode detection, are directly translatable to human clinical imaging and generate improved absorptive-mode spectra without the need for refocusing pulses.

Forecasting the impact of transport improvements on commuting and residential choice

NASA Astrophysics Data System (ADS)

Elhorst, J. Paul; Oosterhaven, Jan

2006-03-01

This paper develops a probabilistic, competing-destinations, assignment model that predicts changes in the spatial pattern of the working population as a result of transport improvements. The choice of residence is explained by a new non-parametric model, which represents an alternative to the popular multinominal logit model. Travel times between zones are approximated by a normal distribution function with different mean and variance for each pair of zones, whereas previous models only use average travel times. The model’s forecast error of the spatial distribution of the Dutch working population is 7% when tested on 1998 base-year data. To incorporate endogenous changes in its causal variables, an almost ideal demand system is estimated to explain the choice of transport mode, and a new economic geography inter-industry model (RAEM) is estimated to explain the spatial distribution of employment. In the application, the model is used to forecast the impact of six mutually exclusive Dutch core-periphery railway proposals in the projection year 2020.

Effect of P T symmetry on nonlinear waves for three-wave interaction models in the quadratic nonlinear media

NASA Astrophysics Data System (ADS)

Shen, Yujia; Wen, Zichao; Yan, Zhenya; Hang, Chao

2018-04-01

We study the three-wave interaction that couples an electromagnetic pump wave to two frequency down-converted daughter waves in a quadratic optical crystal and P T -symmetric potentials. P T symmetric potentials are shown to modulate stably nonlinear modes in two kinds of three-wave interaction models. The first one is a spatially extended three-wave interaction system with odd gain-and-loss distribution in the channel. Modulated by the P T -symmetric single-well or multi-well Scarf-II potentials, the system is numerically shown to possess stable soliton solutions. Via adiabatical change of system parameters, numerical simulations for the excitation and evolution of nonlinear modes are also performed. The second one is a combination of P T -symmetric models which are coupled via three-wave interactions. Families of nonlinear modes are found with some particular choices of parameters. Stable and unstable nonlinear modes are shown in distinct families by means of numerical simulations. These results will be useful to further investigate nonlinear modes in three-wave interaction models.

Active vs. spectator modes in nonadiabatic photodissociation dynamics of the hydroxymethyl radical via the 22A(3s) Rydberg state

NASA Astrophysics Data System (ADS)

Xie, Changjian; Guo, Hua

2018-01-01

The choice of the active degrees of freedom (DOFs) is a pivotal issue in a reduced-dimensional model of quantum dynamics when a full-dimensional one is not feasible. Here, several five-dimensional (5D) models are used to investigate the nonadiabatic photodissociation dynamics of the hydroxymethyl (CH2OH) radical, which possesses nine internal DOFs, in its lowest absorption band. A normal-mode based scheme is used to identify the active and spectator modes, and its predictions are confirmed by 5D quantum dynamical calculations. Our results underscore the important role of the CO stretching mode in the photodissociation dynamics of CH2OH, originating from the photo-induced promotion of an electron from the half-occupied π*CO antibonding orbital to a carbon Rydberg orbital.

What Drives Parents? A Case Sensitive Inquiry into Parents' Mode Preferences for the Journey to School

ERIC Educational Resources Information Center

Zuniga, Kelly Draper

2010-01-01

This dissertation uses a case-sensitive approach to examine an active travel intervention's diverse target population. It builds on a series of travel choice models, and draws key conceptual themes from Chapin's (1974) human activity model, which highlights opportunity-related and propensity-related factors associated with behaviors. The research…

The effect of prey density on foraging mode selection in juvenile lumpfish: balancing food intake with the metabolic cost of foraging.

PubMed

Killen, Shaun S; Brown, Joseph A; Gamperl, A Kurt

2007-07-01

1. In many species, individuals will alter their foraging strategy in response to changes in prey density. However, previous work has shown that prey density has differing effects on the foraging mode decisions of ectotherms as compared with endotherms. This is likely due to differences in metabolic demand; however, the relationship between metabolism and foraging mode choice in ectotherms has not been thoroughly studied. 2. Juvenile lumpfish Cyclopterus lumpus forage using one of two modes: they can actively search for prey while swimming, or they can 'sit-and-wait' for prey while clinging to the substrate using a ventral adhesive disk. The presence of these easily distinguishable foraging modes makes juvenile lumpfish ideal for the study of foraging mode choice in ectotherms. 3. Behavioural observations conducted during laboratory experiments showed that juvenile lumpfish predominantly use the 'cling' foraging mode when prey is abundant, but resort to the more costly 'swim' mode to seek out food when prey is scarce. The metabolic cost of active foraging was also quantified for juvenile lumpfish using swim-tunnel respirometry, and a model was devised to predict the prey density at which lumpfish should switch between the swim and cling foraging modes to maximize energy intake. 4. The results of this model do not agree with previous observations of lumpfish behaviour, and thus it appears that juvenile lumpfish do not try to maximize their net energetic gain. Instead, our data suggest that juvenile lumpfish forage in a manner that reduces activity and conserves space in their limited aerobic scope. This behavioural flexibility is of great benefit to this species, as it allows young individuals to divert energy towards growth as opposed to activity. In a broader context, our results support previous speculation that ectotherms often forage in a manner that maintains a minimum prey encounter rate, but does not necessarily maximize net energy gain.

Leadership style and choice of strategy in conflict management among Israeli nurse managers in general hospitals.

PubMed

Hendel, Tova; Fish, Miri; Galon, Vered

2005-03-01

To identify conflict mode choices of head nurses in general hospitals and examine the relationship between leadership style, choice of strategy in handling conflicts and demographic characteristics. Nurse managers deal with conflicts daily. The choice of conflict management mode is associated with managerial effectiveness. The ability to creatively manage conflict situations, towards constructive outcomes is becoming a standard requirement. Head nurses (N = 60) in five general hospitals in central Israel were surveyed, using a 3-part questionnaire: The Thomas-Kilmann Conflict Mode Instrument, the Multi-factor Leadership Questionnaire, Form 5X-Short (MLQ 5X) and demographic data. Head nurses perceive themselves significantly more as transformational leaders than as transactional leaders. Compromise was found to be the most commonly used conflict management strategy. Approximately half of the nurses surveyed used only one mode in conflict management. Transformational leadership significantly affected the conflict strategy chosen. Head nurses tend to choose a conflict-handling mode which is concerned a form of a Lose-Lose approach. Preparation in conflict management should start from undergraduate education.

Evaluation of the relative risk to birds of alternative pesticides using EPA’s TIM/MCnest Model

EPA Science Inventory

Agricultural producers today have many choices of active ingredients for crop protection. These products come with different active ingredients, different modes of action, and that initiate different adverse outcome pathways. Use patterns also differ considerably among products...

Future travel demand and its implications for transportation infrastructure investments in the Texas Triangle.

DOT National Transportation Integrated Search

2009-03-01

This study takes a megaregion approach to project future travel demand and choice of transport : modes in the Texas Triangle, which is encompassed by four major metropolitan areas, Dallas-Fort : Worth, Houston, San Antonio, and Austin. The model was ...

0-6766 : a generic mode choice model applicable for small and medium-sized MPOs : [project summary].

DOT National Transportation Integrated Search

2013-12-01

Due to the projected population growth increase : in Texas and the continued increase in total : motorized vehicle miles traveled in Texas, the : Texas Department of Transportation (TxDOT) is : interested in examining multimodal solutions to : aid in...

Neighbourhood, Route and Workplace-Related Environmental Characteristics Predict Adults' Mode of Travel to Work

PubMed Central

Dalton, Alice M.; Jones, Andrew P.; Panter, Jenna R.; Ogilvie, David

2013-01-01

Objective Commuting provides opportunities for regular physical activity which can reduce the risk of chronic disease. Commuters' mode of travel may be shaped by their environment, but understanding of which specific environmental characteristics are most important and might form targets for intervention is limited. This study investigated associations between mode choice and a range of objectively assessed environmental characteristics. Methods Participants in the Commuting and Health in Cambridge study reported where they lived and worked, their usual mode of travel to work and a variety of socio-demographic characteristics. Using geographic information system (GIS) software, 30 exposure variables were produced capturing characteristics of areas around participants' homes and workplaces and their shortest modelled routes to work. Associations between usual mode of travel to work and personal and environmental characteristics were investigated using multinomial logistic regression. Results Of the 1124 respondents, 50% reported cycling or walking as their usual mode of travel to work. In adjusted analyses, home-work distance was strongly associated with mode choice, particularly for walking. Lower odds of walking or cycling rather than driving were associated with a less frequent bus service (highest versus lowest tertile: walking OR 0.61 [95% CI 0.20–1.85]; cycling OR 0.43 [95% CI 0.23–0.83]), low street connectivity (OR 0.22, [0.07–0.67]; OR 0.48 [0.26–0.90]) and free car parking at work (OR 0.24 [0.10–0.59]; OR 0.55 [0.32–0.95]). Participants were less likely to cycle if they had access to fewer destinations (leisure facilities, shops and schools) close to work (OR 0.36 [0.21–0.62]) and a railway station further from home (OR 0.53 [0.30–0.93]). Covariates strongly predicted travel mode (pseudo r-squared 0.74). Conclusions Potentially modifiable environmental characteristics, including workplace car parking, street connectivity and access to public transport, are associated with travel mode choice, and could be addressed as part of transport policy and infrastructural interventions to promote active commuting. PMID:23840743

Neighbourhood, Route and Workplace-Related Environmental Characteristics Predict Adults' Mode of Travel to Work.

PubMed

Dalton, Alice M; Jones, Andrew P; Panter, Jenna R; Ogilvie, David

2013-01-01

Commuting provides opportunities for regular physical activity which can reduce the risk of chronic disease. Commuters' mode of travel may be shaped by their environment, but understanding of which specific environmental characteristics are most important and might form targets for intervention is limited. This study investigated associations between mode choice and a range of objectively assessed environmental characteristics. Participants in the Commuting and Health in Cambridge study reported where they lived and worked, their usual mode of travel to work and a variety of socio-demographic characteristics. Using geographic information system (GIS) software, 30 exposure variables were produced capturing characteristics of areas around participants' homes and workplaces and their shortest modelled routes to work. Associations between usual mode of travel to work and personal and environmental characteristics were investigated using multinomial logistic regression. Of the 1124 respondents, 50% reported cycling or walking as their usual mode of travel to work. In adjusted analyses, home-work distance was strongly associated with mode choice, particularly for walking. Lower odds of walking or cycling rather than driving were associated with a less frequent bus service (highest versus lowest tertile: walking OR 0.61 [95% CI 0.20-1.85]; cycling OR 0.43 [95% CI 0.23-0.83]), low street connectivity (OR 0.22, [0.07-0.67]; OR 0.48 [0.26-0.90]) and free car parking at work (OR 0.24 [0.10-0.59]; OR 0.55 [0.32-0.95]). Participants were less likely to cycle if they had access to fewer destinations (leisure facilities, shops and schools) close to work (OR 0.36 [0.21-0.62]) and a railway station further from home (OR 0.53 [0.30-0.93]). Covariates strongly predicted travel mode (pseudo r-squared 0.74). Potentially modifiable environmental characteristics, including workplace car parking, street connectivity and access to public transport, are associated with travel mode choice, and could be addressed as part of transport policy and infrastructural interventions to promote active commuting.

Acoustics of two-component porous materials with anisotropic tortuosity

NASA Astrophysics Data System (ADS)

Albers, Bettina; Wilmanski, Krzysztof

2012-11-01

The paper is devoted to the analysis of monochromatic waves in two-component poroelastic materials described by a Biot-like model whose stress-strain relations are isotropic but the permeability is anisotropic. This anisotropy is induced by the anisotropy of the tortuosity which is given by a second order symmetric tensor. This is a new feature of the model while in earlier papers only isotropic permeabilities were considered. We show that this new model describes four modes of propagation. For our special choice of orientation of the direction of propagation these are two pseudo longitudinal modes P1 and P2, one pseudo transversal mode S2 and one transversal mode S1. The latter becomes also pseudo transversal in the general case of anisotropy. We analyze the speeds of propagation and the attenuation of these waves as well as the polarization properties in dependence on the orientation of the principal directions of the tortuosity. We indicate the practical importance of different shear (transversal) modes of propagation in a possible new nondestructive test of geophysical materials.

Bus-based park-and-ride system: a stochastic model on multimodal network with congestion pricing schemes

NASA Astrophysics Data System (ADS)

Liu, Zhiyuan; Meng, Qiang

2014-05-01

This paper focuses on modelling the network flow equilibrium problem on a multimodal transport network with bus-based park-and-ride (P&R) system and congestion pricing charges. The multimodal network has three travel modes: auto mode, transit mode and P&R mode. A continuously distributed value-of-time is assumed to convert toll charges and transit fares to time unit, and the users' route choice behaviour is assumed to follow the probit-based stochastic user equilibrium principle with elastic demand. These two assumptions have caused randomness to the users' generalised travel times on the multimodal network. A comprehensive network framework is first defined for the flow equilibrium problem with consideration of interactions between auto flows and transit (bus) flows. Then, a fixed-point model with unique solution is proposed for the equilibrium flows, which can be solved by a convergent cost averaging method. Finally, the proposed methodology is tested by a network example.

The Role of Personality Traits through Habit and Intention on Determining Future Preferences of Public Transport Use

PubMed Central

Yazdanpanah, Mahdi; Hadji Hosseinlou, Mansour

2017-01-01

A complex set of factors may affect transportation mode choice. While earlier studies have often considered objective factors in determining preferences of public transport use as a sustainable transportation, subjective factors such as personality traits are underexplored. Therefore, this study aimed to investigate the influence of personality traits on the number of future public transport use. Additionally, “car habit” and “intention toward using public modes” were considered to be important. For this purpose, a case study from departure passengers at Imam Khomeini International Airport (IKIA, Tehran, Iran) was conducted between January and February 2015 at IKIA. Results of structural equation modeling (SEM) shows that only neuroticism and extraversion personality traits were significant in determining future public transportation mode choice. However, the model indicates that these traits indirectly influence intention and car habit. Neuroticism was found to have a total effect of −0.022 on future public transport use, which represents a negative association with public transport use, while extraversion positively influenced future public transport use with a total effect of 0.031. Moreover, the results found interestingly that car access had a better fit to the data than the number of cars in household (NCH); both had significant positive effect on car habit, but only car access had a significant influence on intention. Furthermore, the effect of socio-demographic variables such as age, gender, educational level, income level, and body mass index (BMI) were determined to be significant in identifying choice of future transport mode to airports, which is explained in the discussion section of this paper. PMID:28218641

Variability in baseline travel behaviour as a predictor of changes in commuting by active travel, car and public transport: a natural experimental study

PubMed Central

Heinen, Eva; Ogilvie, David

2016-01-01

Purpose To strengthen our understanding of the impact of baseline variability in mode choice on the likelihood of travel behaviour change. Methods Quasi-experimental analyses in a cohort study of 450 commuters exposed to a new guided busway with a path for walking and cycling in Cambridge, UK. Exposure to the intervention was defined using the shortest network distance from each participant’s home to the busway. Variability in commuter travel behaviour at baseline was defined using the Herfindahl–Hirschman Index, the number of different modes of transport used over a week, and the proportion of trips made by the main (combination of) mode(s). The outcomes were changes in the share of commute trips (i) involving any active travel, (ii) involving any public transport, and (iii) made entirely by car. Variability and change data were derived from a self-reported seven-day record collected before (2009) and after (2012) the intervention. Separate multinomial regression models were estimated to assess the influence of baseline variability on behaviour change, both independently and as an interaction effect with exposure to the intervention. Results All three measures of variability predicted changes in mode share in most models. The effect size for the intervention was slightly strengthened after including variability. Commuters with higher baseline variability were more likely to increase their active mode share (e.g. for HHI: relative risk ratio [RRR] for interaction 3.34, 95% CI 1.41, 7.89) and decrease their car mode share in response to the intervention (e.g. for HHI: RRR 7.50, 95% CI 2.52, 22.34). Conclusions People reporting a higher level of variability in mode choice were more likely to change their travel behaviour following an intervention. Future research should consider such variability as a potential predictor and effect modifier of travel and physical activity behaviour change, and its significance for the design and targeting of interventions. PMID:27200265

The influence of travel attitudes, commute mode choice, and perceived neighborhood characteristics on physical activity.

PubMed

Morckel, Victoria; Terzano, Kathryn

2014-01-01

This study examines the relationships between physical activity, travel attitudes, commute mode choice, and perceived neighborhood characteristics. A recent study found that people who walk or bike during their commute exercise more outside of the commute than do people who commute by mass transit or car. The current study seeks to explain what might account for this relationship, using ANOVA models (Method) conducted on survey data from 3 cities. Perceived neighborhood characteristics and travel attitudes influence participants' reported physical activity levels both during the commute and outside of the commute. While the study does not establish causality, the results provide some support for the notion that policy makers interested in increasing physical activity levels should consider changing not only the physical environment, but also perceived neighborhood characteristics and travel attitudes.

Neighborhood crime and transit station access mode choice - phase III of neighborhood crime and travel behavior.

DOT National Transportation Integrated Search

2015-08-01

This report provides the findings from the third phase of a three-part study about the influences of neighborhood crimes on travel : mode choice. While previous phases found evidence that high levels of neighborhood crime discourage people from choos...

Neighborhood crime and travel behavior : an investigation of the influence of neighborhood crime rates on mode choice, phase II.

DOT National Transportation Integrated Search

2012-01-01

There are considerable environmental and public health benefits if people choose to walk, bicycle, or ride transit, instead of drive. However, little work has been done on the effects of neighborhood crimes on mode choice. Instinctively, we understan...

Neighborhood crime and travel behavior : an investigation of the influence of neighborhood crime rates on mode choice - phase II.

DOT National Transportation Integrated Search

2012-01-01

There are considerable environmental and public health benefits if people choose to walk, bicycle, or ride transit, instead of drive. : However, little work has been done on the effects of neighborhood crimes on mode choice. Instinctively, we underst...

Vertical resolution of baroclinic modes in global ocean models

NASA Astrophysics Data System (ADS)

Stewart, K. D.; Hogg, A. McC.; Griffies, S. M.; Heerdegen, A. P.; Ward, M. L.; Spence, P.; England, M. H.

2017-05-01

Improvements in the horizontal resolution of global ocean models, motivated by the horizontal resolution requirements for specific flow features, has advanced modelling capabilities into the dynamical regime dominated by mesoscale variability. In contrast, the choice of the vertical grid remains a subjective choice, and it is not clear that efforts to improve vertical resolution adequately support their horizontal counterparts. Indeed, considering that the bulk of the vertical ocean dynamics (including convection) are parameterized, it is not immediately obvious what the vertical grid is supposed to resolve. Here, we propose that the primary purpose of the vertical grid in a hydrostatic ocean model is to resolve the vertical structure of horizontal flows, rather than to resolve vertical motion. With this principle we construct vertical grids based on their abilities to represent baroclinic modal structures commensurate with the theoretical capabilities of a given horizontal grid. This approach is designed to ensure that the vertical grids of global ocean models complement (and, importantly, to not undermine) the resolution capabilities of the horizontal grid. We find that for z-coordinate global ocean models, at least 50 well-positioned vertical levels are required to resolve the first baroclinic mode, with an additional 25 levels per subsequent mode. High-resolution ocean-sea ice simulations are used to illustrate some of the dynamical enhancements gained by improving the vertical resolution of a 1/10° global ocean model. These enhancements include substantial increases in the sea surface height variance (∼30% increase south of 40°S), the barotropic and baroclinic eddy kinetic energies (up to 200% increase on and surrounding the Antarctic continental shelf and slopes), and the overturning streamfunction in potential density space (near-tripling of the Antarctic Bottom Water cell at 65°S).

Testing boundary conditions for the conjunction fallacy: effects of response mode, conceptual focus, and problem type.

PubMed

Wedell, Douglas H; Moro, Rodrigo

2008-04-01

Two experiments used within-subject designs to examine how conjunction errors depend on the use of (1) choice versus estimation tasks, (2) probability versus frequency language, and (3) conjunctions of two likely events versus conjunctions of likely and unlikely events. All problems included a three-option format verified to minimize misinterpretation of the base event. In both experiments, conjunction errors were reduced when likely events were conjoined. Conjunction errors were also reduced for estimations compared with choices, with this reduction greater for likely conjuncts, an interaction effect. Shifting conceptual focus from probabilities to frequencies did not affect conjunction error rates. Analyses of numerical estimates for a subset of the problems provided support for the use of three general models by participants for generating estimates. Strikingly, the order in which the two tasks were carried out did not affect the pattern of results, supporting the idea that the mode of responding strongly determines the mode of thinking about conjunctions and hence the occurrence of the conjunction fallacy. These findings were evaluated in terms of implications for rationality of human judgment and reasoning.

Koopman decomposition of Burgers' equation: What can we learn?

NASA Astrophysics Data System (ADS)

Page, Jacob; Kerswell, Rich

2017-11-01

Burgers' equation is a well known 1D model of the Navier-Stokes equations and admits a selection of equilibria and travelling wave solutions. A series of Burgers' trajectories are examined with Dynamic Mode Decomposition (DMD) to probe the capability of the method to extract coherent structures from ``run-down'' simulations. The performance of the method depends critically on the choice of observable. We use the Cole-Hopf transformation to derive an observable which has linear, autonomous dynamics and for which the DMD modes overlap exactly with Koopman modes. This observable can accurately predict the flow evolution beyond the time window of the data used in the DMD, and in that sense outperforms other observables motivated by the nonlinearity in the governing equation. The linearizing observable also allows us to make informed decisions about often ambiguous choices in nonlinear problems, such as rank truncation and snapshot spacing. A number of rules of thumb for connecting DMD with the Koopman operator for nonlinear PDEs are distilled from the results. Related problems in low Reynolds number fluid turbulence are also discussed.

Consumer-directed models of personal care: lessons from Medicaid.

PubMed

Doty, P; Kasper, J; Litvak, S

1996-01-01

"Consumer-directed" models of financing and services delivery are compared with models that emphasize professional control and accountability within the context of Medicaid-financed personal care services (PCS). The Medicaid PCS benefit finances aide or attendant services for low-income persons with functional disabilities to assist them with daily living tasks. Consumer-directed modes of service provision permit service recipients themselves to have greater choice and control over all aspects of service provision. Client surveys in three states found that clients were most satisfied with the program elements of Medicaid PCS services that gave them more choice and control. Case studies of how Medicaid PCS programs in particular states are administered indicate that the use of aides who are independent providers, unattached to a home health or home care agency, is a critical aspect of consumer direction. By itself, however, this factor does not guarantee consumer direction because other Medicaid PCS rules and regulations may restrict client choice and control.

Modeling of a microchannel plate working in pulsed mode

NASA Astrophysics Data System (ADS)

Secroun, Aurelia; Mens, Alain; Segre, Jacques; Assous, Franck; Piault, Emmanuel; Rebuffie, Jean-Claude

1997-05-01

MicroChannel Plates (MCPs) are used in high speed cinematography systems such as MCP framing cameras and streak camera readouts. In order to know the dynamic range or the signal to noise ratio that are available in these devices, a good knowledge of the performances of the MCP is essential. The point of interest of our simulation is the working mode of the microchannel plate--that is light pulsed mode--, in which the signal level is relatively high and its duration can be shorter than the time needed to replenish the wall of the channel, when other papers mainly studied night vision applications with weak continuous and nearly single electron input signal. Also our method allows the simulation of saturation phenomena due to the large number of electrons involved, whereas the discrete models previously used for simulating pulsed mode might not be properly adapted. Here are presented the choices made in modeling the microchannel, more specifically as for the physics laws, the secondary emission parameters and the 3D- geometry. In a last part first results are shown.

Box-Cox Mixed Logit Model for Travel Behavior Analysis

NASA Astrophysics Data System (ADS)

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.

Numerical Investigation of Flapwise-Torsional Vibration Model of a Smart Section Blade with Microtab

DOE PAGES

Li, Nailu; Balas, Mark J.; Yang, Hua; ...

2015-01-01

This paper presents a method to develop an aeroelastic model of a smart section blade equipped with microtab. The model is suitable for potential passive vibration control study of the blade section in classic flutter. Equations of the model are described by the nondimensional flapwise and torsional vibration modes coupled with the aerodynamic model based on the Theodorsen theory and aerodynamic effects of the microtab based on the wind tunnel experimental data. The aeroelastic model is validated using numerical data available in the literature and then utilized to analyze the microtab control capability on flutter instability case and divergence instabilitymore » case. The effectiveness of the microtab is investigated with the scenarios of different output controllers and actuation deployments for both instability cases. The numerical results show that the microtab can effectively suppress both vibration modes with the appropriate choice of the output feedback controller.« less

Numerical Investigation of Flapwise-Torsional Vibration Model of a Smart Section Blade with Microtab

DOE Office of Scientific and Technical Information (OSTI.GOV)

Li, Nailu; Balas, Mark J.; Yang, Hua

2015-01-01

This study presents a method to develop an aeroelastic model of a smart section blade equipped with microtab. The model is suitable for potential passive vibration control study of the blade section in classic flutter. Equations of the model are described by the nondimensional flapwise and torsional vibration modes coupled with the aerodynamic model based on the Theodorsen theory and aerodynamic effects of the microtab based on the wind tunnel experimental data. The aeroelastic model is validated using numerical data available in the literature and then utilized to analyze the microtab control capability on flutter instability case and divergence instabilitymore » case. The effectiveness of the microtab is investigated with the scenarios of different output controllers and actuation deployments for both instability cases. The numerical results show that the microtab can effectively suppress both vibration modes with the appropriate choice of the output feedback controller.« less

Emergent gravity from a mass deformation in warped spacetime

DOE Office of Scientific and Technical Information (OSTI.GOV)

Gherghetta, Tony; Peloso, Marco; Poppitz, Erich

2005-11-15

We consider a deformation of five-dimensional warped gravity with bulk and boundary mass terms to quadratic order in the action. We show that massless zero modes occur for special choices of the masses. The tensor zero mode is a smooth deformation of the Randall-Sundrum graviton wave function and can be localized anywhere in the bulk. There is also a vector zero mode with similar localization properties, which is decoupled from conserved sources at tree level. Interestingly, there are no scalar modes, and the model is ghost-free at the linearized level. When the tensor zero mode is localized near the IRmore » brane, the dual interpretation is a composite graviton describing an emergent (induced) theory of gravity at the IR scale. In this case Newton's law of gravity changes to a new power law below the millimeter scale, with an exponent that can even be irrational.« less

Modes of Decision Making Used by Nursing Home Residents and Their Families When Confronted With Potential Hospital Readmission.

PubMed

Tappen, Ruth M; Elkins, Deborah; Worch, Sarah; Weglinski, MaryAnn

2016-11-01

The purpose of the current study was to characterize the decision-making processes used by nursing home (NH) residents and their families when confronted with an acute change in condition and the choice of transfer to the hospital or treatment in the NH. Using cognitive task analysis, 96 residents and 75 family members from 19 NHs were asked how they would make this choice. Fifty-one residents (53%) and 61 family members (81%) used a deliberative mode characterized by seeking information and weighing risks and benefits. Ten residents (10%) and five family members (7%) used a predominantly emotion-based mode characterized by references to feelings and prior experiences in these facilities. Thirty-six residents (38%) and nine family members (12%) delegated the decision to a family member or provider. Age and resident/family status were associated with mode used; transfer choice, gender, religion, education, and ethnic group were not. Although classic theories of information processing posit two modes of decision making, deliberative and affective, the current data suggest a third mode, that of delegating the decision to trusted others, particularly family members and providers. [Res Gerontol Nurs. 2016; 9(6):288-299.]. Copyright 2016, SLACK Incorporated.

Estimating the health benefits of planned public transit investments in Montreal.

PubMed

Tétreault, Louis-François; Eluru, Naveen; Hatzopoulou, Marianne; Morency, Patrick; Plante, Celine; Morency, Catherine; Reynaud, Frederic; Shekarrizfard, Maryam; Shamsunnahar, Yasmin; Faghih Imani, Ahmadreza; Drouin, Louis; Pelletier, Anne; Goudreau, Sophie; Tessier, Francois; Gauvin, Lise; Smargiassi, Audrey

2018-01-01

Since public transit infrastructure affects road traffic volumes and influences transportation mode choice, which in turn impacts health, it is important to estimate the alteration of the health burden linked with transit policies. We quantified the variation in health benefits and burden between a business as usual (BAU) and a public transit (PT) scenarios in 2031 (with 8 and 19 new subway and train stations) for the greater Montreal region. Using mode choice and traffic assignment models, we predicted the transportation mode choice and traffic assignment on the road network. Subsequently, we estimated the distance travelled in each municipality by mode, the minutes spent in active transportation, as well as traffic emissions. Thereafter we estimated the health burden attributed to air pollution and road traumas and the gains associated with active transportation for both the BAU and PT scenarios. We predicted a slight decrease of overall trips and kilometers travelled by car as well as an increase of active transportation for the PT in 2031 vs the BAU. Our analysis shows that new infrastructure will reduce the overall burden of transportation by 2.5 DALYs per 100,000 persons. This decrease is caused by the reduction of road traumas occurring in the inner suburbs and central Montreal region as well as gains in active transportation in the inner suburbs. Based on the results of our study, transportation planned public transit projects for Montreal are unlikely to reduce drastically the burden of disease attributable to road vehicles and infrastructures in the Montreal region. The impact of the planned transportation infrastructures seems to be very low and localized mainly in the areas where new public transit stations are planned. Copyright © 2017 Elsevier Inc. All rights reserved.

Grocery Shopping How Individuals and Built Environments Influence Choice of Travel Mode.

PubMed

Jiao, Junfeng; Moudon, Anne Vernez; Drewnowski, Adam

This research investigated the influences of socioeconomic characteristics of individual travelers and of the environments where the travelers live and shop on choice of travel mode for grocery shopping. The data on travel for grocery shopping came from 2,001 respondents to the 2009 Seattle Obesity Study survey in King County, Washington. Eighty-eight percent of the respondents drove to their grocery stores, whereas 12% used transit or taxis, walked, biked, or carpooled. The addresses of 1,994 homes and 1,901 primary grocery stores used by respondents were geographically coded. The characteristics of built environments in the neighborhoods around homes and grocery stores and the distances between those homes and stores were measured in a geographic information system. Four binary logistic models estimated the impact of individual socioeconomic characteristics, distance, and built environments around homes and grocery stores on the travel mode used for grocery shopping. Fourteen variables were significantly related to mode choice. The strongest predictors of driving to the grocery store were more cars per adult household member, more adults per household, living in a single-family house, longer distances between homes and grocery stores (both the stores used and the nearest stores), and more at-ground parking around the grocery store used. Higher street density, more quick-service restaurants around homes, and more nonchain grocery stores near the primary grocery store used were related to not driving. Results suggested that reductions of distances between homes and grocery stores, clustering of grocery stores and other food establishments, and reductions in the amount of the parking around them could lead to less driving for grocery shopping.

Grocery Shopping How Individuals and Built Environments Influence Choice of Travel Mode

PubMed Central

Jiao, Junfeng; Moudon, Anne Vernez; Drewnowski, Adam

2014-01-01

This research investigated the influences of socioeconomic characteristics of individual travelers and of the environments where the travelers live and shop on choice of travel mode for grocery shopping. The data on travel for grocery shopping came from 2,001 respondents to the 2009 Seattle Obesity Study survey in King County, Washington. Eighty-eight percent of the respondents drove to their grocery stores, whereas 12% used transit or taxis, walked, biked, or carpooled. The addresses of 1,994 homes and 1,901 primary grocery stores used by respondents were geographically coded. The characteristics of built environments in the neighborhoods around homes and grocery stores and the distances between those homes and stores were measured in a geographic information system. Four binary logistic models estimated the impact of individual socioeconomic characteristics, distance, and built environments around homes and grocery stores on the travel mode used for grocery shopping. Fourteen variables were significantly related to mode choice. The strongest predictors of driving to the grocery store were more cars per adult household member, more adults per household, living in a single-family house, longer distances between homes and grocery stores (both the stores used and the nearest stores), and more at-ground parking around the grocery store used. Higher street density, more quick-service restaurants around homes, and more nonchain grocery stores near the primary grocery store used were related to not driving. Results suggested that reductions of distances between homes and grocery stores, clustering of grocery stores and other food establishments, and reductions in the amount of the parking around them could lead to less driving for grocery shopping. PMID:25729127

Valuation of Mortality Risk Attributable to Climate Change: Investigating the Effect of Survey Administration Modes on a VSL

PubMed Central

Ščasný, Milan; Alberini, Anna

2012-01-01

The health impact attributable to climate change has been identified as one of the priority areas for impact assessment. The main goal of this paper is to estimate the monetary value of one key health effect, which is premature mortality. Specifically, our goal is to derive the value of a statistical life from people’s willingness to pay for avoiding the risk of dying in one post-transition country in Europe, i.e., the Czech Republic. We carried out a series of conjoint choice experiments in order to value mortality risk reductions. We found the responses to the conjoint choice questions to be reasonable and consistent with the economic paradigm. The VSL is about EUR 2.4 million, and our estimate is comparable with the value of preventing a fatality as used in one of the integrated assessment models. To investigate whether carrying out the survey through the internet may violate the welfare estimate, we administered our questionnaire to two independent samples of respondents using two different modes of survey administration. The results show that the VSLs for the two groups of respondents are €2.25 and €2.55 million, and these figures are statistically indistinguishable. However, the key parameters of indirect utility between the two modes of survey administration are statistically different when specific subgroups of population, such as older respondents, are concerned. Based on this evidence, we conclude that properly designed and administered on-line surveys are a reliable method for administering questionnaires, even when the latter are cognitively challenging. However, attention should be paid to sampling and choice regarding the mode of survey administration if the preference of specific segments of the population is elicited. PMID:23249861

A Dozen Heads Are Better than One: Collaborative Writing in Genre-Based Pedagogy

ERIC Educational Resources Information Center

Caplan, Nigel A.; Farling, Monica

2017-01-01

Organizing writing instruction around genres rather than rhetorical modes can be a highly effective and engaging preparation for students' academic and professional writing needs. The teaching/learning cycle (TLC) is a highly scaffolded curriculum model for teaching target written genres. In the TLC, the organization of and linguistic choices in a…

Closing in on the large-scale CMB power asymmetry

NASA Astrophysics Data System (ADS)

Contreras, D.; Hutchinson, J.; Moss, A.; Scott, D.; Zibin, J. P.

2018-03-01

Measurements of the cosmic microwave background (CMB) temperature anisotropies have revealed a dipolar asymmetry in power at the largest scales, in apparent contradiction with the statistical isotropy of standard cosmological models. The significance of the effect is not very high, and is dependent on a posteriori choices. Nevertheless, a number of models have been proposed that produce a scale-dependent asymmetry. We confront several such models for a physical, position-space modulation with CMB temperature observations. We find that, while some models that maintain the standard isotropic power spectrum are allowed, others, such as those with modulated tensor or uncorrelated isocurvature modes, can be ruled out on the basis of the overproduction of isotropic power. This remains the case even when an extra isocurvature mode fully anticorrelated with the adiabatic perturbations is added to suppress power on large scales.

Projecting Future Scheduled Airline Demand, Schedules and NGATS Benefits Using TSAM

NASA Technical Reports Server (NTRS)

Dollyhigh, Samuel; Smith, Jeremy; Viken, Jeff; Trani, Antonio; Baik, Hojong; Hinze, Nickolas; Ashiabor, Senanu

2006-01-01

The Transportation Systems Analysis Model (TSAM) developed by Virginia Tech s Air Transportation Systems Lab and NASA Langley can provide detailed analysis of the effects on the demand for air travel of a full range of NASA and FAA aviation projects. TSAM has been used to project the passenger demand for very light jet (VLJ) air taxi service, scheduled airline demand growth and future schedules, Next Generation Air Transportation System (NGATS) benefits, and future passenger revenues for the Airport and Airway Trust Fund. TSAM can project the resulting demand when new vehicles and/or technology is inserted into the long distance (100 or more miles one-way) transportation system, as well as, changes in demand as a result of fare yield increases or decreases, airport transit times, scheduled flight times, ticket taxes, reductions or increases in flight delays, and so on. TSAM models all long distance travel in the contiguous U.S. and determines the mode choice of the traveler based on detailed trip costs, travel time, schedule frequency, purpose of the trip (business or non-business), and household income level of the traveler. Demand is modeled at the county level, with an airport choice module providing up to three airports as part of the mode choice. Future enplanements at airports can be projected for different scenarios. A Fratar algorithm and a schedule generator are applied to generate future flight schedules. This paper presents the application of TSAM to modeling future scheduled air passenger demand and resulting airline schedules, the impact of NGATS goals and objectives on passenger demand, along with projections for passenger fee receipts for several scenarios for the FAA Airport and Airway Trust Fund.

Preferred modes of travel among older adults: what factors affect the choice to walk instead of drive?

PubMed

Naumann, Rebecca B; Dellinger, Ann M; Anderson, Melissa L; Bonomi, Amy E; Rivara, Frederick P; Thompson, Robert S

2009-10-01

There are many factors that influence older adults' travel choices. This paper explores the associations between mode of travel choice for a short trip and older adults' personal characteristics. This study included 406 drivers over the age of 64 who were enrolled in a large integrated health plan in the United States between 1991 and 2001. Bivariate analyses and generalized linear modeling were used to examine associations between choosing to walk or drive and respondents' self-reported general health, physical and functional abilities, and confidence in walking and driving. Having more confidence in their ability to walk versus drive increased an older adult's likelihood of walking to make a short trip by about 20% (PR=1.22; 95% CI: 1.06-1.40), and walking for exercise increased the likelihood by about 50% (PR=1.53; 95% CI=1.22-1.91). Reporting fair or poor health decreased the likelihood of walking, as did cutting down on the amount of driving due to a physical problem. Factors affecting a person's decision to walk for exercise may not be the same as those that influence their decision to walk as a mode of travel. It is important to understand the barriers to walking for exercise and walking for travel to develop strategies to help older adults meet both their exercise and mobility needs. Increasing walking over driving among older adults may require programs that increase confidence in walking and encourage walking for exercise.

Mode perturbation method for optimal guided wave mode and frequency selection.

PubMed

Philtron, J H; Rose, J L

2014-09-01

With a thorough understanding of guided wave mechanics, researchers can predict which guided wave modes will have a high probability of success in a particular nondestructive evaluation application. However, work continues to find optimal mode and frequency selection for a given application. This "optimal" mode could give the highest sensitivity to defects or the greatest penetration power, increasing inspection efficiency. Since material properties used for modeling work may be estimates, in many cases guided wave mode and frequency selection can be adjusted for increased inspection efficiency in the field. In this paper, a novel mode and frequency perturbation method is described and used to identify optimal mode points based on quantifiable wave characteristics. The technique uses an ultrasonic phased array comb transducer to sweep in phase velocity and frequency space. It is demonstrated using guided interface waves for bond evaluation. After searching nearby mode points, an optimal mode and frequency can be selected which has the highest sensitivity to a defect, or gives the greatest penetration power. The optimal mode choice for a given application depends on the requirements of the inspection. Copyright © 2014 Elsevier B.V. All rights reserved.

Natural and built environmental exposures on children's active school travel: A Dutch global positioning system-based cross-sectional study.

PubMed

Helbich, Marco; Emmichoven, Maarten J Zeylmans van; Dijst, Martin J; Kwan, Mei-Po; Pierik, Frank H; Vries, Sanne I de

2016-05-01

Physical inactivity among children is on the rise. Active transport to school (ATS), namely walking and cycling there, adds to children's activity level. Little is known about how exposures along actual routes influence children's transport behavior. This study examined how natural and built environments influence mode choice among Dutch children aged 6-11 years. 623 school trips were tracked with global positioning system. Natural and built environmental exposures were determined by means of a geographic information system and their associations with children's active/passive mode choice were analyzed using mixed models. The actual commuted distance is inversely associated with ATS when only personal, traffic safety, and weather features are considered. When the model is adjusted for urban environments, the results are reversed and distance is no longer significant, whereas well-connected streets and cycling lanes are positively associated with ATS. Neither green space nor weather is significant. As distance is not apparent as a constraining travel determinant when moving through urban landscapes, planning authorities should support children's ATS by providing well-designed cities. Copyright © 2016 Elsevier Ltd. All rights reserved.

Modeling electron fractionalization with unconventional Fock spaces.

PubMed

Cobanera, Emilio

2017-08-02

It is shown that certain fractionally-charged quasiparticles can be modeled on D-dimensional lattices in terms of unconventional yet simple Fock algebras of creation and annihilation operators. These unconventional Fock algebras are derived from the usual fermionic algebra by taking roots (the square root, cubic root, etc) of the usual fermionic creation and annihilation operators. If the fermions carry non-Abelian charges, then this approach fractionalizes the Abelian charges only. In particular, the mth-root of a spinful fermion carries charge e/m and spin 1/2. Just like taking a root of a complex number, taking a root of a fermion yields a mildly non-unique result. As a consequence, there are several possible choices of quantum exchange statistics for fermion-root quasiparticles. These choices are tied to the dimensionality [Formula: see text] of the lattice by basic physical considerations. One particular family of fermion-root quasiparticles is directly connected to the parafermion zero-energy modes expected to emerge in certain mesoscopic devices involving fractional quantum Hall states. Hence, as an application of potential mesoscopic interest, I investigate numerically the hybridization of Majorana and parafermion zero-energy edge modes caused by fractionalizing but charge-conserving tunneling.

Learners' choices and beliefs about self-testing.

PubMed

Kornell, Nate; Son, Lisa K

2009-07-01

Students have to make scores of practical decisions when they study. We investigated the effectiveness of, and beliefs underlying, one such practical decision: the decision to test oneself while studying. Using a flashcards-like procedure, participants studied lists of word pairs. On the second of two study trials, participants either saw the entire pair again (pair mode) or saw the cue and attempted to generate the target (test mode). Participants were asked either to rate the effectiveness of each study mode (Experiment 1) or to choose between the two modes (Experiment 2). The results demonstrated a mismatch between metacognitive beliefs and study choices: Participants (incorrectly) judged that the pair mode resulted in the most learning, but chose the test mode most frequently. A post-experimental questionnaire suggested that self-testing was motivated by a desire to diagnose learning rather than a desire to improve learning.

Contraceptive practice in China: 1970-2004.

PubMed

Wang, Cuntong

2015-03-01

Using large-scale data from the national conventional statistics and nationally representative sample surveys, the current study aims to assess the level, mode, and determinants of modern contraceptive use from 1970 to 2004 among married couples aged 20 to 49 years in China. A relatively stable Chinese mode of contraception has been established and maintained since the 1980s, characterized by prominent, long-acting contraceptive use and the highest overall prevalence in the world during the past 3 decades. In recent years, the composition of contraceptive use has changed, characterized by the increasing use of the intrauterine device and short-acting methods and a drastic decrease in male and female sterilization. However, the dominance of the long-acting methods has not undergone substantial change. The results from a multinomial logit model employed in this study indicate that family planning policy and socioeconomic and demographic factors jointly influence contraceptive choice. In particular, contraceptive choice is closely associated with the strength of family planning policy in China. © 2011 APJPH.

N-body simulations of collective effects in spiral and barred galaxies

NASA Astrophysics Data System (ADS)

Zhang, X.

2016-10-01

We present gravitational N-body simulations of the secular morphological evolution of disk galaxies induced by density wave modes. In particular, we address the demands collective effects place on the choice of simulation parameters, and show that the common practice of the use of a large gravity softening parameter was responsible for the failure of past simulations to correctly model the secular evolution process in galaxies, even for those simulations where the choice of basic state allows an unstable mode to emerge, a prerequisite for obtaining the coordinated radial mass flow pattern needed for secular evolution of galaxies along the Hubble sequence. We also demonstrate that the secular evolution rates measured in our improved simulations agree to an impressive degree with the corresponding rates predicted by the recently-advanced theories of dynamically-driven secular evolution of galaxies. The results of the current work, besides having direct implications on the cosmological evolution of galaxies, also shed light on the general question of how irreversibility emerges from a nominally reversible physical system.

Transportation Energy Futures: Freight Transportation Modal Shares: Scenarios for a Low-Carbon Future

DOE Office of Scientific and Technical Information (OSTI.GOV)

Brogan, J. J.; Aeppli, A. E.; Brown, D. F.

2013-03-01

Freight transportation modes—truck, rail, water, air, and pipeline—each serve a distinct share of the freight transportation market. A variety of factors influence the modes chosen by shippers, carriers, and others involved in freight supply chains. Analytical methods can be used to project future modal shares, and federal policy actions could influence future freight mode choices. This report considers how these topics have been addressed in existing literature and offers insights on federal policy decisions with the potential to prompt mode choices that reduce energy use and greenhouse gas emissions.

The dependence of acoustic properties of a crack on the resonance mode and geometry

USGS Publications Warehouse

Kumagai, H.; Chouet, B.A.

2001-01-01

We examine the dependence of the acoustic properties of a crack containing magmatic or hydrothermal fluids on the resonance mode and geometry to quantify the source properties of long-period (LP) events observed in volcanic areas. Our results, based on spectral analyses of synthetic waveforms generated with a fluid-driven crack model, indicate that the basic features of the dimensionless frequency (??) and quality factor (Qr) for a crack containing various types of fluids are not strongly affected by the choice of mode, although the actual ranges of Q?? and ?? both depend on the mode. The dimensionless complex frequency systematically varies with changes in the crack geometry, showing increases in both Qr and ?? as the crack length to aperture ratio decreases. The present results may be useful for the interpretation of spatial and temporal variations in the observed complex frequencies of LP events.

Choice of commuting mode among employees: Do home neighborhood environment, worksite neighborhood environment, and worksite policy and supports matter?

PubMed Central

Yang, Lin; Hipp, J. Aaron; Adlakha, Deepti; Marx, Christine M.; Tabak, Rachel G.; Brownson, Ross C.

2015-01-01

Background Promoting the use of public transit and active transport (walking and cycling) instead of car driving is an appealing strategy to increase overall physical activity. Purpose To quantify the combined associations between self-reported home and worksite neighborhood environments, worksite support and policies, and employees’ commuting modes. Method Between 2012 and 2013, participants residing in four Missouri metropolitan areas were interviewed via telephone (n = 1,338) and provided information on socio-demographic characteristics, home and worksite neighborhoods, and worksite support and policies. Commuting mode was self-reported and categorized into car driving, public transit, and active commuting. Commuting distance was calculated using geographic information systems. Commuters providing completed data were included in the analysis. Multivariate logistic regression models were used to examine the correlates of using public transit and active commuting. Result The majority of participants reported commuting by driving (88.9%); only 4.9% used public transit and 6.2% used active modes. After multivariate adjustment, having transit stops within 10-15 minutes walking distance from home (p=0.05) and using worksite incentive for public transit (p<0.001) were associated with commuting by public transit. Commuting distance (p<0.001) was negatively associated with active commuting. Having free or low cost recreation facilities around the worksite (p=0.04) and using bike facilities to lock bikes at the worksite (p<0.001) were associated with active commuting. Conclusion Both environment features and worksite supports and policies are associated with the choice of commuting mode. Future studies should use longitudinal designs to investigate the potential of promoting alternative commuting modes through worksite efforts that support sustainable commuting behaviors as well as the potential of built environment improvements. PMID:26085979

Internet and telephonic IVR mixed-mode survey for longitudinal studies: choice, retention, and data equivalency.

PubMed

Verma, Santosh K; Courtney, Theodore K; Lombardi, David A; Chang, Wen-Ruey; Huang, Yueng-Hsiang; Brennan, Melanye J; Perry, Melissa J

2014-01-01

This study examined data equivalency and loss to follow-up rates from Internet and interactive voice response (IVR) system surveys in a prospective-cohort study. 475 limited-service restaurant workers participating in the 12-week study were given a choice to report their weekly slipping experience by either IVR or Internet. Demographic differences, loss to follow-up, self-reported rates of slipping, and selection of first and last choices were compared. Loss to follow-up rates were slightly higher for those choosing the IVR mode. Rates of slipping and selection of first and last choices were not significantly different between survey modes. Propensity to choose an Internet survey decreased with increasing age, and was the lowest among Spanish speakers (5%) and those with less than a high school education (14%). Studies relying solely on Internet-based data collection may lead to selective exclusion of certain populations. Findings suggest that Internet and IVR may be combined as survey modalities within longitudinal studies. Copyright © 2014 The Authors. Published by Elsevier Inc. All rights reserved.

Co-digestion of solid waste: Towards a simple model to predict methane production.

PubMed

Kouas, Mokhles; Torrijos, Michel; Schmitz, Sabine; Sousbie, Philippe; Sayadi, Sami; Harmand, Jérôme

2018-04-01

Modeling methane production is a key issue for solid waste co-digestion. Here, the effect of a step-wise increase in the organic loading rate (OLR) on reactor performance was investigated, and four new models were evaluated to predict methane yields using data acquired in batch mode. Four co-digestion experiments of mixtures of 2 solid substrates were conducted in semi-continuous mode. Experimental methane yields were always higher than the BMP values of mixtures calculated from the BMP of each substrate, highlighting the importance of endogenous production (methane produced from auto-degradation of microbial community and generated solids). The experimental methane productions under increasing OLRs corresponded well to the modeled data using the model with constant endogenous production and kinetics identified at 80% from total batch time. This model provides a simple and useful tool for technical design consultancies and plant operators to optimize the co-digestion and the choice of the OLRs. Copyright © 2018 Elsevier Ltd. All rights reserved.

To walk or to fly? How birds choose among foraging modes

PubMed Central

Bautista, Luis M.; Tinbergen, Joost; Kacelnik, Alejandro

2001-01-01

We test the predictive value of the main energetic currencies used in foraging theory using starlings that choose between two foraging modes (walking versus flying). Walking is low-cost, low-yield, whereas flying is the opposite. We fixed experimentally, at 11 different values, the amount of flight required to get one food reward, and for each flight cost value, we titrated the amount of walking until the birds showed indifference between foraging modes. We then compared the indifference points to those predicted by gross rate of gain over time, net rate of gain over time, and the ratio of gain to expenditure (efficiency). The results for the choice between modes show strong qualitative and quantitative support for net rate of gain over time over the alternatives. However, the birds foraged for only a fraction of the available time, indicating that the choice between foraging and resting could not be explained by any of these currencies. We suggest that this discrepancy could be accounted for functionally because nonenergetic factors such as predation risk may differ between resting and foraging in any mode but may not differ much between foraging modes, hence releasing the choice between foraging modes from the influence of such factors. Alternatively, the discrepancy may be attributable to the use of predictable (rather than stochastic) ratios of effort per prey in our experiment, and it may thus be better understood with mechanistic rather than functional arguments. PMID:11158599

To walk or to fly? How birds choose among foraging modes.

PubMed

Bautista, L M; Tinbergen, J; Kacelnik, A

2001-01-30

We test the predictive value of the main energetic currencies used in foraging theory using starlings that choose between two foraging modes (walking versus flying). Walking is low-cost, low-yield, whereas flying is the opposite. We fixed experimentally, at 11 different values, the amount of flight required to get one food reward, and for each flight cost value, we titrated the amount of walking until the birds showed indifference between foraging modes. We then compared the indifference points to those predicted by gross rate of gain over time, net rate of gain over time, and the ratio of gain to expenditure (efficiency). The results for the choice between modes show strong qualitative and quantitative support for net rate of gain over time over the alternatives. However, the birds foraged for only a fraction of the available time, indicating that the choice between foraging and resting could not be explained by any of these currencies. We suggest that this discrepancy could be accounted for functionally because nonenergetic factors such as predation risk may differ between resting and foraging in any mode but may not differ much between foraging modes, hence releasing the choice between foraging modes from the influence of such factors. Alternatively, the discrepancy may be attributable to the use of predictable (rather than stochastic) ratios of effort per prey in our experiment, and it may thus be better understood with mechanistic rather than functional arguments.

Mode locking and quasiperiodicity in a discrete-time Chialvo neuron model

NASA Astrophysics Data System (ADS)

Wang, Fengjuan; Cao, Hongjun

2018-03-01

The two-dimensional parameter spaces of a discrete-time Chialvo neuron model are investigated. Our studies demonstrate that for all our choice of two parameters (i) the fixed point is destabilized via Neimark-Sacker bifurcation; (ii) there exist mode locking structures like Arnold tongues and shrimps, with periods organized in a Farey tree sequence, embedded in quasiperiodic/chaotic region. We determine analytically the location of the parameter sets where Neimark-Sacker bifurcation occurs, and the location on this curve where Arnold tongues of arbitrary period are born. Properties of the transition that follows the so-called two-torus from quasiperiodicity to chaos are presented clearly and proved strictly by using numerical simulations such as bifurcation diagrams, the largest Lyapunov exponent diagram on MATLAB and C++.

Train users’ perceptions of walking distance to train station and attributes of paratransit service: understanding their association with decision using paratransit or not towards the train station

NASA Astrophysics Data System (ADS)

Syafriharti, R.; Kombaitan, B.; Kusumantoro, I. P.; Syabri, I.

2018-05-01

Access mode is an important factor in public transport systems. Most of the train users from Cicalengka to Padalarang via Bandung use paratransit as access mode. Access modes under this study are only paratransit and walking. This study aims to explore the relationship between access mode choice to the station and the perception about walking distance to station, perception about attributes of paratransit service quality which consist of accessibility, cheapness, comfortable, swiftness, safety, security and easiness. Of all the variables tested, walking distance to the station is the only variable relating to the mode access choice. So, a person will tend to use paratransit when his/her perception of walking distance to station is relatively far away. While perceptions about the quality of paratransit service can not determine whether a person will choose paratransit or not.

Representation of Nucleation Mode Microphysics in a Global Aerosol Model with Sectional Microphysics

NASA Technical Reports Server (NTRS)

Lee, Y. H.; Pierce, J. R.; Adams, P. J.

2013-01-01

In models, nucleation mode (1 nm

Pitting intuitive and analytical thinking against each other: the case of transitivity.

PubMed

Rusou, Zohar; Zakay, Dan; Usher, Marius

2013-06-01

Identifying which thinking mode, intuitive or analytical, yields better decisions has been a major subject of inquiry by decision-making researchers. Yet studies show contradictory results. One possibility is that the ambiguity is due to the variability in experimental conditions across studies. Our hypothesis is that decision quality depends critically on the level of compatibility between the thinking mode employed in the decision and the nature of the decision-making task. In two experiments, we pitted intuition and analytical thinking against each other on tasks that were either mainly intuitive or mainly analytical. Thinking modes, as well as task characteristics, were manipulated in a factorial design, with choice transitivity as the dependent measure. Results showed higher choice consistency (transitivity) when thinking mode and the characteristics of the decision task were compatible.

Determinants of edible oil choice by households in Tamil Nadu, India.

PubMed

Govindaraj, Gurrappa Naidu; Suryaprakash, Satrasala

2013-01-01

This study investigated the major determinants that influence the choice of edible oils by households across geographical zones in Tamil Nadu state, India. The primary data from 1,000 sample households were collected using a structured pre-tested questionnaire. Multinomial logit model was fitted for determining the factors. The results revealed that education, income, and households with a history of health problems were the important determinants that influenced the choice of low-saturated-fat oils, whereas the larger size households and weaker section households preferred low-priced palm oil. Income and education levels in Tamil Nadu state surged ahead in recent years. In consonance to these changes the nontraditional low-saturated fat containing sunflower oil demand will increase in many folds in coming years. Hence, besides traditional oils, sunflower oil production has to be stepped up on "mission mode" through appropriate production programs to meet the present and future edible oil demand domestically.

Provision of information about newborn screening antenatally: a sequential exploratory mixed-methods project.

PubMed

Ulph, Fiona; Wright, Stuart; Dharni, Nimarta; Payne, Katherine; Bennett, Rebecca; Roberts, Stephen; Walshe, Kieran; Lavender, Tina

2017-10-01

Participation in the UK Newborn Bloodspot Screening Programme (NBSP) requires parental consent but concerns exist about whether or not this happens in practice and the best methods and timing to obtain consent at reasonable cost. To collate all possible modes of prescreening communication and consent for newborn (neonatal) screening (NBS); examine midwives', screening professionals' and users' views about the feasibility, efficiency and impact on understanding of each; measure midwives' and parents' preferences for information provision; and identify key drivers of cost-effectiveness for alternative modes of information provision. Six study designs were used: (1) realist review - to generate alternative communication and consent models; (2) qualitative interviews with parents and health professionals - to examine the implications of current practice for understanding and views on alternative models; (3) survey and observation of midwives - to establish current costs; (4) stated preference surveys with midwives, parents and potential future parents - to establish preferences for information provision; (5) economic analysis - to identify cost-effectiveness drivers of alternative models; and (6) stakeholder validation focus groups and interviews - to examine the acceptability, views and broader impact of alternative communication and consent models. Providers and users of NBS in England. Study 2: 45 parents and 37 health professionals; study 3: 22 midwives and eight observations; study 4: 705 adults aged 18-45 years and 134 midwives; and study 6: 12 health-care professionals and five parents. The realist review identified low parental knowledge and evidence of coercive consent practices. Interview, focus group and stated preference data suggested a preference for full information, with some valuing this more than choice. Health professionals preferred informed choice models but parents and health professionals queried whether or not current consent was fully informed. Barriers to using leaflets effectively were highlighted. All studies indicated that a 'personalised' approach to NBS communication, allowing parents to select the mode and level of information suited to their learning needs, could have added value. A personalised approach should rely on midwife communication and should occur in the third trimester. Overall awareness was identified as requiring improvement. Starting NBS communication by alerting parents that they have a choice to make and telling them that samples could be stored are both likely to enhance engagement. The methods of information provision and maternal anxiety causing additional visits to health-care professionals were the drivers of relative cost-effectiveness. Lack of data to populate an economic analysis, confirmed by value of information analysis, indicated a need for further research. There are some limitations with regard to the range of participants used in studies 2 and 3 and so caution should be exercised when interpreting some of the results. This project highlighted the importance of focusing on information receipt and identified key communication barriers. Health professionals strongly preferred informed consent, which parents endorsed if they were made aware of sample storage. Uniform models of information provision were perceived as ineffective. A choice of information provision was supported by health professionals and parents, which both enhances cost-effectiveness and improves engagement, understanding and the validity of consent. Remaining uncertainties suggest that more research is needed before new communication modes are introduced into practice. Future research should measure the impact of the suggested practice changes (informing in third trimester, information toolkits, changed role of midwife). Current Controlled Trials ISRCTN70227207. This project was funded by the NIHR Health Technology Assessment programme and will be published in full in Health Technology Assessment ; Vol. 21, No. 55. See the NIHR Journals Library website for further project information.

[Patents and innovations. Definitions--modes of action].

PubMed

Lodde, J P

1994-06-01

The author presents the various methods available for the doctor to protect and exploit his inventions or technological discoveries. In the medical field, as in other fields, there are three titles of industrial property: patent, registered model and trademark. The modalities of each of these titles are explained. Based on the his own experience, the author presents advice concerning the use of patents, contracts and the choice of industrial partners.

Pricing decisions from experience: the roles of information-acquisition and response modes.

PubMed

Golan, Hagai; Ert, Eyal

2015-03-01

While pricing decisions that are based on experience are quite common, e.g., setting a selling price for a used car, this type of decision has been surprisingly overlooked in psychology and decision research. Previous studies have focused on either choice decisions from experience, or pricing decisions from description. Those studies revealed that pricing involves cognitive mechanisms other than choice, while experience-based decisions involve mechanisms that differ from description-based ones. Thus, the mutual effect of pricing and experience on decision-making remains unclear. To test this effect, we experimentally compared real-money pricing decisions from experience with those from description, and with choices from experience. The results show that the mode of acquiring information affects pricing: the tendency to underprice high-probability prospects and overprice low-probability ones is diminished when pricing is based on experience rather than description. The findings further reveal attenuation of the tendency to underweight rare events, which underlies choices from experience, in pricing decisions from experience. The difference occurs because the response mode affects the search effort and decision strategy in decisions from experience. Copyright © 2014 Elsevier B.V. All rights reserved.

Free-space propagation of high-dimensional structured optical fields in an urban environment

PubMed Central

Lavery, Martin P. J.; Peuntinger, Christian; Günthner, Kevin; Banzer, Peter; Elser, Dominique; Boyd, Robert W.; Padgett, Miles J.; Marquardt, Christoph; Leuchs, Gerd

2017-01-01

Spatially structured optical fields have been used to enhance the functionality of a wide variety of systems that use light for sensing or information transfer. As higher-dimensional modes become a solution of choice in optical systems, it is important to develop channel models that suitably predict the effect of atmospheric turbulence on these modes. We investigate the propagation of a set of orthogonal spatial modes across a free-space channel between two buildings separated by 1.6 km. Given the circular geometry of a common optical lens, the orthogonal mode set we choose to implement is that described by the Laguerre-Gaussian (LG) field equations. Our study focuses on the preservation of phase purity, which is vital for spatial multiplexing and any system requiring full quantum-state tomography. We present experimental data for the modal degradation in a real urban environment and draw a comparison to recognized theoretical predictions of the link. Our findings indicate that adaptations to channel models are required to simulate the effects of atmospheric turbulence placed on high-dimensional structured modes that propagate over a long distance. Our study indicates that with mitigation of vortex splitting, potentially through precorrection techniques, one could overcome the challenges in a real point-to-point free-space channel in an urban environment. PMID:29075663

Free-space propagation of high-dimensional structured optical fields in an urban environment.

PubMed

Lavery, Martin P J; Peuntinger, Christian; Günthner, Kevin; Banzer, Peter; Elser, Dominique; Boyd, Robert W; Padgett, Miles J; Marquardt, Christoph; Leuchs, Gerd

2017-10-01

Spatially structured optical fields have been used to enhance the functionality of a wide variety of systems that use light for sensing or information transfer. As higher-dimensional modes become a solution of choice in optical systems, it is important to develop channel models that suitably predict the effect of atmospheric turbulence on these modes. We investigate the propagation of a set of orthogonal spatial modes across a free-space channel between two buildings separated by 1.6 km. Given the circular geometry of a common optical lens, the orthogonal mode set we choose to implement is that described by the Laguerre-Gaussian (LG) field equations. Our study focuses on the preservation of phase purity, which is vital for spatial multiplexing and any system requiring full quantum-state tomography. We present experimental data for the modal degradation in a real urban environment and draw a comparison to recognized theoretical predictions of the link. Our findings indicate that adaptations to channel models are required to simulate the effects of atmospheric turbulence placed on high-dimensional structured modes that propagate over a long distance. Our study indicates that with mitigation of vortex splitting, potentially through precorrection techniques, one could overcome the challenges in a real point-to-point free-space channel in an urban environment.

Different Identity Revelation Modes in an Online Peer-Assessment Learning Environment: Effects on Perceptions toward Assessors, Classroom Climate and Learning Activities

ERIC Educational Resources Information Center

Yu, Fu-Yun; Wu, Chun-Ping

2011-01-01

The effects of four different identity revelation modes (three fixed modes: real-name, anonymity, nickname and one dynamic user self-choice mode) on participants' perceptions toward their assessors, classroom climate, and past experience with the learning activity in which they were engaged were examined. A pretest-posttest quasi-experimental…

Atomic force microscopy contact, tapping, and jumping modes for imaging biological samples in liquids

NASA Astrophysics Data System (ADS)

Moreno-Herrero, F.; Colchero, J.; Gómez-Herrero, J.; Baró, A. M.

2004-03-01

The capabilities of the atomic force microscope for imaging biomolecules under physiological conditions has been systematically investigated. Contact, dynamic, and jumping modes have been applied to four different biological systems: DNA, purple membrane, Alzheimer paired helical filaments, and the bacteriophage φ29. These samples have been selected to cover a wide variety of biological systems in terms of sizes and substrate contact area, which make them very appropriate for the type of comparative studies carried out in the present work. Although dynamic mode atomic force microscopy is clearly the best choice for imaging soft samples in air, in liquids there is not a leading technique. In liquids, the most appropriate imaging mode depends on the sample characteristics and preparation methods. Contact or dynamic modes are the best choices for imaging molecular assemblies arranged as crystals such as the purple membrane. In this case, the advantage of image acquisition speed predominates over the disadvantage of high lateral or normal force. For imaging individual macromolecules, which are weakly bonded to the substrate, lateral and normal forces are the relevant factors, and hence the jumping mode, an imaging mode which minimizes lateral and normal forces, is preferable to other imaging modes.

Accessibility Measures: Formulation Considerations and Current Applications

DOT National Transportation Integrated Search

2000-09-01

This report examines micro-scale and macro-scale factors for inclusion in an ideal accessibility measure. Their potential influence on the evaluation of mode choice and destination choice is discussed. Availability in Texas' major cities is presented...

OEDGE modeling for the planned tungsten ring experiment on DIII-D

DOE PAGES

Elder, J. David; Stangeby, Peter C.; Abrams, Tyler W.; ...

2017-04-19

The OEDGE code is used to model tungsten erosion and transport for DIII-D experiments with toroidal rings of high-Z metal tiles. Such modeling is needed for both experimental and diagnostic design to have estimates of the expected core and edge tungsten density and to understand the various factors contributing to the uncertainties in these calculations. OEDGE simulations are performed using the planned experimental magnetic geometries and plasma conditions typical of both L-mode and inter-ELM H-mode discharges in DIII-D. OEDGE plasma reconstruction based on specific representative discharges for similar geometries is used to determine the plasma conditions applied to tungsten plasmamore » impurity simulations. We developed a new model for tungsten erosion in OEDGE which imports charge-state resolved carbon impurity fluxes and impact energies from a separate OEDGE run which models the carbon production, transport and deposition for the same plasma conditions as the tungsten simulations. Furthermore, these values are then used to calculate the gross tungsten physical sputtering due to carbon plasma impurities which is then added to any sputtering by deuterium ions; tungsten self-sputtering is also included. The code results are found to be dependent on the following factors: divertor geometry and closure, the choice of cross-field anomalous transport coefficients, divertor plasma conditions (affecting both tungsten source strength and transport), the choice of tungsten atomic physics data used in the model (in particular sviz(Te) for W-atoms), and the model of the carbon flux and energy used for 2 calculating the tungsten source due to sputtering. The core tungsten density is found to be of order 10 15 m -3 (excluding effects of any core transport barrier and with significant variability depending on the other factors mentioned) with density decaying into the scrape off layer.« less

Quasi-periodic oscillations and the global modes of relativistic, MHD accretion discs

NASA Astrophysics Data System (ADS)

Dewberry, Janosz W.; Latter, Henrik N.; Ogilvie, Gordon I.

2018-05-01

The high-frequency quasi-periodic oscillations that punctuate the light curves of X-ray binary systems present a window on to the intrinsic properties of stellar-mass black holes and hence a testbed for general relativity. One explanation for these features is that relativistic distortion of the accretion disc's differential rotation creates a trapping region in which inertial waves (r-modes) might grow to observable amplitudes. Local analyses, however, predict that large-scale magnetic fields push this trapping region to the inner disc edge, where conditions may be unfavourable for r-mode growth. We revisit this problem from a pseudo-Newtonian but fully global perspective, deriving linearized equations describing a relativistic, magnetized accretion flow, and calculating normal modes with and without vertical density stratification. In an unstratified model we confirm that vertical magnetic fields drive r-modes towards the inner edge, though the effect depends on the choice of vertical wavenumber. In a global model we better quantify this susceptibility, and its dependence on the disc's vertical structure and thickness. Our calculations suggest that in thin discs, r-modes may remain independent of the inner disc edge for vertical magnetic fields with plasma betas as low as β ≈ 100-300. We posit that the appearance of r-modes in observations may be more determined by a competition between excitation and damping mechanisms near the ISCO than by the modification of the trapping region by magnetic fields.

Preference Reversals Between Joint and Separate Evaluations With Multiple Alternatives and Context Effects.

PubMed

Cheng, Yin-Hui; Yu, Annie P; Huang, Molly Chien-Jung; Dai, Chia-Jung

2017-01-01

Most research on preference reversal (PR) focuses on the evaluability hypothesis with one or two alternatives. However, people normally encounter more than two options in daily life. In this research, a third option was added to the PR effect choice sets in the traditional joint-separate evaluations mode to create a context effect. Three studies were conducted. Studies 1 and 2 showed that adding a third option to the choice sets changed the PR effect; either the attributes were both important or one was important and the other was not. Study 3 showed that the PR effect reappeared when a third option was added to the choice sets that had no PR effect with just two attributes that were difficult to evaluate independently in traditional evaluations modes. The three studies confirmed that preferences changed in multi-alternative evaluation modes, contradicting Hsee's (1996) work and showing that the context effect is stronger than that of the attribute's importance in the PR effect.

The Integrated Airport Competition Model, 1998

NASA Technical Reports Server (NTRS)

Veldhuis, J.; Essers, I.; Bakker, D.; Cohn, N.; Kroes, E.

1999-01-01

This paper addresses recent model development by the Directorate General of Civil Aviation (DGCA) and Hague Consulting Group (HCG) concerning long-distance travel. Long-distance travel demand is growing very quickly and raising a great deal of economic and policy issues. There is increasing competition among the main Western European airports, and smaller, regional airports are fighting for market share. New modes of transport, such as high speed rail, are also coming into the picture and affect the mode split for medium distance transport within Europe. Developments such as these are demanding the attention of policy makers and a tool is required for their analysis. For DGCA, Hague Consulting Group has developed a model system to provide answers to the policy questions posed by these expected trends, and to identify areas where policy makers can influence the traveller choices. The development of this model system, the Integrated Airport Competition Model/integraal Luchthaven Competitie Model (ILCM), began in 1992. Since that time the sub-models, input data and user interface have been expanded, updated and improved. HCG and DGCA have transformed the ILCM from a prototype into an operational forecasting tool.

The Integrated Airport Competition Model, 1998

NASA Technical Reports Server (NTRS)

Veldhuis, J.; Essers, I.; Bakker, D.; Cohn, N.; Kroes, E.

1999-01-01

This paper addresses recent model development by the Directorate General of Civil Aviation (DGCA) and Hague Consulting Group (HCG) concerning long-distance travel, Long-distance travel demand is growing very quickly and raising a great deal of economic and policy issues. There is increasing competition among the main Western European airports, and smaller, regional airports are fighting for market share. New modes of transport, such as high speed rail, arc also coming into the picture and affect the mode split for medium distance transport within Europe. Developments such as these are demanding the attention of policy makers and a tool is required for their analysis. For DGCA, Hague Consulting Group has developed a model system to provide answers to the policy questions posed by these expected trends, and to identify areas where policy makers can influence the traveller choices. The development of this model system, the Integrated Airport Competition Model/Integral Luchthaven Competitive Model (ILCM), began in 1992. Since that time the sub-models, input data and user interface have been expanded, updated and improved. HCG and DGCA have transformed the ILCM from a prototype into an operational forecasting tool.

Construction and identification of a D-Vine model applied to the probability distribution of modal parameters in structural dynamics

NASA Astrophysics Data System (ADS)

Dubreuil, S.; Salaün, M.; Rodriguez, E.; Petitjean, F.

2018-01-01

This study investigates the construction and identification of the probability distribution of random modal parameters (natural frequencies and effective parameters) in structural dynamics. As these parameters present various types of dependence structures, the retained approach is based on pair copula construction (PCC). A literature review leads us to choose a D-Vine model for the construction of modal parameters probability distributions. Identification of this model is based on likelihood maximization which makes it sensitive to the dimension of the distribution, namely the number of considered modes in our context. To this respect, a mode selection preprocessing step is proposed. It allows the selection of the relevant random modes for a given transfer function. The second point, addressed in this study, concerns the choice of the D-Vine model. Indeed, D-Vine model is not uniquely defined. Two strategies are proposed and compared. The first one is based on the context of the study whereas the second one is purely based on statistical considerations. Finally, the proposed approaches are numerically studied and compared with respect to their capabilities, first in the identification of the probability distribution of random modal parameters and second in the estimation of the 99 % quantiles of some transfer functions.

A Logical Account of Diagnosis with Multiple Theories

NASA Technical Reports Server (NTRS)

Pandurang, P.; Lum, Henry Jr. (Technical Monitor)

1994-01-01

Model-based diagnosis is a powerful, first-principles approach to diagnosis. The primary drawback with model-based diagnosis is that it is based on a system model, and this model might be inappropriate. The inappropriateness of models usually stems from the fundamental tradeoff between completeness and efficiency. Recently, Struss has developed an elegant proposal for diagnosis with multiple models. Struss characterizes models as relations and develops a precise notion of abstraction. He defines relations between models and analyzes the effect of a model switch on the space of possible diagnoses. In this paper we extend Struss's proposal in three ways. First, our account of diagnosis with multiple models is based on representing models as more expressive first-order theories, rather than as relations. A key technical contribution is the use of a general notion of abstraction based on interpretations between theories. Second, Struss conflates component modes with models, requiring him to define models relations such as choices which result in non-relational models. We avoid this problem by differentiating component modes from models. Third, we present a more general account of simplifications that correctly handles situations where the simplification contradicts the base theory.

Vibration suppression and slewing control of a flexible structure

NASA Technical Reports Server (NTRS)

Inman, Daniel J.; Garcia, Ephrahim; Pokines, Brett

1991-01-01

Examined here are the effects of motor dynamics and secondary piezoceramic actuators on vibration suppression during the slewing of flexible structures. The approach focuses on the interaction between the structure, the actuators, and the choice of control law. The results presented here are all simulated, but are based on experimentally determined parameters for the motor, structure, piezoceramic actuators, and piezofilm sensors. The simulation results clearly illustrate that the choice of motor inertia relative to beam inertia makes a critical difference in the performance of the system. In addition, the use of secondary piezoelectric actuators reduces the load requirements on the motor and also reduces the overshoot of the tip deflection. The structures considered here are a beam and a frame. The majority of results are based on a Euler Bernoulli beam model. The slewing frame introduces substantial torsional modes and a more realistic model. The slewing frame results are incomplete and represent work in progress.

Motivation and justification: a dual-process model of culture in action.

PubMed

Vaisey, Stephen

2009-05-01

This article presents a new model of culture in action. Although most sociologists who study culture emphasize its role in post hoc sense making, sociologists of religion and social psychologists tend to focus on the role beliefs play in motivation. The dual-process model integrates justificatory and motivational approaches by distinguishing between "discursive" and "practical" modes of culture and cognition. The author uses panel data from the National Study of Youth and Religion to illustrate the model's usefulness. Consistent with its predictions, he finds that though respondents cannot articulate clear principles of moral judgment, their choice from a list of moral-cultural scripts strongly predicts later behavior.

Simplified THz Instrumentation for High-Field DNP-NMR Spectroscopy

PubMed Central

Sirigiri, Jagadishwar R.

2012-01-01

We present an alternate simplified concept to irradiate a nuclear magnetic resonance sample with terahertz (THz) radiation for dynamic nuclear polarization (DNP) experiments using the TE01 circular waveguide mode for transmission of the THz power and the illumination of the DNP sample by either the TE01 or TE11 mode. Using finite element method and 3D electromagnetic simulations we demonstrate that the average value of the transverse magnetic field induced by the THz radiation and responsible for the DNP effect using the TE11 or the TE01 mode are comparable to that generated by the HE11 mode and a corrugated waveguide. The choice of the TE11/TE01 mode allows the use of a smooth-walled, oversized waveguide that is easier to fabricate and less expensive than a corrugated waveguide required for transmission of the HE11 mode. Also, the choice of the TE01 mode can lead to a simplification of gyrotron oscillators that operate in the TE0n mode, by employing an on-axis rippled-wall mode converter to convert the TE0n mode into the TE01 mode either inside or outside of the gyrotron tube. These novel concepts will lead to a significant simplification of the gyrotron, the transmission line and the THz coupler, which are the three main components of a DNP system. PMID:22977293

Localized tearing modes in the magnetotail driven by curvature effects

NASA Technical Reports Server (NTRS)

Sundaram, A. K.; Fairfield, D. H.

1995-01-01

The stability of collisionless tearing modes is examined in the presence of curvature drift resonances and the trapped particle effects. A kinetic description for both electrons and ions is employed to investigate the stability of a two-dimensional equilibrium model. The main features of the study are to treat the ion dynamics properly by incorporating effects associated with particle trajectories in the tail fields and to include the linear coupling of trapped particle modes. Generalized dispersion relations are derived in several parameter regimes by considering two important sublayers of the reconnecting region. For a typical choice of parameters appropriate to the current sheet region, we demonstrate that localized tearing modes driven by ion curvature drift resonance effects are excited in the current sheet region with growth time of the order of a few seconds. Also, we examine nonlocal characteristics of tearing modes driven by curvature effects and show that modes growing in a fraction of a second arise when mode widths are larger than the current sheet width. Further, we show that trapped particle effects, in an interesting frequency regime, significantly enhance the growth rate of the tearing mode. The relevance of this theory for substorm onset phase and other features of the substorms is briefly discussed.

Mode, load, and specific climate impact from passenger trips.

PubMed

Borken-Kleefeld, Jens; Fuglestvedt, Jan; Berntsen, Terje

2013-07-16

The climate impact from a long-distance trip can easily vary by a factor of 10 per passenger depending on mode choice, vehicle efficiency, and occupancy. In this paper we compare the specific climate impact of long-distance car travel with coach, train, or air trips. We account for both, CO2 emissions and short-lived climate forcers. This particularly affects the ranking of aircraft's climate impact relative to other modes. We calculate the specific impact for the Global Warming Potential and the Global Temperature Change Potential, considering time horizons between 20 and 100 years, and compare with results accounting only for CO2 emissions. The car's fuel efficiency and occupancy are central whether the impact from a trip is as high as from air travel or as low as from train travel. These results can be used for carbon-offsetting schemes, mode choice and transportation planning for climate mitigation.

FAMIAS User Manual

NASA Astrophysics Data System (ADS)

Zima, Wolfgang

2008-10-01

The excitation of pulsation modes in Beta Cephei and Slowly Pulsating B stars is known to be very sensitive to opacity changes in the stellar interior where T ~ 2 x 10E5 K. In this region differences in opacity up to ~ 50% can be induced by the choice between OPAL and OP opacity tables, and between two different metal mixtures (Grevesse & Noels 1993 and Asplund et al. 2005). We have extended the non-adiabatic computations presented in Miglio et al. (2007) towards models of higher mass and pulsation modes of degree l = 3, and we present here the instability domains in the HR- and log P-log Teff diagrams resulting from different choices of opacity tables, and for three different metallicities. FAMIAS (Frequency Analysis and Mode Identification for AsteroSeismology) is a collection of state-of-the-art software tools for the analysis of photometric and spectroscopic time series data. It is one of the deliverables of the Work Package NA5: Asteroseismology of the European Coordination Action in Helio-and Asteroseismology (HELAS). Two main sets of tools are incorporated in FAMIAS. The first set allows to search for periodicities in the data using Fourier and non-linear least-squares fitting algorithms. The other set allows to carry out a mode identification for the detected pulsation frequencies to determine their pulsational quantum numbers, the harmonic degree, m. The types of stars to which famias is applicable are main-sequence pulsators hotter than the Sun. This includes the Gamma Dor stars, Delta Sct stars, the slowly pulsating B stars and the Beta Cep stars - basically all pulsating main-sequence stars, for which empirical mode identification is required to successfully carry out asteroseismology. This user manual describes how to use the different features of FAMIAS and provides two tutorials that demonstrate the usage of FAMIAS for spectroscopic and photometric mode identification.

Food choices at lunch during the third year of life: high selection of animal and starchy foods but avoidance of vegetables.

PubMed

Nicklaus, Sophie; Boggio, Vincent; Issanchou, Sylvie

2005-07-01

The objective was to show patterns of food selection by 2- to 3-y-old children for a wide variety of foods in a self-service cafeteria and to assess the effect of individual variables (gender, BMI, mode of feeding after birth and rank in sibship). In a nursery self-service canteen, food choices at lunch made by children (n=418, 24-36 mo; 109 observations per child on average) were recorded by trained assistants who monitored portion size. An offer of eight dishes (animal products, starchy foods, combination dishes, vegetables and dairy products), excluding dessert-type foods, was proposed. Choice level was calculated for each food. Analysis of variance was used to compare choices for the various foods and to assess the effect of the individual variables. The choice of a food largely depended upon its nature: animal products, starchy foods and their combinations were widely chosen, whereas vegetables were not often selected; the choice for dairy products depended upon the type. The mode of preparation of the food influenced its choice. Segmenting products were identified; however, except for cheeses, a given child did not refuse an entire food category. Children's characteristics did not explain the choice variability. At the age of 2 to 3 y, children preferentially choose animal products and starchy foods and avoid vegetables; the high individual variability of their food choices could be related to previous food experiences.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Feng, Jun, E-mail: j.feng1@uq.edu.au; Zhang, Yao-Zhong; Gould, Mark D.

We study the quantum correlation and quantum communication channel of both free scalar and fermionic fields in de Sitter space, while the Planckian modification presented by the choice of a particular α-vacuum has been considered. We show the occurrence of degradation of quantum entanglement between field modes for an inertial observer in curved space, due to the radiation associated with its cosmological horizon. Comparing with standard Bunch–Davies choice, the possible Planckian physics causes some extra decrement on the quantum correlation, which may provide the means to detect quantum gravitational effects via quantum information methodology in future. Beyond single-mode approximation, wemore » construct proper Unruh modes admitting general α-vacua, and find a convergent feature of both bosonic and fermionic entanglements. In particular, we show that the convergent points of fermionic entanglement negativity are dependent on the choice of α. Moreover, an one-to-one correspondence between convergent points H{sub c} of negativity and zeros of quantum capacity of quantum channels in de Sitter space has been proved. - Highlights: • Quantum correlation and quantum channel in de Sitter space are studied. • Gibbons–Hawking effect causes entanglement degradation for static observer. • Planckian physics causes extra decrement on quantum correlation. • Convergent feature of negativity relies on the choice of alpha-vacua. • Link between negativity convergence and quantum channel capacity is given.« less

Making truck-rail intermodal more competitive.

DOT National Transportation Integrated Search

2010-09-01

Truck-rail intermodal freight is a technique that can gain much of the benefit of truck service and rail efficiency. Despite the attraction of the mode : choice and its benefit in reducing emissions and highway congestion, the mode typically is used ...

Factors Influencing Students' Choice of Study Mode: An Australian Case Study

ERIC Educational Resources Information Center

Ifenthaler, Dirk; Gosper, Maree; Bailey, Matthew; Kretzschmar, Mandy

2014-01-01

Despite the expansion of online and blended learning, as well as open education, little research has been undertaken on what motivates students to enrol in particular study modes at university level. This project addresses this gap in higher education research by exploring the reasons why humanities students choose to study through specific modes.…

Solving an emergency rescue materials problem under the joint reserves mode of government and framework agreement suppliers

PubMed Central

Sun, Xiao-Qing; Zhu, Rui; Li, Ming; Miao, Wang

2017-01-01

Emergency rescue material reserves are vital for the success of emergency rescue activities. In this study, we consider a situation where a government owned distribution center and framework agreement suppliers jointly store emergency rescue materials. Using a scenario-based approach to represent demand uncertainty, we propose a comprehensive transportation pattern for the following supply chain: “suppliers—government distribution center—disaster area.” Using a joint reserves model that includes the government and framework agreement suppliers, we develop a non-linear mathematic model that determines the choices of the framework suppliers, the corresponding optimal commitment quantities, and the quantity of materials that are stored at a government distribution center. Finally, we use IBM ILOG CPLEX to solve the numerical examples to verify the effectiveness of the mode and perform sensitivity analyses on the relevant parameters. PMID:29077722

Role of interbranch pumping on the quantum-statistical behavior of multi-mode magnons in ferromagnetic nanowires

NASA Astrophysics Data System (ADS)

Haghshenasfard, Zahra; Cottam, M. G.

2018-01-01

Theoretical studies are reported for the quantum-statistical properties of microwave-driven multi-mode magnon systems as represented by ferromagnetic nanowires with a stripe geometry. Effects of both the exchange and the dipole-dipole interactions, as well as a Zeeman term for an external applied field, are included in the magnetic Hamiltonian. The model also contains the time-dependent nonlinear effects due to parallel pumping with an electromagnetic field. Using a coherent magnon state representation in terms of creation and annihilation operators, we investigate the effects of parallel pumping on the temporal evolution of various nonclassical properties of the system. A focus is on the interbranch mixing produced by the pumping field when there are three or more modes. In particular, the occupation magnon number and the multi-mode cross correlations between magnon modes are studied. Manipulation of the collapse and revival phenomena of the average magnon occupation number and the control of the cross correlation between the magnon modes are demonstrated through tuning of the parallel pumping field amplitude and appropriate choices for the coherent magnon states. The cross correlations are a direct consequence of the interbranch pumping effects and do not appear in the corresponding one- or two-mode magnon systems.

Women's attitudes towards the medicalization of childbirth and their associations with planned and actual modes of birth.

PubMed

Benyamini, Yael; Molcho, Maya Lila; Dan, Uzi; Gozlan, Miri; Preis, Heidi

2017-10-01

Rates of medical interventions in childbirth have greatly increased in the Western world. Women's attitudes affect their birth choices. To assess women's attitudes towards the medicalization of childbirth and their associations with women's background as well as their fear of birth and planned and unplanned modes of birth. This longitudinal observational study included 836 parous woman recruited at women's health centres and natural birth communities in Israel. All women filled in questionnaires about attitudes towards the medicalization of childbirth, fear of birth, and planned birth choices. Women at <28 weeks gestation when filling in the questionnaire were asked to fill in a second one at ∼34 weeks. Phone follow-up was conducted ∼6 weeks postpartum to assess actual mode of birth. Attitudes towards medicalization were more positive among younger and less educated women, those who emigrated from the former Soviet Union, and those with a more complicated obstetric background. Baseline attitudes did not differ by parity yet became less positive throughout pregnancy only for primiparae. More positive attitudes were related to greater fear of birth. The attitudes were significantly associated with planned birth choices and predicted emergency caesareans and instrumental births. Women form attitudes towards the medicalization of childbirth which may still be open to change during the first pregnancy. More favourable attitudes are related to more medical modes of birth, planned and unplanned. Understanding women's views of childbirth medicalization may be key to understanding their choices and how they affect labour and birth. Copyright © 2017 Australian College of Midwives. Published by Elsevier Ltd. All rights reserved.

Tackling the conformational sampling of larger flexible compounds and macrocycles in pharmacology and drug discovery.

PubMed

Chen, I-Jen; Foloppe, Nicolas

2013-12-15

Computational conformational sampling underpins much of molecular modeling and design in pharmaceutical work. The sampling of smaller drug-like compounds has been an active area of research. However, few studies have tested in details the sampling of larger more flexible compounds, which are also relevant to drug discovery, including therapeutic peptides, macrocycles, and inhibitors of protein-protein interactions. Here, we investigate extensively mainstream conformational sampling methods on three carefully curated compound sets, namely the 'Drug-like', larger 'Flexible', and 'Macrocycle' compounds. These test molecules are chemically diverse with reliable X-ray protein-bound bioactive structures. The compared sampling methods include Stochastic Search and the recent LowModeMD from MOE, all the low-mode based approaches from MacroModel, and MD/LLMOD recently developed for macrocycles. In addition to default settings, key parameters of the sampling protocols were explored. The performance of the computational protocols was assessed via (i) the reproduction of the X-ray bioactive structures, (ii) the size, coverage and diversity of the output conformational ensembles, (iii) the compactness/extendedness of the conformers, and (iv) the ability to locate the global energy minimum. The influence of the stochastic nature of the searches on the results was also examined. Much better results were obtained by adopting search parameters enhanced over the default settings, while maintaining computational tractability. In MOE, the recent LowModeMD emerged as the method of choice. Mixed torsional/low-mode from MacroModel performed as well as LowModeMD, and MD/LLMOD performed well for macrocycles. The low-mode based approaches yielded very encouraging results with the flexible and macrocycle sets. Thus, one can productively tackle the computational conformational search of larger flexible compounds for drug discovery, including macrocycles. Copyright © 2013 Elsevier Ltd. All rights reserved.

Mixed-Methods Research Methodologies

ERIC Educational Resources Information Center

Terrell, Steven R.

2012-01-01

Mixed-Method studies have emerged from the paradigm wars between qualitative and quantitative research approaches to become a widely used mode of inquiry. Depending on choices made across four dimensions, mixed-methods can provide an investigator with many design choices which involve a range of sequential and concurrent strategies. Defining…

Empowering individuals to make environmentally sustainable and healthy transportation choices in mega-cities through a smartphone app.

DOT National Transportation Integrated Search

2015-04-01

A paradox of industrialized society is the overreliance on unsustainable fossil fuel energy for transportation and insufficient use of sustainable : bodily energy for more physically active modes of transport. Different modes of transportation requir...

Analysis of Small Aircraft as a Transportation System

NASA Technical Reports Server (NTRS)

Dollyhigh, Samuel M.; Yackovetsky, Robert E. (Technical Monitor)

2002-01-01

An analysis was conducted to examine the market viability of small aircraft as a transportation mode in competition with automobile and scheduled commercial air travel by estimating the pool of users that would potentially switch to on-demand air travel due to cost/time savings. The basis for the analysis model was the Integrated Air Transportation System Evaluation Tool (IATSET) which was developed under contract to NASA by the Logistics Management Institute. IATSET is a macroeconomic model that predicts at a National level the mode choice between automobile, scheduled air, and on-demand air travel based on the value of a travelers time and monetary cost of the trip. A number of modifications are detailed to the original IATSET to better model the changing small aircraft environment. The potential trip market was modeled for the Eclipse 500 operated as a corporate jet and as an air taxi for the business travel market. The Cirrus 20R and a $80K single engine piston aircraft (based on automobile manufacturing technology) are evaluated in the pleasure and personal business travel market.

Perceived risk and modal choice: risk compensation in transportation systems.

PubMed

Noland, R B

1995-08-01

A transportation mode choice analysis is performed that examines behavioral responses to perceived risk in the choice of mode for daily commute trips. This methodology provides a technique for examining, by means of disaggregate individual level data, risk-compensating effects in transportation systems. Various measures of perceived risk are examined for explaining modal choice. Other studies have described how safety regulations have resulted in increases in "driving intensity." This study defines one component of driving intensity to be the increased probability of commuting by automobile. The results show that modal shifts occur when risk perceptions for a given mode are reduced. To demonstrate potential risk-compensating effects within the transportation system, an estimate of changes in accident fatalities due to commuting is derived using rough estimates of fatalities per person-mile travelled. It is shown that a given change in the perceived risk of commuting by automobile results in a less than proportionate change in net commuting fatalities. The relative magnitude is dependent on how objective reductions in risk translate into perceived reductions in risk. This study also shows that perceived safety improvements in bicycle transportation have an aggregate elasticity value that is greater than one. This means that bicycle safety improvements attract proportionately more people to bicycle commuting (i.e. a 10% increase in safety results in a greater than 10% increase in the share of people bicycle commuting).

Identification of significant intrinsic mode functions for the diagnosis of induction motor fault.

PubMed

Cho, Sangjin; Shahriar, Md Rifat; Chong, Uipil

2014-08-01

For the analysis of non-stationary signals generated by a non-linear process like fault of an induction motor, empirical mode decomposition (EMD) is the best choice as it decomposes the signal into its natural oscillatory modes known as intrinsic mode functions (IMFs). However, some of these oscillatory modes obtained from a fault signal are not significant as they do not bear any fault signature and can cause misclassification of the fault instance. To solve this issue, a novel IMF selection algorithm is proposed in this work.

IMIS: An intelligence microscope imaging system

NASA Technical Reports Server (NTRS)

Caputo, Michael; Hunter, Norwood; Taylor, Gerald

1994-01-01

Until recently microscope users in space relied on traditional microscopy techniques that required manual operation of the microscope and recording of observations in the form of written notes, drawings, or photographs. This method was time consuming and required the return of film and drawings from space for analysis. No real-time data analysis was possible. Advances in digital and video technologies along with recent developments in article intelligence will allow future space microscopists to have a choice of three additional modes of microscopy: remote coaching, remote control, and automation. Remote coaching requires manual operations of the microscope with instructions given by two-way audio/video transmission during critical phases of the experiment. When using the remote mode of microscopy, the Principal Investigator controls the microscope from the ground. The automated mode employs artificial intelligence to control microscope functions and is the only mode that can be operated in the other three modes as well. The purpose of this presentation is to discuss the advantages and disadvantages of the four modes of of microscopy and how the IMIS, a proposed intelligent microscope imaging system, can be used as a model for developing and testing concepts, operating procedures, and equipment design of specifications required to provide a comprehensive microscopy/imaging capability onboard Space Station Freedom.

More than a Game...Teaching in the Gamic Mode: Disciplinary Knowledge, Digital Literacy, and Collaboration

ERIC Educational Resources Information Center

Clyde, Jerremie; Wilkinson, Glenn R.

2012-01-01

The gamic mode is an innovative way of authoring scholarly history that goes beyond the printed text or digital simulations by using digital game technologies to allow the reader to interact with a scholarly argument through meaningful choice and trial and error. The gamic mode makes the way in which the past is constructed as history explicit by…

The Impact of Microphysics and Planetary Boundary Layer Physics on Model Simulation of U.S. Deep South Summer Convection

NASA Technical Reports Server (NTRS)

McCaul, Eugene W., Jr.; Case, Jonathan L.; Zavodsky, Bradley T.; Srikishen, Jayanthi; Medlin, Jeffrey M.; Wood, Lance

2014-01-01

Inspection of output from various configurations of high-resolution, explicit convection forecast models such as the Weather Research and Forecasting (WRF) model indicates significant sensitivity to the choices of model physics pararneterizations employed. Some of the largest apparent sensitivities are related to the specifications of the cloud microphysics and planetary boundary layer physics packages. In addition, these sensitivities appear to be especially pronounced for the weakly-sheared, multicell modes of deep convection characteristic of the Deep South of the United States during the boreal summer. Possible ocean-land sensitivities also argue for further examination of the impacts of using unique ocean-land surface initialization datasets provided by the NASA Short-term Prediction Research and Transition (SPoRn Center to select NOAAlNWS weather forecast offices. To obtain better quantitative understanding of these sensitivities and also to determine the utility of the ocean-land initialization data, we have executed matrices of regional WRF forecasts for selected convective events near Mobile, AL (MOB), and Houston, TX (HGX). The matrices consist of identically initialized WRF 24-h forecasts using any of eight microphysics choices and any of three planetary boWldary layer choices. The resulting 24 simulations performed for each event within either the MOB or HGX regions are then compared to identify the sensitivities of various convective storm metrics to the physics choices. Particular emphasis is placed on sensitivities of precipitation timing, intensity, and coverage, as well as amount and coverage oflightuing activity diagnosed from storm kinematics and graupel in the mixed phase layer. The results confirm impressions gleaned from study of the behavior of variously configured WRF runs contained in the ensembles produced each spring at the Center for the Analysis and Prediction of Storms, but with the benefit of more straightforward control of the physics package choices. The design of the experiments thus allows for more direct interpretation of the sensitivities to each possible physics combination. The results should assist forecasters in their efforts to anticipate and correct for possible biases in simulated WRF convection patterns, and help the modeling community refine their model parameterizations.

The Impacts of Microphysics and Planetary Boundary Layer Physics on Model Simulations of U. S. Deep South Summer Convection

NASA Technical Reports Server (NTRS)

McCaul, E. W., Jr.; Case, J. L.; Zavodsky, B. T.; Srikishen, J.; Medlin, J. M.; Wood, L.

2014-01-01

Inspection of output from various configurations of high-resolution, explicit convection forecast models such as the Weather Research and Forecasting (WRF) model indicates significant sensitivity to the choices of model physics parameterizations employed. Some of the largest apparent sensitivities are related to the specifications of the cloud microphysics and planetary boundary layer physics packages. In addition, these sensitivities appear to be especially pronounced for the weakly-sheared, multicell modes of deep convection characteristic of the Deep South of the United States during the boreal summer. Possible ocean-land sensitivities also argue for further examination of the impacts of using unique ocean-land surface initialization datasets provided by the NASA Short-term Prediction Research and Transition (SPoRT Center to select NOAA/NWS weather forecast offices. To obtain better quantitative understanding of these sensitivities and also to determine the utility of the ocean-land initialization data, we have executed matrices of regional WRF forecasts for selected convective events near Mobile, AL (MOB), and Houston, TX (HGX). The matrices consist of identically initialized WRF 24-h forecasts using any of eight microphysics choices and any of three planetary boundary layer choices. The resulting 24 simulations performed for each event within either the MOB or HGX regions are then compared to identify the sensitivities of various convective storm metrics to the physics choices. Particular emphasis is placed on sensitivities of precipitation timing, intensity, and coverage, as well as amount and coverage of lightning activity diagnosed from storm kinematics and graupel in the mixed phase layer. The results confirm impressions gleaned from study of the behavior of variously configured WRF runs contained in the ensembles produced each spring at the Center for the Analysis and Prediction of Storms, but with the benefit of more straightforward control of the physics package choices. The design of the experiments thus allows for more direct interpretation of the sensitivities to each possible physics combination. The results should assist forecasters in their efforts to anticipate and correct for possible biases in simulated WRF convection patterns, and help the modeling community refine their model parameterizations.

Breech presentation and choice of mode of childbirth: a qualitative study of women's experiences.

PubMed

Guittier, Marie-Julia; Bonnet, Jocelyne; Jarabo, Graziella; Boulvain, Michel; Irion, Olivier; Hudelson, Patricia

2011-12-01

To explore women's perceptions of their experience of the diagnosis of breech presentation and decision-making processes regarding the choice of mode of childbirth. A qualitative study was conducted using semi-structured interviews. Data were analysed thematically. Department of Gynaecology and Obstetrics, University Hospitals of Geneva, Switzerland. seven primiparous and five multiparous women experiencing a singleton breech presentation for childbirth were interviewed. Two concomitant and interdependent processes were identified. First, an emotional response ranging from the hope that the fetus would return to a normal vertex position to the acceptance of breech presentation and its consequences. Second, a decision-making process related to childbirth mode for breech presentation with the complex management of intra- and extra-personal factor influences. Women perceive information about the risks of vaginal childbirth of paramount importance compared with those associated with caesarean childbirth. When women choose vaginal childbirth, influences related to their personality and life history appear to predominate. Women often have the feeling of being alone to assume the choice of childbirth mode and possible complications. The diagnosis of breech presentation should not be treated as a commonplace event. The role of caregivers needs to go beyond information on the risks and benefits of both modes of childbirth. Emphasis should be placed on listening to the expectations of pregnant women for childbirth, creating spaces for dialogue, and allowing additional time for reflection. Useful information material should be provided to give the women a feeling of shared decision-making. Copyright © 2010 Elsevier Ltd. All rights reserved.

Molecular-dynamics simulation of a model with incommensurate phases

NASA Astrophysics Data System (ADS)

Parlinski, Krzysztof

1987-06-01

Two-dimensional models of displacive and order-disorder behavior, in the form of crystallites with free boundary conditions and with one-dimensional incommensurate and/or commensurate phases, have been studied using the molecular-dynamics method. The incommensurate phase can be characterized with any wave vector by the appropriate choice of potential-energy parameters. The ground-state devil's staircases of the models are complete. By a series of cooling runs the phase diagram is established. The map of the particle configuration, a result of the cooling run, formed a nonideal incommensurate phase. In the diffraction pattern of that configuration the intensities of the satellites, especially those of higher order, are considerably lower. The displacive system shows a soft, underdamped phonon mode, which with lowering temperature condenses at the critical wave vector, producing the incommensurate phase, in which the phase and amplitude modes are observed. The phase-mode dispersion curve does not show a gap. Adding 2% point defects to the system does not influence the phase and amplitude modes. The kinetics of the variation of the wave-vector modulation of the incommensurate phase has also been studied. The relevant non- equilibrium devil's staircase exhibits quasisteps at irrational numbers which are attributed to the nucleation and growth of new incommensurate periods observed as a stripple. Examples of nucleation inside and at the edges of the crystallite are given. Point defects hinder the propagation of the deperiodization line which borders the stripple.

Permutation on hybrid natural inflation

NASA Astrophysics Data System (ADS)

Carone, Christopher D.; Erlich, Joshua; Ramos, Raymundo; Sher, Marc

2014-09-01

We analyze a model of hybrid natural inflation based on the smallest non-Abelian discrete group S3. Leading invariant terms in the scalar potential have an accidental global symmetry that is spontaneously broken, providing a pseudo-Goldstone boson that is identified as the inflaton. The S3 symmetry restricts both the form of the inflaton potential and the couplings of the inflaton field to the waterfall fields responsible for the end of inflation. We identify viable points in the model parameter space. Although the power in tensor modes is small in most of the parameter space of the model, we identify parameter choices that yield potentially observable values of r without super-Planckian initial values of the inflaton field.

ELM control with RMP: plasma response models and the role of edge peeling response

NASA Astrophysics Data System (ADS)

Liu, Yueqiang; Ham, C. J.; Kirk, A.; Li, Li; Loarte, A.; Ryan, D. A.; Sun, Youwen; Suttrop, W.; Yang, Xu; Zhou, Lina

2016-11-01

Resonant magnetic perturbations (RMP) have extensively been demonstrated as a plausible technique for mitigating or suppressing large edge localized modes (ELMs). Associated with this is a substantial amount of theory and modelling efforts during recent years. Various models describing the plasma response to the RMP fields have been proposed in the literature, and are briefly reviewed in this work. Despite their simplicity, linear response models can provide alternative criteria, than the vacuum field based criteria, for guiding the choice of the coil configurations to achieve the best control of ELMs. The role of the edge peeling response to the RMP fields is illustrated as a key indicator for the ELM mitigation in low collisionality plasmas, in various tokamak devices.

Supersymmetric gauged matrix models from dimensional reduction on a sphere

NASA Astrophysics Data System (ADS)

Closset, Cyril; Ghim, Dongwook; Seong, Rak-Kyeong

2018-05-01

It was recently proposed that N = 1 supersymmetric gauged matrix models have a duality of order four — that is, a quadrality — reminiscent of infrared dualities of SQCD theories in higher dimensions. In this note, we show that the zero-dimensional quadrality proposal can be inferred from the two-dimensional Gadde-Gukov-Putrov triality. We consider two-dimensional N = (0, 2) SQCD compactified on a sphere with the half-topological twist. For a convenient choice of R-charge, the zero-mode sector on the sphere gives rise to a simple N = 1 gauged matrix model. Triality on the sphere then implies a triality relation for the supersymmetric matrix model, which can be completed to the full quadrality.

Disc-oscillation resonance and neutron star QPOs: 3:2 epicyclic orbital model

NASA Astrophysics Data System (ADS)

Urbanec, M.; Török, G.; Šrámková, E.; Čech, P.; Stuchlík, Z.; Bakala, P.

2010-11-01

The high-frequency quasi-periodic oscillations (HF QPOs) that appear in the X-ray fluxes of low-mass X-ray binaries remain an unexplained phenomenon. Among other ideas, it has been suggested that a non-linear resonance between two oscillation modes in an accretion disc orbiting either a black hole or a neutron star plays a role in exciting the observed modulation. Several possible resonances have been discussed. A particular model assumes resonances in which the disc-oscillation modes have the eigenfrequencies equal to the radial and vertical epicyclic frequencies of geodesic orbital motion. This model has been discussed for black hole microquasar sources as well as for a group of neutron star sources. Assuming several neutron (strange) star equations of state and Hartle-Thorne geometry of rotating stars, we briefly compare the frequencies expected from the model to those observed. Our comparison implies that the inferred neutron star radius RNS is larger than the related radius of the marginally stable circular orbit rms for nuclear matter equations of state and spin frequencies up to 800 Hz. For the same range of spin and a strange star (MIT) equation of state, the inferrred radius is RNS ˜ rms. The “Paczyński modulation” mechanism considered within the model requires that RNS < rms. However, we find this condition to be fulfilled only for the strange matter equation of state, masses below 1 M⊙, and spin frequencies above 800 Hz. This result most likely falsifies the postulation of the neutron star 3:2 resonant eigenfrequencies being equal to the frequencies of geodesic radial and vertical epicyclic modes. We suggest that the 3:2 epicyclic modes could stay among the possible choices only if a fairly non-geodesic accretion flow is assumed, or if a different modulation mechanism operates.

Teaching and Learning Principles of Microeconomics Online: An Empirical Assessment

ERIC Educational Resources Information Center

Gratton-Lavoie, Chiara; Stanley, Denise

2009-01-01

How do students enrolled in online courses perform relative to those who choose a more traditional classroom environment? What student characteristics help explain differences in student academic achievement in the two modes of instruction? What factors affect the students' choice of instruction mode? The authors address these questions in…

Student Career Decisions: The Limits of Rationality.

ERIC Educational Resources Information Center

Baumgardner, Steve R.; Rappoport, Leon

This study compares modes of cognitive functioning revealed in student selection of a college major. Students were interviewed in-depth concerning reasons for their choice of majors. Protocol data suggested two distinct modes of thinking were evident on an analytic-intuitive dimension. For operational purposes analytic thinking was defined by…

Joint Optimization of Distribution Network Design and Two-Echelon Inventory Control with Stochastic Demand and CO2 Emission Tax Charges.

PubMed

Li, Shuangyan; Li, Xialian; Zhang, Dezhi; Zhou, Lingyun

2017-01-01

This study develops an optimization model to integrate facility location and inventory control for a three-level distribution network consisting of a supplier, multiple distribution centers (DCs), and multiple retailers. The integrated model addressed in this study simultaneously determines three types of decisions: (1) facility location (optimal number, location, and size of DCs); (2) allocation (assignment of suppliers to located DCs and retailers to located DCs, and corresponding optimal transport mode choices); and (3) inventory control decisions on order quantities, reorder points, and amount of safety stock at each retailer and opened DC. A mixed-integer programming model is presented, which considers the carbon emission taxes, multiple transport modes, stochastic demand, and replenishment lead time. The goal is to minimize the total cost, which covers the fixed costs of logistics facilities, inventory, transportation, and CO2 emission tax charges. The aforementioned optimal model was solved using commercial software LINGO 11. A numerical example is provided to illustrate the applications of the proposed model. The findings show that carbon emission taxes can significantly affect the supply chain structure, inventory level, and carbon emission reduction levels. The delay rate directly affects the replenishment decision of a retailer.

Energy transport in weakly nonlinear wave systems with narrow frequency band excitation.

PubMed

Kartashova, Elena

2012-10-01

A novel discrete model (D model) is presented describing nonlinear wave interactions in systems with small and moderate nonlinearity under narrow frequency band excitation. It integrates in a single theoretical frame two mechanisms of energy transport between modes, namely, intermittency and energy cascade, and gives the conditions under which each regime will take place. Conditions for the formation of a cascade, cascade direction, conditions for cascade termination, etc., are given and depend strongly on the choice of excitation parameters. The energy spectra of a cascade may be computed, yielding discrete and continuous energy spectra. The model does not require statistical assumptions, as all effects are derived from the interaction of distinct modes. In the example given-surface water waves with dispersion function ω(2)=gk and small nonlinearity-the D model predicts asymmetrical growth of side-bands for Benjamin-Feir instability, while the transition from discrete to continuous energy spectrum, excitation parameters properly chosen, yields the saturated Phillips' power spectrum ~g(2)ω(-5). The D model can be applied to the experimental and theoretical study of numerous wave systems appearing in hydrodynamics, nonlinear optics, electrodynamics, plasma, convection theory, etc.

Prospect balancing theory: Bounded rationality of drivers' speed choice.

PubMed

Schmidt-Daffy, Martin

2014-02-01

This paper introduces a new approach to model the psychological determinants of drivers' speed choice: prospect-balancing theory. The theory transfers psychological insight into the bounded rationality of human decision-making to the field of driving behaviour. Speed choice is conceptualized as a trade-off between two options for action: the option to drive slower and the option to drive faster. Each option is weighted according to a subjective value and a subjectively weighted probability attributed to the achievement of the associated action goal; e.g. to avoid an accident by driving more slowly. The theory proposes that the subjective values and weightings of probability differ systematically from the objective conditions and thereby usually favour a cautious speed choice. A driving simulation study with 24 male participants supports this assumption. In a conflict between a monetary gain in case of fast arrival and a monetary loss in case of a collision with a deer, participants chose a velocity lower than that which would maximize their pay-out. Participants' subjective certainty of arriving in time and of avoiding a deer collision assessed at different driving speeds diverged from the respective objective probabilities in accordance with the observed bias in choice of speed. Results suggest that the bounded rationality of drivers' speed choice might be used to support attempts to improve road safety. Thus, understanding the motivational and perceptual determinants of this intuitive mode of decision-making might be a worthwhile focus of future research. Copyright © 2013 Elsevier Ltd. All rights reserved.

The effect of residential choice on the travel distance and the implications for sustainable development

NASA Astrophysics Data System (ADS)

Eka Putra, Kaspan

2018-03-01

For Medan citizens, the choice of residence location depends on the ability to buy a house. House price is determined by the price of land where the housing is located. The more to the edge of the city the location of a house, then the price will be lower. So that the suburbs of Medan become the residential choice for the citizens of low-income. The residential choice will affect the distance of the journey to the workplace. This study analyzed the effect of residential choice on the travel distance and the implications for the implementation of sustainable development. The data used in this study is the primary data obtained through the survey held in Medan. The research approach is quantitative with the data analysis technique of Structural Equation Model (SEM). The results show that low-income citizens tend to choose the location of suburbs, while they work in the urban area. The location of the residence affects the daily travel distance is very high. The travel distance that is the very high effect the use of private vehicle mode. The use of private vehicles for long travel distance requires a huge energy. The use of very high fuel oils is a waste of energy and can increase air pollution. This is not in accordance with the concept of sustainable development.

What's good and bad about contraceptive products?: a best-worst attribute experiment comparing the values of women consumers and GPs.

PubMed

Knox, Stephanie A; Viney, Rosalie C; Street, Deborah J; Haas, Marion R; Fiebig, Denzil G; Weisberg, Edith; Bateson, Deborah

2012-12-01

In the past decade, the range of contraceptives available has increased dramatically. There are limited data on the factors that determine women's choices on contraceptive alternatives or what factors providers consider most important when recommending contraceptive products to women. Our objectives were to compare women's (consumers') preferences and GPs' (providers') views in relation to existing and new contraceptive methods, and particularly to examine what factors increase the acceptability of different contraceptive products. A best-worst attribute stated-choice experiment was completed online. Participants (Australian women of reproductive age and Australian GPs) completed questions on 16 contraceptive profiles. 200 women of reproductive age were recruited through a commercial panel. GPs from all states of Australia were randomly sampled and approached by phone; 162 GPs agreed to participate. Participants chose the best and worst attribute levels of hypothetical but realistic prescribed contraceptive products. Best and worst choices were modelled using multinomial logit and product features were ranked from best to worst according to the size of model coefficients. The most attractive feature of the contraceptive products for both GPs and women consumers were an administration frequency of longer than 1 year and light or no bleeding. Women indicated that the hormonal vaginal ring was the least attractive mode of administration. Women and GPs agree that longer-acting methods with less bleeding are important features in preferred methods of contraception; however, women are also attracted to products involving less invasive modes of administration. While the vaginal ring may fill the niche in Australia for a relatively non-invasive, moderately long-acting and effective contraceptive, the results of this study indicate that GPs will need to promote the benefits of the vaginal ring to overcome negative perceptions about this method among women who may benefit from using it.

The Changing Importance of Factors Influencing Students' Choice of Study Mode

ERIC Educational Resources Information Center

Bailey, Matthew; Ifenthaler, Dirk; Gosper, Maree; Kretzschmar, Mandy; Ware, Cheryl

2015-01-01

Despite the expansion of online and blended learning, as well as open education, until relatively recently little research has been undertaken on what motivates students to enrol in particular study modes at university level. This project contributes to recent scholarship in the field by exploring the reasons why humanities students choose to…

Constraints on isocurvature models from the WMAP first-year data

DOE Office of Scientific and Technical Information (OSTI.GOV)

Moodley, K.; Astrophysics, University of Oxford, Denys Wilkinson Building, Keble Road, Oxford OX1 3RH; Bucher, M.

2004-11-15

We investigate the constraints imposed by the first-year Wilkinson Microwave Anisotropy Probe (WMAP) cosmic microwave background (CMB) data extended to higher multipoles by data from ACBAR, BOOMERANG, CBI, and the VSA and by the large-scale structure data from the 2dF galaxy redshift survey on the possible amplitude of primordial isocurvature modes. A flat universe with cold dark matter (CDM) and cosmological constant {lambda} is assumed, and the baryon, CDM isocurvature (CI), and neutrino density (NID), and velocity (NIV) isocurvature modes are considered. Constraints on the allowed isocurvature contributions are established from the data for various combinations of the adiabatic modemore » and one, two, and three isocurvature modes, with intermode cross correlations allowed. Since baryon and CDM isocurvature are observationally virtually indistinguishable, these modes are not considered separately. We find that when just a single isocurvature mode is added, the present data allows an isocurvature fraction, in terms of the nonadiabatic contribution to the power in the CMB anisotropy, as large as 13{+-}6, 7{+-}4, and 13{+-}7 percent for adiabatic plus the CI, NID, and NIV modes, respectively. When two isocurvature modes plus the adiabatic mode and cross correlations are allowed, these percentages rise to 47{+-}16, 34{+-}12, and 44{+-}12 for the combinations CI+NID, CI+NIV, and NID+NIV, respectively. Finally, when all three isocurvature modes and cross correlations are allowed, the admissible isocurvature fraction rises to 57{+-}9 percent. In our analysis we consider only scalar modes with a single common tilt parameter for all the modes and do not consider any possible primordial anisotropies in the local neutrino velocity distribution beyond quadrupole order. The sensitivity of the results to the choice of prior probability distribution is examined.« less

Walk, Bicycle, and Transit Trips of Transit-Dependent and Choice Riders in the 2009 United States National Household Travel Survey.

PubMed

Lachapelle, Ugo

2015-08-01

Previous research has shown that public transit use may be associated with active transportation. Access to a car may influence active transportation of transit riders. Using the 2009 United States National Household Travel Survey (NHTS), transit users ≥ 16 years old (n = 25,550) were categorized according to driver status and number of cars and drivers in the household. This typology ranged from choice transit riders (ie, "fully motorized drivers") to transit-dependent riders (ie, "unmotorized nondriver"). Transit trips, walking trips, and bicycling trips of transit users are estimated in negative binomial models against the car availability typology. Sixteen percent of participants took transit in the past month; most (86%) lived in car-owning households. As income increased, car availability also increased. Transit user groups with lower car availability were generally more likely than fully motorized drivers to take more public transit, walking, and bicycle trips. Transit riders have varying levels of vehicle access; their use of combinations of alternative modes of transportation fluctuates accordingly. Transit-dependent individuals without cars or sharing cars used active transportation more frequently than car owners. Policies to reduce vehicle ownership in households may enable increases in the use of alternative modes of transportation for transit users, even when cars are still owned.

Calculation of SF6-/SF6 and Cl-/CFCl3 electron attachment cross sections in the energy range 0-100 meV

NASA Technical Reports Server (NTRS)

Chutjian, A.

1982-01-01

Electron attachment cross sections for the processes SF6-/SF6 and Cl-/CFCl3 are calculated in a local theory using a model in which diatomic-like potential energy curves for the normal modes are constructed from available spectroscopic data. Thermally populated vibrational and rotational levels are included. Good agreement is found with experimental cross sections in the energy range 5-100 meV for a particular choice of potential energy curve parameters.

Scale-free memory model for multiagent reinforcement learning. Mean field approximation and rock-paper-scissors dynamics

NASA Astrophysics Data System (ADS)

Lubashevsky, I.; Kanemoto, S.

2010-07-01

A continuous time model for multiagent systems governed by reinforcement learning with scale-free memory is developed. The agents are assumed to act independently of one another in optimizing their choice of possible actions via trial-and-error search. To gain awareness about the action value the agents accumulate in their memory the rewards obtained from taking a specific action at each moment of time. The contribution of the rewards in the past to the agent current perception of action value is described by an integral operator with a power-law kernel. Finally a fractional differential equation governing the system dynamics is obtained. The agents are considered to interact with one another implicitly via the reward of one agent depending on the choice of the other agents. The pairwise interaction model is adopted to describe this effect. As a specific example of systems with non-transitive interactions, a two agent and three agent systems of the rock-paper-scissors type are analyzed in detail, including the stability analysis and numerical simulation. Scale-free memory is demonstrated to cause complex dynamics of the systems at hand. In particular, it is shown that there can be simultaneously two modes of the system instability undergoing subcritical and supercritical bifurcation, with the latter one exhibiting anomalous oscillations with the amplitude and period growing with time. Besides, the instability onset via this supercritical mode may be regarded as “altruism self-organization”. For the three agent system the instability dynamics is found to be rather irregular and can be composed of alternate fragments of oscillations different in their properties.

Numerical Simulation of Vitiation Effects on a Hydrogen-Fueled Dual-Mode Scramjet

NASA Technical Reports Server (NTRS)

Vyas, Manan A.; Engblom, William A.; Georgiadis, Nicholas J.; Trefny, Charles J.; Bhagwandin, Vishal A.

2010-01-01

The Wind-US computational fluid dynamics (CFD) flow solver was used to simulate dual-mode direct-connect ramjet/scramjet engine flowpath tests conducted in the University of Virginia (UVa) Supersonic Combustion Facility (SCF). The objective was to develop a computational capability within Wind-US to aid current hypersonic research and provide insight to flow as well as chemistry details that are not resolved by instruments available. Computational results are compared with experimental data to validate the accuracy of the numerical modeling. These results include two fuel-off non-reacting and eight fuel-on reacting cases with different equivalence ratios, split between one set with a clean (non-vitiated) air supply and the other set with a vitiated air supply (12 percent H2O vapor). The Peters and Rogg hydrogen-air chemical kinetics model was selected for the scramjet simulations. A limited sensitivity study was done to investigate the choice of turbulence model and inviscid flux scheme and led to the selection of the k-epsilon model and Harten, Lax and van Leer (for contact waves) (HLLC) scheme for general use. Simulation results show reasonably good agreement with experimental data and the overall vitiation effects were captured.

Transport choice when travelling to a sports facility: the role of perceived route features - Results from a cross-sectional study in the Netherlands.

PubMed

de Hollander, Ellen L; Scheepers, Eline; van Wijnen, Harm J; van Wesemael, Pieter Jv; Schuit, Albertine J; Wendel-Vos, Wanda; van Kempen, Elise Emm

2015-01-01

Physical activity and sedentary behaviour are independently associated with health outcomes, where physical activity (PA) is associated with health benefits and sedentary behaviour is associated with health risks. One possible strategy to counteract sedentary behaviour is to stimulate active transport use. As monitoring studies in the Netherlands have shown that among sedentary people the proportion of adults who engage in sports (hereafter: sports practitioners) is 62.3%, sports practitioners seem a feasible target group for this strategy. Previous studies have generally reported associations between neighbourhood characteristics and active transport use. However, the neighbourhood covers only part of the route to a certain destination. Therefore, we examined the association between perceived route features and transport choice when travelling up to 7.5 kilometres to a sports facility among sports practitioners. For 1118 Dutch sports practitioners - who indicated that they practice a sport and travel to a sports facility - age 18 and older, data on transport choice and perceived features of the route to a sports facility were gathered. Participants were classified into one of three transport groups based on their transport choice: car users, cyclists and walkers. Participants were asked whether perceived route features influenced their transport choice. Logistic regression was used to model the odds of cycling versus car use and walking versus car use in the association with perceived route features, adjusted for potential confounders. Perceived traffic safety was associated with lower odds of cycling (OR: 0.36, 95% CI: 0.15-0.86). Perceived route duration was associated with lower odds of both cycling (OR: 0.54, 95%CI: 0.39-0.75) and walking (OR: 0.60, 95%CI: 0.36-1.00). Perceived distance to a sports facility and having to make a detour when using other transport modes than the chosen transport mode were associated with higher odds of both cycling and walking (ORrange: 1.82-5.21). What and who people encountered during their trip (i.e. visual aspects) was associated with higher odds of both cycling and walking (ORrange: 2.40-3.69). Perceived traffic safety, duration, distance, detour, and visual aspects, when travelling to a sports facility were associated with transport choice. Therefore, the perception of route features should be considered when stimulating active transport use among sports practitioners.

Probabilistic estimation of splitting coefficients of normal modes of the Earth, and their uncertainties, using an autoregressive technique

NASA Astrophysics Data System (ADS)

Pachhai, S.; Masters, G.; Laske, G.

2017-12-01

Earth's normal-mode spectra are crucial to studying the long wavelength structure of the Earth. Such observations have been used extensively to estimate "splitting coefficients" which, in turn, can be used to determine the three-dimensional velocity and density structure. Most past studies apply a non-linear iterative inversion to estimate the splitting coefficients which requires that the earthquake source is known. However, it is challenging to know the source details, particularly for big events as used in normal-mode analyses. Additionally, the final solution of the non-linear inversion can depend on the choice of damping parameter and starting model. To circumvent the need to know the source, a two-step linear inversion has been developed and successfully applied to many mantle and core sensitive modes. The first step takes combinations of the data from a single event to produce spectra known as "receiver strips". The autoregressive nature of the receiver strips can then be used to estimate the structure coefficients without the need to know the source. Based on this approach, we recently employed a neighborhood algorithm to measure the splitting coefficients for an isolated inner-core sensitive mode (13S2). This approach explores the parameter space efficiently without any need of regularization and finds the structure coefficients which best fit the observed strips. Here, we implement a Bayesian approach to data collected for earthquakes from early 2000 and more recent. This approach combines the data (through likelihood) and prior information to provide rigorous parameter values and their uncertainties for both isolated and coupled modes. The likelihood function is derived from the inferred errors of the receiver strips which allows us to retrieve proper uncertainties. Finally, we apply model selection criteria that balance the trade-offs between fit (likelihood) and model complexity to investigate the degree and type of structure (elastic and anelastic) required to explain the data.

A data-driven decomposition approach to model aerodynamic forces on flapping airfoils

NASA Astrophysics Data System (ADS)

Raiola, Marco; Discetti, Stefano; Ianiro, Andrea

2017-11-01

In this work, we exploit a data-driven decomposition of experimental data from a flapping airfoil experiment with the aim of isolating the main contributions to the aerodynamic force and obtaining a phenomenological model. Experiments are carried out on a NACA 0012 airfoil in forward flight with both heaving and pitching motion. Velocity measurements of the near field are carried out with Planar PIV while force measurements are performed with a load cell. The phase-averaged velocity fields are transformed into the wing-fixed reference frame, allowing for a description of the field in a domain with fixed boundaries. The decomposition of the flow field is performed by means of the POD applied on the velocity fluctuations and then extended to the phase-averaged force data by means of the Extended POD approach. This choice is justified by the simple consideration that aerodynamic forces determine the largest contributions to the energetic balance in the flow field. Only the first 6 modes have a relevant contribution to the force. A clear relationship can be drawn between the force and the flow field modes. Moreover, the force modes are closely related (yet slightly different) to the contributions of the classic potential models in literature, allowing for their correction. This work has been supported by the Spanish MINECO under Grant TRA2013-41103-P.

Extreme learning machine for reduced order modeling of turbulent geophysical flows.

PubMed

San, Omer; Maulik, Romit

2018-04-01

We investigate the application of artificial neural networks to stabilize proper orthogonal decomposition-based reduced order models for quasistationary geophysical turbulent flows. An extreme learning machine concept is introduced for computing an eddy-viscosity closure dynamically to incorporate the effects of the truncated modes. We consider a four-gyre wind-driven ocean circulation problem as our prototype setting to assess the performance of the proposed data-driven approach. Our framework provides a significant reduction in computational time and effectively retains the dynamics of the full-order model during the forward simulation period beyond the training data set. Furthermore, we show that the method is robust for larger choices of time steps and can be used as an efficient and reliable tool for long time integration of general circulation models.

Extreme learning machine for reduced order modeling of turbulent geophysical flows

NASA Astrophysics Data System (ADS)

San, Omer; Maulik, Romit

2018-04-01

We investigate the application of artificial neural networks to stabilize proper orthogonal decomposition-based reduced order models for quasistationary geophysical turbulent flows. An extreme learning machine concept is introduced for computing an eddy-viscosity closure dynamically to incorporate the effects of the truncated modes. We consider a four-gyre wind-driven ocean circulation problem as our prototype setting to assess the performance of the proposed data-driven approach. Our framework provides a significant reduction in computational time and effectively retains the dynamics of the full-order model during the forward simulation period beyond the training data set. Furthermore, we show that the method is robust for larger choices of time steps and can be used as an efficient and reliable tool for long time integration of general circulation models.

[Demographic pressure, "informal sector" and technological choices in Third World countries].

PubMed

Hugon, P

1983-01-01

Trisectorial models of economic functioning have been proposed to replace the dualistic models that proved incapable of illuminating postwar employment trends in developing countries. The new models propose 3 sectors: the subsistence sector, where average productivity corresponds to the subsistence minimum and which is thus incapable of generating a surplus for savings; the intermediate sector, weakly capitalistic, characterized by the absence of a permanent salaried work force or codified labor relations, in which precariousness of employment and the exploitation of specific social relations allow a low wage rate, with a concommitant mode of regulation that largely escapes state control; and the intensely capitalistic sector, with a salaried work force, codified labor relations, existence of administered prices, various state subventions and protections and a monopolistic type of regulation. The 3 sectors are described in greater detail and represented graphically, along with a critique of the limitations of most studies employing a trisectorial perspective. A study of the impact of demographic pressure at different levels of technology embedded in specific sociohistoric systems follows. The final section contains an analysis of 3 types of effects which may mediate the role of demographic pressure in the choice of technologies: effects of demographic pressure on structures of production and consumption, on segments of the labor force, and on involutive and evolutive processes. It is argued that the links between demographic pressure, technologic choices, and the productive sector can only be analyzed in specific social systems.

An analysis of the number of parking bays and checkout counters for a supermarket using SAS simulation studio

NASA Astrophysics Data System (ADS)

Kar, Leow Soo

2014-07-01

Two important factors that influence customer satisfaction in large supermarkets or hypermarkets are adequate parking facilities and short waiting times at the checkout counters. This paper describes the simulation analysis of a large supermarket to determine the optimal levels of these two factors. SAS Simulation Studio is used to model a large supermarket in a shopping mall with car park facility. In order to make the simulation model more realistic, a number of complexities are introduced into the model. For example, arrival patterns of customers vary with the time of the day (morning, afternoon and evening) and with the day of the week (weekdays or weekends), the transport mode of arriving customers (by car or other means), the mode of payment (cash or credit card), customer shopping pattern (leisurely, normal, exact) or choice of checkout counters (normal or express). In this study, we focus on 2 important components of the simulation model, namely the parking area, the normal and express checkout counters. The parking area is modeled using a Resource Pool block where one resource unit represents one parking bay. A customer arriving by car seizes a unit of the resource from the Pool block (parks car) and only releases it when he exits the system. Cars arriving when the Resource Pool is empty (no more parking bays) leave without entering the system. The normal and express checkouts are represented by Server blocks with appropriate service time distributions. As a case study, a supermarket in a shopping mall with a limited number of parking bays in Bangsar was chosen for this research. Empirical data on arrival patterns, arrival modes, payment modes, shopping patterns, service times of the checkout counters were collected and analyzed to validate the model. Sensitivity analysis was also performed with different simulation scenarios to identify the parameters for the optimal number the parking spaces and checkout counters.

Transverse mode instabilities in burst operation of high-power fiber laser systems

NASA Astrophysics Data System (ADS)

Jauregui, Cesar; Stihler, Christoph; Tünnermann, Andreas; Limpert, Jens

2018-02-01

We propose, to the best of our knowledge, the first mitigation strategy for TMI based on controlling the phase shift between the thermally-induced index grating and the modal intensity pattern. In particular, in this work we present a study of transverse mode instabilities in burst operation in a high-power fiber laser system. It is shown that, with a careful choice of the parameters, this operation regime can potentially lead to the mitigation of TMI by forcing an energy transfer from the higher-order-modes into the fundamental mode during the burst.

Generalized cable equation model for myelinated nerve fiber.

PubMed

Einziger, Pinchas D; Livshitz, Leonid M; Mizrahi, Joseph

2005-10-01

Herein, the well-known cable equation for nonmyelinated axon model is extended analytically for myelinated axon formulation. The myelinated membrane conductivity is represented via the Fourier series expansion. The classical cable equation is thereby modified into a linear second order ordinary differential equation with periodic coefficients, known as Hill's equation. The general internal source response, expressed via repeated convolutions, uniformly converges provided that the entire periodic membrane is passive. The solution can be interpreted as an extended source response in an equivalent nonmyelinated axon (i.e., the response is governed by the classical cable equation). The extended source consists of the original source and a novel activation function, replacing the periodic membrane in the myelinated axon model. Hill's equation is explicitly integrated for the specific choice of piecewise constant membrane conductivity profile, thereby resulting in an explicit closed form expression for the transmembrane potential in terms of trigonometric functions. The Floquet's modes are recognized as the nerve fiber activation modes, which are conventionally associated with the nonlinear Hodgkin-Huxley formulation. They can also be incorporated in our linear model, provided that the periodic membrane point-wise passivity constraint is properly modified. Indeed, the modified condition, enforcing the periodic membrane passivity constraint on the average conductivity only leads, for the first time, to the inclusion of the nerve fiber activation modes in our novel model. The validity of the generalized transmission-line and cable equation models for a myelinated nerve fiber, is verified herein through a rigorous Green's function formulation and numerical simulations for transmembrane potential induced in three-dimensional myelinated cylindrical cell. It is shown that the dominant pole contribution of the exact modal expansion is the transmembrane potential solution of our generalized model.

Joint Optimization of Distribution Network Design and Two-Echelon Inventory Control with Stochastic Demand and CO2 Emission Tax Charges

PubMed Central

Li, Shuangyan; Li, Xialian; Zhang, Dezhi; Zhou, Lingyun

2017-01-01

This study develops an optimization model to integrate facility location and inventory control for a three-level distribution network consisting of a supplier, multiple distribution centers (DCs), and multiple retailers. The integrated model addressed in this study simultaneously determines three types of decisions: (1) facility location (optimal number, location, and size of DCs); (2) allocation (assignment of suppliers to located DCs and retailers to located DCs, and corresponding optimal transport mode choices); and (3) inventory control decisions on order quantities, reorder points, and amount of safety stock at each retailer and opened DC. A mixed-integer programming model is presented, which considers the carbon emission taxes, multiple transport modes, stochastic demand, and replenishment lead time. The goal is to minimize the total cost, which covers the fixed costs of logistics facilities, inventory, transportation, and CO2 emission tax charges. The aforementioned optimal model was solved using commercial software LINGO 11. A numerical example is provided to illustrate the applications of the proposed model. The findings show that carbon emission taxes can significantly affect the supply chain structure, inventory level, and carbon emission reduction levels. The delay rate directly affects the replenishment decision of a retailer. PMID:28103246

The quasi-inertial and wide-deadband modes as backup attitude options for the Skylab mission

NASA Technical Reports Server (NTRS)

Elrod, B. D.

1971-01-01

The quasi-inertial (QI) and wide deadband (WDB) modes were investigated as alternatives to the solar inertial (SI) mode in case two control moment gyros fail during the Skylab mission. Both modes provide a substantial reduction in propellant requirements from the solar interial hold requirement with either the orbital assembly/thruster attitude control system or service module reaction control system. Spacecraft motion in the QI mode is produced by a command rate and results in a small amplitude oscillation (17 deg, maximum) about the SI orientation. In the WDB mode a somewhat similar, but larger amplitude motion (35 deg maximum) about the SI orientation is developed by appropriate choice of controller deadbands and switch line slopes.

Transfer of learning in choice reactions: The roles of stimulus type, response mode, and set-level compatibility.

PubMed

Yamaguchi, Motonori; Chen, Jing; Proctor, Robert W

2015-08-01

The Simon effect refers to the advantage of responding to spatially compatible stimuli. This effect can be eliminated or even reversed to favor spatially incompatible stimuli after participants practice a choice-reaction task with spatially incompatible mappings (e.g., pressing left and right keys to stimuli on the right and left, respectively). This transfer of incompatible spatial associations has been observed under conditions in which responses were made manually (e.g., keypresses, moving a joystick). The present study used vocal responses to reveal the primary determinants of the transfer effect, dissociating the influences of stimulus type, response mode, and their interaction (set-level compatibility). The results suggest that contextual match between the practice and transfer tasks with respect to stimulus type and response mode determined transfer of incompatible associations to the Simon task, and stimulus type determined the efficiency of acquiring new associations. However, there was little evidence that set-level compatibility plays any major role in either acquisition or transfer of spatial associations.

Self-force via m-mode regularization and 2+1D evolution: Foundations and a scalar-field implementation on Schwarzschild spacetime

DOE Office of Scientific and Technical Information (OSTI.GOV)

Dolan, Sam R.; Barack, Leor

2011-01-15

To model the radiative evolution of extreme mass-ratio binary inspirals (a key target of the LISA mission), the community needs efficient methods for computation of the gravitational self-force (SF) on the Kerr spacetime. Here we further develop a practical 'm-mode regularization' scheme for SF calculations, and give the details of a first implementation. The key steps in the method are (i) removal of a singular part of the perturbation field with a suitable 'puncture' to leave a sufficiently regular residual within a finite worldtube surrounding the particle's worldline, (ii) decomposition in azimuthal (m) modes, (iii) numerical evolution of the mmore » modes in 2+1D with a finite-difference scheme, and (iv) reconstruction of the SF from the mode sum. The method relies on a judicious choice of puncture, based on the Detweiler-Whiting decomposition. We give a working definition for the ''order'' of the puncture, and show how it determines the convergence rate of the m-mode sum. The dissipative piece of the SF displays an exponentially convergent mode sum, while the m-mode sum for the conservative piece converges with a power law. In the latter case, the individual modal contributions fall off at large m as m{sup -n} for even n and as m{sup -n+1} for odd n, where n is the puncture order. We describe an m-mode implementation with a 4th-order puncture to compute the scalar-field SF along circular geodesics on Schwarzschild. In a forthcoming companion paper we extend the calculation to the Kerr spacetime.« less

A Test of Web and Mail Mode Effects in a Financially Sensitive Survey of Older Americans

PubMed Central

Hsu, Joanne W.

2018-01-01

This study leverages a randomized experimental design of a mixed-mode mail- and web-based survey to examine mode effects separately from sample selectivity issues. Using data from the Cognitive Economics Study, which contains some sensitive financial questions, we analyze two sets of questions: fixed-choice questions posed nearly identically across mode, and dollar-value questions that exploit features available only on web mode. Focusing on differences in item nonresponse and response distributions, our results indicate that, in contrast to mail mode, web mode surveys display lower item nonresponse for all questions. While respondents appear to prefer providing financial information in ranges, use of reminder screens on the web version yields greater use of exact values without large sacrifices in item response. Still, response distributions for all questions are similar across mode, suggesting that data on sensitive financial questions collected from the two modes can be pooled.

Mathematical modeling of non-stationary gas flow in gas pipeline

NASA Astrophysics Data System (ADS)

Fetisov, V. G.; Nikolaev, A. K.; Lykov, Y. V.; Duchnevich, L. N.

2018-03-01

An analysis of the operation of the gas transportation system shows that for a considerable part of time pipelines operate in an unsettled regime of gas movement. Its pressure and flow rate vary along the length of pipeline and over time as a result of uneven consumption and selection, switching on and off compressor units, shutting off stop valves, emergence of emergency leaks. The operational management of such regimes is associated with difficulty of reconciling the operating modes of individual sections of gas pipeline with each other, as well as with compressor stations. Determining the grounds that cause change in the operating mode of the pipeline system and revealing patterns of these changes determine the choice of its parameters. Therefore, knowledge of the laws of changing the main technological parameters of gas pumping through pipelines in conditions of non-stationary motion is of great importance for practice.

Action and Valence Modulate Choice and Choice-Induced Preference Change

PubMed Central

Koster, Raphael; Duzel, Emrah; Dolan, Raymond J.

2015-01-01

Choices are not only communicated via explicit actions but also passively through inaction. In this study we investigated how active or passive choice impacts upon the choice process itself as well as a preference change induced by choice. Subjects were tasked to select a preference for unfamiliar photographs by action or inaction, before and after they gave valuation ratings for all photographs. We replicate a finding that valuation increases for chosen items and decreases for unchosen items compared to a control condition in which the choice was made post re-evaluation. Whether choice was expressed actively or passively affected the dynamics of revaluation differently for positive and negatively valenced items. Additionally, the choice itself was biased towards action such that subjects tended to choose a photograph obtained by action more often than a photographed obtained through inaction. These results highlight intrinsic biases consistent with a tight coupling of action and reward and add to an emerging understanding of how the mode of action itself, and not just an associated outcome, modulates the decision making process. PMID:25747703

Coherent optical OFDM: theory and design.

PubMed

Shieh, W; Bao, H; Tang, Y

2008-01-21

Coherent optical OFDM (CO-OFDM) has recently been proposed and the proof-of-concept transmission experiments have shown its extreme robustness against chromatic dispersion and polarization mode dispersion. In this paper, we first review the theoretical fundamentals for CO-OFDM and its channel model in a 2x2 MIMO-OFDM representation. We then present various design choices for CO-OFDM systems and perform the nonlinearity analysis for RF-to-optical up-converter. We also show the receiver-based digital signal processing to mitigate self-phase-modulation (SPM) and Gordon-Mollenauer phase noise, which is equivalent to the midspan phase conjugation.

Muscarinic receptor regulates extracellular signal regulated kinase by two modes of arrestin binding.

PubMed

Jung, Seung-Ryoung; Kushmerick, Christopher; Seo, Jong Bae; Koh, Duk-Su; Hille, Bertil

2017-07-11

Binding of agonists to G-protein-coupled receptors (GPCRs) activates heterotrimeric G proteins and downstream signaling. Agonist-bound GPCRs are then phosphorylated by protein kinases and bound by arrestin to trigger desensitization and endocytosis. Arrestin plays another important signaling function. It recruits and regulates activity of an extracellular signal-regulated kinase (ERK) cascade. However, molecular details and timing of ERK activation remain fundamental unanswered questions that limit understanding of how arrestin-dependent GPCR signaling controls cell functions. Here we validate and model a system that tracks the dynamics of interactions of arrestin with receptors and of ERK activation using optical reporters. Our intermolecular FRET measurements in living cells are consistent with β-arrestin binding to M 1 muscarinic acetylcholine receptors (M 1 Rs) in two different binding modes, transient and stable. The stable mode persists for minutes after agonist removal. The choice of mode is governed by phosphorylation on key residues in the third intracellular loop of the receptor. We detect a similar intramolecular conformational change in arrestin in either binding mode. It develops within seconds of arrestin binding to the M 1 receptor, and it reverses within seconds of arrestin unbinding from the transient binding mode. Furthermore, we observed that, when stably bound to phosphorylated M 1 R, β-arrestin scaffolds and activates MEK-dependent ERK. In contrast, when transiently bound, β-arrestin reduces ERK activity via recruitment of a protein phosphatase. All this ERK signaling develops at the plasma membrane. In this scaffolding hypothesis, a shifting balance between the two arrestin binding modes determines the degree of ERK activation at the membrane.

Muscarinic receptor regulates extracellular signal regulated kinase by two modes of arrestin binding

PubMed Central

Jung, Seung-Ryoung; Kushmerick, Christopher; Seo, Jong Bae; Koh, Duk-Su

2017-01-01

Binding of agonists to G-protein–coupled receptors (GPCRs) activates heterotrimeric G proteins and downstream signaling. Agonist-bound GPCRs are then phosphorylated by protein kinases and bound by arrestin to trigger desensitization and endocytosis. Arrestin plays another important signaling function. It recruits and regulates activity of an extracellular signal-regulated kinase (ERK) cascade. However, molecular details and timing of ERK activation remain fundamental unanswered questions that limit understanding of how arrestin-dependent GPCR signaling controls cell functions. Here we validate and model a system that tracks the dynamics of interactions of arrestin with receptors and of ERK activation using optical reporters. Our intermolecular FRET measurements in living cells are consistent with β-arrestin binding to M1 muscarinic acetylcholine receptors (M1Rs) in two different binding modes, transient and stable. The stable mode persists for minutes after agonist removal. The choice of mode is governed by phosphorylation on key residues in the third intracellular loop of the receptor. We detect a similar intramolecular conformational change in arrestin in either binding mode. It develops within seconds of arrestin binding to the M1 receptor, and it reverses within seconds of arrestin unbinding from the transient binding mode. Furthermore, we observed that, when stably bound to phosphorylated M1R, β-arrestin scaffolds and activates MEK-dependent ERK. In contrast, when transiently bound, β-arrestin reduces ERK activity via recruitment of a protein phosphatase. All this ERK signaling develops at the plasma membrane. In this scaffolding hypothesis, a shifting balance between the two arrestin binding modes determines the degree of ERK activation at the membrane. PMID:28652372

Failure mode prediction for composite structural insulated panels with MgO board facings

NASA Astrophysics Data System (ADS)

Smakosz, Łukasz; Kreja, Ireneusz

2018-01-01

Sandwich panels are readily used in civil engineering due to their high strength to weight ratio and the ease and speed of assembly. The idea of a sandwich section is to combine thin and durable facings with a light-weight core and the choice of materials used allows obtaining the desired behaviour. Panels in consideration consist of MgO (magnesium oxide) board facings and expanded polystyrene core and are characterized by immunity to biological corrosion, a high thermal insulation and a relatively low impact on environment. Customizing the range of panels to meet market needs requires frequent size changes, leading to different failure modes, which are identified in a series of costly full-scale laboratory tests. A nonlinear numerical model was created with a use of a commercial ABAQUS code and a user-defined procedure, which is able to reproduce observed failure mechanisms; its parameters were established on the basis of small-scale tests and numerical experiments. The model was validated by a comparison with the results of the full-scale bending and compression tests. The results obtained were in satisfactory agreement with the test data.

Convective Propagation Characteristics Using a Simple Representation of Convective Organization

NASA Astrophysics Data System (ADS)

Neale, R. B.; Mapes, B. E.

2016-12-01

Observed equatorial wave propagation is intimately linked to convective organization and it's coupling to features of the larger-scale flow. In this talk we a use simple 4 level model to accommodate vertical modes of a mass flux convection scheme (shallow, mid-level and deep). Two paradigms of convection are used to represent convective processes. One that has only both random (unorganized) diagnosed fluctuations of convective properties and one with organized fluctuations of convective properties that are amplified by previously existing convection and has an explicit moistening impact on the local convecting environment We show a series of model simulations in single-column, 2D and 3D configurations, where the role of convective organization in wave propagation is shown to be fundamental. For the optimal choice of parameters linking organization to local atmospheric state, a broad array of convective wave propagation emerges. Interestingly the key characteristics of propagating modes are the low-level moistening followed by deep convection followed by mature 'large-scale' heating. This organization structure appears to hold firm across timescales from 5-day wave disturbances to MJO-like wave propagation.

How Bias Reduction Is Affected by Covariate Choice, Unreliability, and Mode of Data Analysis: Results from Two Types of within-Study Comparisons

ERIC Educational Resources Information Center

Cook, Thomas D.; Steiner, Peter M.; Pohl, Steffi

2009-01-01

This study uses within-study comparisons to assess the relative importance of covariate choice, unreliability in the measurement of these covariates, and whether regression or various forms of propensity score analysis are used to analyze the outcome data. Two of the within-study comparisons are of the four-arm type, and many more are of the…

Money Earlier or Later? Simple Heuristics Explain Intertemporal Choices Better than Delay Discounting1

PubMed Central

Marzilli Ericson, Keith M.; White, John Myles; Laibson, David; Cohen, Jonathan D.

2015-01-01

Heuristic models have been proposed for many domains of choice. We compare heuristic models of intertemporal choice, which can account for many of the known intertemporal choice anomalies, to discounting models. We conduct an out-of-sample, cross-validated comparison of intertemporal choice models. Heuristic models outperform traditional utility discounting models, including models of exponential and hyperbolic discounting. The best performing models predict choices by using a weighted average of absolute differences and relative (percentage) differences of the attributes of the goods in a choice set. We conclude that heuristic models explain time-money tradeoff choices in experiments better than utility discounting models. PMID:25911124

[Modeling the academic performance of medical students in basic sciences and pre-clinical courses: a longitudinal study].

PubMed

Zúñiga, Denisse; Mena, Beltrán; Oliva, Rose; Pedrals, Nuria; Padilla, Oslando; Bitran, Marcela

2009-10-01

The study of predictors of academic performance is relevant for medical education. Most studies of academic performance use global ratings as outcome measure, and do not evaluate the influence of the assessment methods. To model by multivariate analysis, the academic performance of medical considering, besides academic and demographic variables, the methods used to assess students' learning and their preferred modes of information processing. Two hundred seventy two students admitted to the medical school of the Pontificia Universidad Católica de Chile from 2000 to 2003. Six groups of variables were studied to model the students' performance in five basic science courses (Anatomy, Biology, Calculus, Chemistry and Physics) and two pre-clinical courses (Integrated Medical Clinic I and IT). The assessment methods examined were multiple choice question tests, Objective Structured Clinical Examination and tutor appraisal. The results of the university admission tests (high school grades, mathematics and biology tests), the assessment methods used, the curricular year and previous application to medical school, were predictors of academic performance. The information processing modes influenced academic performance, but only in interaction with other variables. Perception (abstract or concrete) interacted with the assessment methods, and information use (active or reflexive), with sex. The correlation between the real and predicted grades was 0.7. In addition to the academic results obtained prior to university entrance, the methods of assessment used in the university and the information processing modes influence the academic performance of medical students in basic and preclinical courses.

Compressed modes for variational problems in mathematics and physics.

PubMed

Ozolins, Vidvuds; Lai, Rongjie; Caflisch, Russel; Osher, Stanley

2013-11-12

This article describes a general formalism for obtaining spatially localized ("sparse") solutions to a class of problems in mathematical physics, which can be recast as variational optimization problems, such as the important case of Schrödinger's equation in quantum mechanics. Sparsity is achieved by adding an regularization term to the variational principle, which is shown to yield solutions with compact support ("compressed modes"). Linear combinations of these modes approximate the eigenvalue spectrum and eigenfunctions in a systematically improvable manner, and the localization properties of compressed modes make them an attractive choice for use with efficient numerical algorithms that scale linearly with the problem size.

Optical proposals for controlled delayed-choice experiment based on weak cross-Kerr nonlinearities

NASA Astrophysics Data System (ADS)

Dong, Li; Lin, Yan-Fang; Li, Qing-Yang; Xiu, Xiao-Ming; Dong, Hai-Kuan; Gao, Ya-Jun

2017-05-01

Employing polarization modes of a photon, we propose two theoretical proposals to exhibit the wave-particle duality of the photon with the assistance of weak cross-Kerr nonlinearities. The first proposal is a classical controlled delayed-choice experiment (that is, Wheeler's delayed-choice experiment), where we can observe selectively wave property or particle property of the photon relying on the experimenter's selection, whereas the second proposal is a quantum controlled delayed-choice experiment, by which the mixture phenomenon of a wave and a particle will be exhibited. Both of them can be realized with near-unity probability and embody the charming characteristics of quantum mechanics. The employment of the mature techniques and simple operations (e.g., Homodyne measurement, classical feed forward, and single-photon transformations) provides the feasibility of the delayed-choice experiment proposals presented here.

Proactive patient rounding to increase customer service and satisfaction on an orthopaedic unit.

PubMed

Tea, Christine; Ellison, Michael; Feghali, Fadia

2008-01-01

Customer service and patient satisfaction have become increasingly important in the healthcare industry. Given limited resources and a myriad of choices, on which facets of patient satisfaction should healthcare providers focus? An analysis of 40,000 observations across 4 hospitals found 1 important intervention: timely staff responsiveness. Using the Plan-Do-Check-Act (PDCA) quality methodology, the goal was set to improve staff responsiveness to orthopaedic patient needs and requests, thus improving patient satisfaction. A model to improve staff responsiveness was systematically developed and implemented. The I Care Rounding model places the emphasis on proactively meeting patient needs through hourly rounding, rather than caregivers providing care in a reactionary mode. After full implementation, positive improvement was demonstrated.

Method for Prediction of the Power Output from Photovoltaic Power Plant under Actual Operating Conditions

NASA Astrophysics Data System (ADS)

Obukhov, S. G.; Plotnikov, I. A.; Surzhikova, O. A.; Savkin, K. D.

2017-04-01

Solar photovoltaic technology is one of the most rapidly growing renewable sources of electricity that has practical application in various fields of human activity due to its high availability, huge potential and environmental compatibility. The original simulation model of the photovoltaic power plant has been developed to simulate and investigate the plant operating modes under actual operating conditions. The proposed model considers the impact of the external climatic factors on the solar panel energy characteristics that improves accuracy in the power output prediction. The data obtained through the photovoltaic power plant operation simulation enable a well-reasoned choice of the required capacity for storage devices and determination of the rational algorithms to control the energy complex.

A computational analysis of the binding mode of closantel as inhibitor of the Onchocerca volvulus chitinase: insights on macrofilaricidal drug design

NASA Astrophysics Data System (ADS)

Segura-Cabrera, Aldo; Bocanegra-García, Virgilio; Lizarazo-Ortega, Cristian; Guo, Xianwu; Correa-Basurto, José; Rodríguez-Pérez, Mario A.

2011-12-01

Onchocerciasis is a leading cause of blindness with at least 37 million people infected and more than 120 million people at risk of contracting the disease; most (99%) of this population, threatened by infection, live in Africa. The drug of choice for mass treatment is the microfilaricidal Mectizan® (ivermectin); it does not kill the adult stages of the parasite at the standard dose which is a single annual dose aimed at disease control. However, multiple treatments a year with ivermectin have effects on adult worms. The discovery of new therapeutic targets and drugs directed towards the killing of the adult parasites are thus urgently needed. The chitinase of filarial nematodes is a new drug target due to its essential function in the metabolism and molting of the parasite. Closantel is a potent and specific inhibitor of chitinase of Onchocerca volvulus (OvCHT1) and other filarial chitinases. However, the binding mode and specificity of closantel towards OvCHT1 remain unknown. In the absence of a crystallographic structure of OvCHT1, we developed a homology model of OvCHT1 using the currently available X-ray structures of human chitinases as templates. Energy minimization and molecular dynamics (MD) simulation of the model led to a high quality of 3D structure of OvCHIT1. A flexible docking study using closantel as the ligand on the binding site of OvCHIT1 and human chitinases was performed and demonstrated the differences in the closantel binding mode between OvCHIT1 and human chitinase. Furthermore, molecular dynamics simulations and free-energy calculation were employed to determine and compare the detailed binding mode of closantel with OvCHT1 and the structure of human chitinase. This comparative study allowed identification of structural features and properties responsible for differences in the computationally predicted closantel binding modes. The homology model and the closantel binding mode reported herein might help guide the rational development of novel drugs against the adult parasite of O. volvulus and such findings could be extrapolated to other filarial neglected diseases.

Earth's Outer Core Properties Estimated Using Bayesian Inversion of Normal Mode Eigenfrequencies

NASA Astrophysics Data System (ADS)

Irving, J. C. E.; Cottaar, S.; Lekic, V.

2016-12-01

The outer core is arguably Earth's most dynamic region, and consists of an iron-nickel liquid with an unknown combination of lighter alloying elements. Frequencies of Earth's normal modes provide the strongest constraints on the radial profiles of compressional wavespeed, VΦ, and density, ρ, in the outer core. Recent great earthquakes have yielded new normal mode measurements; however, mineral physics experiments and calculations are often compared to the Preliminary reference Earth model (PREM), which is 35 years old and does not provide uncertainties. Here we investigate the thermo-elastic properties of the outer core using Earth's free oscillations and a Bayesian framework. To estimate radial structure of the outer core and its uncertainties, we choose to exploit recent datasets of normal mode centre frequencies. Under the self-coupling approximation, centre frequencies are unaffected by lateral heterogeneities in the Earth, for example in the mantle. Normal modes are sensitive to both VΦ and ρ in the outer core, with each mode's specific sensitivity depending on its eigenfunctions. We include a priori bounds on outer core models that ensure compatibility with measurements of mass and moment of inertia. We use Bayesian Monte Carlo Markov Chain techniques to explore different choices in parameterizing the outer core, each of which represents different a priori constraints. We test how results vary (1) assuming a smooth polynomial parametrization, (2) allowing for structure close to the outer core's boundaries, (3) assuming an Equation-of-State and adiabaticity and inverting directly for thermo-elastic parameters. In the second approach we recognize that the outer core may have distinct regions close to the core-mantle and inner core boundaries and investigate models which parameterize the well mixed outer core separately from these two layers. In the last approach we seek to map the uncertainties directly into thermo-elastic parameters including the bulk modulus, its pressure derivative, and molar mass and volume, with particular attention paid to the (inherent) trade-offs between the different coefficients. We discuss our results in terms of added uncertainty to the light element composition of the outer core and the potential existence of anomalous structure near the outer core's boundaries.

Trends in Extreme Rainfall Frequency in the Contiguous United States: Attribution to Climate Change and Climate Variability Modes

NASA Astrophysics Data System (ADS)

Armal, S.; Devineni, N.; Khanbilvardi, R.

2017-12-01

This study presents a systematic analysis for identifying and attributing trends in the annual frequency of extreme rainfall events across the contiguous United States to climate change and climate variability modes. A Bayesian multilevel model is developed for 1,244 stations simultaneously to test the null hypothesis of no trend and verify two alternate hypotheses: Trend can be attributed to changes in global surface temperature anomalies, or to a combination of cyclical climate modes with varying quasi-periodicities and global surface temperature anomalies. The Bayesian multilevel model provides the opportunity to pool information across stations and reduce the parameter estimation uncertainty, hence identifying the trends better. The choice of the best alternate hypotheses is made based on Watanabe-Akaike Information Criterion, a Bayesian pointwise predictive accuracy measure. Statistically significant time trends are observed in 742 of the 1,244 stations. Trends in 409 of these stations can be attributed to changes in global surface temperature anomalies. These stations are predominantly found in the Southeast and Northeast climate regions. The trends in 274 of these stations can be attributed to the El Nino Southern Oscillations, North Atlantic Oscillation, Pacific Decadal Oscillation and Atlantic Multi-Decadal Oscillation along with changes in global surface temperature anomalies. These stations are mainly found in the Northwest, West and Southwest climate regions.

Modelling and characterisation of a ultrasound-actuated needle for improved visibility in ultrasound-guided regional anaesthesia and tissue biopsy.

PubMed

Kuang, Y; Hilgers, A; Sadiq, M; Cochran, S; Corner, G; Huang, Z

2016-07-01

Clear needle visualisation is recognised as an unmet need for ultrasound guided percutaneous needle procedures including regional anaesthesia and tissue biopsy. With inadequate needle visibility, these procedures may result in serious complications or a failed operation. This paper reports analysis of the modal behaviour of a previously proposed ultrasound-actuated needle configuration, which may overcome this problem by improving needle visibility in colour Doppler imaging. It uses a piezoelectric transducer to actuate longitudinal resonant modes in needles (outer diameter 0.8-1.2mm, length>65mm). The factors that affect the needle's vibration mode are identified, including the needle length, the transducer's resonance frequency and the gripping position. Their effects are investigated using finite element modelling, with the conclusions validated experimentally. The actuated needle was inserted into porcine tissue up to 30mm depth and its visibility was observed under colour Doppler imaging. The piezoelectric transducer is able to generate longitudinal vibration with peak-to-peak amplitude up to 4μm at the needle tip with an actuating voltage of 20Vpp. Actuated in longitudinal vibration modes (distal mode at 27.6kHz and transducer mode at 42.2kHz) with a drive amplitude of 12-14Vpp, a 120mm needle is delineated as a coloured line in colour Doppler images, with both needle tip and shaft visualised. The improved needle visibility is maintained while the needle is advanced into the tissue, thus allowing tracking of the needle position in real time. Moreover, the needle tip is highlighted by strong coloured artefacts around the actuated needle generated by its flexural vibration. A limitation of the technique is that the transducer mode requires needles of specific lengths so that the needle's resonance frequency matches the transducer. This may restrict the choice of needle lengths in clinical applications. Copyright © 2016 The Authors. Published by Elsevier B.V. All rights reserved.

Factors influencing mode of transport in older adolescents: a qualitative study

PubMed Central

2013-01-01

Background Since a decline in activity levels occurs in adolescence, active transport could be important to increase daily physical activity in older adolescents (17–18 years). To promote active transport, it is necessary to be aware of the barriers and facilitators of this type of transport, but also of other transport modes. This study sought to uncover the factors influencing the choice of transport mode for short distance travel to various destinations in older adolescents using focus groups. Methods Thirty-two focus group volunteers (mean age of 17 ± 1.2 years) were recruited from the two final years of the secondary school in Antwerp (Belgium). Five focus groups were conducted (five to eight participants/group). Content analysis was performed using NVivo 9 software (QSR International). Grounded theory was used to derive categories and subcategories. Results Data were categorized in three main themes with several subcategories: personal factors (high autonomy, low costs and health), social factors (good social support) and physical environmental factors (short travel time, good access to transport modes and to facilities, good weather, an adapted built environment, perceived safety and ecology). Conclusions For older adolescents, the interplay between short travel time, high autonomy, good social support, low costs, good access to transport modes and facilities, and good weather was important for choosing active transport over other transport forms for travelling short distances to various destinations. Other well-known factors such as safety, ecology and health seemed not to have a big influence on their transport mode choice. PMID:23574974

A selective and sensitive method for quantitation of lysergic acid diethylamide (LSD) in whole blood by gas chromatography-ion trap tandem mass spectrometry.

PubMed

Libong, Danielle; Bouchonnet, Stéphane; Ricordel, Ivan

2003-01-01

A gas chromatography-ion trap tandem mass spectrometry (GC-ion trap MS-MS) method for detection and quantitation of LSD in whole blood is presented. The sample preparation process, including a solid-phase extraction step with Bond Elut cartridges, was performed with 2 mL of whole blood. Eight microliters of the purified extract was injected with a cold on-column injection method. Positive chemical ionization was performed using acetonitrile as reagent gas; LSD was detected in the MS-MS mode. The chromatograms obtained from blood extracts showed the great selectivity of the method. GC-MS quantitation was performed using lysergic acid methylpropylamide as the internal standard. The response of the MS was linear for concentrations ranging from 0.02 ng/mL (detection threshold) to 10.0 ng/mL. Several parameters such as the choice of the capillary column, the choice of the internal standard and that of the ionization mode (positive CI vs. EI) were rationalized. Decomposition pathways under both ionization modes were studied. Within-day and between-day stability were evaluated.

Money earlier or later? Simple heuristics explain intertemporal choices better than delay discounting does.

PubMed

Ericson, Keith M Marzilli; White, John Myles; Laibson, David; Cohen, Jonathan D

2015-06-01

Heuristic models have been proposed for many domains involving choice. We conducted an out-of-sample, cross-validated comparison of heuristic models of intertemporal choice (which can account for many of the known intertemporal choice anomalies) and discounting models. Heuristic models outperformed traditional utility-discounting models, including models of exponential and hyperbolic discounting. The best-performing models predicted choices by using a weighted average of absolute differences and relative percentage differences of the attributes of the goods in a choice set. We concluded that heuristic models explain time-money trade-off choices in experiments better than do utility-discounting models. © The Author(s) 2015.

Analysis of edge stability for models of heat flux width

DOE PAGES

Makowski, Michael A.; Lasnier, Charles J.; Leonard, Anthony W.; ...

2017-05-12

Detailed measurements of the n e, and T e, and T i profiles in the vicinity of the separatrix of ELMing H-mode discharges have been used to examine plasma stability at the extreme edge of the plasma and assess stability dependent models of the heat flux width. The results are strongly contrary to the critical gradient model, which posits that a ballooning instability determines a gradient scale length related to the heat flux width. The results of this analysis are not sensitive to the choice of location to evaluate stability. Significantly, it is also found that the results are completelymore » consistent with the heuristic drift model for the heat flux width. Here the edge pressure gradient scales with plasma density and is proportional to the pressure gradient inferred from the equilibrium in accordance with the predictions of that theory.« less

Determinants of ambulatory treatment mode for mental illness.

PubMed

Freiman, M P; Zuvekas, S H

2000-07-01

We estimate a reduced-form bivariate probit model to analyse jointly the choice of ambulatory treatment from the specialty mental health sector and/or the use of psychotropic drugs for a nationally representative sample of US household residents. We find significant differences in treatment choice by education, gender, race and ethnicity, while controlling for several aspects of self-reported mental health and treatment attitudes. For example, while women are more likely than men to use the specialty mental health sector and more likely to take psychotropic medications, this difference between men and women is much greater for psychotropic medications. The estimated differences may reflect patient preferences in a manner traditionally assumed when interpreting these coefficients in such equations, but we discuss how they may also reflect biases and misperceptions on the parts of patients and providers. We also discuss how our results relate to some findings and policies in the general health care sector. Copyright 2000 John Wiley & Sons, Ltd.

Sequential inference as a mode of cognition and its correlates in fronto-parietal and hippocampal brain regions

PubMed Central

Friston, Karl J.; Dolan, Raymond J.

2017-01-01

Normative models of human cognition often appeal to Bayesian filtering, which provides optimal online estimates of unknown or hidden states of the world, based on previous observations. However, in many cases it is necessary to optimise beliefs about sequences of states rather than just the current state. Importantly, Bayesian filtering and sequential inference strategies make different predictions about beliefs and subsequent choices, rendering them behaviourally dissociable. Taking data from a probabilistic reversal task we show that subjects’ choices provide strong evidence that they are representing short sequences of states. Between-subject measures of this implicit sequential inference strategy had a neurobiological underpinning and correlated with grey matter density in prefrontal and parietal cortex, as well as the hippocampus. Our findings provide, to our knowledge, the first evidence for sequential inference in human cognition, and by exploiting between-subject variation in this measure we provide pointers to its neuronal substrates. PMID:28486504

Geovisualisation of relief in a virtual reality system on the basis of low-level aerial imagery

NASA Astrophysics Data System (ADS)

Halik, Łukasz; Smaczyński, Maciej

2017-12-01

The aim of the following paper was to present the geomatic process of transforming low-level aerial imagery obtained with unmanned aerial vehicles (UAV) into a digital terrain model (DTM) and implementing the model into a virtual reality system (VR). The object of the study was a natural aggretage heap of an irregular shape and denivelations up to 11 m. Based on the obtained photos, three point clouds (varying in the level of detail) were generated for the 20,000-m2-area. For further analyses, the researchers selected the point cloud with the best ratio of accuracy to output file size. This choice was made based on seven control points of the heap surveyed in the field and the corresponding points in the generated 3D model. The obtained several-centimetre differences between the control points in the field and the ones from the model might testify to the usefulness of the described algorithm for creating large-scale DTMs for engineering purposes. Finally, the chosen model was implemented into the VR system, which enables the most lifelike exploration of 3D terrain plasticity in real time, thanks to the first person view mode (FPV). In this mode, the user observes an object with the aid of a Head- mounted display (HMD), experiencing the geovisualisation from the inside, and virtually analysing the terrain as a direct animator of the observations.

NO PSEUDOSYNCHRONOUS ROTATION FOR TERRESTRIAL PLANETS AND MOONS

DOE Office of Scientific and Technical Information (OSTI.GOV)

Makarov, Valeri V.; Efroimsky, Michael, E-mail: vvm@usno.navy.mil, E-mail: michael.efroimsky@usno.navy.mil

2013-02-10

We re-examine the popular belief that a telluric planet or a satellite on an eccentric orbit can, outside a spin-orbit resonance, be captured in a quasi-static tidal equilibrium called pseudosynchronous rotation. The existence of such configurations was deduced from oversimplified tidal models assuming either a constant tidal torque or a torque linear in the tidal frequency. A more accurate treatment requires that the torque be decomposed into the Darwin-Kaula series over the tidal modes, and that this decomposition be combined with a realistic choice of rheological properties of the mantle, which we choose to be a combination of the Andrademore » model at ordinary frequencies and the Maxwell model at low frequencies. This development demonstrates that there exist no stable equilibrium states for solid planets and moons, other than spin-orbit resonances.« less

Recent experiences with implementing a video based six degree of freedom measurement system for airplane models in a 20 foot diameter vertical spin tunnel

NASA Technical Reports Server (NTRS)

Snow, Walter L.; Childers, Brooks A.; Jones, Stephen B.; Fremaux, Charles M.

1993-01-01

A model space positioning system (MSPS), a state-of-the-art, real-time tracking system to provide the test engineer with on line model pitch and spin rate information, is described. It is noted that the six-degree-of-freedom post processor program will require additional programming effort both in the automated tracking mode for high spin rates and in accuracy to meet the measurement objectives. An independent multicamera system intended to augment the MSPS is studied using laboratory calibration methods based on photogrammetry to characterize the losses in various recording options. Data acquired to Super VHS tape encoded with Vertical Interval Time Code and transcribed to video disk are considered to be a reasonable priced choice for post editing and processing video data.

Probing quantum entanglement in the Schwarzschild space-time beyond the single-mode approximation

NASA Astrophysics Data System (ADS)

He, Juan; Ding, Zhi-Yong; Ye, Liu

2018-05-01

In this paper, we deduce the vacuum structure for Dirac fields in the background of Schwarzschild space-time beyond the single-mode approximation and discuss the performance of quantum entanglement between particle and antiparticle modes of a Dirac field with Hawking effect. It is shown that Hawking radiation does not always destroy the physically accessible entanglement, and entanglement amplification may happen in some cases. This striking result is different from that of the single-mode approximation, which holds that the Hawking radiation can only destroy entanglement. Lastly, we analyze the physically accessible entanglement relation outside the event horizon and demonstrate that the monogamy inequality is constantly established regardless of the choice of given parameters.

Sociodemographic Differences by Survey Mode in a Respondent-Driven Sampling Study of Transgender People in Ontario, Canada.

PubMed

Scheim, Ayden I; Bauer, Greta R; Coleman, Todd A

2016-10-01

To describe survey mode uptake and sociodemographic differences by mode among respondents to a respondent-driven sampling survey of transgender people in Ontario, Canada. Survey mode was left to participant choice. Data were collected from 433 transgender Ontarians in 2009-2010 through a self-administered questionnaire, available online, by paper copy, or by telephone with language interpretation. Paper respondents (9.5%) were significantly more likely to be Aboriginal or persons of color, underhoused, sex workers, and unemployed or receiving disability benefits. In Canada and similar high-income countries, sampling transgender populations that are diverse with respect to social determinants of health may be best carried out with multimode surveys.

A Coarse-Grained Elastic Network Atom Contact Model and Its Use in the Simulation of Protein Dynamics and the Prediction of the Effect of Mutations

PubMed Central

Frappier, Vincent; Najmanovich, Rafael J.

2014-01-01

Normal mode analysis (NMA) methods are widely used to study dynamic aspects of protein structures. Two critical components of NMA methods are coarse-graining in the level of simplification used to represent protein structures and the choice of potential energy functional form. There is a trade-off between speed and accuracy in different choices. In one extreme one finds accurate but slow molecular-dynamics based methods with all-atom representations and detailed atom potentials. On the other extreme, fast elastic network model (ENM) methods with Cα−only representations and simplified potentials that based on geometry alone, thus oblivious to protein sequence. Here we present ENCoM, an Elastic Network Contact Model that employs a potential energy function that includes a pairwise atom-type non-bonded interaction term and thus makes it possible to consider the effect of the specific nature of amino-acids on dynamics within the context of NMA. ENCoM is as fast as existing ENM methods and outperforms such methods in the generation of conformational ensembles. Here we introduce a new application for NMA methods with the use of ENCoM in the prediction of the effect of mutations on protein stability. While existing methods are based on machine learning or enthalpic considerations, the use of ENCoM, based on vibrational normal modes, is based on entropic considerations. This represents a novel area of application for NMA methods and a novel approach for the prediction of the effect of mutations. We compare ENCoM to a large number of methods in terms of accuracy and self-consistency. We show that the accuracy of ENCoM is comparable to that of the best existing methods. We show that existing methods are biased towards the prediction of destabilizing mutations and that ENCoM is less biased at predicting stabilizing mutations. PMID:24762569

Index-antiguided planar waveguide lasers with large mode area

NASA Astrophysics Data System (ADS)

Liu, Yuanye

The on-going research and application interests with high power large-mode-area (LMA) waveguide lasers, especially in fiber geometry, at the beginning of this century drive the development of many novel waveguide designs. Index antiguiding, proposed by Siegman in 2003, is among one of them. The goal for index antiguiding is to introduce transversal modal loss with the relative simple waveguide design while maintain single transverse mode operation for good beam quality. The idea which is selectively support of fundamental mode is facilitated by involving certain level of signal regeneration inside the waveguide core. Since the modal loss is closed associated with waveguide design parameters such as core size and refractive index, the amount of gain inside the core provides active control of transverse modes inside index-antiguiding waveguide. For example, fundamental transverse mode inside such waveguide can be excited and propagate lossless when sufficient optical gain is provided. This often requires doped waveguide core and optical pumping at corresponding absorption band. However, the involvement of optical pumping also has its consequences. Phenomena such as thermal-optic effect and gain spatial hole-burning which are commonly found in bulk lasers request attention when scaling up output power with LMA index-antiguided waveguide amplifiers and resonators. In response, three key challenges of index-antiguided planar waveguide lasers, namely, guiding mechanism, power efficiency and transverse mode discrimination, are analyzed theoretically and experimentally in this dissertation. Experiments are based on two index-antiguided planar waveguide chips, whose core thickness are 220 microm and 400 microm respectively. The material of waveguide core is 1% Neodymium-doped Yttrium Aluminium garnet, or Nd:YAG while the cladding is made from Terbium Gallium garnet, or TGG. Due to the face pumping and limited pump power, it is found, with 220 microm-thick-core chip, that the guidance of the fundamental transverse mode along two orthogonal directions in a transverse plane is different. Along the bounded direction, index antiguiding prevails with negligible thermal refractive focusing while along the unbounded direction, the lasing mode is guided by thermal refractive focusing with negligible quadratic gain focusing. It is also founded that the quadratic thermal focusing will dominate the mode guidance in 220 microm chip with the help of additional pump. All these discovery calls for an active thermal control. The modal discriminative loss, though beneficial for transverse mode control, yet reduces the lasing efficiency. To model it, a 3-D lasing output power calculation model is developed based on spatial rate equations. The simulation results show good agreement with experiment data where slope efficiency curve are measured using multiple output couplers. The 10% slope efficiency with respect to incident pump power is the highest slope efficiency recorded in index-antiguided waveguide continuous-wave lasers. The model indicates more efficient pump absorption can facilitate further power scaling. The role of the modal discriminative loss in transverse mode competition is discussed. A theoretical model based on Rigrod analysis and spatial hole-burning is developed. The simulation shows reasonable agreement with experiment results in both chips. The single fundamental mode operation up to 10 times above the lasing threshold for 220 microm chip is achieved, which is limited by the incident pump power. However, as the core size increases, the modal distributed loss due to the index antiguiding is found to be less effective in transverse mode control. Other modal loss is needed to facilitate the suppression of higher-order modes. Based on the model, a strategy is proposed aiming to maximize the single mode output. It is also noted that the transverse mode competition model is also suitable for other lasers system with well-defined modal loss. Based on the models and experiment data, the index-antiguided planar waveguide lasers are proved to be capable of maintaining large-mode-area single transverse mode operation with the potential of power scaling. However, it is also shown that proper waveguide design is essential. The remaining challenges are the material choices for waveguide fabrication, especially for high power applications.

Robust fault tolerant control based on sliding mode method for uncertain linear systems with quantization.

PubMed

Hao, Li-Ying; Yang, Guang-Hong

2013-09-01

This paper is concerned with the problem of robust fault-tolerant compensation control problem for uncertain linear systems subject to both state and input signal quantization. By incorporating novel matrix full-rank factorization technique with sliding surface design successfully, the total failure of certain actuators can be coped with, under a special actuator redundancy assumption. In order to compensate for quantization errors, an adjustment range of quantization sensitivity for a dynamic uniform quantizer is given through the flexible choices of design parameters. Comparing with the existing results, the derived inequality condition leads to the fault tolerance ability stronger and much wider scope of applicability. With a static adjustment policy of quantization sensitivity, an adaptive sliding mode controller is then designed to maintain the sliding mode, where the gain of the nonlinear unit vector term is updated automatically to compensate for the effects of actuator faults, quantization errors, exogenous disturbances and parameter uncertainties without the need for a fault detection and isolation (FDI) mechanism. Finally, the effectiveness of the proposed design method is illustrated via a model of a rocket fairing structural-acoustic. Copyright © 2013 ISA. Published by Elsevier Ltd. All rights reserved.

Evolving forecasting classifications and applications in health forecasting

PubMed Central

Soyiri, Ireneous N; Reidpath, Daniel D

2012-01-01

Health forecasting forewarns the health community about future health situations and disease episodes so that health systems can better allocate resources and manage demand. The tools used for developing and measuring the accuracy and validity of health forecasts commonly are not defined although they are usually adapted forms of statistical procedures. This review identifies previous typologies used in classifying the forecasting methods commonly used in forecasting health conditions or situations. It then discusses the strengths and weaknesses of these methods and presents the choices available for measuring the accuracy of health-forecasting models, including a note on the discrepancies in the modes of validation. PMID:22615533

Goldstone-like phonon modes in a (111)-strained perovskite

NASA Astrophysics Data System (ADS)

Marthinsen, A.; Griffin, S. M.; Moreau, M.; Grande, T.; Tybell, T.; Selbach, S. M.

2018-01-01

Goldstone modes are massless particles resulting from spontaneous symmetry breaking. Although such modes are found in elementary particle physics as well as in condensed-matter systems like superfluid helium, superconductors, and magnons, structural Goldstone modes are rare. Epitaxial strain in thin films can induce structures and properties not accessible in bulk and has been intensively studied for (001)-oriented perovskite oxides. Here we predict Goldstone-like phonon modes in (111)-strained SrMn O3 by first-principles calculations. Under compressive strain the coupling between two in-plane rotational instabilities gives rise to a Mexican hat-shaped energy surface characteristic of a Goldstone mode. Conversely, large tensile strain induces in-plane polar instabilities with no directional preference, giving rise to a continuous polar ground state. Such phonon modes with U (1) symmetry could emulate structural condensed-matter Higgs modes. The mass of this Higgs boson, given by the shape of the Mexican hat energy surface, can be tuned by strain through proper choice of substrate.

Recent ride-sharing research and policy findings. Transportation Research Record

DOE Office of Scientific and Technical Information (OSTI.GOV)

Mehranian, M.; Wachs, M.; Shoup, D.

1987-01-01

The five papers in the report deal with the following areas: parking cost and mode choices among downtown workers: a case study; duration of carpool and vanpool usage by clients of rides; a ride-sharing market analysis survey of commuter attitudes and behavior at a major suburban employment center; alternative access modes data-base project; formulating ride-sharing goals for transportation and air-quality plans: Southern California as a case study.

Adaptive control system of dump truck traction electric drive

NASA Astrophysics Data System (ADS)

Bolshunova, O. M.; Korzhev, A. A.; Kamyshyan, A. M.

2018-03-01

The paper describes the operational factors that determine the accident rate of a quarry motor vehicle and assessment of their impact on the choice of the operation mode of the traction drive control system.

Image-driven Population Analysis through Mixture Modeling

PubMed Central

Sabuncu, Mert R.; Balci, Serdar K.; Shenton, Martha E.; Golland, Polina

2009-01-01

We present iCluster, a fast and efficient algorithm that clusters a set of images while co-registering them using a parameterized, nonlinear transformation model. The output of the algorithm is a small number of template images that represent different modes in a population. This is in contrast with traditional, hypothesis-driven computational anatomy approaches that assume a single template to construct an atlas. We derive the algorithm based on a generative model of an image population as a mixture of deformable template images. We validate and explore our method in four experiments. In the first experiment, we use synthetic data to explore the behavior of the algorithm and inform a design choice on parameter settings. In the second experiment, we demonstrate the utility of having multiple atlases for the application of localizing temporal lobe brain structures in a pool of subjects that contains healthy controls and schizophrenia patients. Next, we employ iCluster to partition a data set of 415 whole brain MR volumes of subjects aged 18 through 96 years into three anatomical subgroups. Our analysis suggests that these subgroups mainly correspond to age groups. The templates reveal significant structural differences across these age groups that confirm previous findings in aging research. In the final experiment, we run iCluster on a group of 15 patients with dementia and 15 age-matched healthy controls. The algorithm produces two modes, one of which contains dementia patients only. These results suggest that the algorithm can be used to discover sub-populations that correspond to interesting structural or functional “modes.” PMID:19336293

Simulation and automation of thermal processes in oil well

NASA Astrophysics Data System (ADS)

Kostarev, N. A.; Trufanova, N. M.

2018-03-01

The paper presents a two-dimensional mathematical model and a numerical analysis of heat and mass transfer processes in an oil well. The proposed and implemented mathematical model of the process of heat and mass transfer in an oil well allows analyzing the temperature field in the whole space of an oil well and is suitable for any fields equipped with an electric centrifugal pump. Temperature and velocity fields were obtained, as well as the distribution of temperature on the wall of the pump tubing along the depth of the well. On the basis of the obtained temperature fields, the modes of periodic heating of the well by the heating cable were developed. Recommendations are given on the choice of power parameters and the time of warming up the well.

Marine vessels as substitutes for heavy-duty trucks in Great Lakes freight transportation.

PubMed

Comer, Bryan; Corbett, James J; Hawker, J Scott; Korfmacher, Karl; Lee, Earl E; Prokop, Chris; Winebrake, James J

2010-07-01

This paper applies a geospatial network optimization model to explore environmental, economic, and time-of-delivery tradeoffs associated with the application of marine vessels as substitutes for heavy-duty trucks operating in the Great Lakes region. The geospatial model integrates U.S. and Canadian highway, rail, and waterway networks to create an intermodal network and characterizes this network using temporal, economic, and environmental attributes (including emissions of carbon dioxide, particulate matter, carbon monoxide, sulfur oxides, volatile organic compounds, and nitrogen oxides). A case study evaluates tradeoffs associated with containerized traffic flow in the Great Lakes region, demonstrating how choice of freight mode affects the environmental performance of movement of goods. These results suggest opportunities to improve the environmental performance of freight transport through infrastructure development, technology implementation, and economic incentives.

Characteristics of movement and factors affecting the choice of mode of transport of community on the bank of Musi River of Palembang City of South Sumatra

NASA Astrophysics Data System (ADS)

Arliansyah, Joni; Hartono, Yusuf; Hastuti, Yulia; Astuti, Rinna

2017-11-01

Palembang City is one of the cities having the largest river in Indonesia and it should be able to take advantage of river transportation as an alternative choice. Inadequate availability of river transport facilities and infrastructures makes the people prefer other modes of land transportation rather than using river transportation. In addition, the development planning of river transportation such as the development of river taxi is less successful because it is not yet based on the movement pattern of the origin of the community travel destination. Based on the above matter, this study was conducted. The aim of the study was to find out the characteristics and factors affecting the mode choice of the community living along the bank of Musi River of Palembang City to be the basis of the development of river transportation system in Palembang City. The selected modes were motorcycles, cars, city transports, and ketek (motorized boats). Survey of home interviews was conducted to determine the origin of the destination and characteristics of travel was conducted in 30 villages located on the banks of Musi River. Field survey was conducted to determine the conditions and types of existing river transportation facilities and services. The results show that only 5.3 % of the occurrence movement used river transportation, the rest used motorcycles (69.1%), urban transport (15.9 %) and cars (9.7%), with the travel range less than10 minutes and 10 - 20 minutes as much as 43.2 % and 29 % of the total trips. From the socioeconomic profile of the community, it is found that most of the people living along the Musi River have low and middle incomes with the largest types of jobs as workers, students, shop owner, and housewives. The peak movement time for the movement of river transport occurs at 7:00 - 8:00, 10:00 - 11:00 and 16:00 - 17:00 with the movement of origin of the destination of river transportation is known to be 50% at the traditional market center of Dermaga of 16 Ilir. Types of river transportation used for short trips are large, medium and small motorized boats. While for longer trips there are large and medium size speedboats. The statistical analysis results showed that the parameters affecting the mode choice of the community living along the bank of Musi River were age, occupation, monthly income, house types, and travel time.

Statistics of Macroturbulence from Flow Equations

NASA Astrophysics Data System (ADS)

Marston, Brad; Iadecola, Thomas; Qi, Wanming

2012-02-01

Probability distribution functions of stochastically-driven and frictionally-damped fluids are governed by a linear framework that resembles quantum many-body theory. Besides the Fokker-Planck approach, there is a closely related Hopf functional methodfootnotetextOokie Ma and J. B. Marston, J. Stat. Phys. Th. Exp. P10007 (2005).; in both formalisms, zero modes of linear operators describe the stationary non-equilibrium statistics. To access the statistics, we generalize the flow equation approachfootnotetextF. Wegner, Ann. Phys. 3, 77 (1994). (also known as the method of continuous unitary transformationsfootnotetextS. D. Glazek and K. G. Wilson, Phys. Rev. D 48, 5863 (1993); Phys. Rev. D 49, 4214 (1994).) to find the zero mode. We test the approach using a prototypical model of geophysical and astrophysical flows on a rotating sphere that spontaneously organizes into a coherent jet. Good agreement is found with low-order equal-time statistics accumulated by direct numerical simulation, the traditional method. Different choices for the generators of the continuous transformations, and for closure approximations of the operator algebra, are discussed.

Analysis of potential diverted of passenger car to the new toll road (case study: Cileunyi - Sumedang, West Java)

NASA Astrophysics Data System (ADS)

Prahara, Eduardi; Suangga, Made; Lutfi Ansori, Ahmad

2017-12-01

This study aims to determine of potential of passenger car divert from national road to on-construction Cisumdawu Toll Road. The study was conducted by traffic count survey and followed by a roadside interview survey. Stated Preference method was used in order to analyse trip forecasting value. Mode choice model of new trip mode plans (Cisumdawu Toll Road) and current intercity road for Cileunyi - Sumedang is (UJT -UJR ) = 0.1079-0.507726x 1-0.8953764x 2, while Sumedang - Cileunyi is (UJT -UJR ) = 0.0790-0.301341x 1-0.548446x 2. Multiple linear regression analysis was used to obtain the forecasting of private vehicle that diverts to the new toll road (Cisumdawu Toll Road). Trip characteristics such as trip origin and destination, types of trips, occupations, salary, and others become a motive for respondents to choose a new trip mode. Results of the new trip mode forecasting that prefer to divert to the toll road in terms of the value of cost and time for Cileunyi - Sumedang are 74.11% and 86.62% respectively, while for Sumedang - Cileunyi are 69.60% and 76.48% respectively. These results are relatively high compare to toll planning document. The impact of this results can be determined such as lower overall fuel consumption, lower pollution and more important is the maintenance cost of national road will be decrease.

Expanding Commuter Choice Tax Benefit Options

DOT National Transportation Integrated Search

2003-10-01

According to the US Census, 76.3 percent of U.S. workers drive alone to work. The Internal Revenue Code Section 132(f) provides incentives for employers to encourage alternative mode use, specifically transit and vanpooling, through commuter benefits...

Think, blink or sleep on it? The impact of modes of thought on complex decision making.

PubMed

Newell, Ben R; Wong, Kwan Yao; Cheung, Jeremy C H; Rakow, Tim

2009-04-01

This paper examines controversial claims about the merit of "unconscious thought" for making complex decisions. In four experiments, participants were presented with complex decisions and were asked to choose the best option immediately, after a period of conscious deliberation, or after a period of distraction (said to encourage "unconscious thought processes"). In all experiments the majority of participants chose the option predicted by their own subjective attribute weighting scores, regardless of the mode of thought employed. There was little evidence for the superiority of choices made "unconsciously", but some evidence that conscious deliberation can lead to better choices. The final experiment suggested that the task is best conceptualized as one involving "online judgement" rather than one in which decisions are made after periods of deliberation or distraction. The results suggest that we should be cautious in accepting the advice to "stop thinking" about complex decisions.

Guided wave mode selection for inhomogeneous elastic waveguides using frequency domain finite element approach.

PubMed

Chillara, Vamshi Krishna; Ren, Baiyang; Lissenden, Cliff J

2016-04-01

This article describes the use of the frequency domain finite element (FDFE) technique for guided wave mode selection in inhomogeneous waveguides. Problems with Rayleigh-Lamb and Shear-Horizontal mode excitation in isotropic homogeneous plates are first studied to demonstrate the application of the approach. Then, two specific cases of inhomogeneous waveguides are studied using FDFE. Finally, an example of guided wave mode selection for inspecting disbonds in composites is presented. Identification of sensitive and insensitive modes for defect inspection is demonstrated. As the discretization parameters affect the accuracy of the results obtained from FDFE, effect of spatial discretization and the length of the domain used for the spatial fast Fourier transform are studied. Some recommendations with regard to the choice of the above parameters are provided. Copyright © 2015 Elsevier B.V. All rights reserved.

Developing a database for pedestrians' earthquake emergency evacuation in indoor scenarios.

PubMed

Zhou, Junxue; Li, Sha; Nie, Gaozhong; Fan, Xiwei; Tan, Jinxian; Li, Huayue; Pang, Xiaoke

2018-01-01

With the booming development of evacuation simulation software, developing an extensive database in indoor scenarios for evacuation models is imperative. In this paper, we conduct a qualitative and quantitative analysis of the collected videotapes and aim to provide a complete and unitary database of pedestrians' earthquake emergency response behaviors in indoor scenarios, including human-environment interactions. Using the qualitative analysis method, we extract keyword groups and keywords that code the response modes of pedestrians and construct a general decision flowchart using chronological organization. Using the quantitative analysis method, we analyze data on the delay time, evacuation speed, evacuation route and emergency exit choices. Furthermore, we study the effect of classroom layout on emergency evacuation. The database for indoor scenarios provides reliable input parameters and allows the construction of real and effective constraints for use in software and mathematical models. The database can also be used to validate the accuracy of evacuation models.

The economics of satellite maintenance

NASA Technical Reports Server (NTRS)

Derocher, W. L., Jr.; Sosnay, R. G.

1975-01-01

The primary goal of the space transportation system - to reduce the cost of space programs while satisfying their mission requirements - can be enhanced by the proper choice of a satellite-maintenance concept. This paper develops the life-cycle costs of performing an automated satellite program during the shuttle era in three competitive modes: expendable, ground-refurbishable, and in-orbit maintainable. In-orbit maintenance is shown to be the most economic maintenance mode for both low- and high-earth orbits.

Genetics of host plant use and life history in the comma butterfly across Europe: varying modes of inheritance as a potential reproductive barrier.

PubMed

Nygren, G H; Nylin, S; Stefanescu, C

2006-11-01

Comma butterflies (Nymphalidae: Polygonia c-album L.) from one Belgian site and three Spanish sites were crossed with butterflies from a Swedish population in order to investigate inheritance of female host plant choice, egg mass and larval growth rate. We found three different modes of inheritance for the three investigated traits. In line with earlier results from crosses between Swedish and English populations, the results regarding female oviposition preference (choice between Urtica dioica and Salix caprea) showed X-linked inheritance to be of importance for the variation between Sweden and the other sites. Egg mass and growth rate did not show any sex-linked inheritance. Egg mass differences between populations seem to be controlled mainly by additive autosomal genes, as hybrids showed intermediate values. The growth rates of both hybrid types following reciprocal crossings were similar to each other but consistently higher than for the two source populations, suggesting a nonadditive mode of inheritance which is not sex-linked. The different modes of inheritance for host plant preference vs. important life history traits are likely to result in hybrids with unfit combinations of traits. This type of potential reproductive barrier based on multiple ecologically important traits deserves more attention, as it should be a common situation for instance in the early stages of population divergence in host plant usage, facilitating ecological speciation.

Second-order sliding mode control for DFIG-based wind turbines fault ride-through capability enhancement.

PubMed

Benbouzid, Mohamed; Beltran, Brice; Amirat, Yassine; Yao, Gang; Han, Jingang; Mangel, Hervé

2014-05-01

This paper deals with the fault ride-through capability assessment of a doubly fed induction generator-based wind turbine using a high-order sliding mode control. Indeed, it has been recently suggested that sliding mode control is a solution of choice to the fault ride-through problem. In this context, this paper proposes a second-order sliding mode as an improved solution that handle the classical sliding mode chattering problem. Indeed, the main and attractive features of high-order sliding modes are robustness against external disturbances, the grids faults in particular, and chattering-free behavior (no extra mechanical stress on the wind turbine drive train). Simulations using the NREL FAST code on a 1.5-MW wind turbine are carried out to evaluate ride-through performance of the proposed high-order sliding mode control strategy in case of grid frequency variations and unbalanced voltage sags. Copyright © 2014 ISA. Published by Elsevier Ltd. All rights reserved.

A dual-polarized and reconfigurable reflectarray for generation of vortex radio waves

NASA Astrophysics Data System (ADS)

Li, Chen-Chen; Wu, Lin-Sheng; Yin, Wen-Yan

2018-05-01

Electromagnetic (EM) waves with orbital angular momentum (OAM) provide a new degree of freedom for channel multiplexing to improve the capacity of wireless communication. For OAM-based systems, it is important to design specific configurations to generate vortex radios. In this paper, a reconfigurable reflectarray antenna is proposed with independent control of dual polarizations. A reflective cell is proposed by properly assigning the variable capacitances of four varactors, which are placed between metal square rings of each unit. The varactors of each unit are divided into two groups and the capacitance value of each group controls the reflection phase for a single linear polarization. By using the equivalent circuit model, the reflective units and array can be designed efficiently. Smooth phase variation and good reflection efficiency are achieved. Then, the reflectarray is set into sectors and a simple phase-shifting surface model is used to generate vortex beam. Each sector is realized with reflective units satisfying desired reflection phases for different modes. This kind of OAM-generating method can reduce the required variation range of reflection phase and provide more choices for a specific OAM mode combination with dual polarization, which is helpful to reduce mutual coupling between the two linear polarizations. Finally, full-wave simulations show that the 0, ±1, ±2 modes of vortex beam are successfully generated at 3.5 GHz with arbitrary combination in dual-polarization, which is also supported by OAM modes purity and reflection efficiency analysis. Therefore, in our design, the reconfigurable OAM and spin angular momentum (SAM), related with polarization, can be utilized simultaneously and independently for high-capacity wireless communication.

Regional TEC dynamic modeling based on Slepian functions

NASA Astrophysics Data System (ADS)

Sharifi, Mohammad Ali; Farzaneh, Saeed

2015-09-01

In this work, the three-dimensional state of the ionosphere has been estimated by integrating the spherical Slepian harmonic function and Kalman filter. The spherical Slepian harmonic functions have been used to establish the observation equations because of their properties in local modeling. Spherical harmonics are poor choices to represent or analyze geophysical processes without perfect global coverage but the Slepian functions afford spatial and spectral selectivity. The Kalman filter has been utilized to perform the parameter estimation due to its suitable properties in processing the GPS measurements in the real-time mode. The proposed model has been applied to the real data obtained from the ground-based GPS observations across some portion of the IGS network in Europe. Results have been compared with the estimated TECs by the CODE, ESA, IGS centers and IRI-2012 model. The results indicated that the proposed model which takes advantage of the Slepian basis and Kalman filter is efficient and allows for the generation of the near-real-time regional TEC map.

The GFDL global atmosphere and land model AM4.0/LM4.0: 2. Model description, sensitivity studies, and tuning strategies

USGS Publications Warehouse

Zhao, M.; Golaz, J.-C.; Held, I. M.; Guo, H.; Balaji, V.; Benson, R.; Chen, J.-H.; Chen, X.; Donner, L. J.; Dunne, J. P.; Dunne, Krista A.; Durachta, J.; Fan, S.-M.; Freidenreich, S. M.; Garner, S. T.; Ginoux, P.; Harris, L. M.; Horowitz, L. W.; Krasting, J. P.; Langenhorst, A. R.; Liang, Z.; Lin, P.; Lin, S.-J.; Malyshev, S. L.; Mason, E.; Milly, Paul C.D.; Ming, Y.; Naik, V.; Paulot, F.; Paynter, D.; Phillipps, P.; Radhakrishnan, A.; Ramaswamy, V.; Robinson, T.; Schwarzkopf, D.; Seman, C. J.; Shevliakova, E.; Shen, Z.; Shin, H.; Silvers, L.; Wilson, J. R.; Winton, M.; Wittenberg, A. T.; Wyman, B.; Xiang, B.

2018-01-01

In Part 2 of this two‐part paper, documentation is provided of key aspects of a version of the AM4.0/LM4.0 atmosphere/land model that will serve as a base for a new set of climate and Earth system models (CM4 and ESM4) under development at NOAA's Geophysical Fluid Dynamics Laboratory (GFDL). The quality of the simulation in AMIP (Atmospheric Model Intercomparison Project) mode has been provided in Part 1. Part 2 provides documentation of key components and some sensitivities to choices of model formulation and values of parameters, highlighting the convection parameterization and orographic gravity wave drag. The approach taken to tune the model's clouds to observations is a particular focal point. Care is taken to describe the extent to which aerosol effective forcing and Cess sensitivity have been tuned through the model development process, both of which are relevant to the ability of the model to simulate the evolution of temperatures over the last century when coupled to an ocean model.

The GFDL Global Atmosphere and Land Model AM4.0/LM4.0: 2. Model Description, Sensitivity Studies, and Tuning Strategies

DOE PAGES

Zhao, Ming; Golaz, J. -C.; Held, I. M.; ...

2018-02-19

Here, in Part 2 of this two–part paper, documentation is provided of key aspects of a version of the AM4.0/LM4.0 atmosphere/land model that will serve as a base for a new set of climate and Earth system models (CM4 and ESM4) under development at NOAA's Geophysical Fluid Dynamics Laboratory (GFDL). The quality of the simulation in AMIP (Atmospheric Model Intercomparison Project) mode has been provided in Part 1. Part 2 provides documentation of key components and some sensitivities to choices of model formulation and values of parameters, highlighting the convection parameterization and orographic gravity wave drag. The approach taken tomore » tune the model's clouds to observations is a particular focal point. Care is taken to describe the extent to which aerosol effective forcing and Cess sensitivity have been tuned through the model development process, both of which are relevant to the ability of the model to simulate the evolution of temperatures over the last century when coupled to an ocean model.« less

The GFDL Global Atmosphere and Land Model AM4.0/LM4.0: 2. Model Description, Sensitivity Studies, and Tuning Strategies

NASA Astrophysics Data System (ADS)

Zhao, M.; Golaz, J.-C.; Held, I. M.; Guo, H.; Balaji, V.; Benson, R.; Chen, J.-H.; Chen, X.; Donner, L. J.; Dunne, J. P.; Dunne, K.; Durachta, J.; Fan, S.-M.; Freidenreich, S. M.; Garner, S. T.; Ginoux, P.; Harris, L. M.; Horowitz, L. W.; Krasting, J. P.; Langenhorst, A. R.; Liang, Z.; Lin, P.; Lin, S.-J.; Malyshev, S. L.; Mason, E.; Milly, P. C. D.; Ming, Y.; Naik, V.; Paulot, F.; Paynter, D.; Phillipps, P.; Radhakrishnan, A.; Ramaswamy, V.; Robinson, T.; Schwarzkopf, D.; Seman, C. J.; Shevliakova, E.; Shen, Z.; Shin, H.; Silvers, L. G.; Wilson, J. R.; Winton, M.; Wittenberg, A. T.; Wyman, B.; Xiang, B.

2018-03-01

In Part 2 of this two-part paper, documentation is provided of key aspects of a version of the AM4.0/LM4.0 atmosphere/land model that will serve as a base for a new set of climate and Earth system models (CM4 and ESM4) under development at NOAA's Geophysical Fluid Dynamics Laboratory (GFDL). The quality of the simulation in AMIP (Atmospheric Model Intercomparison Project) mode has been provided in Part 1. Part 2 provides documentation of key components and some sensitivities to choices of model formulation and values of parameters, highlighting the convection parameterization and orographic gravity wave drag. The approach taken to tune the model's clouds to observations is a particular focal point. Care is taken to describe the extent to which aerosol effective forcing and Cess sensitivity have been tuned through the model development process, both of which are relevant to the ability of the model to simulate the evolution of temperatures over the last century when coupled to an ocean model.

The GFDL Global Atmosphere and Land Model AM4.0/LM4.0: 2. Model Description, Sensitivity Studies, and Tuning Strategies

DOE Office of Scientific and Technical Information (OSTI.GOV)

Zhao, Ming; Golaz, J. -C.; Held, I. M.

Here, in Part 2 of this two–part paper, documentation is provided of key aspects of a version of the AM4.0/LM4.0 atmosphere/land model that will serve as a base for a new set of climate and Earth system models (CM4 and ESM4) under development at NOAA's Geophysical Fluid Dynamics Laboratory (GFDL). The quality of the simulation in AMIP (Atmospheric Model Intercomparison Project) mode has been provided in Part 1. Part 2 provides documentation of key components and some sensitivities to choices of model formulation and values of parameters, highlighting the convection parameterization and orographic gravity wave drag. The approach taken tomore » tune the model's clouds to observations is a particular focal point. Care is taken to describe the extent to which aerosol effective forcing and Cess sensitivity have been tuned through the model development process, both of which are relevant to the ability of the model to simulate the evolution of temperatures over the last century when coupled to an ocean model.« less

High reliability level on single-mode 980nm-1060 nm diode lasers for telecommunication and industrial applications

NASA Astrophysics Data System (ADS)

Van de Casteele, J.; Bettiati, M.; Laruelle, F.; Cargemel, V.; Pagnod-Rossiaux, P.; Garabedian, P.; Raymond, L.; Laffitte, D.; Fromy, S.; Chambonnet, D.; Hirtz, J. P.

2008-02-01

We demonstrate very high reliability level on 980-1060nm high-power single-mode lasers through multi-cell tests. First, we show how our chip design and technology enables high reliability levels. Then, we aged 758 devices during 9500 hours among 6 cells with high current (0.8A-1.2A) and high submount temperature (65°C-105°C) for the reliability demonstration. Sudden catastrophic failure is the main degradation mechanism observed. A statistical failure rate model gives an Arrhenius thermal activation energy of 0.51eV and a power law forward current acceleration factor of 5.9. For high-power submarine applications (360mW pump module output optical power), this model exhibits a failure rate as low as 9 FIT at 13°C, while ultra-high power terrestrial modules (600mW) lie below 220 FIT at 25°C. Wear-out phenomena is observed only for very high current level without any reliability impact under 1.1A. For the 1060nm chip, step-stress tests were performed and a set of devices were aged during more than 2000 hours in different stress conditions. First results are in accordance with 980nm product with more than 100khours estimated MTTF. These reliability and performance features of 980-1060nm laser diodes will make high-power single-mode emitters the best choice for a number of telecommunication and industrial applications in the next few years.

Influence of injection mode on transport properties in kilometer-scale three-dimensional discrete fracture networks

DOE Office of Scientific and Technical Information (OSTI.GOV)

Hyman, Jeffrey De'Haven; Painter, S. L.; Viswanathan, H.

We investigate how the choice of injection mode impacts transport properties in kilometer-scale three-dimensional discrete fracture networks (DFN). The choice of injection mode, resident and flux-weighted, is designed to mimic different physical phenomena. It has been hypothesized that solute plumes injected under resident conditions evolve to behave similarly to solutes injected under flux-weighted conditions. Previously, computational limitations have prohibited the large-scale simulations required to investigate this hypothesis. We investigate this hypothesis by using a high-performance DFN suite, dfnWorks, to simulate flow in kilometer-scale three-dimensional DFNs based on fractured granite at the Forsmark site in Sweden, and adopt a Lagrangian approachmore » to simulate transport therein. Results show that after traveling through a pre-equilibrium region, both injection methods exhibit linear scaling of the first moment of travel time and power law scaling of the breakthrough curve with similar exponents, slightly larger than 2. Lastly, the physical mechanisms behind this evolution appear to be the combination of in-network channeling of mass into larger fractures, which offer reduced resistance to flow, and in-fracture channeling, which results from the topology of the DFN.« less

Influence of injection mode on transport properties in kilometer-scale three-dimensional discrete fracture networks

DOE PAGES

Hyman, Jeffrey De'Haven; Painter, S. L.; Viswanathan, H.; ...

2015-09-12

We investigate how the choice of injection mode impacts transport properties in kilometer-scale three-dimensional discrete fracture networks (DFN). The choice of injection mode, resident and flux-weighted, is designed to mimic different physical phenomena. It has been hypothesized that solute plumes injected under resident conditions evolve to behave similarly to solutes injected under flux-weighted conditions. Previously, computational limitations have prohibited the large-scale simulations required to investigate this hypothesis. We investigate this hypothesis by using a high-performance DFN suite, dfnWorks, to simulate flow in kilometer-scale three-dimensional DFNs based on fractured granite at the Forsmark site in Sweden, and adopt a Lagrangian approachmore » to simulate transport therein. Results show that after traveling through a pre-equilibrium region, both injection methods exhibit linear scaling of the first moment of travel time and power law scaling of the breakthrough curve with similar exponents, slightly larger than 2. Lastly, the physical mechanisms behind this evolution appear to be the combination of in-network channeling of mass into larger fractures, which offer reduced resistance to flow, and in-fracture channeling, which results from the topology of the DFN.« less

Explicit control of adaptive automation under different levels of environmental stress.

PubMed

Sauer, Jürgen; Kao, Chung-Shan; Wastell, David; Nickel, Peter

2011-08-01

This article examines the effectiveness of three different forms of explicit control of adaptive automation under low- and high-stress conditions, operationalised by different levels of noise. In total, 60 participants were assigned to one of three types of automation design (free, prompted and forced choice). They were trained for 4 h on a highly automated simulation of a process control environment, called AutoCAMS. This was followed by a 4-h testing session under noise exposure and quiet conditions. Measures of performance, psychophysiology and subjective reactions were taken. The results showed that all three modes of explicit control of adaptive automation modes were able to attenuate the negative effects of noise. This was partly due to the fact that operators opted for higher levels of automation under noise. It also emerged that forced choice showed marginal advantages over the two other automation modes. Statement of Relevance: This work is relevant to the design of adaptive automation since it emphasises the need to consider the impact of work-related stressors during task completion. During the presence of stressors, different forms of operator support through automation may be required than under more favourable working conditions.

What Drives Them to Drive?—Parents' Reasons for Choosing the Car to Take Their Children to School

PubMed Central

Westman, Jessica; Friman, Margareta; Olsson, Lars E.

2017-01-01

Children's school journeys have changed vastly during recent decades: More children are being driven to school in private cars instead of walking and cycling, with many who are entitled to a free school bus service still being driven. Earlier research into travel mode choice has often investigated how urban form impacts upon mode choice regarding school journeys—in particular how urban form hinders or enables the use of the active mode. This paper quantitatively explores parents' stated reasons for choosing the car and the relationship between these reasons and the decision to use the car to take their children to school. We additionally investigate the relationship between sociodemographic factors, distance, and both the stated reasons and the actual mode decision. A sample of 245 parents (194 women) of school children aged 10–15 in the County of Värmland in Sweden were included in the study. The results of PLS-SEM show that the factor Social convenience has a direct relationship with the frequency of car use indicating that the wish to accompany the child and the convenience of car impacts on car choice. If the child is not allowed to travel independently, the parents choose the car to take him/her to school. Sociodemographic factors had a direct relationship with the stated reasons, whereby parents with a higher level of education valued safety/security less. Quite surprisingly, distance (i.e., environmental factor) did not affect car use, indicating that parents drive their children to school regardless of distance. By isolating the particular reasons for choosing the car, this paper focuses on a potentially important missing piece as regards finding out what motivates the increasing car usage in children's school journeys. An increased knowledge of what motivates the decision to take children by car is important for effective policies aimed at changing parents' inclination toward choosing the car. PMID:29167653

Compressed modes for variational problems in mathematics and physics

PubMed Central

Ozoliņš, Vidvuds; Lai, Rongjie; Caflisch, Russel; Osher, Stanley

2013-01-01

This article describes a general formalism for obtaining spatially localized (“sparse”) solutions to a class of problems in mathematical physics, which can be recast as variational optimization problems, such as the important case of Schrödinger’s equation in quantum mechanics. Sparsity is achieved by adding an regularization term to the variational principle, which is shown to yield solutions with compact support (“compressed modes”). Linear combinations of these modes approximate the eigenvalue spectrum and eigenfunctions in a systematically improvable manner, and the localization properties of compressed modes make them an attractive choice for use with efficient numerical algorithms that scale linearly with the problem size. PMID:24170861

Psycholinguistics in Applied Linguistics: Trends and Perspectives.

ERIC Educational Resources Information Center

de Bot, Kees

2000-01-01

Discusses the relationship between the terms psycholinguistics and applied linguistics, and in the process explores key issues in multilingual processing, such as the structure of the bilingual lexicon, language choice in production and perception, and the language mode. (Author/VWL)

GPS-based household interview survey for the Cincinnati, Ohio Region : executive summary report.

DOT National Transportation Integrated Search

2012-02-29

PROJECT BACKGROUND: Household travel surveys (HTS) are designed to provide information about daily travel patterns, including : trip purposes, time of day decisions, mode choices, trip lengths and distances, activity locations, and : routes taken. Th...

Exploring bicycle route choice behavior with space syntax analysis : final report.

DOT National Transportation Integrated Search

2016-12-31

Cycling provides an environmentally friendly alternative mode of transportation. It improves : urban mobility, livability, and public health, and it also helps in reducing traffic congestion and : emissions. Cycling is gaining popularity both as a re...

Examining consumer behavior and travel choices.

DOT National Transportation Integrated Search

2013-02-01

This study represents a first attempt to answer a few of the questions that have arisen concerning multimodal transportation investments and the : impacts of mode shifts on the business community. This research aims to merge the long history of schol...

Changes over time in population level transport satisfaction and mode of travel: A 13 year repeat cross-sectional study, UK.

PubMed

Olsen, Jonathan R; Macdonald, Laura; Ellaway, Anne

2017-09-01

The aim of the study was to examine changes over time in satisfaction with usual transport mode, explore individual and area level characteristics as mediators in the likelihood of transport satisfaction, and whether any changes in transport satisfaction varied by these factors over time. Adults from West Central Scotland, United Kingdom, who participated at both waves of the repeat cross-sectional 'Transport, Health and Well-being Study' conducted in 1997 (n=2735) and 2010 (n=2024) were assessed. Individuals completed a detailed postal questionnaire at both time points including self-rated satisfaction with usual transport mode (using a seven point scale subsequently dichotomised to a binary outcome of satisfied (1-2) and other (3-7)). Participants reported usual transport mode for travel to various destinations. A multilevel logistic regression model was used and individuals were nested within areas (c. 4000 population). At the 2010 sweep, two thirds (n=1345) of individuals were satisfied with their transport choice. Those with fair/poor health were less satisfied with their usual transport compared to those in better health (Odds Ratio (OR) 0.49, p<0.001). Access to a car was associated with overall transport satisfaction (OR 2.63, p<0.001) and the effect of deprivation on transport satisfaction was mitigated when adjusted by household car access. Transport satisfaction increased more from 1997 to 2010 for retired individuals compared to those in employment (OR 1.40, p=0.032), and for those who travelled by public transport (OR 2.39, p=0.005) and using multiple modes (OR 2.19, p<0.001) compared to those who travelled by car. The proportion of those who travelled using public transport, active modes or by multiple mode increased journey satisfaction over time at a greater rate than those who travelled by car, highlighting that continued efforts should be made to promote these more active transport modes which have potential to impact on health.

A recurrent network mechanism of time integration in perceptual decisions.

PubMed

Wong, Kong-Fatt; Wang, Xiao-Jing

2006-01-25

Recent physiological studies using behaving monkeys revealed that, in a two-alternative forced-choice visual motion discrimination task, reaction time was correlated with ramping of spike activity of lateral intraparietal cortical neurons. The ramping activity appears to reflect temporal accumulation, on a timescale of hundreds of milliseconds, of sensory evidence before a decision is reached. To elucidate the cellular and circuit basis of such integration times, we developed and investigated a simplified two-variable version of a biophysically realistic cortical network model of decision making. In this model, slow time integration can be achieved robustly if excitatory reverberation is primarily mediated by NMDA receptors; our model with only fast AMPA receptors at recurrent synapses produces decision times that are not comparable with experimental observations. Moreover, we found two distinct modes of network behavior, in which decision computation by winner-take-all competition is instantiated with or without attractor states for working memory. Decision process is closely linked to the local dynamics, in the "decision space" of the system, in the vicinity of an unstable saddle steady state that separates the basins of attraction for the two alternative choices. This picture provides a rigorous and quantitative explanation for the dependence of performance and response time on the degree of task difficulty, and the reason for which reaction times are longer in error trials than in correct trials as observed in the monkey experiment. Our reduced two-variable neural model offers a simple yet biophysically plausible framework for studying perceptual decision making in general.

Multialternative drift-diffusion model predicts the relationship between visual fixations and choice in value-based decisions.

PubMed

Krajbich, Ian; Rangel, Antonio

2011-08-16

How do we make decisions when confronted with several alternatives (e.g., on a supermarket shelf)? Previous work has shown that accumulator models, such as the drift-diffusion model, can provide accurate descriptions of the psychometric data for binary value-based choices, and that the choice process is guided by visual attention. However, the computational processes used to make choices in more complicated situations involving three or more options are unknown. We propose a model of trinary value-based choice that generalizes what is known about binary choice, and test it using an eye-tracking experiment. We find that the model provides a quantitatively accurate description of the relationship between choice, reaction time, and visual fixation data using the same parameters that were estimated in previous work on binary choice. Our findings suggest that the brain uses similar computational processes to make binary and trinary choices.

Patient preferences and willingness-to-pay for a home or clinic based program of chronic heart failure management: findings from the Which? trial.

PubMed

Whitty, Jennifer A; Stewart, Simon; Carrington, Melinda J; Calderone, Alicia; Marwick, Thomas; Horowitz, John D; Krum, Henry; Davidson, Patricia M; Macdonald, Peter S; Reid, Christopher; Scuffham, Paul A

2013-01-01

Beyond examining their overall cost-effectiveness and mechanisms of effect, it is important to understand patient preferences for the delivery of different modes of chronic heart failure management programs (CHF-MPs). We elicited patient preferences around the characteristics and willingness-to-pay (WTP) for a clinic or home-based CHF-MP. A Discrete Choice Experiment was completed by a sub-set of patients (n = 91) enrolled in the WHICH? trial comparing home versus clinic-based CHF-MP. Participants provided 5 choices between hypothetical clinic and home-based programs varying by frequency of nurse consultations, nurse continuity, patient costs, and availability of telephone or education support. Participants (aged 71±13 yrs, 72.5% male, 25.3% NYHA class III/IV) displayed two distinct preference classes. A latent class model of the choice data indicated 56% of participants preferred clinic delivery, access to group CHF education classes, and lower cost programs (p<0.05). The remainder preferred home-based CHF-MPs, monthly rather than weekly visits, and access to a phone advice service (p<0.05). Continuity of nurse contact was consistently important. No significant association was observed between program preference and participant allocation in the parent trial. WTP was estimated from the model and a dichotomous bidding technique. For those preferring clinic, estimated WTP was ≈AU$9-20 per visit; however for those preferring home-based programs, WTP varied widely (AU$15-105). Patient preferences for CHF-MPs were dichotomised between a home-based model which is more likely to suit older patients, those who live alone, and those with a lower household income; and a clinic-based model which is more likely to suit those who are more socially active and wealthier. To optimise the delivery of CHF-MPs, health care services should consider their patients' preferences when designing CHF-MPs.

Theoretical study on mode competition between fundamental and second harmonic modes in a 0.42 THz gyrotron with gradually tapered complex cavity

DOE Office of Scientific and Technical Information (OSTI.GOV)

Zhao, Qixiang, E-mail: zxqi1105@gmail.com; Yu, Sheng; Zhang, Tianzhong

2015-10-15

In this paper, the nonlinear dynamics of mode competition in the complex cavity gyrotron are studied by using multi-frequency, time-dependent theory with the cold-cavity longitudinal profile approximation. Based on the theory, a code is written to simulate the mode competition in the gradually tapered complex cavity gyrotron operating at second harmonic oscillation. The simulations tracking seven competition modes show that single mode oscillation of the desired mode TE{sub 17.4} at 150 kW level can be expected with proper choice of operating parameters. Through studying on mode competition, it is proved that the complex cavity has a good capability for suppressing themore » mode competition. Meanwhile, it is found that TE{sub 17.3} could be excited in the first cavity as a competition mode when the gyrotron operating at large beam current, which leads to that TE{sub 17.3} and TE{sub 17.4} with different frequencies can coexist stably in the complex cavity gyrotron with very close amplitudes. Thus, the complex cavity might be used for multi-frequency output gyrotron.« less

A Probabilistic, Dynamic, and Attribute-wise Model of Intertemporal Choice

PubMed Central

Dai, Junyi; Busemeyer, Jerome R.

2014-01-01

Most theoretical and empirical research on intertemporal choice assumes a deterministic and static perspective, leading to the widely adopted delay discounting models. As a form of preferential choice, however, intertemporal choice may be generated by a stochastic process that requires some deliberation time to reach a decision. We conducted three experiments to investigate how choice and decision time varied as a function of manipulations designed to examine the delay duration effect, the common difference effect, and the magnitude effect in intertemporal choice. The results, especially those associated with the delay duration effect, challenged the traditional deterministic and static view and called for alternative approaches. Consequently, various static or dynamic stochastic choice models were explored and fit to the choice data, including alternative-wise models derived from the traditional exponential or hyperbolic discount function and attribute-wise models built upon comparisons of direct or relative differences in money and delay. Furthermore, for the first time, dynamic diffusion models, such as those based on decision field theory, were also fit to the choice and response time data simultaneously. The results revealed that the attribute-wise diffusion model with direct differences, power transformations of objective value and time, and varied diffusion parameter performed the best and could account for all three intertemporal effects. In addition, the empirical relationship between choice proportions and response times was consistent with the prediction of diffusion models and thus favored a stochastic choice process for intertemporal choice that requires some deliberation time to make a decision. PMID:24635188

Market Assessment For Traveler Services, A Choice Modeling Study Phase Iii, Fast-Trac Deliverable, #16B: Final Choice Modeling Report

DOT National Transportation Integrated Search

1999-02-12

FAST-TRAC : THIS REPORT DESCRIBES THE CHOICE MODEL STUDY OF THE FAST-TRAC (FASTER AND SAFER TRAVEL THROUGH TRAFFIC ROUTING AND ADVANCED CONTROLS) OPERATIONAL TEST IN SOUTHEAST MICHIGAN. CHOICE MODELING IS A STATED-PREFERENCE APPROACH IN WHICH RESP...

The Dependent Poisson Race Model and Modeling Dependence in Conjoint Choice Experiments

ERIC Educational Resources Information Center

Ruan, Shiling; MacEachern, Steven N.; Otter, Thomas; Dean, Angela M.

2008-01-01

Conjoint choice experiments are used widely in marketing to study consumer preferences amongst alternative products. We develop a class of choice models, belonging to the class of Poisson race models, that describe a "random utility" which lends itself to a process-based description of choice. The models incorporate a dependence structure which…

Exploring the Positive Utility of Travel and Mode Choice

DOT National Transportation Integrated Search

2017-08-01

Why do people travel? Underlying most travel behavior research is the derived-demand paradigm of travel analysis, which assumes that travel demand is derived from the demand for spatially separated activities, traveling is a means to an end (reaching...

DOE Office of Scientific and Technical Information (OSTI.GOV)

Zhang, Ying-Jie, E-mail: yingjiezhang@qfnu.edu.cn; Han, Wei; Xia, Yun-Jie, E-mail: yjxia@qfnu.edu.cn

We propose a scheme of controlling entanglement dynamics of a quantum system by applying the external classical driving field for two atoms separately located in a single-mode photon cavity. It is shown that, with a judicious choice of the classical-driving strength and the atom–photon detuning, the effective atom–photon interaction Hamiltonian can be switched from Jaynes–Cummings model to anti-Jaynes–Cummings model. By tuning the controllable atom–photon interaction induced by the classical field, we illustrate that the evolution trajectory of the Bell-like entanglement states can be manipulated from entanglement-sudden-death to no-entanglement-sudden-death, from no-entanglement-invariant to entanglement-invariant. Furthermore, the robustness of the initial Bell-like entanglementmore » can be improved by the classical driving field in the leaky cavities. This classical-driving-assisted architecture can be easily extensible to multi-atom quantum system for scalability.« less

iSEDfit: Bayesian spectral energy distribution modeling of galaxies

NASA Astrophysics Data System (ADS)

Moustakas, John

2017-08-01

iSEDfit uses Bayesian inference to extract the physical properties of galaxies from their observed broadband photometric spectral energy distribution (SED). In its default mode, the inputs to iSEDfit are the measured photometry (fluxes and corresponding inverse variances) and a measurement of the galaxy redshift. Alternatively, iSEDfit can be used to estimate photometric redshifts from the input photometry alone. After the priors have been specified, iSEDfit calculates the marginalized posterior probability distributions for the physical parameters of interest, including the stellar mass, star-formation rate, dust content, star formation history, and stellar metallicity. iSEDfit also optionally computes K-corrections and produces multiple "quality assurance" (QA) plots at each stage of the modeling procedure to aid in the interpretation of the prior parameter choices and subsequent fitting results. The software is distributed as part of the impro IDL suite.

Equilibrium dynamical correlations in the Toda chain and other integrable models

NASA Astrophysics Data System (ADS)

Kundu, Aritra; Dhar, Abhishek

2016-12-01

We investigate the form of equilibrium spatiotemporal correlation functions of conserved quantities in the Toda lattice and in other integrable models. From numerical simulations we find that the correlations satisfy ballistic scaling with a remarkable collapse of data from different times. We examine special limiting choices of parameter values, for which the Toda lattice tends to either the harmonic chain or the equal mass hard-particle gas. In both these limiting cases, one can obtain the correlations exactly and we find excellent agreement with the direct Toda simulation results. We also discuss a transformation to "normal mode" variables, as commonly done in hydrodynamic theory of nonintegrable systems, and find that this is useful, to some extent, even for the integrable system. The striking differences between the Toda chain and a truncated version, expected to be nonintegrable, are pointed out.

Equilibrium dynamical correlations in the Toda chain and other integrable models.

PubMed

Kundu, Aritra; Dhar, Abhishek

2016-12-01

We investigate the form of equilibrium spatiotemporal correlation functions of conserved quantities in the Toda lattice and in other integrable models. From numerical simulations we find that the correlations satisfy ballistic scaling with a remarkable collapse of data from different times. We examine special limiting choices of parameter values, for which the Toda lattice tends to either the harmonic chain or the equal mass hard-particle gas. In both these limiting cases, one can obtain the correlations exactly and we find excellent agreement with the direct Toda simulation results. We also discuss a transformation to "normal mode" variables, as commonly done in hydrodynamic theory of nonintegrable systems, and find that this is useful, to some extent, even for the integrable system. The striking differences between the Toda chain and a truncated version, expected to be nonintegrable, are pointed out.

Sliding mode controller with modified sliding function for DC-DC Buck Converter.

PubMed

Naik, B B; Mehta, A J

2017-09-01

This article presents design of Sliding Mode Controller with proportional integral type sliding function for DC-DC Buck Converter for the controlled power supply. The converter with conventional sliding mode controller results in a steady state error in load voltage. The proposed modified sliding function improves the steady state and dynamic performance of the Convertor and facilitates better choices of controller tuning parameters. The conditions for existence of sliding modes for proposed control scheme are derived. The stability of the closed loop system with proposed sliding mode control is proved and improvement in steady state performance is exemplified. The idea of adaptive tuning for the proposed controller to compensate load variations is outlined. The comparative study of conventional and proposed control strategy is presented. The efficacy of the proposed strategy is endowed by the simulation and experimental results. Copyright © 2017 ISA. Published by Elsevier Ltd. All rights reserved.

Mode Propagation in Nonuniform Circular Ducts with Potential Flow

NASA Technical Reports Server (NTRS)

Cho, Y. C.; Ingard, K. U.

1982-01-01

A previously reported closed form solution is expanded to determine effects of isentropic mean flow on mode propagation in a slowly converging-diverging duct, a circular cosh duct. On the assumption of uniform steady fluid density, the mean flow increases the power transmission coefficient. The increase is directly related to the increase of the cutoff ratio at the duct throat. With the negligible transverse gradients of the steady fluid variables, the conversion from one mode to another is negligible, and the power transmission coefficient remains unchanged with the mean flow direction reversed. With a proper choice of frequency parameter, many different modes can be made subject to a single value of the power transmission loss. A systematic method to include the effects of the gradients of the steady fluid variables is also described.

Impact of the neutron detector choice on Bell and Glasstone spatial correction factor for subcriticality measurement

NASA Astrophysics Data System (ADS)

Talamo, Alberto; Gohar, Y.; Cao, Y.; Zhong, Z.; Kiyavitskaya, H.; Bournos, V.; Fokov, Y.; Routkovskaya, C.

2012-03-01

In subcritical assemblies, the Bell and Glasstone spatial correction factor is used to correct the measured reactivity from different detector positions. In addition to the measuring position, several other parameters affect the correction factor: the detector material, the detector size, and the energy-angle distribution of source neutrons. The effective multiplication factor calculated by computer codes in criticality mode slightly differs from the average value obtained from the measurements in the different experimental channels of the subcritical assembly, which are corrected by the Bell and Glasstone spatial correction factor. Generally, this difference is due to (1) neutron counting errors; (2) geometrical imperfections, which are not simulated in the calculational model, and (3) quantities and distributions of material impurities, which are missing from the material definitions. This work examines these issues and it focuses on the detector choice and the calculation methodologies. The work investigated the YALINA Booster subcritical assembly of Belarus, which has been operated with three different fuel enrichments in the fast zone either: high (90%) and medium (36%), medium (36%), or low (21%) enriched uranium fuel.

The power and value of green in promoting sustainable transport behavior

NASA Astrophysics Data System (ADS)

Gaker, David; Vautin, David; Vij, Akshay; Walker, Joan L.

2011-07-01

While it is increasingly popular to broadcast information regarding environmental impact, little is known regarding the effects that this information has on human behavior. This research aims to provide insight into whether, and to what extent, presenting environmental attributes of transport alternatives influences individual transport decisions. We designed and conducted three experiments in which subjects (UC Berkeley undergraduates) were presented with hypothetical scenarios of transport decisions, including auto purchase choice, mode choice, and route choice. We analyzed their decisions via a choice model to determine how they value reducing their emissions relative to other attributes. We found that our subjects are willing to adjust their behavior to reduce emissions, exhibiting an average willingness to pay for emissions reduction, or value of green (VoG), of 15 cents per pound of CO2 saved. Despite concern that people cannot meaningfully process quantities of CO2, we found evidence to the contrary in our subject pool in that the estimated VoG was consistent across context (the wide range of transport decisions that we presented) and presentation (e.g., whether the information was presented in tons or pounds, or whether a social reference point of the emissions of an average person was provided). We also found significant heterogeneity in VoG, with most of the respondents valuing green somewhere between 0 and 70 cents per pound and with women, on average, willing to pay 7 cents more per saved pound than men. While the findings are encouraging, further work is required to determine whether they hold outside of a lab environment and with a more representative pool of subjects.

Asymmetric dynamics of the inner core and impact on the outer core

NASA Astrophysics Data System (ADS)

Alboussière, Thierry; Deguen, Renaud

2012-10-01

The history and present state of knowledge of the dynamics of the inner core are outlined in this paper. The observations that motivated ideas on the dynamical processes are introduced, but the main objective is really to concentrate on the diverse dynamical models that have been and are currently proposed for the formation and evolution of the inner core. A deliberate choice has been made of reproducing key figures from the literature in a didactic attempt to provide clear and quick identification for these models. This review looses impartiality concerning recent models, notably those aiming at explaining the hemispherical asymmetry. A preference for an intrinsic dynamic mode of the inner core is expressed, as opposed to the distant influence of the dynamics of the mantle through heat-flux heterogeneities. Meanwhile, the opinion is conveyed that the dynamics of the inner core is largely not understood yet and that every model must be considered with a critical eye.

Predictors of Latina/o Community College Student Vocational Choice of STEM Fields: Testing of the STEM-Vocational Choice Model

ERIC Educational Resources Information Center

Johnson, Joel D.

2013-01-01

This study confirmed appropriate measurement model fit for a theoretical model, the STEM vocational choice (STEM-VC) model. This model identifies exogenous factors that successfully predicted, at a statistically significant level, a student's vocational choice decision to pursue a STEM degree at transfer. The student population examined for this…

Rigorously testing multialternative decision field theory against random utility models.

PubMed

Berkowitsch, Nicolas A J; Scheibehenne, Benjamin; Rieskamp, Jörg

2014-06-01

Cognitive models of decision making aim to explain the process underlying observed choices. Here, we test a sequential sampling model of decision making, multialternative decision field theory (MDFT; Roe, Busemeyer, & Townsend, 2001), on empirical grounds and compare it against 2 established random utility models of choice: the probit and the logit model. Using a within-subject experimental design, participants in 2 studies repeatedly choose among sets of options (consumer products) described on several attributes. The results of Study 1 showed that all models predicted participants' choices equally well. In Study 2, in which the choice sets were explicitly designed to distinguish the models, MDFT had an advantage in predicting the observed choices. Study 2 further revealed the occurrence of multiple context effects within single participants, indicating an interdependent evaluation of choice options and correlations between different context effects. In sum, the results indicate that sequential sampling models can provide relevant insights into the cognitive process underlying preferential choices and thus can lead to better choice predictions. PsycINFO Database Record (c) 2014 APA, all rights reserved.

Detection of B-mode polarization in the cosmic microwave background with data from the South Pole Telescope.

PubMed

Hanson, D; Hoover, S; Crites, A; Ade, P A R; Aird, K A; Austermann, J E; Beall, J A; Bender, A N; Benson, B A; Bleem, L E; Bock, J J; Carlstrom, J E; Chang, C L; Chiang, H C; Cho, H-M; Conley, A; Crawford, T M; de Haan, T; Dobbs, M A; Everett, W; Gallicchio, J; Gao, J; George, E M; Halverson, N W; Harrington, N; Henning, J W; Hilton, G C; Holder, G P; Holzapfel, W L; Hrubes, J D; Huang, N; Hubmayr, J; Irwin, K D; Keisler, R; Knox, L; Lee, A T; Leitch, E; Li, D; Liang, C; Luong-Van, D; Marsden, G; McMahon, J J; Mehl, J; Meyer, S S; Mocanu, L; Montroy, T E; Natoli, T; Nibarger, J P; Novosad, V; Padin, S; Pryke, C; Reichardt, C L; Ruhl, J E; Saliwanchik, B R; Sayre, J T; Schaffer, K K; Schulz, B; Smecher, G; Stark, A A; Story, K T; Tucker, C; Vanderlinde, K; Vieira, J D; Viero, M P; Wang, G; Yefremenko, V; Zahn, O; Zemcov, M

2013-10-04

Gravitational lensing of the cosmic microwave background generates a curl pattern in the observed polarization. This "B-mode" signal provides a measure of the projected mass distribution over the entire observable Universe and also acts as a contaminant for the measurement of primordial gravity-wave signals. In this Letter we present the first detection of gravitational lensing B modes, using first-season data from the polarization-sensitive receiver on the South Pole Telescope (SPTpol). We construct a template for the lensing B-mode signal by combining E-mode polarization measured by SPTpol with estimates of the lensing potential from a Herschel-SPIRE map of the cosmic infrared background. We compare this template to the B modes measured directly by SPTpol, finding a nonzero correlation at 7.7σ significance. The correlation has an amplitude and scale dependence consistent with theoretical expectations, is robust with respect to analysis choices, and constitutes the first measurement of a powerful cosmological observable.

Correlation between a 2D Channelized Hotelling Observer and Human Observers in a Low-contrast Detection Task with Multi-slice Reading in CT

PubMed Central

Yu, Lifeng; Chen, Baiyu; Kofler, James M.; Favazza, Christopher P.; Leng, Shuai; Kupinski, Matthew A.; McCollough, Cynthia H.

2017-01-01

Purpose Model observers have been successfully developed and used to assess the quality of static 2D CT images. However, radiologists typically read images by paging through multiple 2D slices (i.e. multi-slice reading). The purpose of this study was to correlate human and model observer performance in a low-contrast detection task performed using both 2D and multi-slice reading, and to determine if the 2D model observer still correlate well with human observer performance in multi-slice reading. Methods A phantom containing 18 low-contrast spheres (6 sizes × 3 contrast levels) was scanned on a 192-slice CT scanner at 5 dose levels (CTDIvol = 27, 13.5, 6.8, 3.4, and 1.7 mGy), each repeated 100 times. Images were reconstructed using both filtered-backprojection (FBP) and an iterative reconstruction (IR) method (ADMIRE, Siemens). A 3D volume of interest (VOI) around each sphere was extracted and placed side-by-side with a signal-absent VOI to create a 2-alternative forced choice (2AFC) trial. Sixteen 2AFC studies were generated, each with 100 trials, to evaluate the impact of radiation dose, lesion size and contrast, and reconstruction methods on object detection. In total, 1600 trials were presented to both model and human observers. Three medical physicists acted as human observers and were allowed to page through the 3D volumes to make a decision for each 2AFC trial. The human observer performance was compared with the performance of a multi-slice channelized Hotelling observer (CHO_MS), which integrates multi-slice image data, and with the performance of previously validated CHO, which operates on static 2D images (CHO_2D). For comparison, the same 16 2AFC studies were also performed in a 2D viewing mode by the human observers and compared with the multi-slice viewing performance and the two CHO models. Results Human observer performance was well correlated with the CHO_2D performance in the 2D viewing mode (Pearson product-moment correlation coefficient R=0.972, 95% confidence interval (CI): 0.919 to 0.990) and with the CHO_MS performance in the multi-slice viewing mode (R=0.952, 95% CI: 0.865 to 0.984). The CHO_2D performance, calculated from the 2D viewing mode, also had a strong correlation with human observer performance in the multi-slice viewing mode (R=0.957, 95% CI: 879 to 0.985). Human observer performance varied between the multi-slice and 2D modes. One reader performed better in the multi-slice mode (p=0.013); whereas the other two readers showed no significant difference between the two viewing modes (p=0.057 and p=0.38). Conclusions A 2D CHO model is highly correlated with human observer performance in detecting spherical low contrast objects in multi-slice viewing of CT images. This finding provides some evidence for the use of a simpler, 2D CHO to assess image quality in clinically relevant CT tasks where multi-slice viewing is used. PMID:28555878

Correlation between a 2D channelized Hotelling observer and human observers in a low-contrast detection task with multislice reading in CT.

PubMed

Yu, Lifeng; Chen, Baiyu; Kofler, James M; Favazza, Christopher P; Leng, Shuai; Kupinski, Matthew A; McCollough, Cynthia H

2017-08-01

Model observers have been successfully developed and used to assess the quality of static 2D CT images. However, radiologists typically read images by paging through multiple 2D slices (i.e., multislice reading). The purpose of this study was to correlate human and model observer performance in a low-contrast detection task performed using both 2D and multislice reading, and to determine if the 2D model observer still correlate well with human observer performance in multislice reading. A phantom containing 18 low-contrast spheres (6 sizes × 3 contrast levels) was scanned on a 192-slice CT scanner at five dose levels (CTDI vol = 27, 13.5, 6.8, 3.4, and 1.7 mGy), each repeated 100 times. Images were reconstructed using both filtered-backprojection (FBP) and an iterative reconstruction (IR) method (ADMIRE, Siemens). A 3D volume of interest (VOI) around each sphere was extracted and placed side-by-side with a signal-absent VOI to create a 2-alternative forced choice (2AFC) trial. Sixteen 2AFC studies were generated, each with 100 trials, to evaluate the impact of radiation dose, lesion size and contrast, and reconstruction methods on object detection. In total, 1600 trials were presented to both model and human observers. Three medical physicists acted as human observers and were allowed to page through the 3D volumes to make a decision for each 2AFC trial. The human observer performance was compared with the performance of a multislice channelized Hotelling observer (CHO_MS), which integrates multislice image data, and with the performance of previously validated CHO, which operates on static 2D images (CHO_2D). For comparison, the same 16 2AFC studies were also performed in a 2D viewing mode by the human observers and compared with the multislice viewing performance and the two CHO models. Human observer performance was well correlated with the CHO_2D performance in the 2D viewing mode [Pearson product-moment correlation coefficient R = 0.972, 95% confidence interval (CI): 0.919 to 0.990] and with the CHO_MS performance in the multislice viewing mode (R = 0.952, 95% CI: 0.865 to 0.984). The CHO_2D performance, calculated from the 2D viewing mode, also had a strong correlation with human observer performance in the multislice viewing mode (R = 0.957, 95% CI: 879 to 0.985). Human observer performance varied between the multislice and 2D modes. One reader performed better in the multislice mode (P = 0.013); whereas the other two readers showed no significant difference between the two viewing modes (P = 0.057 and P = 0.38). A 2D CHO model is highly correlated with human observer performance in detecting spherical low contrast objects in multislice viewing of CT images. This finding provides some evidence for the use of a simpler, 2D CHO to assess image quality in clinically relevant CT tasks where multislice viewing is used. © 2017 American Association of Physicists in Medicine.

Modeling and Simulating Passenger Behavior for a Station Closure in a Rail Transit Network

PubMed Central

Yin, Haodong; Han, Baoming; Li, Dewei; Wu, Jianjun; Sun, Huijun

2016-01-01

A station closure is an abnormal operational situation in which the entrances or exits of a rail transit station have to be closed for some time due to an unexpected incident. A novel approach is developed to estimate the impacts of the alternative station closure scenarios on both passenger behavioral choices at the individual level and passenger demand at the disaggregate level in a rail transit network. Therefore, the contributions of this study are two-fold: (1) A basic passenger behavior optimization model is mathematically constructed based on 0–1 integer programming to describe passengers’ responses to alternative origin station closure scenarios and destination station closure scenarios; this model also considers the availability of multi-mode transportation and the uncertain duration of the station closure; (2) An integrated solution algorithm based on the passenger simulation is developed to solve the proposed model and to estimate the effects of a station closure on passenger demand in a rail transit network. Furthermore, 13 groups of numerical experiments based on the Beijing rail transit network are performed as case studies with 2,074,267 records of smart card data. The comparisons of the model outputs and the manual survey show that the accuracy of our proposed behavior optimization model is approximately 80%. The results also show that our model can be used to capture the passenger behavior and to quantitatively estimate the effects of alternative closure scenarios on passenger flow demand for the rail transit network. Moreover, the closure duration and its overestimation greatly influence the individual behavioral choices of the affected passengers and the passenger demand. Furthermore, if the rail transit operator can more accurately estimate the closure duration (namely, as g approaches 1), the impact of the closure can be somewhat mitigated. PMID:27935963

Modeling and Simulating Passenger Behavior for a Station Closure in a Rail Transit Network.

PubMed

Yin, Haodong; Han, Baoming; Li, Dewei; Wu, Jianjun; Sun, Huijun

2016-01-01

A station closure is an abnormal operational situation in which the entrances or exits of a rail transit station have to be closed for some time due to an unexpected incident. A novel approach is developed to estimate the impacts of the alternative station closure scenarios on both passenger behavioral choices at the individual level and passenger demand at the disaggregate level in a rail transit network. Therefore, the contributions of this study are two-fold: (1) A basic passenger behavior optimization model is mathematically constructed based on 0-1 integer programming to describe passengers' responses to alternative origin station closure scenarios and destination station closure scenarios; this model also considers the availability of multi-mode transportation and the uncertain duration of the station closure; (2) An integrated solution algorithm based on the passenger simulation is developed to solve the proposed model and to estimate the effects of a station closure on passenger demand in a rail transit network. Furthermore, 13 groups of numerical experiments based on the Beijing rail transit network are performed as case studies with 2,074,267 records of smart card data. The comparisons of the model outputs and the manual survey show that the accuracy of our proposed behavior optimization model is approximately 80%. The results also show that our model can be used to capture the passenger behavior and to quantitatively estimate the effects of alternative closure scenarios on passenger flow demand for the rail transit network. Moreover, the closure duration and its overestimation greatly influence the individual behavioral choices of the affected passengers and the passenger demand. Furthermore, if the rail transit operator can more accurately estimate the closure duration (namely, as g approaches 1), the impact of the closure can be somewhat mitigated.

Changing resonator geometry to boost sound power decouples size and song frequency in a small insect.

PubMed

Mhatre, Natasha; Montealegre-Z, Fernando; Balakrishnan, Rohini; Robert, Daniel

2012-05-29

Despite their small size, some insects, such as crickets, can produce high amplitude mating songs by rubbing their wings together. By exploiting structural resonance for sound radiation, crickets broadcast species-specific songs at a sharply tuned frequency. Such songs enhance the range of signal transmission, contain information about the signaler's quality, and allow mate choice. The production of pure tones requires elaborate structural mechanisms that control and sustain resonance at the species-specific frequency. Tree crickets differ sharply from this scheme. Although they use a resonant system to produce sound, tree crickets can produce high amplitude songs at different frequencies, varying by as much as an octave. Based on an investigation of the driving mechanism and the resonant system, using laser Doppler vibrometry and finite element modeling, we show that it is the distinctive geometry of the crickets' forewings (the resonant system) that is responsible for their capacity to vary frequency. The long, enlarged wings enable the production of high amplitude songs; however, as a mechanical consequence of the high aspect ratio, the resonant structures have multiple resonant modes that are similar in frequency. The drive produced by the singing apparatus cannot, therefore, be locked to a single frequency, and different resonant modes can easily be engaged, allowing individual males to vary the carrier frequency of their songs. Such flexibility in sound production, decoupling body size and song frequency, has important implications for conventional views of mate choice, and offers inspiration for the design of miniature, multifrequency, resonant acoustic radiators.

Evaluating the impact of Mobike on automobile-involved bicycle crashes at the road network level.

PubMed

Li, Ye; Xing, Lu; Wang, Wei; Liang, Mingzhang; Wang, Hao

2018-03-01

As a booming system, free-floating bicycle-sharing (denoted as Mobike) attracts a large number of users due to the convenient utilization procedure. However, it brings about a rapid increase of bicycle volume on roadways, resulting in safety problems especially on road segments shared by automobiles and bikes. This study aimed to evaluate impacts of Mobike on automobile-involved bicycle crashes on shared roadways at a macro level, the network level. Relation between traffic volumes and crashes was first established. Then, the travel mode choice before and after supplying Mobike in the market was analyzed, based on which the multi-class multi-modal user equilibrium (MMUE) models were formulated and solved. Two attributes of Mobike, supply quantity and fare, were investigated via various scenarios. Results suggested the Mobike attracted more walkers than auto-users in travel mode choices, which caused the volume increase of bicycles but few volume decline of automobiles and resulted in more crashes. The supply quantity of Mobike had a negative impact on safety, while the fare had a positive effect. The total supply of Mobike in the market should be regulated by governments to avoid over-supply and reduce bicycle crashes. The fares should be also regulated by including taxes and insurances, which can be used to build up more separated bicycle facilities and cover the Mobike accidents, respectively. The findings of this study provide useful information for governments and urban transportation managers to improve bicycle safety and regulate the Mobike market. Copyright © 2018 Elsevier Ltd. All rights reserved.

Effects of on-street parking on cyclist route choice and the operational behavior of cyclists and motorists.

DOT National Transportation Integrated Search

2009-04-01

Because of the serious societal, environmental, economic, and public health problems associated with motorized : transportation, there is increased interest in encouraging non-motorized modes of travel. The current study contributes toward this : obj...

Stated choice for transportation demand management models : using a disaggregate truth set to study predictive validity

DOT National Transportation Integrated Search

1997-01-01

Discrete choice models have expanded the ability of transportation planners to forecast future trends. Where new services or policies are proposed, the stated-choice approach can provide an objective basis for forecasts. Stated-choice models are subj...

Predictive Genetic Testing and Alternatives to Face to Face Results Disclosure: A Retrospective Review of Patients Preference for Alternative Modes of BRCA 1 and 2 Results Disclosure in the Republic of Ireland.

PubMed

O'Shea, Rosie; Meany, Marie; Carroll, Cliona; Cody, Nuala; Healy, David; Green, Andrew; Lynch, Sally Ann

2016-06-01

The traditional model of providing cancer predictive testing services is changing. Many genetic centres are now offering a choice to patients in how they receive their results instead of the typical face-to-face disclosure. In view of this shift in practice and the increasing demand on the ROI cancer predictive testing service, a 2 year retrospective study on patient preference in how to receive a Breast Cancer (BRCA) predictive result was carried out. Results showed that 71.7 % of respondents would have liked to have the option of obtaining their results by telephone or by letter. However, when asked about their actual experience of BRCA predictive results disclosure 40.6 % did still value the face-to-face contact, while 44.9 % would still have preferred to receive results by either post or telephone. No significant difference was found between males and females (p > 0.05) and those who tested negative or positive for the BRCA mutation (p > 0.05) in wanting a choice in how their results were disclosed. While the majority expressed a wish to have a choice in how to receive their results, it is important not to underestimate the value of a face-to-face encounter in these circumstances.

Should pantomime and gesticulation be assessed separately for their comprehensibility in aphasia? A case study.

PubMed

van Nispen, Karin; van de Sandt-Koenderman, Mieke; Mol, Lisette; Krahmer, Emiel

2014-01-01

Gesticulation (gestures accompanying speech) and pantomime (gestures in the absence of speech) can each be comprehensible. Little is known about the differences between these two gesture modes in people with aphasia. To discover whether there are differences in the communicative use of gesticulation and pantomime in QH, a person with severe fluent aphasia. QH performed two tasks: naming objects and retelling a story. He did this once in a verbal condition (enabling gesticulation) and once in a pantomime condition. For both conditions, the comprehensibility of gestures was analysed in a forced-choice task by naïve judges. Secondly, a comparison was made between QH and healthy controls for the representation techniques used. Pantomimes produced by QH for naming objects were significantly more comprehensible than chance, whereas his gesticulation was not. For retelling a story the opposite pattern was found. When naming objects QH gesticulated much more than did healthy controls. His pantomimes for this task were simpler than those used by the control group. For retelling a story no differences were found. Although QH did not make full use of each gesture modes' potential, both did contribute to QH's comprehensibility. Crucially, the benefits of each mode differed across tasks. This implies that both gesture modes should be taken into account separately in models of speech and gesture production and in clinical practice for different communicative settings. © 2013 Royal College of Speech and Language Therapists.

[Lung protective ventilation. Ventilatory modes and ventilator parameters].

PubMed

Schädler, Dirk; Weiler, Norbert

2008-06-01

Mechanical ventilation has a considerable potential for injuring the lung tissue. Therefore, attention has to be paid to the proper choice of ventilatory mode and settings to secure lung-protective ventilation whenever possible. Such ventilator strategy should account for low tidal volume ventilation (6 ml/kg PBW), limited plateau pressure (30 to 35 cm H2O) and positive end-expiratory pressure (PEEP). It is unclear whether pressure controlled or volume controlled ventilation with square flow profile is beneficial. The adjustment of inspiration and expiration time should consider the actual breathing mechanics and anticipate the generation of intrinsic PEEP. Ventilatory modes with the possibility of supporting spontaneous breathing should be used as soon as possible.

Adapting TESLA technology for future cw light sources using HoBiCaT

NASA Astrophysics Data System (ADS)

Kugeler, O.; Neumann, A.; Anders, W.; Knobloch, J.

2010-07-01

The HoBiCaT facility has been set up and operated at the Helmholtz-Zentrum-Berlin and BESSY since 2005. Its purpose is testing superconducting cavities in cw mode of operation and it was successfully demonstrated that TESLA pulsed technology can be used for cw mode of operation with only minor changes. Issues that were addressed comprise of elevated dynamic thermal losses in the cavity walls, necessary modifications in the cryogenics and the cavity processing, the optimum choice of operational parameters such as cavity temperature or bandwidth, the characterization of higher order modes in the cavity, and the usability of existing tuners and couplers for cw.

Formal language constrained path problems

DOE Office of Scientific and Technical Information (OSTI.GOV)

Barrett, C.; Jacob, R.; Marathe, M.

1997-07-08

In many path finding problems arising in practice, certain patterns of edge/vertex labels in the labeled graph being traversed are allowed/preferred, while others are disallowed. Motivated by such applications as intermodal transportation planning, the authors investigate the complexity of finding feasible paths in a labeled network, where the mode choice for each traveler is specified by a formal language. The main contributions of this paper include the following: (1) the authors show that the problem of finding a shortest path between a source and destination for a traveler whose mode choice is specified as a context free language is solvablemore » efficiently in polynomial time, when the mode choice is specified as a regular language they provide algorithms with improved space and time bounds; (2) in contrast, they show that the problem of finding simple paths between a source and a given destination is NP-hard, even when restricted to very simple regular expressions and/or very simple graphs; (3) for the class of treewidth bounded graphs, they show that (i) the problem of finding a regular language constrained simple path between source and a destination is solvable in polynomial time and (ii) the extension to finding context free language constrained simple paths is NP-complete. Several extensions of these results are presented in the context of finding shortest paths with additional constraints. These results significantly extend the results in [MW95]. As a corollary of the results, they obtain a polynomial time algorithm for the BEST k-SIMILAR PATH problem studied in [SJB97]. The previous best algorithm was given by [SJB97] and takes exponential time in the worst case.« less

Sequential and simultaneous choices: testing the diet selection and sequential choice models.

PubMed

Freidin, Esteban; Aw, Justine; Kacelnik, Alex

2009-03-01

We investigate simultaneous and sequential choices in starlings, using Charnov's Diet Choice Model (DCM) and Shapiro, Siller and Kacelnik's Sequential Choice Model (SCM) to integrate function and mechanism. During a training phase, starlings encountered one food-related option per trial (A, B or R) in random sequence and with equal probability. A and B delivered food rewards after programmed delays (shorter for A), while R ('rejection') moved directly to the next trial without reward. In this phase we measured latencies to respond. In a later, choice, phase, birds encountered the pairs A-B, A-R and B-R, the first implementing a simultaneous choice and the second and third sequential choices. The DCM predicts when R should be chosen to maximize intake rate, and SCM uses latencies of the training phase to predict choices between any pair of options in the choice phase. The predictions of both models coincided, and both successfully predicted the birds' preferences. The DCM does not deal with partial preferences, while the SCM does, and experimental results were strongly correlated to this model's predictions. We believe that the SCM may expose a very general mechanism of animal choice, and that its wider domain of success reflects the greater ecological significance of sequential over simultaneous choices.

Modeling of a sensitive time-of-flight flash LiDAR system

NASA Astrophysics Data System (ADS)

Fathipour, V.; Wheaton, S.; Johnson, W. E.; Mohseni, H.

2016-09-01

used for monitoring and profiling structures, range, velocity, vibration, and air turbulence. Remote sensing in the IR region has several advantages over the visible region, including higher transmitter energy while maintaining eye-safety requirements. Electron-injection detectors are a new class of detectors with high internal avalanche-free amplification together with an excess-noise-factor of unity. They have a cutoff wavelength of 1700 nm. Furthermore, they have an extremely low jitter. The detector operates in linear-mode and requires only bias voltage of a few volts. This together with the feedback stabilized gain mechanism, makes formation of large-format high pixel density electron-injection FPAs less challenging compared to other detector technologies such as avalanche photodetectors. These characteristics make electron-injection detectors an ideal choice for flash LiDAR application with mm scale resolution at longer ranges. Based on our experimentally measured device characteristics, a detailed theoretical LiDAR model was developed. In this model we compare the performance of the electron-injection detector with commercially available linear-mode InGaAs APD from (Hamamatsu G8931-20) as well as a p-i-n diode (Hamamatsu 11193 p-i-n). Flash LiDAR images obtained by our model, show the electron-injection detector array (of 100 x 100 element) achieves better resolution with higher signal-to-noise compared with both the InGaAs APD and the p-i-n array (of 100 x 100 element).

The evolution of mate choice: a dialogue between theory and experiment.

PubMed

Roff, Derek A

2015-12-01

Research on the evolution of mate choice has followed three avenues of investigation: (1) theoretical models of the evolution of preference and the preferred trait; (2) proposed models of mate choice; and (3) experiments and observations on mate choice, both in the laboratory and with free-ranging animals. However, there has been relatively little dialogue among these three areas. Most attempts to account for observations of mate choice using theoretical mate-choice models have focused only upon a subset of particular models and have generally failed to consider the difference between probabilistic and deterministic models. In this review, I outline the underlying reasoning of the commonly cited mate-choice models and review the conclusions of the empirical investigations. I present a brief outline of how one might go about testing these models. It remains uncertain if, in general, mate-choice models can be realistically analyzed. Although it is clear that females frequently discriminate among males, data also suggest that females may typically have a very limited number of males from which to choose. The extent to which female choice under natural conditions is relatively random because of limited opportunities remains an open question for the majority of species. © 2015 New York Academy of Sciences.

A review of micro-contact physics for microelectromechanical systems (MEMS) metal contact switches

NASA Astrophysics Data System (ADS)

Toler, Benjamin F.; Coutu, Ronald A., Jr.; McBride, John W.

2013-10-01

Innovations in relevant micro-contact areas are highlighted, these include, design, contact resistance modeling, contact materials, performance and reliability. For each area the basic theory and relevant innovations are explored. A brief comparison of actuation methods is provided to show why electrostatic actuation is most commonly used by radio frequency microelectromechanical systems designers. An examination of the important characteristics of the contact interface such as modeling and material choice is discussed. Micro-contact resistance models based on plastic, elastic-plastic and elastic deformations are reviewed. Much of the modeling for metal contact micro-switches centers around contact area and surface roughness. Surface roughness and its effect on contact area is stressed when considering micro-contact resistance modeling. Finite element models and various approaches for describing surface roughness are compared. Different contact materials to include gold, gold alloys, carbon nanotubes, composite gold-carbon nanotubes, ruthenium, ruthenium oxide, as well as tungsten have been shown to enhance contact performance and reliability with distinct trade offs for each. Finally, a review of physical and electrical failure modes witnessed by researchers are detailed and examined.

Overview of experiment design and comparison of models participating in phase 1 of the SPARC Quasi-Biennial Oscillation initiative (QBOi)

NASA Astrophysics Data System (ADS)

Butchart, Neal; Anstey, James A.; Hamilton, Kevin; Osprey, Scott; McLandress, Charles; Bushell, Andrew C.; Kawatani, Yoshio; Kim, Young-Ha; Lott, Francois; Scinocca, John; Stockdale, Timothy N.; Andrews, Martin; Bellprat, Omar; Braesicke, Peter; Cagnazzo, Chiara; Chen, Chih-Chieh; Chun, Hye-Yeong; Dobrynin, Mikhail; Garcia, Rolando R.; Garcia-Serrano, Javier; Gray, Lesley J.; Holt, Laura; Kerzenmacher, Tobias; Naoe, Hiroaki; Pohlmann, Holger; Richter, Jadwiga H.; Scaife, Adam A.; Schenzinger, Verena; Serva, Federico; Versick, Stefan; Watanabe, Shingo; Yoshida, Kohei; Yukimoto, Seiji

2018-03-01

The Stratosphere-troposphere Processes And their Role in Climate (SPARC) Quasi-Biennial Oscillation initiative (QBOi) aims to improve the fidelity of tropical stratospheric variability in general circulation and Earth system models by conducting coordinated numerical experiments and analysis. In the equatorial stratosphere, the QBO is the most conspicuous mode of variability. Five coordinated experiments have therefore been designed to (i) evaluate and compare the verisimilitude of modelled QBOs under present-day conditions, (ii) identify robustness (or alternatively the spread and uncertainty) in the simulated QBO response to commonly imposed changes in model climate forcings (e.g. a doubling of CO2 amounts), and (iii) examine model dependence of QBO predictability. This paper documents these experiments and the recommended output diagnostics. The rationale behind the experimental design and choice of diagnostics is presented. To facilitate scientific interpretation of the results in other planned QBOi studies, consistent descriptions of the models performing each experiment set are given, with those aspects particularly relevant for simulating the QBO tabulated for easy comparison.

Squeezing in a 2-D generalized oscillator

NASA Technical Reports Server (NTRS)

Castanos, Octavio; Lopez-Pena, Ramon; Manko, Vladimir I.

1994-01-01

A two-dimensional generalized oscillator with time-dependent parameters is considered to study the two-mode squeezing phenomena. Specific choices of the parameters are used to determine the dispersion matrix and analytic expressions, in terms of standard hermite polynomials, of the wavefunctions and photon distributions.

Impact of passenger transportation modes, travel choices, and urban geography on CO2 emissions.

DOT National Transportation Integrated Search

2017-01-23

The contributions of this study are twofold. First, the impacts of changes in the various travel related, population density, and policy variables on CO2 emissions are quantified. Second, the implications of these quantifications on policy-making are...

Estimation of Local Orientations in Fibrous Structures With Applications to the Purkinje System

PubMed Central

Plank, Gernot; Trayanova, Natalia A.; Vidal, René

2011-01-01

The extraction of the cardiac Purkinje system (PS) from intensity images is a critical step toward the development of realistic structural models of the heart. Such models are important for uncovering the mechanisms of cardiac disease and improving its treatment and prevention. Unfortunately, the manual extraction of the PS is a challenging and error-prone task due to the presence of image noise and numerous fiber junctions. To deal with these challenges, we propose a framework that estimates local fiber orientations with high accuracy and reconstructs the fibers via tracking. Our key contribution is the development of a descriptor for estimating the orientation distribution function (ODF), a spherical function encoding the local geometry of the fibers at a point of interest. The fiber/branch orientations are identified as the modes of the ODFs via spherical clustering and guide the extraction of the fiber centerlines. Experiments on synthetic data evaluate the sensitivity of our approach to image noise, width of the fiber, and choice of the mode detection strategy, and show its superior performance compared to those of the existing descriptors. Experiments on the free-running PS in an MR image also demonstrate the accuracy of our method in reconstructing such sparse fibrous structures. PMID:21335301

Utility-free heuristic models of two-option choice can mimic predictions of utility-stage models under many conditions

PubMed Central

Piantadosi, Steven T.; Hayden, Benjamin Y.

2015-01-01

Economists often model choices as if decision-makers assign each option a scalar value variable, known as utility, and then select the option with the highest utility. It remains unclear whether as-if utility models describe real mental and neural steps in choice. Although choices alone cannot prove the existence of a utility stage, utility transformations are often taken to provide the most parsimonious or psychologically plausible explanation for choice data. Here, we show that it is possible to mathematically transform a large set of common utility-stage two-option choice models (specifically ones in which dimensions are can be decomposed into additive functions) into a heuristic model (specifically, a dimensional prioritization heuristic) that has no utility computation stage. We then show that under a range of plausible assumptions, both classes of model predict similar neural responses. These results highlight the difficulties in using neuroeconomic data to infer the existence of a value stage in choice. PMID:25914613

A Conditional Curie-Weiss Model for Stylized Multi-group Binary Choice with Social Interaction

NASA Astrophysics Data System (ADS)

Opoku, Alex Akwasi; Edusei, Kwame Owusu; Ansah, Richard Kwame

2018-04-01

This paper proposes a conditional Curie-Weiss model as a model for decision making in a stylized society made up of binary decision makers that face a particular dichotomous choice between two options. Following Brock and Durlauf (Discrete choice with social interaction I: theory, 1955), we set-up both socio-economic and statistical mechanical models for the choice problem. We point out when both the socio-economic and statistical mechanical models give rise to the same self-consistent equilibrium mean choice level(s). Phase diagram of the associated statistical mechanical model and its socio-economic implications are discussed.

Choices and changes: Eccles' Expectancy-Value model and upper-secondary school students' longitudinal reflections about their choice of a STEM education

NASA Astrophysics Data System (ADS)

Lykkegaard, Eva; Ulriksen, Lars

2016-03-01

During the past 30 years, Eccles' comprehensive social-psychological Expectancy-Value Model of Motivated Behavioural Choices (EV-MBC model) has been proven suitable for studying educational choices related to Science, Technology, Engineering and/or Mathematics (STEM). The reflections of 15 students in their last year in upper-secondary school concerning their choice of tertiary education were examined using quantitative EV-MBC surveys and repeated qualitative interviews. This article presents the analyses of three cases in detail. The analytical focus was whether the factors indicated in the EV-MBC model could be used to detect significant changes in the students' educational choice processes. An important finding was that the quantitative EV-MBC surveys and the qualitative interviews gave quite different results concerning the students' considerations about the choice of tertiary education, and that significant changes in the students' reflections were not captured by the factors of the EV-MBC model. This questions the validity of the EV-MBC surveys. Moreover, the quantitative factors from the EV-MBC model did not sufficiently explain students' dynamical educational choice processes where students in parallel considered several different potential educational trajectories. We therefore call for further studies of the EV-MBC model's use in describing longitudinal choice processes and especially in investigating significant changes.

Engineering long term clinical success of advanced ceramic prostheses.

PubMed

Rekow, Dianne; Thompson, Van P

2007-01-01

Biocompatability and, in some applications, esthetics make all-ceramic prostheses compelling choices but despite significant improvements in materials properties and toughening mechanisms, these still have significant failure rates. Factors that contribute to the degradation in strength and survival include material selection and prosthesis design which set the upper limit for performance. However, fabrication operations introduce damage that can be exacerbated by environmental conditions and clinical function. Using all-ceramic dental crowns as an example, experimentally derived models provide insight into the relationships between materials properties and initial critical loads to failure. Analysis of fabrication operations suggests strategies to minimize damage. Environmental conditions can create viscoplastic flow of supporting components which can contribute additional stress within the prosthesis. Fatigue is a particularly challenging problem, not only providing the energy to propagate existing damage but, when combined with the wet environment, can create new damage modes. While much is known, the influence of these new damage modes has not been completely elucidated. The role of complex prosthesis geometry and its interaction with other factors on damage initiation and propagation has yet to be well characterized.

Infrastructure for the design and fabrication of MEMS for RF/microwave and millimeter wave applications

NASA Astrophysics Data System (ADS)

Nerguizian, Vahe; Rafaf, Mustapha

2004-08-01

This article describes and provides valuable information for companies and universities with strategies to start fabricating MEMS for RF/Microwave and millimeter wave applications. The present work shows the infrastructure developed for RF/Microwave and millimeter wave MEMS platforms, which helps the identification, evaluation and selection of design tools and fabrication foundries taking into account packaging and testing. The selected and implemented simple infrastructure models, based on surface and bulk micromachining, yield inexpensive and innovative approaches for distributed choices of MEMS operating tools. With different educational or industrial institution needs, these models may be modified for specific resource changes using a careful analyzed iteration process. The inputs of the project are evaluation selection criteria and information sources such as financial, technical, availability, accessibility, simplicity, versatility and practical considerations. The outputs of the project are the selection of different MEMS design tools or software (solid modeling, electrostatic/electromagnetic and others, compatible with existing standard RF/Microwave design tools) and different MEMS manufacturing foundries. Typical RF/Microwave and millimeter wave MEMS solutions are introduced on the platform during the evaluation and development phases of the project for the validation of realistic results and operational decision making choices. The encountered challenges during the investigation and the development steps are identified and the dynamic behavior of the infrastructure is emphasized. The inputs (resources) and the outputs (demonstrated solutions) are presented in tables and flow chart mode diagrams.

Vocational Choice: A Decision Making Perspective

ERIC Educational Resources Information Center

Sauermann, Henry

2005-01-01

We propose a model of vocational choice that can be used for analyzing and guiding the decision processes underlying career and job choices. Our model is based on research in behavioral decision making (BDM), in particular the choice goals framework developed by Bettman, Luce, and Payne (1998). The basic model involves two major processes. First,…

The emerging dental workforce: why dentistry? A quantitative study of final year dental students' views on their professional career

PubMed Central

Gallagher, Jennifer E; Patel, Resmi; Donaldson, Nora; Wilson, Nairn HF

2007-01-01

Background Dental graduates are joining a profession experiencing changes in systems of care, funding and skill mix. Research into the motivation and expectations of the emerging workforce is vital to inform professional and policy decisions. The objective of this research was to investigate final year dental students' perceived motivation for their choice of career in relation to sex, ethnicity and mode of entry. Methods Self-administered questionnaire survey of all final year dental students at King's College London. Data were entered into SPSS; statistical analysis included Chi Squared tests for linear association, multiple regression, factor analysis and logistic regression. Results A response of 90% (n = 126) was achieved. The majority were aged 23 years (59%), female (58%) and Asian (70%). One in 10 were mature students. Eighty per cent identified 11 or more 'important' or 'very important' influences, the most common of which were related to features of the job: 'regular working hours' (91%), 'degree leading to recognised job' (90%) and 'job security' (90%). There were significant differences in important influences by sex (males > females: 'able to run own business'; females > males: 'a desire to work with people'), ethnic group (Asians > white: 'wish to provide public service', 'influence of friends', 'desire to work in healthcare', having 'tried an alternative career/course' and 'work experience') and mode of entry (mature > early entry: 'a desire to work with people'). Multivariate analysis suggested 61% of the variation in influences is explained by five factors: the 'professional job' (31%), 'healthcare-people' (11%), 'academic-scientific' (8%), 'careers-advising' (6%), and 'family/friends' (6%). The single major influence on choice of career was a 'desire to work with people'; Indian students were twice as likely to report this as white or other ethnic groups. Conclusion Final year dental students report a wide range of important influences on their choice of dentistry, with variation by sex, ethnicity and mode of entry in relation to individual influences. Features of the 'professional job', followed by 'healthcare and people' were the most important underlying factors influencing choice of career. PMID:17573967

Impact of Retirement Choices of Early Career Marines: A Choice Analysis Model

DTIC Science & Technology

2013-03-01

CHOICES OF EARLY CAREER MARINES: A CHOICE ANALYSIS MODEL by André G. La Taste Aaron Masaitis March 2013 Thesis Advisor: Michael Dixon... ANALYSIS MODEL 5. FUNDING NUMBERS 6. AUTHOR(S) André G. La Taste, Aaron Masaitis 7. PERFORMING ORGANIZATION NAME(S) AND ADDRESS(ES) Naval Postgraduate...system. The research will be conducted using a discrete choice analysis methodology that is often used to differentiate factors that lead to

Ambush frequency should increase over time during optimal predator search for prey

PubMed Central

Alpern, Steve; Fokkink, Robbert; Timmer, Marco; Casas, Jérôme

2011-01-01

We advance and apply the mathematical theory of search games to model the problem faced by a predator searching for prey. Two search modes are available: ambush and cruising search. Some species can adopt either mode, with their choice at a given time traditionally explained in terms of varying habitat and physiological conditions. We present an additional explanation of the observed predator alternation between these search modes, which is based on the dynamical nature of the search game they are playing: the possibility of ambush decreases the propensity of the prey to frequently change locations and thereby renders it more susceptible to the systematic cruising search portion of the strategy. This heuristic explanation is supported by showing that in a new idealized search game where the predator is allowed to ambush or search at any time, and the prey can change locations at intermittent times, optimal predator play requires an alternation (or mixture) over time of ambush and cruise search. Thus, our game is an extension of the well-studied ‘Princess and Monster’ search game. Search games are zero sum games, where the pay-off is the capture time and neither the Searcher nor the Hider knows the location of the other. We are able to determine the optimal mixture of the search modes when the predator uses a mixture which is constant over time, and also to determine how the mode mixture changes over time when dynamic strategies are allowed (the ambush probability increases over time). In particular, we establish the ‘square root law of search predation’: the optimal proportion of active search equals the square root of the fraction of the region that has not yet been explored. PMID:21571944

Proper source-receiver distance to obtain surface wave group velocity profile for flaw detection inside a concrete plate-like structure

NASA Astrophysics Data System (ADS)

Cheng, Chia-Chi; Hsu, Keng-Tsang; Wang, Hong-Hua; Chiang, Chih-Hung

2018-04-01

A technique leads to rapid flaw detection for concrete plate-like structure is realized by obtaining the group velocity dispersion profile of the fundamental antisymmetric mode of the plate (A0 mode). The depth of a delaminating crack, honeycomb or depth of weak surface layer on top of the sound concrete can all be evaluated by the change of velocity in the dispersion profile of A0 mode at the wavelength about twice of the depth. The testing method involves obtaining the A0 group slowness spectrogram produced by single test with one receiver placed away from the source of impact. The image of the spectrogram is obtained by Short-Time Fourier Transfer (STFT) and enhanced by reassigned method. The choice of window length in STFT and the ratio between impactor-receiver distance and plate thickness, d/T, is essential as the dominant surface wave response may simply a non-dispersive Rayleigh wave or following the A0 or S0 (fundamental symmetric mode) modal dispersion curve. In this study, the axisymmetric finite element model of a plate subject to transient load was constructed. The nodal vertical velocity waveforms for various distances were analyzed using various STFT window lengths. The results show, for certain d/T ratio, S0 mode would be dominant when longer window is used. The best window lengths for a d/T ratio as well as the corresponding largest wavelength which follows the A0 theoretical dispersion curve or Rayleigh wave were summarized. The information allows people to determine the proper impactor-receiver distance and analyzing window to successfully detect the depth of flaws inside a plate.

Ambush frequency should increase over time during optimal predator search for prey.

PubMed

Alpern, Steve; Fokkink, Robbert; Timmer, Marco; Casas, Jérôme

2011-11-07

We advance and apply the mathematical theory of search games to model the problem faced by a predator searching for prey. Two search modes are available: ambush and cruising search. Some species can adopt either mode, with their choice at a given time traditionally explained in terms of varying habitat and physiological conditions. We present an additional explanation of the observed predator alternation between these search modes, which is based on the dynamical nature of the search game they are playing: the possibility of ambush decreases the propensity of the prey to frequently change locations and thereby renders it more susceptible to the systematic cruising search portion of the strategy. This heuristic explanation is supported by showing that in a new idealized search game where the predator is allowed to ambush or search at any time, and the prey can change locations at intermittent times, optimal predator play requires an alternation (or mixture) over time of ambush and cruise search. Thus, our game is an extension of the well-studied 'Princess and Monster' search game. Search games are zero sum games, where the pay-off is the capture time and neither the Searcher nor the Hider knows the location of the other. We are able to determine the optimal mixture of the search modes when the predator uses a mixture which is constant over time, and also to determine how the mode mixture changes over time when dynamic strategies are allowed (the ambush probability increases over time). In particular, we establish the 'square root law of search predation': the optimal proportion of active search equals the square root of the fraction of the region that has not yet been explored.

Comparison of response patterns in different survey designs: a longitudinal panel with mixed-mode and online-only design.

PubMed

Rübsamen, Nicole; Akmatov, Manas K; Castell, Stefanie; Karch, André; Mikolajczyk, Rafael T

2017-01-01

Increasing availability of the Internet allows using only online data collection for more epidemiological studies. We compare response patterns in a population-based health survey using two survey designs: mixed-mode (choice between paper-and-pencil and online questionnaires) and online-only design (without choice). We used data from a longitudinal panel, the Hygiene and Behaviour Infectious Diseases Study (HaBIDS), conducted in 2014/2015 in four regions in Lower Saxony, Germany. Individuals were recruited using address-based probability sampling. In two regions, individuals could choose between paper-and-pencil and online questionnaires. In the other two regions, individuals were offered online-only participation. We compared sociodemographic characteristics of respondents who filled in all panel questionnaires between the mixed-mode group (n = 1110) and the online-only group (n = 482). Using 134 items, we performed multinomial logistic regression to compare responses between survey designs in terms of type (missing, "do not know" or valid response) and ordinal regression to compare responses in terms of content. We applied the false discovery rates (FDR) to control for multiple testing and investigated effects of adjusting for sociodemographic characteristic. For validation of the differential response patterns between mixed-mode and online-only, we compared the response patterns between paper and online mode among the respondents in the mixed-mode group in one region (n = 786). Respondents in the online-only group were older than those in the mixed-mode group, but both groups did not differ regarding sex or education. Type of response did not differ between the online-only and the mixed-mode group. Survey design was associated with different content of response in 18 of the 134 investigated items; which decreased to 11 after adjusting for sociodemographic variables. In the validation within the mixed-mode, only two of those were among the 11 significantly different items. The probability of observing by chance the same two or more significant differences in this setting was 22%. We found similar response patterns in both survey designs with only few items being answered differently, likely attributable to chance. Our study supports the equivalence of the compared survey designs and suggests that, in the studied setting, using online-only design does not cause strong distortion of the results.

Parametric Flutter Analysis of the TCA Configuration and Recommendation for FFM Design and Scaling

NASA Technical Reports Server (NTRS)

Baker, Myles; Lenkey, Peter

1997-01-01

The current HSR Aeroelasticity plan to design, build, and test a full span, free flying transonic flutter model in the TDT has many technical obstacles that must be overcome for a successful program. One technical obstacle is the determination of a suitable configuration and point in the sky to use in setting the scaling point for the ASE models program. Determining this configuration and point in the sky requires balancing several conflicting requirements, including model buildability, tunnel test safety, and the ability of the model to represent the flutter mechanisms of interest. As will be discussed in detail in subsequent sections, the current TCA design exhibits several flutter mechanisms of interest. It has been decided that the ASE models program will focus on the low frequency symmetric flutter mechanism, and will make no attempt to investigate high frequency flutter mechanisms. There are several reasons for this choice. First, it is believed that the high frequency flutter mechanisms are similar in nature to classical wing bending/torsion flutter, and therefore there is more confidence that this mechanism can be predicted using current techniques. The low frequency mode, on the other hand, is a highly coupled mechanism involving wing, body, tail, and engine motion which may be very difficult to predict. Second, the high frequency flutter modes result in very small weight penalties (several hundred pounds), while suppression of the low frequency mechanism inside the flight envelope causes thousands of pounds to be added to the structure. In order to successfully test the low frequency flutter mode of interest, a suitable starting configuration and point in the sky must be identified. The configuration and point in the sky must result in a wind tunnel model that (1) represents the low-frequency wing/body/engine/empennage flutter mechanisms that are unique to HSCT configurations, (2) flutters at an acceptably low frequency in the tunnel, (3) flutters at an acceptably low dynamic pressure in the tunnel, (4) allows sufficient weight for model buildability without inordinately high cost, and (5) has significant separation between the target flutter mechanism and other, potentially catastrophic, flutter mechanisms.

Probabilistic choice models in health-state valuation research: background, theories, assumptions and applications.

PubMed

Arons, Alexander M M; Krabbe, Paul F M

2013-02-01

Interest is rising in measuring subjective health outcomes, such as treatment outcomes that are not directly quantifiable (functional disability, symptoms, complaints, side effects and health-related quality of life). Health economists in particular have applied probabilistic choice models in the area of health evaluation. They increasingly use discrete choice models based on random utility theory to derive values for healthcare goods or services. Recent attempts have been made to use discrete choice models as an alternative method to derive values for health states. In this article, various probabilistic choice models are described according to their underlying theory. A historical overview traces their development and applications in diverse fields. The discussion highlights some theoretical and technical aspects of the choice models and their similarity and dissimilarity. The objective of the article is to elucidate the position of each model and their applications for health-state valuation.

Review of "Foundations of Social Theory," by James S. Coleman.

ERIC Educational Resources Information Center

Gibbs, Jack P.

1990-01-01

Suggests that this book is a major contribution to sociology and that its greatest (and most controversial) merit is its insistence that sociological macrovariables must be demonstrably related through individual action having purposive quality. Discusses modes of theory construction, rational choice theory, and reductionism. (SV)

Hollow Gaussian beams and their propagation properties

NASA Astrophysics Data System (ADS)

Cai, Yangjian; Lu, Xuanhui; Lin, Qiang

2003-07-01

A new mathematical model, described as hollow Gaussian beams (HGBs), is proposed to describe a dark hollow laser beam (DHB). The area of the dark region across the HGBs can easily be controlled by proper choice of the beam parameters. Based on the Collins integral, an analytical propagation formula for the HGBs through a paraxial optical system is derived. The HGBs also can be expressed as a superposition of a series of Lagurerre-Gaussian modes by use of a polynomial expansion. As a numerical example, the propagation properties of a DHB in free space are illustrated graphically. The HGBs provide a convenient and powerful way to describe and treat the propagation of DHBs and can be used conveniently to analyze atoms manipulated with a DHB.

Hollow Gaussian beams and their propagation properties.

PubMed

Cai, Yangjian; Lu, Xuanhui; Lin, Qiang

2003-07-01

A new mathematical model, described as hollow Gaussian beams (HGBs), is proposed to describe a dark hollow laser beam (DHB). The area of the dark region across the HGBs can easily be controlled by proper choice of the beam parameters. Based on the Collins integral, an analytical propagation formula for the HGBs through a paraxial optical system is derived. The HGBs also can be expressed as a superposition of a series of Lagurerre-Gaussian modes by use of a polynomial expansion. As a numerical example, the propagation properties of a DHB in free space are illustrated graphically. The HGBs provide a convenient and powerful way to describe and treat the propagation of DHBs and can be used conveniently to analyze atoms manipulated with a DHB.

Editorial Commentary: All-Suture Anchors, Foam Blocks, and Biomechanical Testing.

PubMed

Brand, Jefferson C

2017-06-01

Barber's biomechanical work is well known to Arthroscopy's readers as thorough, comprehensive, and inclusive of new designs as they become available. In "All-Suture Anchors: Biomechanical Analysis of Pullout Strength, Displacement, and Failure Mode," the latest iteration, Barber and Herbert test all-suture anchors in both porcine femurs and biphasic foam. While we await in vivo clinical trials that compare all-suture anchors to currently used anchors, Barber and Herbert have provided data to inform anchor choice, and using their biomechanical data at time zero from all-suture anchor trials in an animal model, we can determine the anchors' feasibility for human clinical investigations. Copyright © 2017 Arthroscopy Association of North America. Published by Elsevier Inc. All rights reserved.

Quantum behaviour of pumped and damped triangular Bose-Hubbard systems

NASA Astrophysics Data System (ADS)

Chianca, C. V.; Olsen, M. K.

2017-12-01

We propose and analyse analogs of optical cavities for atoms using three-well Bose-Hubbard models with pumping and losses. We consider triangular configurations. With one well pumped and one damped, we find that both the mean-field dynamics and the quantum statistics show a quantitative dependence on the choice of damped well. The systems we analyse remain far from equilibrium, preserving good coherence between the wells in the steady-state. We find quadrature squeezing and mode entanglement for some parameter regimes and demonstrate that the trimer with pumping and damping at the same well is the stronger option for producing non-classical states. Due to recent experimental advances, it should be possible to demonstrate the effects we investigate and predict.

Improved ALE mesh velocities for complex flows

DOE PAGES

Bakosi, Jozsef; Waltz, Jacob I.; Morgan, Nathaniel Ray

2017-05-31

A key choice in the development of arbitrary Lagrangian-Eulerian solution algorithms is how to move the computational mesh. The most common approaches are smoothing and relaxation techniques, or to compute a mesh velocity field that produces smooth mesh displacements. We present a method in which the mesh velocity is specified by the irrotational component of the fluid velocity as computed from a Helmholtz decomposition, and excess compression of mesh cells is treated through a noniterative, local spring-force model. This approach allows distinct and separate control over rotational and translational modes. In conclusion, the utility of the new mesh motion algorithmmore » is demonstrated on a number of 3D test problems, including problems that involve both shocks and significant amounts of vorticity.« less

Nested Logit Models for Multiple-Choice Item Response Data

ERIC Educational Resources Information Center

Suh, Youngsuk; Bolt, Daniel M.

2010-01-01

Nested logit item response models for multiple-choice data are presented. Relative to previous models, the new models are suggested to provide a better approximation to multiple-choice items where the application of a solution strategy precedes consideration of response options. In practice, the models also accommodate collapsibility across all…

Enhancing Consumer Choice: Are We Making Appropriate Recommendations?

ERIC Educational Resources Information Center

Lee, Jinkook; Geistfeld, Loren V.

1998-01-01

This study used conjoint analysis to identify consumer choice models. Results suggest a need to base choice-making aids on ideal choice models if the aid is to lead consumers to decisions consistent with true preferences. (Author/JOW)

Results from flamelet and non-flamelet models for supersonic combustion

NASA Astrophysics Data System (ADS)

Ladeinde, Foluso; Li, Wenhai

2017-11-01

Air-breathing propulsion systems (scramjets) have been identified as a viable alternative to rocket engines for improved efficiency. A scramjet engine, which operates at flight Mach numbers around 7 or above, is characterized by the existence of supersonic flow conditions in the combustor. In a dual-mode scramjet, this phenomenon is possible because of the relatively low value of the equivalence ratio and high stagnation temperature, which, together, inhibits thermal choking downstream of transverse injectors. The flamelet method has been our choice for turbulence-combustion interaction modeling and we have extended the basic approach in several dimensions, with a focus on the way the pressure and progress variable are modeled. Improved results have been obtained. We have also examined non-flamelet models, including laminar chemistry (QL), eddy dissipation concept (EDC), and partially-stirred reactor (PaSR). The pressure/progress variable-corrected simulations give better results compared with the original model, with reaction rates that are lower than those from EDC and PaSR. In general, QL tends to over-predict the reaction rate for the supersonic combustion problems investigated in our work.

Research & market strategy: how choice of drug discovery approach can affect market position.

PubMed

Sams-Dodd, Frank

2007-04-01

In principal, drug discovery approaches can be grouped into target- and function-based, with the respective aims of developing either a target-selective drug or a drug that produces a specific biological effect irrespective of its mode of action. Most analyses of drug discovery approaches focus on productivity, whereas the strategic implications of the choice of drug discovery approach on market position and ability to maintain market exclusivity are rarely considered. However, a comparison of approaches from the perspective of market position indicates that the functional approach is superior for the development of novel, innovative treatments.

Mask cost of ownership for advanced lithography

NASA Astrophysics Data System (ADS)

Muzio, Edward G.; Seidel, Philip K.

2000-07-01

As technology advances, becoming more difficult and more expensive, the cost of ownership (CoO) metric becomes increasingly important in evaluating technical strategies. The International SEMATECH CoC analysis has steadily gained visibility over the past year, as it attempts to level the playing field between technology choices, and create a fair relative comparison. In order to predict mask cots for advanced lithography, mask process flows are modeled using bets-known processing strategies, equipment cost, and yields. Using a newly revised yield mode, and updated mask manufacture flows, representative mask flows can be built. These flows are then used to calculate mask costs for advanced lithography down to the 50 nm node. It is never the goal of this type of work to provide absolute cost estimates for business planning purposes. However, the combination of a quantifiable yield model with a clearly defined set of mask processing flows and a cost model based upon them serves as an excellent starting point for cost driver analysis and process flow discussion.

Compact eccentric long period grating with improved sensitivity in low refractive index region.

PubMed

Shen, Fangcheng; Zhou, Kaiming; Gordon, Neil; Zhang, Lin; Shu, Xuewen

2017-07-10

We demonstrate a compact eccentric long period grating with enhanced sensitivity in low refractive index region. With a period designed at 15 µm for coupling light to high order cladding modes, the grating is more sensitive to surrounding refractive index in low refractive index region. The intrinsically low coupling coefficients for those high order cladding modes are significantly improved with the eccentric localized inscription induced by the femtosecond laser. The fabricated grating is compact with a length of 4.05 mm, and exhibits an average sensitivity of ~505 nm/RIU in low refractive index region (1.3328-1.3544). The proposed principle can also work in other refractive index region with a proper choice of the resonant cladding modes.

Optimization of Antenna Current Feeding for the Alfvén Eigenmodes Active Diagnostic System of JET

NASA Astrophysics Data System (ADS)

Albarracin Manrique, Marcos A.; Ruchko, L.; Pires, C. J. A.; Galvão, R. M. O.; Elfimov, A. G.

2018-04-01

The possibility of exploring proper phasing of the feeding currents in the existing antenna of the Alfvén Eigenmodes Active Diagnostic system of JET, to excite pure toroidal spectra of Toroidal Alfvén Eigenmodes, is numerically investigated. Special attention is given to the actual perturbed fields excited in the plasma, which are calculated self-consistently using the antenna version of the CASTOR code. It is found that due to the close spacing of the JET antenna modules and quasi degeneracy of modes with medium to high values of the toroidal mode number n, although a proper choice of the phasing of the feeding currents of the antenna modules indeed leads to an increase of the perturbed fields of the selected mode, modes with nearby values of n are also excited with large amplitudes, so that a scheme to proper select the detected modes remains necessary. A scheme using different antenna position distribution is proposed to achieve successful optimization.

Preferences for breast cancer risk reduction among BRCA1/BRCA2 mutation carriers: a discrete-choice experiment.

PubMed

Liede, Alexander; Mansfield, Carol A; Metcalfe, Kelly A; Price, Melanie A; Snyder, Carrie; Lynch, Henry T; Friedman, Sue; Amelio, Justyna; Posner, Joshua; Narod, Steven A; Lindeman, Geoffrey J; Evans, D Gareth

2017-09-01

Unaffected women who carry BRCA1 or BRCA2 mutations face difficult choices about reducing their breast cancer risk. Understanding their treatment preferences could help us improve patient counseling and inform drug trials. The objective was to explore preferences for various risk-reducing options among women with germline BRCA1/2 mutations using a discrete-choice experiment survey and to compare expressed preferences with actual behaviors. A discrete-choice experiment survey was designed wherein women choose between hypothetical treatments to reduce breast cancer risk. The hypothetical treatments were characterized by the extent of breast cancer risk reduction, treatment duration, impact on fertility, hormone levels, risk of uterine cancer, and ease and mode of administration. Data were analyzed using a random-parameters logit model. Women were also asked to express their preference between surgical and chemoprevention options and to report on their actual risk-reduction actions. Women aged 25-55 years with germline BRCA1/2 mutations who were unaffected with breast or ovarian cancer were recruited through research registries at five clinics and a patient advocacy group. Between January 2015 and March 2016, 622 women completed the survey. Breast cancer risk reduction was the most important consideration expressed, followed by maintaining fertility. Among the subset of women who wished to have children in future, the ability to maintain fertility was the most important factor, followed by the extent of risk reduction. Many more women said they would take a chemoprevention drug than had actually taken chemoprevention. Women with BRCA1/2 mutations indicated strong preferences for breast cancer risk reduction and maintaining fertility. The expressed desire to have a safe chemoprevention drug available to them was not met by current chemoprevention options.

The roles of dopamine and serotonin in decision making: evidence from pharmacological experiments in humans.

PubMed

Rogers, Robert D

2011-01-01

Neurophysiological experiments in primates, alongside neuropsychological and functional magnetic resonance investigations in humans, have significantly enhanced our understanding of the neural architecture of decision making. In this review, I consider the more limited database of experiments that have investigated how dopamine and serotonin activity influences the choices of human adults. These include those experiments that have involved the administration of drugs to healthy controls, experiments that have tested genotypic influences upon dopamine and serotonin function, and, finally, some of those experiments that have examined the effects of drugs on the decision making of clinical samples. Pharmacological experiments in humans are few in number and face considerable methodological challenges in terms of drug specificity, uncertainties about pre- vs post-synaptic modes of action, and interactions with baseline cognitive performance. However, the available data are broadly consistent with current computational models of dopamine function in decision making and highlight the dissociable roles of dopamine receptor systems in the learning about outcomes that underpins value-based decision making. Moreover, genotypic influences on (interacting) prefrontal and striatal dopamine activity are associated with changes in choice behavior that might be relevant to understanding exploratory behaviors and vulnerability to addictive disorders. Manipulations of serotonin in laboratory tests of decision making in human participants have provided less consistent results, but the information gathered to date indicates a role for serotonin in learning about bad decision outcomes, non-normative aspects of risk-seeking behavior, and social choices involving affiliation and notions of fairness. Finally, I suggest that the role played by serotonin in the regulation of cognitive biases, and representation of context in learning, point toward a role in the cortically mediated cognitive appraisal of reinforcers when selecting between actions, potentially accounting for its influence upon the processing salient aversive outcomes and social choice.

Going public: do risk and choice explain differences in caesarean birth rates between public and private places of birth in Australia?

PubMed

Miller, Yvette D; Prosser, Samantha J; Thompson, Rachel

2012-10-01

women who birth in private facilities in Australia are more likely to have a caesarean birth than women who birth in public facilities and these differences remain after accounting for sector differences in the demographic and health risk profiles of women. However, the extent to which women's preferences and/or freedom to choose their mode of birth further account for differences in the likelihood of caesarean birth between the sectors remains untested. women who birthed in Queensland, Australia during a two-week period in 2009 were mailed a self-report survey approximately 3 months after birth. Seven hundred and fifty-seven women provided cross-sectional retrospective data on where they birthed (public or private facility), mode of birth (vaginal or caesarean) and risk factors, along with their preferences and freedom to choose their mode of birth. A hierarchical logistic regression was conducted to determine the extent to which maternal risk and freedom to choose one's mode of birth explain sector differences in the likelihood of having a caesarean birth. while there was no sector difference in women's preference for mode of birth, women who birthed in private facilities had higher odds of feeling able to choose either a vaginal or caesarean birth, and feeling able to choose only a caesarean birth. Women had higher odds of having caesarean birth if they birthed in private facilities, even after accounting for significant risk factors such as age, body mass index, previous caesarean and use of assisted reproductive technology. However, there was no association between place of birth and odds of having a caesarean birth after also accounting for freedom to choose one's mode of birth. these findings call into question suggestions that the higher caesarean birth rate in the private sector in Australia is attributable to increased levels of obstetric risk among women birthing in the private sector or maternal preferences alone. Instead, the determinants of sector differences in the likelihood of caesarean births are complex and are linked to differences in the perceived choices for mode of birth between women birthing in the private and public systems. Copyright © 2012 Elsevier Ltd. All rights reserved.

Embodied Choice: How Action Influences Perceptual Decision Making

PubMed Central

Lepora, Nathan F.; Pezzulo, Giovanni

2015-01-01

Embodied Choice considers action performance as a proper part of the decision making process rather than merely as a means to report the decision. The central statement of embodied choice is the existence of bidirectional influences between action and decisions. This implies that for a decision expressed by an action, the action dynamics and its constraints (e.g. current trajectory and kinematics) influence the decision making process. Here we use a perceptual decision making task to compare three types of model: a serial decision-then-action model, a parallel decision-and-action model, and an embodied choice model where the action feeds back into the decision making. The embodied model incorporates two key mechanisms that together are lacking in the other models: action preparation and commitment. First, action preparation strategies alleviate delays in enacting a choice but also modify decision termination. Second, action dynamics change the prospects and create a commitment effect to the initially preferred choice. Our results show that these two mechanisms make embodied choice models better suited to combine decision and action appropriately to achieve suitably fast and accurate responses, as usually required in ecologically valid situations. Moreover, embodied choice models with these mechanisms give a better account of trajectory tracking experiments during decision making. In conclusion, the embodied choice framework offers a combined theory of decision and action that gives a clear case that embodied phenomena such as the dynamics of actions can have a causal influence on central cognition. PMID:25849349

Embodied choice: how action influences perceptual decision making.

PubMed

Lepora, Nathan F; Pezzulo, Giovanni

2015-04-01

Embodied Choice considers action performance as a proper part of the decision making process rather than merely as a means to report the decision. The central statement of embodied choice is the existence of bidirectional influences between action and decisions. This implies that for a decision expressed by an action, the action dynamics and its constraints (e.g. current trajectory and kinematics) influence the decision making process. Here we use a perceptual decision making task to compare three types of model: a serial decision-then-action model, a parallel decision-and-action model, and an embodied choice model where the action feeds back into the decision making. The embodied model incorporates two key mechanisms that together are lacking in the other models: action preparation and commitment. First, action preparation strategies alleviate delays in enacting a choice but also modify decision termination. Second, action dynamics change the prospects and create a commitment effect to the initially preferred choice. Our results show that these two mechanisms make embodied choice models better suited to combine decision and action appropriately to achieve suitably fast and accurate responses, as usually required in ecologically valid situations. Moreover, embodied choice models with these mechanisms give a better account of trajectory tracking experiments during decision making. In conclusion, the embodied choice framework offers a combined theory of decision and action that gives a clear case that embodied phenomena such as the dynamics of actions can have a causal influence on central cognition.

Shear horizontal feature guided ultrasonic waves in plate structures with 90° transverse bends.

PubMed

Yu, Xudong; Manogharan, Prabhakaran; Fan, Zheng; Rajagopal, Prabhu

2016-02-01

Antisymmetric and symmetric Lamb-type feature guided waves (FGW) have recently been shown to exist in small angle plate bends. This paper reports Semi-Analytical Finite Element (SAFE) method simulations revealing the existence of a new family of Shear Horizontal (SHB) type of FGW mode in 90° bends in plate structures. Mode shapes and velocity dispersion curves are extracted, demonstrating the SH-like nature of a bend-confined mode identified in studies of power flow across the bend. The SHB mode is shown to have reduced attenuation in the higher frequency range, making it an ideal choice for high-resolution inspection of such bends. Further modal studies examine the physical basis for mode confinement, and argue that this is strongly related to FGW phenomena reported earlier, and also linked to the curvature at the bend region. Wedge acoustic waves discussed widely in literature are shown as arising from surface-limiting of the SHB mode at higher frequencies. The results are validated by experiments and supported by 3D Finite Element (FE) simulations. Copyright © 2015 Elsevier B.V. All rights reserved.

Choice of reserve capacity by hospitals: a problem for prospective payment.

PubMed

Widmer, Philippe K; Trottmann, Maria; Zweifel, Peter

2018-06-01

This contribution analyzes the impact of prospective payment on hospital decisions with regard to reserve capacity, using Swiss hospital data covering the years 2004-2009. This data set is unique because it permits distinguishing of institutional characteristics (e.g., ownership status) from the mode of payment as determinants of hospital efficiency, due to the fact that some Swiss cantons introduced prospective payment early while others waited for federal legislation to be enacted in 2012. Since a hospital's choice of reserve capacity depends also on the risk preferences of management while affecting the cost function, heterogeneity is predicted even in the presence of identical technology and factor prices. For estimating hospitals' marginal costs, we employ the flexible representation of risk preferences by Pope and Chavas [Am J Agric Econ 76, 196-204 (1994)]. Production uncertainty is measured as the difference between actual admissions and admissions predicted by an autoregressive moving average model. Its effect on hospital cost is analyzed using a multilevel stochastic cost frontier model with random coefficients reflecting unobserved differences in technology. Public hospitals are found to opt for a higher probability of meeting unexpected demand, as predicted. Their operating cost is 1.1% higher than for private hospitals and even 1.9% higher than for teaching hospitals, creating an incentive to turn away patients or to keep them waiting for treatment.

Neighborhood crime and travel behavior : an investigation of the influence of neighborhood crime rates on mode choice, phase II [research brief].

DOT National Transportation Integrated Search

2012-01-01

There are considerable environmental and public health benefits if people choose to walk, bicycle, or ride transit, instead of drive. As a result, planners and policy-makers are increasingly looking for ways to encourage alternatives to driving. Most...

Multiple Modes in Corporate Learning: Propelling Business IQ with Formal, Informal and Social Learning

ERIC Educational Resources Information Center

Ambrose, John; Ogilvie, Julie

2010-01-01

Recognizing that the shifting corporate environment is placing ever greater stresses on learning organizations, this paper reports how companies are increasingly offering employees a wide choice of learning options beyond conventional classroom training, including online, social learning, and other modalities in "blended" programs. Identifying a…

Geospatial analysis of bicycle network "level of traffic stress", bicycle mode choice behavior, and bicycle crashes for risk factor identification.

DOT National Transportation Integrated Search

2015-08-01

Small and medium-sized cities need publicly acceptable criteria for bicycle infrastructure improvements. This report explores the : effectiveness of one proposed system of bicycle infrastructure criteria using data from a state-of-the-art travel surv...

Female Faculty: Challenges and Choices in the United States and Beyond

ERIC Educational Resources Information Center

Samble, Jennifer N.

2008-01-01

Substantial amounts of research and data detail the challenges female faculty face in the academy. These include unequal pay for similarly situated individuals, disparities between female representation within the professoriate and student population, and perceptions and accepted modes of behavior that have the effect of disenfranchising women as…

The Future of Learning and Training in Augmented Reality

ERIC Educational Resources Information Center

Lee, Kangdon

2012-01-01

Students acquire knowledge and skills through different modes of instruction that include classroom lectures with textbooks, computers, and the like. The availability and choice of learning innovation depends on the individual's access to technologies and on the infrastructure environment of the surrounding community. In this rapidly changing…

A systematic evaluation of the impacts of traffic condition information on the reduction of on-road mobile emissions : final report.

DOT National Transportation Integrated Search

2016-07-01

Current Advanced Traveler Information Systems (ATIS) allow travelers to change their route, mode, departure time, route choice or destination to avoid delays and congestions, which results in improved traffic flow. This means higher vehicle speed, lo...

Syntactic Language Correlates of Written Communication Apprehension.

ERIC Educational Resources Information Center

Stacks, Don W.; And Others

A study provided the initial test of a multidimensional instrument based on the idea that syntactic language choice might predict writing apprehension. The test measured six factors: (1) blank page paralysis, (2) general affect toward writing, (3) positive/negative business affect, (4) alternative modes, (5) attitude toward writing competence, and…

Choices and Changes: Eccles' Expectancy-Value Model and Upper-Secondary School Students' Longitudinal Reflections about Their Choice of a STEM Education

ERIC Educational Resources Information Center

Lykkegaard, Eva; Ulriksen, Lars

2016-01-01

During the past 30 years, Eccles' comprehensive social-psychological Expectancy-Value Model of Motivated Behavioural Choices (EV-MBC model) has been proven suitable for studying educational choices related to Science, Technology, Engineering and/or Mathematics (STEM). The reflections of 15 students in their last year in upper-secondary school…

Greater preference consistency during the Willingness-to-Pay task is related to higher resting state connectivity between the ventromedial prefrontal cortex and the ventral striatum.

PubMed

Mackey, Scott; Olafsson, Valur; Aupperle, Robin L; Lu, Kun; Fonzo, Greg A; Parnass, Jason; Liu, Thomas; Paulus, Martin P

2016-09-01

The significance of why a similar set of brain regions are associated with the default mode network and value-related neural processes remains to be clarified. Here, we examined i) whether brain regions exhibiting willingness-to-pay (WTP) task-related activity are intrinsically connected when the brain is at rest, ii) whether these regions overlap spatially with the default mode network, and iii) whether individual differences in choice behavior during the WTP task are reflected in functional brain connectivity at rest. Blood-oxygen-level dependent (BOLD) signal was measured by functional magnetic resonance imaging while subjects performed the WTP task and at rest with eyes open. Brain regions that tracked the value of bids during the WTP task were used as seed regions in an analysis of functional connectivity in the resting state data. The seed in the ventromedial prefrontal cortex was functionally connected to core regions of the WTP task-related network. Brain regions within the WTP task-related network, namely the ventral precuneus, ventromedial prefrontal and posterior cingulate cortex overlapped spatially with publically available maps of the default mode network. Also, those individuals with higher functional connectivity during rest between the ventromedial prefrontal cortex and the ventral striatum showed greater preference consistency during the WTP task. Thus, WTP task-related regions are an intrinsic network of the brain that corresponds spatially with the default mode network, and individual differences in functional connectivity within the WTP network at rest may reveal a priori biases in choice behavior.

Greater preference consistency during the Willingness-to-Pay task is related to higher resting state connectivity between the ventromedial prefrontal cortex and the ventral striatum

PubMed Central

Mackey, Scott; Olafsson, Valur; Aupperle, Robin; Lu, Kun; Fonzo, Greg; Parnass, Jason; Liu, Thomas; Paulus, Martin P.

2015-01-01

The significance of why a similar set of brain regions are associated with the default mode network and value-related neural processes remains to be clarified. Here, we examined i) whether brain regions exhibiting willingness-to-pay (WTP) task-related activity are intrinsically connected when the brain is at rest, ii) whether these regions overlap spatially with the default mode network, and iii) whether individual differences in choice behavior during the WTP task are reflected in functional brain connectivity at rest. Blood-oxygen-level dependent (BOLD) signal was measured by functional magnetic resonance imaging while subjects performed the WTP task and at rest with eyes open. Brain regions that tracked the value of bids during the WTP task were used as seed regions in an analysis of functional connectivity in the resting state data. The seed in the ventromedial prefrontal cortex was functionally connected to core regions of the WTP task-related network. Brain regions within the WTP task-related network, namely the ventral precuneus, ventromedial prefrontal and posterior cingulate cortex overlapped spatially with publically available maps of the default mode network. Also, those individuals with higher functional connectivity during rest between the ventromedial prefrontal cortex and the ventral striatum showed greater preference consistency during the WTP task. Thus, WTP task-related regions are an intrinsic network of the brain that corresponds spatially with the default mode network, and individual differences in functional connectivity within the WTP network at rest may reveal a priori biases in choice behavior. PMID:26271206

The nonlinear evolution of modes on unstable stratified shear layers

NASA Technical Reports Server (NTRS)

Blackaby, Nicholas; Dando, Andrew; Hall, Philip

1993-01-01

The nonlinear development of disturbances in stratified shear flows (having a local Richardson number of value less than one quarter) is considered. Such modes are initially fast growing but, like related studies, we assume that the viscous, non-parallel spreading of the shear layer results in them evolving in a linear fashion until they reach a position where their amplitudes are large enough and their growth rates have diminished sufficiently so that amplitude equations can be derived using weakly nonlinear and non-equilibrium critical-layer theories. Four different basic integro-differential amplitude equations are possible, including one due to a novel mechanism; the relevant choice of amplitude equation, at a particular instance, being dependent on the relative sizes of the disturbance amplitude, the growth rate of the disturbance, its wavenumber, and the viscosity of the fluid. This richness of choice of possible nonlinearities arises mathematically from the indicial Frobenius roots of the governing linear inviscid equation (the Taylor-Goldstein equation) not, in general, differing by an integer. The initial nonlinear evolution of a mode will be governed by an integro-differential amplitude equations with a cubic nonlinearity but the resulting significant increase in the size of the disturbance's amplitude leads on to the next stage of the evolution process where the evolution of the mode is governed by an integro-differential amplitude equations with a quintic nonlinearity. Continued growth of the disturbance amplitude is expected during this stage, resulting in the effects of nonlinearity spreading to outside the critical level, by which time the flow has become fully nonlinear.

Socio-sexuality and episodic memory function in women: further evidence of an adaptive "mating mode".

PubMed

Smith, David S; Jones, Benedict C; Allan, Kevin

2013-08-01

The functionalist memory perspective predicts that information of adaptive value may trigger specific processing modes. It was recently demonstrated that women's memory is sensitive to cues of male sexual dimorphism (i.e., masculinity) that convey information of adaptive value for mate choice because they signal health and genetic quality, as well as personality traits important in relationship contexts. Here, we show that individual differences in women's mating strategies predict the effect of facial masculinity cues upon memory, strengthening the case for functional design within memory. Using the revised socio-sexual orientation inventory, Experiment 1 demonstrates that women pursuing a short-term, uncommitted mating strategy have enhanced source memory for men with exaggerated versus reduced masculine facial features, an effect that reverses in women who favor long-term committed relationships. The reversal in the direction of the effect indicates that it does not reflect the sex typicality of male faces per se. The same pattern occurred within women's source memory for women's faces, implying that the memory bias does not reflect the perceived attractiveness of faces per se. In Experiment 2, we reran the experiment using men's faces to establish the reliability of the core finding and replicated Experiment 1's results. Masculinity cues may therefore trigger a specific mode within women's episodic memory. We discuss why this mode may be triggered by female faces and its possible role in mate choice. In so doing, we draw upon the encoding specificity principle and the idea that episodic memory limits the scope of stereotypical inferences about male behavior.

Application of failure mode and effects analysis (FMEA) to pretreatment phases in tomotherapy.

PubMed

Broggi, Sara; Cantone, Marie Claire; Chiara, Anna; Di Muzio, Nadia; Longobardi, Barbara; Mangili, Paola; Veronese, Ivan

2013-09-06

The aim of this paper was the application of the failure mode and effects analysis (FMEA) approach to assess the risks for patients undergoing radiotherapy treatments performed by means of a helical tomotherapy unit. FMEA was applied to the preplanning imaging, volume determination, and treatment planning stages of the tomotherapy process and consisted of three steps: 1) identification of the involved subprocesses; 2) identification and ranking of the potential failure modes, together with their causes and effects, using the risk probability number (RPN) scoring system; and 3) identification of additional safety measures to be proposed for process quality and safety improvement. RPN upper threshold for little concern of risk was set at 125. A total of 74 failure modes were identified: 38 in the stage of preplanning imaging and volume determination, and 36 in the stage of planning. The threshold of 125 for RPN was exceeded in four cases: one case only in the phase of preplanning imaging and volume determination, and three cases in the stage of planning. The most critical failures appeared related to (i) the wrong or missing definition and contouring of the overlapping regions, (ii) the wrong assignment of the overlap priority to each anatomical structure, (iii) the wrong choice of the computed tomography calibration curve for dose calculation, and (iv) the wrong (or not performed) choice of the number of fractions in the planning station. On the basis of these findings, in addition to the safety strategies already adopted in the clinical practice, novel solutions have been proposed for mitigating the risk of these failures and to increase patient safety.

a New Method for Fmeca Based on Fuzzy Theory and Expert System

NASA Astrophysics Data System (ADS)

Byeon, Yoong-Tae; Kim, Dong-Jin; Kim, Jin-O.

2008-10-01

Failure Mode Effects and Criticality Analysis (FMECA) is one of most widely used methods in modern engineering system to investigate potential failure modes and its severity upon the system. FMECA evaluates criticality and severity of each failure mode and visualize the risk level matrix putting those indices to column and row variable respectively. Generally, those indices are determined subjectively by experts and operators. However, this process has no choice but to include uncertainty. In this paper, a method for eliciting expert opinions considering its uncertainty is proposed to evaluate the criticality and severity. In addition, a fuzzy expert system is constructed in order to determine the crisp value of risk level for each failure mode. Finally, an illustrative example system is analyzed in the case study. The results are worth considering in deciding the proper policies for each component of the system.

The effects of Georgia's Choice curricular reform model on third grade science scores on the Georgia Criterion Referenced Competency Test

NASA Astrophysics Data System (ADS)

Phemister, Art W.

The purpose of this study was to evaluate the effectiveness of the Georgia's Choice reading curriculum on third grade science scores on the Georgia Criterion Referenced Competency Test from 2002 to 2008. In assessing the effectiveness of the Georgia's Choice curriculum model this causal comparative study examined the 105 elementary schools that implemented Georgia's Choice and 105 randomly selected elementary schools that did not elect to use Georgia's Choice. The Georgia's Choice reading program used intensified instruction in an effort to increase reading levels for all students. The study used a non-equivalent control group with a pretest and posttest design to determine the effectiveness of the Georgia's Choice curriculum model. Findings indicated that third grade students in Non-Georgia's Choice schools outscored third grade students in Georgia's Choice schools across the span of the study.

Axisymmetric Shearing Box Models of Magnetized Disks

NASA Astrophysics Data System (ADS)

Guan, Xiaoyue; Gammie, Charles F.

2008-01-01

The local model, or shearing box, has proven a useful model for studying the dynamics of astrophysical disks. Here we consider the evolution of magnetohydrodynamic (MHD) turbulence in an axisymmetric local model in order to evaluate the limitations of global axisymmetric models. An exploration of the model parameter space shows the following: (1) The magnetic energy and α-decay approximately exponentially after an initial burst of turbulence. For our code, HAM, the decay time τ propto Res , where Res/2 is the number of zones per scale height. (2) In the initial burst of turbulence the magnetic energy is amplified by a factor proportional to Res3/4λR, where λR is the radial scale of the initial field. This scaling applies only if the most unstable wavelength of the magnetorotational instability is resolved and the final field is subthermal. (3) The shearing box is a resonant cavity and in linear theory exhibits a discrete set of compressive modes. These modes are excited by the MHD turbulence and are visible as quasi-periodic oscillations (QPOs) in temporal power spectra of fluid variables at low spatial resolution. At high resolution the QPOs are hidden by a noise continuum. (4) In axisymmetry disk turbulence is local. The correlation function of the turbulence is limited in radial extent, and the peak magnetic energy density is independent of the radial extent of the box LR for LR > 2H. (5) Similar results are obtained for the HAM, ZEUS, and ATHENA codes; ATHENA has an effective resolution that is nearly double that of HAM and ZEUS. (6) Similar results are obtained for 2D and 3D runs at similar resolution, but only for particular choices of the initial field strength and radial scale of the initial magnetic field.

Patients' preferences for anti-osteoporosis drug treatment: a cross-European discrete choice experiment.

PubMed

Hiligsmann, Mickaël; Dellaert, Benedict G; Dirksen, Carmen D; Watson, Verity; Bours, Sandrine; Goemaere, Stefan; Reginster, Jean-Yves; Roux, Christian; McGowan, Bernie; Silke, Carmel; Whelan, Bryan; Diez-Perez, Adolfo; Torres, Elisa; Papadakis, Georgios; Rizzoli, Rene; Cooper, Cyrus; Pearson, Gill; Boonen, Annelies

2017-07-01

To estimate the preferences of osteoporotic patients for medication attributes, and analyse data from seven European countries. A discrete choice experiment was conducted in Belgium, France, Ireland, the Netherlands, Spain, Switzerland and the UK. Patients were asked to choose repeatedly between two hypothetical unlabelled drug treatments (and an opt-out option) that varied with respect to four attributes: efficacy in reducing the risk of fracture, type of potential common side effects, and mode and frequency of administration. In those countries in which patients contribute to the cost of their treatment directly, a fifth attribute was added: out-of-pocket cost. A mixed logit panel model was used to estimate patients' preferences. In total, 1124 patients completed the experiment, with a sample of between 98 and 257 patients per country. In all countries, patients preferred treatment with higher effectiveness, and 6-monthly subcutaneous injection was always preferred over weekly oral tablets. In five countries, patients also preferred a monthly oral tablet and yearly i.v. injections over weekly oral tablets. In the three countries where the out-of-pocket cost was included as an attribute, lower costs significantly contributed to the treatment preference. Between countries, there were statistically significant differences for 13 out of 42 attribute/level interactions. We found statistically significant differences in patients' preferences for anti-osteoporosis medications between countries, especially for the mode of administration. Our findings emphasized that international treatment recommendations should allow for local adaptation, and that understanding individual preferences is important if we want to improve the quality of clinical care for patients with osteoporosis. © The Author 2017. Published by Oxford University Press on behalf of the British Society for Rheumatology. All rights reserved. For Permissions, please email: journals.permissions@oup.com

Estimating preferences for modes of drug administration: The case of US healthcare professionals.

PubMed

Tetteh, Ebenezer K; Morris, Steve; Titchener-Hooker, Nigel

2018-01-01

There are hidden drug administration costs that arise from a mismatch between end-user preferences and how manufacturers choose to formulate their drug products for delivery to patients. The corollary of this is: there are "intangible benefits" from considering end-user preferences in manufacturing patient-friendly medicines. It is important then to have some idea of what pharmaceutical manufacturers should consider in making patient-friendly medicines and of the magnitude of the indirect benefits from doing so. This study aimed to evaluate preferences of healthcare professionals in the US for the non-monetary attributes of different modes of drug administration. It uses these preference orderings to compute a monetary valuation of the indirect benefits from making patient-friendly medicines. A survey collected choice preferences of a sample of 210 healthcare professionals in the US for two unlabelled drug options. These drugs were identical except in the levels of attributes of drug administration. Using the choice data collected, statistical models were estimated to compute gross welfare benefits, measured by the expected compensating variation, from making drugs in a more patient-friendly manner. The monetary value of end-user benefits from developing patient-friendly drug delivery systems is: (1) as large as the annual acquisition costs per full treatment episode for some biologic drugs; and (2) likely to fall in the "high end" of the distribution of the direct monetary costs of drug administration. An examination of end-user preferences should help manufacturers make more effective and efficient use of limited resources for innovations in drug delivery system, or manufacturing research in general. Copyright © 2017 Elsevier Inc. All rights reserved.

Discrete Choice Experiments: A Guide to Model Specification, Estimation and Software.

PubMed

Lancsar, Emily; Fiebig, Denzil G; Hole, Arne Risa

2017-07-01

We provide a user guide on the analysis of data (including best-worst and best-best data) generated from discrete-choice experiments (DCEs), comprising a theoretical review of the main choice models followed by practical advice on estimation and post-estimation. We also provide a review of standard software. In providing this guide, we endeavour to not only provide guidance on choice modelling but to do so in a way that provides a 'way in' for researchers to the practicalities of data analysis. We argue that choice of modelling approach depends on the research questions, study design and constraints in terms of quality/quantity of data and that decisions made in relation to analysis of choice data are often interdependent rather than sequential. Given the core theory and estimation of choice models is common across settings, we expect the theoretical and practical content of this paper to be useful to researchers not only within but also beyond health economics.

A Bayesian hierarchical model for discrete choice data in health care.

PubMed

Antonio, Anna Liza M; Weiss, Robert E; Saigal, Christopher S; Dahan, Ely; Crespi, Catherine M

2017-01-01

In discrete choice experiments, patients are presented with sets of health states described by various attributes and asked to make choices from among them. Discrete choice experiments allow health care researchers to study the preferences of individual patients by eliciting trade-offs between different aspects of health-related quality of life. However, many discrete choice experiments yield data with incomplete ranking information and sparsity due to the limited number of choice sets presented to each patient, making it challenging to estimate patient preferences. Moreover, methods to identify outliers in discrete choice data are lacking. We develop a Bayesian hierarchical random effects rank-ordered multinomial logit model for discrete choice data. Missing ranks are accounted for by marginalizing over all possible permutations of unranked alternatives to estimate individual patient preferences, which are modeled as a function of patient covariates. We provide a Bayesian version of relative attribute importance, and adapt the use of the conditional predictive ordinate to identify outlying choice sets and outlying individuals with unusual preferences compared to the population. The model is applied to data from a study using a discrete choice experiment to estimate individual patient preferences for health states related to prostate cancer treatment.

Response repetition biases in human perceptual decisions are explained by activity decay in competitive attractor models

PubMed Central

Bonaiuto, James J; de Berker, Archy; Bestmann, Sven

2016-01-01

Animals and humans have a tendency to repeat recent choices, a phenomenon known as choice hysteresis. The mechanism for this choice bias remains unclear. Using an established, biophysically informed model of a competitive attractor network for decision making, we found that decaying tail activity from the previous trial caused choice hysteresis, especially during difficult trials, and accurately predicted human perceptual choices. In the model, choice variability could be directionally altered through amplification or dampening of post-trial activity decay through simulated depolarizing or hyperpolarizing network stimulation. An analogous intervention using transcranial direct current stimulation (tDCS) over left dorsolateral prefrontal cortex (dlPFC) yielded a close match between model predictions and experimental results: net soma depolarizing currents increased choice hysteresis, while hyperpolarizing currents suppressed it. Residual activity in competitive attractor networks within dlPFC may thus give rise to biases in perceptual choices, which can be directionally controlled through non-invasive brain stimulation. DOI: http://dx.doi.org/10.7554/eLife.20047.001 PMID:28005007

Full vector modal analysis of microstructured optical fiber propagation characteristics

NASA Astrophysics Data System (ADS)

Zghal, Mourad; Bahloul, Faouzi; Chatta, Rihab; Attia, Rabah; Pagnoux, Dominique; Roy, Philippe; Melin, Gilles; Gasca, Laurent

2004-10-01

Microstructured optical fibers (MOFs) are optical fibers having a periodic air-silica cross-section. The air holes extend along the axis of the fiber for its entire length. The core of the fiber is formed by a missing hole in the periodic structure. Remarkable properties of MOFs have recently been reported. This paper presents new work in the modeling of the propagation characteristics of MOFs using the Finite Element Method (FEM) and the Galerkin Method (GM). This efficient electromagnetic simulation package provides a vectorial description of the electromagnetic fields and of the associated effective index. This information includes accurate determination of the spectral extent of the modes, cutoff properties and mode-field distributions. We show that FEM is well adapted for describing the fields at abrupt transitions of the refractive index while GM has the advantage to accurately analyze MOFs of significant complexity using only modest computational resources. This presentation will focus on the specific techniques required to determine single mode operation, dispersion properties and effective area through careful choice of the geometrical parameters of the fibers. We demonstrate that with suitable geometrical parameters, the zero dispersion wavelength can be shifted. This tool can also provide design criteria for fabricating MOFs and a corresponding map of effective area. This approach is validated by comparison with experimental results and measurements on actual MOFs fabricated at IRCOM and at Alcatel Research and Innovation Center.

Choice-Based Conjoint Analysis: Classification vs. Discrete Choice Models

NASA Astrophysics Data System (ADS)

Giesen, Joachim; Mueller, Klaus; Taneva, Bilyana; Zolliker, Peter

Conjoint analysis is a family of techniques that originated in psychology and later became popular in market research. The main objective of conjoint analysis is to measure an individual's or a population's preferences on a class of options that can be described by parameters and their levels. We consider preference data obtained in choice-based conjoint analysis studies, where one observes test persons' choices on small subsets of the options. There are many ways to analyze choice-based conjoint analysis data. Here we discuss the intuition behind a classification based approach, and compare this approach to one based on statistical assumptions (discrete choice models) and to a regression approach. Our comparison on real and synthetic data indicates that the classification approach outperforms the discrete choice models.

The Answering Process for Multiple-Choice Questions in Collaborative Learning: A Mathematical Learning Model Analysis

ERIC Educational Resources Information Center

Nakamura, Yasuyuki; Nishi, Shinnosuke; Muramatsu, Yuta; Yasutake, Koichi; Yamakawa, Osamu; Tagawa, Takahiro

2014-01-01

In this paper, we introduce a mathematical model for collaborative learning and the answering process for multiple-choice questions. The collaborative learning model is inspired by the Ising spin model and the model for answering multiple-choice questions is based on their difficulty level. An intensive simulation study predicts the possibility of…

A comprehensive dwelling unit choice model accommodating psychological constructs within a search strategy for consideration set formation.

DOT National Transportation Integrated Search

2015-12-01

This study adopts a dwelling unit level of analysis and considers a probabilistic choice set generation approach for residential choice modeling. In doing so, we accommodate the fact that housing choices involve both characteristics of the dwelling u...

NGST fine guidance sensor

NASA Astrophysics Data System (ADS)

Rowlands, Neil; Hutchings, John; Murowinski, Richard G.; Alexander, Russ

2003-03-01

Instrumentation for the Next Generation Space Telescope (NGST) is currently in the Phase A definition stage. We have developed a concept for the NGST Fine Guidance Sensor or FGS. The FGS is a detector array based imager which resides in the NGST focal plane. We report here on tradeoff studies aimed at defining an overall configuration of the FGS which will meet the performance and interface requirements. A key performance requirement is a noise equivalent angle of 3 milli-arcseconds to be achieved with 95% probability for any pointing of the observatory in the celestial sphere. A key interface requirement is compatibility with the architecture of the Integrated Science Instrument Module (ISIM). The concept developed consists of two independent and redundant FGS modules, each with a 4' x 2' field of view covered by two 2048 x 2048 infrared detector arrays, providing 60 milli-arcsecond sampling. Performance modeling supporting the choice of this architecture and the trade space considered is presented. Each module has a set of readout electronics which perform star detection, pixel-by-pixel correction, and in fine guiding mode, centroid calculation. These readout electronics communicate with the ISIM Command &Data Handling Units where the FGS control software is based. Rationale for this choice of architecture is also presented.

Internet Access as a Structural Factor in Career Choice: A Comparison between Computing and Non-Computing Major Students

ERIC Educational Resources Information Center

Lotriet, Hugo; Matthee, Machdel; Alexander, Patricia

2011-01-01

The career choice model of Adya and Kaiser posits the availability of technology resources as a structural element impacting on career choice. The model distinguishes between accessibility at school and at home. Based on this theoretical point of departure and by arguing a link between choice of major and choice of field of career, this paper…

Hierarchical Diffusion Models for Two-Choice Response Times

ERIC Educational Resources Information Center

Vandekerckhove, Joachim; Tuerlinckx, Francis; Lee, Michael D.

2011-01-01

Two-choice response times are a common type of data, and much research has been devoted to the development of process models for such data. However, the practical application of these models is notoriously complicated, and flexible methods are largely nonexistent. We combine a popular model for choice response times--the Wiener diffusion…

Predictors of Latina/o Community College Student Vocational Choice in STEM

ERIC Educational Resources Information Center

Johnson, Joel D.; Starobin, Soko S.; Santos Laanan, Frankie

2016-01-01

This study confirmed appropriate measurement model fit for a theoretical model, the STEM (science, technology, engineering, and mathematics) vocational choice (STEM-VC) model. This model identified factors that successfully predicted a student's vocational choice decision to pursue a STEM degree for Latina/o and White community college students.…

An analysis of four ways of assessing student beliefs about sts topics

NASA Astrophysics Data System (ADS)

Aikenhead, Glen S.

The study investigated the degree of ambiguity harbored by four different response modes used to monitor student beliefs about science-technology-society topics: Likert-type, written paragraph, semistrue tured interview, and empirically developed multiple choice. The study also explored the sources of those beliefs. Grade-12 students in a Canadian urban setting responded, in each of the four modes, to statements from Views on Science-Technology-Society. It was discovered that TV had far more influence on what students believed about science and its social, technological context than did numerous science courses. The challenge to science educators is to use the media effectively in combating naive views about science. Regarding ambiguity in student assessment, the Likert-type responses were the most inaccurate, offering only a guess at student beliefs. Such guesswork calls into question the use of Likert-type standardized tests that claim to assess student views about science. Student paragraph responses contained significant ambiguities in about 50% of the cases. The empirically developed multiple choices, however, reduced the ambiguity to the 20% level. Predictably, the semistructured interview was the least ambiguous of all four response modes, but it required the most time to administer. These findings encourage researchers to develop instruments grounded in the empirical data of student viewpoints, rather than relying solely on instruments structured by the philosophical stances of science educators.

Importance of the habitat choice behavior assumed when modeling the effects of food and temperature on fish populations

USGS Publications Warehouse

Wildhaber, Mark L.; Lamberson, Peter J.

2004-01-01

Various mechanisms of habitat choice in fishes based on food and/or temperature have been proposed: optimal foraging for food alone; behavioral thermoregulation for temperature alone; and behavioral energetics and discounted matching for food and temperature combined. Along with development of habitat choice mechanisms, there has been a major push to develop and apply to fish populations individual-based models that incorporate various forms of these mechanisms. However, it is not known how the wide variation in observed and hypothesized mechanisms of fish habitat choice could alter fish population predictions (e.g. growth, size distributions, etc.). We used spatially explicit, individual-based modeling to compare predicted fish populations using different submodels of patch choice behavior under various food and temperature distributions. We compared predicted growth, temperature experience, food consumption, and final spatial distribution using the different models. Our results demonstrated that the habitat choice mechanism assumed in fish population modeling simulations was critical to predictions of fish distribution and growth rates. Hence, resource managers who use modeling results to predict fish population trends should be very aware of and understand the underlying patch choice mechanisms used in their models to assure that those mechanisms correctly represent the fish populations being modeled.

Design and analysis of simple choice surveys for natural resource management

USGS Publications Warehouse

Fieberg, John; Cornicelli, Louis; Fulton, David C.; Grund, Marrett D.

2010-01-01

We used a simple yet powerful method for judging public support for management actions from randomized surveys. We asked respondents to rank choices (representing management regulations under consideration) according to their preference, and we then used discrete choice models to estimate probability of choosing among options (conditional on the set of options presented to respondents). Because choices may share similar unmodeled characteristics, the multinomial logit model, commonly applied to discrete choice data, may not be appropriate. We introduced the nested logit model, which offers a simple approach for incorporating correlation among choices. This forced choice survey approach provides a useful method of gathering public input; it is relatively easy to apply in practice, and the data are likely to be more informative than asking constituents to rate attractiveness of each option separately.

Modeling Confidence Judgments, Response Times, and Multiple Choices in Decision Making: Recognition Memory and Motion Discrimination

PubMed Central

Ratcliff, Roger; Starns, Jeffrey J.

2014-01-01

Confidence in judgments is a fundamental aspect of decision making, and tasks that collect confidence judgments are an instantiation of multiple-choice decision making. We present a model for confidence judgments in recognition memory tasks that uses a multiple-choice diffusion decision process with separate accumulators of evidence for the different confidence choices. The accumulator that first reaches its decision boundary determines which choice is made. Five algorithms for accumulating evidence were compared, and one of them produced proportions of responses for each of the choices and full response time distributions for each choice that closely matched empirical data. With this algorithm, an increase in the evidence in one accumulator is accompanied by a decrease in the others so that the total amount of evidence in the system is constant. Application of the model to the data from an earlier experiment (Ratcliff, McKoon, & Tindall, 1994) uncovered a relationship between the shapes of z-transformed receiver operating characteristics and the behavior of response time distributions. Both are explained in the model by the behavior of the decision boundaries. For generality, we also applied the decision model to a 3-choice motion discrimination task and found it accounted for data better than a competing class of models. The confidence model presents a coherent account of confidence judgments and response time that cannot be explained with currently popular signal detection theory analyses or dual-process models of recognition. PMID:23915088

Analysis of bending wave transmission using beam tracing with advanced statistical energy analysis for periodic box-like structures affected by spatial filtering

NASA Astrophysics Data System (ADS)

Wilson, D.; Hopkins, C.

2015-04-01

For bending wave transmission across periodic box-like arrangements of plates, the effects of spatial filtering can be significant and this needs to be considered in the choice of prediction model. This paper investigates the errors that can occur with Statistical Energy Analysis (SEA) and the potential of using Advanced SEA (ASEA) to improve predictions. The focus is on the low- and mid-frequency range where plates only support local modes with low mode counts and the in situ modal overlap is relatively high. To increase the computational efficiency when using ASEA on large systems, a beam tracing method is introduced which groups together all rays with the same heading into a single beam. Based on a diffuse field on the source plate, numerical experiments are used to determine the angular distribution of incident power on receiver plate edges on linear and cuboid box-like structures. These show that on receiver plates which do not share a boundary with the source plate, the angular distribution on the receiver plate boundaries differs significantly from a diffuse field. SEA and ASEA predictions are assessed through comparison with finite element models. With rain-on-the-roof excitation on the source plate, the results show that compared to SEA, ASEA provides significantly better estimates of the receiver plate energy, but only where there are at least one or two bending modes in each one-third octave band. Whilst ASEA provides better accuracy than SEA, discrepancies still exist which become more apparent when the direct propagation path crosses more than three nominally identical structural junctions.

Model-based choices involve prospective neural activity

PubMed Central

Doll, Bradley B.; Duncan, Katherine D.; Simon, Dylan A.; Shohamy, Daphna; Daw, Nathaniel D.

2015-01-01

Decisions may arise via “model-free” repetition of previously reinforced actions, or by “model-based” evaluation, which is widely thought to follow from prospective anticipation of action consequences using a learned map or model. While choices and neural correlates of decision variables sometimes reflect knowledge of their consequences, it remains unclear whether this actually arises from prospective evaluation. Using functional MRI and a sequential reward-learning task in which paths contained decodable object categories, we found that humans’ model-based choices were associated with neural signatures of future paths observed at decision time, suggesting a prospective mechanism for choice. Prospection also covaried with the degree of model-based influences on neural correlates of decision variables, and was inversely related to prediction error signals thought to underlie model-free learning. These results dissociate separate mechanisms underlying model-based and model-free evaluation and support the hypothesis that model-based influences on choices and neural decision variables result from prospection. PMID:25799041

Visual Aids for Positive Behavior Support of Young Children with Autism Spectrum Disorders

ERIC Educational Resources Information Center

Kidder, Jaimee E.; McDonnell, Andrea P.

2017-01-01

Research suggests that many children with ASD are visual learners (Quill, 1997) and may struggle to comprehend expectations presented in a verbal mode only. Visually structured interventions present choices, expectations, tasks, and communication exchanges in a way that is appealing and approachable for visual learners. There are many types of…

Creating School Change: Discovering a Choice of Lenses for the School Administrator.

ERIC Educational Resources Information Center

Amatea, Ellen S.; And Others

1996-01-01

Proposes a variety of epistemological lenses for viewing the school change process for school administrators' use. Applies these lenses in an actual case study depicting school change, illustrating how administrators can shift focus, position, and mode of inquiry from their usual rational viewpoint. Analyzes implications of using such lenses for…

Element Research.

ERIC Educational Resources Information Center

Herald, Christine

2001-01-01

Describes a research assignment for 8th grade students on the elements of the periodic table. Students use web-based resources and a chemistry handbook to gather information, construct concept maps, and present the findings to the full class using the mode of their choice: a humorous story, a slideshow or gameboard, a brochure, a song, or skit.…

Quality Issues in Judging Portfolios: Implications for Organizing Teaching Portfolio Assessment Procedures

ERIC Educational Resources Information Center

Tigelaar, Dineke E. H.; Dolmans, Diana H. J. M.; Wolfhagen, Ineke H. A. P.; van der Vleuten, Cees P. M.

2005-01-01

This article addresses the choice of the most appropriate procedure for the assessment of portfolios used in teacher and lecturer assessment. A characteristic of modern assessment modes, including portfolios, is that the information they provide is often qualitative and derived from different contexts. Unambiguous, objective rating of portfolios…

Values: Jaundiced Perversions/Lucid Alternatives.

ERIC Educational Resources Information Center

Nissman, Albert

The American educational system must emphasize values education and the role of the teacher in instilling proper values. Within the context of this paper, values are the intrinsic regard people have for other people, ideas, attitudes, or modes of behavior. Values rest on a philosophical base and require the intellectual choice of the beholder.…

Technological Barriers to Success in Distance Education: The Revolving Door of Online Education

ERIC Educational Resources Information Center

Roe, Richard Thomas

2011-01-01

Taking online courses has become a delivery mode of choice for many students. This collaborative study focuses on the impact of college readiness; technological resources, and course design on student success in an online introduction to computers distance education course within the Kentucky Community and Technical College System (KCTCS). The…

Feedback is the breakfast of champions: the significance of self-controlled formal feedback for autonomous task engagement.

PubMed

Meng, Liang; Yang, Zijing

2018-01-03

With the aim of examining the positive effect of the formal feedback mechanism itself beyond its informational aspect, we engaged participants in the stopwatch task and recorded their electroencephalogram throughout the experiment. This task requires a button press to stop the watch within a given time interval, the completion of which is simultaneously accompanied by adequate information on task performance. In the self-controlled feedback mode, participants could freely choose whether to request formal feedback after completing the task. In another mode, additional feedback was not provided. The 'non-choice' cue was found to elicit a more negative cue-elicited feedback negativity compared with 'choice', suggesting that the opportunity to solicit formal feedback was perceived as more desirable. In addition, a more enhanced stimulus-preceding negativity was observed prior to the task initiation cue in the self-controlled feedback condition, indicating that participants paid more sustained anticipatory attention during task preparation. Taken together, these electrophysiological results suggested an inherent reward within the formal feedback mechanism itself and the significance of self-controlled formal feedback for autonomous task engagement.

Estimation of Channel-Forming Discharge and Large-Event Geomorphic Response Using HEC-RAS

NASA Astrophysics Data System (ADS)

Hamilton, P.; Strom, K.; Hosseiny, S. M. H.

2015-12-01

The goal of the present work was to consider the functionality and applicability of HEC-RAS sediment transport simulations in two situations. The first was as a mode for obtaining quick estimates of the effective discharge, one measure of channel-forming discharge, and the second was as a mode to quickly estimate sediment transport and the commensurate potential erosion and deposition during large flood events. Though there are many other sediment transport and morphodynamic models available, e.g., CCHE1D, Nays2DH, we were interested in using HEC-RAS since this is the model of choice for many regulatory bodies, e.g., FEMA, cities, and counties. This makes using the sediment transport capability of HEC-RAS a natural extension of models that already otherwise exist and are well calibrated. In first looking at the utility of these models, we wanted to estimate the effective discharge of streams. Effective discharge is one way of defining the channel-forming discharge for a stream and is therefore an important parameter in natural channel design and restoration efforts. By running this range of floods, one can easily obtain an estimate for recurrence interval most responsible for moving the majority of sediment over a long time period. Results were compared to data collected within our research group on the Brazos River (TX). Effective discharge is an important estimate, particularly in understanding the equilibrium channel condition. Nevertheless, large floods are contemporaneously catastrophic and understanding their potential effects is desirable. Finally, we performed some sensitivity analysis to better understand the underlying assumptions of the various sediment transport model options and how they might affect the outcome of the aforementioned computations.

Harvest choice and timber supply models for forest forecasting

Treesearch

Maksym Polyakov; David N Wear

2010-01-01

Timber supply has traditionally been modeled using aggregate data, whereas individual harvest choices have been shown to be sensitive to the vintage and condition of forest capital stocks. In this article, we build aggregate supply models for four roundwood products in a seven-state region of the US South directly from stand-level harvest choice models applied to...

Variation in Estimated Ozone-Related Health Impacts of Climate Change due to Modeling Choices and Assumptions

PubMed Central

Post, Ellen S.; Grambsch, Anne; Weaver, Chris; Morefield, Philip; Leung, Lai-Yung; Nolte, Christopher G.; Adams, Peter; Liang, Xin-Zhong; Zhu, Jin-Hong; Mahoney, Hardee

2012-01-01

Background: Future climate change may cause air quality degradation via climate-induced changes in meteorology, atmospheric chemistry, and emissions into the air. Few studies have explicitly modeled the potential relationships between climate change, air quality, and human health, and fewer still have investigated the sensitivity of estimates to the underlying modeling choices. Objectives: Our goal was to assess the sensitivity of estimated ozone-related human health impacts of climate change to key modeling choices. Methods: Our analysis included seven modeling systems in which a climate change model is linked to an air quality model, five population projections, and multiple concentration–response functions. Using the U.S. Environmental Protection Agency’s (EPA’s) Environmental Benefits Mapping and Analysis Program (BenMAP), we estimated future ozone (O3)-related health effects in the United States attributable to simulated climate change between the years 2000 and approximately 2050, given each combination of modeling choices. Health effects and concentration–response functions were chosen to match those used in the U.S. EPA’s 2008 Regulatory Impact Analysis of the National Ambient Air Quality Standards for O3. Results: Different combinations of methodological choices produced a range of estimates of national O3-related mortality from roughly 600 deaths avoided as a result of climate change to 2,500 deaths attributable to climate change (although the large majority produced increases in mortality). The choice of the climate change and the air quality model reflected the greatest source of uncertainty, with the other modeling choices having lesser but still substantial effects. Conclusions: Our results highlight the need to use an ensemble approach, instead of relying on any one set of modeling choices, to assess the potential risks associated with O3-related human health effects resulting from climate change. PMID:22796531

The Stay/Switch Model of Concurrent Choice

ERIC Educational Resources Information Center

MacDonall, James S.

2009-01-01

This experiment compared descriptions of concurrent choice by the stay/switch model, which says choice is a function of the reinforcers obtained for staying at and for switching from each alternative, and the generalized matching law, which says choice is a function of the total reinforcers obtained at each alternative. For the stay/switch model…

Eye Movements in Strategic Choice

PubMed Central

Gächter, Simon; Noguchi, Takao; Mullett, Timothy L.

2015-01-01

Abstract In risky and other multiattribute choices, the process of choosing is well described by random walk or drift diffusion models in which evidence is accumulated over time to threshold. In strategic choices, level‐k and cognitive hierarchy models have been offered as accounts of the choice process, in which people simulate the choice processes of their opponents or partners. We recorded the eye movements in 2 × 2 symmetric games including dominance‐solvable games like prisoner's dilemma and asymmetric coordination games like stag hunt and hawk–dove. The evidence was most consistent with the accumulation of payoff differences over time: we found longer duration choices with more fixations when payoffs differences were more finely balanced, an emerging bias to gaze more at the payoffs for the action ultimately chosen, and that a simple count of transitions between payoffs—whether or not the comparison is strategically informative—was strongly associated with the final choice. The accumulator models do account for these strategic choice process measures, but the level‐k and cognitive hierarchy models do not. © 2015 The Authors. Journal of Behavioral Decision Making published by John Wiley & Sons Ltd. PMID:27513881

Predicting the emergence of H3N2 influenza viruses reveals contrasted modes of evolution of HA and NA antigens.

PubMed

Sandie, Reatha; Aris-Brosou, Stéphane

2014-01-01

Vaccine design for rapidly changing viruses is based on empirical surveillance of strains circulating in a given season to assess those that will most likely spread during the next season. The choice of which strains to include in the vaccine is critical, as an erroneous decision can lead to a nonimmunized human population that will then be at risk in the face of an epidemic or, worse, a pandemic. Here, we present the first steps toward a very general phylogenetic approach to predict the emergence of novel viruses. Our genomic model builds upon natural features of viral evolution such as selection and recombination / reassortment, and incorporates episodic bursts of evolution and or of recombination. As a proof-of-concept, we assess the performance of this model in a retrospective study, focusing: (i) on the emergence of an unexpected H3N2 influenza strain in 2007, and (ii) on a longitudinal design. Based on the analysis of hemagglutinin (HA) and neuraminidase (NA) genes, our results show a lack of predictive power in both experimental designs, but shed light on the mode of evolution of these two antigens: (i) supporting the lack of significance of recombination in the evolution of this influenza virus, and (ii) showing that HA evolves episodically while NA changes gradually.

Some implications of Scale Relativity theory in avascular stages of growth of solid tumors in the presence of an immune system response.

PubMed

Buzea, C Gh; Agop, M; Moraru, Evelina; Stana, Bogdan A; Gîrţu, Manuela; Iancu, D

2011-08-07

We present a traveling-wave analysis of a reduced mathematical model describing the growth of a solid tumor in the presence of an immune system response in the framework of Scale Relativity theory. Attention is focused upon the attack of tumor cells by tumor-infiltrating cytotoxic lymphocytes (TICLs), in a small multicellular tumor, without necrosis and at some stage prior to (tumor-induced) angiogenesis. For a particular choice of parameters, the underlying system of partial differential equations is able to simulate the well-documented phenomenon of cancer dormancy and propagation of a perturbation in the tumor cell concentration by cnoidal modes, by depicting spatially heterogeneous tumor cell distributions that are characterized by a relatively small total number of tumor cells. This behavior is consistent with several immunomorphological investigations. Moreover, the alteration of certain parameters of the model is enough to induce soliton like modes and soliton packets into the system, which in turn result in tumor invasion in the form of a standard traveling wave. In the same framework of Scale Relativity theory, a very important feature of malignant tumors also results, that even in avascular stages they might propagate and invade healthy tissues, by means of a diffusion on a Newtonian fluid. Copyright © 2011 Elsevier Ltd. All rights reserved.

A Comparison of Filter-based Approaches for Model-based Prognostics

NASA Technical Reports Server (NTRS)

Daigle, Matthew John; Saha, Bhaskar; Goebel, Kai

2012-01-01

Model-based prognostics approaches use domain knowledge about a system and its failure modes through the use of physics-based models. Model-based prognosis is generally divided into two sequential problems: a joint state-parameter estimation problem, in which, using the model, the health of a system or component is determined based on the observations; and a prediction problem, in which, using the model, the stateparameter distribution is simulated forward in time to compute end of life and remaining useful life. The first problem is typically solved through the use of a state observer, or filter. The choice of filter depends on the assumptions that may be made about the system, and on the desired algorithm performance. In this paper, we review three separate filters for the solution to the first problem: the Daum filter, an exact nonlinear filter; the unscented Kalman filter, which approximates nonlinearities through the use of a deterministic sampling method known as the unscented transform; and the particle filter, which approximates the state distribution using a finite set of discrete, weighted samples, called particles. Using a centrifugal pump as a case study, we conduct a number of simulation-based experiments investigating the performance of the different algorithms as applied to prognostics.

Smooth and flat phase-locked Kerr frequency comb generation by higher order mode suppression

PubMed Central

Huang, S.-W.; Liu, H.; Yang, J.; Yu, M.; Kwong, D.-L.; Wong, C. W.

2016-01-01

High-Q microresonator is perceived as a promising platform for optical frequency comb generation, via dissipative soliton formation. In order to achieve a higher quality factor and obtain the necessary anomalous dispersion, multi-mode waveguides were previously implemented in Si3N4 microresonators. However, coupling between different transverse mode families in multi-mode waveguides results in periodic disruption of dispersion and quality factor, and consequently causes perturbation to dissipative soliton formation and amplitude modulation to the corresponding spectrum. Careful choice of pump wavelength to avoid the mode crossing region is thus critical in conventional Si3N4 microresonators. Here, we report a novel design of Si3N4 microresonator in which single-mode operation, high quality factor, and anomalous dispersion are attained simultaneously. The novel microresonator is consisted of uniform single-mode waveguides in the semi-circle region, to eliminate bending induced mode coupling, and adiabatically tapered waveguides in the straight region, to avoid excitation of higher order modes. The intrinsic quality factor of the microresonator reaches 1.36 × 106 while the group velocity dispersion remains to be anomalous at −50 fs2/mm. With this novel microresonator, we demonstrate that broadband phase-locked Kerr frequency combs with flat and smooth spectra can be generated by pumping at any resonances in the optical C-band. PMID:27181420

Comparative study of various normal mode analysis techniques based on partial Hessians.

PubMed

Ghysels, An; Van Speybroeck, Veronique; Pauwels, Ewald; Catak, Saron; Brooks, Bernard R; Van Neck, Dimitri; Waroquier, Michel

2010-04-15

Standard normal mode analysis becomes problematic for complex molecular systems, as a result of both the high computational cost and the excessive amount of information when the full Hessian matrix is used. Several partial Hessian methods have been proposed in the literature, yielding approximate normal modes. These methods aim at reducing the computational load and/or calculating only the relevant normal modes of interest in a specific application. Each method has its own (dis)advantages and application field but guidelines for the most suitable choice are lacking. We have investigated several partial Hessian methods, including the Partial Hessian Vibrational Analysis (PHVA), the Mobile Block Hessian (MBH), and the Vibrational Subsystem Analysis (VSA). In this article, we focus on the benefits and drawbacks of these methods, in terms of the reproduction of localized modes, collective modes, and the performance in partially optimized structures. We find that the PHVA is suitable for describing localized modes, that the MBH not only reproduces localized and global modes but also serves as an analysis tool of the spectrum, and that the VSA is mostly useful for the reproduction of the low frequency spectrum. These guidelines are illustrated with the reproduction of the localized amine-stretch, the spectrum of quinine and a bis-cinchona derivative, and the low frequency modes of the LAO binding protein. 2009 Wiley Periodicals, Inc.

Comparative Study of Various Normal Mode Analysis Techniques Based on Partial Hessians

PubMed Central

GHYSELS, AN; VAN SPEYBROECK, VERONIQUE; PAUWELS, EWALD; CATAK, SARON; BROOKS, BERNARD R.; VAN NECK, DIMITRI; WAROQUIER, MICHEL

2014-01-01

Standard normal mode analysis becomes problematic for complex molecular systems, as a result of both the high computational cost and the excessive amount of information when the full Hessian matrix is used. Several partial Hessian methods have been proposed in the literature, yielding approximate normal modes. These methods aim at reducing the computational load and/or calculating only the relevant normal modes of interest in a specific application. Each method has its own (dis)advantages and application field but guidelines for the most suitable choice are lacking. We have investigated several partial Hessian methods, including the Partial Hessian Vibrational Analysis (PHVA), the Mobile Block Hessian (MBH), and the Vibrational Subsystem Analysis (VSA). In this article, we focus on the benefits and drawbacks of these methods, in terms of the reproduction of localized modes, collective modes, and the performance in partially optimized structures. We find that the PHVA is suitable for describing localized modes, that the MBH not only reproduces localized and global modes but also serves as an analysis tool of the spectrum, and that the VSA is mostly useful for the reproduction of the low frequency spectrum. These guidelines are illustrated with the reproduction of the localized amine-stretch, the spectrum of quinine and a bis-cinchona derivative, and the low frequency modes of the LAO binding protein. PMID:19813181

Beam asymmetry Σ in η' photoproduction off the proton at the GRAAL experiment

NASA Astrophysics Data System (ADS)

Mandaglio, G.; Bellini, V.; Bocquet, J. P.; Capogni, M.; Curciarello, F.; D'Angelo, A.; De Leo, V.; Didelez, J. P.; Di Salvo, R.; Fantini, A.; Franco, D.; Gervino, G.; Ghio, F.; Giardina, G.; Girolami, B.; Lapik, A. M.; Levi Sandri, P.; Lleres, A.; Mammoliti, F.; Manganaro, M.; Moricciani, D.; Mushkarenkov, A. N.; Nedorezov, V. G.; Rebreyend, D.; Rudnev, N. V.; Schaerf, C.; Sperduto, M. L.; Sutera, M. C.; Turinge, A.; Vegna, V.; Zonta, I.

2014-06-01

The only recent η' photoproduction data off proton available in literature are the differential and total cross sections published by the CLAS and CB-ELSA-TAPS Collaborations. However, the wide information about reaction cross sections are not sufficient to understand the role of resonances involved in the process. Different theoretical works stressed the importance to measure also polarization observables in order to solve the ambiguities in the choice of the parameters used in their models. We present the analysis of η' photoproduction off the proton analysis, identifying the investigated meson by the π+π-η, π0π0η, and γγ decay modes by using the GRAAL apparatus; and we show the preliminary GRAAL results on the beam asymmetry Σ at beam energy of 1475 MeV.

A theory of the Io phase asymmetry of the Jovian decametric radiation

NASA Technical Reports Server (NTRS)

Hashimoto, K.; Goldstein, M. L.

1982-01-01

An explanation of an asymmetry in the occurrence probability of the Io-dependent Jovian decametric radiation is proposed. Io generates stronger Alfven waves toward the south when it is in the northern part of the torus. This wave then generates decametric radiation in the northern ionosphere after it reflects in the southern ionosphere. The asymmetry then results from computing the propagation time of the alfven wave along this trajectory. The ray paths of the decameter radiation are calculated using a three dimensional ray tracing program in the Jovian ionosphere. Variations in the expected probability plots are computer for two models of the Jovian ionosphere and global magnetic field, as well as for several choices of the ratio of the radiated frequency to the X-mode cutoff frequency.

Children's Conceptions of Career Choice and Attainment: Model Development

ERIC Educational Resources Information Center

Howard, Kimberly A. S.; Walsh, Mary E.

2011-01-01

This article describes a model of children's conceptions of two key career development processes: career choice and career attainment. The model of children's understanding of career choice and attainment was constructed with developmental research and theory into children's understanding of allied phenomena such as their understanding of illness,…

Women's preferences and mode of delivery in public and private hospitals: a prospective cohort study.

PubMed

Mazzoni, Agustina; Althabe, Fernando; Gutierrez, Laura; Gibbons, Luz; Liu, Nancy H; Bonotti, Ana María; Izbizky, Gustavo H; Ferrary, Marta; Viergue, Nora; Vigil, Silvia I; Zalazar Denett, Gabriela; Belizán, José M

2016-02-08

Rates of caesarean section have steadily increased in most middle- and high-income countries over the last few decades without medical justification. Maternal request is one of the frequently cited non-medical factors contributing to this trend. The objectives of this study were to assess pregnant women's preferences regarding mode of delivery and to compare actual caesarean section rates in the public and private sectors. A prospective cohort study was conducted in two public and three private hospitals in Buenos Aires, Argentina. 382 nulliparous pregnant women (183 from the private sector and 199 from the public sector) aged 18 to 35 years, with single pregnancies over 32 weeks of gestational age were enrolled during antenatal care visits between October 2010 and September 2011. We excluded women with pregnancies resulting from assisted fertility, women with known pre-existing major diseases or, with pregnancy complications, or with a medical indication of elective cesarean section. We used two different approaches to assess women's preferences: a survey using a tailored questionnaire, and a discrete choice experiment. Only 8 and 6% of the healthy nulliparous women in the public and private sectors, respectively, expressed a preference for caesarean section. Fear of pain and safety were the most frequently expressed reasons for preferring caesarean section. When reasons for delivery mode were assessed by a discrete choice experiment, women placed the most emphasis on sex after childbirth. Of women who expressed their preference for vaginal delivery, 34 and 40% ended their pregnancies by caesarean section in public and private hospitals, respectively. The preference for caesarean section is low among healthy nulliparous women in Buenos Aires. The reasons why these women had a rate of more than 35% caesarean sections are unlikely related to their preferences for mode of delivery.

Application of failure mode and effects analysis (FMEA) to pretreatment phases in tomotherapy

PubMed Central

Broggi, Sara; Cantone, Marie Claire; Chiara, Anna; Muzio, Nadia Di; Longobardi, Barbara; Mangili, Paola

2013-01-01

The aim of this paper was the application of the failure mode and effects analysis (FMEA) approach to assess the risks for patients undergoing radiotherapy treatments performed by means of a helical tomotherapy unit. FMEA was applied to the preplanning imaging, volume determination, and treatment planning stages of the tomotherapy process and consisted of three steps: 1) identification of the involved subprocesses; 2) identification and ranking of the potential failure modes, together with their causes and effects, using the risk probability number (RPN) scoring system; and 3) identification of additional safety measures to be proposed for process quality and safety improvement. RPN upper threshold for little concern of risk was set at 125. A total of 74 failure modes were identified: 38 in the stage of preplanning imaging and volume determination, and 36 in the stage of planning. The threshold of 125 for RPN was exceeded in four cases: one case only in the phase of preplanning imaging and volume determination, and three cases in the stage of planning. The most critical failures appeared related to (i) the wrong or missing definition and contouring of the overlapping regions, (ii) the wrong assignment of the overlap priority to each anatomical structure, (iii) the wrong choice of the computed tomography calibration curve for dose calculation, and (iv) the wrong (or not performed) choice of the number of fractions in the planning station. On the basis of these findings, in addition to the safety strategies already adopted in the clinical practice, novel solutions have been proposed for mitigating the risk of these failures and to increase patient safety. PACS number: 87.55.Qr PMID:24036868

Standards and Stories: The Interactional Work of Informed Choice in Ontario Midwifery Care

PubMed Central

Spoel, Philippa; Mckenzie, Pamela; James, Susan; Hobberlin, Jessica

2013-01-01

This paper uses a discourse-rhetorical approach to analyze how Ontario midwives and their clients interactionally accomplish the healthcare communicative process of «informed choice.» Working with four excerpts from recorded visits between Ontario midwives and women, the analysis focuses on the discursive rendering during informed choice conversations of two contrasting kinds of evidence — professional standards and story-telling — related to potential interventions during labour. We draw on the concepts of discursive hybridity (Sarangi and Roberts 1999) and recontextualization (Linell 1998; Sarangi 1998) to trace the complex and creative ways in which the conversational participants reconstruct the meanings of these evidentiary sources to address their particular care contexts. This analysis shows how, though very different in their forms, both modes of evidence function as hybrid and flexible discursive resources that perform both instrumental and social-relational healthcare work. PMID:24289941

Human X-chromosome inactivation pattern distributions fit a model of genetically influenced choice better than models of completely random choice

PubMed Central

Renault, Nisa K E; Pritchett, Sonja M; Howell, Robin E; Greer, Wenda L; Sapienza, Carmen; Ørstavik, Karen Helene; Hamilton, David C

2013-01-01

In eutherian mammals, one X-chromosome in every XX somatic cell is transcriptionally silenced through the process of X-chromosome inactivation (XCI). Females are thus functional mosaics, where some cells express genes from the paternal X, and the others from the maternal X. The relative abundance of the two cell populations (X-inactivation pattern, XIP) can have significant medical implications for some females. In mice, the ‘choice' of which X to inactivate, maternal or paternal, in each cell of the early embryo is genetically influenced. In humans, the timing of XCI choice and whether choice occurs completely randomly or under a genetic influence is debated. Here, we explore these questions by analysing the distribution of XIPs in large populations of normal females. Models were generated to predict XIP distributions resulting from completely random or genetically influenced choice. Each model describes the discrete primary distribution at the onset of XCI, and the continuous secondary distribution accounting for changes to the XIP as a result of development and ageing. Statistical methods are used to compare models with empirical data from Danish and Utah populations. A rigorous data treatment strategy maximises information content and allows for unbiased use of unphased XIP data. The Anderson–Darling goodness-of-fit statistics and likelihood ratio tests indicate that a model of genetically influenced XCI choice better fits the empirical data than models of completely random choice. PMID:23652377

Influences That Affect First-Generation College Students' College Choice: A Qualitative Inquiry of Student Perceptions

ERIC Educational Resources Information Center

Cresswell-Yeager, Tiffany J.

2012-01-01

College choice is the three-stage process of aspiring, searching and choosing to attend college. There are many models pertaining to college choice, however, this study uses the Hossler and Gallagher Model---aspiration, search and choice. This qualitative study explored first-generation college students' perceptions about the influences…

Tandem mass spectrometry characteristics of polyester anions and cations formed by electrospray ionization.

PubMed

Arnould, Mark A; Buehner, Rita W; Wesdemiotis, Chrys; Vargas, Rafael

2005-01-01

Electrospray ionization of polyesters composed of isophthalic acid and neopentyl glycol produces carboxylate anions in negative mode and mainly sodium ion adducts in positive mode. A tandem mass spectrometry (MS/MS) study of these ions in a quadrupole ion trap shows that the collisionally activated dissociation pathways of the anions are simpler than those of the corresponding cations. Charge-remote fragmentations predominate in both cases, but the spectra obtained in negative mode are devoid of the complicating cation exchange observed in positive mode. MS/MS of the Na(+) adducts gives rise to a greater number of fragments but not necessarily more structural information. In either positive or negative mode, polyester oligomers with different end groups fragment by similar mechanisms. The observed fragments are consistent with rearrangements initiated by the end groups. Single-stage ESI mass spectra also are more complex in positive mode because of extensive H/Na substitutions; this is also true for matrix-assisted laser desorption ionization (MALDI) mass spectra. Hence, formation and analysis of anions might be the method of choice for determining block length, end group structure and copolymer sequence, provided the polyester contains at least one carboxylic acid end group that is ionizable to anions.

Medical students’ personal choice for mode of delivery in Santa Catarina, Brazil: a cross-sectional, quantitative study

PubMed Central

2012-01-01

Background The increase in overall rates of cesarean sections (CS) in Brazil causes concern and it appears that multiple factors are involved in this fact. In 2009, undergraduate students in the first and final years of medical school at the University of Santa Catarina answered questionnaires regarding their choice of mode of delivery. The aim of the study was to evaluate whether the education process affects decision-making regarding the waay of childbirth preferred by medical students. Methods A cross-sectional, quantitative study was conducted based on data obtained from questionnaires applied to medical students. The questions addressed four different scenarios in childbirth, as follows: under an uneventful pregnancy; the mode of delivery for a pregnant woman under their care; the best choice as a healthcare manager and lastly, choosing the birth of their own child. For each circumstance, there was an open question to explain their choice. Results A total of 189 students answered the questionnaires. For any uneventful pregnancy and for a pregnant woman under their care, 8.46% of the students would opt for CS. As a healthcare manager, only 2.64% of the students would recommend CS. For these three scenarios, the answers of the students in the first year did not differ from those given by students in the sixth year. In the case of the student’s own or a partner’s pregnancy, 41.4% of those in the sixth year and 16.8% of those in the first year would choose a CS. A positive association was found between being a sixth year student and a personal preference for CS according to logistic regression (OR = 2.91; 95%CI: 1.03–8.30). Pain associated with vaginal delivery was usually the reason for choosing a CS. Conclusions A higher number of sixth year students preferred a CS for their own pregnancy (or their partner’s) compared to first year students. Pain associated with vaginal delivery was the most common reason given for haven chosen a CS. The students’ preference for childbirth changed over time during their graduation in favor of cesarean sections. This finding deserves considerable attention when structuring medical education in Obstetrics. PMID:22818043

How the twain can meet: Prospect theory and models of heuristics in risky choice.

PubMed

Pachur, Thorsten; Suter, Renata S; Hertwig, Ralph

2017-03-01

Two influential approaches to modeling choice between risky options are algebraic models (which focus on predicting the overt decisions) and models of heuristics (which are also concerned with capturing the underlying cognitive process). Because they rest on fundamentally different assumptions and algorithms, the two approaches are usually treated as antithetical, or even incommensurable. Drawing on cumulative prospect theory (CPT; Tversky & Kahneman, 1992) as the currently most influential instance of a descriptive algebraic model, we demonstrate how the two modeling traditions can be linked. CPT's algebraic functions characterize choices in terms of psychophysical (diminishing sensitivity to probabilities and outcomes) as well as psychological (risk aversion and loss aversion) constructs. Models of heuristics characterize choices as rooted in simple information-processing principles such as lexicographic and limited search. In computer simulations, we estimated CPT's parameters for choices produced by various heuristics. The resulting CPT parameter profiles portray each of the choice-generating heuristics in psychologically meaningful ways-capturing, for instance, differences in how the heuristics process probability information. Furthermore, CPT parameters can reflect a key property of many heuristics, lexicographic search, and track the environment-dependent behavior of heuristics. Finally, we show, both in an empirical and a model recovery study, how CPT parameter profiles can be used to detect the operation of heuristics. We also address the limits of CPT's ability to capture choices produced by heuristics. Our results highlight an untapped potential of CPT as a measurement tool to characterize the information processing underlying risky choice. Copyright © 2017 Elsevier Inc. All rights reserved.

A Common Mechanism Underlying Food Choice and Social Decisions.

PubMed

Krajbich, Ian; Hare, Todd; Bartling, Björn; Morishima, Yosuke; Fehr, Ernst

2015-10-01

People make numerous decisions every day including perceptual decisions such as walking through a crowd, decisions over primary rewards such as what to eat, and social decisions that require balancing own and others' benefits. The unifying principles behind choices in various domains are, however, still not well understood. Mathematical models that describe choice behavior in specific contexts have provided important insights into the computations that may underlie decision making in the brain. However, a critical and largely unanswered question is whether these models generalize from one choice context to another. Here we show that a model adapted from the perceptual decision-making domain and estimated on choices over food rewards accurately predicts choices and reaction times in four independent sets of subjects making social decisions. The robustness of the model across domains provides behavioral evidence for a common decision-making process in perceptual, primary reward, and social decision making.

A Common Mechanism Underlying Food Choice and Social Decisions

PubMed Central

Krajbich, Ian; Hare, Todd; Bartling, Björn; Morishima, Yosuke; Fehr, Ernst

2015-01-01

People make numerous decisions every day including perceptual decisions such as walking through a crowd, decisions over primary rewards such as what to eat, and social decisions that require balancing own and others’ benefits. The unifying principles behind choices in various domains are, however, still not well understood. Mathematical models that describe choice behavior in specific contexts have provided important insights into the computations that may underlie decision making in the brain. However, a critical and largely unanswered question is whether these models generalize from one choice context to another. Here we show that a model adapted from the perceptual decision-making domain and estimated on choices over food rewards accurately predicts choices and reaction times in four independent sets of subjects making social decisions. The robustness of the model across domains provides behavioral evidence for a common decision-making process in perceptual, primary reward, and social decision making. PMID:26460812

There's no such thing as bad weather, just the wrong clothing: climate, weather and active school transportation in Toronto, Canada.

PubMed

Mitra, Raktim; Faulkner, Guy

2012-07-10

Climatic conditions may enable or deter active school transportation in many North American cities, but the topic remains largely overlooked in the existing literature. This study explores the effect of seasonal climate (i.e., fall versus winter) and weekly weather conditions (i.e., temperature, precipitation) on active travelling to school across different built and policy environments. Home-to-school trips by 11-12-year-old children in the City of Toronto were examined using data from the 2006 Transportation Tomorrow Survey. Binomial logistic regressions were estimated to explore the correlates of the choice of active (i.e., walking) versus non-active (i.e., private automobile, transit and school bus) mode for school trips. Climate and weather-related variables were not associated with choice of school travel mode. Children living within the sidewalk snow-plough zone (i.e., in the inner-suburban neighbourhoods) were less likely to walk to school than children living outside of the zone (i.e., in the inner-city neighbourhoods). Given that seasonality and short-term weather conditions appear not to limit active school transportation in general, built environment interventions designed to facilitate active travel could have benefits that spill over across the entire year rather than being limited to a particular season. Educational campaigns with strategies for making the trip fun and ensuring that the appropriate clothing choices are made are also warranted in complementing built environment modifications.

Estimation of an Occupational Choice Model when Occupations Are Misclassified

ERIC Educational Resources Information Center

Sullivan, Paul

2009-01-01

This paper develops an empirical occupational choice model that corrects for misclassification in occupational choices and measurement error in occupation-specific work experience. The model is used to estimate the extent of measurement error in occupation data and quantify the bias that results from ignoring measurement error in occupation codes…

Analysis of strength-of-preference measures in dichotomous choice models

Treesearch

Donald F. Dennis; Peter Newman; Robert Manning

2008-01-01

Choice models are becoming increasingly useful for soliciting and analyzing multiple objective decisions faced by recreation managers and others interested in decisions involving natural resources. Choice models are used to estimate relative values for multiple aspects of natural resource management, not individually but within the context of other relevant decision...

From Recurrent Choice to Skill Learning: A Reinforcement-Learning Model

ERIC Educational Resources Information Center

Fu, Wai-Tat; Anderson, John R.

2006-01-01

The authors propose a reinforcement-learning mechanism as a model for recurrent choice and extend it to account for skill learning. The model was inspired by recent research in neurophysiological studies of the basal ganglia and provides an integrated explanation of recurrent choice behavior and skill learning. The behavior includes effects of…

Mechanisms underlying the influence of saliency on value-based decisions

PubMed Central

Chen, Xiaomo; Mihalas, Stefan; Niebur, Ernst; Stuphorn, Veit

2013-01-01

Objects in the environment differ in their low-level perceptual properties (e.g., how easily a fruit can be recognized) as well as in their subjective value (how tasty it is). We studied the influence of visual salience on value-based decisions using a two alternative forced choice task, in which human subjects rapidly chose items from a visual display. All targets were equally easy to detect. Nevertheless, both value and salience strongly affected choices made and reaction times. We analyzed the neuronal mechanisms underlying these behavioral effects using stochastic accumulator models, allowing us to characterize not only the averages of reaction times but their full distributions. Independent models without interaction between the possible choices failed to reproduce the observed choice behavior, while models with mutual inhibition between alternative choices produced much better results. Mutual inhibition thus is an important feature of the decision mechanism. Value influenced the amount of accumulation in all models. In contrast, increased salience could either lead to an earlier start (onset model) or to a higher rate (speed model) of accumulation. Both models explained the data from the choice trials equally well. However, salience also affected reaction times in no-choice trials in which only one item was present, as well as error trials. Only the onset model could explain the observed reaction time distributions of error trials and no-choice trials. In contrast, the speed model could not, irrespective of whether the rate increase resulted from more frequent accumulated quanta or from larger quanta. Visual salience thus likely provides an advantage in the onset, not in the processing speed, of value-based decision making. PMID:24167161

Think twice before you book? Modelling the choice of public vs private dentist in a choice experiment.

PubMed

Kiiskinen, Urpo; Suominen-Taipale, Anna Liisa; Cairns, John

2010-06-01

This study concerns the choice of primary dental service provider by consumers. If the health service delivery system allows individuals to choose between public-care providers or if complementary private services are available, it is typically assumed that utilisation is a three-stage decision process. The patient first makes a decision to seek care, and then chooses the service provider. The final stage, involving decisions over the amount and form of treatment, is not considered here. The paper reports a discrete choice experiment (DCE) designed to evaluate attributes affecting individuals' choice of dental-care provider. The feasibility of the DCE approach in modelling consumers' choice in the context of non-acute need for dental care is assessed. The aim is to test whether a separate two-stage logit, a multinomial logit, or a nested logit best fits the choice process of consumers. A nested logit model of indirect utility functions is estimated and inclusive value (IV) constraints are tested for modelling implications. The results show that non-trading behaviour has an impact on the choice of appropriate modelling technique, but is to some extent dependent on the choice of scenarios offered. It is concluded that for traders multinomial logit is appropriate, whereas for non-traders and on average the nested logit is the method supported by the analyses. The consistent finding in all subgroup analyses is that the traditional two-stage decision process is found to be implausible in the context of consumer's choice of dental-care provider.

Fitting observed and theoretical choices - women's choices about prenatal diagnosis of Down syndrome.

PubMed

Seror, Valerie

2008-05-01

Choices regarding prenatal diagnosis of Down syndrome - the most frequent chromosomal defect - are particularly relevant to decision analysis, since women's decisions are based on the assessment of their risk of carrying a child with Down syndrome, and involve tradeoffs (giving birth to an affected child vs procedure-related miscarriage). The aim of this study, based on face-to-face interviews with 78 women aged 25-35 with prior experience of pregnancy, was to compare the women' expressed choices towards prenatal diagnosis with those derived from theoretical models of choice (expected utility theory, rank-dependent theory, and cumulative prospect theory). The main finding obtained in this study was that the cumulative prospect model fitted the observed choices best: both subjective transformation of probabilities and loss aversion, which are basic features of the cumulative prospect model, have to be taken into account to make the observed choices consistent with the theoretical ones.

Mode of delivery affected questionnaire response rates in a birth cohort study.

PubMed

Bray, Isabelle; Noble, Sian; Robinson, Ross; Molloy, Lynn; Tilling, Kate

2017-01-01

Cohort studies must collect data from their participants as economically as possible, while maintaining response rates. This randomized controlled trial investigated whether offering a choice of online or paper questionnaires resulted in improved response rates compared with offering online first. Eligible participants were young people in the Avon Longitudinal Study of Parents and Children (ALSPAC) study (born April 1, 1991, to December 31, 1992, in the Avon area). After exclusions, 8,795 participants were randomized. The "online first" group were invited to complete the questionnaire online. The "choice" group were also sent a paper questionnaire and offered a choice of completion method. The trial was embedded within routine data collection. The main outcome measure was the number of questionnaires returned. Data on costs were also collected. Those in the "online first" arm of the trial were less likely to return a questionnaire [adjusted odds ratio: 0.90; 95% confidence interval (CI): 0.82, 0.99]. The "choice" arm was more expensive (mean difference per participant £0.71; 95% CI: £0.65, £0.76). It cost an extra £47 to have one extra person to complete the questionnaire in the "choice" arm. Offering a choice of completion methods (paper or online) for questionnaires in ALSPAC increased response rates but was more expensive than offering online first. Copyright © 2016 The Author(s). Published by Elsevier Inc. All rights reserved.

Changing choices in health care: implications for equity, efficiency and cost.

PubMed

Bevan, Gwyn; Helderman, Jan-Kees; Wilsford, David

2010-07-01

Although choice may be seen as an end in itself, the papers included in this special issue of Health Economics, Policy and Law, examine choice policies in European systems of health care, which aim to be effective instruments for ameliorating the systemic pressures from the iron triangle of equity, efficiency, and cost. Three papers consider the nature of differences between and within countries following the Beveridge and Bismarck models of financing and organising the delivery of care, and how choices are changing within different systems. Within countries following the Beveridge model, current policies in England, Denmark and Sweden emphasise increasing patient choice of provider. Within countries following the Bismarck model, current policies in France and Germany seek to restrict choice of specialists by introducing 'soft' gatekeeping; and in the Netherlands there is a system of managed competition with choice of insurer that, in principle, allows insurers to contract selectively with providers. A fourth paper considers how government policies that seek to restrict choice within systems of universal coverage have been subject to challenges in the courts. A commentary explores the implications of the fraught and complex nature of choices between insurers and providers of health care for designing effective choice policies.

Constructing food choice decisions.

PubMed

Sobal, Jeffery; Bisogni, Carole A

2009-12-01

Food choice decisions are frequent, multifaceted, situational, dynamic, and complex and lead to food behaviors where people acquire, prepare, serve, give away, store, eat, and clean up. Many disciplines and fields examine decision making. Several classes of theories are applicable to food decision making, including social behavior, social facts, and social definition perspectives. Each offers some insights but also makes limiting assumptions that prevent fully explaining food choice decisions. We used constructionist social definition perspectives to inductively develop a food choice process model that organizes a broad scope of factors and dynamics involved in food behaviors. This food choice process model includes (1) life course events and experiences that establish a food choice trajectory through transitions, turning points, timing, and contexts; (2) influences on food choices that include cultural ideals, personal factors, resources, social factors, and present contexts; and (3) a personal system that develops food choice values, negotiates and balances values, classifies foods and situations, and forms/revises food choice strategies, scripts, and routines. The parts of the model dynamically interact to make food choice decisions leading to food behaviors. No single theory can fully explain decision making in food behavior. Multiple perspectives are needed, including constructionist thinking.

Understanding Predisposition in College Choice: Toward an Integrated Model of College Choice and Theory of Reasoned Action

ERIC Educational Resources Information Center

Pitre, Paul E.; Johnson, Todd E.; Pitre, Charisse Cowan

2006-01-01

This article seeks to improve traditional models of college choice that draw from recruitment and enrollment management paradigms. In adopting a consumer approach to college choice, this article seeks to build upon consumer-related research, which centers on behavior and reasoning. More specifically, this article seeks to move inquiry beyond the…

Mate-choice copying in single and coupled women: the influence of mate acceptance and mate rejection decisions of other women.

PubMed

Deng, Yan; Zheng, Yong

2015-01-26

Studies of humans and non-human animals indicate that females tend to change the likelihood of choosing a potential mate based on the decisions of other females; this is known as mate-choice copying. In a sample of both single and coupled women, we examined the influence of other women's (model) mate-choice decisions, including mate acceptance and mate rejection, on participants' attractiveness ratings of men (target) and willingness of mate selection. We also examined whether different types of relationships between the target men and the model women affected mate-choice copying. We found that both the single and coupled women showed mate-choice copying, but their response patterns differed. The significant effects for single women were dependent on a decrease in attractiveness ratings when they perceived the models' mate rejection. However, the significant findings for coupled women relied on an increase in attractiveness ratings when they observed the models' mate acceptance. Furthermore, the relationship status between the target men and the model women affected the magnitude of mate-choice copying effects for the single women. Specifically, they showed less mate-choice copying when the targets and models were in a committed romantic relationship than when in a temporary relationship.

Value-based choice: An integrative, neuroscience-informed model of health goals.

PubMed

Berkman, Elliot T

2018-01-01

Traditional models of health behaviour focus on the roles of cognitive, personality and social-cognitive constructs (e.g. executive function, grit, self-efficacy), and give less attention to the process by which these constructs interact in the moment that a health-relevant choice is made. Health psychology needs a process-focused account of how various factors are integrated to produce the decisions that determine health behaviour. I present an integrative value-based choice model of health behaviour, which characterises the mechanism by which a variety of factors come together to determine behaviour. This model imports knowledge from research on behavioural economics and neuroscience about how choices are made to the study of health behaviour, and uses that knowledge to generate novel predictions about how to change health behaviour. I describe anomalies in value-based choice that can be exploited for health promotion, and review neuroimaging evidence about the involvement of midline dopamine structures in tracking and integrating value-related information during choice. I highlight how this knowledge can bring insights to health psychology using illustrative case of healthy eating. Value-based choice is a viable model for health behaviour and opens new avenues for mechanism-focused intervention.

Instrumental Techniques: Guitar, Course Number: Music: 5631.3-3.

ERIC Educational Resources Information Center

Bennitt, Barth; Thum, Marie-Jo

A course which is an introduction to music emphasizing modes and forms is outlined. Objectives include: (1) The student will select the title of a familiar melody from a list provided; (2) The student will identify by ear the performing medium from the following choices: violin, voice, piano, guitar, clarinet, trombone, organ, string bass,…

Do Modes of Thinking Predict Career Interest Types among Chinese University Students?

ERIC Educational Resources Information Center

Zhang, Li-fang; Fan, Weiqiao

2007-01-01

This study had two objectives. The preliminary objective was to further test the psychometric properties of the short-version self-directed search that was intended to be a brief research tool for measuring Holland [Holland, J. L. (1973). "Making vocational choices: A theory of careers." Englewood Cliffs, NJ: Prentice-Hall; Holland, J.…

Articulating Choice and Deliberation in Conducting Research--Researchers "Working in the Interpretive Zone"

ERIC Educational Resources Information Center

Tillema, Harm H.; Barak, Lily Orland; Marcos, Juan Jose Mena

2008-01-01

For researchers, committed to a research problem, finding meaningful answers is a process of careful weighting and interpreting what is actually found as an outcome of their mode of inquiry in reference to initial intentions and research goals. Particularly in doing qualitative research in/on teaching researchers have recognised the need to…

Comprehension of Ambiguous and Other Polysemous Utterances: Presented in Written Mode.

ERIC Educational Resources Information Center

Brause, Rita S.

Designed to assess comprehension of written ambiguous and polysemous structures, this instrument is a series of written statements that include varying degrees and types of ambiguity. In the first part of the test students are asked to identify (from a choice of three) semantically acceptable paraphrases for an initial sentence. Then students must…

Design of a Motivational Scaffold for the Malaysian e-Learning Environment

ERIC Educational Resources Information Center

Alias, Nor Aziah

2012-01-01

With a structure that provides control and choice over time, place, and pace, e-learning has emerged as a viable mode for working adults who wish to upgrade their knowledge. However, such flexibility provides leeway for these adults to procrastinate and for their motivation to dwindle. After all, many adults, especially Malaysian adults, are used…

Testing Boundary Conditions for the Conjunction Fallacy: Effects of Response Mode, Conceptual Focus, and Problem Type

ERIC Educational Resources Information Center

Wedell, Douglas H.; Moro, Rodrigo

2008-01-01

Two experiments used within-subject designs to examine how conjunction errors depend on the use of (1) choice versus estimation tasks, (2) probability versus frequency language, and (3) conjunctions of two likely events versus conjunctions of likely and unlikely events. All problems included a three-option format verified to minimize…

Relating Communications Mode Choice and Teamwork Quality: Conversational versus Textual Communication in IT System and Software Development Teams

ERIC Educational Resources Information Center

Smith, James Robert

2012-01-01

This cross-sectional study explored how IT system and software development team members communicated in the workplace and whether teams that used more verbal communication (and less text-based communication) experienced higher levels of collaboration as measured using the Teamwork Quality (TWQ) scale. Although computer-mediated communication tools…

For Love or Money: Patterns of Resource Commutation in Social Interchange.

ERIC Educational Resources Information Center

Turner, Jim L.; Foa, Uriel G.

The notion of particularism is used in this study to relate the choice of reciprocal action to the previous exchange situation. Initial encounters were manipulated by exposing 80 female subjects to affective and monetary outcomes provided by 2 male peers. Treatment conditions varyed in feedback level (high vs. low) and mode of interaction…

Adult Learners' Use of Flexible Online Resources in a Blended Programme

ERIC Educational Resources Information Center

Cornelius, Sarah; Gordon, Carole

2009-01-01

This paper presents a case study of a blended programme for adults and discusses findings from a mixed-methods investigative study of learners' and tutors' experiences of the programme. The programme employs a set of flexible online resources, which are activity-based and designed to provide choice in study routes and modes of learning. Our…

Model-based influences on humans’ choices and striatal prediction errors

PubMed Central

Daw, Nathaniel D.; Gershman, Samuel J.; Seymour, Ben; Dayan, Peter; Dolan, Raymond J.

2011-01-01

Summary The mesostriatal dopamine system is prominently implicated in model-free reinforcement learning, with fMRI BOLD signals in ventral striatum notably covarying with model-free prediction errors. However, latent learning and devaluation studies show that behavior also shows hallmarks of model-based planning, and the interaction between model-based and model-free values, prediction errors and preferences is underexplored. We designed a multistep decision task in which model-based and model-free influences on human choice behavior could be distinguished. By showing that choices reflected both influences we could then test the purity of the ventral striatal BOLD signal as a model-free report. Contrary to expectations, the signal reflected both model-free and model-based predictions in proportions matching those that best explained choice behavior. These results challenge the notion of a separate model-free learner and suggest a more integrated computational architecture for high-level human decision-making. PMID:21435563

Dynamic Analysis With Stress Mode Animation by the Integrated Force Method

NASA Technical Reports Server (NTRS)

Patnaik, Surya N.; Coroneos, Rula M.; Hopkins, Dale A.

1997-01-01

Dynamic animation of stresses and displacements, which complement each other, can be a useful tool in the analysis and design of structural components. At the present time only displacement-mode animation is available through the popular stiffness formulation. This paper attempts to complete this valuable visualization tool by augmenting the existing art with stress mode animation. The reformulated method of forces, which in the literature is known as the integrated force method (IFM), became the analyzer of choice for the development of stress mode animation because stresses are the primary unknowns of its dynamic analysis. Animation of stresses and displacements, which have been developed successfully through the IFM analyzers, is illustrated in several examples along with a brief introduction to IFM dynamic analysis. The usefulness of animation in design optimization is illustrated considering the spacer structure component of the International Space Station as an example. An overview of the integrated force method analysis code (IFM/ANALYZERS) is provided in the appendix.

The evolution of phenotypes and genetic parameters under preferential mating

PubMed Central

Roff, Derek A; Fairbairn, Daphne J

2014-01-01

This article extends and adds more realism to Lande's analytical model for evolution under mate choice by using individual-based simulations in which females sample a finite number of males and the genetic architecture of the preference and preferred trait evolves. The simulations show that the equilibrium heritabilities of the preference and preferred trait and the genetic correlation between them (rG), depend critically on aspects of the mating system (the preference function, mode of mate choice, choosiness, and number of potential mates sampled), the presence or absence of natural selection on the preferred trait, and the initial genetic parameters. Under some parameter combinations, preferential mating increased the heritability of the preferred trait, providing a possible resolution for the lek paradox. The Kirkpatrick–Barton approximation for rG proved to be biased downward, but the realized genetic correlations were also low, generally <0.2. Such low values of rG indicate that coevolution of the preference and preferred trait is likely to be very slow and subject to significant stochastic variation. Lande's model accurately predicted the incidence of runaway selection in the simulations, except where preferences were relative and the preferred trait was subject to natural selection. In these cases, runaways were over- or underestimated, depending on the number of males sampled. We conclude that rapid coevolution of preferences and preferred traits is unlikely in natural populations, but that the parameter combinations most conducive to it are most likely to occur in lekking species. PMID:25077025

A behavioural and neural evaluation of prospective decision-making under risk

PubMed Central

Symmonds, Mkael; Bossaerts, Peter; Dolan, Raymond J.

2010-01-01

Making the best choice when faced with a chain of decisions requires a person to judge both anticipated outcomes and future actions. Although economic decision-making models account for both risk and reward in single choice contexts there is a dearth of similar knowledge about sequential choice. Classical utility-based models assume that decision-makers select and follow an optimal pre-determined strategy, irrespective of the particular order in which options are presented. An alternative model involves continuously re-evaluating decision utilities, without prescribing a specific future set of choices. Here, using behavioral and functional magnetic resonance imaging (fMRI) data, we studied human subjects in a sequential choice task and use these data to compare alternative decision models of valuation and strategy selection. We provide evidence that subjects adopt a model of re-evaluating decision utilities, where available strategies are continuously updated and combined in assessing action values. We validate this model by using simultaneously-acquired fMRI data to show that sequential choice evokes a pattern of neural response consistent with a tracking of anticipated distribution of future reward, as expected in such a model. Thus, brain activity evoked at each decision point reflects the expected mean, variance and skewness of possible payoffs, consistent with the idea that sequential choice evokes a prospective evaluation of both available strategies and possible outcomes. PMID:20980595

A behavioral and neural evaluation of prospective decision-making under risk.

PubMed

Symmonds, Mkael; Bossaerts, Peter; Dolan, Raymond J

2010-10-27

Making the best choice when faced with a chain of decisions requires a person to judge both anticipated outcomes and future actions. Although economic decision-making models account for both risk and reward in single-choice contexts, there is a dearth of similar knowledge about sequential choice. Classical utility-based models assume that decision-makers select and follow an optimal predetermined strategy, regardless of the particular order in which options are presented. An alternative model involves continuously reevaluating decision utilities, without prescribing a specific future set of choices. Here, using behavioral and functional magnetic resonance imaging (fMRI) data, we studied human subjects in a sequential choice task and use these data to compare alternative decision models of valuation and strategy selection. We provide evidence that subjects adopt a model of reevaluating decision utilities, in which available strategies are continuously updated and combined in assessing action values. We validate this model by using simultaneously acquired fMRI data to show that sequential choice evokes a pattern of neural response consistent with a tracking of anticipated distribution of future reward, as expected in such a model. Thus, brain activity evoked at each decision point reflects the expected mean, variance, and skewness of possible payoffs, consistent with the idea that sequential choice evokes a prospective evaluation of both available strategies and possible outcomes.

The modal density of composite beams incorporating the effects of shear deformation and rotary inertia

NASA Astrophysics Data System (ADS)

Bachoo, Richard; Bridge, Jacqueline

2018-06-01

Engineers and designers are often faced with the task of selecting materials that minimizes structural weight whilst meeting the required strength and stiffness. In many cases fibre reinforced composites (FRCs) are the materials of choice since they possess a combination of high strength and low density. Depending on the application, composites are frequently constructed to form long slender beam-like structures or flat thin plate-like structures. Such structures when subjected to random excitation have the potential to excite higher order vibratory modes which can contribute significantly to structure-borne sound. Statistical Energy Analysis (SEA) is a framework for modeling the high frequency vibration of structures. The modal density, which is typically defined as the number of modes per unit Hertz in a frequency band, is a fundamental parameter when applying SEA. This study derives formulas for the modal density of a fibre reinforced composite beam coupled in bending and torsion. The effects of shear deformation and rotary inertia are accounted for in the formulation. The modal density is shown to be insensitive to boundary conditions. Numerical analyses were carried out to investigate the variation of modal density with fibre orientation including and excluding the effects of shear deformation and rotary inertia. It was observed that neglecting such effects leads to underestimating the mode count in a particular frequency band. In each frequency band there exists a fibre orientation for which the modal density is minimized. This angular orientation is shown to be dependent on the shear rigidity as well as the bending, torsional and coupling rigidities. The foregoing observation becomes more pronounced with increasing frequency. The paper also addresses the modal density beyond the wave-mode transition frequency where the beam supports three propagating waves.

Vibrational analysis of carbonyl modes in different stages of light-induced cyclopyrimidine dimer repair reactions

NASA Astrophysics Data System (ADS)

Schmitz, Matthias; Tavan, Paul; Nonella, Marco

2001-11-01

The formation of cyclopyrimidine dimers is a DNA defect, which is repaired by the enzyme DNA photolyase in a light-induced reaction. Radical anions of the dimers have been suggested to occur as short-lived intermediates during repair. For their identification time-resolved Fourier-transform infrared (FTIR) spectroscopy will be a method of choice. To support and guide such spectroscopic studies we have calculated the vibrational spectra of various pyrimidine compounds using density functional methods. Our results suggest that the carbonyl vibrations of these molecules can serve as marker modes to identify and distinguish intermediates of the repair reaction.

FIBER AND INTEGRATED OPTICS: Radio-frequency electrooptic modulation in optical fibers

NASA Astrophysics Data System (ADS)

Bulyuk, A. N.

1992-10-01

The electrooptic interaction in single-mode optical fibers with both linear and circular birefringe is analyzed. In most cases, a large interaction length imposes a limit on the modulation frequency. A circular birefringence in an optical fiber may lead to an effective coupling of polarization normal modes if a phase-matching condition is satisfied. Through an appropriate choice of polarization states of the light at the entrance and exit of the device, one can achieve a polarization modulation or a frequency shift of the light. There are possible applications in rf polarization modulators, devices for shifting the frequency of light, and detectors of electromagnetic fields.

Wavelength and pulse duration tunable ultrafast fiber laser mode-locked with carbon nanotubes.

PubMed

Li, Diao; Jussila, Henri; Wang, Yadong; Hu, Guohua; Albrow-Owen, Tom; C T Howe, Richard; Ren, Zhaoyu; Bai, Jintao; Hasan, Tawfique; Sun, Zhipei

2018-02-09

Ultrafast lasers with tunable parameters in wavelength and time domains are the choice of light source for various applications such as spectroscopy and communication. Here, we report a wavelength and pulse-duration tunable mode-locked Erbium doped fiber laser with single wall carbon nanotube-based saturable absorber. An intra-cavity tunable filter is employed to continuously tune the output wavelength for 34 nm (from 1525 nm to 1559 nm) and pulse duration from 545 fs to 6.1 ps, respectively. Our results provide a novel light source for various applications requiring variable wavelength or pulse duration.

Measuring and modeling travel well-being in a dynamic context.

DOT National Transportation Integrated Search

2013-03-01

Travel behavior models typically assume that people base their travel choices on time and cost : considerations and do not account sufficiently for qualitative factors that affect the choice. Travel : choices are however more likely to be motivated b...

Critical multi-level governance issues of integrated modelling: An example of low-water management in the Adour-Garonne basin (France)

NASA Astrophysics Data System (ADS)

Mazzega, Pierre; Therond, Olivier; Debril, Thomas; March, Hug; Sibertin-Blanc, Christophe; Lardy, Romain; Sant'ana, Daniel

2014-11-01

This paper presents the experience gained related to the development of an integrated simulation model of water policy. Within this context, we analyze particular difficulties raised by the inclusion of multi-level governance that assigns the responsibility of individual or collective decision-making to a variety of actors, regarding measures of which the implementation has significant effects toward the sustainability of socio-hydrosystems. Multi-level governance procedures are compared with the potential of model-based impact assessment. Our discussion is illustrated on the basis of the exploitation of the multi-agent platform MAELIA dedicated to the simulation of social, economic and environmental impacts of low-water management in a context of climate and regulatory changes. We focus on three major decision-making processes occurring in the Adour-Garonne basin, France: (i) the participatory development of the Master Scheme for Water Planning and Management (SDAGE) under the auspices of the Water Agency; (ii) the publication of water use restrictions in situations of water scarcity; and (iii) the determination of the abstraction volumes for irrigation and their allocation. The MAELIA platform explicitly takes into account the mode of decision-making when it is framed by a procedure set beforehand, focusing on the actors' participation and on the nature and parameters of the measures to be implemented. It is observed that in some water organizations decision-making follows patterns that can be represented as rule-based actions triggered by thresholds of resource states. When decisions are resulting from individual choice, endowing virtual agents with bounded rationality allows us to reproduce (in silico) their behavior and decisions in a reliable way. However, the negotiation processes taking place during the period of time simulated by the models in arenas of collective choices are not all reproducible. Outcomes of some collective decisions are very little or not at all predictable. The development and simulation of a priori policy scenarios capturing the most plausible or interesting outcomes of such collective decisions on measures for low-water management allows these difficulties to be overcome. The building of these kind of scenarios requires close collaboration between researchers and stakeholders involved in arenas of collective choice, and implies the integration of the production of model and the analysis of scenarios as one component of the polycentric political process of water management.

Emerging Australian Education Markets: A Discrete Choice Model of Taiwanese and Indonesian Student Intended Study Destination.

ERIC Educational Resources Information Center

Kemp, Steven; Madden, Gary; Simpson, Michael

1998-01-01

Isolates factors influencing choice of Australia as a preferred destination for international students in emerging regional markets. Uses data obtained from a survey of students in Indonesia and Taiwan to estimate a U.S./Australia and rest-of-world/Australia discrete destination-choice model. This model identifies key factors determining country…

Representing Heterogeneity in Structural Relationships Among Multiple Choice Variables Using a Latent Segmentation Approach

DOE Office of Scientific and Technical Information (OSTI.GOV)

Garikapati, Venu; Astroza, Sebastian; Pendyala, Ram M.

Travel model systems often adopt a single decision structure that links several activity-travel choices together. The single decision structure is then used to predict activity-travel choices, with those downstream in the decision-making chain influenced by those upstream in the sequence. The adoption of a singular sequential causal structure to depict relationships among activity-travel choices in travel demand model systems ignores the possibility that some choices are made jointly as a bundle as well as the possible presence of structural heterogeneity in the population with respect to decision-making processes. As different segments in the population may adopt and follow different causalmore » decision-making mechanisms when making selected choices jointly, it would be of value to develop simultaneous equations model systems relating multiple endogenous choice variables that are able to identify population subgroups following alternative causal decision structures. Because the segments are not known a priori, they are considered latent and determined endogenously within a joint modeling framework proposed in this paper. The methodology is applied to a national mobility survey data set to identify population segments that follow different causal structures relating residential location choice, vehicle ownership, and car-share and mobility service usage. It is found that the model revealing three distinct latent segments best describes the data, confirming the efficacy of the modeling approach and the existence of structural heterogeneity in decision-making in the population. Future versions of activity-travel model systems should strive to incorporate such structural heterogeneity to better reflect varying decision processes across population subgroups.« less

Variable selection and model choice in geoadditive regression models.

PubMed

Kneib, Thomas; Hothorn, Torsten; Tutz, Gerhard

2009-06-01

Model choice and variable selection are issues of major concern in practical regression analyses, arising in many biometric applications such as habitat suitability analyses, where the aim is to identify the influence of potentially many environmental conditions on certain species. We describe regression models for breeding bird communities that facilitate both model choice and variable selection, by a boosting algorithm that works within a class of geoadditive regression models comprising spatial effects, nonparametric effects of continuous covariates, interaction surfaces, and varying coefficients. The major modeling components are penalized splines and their bivariate tensor product extensions. All smooth model terms are represented as the sum of a parametric component and a smooth component with one degree of freedom to obtain a fair comparison between the model terms. A generic representation of the geoadditive model allows us to devise a general boosting algorithm that automatically performs model choice and variable selection.

Economic rationality and health and lifestyle choices for people with diabetes.

PubMed

Baker, Rachel Mairi

2006-11-01

Economic rationality is traditionally represented by goal-oriented, maximising behaviour, or 'instrumental rationality'. Such a consequentialist, instrumental model of choice is often implicit in a biomedical approach to health promotion and education. The research reported here assesses the relevance of a broader conceptual framework of rationality, which includes 'procedural' and 'expressive' rationality as complements to an instrumental model of rationality, in a health context. Q methodology was used to derive 'factors' underlying health and lifestyle choices, based on a factor analysis of the results of a card sorting procedure undertaken by 27 adult respondents with type 2 diabetes in Newcastle upon Tyne, UK. These factors were then compared with the rationality framework and the appropriateness of an extended model of economic rationality as a means of better understanding health and lifestyle choices was assessed. Taking a wider rational choice perspective, choices which are rendered irrational within a narrow-biomedical or strictly instrumental model, can be understood in terms of a coherent rationale, grounded in the accounts of respondents. The implications of these findings are discussed in terms of rational choice theory and diabetes management and research.

Phase space effects on fast ion distribution function modeling in tokamaks

NASA Astrophysics Data System (ADS)

Podestà, M.; Gorelenkova, M.; Fredrickson, E. D.; Gorelenkov, N. N.; White, R. B.

2016-05-01

Integrated simulations of tokamak discharges typically rely on classical physics to model energetic particle (EP) dynamics. However, there are numerous cases in which energetic particles can suffer additional transport that is not classical in nature. Examples include transport by applied 3D magnetic perturbations and, more notably, by plasma instabilities. Focusing on the effects of instabilities, ad-hoc models can empirically reproduce increased transport, but the choice of transport coefficients is usually somehow arbitrary. New approaches based on physics-based reduced models are being developed to address those issues in a simplified way, while retaining a more correct treatment of resonant wave-particle interactions. The kick model implemented in the tokamak transport code TRANSP is an example of such reduced models. It includes modifications of the EP distribution by instabilities in real and velocity space, retaining correlations between transport in energy and space typical of resonant EP transport. The relevance of EP phase space modifications by instabilities is first discussed in terms of predicted fast ion distribution. Results are compared with those from a simple, ad-hoc diffusive model. It is then shown that the phase-space resolved model can also provide additional insight into important issues such as internal consistency of the simulations and mode stability through the analysis of the power exchanged between energetic particles and the instabilities.

Phase space effects on fast ion distribution function modeling in tokamaks

DOE Data Explorer

White, R. B. [Princeton Plasma Physics Lab. (PPPL), Princeton, NJ (United States); Podesta, M. [Princeton Plasma Physics Lab. (PPPL), Princeton, NJ (United States); Gorelenkova, M. [Princeton Plasma Physics Lab. (PPPL), Princeton, NJ (United States); Fredrickson, E. D. [Princeton Plasma Physics Lab. (PPPL), Princeton, NJ (United States); Gorelenkov, N. N. [Princeton Plasma Physics Lab. (PPPL), Princeton, NJ (United States)

2016-06-01

Integrated simulations of tokamak discharges typically rely on classical physics to model energetic particle (EP) dynamics. However, there are numerous cases in which energetic particles can suffer additional transport that is not classical in nature. Examples include transport by applied 3D magnetic perturbations and, more notably, by plasma instabilities. Focusing on the effects of instabilities, ad-hoc models can empirically reproduce increased transport, but the choice of transport coefficients is usually somehow arbitrary. New approaches based on physics-based reduced models are being developed to address those issues in a simplified way, while retaining a more correct treatment of resonant wave-particle interactions. The kick model implemented in the tokamak transport code TRANSP is an example of such reduced models. It includes modifications of the EP distribution by instabilities in real and velocity space, retaining correlations between transport in energy and space typical of resonant EP transport. The relevance of EP phase space modifications by instabilities is first discussed in terms of predicted fast ion distribution. Results are compared with those from a simple, ad-hoc diffusive model. It is then shown that the phase-space resolved model can also provide additional insight into important issues such as internal consistency of the simulations and mode stability through the analysis of the power exchanged between energetic particles and the instabilities.

The effect of constraints on the analytical figures of merit achieved by extended multivariate curve resolution-alternating least-squares.

PubMed

Pellegrino Vidal, Rocío B; Allegrini, Franco; Olivieri, Alejandro C

2018-03-20

Multivariate curve resolution-alternating least-squares (MCR-ALS) is the model of choice when dealing with some non-trilinear arrays, specifically when the data are of chromatographic origin. To drive the iterative procedure to chemically interpretable solutions, the use of constraints becomes essential. In this work, both simulated and experimental data have been analyzed by MCR-ALS, applying chemically reasonable constraints, and investigating the relationship between selectivity, analytical sensitivity (γ) and root mean square error of prediction (RMSEP). As the selectivity in the instrumental modes decreases, the estimated values for γ did not fully represent the predictive model capabilities, judged from the obtained RMSEP values. Since the available sensitivity expressions have been developed by error propagation theory in unconstrained systems, there is a need of developing new expressions or analytical indicators. They should not only consider the specific profiles retrieved by MCR-ALS, but also the constraints under which the latter ones have been obtained. Copyright © 2017 Elsevier B.V. All rights reserved.

Slicer Method Comparison Using Open-source 3D Printer

NASA Astrophysics Data System (ADS)

Ariffin, M. K. A. Mohd; Sukindar, N. A.; Baharudin, B. T. H. T.; Jaafar, C. N. A.; Ismail, M. I. S.

2018-01-01

Open-source 3D printer has been one of the popular choices in fabricating 3D models. This technology is easily accessible and low in cost. However, several studies have been made to improve the performance of this low-cost technology in term of the accuracy of the parts finish. This study is focusing on the selection of slicer mode between CuraEngine and Slic3r. The effect on this slicer has been observe in terms of accuracy and surface visualization. The result shows that if the accuracy is the top priority, CuraEngine is the better option to use as contribute more accuracy as well as less filament is needed compared to the Slice3r. Slice3r may be very useful for complicated parts such as hanging structure due to excessive material which act as support material. The study provides basic platform for the user to have an idea which option to be used in fabricating 3D model.

Tensor discriminant color space for face recognition.

PubMed

Wang, Su-Jing; Yang, Jian; Zhang, Na; Zhou, Chun-Guang

2011-09-01

Recent research efforts reveal that color may provide useful information for face recognition. For different visual tasks, the choice of a color space is generally different. How can a color space be sought for the specific face recognition problem? To address this problem, this paper represents a color image as a third-order tensor and presents the tensor discriminant color space (TDCS) model. The model can keep the underlying spatial structure of color images. With the definition of n-mode between-class scatter matrices and within-class scatter matrices, TDCS constructs an iterative procedure to obtain one color space transformation matrix and two discriminant projection matrices by maximizing the ratio of these two scatter matrices. The experiments are conducted on two color face databases, AR and Georgia Tech face databases, and the results show that both the performance and the efficiency of the proposed method are better than those of the state-of-the-art color image discriminant model, which involve one color space transformation matrix and one discriminant projection matrix, specifically in a complicated face database with various pose variations.

Detecting anomalies in CMB maps: a new method

DOE Office of Scientific and Technical Information (OSTI.GOV)

Neelakanta, Jayanth T., E-mail: jayanthtn@gmail.com

2015-10-01

Ever since WMAP announced its first results, different analyses have shown that there is weak evidence for several large-scale anomalies in the CMB data. While the evidence for each anomaly appears to be weak, the fact that there are multiple seemingly unrelated anomalies makes it difficult to account for them via a single statistical fluke. So, one is led to considering a combination of these anomalies. But, if we ''hand-pick'' the anomalies (test statistics) to consider, we are making an a posteriori choice. In this article, we propose two statistics that do not suffer from this problem. The statistics aremore » linear and quadratic combinations of the a{sub ℓ m}'s with random co-efficients, and they test the null hypothesis that the a{sub ℓ m}'s are independent, normally-distributed, zero-mean random variables with an m-independent variance. The motivation for considering multiple modes is this: because most physical models that lead to large-scale anomalies result in coupling multiple ℓ and m modes, the ''coherence'' of this coupling should get enhanced if a combination of different modes is considered. In this sense, the statistics are thus much more generic than those that have been hitherto considered in literature. Using fiducial data, we demonstrate that the method works and discuss how it can be used with actual CMB data to make quite general statements about the incompatibility of the data with the null hypothesis.« less

Transformation Model Choice in Nonlinear Regression Analysis of Fluorescence-based Serial Dilution Assays

PubMed Central

Fong, Youyi; Yu, Xuesong

2016-01-01

Many modern serial dilution assays are based on fluorescence intensity (FI) readouts. We study optimal transformation model choice for fitting five parameter logistic curves (5PL) to FI-based serial dilution assay data. We first develop a generalized least squares-pseudolikelihood type algorithm for fitting heteroscedastic logistic models. Next we show that the 5PL and log 5PL functions can approximate each other well. We then compare four 5PL models with different choices of log transformation and variance modeling through a Monte Carlo study and real data. Our findings are that the optimal choice depends on the intended use of the fitted curves. PMID:27642502

Dynamic Response-by-Response Models of Matching Behavior in Rhesus Monkeys

PubMed Central

Lau, Brian; Glimcher, Paul W

2005-01-01

We studied the choice behavior of 2 monkeys in a discrete-trial task with reinforcement contingencies similar to those Herrnstein (1961) used when he described the matching law. In each session, the monkeys experienced blocks of discrete trials at different relative-reinforcer frequencies or magnitudes with unsignalled transitions between the blocks. Steady-state data following adjustment to each transition were well characterized by the generalized matching law; response ratios undermatched reinforcer frequency ratios but matched reinforcer magnitude ratios. We modelled response-by-response behavior with linear models that used past reinforcers as well as past choices to predict the monkeys' choices on each trial. We found that more recently obtained reinforcers more strongly influenced choice behavior. Perhaps surprisingly, we also found that the monkeys' actions were influenced by the pattern of their own past choices. It was necessary to incorporate both past reinforcers and past choices in order to accurately capture steady-state behavior as well as the fluctuations during block transitions and the response-by-response patterns of behavior. Our results suggest that simple reinforcement learning models must account for the effects of past choices to accurately characterize behavior in this task, and that models with these properties provide a conceptual tool for studying how both past reinforcers and past choices are integrated by the neural systems that generate behavior. PMID:16596980

Two formalisms, one renormalized stress-energy tensor

NASA Astrophysics Data System (ADS)

Barceló, C.; Carballo, R.; Garay, L. J.

2012-04-01

We explicitly compare the structure of the renormalized stress-energy tensor of a massless scalar field in a (1+1) curved spacetime as obtained by two different strategies: normal-mode construction of the field operator and one-loop effective action. We pay special attention to where and how the information related to the choice of vacuum state in both formalisms is encoded. By establishing a clear translation map between both procedures, we show that these two potentially different renormalized stress-energy tensors are actually equal, when using vacuum-state choices related by this map. One specific aim of the analysis is to facilitate the comparison of results regarding semiclassical effects in gravitational collapse as obtained within these different formalisms.

Gravitational waves in ghost free bimetric gravity

DOE Office of Scientific and Technical Information (OSTI.GOV)

Mohseni, Morteza, E-mail: m-mohseni@pnu.ac.ir

2012-11-01

We obtain a set of exact gravitational wave solutions for the ghost free bimetric theory of gravity. With a flat reference metric, the theory admits the vacuum Brinkmann plane wave solution for suitable choices of the coefficients of different terms in the interaction potential. An exact gravitational wave solution corresponding to a massive scalar mode is also admitted for arbitrary choice of the coefficients with the reference metric being proportional to the spacetime metric. The proportionality factor and the speed of the wave are calculated in terms of the parameters of the theory. We also show that a F(R) extensionmore » of the theory admits similar solutions but in general is plagued with ghost instabilities.« less

Transition Matrices: A Tool to Assess Student Learning and Improve Instruction

NASA Astrophysics Data System (ADS)

Morris, Gary A.; Walter, Paul; Skees, Spencer; Schwartz, Samantha

2017-03-01

This paper introduces a new spreadsheet tool for adoption by high school or college-level physics teachers who use common assessments in a pre-instruction/post-instruction mode to diagnose student learning and teaching effectiveness. The spreadsheet creates a simple matrix that identifies the percentage of students who select each possible pre-/post-test answer combination on each question of the diagnostic exam. Leveraging analysis of the quality of the incorrect answer choices, one can order the answer choices from worst to best (i.e., correct), resulting in "transition matrices" that can provide deeper insight into student learning and the success or failure of the pedagogical approach than traditional analyses that employ dichotomous scoring.

Trajectory-adaptive route choice models : specification, choice set generation, and estimation.

DOT National Transportation Integrated Search

2013-03-01

The objective of the research is to investigate adaptive route choice behavior using individuallevel route choice data from GPS (Global Positioning System) observations in a real-life : network, where a traveler could revise the route choice based up...

Interacting holographic dark energy models: a general approach

NASA Astrophysics Data System (ADS)

Som, S.; Sil, A.

2014-08-01

Dark energy models inspired by the cosmological holographic principle are studied in homogeneous isotropic spacetime with a general choice for the dark energy density . Special choices of the parameters enable us to obtain three different holographic models, including the holographic Ricci dark energy (RDE) model. Effect of interaction between dark matter and dark energy on the dynamics of those models are investigated for different popular forms of interaction. It is found that crossing of phantom divide can be avoided in RDE models for β>0.5 irrespective of the presence of interaction. A choice of α=1 and β=2/3 leads to a varying Λ-like model introducing an IR cutoff length Λ -1/2. It is concluded that among the popular choices an interaction of the form Q∝ Hρ m suits the best in avoiding the coincidence problem in this model.

Wrong Answers on Multiple-Choice Achievement Tests: Blind Guesses or Systematic Choices?.

ERIC Educational Resources Information Center

Powell, J. C.

A multi-faceted model for the selection of answers for multiple-choice tests was developed from the findings of a series of exploratory studies. This model implies that answer selection should be curvilinear. A series of models were tested for fit using the chi square procedure. Data were collected from 359 elementary school students ages 9-12.…

A simple computational algorithm of model-based choice preference.

PubMed

Toyama, Asako; Katahira, Kentaro; Ohira, Hideki

2017-08-01

A broadly used computational framework posits that two learning systems operate in parallel during the learning of choice preferences-namely, the model-free and model-based reinforcement-learning systems. In this study, we examined another possibility, through which model-free learning is the basic system and model-based information is its modulator. Accordingly, we proposed several modified versions of a temporal-difference learning model to explain the choice-learning process. Using the two-stage decision task developed by Daw, Gershman, Seymour, Dayan, and Dolan (2011), we compared their original computational model, which assumes a parallel learning process, and our proposed models, which assume a sequential learning process. Choice data from 23 participants showed a better fit with the proposed models. More specifically, the proposed eligibility adjustment model, which assumes that the environmental model can weight the degree of the eligibility trace, can explain choices better under both model-free and model-based controls and has a simpler computational algorithm than the original model. In addition, the forgetting learning model and its variation, which assume changes in the values of unchosen actions, substantially improved the fits to the data. Overall, we show that a hybrid computational model best fits the data. The parameters used in this model succeed in capturing individual tendencies with respect to both model use in learning and exploration behavior. This computational model provides novel insights into learning with interacting model-free and model-based components.

The Influence of Consumer Goals and Marketing Activities on Product Bundling

NASA Astrophysics Data System (ADS)

Haijun, Wang

Upon entering a store, consumers are faced with the questions of whether to buy, what to buy, and how much to buy. Consumers include products from different categories in their decision process. Product categories can be related in different ways. Product bundling is a process that involves the choice of at least two non-substitutable items. In this research, the consumers' explicit product bundling activity at the point of sale is focused. We focuses on the retailers' perspective and therefore leaves out consumers' brand choice decisions, concentrating on purchase incidence and quantity. At the base of the current model of the exist researches, we integrate behavioural choice analysis and predictive choice modelling through the underlying behavioural models, called random utility maximization (RUM) models. The methodological contribution of this research lies therein to combine a nested logit choice model with a latent variable factor model. We point out several limitations for both theory and practice at the end.

PEER REVIEW FOR THE CONSUMER VEHICLE CHOICE MODEL

EPA Science Inventory

The U.S. Environmental Protection Agency’s (EPA) Office of Transportation and Air Quality (OTAQ) has recently sponsored the development of a Consumer Vehicle Choice Model (CVCM) by the Oak Ridge National Laboratory (ORNL). The specification by OTAQ to ORNL for consumer choice mod...

Exclusive queueing model including the choice of service windows

NASA Astrophysics Data System (ADS)

Tanaka, Masahiro; Yanagisawa, Daichi; Nishinari, Katsuhiro

2018-01-01

In a queueing system involving multiple service windows, choice behavior is a significant concern. This paper incorporates the choice of service windows into a queueing model with a floor represented by discrete cells. We contrived a logit-based choice algorithm for agents considering the numbers of agents and the distances to all service windows. Simulations were conducted with various parameters of agent choice preference for these two elements and for different floor configurations, including the floor length and the number of service windows. We investigated the model from the viewpoint of transit times and entrance block rates. The influences of the parameters on these factors were surveyed in detail and we determined that there are optimum floor lengths that minimize the transit times. In addition, we observed that the transit times were determined almost entirely by the entrance block rates. The results of the presented model are relevant to understanding queueing systems including the choice of service windows and can be employed to optimize facility design and floor management.

Classification and recognition of dynamical models: the role of phase, independent components, kernels and optimal transport.

PubMed

Bissacco, Alessandro; Chiuso, Alessandro; Soatto, Stefano

2007-11-01

We address the problem of performing decision tasks, and in particular classification and recognition, in the space of dynamical models in order to compare time series of data. Motivated by the application of recognition of human motion in image sequences, we consider a class of models that include linear dynamics, both stable and marginally stable (periodic), both minimum and non-minimum phase, driven by non-Gaussian processes. This requires extending existing learning and system identification algorithms to handle periodic modes and nonminimum phase behavior, while taking into account higher-order statistics of the data. Once a model is identified, we define a kernel-based cord distance between models that includes their dynamics, their initial conditions as well as input distribution. This is made possible by a novel kernel defined between two arbitrary (non-Gaussian) distributions, which is computed by efficiently solving an optimal transport problem. We validate our choice of models, inference algorithm, and distance on the tasks of human motion synthesis (sample paths of the learned models), and recognition (nearest-neighbor classification in the computed distance). However, our work can be applied more broadly where one needs to compare historical data while taking into account periodic trends, non-minimum phase behavior, and non-Gaussian input distributions.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Podestà, M., E-mail: mpodesta@pppl.gov; Gorelenkova, M.; Fredrickson, E. D.

Integrated simulations of tokamak discharges typically rely on classical physics to model energetic particle (EP) dynamics. However, there are numerous cases in which energetic particles can suffer additional transport that is not classical in nature. Examples include transport by applied 3D magnetic perturbations and, more notably, by plasma instabilities. Focusing on the effects of instabilities, ad-hoc models can empirically reproduce increased transport, but the choice of transport coefficients is usually somehow arbitrary. New approaches based on physics-based reduced models are being developed to address those issues in a simplified way, while retaining a more correct treatment of resonant wave-particle interactions.more » The kick model implemented in the tokamak transport code TRANSP is an example of such reduced models. It includes modifications of the EP distribution by instabilities in real and velocity space, retaining correlations between transport in energy and space typical of resonant EP transport. The relevance of EP phase space modifications by instabilities is first discussed in terms of predicted fast ion distribution. Results are compared with those from a simple, ad-hoc diffusive model. It is then shown that the phase-space resolved model can also provide additional insight into important issues such as internal consistency of the simulations and mode stability through the analysis of the power exchanged between energetic particles and the instabilities.« less

Optimization of the imaging response of scanning microwave microscopy measurements

NASA Astrophysics Data System (ADS)

Sardi, G. M.; Lucibello, A.; Kasper, M.; Gramse, G.; Proietti, E.; Kienberger, F.; Marcelli, R.

2015-07-01

In this work, we present the analytical modeling and preliminary experimental results for the choice of the optimal frequencies when performing amplitude and phase measurements with a scanning microwave microscope. In particular, the analysis is related to the reflection mode operation of the instrument, i.e., the acquisition of the complex reflection coefficient data, usually referred as S11. The studied configuration is composed of an atomic force microscope with a microwave matched nanometric cantilever probe tip, connected by a λ/2 coaxial cable resonator to a vector network analyzer. The set-up is provided by Keysight Technologies. As a peculiar result, the optimal frequencies, where the maximum sensitivity is achieved, are different for the amplitude and for the phase signals. The analysis is focused on measurements of dielectric samples, like semiconductor devices, textile pieces, and biological specimens.

The attentional drift-diffusion model extends to simple purchasing decisions.

PubMed

Krajbich, Ian; Lu, Dingchao; Camerer, Colin; Rangel, Antonio

2012-01-01

How do we make simple purchasing decisions (e.g., whether or not to buy a product at a given price)? Previous work has shown that the attentional drift-diffusion model (aDDM) can provide accurate quantitative descriptions of the psychometric data for binary and trinary value-based choices, and of how the choice process is guided by visual attention. Here we extend the aDDM to the case of purchasing decisions, and test it using an eye-tracking experiment. We find that the model also provides a reasonably accurate quantitative description of the relationship between choice, reaction time, and visual fixations using parameters that are very similar to those that best fit the previous data. The only critical difference is that the choice biases induced by the fixations are about half as big in purchasing decisions as in binary choices. This suggests that a similar computational process is used to make binary choices, trinary choices, and simple purchasing decisions.

The Attentional Drift-Diffusion Model Extends to Simple Purchasing Decisions

PubMed Central

Krajbich, Ian; Lu, Dingchao; Camerer, Colin; Rangel, Antonio

2012-01-01

How do we make simple purchasing decisions (e.g., whether or not to buy a product at a given price)? Previous work has shown that the attentional drift-diffusion model (aDDM) can provide accurate quantitative descriptions of the psychometric data for binary and trinary value-based choices, and of how the choice process is guided by visual attention. Here we extend the aDDM to the case of purchasing decisions, and test it using an eye-tracking experiment. We find that the model also provides a reasonably accurate quantitative description of the relationship between choice, reaction time, and visual fixations using parameters that are very similar to those that best fit the previous data. The only critical difference is that the choice biases induced by the fixations are about half as big in purchasing decisions as in binary choices. This suggests that a similar computational process is used to make binary choices, trinary choices, and simple purchasing decisions. PMID:22707945

Choice theories: What are they good for?☆

PubMed Central

Johnson, Eric J.

2013-01-01

Simonson et al. present an ambitious sketch of an integrative theory of context. Provoked by this thoughtful proposal, I discuss what is the function of theories of choice in the coming decades. Traditionally, choice models and theory have attempted to predict choices as a function of the attributes of options. I argue that to be truly useful, they need to generate specific and quantitative predictions of the effect of the choice environment upon choice probability. To do this, we need to focus on rigorously modeling and measuring the underlying processes causing these effects, and use the Simonson et al. proposal to provide some examples. I also present some examples from research in decision-making and decision neuroscience, and argue that models that fail, and fail spectacularly are particularly useful. I close with a challenge: How would consumer researcher aid the design of real world choice environments such as the health exchanges under the Patient Protection and Affordable Care Act? PMID:23794793

Choice Rules and Accumulator Networks

PubMed Central

2015-01-01

This article presents a preference accumulation model that can be used to implement a number of different multi-attribute heuristic choice rules, including the lexicographic rule, the majority of confirming dimensions (tallying) rule and the equal weights rule. The proposed model differs from existing accumulators in terms of attribute representation: Leakage and competition, typically applied only to preference accumulation, are also assumed to be involved in processing attribute values. This allows the model to perform a range of sophisticated attribute-wise comparisons, including comparisons that compute relative rank. The ability of a preference accumulation model composed of leaky competitive networks to mimic symbolic models of heuristic choice suggests that these 2 approaches are not incompatible, and that a unitary cognitive model of preferential choice, based on insights from both these approaches, may be feasible. PMID:28670592

Modeling Dynamic Food Choice Processes to Understand Dietary Intervention Effects.

PubMed

Marcum, Christopher Steven; Goldring, Megan R; McBride, Colleen M; Persky, Susan

2018-02-17

Meal construction is largely governed by nonconscious and habit-based processes that can be represented as a collection of in dividual, micro-level food choices that eventually give rise to a final plate. Despite this, dietary behavior intervention research rarely captures these micro-level food choice processes, instead measuring outcomes at aggregated levels. This is due in part to a dearth of analytic techniques to model these dynamic time-series events. The current article addresses this limitation by applying a generalization of the relational event framework to model micro-level food choice behavior following an educational intervention. Relational event modeling was used to model the food choices that 221 mothers made for their child following receipt of an information-based intervention. Participants were randomized to receive either (a) control information; (b) childhood obesity risk information; (c) childhood obesity risk information plus a personalized family history-based risk estimate for their child. Participants then made food choices for their child in a virtual reality-based food buffet simulation. Micro-level aspects of the built environment, such as the ordering of each food in the buffet, were influential. Other dynamic processes such as choice inertia also influenced food selection. Among participants receiving the strongest intervention condition, choice inertia decreased and the overall rate of food selection increased. Modeling food selection processes can elucidate the points at which interventions exert their influence. Researchers can leverage these findings to gain insight into nonconscious and uncontrollable aspects of food selection that influence dietary outcomes, which can ultimately improve the design of dietary interventions.

New Literacy's Cut and Paste and How Educators Can Assist Creativity

ERIC Educational Resources Information Center

Hall, Stephen J.

2010-01-01

There is little point in teachers and writers arguing for the good old days of copper plate writing and the perceived decay of the English language through on-line modes. We have little choice but to embrace change, Facebook reality and consider the role of new media, so as to avoid being caught in a widening digital awareness gap. Language…

Developing a typology for understanding VFR as a primary purpose vs. VFR as a type of accommodation

Treesearch

Lori Pennington-Gray; Charles W. Lane; Andrew Holdnak

2003-01-01

This study examined VFR travelers in relation to their behaviors. Data were collected at fourteen sites Alachua County, Florida in 2001. Some of the sites included: hotels, local attractions and special events. A fixed choice questionnaire contained items asking about mode of transportation, demographic characteristics, number of people in the travel party, number of...

76 FR 54268 - Self-Regulatory Organizations; Fixed Income Clearing Corporation; Notice of Filing of Proposed...

Federal Register 2010, 2011, 2012, 2013, 2014

2011-08-31

... undertaking a rewrite of its internal software applications and operating systems to promote efficiency and... believes there is no need to provide participants with a choice of match mode because MBSD's system already attempts to find an exact match for trade input and, only if an exact match is not found, will the system...

Crime in the Classroom: Analysis over 26 Years

ERIC Educational Resources Information Center

Harrp, David N.

2018-01-01

Copying adjacent answer sheets on the oft-used multiple-choice exams can be prevented if exam material is scrambled. The latter mode has been a requirement for all exams of this type at McGill University for 26 years. Cheating by copying has been reduced to nearly zero in this time. The experiment carried out used permissive seating and a single…

Ships/Trains/Planes/Automobiles: A Renaissance of their Interface

NASA Technical Reports Server (NTRS)

Allan, Stanley N.

1974-01-01

This paper highlights some of the major multi-modal interface problems created by technological advances, socio-political individualism and the flexibility of choices we expect from our transportation modes. The emphasis is on the need for a comprehensive national network of multi-modal priorities to enhance the movement of people and goods within the changing physical shape of our cities.

Socio-Semiotic Patterns in Digital Meaning-Making: Semiotic Choice as Indicator of Communicative Experience

ERIC Educational Resources Information Center

Sofkova Hashemi, Sylvana

2017-01-01

Access to digital technology in the classroom enables the composition and organization of ideas on screen with a variety of semiotic systems of different modes and media. This study explores patterns of communication and preference of design in digital meaning-making of twelve 7-8 years old students. Meanings were shaped in complex uses and…

The Use of Information and Communications Technology in Teaching and E-Learning in the Caribbean

ERIC Educational Resources Information Center

Masino, Monica

2013-01-01

As educational institutions and other training facilities search for more economical ways to deliver education and training, the Internet has become the main mode of choice for its reach is farther and wider than any major educational marketing initiative. The Internet is also an inexpensive tool that delivers access to education and training to…

Nonlinear analysis of a relativistic beam-plasma cyclotron instability

NASA Technical Reports Server (NTRS)

Sprangle, P.; Vlahos, L.

1986-01-01

A self-consistent set of nonlinear and relativistic wave-particle equations are derived for a magnetized beam-plasma system interacting with electromagnetic cyclotron waves. In particular, the high-frequency cyclotron mode interacting with a streaming and gyrating electron beam within a background plasma is considered in some detail. This interaction mode may possibly find application as a high-power source of coherent short-wavelength radiation for laboratory devices. The background plasma, although passive, plays a central role in this mechanism by modifying the dielectric properties in which the magnetized electron beam propagates. For a particular choice of the transverse beam velocity (i.e., the speed of light divided by the relativistic mass factor), the interaction frequency equals the nonrelativistic electron cyclotron frequency times the relativistic mass factor. For this choice of transverse beam velocity the detrimental effects of a longitudinal beam velocity spread is virtually removed. Power conversion efficiencies in excess of 18 percent are both analytically calculated and obtained through numerical simulations of the wave-particle equations. The quality of the electron beam, degree of energy and pitch angle spread, and its effect on the beam-plasma cyclotron instability is studied.

Conflict management and job satisfaction in paediatric hospitals in Greece.

PubMed

Kaitelidou, Daphne; Kontogianni, Alexandra; Galanis, Petros; Siskou, Olga; Mallidou, Anastasia; Pavlakis, Andreas; Kostagiolas, Petros; Theodorou, Mamas; Liaropoulos, Lycurgus

2012-05-01

To assess the major causes of conflict and to identify choices of strategy in handling conflicts. Conflict is inherent to hospitals as in all complex organizations, and health personnel deal with internal and external conflicts daily. The sample consisted of 286 participants. A five-part questionnaire, specific for conflicts in hospitals, was administered to health personnel. Of the participants 37% were physicians and 63% were nurses and nursing assistants. As far as choice of strategy in conflict management is concerned, avoidance was found to be the most frequent mode chosen while accommodation was the least frequent mode. Organizational problems were the main issue creating conflicts since 52% of nurses and 45% of physicians agreed that receiving direction from more than one manager may lead to conflicts (P=0.02). Educational differences and communication gaps were reported as another cause of conflicts, with nurses supporting this statement more than the other groups (P=0.006). To become effective in conflict management nurses and physicians must understand causes and strategies in handling conflicts. Major changes are needed regarding human resource management, work incentives and dynamics of teamwork in order to improve working conditions in Greek public hospitals. © 2011 Blackwell Publishing Ltd.

Overview of the JET results

NASA Astrophysics Data System (ADS)

Romanelli, F.; JET Contributors,

2015-10-01

Since the installation of an ITER-like wall, the JET programme has focused on the consolidation of ITER design choices and the preparation for ITER operation, with a specific emphasis given to the bulk tungsten melt experiment, which has been crucial for the final decision on the material choice for the day-one tungsten divertor in ITER. Integrated scenarios have been progressed with the re-establishment of long-pulse, high-confinement H-modes by optimizing the magnetic configuration and the use of ICRH to avoid tungsten impurity accumulation. Stationary discharges with detached divertor conditions and small edge localized modes have been demonstrated by nitrogen seeding. The differences in confinement and pedestal behaviour before and after the ITER-like wall installation have been better characterized towards the development of high fusion yield scenarios in DT. Post-mortem analyses of the plasma-facing components have confirmed the previously reported low fuel retention obtained by gas balance and shown that the pattern of deposition within the divertor has changed significantly with respect to the JET carbon wall campaigns due to the absence of thermally activated chemical erosion of beryllium in contrast to carbon. Transport to remote areas is almost absent and two orders of magnitude less material is found in the divertor.

Choice and explanation in medical management: a multiattribute model of artificial intelligence approaches.

PubMed

Rennels, G D; Shortliffe, E H; Miller, P L

1987-01-01

This paper explores a model of choice and explanation in medical management and makes clear its advantages and limitations. The model is based on multiattribute decision making (MADM) and consists of four distinct strategies for choice and explanation, plus combinations of these four. Each strategy is a restricted form of the general MADM approach, and each makes restrictive assumptions about the nature of the domain. The advantage of tailoring a restricted form of a general technique to a particular domain is that such efforts may better capture the character of the domain and allow choice and explanation to be more naturally modelled. The uses of the strategies for both choice and explanation are illustrated with analyses of several existing medical management artificial intelligence (AI) systems, and also with examples from the management of primary breast cancer. Using the model it is possible to identify common underlying features of these AI systems, since each employs portions of this model in different ways. Thus the model enables better understanding and characterization of the seemingly ad hoc decision making of previous systems.

Model-based influences on humans' choices and striatal prediction errors.

PubMed

Daw, Nathaniel D; Gershman, Samuel J; Seymour, Ben; Dayan, Peter; Dolan, Raymond J

2011-03-24

The mesostriatal dopamine system is prominently implicated in model-free reinforcement learning, with fMRI BOLD signals in ventral striatum notably covarying with model-free prediction errors. However, latent learning and devaluation studies show that behavior also shows hallmarks of model-based planning, and the interaction between model-based and model-free values, prediction errors, and preferences is underexplored. We designed a multistep decision task in which model-based and model-free influences on human choice behavior could be distinguished. By showing that choices reflected both influences we could then test the purity of the ventral striatal BOLD signal as a model-free report. Contrary to expectations, the signal reflected both model-free and model-based predictions in proportions matching those that best explained choice behavior. These results challenge the notion of a separate model-free learner and suggest a more integrated computational architecture for high-level human decision-making. Copyright © 2011 Elsevier Inc. All rights reserved.

Stated choice models for predicting the impact of user fees at public recreation sites

Treesearch

Herbert W. Schroeder; Jordan Louviere

1999-01-01

A crucial question in the implementation of fee programs is how the users of recreation sites will respond to various levels and types of fees. Stated choice models can help managers anticipate the impact of user fees on people's choices among the alternative recreation sites available to them. Models developed for both day and overnight trips to several areas and...

Choice as a Global Language in Local Practice: A Mixed Model of School Choice in Taiwan

ERIC Educational Resources Information Center

Mao, Chin-Ju

2015-01-01

This paper uses school choice policy as an example to demonstrate how local actors adopt, mediate, translate, and reformulate "choice" as neo-liberal rhetoric informing education reform. Complex processes exist between global policy about school choice and the local practice of school choice. Based on the theoretical sensibility of…

Alternative fuels and vehicles choice model

DOT National Transportation Integrated Search

1994-10-01

This report describes the theory and implementation of a model of alternative fuel and vehicle choice (AFVC), designed for use with the United States Department of Energy's Alternative Fuels Trade Model (AFTM). The AFTM is a static equilibrium model ...

The drift diffusion model as the choice rule in reinforcement learning.

PubMed

Pedersen, Mads Lund; Frank, Michael J; Biele, Guido

2017-08-01

Current reinforcement-learning models often assume simplified decision processes that do not fully reflect the dynamic complexities of choice processes. Conversely, sequential-sampling models of decision making account for both choice accuracy and response time, but assume that decisions are based on static decision values. To combine these two computational models of decision making and learning, we implemented reinforcement-learning models in which the drift diffusion model describes the choice process, thereby capturing both within- and across-trial dynamics. To exemplify the utility of this approach, we quantitatively fit data from a common reinforcement-learning paradigm using hierarchical Bayesian parameter estimation, and compared model variants to determine whether they could capture the effects of stimulant medication in adult patients with attention-deficit hyperactivity disorder (ADHD). The model with the best relative fit provided a good description of the learning process, choices, and response times. A parameter recovery experiment showed that the hierarchical Bayesian modeling approach enabled accurate estimation of the model parameters. The model approach described here, using simultaneous estimation of reinforcement-learning and drift diffusion model parameters, shows promise for revealing new insights into the cognitive and neural mechanisms of learning and decision making, as well as the alteration of such processes in clinical groups.

The drift diffusion model as the choice rule in reinforcement learning

PubMed Central

Frank, Michael J.

2017-01-01

Current reinforcement-learning models often assume simplified decision processes that do not fully reflect the dynamic complexities of choice processes. Conversely, sequential-sampling models of decision making account for both choice accuracy and response time, but assume that decisions are based on static decision values. To combine these two computational models of decision making and learning, we implemented reinforcement-learning models in which the drift diffusion model describes the choice process, thereby capturing both within- and across-trial dynamics. To exemplify the utility of this approach, we quantitatively fit data from a common reinforcement-learning paradigm using hierarchical Bayesian parameter estimation, and compared model variants to determine whether they could capture the effects of stimulant medication in adult patients with attention-deficit hyper-activity disorder (ADHD). The model with the best relative fit provided a good description of the learning process, choices, and response times. A parameter recovery experiment showed that the hierarchical Bayesian modeling approach enabled accurate estimation of the model parameters. The model approach described here, using simultaneous estimation of reinforcement-learning and drift diffusion model parameters, shows promise for revealing new insights into the cognitive and neural mechanisms of learning and decision making, as well as the alteration of such processes in clinical groups. PMID:27966103

Parameter Estimation for Thurstone Choice Models

DOE Office of Scientific and Technical Information (OSTI.GOV)

Vojnovic, Milan; Yun, Seyoung

We consider the estimation accuracy of individual strength parameters of a Thurstone choice model when each input observation consists of a choice of one item from a set of two or more items (so called top-1 lists). This model accommodates the well-known choice models such as the Luce choice model for comparison sets of two or more items and the Bradley-Terry model for pair comparisons. We provide a tight characterization of the mean squared error of the maximum likelihood parameter estimator. We also provide similar characterizations for parameter estimators defined by a rank-breaking method, which amounts to deducing one ormore » more pair comparisons from a comparison of two or more items, assuming independence of these pair comparisons, and maximizing a likelihood function derived under these assumptions. We also consider a related binary classification problem where each individual parameter takes value from a set of two possible values and the goal is to correctly classify all items within a prescribed classification error. The results of this paper shed light on how the parameter estimation accuracy depends on given Thurstone choice model and the structure of comparison sets. In particular, we found that for unbiased input comparison sets of a given cardinality, when in expectation each comparison set of given cardinality occurs the same number of times, for a broad class of Thurstone choice models, the mean squared error decreases with the cardinality of comparison sets, but only marginally according to a diminishing returns relation. On the other hand, we found that there exist Thurstone choice models for which the mean squared error of the maximum likelihood parameter estimator can decrease much faster with the cardinality of comparison sets. We report empirical evaluation of some claims and key parameters revealed by theory using both synthetic and real-world input data from some popular sport competitions and online labor platforms.« less

Determinants of choice, and vulnerability and recovery in addiction.

PubMed

Lamb, R J; Maguire, David R; Ginsburg, Brett C; Pinkston, Jonathan W; France, Charles P

2016-06-01

Addiction may be viewed as choice governed by competing contingencies. One factor impacting choice, particularly as it relates to addiction, is sensitivity to delayed rewards. Discounting of delayed rewards influences addiction vulnerability because of competition between relatively immediate gains of drug use, e.g. intoxication, versus relatively remote gains of abstinence, e.g. family stability. Factors modifying delay sensitivity can be modeled in the laboratory. For instance, increased delay sensitivity can be similarly observed in adolescent humans and non-human animals. Similarly, genetic factors influence delay sensitivity in humans and animals. Recovery from addiction may also be viewed as choice behavior. Thus, reinforcing alternative behavior facilitates recovery because reinforcing alternative behavior decreases the frequency of using drugs. How reinforcing alternative behavior influences recovery can also be modeled in the laboratory. For instance, relapse risk decreases as abstinence duration increases, and this decreasing risk can be modeled in animals using choice procedures. In summary, addiction in many respects can be conceptualized as a problem of choice. Animal models of choice disorders stand to increase our understanding of the core processes that establish and maintain addiction and serve as a proving ground for development of novel treatments. Copyright © 2016 Elsevier B.V. All rights reserved.

Determinants of choice, and vulnerability and recovery in addiction

PubMed Central

Lamb, R.J.; Maguire, David R.; Ginsburg, Brett C.; Pinkston, Jonathan W.; France, Charles P.

2016-01-01

Addiction may be viewed as choice governed by competing contingencies. One factor impacting choice, particularly as it relates to addiction, is sensitivity to delayed rewards. Discounting of delayed rewards influences addiction vulnerability because of competition between relatively immediate gains of drug use, e.g. intoxication, versus relatively remote gains of abstinence, e.g. family stability. Factors modifying delay sensitivity can be modeled in the laboratory. For instance, increased delay sensitivity can be similarly observed in adolescent humans and non-human animals. Similarly, genetic factors influence delay sensitivity in humans and animals. Recovery from addiction may also be viewed as choice behavior. Thus, reinforcing alternative behavior facilitates recovery because reinforcing alternative behavior decreases the frequency of using drugs. How reinforcing alternative behavior influences recovery can also be modeled in the laboratory. For instance, relapse risk decreases as abstinence duration increases, and this decreasing risk can be modeled in animals using choice procedures. In summary, addiction in many respects can be conceptualized as a problem of choice. Animal models of choice disorders stand to increase our understanding of the core processes that establish and maintain addiction and serve as a proving ground for development of novel treatments. PMID:27083500

Vertical normal modes of a mesoscale model using a scaled height coordinate

NASA Technical Reports Server (NTRS)

Lipton, A. E.; Pielke, R. A.

1986-01-01

Vertical modes were derived for a version of the Colorado State Regional Atmospheric Mesoscale Modeling System. The impacts of three options for dealing with the upper boundary of the model were studied. The standard model formulation holds pressure constant at a fixed altitude near the model top, and produces a fastest mode with a speed of about 90 m/sec. An alternative formulation, which allows for an external mode, could require recomputation of vertical modes for every surface elevation on the horizontal grid unless the modes are derived in a particular way. These results have bearing on the feasibility of applying vertical mode initialization to models with scaled height coordinates.

Implicit-Explicit Time Integration Methods for Non-hydrostatic Atmospheric Models

NASA Astrophysics Data System (ADS)

Gardner, D. J.; Guerra, J. E.; Hamon, F. P.; Reynolds, D. R.; Ullrich, P. A.; Woodward, C. S.

2016-12-01

The Accelerated Climate Modeling for Energy (ACME) project is developing a non-hydrostatic atmospheric dynamical core for high-resolution coupled climate simulations on Department of Energy leadership class supercomputers. An important factor in computational efficiency is avoiding the overly restrictive time step size limitations of fully explicit time integration methods due to the stiffest modes present in the model (acoustic waves). In this work we compare the accuracy and performance of different Implicit-Explicit (IMEX) splittings of the non-hydrostatic equations and various Additive Runge-Kutta (ARK) time integration methods. Results utilizing the Tempest non-hydrostatic atmospheric model and the ARKode package show that the choice of IMEX splitting and ARK scheme has a significant impact on the maximum stable time step size as well as solution quality. Horizontally Explicit Vertically Implicit (HEVI) approaches paired with certain ARK methods lead to greatly improved runtimes. With effective preconditioning IMEX splittings that incorporate some implicit horizontal dynamics can be competitive with HEVI results. This work was performed under the auspices of the U.S. Department of Energy by Lawrence Livermore National Laboratory under Contract DE-AC52-07NA27344. LLNL-ABS-699187

A developmental model of recreation choice behavior

Treesearch

Daniel R. Williams

1985-01-01

Recreation choices are viewed as including, at least implicitly, a selection of an activity, a setting, and a set of companions. With development these three elements become increasingly differentiated from one another. The model is tested by examining the perceived similarities among a set of 15 recreation choices depicted in color slides.

Comparison of two interpolation methods for empirical mode decomposition based evaluation of radiographic femur bone images.

PubMed

Udhayakumar, Ganesan; Sujatha, Chinnaswamy Manoharan; Ramakrishnan, Swaminathan

2013-01-01

Analysis of bone strength in radiographic images is an important component of estimation of bone quality in diseases such as osteoporosis. Conventional radiographic femur bone images are used to analyze its architecture using bi-dimensional empirical mode decomposition method. Surface interpolation of local maxima and minima points of an image is a crucial part of bi-dimensional empirical mode decomposition method and the choice of appropriate interpolation depends on specific structure of the problem. In this work, two interpolation methods of bi-dimensional empirical mode decomposition are analyzed to characterize the trabecular femur bone architecture of radiographic images. The trabecular bone regions of normal and osteoporotic femur bone images (N = 40) recorded under standard condition are used for this study. The compressive and tensile strength regions of the images are delineated using pre-processing procedures. The delineated images are decomposed into their corresponding intrinsic mode functions using interpolation methods such as Radial basis function multiquadratic and hierarchical b-spline techniques. Results show that bi-dimensional empirical mode decomposition analyses using both interpolations are able to represent architectural variations of femur bone radiographic images. As the strength of the bone depends on architectural variation in addition to bone mass, this study seems to be clinically useful.

Estimating the mode of inheritance in genetic association studies of qualitative traits based on the degree of dominance index

PubMed Central

2011-01-01

Background The biological justification for the choice of the genetic mode in genetic association studies (GAS) is seldom available. Then, the mode of inheritance is approximated by investigating a number of non-orthogonal genetic contrasts making the interpretation of results difficult. Methods We propose to define the mode of inheritance by the significance of the deviance of the co-dominant contrast and the degree of dominance (h), which is a function of two orthogonal contrasts (the co-dominant and additive). Non-dominance exists when the co-dominant contrast is non-significant and, hence, the risk effect of heterozygotes lies in the middle of the risk of the two homozygotes. Otherwise, dominance (including over- and under-dominance) is present and the direction of dominance depends on the value of h. Results Simulations show that h may capture the real mode of inheritance and it is affected by deviations from Hardy-Weinberg equilibrium (HWE). In addition, power for detecting significance of h when the study conforms to HWE rule increases with the degree of dominance and to some extent is related to the mutant allele frequency. Conclusion The introduction of the degree of dominance provides useful insights into the mode of inheritance in GAS. PMID:22188898

Hierarchical competitions subserving multi-attribute choice

PubMed Central

Hunt, Laurence T; Dolan, Raymond J; Behrens, Timothy EJ

2015-01-01

Valuation is a key tenet of decision neuroscience, where it is generally assumed that different attributes of competing options are assimilated into unitary values. Such values are central to current neural models of choice. By contrast, psychological studies emphasize complex interactions between choice and valuation. Principles of neuronal selection also suggest competitive inhibition may occur in early valuation stages, before option selection. Here, we show behavior in multi-attribute choice is best explained by a model involving competition at multiple levels of representation. This hierarchical model also explains neural signals in human brain regions previously linked to valuation, including striatum, parietal and prefrontal cortex, where activity represents competition within-attribute, competition between attributes, and option selection. This multi-layered inhibition framework challenges the assumption that option values are computed before choice. Instead our results indicate a canonical competition mechanism throughout all stages of a processing hierarchy, not simply at a final choice stage. PMID:25306549

NEUROBIOLOGY OF ECONOMIC CHOICE: A GOOD-BASED MODEL

PubMed Central

Padoa-Schioppa, Camillo

2012-01-01

Traditionally the object of economic theory and experimental psychology, economic choice recently became a lively research focus in systems neuroscience. Here I summarize the emerging results and I propose a unifying model of how economic choice might function at the neural level. Economic choice entails comparing options that vary on multiple dimensions. Hence, while choosing, individuals integrate different determinants into a subjective value; decisions are then made by comparing values. According to the good-based model, the values of different goods are computed independently of one another, which implies transitivity. Values are not learned as such, but rather computed at the time of choice. Most importantly, values are compared within the space of goods, independent of the sensori-motor contingencies of choice. Evidence from neurophysiology, imaging and lesion studies indicates that abstract representations of value exist in the orbitofrontal and ventromedial prefrontal cortices. The computation and comparison of values may thus take place within these regions. PMID:21456961

Mode switching in volcanic seismicity: El Hierro 2011-2013

NASA Astrophysics Data System (ADS)

Roberts, Nick S.; Bell, Andrew F.; Main, Ian G.

2016-05-01

The Gutenberg-Richter b value is commonly used in volcanic eruption forecasting to infer material or mechanical properties from earthquake distributions. Such studies typically analyze discrete time windows or phases, but the choice of such windows is subjective and can introduce significant bias. Here we minimize this sample bias by iteratively sampling catalogs with randomly chosen windows and then stack the resulting probability density functions for the estimated b>˜ value to determine a net probability density function. We examine data from the El Hierro seismic catalog during a period of unrest in 2011-2013 and demonstrate clear multimodal behavior. Individual modes are relatively stable in time, but the most probable b>˜ value intermittently switches between modes, one of which is similar to that of tectonic seismicity. Multimodality is primarily associated with intermittent activation and cessation of activity in different parts of the volcanic system rather than with respect to any systematic inferred underlying process.

Operating and hydrodynamic characteristics of a reversed flow jet loop bioreactor (RFJLB) with ejector.

PubMed

Wagh, Sameer M; Koranne, Kishore V; Sonolikar, Ram L

2012-04-01

The hydrodynamic characteristics of RFJLB was studied with superficial liquid velocity (Ul), nozzle diameter (Dn) and nozzle height (Hn) in the range of 0.0293-0.094m/s, 17.4-22.0mm and 50-400mm, respectively. For Dn=17.4mm, Hn=50 and 200mm, with ejector mode and regular operating procedure i.e. simultaneous entry of gas with increasing liquid velocity, had limitation of not establishing the circulation loop. To overcome this limitation a modified operating procedure i.e. entry of gas after established liquid circulation loop is proposed. Also the comparison of gas holdups with ejector and injector mode proves the effectiveness of ejector mode and can eliminate the supply of compressed gas. Thus proper choice of Dn, Hn and also the operating procedure becomes necessary. Copyright © 2012 Elsevier Ltd. All rights reserved.

Study on the stability and reliability of Clinotron at Y-band

NASA Astrophysics Data System (ADS)

Li, Shuang; Wang, Jianguo; Chen, Zaigao; Wang, Guangqiang; Wang, Dongyang; Teng, Yan

2017-11-01

To improve the stability and reliability of Clinotron at the Y-band, some key issues are researched, such as the synchronous operating mode, the heat accumulation on the slow-wave structure, and the errors in micro-fabrication. By analyzing the dispersion relationship, the working mode is determined as the TM10 mode. The problem of heat dissipation on a comb is researched to make a trade-off on the choice of suitable working conditions, making sure that the safety and efficiency of the device are guaranteed simultaneously. The study on the effect of tolerance on device's performance is also conducted to determine the acceptable error during micro-fabrication. The validity of the device and the cost for fabrication are both taken into consideration. At last, the performance of Clinotron under the optimized conditions demonstrates that it can work steadily at 315.89 GHz and the output power is about 12 W, showing advanced stability and reliability.

Whistlers, helicons, and lower hybrid waves: The physics of radio frequency wave propagation and absorption for current drive via Landau damping

DOE PAGES

Pinsker, Robert I.

2015-09-24

This introductory-level tutorial article describes the application of plasma waves in the lower hybrid range of frequencies for current drive in tokamaks. Wave damping mechanisms in a nearly collisionless hot magnetized plasma are briefly described, and the connections between the properties of the damping mechanisms and the optimal choices of wave properties (mode, frequency, wavelength) are explored. The two wave modes available for current drive in the lower hybrid range of frequencies (LHRF) are described and compared. The terms applied to these waves in different applications of plasma physics are elucidated. Here, the character of the ray paths of thesemore » waves in the LHRF is illustrated in slab and toroidal geometries. An upcoming experiment on one of these two wave modes, the “helicon” or “whistler”, to be carried out on the DIII-D tokamak, is described.« less

A novel adaptive switching function on fault tolerable sliding mode control for uncertain stochastic systems.

PubMed

Zahiripour, Seyed Ali; Jalali, Ali Akbar

2014-09-01

A novel switching function based on an optimization strategy for the sliding mode control (SMC) method has been provided for uncertain stochastic systems subject to actuator degradation such that the closed-loop system is globally asymptotically stable with probability one. In the previous researches the focus on sliding surface has been on proportional or proportional-integral function of states. In this research, from a degree of freedom that depends on designer choice is used to meet certain objectives. In the design of the switching function, there is a parameter which the designer can regulate for specified objectives. A sliding-mode controller is synthesized to ensure the reachability of the specified switching surface, despite actuator degradation and uncertainties. Finally, the simulation results demonstrate the effectiveness of the proposed method. Copyright © 2014 ISA. Published by Elsevier Ltd. All rights reserved.

Safety and efficacy of endovascular therapy and gamma knife surgery for brain arteriovenous malformations in China: Study protocol for an observational clinical trial.

PubMed

Jin, Hengwei; Huo, Xiaochuan; Jiang, Yuhua; Li, Xiaolong; Li, Youxiang

2017-09-01

Brain arteriovenous malformations (BAVMs) are associated with high morbidity and mortality. The treatment of BAVM remains controversial. Microinvasive treatment, including endovascular therapy and gamma knife surgery, has been the first choice in many conditions. However, the overall clinical outcome of microinvasive treatment remains unknown and a prospective trial is needed. This is a prospective, non-randomized, and multicenter observational registry clinical trial to evaluate the safety and efficacy of microinvasive treatment for BAVMs. The study will require up to 400 patients in approximately 12 or more centers in China, followed for 2 years. Main subjects of this study are BAVM patients underwent endovascular therapy and/or gamma knife surgery. The trial will not affect the choice of treatment modality. The primary outcomes are perioperative complications (safety), and postoperative hemorrhage incidence rate and complete occlusion rate (efficacy). Secondary outcomes are elimination of hemorrhage risk factors (coexisting aneurysms and arteriovenous fistula), volume reduction and remission of symptoms. Safety and efficacy of endovascular therapy, gamma knife surgery, and various combination modes of the two modalities will be compared. Operative complications and outcomes at pretreatment, post-treatment, at discharge and at 3 months, 6 months and 2 years follow-up intervals will be analyzed using the modified Rankin Scale (mRS). The most confusion on BAVM treatment is whether to choose interventional therapy or medical therapy, and the choice of interventional therapy modes. This study will provide evidence for evaluating the safety and efficacy of microinvasive treatment in China, to characterize the microinvasive treatment strategy for BAVMs.

Role of accentuation in the selection/rejection task framing effect.

PubMed

Chen, Jing; Proctor, Robert W

2017-04-01

Procedure invariance is a basic assumption of rational theories of choice, however, it has been shown to be violated: Different response modes, or task frames, sometimes reveal opposite preferences. The current study focused on selection and rejection task frames, involving a unique type of problem with enriched and impoverished options, which has previously led to conflicting findings and theoretical explanations: the compatibility hypothesis (Shafir, 1993) and the accentuation hypothesis (Wedell, 1997). We examined the role of task frame by distinguishing these 2 hypotheses and evaluating the information-processing basis of the choices. Experiments conducted online (Experiments 1 and 3) and in-lab (Experiment 4 with eye-tracking technique) revealed a difference between the 2 task frames in the choice data (i.e., the task-framing effect) as a function of the relative attractiveness of the options. Also, this task-framing effect was not influenced by imposed time constraints (Experiments 5 and 6) and was similarly evident with a more direct measure for the option attractiveness (obtained in Experiment 7). Experiment 2, conducted in a lab setting with verbal-protocol requirements, yielded no task-framing effect, suggesting that a requirement to verbalize reasons for choice minimizes accentuation. With this exception, the choice data are in agreement with the accentuation hypothesis, and the combined findings in choice, decision time, task confusion, and eye-tracking data provide evidence of a basis in cognitive effort rather than motivation, as Wedell proposed. (PsycINFO Database Record (c) 2017 APA, all rights reserved).

Task Analytic Models to Guide Analysis and Design: Use of the Operator Function Model to Represent Pilot-Autoflight System Mode Problems

NASA Technical Reports Server (NTRS)

Degani, Asaf; Mitchell, Christine M.; Chappell, Alan R.; Shafto, Mike (Technical Monitor)

1995-01-01

Task-analytic models structure essential information about operator interaction with complex systems, in this case pilot interaction with the autoflight system. Such models serve two purposes: (1) they allow researchers and practitioners to understand pilots' actions; and (2) they provide a compact, computational representation needed to design 'intelligent' aids, e.g., displays, assistants, and training systems. This paper demonstrates the use of the operator function model to trace the process of mode engagements while a pilot is controlling an aircraft via the, autoflight system. The operator function model is a normative and nondeterministic model of how a well-trained, well-motivated operator manages multiple concurrent activities for effective real-time control. For each function, the model links the pilot's actions with the required information. Using the operator function model, this paper describes several mode engagement scenarios. These scenarios were observed and documented during a field study that focused on mode engagements and mode transitions during normal line operations. Data including time, ATC clearances, altitude, system states, and active modes and sub-modes, engagement of modes, were recorded during sixty-six flights. Using these data, seven prototypical mode engagement scenarios were extracted. One scenario details the decision of the crew to disengage a fully automatic mode in favor of a semi-automatic mode, and the consequences of this action. Another describes a mode error involving updating aircraft speed following the engagement of a speed submode. Other scenarios detail mode confusion at various phases of the flight. This analysis uses the operator function model to identify three aspects of mode engagement: (1) the progress of pilot-aircraft-autoflight system interaction; (2) control/display information required to perform mode management activities; and (3) the potential cause(s) of mode confusion. The goal of this paper is twofold: (1) to demonstrate the use of the operator functio model methodology to describe pilot-system interaction while engaging modes And monitoring the system, and (2) to initiate a discussion of how task-analytic models might inform design processes. While the operator function model is only one type of task-analytic representation, the hypothesis of this paper is that some type of task analytic structure is a prerequisite for the design of effective human-automation interaction.

An Extrinsic Fabry-Perot Interferometric Sensor using Intermodal Phase Shifting and Demultiplexing of the Propagating Modes in a Few-Mode Fiber

NASA Astrophysics Data System (ADS)

Chatterjee, Julius

This dissertation demonstrates a fiber-optic phase shifted Fabry-Perot interferometer (PS-FPI) as a sensor using modal demultiplexing. Single wavelength Fabry-Perot interferometers suffer from fringe ambiguity and loss of sensitivity at fringe extremes. These hindrances cause it to be a secondary choice when being selected for a measurement task at hand, and more often than not, white light based sensors are selected in favor of the single wavelength Fabry-Perot sensors. This work aims to introduce a technique involving the demultiplexing of the propagating linearly polarized (LP) modes in few mode fibers to obtain two fringe systems from the same sensing cavity. This results in a few-mode interferometer that effectively has two to three orders of magnitude higher perturbation sensitivity than a conventional few mode interferometer for the same sensing region. In this work, two different modal demultiplexing techniques (MD) are used to demodulate the propagating modes and to obtain two fringe sets. These output fringe sets are shifted in phase with respect to each other by a phase shift due to the propagation of the modes in the fiber-optic layout. A method of controlling this phase shift by straining a length of a two mode fiber located separate from the PS-FPI cavity is demonstrated and corresponding changes in phase shifts are shown. The results show a controllable phase shift for both the MD techniques, which is useful in sensing by permitting quadrature demodulation of interferometric fringes and also results in a novel few-mode sensing system having more than two orders of magnitude sensitivity than conventional few-mode devices.

Models of Affective Decision Making: How Do Feelings Predict Choice?

PubMed

Charpentier, Caroline J; De Neve, Jan-Emmanuel; Li, Xinyi; Roiser, Jonathan P; Sharot, Tali

2016-06-01

Intuitively, how you feel about potential outcomes will determine your decisions. Indeed, an implicit assumption in one of the most influential theories in psychology, prospect theory, is that feelings govern choice. Surprisingly, however, very little is known about the rules by which feelings are transformed into decisions. Here, we specified a computational model that used feelings to predict choices. We found that this model predicted choice better than existing value-based models, showing a unique contribution of feelings to decisions, over and above value. Similar to the value function in prospect theory, our feeling function showed diminished sensitivity to outcomes as value increased. However, loss aversion in choice was explained by an asymmetry in how feelings about losses and gains were weighted when making a decision, not by an asymmetry in the feelings themselves. The results provide new insights into how feelings are utilized to reach a decision. © The Author(s) 2016.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Podesta, M.; Gorelenkova, M.; Fredrickson, E. D.

Here, integrated simulations of tokamak discharges typically rely on classical physics to model energetic particle (EP) dynamics. However, there are numerous cases in which energetic particles can suffer additional transport that is not classical in nature. Examples include transport by applied 3D magnetic perturbations and, more notably, by plasma instabilities. Focusing on the effects of instabilities,ad-hocmodels can empirically reproduce increased transport, but the choice of transport coefficients is usually somehow arbitrary. New approaches based on physics-based reduced models are being developed to address those issues in a simplified way, while retaining a more correct treatment of resonant wave-particle interactions. Themore » kick model implemented in the tokamaktransport code TRANSP is an example of such reduced models. It includes modifications of the EP distribution by instabilities in real and velocity space, retaining correlations between transport in energy and space typical of resonant EP transport. The relevance of EP phase space modifications by instabilities is first discussed in terms of predicted fast ion distribution. Results are compared with those from a simple, ad-hoc diffusive model. It is then shown that the phase-space resolved model can also provide additional insight into important issues such as internal consistency of the simulations and mode stability through the analysis of the power exchanged between energetic particles and the instabilities.« less

Characteristic analysis-1981: Final program and a possible discovery

USGS Publications Warehouse

McCammon, R.B.; Botbol, J.M.; Sinding-Larsen, R.; Bowen, R.W.

1983-01-01

The latest ornewest version of thecharacteristicanalysis (NCHARAN)computer program offers the exploration geologist a wide variety of options for integrating regionalized multivariate data. The options include the selection of regional cells for characterizing deposit models, the selection of variables that constitute the models, and the choice of logical combinations of variables that best represent these models. Moreover, the program provides for the display of results which, in turn, makes possible review, reselection, and refinement of a model. Most important, the performance of the above-mentioned steps in an interactive computing mode can result in a timely and meaningful interpretation of the data available to the exploration geologist. The most recent application of characteristic analysis has resulted in the possible discovery of economic sulfide mineralization in the Grong area in central Norway. Exploration data for 27 geophysical, geological, and geochemical variables were used to construct a mineralized and a lithogeochemical model for an area that contained a known massive sulfide deposit. The models were applied to exploration data collected from the Gjersvik area in the Grong mining district and resulted in the identification of two localities of possible mineralization. Detailed field examination revealed the presence of a sulfide vein system and a partially inverted stratigraphic sequence indicating the possible presence of a massive sulfide deposit at depth. ?? 1983 Plenum Publishing Corporation.

Psychophysics of time perception and intertemporal choice models

NASA Astrophysics Data System (ADS)

Takahashi, Taiki; Oono, Hidemi; Radford, Mark H. B.

2008-03-01

Intertemporal choice and psychophysics of time perception have been attracting attention in econophysics and neuroeconomics. Several models have been proposed for intertemporal choice: exponential discounting, general hyperbolic discounting (exponential discounting with logarithmic time perception of the Weber-Fechner law, a q-exponential discount model based on Tsallis's statistics), simple hyperbolic discounting, and Stevens' power law-exponential discounting (exponential discounting with Stevens' power time perception). In order to examine the fitness of the models for behavioral data, we estimated the parameters and AICc (Akaike Information Criterion with small sample correction) of the intertemporal choice models by assessing the points of subjective equality (indifference points) at seven delays. Our results have shown that the orders of the goodness-of-fit for both group and individual data were [Weber-Fechner discounting (general hyperbola) > Stevens' power law discounting > Simple hyperbolic discounting > Exponential discounting], indicating that human time perception in intertemporal choice may follow the Weber-Fechner law. Indications of the results for neuropsychopharmacological treatments of addiction and biophysical processing underlying temporal discounting and time perception are discussed.

Lateral Orbitofrontal Inactivation Dissociates Devaluation-Sensitive Behavior and Economic Choice.

PubMed

Gardner, Matthew P H; Conroy, Jessica S; Shaham, Michael H; Styer, Clay V; Schoenbaum, Geoffrey

2017-12-06

How do we choose between goods that have different subjective values, like apples and oranges? Neuroeconomics proposes that this is done by reducing complex goods to a single unitary value to allow comparison. This value is computed "on the fly" from the underlying model of the goods space, allowing decisions to meet current needs. This is termed "model-based" behavior to distinguish it from pre-determined, habitual, or "model-free" behavior. The lateral orbitofrontal cortex (OFC) supports model-based behavior in rats and primates, but whether the OFC is necessary for economic choice is less clear. Here we tested this question by optogenetically inactivating the lateral OFC in rats in a classic model-based task and during economic choice. Contrary to predictions, inactivation disrupted model-based behavior without affecting economic choice. Published by Elsevier Inc.

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

NASA Technical Reports Server (NTRS)

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

A likelihood-based biostatistical model for analyzing consumer movement in simultaneous choice experiments.

PubMed

Zeilinger, Adam R; Olson, Dawn M; Andow, David A

2014-08-01

Consumer feeding preference among resource choices has critical implications for basic ecological and evolutionary processes, and can be highly relevant to applied problems such as ecological risk assessment and invasion biology. Within consumer choice experiments, also known as feeding preference or cafeteria experiments, measures of relative consumption and measures of consumer movement can provide distinct and complementary insights into the strength, causes, and consequences of preference. Despite the distinct value of inferring preference from measures of consumer movement, rigorous and biologically relevant analytical methods are lacking. We describe a simple, likelihood-based, biostatistical model for analyzing the transient dynamics of consumer movement in a paired-choice experiment. With experimental data consisting of repeated discrete measures of consumer location, the model can be used to estimate constant consumer attraction and leaving rates for two food choices, and differences in choice-specific attraction and leaving rates can be tested using model selection. The model enables calculation of transient and equilibrial probabilities of consumer-resource association, which could be incorporated into larger scale movement models. We explore the effect of experimental design on parameter estimation through stochastic simulation and describe methods to check that data meet model assumptions. Using a dataset of modest sample size, we illustrate the use of the model to draw inferences on consumer preference as well as underlying behavioral mechanisms. Finally, we include a user's guide and computer code scripts in R to facilitate use of the model by other researchers.

Design and Development of a User Interface for the Dynamic Model of Software Project Management.

DTIC Science & Technology

1988-03-01

rectory of the user’s choice for future...the last choice selected. Let us assume for the sake of this tour that the user has selected all eight choices . ESTIMATED ACTUAL PROJECT SIZE DEFINITION...manipulation of varaibles in the * •. TJin~ca model "h ... ser Inter ace for the Dynamica model was designed b in iterative process of prototyping

An aggregate method to calibrate the reference point of cumulative prospect theory-based route choice model for urban transit network

NASA Astrophysics Data System (ADS)

Zhang, Yufeng; Long, Man; Luo, Sida; Bao, Yu; Shen, Hanxia

2015-12-01

Transit route choice model is the key technology of public transit systems planning and management. Traditional route choice models are mostly based on expected utility theory which has an evident shortcoming that it cannot accurately portray travelers' subjective route choice behavior for their risk preferences are not taken into consideration. Cumulative prospect theory (CPT), a brand new theory, can be used to describe travelers' decision-making process under the condition of uncertainty of transit supply and risk preferences of multi-type travelers. The method to calibrate the reference point, a key parameter to CPT-based transit route choice model, determines the precision of the model to a great extent. In this paper, a new method is put forward to obtain the value of reference point which combines theoretical calculation and field investigation results. Comparing the proposed method with traditional method, it shows that the new method can promote the quality of CPT-based model by improving the accuracy in simulating travelers' route choice behaviors based on transit trip investigation from Nanjing City, China. The proposed method is of great significance to logical transit planning and management, and to some extent makes up the defect that obtaining the reference point is solely based on qualitative analysis.

Patient or physician preferences for decision analysis: the prenatal genetic testing decision.

PubMed

Heckerling, P S; Verp, M S; Albert, N

1999-01-01

The choice between amniocentesis and chorionic villus sampling for prenatal genetic testing involves tradeoffs of the benefits and risks of the tests. Decision analysis is a method of explicitly weighing such tradeoffs. The authors examined the relationship between prenatal test choices made by patients and the choices prescribed by decision-analytic models based on their preferences, and separate models based on the preferences of their physicians. Preferences were assessed using written scenarios describing prenatal testing outcomes, and were recorded on linear rating scales. After adjustment for sociodemographic and obstetric confounders, test choice was significantly associated with the choice of decision models based on patient preferences (odds ratio 4.44; Cl, 2.53 to 7.78), but not with the choice of models based on the preferences of the physicians (odds ratio 1.60; Cl, 0.79 to 3.26). Agreement between decision analyses based on patient preferences and on physician preferences was little better than chance (kappa = 0.085+/-0.063). These results were robust both to changes in the decision-analytic probabilities and to changes in the model structure itself to simulate non-expected utility decision rules. The authors conclude that patient but not physician preferences, incorporated in decision models, correspond to the choice of amniocentesis or chorionic villus sampling made by the patient. Nevertheless, because patient preferences were assessed after referral for genetic testing, prospective preference-assessment studies will be necessary to confirm this association.

Calculations of the variability of ice cloud radiative properties at selected solar wavelengths

NASA Technical Reports Server (NTRS)

Welch, R. M.; Zdunkowski, W. G.; Cox, S. K.

1980-01-01

This study shows that there is surprising little difference in values of reflectance, absorptance, and transmittance for many of the intermediate-size particle spectra. Particle size distributions with mode radii ranging from approximately 50 to 300 microns, irrespective of particle shape and nearly independent of the choice of size distribution representation, give relatively similar flux values. The very small particle sizes, however, have significantly larger values of reflectance and transmittance with corresponding smaller values of absorptance than do the larger particle sizes. The very large particle modes produce very small values of reflectance and transmittance along with very large values of absorptance. Such variations are particularly noticeable when plotted as a function of wavelength.

A new device for energy-dispersive x-ray fluorescence

NASA Astrophysics Data System (ADS)

Swoboda, Walter; Kanngiesser, Birgit; Beckhoff, Burkhard; Begemann, Klaus; Neuhaus, Hermann; Scheer, Jens

1991-12-01

A new measuring chamber for energy-dispersive x-ray fluorescence is presented, which allows excitation of the sample by three (commonly applied) modes: secondary target excitation, Barkla scattering, and Bragg reflection. In spite of the short distances required to obtain high intensities, the transmission of the radiator through the bulk matter of the chamber wall and the collimators could be kept negligibly small. In the case of Bragg reflection, the adjustment of all degrees of freedom of the crystal is performed independently and reproducibly under vacuum conditions. The device allows the choice of excitation mode optimized for the respective analytical problem. An experimental test using an environmental specimen shows the detection limits obtainable.

A component modes projection and assembly model reduction methodology for articulated, multi-flexible body structures

NASA Technical Reports Server (NTRS)

Lee, Allan Y.; Tsuha, Walter S.

1993-01-01

A two-stage model reduction methodology, combining the classical Component Mode Synthesis (CMS) method and the newly developed Enhanced Projection and Assembly (EP&A) method, is proposed in this research. The first stage of this methodology, called the COmponent Modes Projection and Assembly model REduction (COMPARE) method, involves the generation of CMS mode sets, such as the MacNeal-Rubin mode sets. These mode sets are then used to reduce the order of each component model in the Rayleigh-Ritz sense. The resultant component models are then combined to generate reduced-order system models at various system configurations. A composite mode set which retains important system modes at all system configurations is then selected from these reduced-order system models. In the second stage, the EP&A model reduction method is employed to reduce further the order of the system model generated in the first stage. The effectiveness of the COMPARE methodology has been successfully demonstrated on a high-order, finite-element model of the cruise-configured Galileo spacecraft.

Optimal Decision Stimuli for Risky Choice Experiments: An Adaptive Approach.

PubMed

Cavagnaro, Daniel R; Gonzalez, Richard; Myung, Jay I; Pitt, Mark A

2013-02-01

Collecting data to discriminate between models of risky choice requires careful selection of decision stimuli. Models of decision making aim to predict decisions across a wide range of possible stimuli, but practical limitations force experimenters to select only a handful of them for actual testing. Some stimuli are more diagnostic between models than others, so the choice of stimuli is critical. This paper provides the theoretical background and a methodological framework for adaptive selection of optimal stimuli for discriminating among models of risky choice. The approach, called Adaptive Design Optimization (ADO), adapts the stimulus in each experimental trial based on the results of the preceding trials. We demonstrate the validity of the approach with simulation studies aiming to discriminate Expected Utility, Weighted Expected Utility, Original Prospect Theory, and Cumulative Prospect Theory models.

Does cost-effectiveness of influenza vaccine choice vary across the U.S.? An agent-based modeling study.

PubMed

DePasse, Jay V; Nowalk, Mary Patricia; Smith, Kenneth J; Raviotta, Jonathan M; Shim, Eunha; Zimmerman, Richard K; Brown, Shawn T

2017-07-13

In a prior agent-based modeling study, offering a choice of influenza vaccine type was shown to be cost-effective when the simulated population represented the large, Washington DC metropolitan area. This study calculated the public health impact and cost-effectiveness of the same four strategies: No Choice, Pediatric Choice, Adult Choice, or Choice for Both Age Groups in five United States (U.S.) counties selected to represent extremes in population age distribution. The choice offered was either inactivated influenza vaccine delivered intramuscularly with a needle (IIV-IM) or an age-appropriate needle-sparing vaccine, specifically, the nasal spray (LAIV) or intradermal (IIV-ID) delivery system. Using agent-based modeling, individuals were simulated as they interacted with others, and influenza was tracked as it spread through each population. Influenza vaccination coverage derived from Centers for Disease Control and Prevention (CDC) data, was increased by 6.5% (range 3.25%-11.25%) to reflect the effects of vaccine choice. Assuming moderate influenza infectivity, the number of averted cases was highest for the Choice for Both Age Groups in all five counties despite differing demographic profiles. In a cost-effectiveness analysis, Choice for Both Age Groups was the dominant strategy. Sensitivity analyses varying influenza infectivity, costs, and degrees of vaccine coverage increase due to choice, supported the base case findings. Offering a choice to receive a needle-sparing influenza vaccine has the potential to significantly reduce influenza disease burden and to be cost saving. Consistent findings across diverse populations confirmed these findings. Copyright © 2017 Elsevier Ltd. All rights reserved.