Executive Functions and Working Memory Behaviours in Children with a Poor Working Memory

ERIC Educational Resources Information Center

St. Clair-Thompson, Helen L.

2011-01-01

Previous research has suggested that working memory difficulties play an integral role in children's underachievement at school. However, working memory is just one of several executive functions. The extent to which problems in working memory extend to other executive functions is not well understood. In the current study 38 children with a poor…

An approximate Riemann solver for magnetohydrodynamics (that works in more than one dimension)

NASA Technical Reports Server (NTRS)

Powell, Kenneth G.

1994-01-01

An approximate Riemann solver is developed for the governing equations of ideal magnetohydrodynamics (MHD). The Riemann solver has an eight-wave structure, where seven of the waves are those used in previous work on upwind schemes for MHD, and the eighth wave is related to the divergence of the magnetic field. The structure of the eighth wave is not immediately obvious from the governing equations as they are usually written, but arises from a modification of the equations that is presented in this paper. The addition of the eighth wave allows multidimensional MHD problems to be solved without the use of staggered grids or a projection scheme, one or the other of which was necessary in previous work on upwind schemes for MHD. A test problem made up of a shock tube with rotated initial conditions is solved to show that the two-dimensional code yields answers consistent with the one-dimensional methods developed previously.

Characteristic of cognitive decline in Parkinson's disease: a 1-year follow-up.

PubMed

McKinlay, Audrey; Grace, Randolph C

2011-10-01

The aim of this study was to track the evolution of cognitive decline in Parkinson's disease (PD) patients 1 year after baseline testing. Thirty-three PD patients, divided according to three previously determined subgroups based on their initial cognitive performance, and a healthy comparison group were reassessed after a 1-year interval. Participants were assessed in the following five domains: Executive Function, Problem Solving, Working Memory/Attention, Memory, and Visuospatial Ability. The PD groups differed on the domains of Executive Function, Problem Solving, and Working Memory, with the most severe deficits being evident for the group that had previously shown the greatest level of impairment. Increased cognitive problems were also associated with decreased functioning in activities of daily living. The most severely impaired group had evidence of global cognitive decline, possibly reflecting a stage of preclinical dementia.

What works with worked examples: Extending self-explanation and analogical comparison to synthesis problems

NASA Astrophysics Data System (ADS)

Badeau, Ryan; White, Daniel R.; Ibrahim, Bashirah; Ding, Lin; Heckler, Andrew F.

2017-12-01

The ability to solve physics problems that require multiple concepts from across the physics curriculum—"synthesis" problems—is often a goal of physics instruction. Three experiments were designed to evaluate the effectiveness of two instructional methods employing worked examples on student performance with synthesis problems; these instructional techniques, analogical comparison and self-explanation, have previously been studied primarily in the context of single-concept problems. Across three experiments with students from introductory calculus-based physics courses, both self-explanation and certain kinds of analogical comparison of worked examples significantly improved student performance on a target synthesis problem, with distinct improvements in recognition of the relevant concepts. More specifically, analogical comparison significantly improved student performance when the comparisons were invoked between worked synthesis examples. In contrast, similar comparisons between corresponding pairs of worked single-concept examples did not significantly improve performance. On a more complicated synthesis problem, self-explanation was significantly more effective than analogical comparison, potentially due to differences in how successfully students encoded the full structure of the worked examples. Finally, we find that the two techniques can be combined for additional benefit, with the trade-off of slightly more time on task.

Multiobjective Resource-Constrained Project Scheduling with a Time-Varying Number of Tasks

PubMed Central

Abello, Manuel Blanco

2014-01-01

In resource-constrained project scheduling (RCPS) problems, ongoing tasks are restricted to utilizing a fixed number of resources. This paper investigates a dynamic version of the RCPS problem where the number of tasks varies in time. Our previous work investigated a technique called mapping of task IDs for centroid-based approach with random immigrants (McBAR) that was used to solve the dynamic problem. However, the solution-searching ability of McBAR was investigated over only a few instances of the dynamic problem. As a consequence, only a small number of characteristics of McBAR, under the dynamics of the RCPS problem, were found. Further, only a few techniques were compared to McBAR with respect to its solution-searching ability for solving the dynamic problem. In this paper, (a) the significance of the subalgorithms of McBAR is investigated by comparing McBAR to several other techniques; and (b) the scope of investigation in the previous work is extended. In particular, McBAR is compared to a technique called, Estimation Distribution Algorithm (EDA). As with McBAR, EDA is applied to solve the dynamic problem, an application that is unique in the literature. PMID:24883398

Usability Flaws in Medication Alerting Systems: Impact on Usage and Work System.

PubMed

Marcilly, R; Ammenwerth, E; Roehrer, E; Pelayo, S; Vasseur, F; Beuscart-Zéphir, M-C

2015-08-13

Previous research has shown that medication alerting systems face usability issues. There has been no previous attempt to systematically explore the consequences of usability flaws in such systems on users (i.e. usage problems) and work systems (i.e. negative outcomes). This paper aims at exploring and synthesizing the consequences of usability flaws in terms of usage problems and negative outcomes on the work system. A secondary analysis of 26 papers included in a prior systematic review of the usability flaws in medication alerting was performed. Usage problems and negative outcomes were extracted and sorted. Links between usability flaws, usage problems, and negative outcomes were also analyzed. Poor usability generates a large variety of consequences. It impacts the user from a cognitive, behavioral, emotional, and attitudinal perspective. Ultimately, usability flaws have negative consequences on the workflow, the effectiveness of the technology, the medication management process, and, more importantly, patient safety. Only few complete pathways leading from usability flaws to negative outcomes were identified. Usability flaws in medication alerting systems impede users, and ultimately their work system, and negatively impact patient safety. Therefore, the usability dimension may act as a hidden explanatory variable that could explain, at least partly, the (absence of) intended outcomes of new technology.

Usability Flaws in Medication Alerting Systems: Impact on Usage and Work System

PubMed Central

Ammenwerth, E.; Roehrer, E.; Pelayo, S.; Vasseur, F.; Beuscart-Zéphir, M.-C.

2015-01-01

Summary Objectives Previous research has shown that medication alerting systems face usability issues. There has been no previous attempt to systematically explore the consequences of usability flaws in such systems on users (i.e. usage problems) and work systems (i.e. negative outcomes). This paper aims at exploring and synthesizing the consequences of usability flaws in terms of usage problems and negative outcomes on the work system. Methods A secondary analysis of 26 papers included in a prior systematic review of the usability flaws in medication alerting was performed. Usage problems and negative outcomes were extracted and sorted. Links between usability flaws, usage problems, and negative outcomes were also analyzed. Results Poor usability generates a large variety of consequences. It impacts the user from a cognitive, behavioral, emotional, and attitudinal perspective. Ultimately, usability flaws have negative consequences on the workflow, the effectiveness of the technology, the medication management process, and, more importantly, patient safety. Only few complete pathways leading from usability flaws to negative outcomes were identified. Conclusion Usability flaws in medication alerting systems impede users, and ultimately their work system, and negatively impact patient safety. Therefore, the usability dimension may act as a hidden explanatory variable that could explain, at least partly, the (absence of) intended outcomes of new technology. PMID:26123906

Teachers' Perceptions of Employment-Related Problems: A Survey of Teachers in Two States.

ERIC Educational Resources Information Center

Cutrer, Susan S.; Daniel, Larry G.

This study was conducted to determine the degree to which a randomly selected sample of teachers in Mississippi and Louisiana (N=291) experience various types of work-related problems. It provides an opportunity to either confirm or deny the findings of previous studies, many of them limited by various methodological problems. Data were collected…

Study of viscous flow about airfoils by the integro-differential method

NASA Technical Reports Server (NTRS)

Wu, J. C.; Sampath, S.

1975-01-01

An integro-differential method was used for numerically solving unsteady incompressible viscous flow problems. A computer program was prepared to solve the problem of an impulsively started 9% thick symmetric Joukowski airfoil at an angle of attack of 15 deg and a Reynolds number of 1000. Some of the results obtained for this problem were discussed and compared with related work completed previously. Two numerical procedures were used, an Alternating Direction Implicit (ADI) method and a Successive Line Relaxation (SLR) method. Generally, the ADI solution agrees well with the SLR solution and with previous results are stations away from the trailing edge. At the trailing edge station, the ADI solution differs substantially from previous results, while the vorticity profiles obtained from the SLR method there are in good qualitative agreement with previous results.

Return to work after vocational rehabilitation for sick-listed workers with long-term back, neck and shoulder problems: A follow-up study of factors involved.

PubMed

Rinaldo, Ulrika; Selander, John

2016-09-27

Absence from work due to musculoskeletal disorders is a significant problem from a number of perspectives, and there is a great need to identify factors that facilitate return to work (RTW). To identify factors related to RTW after vocational rehabilitation for sick-listed workers with long-term back, neck and/or shoulder problems, and to compare the results with those from a previous literature review based on studies from 1980 to 2000. A literature review based on studies published 2001-2014 in PubMed, CINAHL, EMBASE, ERIC and the Cochrane Library. Major risk factors for not returning to work are: higher age, factors related to pain such as higher levels of pain and pain related fear, avoidance of activity, high distress and depression. Facilitating factors for RTW are: lower functional disability, gaining control over one's own condition, believing in RTW and work-related factors such as occupational training, and having a job coach or an RTW coordinator. Compared with the results from the previous review, the present review shows less of a focus on sociodemographic factors and more on psychological factors. Both studies highlight risk factors such as older age, higher levels of pain, depression and less internal locus of control. Psychosocial and work-related factors are important and should be included in interventions for the RTW of people with long-term back, neck and/or shoulder problems.

Macroscopic relationship in primal-dual portfolio optimization problem

NASA Astrophysics Data System (ADS)

Shinzato, Takashi

2018-02-01

In the present paper, using a replica analysis, we examine the portfolio optimization problem handled in previous work and discuss the minimization of investment risk under constraints of budget and expected return for the case that the distribution of the hyperparameters of the mean and variance of the return rate of each asset are not limited to a specific probability family. Findings derived using our proposed method are compared with those in previous work to verify the effectiveness of our proposed method. Further, we derive a Pythagorean theorem of the Sharpe ratio and macroscopic relations of opportunity loss. Using numerical experiments, the effectiveness of our proposed method is demonstrated for a specific situation.

Methodes entropiques appliquees au probleme inverse en magnetoencephalographie

NASA Astrophysics Data System (ADS)

Lapalme, Ervig

2005-07-01

This thesis is devoted to biomagnetic source localization using magnetoencephalography. This problem is known to have an infinite number of solutions. So methods are required to take into account anatomical and functional information on the solution. The work presented in this thesis uses the maximum entropy on the mean method to constrain the solution. This method originates from statistical mechanics and information theory. This thesis is divided into two main parts containing three chapters each. The first part reviews the magnetoencephalographic inverse problem: the theory needed to understand its context and the hypotheses for simplifying the problem. In the last chapter of this first part, the maximum entropy on the mean method is presented: its origins are explained and also how it is applied to our problem. The second part is the original work of this thesis presenting three articles; one of them already published and two others submitted for publication. In the first article, a biomagnetic source model is developed and applied in a theoretical con text but still demonstrating the efficiency of the method. In the second article, we go one step further towards a realistic modelization of the cerebral activation. The main priors are estimated using the magnetoencephalographic data. This method proved to be very efficient in realistic simulations. In the third article, the previous method is extended to deal with time signals thus exploiting the excellent time resolution offered by magnetoencephalography. Compared with our previous work, the temporal method is applied to real magnetoencephalographic data coming from a somatotopy experience and results agree with previous physiological knowledge about this kind of cognitive process.

Efficient Planning of Wind-Optimal Routes in North Atlantic Oceanic Airspace

NASA Technical Reports Server (NTRS)

Rodionova, Olga; Sridhar, Banavar

2017-01-01

The North Atlantic oceanic airspace (NAT) is crossed daily by more than a thousand flights, which are greatly affected by strong jet stream air currents. Several studies devoted to generating wind-optimal (WO) aircraft trajectories in the NAT demonstrated great efficiency of such an approach for individual flights. However, because of the large separation norms imposed in the NAT, previously proposed WO trajectories induce a large number of potential conflicts. Much work has been done on strategic conflict detection and resolution (CDR) in the NAT. The work presented here extends previous methods and attempts to take advantage of the NAT traffic structure to simplify the problem and improve the results of CDR. Four approaches are studied in this work: 1) subdividing the existing CDR problem into sub-problems of smaller sizes, which are easier to handle; 2) more efficient data reorganization within the considered time period; 3) problem localization, i.e. concentrating the resolution effort in the most conflicted regions; 4) applying CDR to the pre-tactical decision horizon (a couple of hours in advance). Obtained results show that these methods efficiently resolve potential conflicts at the strategic and pre-tactical levels by keeping the resulting trajectories close to the initial WO ones.

"Aprender a Convivir." A Prevention Program for Improving Social Competence in Three-to Seven-Year-Olds

ERIC Educational Resources Information Center

Alba, Guadalupe; Justicia-Arraez, Ana; Pichardo, M. Carmen; Justicia-Justicia, Fernando

2013-01-01

Behavior problems are often observed in classrooms. The age at which problems appears is increasingly younger, and there are no interventions that ensure a reduction in such behavior problems among school age children. Research and previous evidence show the importance of social competence in this kind of prevention. Working with preschool and…

Solving Large Problems with a Small Working Memory

ERIC Educational Resources Information Center

Pizlo, Zygmunt; Stefanov, Emil

2013-01-01

We describe an important elaboration of our multiscale/multiresolution model for solving the Traveling Salesman Problem (TSP). Our previous model emulated the non-uniform distribution of receptors on the human retina and the shifts of visual attention. This model produced near-optimal solutions of TSP in linear time by performing hierarchical…

Dynamic Cognitive Tracing: Towards Unified Discovery of Student and Cognitive Models

ERIC Educational Resources Information Center

Gonzalez-Brenes, Jose P.; Mostow, Jack

2012-01-01

This work describes a unified approach to two problems previously addressed separately in Intelligent Tutoring Systems: (i) Cognitive Modeling, which factorizes problem solving steps into the latent set of skills required to perform them; and (ii) Student Modeling, which infers students' learning by observing student performance. The practical…

Nonlinear Multidimensional Assignment Problems Efficient Conic Optimization Methods and Applications

DTIC Science & Technology

2015-06-24

WORK UNIT NUMBER 7. PERFORMING ORGANIZATION NAME(S) AND ADDRESS(ES) Arizona State University School of Mathematical & Statistical Sciences 901 S...SUPPLEMENTARY NOTES 14. ABSTRACT The major goals of this project were completed: the exact solution of previously unsolved challenging combinatorial optimization... combinatorial optimization problem, the Directional Sensor Problem, was solved in two ways. First, heuristically in an engineering fashion and second, exactly

Tracking It Down: Predictors of Risky Drinking in an Australian Railway.

ERIC Educational Resources Information Center

Zinkiewicz, Lucy; Davey, Jeremy; Obst, Patricia; Sheehan, Mary

1999-01-01

Surveys employees (N=4,979) of an Australian state railway to determine self-reported employee alcohol use and the influence of work-related risk factors on this use. Examination of risk factors previously associated with work-related problem drinking showed that gender, nights away from home for work, job satisfaction, and availability of alcohol…

Models of performance of evolutionary program induction algorithms based on indicators of problem difficulty.

PubMed

Graff, Mario; Poli, Riccardo; Flores, Juan J

2013-01-01

Modeling the behavior of algorithms is the realm of evolutionary algorithm theory. From a practitioner's point of view, theory must provide some guidelines regarding which algorithm/parameters to use in order to solve a particular problem. Unfortunately, most theoretical models of evolutionary algorithms are difficult to apply to realistic situations. However, in recent work (Graff and Poli, 2008, 2010), where we developed a method to practically estimate the performance of evolutionary program-induction algorithms (EPAs), we started addressing this issue. The method was quite general; however, it suffered from some limitations: it required the identification of a set of reference problems, it required hand picking a distance measure in each particular domain, and the resulting models were opaque, typically being linear combinations of 100 features or more. In this paper, we propose a significant improvement of this technique that overcomes the three limitations of our previous method. We achieve this through the use of a novel set of features for assessing problem difficulty for EPAs which are very general, essentially based on the notion of finite difference. To show the capabilities or our technique and to compare it with our previous performance models, we create models for the same two important classes of problems-symbolic regression on rational functions and Boolean function induction-used in our previous work. We model a variety of EPAs. The comparison showed that for the majority of the algorithms and problem classes, the new method produced much simpler and more accurate models than before. To further illustrate the practicality of the technique and its generality (beyond EPAs), we have also used it to predict the performance of both autoregressive models and EPAs on the problem of wind speed forecasting, obtaining simpler and more accurate models that outperform in all cases our previous performance models.

Transitions in Learning: Evidence for Simultaneously Activated Strategies.

ERIC Educational Resources Information Center

Goldin-Meadow, Susan; And Others

Children rarely cite more than one strategy when asked to explain how they solved a particular arithmetic problem, hence their verbal explanations will not necessarily reveal whether they have considered multiple strategies on that problem. However, previous work has shown that, when asked to explain their performance on a task, children often use…

School Social Work with Students with Mental Health Problems: Examining Different Practice Approaches

ERIC Educational Resources Information Center

McManama O'Brien, Kimberly H.; Berzin, Stephanie C.; Kelly, Michael S.; Frey, Andy J.; Alvarez, Michelle E.; Shaffer, Gary L.

2011-01-01

School social workers frequently serve as the primary mental health providers to youths with mental health problems. Although school social workers play a primary role in care, many students also receive outside counseling services. Previous research has not examined whether practice approaches differ when considering mental health practice with…

General Definitions of Work and Heat in Thermodynamic Processes.

ERIC Educational Resources Information Center

Gislason, Eric A.; Craig, Norman C.

1987-01-01

Argues that previous definitions of work and heat are inappropriate. Presents new definitions that are formulated using experimental quantities, claiming that they apply equally well to reversible and irreversible processes. Indicates some of the problems with earlier definitions and applies the new definitions to the First Law of thermodynamics.…

Application of response surface techniques to helicopter rotor blade optimization procedure

NASA Technical Reports Server (NTRS)

Henderson, Joseph Lynn; Walsh, Joanne L.; Young, Katherine C.

1995-01-01

In multidisciplinary optimization problems, response surface techniques can be used to replace the complex analyses that define the objective function and/or constraints with simple functions, typically polynomials. In this work a response surface is applied to the design optimization of a helicopter rotor blade. In previous work, this problem has been formulated with a multilevel approach. Here, the response surface takes advantage of this decomposition and is used to replace the lower level, a structural optimization of the blade. Problems that were encountered and important considerations in applying the response surface are discussed. Preliminary results are also presented that illustrate the benefits of using the response surface.

Invariant Manifolds, the Spatial Three-Body Problem and Space Mission Design

NASA Technical Reports Server (NTRS)

Gomez, G.; Koon, W. S.; Lo, Martin W.; Marsden, J. E.; Masdemont, J.; Ross, S. D.

2001-01-01

The invariant manifold structures of the collinear libration points for the spatial restricted three-body problem provide the framework for understanding complex dynamical phenomena from a geometric point of view. In particular, the stable and unstable invariant manifold 'tubes' associated to libration point orbits are the phase space structures that provide a conduit for orbits between primary bodies for separate three-body systems. These invariant manifold tubes can be used to construct new spacecraft trajectories, such as 'Petit Grand Tour' of the moons of Jupiter. Previous work focused on the planar circular restricted three-body problem. The current work extends the results to the spatial case.

Alternative Constraint Handling Technique for Four-Bar Linkage Path Generation

NASA Astrophysics Data System (ADS)

Sleesongsom, S.; Bureerat, S.

2018-03-01

This paper proposes an extension of a new concept for path generation from our previous work by adding a new constraint handling technique. The propose technique was initially designed for problems without prescribed timing by avoiding the timing constraint, while remain constraints are solving with a new constraint handling technique. The technique is one kind of penalty technique. The comparative study is optimisation of path generation problems are solved using self-adaptive population size teaching-learning based optimization (SAP-TLBO) and original TLBO. In this study, two traditional path generation test problem are used to test the proposed technique. The results show that the new technique can be applied with the path generation problem without prescribed timing and gives better results than the previous technique. Furthermore, SAP-TLBO outperforms the original one.

Towards a Cognitively Realistic Computational Model of Team Problem Solving Using ACT-R Agents and the ELICIT Experimentation Framework

DTIC Science & Technology

2014-06-01

intelligence analysis processes. However, as has been noted in previous work (e.g., [42]), there are a number of important differences between the nature of the...problem encountered in the context of the ELICIT task and the problems dealt with by intelligence analysts. Perhaps most importantly, the fact that a...see Section 7). 6 departure from the reality of most intelligence analysis situations: in most real-world intelligence analysis problems agents have

Scalar discrete nonlinear multipoint boundary value problems

NASA Astrophysics Data System (ADS)

Rodriguez, Jesus; Taylor, Padraic

2007-06-01

In this paper we provide sufficient conditions for the existence of solutions to scalar discrete nonlinear multipoint boundary value problems. By allowing more general boundary conditions and by imposing less restrictions on the nonlinearities, we obtain results that extend previous work in the area of discrete boundary value problems [Debra L. Etheridge, Jesus Rodriguez, Periodic solutions of nonlinear discrete-time systems, Appl. Anal. 62 (1996) 119-137; Debra L. Etheridge, Jesus Rodriguez, Scalar discrete nonlinear two-point boundary value problems, J. Difference Equ. Appl. 4 (1998) 127-144].

A low-rank matrix recovery approach for energy efficient EEG acquisition for a wireless body area network.

PubMed

Majumdar, Angshul; Gogna, Anupriya; Ward, Rabab

2014-08-25

We address the problem of acquiring and transmitting EEG signals in Wireless Body Area Networks (WBAN) in an energy efficient fashion. In WBANs, the energy is consumed by three operations: sensing (sampling), processing and transmission. Previous studies only addressed the problem of reducing the transmission energy. For the first time, in this work, we propose a technique to reduce sensing and processing energy as well: this is achieved by randomly under-sampling the EEG signal. We depart from previous Compressed Sensing based approaches and formulate signal recovery (from under-sampled measurements) as a matrix completion problem. A new algorithm to solve the matrix completion problem is derived here. We test our proposed method and find that the reconstruction accuracy of our method is significantly better than state-of-the-art techniques; and we achieve this while saving sensing, processing and transmission energy. Simple power analysis shows that our proposed methodology consumes considerably less power compared to previous CS based techniques.

Stability of Shapes Held by Surface Tension and Subjected to Flow

NASA Technical Reports Server (NTRS)

Chen, Yi-Ju; Robinson, Nathaniel D.; Steen, Paul H.

1999-01-01

Results of three problems are summarized in this contribution. Each involves the fundamental capillary instability of an interfacial bridge and is an extension of previous work. The first two problems concern equilibrium shapes of liquid bridges near the stability boundary corresponding to maximum length (Plateau-Rayleigh limit). For the first problem, a previously formulated nonlinear theory to account for imposed gravity and interfacial shear disturbances in an isothermal environment is quantitatively tested in experiment. For the second problem, the liquid bridge is subjected to a shear that models the effect of a thermocapillary flow generated by a ring heater in a liquid encapsulated float-zone configuration. In the absence of gravity, this symmetric perturbation can stabilize the bridge to lengths on the order of 30 percent beyond the Plateau-Rayleigh limit, which is on the order of heretofore unexplained Shuttle observations. The third problem considers the dynamics of collapse and pinchoff of a film bridge (no gravity), which happens in the absence of stabilization. Here, we summarize experimental efforts to measure the self-similar cone-and-crater structure predicted by a previous theory.

Prospective relationship between poor sleep and substance-related problems in a national sample of adolescents

PubMed Central

Wong, Maria M.; Roberson, Gail; Dyson, Rachel

2014-01-01

Background Previous studies showed that poor sleep prospectively predicted alcohol related problems and illicit drug use in adolescents and young adults (Wong et al., 2010, 2012). However, more works needs to be done to elucidate the nature of these problems. The purpose of this study was to examine whether sleep difficulties and hours of sleep prospectively predicted several serious substance related problems, e.g., binge drinking, driving under the influence of alcohol, risky sexual behavior. Methods Study participants were 6504 adolescents from the National Longitudinal Study of Adolescent Health (ADD HEALTH). Data were collected from interviews and questionnaires. The current study analyzed data from the first three waves of data (T1: 1994–95; T2: 1996; T3: 2001–02). In all analyses, we used sleep difficulties at a previous wave to predict substance-related problems at a subsequent wave, while controlling for substance-related problems at a previous wave. Results Holding T1 alcohol-related problems constant, sleep difficulties at T1 significantly predicted alcohol-related interpersonal problems, binge drinking, gotten drunk or very high on alcohol, driving under the influence of alcohol, getting into a sexual situation one later regretted due to drinking, ever using any illicit drugs and drugs-related problems at T2. T1 hours of sleep negatively predicted T2 alcohol-related interpersonal problems and binge drinking. The relationship between T2 sleep variables and T3 substance-related problems were consistent with previous waves, though the effect was weaker. Conclusions Sleep difficulties and hours of sleep are a significant predictor of a number of substance-related problems. It may be useful to educate adolescents about the importance of sleep, sleep hygiene and the potential consequences of poor sleep on drinking and related behaviors. PMID:25598438

Future Orientation, School Contexts, and Problem Behaviors: A Multilevel Study

ERIC Educational Resources Information Center

Chen, Pan; Vazsonyi, Alexander T.

2013-01-01

The association between future orientation and problem behaviors has received extensive empirical attention; however, previous work has not considered school contextual influences on this link. Using a sample of N = 9,163 9th to 12th graders (51.0% females) from N = 85 high schools of the National Longitudinal Study of Adolescent Health, the…

The Experience of Anger and Sadness in Everyday Problems Impacts Age Differences in Emotion Regulation

ERIC Educational Resources Information Center

Blanchard-Fields, Fredda; Coats, Abby Heckman

2008-01-01

The authors examined regulation of the discrete emotions anger and sadness in adolescents through older adults in the context of describing everyday problem situations. The results support previous work; in comparison to younger age groups, older adults reported that they experienced less anger and reported that they used more passive and fewer…

Further Examination of Factors that Influence Preference for Positive versus Negative Reinforcement

ERIC Educational Resources Information Center

Kodak, Tiffany; Lerman, Dorothea C.; Volkert, Valerie M.; Trosclair, Nicole

2007-01-01

Factors that influence choice between qualitatively different reinforcers (e.g., a food item or a break from work) are important to consider when arranging treatments for problem behavior. Previous findings indicate that children who engage in problem behavior maintained by escape from demands may choose a food item over the functional reinforcer…

Varying Use of Conceptual Metaphors across Levels of Expertise in Thermodynamics

ERIC Educational Resources Information Center

Jeppsson, Fredrik; Haglund, Jesper; Amin, Tamer G.

2015-01-01

Many studies have previously focused on how people with different levels of expertise solve physics problems. In early work, focus was on characterising differences between experts and novices and a key finding was the central role that propositionally expressed principles and laws play in expert, but not novice, problem-solving. A more recent…

Student-Posed Problems

NASA Astrophysics Data System (ADS)

Harper, Kathleen A.; Etkina, Eugenia

2002-10-01

As part of weekly reports,1 structured journals in which students answer three standard questions each week, they respond to the prompt, If I were the instructor, what questions would I ask or problems assign to determine if my students understood the material? An initial analysis of the results shows that some student-generated problems indicate fundamental misunderstandings of basic physical concepts. A further investigation explores the relevance of the problems to the week's material, whether the problems are solvable, and the type of problems (conceptual or calculation-based) written. Also, possible links between various characteristics of the problems and conceptual achievement are being explored. The results of this study spark many more questions for further work. A summary of current findings will be presented, along with its relationship to previous work concerning problem posing.2 1Etkina, E. Weekly Reports;A Two-Way Feedback Tool, Science Education, 84, 594-605 (2000). 2Mestre, J.P., Probing Adults Conceptual Understanding and Transfer of Learning Via Problem Posing, Journal of Applied Developmental Psychology, 23, 9-50 (2002).

Evaluating Higher Education's Two-Body Problem

ERIC Educational Resources Information Center

Woolstenhulme, Jared Lynn

2013-01-01

Academic couples make up a significant portion of the academic labor market. Unlike other dual-career households, academic couples must not only find employment in the same region, but often in the same institution. Previous work has not considered how outcomes may be different when dual career households work for the same employer. In the first…

Perceived Communication Skill Needs for Small Work Groups.

ERIC Educational Resources Information Center

Hawkins, Katherine; Fillion, Bryant

A study examined communication skills essential for small work groups and whether the quality of small group teaching and research is in decline. The study reviewed small group research done previously by others and the problem of existing pedagogy and research in small group communication which does not provide practical solutions to real life…

Factors Related to Early Termination from Work for Youth with Disabilities

ERIC Educational Resources Information Center

Pebdani, Roxanna Nasseri

2012-01-01

Youth with disabilities face significant barriers in achieving positive post-high school outcomes, particularly when transitioning out of high school and entering the workforce, a problem that has been documented and studied by many researchers. The impact of previous work experience has long been viewed as related to positive outcomes when youth…

Neuropsychological sequelae of work-stress-related exhaustion.

PubMed

Österberg, Kai; Skogsliden, Sofia; Karlson, Björn

2014-01-01

The aim was to assess long-term cognitive performance after substantial recovery from work-stress-related exhaustion, in relation to subjective cognitive complaints and return to active work. In total, 54 patients previously diagnosed with work-stress-related exhaustion participated in a neuropsychological examination ∼2 years after initial sick leave. Most participants were substantially recovered at follow-up, with only 13% still meeting the criteria for exhaustion disorder suggested by the Swedish National Board of Health and Welfare. When participants' scores on 14 neuropsychological tests were compared to a matched group of 50 controls, the former patient group showed lower performance mainly on attention tests of the reaction time type, but also slightly lower scores on visuo-spatial constructional ability. However, the former patient group performed better than controls on two memory tests and, in part, on a test of simultaneous capacity. Self-ratings of everyday cognitive problems remained significantly higher in the former patient group than among controls, but the extent of self-rated cognitive problems was generally unrelated to performance on the neuropsychological tests. No relationship between performance on these tests and the extent of work resumption was observed. In summary, persons with previous work-stress-related exhaustion showed persistent signs of a minor attention deficit, despite considerable general recovery and return to work.

The Priority Inversion Problem and Real-Time Symbolic Model Checking

DTIC Science & Technology

1993-04-23

real time systems unpredictable in subtle ways. This makes it more difficult to implement and debug such systems. Our work discusses this problem and presents one possible solution. The solution is formalized and verified using temporal logic model checking techniques. In order to perform the verification, the BDD-based symbolic model checking algorithm given in previous works was extended to handle real-time properties using the bounded until operator. We believe that this algorithm, which is based on discrete time, is able to handle many real-time properties

Nonlinear calculations of the time evolution of black hole accretion disks

NASA Technical Reports Server (NTRS)

Luo, C.

1994-01-01

Based on previous works on black hole accretion disks, I continue to explore the disk dynamics using the finite difference method to solve the highly nonlinear problem of time-dependent alpha disk equations. Here a radially zoned model is used to develop a computational scheme in order to accommodate functional dependence of the viscosity parameter alpha on the disk scale height and/or surface density. This work is based on the author's previous work on the steady disk structure and the linear analysis of disk dynamics to try to apply to x-ray emissions from black candidates (i.e., multiple-state spectra, instabilities, QPO's, etc.).

The impact of recurrent throat infection on children and their families.

PubMed

Howel, Denise; Webster, Simon; Hayes, Jane; Barton, Andrew; Donaldson, Liam

2002-06-01

Recurrent throat problems in children are common and have an impact on the family. The appropriateness of surgery will depend on both clinical and social factors. The aim of this study was to assess the impact on the whole family when a child is suffering from recurrent throat problems, and investigate related parental attitudes. A total of 1190 parents of children in northern England for whom tonsillectomy or adeno-tonsillectomy was a possible treatment option were sent a questionnaire covering social and clinical issues such as children's symptoms, the impact on family life and parental attitudes. The majority of children had experienced more than four episodes in the previous year, had their sleep affected and time off school. Most parents were worried and reported disruption to the family, including taking time off work and cross-infection. Parental disruption, worry and eagerness for surgery were significantly associated with the duration of episodes of throat problems and the number of episodes in the previous year, but not with duration of tonsillitis. Time off school, or parental time off work was significantly associated with parental worry and disruption, but not with eagerness for surgery. This work highlights the impact of recurrent throat problems and related parental attitudes, and will aid in striking a balance between clinical requirements and the needs and wishes of the family.

Designing worked examples for learning tangent lines to circles

NASA Astrophysics Data System (ADS)

Retnowati, E.; Marissa

2018-03-01

Geometry is a branch of mathematics that deals with shape and space, including the circle. A difficult topic in the circle may be the tangent line to circle. This is considered a complex material since students have to simultaneously apply several principles to solve the problems, these are the property of circle, definition of the tangent, measurement and Pythagorean theorem. This paper discusses designs of worked examples for learning tangent line to circles and how to apply this design to an effective and efficient instructional activity. When students do not have sufficient prior knowledge, solving tangent problems might be clumsy, and as a consequence, the problem-solving activity hinders learning. According to a Cognitive Load Theory, learning occurs when students can construct new knowledge based on the relevant knowledge previously learned. When the relevant knowledge is unavailable, providing students with the worked example is suggested. Worked example may reduce unproductive process during learning that causes extraneous cognitive load. Nevertheless, worked examples must be created in such a way facilitate learning.

A Constant-Factor Approximation Algorithm for the Link Building Problem

NASA Astrophysics Data System (ADS)

Olsen, Martin; Viglas, Anastasios; Zvedeniouk, Ilia

In this work we consider the problem of maximizing the PageRank of a given target node in a graph by adding k new links. We consider the case that the new links must point to the given target node (backlinks). Previous work [7] shows that this problem has no fully polynomial time approximation schemes unless P = NP. We present a polynomial time algorithm yielding a PageRank value within a constant factor from the optimal. We also consider the naive algorithm where we choose backlinks from nodes with high PageRank values compared to the outdegree and show that the naive algorithm performs much worse on certain graphs compared to the constant factor approximation scheme.

The Relationship between Parental Knowledge and Monitoring and Child and Adolescent Conduct Problems: A 10-Year Update

ERIC Educational Resources Information Center

Racz, Sarah Jensen; McMahon, Robert J.

2011-01-01

Inadequate parental monitoring is widely recognized as a risk factor for the development of child and adolescent conduct problems. However, previous studies examining parental monitoring have largely measured parental knowledge and not the active methods used by parents to track the activities and behavior of their children. The seminal work of…

Moving to Learn: How Guiding the Hands Can Set the Stage for Learning

ERIC Educational Resources Information Center

Brooks, Neon; Goldin-Meadow, Susan

2016-01-01

Previous work has found that guiding problem-solvers' movements can have an immediate effect on their ability to solve a problem. Here we explore these processes in a learning paradigm. We ask whether guiding a learner's movements can have a delayed effect on learning, setting the stage for change that comes about only after instruction. Children…

On the Problem of Theorising: An Insider Account of Research Practice

ERIC Educational Resources Information Center

Clegg, Sue

2012-01-01

This article addresses the problem of how we theorise in writing about higher education through a reconstruction and interrogation of my previous work. I argue that theorising is messy, incomplete and a non-reductive process. Using C. Wright-Mills' notion of craft and Val Hey's insights into theorists who come to haunt us, I retrace the steps…

The Problem of Simplification: Think-Tanks, Recipes, Equity and "Turning around Low-Performing Schools"

ERIC Educational Resources Information Center

Loughland, Tony; Thompson, Greg

2016-01-01

Non-government actors such as think-tanks are playing an important role in Australian policy work. As governments increasingly outsource policy work previously done by education departments and academics to these new policy actors, more think-tanks have emerged that represent a wide range of political views and ideological positions. This paper…

Anxiety Profiles in Children with and without Developmental Coordination Disorder

ERIC Educational Resources Information Center

Pratt, Michelle L.; Hill, Elisabeth L.

2011-01-01

Previous work has highlighted that children diagnosed with DCD may be at risk of greater problems related to emotional wellbeing. However, to date much work has relied on population based samples, and anxiety has not been examined within a group of children given a clinical diagnosis of DCD. Additionally, the profile of individual differences has…

Responses to Different Types of Inquiry Prompts: College Students' Discourse, Performance, and Perceptions of Group Work in an Engineering Class

ERIC Educational Resources Information Center

Balgopal, Meena M.; Casper, Anne Marie A.; Atadero, Rebecca A.; Rambo-Hernandez, Karen E.

2017-01-01

Working in small groups to solve problems is an instructional strategy that allows university students in science, technology, engineering, and mathematics disciplines the opportunity to practice interpersonal and professional skills while gaining and applying discipline-specific content knowledge. Previous research indicates that not all group…

Enhancing memory and imagination improves problem solving among individuals with depression.

PubMed

McFarland, Craig P; Primosch, Mark; Maxson, Chelsey M; Stewart, Brandon T

2017-08-01

Recent work has revealed links between memory, imagination, and problem solving, and suggests that increasing access to detailed memories can lead to improved imagination and problem-solving performance. Depression is often associated with overgeneral memory and imagination, along with problem-solving deficits. In this study, we tested the hypothesis that an interview designed to elicit detailed recollections would enhance imagination and problem solving among both depressed and nondepressed participants. In a within-subjects design, participants completed a control interview or an episodic specificity induction prior to completing memory, imagination, and problem-solving tasks. Results revealed that compared to the control interview, the episodic specificity induction fostered increased detail generation in memory and imagination and more relevant steps on the problem-solving task among depressed and nondepressed participants. This study builds on previous work by demonstrating that a brief interview can enhance problem solving among individuals with depression and supports the notion that episodic memory plays a key role in problem solving. It should be noted, however, that the results of the interview are relatively short-lived.

Trajectories of Maternal Verbal Aggression across the Middle School Years: Associations with Negative View of Self and Social Problems

ERIC Educational Resources Information Center

Donovan, Kera L.; Brassard, Marla R.

2011-01-01

Objective: The primary research objective was to explore the relationship between trajectories of maternal verbal aggression (VA) experienced by low-income, community middle school students across a three-year period and outcomes that have been found to be related to VA in previous work, including a negative view of self and social problems.…

Bio-Inspired Human-Level Machine Learning

DTIC Science & Technology

2015-10-25

extensions to high-level cognitive functions such as anagram solving problem. 15. SUBJECT TERMS 16. SECURITY CLASSIFICATION OF: 17. LIMITATION OF...extensions to high-level cognitive functions such as anagram solving problem. We expect that the bio-inspired human-level machine learning combined with...numbers of 1011 neurons and 1014 synaptic connections in the human brain. In previous work, we experimentally demonstrated the feasibility of cognitive

Cancer rehabilitation with a focus on evidence-based outpatient physical and occupational therapy interventions.

PubMed

Silver, Julie K; Gilchrist, Laura S

2011-05-01

Cancer rehabilitation is an important part of survivorship as a distinct phase of treatment. Although cancer rehabilitation may involve many disciplines, this article specifically covers evidence-based treatment in physical and occupational therapy. Patients may need physical and occupational therapy services for a variety of cancer-related or cancer-treatment-related problems, including pain, fatigue, deconditioning, and difficulty with gait. They may also have problems resuming their previous level of function, which can impact on activities of daily living, instrumental activities of daily living, return to previous home and community activity levels, and return to work. This review discusses the role of physical and occupational therapy in helping cancer patients improve pain and musculoskeletal issues, deconditioning and endurance effects, fatigue, balance and falls, and lymphedema and psychosocial problems.

Measuring Load on Working Memory: The Use of Heart Rate as a Means of Measuring Chemistry Students' Cognitive Load

ERIC Educational Resources Information Center

Cranford, Kristen N.; Tiettmeyer, Jessica M.; Chuprinko, Bryan C.; Jordan, Sophia; Grove, Nathaniel P.

2014-01-01

Information processing provides a powerful model for understanding how learning occurs and highlights the important role that cognitive load plays in this process. In instances in which the cognitive load of a problem exceeds the available working memory, learning can be seriously hindered. Previously reported methods for measuring cognitive load…

Daily spillover from family to work: A test of the work-home resources model.

PubMed

Du, Danyang; Derks, Daantje; Bakker, Arnold B

2018-04-01

The present study examines a mediated moderation model of the day-level effects of family hassles and family-work spillover (affect and cognition) on the relationship between job resources and employees' flourishing at work. Based on the work-home resources model, the authors hypothesized that demands from one domain (family) induce repetitive thoughts or negative feelings about those problems, so that individuals are not able to function optimally and to make full use of contextual resources in the other domain (work). Multilevel analyses of 108 Chinese working parents' 366 daily surveys revealed that the relationship between morning job resources and afternoon flourishing was significantly positive when previous day family hassles were low; the relationship became nonsignificant when previous day family hassles were high. In addition, as predicted, daily rumination also attenuated the relationship between morning job resources and afternoon flourishing, whereas daily affect did not. Finally, the moderating effect of previous day family hassles was mediated by daily rumination. The findings contribute to spillover theories by revealing the roles of affective and cognitive spillover from family to work. (PsycINFO Database Record (c) 2018 APA, all rights reserved).

A review on simple assembly line balancing type-e problem

NASA Astrophysics Data System (ADS)

Jusop, M.; Rashid, M. F. F. Ab

2015-12-01

Simple assembly line balancing (SALB) is an attempt to assign the tasks to the various workstations along the line so that the precedence relations are satisfied and some performance measure are optimised. Advanced approach of algorithm is necessary to solve large-scale problems as SALB is a class of NP-hard. Only a few studies are focusing on simple assembly line balancing of Type-E problem (SALB-E) since it is a general and complex problem. SALB-E problem is one of SALB problem which consider the number of workstation and the cycle time simultaneously for the purpose of maximising the line efficiency. This paper review previous works that has been done in order to optimise SALB -E problem. Besides that, this paper also reviewed the Genetic Algorithm approach that has been used to optimise SALB-E. From the reviewed that has been done, it was found that none of the existing works are concern on the resource constraint in the SALB-E problem especially on machine and tool constraints. The research on SALB-E will contribute to the improvement of productivity in real industrial application.

Gold-standard evaluation of a folksonomy-based ontology learning model

NASA Astrophysics Data System (ADS)

Djuana, E.

2018-03-01

Folksonomy, as one result of collaborative tagging process, has been acknowledged for its potential in improving categorization and searching of web resources. However, folksonomy contains ambiguities such as synonymy and polysemy as well as different abstractions or generality problem. To maximize its potential, some methods for associating tags of folksonomy with semantics and structural relationships have been proposed such as using ontology learning method. This paper evaluates our previous work in ontology learning according to gold-standard evaluation approach in comparison to a notable state-of-the-art work and several baselines. The results show that our method is comparable to the state-of the art work which further validate our approach as has been previously validated using task-based evaluation approach.

Steady-State ALPS for Real-Valued Problems

NASA Technical Reports Server (NTRS)

Hornby, Gregory S.

2009-01-01

The two objectives of this paper are to describe a steady-state version of the Age-Layered Population Structure (ALPS) Evolutionary Algorithm (EA) and to compare it against other GAs on real-valued problems. Motivation for this work comes from our previous success in demonstrating that a generational version of ALPS greatly improves search performance on a Genetic Programming problem. In making steady-state ALPS some modifications were made to the method for calculating age and the method for moving individuals up layers. To demonstrate that ALPS works well on real-valued problems we compare it against CMA-ES and Differential Evolution (DE) on five challenging, real-valued functions and on one real-world problem. While CMA-ES and DE outperform ALPS on the two unimodal test functions, ALPS is much better on the three multimodal test problems and on the real-world problem. Further examination shows that, unlike the other GAs, ALPS maintains a genotypically diverse population throughout the entire search process. These findings strongly suggest that the ALPS paradigm is better able to avoid premature convergence then the other GAs.

Working conditions and health among employees at information technology--enabled services: a review of current evidence.

PubMed

Kesavachandran, C; Rastogi, S K; Das, Mohan; Khan, Asif M

2006-07-01

Workers in information technology (IT)-enabled services like business process outsourcing and call centers working with visual display units are reported to have various health and psycho-social disorders. Evidence from previously published studies in peer- reviewed journals and internet sources were examined to explore health disorders and psycho-social problems among personnel employed in IT-based services, for a systematic review on the topic. In addition, authors executed a questionnaire- based pilot study. The available literature and the pilot study, both suggest health disorders and psychosocial problems among workers of business process outsourcing. The details are discussed in the review.

The application of contraction theory to an iterative formulation of electromagnetic scattering

NASA Technical Reports Server (NTRS)

Brand, J. C.; Kauffman, J. F.

1985-01-01

Contraction theory is applied to an iterative formulation of electromagnetic scattering from periodic structures and a computational method for insuring convergence is developed. A short history of spectral (or k-space) formulation is presented with an emphasis on application to periodic surfaces. To insure a convergent solution of the iterative equation, a process called the contraction corrector method is developed. Convergence properties of previously presented iterative solutions to one-dimensional problems are examined utilizing contraction theory and the general conditions for achieving a convergent solution are explored. The contraction corrector method is then applied to several scattering problems including an infinite grating of thin wires with the solution data compared to previous works.

Towards overcoming the Monte Carlo sign problem with tensor networks

NASA Astrophysics Data System (ADS)

Bañuls, Mari Carmen; Cichy, Krzysztof; Ignacio Cirac, J.; Jansen, Karl; Kühn, Stefan; Saito, Hana

2017-03-01

The study of lattice gauge theories with Monte Carlo simulations is hindered by the infamous sign problem that appears under certain circumstances, in particular at non-zero chemical potential. So far, there is no universal method to overcome this problem. However, recent years brought a new class of non-perturbative Hamiltonian techniques named tensor networks, where the sign problem is absent. In previous work, we have demonstrated that this approach, in particular matrix product states in 1+1 dimensions, can be used to perform precise calculations in a lattice gauge theory, the massless and massive Schwinger model. We have computed the mass spectrum of this theory, its thermal properties and real-time dynamics. In this work, we review these results and we extend our calculations to the case of two flavours and non-zero chemical potential. We are able to reliably reproduce known analytical results for this model, thus demonstrating that tensor networks can tackle the sign problem of a lattice gauge theory at finite density.

Dynamic bin packing problem

NASA Technical Reports Server (NTRS)

Dikshit, Piyush; Guimaraes, Katia; Ramamurthy, Maya; Agrawala, Ashok K.; Larsen, Ronald L.

1989-01-01

In a previous work we have defined a general architecture model for autonomous systems, which can be mapped easily to describe the functions of any automated system (SDAG-86-01). In this note, we use the model to describe the problem of thermal management in space stations. First we briefly review the architecture, then we present the environment of our application, and finally we detail the specific function for each functional block of the architecture for that environment.

A random utility model of delay discounting and its application to people with externalizing psychopathology.

PubMed

Dai, Junyi; Gunn, Rachel L; Gerst, Kyle R; Busemeyer, Jerome R; Finn, Peter R

2016-10-01

Previous studies have demonstrated that working memory capacity plays a central role in delay discounting in people with externalizing psychopathology. These studies used a hyperbolic discounting model, and its single parameter-a measure of delay discounting-was estimated using the standard method of searching for indifference points between intertemporal options. However, there are several problems with this approach. First, the deterministic perspective on delay discounting underlying the indifference point method might be inappropriate. Second, the estimation procedure using the R2 measure often leads to poor model fit. Third, when parameters are estimated using indifference points only, much of the information collected in a delay discounting decision task is wasted. To overcome these problems, this article proposes a random utility model of delay discounting. The proposed model has 2 parameters, 1 for delay discounting and 1 for choice variability. It was fit to choice data obtained from a recently published data set using both maximum-likelihood and Bayesian parameter estimation. As in previous studies, the delay discounting parameter was significantly associated with both externalizing problems and working memory capacity. Furthermore, choice variability was also found to be significantly associated with both variables. This finding suggests that randomness in decisions may be a mechanism by which externalizing problems and low working memory capacity are associated with poor decision making. The random utility model thus has the advantage of disclosing the role of choice variability, which had been masked by the traditional deterministic model. (PsycINFO Database Record (c) 2016 APA, all rights reserved).

Random Matrix Approach for Primal-Dual Portfolio Optimization Problems

NASA Astrophysics Data System (ADS)

Tada, Daichi; Yamamoto, Hisashi; Shinzato, Takashi

2017-12-01

In this paper, we revisit the portfolio optimization problems of the minimization/maximization of investment risk under constraints of budget and investment concentration (primal problem) and the maximization/minimization of investment concentration under constraints of budget and investment risk (dual problem) for the case that the variances of the return rates of the assets are identical. We analyze both optimization problems by the Lagrange multiplier method and the random matrix approach. Thereafter, we compare the results obtained from our proposed approach with the results obtained in previous work. Moreover, we use numerical experiments to validate the results obtained from the replica approach and the random matrix approach as methods for analyzing both the primal and dual portfolio optimization problems.

A Riemann-Hilbert approach to the inverse problem for the Stark operator on the line

NASA Astrophysics Data System (ADS)

Its, A.; Sukhanov, V.

2016-05-01

The paper is concerned with the inverse scattering problem for the Stark operator on the line with a potential from the Schwartz class. In our study of the inverse problem, we use the Riemann-Hilbert formalism. This allows us to overcome the principal technical difficulties which arise in the more traditional approaches based on the Gel’fand-Levitan-Marchenko equations, and indeed solve the problem. We also produce a complete description of the relevant scattering data (which have not been obtained in the previous works on the Stark operator) and establish the bijection between the Schwartz class potentials and the scattering data.

A SAT Based Effective Algorithm for the Directed Hamiltonian Cycle Problem

NASA Astrophysics Data System (ADS)

Jäger, Gerold; Zhang, Weixiong

The Hamiltonian cycle problem (HCP) is an important combinatorial problem with applications in many areas. While thorough theoretical and experimental analyses have been made on the HCP in undirected graphs, little is known for the HCP in directed graphs (DHCP). The contribution of this work is an effective algorithm for the DHCP. Our algorithm explores and exploits the close relationship between the DHCP and the Assignment Problem (AP) and utilizes a technique based on Boolean satisfiability (SAT). By combining effective algorithms for the AP and SAT, our algorithm significantly outperforms previous exact DHCP algorithms including an algorithm based on the award-winning Concorde TSP algorithm.

Introduction to Sustainable Urban Engineering - National Perspective - Measuring the Magnitude of the Problem

EPA Science Inventory

This seminar will present previous work on the Tool for the Reduction and Assessment and of Chemical and other environmental Impacts (TRACI) along with interim research on the quantification of land use modifications for comprehensive impact assessment. Various research options ...

Teaching Calculus Students How to Study.

ERIC Educational Resources Information Center

Boelkins, Matthew R.; Pfaff, Thomas J.

1998-01-01

Addresses the problem of poor study habits in calculus students and presents techniques to teach students how to study consistently and effectively. Concludes that many students greatly appreciate the added structure, work harder than in previous courses, and witness newfound success as a consequence. (Author/ASK)

Gaze data reveal distinct choice processes underlying model-based and model-free reinforcement learning

PubMed Central

Konovalov, Arkady; Krajbich, Ian

2016-01-01

Organisms appear to learn and make decisions using different strategies known as model-free and model-based learning; the former is mere reinforcement of previously rewarded actions and the latter is a forward-looking strategy that involves evaluation of action-state transition probabilities. Prior work has used neural data to argue that both model-based and model-free learners implement a value comparison process at trial onset, but model-based learners assign more weight to forward-looking computations. Here using eye-tracking, we report evidence for a different interpretation of prior results: model-based subjects make their choices prior to trial onset. In contrast, model-free subjects tend to ignore model-based aspects of the task and instead seem to treat the decision problem as a simple comparison process between two differentially valued items, consistent with previous work on sequential-sampling models of decision making. These findings illustrate a problem with assuming that experimental subjects make their decisions at the same prescribed time. PMID:27511383

Stress and prevalence of hearing problems in the Swedish working population

PubMed Central

2011-01-01

Background Current human and experimental studies are indicating an association between stress and hearing problems; however potential risk factors have not been established. Hearing problems are projected to become among the top ten disabilities according to the WHO in the near future. Therefore a better understanding of the relationships between stress and hearing is warranted. Here we describe the prevalence of two common hearing problems, i.e. hearing complaints and tinnitus, in relation to different work-and health-related stressors. Methods A total of 18,734 individuals were invited to participate in the study, out of which 9,756 (52%) enrolled. Results The results demonstrate a clear and mostly linear relationship between higher prevalence of hearing problems (tinnitus or hearing loss or both) and different stressors, e.g. occupational, poorer self-rated health, long-term illness, poorer sleep quality, and higher burnout scores. Conclusions The present study unambiguously demonstrates associations between hearing problems and various stressors that have not been previously described for the auditory system. These findings will open new avenues for future investigations. PMID:21345187

Mental health problems among young doctors: an updated review of prospective studies.

PubMed

Tyssen, Reidar; Vaglum, Per

2002-01-01

Previous studies have shown the medical community to exhibit a relatively high level of certain mental health problems, particularly depression, which may lead to drug abuse and suicide. We reviewed prospective studies published over the past 20 years to investigate the prevalence and predictors of mental health problems in doctors during their first postgraduate years. We selected clinically relevant mental health problems as the outcome measure. We found nine cohort studies that met our selection criteria. Each of them had limitations, notably low response rate at follow-up, small sample size, and/or short observation period. Most studies showed that symptoms of mental health problems, particularly of depression, were highest during the first postgraduate year. They found that individual factors, such as family background, personality traits (neuroticism and self-criticism), and coping by wishful thinking, as well as contextual factors including perceived medical-school stress, perceived overwork, emotional pressure, working in an intensive-care setting, and stress outside of work, were often predictive of mental health problems. The studies revealed somewhat discrepant findings with respect to gender. The implications of these findings are discussed.

A quantum annealing approach for fault detection and diagnosis of graph-based systems

NASA Astrophysics Data System (ADS)

Perdomo-Ortiz, A.; Fluegemann, J.; Narasimhan, S.; Biswas, R.; Smelyanskiy, V. N.

2015-02-01

Diagnosing the minimal set of faults capable of explaining a set of given observations, e.g., from sensor readouts, is a hard combinatorial optimization problem usually tackled with artificial intelligence techniques. We present the mapping of this combinatorial problem to quadratic unconstrained binary optimization (QUBO), and the experimental results of instances embedded onto a quantum annealing device with 509 quantum bits. Besides being the first time a quantum approach has been proposed for problems in the advanced diagnostics community, to the best of our knowledge this work is also the first research utilizing the route Problem → QUBO → Direct embedding into quantum hardware, where we are able to implement and tackle problem instances with sizes that go beyond previously reported toy-model proof-of-principle quantum annealing implementations; this is a significant leap in the solution of problems via direct-embedding adiabatic quantum optimization. We discuss some of the programmability challenges in the current generation of the quantum device as well as a few possible ways to extend this work to more complex arbitrary network graphs.

Work-related musculoskeletal disorders in Australian dentists and orthodontists: Risk assessment and prevention.

PubMed

Sakzewski, Lisa; Naser-ud-Din, Shazia

2015-01-01

As professionals work longer hours and live longer there have been concerns regarding the Work related Musculoskeletal Disorders (WMSD) affecting both professional and personal lives. Moreover, past decade has seen a surge in interest in all allied health sciences personnel with self reporting cross sectional studies. Health professionals often suffer WMSD due to occupational stress. It is important to assess the problem in order to find ways to prevent it. Hence, the focus of this cross-sectional survey. The aim was to investigate the prevalence and risk factors of WMSD between Australian dentists and orthodontists. A postal survey was sent to 447 Australian orthodontists and 450 Queensland dentists using the universal Nordic scale previously piloted at UQ and refined for this cross-sectional study. Questions were directed towards individuals, workplace and psychosocial variables and were designed to gather information regarding health, lifestyle, education, awareness of musculoskeletal problems and current preventative strategies. A high prevalence of musculoskeletal problems was found for both dentists (88.9%) and orthodontists (83.6%) reported in the last 12 months. The main predictor in both groups was increased work stress. Less than a third of those professionals surveyed had received education regarding dental practice ergonomics during their tertiary education. Dentists and orthodontists experienced a high rate of musculoskeletal problems which were associated with increased levels of stress at work. Further research should be directed toward interventions aimed at reducing stress in the work environment as well as improving work posture.

Group relationships in early and late sessions and improvement in interpersonal problems.

PubMed

Lo Coco, Gianluca; Gullo, Salvatore; Di Fratello, Carla; Giordano, Cecilia; Kivlighan, Dennis M

2016-07-01

Groups are more effective when positive bonds are established and interpersonal conflicts resolved in early sessions and work is accomplished in later sessions. Previous research has provided mixed support for this group development model. We performed a test of this theoretical perspective using group members' (actors) and aggregated group members' (partners) perceptions of positive bonding, positive working, and negative group relationships measured early and late in interpersonal growth groups. Participants were 325 Italian graduate students randomly (within semester) assigned to 1 of 16 interpersonal growth groups. Groups met for 9 weeks with experienced psychologists using Yalom and Leszcz's (2005) interpersonal process model. Outcome was assessed pre- and posttreatment using the Inventory of Interpersonal Problems, and group relationships were measured at Sessions 3 and 6 using the Group Questionnaire. As hypothesized, early measures of positive bonding and late measures of positive working, for both actors and partners, were positively related to improved interpersonal problems. Also as hypothesized, late measures of positive bonding and early measures of positive working, for both actors and partners, were negatively related to improved interpersonal problems. We also found that early actor and partner positive bonding and negative relationships interacted to predict changes in interpersonal problems. The findings are consistent with group development theory and suggest that group therapists focus on group-as-a-whole positive bonding relationships in early group sessions and on group-as-a-whole positive working relationships in later group sessions. (PsycINFO Database Record (c) 2016 APA, all rights reserved).

Results and conclusions: perception sensor study for high speed autonomous operations

NASA Astrophysics Data System (ADS)

Schneider, Anne; LaCelle, Zachary; Lacaze, Alberto; Murphy, Karl; Close, Ryan

2016-05-01

Previous research has presented work on sensor requirements, specifications, and testing, to evaluate the feasibility of increasing autonomous vehicle system speeds. Discussions included the theoretical background for determining sensor requirements, and the basic test setup and evaluation criteria for comparing existing and prototype sensor designs. This paper will present and discuss the continuation of this work. In particular, this paper will focus on analyzing the problem via a real-world comparison of various sensor technology testing results, as opposed to previous work that utilized more of a theoretical approach. LADAR/LIDAR, radar, visual, and infrared sensors are considered in this research. Results are evaluated against the theoretical, desired perception specifications. Conclusions for utilizing a suite of perception sensors, to achieve the goal of doubling ground vehicle speeds, is also discussed.

Full self-consistency in the Fermi-orbital self-interaction correction

NASA Astrophysics Data System (ADS)

Yang, Zeng-hui; Pederson, Mark R.; Perdew, John P.

2017-05-01

The Perdew-Zunger self-interaction correction cures many common problems associated with semilocal density functionals, but suffers from a size-extensivity problem when Kohn-Sham orbitals are used in the correction. Fermi-Löwdin-orbital self-interaction correction (FLOSIC) solves the size-extensivity problem, allowing its use in periodic systems and resulting in better accuracy in finite systems. Although the previously published FLOSIC algorithm Pederson et al., J. Chem. Phys. 140, 121103 (2014)., 10.1063/1.4869581 appears to work well in many cases, it is not fully self-consistent. This would be particularly problematic for systems where the occupied manifold is strongly changed by the correction. In this paper, we demonstrate a different algorithm for FLOSIC to achieve full self-consistency with only marginal increase of computational cost. The resulting total energies are found to be lower than previously reported non-self-consistent results.

Planning Under Continuous Time and Resource Uncertainty: A Challenge for AI

NASA Technical Reports Server (NTRS)

Bresina, John; Dearden, Richard; Meuleau, Nicolas; Smith, David; Washington, Rich; Clancy, Daniel (Technical Monitor)

2002-01-01

There has been considerable work in Al on decision-theoretic planning and planning under uncertainty. Unfortunately, all of this work suffers from one or more of the following limitations: 1) it relies on very simple models of actions and time, 2) it assumes that uncertainty is manifested in discrete action outcomes, and 3) it is only practical for very small problems. For many real world problems, these assumptions fail to hold. A case in point is planning the activities for a Mars rover. For this domain none of the above assumptions are valid: 1) actions can be concurrent and have differing durations, 2) there is uncertainty concerning action durations and consumption of continuous resources like power, and 3) typical daily plans involve on the order of a hundred actions. We describe the rover problem, discuss previous work on planning under uncertainty, and present a detailed. but very small, example illustrating some of the difficulties of finding good plans.

The influence of achievement goals on the constructive activity of low achievers during collaborative problem solving.

PubMed

Gabriele, Anthony J

2007-03-01

Previous research on small-group learning has found that level of constructive activity (solving or explaining how to solve problems using ideas stated or implied in the explanation provided by a partner) was a better predictor of post-test achievement than either a student's prior achievement or the quality of help received (Webb, Troper, & Fall, 1995). The purpose of this study was to extend this research by examining the influence of additional factors, in particular, achievement goals and comprehension monitoring, on low achieving students' constructive activity after receiving help from a high achieving peer. Thirty-two low achieving upper elementary students from an urban school district in the mid-west of the United States were paired with high achieving partners. Videotape data from a previously reported study on peer collaboration were transcribed and reanalyzed. In that study, dyads were randomly assigned instructions designed to induce either a learning or performance goal and were videotaped as they worked together to solve a set of mathematical word problems. The following day, students were individually post-tested on problems similar to the ones worked on in pairs. Consistent with previous research, low achieving students' level of constructive activity predicted post-test performance. In addition, constructive activity was found to mediate the relationship between achievement goals and learning. However, achievement goals were not related to low achievers constructive use of help. Instead, achievement goals were related to low achievers' relative accuracy in comprehension monitoring, which in turn was related to level of constructive activity. The meaning of these results for understanding the processes by which low achievers learn from peer help and implications for classroom practice are discussed.

Symmetries in vakonomic dynamics: applications to optimal control

NASA Astrophysics Data System (ADS)

Martínez, Sonia; Cortés, Jorge; de León, Manuel

2001-06-01

Symmetries in vakonomic dynamics are discussed. Appropriate notions are introduced and their relationship with previous work on symmetries of singular Lagrangian systems is shown. Some Noether-type theorems are obtained. The results are applied to a class of general optimal control problems and to kinematic locomotion systems.

Using barley genomics to develop Fusarium head blight resistant wheat and barley

USDA-ARS?s Scientific Manuscript database

Fusarium head blight, caused by Fusarium graminearum, is a major problem for wheat and barley growers. During infection, F. graminearum produces trichothecene mycotoxins (e.g., deoxynivalenol or DON) that increases fungal virulence and reduces grain quality and yield. Previous work in Arabidopsis sh...

[The use of volunteers to support family carers of dementia patients: results of a prospective longitudinal study investigating expectations towards and experience with training and professional support].

PubMed

Grässel, E; Schirmer, B

2006-06-01

Caring for a dementia patient in the family often turns out to be a full-time job for family carers. So home visitors-for example volunteers spending time with the patient and thus offering some respite to the family-may be a very important aspect of stabilizing home care. This study investigates the expectations of volunteers concerning their training and their future voluntary work, as well as their visiting experiences, and their reasons for stopping the voluntary work. A total of 40 volunteers were interviewed three times over a 18 month period. The interviews were based on interview guidelines and were problem-centered. The interviewees' replies were subject to a summarizing qualitative content analysis. Of the study participants 85% were women, 48% had previously been family carers themselves, and 50% had previous experience of other voluntary work. Their wish "to do something useful" and "to learn more about dementia" were the main reasons for participation in voluntary work. The interviewed persons tend to learn most about communicating with dementia patients through case studies and practical exercises. Work pressures or restarting employment were the most common reasons to stop the voluntary work. Only if the volunteers are supported by professionals--particularly in the form of a contact person who is always available when problems occur--can this type of respite for family carers be maintained.

International Space Station (ISS) Environmental Control and Life Support (ECLS) System Overview of Events: February 2002 - 2004

NASA Technical Reports Server (NTRS)

Gentry, Gregory J.; Reysa, Richard P.; Williams, Dave E.

2004-01-01

The International Space Station continues to build up its life support equipment capability. Several ECLS equipment failures have occurred since Lab activation in February 2001. Major problems occurring between February 2001 and February 2002 were discussed in other works. Major problems occurring between February 2002 and February 2003 are discussed in this paper, as are updates from previously ongoing unresolved problems. This paper addresses failures, and root cause, with particular emphasis on likely micro-gravity causes. Impact to overall station operations and proposed and accomplished fixes will also be discussed.

The discovery of the causes of leprosy: A computational analysis

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

Corruble, V.; Ganascia, J.G.

1996-12-31

The role played by the inductive inference has been studied extensively in the field of Scientific Discovery. The work presented here tackles the problem of induction in medical research. The discovery of the causes of leprosy is analyzed and simulated using computational means. An inductive algorithm is proposed, which is successful in simulating some essential steps in the progress of the understanding of the disease. It also allows us to simulate the false reasoning of previous centuries through the introduction of some medical a priori inherited form archaic medicine. Corroborating previous research, this problem illustrates the importance of the socialmore » and cultural environment on the way the inductive inference is performed in medicine.« less

Implementation of Real-Time Feedback Flow Control Algorithms on a Canonical Testbed

NASA Technical Reports Server (NTRS)

Tian, Ye; Song, Qi; Cattafesta, Louis

2005-01-01

This report summarizes the activities on "Implementation of Real-Time Feedback Flow Control Algorithms on a Canonical Testbed." The work summarized consists primarily of two parts. The first part summarizes our previous work and the extensions to adaptive ID and control algorithms. The second part concentrates on the validation of adaptive algorithms by applying them to a vibration beam test bed. Extensions to flow control problems are discussed.

Health problems lead to considerable productivity loss at work among workers with high physical load jobs.

PubMed

Meerding, W J; IJzelenberg, W; Koopmanschap, M A; Severens, J L; Burdorf, A

2005-05-01

To assess the feasibility and validity of two instruments for the measurement of health-related productivity loss at work. A cross-sectional study was conducted in two occupational populations with a high prevalence of health problems: industrial workers (n=388) and construction workers (n=182). We collected information on self-reported productivity during the previous 2 weeks and during the last work day with the Health and Labor Questionnaire (HLQ) and the Quantity and Quality instrument (QQ), with added data on job characteristics, general health, presence of musculoskeletal complaints, sick leave, and health-care consumption. For construction workers, we validated self-reported productivity with objective information on daily work output from 19 work site observations. About half the workers with health problems on the last working day reported reduced work productivity (QQ), or 10.7% of all industrial workers and 11.8% of all construction workers, resulting in a mean loss of 2.0 hr/day per worker with reduced work productivity. The proportion of workers with reduced productivity was significantly lower on the HLQ: 5.3% of industrial workers and 6.5% of construction workers. Reduced work productivity on the HLQ and the QQ was significantly associated with musculoskeletal complaints, worse physical, mental and general health, and recent absenteeism. The QQ and HLQ questionnaires demonstrated poor agreement on the reporting of reduced productivity. Self-reported productivity on the QQ correlated significantly with objective work output (r=.48). Health problems may lead to considerable sickness presenteeism. The QQ measurement instrument is better understandable, and more feasible for jobs with low opportunities for catching up on backlogs.

Measuring Student Performance in General Organic Chemistry

ERIC Educational Resources Information Center

Austin, Ara C.; Ben-Daat, Hagit; Zhu, Mary; Atkinson, Robert; Barrows, Nathan; Gould, Ian R.

2015-01-01

Student performance in general organic chemistry courses is determined by a wide range of factors including cognitive ability, motivation and cultural capital. Previous work on cognitive factors has tended to focus on specific areas rather than exploring performance across all problem types and cognitive skills. In this study, we have categorized…

Social Class and Mass Environmental Beliefs: A Reconsideration.

ERIC Educational Resources Information Center

Buttel, Frederick H.; Flinn, William L.

The previous literature on the socioeconomic correlates of environmental concern places great stress on the middle class being more supportive of environmental agendas than the working or lower socioeconomic class. The authors believe that methodological problems in this research and the theoretical implications of the middle class generalization…

Thermodynamics and Human Population

ERIC Educational Resources Information Center

Cordry, Sean M.

2010-01-01

This paper discusses a Fermi-problem exercise through which I take students in several of my college courses. Students work in teams, determining the average daily Caloric needs per person. Then they use insolation values to determine the size of a collection area needed to absorb the previously determined daily energy requirements. Adjustments to…

The entrepreneurial revolution in health care delivery.

PubMed

Silver, A D

1987-06-01

The rapid changes in the health marketplace have opened the door for entrepreneurs. The author shows how entrepreneurs seek previously unthought of solutions to problems and through a team effort increase corporate value. According to the author, there is a specific profile of the successful entrepreneur. The qualities of the entrepreneur and the managers that work with them, therefore, are discussed in detail. Finally, several examples of problems in health care that present entrepreneurial opportunities are presented. The author includes scenarios for taking advantage of these opportunities.

Transition between free-space Helmholtz equation solutions with plane sources and parabolic wave equation solutions.

PubMed

Mahillo-Isla, R; Gonźalez-Morales, M J; Dehesa-Martínez, C

2011-06-01

The slowly varying envelope approximation is applied to the radiation problems of the Helmholtz equation with a planar single-layer and dipolar sources. The analyses of such problems provide procedures to recover solutions of the Helmholtz equation based on the evaluation of solutions of the parabolic wave equation at a given plane. Furthermore, the conditions that must be fulfilled to apply each procedure are also discussed. The relations to previous work are given as well.

On the Uniqueness Conditions and Bifurcation Criteria in Coupled Thermo-Elasto-Plasticity

NASA Astrophysics Data System (ADS)

Śloderbach, Z.

2017-02-01

The global and local conditions of uniqueness and the criteria excluding a possibility of bifurcation of the equilibrium state for small strains are derived. The conditions and criteria are derived analyzing the problem of uniqueness of solution of the basic incremental boundary problem of coupled generalized thermo-elasto-plasticity. This paper is a continuation of some previous works by the author, but contains new derivation of the global and local criteria excluding a possibility of bifurcation of the equilibrium state for a comparison body dependent on statically admissible fields of stress velocity. All the thermal elastoplastic coupling effects, non-associated laws of plastic flow and influence of plastic strains on thermoplastic properties of a body were taken into account in this work. Thus, the mathematical problem considered here is not a self-conjugated problem. The paper contains four Appendices A, B, C and D where the local necessery and sufficient conditions of uniqueness have been derived.

Closed set of the uniqueness conditions and bifurcation criteria in generalized coupled thermoplasticity for small deformations

NASA Astrophysics Data System (ADS)

Śloderbach, Zdzisław

2016-05-01

This paper reports the results of a study into global and local conditions of uniqueness and the criteria excluding the possibility of bifurcation of the equilibrium state for small strains. The conditions and criteria are derived on the basis of an analysis of the problem of uniqueness of a solution involving the basic incremental boundary problem of coupled generalized thermo-elasto-plasticity. This work forms a follow-up of previous research (Śloderbach in Bifurcations criteria for equilibrium states in generalized thermoplasticity, IFTR Reports, 1980, Arch Mech 3(35):337-349, 351-367, 1983), but contains a new derivation of global and local criteria excluding a possibility of bifurcation of an equilibrium state regarding a comparison body dependent on the admissible fields of stress rate. The thermal elasto-plastic coupling effects, non-associated laws of plastic flow and influence of plastic strains on thermoplastic properties of a body were taken into account in this work. Thus, the mathematical problem considered here is not a self-conjugated problem.

A Moving Mesh Finite Element Algorithm for Singular Problems in Two and Three Space Dimensions

NASA Astrophysics Data System (ADS)

Li, Ruo; Tang, Tao; Zhang, Pingwen

2002-04-01

A framework for adaptive meshes based on the Hamilton-Schoen-Yau theory was proposed by Dvinsky. In a recent work (2001, J. Comput. Phys.170, 562-588), we extended Dvinsky's method to provide an efficient moving mesh algorithm which compared favorably with the previously proposed schemes in terms of simplicity and reliability. In this work, we will further extend the moving mesh methods based on harmonic maps to deal with mesh adaptation in three space dimensions. In obtaining the variational mesh, we will solve an optimization problem with some appropriate constraints, which is in contrast to the traditional method of solving the Euler-Lagrange equation directly. The key idea of this approach is to update the interior and boundary grids simultaneously, rather than considering them separately. Application of the proposed moving mesh scheme is illustrated with some two- and three-dimensional problems with large solution gradients. The numerical experiments show that our methods can accurately resolve detail features of singular problems in 3D.

The aggregated unfitted finite element method for elliptic problems

NASA Astrophysics Data System (ADS)

Badia, Santiago; Verdugo, Francesc; Martín, Alberto F.

2018-07-01

Unfitted finite element techniques are valuable tools in different applications where the generation of body-fitted meshes is difficult. However, these techniques are prone to severe ill conditioning problems that obstruct the efficient use of iterative Krylov methods and, in consequence, hinders the practical usage of unfitted methods for realistic large scale applications. In this work, we present a technique that addresses such conditioning problems by constructing enhanced finite element spaces based on a cell aggregation technique. The presented method, called aggregated unfitted finite element method, is easy to implement, and can be used, in contrast to previous works, in Galerkin approximations of coercive problems with conforming Lagrangian finite element spaces. The mathematical analysis of the new method states that the condition number of the resulting linear system matrix scales as in standard finite elements for body-fitted meshes, without being affected by small cut cells, and that the method leads to the optimal finite element convergence order. These theoretical results are confirmed with 2D and 3D numerical experiments.

A study on the ergonomic assessment in the workplace

NASA Astrophysics Data System (ADS)

Tee, Kian Sek; Low, Eugene; Saim, Hashim; Zakaria, Wan Nurshazwani Wan; Khialdin, Safinaz Binti Mohd; Isa, Hazlita; Awad, M. I.; Soon, Chin Fhong

2017-09-01

Ergonomics has gained attention and take into consideration by the workers in the different fields of works recently. It has given a huge impact on the workers comfort which directly affects the work efficiency and productivity. The workers have claimed to suffer from the painful postures and injuries in their workplace. Musculoskeletal disorders (MSDs) is the most common problem frequently reported by the workers. This problem occurs due to the lack of knowledge and alertness from the workers to the ergonomic in their surroundings. This paper intends to review the approaches and instruments used by the previous works of the researchers in the evaluation of the ergonomics. The two main assessment methods often used for ergonomic evaluation are Rapid Upper Limb Assessment (RULA) and Rapid Entire Body Assessment (REBA). Popular devices are Inertial Measurement Units (IMU) and Microsoft Kinect.

Discriminatively learning for representing local image features with quadruplet model

NASA Astrophysics Data System (ADS)

Zhang, Da-long; Zhao, Lei; Xu, Duan-qing; Lu, Dong-ming

2017-11-01

Traditional hand-crafted features for representing local image patches are evolving into current data-driven and learning-based image feature, but learning a robust and discriminative descriptor which is capable of controlling various patch-level computer vision tasks is still an open problem. In this work, we propose a novel deep convolutional neural network (CNN) to learn local feature descriptors. We utilize the quadruplets with positive and negative training samples, together with a constraint to restrict the intra-class variance, to learn good discriminative CNN representations. Compared with previous works, our model reduces the overlap in feature space between corresponding and non-corresponding patch pairs, and mitigates margin varying problem caused by commonly used triplet loss. We demonstrate that our method achieves better embedding result than some latest works, like PN-Net and TN-TG, on benchmark dataset.

The Role of Personal and Job Resources in the Relationship between Psychosocial Job Demands, Mental Strain, and Health Problems

PubMed Central

Mayerl, Hannes; Stolz, Erwin; Waxenegger, Anja; Rásky, Éva; Freidl, Wolfgang

2016-01-01

Recent research highlights the importance of both job resources and personal resources in the job demands-resources model. However, the results of previous studies on how these resources are related to each other and how they operate in relation to the health-impairment process of the job demands-resources model are ambiguous. Thus, the authors tested an alternative model, considering job and personal resources to be domains of the same underlying factor and linking this factor to the health-impairment process. Survey data of two Austrian occupational samples (N1 = 8657 and N2 = 9536) were analyzed using confirmatory factor analysis (CFA) and structural equation modeling (SEM). The results revealed that job and personal resources can be considered as indicators of a single resources factor which was negatively related to psychosocial job demands, mental strain, and health problems. Confirming previous studies, we further found that mental strain mediated the relationship between psychosocial job demands and health problems. Our findings suggest that interventions aimed at maintaining health in the context of work may take action on three levels: (1) the prevention of extensive job demands, (2) the reduction of work-related mental strain, and (3) the strengthening of resources. PMID:27582717

Working conditions in call-centers, the impact on employee health: a transversal study. Part II.

PubMed

Charbotel, Barbara; Croidieu, Sophie; Vohito, Michel; Guerin, Anne-Céline; Renaud, Liliane; Jaussaud, Joelle; Bourboul, Christian; Imbard, Isabelle; Ardiet, Dominique; Bergeret, Alain

2009-05-01

The present study sought to assess the impact of telephone call center employees' working conditions on health by identifying at-risk employment situations. A transversal study was performed in companies followed by 47 occupational physicians taking part (working conditions have been previously described). A self-administered medical questionnaire was used to collect data on absence due to sick leave, hearing and visual problems, musculoskeletal disorders, psychotropic drug use, etc. An analog-scale self-assessment of health status and a general health questionnaire (GHQ-12) were used. Personal or familial events that might underlie health problems and affect GHQ-12 results were quantified and taken into account in a logistic regression. A total of 2,130 call-handlers were included. Workers who had availed sick leave during the previous 12 months were 60%. The most frequent musculoskeletal complaints over the previous 12-month period concerned the cervical region (59%). During the same period, 77.3% of subjects experienced visual fatigue, 50% reported auditory fatigue signs and 47% vocal disturbance or fatigue. According to the Likert scale, 39.4% of workers had showed psychological distress. Almost 24% of the workers had used psychoactive medication during the previous 12 months. A significant association was found between psychological distress and the frequency of musculoskeletal disorders. Psychological distress and musculoskeletal disorders were significantly greater in workers with Job Strain and Iso Strain. After taking non-occupational factors into account, some occupational factors were found to increase the risk of psychological distress (Likert >12): imposed full-time schedule, being unable to simultaneously meet both quality and quantity requirements, situations of tension with clients, negative comments from superiors, and lack of recognition from superiors. This survey of over 2,000 call center employees highlighted the high frequency of psychological distress in this population and the health impact of working conditions.

Coping with jealousy: the association between maladaptive aspects of jealousy and drinking problems is mediated by drinking to cope.

PubMed

Dibello, Angelo M; Neighbors, Clayton; Rodriguez, Lindsey M; Lindgren, Kristen

2014-01-01

Previous research has shown that both alcohol use and jealousy are related to negative relationship outcomes. Little work, however, has examined direct associations between alcohol use and jealousy. The current study was aimed to build upon existing research examining alcohol use and jealousy. More specifically, findings from current jealousy literature indicate that jealousy is a multifaceted construct with both maladaptive and adaptive aspects. The current study examined the association between maladaptive and adaptive feelings of jealousy and alcohol-related problems in the context of drinking to cope. Given the relationship between coping motives and alcohol-related problems, our primary interest was in predicting alcohol-related problems, but alcohol consumption was also investigated. Undergraduate students at a large Northwestern university (N=657) in the US participated in the study. They completed measures of jealousy, drinking to cope, alcohol use, and alcohol-related problems. Analyses examined associations between jealousy subscales, alcohol use, drinking to cope, and drinking problems. Results indicated that drinking to cope mediated the association between some, but not all, aspects of jealousy and problems with alcohol use. In particular, the more negative or maladaptive aspects of jealousy were related to drinking to cope and drinking problems, while the more adaptive aspects were not, suggesting a more complex view of jealousy than previously understood. © 2013. Published by Elsevier Ltd. All rights reserved.

Coping with Jealousy: The Association between Maladaptive Aspects of Jealousy and Drinking Problems are Mediated by Drinking to Cope

PubMed Central

DiBello, Angelo M.; Neighbors, Clayton; Rodriguez, Lindsey M.; Lindgren, Kristen

2013-01-01

Previous research has shown that both alcohol use and jealousy are related to negative relationship outcomes. Little work, however, has examined direct associations between alcohol use and jealousy. The current study aimed to build upon existing research examining alcohol use and jealousy. More specifically, findings from current jealousy literature indicate that jealousy is a multifaceted construct with both maladaptive and adaptive aspects. The current study examined the association between maladaptive and adaptive feelings of jealousy and alcohol-related problems in the context of drinking to cope. Given the relationship between coping motives and alcohol-related problems, our primary interest was in predicting alcohol-related problems, but alcohol consumption was also investigated. Undergraduate students at a large Northwestern university (N = 657) in the US participated in the study. They completed measures of jealousy, drinking to cope, alcohol use, and alcohol-related problems. Analyses examined associations between jealousy subscales, alcohol use, drinking to cope, and drinking problems. Results indicated that drinking to cope mediated the association between some, but not all, aspects of jealousy and problems with alcohol use. In particular, the more negative or maladaptive aspects of jealousy were related to drinking to cope and drinking problems, while the more adaptive aspects were not, suggesting a more complex view of jealousy than previously understood. PMID:24138965

Actuator Placement Via Genetic Algorithm for Aircraft Morphing

NASA Technical Reports Server (NTRS)

Crossley, William A.; Cook, Andrea M.

2001-01-01

This research continued work that began under the support of NASA Grant NAG1-2119. The focus of this effort was to continue investigations of Genetic Algorithm (GA) approaches that could be used to solve an actuator placement problem by treating this as a discrete optimization problem. In these efforts, the actuators are assumed to be "smart" devices that change the aerodynamic shape of an aircraft wing to alter the flow past the wing, and, as a result, provide aerodynamic moments that could provide flight control. The earlier work investigated issued for the problem statement, developed the appropriate actuator modeling, recognized the importance of symmetry for this problem, modified the aerodynamic analysis routine for more efficient use with the genetic algorithm, and began a problem size study to measure the impact of increasing problem complexity. The research discussed in this final summary further investigated the problem statement to provide a "combined moment" problem statement to simultaneously address roll, pitch and yaw. Investigations of problem size using this new problem statement provided insight into performance of the GA as the number of possible actuator locations increased. Where previous investigations utilized a simple wing model to develop the GA approach for actuator placement, this research culminated with application of the GA approach to a high-altitude unmanned aerial vehicle concept to demonstrate that the approach is valid for an aircraft configuration.

Structure and validity of sluggish cognitive tempo using an expanded item pool in children with attention-deficit/hyperactivity disorder.

PubMed

McBurnett, Keith; Villodas, Miguel; Burns, G Leonard; Hinshaw, Stephen P; Beaulieu, Allyson; Pfiffner, Linda J

2014-01-01

We evaluated the latent structure and validity of an expanded pool of Sluggish Cognitive Tempo (SCT) items. An experimental rating scale with 44 candidate SCT items was administered to parents and teachers of 165 children in grades 2-5 (ages 7-11) recruited for a randomized clinical trial of a psychosocial intervention for Attention-Deficit/Hyperactivity Disorder, Predominantly Inattentive Type. Exploratory factor analyses (EFA) were used to extract items with high loadings (>0.59) on primary factors of SCT and low cross-loadings (0.30 or lower) on other SCT factors and on the Inattention factor of ADHD. Items were required to meet these criteria for both informants. This procedure reduced the pool to 15 items. Generally, items representing slowness and low initiative failed these criteria. SCT factors (termed Daydreaming, Working Memory Problems, and Sleepy/Tired) showed good convergent and discriminant validity in EFA and in a confirmatory model with ADHD factors. Simultaneous regressions of impairment and comorbidity on SCT and ADHD factors found that Daydreams was associated with global impairment, and Sleepy/Tired was associated with organizational problems and depression ratings, across both informants. For teachers, Daydreams also predicted ODD (inversely); Sleepy/Tired also predicted poor academic behavior, low social skills, and problem social behavior; and Working Memory Problems predicted organizational problems and anxiety. When depression, rather than ADHD, was included among the predictors, the only SCT-related associations rendered insignificant were the teacher-reported associations of Daydreams with ODD; Working Memory Problems with anxiety, and Sleepy/Tired with poor social skills. SCT appears to be meaningfully associated with impairment, even when controlling for depression. Common behaviors resembling Working Memory problems may represent a previously undescribed factor of SCT.

Strategies for Global Optimization of Temporal Preferences

NASA Technical Reports Server (NTRS)

Morris, Paul; Morris, Robert; Khatib, Lina; Ramakrishnan, Sailesh

2004-01-01

A temporal reasoning problem can often be naturally characterized as a collection of constraints with associated local preferences for times that make up the admissible values for those constraints. Globally preferred solutions to such problems emerge as a result of well-defined operations that compose and order temporal assignments. The overall objective of this work is a characterization of different notions of global preference, and to identify tractable sub-classes of temporal reasoning problems incorporating these notions. This paper extends previous results by refining the class of useful notions of global temporal preference that are associated with problems that admit of tractable solution techniques. This paper also answers the hitherto open question of whether problems that seek solutions that are globally preferred from a Utilitarian criterion for global preference can be found tractably.

Mean-Variance Hedging on Uncertain Time Horizon in a Market with a Jump

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

Kharroubi, Idris, E-mail: kharroubi@ceremade.dauphine.fr; Lim, Thomas, E-mail: lim@ensiie.fr; Ngoupeyou, Armand, E-mail: armand.ngoupeyou@univ-paris-diderot.fr

2013-12-15

In this work, we study the problem of mean-variance hedging with a random horizon T∧τ, where T is a deterministic constant and τ is a jump time of the underlying asset price process. We first formulate this problem as a stochastic control problem and relate it to a system of BSDEs with a jump. We then provide a verification theorem which gives the optimal strategy for the mean-variance hedging using the solution of the previous system of BSDEs. Finally, we prove that this system of BSDEs admits a solution via a decomposition approach coming from filtration enlargement theory.

Multiscale real-space quantum-mechanical tight-binding calculations of electronic structure in crystals with defects using perfectly matched layers

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

Pourmatin, Hossein, E-mail: mpourmat@andrew.cmu.edu; Dayal, Kaushik, E-mail: kaushik@cmu.edu

2016-10-15

Graphical abstract: - Abstract: We consider the scattering of incident plane-wave electrons from a defect in a crystal modeled by the time-harmonic Schrödinger equation. While the defect potential is localized, the far-field potential is periodic, unlike standard free-space scattering problems. Previous work on the Schrödinger equation has been almost entirely in free-space conditions; a few works on crystals have been in one-dimension. We construct absorbing boundary conditions for this problem using perfectly matched layers in a tight-binding formulation. Using the example of a point defect in graphene, we examine the efficiency and convergence of the proposed absorbing boundary condition.

Violence Directed against Teachers: Results from a National Survey

ERIC Educational Resources Information Center

Mcmahon, Susan D.; Martinez, Andrew; Espelage, Dorothy; Rose, Chad; Reddy, Linda A.; Lane, Kathleen; Anderman, Eric M.; Reynolds, Cecil R.; Jones, Abraham; Brown, Veda

2014-01-01

Teachers in U.S. schools report high rates of victimization, yet previous studies focus on select types of victimization and student perpetrators, which may underestimate the extent of the problem. This national study was based on work conducted by the American Psychological Association Classroom Violence Directed Against Teachers Task Force and…

Educational Financing and Budgeting in Lao PDR. Financial Management of Education Systems. Working Document.

ERIC Educational Resources Information Center

Bouapao, Lytou; Sengchandavong, Ouam; Sihavong, Siphandone

This study provides an indepth description of financial management and budgetary procedures for education as well as a detailed analysis of major problems, recent developments, and new issues in Cambodia, Laos, and Vietnam. Laos, formerly one of the centrally planned economies, was previously considered "dormant" because of its limited…

Marijuana Effects on Human Forgetting Functions

ERIC Educational Resources Information Center

Lane, Scott D.; Cherek, Don R.; Lieving, Lori M.; Tcheremissine, Oleg V.

2005-01-01

It has long been known that acute marijuana administration impairs working memory (e.g., the discrimination of stimuli separated by a delay). The determination of which of the individual components of memory are altered by marijuana is an unresolved problem. Previous human studies did not use test protocols that allowed for the determination of…

Causes and Consequences of Early Life Health. NBER Working Paper No. 15637

ERIC Educational Resources Information Center

Case, Anne; Paxson, Christina

2010-01-01

We examine the consequences of childhood health for economic and health outcomes in adulthood, using height as a marker of health in childhood. After reviewing previous evidence, we present a conceptual framework that highlights data limitations and methodological problems associated with the study of this topic. We present estimates of the…

Collaborative Writing Tasks in the L2 Classroom: Comparing Group, Pair, and Individual Work

ERIC Educational Resources Information Center

Dobao, Ana Fernandez

2012-01-01

This study investigates the benefits of collaborative writing tasks. Previous research from the perspective of the sociocultural theory of mind suggests that writing tasks completed in pairs offer learners an opportunity to collaborate in the solution of their language-related problems, co-construct new language knowledge, and produce…

78 FR 26336 - Agency Information Collection Activities; Submission to the Office of Management and Budget for...

Federal Register 2010, 2011, 2012, 2013, 2014

2013-05-06

... PIAAC National Supplement builds upon the 2011-12 PIAAC Main Study, which was coordinated by the... addition to the United States. PIAAC assesses adult literacy, numeracy, and problem-solving skills in... employment experience and about the skills they use at work. PIAAC builds on previous international literacy...

British-Tradition English in the American University. Lektos: Interdisciplinary Working Papers in Language Sciences, Special Issue.

ERIC Educational Resources Information Center

Dubois, Betty Lou

This paper describes the English language problems encountered by foreign students at New Mexico State University, students whose previous educational experiences have included extensive use of British English. Specifically dealt with are West African students having lived in a situation where "transplanted English" was introduced by…

Towards an Entropy Stable Spectral Element Framework for Computational Fluid Dynamics

NASA Technical Reports Server (NTRS)

Carpenter, Mark H.; Parsani, Matteo; Fisher, Travis C.; Nielsen, Eric J.

2016-01-01

Entropy stable (SS) discontinuous spectral collocation formulations of any order are developed for the compressible Navier-Stokes equations on hexahedral elements. Recent progress on two complementary efforts is presented. The first effort is a generalization of previous SS spectral collocation work to extend the applicable set of points from tensor product, Legendre-Gauss-Lobatto (LGL) to tensor product Legendre-Gauss (LG) points. The LG and LGL point formulations are compared on a series of test problems. Although being more costly to implement, it is shown that the LG operators are significantly more accurate on comparable grids. Both the LGL and LG operators are of comparable efficiency and robustness, as is demonstrated using test problems for which conventional FEM techniques suffer instability. The second effort generalizes previous SS work to include the possibility of p-refinement at non-conforming interfaces. A generalization of existing entropy stability machinery is developed to accommodate the nuances of fully multi-dimensional summation-by-parts (SBP) operators. The entropy stability of the compressible Euler equations on non-conforming interfaces is demonstrated using the newly developed LG operators and multi-dimensional interface interpolation operators.

Co-evolution for Problem Simplification

NASA Technical Reports Server (NTRS)

Haith, Gary L.; Lohn, Jason D.; Cplombano, Silvano P.; Stassinopoulos, Dimitris

1999-01-01

This paper explores a co-evolutionary approach applicable to difficult problems with limited failure/success performance feedback. Like familiar "predator-prey" frameworks this algorithm evolves two populations of individuals - the solutions (predators) and the problems (prey). The approach extends previous work by rewarding only the problems that match their difficulty to the level of solut,ion competence. In complex problem domains with limited feedback, this "tractability constraint" helps provide an adaptive fitness gradient that, effectively differentiates the candidate solutions. The algorithm generates selective pressure toward the evolution of increasingly competent solutions by rewarding solution generality and uniqueness and problem tractability and difficulty. Relative (inverse-fitness) and absolute (static objective function) approaches to evaluating problem difficulty are explored and discussed. On a simple control task, this co-evolutionary algorithm was found to have significant advantages over a genetic algorithm with either a static fitness function or a fitness function that changes on a hand-tuned schedule.

[Adolescents previously involved in Satanism: mental health problems experience].

PubMed

Heathcote, H; Gmeiner, A; Poggenpoel, M

1998-03-01

As far as the phenomena of adolescents previously involved with satanism that experience obstacles in the strive for mental health, no research has previously been done. Adolescents previously involved in satanism, presents behaviour problems like aggressive outbursts depression, "psychosis", or suicide attempts that can even lead to suicide. In the phenomena-analysis semi-structured, phenomenological interviews with the respondents and their parents, were performed. The respondents were requested to write a naive sketch about there life. After the data-control was done, guidelines for nursing staff had been set. The guidelines are set for the management of adolescents that has previously been involved in satanism, and experiences obstacles in their strive for mental health. Interviews with experts in satanism was done, literature in the form of books, magazines and newsclippings were used to verify the findings in the research. The most important guidelines are that: the caregivers have to be reborn Christians; they are not allowed to show, any fear or sympathy; they have to have sufficient knowledge about satanism; the adolescent has to be unconditionally accepted; the caregivers have to work in a team; the adolescents have to be taught to deal with their emotions.

Adolescents previously involved in Satanism experiencing mental health problems.

PubMed

Heathcote, H; Gmeiner, A; Poggenpoel, M

1999-06-01

No research has previously been done regarding the phenomenon of adolescents who have previously been involved in Satanism and who experience obstacles in their strive for mental health. Adolescents previously involved in Satanism present behavioral problems like aggressive outbursts, depression, "psychosis" or suicide attempts, that could lead to suicide. In the phenomenon-analysis semi-structured, phenomenological interviews were performed with the respondents and their parents. The respondents were requested to write a naïve sketch about their life. After completion of the data-control, guidelines for nursing staff were set. The guidelines are set for the management of adolescents who have previously been involved in Satanism and who experience obstacles in their strive for mental health. Interviews with experts in Satanism were conducted, literature in the form of books, magazines and newspaper-clippings were used to verify the research findings. The most important guidelines are that the caregivers have to be reborn Christians; they are not allowed to show any fear or sympathy; they must have sufficient knowledge about Satanism; the adolescents have to be unconditionally accepted; the caregivers have to work in a team and the adolescents have to be taught to deal with their emotions.

Talking Physics: Two Case Studies on Short Answers and Self-explanation in Learning Physics

NASA Astrophysics Data System (ADS)

Badeau, Ryan C.

This thesis explores two case studies into the use of short answers and self-explanation to improve student learning in physics. The first set of experiments focuses on the role of short answer questions in the context of computer-based instruction. Through a series of six experiments, we compare and evaluate the performance of computer-assessed short answer questions versus multiple choice for training conceptual topics in physics, controlling for feedback between the two formats. In addition to finding overall similar improvements on subsequent student performance and retention, we identify unique differences in how students interact with the treatments in terms of time spent on feedback and performance on follow-up short answer assessment. In addition, we identify interactions between the level of interactivity of the training, question format, and student attitudinal ratings of each respective training. The second case study focuses on the use of worked examples in the context of multi-concept physics problems - which we call "synthesis problems." For this part of the thesis, four experiments were designed to evaluate the effectiveness of two instructional methods employing worked examples on student performance with synthesis problems; these instructional techniques, analogical comparison and self-explanation, have previously been studied primarily in the context of single-concept problems. As such, the work presented here represents a novel focus on extending these two techniques to this class of more complicated physics problem. Across the four experiments, both self-explanation and certain kinds of analogical comparison of worked examples significantly improved student performance on a target synthesis problem, with distinct improvements in recognition of the relevant concepts. More specifically, analogical comparison significantly improved student performance when the comparisons were invoked between worked synthesis examples. In contrast, similar comparisons between corresponding pairs of worked single-concept examples did not significantly improve performance. On a more complicated synthesis problem, self-explanation was significantly more effective than analogical comparison, potentially due to differences in how successfully students encoded the full structure of the worked examples. Finally, we find that the two techniques can be combined for additional benefit, with the trade-off of slightly more time-on-task.

Single-shot work extraction in quantum thermodynamics revisited

NASA Astrophysics Data System (ADS)

Wang, Shang-Yung

2018-01-01

We revisit the problem of work extraction from a system in contact with a heat bath to a work storage system, and the reverse problem of state formation from a thermal system state in single-shot quantum thermodynamics. A physically intuitive and mathematically simple approach using only elementary majorization theory and matrix analysis is developed, and a graphical interpretation of the maximum extractable work, minimum work cost of formation, and corresponding single-shot free energies is presented. This approach provides a bridge between two previous methods based respectively on the concept of thermomajorization and a comparison of subspace dimensions. In addition, a conceptual inconsistency with regard to general work extraction involving transitions between multiple energy levels of the work storage system is clarified and resolved. It is shown that an additional contribution to the maximum extractable work in those general cases should be interpreted not as work extracted from the system, but as heat transferred from the heat bath. Indeed, the additional contribution is an artifact of a work storage system (essentially a suspended ‘weight’ that can be raised or lowered) that does not truly distinguish work from heat. The result calls into question the common concept that a work storage system in quantum thermodynamics is simply the quantum version of a suspended weight in classical thermodynamics.

The linear stability of the post-Newtonian triangular equilibrium in the three-body problem

NASA Astrophysics Data System (ADS)

Yamada, Kei; Tsuchiya, Takuya

2017-12-01

Continuing a work initiated in an earlier publication (Yamada et al. in Phys Rev D 91:124016, 2015), we reexamine the linear stability of the triangular solution in the relativistic three-body problem for general masses by the standard linear algebraic analysis. In this paper, we start with the Einstein-Infeld-Hoffmann form of equations of motion for N-body systems in the uniformly rotating frame. As an extension of the previous work, we consider general perturbations to the equilibrium, i.e., we take account of perturbations orthogonal to the orbital plane, as well as perturbations lying on it. It is found that the orthogonal perturbations depend on each other by the first post-Newtonian (1PN) three-body interactions, though these are independent of the lying ones likewise the Newtonian case. We also show that the orthogonal perturbations do not affect the condition of stability. This is because these do not grow with time, but always precess with two frequency modes, namely, the same with the orbital frequency and the slightly different one due to the 1PN effect. The condition of stability, which is identical to that obtained by the previous work (Yamada et al. 2015) and is valid for the general perturbations, is obtained from the lying perturbations.

Training for Efficiency: Work, Time and Systems-based Practice in Medical Residency*

PubMed Central

Szymczak, Julia E.; Bosk, Charles L.

2013-01-01

Medical residency is a period of intense socialization with a heavy workload. Previous sociological studies have identified efficiency as a practical skill necessary for success. However, many contextual features of the training environment have undergone dramatic change since these studies were conducted. What are the consequences of these changes for the socialization of residents to time management and the development of a professional identity? Based on observations of and interviews with internal medicine residents at 3 training programs, we find that efficiency is both a social norm and strategy that residents employ to manage a workload for which the demand for work exceeds the supply of time available to accomplish it. We found that residents struggle to be efficient in the face of seemingly intractable “systems” problems. Residents work around these problems, and in doing so develop a tolerance for organizational vulnerabilities. PMID:22863601

Cognitive work analysis to evaluate the problem of patient falls in an inpatient setting

PubMed Central

Lopez, Karen Dunn; Cary, Michael P; Kanak, Mary F

2010-01-01

Objective To identify factors in the nursing work domain that contribute to the problem of inpatient falls, aside from patient risk, using cognitive work analysis. Design A mix of qualitative and quantitative methods were used to identify work constraints imposed on nurses, which may underlie patient falls. Measurements Data collection was done on a neurology unit staffed by 27 registered nurses and utilized field observations, focus groups, time–motion studies and written surveys (AHRQ Hospital Survey on Patient Culture, NASA-TLX, and custom Nursing Knowledge of Fall Prevention Subscale). Results Four major constraints were identified that inhibit nurses' ability to prevent patient falls. All constraints relate to work processes and the physical work environment, opposed to safety culture or nursing knowledge, as currently emphasized. The constraints were: cognitive ‘head data’, temporal workload, inconsistencies in written and verbal transfer of patient data, and limitations in the physical environment. To deal with these constraints, the nurses tend to employ four workarounds: written and mental chunking schemas, bed alarms, informal querying of the previous care nurse, and informal video and audio surveillance. These workarounds reflect systemic design flaws and may only be minimally effective in decreasing risk to patients. Conclusion Cognitive engineering techniques helped identify seemingly hidden constraints in the work domain that impact the problem of patient falls. System redesign strategies aimed at improving work processes and environmental limitations hold promise for decreasing the incidence of falls in inpatient nursing units. PMID:20442150

Cognitive work analysis to evaluate the problem of patient falls in an inpatient setting.

PubMed

Lopez, Karen Dunn; Gerling, Gregory J; Cary, Michael P; Kanak, Mary F

2010-01-01

To identify factors in the nursing work domain that contribute to the problem of inpatient falls, aside from patient risk, using cognitive work analysis. A mix of qualitative and quantitative methods were used to identify work constraints imposed on nurses, which may underlie patient falls. Data collection was done on a neurology unit staffed by 27 registered nurses and utilized field observations, focus groups, time-motion studies and written surveys (AHRQ Hospital Survey on Patient Culture, NASA-TLX, and custom Nursing Knowledge of Fall Prevention Subscale). Four major constraints were identified that inhibit nurses' ability to prevent patient falls. All constraints relate to work processes and the physical work environment, opposed to safety culture or nursing knowledge, as currently emphasized. The constraints were: cognitive 'head data', temporal workload, inconsistencies in written and verbal transfer of patient data, and limitations in the physical environment. To deal with these constraints, the nurses tend to employ four workarounds: written and mental chunking schemas, bed alarms, informal querying of the previous care nurse, and informal video and audio surveillance. These workarounds reflect systemic design flaws and may only be minimally effective in decreasing risk to patients. Cognitive engineering techniques helped identify seemingly hidden constraints in the work domain that impact the problem of patient falls. System redesign strategies aimed at improving work processes and environmental limitations hold promise for decreasing the incidence of falls in inpatient nursing units.

Personality traits, interpersonal problems and therapeutic alliance in early schizophrenia spectrum disorders.

PubMed

Johansen, Ragnhild; Melle, Ingrid; Iversen, Valentina Cabral; Hestad, Knut

2013-11-01

The quality of the therapeutic alliance is associated with engagement in- and thus important to the outcome of- treatment in schizophrenia. In non-psychotic disorders, general personality traits and individual patterns of interpersonal problems have been linked to the formation and quality of the therapeutic alliance. The role of these factors in relation to therapeutic alliance has not previously been explored in schizophrenia spectrum disorders. To investigate associations between personality traits, interpersonal problems and the quality of the therapeutic alliance in early schizophrenia spectrum disorders. Demographic and clinical characteristics including Positive and Negative Syndrome Scale (PANSS) scores were assessed in 42 patients. Personality traits and interpersonal problems were assessed with the NEO Five factor Inventory (NEO-FFI) and the circumplex model of the Inventory of Interpersonal Problems (IIP-64C). Therapeutic alliance was measured with the Working Alliance Inventory - short form (WAI-S). Patient WAI-S scores were predicted by IIP-64C Submissive/Hostile interpersonal problems, age and PANSS excitative symptoms. Therapist WAI-S scores were predicted by NEO-FFI Agreeableness and the PANSS insight item. Core traits of personality and dimensions of interpersonal problems are associated with both patients' and therapists' perceptions of the quality of the working alliance. Copyright © 2013 Elsevier Inc. All rights reserved.

[Study on empowerment factors for career continuity of hospital nurses].

PubMed

Kato, Hirosato; Ito, Yukie; Yoshida, Aki; Mizuno, Shizue; Ogoshi, Kumiko; Imamura, Tomoaki

2015-01-01

The resignation rate of nurses working in hospitals is extremely high. This study aims to identify both the factors related to the resignation of nurses and the empowerment factors supporting their job retention. In 2011 we conducted a Web-based questionnaire survey of nurses with less than 10 years of working experience. There were 25 survey items including the following reasons for choosing the current employment position, intention of continuing work, sense of fulfillment and the presence or absence of problems in the current workplace. In addition, nurses who previously had resigned were asked why they left their last workplace. The reasons why they chose the current workplace were markedly different between the not-resigned (A group) and previously resigned (B group) nurses. As a result of cluster analysis, the reasons for resignation were classified into six clusters; "overwork", "burnout", "bad atmosphere", "work life balance factors", "working conditions" and "marriage". In this study, it is shown that there is a positive correlation between the sense of fulfillment at work and the intention to do research work. It is suggested that encouragement of nurses to undertake research work is one of the empowerment factors supporting their job retention.

Testing a mediation model of psychotherapy process and outcome in psychodynamic psychotherapy: Previous client distress, psychodynamic techniques, dyadic working alliance, and current client distress.

PubMed

Kivlighan, Dennis M; Hill, Clara E; Ross, Katherine; Kline, Kathryn; Furhmann, Amy; Sauber, Elizabeth

2018-01-05

To test a sequential model of psychotherapy process and outcome, we included previous client distress, therapist psychodynamic techniques, dyadic working alliance, and current client distress. For 114 sets of eight-session segments in 40 cases of psychodynamic psychotherapy, clients completed the Outcome Questionnaire-45 and Inventory of Interpersonal Problems-32 after the first and final session, judges reliably coded one middle sessions on the Psychodynamic subscale of the Multitheoretical List of Therapeutic Interventions, and clients and therapists completed the Working Alliance Inventory after every session. Results indicated that higher use of psychodynamic techniques was associated with higher levels of the working alliance, which in turn was associated decreased client distress; and working alliance was higher later in psychotherapy. There was a significant indirect effect of psychodynamic techniques on decreases in distress mediated by the working alliance. Implications for theory, practice, and research are provided. Clinical or methodological significance of this article: Conducted a longitudinal, latent variable examination of the relationships of psychodynamic techniques and working alliance on client distress. Psychodynamic techniques have an indirect effect on decreases in client distress through the dyadic working alliance.

Prediction of employer-employee relationships from sociodemographic variables and social values in Brunei public and private sector workers.

PubMed

Mundia, Lawrence; Mahalle, Salwa; Matzin, Rohani; Nasir Zakaria, Gamal Abdul; Abdullah, Nor Zaiham Midawati; Abdul Latif, Siti Norhedayah

2017-01-01

The purpose of the study was to identify the sociodemographic variables and social value correlates and predictors of employer-employee relationship problems in a random sample of 860 Brunei public and private sector workers of both genders. A quantitative field survey design was used and data were analyzed by correlation and logistic regression. The rationale and justification for using this approach is explained. The main sociodemographic correlates and predictors of employer-employee relationship problems in this study were educational level and the district in which the employee resided and worked. Other correlates, but not necessarily predictors, of employer-employee relationship problems were seeking help from the Bomo (traditional healer); obtaining help from online social networking; and workers with children in the family. The two best and most significant social value correlates and predictors of employer-employee relationship problems included interpersonal communications; and self-regulation and self-direction. Low scorers on the following variables were also associated with high likelihood for possessing employer-employee relationship problems: satisfaction with work achievements; and peace and security, while low scorers on work stress had lower odds of having employer-employee relationship problems. Other significant social value correlates, but not predictors of employer-employee relationship problems were self-presentation; interpersonal trust; peace and security; and general anxiety. Consistent with findings of relevant previous studies conducted elsewhere, there were the variables that correlated with and predicted employer-employee relationship problems in Brunei public and private sector workers. Having identified these, the next step, efforts and priority should be directed at addressing the presenting issues via counseling and psychotherapy with affected employees. Further research is recommended to understand better the problem and its possible solutions.

Prediction of employer–employee relationships from sociodemographic variables and social values in Brunei public and private sector workers

PubMed Central

Mundia, Lawrence; Mahalle, Salwa; Matzin, Rohani; Nasir Zakaria, Gamal Abdul; Abdullah, Nor Zaiham Midawati; Abdul Latif, Siti Norhedayah

2017-01-01

The purpose of the study was to identify the sociodemographic variables and social value correlates and predictors of employer–employee relationship problems in a random sample of 860 Brunei public and private sector workers of both genders. A quantitative field survey design was used and data were analyzed by correlation and logistic regression. The rationale and justification for using this approach is explained. The main sociodemographic correlates and predictors of employer–employee relationship problems in this study were educational level and the district in which the employee resided and worked. Other correlates, but not necessarily predictors, of employer–employee relationship problems were seeking help from the Bomo (traditional healer); obtaining help from online social networking; and workers with children in the family. The two best and most significant social value correlates and predictors of employer–employee relationship problems included interpersonal communications; and self-regulation and self-direction. Low scorers on the following variables were also associated with high likelihood for possessing employer–employee relationship problems: satisfaction with work achievements; and peace and security, while low scorers on work stress had lower odds of having employer–employee relationship problems. Other significant social value correlates, but not predictors of employer–employee relationship problems were self-presentation; interpersonal trust; peace and security; and general anxiety. Consistent with findings of relevant previous studies conducted elsewhere, there were the variables that correlated with and predicted employer–employee relationship problems in Brunei public and private sector workers. Having identified these, the next step, efforts and priority should be directed at addressing the presenting issues via counseling and psychotherapy with affected employees. Further research is recommended to understand better the problem and its possible solutions. PMID:28769597

Multigrid Algorithms for the Solution of Linear Complementarity Problems Arising from Free Boundary Problems.

DTIC Science & Technology

1980-10-01

faster than previous algorithms. Indeed, with only minor modifications, the standard multigrid programs solve the LCP with essentially the same efficiency... Lemna 2.2. Let Uk be the solution of the LCP (2.3), and let uk > 0 be an approximate solu- tion obtained after one or more Gk projected sweeps. Let...in Figure 3.2, Ivu IIG decreased from .293 10 to .110 10 with the expenditure of (99.039-94.400) = 4.639 work units. While minor variations do arise, a

Particle Acceleration in a Statistically Modeled Solar Active-Region Corona

NASA Astrophysics Data System (ADS)

Toutounzi, A.; Vlahos, L.; Isliker, H.; Dimitropoulou, M.; Anastasiadis, A.; Georgoulis, M.

2013-09-01

Elaborating a statistical approach to describe the spatiotemporally intermittent electric field structures formed inside a flaring solar active region, we investigate the efficiency of such structures in accelerating charged particles (electrons). The large-scale magnetic configuration in the solar atmosphere responds to the strong turbulent flows that convey perturbations across the active region by initiating avalanche-type processes. The resulting unstable structures correspond to small-scale dissipation regions hosting strong electric fields. Previous research on particle acceleration in strongly turbulent plasmas provides a general framework for addressing such a problem. This framework combines various electromagnetic field configurations obtained by magnetohydrodynamical (MHD) or cellular automata (CA) simulations, or by employing a statistical description of the field's strength and configuration with test particle simulations. Our objective is to complement previous work done on the subject. As in previous efforts, a set of three probability distribution functions describes our ad-hoc electromagnetic field configurations. In addition, we work on data-driven 3D magnetic field extrapolations. A collisional relativistic test-particle simulation traces each particle's guiding center within these configurations. We also find that an interplay between different electron populations (thermal/non-thermal, ambient/injected) in our simulations may also address, via a re-acceleration mechanism, the so called `number problem'. Using the simulated particle-energy distributions at different heights of the cylinder we test our results against observations, in the framework of the collisional thick target model (CTTM) of solar hard X-ray (HXR) emission. The above work is supported by the Hellenic National Space Weather Research Network (HNSWRN) via the THALIS Programme.

Unemployment, health and health services in German-speaking countries.

PubMed

Schwefel, D

1986-01-01

The links between unemployment and health are manifold: Employment may lead to illness: health problems (that may lead to unemployment) often result from unfavourable working conditions of the (previous) employment. Another factor is job insecurity: fear of job loss increases the incidence of disease, and this applies not only to people who are emotionally unstable. Illness may lead to unemployment: in many cases, unemployment is caused by previous health impairments, which, to a considerable extent, also explain the duration of unemployment. Unemployment may lead to illness: there is evidence that unemployment not only reinforces existing physical disease but also acts as a risk factor for new ones. This seems particularly true for problem groups such as the unemployed elderly as well as for infants and children of unemployed people. The relations between unemployment and mental health are strong, mainly in terms of depression and alcoholism. Unemployment may lead to health: short-time work and short-term unemployment may improve health by reducing previous stress, caused by employment or by an overload with social roles. Even in the case of long-term unemployment there are some positive health effects as long as a minimum of social security and alternative social roles are available and useful activities--minor agricultural jobs, illicit work--can be carried out. The links between unemployment, work and society can considerably be loosened by a number of social factors and personal characteristics of the people affected. Existing health services are not in a position to deal with disease stemming from employment or unemployment except through symptomatical and curative therapies. In addition to general medical care, which is guaranteed by the German health insurance system for the unemployed, too, therapeutical measures are especially important in cases of depression and alcoholism. As a rule, the medical profession has no knowledge of the links between health, work and unemployment; such knowledge, however, would facilitate prevention. Individual prevention and rehabilitation measures are of great importance to problem groups suffering from cumulative or indirect unemployment, i.e. to unemployed elderly as well as to children of unemployed parents. Since the unemployed tend to isolate themselves, extramural services are useful. Specific services for the unemployed only are certainly not as helpful as multi-functional social services, such as those being already rendered by some self-help organizations, churches and trade-unions.(ABSTRACT TRUNCATED AT 400 WORDS)

Differential Associations of UPPS-P Impulsivity Traits With Alcohol Problems.

PubMed

McCarty, Kayleigh N; Morris, David H; Hatz, Laura E; McCarthy, Denis M

2017-07-01

The UPPS-P model posits that impulsivity comprises five factors: positive urgency, negative urgency, lack of planning, lack of perseverance, and sensation seeking. Negative and positive urgency are the traits most consistently associated with alcohol problems. However, previous work has examined alcohol problems either individually or in the aggregate, rather than examining multiple problem domains simultaneously. Recent work has also questioned the utility of distinguishing between positive and negative urgency, as this distinction did not meaningfully differ in predicting domains of psychopathology. The aims of this study were to address these issues by (a) testing unique associations of UPPS-P with specific domains of alcohol problems and (b) determining the utility of distinguishing between positive and negative urgency as risk factors for specific alcohol problems. Associations between UPPS-P traits and alcohol problem domains were examined in two cross-sectional data sets using negative binomial regression models. In both samples, negative urgency was associated with social/interpersonal, self-perception, risky behaviors, and blackout drinking problems. Positive urgency was associated with academic/occupational and physiological dependence problems. Both urgency traits were associated with impaired control and self-care problems. Associations for other UPPS-P traits did not replicate across samples. Results indicate that negative and positive urgency have differential associations with alcohol problem domains. Results also suggest a distinction between the type of alcohol problems associated with these traits-negative urgency was associated with problems experienced during a drinking episode, whereas positive urgency was associated with alcohol problems that result from longer-term drinking trends.

Nickel-hydrogen separator development

NASA Technical Reports Server (NTRS)

Gonzalez-Sanabria, O. D.

1986-01-01

The separator technology is a critical element in the nickel-hydrogen (Ni-H2) systems. Previous research and development work carried out at NASA Lewis Research Center has determined that separators made from zirconium oxide (ZrO2) and potassium titanate (PKT) fibers will function satisfactorily in Ni-H2 cells without exhibiting the problems associated with the asbestos separators. These separators and their characteristics were previously discussed. A program was established to transfer the separator technology into a commercial production line. A detailed plan of this program will be presented and the preliminary results will be discussed.

A Novel Joint Problem of Routing, Scheduling, and Variable-Width Channel Allocation in WMNs

PubMed Central

Liu, Wan-Yu; Chou, Chun-Hung

2014-01-01

This paper investigates a novel joint problem of routing, scheduling, and channel allocation for single-radio multichannel wireless mesh networks in which multiple channel widths can be adjusted dynamically through a new software technology so that more concurrent transmissions and suppressed overlapping channel interference can be achieved. Although the previous works have studied this joint problem, their linear programming models for the problem were not incorporated with some delicate constraints. As a result, this paper first constructs a linear programming model with more practical concerns and then proposes a simulated annealing approach with a novel encoding mechanism, in which the configurations of multiple time slots are devised to characterize the dynamic transmission process. Experimental results show that our approach can find the same or similar solutions as the optimal solutions for smaller-scale problems and can efficiently find good-quality solutions for a variety of larger-scale problems. PMID:24982990

A General Architecture for Intelligent Tutoring of Diagnostic Classification Problem Solving

PubMed Central

Crowley, Rebecca S.; Medvedeva, Olga

2003-01-01

We report on a general architecture for creating knowledge-based medical training systems to teach diagnostic classification problem solving. The approach is informed by our previous work describing the development of expertise in classification problem solving in Pathology. The architecture envelops the traditional Intelligent Tutoring System design within the Unified Problem-solving Method description Language (UPML) architecture, supporting component modularity and reuse. Based on the domain ontology, domain task ontology and case data, the abstract problem-solving methods of the expert model create a dynamic solution graph. Student interaction with the solution graph is filtered through an instructional layer, which is created by a second set of abstract problem-solving methods and pedagogic ontologies, in response to the current state of the student model. We outline the advantages and limitations of this general approach, and describe it’s implementation in SlideTutor–a developing Intelligent Tutoring System in Dermatopathology. PMID:14728159

Meshless Local Petrov-Galerkin Method for Bending Problems

NASA Technical Reports Server (NTRS)

Phillips, Dawn R.; Raju, Ivatury S.

2002-01-01

Recent literature shows extensive research work on meshless or element-free methods as alternatives to the versatile Finite Element Method. One such meshless method is the Meshless Local Petrov-Galerkin (MLPG) method. In this report, the method is developed for bending of beams - C1 problems. A generalized moving least squares (GMLS) interpolation is used to construct the trial functions, and spline and power weight functions are used as the test functions. The method is applied to problems for which exact solutions are available to evaluate its effectiveness. The accuracy of the method is demonstrated for problems with load discontinuities and continuous beam problems. A Petrov-Galerkin implementation of the method is shown to greatly reduce computational time and effort and is thus preferable over the previously developed Galerkin approach. The MLPG method for beam problems yields very accurate deflections and slopes and continuous moment and shear forces without the need for elaborate post-processing techniques.

A hybrid, auto-adaptive and rule-based multi-agent approach using evolutionary algorithms for improved searching

NASA Astrophysics Data System (ADS)

Izquierdo, Joaquín; Montalvo, Idel; Campbell, Enrique; Pérez-García, Rafael

2016-08-01

Selecting the most appropriate heuristic for solving a specific problem is not easy, for many reasons. This article focuses on one of these reasons: traditionally, the solution search process has operated in a given manner regardless of the specific problem being solved, and the process has been the same regardless of the size, complexity and domain of the problem. To cope with this situation, search processes should mould the search into areas of the search space that are meaningful for the problem. This article builds on previous work in the development of a multi-agent paradigm using techniques derived from knowledge discovery (data-mining techniques) on databases of so-far visited solutions. The aim is to improve the search mechanisms, increase computational efficiency and use rules to enrich the formulation of optimization problems, while reducing the search space and catering to realistic problems.

Investigation of the relationship between convenient visits and doctors' fatigue using burnout and work engagement scales.

PubMed

Matsumoto, Yuuki; Hoshiko, Michiko; Morimatsu, Yoshitaka; Mori, Mihoko; Kushino, Nanae; Ishitake, Tatsuya

2015-01-01

Fatigue caused by high workload is often responsible for the high attrition among doctors, and has contributed to a disruption in community medicine. In order to address this problem, institutional mechanisms at the hospital level are required. Previous studies have shown that systemic measures at the hospital level and a change in the mindset of patients can help manage the problem. "Convenient visits" refer to emergency visits for non-emergency problems. It is an avoidable cause of high workload on doctors. Convenient visits also refer to emergency consultation for non-emergency symptoms. As this is a new phenomenon, its relationship with doctors' fatigue needs further research. We investigated the relationship between convenient visits and doctors' fatigue using burnout and work engagement scales. We selected 44 hospitals, with >200 beds each, in provincial cities of prefectures with a doctor-population ratio lower than the national average. These cities were considered likely to manifest the phenomenon of 24-hour society and include overworked doctors. Ordinance-designated cities were excluded from this study owing to wide population variability. Three doctors from each hospital were randomly selected from among physicians, surgeons, and pediatricians. We distributed questionnaires (a questionnaire concerning convenient visits, Maslach Burnout Inventory-Human Services Survey, and Utrecht Work Engagement Scale) to 132 doctors. Forty-two doctors responded to the survey. The median proportion of convenient visits among emergency visits was 50%. Sixty percent of the doctors surveyed were annoyed by convenient visits. Other doctors indicated good collaboration between the hospitals and communities or that they were not currently annoyed by convenient visits, although they had been annoyed previously. The emotional exhaustion in doctors, who worked in hospitals that did not restrict convenient visits, was significantly higher than in those who worked in hospitals that restricted these visits. A significant risk of serious burnout was found via crude and multiple logistic regression analysis (adjusted for age and gender, or adjusted for age, gender, clinical department, frequency of work shifts, and sleep duration during work shifts). Doctors working in hospitals that do not protect them against convenient visits are more prone to burnout. Although the number of convenient visitors is increasing, many hospitals lack systemic measures to manage them. This contributes to doctors' burnout. We suggest that hospitals control convenient visits for preventing doctors' burnout. Collaboration between hospitals and communities is required to help alleviate this problem.

What Are the Problems with Teacher Supply?

ERIC Educational Resources Information Center

White, Patrick; Gorard, Stephen; See, Beng Huat

2006-01-01

This paper is based on our studies of teacher recruitment and retention. Using official statistics from a variety of secondary sources, it builds on our previous work on the changing demand for teachers by exploring issues of teacher supply in the UK. Our findings suggest there is no overall shortage of applicants to initial teacher education and…

Gaps and Barriers in Services for Children in State Mental Health Plans

ERIC Educational Resources Information Center

Gould, Sara R.; Beals-Erickson, Sarah E.; Roberts, Michael C.

2012-01-01

Significant gaps exist in children's mental healthcare, and barriers prevent access to existing services. Current federal initiatives call for state governmental agencies to recognize and resolve deficits in their systems of care. Previous work has acknowledged some of the problems in meeting the mental health needs of children within a system of…

Expert systems research

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

Duda, R.O.; Shortliffe, E.H.

1983-04-15

Artificial intelligence, long a topic of basic computer science research, is now being applied to problems of scientific, technical, and commercial interest. Some consultation programs although limited in versatility, have achieved levels of performance rivaling those of human experts. A collateral benefit of this work is the systematization of previously unformalized knowledge in areas such as medical diagnosis and geology. 30 references.

Sleep Quality and Alcohol Risk in College Students: Examining the Moderating Effects of Drinking Motives

ERIC Educational Resources Information Center

Kenney, Shannon R.; Paves, Andrew P.; Grimaldi, Elizabeth M.; LaBrie, Joseph W.

2014-01-01

Objective: Sleep problems and alcohol misuse are common issues experienced by college students that can have detrimental effects on overall health. Previous work indicates a strong relationship between poor sleep quality and alcohol risk in this population. This study explored the moderating effect of drinking motives in the relationship between…

The Difficulties of a Curriculum Helper in an Urban School.

ERIC Educational Resources Information Center

Smith, Michael S.

This paper describes the experiences of a teacher and a curriculum helper in designing and implementing a fifth grade language arts curriculum at an inner city, magnet school in Indianapolis (Indiana). The report describes the work in three phases: (1) making explicit the problems with the previous language arts curriculum; (2) formulating a plan…

A constrained robust least squares approach for contaminant release history identification

NASA Astrophysics Data System (ADS)

Sun, Alexander Y.; Painter, Scott L.; Wittmeyer, Gordon W.

2006-04-01

Contaminant source identification is an important type of inverse problem in groundwater modeling and is subject to both data and model uncertainty. Model uncertainty was rarely considered in the previous studies. In this work, a robust framework for solving contaminant source recovery problems is introduced. The contaminant source identification problem is first cast into one of solving uncertain linear equations, where the response matrix is constructed using a superposition technique. The formulation presented here is general and is applicable to any porous media flow and transport solvers. The robust least squares (RLS) estimator, which originated in the field of robust identification, directly accounts for errors arising from model uncertainty and has been shown to significantly reduce the sensitivity of the optimal solution to perturbations in model and data. In this work, a new variant of RLS, the constrained robust least squares (CRLS), is formulated for solving uncertain linear equations. CRLS allows for additional constraints, such as nonnegativity, to be imposed. The performance of CRLS is demonstrated through one- and two-dimensional test problems. When the system is ill-conditioned and uncertain, it is found that CRLS gave much better performance than its classical counterpart, the nonnegative least squares. The source identification framework developed in this work thus constitutes a reliable tool for recovering source release histories in real applications.

Hierarchical Recognition Scheme for Human Facial Expression Recognition Systems

PubMed Central

Siddiqi, Muhammad Hameed; Lee, Sungyoung; Lee, Young-Koo; Khan, Adil Mehmood; Truc, Phan Tran Ho

2013-01-01

Over the last decade, human facial expressions recognition (FER) has emerged as an important research area. Several factors make FER a challenging research problem. These include varying light conditions in training and test images; need for automatic and accurate face detection before feature extraction; and high similarity among different expressions that makes it difficult to distinguish these expressions with a high accuracy. This work implements a hierarchical linear discriminant analysis-based facial expressions recognition (HL-FER) system to tackle these problems. Unlike the previous systems, the HL-FER uses a pre-processing step to eliminate light effects, incorporates a new automatic face detection scheme, employs methods to extract both global and local features, and utilizes a HL-FER to overcome the problem of high similarity among different expressions. Unlike most of the previous works that were evaluated using a single dataset, the performance of the HL-FER is assessed using three publicly available datasets under three different experimental settings: n-fold cross validation based on subjects for each dataset separately; n-fold cross validation rule based on datasets; and, finally, a last set of experiments to assess the effectiveness of each module of the HL-FER separately. Weighted average recognition accuracy of 98.7% across three different datasets, using three classifiers, indicates the success of employing the HL-FER for human FER. PMID:24316568

Improving the efficiency of a user-driven learning system with reconfigurable hardware. Application to DNA splicing.

PubMed

Lemoine, E; Merceron, D; Sallantin, J; Nguifo, E M

1999-01-01

This paper describes a new approach to problem solving by splitting up problem component parts between software and hardware. Our main idea arises from the combination of two previously published works. The first one proposed a conceptual environment of concept modelling in which the machine and the human expert interact. The second one reported an algorithm based on reconfigurable hardware system which outperforms any kind of previously published genetic data base scanning hardware or algorithms. Here we show how efficient the interaction between the machine and the expert is when the concept modelling is based on reconfigurable hardware system. Their cooperation is thus achieved with an real time interaction speed. The designed system has been partially applied to the recognition of primate splice junctions sites in genetic sequences.

A gyrokinetic one-dimensional scrape-off layer model of an edge-localized mode heat pulse

DOE PAGES

Shi, E. L.; Hakim, A. H.; Hammett, G. W.

2015-02-03

An electrostatic gyrokinetic-based model is applied to simulate parallel plasma transport in the scrape-off layer to a divertor plate. We focus on a test problem that has been studied previously, using parameters chosen to model a heat pulse driven by an edge-localized mode in JET. Previous work has used direct particle-in-cellequations with full dynamics, or Vlasov or fluid equations with only parallel dynamics. With the use of the gyrokinetic quasineutrality equation and logical sheathboundary conditions, spatial and temporal resolution requirements are no longer set by the electron Debye length and plasma frequency, respectively. Finally, this test problem also helps illustratemore » some of the physics contained in the Hamiltonian form of the gyrokineticequations and some of the numerical challenges in developing an edge gyrokinetic code.« less

Quantum-Like Representation of Non-Bayesian Inference

NASA Astrophysics Data System (ADS)

Asano, M.; Basieva, I.; Khrennikov, A.; Ohya, M.; Tanaka, Y.

2013-01-01

This research is related to the problem of "irrational decision making or inference" that have been discussed in cognitive psychology. There are some experimental studies, and these statistical data cannot be described by classical probability theory. The process of decision making generating these data cannot be reduced to the classical Bayesian inference. For this problem, a number of quantum-like coginitive models of decision making was proposed. Our previous work represented in a natural way the classical Bayesian inference in the frame work of quantum mechanics. By using this representation, in this paper, we try to discuss the non-Bayesian (irrational) inference that is biased by effects like the quantum interference. Further, we describe "psychological factor" disturbing "rationality" as an "environment" correlating with the "main system" of usual Bayesian inference.

On the Directional Dependence and Null Space Freedom in Uncertainty Bound Identification

NASA Technical Reports Server (NTRS)

Lim, K. B.; Giesy, D. P.

1997-01-01

In previous work, the determination of uncertainty models via minimum norm model validation is based on a single set of input and output measurement data. Since uncertainty bounds at each frequency is directionally dependent for multivariable systems, this will lead to optimistic uncertainty levels. In addition, the design freedom in the uncertainty model has not been utilized to further reduce uncertainty levels. The above issues are addressed by formulating a min- max problem. An analytical solution to the min-max problem is given to within a generalized eigenvalue problem, thus avoiding a direct numerical approach. This result will lead to less conservative and more realistic uncertainty models for use in robust control.

Dominant takeover regimes for genetic algorithms

NASA Technical Reports Server (NTRS)

Noever, David; Baskaran, Subbiah

1995-01-01

The genetic algorithm (GA) is a machine-based optimization routine which connects evolutionary learning to natural genetic laws. The present work addresses the problem of obtaining the dominant takeover regimes in the GA dynamics. Estimated GA run times are computed for slow and fast convergence in the limits of high and low fitness ratios. Using Euler's device for obtaining partial sums in closed forms, the result relaxes the previously held requirements for long time limits. Analytical solution reveal that appropriately accelerated regimes can mark the ascendancy of the most fit solution. In virtually all cases, the weak (logarithmic) dependence of convergence time on problem size demonstrates the potential for the GA to solve large N-P complete problems.

Protocols development for security and privacy of radio frequency identification systems

NASA Astrophysics Data System (ADS)

Sabbagha, Fatin

There are benefits to adopting radio frequency identification (RFID) technology, although there are methods of attack that can compromise the system. This research determined how that may happen and what possible solutions can keep that from happening. Protocols were developed to implement better security. In addition, new topologies were developed to handle the problems of the key management. Previously proposed protocols focused on providing mutual authentication and privacy between readers and tags. However, those protocols are still vulnerable to be attacked. These protocols were analyzed and the disadvantages shown for each one. Previous works assumed that the channels between readers and the servers were secure. In the proposed protocols, a compromised reader is considered along with how to prevent tags from being read by that reader. The new protocols provide mutual authentication between readers and tags and, at the same time, remove the compromised reader from the system. Three protocols are proposed. In the first protocol, a mutual authentication is achieved and a compromised reader is not allowed in the network. In the second protocol, the number of times a reader contacts the server is reduced. The third protocol provides authentication and privacy between tags and readers using a trusted third party. The developed topology is implemented using python language and simulates work to check the efficiency regarding the processing time. The three protocols are implemented by writing codes in C language and then compiling them in MSP430. IAR Embedded workbench is used, which is an integrated development environment with the C/C++ compiler to generate a faster code and to debug the microcontroller. In summary, the goal of this research is to find solutions for the problems on previously proposed protocols, handle a compromised reader, and solve key management problems.

Gender role stereotype and poor working condition pose obstacles for female doctors to stay in full-time employment: alumnae survey from two private medical schools in Japan.

PubMed

Izumi, Miki; Nomura, Kyoko; Higaki, Yuko; Akaishi, Yu; Seki, Masayasu; Kobayashi, Shizuko; Komoda, Takayuki; Otaki, Junji

2013-03-01

The shortage of physicians has become a serious problem in Japan. It has been pointed out that an increase in the number of female doctors may contribute to the aggravation of this shortage because it is known that women work fewer hours than male doctors. Here, we investigated how many female doctors had ever resigned from a full-time position, and elucidated the reasons why female doctors find it difficult to stay in full-time employment. An alumnae survey of 2 private medical schools was conducted in 2007. A self-administered questionnaire was sent to 1423 graduates and 711 responded with informed consent (response rate, 50%; mean age, 39 years). Overall, 55% of the respondents had previously resigned from full-time employment, of which 90% resigned within 10 years of graduating from medical school. The difficulty in balancing work, childbirth and child rearing (45%) were the top 2 reasons for resignation, followed by physical problems (12%) and long working hours (8%). Among those who resigned, only 33% returned to full-time employment. Women who had at least 1 child were only 30% of those who had never resigned and 84% of those who had previously resigned. The majority of study subjects, regardless of experience of resignation (88%), agreed that women should continue to work even after childbirth. In conclusion, the results of this study suggested that many female doctors resigned from a full-time position within 10 years of graduating from medical school, largely because of the gender role stereotype and poor working conditions.

A swallowtail catastrophe model for the emergence of leadership in coordination-intensive groups.

PubMed

Guastello, Stephen J; Bond, Robert W

2007-04-01

This research extended the previous studies concerning the swallowtail catastrophe model for leadership emergence to coordination-intensive groups. Thirteen 4-person groups composed of undergraduates played in Intersection coordination (card game) task and were allowed to talk while performing it; 13 other groups worked nonverbally. A questionnaire measured leadership emergence at the end of the game along with other social contributions to the groups' efforts. The swallowtail catastrophe model that was evident in previous leadership emergence phenomena in creative problem solving and production groups was found here also. All three control parameters were identified: a general participation variable that was akin to K in the rugged landscape model of self-organization, task control, and whether the groups worked verbally or nonverbally. Several new avenues for future research were delineated.

Work related risk factors for musculoskeletal complaints in the spinning industry in Lithuania

PubMed Central

Gamperiene, M.; Stigum, H.

1999-01-01

OBJECTIVES: To describe the prevalence of self reported musculoskeletal complaints in the back, arms or neck, and legs among workers in the spinning industry, and to investigate the relations between these complaints and work related variables. METHODS: An interview based questionnaire survey was carried out in two spinning industry factories in Lithuania. RESULTS: The study group consisted of all workers in production (n = 363). Symptoms of the legs were the musculoskeletal symptom reported most often (61%). Many subjects had arms or neck (55%) or back problems (28%). 20% had experienced pain from all three sites. Almost 25% had had musculoskeletal pain every day and 16% had experienced constant pain during previous year. Packers had the highest risk of arms or neck problems whereas spinners had the highest risk of back or leg problems. Working in a strained posture (bending, work with arms raised up above shoulder level, and repetitive movements of the fingers) was associated with all three complaints. Only arms or neck complaints were associated with age. CONCLUSIONS: Musculoskeletal disorders are a common problem among workers producing gobelin or synthetic thread in Lithuania and working in a strained posture is a risk factor for developing musculoskeletal disorders in three body sites: legs, arms or neck, and back. To better understand the different aspects of physical load as risk factors, a more detailed study of the frequency of postural changes as well as an observation of individually adopted postures would be necessary. This applies to intervention studies in factories of the spinning industry to prevent complaints of the legs and shoulders.   PMID:10474538

Artifact Reduction in X-Ray CT Images of Al-Steel-Perspex Specimens Mimicking a Hip Prosthesis

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

Madhogarhia, Manish; Munshi, P.; Lukose, Sijo

2008-09-26

X-ray Computed Tomography (CT) is a relatively new technique developed in the late 1970's, which enables the nondestructive visualization of the internal structure of objects. Beam hardening caused by the polychromatic spectrum is an important problem in X-ray computed tomography (X-CT). It leads to various artifacts in reconstruction images and reduces image quality. In the present work we are considering the Artifact Reduction in Total Hip Prosthesis CT Scan which is a problem of medical imaging. We are trying to reduce the cupping artifact induced by beam hardening as well as metal artifact as they exist in the CT scanmore » of a human hip after the femur is replaced by a metal implant. The correction method for beam hardening used here is based on a previous work. Simulation study for the present problem includes a phantom consisting of mild steel, aluminium and perspex mimicking the photon attenuation properties of a hum hip cross section with metal implant.« less

[Current problems in the use of probation with compulsory work].

PubMed

Salautdinov, S A

1976-01-01

In the framework of the Soviet law, probation accompanied by compulsory work represents an up-to-date measure of a criminal character that allows to rehabilitate a convicted offender without depriving him of his freedom. The Panfederal Institute for the study of the causes of criminal behaviour and for the formulation of measures for preventing it, has conducted a number of researches directed at clearing up some debated problems bearing on the implementation of the measures existing on the subject, and at collecting proposals of amendment. The present article deals with the assumptions and preconditions, of both an objective and subjective character, underlying the application of this juridical institute, and also tackles, by referring to some cases previously occurred, the problems posed by the various types of subjects. Special attention is devoted to the decision-making procedure followed by the tribunals in applying the said measures, and to the various elements on which it is to be based.

Swarm intelligence for multi-objective optimization of synthesis gas production

NASA Astrophysics Data System (ADS)

Ganesan, T.; Vasant, P.; Elamvazuthi, I.; Ku Shaari, Ku Zilati

2012-11-01

In the chemical industry, the production of methanol, ammonia, hydrogen and higher hydrocarbons require synthesis gas (or syn gas). The main three syn gas production methods are carbon dioxide reforming (CRM), steam reforming (SRM) and partial-oxidation of methane (POM). In this work, multi-objective (MO) optimization of the combined CRM and POM was carried out. The empirical model and the MO problem formulation for this combined process were obtained from previous works. The central objectives considered in this problem are methane conversion, carbon monoxide selectivity and the hydrogen to carbon monoxide ratio. The MO nature of the problem was tackled using the Normal Boundary Intersection (NBI) method. Two techniques (Gravitational Search Algorithm (GSA) and Particle Swarm Optimization (PSO)) were then applied in conjunction with the NBI method. The performance of the two algorithms and the quality of the solutions were gauged by using two performance metrics. Comparative studies and results analysis were then carried out on the optimization results.

Output-feedback control of combined sewer networks through receding horizon control with moving horizon estimation

NASA Astrophysics Data System (ADS)

Joseph-Duran, Bernat; Ocampo-Martinez, Carlos; Cembrano, Gabriela

2015-10-01

An output-feedback control strategy for pollution mitigation in combined sewer networks is presented. The proposed strategy provides means to apply model-based predictive control to large-scale sewer networks, in-spite of the lack of measurements at most of the network sewers. In previous works, the authors presented a hybrid linear control-oriented model for sewer networks together with the formulation of Optimal Control Problems (OCP) and State Estimation Problems (SEP). By iteratively solving these problems, preliminary Receding Horizon Control with Moving Horizon Estimation (RHC/MHE) results, based on flow measurements, were also obtained. In this work, the RHC/MHE algorithm has been extended to take into account both flow and water level measurements and the resulting control loop has been extensively simulated to assess the system performance according different measurement availability scenarios and rain events. All simulations have been carried out using a detailed physically based model of a real case-study network as virtual reality.

Magnetic sensor technology for detecting mines, UXO, and other concealed security threats

NASA Astrophysics Data System (ADS)

Czipott, Peter V.; Iwanowski, Mark D.

1997-01-01

Magnetic sensors have been the sensor of choice in the detection and classification of buried mines and unexploded ordnance (UXO), both on land and underwater, Quantum Magnetics (QM), together with its research partner IBM, have developed a variety of advanced, very high sensitivity superconducting and room temperature magnetic sensors to meet military needs. This work has led to the development and utilization of a three-sensor gradiometer (TSG) patented by IBM, which cannot only detect, but also localize mines and ordnance. QM is also working with IBM and the U.S. Navy to develop an advanced superconducting gradiometer for buried underwater mine detection. The ability to both detect and classify buried non-metallic mines is virtually impossible with existing magnetic sensors. To solve this problem, Quantum Magnetics, building on work of the Naval Research Laboratory (NRL), is pioneering work in the development of quadrupole resonance (QR) methods which can be used to detect the explosive material directly. Based on recent laboratory work done at QM and previous work done in the U.S., Russia and the United Kingdom, we are confident that QR can be effectively applied to the non-metallic mine identification problem.

Assimilation approach to measuring organizational change from pre- to post-intervention

PubMed Central

Moore, Scott C; Osatuke, Katerine; Howe, Steven R

2014-01-01

AIM: To present a conceptual and measurement strategy that allows to objectively, sensitively evaluate intervention progress based on data of participants’ perceptions of presenting problems. METHODS: We used as an example an organization development intervention at a United States Veterans Affairs medical center. Within a year, the intervention addressed the hospital’s initially serious problems and multiple stakeholders (employees, management, union representatives) reported satisfaction with progress made. Traditional quantitative outcome measures, however, failed to capture the strong positive impact consistently reported by several types of stakeholders in qualitative interviews. To address the paradox, full interview data describing the medical center pre- and post- intervention were examined applying a validated theoretical framework from another discipline: Psychotherapy research. The Assimilation model is a clinical-developmental theory that describes empirically grounded change levels in problematic experiences, e.g., problems reported by participants. The model, measure Assimilation of Problematic Experiences Scale (APES), and rating procedure have been previously applied across various populations and problem types, mainly in clinical but also in non-clinical settings. We applied the APES to the transcribed qualitative data of intervention participants’ interviews, using the method closely replicating prior assimilation research (the process whereby trained clinicians familiar with the Assimilation model work with full, transcribed interview data to assign the APES ratings). The APES ratings summarized levels of progress which was defined as participants’ assimilation level of problematic experiences, and compared from pre- to post-intervention. RESULTS: The results were consistent with participants’ own reported perceptions of the intervention impact. Increase in APES levels from pre- to post-intervention suggested improvement, missed in the previous quantitative measures (the Maslach Burnout Inventory and the Work Environment Scale). The progress specifically consisted of participants’ moving from the APES stages where the problematic experience was avoided, to the APES stages where awareness and attention to the problems were steadily sustained, although the problems were not yet fully processed or resolved. These results explain why the conventional outcome measures failed to reflect the intervention progress; they narrowly defined progress as resolution of the presenting problems and alleviation of symptomatic distress. In the Assimilation model, this definition only applies to a sub-segment of the change continuum, specifically the latest APES stages. The model defines progress as change in psychological processes used in response to the problem, i.e., a growing ability to deal with problematic issues non-defensively, manifested differently depending on APES stages. At early stages, progress is an increased ability to face the problem rather than turning away. At later APES stages, progress involves naming, understanding and successfully addressing the problem. The assimilation approach provides a broader developmental context compared to exclusively symptom, problem-, or behavior- focused approaches that typically inform outcome measurement in interpersonally based interventions. In our data, this made the difference between reflecting (APES) vs missing (Maslach Burnout Inventory, Work Environment Scale) the pre-post change that was strongly perceived by the intervention recipients. CONCLUSION: The results illustrated a working solution to the challenge of objectively evaluating progress in subjectively experienced problems. This approach informs measuring change in psychologically based interventions. PMID:24660141

Towards parameter-free classification of sound effects in movies

NASA Astrophysics Data System (ADS)

Chu, Selina; Narayanan, Shrikanth; Kuo, C.-C. J.

2005-08-01

The problem of identifying intense events via multimedia data mining in films is investigated in this work. Movies are mainly characterized by dialog, music, and sound effects. We begin our investigation with detecting interesting events through sound effects. Sound effects are neither speech nor music, but are closely associated with interesting events such as car chases and gun shots. In this work, we utilize low-level audio features including MFCC and energy to identify sound effects. It was shown in previous work that the Hidden Markov model (HMM) works well for speech/audio signals. However, this technique requires a careful choice in designing the model and choosing correct parameters. In this work, we introduce a framework that will avoid such necessity and works well with semi- and non-parametric learning algorithms.

Teaching Rational Number Addition Using Video Games: The Effects of Instructional Variation. CRESST Report 808

ERIC Educational Resources Information Center

Vendlinski, Terry P.; Chung, Greg K. W. K.; Binning, Kevin R.; Buschang, Rebecca E.

2011-01-01

Understanding the meaning of rational numbers and how to perform mathematical operations with those numbers seems to be a perennial problem in the United States for both adults and children. Based on previous work, we hypothesized that giving students more time to practice using rational numbers in an environment that enticed them to apply their…

Worrying about What Others Think: A Social-Comparison Concern Intervention in Small Learning Groups

ERIC Educational Resources Information Center

Micari, Marina; Pazos, Pilar

2014-01-01

Small-group learning has become commonplace in education at all levels. While it has been shown to have many benefits, previous research has demonstrated that it may not always work to the advantage of every student. One potential problem is that less-prepared students may feel anxious about participating, for fear of looking "dumb" in…

A Sequence of Assignments for Basic Writing: Teaching To Problems "Beyond the Sentence."

ERIC Educational Resources Information Center

Wall, Susan V.

Students in college basic writing courses need to consider their own written language and to compare it with other students' work before they can develop a sense of the symbolic relationship between language and experience. Because of a lack of previous writing experience, basic writers have no sense that the "facts" about which they write are…

Focus Particles at Syntactic, Semantic, and Pragmatic Interfaces: The Acquisition of Only and Even in English

ERIC Educational Resources Information Center

Kim, Soyoung

2012-01-01

In order to interpret a sentence, hearers must often access information that is not explicitly stated, drawing on pragmatic knowledge and/or the discourse context. A problem with previous work on the acquisition of English focus particles such as "only," "also," "even," etc. is that it has often ignored such factors. Using a context-based…

Encouraging Survey Participation among Individuals Seeking HIV Prevention Services: Does a Community Identity Match Help or Hurt?

ERIC Educational Resources Information Center

Crowley, Jocelyn Elise; Roff, Brian H.; Lynch, Jeneve

2007-01-01

Understanding the behaviors and attitudes of at-risk populations is fundamental to controlling the spread of HIV, the virus that causes AIDS. The problem of nonresponse among these populations, however, plagues survey research designed to address these issues. Previous work undertaken to map out the dynamics of nonresponse--both noncontacts and…

ConfChem Conference on Flipped Classroom: Time-Saving Resources Aligned with Cognitive Science to Help Instructors

ERIC Educational Resources Information Center

Hartman, JudithAnn R.; Dahm, Donald J.; Nelson, Eric A.

2015-01-01

Studies in cognitive science have verified that working memory (where the brain solves problems) can manipulate nearly all elements of knowledge that can be recalled automatically from long-term memory, but only a few elements that have not previously been well memorized. Research in reading comprehension has found that "lecture notes with…

A new graph-based method for pairwise global network alignment

PubMed Central

Klau, Gunnar W

2009-01-01

Background In addition to component-based comparative approaches, network alignments provide the means to study conserved network topology such as common pathways and more complex network motifs. Yet, unlike in classical sequence alignment, the comparison of networks becomes computationally more challenging, as most meaningful assumptions instantly lead to NP-hard problems. Most previous algorithmic work on network alignments is heuristic in nature. Results We introduce the graph-based maximum structural matching formulation for pairwise global network alignment. We relate the formulation to previous work and prove NP-hardness of the problem. Based on the new formulation we build upon recent results in computational structural biology and present a novel Lagrangian relaxation approach that, in combination with a branch-and-bound method, computes provably optimal network alignments. The Lagrangian algorithm alone is a powerful heuristic method, which produces solutions that are often near-optimal and – unlike those computed by pure heuristics – come with a quality guarantee. Conclusion Computational experiments on the alignment of protein-protein interaction networks and on the classification of metabolic subnetworks demonstrate that the new method is reasonably fast and has advantages over pure heuristics. Our software tool is freely available as part of the LISA library. PMID:19208162

Optimal Wonderful Life Utility Functions in Multi-Agent Systems

NASA Technical Reports Server (NTRS)

Wolpert, David H.; Tumer, Kagan; Swanson, Keith (Technical Monitor)

2000-01-01

The mathematics of Collective Intelligence (COINs) is concerned with the design of multi-agent systems so as to optimize an overall global utility function when those systems lack centralized communication and control. Typically in COINs each agent runs a distinct Reinforcement Learning (RL) algorithm, so that much of the design problem reduces to how best to initialize/update each agent's private utility function, as far as the ensuing value of the global utility is concerned. Traditional team game solutions to this problem assign to each agent the global utility as its private utility function. In previous work we used the COIN framework to derive the alternative Wonderful Life Utility (WLU), and experimentally established that having the agents use it induces global utility performance up to orders of magnitude superior to that induced by use of the team game utility. The WLU has a free parameter (the clamping parameter) which we simply set to zero in that previous work. Here we derive the optimal value of the clamping parameter, and demonstrate experimentally that using that optimal value can result in significantly improved performance over that of clamping to zero, over and above the improvement beyond traditional approaches.

Associating optical measurements and estimating orbits of geocentric objects with a Genetic Algorithm: performance limitations.

NASA Astrophysics Data System (ADS)

Zittersteijn, Michiel; Schildknecht, Thomas; Vananti, Alessandro; Dolado Perez, Juan Carlos; Martinot, Vincent

2016-07-01

Currently several thousands of objects are being tracked in the MEO and GEO regions through optical means. With the advent of improved sensors and a heightened interest in the problem of space debris, it is expected that the number of tracked objects will grow by an order of magnitude in the near future. This research aims to provide a method that can treat the correlation and orbit determination problems simultaneously, and is able to efficiently process large data sets with minimal manual intervention. This problem is also known as the Multiple Target Tracking (MTT) problem. The complexity of the MTT problem is defined by its dimension S. Current research tends to focus on the S = 2 MTT problem. The reason for this is that for S = 2 the problem has a P-complexity. However, with S = 2 the decision to associate a set of observations is based on the minimum amount of information, in ambiguous situations (e.g. satellite clusters) this will lead to incorrect associations. The S > 2 MTT problem is an NP-hard combinatorial optimization problem. In previous work an Elitist Genetic Algorithm (EGA) was proposed as a method to approximately solve this problem. It was shown that the EGA is able to find a good approximate solution with a polynomial time complexity. The EGA relies on solving the Lambert problem in order to perform the necessary orbit determinations. This means that the algorithm is restricted to orbits that are described by Keplerian motion. The work presented in this paper focuses on the impact that this restriction has on the algorithm performance.

MILP model for integrated balancing and sequencing mixed-model two-sided assembly line with variable launching interval and assignment restrictions

NASA Astrophysics Data System (ADS)

Azmi, N. I. L. Mohd; Ahmad, R.; Zainuddin, Z. M.

2017-09-01

This research explores the Mixed-Model Two-Sided Assembly Line (MMTSAL). There are two interrelated problems in MMTSAL which are line balancing and model sequencing. In previous studies, many researchers considered these problems separately and only few studied them simultaneously for one-sided line. However in this study, these two problems are solved simultaneously to obtain more efficient solution. The Mixed Integer Linear Programming (MILP) model with objectives of minimizing total utility work and idle time is generated by considering variable launching interval and assignment restriction constraint. The problem is analysed using small-size test cases to validate the integrated model. Throughout this paper, numerical experiment was conducted by using General Algebraic Modelling System (GAMS) with the solver CPLEX. Experimental results indicate that integrating the problems of model sequencing and line balancing help to minimise the proposed objectives function.

Making It Work for Everyone: An Evolving Reference Service.

PubMed

Feldman, Jonquil D; Lopez, Emme; Gaspard, Christine S; Barton, Karen D; Barcenes, Luis F

2018-01-01

At an academic health science center, librarians identified problems, weaknesses, and strengths in reference services. The on-call reference schedule was discontinued and a question flowchart was developed for circulation staff. Only research questions were referred to librarians, who would respond if available. Circulation staff perceived the unscheduled, voluntary model was not working well for the patrons or the staff. After two months, the schedule was reinstated with a hybrid version of the previous on-call format. In the process of changing the service model, the library staff also underwent a cultural change.

A health hierarchy of effects model: a synthesis of advertising and health hierarchy conceptualizations.

PubMed

Rouse, R A

1991-01-01

Work by both advertising and health researchers has independently yielded hierarchy of effects models which can be used to predict campaign success. Unfortunately, however, previous work has been criticized as "common sense" approaches which are more "assumed" than "proven." This analysis argues that much of the problem is due to the lack of precision often associated with over-simplified "uni-dimensional" models. Instead, this perspective synthesized a "two-dimensional" health hierarchy of effects model and outlines a pragmatic strategy for campaign measurement.

Revisiting Higgs inflation in the context of collapse theories

NASA Astrophysics Data System (ADS)

Rodriguez, Saul; Sudarsky, Daniel

2018-03-01

In this work we consider the Higgs inflation scenario, but in contrast with past works, the present analysis is done in the context of a spontaneous collapse theory for the quantum state of the inflaton field. In particular, we will rely on a previously studied adaptation of the Continuous Spontaneous Localization model for the treatment of inflationary cosmology. We will show that with the introduction of the dynamical collapse hypothesis, some of the most serious problems of the Higgs inflation proposal can be resolved in a natural way.

The role of expressive writing in math anxiety.

PubMed

Park, Daeun; Ramirez, Gerardo; Beilock, Sian L

2014-06-01

Math anxiety is a negative affective reaction to situations involving math. Previous work demonstrates that math anxiety can negatively impact math problem solving by creating performance-related worries that disrupt the working memory needed for the task at hand. By leveraging knowledge about the mechanism underlying the math anxiety-performance relationship, we tested the effectiveness of a short expressive writing intervention that has been shown to reduce intrusive thoughts and improve working memory availability. Students (N = 80) varying in math anxiety were asked to sit quietly (control group) prior to completing difficulty-matched math and word problems or to write about their thoughts and feelings regarding the exam they were about to take (expressive writing group). For the control group, high math-anxious individuals (HMAs) performed significantly worse on the math problems than low math-anxious students (LMAs). In the expressive writing group, however, this difference in math performance across HMAs and LMAs was significantly reduced. Among HMAs, the use of words related to anxiety, cause, and insight in their writing was positively related to math performance. Expressive writing boosts the performance of anxious students in math-testing situations. PsycINFO Database Record (c) 2014 APA, all rights reserved.

Stochastic Local Search for Core Membership Checking in Hedonic Games

NASA Astrophysics Data System (ADS)

Keinänen, Helena

Hedonic games have emerged as an important tool in economics and show promise as a useful formalism to model multi-agent coalition formation in AI as well as group formation in social networks. We consider a coNP-complete problem of core membership checking in hedonic coalition formation games. No previous algorithms to tackle the problem have been presented. In this work, we overcome this by developing two stochastic local search algorithms for core membership checking in hedonic games. We demonstrate the usefulness of the algorithms by showing experimentally that they find solutions efficiently, particularly for large agent societies.

The Effect of the Ill-posed Problem on Quantitative Error Assessment in Digital Image Correlation

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

Lehoucq, R. B.; Reu, P. L.; Turner, D. Z.

Here, this work explores the effect of the ill-posed problem on uncertainty quantification for motion estimation using digital image correlation (DIC) (Sutton et al. 2009). We develop a correction factor for standard uncertainty estimates based on the cosine of the angle between the true motion and the image gradients, in an integral sense over a subregion of the image. This correction factor accounts for variability in the DIC solution previously unaccounted for when considering only image noise, interpolation bias, contrast, and the software settings such as subset size and spacing.

The Effect of the Ill-posed Problem on Quantitative Error Assessment in Digital Image Correlation

DOE PAGES

Lehoucq, R. B.; Reu, P. L.; Turner, D. Z.

2017-11-27

Here, this work explores the effect of the ill-posed problem on uncertainty quantification for motion estimation using digital image correlation (DIC) (Sutton et al. 2009). We develop a correction factor for standard uncertainty estimates based on the cosine of the angle between the true motion and the image gradients, in an integral sense over a subregion of the image. This correction factor accounts for variability in the DIC solution previously unaccounted for when considering only image noise, interpolation bias, contrast, and the software settings such as subset size and spacing.

On the convergence of an iterative formulation of the electromagnetic scattering from an infinite grating of thin wires

NASA Technical Reports Server (NTRS)

Brand, J. C.

1985-01-01

Contraction theory is applied to an iterative formulation of electromagnetic scattering from periodic structures and a computational method for insuring convergence is developed. A short history of spectral (or k-space) formulation is presented with an emphasis on application to periodic surfaces. The mathematical background for formulating an iterative equation is covered using straightforward single variable examples including an extension to vector spaces. To insure a convergent solution of the iterative equation, a process called the contraction corrector method is developed. Convergence properties of previously presented iterative solutions to one-dimensional problems are examined utilizing contraction theory and the general conditions for achieving a convergent solution are explored. The contraction corrector method is then applied to several scattering problems including an infinite grating of thin wires with the solution data compared to previous works.

Engineering approximations in welding: Bridging the gap between the speculation and simulation

DOE PAGES

Robino, Charles V.

2016-01-15

During the course of their careers, welding engineers and welding metallurgists are often confronted with questions regarding welding process and properties that on the surface appear to be simple and direct, but are in fact quite challenging. These questions generally mask an underlying complexity whose underpinnings in scientific and applied research predate even the founding of the American Welding Society, and previous Comfort A. Adams lectures provide ample and fascinating evidence of the breadth and depth of this complexity. Using these studies or their own experiences and investigations as a basis, most welding and materials engineers have developed engineering toolsmore » to provide working approaches to these day-to-day questions and problems. In this article several examples of research into developing working approaches to welding problems are presented.« less

Engineering approximations in welding: Bridging the gap between the speculation and simulation

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

Robino, Charles V.

During the course of their careers, welding engineers and welding metallurgists are often confronted with questions regarding welding process and properties that on the surface appear to be simple and direct, but are in fact quite challenging. These questions generally mask an underlying complexity whose underpinnings in scientific and applied research predate even the founding of the American Welding Society, and previous Comfort A. Adams lectures provide ample and fascinating evidence of the breadth and depth of this complexity. Using these studies or their own experiences and investigations as a basis, most welding and materials engineers have developed engineering toolsmore » to provide working approaches to these day-to-day questions and problems. In this article several examples of research into developing working approaches to welding problems are presented.« less

Diagrams benefit symbolic problem-solving.

PubMed

Chu, Junyi; Rittle-Johnson, Bethany; Fyfe, Emily R

2017-06-01

The format of a mathematics problem often influences students' problem-solving performance. For example, providing diagrams in conjunction with story problems can benefit students' understanding, choice of strategy, and accuracy on story problems. However, it remains unclear whether providing diagrams in conjunction with symbolic equations can benefit problem-solving performance as well. We tested the impact of diagram presence on students' performance on algebra equation problems to determine whether diagrams increase problem-solving success. We also examined the influence of item- and student-level factors to test the robustness of the diagram effect. We worked with 61 seventh-grade students who had received 2 months of pre-algebra instruction. Students participated in an experimenter-led classroom session. Using a within-subjects design, students solved algebra problems in two matched formats (equation and equation-with-diagram). The presence of diagrams increased equation-solving accuracy and the use of informal strategies. This diagram benefit was independent of student ability and item complexity. The benefits of diagrams found previously for story problems generalized to symbolic problems. The findings are consistent with cognitive models of problem-solving and suggest that diagrams may be a useful additional representation of symbolic problems. © 2017 The British Psychological Society.

Subjective randomness as statistical inference.

PubMed

Griffiths, Thomas L; Daniels, Dylan; Austerweil, Joseph L; Tenenbaum, Joshua B

2018-06-01

Some events seem more random than others. For example, when tossing a coin, a sequence of eight heads in a row does not seem very random. Where do these intuitions about randomness come from? We argue that subjective randomness can be understood as the result of a statistical inference assessing the evidence that an event provides for having been produced by a random generating process. We show how this account provides a link to previous work relating randomness to algorithmic complexity, in which random events are those that cannot be described by short computer programs. Algorithmic complexity is both incomputable and too general to capture the regularities that people can recognize, but viewing randomness as statistical inference provides two paths to addressing these problems: considering regularities generated by simpler computing machines, and restricting the set of probability distributions that characterize regularity. Building on previous work exploring these different routes to a more restricted notion of randomness, we define strong quantitative models of human randomness judgments that apply not just to binary sequences - which have been the focus of much of the previous work on subjective randomness - but also to binary matrices and spatial clustering. Copyright © 2018 Elsevier Inc. All rights reserved.

Age-related changes in strategic variations during arithmetic problem solving: The role of executive control.

PubMed

Hinault, T; Lemaire, P

2016-01-01

In this review, we provide an overview of how age-related changes in executive control influence aging effects in arithmetic processing. More specifically, we consider the role of executive control in strategic variations with age during arithmetic problem solving. Previous studies found that age-related differences in arithmetic performance are associated with strategic variations. That is, when they accomplish arithmetic problem-solving tasks, older adults use fewer strategies than young adults, use strategies in different proportions, and select and execute strategies less efficiently. Here, we review recent evidence, suggesting that age-related changes in inhibition, cognitive flexibility, and working memory processes underlie age-related changes in strategic variations during arithmetic problem solving. We discuss both behavioral and neural mechanisms underlying age-related changes in these executive control processes. © 2016 Elsevier B.V. All rights reserved.

Intensive working memory training: a single case experimental design in a patient following hypoxic brain damage.

PubMed

Hynes, S M; Fish, J; Manly, T

2014-01-01

Recent reports suggest that intensive, progressive training on working memory tasks can lead to generalized cognitive gains. A patient, following hypoxic brain damage, showed significant difficulties in working memory and time-perception. This study examined the impact and specificity of any benefits resulting from automated working memory training (AWMT) in comparison with the effects of an equivalent programme that emphasized automated novel problem-solving (APST) which served as an active control. Following initial assessment, the patient trained for 4 weeks (20 days), 20-30 minutes a day on the APST tasks before repeating key outcome measures. He then trained for an identical period on AWMT. There were no cognitive gains apparent following APST. Furthermore, there were no disproportionate gains on digit span following AWMT. AWMT was, however, associated with improvement in time-perception that had previously been resistant to rehabilitation. In line with previous reports, AWMT was also followed by gains on a measure of planning. The results provide encouraging evidence that AWMT may have generalized benefits in the context of impaired WM capacity following brain injury.

Erratum: A Comparison of Closures for Stochastic Advection-Diffusion Equations

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

Jarman, Kenneth D.; Tartakovsky, Alexandre M.

2015-01-01

This note corrects an error in the authors' article [SIAM/ASA J. Uncertain. Quantif., 1 (2013), pp. 319 347] in which the cited work [Neuman, Water Resour. Res., 29(3) (1993), pp. 633 645] was incorrectly represented and attributed. Concentration covariance equations presented in our article as new were in fact previously derived in the latter work. In the original abstract, the phrase " . . .we propose a closed-form approximation to two-point covariance as a measure of uncertainty. . ." should be replaced by the phrase " . . .we study a closed-form approximation to two-point covariance, previously derived in [Neumanmore » 1993], as a measure of uncertainty." The primary results in our article--the analytical and numerical comparison of existing closure methods for specific example problems are not changed by this correction.« less

Whistler waves with electron temperature anisotropy and non-Maxwellian distribution functions

NASA Astrophysics Data System (ADS)

Malik, M. Usman; Masood, W.; Qureshi, M. N. S.; Mirza, Arshad M.

2018-05-01

The previous works on whistler waves with electron temperature anisotropy narrated the dependence on plasma parameters, however, they did not explore the reasons behind the observed differences. A comparative analysis of the whistler waves with different electron distributions has not been made to date. This paper attempts to address both these issues in detail by making a detailed comparison of the dispersion relations and growth rates of whistler waves with electron temperature anisotropy for Maxwellian, Cairns, kappa and generalized (r, q) distributions by varying the key plasma parameters for the problem under consideration. It has been found that the growth rate of whistler instability is maximum for flat-topped distribution whereas it is minimum for the Maxwellian distribution. This work not only summarizes and complements the previous work done on the whistler waves with electron temperature anisotropy but also provides a general framework to understand the linear propagation of whistler waves with electron temperature anisotropy that is applicable in all regions of space plasmas where the satellite missions have indicated their presence.

Analysis of Feeder Bus Network Design and Scheduling Problems

PubMed Central

Almasi, Mohammad Hadi; Karim, Mohamed Rehan

2014-01-01

A growing concern for public transit is its inability to shift passenger's mode from private to public transport. In order to overcome this problem, a more developed feeder bus network and matched schedules will play important roles. The present paper aims to review some of the studies performed on Feeder Bus Network Design and Scheduling Problem (FNDSP) based on three distinctive parts of the FNDSP setup, namely, problem description, problem characteristics, and solution approaches. The problems consist of different subproblems including data preparation, feeder bus network design, route generation, and feeder bus scheduling. Subsequently, descriptive analysis and classification of previous works are presented to highlight the main characteristics and solution methods. Finally, some of the issues and trends for future research are identified. This paper is targeted at dealing with the FNDSP to exhibit strategic and tactical goals and also contributes to the unification of the field which might be a useful complement to the few existing reviews. PMID:24526890

Constraint-based integration of planning and scheduling for space-based observatory management

NASA Technical Reports Server (NTRS)

Muscettola, Nicola; Smith, Steven F.

1994-01-01

Progress toward the development of effective, practical solutions to space-based observatory scheduling problems within the HSTS scheduling framework is reported. HSTS was developed and originally applied in the context of the Hubble Space Telescope (HST) short-term observation scheduling problem. The work was motivated by the limitations of the current solution and, more generally, by the insufficiency of classical planning and scheduling approaches in this problem context. HSTS has subsequently been used to develop improved heuristic solution techniques in related scheduling domains and is currently being applied to develop a scheduling tool for the upcoming Submillimeter Wave Astronomy Satellite (SWAS) mission. The salient architectural characteristics of HSTS and their relationship to previous scheduling and AI planning research are summarized. Then, some key problem decomposition techniques underlying the integrated planning and scheduling approach to the HST problem are described; research results indicate that these techniques provide leverage in solving space-based observatory scheduling problems. Finally, more recently developed constraint-posting scheduling procedures and the current SWAS application focus are summarized.

Expert systems applications for space shuttle payload integration automation

NASA Technical Reports Server (NTRS)

Morris, Keith

1988-01-01

Expert systems technologies have been and are continuing to be applied to NASA's Space Shuttle orbiter payload integration problems to provide a level of automation previously unrealizable. NASA's Space Shuttle orbiter was designed to be extremely flexible in its ability to accommodate many different types and combinations of satellites and experiments (payloads) within its payload bay. This flexibility results in differnet and unique engineering resource requirements for each of its payloads, creating recurring payload and cargo integration problems. Expert systems provide a successful solution for these recurring problems. The Orbiter Payload Bay Cabling Expert (EXCABL) was the first expert system, developed to solve the electrical services provisioning problem. A second expert system, EXMATCH, was developed to generate a list of the reusable installation drawings available for each EXCABL solution. These successes have proved the applicability of expert systems technologies to payload integration problems and consequently a third expert system is currently in work. These three expert systems, the manner in which they resolve payload problems and how they will be integrated are described.

A Coherent VLSI Environment

DTIC Science & Technology

1987-03-31

processors . The symmetry-breaking algorithms give efficient ways to convert probabilistic algorithms to deterministic algorithms. Some of the...techniques have been applied to construct several efficient linear- processor algorithms for graph problems, including an O(lg* n)-time algorithm for (A + 1...On n-node graphs, the algorithm works in O(log 2 n) time using only n processors , in contrast to the previous best algorithm which used about n3

Special Course on Interaction of Propagation and Digital Transmission Techniques

DTIC Science & Technology

1986-10-01

military roles. Many working systems have been demonstrated, and there are a number of fully operational civil systems, see for example (Western Union ...provided by the previous analogue systems, impose increased bandwidth demands which are difficult to fulfill in the spectrally-congested European...AGARD, 1984, "Propagation influences on digital transmission systems - problems and solutions", AGARD CP No.363. 2. Western Union

A Computer Program for Solving a Set of Conditional Maximum Likelihood Equations Arising in the Rasch Model for Questionnaires.

ERIC Educational Resources Information Center

Andersen, Erling B.

A computer program for solving the conditional likelihood equations arising in the Rasch model for questionnaires is described. The estimation method and the computational problems involved are described in a previous research report by Andersen, but a summary of those results are given in two sections of this paper. A working example is also…

A Galerkin approximation for linear elastic shallow shells

NASA Astrophysics Data System (ADS)

Figueiredo, I. N.; Trabucho, L.

1992-03-01

This work is a generalization to shallow shell models of previous results for plates by B. Miara (1989). Using the same basis functions as in the plate case, we construct a Galerkin approximation of the three-dimensional linearized elasticity problem, and establish some error estimates as a function of the thickness, the curvature, the geometry of the shell, the forces and the Lamé costants.

Capacitors for Aircraft High Power

DTIC Science & Technology

1980-04-01

Methanol ext rM hton:1 2 . 343 I .2 Z vacuum driedl 1 6034 31 -11 3 5910 30 -17 54 6159 31 A .4 1431 -26:1K raft 1 Vacuum dried at 105 0C � 36 0...was employed, so that each design was the result of the previous work and problems. A very large amount of data was taken during the test effort, anl

Classification with asymmetric label noise: Consistency and maximal denoising

DOE PAGES

Blanchard, Gilles; Flaska, Marek; Handy, Gregory; ...

2016-09-20

In many real-world classification problems, the labels of training examples are randomly corrupted. Most previous theoretical work on classification with label noise assumes that the two classes are separable, that the label noise is independent of the true class label, or that the noise proportions for each class are known. In this work, we give conditions that are necessary and sufficient for the true class-conditional distributions to be identifiable. These conditions are weaker than those analyzed previously, and allow for the classes to be nonseparable and the noise levels to be asymmetric and unknown. The conditions essentially state that amore » majority of the observed labels are correct and that the true class-conditional distributions are “mutually irreducible,” a concept we introduce that limits the similarity of the two distributions. For any label noise problem, there is a unique pair of true class-conditional distributions satisfying the proposed conditions, and we argue that this pair corresponds in a certain sense to maximal denoising of the observed distributions. Our results are facilitated by a connection to “mixture proportion estimation,” which is the problem of estimating the maximal proportion of one distribution that is present in another. We establish a novel rate of convergence result for mixture proportion estimation, and apply this to obtain consistency of a discrimination rule based on surrogate loss minimization. Experimental results on benchmark data and a nuclear particle classification problem demonstrate the efficacy of our approach. MSC 2010 subject classifications: Primary 62H30; secondary 68T10. Keywords and phrases: Classification, label noise, mixture proportion estimation, surrogate loss, consistency.« less

Classification with asymmetric label noise: Consistency and maximal denoising

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

Blanchard, Gilles; Flaska, Marek; Handy, Gregory

In many real-world classification problems, the labels of training examples are randomly corrupted. Most previous theoretical work on classification with label noise assumes that the two classes are separable, that the label noise is independent of the true class label, or that the noise proportions for each class are known. In this work, we give conditions that are necessary and sufficient for the true class-conditional distributions to be identifiable. These conditions are weaker than those analyzed previously, and allow for the classes to be nonseparable and the noise levels to be asymmetric and unknown. The conditions essentially state that amore » majority of the observed labels are correct and that the true class-conditional distributions are “mutually irreducible,” a concept we introduce that limits the similarity of the two distributions. For any label noise problem, there is a unique pair of true class-conditional distributions satisfying the proposed conditions, and we argue that this pair corresponds in a certain sense to maximal denoising of the observed distributions. Our results are facilitated by a connection to “mixture proportion estimation,” which is the problem of estimating the maximal proportion of one distribution that is present in another. We establish a novel rate of convergence result for mixture proportion estimation, and apply this to obtain consistency of a discrimination rule based on surrogate loss minimization. Experimental results on benchmark data and a nuclear particle classification problem demonstrate the efficacy of our approach. MSC 2010 subject classifications: Primary 62H30; secondary 68T10. Keywords and phrases: Classification, label noise, mixture proportion estimation, surrogate loss, consistency.« less

Maximizing work integration in job placement of individuals facing mental health problems: Supervisor experiences.

PubMed

Skarpaas, Lisebet Skeie; Ramvi, Ellen; Løvereide, Lise; Aas, Randi Wågø

2015-01-01

Many people confronting mental health problems are excluded from participation in paid work. Supervisor engagement is essential for successful job placement. To elicit supervisor perspectives on the challenges involved in fostering integration to support individuals with mental health problems (trainees) in their job placement at ordinary companies. Explorative, qualitative designed study with a phenomenological approach, based on semi-structured interviews with 15 supervisors involved in job placements for a total of 105 trainees (mean 7, min-max. 1-30, SD 8). Data were analysed using qualitative content analysis. Superviors experience two interrelated dilemmas concerning knowledge of the trainee and degree of preferential treatment. Challenges to obtaining successful integration were; motivational: 1) Supervisors previous experience with trainees encourages future engagement, 2) Developing a realistic picture of the situation, and 3) Disclosure and knowledge of mental health problems, and continuity challenges: 4) Sustaining trainee cooperation throughout the placement process, 5) Building and maintaining a good relationship between supervisor and trainee, and 6) Ensuring continuous cooperation with the social security system and other stakeholders. Supervisors experience relational dilemmas regarding pre-judgment, privacy and equality. Job placement seem to be maximized when the stakeholders are motivated and recognize that cooperation must be a continuous process.

Problem-based learning: Using students' questions to drive knowledge construction

NASA Astrophysics Data System (ADS)

Chin, Christine; Chia, Li-Gek

2004-09-01

This study employed problem-based learning for project work in a year 9 biology class. The purpose of the study was to investigate (a) students' inspirations for their self-generated problems and questions, (b) the kinds of questions that students asked individually and collaboratively, and (c) how students' questions guided them in knowledge construction. Data sources included observation and field notes, students' written documents, audiotapes and videotapes of students working in groups, and student interviews. Sources of inspiration for students' problems and questions included cultural beliefs and folklore; wonderment about information propagated by advertisements and the media; curiosity arising from personal encounters, family members' concerns, or observations of others; and issues arising from previous lessons in the school curriculum. Questions asked individually pertained to validation of common beliefs and misconceptions, basic information, explanations, and imagined scenarios. The findings regarding questions asked collaboratively are presented as two assertions. Assertion 1 maintained that students' course of learning were driven by their questions. Assertion 2 was that the ability to ask the right'' questions and the extent to which these could be answered, were important in sustaining students' interest in the project. Implications of the findings for instructional practice are discussed.

Several cases of work-related allergic contact dermatitis caused by isocyanates at a company manufacturing heat exchangers.

PubMed

Engfeldt, Malin; Isaksson, Marléne; Zimerson, Erik; Bruze, Magnus

2013-03-01

A 43-year-old woman was referred by her occupational health service with suspected occupational contact dermatitis. In connection with the investigation, a workplace visit was undertaken at her company, which used an adhesive based on pre-polymeric diphenylmethane diisocyanate in one of its units. During the visit, we became aware of six other employees with skin problems who were then referred to our department for investigation. To investigate the seven employees complaining about skin problems. Seven employees were patch tested with a baseline series, an isocyanate series, and a series with work material. Five of seven patients had occupational contact allergy. Four reacted to isocyanate-related test preparations, and one to a cleanser used at the workplace. Workplace visits constitute an important part of an occupational investigation, as they might give a broader picture of the problems at a company. In this case, it was found that 5 of 100 employees currently had or had previously had occupation-related skin problems. Owing to 'healthy worker selection', some of these patients might have been missed if we had not performed a full-scale workplace visit. © 2012 John Wiley & Sons A/S.

Student perception about working in rural United States/Canada after graduation: a study in an offshore Caribbean medical school.

PubMed

Shankar, P Ravi; Dubey, Arun K; Nandy, Atanu; Herz, Burton L; Little, Brian W

2014-01-01

Rural residents of the United States (US) and Canada face problems in accessing healthcare. International medical graduates (IMGs) play an important role in delivering rural healthcare. IMGs from Caribbean medical schools have the highest proportion of physicians in primary care.  Xavier University School of Medicines admits students from the US, Canada and other countries to the undergraduate medical (MD) course and also offers a premedical program. The present study was conducted to obtain student perception about working in rural US/Canada after graduation.   The study was conducted among premedical and preclinical undergraduate medical (MD) students during October 2014. The questionnaire used was modified from a previous study. Semester of study, gender, nationality, place of residence and occupation of parents were noted. Information about whether students plan to work in rural US/Canada after graduation, possible reasons why doctors are reluctant to work in rural areas, how the government can encourage rural practice, possible problems respondents anticipate while working in rural areas were among the topics studied. Ninety nine of the 108 students (91.7%) participated. Forty respondents were in favor of working in rural US/Canada after graduation. Respondents mentioned good housing, regular electricity, water supply, telecommunication facilities, and schools for education of children as important conditions to be fulfilled. The government should provide higher salaries to rural doctors, help with loan repayment, and provide opportunities for professional growth.  Potential problems mentioned were difficulty in being accepted by the rural community, problems in convincing patients to follow medical advice, lack of exposure to rural life among the respondents, and cultural issues. About 40% of respondents would consider working in rural US/Canada. Conditions required to be fulfilled have been mentioned above. Graduates from Caribbean medical schools have a role in addressing rural physician shortage. Similar studies in other offshore Caribbean medical schools are required as Caribbean IMGs make an important contribution to the rural US and Canadian health workforce.

Education and disability pension: a stronger association than previously found.

PubMed

Bruusgaard, Dag; Smeby, Lisbeth; Claussen, Bjørgulf

2010-11-01

Although the Norwegian Welfare Law includes rigorous medical criteria for granting disability pensions, several non-medical factors have been shown to be associated with and possible causal factors of pensioning. We analysed the relationship between disability pension and detailed information on educational attainment in different diagnostic groups. All ethnic Norwegians aged 18-66 years and alive on 31 December 2003 (n = 2,522,430) were included. Age, sex, the receipt of a disability pension on 31 December 2003, and the diagnosis on the medical certificate were taken from a national social security file. The file also included six levels of education: primary school, low-level secondary school, secondary school, low-level university, university, and research level. We found a dramatic increase in the prevalence of persons granted disability pension with decreasing years of education across all levels of education. The disparities were much stronger than those seen for other health-related parameters and were especially strong for those with musculoskeletal diagnoses. The disability pension is more a consequence of health problems than a proxy for health status. The demonstrated relationship between education and disability pension may be partly explained by exclusion from the work force because of health-related work problems. To facilitate a more inclusive working life, attention should be focused on the work place's capacity to include people with different levels of competence and functioning rather than on the health problems of the employees.

Visuo–spatial working memory is an important source of domain-general vulnerability in the development of arithmetic cognition

PubMed Central

Ashkenazi, Sarit; Rosenberg-Lee, Miriam; Metcalfe, Arron W.S.; Swigart, Anna G.; Menon, Vinod

2014-01-01

The study of developmental disorders can provide a unique window into the role of domain-general cognitive abilities and neural systems in typical and atypical development. Mathematical disabilities (MD) are characterized by marked difficulty in mathematical cognition in the presence of preserved intelligence and verbal ability. Although studies of MD have most often focused on the role of core deficits in numerical processing, domain-general cognitive abilities, in particular working memory (WM), have also been implicated. Here we identify specific WM components that are impaired in children with MD and then examine their role in arithmetic problem solving. Compared to typically developing (TD) children, the MD group demonstrated lower arithmetic performance and lower visuo-spatial working memory (VSWM) scores with preserved abilities on the phonological and central executive components of WM. Whole brain analysis revealed that, during arithmetic problem solving, left posterior parietal cortex, bilateral dorsolateral and ventrolateral prefrontal cortex, cingulate gyrus and precuneus, and fusiform gyrus responses were positively correlated with VSWM ability in TD children, but not in the MD group. Additional analyses using a priori posterior parietal cortex regions previously implicated in WM tasks, demonstrated a convergent pattern of results during arithmetic problem solving. These results suggest that MD is characterized by a common locus of arithmetic and VSWM deficits at both the cognitive and functional neuroanatomical levels. Unlike TD children, children with MD do not use VSWM resources appropriately during arithmetic problem solving. This work advances our understanding of VSWM as an important domain-general cognitive process in both typical and atypical mathematical skill development. PMID:23896444

Interrupted: The roles of distributed effort and incubation in preventing fixation and generating problem solutions.

PubMed

Sio, Ut Na; Kotovsky, Kenneth; Cagan, Jonathan

2017-05-01

Fixation on inappropriate concepts is a key barrier to problem solving. Previous research has shown that continuous work is likely to cause repeated retrieval of those concepts, resulting in increased fixation. Accordingly, distributing effort across problems through multiple, brief, and interlaced sessions (distributed effort) should prevent such fixation and in turn enhance problem solving. This study examined whether distributed effort can provide an advantage for problem solving, particularly for problems that can induce fixation (Experiment 1), and whether and how incubation can be combined with distributed effort to further enhance performance (Experiment 2). Remote Associates Test (RAT) problems were used as the problem-solving tasks. Half of them (i.e., misleading RAT) were more likely to mislead individuals to fixate on incorrect associates than the other half. Experiments revealed a superiority of distributed over massed effort on misleading RAT performance and a differing time course of incubation for the massed and distributed groups. We conclude that distributed effort facilitates problem solving, most likely via overcoming fixation. Cognitive mechanisms other than the commonly posited forgetting of inappropriate ideas may occur during incubation to facilitate problem solving. The experiments in this article offer support for the occurrence of spreading activation during incubation.

The Extrapolation of Elementary Sequences

NASA Technical Reports Server (NTRS)

Laird, Philip; Saul, Ronald

1992-01-01

We study sequence extrapolation as a stream-learning problem. Input examples are a stream of data elements of the same type (integers, strings, etc.), and the problem is to construct a hypothesis that both explains the observed sequence of examples and extrapolates the rest of the stream. A primary objective -- and one that distinguishes this work from previous extrapolation algorithms -- is that the same algorithm be able to extrapolate sequences over a variety of different types, including integers, strings, and trees. We define a generous family of constructive data types, and define as our learning bias a stream language called elementary stream descriptions. We then give an algorithm that extrapolates elementary descriptions over constructive datatypes and prove that it learns correctly. For freely-generated types, we prove a polynomial time bound on descriptions of bounded complexity. An especially interesting feature of this work is the ability to provide quantitative measures of confidence in competing hypotheses, using a Bayesian model of prediction.

Control theory based airfoil design using the Euler equations

NASA Technical Reports Server (NTRS)

Jameson, Antony; Reuther, James

1994-01-01

This paper describes the implementation of optimization techniques based on control theory for airfoil design. In our previous work it was shown that control theory could be employed to devise effective optimization procedures for two-dimensional profiles by using the potential flow equation with either a conformal mapping or a general coordinate system. The goal of our present work is to extend the development to treat the Euler equations in two-dimensions by procedures that can readily be generalized to treat complex shapes in three-dimensions. Therefore, we have developed methods which can address airfoil design through either an analytic mapping or an arbitrary grid perturbation method applied to a finite volume discretization of the Euler equations. Here the control law serves to provide computationally inexpensive gradient information to a standard numerical optimization method. Results are presented for both the inverse problem and drag minimization problem.

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

Needham, D.; Spearman, A.

This paper describes the design and development of a modular gas control installation which is completely buried, except for a small instrument housing and vent pipe. Buried installations controlling gas pressure have many advantages:- no unsightly or costly housings, protection from damage by vehicles or vandals, no problems of acquisition of sites in built-up areas, no need to divert mains to alternative locations, reduced noise, and easier planning permission associated with environmental aspects. It had not previously been possible to realise these advantages with conventional equipment but a novel concept has emerged which solves the problems and provides additional benefits.more » All the working components of a single stream governor station are installed under a 600mm diameter surface access cover. The essential control elements are contained in a lightweight cartridge which can be exchanged in about 15 minutes by two men working from ground level.« less

Adding Support to the ALMA Common Software for Real-Time Operations through the Usage of a POSIX-Compliant RTOS

NASA Astrophysics Data System (ADS)

Tobar, R. J.; von Brand, H.; Araya, M. A.; Juerges, T.

2010-12-01

The ALMA Common Software (ACS) framework lacks of the real-time capabilities to control the antennas’ instrumentation — as has been probed by previous works — which has lead to non-portable workarounds to the problem. Indeed, the time service used in ACS, based in the Container/Component model, presents plenty of results that confirm this statement. This work addresses the problem of design and integrate a real-time service for ACS, providing to the framework an implementation such that the control operations over the different instruments could be done within real-time constraints. This implementation is compared with the current time service, showing the difference between the two systems when subjecting them to common scenarios. Also, the new implementation is done following the POSIX specification, ensuring interoperability and portability through different operating systems.

Supervisory control based on minimal cuts and Petri net sub-controllers coordination

NASA Astrophysics Data System (ADS)

Rezig, Sadok; Achour, Zied; Rezg, Nidhal; Kammoun, Mohamed-Ali

2016-10-01

This paper addresses the synthesis of Petri net (PN) controller for the forbidden state transition problem with a new utilisation of the theory of regions. Moreover, as any method of control synthesis based on a reachability graph, the theory of regions suffers from the combinatorial explosion problem. The proposed work minimises the number of equations in the linear system of theory of regions and therefore one can reduce the computation time. In this paper, two different approaches are proposed to select minimal cuts in the reachability graph in order to synthesise a PN controller. Thanks to a switch from one cut to another, one can activate and deactivate the corresponding PNcontroller. An application is implemented in a flexible manufacturing system to illustrate the present method. Finally, comparison with previous works with experimental results in obtaining a maximally permissive controller is presented.

[On machines and instruments (II): the world in the eye of the work of E. T. A. Hoffmann].

PubMed

Montiel, L

2008-01-01

Continuing with the subject of the previous work, this article considers the whole series of problems connected to the question of vision provoked by the mere existence of the body of the automaton. The eyes of the android and, above all, the reactions aroused by looking at these human-shaped machines are the object of Hoffman's reflections, from a viewpoint apparently firmly set within the Goethean concept of the - Welt des Auges. Similarly, there is as it had been perceived in science since the seventeenth century.

Marangoni flow in an evaporating water droplet

NASA Astrophysics Data System (ADS)

Xu, Xuefeng; Luo, Jianbin

2007-09-01

Marangoni effect has been observed in many liquids, but its existence in pure water is still a debated problem. In the present work, the Marangoni flow in evaporating water droplets has been observed by using fluorescent nanoparticles. Flow patterns indicate that a stagnation point where the surface flow, the surface tension gradient, and the surface temperature gradient change their directions exists at the droplet surface. The deduced nonmonotonic variation of the droplet surface temperature, which is different from that in some previous works, is explained by a heat transfer model considering the adsorbed thin film of the evaporating liquid droplet.

Modelling giant radio halos. Doctoral Thesis Award Lecture 2012

NASA Astrophysics Data System (ADS)

Donnert, J. M. F.

2013-06-01

We review models for giant radio halos in clusters of galaxies, with a focus on numerical and theoretical work. After summarising the most important observations of these objects, we present an introduction to the theoretical aspects of hadronic models. We compare these models with observations using simulations and find severe problems for hadronic models. We give a short introduction to reacceleration models and show results from the first simulation of CRe reacceleration in cluster mergers. We find that in-line with previous theoretical work, reacceleration models are able to elegantly explain main observables of giant radio halos.

[Neuroplasticity as a basis for early rehabilitation of stroke patients].

PubMed

Putilina, M V

2011-01-01

The review is devoted to the current state of the problem of early rehabilitation of stroke patients. The rate of primary disability in patients after stroke is 3.2 per 10000 population but only 20% of previously working patients return to work. Early rehabilitation is treatment actions during a period following stroke. Adequate treatment during this period may decrease the extent of brain damage and improve disease outcome. The complexity of rehabilitation consists in using several complementary pharmacological and non-pharmacological rehabilitation measures. Appearance of new techniques of rehabilitation treatment aimed at neuroplasticity stimulation increases treatment potential of rehabilitative technologies.

Code Modernization of VPIC

NASA Astrophysics Data System (ADS)

Bird, Robert; Nystrom, David; Albright, Brian

2017-10-01

The ability of scientific simulations to effectively deliver performant computation is increasingly being challenged by successive generations of high-performance computing architectures. Code development to support efficient computation on these modern architectures is both expensive, and highly complex; if it is approached without due care, it may also not be directly transferable between subsequent hardware generations. Previous works have discussed techniques to support the process of adapting a legacy code for modern hardware generations, but despite the breakthroughs in the areas of mini-app development, portable-performance, and cache oblivious algorithms the problem still remains largely unsolved. In this work we demonstrate how a focus on platform agnostic modern code-development can be applied to Particle-in-Cell (PIC) simulations to facilitate effective scientific delivery. This work builds directly on our previous work optimizing VPIC, in which we replaced intrinsic based vectorisation with compile generated auto-vectorization to improve the performance and portability of VPIC. In this work we present the use of a specialized SIMD queue for processing some particle operations, and also preview a GPU capable OpenMP variant of VPIC. Finally we include a lessons learnt. Work performed under the auspices of the U.S. Dept. of Energy by the Los Alamos National Security, LLC Los Alamos National Laboratory under contract DE-AC52-06NA25396 and supported by the LANL LDRD program.

Finding text in color images

NASA Astrophysics Data System (ADS)

Zhou, Jiangying; Lopresti, Daniel P.; Tasdizen, Tolga

1998-04-01

In this paper, we consider the problem of locating and extracting text from WWW images. A previous algorithm based on color clustering and connected components analysis works well as long as the color of each character is relatively uniform and the typography is fairly simple. It breaks down quickly, however, when these assumptions are violated. In this paper, we describe more robust techniques for dealing with this challenging problem. We present an improved color clustering algorithm that measures similarity based on both RGB and spatial proximity. Layout analysis is also incorporated to handle more complex typography. THese changes significantly enhance the performance of our text detection procedure.

Comparison of Low-Energy Lunar Transfer Trajectories to Invariant Manifolds

NASA Technical Reports Server (NTRS)

Anderson, Rodney L.; Parker, Jeffrey S.

2011-01-01

In this study, transfer trajectories from the Earth to the Moon that encounter the Moon at various flight path angles are examined, and lunar approach trajectories are compared to the invariant manifolds of selected unstable orbits in the circular restricted three-body problem. Previous work focused on lunar impact and landing trajectories encountering the Moon normal to the surface, and this research extends the problem with different flight path angles in three dimensions. The lunar landing geometry for a range of Jacobi constants are computed, and approaches to the Moon via invariant manifolds from unstable orbits are analyzed for different energy levels.

Teen magazines as educational texts on dating violence: the $2.99 approach.

PubMed

Kettrey, Heather Hensman; Emery, Beth C

2010-11-01

This study analyzed the portrayal of dating violence in teen magazines published in the United States. Such an investigation is important because previous research indicates that dating violence is a serious problem facing adolescents, teen magazines overemphasize the importance of romantic relationships, and teens who read this genre frequently or for education/advice are especially susceptible to its messages. Results indicated that although teen magazines do frame dating violence as a cultural problem, they are much more likely to utilize an individual frame that emphasizes the victim. Results were discussed as they apply to the responsibilities of professionals working with adolescents.

Video auto stitching in multicamera surveillance system

NASA Astrophysics Data System (ADS)

He, Bin; Zhao, Gang; Liu, Qifang; Li, Yangyang

2012-01-01

This paper concerns the problem of video stitching automatically in a multi-camera surveillance system. Previous approaches have used multiple calibrated cameras for video mosaic in large scale monitoring application. In this work, we formulate video stitching as a multi-image registration and blending problem, and not all cameras are needed to be calibrated except a few selected master cameras. SURF is used to find matched pairs of image key points from different cameras, and then camera pose is estimated and refined. Homography matrix is employed to calculate overlapping pixels and finally implement boundary resample algorithm to blend images. The result of simulation demonstrates the efficiency of our method.

Video auto stitching in multicamera surveillance system

NASA Astrophysics Data System (ADS)

He, Bin; Zhao, Gang; Liu, Qifang; Li, Yangyang

2011-12-01

This paper concerns the problem of video stitching automatically in a multi-camera surveillance system. Previous approaches have used multiple calibrated cameras for video mosaic in large scale monitoring application. In this work, we formulate video stitching as a multi-image registration and blending problem, and not all cameras are needed to be calibrated except a few selected master cameras. SURF is used to find matched pairs of image key points from different cameras, and then camera pose is estimated and refined. Homography matrix is employed to calculate overlapping pixels and finally implement boundary resample algorithm to blend images. The result of simulation demonstrates the efficiency of our method.

Improved dynamic MRI reconstruction by exploiting sparsity and rank-deficiency.

PubMed

Majumdar, Angshul

2013-06-01

In this paper we address the problem of dynamic MRI reconstruction from partially sampled K-space data. Our work is motivated by previous studies in this area that proposed exploiting the spatiotemporal correlation of the dynamic MRI sequence by posing the reconstruction problem as a least squares minimization regularized by sparsity and low-rank penalties. Ideally the sparsity and low-rank penalties should be represented by the l(0)-norm and the rank of a matrix; however both are NP hard penalties. The previous studies used the convex l(1)-norm as a surrogate for the l(0)-norm and the non-convex Schatten-q norm (0

Sitnikov cyclic configuration of N+1-body problem

NASA Astrophysics Data System (ADS)

Shahbaz Ullah, M.; Hassan, M. R.

2014-12-01

This manuscript deals with the generalisation of all previous works on series solutions and linear stability of equilibrium points of the Sitnikov problem. Following Giacaglia (1967), in Sect. 2 we have derived the equation of motion of the infinitesimal mass moving along the z-axis about which the plane of motion is rotating with unit angular velocity. In Sects. 3, 4 and 5 the series solutions of the Sitnikov problem have been developed by the method of MacMillan, Lindstedt-Poincaré and iteration of Green's function respectively. In Sect. 6 the three series solutions have been compared graphically by putting N=2, 3, 4. In Sect. 7 the coordinates of equilibrium points have been calculated. In Sect. 8 the linear stability of equilibrium points has been examined by the method of Murray and Dermott (Solar System Dynamics, Cambridge University Press, Cambridge, 1999) and it was found that the equilibrium points are stable in Sitnikov problem.

Identification of the heat transfer coefficient in the two-dimensional model of binary alloy solidification

NASA Astrophysics Data System (ADS)

Hetmaniok, Edyta; Hristov, Jordan; Słota, Damian; Zielonka, Adam

2017-05-01

The paper presents the procedure for solving the inverse problem for the binary alloy solidification in a two-dimensional space. This is a continuation of some previous works of the authors investigating a similar problem but in the one-dimensional domain. Goal of the problem consists in identification of the heat transfer coefficient on boundary of the region and in reconstruction of the temperature distribution inside the considered region in case when the temperature measurements in selected points of the alloy are known. Mathematical model of the problem is based on the heat conduction equation with the substitute thermal capacity and with the liquidus and solidus temperatures varying in dependance on the concentration of the alloy component. For describing this concentration the Scheil model is used. Investigated procedure involves also the parallelized Ant Colony Optimization algorithm applied for minimizing a functional expressing the error of approximate solution.

Geometry Helps to Compare Persistence Diagrams

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

Kerber, Michael; Morozov, Dmitriy; Nigmetov, Arnur

2015-11-16

Exploiting geometric structure to improve the asymptotic complexity of discrete assignment problems is a well-studied subject. In contrast, the practical advantages of using geometry for such problems have not been explored. We implement geometric variants of the Hopcroft--Karp algorithm for bottleneck matching (based on previous work by Efrat el al.), and of the auction algorithm by Bertsekas for Wasserstein distance computation. Both implementations use k-d trees to replace a linear scan with a geometric proximity query. Our interest in this problem stems from the desire to compute distances between persistence diagrams, a problem that comes up frequently in topological datamore » analysis. We show that our geometric matching algorithms lead to a substantial performance gain, both in running time and in memory consumption, over their purely combinatorial counterparts. Moreover, our implementation significantly outperforms the only other implementation available for comparing persistence diagrams.« less

Direct application of Padé approximant for solving nonlinear differential equations.

PubMed

Vazquez-Leal, Hector; Benhammouda, Brahim; Filobello-Nino, Uriel; Sarmiento-Reyes, Arturo; Jimenez-Fernandez, Victor Manuel; Garcia-Gervacio, Jose Luis; Huerta-Chua, Jesus; Morales-Mendoza, Luis Javier; Gonzalez-Lee, Mario

2014-01-01

This work presents a direct procedure to apply Padé method to find approximate solutions for nonlinear differential equations. Moreover, we present some cases study showing the strength of the method to generate highly accurate rational approximate solutions compared to other semi-analytical methods. The type of tested nonlinear equations are: a highly nonlinear boundary value problem, a differential-algebraic oscillator problem, and an asymptotic problem. The high accurate handy approximations obtained by the direct application of Padé method shows the high potential if the proposed scheme to approximate a wide variety of problems. What is more, the direct application of the Padé approximant aids to avoid the previous application of an approximative method like Taylor series method, homotopy perturbation method, Adomian Decomposition method, homotopy analysis method, variational iteration method, among others, as tools to obtain a power series solutions to post-treat with the Padé approximant. 34L30.

Others' anger makes people work harder not smarter: the effect of observing anger and sarcasm on creative and analytic thinking.

PubMed

Miron-Spektor, Ella; Efrat-Treister, Dorit; Rafaeli, Anat; Schwarz-Cohen, Orit

2011-09-01

The authors examine whether and how observing anger influences thinking processes and problem-solving ability. In 3 studies, the authors show that participants who listened to an angry customer were more successful in solving analytic problems, but less successful in solving creative problems compared with participants who listened to an emotionally neutral customer. In Studies 2 and 3, the authors further show that observing anger communicated through sarcasm enhances complex thinking and solving of creative problems. Prevention orientation is argued to be the latent variable that mediated the effect of observing anger on complex thinking. The present findings help reconcile inconsistent findings in previous research, promote theory about the effects of observing anger and sarcasm, and contribute to understanding the effects of anger in the workplace. PsycINFO Database Record (c) 2011 APA, all rights reserved

Mining connected global and local dense subgraphs for bigdata

NASA Astrophysics Data System (ADS)

Wu, Bo; Shen, Haiying

2016-01-01

The problem of discovering connected dense subgraphs of natural graphs is important in data analysis. Discovering dense subgraphs that do not contain denser subgraphs or are not contained in denser subgraphs (called significant dense subgraphs) is also critical for wide-ranging applications. In spite of many works on discovering dense subgraphs, there are no algorithms that can guarantee the connectivity of the returned subgraphs or discover significant dense subgraphs. Hence, in this paper, we define two subgraph discovery problems to discover connected and significant dense subgraphs, propose polynomial-time algorithms and theoretically prove their validity. We also propose an algorithm to further improve the time and space efficiency of our basic algorithm for discovering significant dense subgraphs in big data by taking advantage of the unique features of large natural graphs. In the experiments, we use massive natural graphs to evaluate our algorithms in comparison with previous algorithms. The experimental results show the effectiveness of our algorithms for the two problems and their efficiency. This work is also the first that reveals the physical significance of significant dense subgraphs in natural graphs from different domains.

Peer-led instruction for a qualifying exam preparatory course or: How I learned to stop worrying and love the PhD Qualifying Exam

NASA Astrophysics Data System (ADS)

Christensen, Warren; Engelhardt, Larry

2006-04-01

In the spring of 2004, the authors were charged with the task of creating and administering a qualifying exam preparation curriculum that would strive to assist graduate students studying for their comprehensive physics exam. We incorporated many pedagogical techniques that have been proven effective at nearly all levels of instruction by leading researchers in the field of physics education. Our primary focus was on peer-led instruction and time-on-task doing actual problems from previous qualifying exams. After a brief but precise lecture covering essential ideas over a particular subject matter, students spend most of class time working in small groups and presenting worked problems at the board. At all times, the focus was on student explanations concerning the fundamental concepts behind a specific problem, as well as contemplating variations to broaden understanding and challenge students to think on their feet. We found that students who attended and participated regularly in class could be correlated with those students who achieved high marks on the exam.

Evaluation of questionnaire-based information on previous physical work loads. Stockholm MUSIC 1 Study Group. Musculoskeletal Intervention Center.

PubMed

Torgén, M; Winkel, J; Alfredsson, L; Kilbom, A

1999-06-01

The principal aim of the present study was to evaluate questionnaire-based information on past physical work loads (6-year recall). Effects of memory difficulties on reproducibility were evaluated for 82 subjects by comparing previously reported results on current work loads (test-retest procedure) with the same items recalled 6 years later. Validity was assessed by comparing self-reports in 1995, regarding work loads in 1989, with worksite measurements performed in 1989. Six-year reproducibility, calculated as weighted kappa coefficients (k(w)), varied between 0.36 and 0.86, with the highest values for proportion of the workday spent sitting and for perceived general exertion and the lowest values for trunk and neck flexion. The six-year reproducibility results were similar to previously reported test-retest results for these items; this finding indicates that memory difficulties was a minor problem. The validity of the questionnaire responses, expressed as rank correlations (r(s)) between the questionnaire responses and workplace measurements, varied between -0.16 and 0.78. The highest values were obtained for the items sitting and repetitive work, and the lowest and "unacceptable" values were for head rotation and neck flexion. Misclassification of exposure did not appear to be differential with regard to musculoskeletal symptom status, as judged by the calculated risk estimates. The validity of some of these self-administered questionnaire items appears sufficient for a crude assessment of physical work loads in the past in epidemiologic studies of the general population with predominantly low levels of exposure.

On similarity solutions of a boundary layer problem with an upstream moving wall

NASA Technical Reports Server (NTRS)

Hussaini, M. Y.; Lakin, W. D.; Nachman, A.

1986-01-01

The problem of a boundary layer on a flat plate which has a constant velocity opposite in direction to that of the uniform mainstream is examined. It was previously shown that the solution of this boundary value problem is crucially dependent on the parameter which is the ratio of the velocity of the plate to the velocity of the free stream. In particular, it was proved that a solution exists only if this parameter does not exceed a certain critical value, and numerical evidence was adduced to show that this solution is nonunique. Using Crocco formulation the present work proves this nonuniqueness. Also considered are the analyticity of solutions and the derivation of upper bounds on the critical value of wall velocity parameter.

Experimental evaluation of certification trails using abstract data type validation

NASA Technical Reports Server (NTRS)

Wilson, Dwight S.; Sullivan, Gregory F.; Masson, Gerald M.

1993-01-01

Certification trails are a recently introduced and promising approach to fault-detection and fault-tolerance. Recent experimental work reveals many cases in which a certification-trail approach allows for significantly faster program execution time than a basic time-redundancy approach. Algorithms for answer-validation of abstract data types allow a certification trail approach to be used for a wide variety of problems. An attempt to assess the performance of algorithms utilizing certification trails on abstract data types is reported. Specifically, this method was applied to the following problems: heapsort, Hullman tree, shortest path, and skyline. Previous results used certification trails specific to a particular problem and implementation. The approach allows certification trails to be localized to 'data structure modules,' making the use of this technique transparent to the user of such modules.

Sexual and romantic jealousy in heterosexual and homosexual adults.

PubMed

Harris, Christine R

2002-01-01

Several theorists have claimed that men are innately more upset by a mate's sexual infidelity and women are more upset by a mate's emotional infidelity because the sexes faced different adaptive problems (for men, cuckoldry; for women, losing a mate's resources). The present work examined this theory of jealousy as a specific innate module in 196 adult men and women of homosexual and heterosexual orientations. As in previous work, heterosexuals' responses to a forced-choice question about hypothetical infidelity yielded a gender difference. However no gender differences were found when participants recalled personal experiences with a mate's actual infidelity. Men and women, regardless of sexual orientation, on average focused more on a mate's emotional infidelity than on a mate's sexual infidelity. Responses to hypothetical infidelity were uncorrelated with reactions to actual infidelity. This finding casts doubt on the validity of the hypothetical measures used in previous research.

Psychosocial aspects of working with video display terminals (VDTs) and employee physical and mental health.

PubMed

Smith, M J

1997-10-01

Psychosocial aspects of using video display terminals (VDTs) have been recognized as contributors to employees' mental and physical health problems for more than 15 years. Yet, little has been done by employers to change work organization conditions to improve the psychosocial work environment of VDT users. Thus, psychosocial aspects of work are emerging as one of the biggest problems for VDT users in the late 1990s. This paper explores how psychosocial aspects of VDT work are related to job stress, and their consequences for mental and physical health. Using the research literature, it defines various aspects of work organization and job design that have been shown to be related to VDT users' ill-health. Some of the important work design aspects uncovered include a lack of employee skill use, monotonous tasks, high job demands and work pressure, a lack of control over the job, poor supervisory relations, fear of job loss, and unreliable technology. These are the same job stressors that have been defined as problematic for a variety of blue collar jobs in previous research. Work organization improvements for healthier VDT jobs are proposed. These include organizational support, employee participation, improved task content, increased job control, reasonable production standards, career development, enhanced peer socialization, and improved workstation ergonomics. These organizational improvements are derived from a more detailed organizational strategy for job stress reduction. A model of job redesign through proper 'balancing' of work organization features is discussed.

Tanglegrams: A Reduction Tool for Mathematical Phylogenetics.

PubMed

Matsen, Frederick A; Billey, Sara C; Kas, Arnold; Konvalinka, Matjaz

2018-01-01

Many discrete mathematics problems in phylogenetics are defined in terms of the relative labeling of pairs of leaf-labeled trees. These relative labelings are naturally formalized as tanglegrams, which have previously been an object of study in coevolutionary analysis. Although there has been considerable work on planar drawings of tanglegrams, they have not been fully explored as combinatorial objects until recently. In this paper, we describe how many discrete mathematical questions on trees "factor" through a problem on tanglegrams, and how understanding that factoring can simplify analysis. Depending on the problem, it may be useful to consider a unordered version of tanglegrams, and/or their unrooted counterparts. For all of these definitions, we show how the isomorphism types of tanglegrams can be understood in terms of double cosets of the symmetric group, and we investigate their automorphisms. Understanding tanglegrams better will isolate the distinct problems on leaf-labeled pairs of trees and reveal natural symmetries of spaces associated with such problems.

Dynamic node immunization for restraint of harmful information diffusion in social networks

NASA Astrophysics Data System (ADS)

Yang, Dingda; Liao, Xiangwen; Shen, Huawei; Cheng, Xueqi; Chen, Guolong

2018-08-01

To restrain the spread of harmful information is crucial for the healthy and sustainable development of social networks. We address the problem of restraining the spread of harmful information by immunizing nodes in the networks. Previous works have developed methods based on the network topology or studied how to immunize nodes in the presence of initial infected nodes. These static methods, in which nodes are immunized at once, may have poor performance in the certain situation due to the dynamics of diffusion. To tackle this problem, we introduce a new dynamic immunization problem of immunizing nodes during the process of the diffusion in this paper. We formulate the problem and propose a novel heuristic algorithm by dealing with two sub-problems: (1) how to select a node to achieve the best immunization effect at the present time? (2) whether the selected node should be immunized right now? Finally, we demonstrate the effectiveness of our algorithm through extensive experiments on various real datasets.

Problem-solving variability in older spouses: how is it linked to problem-, person-, and couple-characteristics?

PubMed

Hoppmann, Christiane A; Blanchard-Fields, Fredda

2011-09-01

Problem-solving does not take place in isolation and often involves social others such as spouses. Using repeated daily life assessments from 98 older spouses (M age = 72 years; M marriage length = 42 years), the present study examined theoretical notions from social-contextual models of coping regarding (a) the origins of problem-solving variability and (b) associations between problem-solving and specific problem-, person-, and couple- characteristics. Multilevel models indicate that the lion's share of variability in everyday problem-solving is located at the level of the problem situation. Importantly, participants reported more proactive emotion regulation and collaborative problem-solving for social than nonsocial problems. We also found person-specific consistencies in problem-solving. That is, older spouses high in Neuroticism reported more problems across the study period as well as less instrumental problem-solving and more passive emotion regulation than older spouses low in Neuroticism. Contrary to expectations, relationship satisfaction was unrelated to problem-solving in the present sample. Results are in line with the stress and coping literature in demonstrating that everyday problem-solving is a dynamic process that has to be viewed in the broader context in which it occurs. Our findings also complement previous laboratory-based work on everyday problem-solving by underscoring the benefits of examining everyday problem-solving as it unfolds in spouses' own environment.

A new effective operator for the hybrid algorithm for solving global optimisation problems

NASA Astrophysics Data System (ADS)

Duc, Le Anh; Li, Kenli; Nguyen, Tien Trong; Yen, Vu Minh; Truong, Tung Khac

2018-04-01

Hybrid algorithms have been recently used to solve complex single-objective optimisation problems. The ultimate goal is to find an optimised global solution by using these algorithms. Based on the existing algorithms (HP_CRO, PSO, RCCRO), this study proposes a new hybrid algorithm called MPC (Mean-PSO-CRO), which utilises a new Mean-Search Operator. By employing this new operator, the proposed algorithm improves the search ability on areas of the solution space that the other operators of previous algorithms do not explore. Specifically, the Mean-Search Operator helps find the better solutions in comparison with other algorithms. Moreover, the authors have proposed two parameters for balancing local and global search and between various types of local search, as well. In addition, three versions of this operator, which use different constraints, are introduced. The experimental results on 23 benchmark functions, which are used in previous works, show that our framework can find better optimal or close-to-optimal solutions with faster convergence speed for most of the benchmark functions, especially the high-dimensional functions. Thus, the proposed algorithm is more effective in solving single-objective optimisation problems than the other existing algorithms.

Differences in the association between psychosocial work conditions and physical work load in female- and male-dominated occupations. MUSIC-Norrtälje Study Group.

PubMed

Josephson, M; Pernold, G; Ahlberg-Hultén, G; Härenstam, A; Theorell, T; Vingård, E; Waldenström, M; Hjelm, E W

1999-01-01

This study investigated whether there is a relationship between high physical work load and adverse psychosocial work factors, and whether this relationship is different for women and men. Separate analyses for female registered nurses and assistant nurses were made because these are common occupations involving high physical and psychological demands. This study was part of the MUSIC-Norrtälje study, a population study with the overall aim of identifying risk factors for musculoskeletal disorders. The respondents, 1423 gainfully employed men and women, were randomly selected from the study population. The exposure assessments referred to a typical workday during the previous 12 months. Physical exposure was investigated by interview, psychosocial work factors by interview and questionnaire. For the women, but not the men, mainly routine work and a job strain situation, according to the model of Karasek and Theorell, increased the probability of having a high physical work load, assessed as a time-weighted average of energy expenditure in multiples of the resting metabolic rate. Results indicated that in female-dominated occupations, high physical work load might also imply adverse psychosocial conditions. A higher frequency of high physical work load and job strain was observed among assistant nurses compared with registered nurses. Covariance between physical and psychosocial demands makes it difficult to determine the relative influence of each in health problems. Results of the present study imply that this is a larger problem in studies of women than men.

Efficient Nash Equilibrium Resource Allocation Based on Game Theory Mechanism in Cloud Computing by Using Auction

PubMed Central

Nezarat, Amin; Dastghaibifard, GH

2015-01-01

One of the most complex issues in the cloud computing environment is the problem of resource allocation so that, on one hand, the cloud provider expects the most profitability and, on the other hand, users also expect to have the best resources at their disposal considering the budget constraints and time. In most previous work conducted, heuristic and evolutionary approaches have been used to solve this problem. Nevertheless, since the nature of this environment is based on economic methods, using such methods can decrease response time and reducing the complexity of the problem. In this paper, an auction-based method is proposed which determines the auction winner by applying game theory mechanism and holding a repetitive game with incomplete information in a non-cooperative environment. In this method, users calculate suitable price bid with their objective function during several round and repetitions and send it to the auctioneer; and the auctioneer chooses the winning player based the suggested utility function. In the proposed method, the end point of the game is the Nash equilibrium point where players are no longer inclined to alter their bid for that resource and the final bid also satisfies the auctioneer’s utility function. To prove the response space convexity, the Lagrange method is used and the proposed model is simulated in the cloudsim and the results are compared with previous work. At the end, it is concluded that this method converges to a response in a shorter time, provides the lowest service level agreement violations and the most utility to the provider. PMID:26431035

Efficient Nash Equilibrium Resource Allocation Based on Game Theory Mechanism in Cloud Computing by Using Auction.

PubMed

Nezarat, Amin; Dastghaibifard, G H

2015-01-01

One of the most complex issues in the cloud computing environment is the problem of resource allocation so that, on one hand, the cloud provider expects the most profitability and, on the other hand, users also expect to have the best resources at their disposal considering the budget constraints and time. In most previous work conducted, heuristic and evolutionary approaches have been used to solve this problem. Nevertheless, since the nature of this environment is based on economic methods, using such methods can decrease response time and reducing the complexity of the problem. In this paper, an auction-based method is proposed which determines the auction winner by applying game theory mechanism and holding a repetitive game with incomplete information in a non-cooperative environment. In this method, users calculate suitable price bid with their objective function during several round and repetitions and send it to the auctioneer; and the auctioneer chooses the winning player based the suggested utility function. In the proposed method, the end point of the game is the Nash equilibrium point where players are no longer inclined to alter their bid for that resource and the final bid also satisfies the auctioneer's utility function. To prove the response space convexity, the Lagrange method is used and the proposed model is simulated in the cloudsim and the results are compared with previous work. At the end, it is concluded that this method converges to a response in a shorter time, provides the lowest service level agreement violations and the most utility to the provider.

'Mental health day' sickness absence amongst nurses and midwives: workplace, workforce, psychosocial and health characteristics.

PubMed

Lamont, Scott; Brunero, Scott; Perry, Lin; Duffield, Christine; Sibbritt, David; Gallagher, Robyn; Nicholls, Rachel

2017-05-01

To examine the workforce, workplace, psychosocial and health characteristics of nurses and midwives in relation to their reported use of sickness absence described as 'mental health days'. The occupational stress associated with the nursing profession is increasingly recognized and nurse/midwifery absenteeism is a significant global problem. Taking a 'mental health day' as sickness absence is a common phenomenon in Australian health care. No previous studies have empirically explored the characteristics of nurses and midwives using such sickness absence. Online cross-sectional survey. Survey comprising validated tools and questions on workplace and health characteristics was distributed to nurses and midwives in New South Wales, Australia, between May 2014 - February 2015. Sample characteristics were reported using descriptive statistics. Factors independently predictive of 'mental health day' reportage were determined using logistic regression. Fifty-four percentage of the n = 5041 nurse and midwife respondents took 'mental health days'. Those affected were significantly more likely to be at younger ages, working shifts with less time sitting at work; to report workplace abuse and plans to leave; having been admitted to hospital in previous 12 months; to be current smokers; to report mental health problems, accomplishing less due to emotional problems and current psychotropic medication use. Specific characteristics of nurses and midwives who report taking 'mental health day' sickness absence offer healthcare administrators and managers opportunities for early identification and intervention with workplace measures and support frameworks to promote well-being, health promotion and safety. © 2016 The Authors. Journal of Advanced Nursing Published by John Wiley & Sons Ltd.

Integrated reflector antenna design and analysis

NASA Technical Reports Server (NTRS)

Zimmerman, M. L.; Lee, S. W.; Ni, S.; Christensen, M.; Wang, Y. M.

1993-01-01

Reflector antenna design is a mature field and most aspects were studied. However, of that most previous work is distinguished by the fact that it is narrow in scope, analyzing only a particular problem under certain conditions. Methods of analysis of this type are not useful for working on real-life problems since they can not handle the many and various types of perturbations of basic antenna design. The idea of an integrated design and analysis is proposed. By broadening the scope of the analysis, it becomes possible to deal with the intricacies attendant with modem reflector antenna design problems. The concept of integrated reflector antenna design is put forward. A number of electromagnetic problems related to reflector antenna design are investigated. Some of these show how tools for reflector antenna design are created. In particular, a method for estimating spillover loss for open-ended waveguide feeds is examined. The problem of calculating and optimizing beam efficiency (an important figure of merit in radiometry applications) is also solved. Other chapters deal with applications of this general analysis. The wide angle scan abilities of reflector antennas is examined and a design is proposed for the ATDRSS triband reflector antenna. The development of a general phased-array pattern computation program is discussed and how the concept of integrated design can be extended to other types of antennas is shown. The conclusions are contained in the final chapter.

Exposure to bullying behaviors as a predictor of mental health problems among Norwegian nurses: results from the prospective SUSSH-survey.

PubMed

Reknes, Iselin; Pallesen, Ståle; Magerøy, Nils; Moen, Bente Elisabeth; Bjorvatn, Bjørn; Einarsen, Ståle

2014-03-01

The relationship between workplace bullying and mental health problems are well documented in previous cross-sectional studies, but knowledge on how this relationship develops over time is still scarce. The aim of this study was to explore the prospective relationship between exposure to bullying behaviors at baseline, and increased symptoms of mental health problems (anxiety, depression, fatigue) one year later. Furthermore, the reverse relationship was investigated. This is a prospective longitudinal study, where members of the Norwegian Nurses Organization answered identical questions regarding workplace bullying and mental health problems, at baseline (2008-2009) and follow-up (2010). Altogether, 1582 nurses completed both questionnaires. Hierarchical regression analyses indicated that exposure to bullying behaviors at baseline predicted subsequent increased symptoms of anxiety and fatigue, after adjusting for baseline symptoms of anxiety and fatigue respectively, age, gender, night work and job demands. Moreover, symptoms of anxiety, depression and fatigue at baseline predicted increased exposure to bullying behaviors one year later, after adjusting for exposure to bullying behaviors at baseline, age, gender, night work and job demands. In this study we find support for a reciprocal relationship between exposure to bullying behaviors and symptoms of anxiety and fatigue, respectively. Thus, the results may indicate a vicious circle where workplace bullying and mental health problems mutually affect each other negatively. Copyright © 2013 Elsevier Ltd. All rights reserved.

Optimal Reward Functions in Distributed Reinforcement Learning

NASA Technical Reports Server (NTRS)

Wolpert, David H.; Tumer, Kagan

2000-01-01

We consider the design of multi-agent systems so as to optimize an overall world utility function when (1) those systems lack centralized communication and control, and (2) each agents runs a distinct Reinforcement Learning (RL) algorithm. A crucial issue in such design problems is to initialize/update each agent's private utility function, so as to induce best possible world utility. Traditional 'team game' solutions to this problem sidestep this issue and simply assign to each agent the world utility as its private utility function. In previous work we used the 'Collective Intelligence' framework to derive a better choice of private utility functions, one that results in world utility performance up to orders of magnitude superior to that ensuing from use of the team game utility. In this paper we extend these results. We derive the general class of private utility functions that both are easy for the individual agents to learn and that, if learned well, result in high world utility. We demonstrate experimentally that using these new utility functions can result in significantly improved performance over that of our previously proposed utility, over and above that previous utility's superiority to the conventional team game utility.

Positive couple interactions and daily cortisol: on the stress-protecting role of intimacy.

PubMed

Ditzen, Beate; Hoppmann, Christiane; Klumb, Petra

2008-10-01

To determine whether intimacy might be associated with reduced daily salivary cortisol levels in couples, thereby adding to the epidemiologic literature on reduced health burden in happy couples. A total of 51 dual-earner couples reported time spent on intimacy, stated their current affect quality, and provided saliva samples for cortisol estimation approximately every 3 hours in a 1-week time-sampling assessment. In addition, participants provided data on chronic problems of work organization. Multilevel analyses revealed that intimacy was significantly associated with reduced daily salivary cortisol levels. There was an interaction effect of intimacy with chronic problems of work organization in terms of their relationship with cortisol levels, suggesting a buffering effect of intimacy on work-related elevated cortisol levels. Above this, the association between intimacy and cortisol was mediated by positive affect. Intimacy and affect together explained 7% of daily salivary cortisol variance. Our results are in line with previous studies on the effect of intimacy on cortisol stress responses in the laboratory as well as with epidemiologic data on health beneficial effects of happy marital relationships.

The Eccentric Satellites Problem: Comparing Milky Way Satellite Orbital Properties to Simulation Results

NASA Astrophysics Data System (ADS)

Haji, Umran; Pryor, Carlton; Applebaum, Elaad; Brooks, Alyson

2018-01-01

We compare the orbital properties of the satellite galaxies of the Milky Way to those of satellites found in simulated Milky Way-like systems as a means of testing cosmological simulations of galaxy formation. The particular problem that we are investigating is a discrepancy in the distribution of orbital eccentricities. Previous studies of Milky Way-mass systems analyzed in a semi-analytic ΛCDM cosmological model have found that the satellites tend to have significantly larger fractions of their kinetic energy invested in radial motion with respect to their central galaxy than do the real-world Milky Way satellites. We analyze several high-resolution ("zoom-in") hydrodynamical simulations of Milky Way-mass galaxies and their associated satellite systems to investigate why previous works found Milky Way-like systems to be rare. We find a possible relationship between a quiescent galactic assembly history and a distribution of satellite kinematics resembling that of the Milky Way. This project has been supported by funding from National Science Foundation grant PHY-1560077.

Interactive Land-Use Optimization Using Laguerre Voronoi Diagram with Dynamic Generating Point Allocation

NASA Astrophysics Data System (ADS)

Chaidee, S.; Pakawanwong, P.; Suppakitpaisarn, V.; Teerasawat, P.

2017-09-01

In this work, we devise an efficient method for the land-use optimization problem based on Laguerre Voronoi diagram. Previous Voronoi diagram-based methods are more efficient and more suitable for interactive design than discrete optimization-based method, but, in many cases, their outputs do not satisfy area constraints. To cope with the problem, we propose a force-directed graph drawing algorithm, which automatically allocates generating points of Voronoi diagram to appropriate positions. Then, we construct a Laguerre Voronoi diagram based on these generating points, use linear programs to adjust each cell, and reconstruct the diagram based on the adjustment. We adopt the proposed method to the practical case study of Chiang Mai University's allocated land for a mixed-use complex. For this case study, compared to other Voronoi diagram-based method, we decrease the land allocation error by 62.557 %. Although our computation time is larger than the previous Voronoi-diagram-based method, it is still suitable for interactive design.

Occupational health risks of pathologists - results from a nationwide online questionnaire in Switzerland

PubMed Central

2012-01-01

Background Pathologists are highly trained medical professionals who play an essential part in the diagnosis and therapy planning of malignancies and inflammatory diseases. Their work is associated with potential health hazards including injuries involving infectious human tissue, chemicals which are assumed to be carcinogenic or long periods of microscope and computer work. This study aimed to provide the first comprehensive assessment of the health situation of pathologists in Switzerland. Methods Pathologists in Switzerland were contacted via the Swiss Society of Pathologists and asked to answer an ethically approved, online anonymous questionnaire comprising 48 questions on occupational health problems, workplace characteristics and health behaviour. Results 163 pathologists participated in the study. Forty percent of pathologists reported musculoskeletal problems in the previous month. The overall prevalence was 76%. Almost 90% of pathologists had visual refraction errors, mainly myopia. 83% of pathologists had experienced occupational injuries, mostly cutting injuries, in their professional career; more than one fifth of participants reported cutting injuries in the last year. However, long lasting injuries and infectious diseases were rare. Depression and burnout affected every eighth pathologist. The prevalence of smoking was substantially below that of the general Swiss population. Conclusions The results of this study suggest that more care should be taken in technical and personal protective measures, ergonomic workplace optimisation and reduction of work overload and work inefficiencies. Despite the described health risks, Swiss pathologists were optimistic about their future and their working situation. The high rate of ametropia and psychological problems warrants further study. PMID:23216705

New analytical solutions to the two-phase water faucet problem

DOE PAGES

Zou, Ling; Zhao, Haihua; Zhang, Hongbin

2016-06-17

Here, the one-dimensional water faucet problem is one of the classical benchmark problems originally proposed by Ransom to study the two-fluid two-phase flow model. With certain simplifications, such as massless gas phase and no wall and interfacial frictions, analytical solutions had been previously obtained for the transient liquid velocity and void fraction distribution. The water faucet problem and its analytical solutions have been widely used for the purposes of code assessment, benchmark and numerical verifications. In our previous study, the Ransom’s solutions were used for the mesh convergence study of a high-resolution spatial discretization scheme. It was found that, atmore » the steady state, an anticipated second-order spatial accuracy could not be achieved, when compared to the existing Ransom’s analytical solutions. A further investigation showed that the existing analytical solutions do not actually satisfy the commonly used two-fluid single-pressure two-phase flow equations. In this work, we present a new set of analytical solutions of the water faucet problem at the steady state, considering the gas phase density’s effect on pressure distribution. This new set of analytical solutions are used for mesh convergence studies, from which anticipated second-order of accuracy is achieved for the 2nd order spatial discretization scheme. In addition, extended Ransom’s transient solutions for the gas phase velocity and pressure are derived, with the assumption of decoupled liquid and gas pressures. Numerical verifications on the extended Ransom’s solutions are also presented.« less

[SIMBO: a Screening Instrument for Identification of Work-Related Disabilities--analyses of construct and prognostic validity].

PubMed

Streibelt, M; Gerwinn, H; Hansmeier, T; Thren, K; Müller-Fahrnow, W

2007-10-01

For a number of years, work-related interventions in medical rehabilitation (MBO) have been developed. Basically, these interventions concentrate on vocational problems of rehabilitees whose health disorders are strongly associated with contextual factors of the environment as well as personal factors. Previous studies showed a close relationship between the success of an intervention and identification of a specific demand. In fact there are several clinical concepts regarding specific demand. But there still is a lack of appropriate instruments for use in identification of occupational challenges. Therefore SIMBO (Screening Instrument for Identification of a Demand for Medical-Vocational Oriented Rehabilitation) has been developed recently. By using a scale for the intensity of work-related problems as well as a cut-off point, SIMBO is able to identify patients with and without a demand for work-related interventions. Analyses relative to construct validity and predictive validity were carried out on two different samples--a multi-clinic sample (patients with musculoskeletal disorders) and a sample from the German statutory pension insurance agency DRV Westfalen (successful applications for medical rehabilitation). In this context the cut-off level discussion is very important. By means of the multi-clinic sample--irrespective of cut-off definition--the SIMBO-decision and the clinical identification of MBO-demand were found to agree in 74-78% of the cases. This corresponds to a maximum adjusted correlation of r=0.59 (phi coefficient). Compared to the external ratings of vocational problems given by DRV staff in handling the applications, however, only little agreement is found (64%, r=0.25). In fact, SIMBO had in 77% (r=0.50) of the cases been able to correctly predict work-related problems to be expected. So the result obtained using this instrument is far better than prediction of these problems in the external ratings by DRV staff (54%, r=0,21). Also, return to work (RTW) in good health after six months can be predicted correctly by SIMBO in 77% of the cases. This means that the probability of RTW in good health is reduced by 90% (Odds Ratio=0.1) if work-related problems had been identified by SIMBO. Concerning its clinical as well as predictive quality, the validity of SIMBO-based ratings of work-related problems has been proven. Further, it has become obvious that SIMBO is suitable as an easy-to-handle tool for identification of a need for vocationally-focused interventions for use by the social insurance agencies which finance rehabilitation. Further interesting questions arise relative to application in different indications as well as potential uses as an outcome instrument.

Voice activity and participation profile presenting coordinates for readjustment of preventive action of educators.

PubMed

Dragone, Maria Lúcia Suzigan

2011-01-01

To investigate the perception of voice impairment in professional and social contexts, to correlate these data with existing data in the literature, and to explore the perception of voice problems and the adherence to vocal health programs. 502 Brazilian educators working in municipal public schools responded to the Voice Activity and Participation Profile (VAPP) questionnaire. Then a correlation was made with previous results in the literature dealing with a dysphonic and a nondysphonic group. The VAPP data showed that self-perception of voice problems had a higher vocal impact on daily communication and lower scores for activity limitation and participation restriction. The educators' scores were closer to those of the nondysphonic group with regard to daily and social communication, and emotional and activity limitation, but perception of the voice problem was closest to that of the dysphonic group. Nevertheless, the opposite was the case for participation restriction. The educators perceive vocal problems but do not perceive participation restriction to the same extent. This may explain the decreasing participation in the Vocal Health Program. It probably occurs because adults voluntarily apply for training when they feel that their work performance needs to improve so that they can carry out their job properly. Copyright © 2010 S. Karger AG, Basel.

Factors influencing common diagnoses made during first-opinion small-animal consultations in the United Kingdom.

PubMed

Robinson, N J; Dean, R S; Cobb, M; Brennan, M L

2016-09-01

It is currently unclear how frequently a diagnosis is made during small-animal consultations or how much of a role making a diagnosis plays in veterinary decision-making. Understanding more about the diagnostic process will help direct future research towards areas relevant to practicing veterinary surgeons. The aim of this study was to determine the frequency with which a diagnosis was made, classify the types of diagnosis made (and the factors influencing these) and determine which specific diagnoses were made for health problems discussed during small-animal consultations. Data were gathered during real-time direct observation of small-animal consultations in eight practices in the United Kingdom. Data collected included characteristics of the consultation (e.g. consultation type), patient (e.g. breed), and each problem discussed (e.g. new or pre-existing problem). Each problem discussed was classified into one of the following diagnosis types: definitive; working; presumed; open; previous. A three-level multivariable logistic-regression model was developed, with problem (Level 1) nested within patient (Level 2) nested within consulting veterinary surgeon (Level 3). Problems without a previous diagnosis, in cats and dogs only, were included in the model, which had a binary outcome variable of definitive diagnosis versus no definitive diagnosis. Data were recorded for 1901 animals presented, and data on diagnosis were gathered for 3192 health problems. Previous diagnoses were the most common diagnosis type (n=1116/3192; 35.0%), followed by open (n=868/3192; 27.2%) then definitive (n=660/3192; 20.7%). The variables remaining in the final model were patient age, problem history, consultation type, who raised the problem, and body system affected. New problems, problems in younger animals, and problems raised by the veterinary surgeon were more likely to result in a definitive diagnosis than pre-existing problems, problems in older animals, and problems raised by the owner. The most common diagnoses made were overweight/obese and periodontal disease (both n=210; 6.6%). Definitive diagnoses are rarely made during small-animal consultations, with much of the veterinary caseload involving management of ongoing problems or making decisions around new problems prior to a diagnosis being made. This needs to be taken into account when considering future research priorities, and it may be necessary to conduct research focused on the approach to common clinical presentations, rather than purely on the common diagnoses made. Examining how making a diagnosis affects the actions taken during the consultation may shed further light on the role of diagnosis in the clinical decision-making process. Copyright © 2016 The Authors. Published by Elsevier B.V. All rights reserved.

Image watermarking capacity analysis based on Hopfield neural network

NASA Astrophysics Data System (ADS)

Zhang, Fan; Zhang, Hongbin

2004-11-01

In watermarking schemes, watermarking can be viewed as a form of communication problems. Almost all of previous works on image watermarking capacity are based on information theory, using Shannon formula to calculate the capacity of watermarking. In this paper, we present a blind watermarking algorithm using Hopfield neural network, and analyze watermarking capacity based on neural network. In our watermarking algorithm, watermarking capacity is decided by attraction basin of associative memory.

Functional Analysis of Human NF1 in Drosophila

DTIC Science & Technology

2008-12-01

also have learning problem. Such learning phenotypes have been recapitulated in animal models, including in mouse and Drosophila mutants. This proposal...by examining the phenotypes of mutated human genes expressed in Drosophila NF1 null mutants. We also propose that Gsα/NF1 activated AC pathway...in both Drosophila and mouse NF1 models. Our previous work has shown that defective cAMP signaling leads to the learning phenotype in Drosophila Nf1

Design and Control of Large Collections of Learning Agents

NASA Technical Reports Server (NTRS)

Agogino, Adrian

2001-01-01

The intelligent control of multiple autonomous agents is an important yet difficult task. Previous methods used to address this problem have proved to be either too brittle, too hard to use, or not scalable to large systems. The 'Collective Intelligence' project at NASA/Ames provides an elegant, machine-learning approach to address these problems. This approach mathematically defines some essential properties that a reward system should have to promote coordinated behavior among reinforcement learners. This work has focused on creating additional key properties and algorithms within the mathematics of the Collective Intelligence framework. One of the additions will allow agents to learn more quickly, in a more coordinated manner. The other will let agents learn with less knowledge of their environment. These additions will allow the framework to be applied more easily, to a much larger domain of multi-agent problems.

Extraction of a group-pair relation: problem-solving relation from web-board documents.

PubMed

Pechsiri, Chaveevan; Piriyakul, Rapepun

2016-01-01

This paper aims to extract a group-pair relation as a Problem-Solving relation, for example a DiseaseSymptom-Treatment relation and a CarProblem-Repair relation, between two event-explanation groups, a problem-concept group as a symptom/CarProblem-concept group and a solving-concept group as a treatment-concept/repair concept group from hospital-web-board and car-repair-guru-web-board documents. The Problem-Solving relation (particularly Symptom-Treatment relation) including the graphical representation benefits non-professional persons by supporting knowledge of primarily solving problems. The research contains three problems: how to identify an EDU (an Elementary Discourse Unit, which is a simple sentence) with the event concept of either a problem or a solution; how to determine a problem-concept EDU boundary and a solving-concept EDU boundary as two event-explanation groups, and how to determine the Problem-Solving relation between these two event-explanation groups. Therefore, we apply word co-occurrence to identify a problem-concept EDU and a solving-concept EDU, and machine-learning techniques to solve a problem-concept EDU boundary and a solving-concept EDU boundary. We propose using k-mean and Naïve Bayes to determine the Problem-Solving relation between the two event-explanation groups involved with clustering features. In contrast to previous works, the proposed approach enables group-pair relation extraction with high accuracy.

On the emergence of the structure of physics

NASA Astrophysics Data System (ADS)

Majid, S.

2018-04-01

We consider Hilbert's problem of the axioms of physics at a qualitative or conceptual level. This is more pressing than ever as we seek to understand how both general relativity and quantum theory could emerge from some deeper theory of quantum gravity, and in this regard I have previously proposed a principle of self-duality or quantum Born reciprocity as a key structure. Here, I outline some of my recent work around the idea of quantum space-time as motivated by this non-standard philosophy, including a new toy model of gravity on a space-time consisting of four points forming a square. This article is part of the theme issue `Hilbert's sixth problem'.

On the emergence of the structure of physics.

PubMed

Majid, S

2018-04-28

We consider Hilbert's problem of the axioms of physics at a qualitative or conceptual level. This is more pressing than ever as we seek to understand how both general relativity and quantum theory could emerge from some deeper theory of quantum gravity, and in this regard I have previously proposed a principle of self-duality or quantum Born reciprocity as a key structure. Here, I outline some of my recent work around the idea of quantum space-time as motivated by this non-standard philosophy, including a new toy model of gravity on a space-time consisting of four points forming a square.This article is part of the theme issue 'Hilbert's sixth problem'. © 2018 The Author(s).

Dynamic Control of Plans with Temporal Uncertainty

NASA Technical Reports Server (NTRS)

Morris, Paul; Muscettola, Nicola; Vidal, Thierry

2001-01-01

Certain planning systems that deal with quantitative time constraints have used an underlying Simple Temporal Problem solver to ensure temporal consistency of plans. However, many applications involve processes of uncertain duration whose timing cannot be controlled by the execution agent. These cases require more complex notions of temporal feasibility. In previous work, various "controllability" properties such as Weak, Strong, and Dynamic Controllability have been defined. The most interesting and useful Controllability property, the Dynamic one, has ironically proved to be the most difficult to analyze. In this paper, we resolve the complexity issue for Dynamic Controllability. Unexpectedly, the problem turns out to be tractable. We also show how to efficiently execute networks whose status has been verified.

Automatic detection of wheezes by evaluation of multiple acoustic feature extraction methods and C-weighted SVM

NASA Astrophysics Data System (ADS)

Sosa, Germán. D.; Cruz-Roa, Angel; González, Fabio A.

2015-01-01

This work addresses the problem of lung sound classification, in particular, the problem of distinguishing between wheeze and normal sounds. Wheezing sound detection is an important step to associate lung sounds with an abnormal state of the respiratory system, usually associated with tuberculosis or another chronic obstructive pulmonary diseases (COPD). The paper presents an approach for automatic lung sound classification, which uses different state-of-the-art sound features in combination with a C-weighted support vector machine (SVM) classifier that works better for unbalanced data. Feature extraction methods used here are commonly applied in speech recognition and related problems thanks to the fact that they capture the most informative spectral content from the original signals. The evaluated methods were: Fourier transform (FT), wavelet decomposition using Wavelet Packet Transform bank of filters (WPT) and Mel Frequency Cepstral Coefficients (MFCC). For comparison, we evaluated and contrasted the proposed approach against previous works using different combination of features and/or classifiers. The different methods were evaluated on a set of lung sounds including normal and wheezing sounds. A leave-two-out per-case cross-validation approach was used, which, in each fold, chooses as validation set a couple of cases, one including normal sounds and the other including wheezing sounds. Experimental results were reported in terms of traditional classification performance measures: sensitivity, specificity and balanced accuracy. Our best results using the suggested approach, C-weighted SVM and MFCC, achieve a 82.1% of balanced accuracy obtaining the best result for this problem until now. These results suggest that supervised classifiers based on kernel methods are able to learn better models for this challenging classification problem even using the same feature extraction methods.

Familias 3 - Extensions and new functionality.

PubMed

Kling, Daniel; Tillmar, Andreas O; Egeland, Thore

2014-11-01

In relationship testing the aim is to determine the most probable pedigree structure given genetic marker data for a set of persons. Disaster Victim Identification (DVI) based on DNA data from presumed relatives of the missing persons can be considered to be a collection of relationship problems. Forensic calculations in investigative mode address questions like "How many markers and reference persons are needed?" Such questions can be answered by simulations. Mutations, deviations from Hardy-Weinberg Equilibrium (or more generally, accounting for population substructure) and silent alleles cannot be ignored when evaluating forensic evidence in case work. With the advent of new markers, so called microvariants have become more common. Previous mutation models are no longer appropriate and a new model is proposed. This paper describes methods designed to deal with DVI problems and a new simulation model to study distribution of likelihoods. There are softwares available, addressing similar problems. However, for some problems including DVI, we are not aware of freely available validated software. The Familias software has long been widely used by forensic laboratories worldwide to compute likelihoods in relationship scenarios, though previous versions have lacked desired functionality, such as the above mentioned. The extensions as well as some other novel features have been implemented in the new version, freely available at www.familias.no. The implementation and validation are briefly mentioned leaving complete details to Supplementary sections. Copyright © 2014 Elsevier Ireland Ltd. All rights reserved.

Ensuring critical event sequences in high consequence computer based systems as inspired by path expressions

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

Kidd, M.E.C.

1997-02-01

The goal of our work is to provide a high level of confidence that critical software driven event sequences are maintained in the face of hardware failures, malevolent attacks and harsh or unstable operating environments. This will be accomplished by providing dynamic fault management measures directly to the software developer and to their varied development environments. The methodology employed here is inspired by previous work in path expressions. This paper discusses the perceived problems, a brief overview of path expressions, the proposed methods, and a discussion of the differences between the proposed methods and traditional path expression usage and implementation.

A lung sound classification system based on the rational dilation wavelet transform.

PubMed

Ulukaya, Sezer; Serbes, Gorkem; Sen, Ipek; Kahya, Yasemin P

2016-08-01

In this work, a wavelet based classification system that aims to discriminate crackle, normal and wheeze lung sounds is presented. While the previous works related with this problem use constant low Q-factor wavelets, which have limited frequency resolution and can not cope with oscillatory signals, in the proposed system, the Rational Dilation Wavelet Transform, whose Q-factors can be tuned, is employed. Proposed system yields an accuracy of 95 % for crackle, 97 % for wheeze, 93.50 % for normal and 95.17 % for total sound signal types using energy feature subset and proposed approach is superior to conventional low Q-factor wavelet analysis.

Balancing antagonistic time and resource utilization constraints in over-subscribed scheduling problems

NASA Technical Reports Server (NTRS)

Smith, Stephen F.; Pathak, Dhiraj K.

1991-01-01

In this paper, we report work aimed at applying concepts of constraint-based problem structuring and multi-perspective scheduling to an over-subscribed scheduling problem. Previous research has demonstrated the utility of these concepts as a means for effectively balancing conflicting objectives in constraint-relaxable scheduling problems, and our goal here is to provide evidence of their similar potential in the context of HST observation scheduling. To this end, we define and experimentally assess the performance of two time-bounded heuristic scheduling strategies in balancing the tradeoff between resource setup time minimization and satisfaction of absolute time constraints. The first strategy considered is motivated by dispatch-based manufacturing scheduling research, and employs a problem decomposition that concentrates local search on minimizing resource idle time due to setup activities. The second is motivated by research in opportunistic scheduling and advocates a problem decomposition that focuses attention on the goal activities that have the tightest temporal constraints. Analysis of experimental results gives evidence of differential superiority on the part of each strategy in different problem solving circumstances. A composite strategy based on recognition of characteristics of the current problem solving state is then defined and tested to illustrate the potential benefits of constraint-based problem structuring and multi-perspective scheduling in over-subscribe scheduling problems.

Determinants of Chronic Respiratory Symptoms among Pharmaceutical Factory Workers

PubMed Central

Enquselassie, Fikre; Tefera, Yifokire; Gizaw, Muluken; Wakuma, Samson; Woldemariam, Messay

2018-01-01

Background Chronic respiratory symptoms including chronic cough, chronic phlegm, wheezing, shortness of breath, and chest pain are manifestations of respiratory problems which are mainly evolved as a result of occupational exposures. This study aims to assess determinants of chronic respiratory symptoms among pharmaceutical factory workers. Methods A case control study was carried out among 453 pharmaceutical factory workers with 151 cases and 302 controls. Data was collected using pretested and structured questionnaire. The data was analyzed using descriptive statistics and bivariate and multivariate analysis. Result Previous history of chronic respiratory diseases (AOR = 3.36, 95% CI = 1.85–6.12), family history of chronic respiratory diseases (AOR = 2.55, 95% CI = 1.51–4.32), previous dusty working environment (AOR = 2.26, 95% CI = 1.07–4.78), ever smoking (AOR = 3.66, 95% CI = 1.05–12.72), and service years (AOR = 1.86, 95% CI = 1.16–2.99) showed statistically significant association with chronic respiratory symptoms. Conclusion Previous history of respiratory diseases, family history of chronic respiratory diseases, previous dusty working environment, smoking, and service years were determinants of chronic respiratory symptoms. Public health endeavors to prevent the burden of chronic respiratory symptoms among pharmaceutical factory workers should target the reduction of adverse workplace exposures and discouragement of smoking. PMID:29666655

Impact of the "Like Minds, Like Mine" anti-stigma and discrimination campaign in New Zealand on anticipated and experienced discrimination.

PubMed

Thornicroft, Calum; Wyllie, Allan; Thornicroft, Graham; Mehta, Nisha

2014-04-01

The "Like Minds, Like Mine" anti-stigma and discrimination programme has been running in New Zealand since 1997. We aimed to investigate the nature and degree of anticipated and experienced discrimination reported by people with mental illness, and their views on whether the campaign was contributing to reductions in stigma and discrimination. Questionnaires were sent to randomly selected people who were representative of those who had recently used mental health services in New Zealand. The measure used was the modified Discrimination and Stigma Scale (DISC-12), adding questions on the effect of "Like Minds, Like Mine", and also assessing overall changes in discrimination in the previous 5 years. A total of 1135 participants completed the questionnaire. This included 225 Ma-ori, 196 Pacific, and 152 Asian persons. Over half of all participants reported improvement in discrimination over the previous 5 years, and 48% thought that the "Like Minds Like Mine" programme had assisted in reducing discrimination "moderately" or "a lot". Nevertheless, a clear majority (89%) reported experiencing at least "a little" unfair treatment in the previous 12 months due to their mental health problems. The primary source of both positive and negative discrimination was the family. Many (57%) participants had concealed or hidden their mental health problems from others, and 33% had stopped themselves from applying for work because they anticipated discrimination. Family, friendship, and social life were the most common areas of discrimination reported by the participants; however, many believed the overall level of discrimination had reduced over the previous 5 years. Overall, these results characterize the nature of stigma and discrimination anticipated and experienced by people with mental health problems and indicate modest but clear and positive recent progress in their reduction.

Extensive numerical study of a D-brane, anti-D-brane system in AdS 5 /CFT 4

NASA Astrophysics Data System (ADS)

Hegedűs, Árpád

2015-04-01

In this paper the hybrid-NLIE approach of [38] is extended to the ground state of a D-brane anti-D-brane system in AdS/CFT. The hybrid-NLIE equations presented in the paper are finite component alternatives of the previously proposed TBA equations and they admit an appropriate framework for the numerical investigation of the ground state of the problem. Straightforward numerical iterative methods fail to converge, thus new numerical methods are worked out to solve the equations. Our numerical data confirm the previous TBA data. In view of the numerical results the mysterious L = 1 case is also commented in the paper.

Meshless methods in shape optimization of linear elastic and thermoelastic solids

NASA Astrophysics Data System (ADS)

Bobaru, Florin

This dissertation proposes a meshless approach to problems in shape optimization of elastic and thermoelastic solids. The Element-free Galerkin (EFG) method is used for this purpose. The ability of the EFG to avoid remeshing, that is normally done in a Finite Element approach to correct highly distorted meshes, is clearly demonstrated by several examples. The shape optimization example of a thermal cooling fin shows a dramatic improvement in the objective compared to a previous FEM analysis. More importantly, the new solution, displaying large shape changes contrasted to the initial design, was completely missed by the FEM analysis. The EFG formulation given here for shape optimization "uncovers" new solutions that are, apparently, unobtainable via a FEM approach. This is one of the main achievements of our work. The variational formulations for the analysis problem and for the sensitivity problems are obtained with a penalty method for imposing the displacement boundary conditions. The continuum formulation is general and this facilitates 2D and 3D with minor differences from one another. Also, transient thermoelastic problems can use the present development at each time step to solve shape optimization problems for time-dependent thermal problems. For the elasticity framework, displacement sensitivity is obtained in the EFG context. Excellent agreements with analytical solutions for some test problems are obtained. The shape optimization of a fillet is carried out in great detail, and results show significant improvement of the EFG solution over the FEM or the Boundary Element Method solutions. In our approach we avoid differentiating the complicated EFG shape functions, with respect to the shape design parameters, by using a particular discretization for sensitivity calculations. Displacement and temperature sensitivities are formulated for the shape optimization of a linear thermoelastic solid. Two important examples considered in this work, the optimization of a thermal fin and of a uniformly loaded thermoelastic beam, reveal new characteristics of the EFG method in shape optimization applications. Among other advantages of the EFG method over traditional FEM treatments of shape optimization problems, some of the most important ones are shown to be: elimination of post-processing for stress and strain recovery that directly gives more accurate results in critical positions (near the boundaries, for example) for shape optimization problems; nodes movement flexibility that permits new, better shapes (previously missed by an FEM analysis) to be discovered. Several new research directions that need further consideration are exposed.

Student perception about working in rural United States/Canada after graduation: a study in an offshore Caribbean medical school

PubMed Central

Shankar, P Ravi; Dubey, Arun K; Nandy, Atanu; Herz, Burton L; Little, Brian W

2015-01-01

Introduction: Rural residents of the United States (US) and Canada face problems in accessing healthcare. International medical graduates (IMGs) play an important role in delivering rural healthcare. IMGs from Caribbean medical schools have the highest proportion of physicians in primary care.  Xavier University School of Medicines admits students from the US, Canada and other countries to the undergraduate medical (MD) course and also offers a premedical program. The present study was conducted to obtain student perception about working in rural US/Canada after graduation.   Methods: The study was conducted among premedical and preclinical undergraduate medical (MD) students during October 2014. The questionnaire used was modified from a previous study. Semester of study, gender, nationality, place of residence and occupation of parents were noted. Information about whether students plan to work in rural US/Canada after graduation, possible reasons why doctors are reluctant to work in rural areas, how the government can encourage rural practice, possible problems respondents anticipate while working in rural areas were among the topics studied. Results: Ninety nine of the 108 students (91.7%) participated. Forty respondents were in favor of working in rural US/Canada after graduation. Respondents mentioned good housing, regular electricity, water supply, telecommunication facilities, and schools for education of children as important conditions to be fulfilled. The government should provide higher salaries to rural doctors, help with loan repayment, and provide opportunities for professional growth.  Potential problems mentioned were difficulty in being accepted by the rural community, problems in convincing patients to follow medical advice, lack of exposure to rural life among the respondents, and cultural issues. Conclusions: About 40% of respondents would consider working in rural US/Canada. Conditions required to be fulfilled have been mentioned above. Graduates from Caribbean medical schools have a role in addressing rural physician shortage. Similar studies in other offshore Caribbean medical schools are required as Caribbean IMGs make an important contribution to the rural US and Canadian health workforce. PMID:25901275

Analyzing Quadratic Unconstrained Binary Optimization Problems Via Multicommodity Flows

PubMed Central

Wang, Di; Kleinberg, Robert D.

2009-01-01

Quadratic Unconstrained Binary Optimization (QUBO) problems concern the minimization of quadratic polynomials in n {0, 1}-valued variables. These problems are NP-complete, but prior work has identified a sequence of polynomial-time computable lower bounds on the minimum value, denoted by C2, C3, C4,…. It is known that C2 can be computed by solving a maximum-flow problem, whereas the only previously known algorithms for computing Ck (k > 2) require solving a linear program. In this paper we prove that C3 can be computed by solving a maximum multicommodity flow problem in a graph constructed from the quadratic function. In addition to providing a lower bound on the minimum value of the quadratic function on {0, 1}n, this multicommodity flow problem also provides some information about the coordinates of the point where this minimum is achieved. By looking at the edges that are never saturated in any maximum multicommodity flow, we can identify relational persistencies: pairs of variables that must have the same or different values in any minimizing assignment. We furthermore show that all of these persistencies can be detected by solving single-commodity flow problems in the same network. PMID:20161596

Analyzing Quadratic Unconstrained Binary Optimization Problems Via Multicommodity Flows.

PubMed

Wang, Di; Kleinberg, Robert D

2009-11-28

Quadratic Unconstrained Binary Optimization (QUBO) problems concern the minimization of quadratic polynomials in n {0, 1}-valued variables. These problems are NP-complete, but prior work has identified a sequence of polynomial-time computable lower bounds on the minimum value, denoted by C(2), C(3), C(4),…. It is known that C(2) can be computed by solving a maximum-flow problem, whereas the only previously known algorithms for computing C(k) (k > 2) require solving a linear program. In this paper we prove that C(3) can be computed by solving a maximum multicommodity flow problem in a graph constructed from the quadratic function. In addition to providing a lower bound on the minimum value of the quadratic function on {0, 1}(n), this multicommodity flow problem also provides some information about the coordinates of the point where this minimum is achieved. By looking at the edges that are never saturated in any maximum multicommodity flow, we can identify relational persistencies: pairs of variables that must have the same or different values in any minimizing assignment. We furthermore show that all of these persistencies can be detected by solving single-commodity flow problems in the same network.

Health and safety problems associated with long working hours: a review of the current position.

PubMed Central

Spurgeon, A; Harrington, J M; Cooper, C L

1997-01-01

The European Community Directive on Working Time, which should have been implemented in member states of the European Community by November 1996, contains several requirements related to working hours, including the right of employees to refuse to work more than 48 hours a week. The United Kingdom government attempted to oppose the Directive, arguing that there is no convincing evidence that hours of work should be limited on health and safety grounds. Much of the research in this area has focused on the problems of shiftworking and previous reviews have therefore tended to emphasise this aspect of working hours. However, there is much less information about the effects of overtime work, which is a central element of the terms of the Directive. This paper reviews the current evidence relating to the potential effects on health and performance of extensions to the normal working day. Several gaps in the literature are identified. Research to date has been restricted to a limited range of health outcomes--namely, mental health and cardiovascular disorders. Other potential effects which are normally associated with stress--for example, gastrointestinal disorders, musculoskeletal disorders, and problems associated with depression of the immune system, have received little attention. Also, there have been few systematic investigations of performance effects, and little consideration of the implications for occupational exposure limits of extensions to the working day. Existing data relate largely to situations where working hours exceed 50 a week and there is a lack of information on hours below this level, which is of direct relevance to the European Community proposal. Finally, it is clear from investigations relating to shiftwork that a range of modifying factors are likely to influence the level and nature of health and performance outcomes. These include the attitudes and motivation of the people concerned, the job requirements, and other aspects of the organisational and cultural climate. It is concluded that there is currently sufficient evidence to raise concerns about the risks to health and safety of long working hours. However, much more work is required to define the level and nature of those risks. PMID:9245942

Ensemble Grouping Strategies for Embedded Stochastic Collocation Methods Applied to Anisotropic Diffusion Problems

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

D'Elia, M.; Edwards, H. C.; Hu, J.

Previous work has demonstrated that propagating groups of samples, called ensembles, together through forward simulations can dramatically reduce the aggregate cost of sampling-based uncertainty propagation methods [E. Phipps, M. D'Elia, H. C. Edwards, M. Hoemmen, J. Hu, and S. Rajamanickam, SIAM J. Sci. Comput., 39 (2017), pp. C162--C193]. However, critical to the success of this approach when applied to challenging problems of scientific interest is the grouping of samples into ensembles to minimize the total computational work. For example, the total number of linear solver iterations for ensemble systems may be strongly influenced by which samples form the ensemble whenmore » applying iterative linear solvers to parameterized and stochastic linear systems. In this paper we explore sample grouping strategies for local adaptive stochastic collocation methods applied to PDEs with uncertain input data, in particular canonical anisotropic diffusion problems where the diffusion coefficient is modeled by truncated Karhunen--Loève expansions. Finally, we demonstrate that a measure of the total anisotropy of the diffusion coefficient is a good surrogate for the number of linear solver iterations for each sample and therefore provides a simple and effective metric for grouping samples.« less

Coevolving memetic algorithms: a review and progress report.

PubMed

Smith, Jim E

2007-02-01

Coevolving memetic algorithms are a family of metaheuristic search algorithms in which a rule-based representation of local search (LS) is coadapted alongside candidate solutions within a hybrid evolutionary system. Simple versions of these systems have been shown to outperform other nonadaptive memetic and evolutionary algorithms on a range of problems. This paper presents a rationale for such systems and places them in the context of other recent work on adaptive memetic algorithms. It then proposes a general structure within which a population of LS algorithms can be evolved in tandem with the solutions to which they are applied. Previous research started with a simple self-adaptive system before moving on to more complex models. Results showed that the algorithm was able to discover and exploit certain forms of structure and regularities within the problems. This "metalearning" of problem features provided a means of creating highly scalable algorithms. This work is briefly reviewed to highlight some of the important findings and behaviors exhibited. Based on this analysis, new results are then presented from systems with more flexible representations, which, again, show significant improvements. Finally, the current state of, and future directions for, research in this area is discussed.

Ensemble Grouping Strategies for Embedded Stochastic Collocation Methods Applied to Anisotropic Diffusion Problems

DOE PAGES

D'Elia, M.; Edwards, H. C.; Hu, J.; ...

2018-01-18

Previous work has demonstrated that propagating groups of samples, called ensembles, together through forward simulations can dramatically reduce the aggregate cost of sampling-based uncertainty propagation methods [E. Phipps, M. D'Elia, H. C. Edwards, M. Hoemmen, J. Hu, and S. Rajamanickam, SIAM J. Sci. Comput., 39 (2017), pp. C162--C193]. However, critical to the success of this approach when applied to challenging problems of scientific interest is the grouping of samples into ensembles to minimize the total computational work. For example, the total number of linear solver iterations for ensemble systems may be strongly influenced by which samples form the ensemble whenmore » applying iterative linear solvers to parameterized and stochastic linear systems. In this paper we explore sample grouping strategies for local adaptive stochastic collocation methods applied to PDEs with uncertain input data, in particular canonical anisotropic diffusion problems where the diffusion coefficient is modeled by truncated Karhunen--Loève expansions. Finally, we demonstrate that a measure of the total anisotropy of the diffusion coefficient is a good surrogate for the number of linear solver iterations for each sample and therefore provides a simple and effective metric for grouping samples.« less

Cognitive processes in children's reading and attention: the role of working memory, divided attention, and response inhibition.

PubMed

Savage, Robert; Cornish, Kim; Manly, Tom; Hollis, Chris

2006-08-01

Children experiencing attention difficulties have documented cognitive deficits in working memory (WM), response inhibition and dual tasks. Recent evidence suggests however that these same cognitive processes are also closely associated with reading acquisition. This paper therefore explores whether these variables predicted attention difficulties or reading among 123 children with and without significant attention problems sampled from the school population. Children were screened using current WM and attention task measures. Three factors explained variance in WM and attention tasks. Response inhibition tasks loaded mainly with central executive measures, but a dual processing task loaded with the visual-spatial WM measures. Phonological loop measures loaded independently of attention measures. After controls for age, IQ and attention-group membership, phonological loop and 'central processing' measures both predicted reading ability. A 'visual memory/dual-task' factor predicted attention group membership after controls for age, IQ and reading ability. Results thus suggest that some of the processes previously assumed to be predictive of attention problems may reflect processes involved in reading acquisition. Visual memory and dual-task functioning are, however, purer indices of cognitive difficulty in children experiencing attention problems.

Connecting orbits and invariant manifolds in the spatial restricted three-body problem

NASA Astrophysics Data System (ADS)

Gómez, G.; Koon, W. S.; Lo, M. W.; Marsden, J. E.; Masdemont, J.; Ross, S. D.

2004-09-01

The invariant manifold structures of the collinear libration points for the restricted three-body problem provide the framework for understanding transport phenomena from a geometrical point of view. In particular, the stable and unstable invariant manifold tubes associated with libration point orbits are the phase space conduits transporting material between primary bodies for separate three-body systems. These tubes can be used to construct new spacecraft trajectories, such as a 'Petit Grand Tour' of the moons of Jupiter. Previous work focused on the planar circular restricted three-body problem. This work extends the results to the three-dimensional case. Besides providing a full description of different kinds of libration motions in a large vicinity of these points, this paper numerically demonstrates the existence of heteroclinic connections between pairs of libration orbits, one around the libration point L1 and the other around L2. Since these connections are asymptotic orbits, no manoeuvre is needed to perform the transfer from one libration point orbit to the other. A knowledge of these orbits can be very useful in the design of missions such as the Genesis Discovery Mission, and may provide the backbone for other interesting orbits in the future.

Layout optimization using the homogenization method

NASA Technical Reports Server (NTRS)

Suzuki, Katsuyuki; Kikuchi, Noboru

1993-01-01

A generalized layout problem involving sizing, shape, and topology optimization is solved by using the homogenization method for three-dimensional linearly elastic shell structures in order to seek a possibility of establishment of an integrated design system of automotive car bodies, as an extension of the previous work by Bendsoe and Kikuchi. A formulation of a three-dimensional homogenized shell, a solution algorithm, and several examples of computing the optimum layout are presented in this first part of the two articles.

Sensitivity analysis as an aid in modelling and control of (poorly-defined) ecological systems. [closed ecological systems

NASA Technical Reports Server (NTRS)

Hornberger, G. M.; Rastetter, E. B.

1982-01-01

A literature review of the use of sensitivity analyses in modelling nonlinear, ill-defined systems, such as ecological interactions is presented. Discussions of previous work, and a proposed scheme for generalized sensitivity analysis applicable to ill-defined systems are included. This scheme considers classes of mathematical models, problem-defining behavior, analysis procedures (especially the use of Monte-Carlo methods), sensitivity ranking of parameters, and extension to control system design.

Tomographic Neutron Imaging using SIRT

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

Gregor, Jens; FINNEY, Charles E A; Toops, Todd J

2013-01-01

Neutron imaging is complementary to x-ray imaging in that materials such as water and plastic are highly attenuating while material such as metal is nearly transparent. We showcase tomographic imaging of a diesel particulate filter. Reconstruction is done using a modified version of SIRT called PSIRT. We expand on previous work and introduce Tikhonov regularization. We show that near-optimal relaxation can still be achieved. The algorithmic ideas apply to cone beam x-ray CT and other inverse problems.

Toward a Superior Promotion System

DTIC Science & Technology

2012-08-01

AUTHOR(S) 5d. PROJECT NUMBER 5e. TASK NUMBER 5f. WORK UNIT NUMBER 7. PERFORMING ORGANIZATION NAME(S) AND ADDRESS(ES) Air Force Research Institute (AFRI...Air & Space Power Journal,155 N Twining Street,Maxwell AFB,AL,36112 8. PERFORMING ORGANIZATION REPORT NUMBER 9. SPONSORING/MONITORING AGENCY NAME...this lan­ guage might have arisen to remedy a problem in this or previous evalua­ tion systems and has continued to exist as a vestigial feature. The

The particle problem in classical gravity: a historical note on 1941

NASA Astrophysics Data System (ADS)

Galvagno, Mariano; Giribet, Gastón

2005-11-01

This historical note is mainly based on a relatively unknown paper published by Albert Einstein in Revista de la Universidad Nacional de Tucumán in 1941. Taking the ideas of this work as a leitmotiv, we review the discussions about the particle problem in the theory of gravitation within the historical context by means of the study of seminal works on the subject. The revision shows how the digressions regarding the structure of matter and the concise problem of finding regular solutions of the pure field equations turned out to be intrinsically unified in the beginning of the programme towards a final theory of fields. The paper mentioned (Einstein 1941a Rev. Univ. Nac. Tucumán A 2 11) represents the basis of the one written by Einstein in collaboration with Wolfgang Pauli in 1943, in which, following analogous lines, the proof of the non-existence of regular particle-type solutions was generalized to the case of cylindrical geometries in Kaluza-Klein theory (Einstein and Pauli 1943 Ann. Math. 44 131). Besides, other generalizations were subsequently presented. The (non-)existence of such solutions in classical unified field theory was undoubtedly an important criterion leading Einstein's investigations. This aspect was investigated with expertness by Jeroen van Dongen in a recent work, though restricting the scope to the particular case of Kaluza-Klein theory (van Dongen 2002 Stud. Hist. Phil. Mod. Phys. 33 185). Here, we discuss the particle problem within a more general context, presenting in this way a complement to previous reviews.

Toward an optimal solver for time-spectral fluid-dynamic and aeroelastic solutions on unstructured meshes

NASA Astrophysics Data System (ADS)

Mundis, Nathan L.; Mavriplis, Dimitri J.

2017-09-01

The time-spectral method applied to the Euler and coupled aeroelastic equations theoretically offers significant computational savings for purely periodic problems when compared to standard time-implicit methods. However, attaining superior efficiency with time-spectral methods over traditional time-implicit methods hinges on the ability rapidly to solve the large non-linear system resulting from time-spectral discretizations which become larger and stiffer as more time instances are employed or the period of the flow becomes especially short (i.e. the maximum resolvable wave-number increases). In order to increase the efficiency of these solvers, and to improve robustness, particularly for large numbers of time instances, the Generalized Minimal Residual Method (GMRES) is used to solve the implicit linear system over all coupled time instances. The use of GMRES as the linear solver makes time-spectral methods more robust, allows them to be applied to a far greater subset of time-accurate problems, including those with a broad range of harmonic content, and vastly improves the efficiency of time-spectral methods. In previous work, a wave-number independent preconditioner that mitigates the increased stiffness of the time-spectral method when applied to problems with large resolvable wave numbers has been developed. This preconditioner, however, directly inverts a large matrix whose size increases in proportion to the number of time instances. As a result, the computational time of this method scales as the cube of the number of time instances. In the present work, this preconditioner has been reworked to take advantage of an approximate-factorization approach that effectively decouples the spatial and temporal systems. Once decoupled, the time-spectral matrix can be inverted in frequency space, where it has entries only on the main diagonal and therefore can be inverted quite efficiently. This new GMRES/preconditioner combination is shown to be over an order of magnitude more efficient than the previous wave-number independent preconditioner for problems with large numbers of time instances and/or large reduced frequencies.

Work factors as predictors of persistent fatigue: a prospective study of nurses' aides.

PubMed

Eriksen, W

2006-06-01

To identify work factors that predict persistent fatigue in nurses' aides. The sample comprised 5547 Norwegian nurses' aides, not on leave when they completed a mailed questionnaire in 1999. Of these, 4645 (83.7%) completed a second questionnaire 15 months later. The outcome measure was the occurrence of persistent fatigue, defined as having felt "usually fatigued" or "always fatigued" in daytime during the previous 14 days. In respondents without persistent fatigue at baseline, medium and high work demands, heavy smoking, being single, and having long term health problems were associated with increased risk of persistent fatigue at follow up. Medium and high rewards for well done work, medium levels of leadership fairness, and regular physical exercise were associated with reduced risk of persistent fatigue at follow up. In respondents with persistent fatigue at baseline, medium and high levels of positive challenges at work, high support from immediate superior, medium feedback about quality of one's work, and changes of work or work tasks that resulted in less heavy work or lower work pace were associated with increased odds of recovery (no persistent fatigue at follow up). Working in a nursing home and being intensely bothered by long term health problems were associated with reduced odds of recovery. High demands and lack of rewards at work may cause persistent fatigue in nurses' aides. Reduction of demands, adequate feedback, and mental stimulation in the form of support and positive challenges may facilitate recovery in those who have persistent fatigue. Leaders in the health services may be in a position to regulate factors that influence the level of fatigue in nurses' aides.

ScaffoldScaffolder: solving contig orientation via bidirected to directed graph reduction.

PubMed

Bodily, Paul M; Fujimoto, M Stanley; Snell, Quinn; Ventura, Dan; Clement, Mark J

2016-01-01

The contig orientation problem, which we formally define as the MAX-DIR problem, has at times been addressed cursorily and at times using various heuristics. In setting forth a linear-time reduction from the MAX-CUT problem to the MAX-DIR problem, we prove the latter is NP-complete. We compare the relative performance of a novel greedy approach with several other heuristic solutions. Our results suggest that our greedy heuristic algorithm not only works well but also outperforms the other algorithms due to the nature of scaffold graphs. Our results also demonstrate a novel method for identifying inverted repeats and inversion variants, both of which contradict the basic single-orientation assumption. Such inversions have previously been noted as being difficult to detect and are directly involved in the genetic mechanisms of several diseases. http://bioresearch.byu.edu/scaffoldscaffolder. paulmbodily@gmail.com Supplementary data are available at Bioinformatics online. © The Author 2015. Published by Oxford University Press. All rights reserved. For Permissions, please e-mail: journals.permissions@oup.com.

Optimal partial mass transportation and obstacle Monge-Kantorovich equation

NASA Astrophysics Data System (ADS)

Igbida, Noureddine; Nguyen, Van Thanh

2018-05-01

Optimal partial mass transport, which is a variant of the optimal transport problem, consists in transporting effectively a prescribed amount of mass from a source to a target. The problem was first studied by Caffarelli and McCann (2010) [6] and Figalli (2010) [12] with a particular attention to the quadratic cost. Our aim here is to study the optimal partial mass transport problem with Finsler distance costs including the Monge cost given by the Euclidian distance. Our approach is different and our results do not follow from previous works. Among our results, we introduce a PDE of Monge-Kantorovich type with a double obstacle to characterize active submeasures, Kantorovich potential and optimal flow for the optimal partial transport problem. This new PDE enables us to study the uniqueness and monotonicity results for the active submeasures. Another interesting issue of our approach is its convenience for numerical analysis and computations that we develop in a separate paper [14] (Igbida and Nguyen, 2018).

Low-Complexity User Selection for Rate Maximization in MIMO Broadcast Channels with Downlink Beamforming

PubMed Central

Silva, Adão; Gameiro, Atílio

2014-01-01

We present in this work a low-complexity algorithm to solve the sum rate maximization problem in multiuser MIMO broadcast channels with downlink beamforming. Our approach decouples the user selection problem from the resource allocation problem and its main goal is to create a set of quasiorthogonal users. The proposed algorithm exploits physical metrics of the wireless channels that can be easily computed in such a way that a null space projection power can be approximated efficiently. Based on the derived metrics we present a mathematical model that describes the dynamics of the user selection process which renders the user selection problem into an integer linear program. Numerical results show that our approach is highly efficient to form groups of quasiorthogonal users when compared to previously proposed algorithms in the literature. Our user selection algorithm achieves a large portion of the optimum user selection sum rate (90%) for a moderate number of active users. PMID:24574928

Clarifying the Behavioral Economics of Social Anxiety Disorder: Effects of Interpersonal Problems and Symptom Severity on Generosity.

PubMed

Rodebaugh, Thomas L; Heimberg, Richard G; Taylor, Kristin P; Lenze, Eric J

2016-01-01

Social anxiety disorder is associated with lower interpersonal warmth, possibly explaining its associated interpersonal impairment. Across two samples, we attempted to replicate previous findings that the disorder's constraint of interpersonal warmth can be detected via behavioral economic tasks. We also tested the test-retest stability of task indices. Results indicated that factors associated with social anxiety disorder (and not the disorder itself), such as the severity of social anxiety and more extreme interpersonal problems, lead to less generous behavior on the economic task examined. Results were clearest regarding fine-grained indices derived from latent trajectories. Unexpectedly, the combination of generalized anxiety disorder and higher depression also restricted generosity. Two of three indices showed acceptable test-retest stability. Maladaptive giving behavior may be a treatment target to improve interpersonal functioning in psychiatric disorders; therefore, future work should more precisely characterize behavioral economic tasks, including basic psychometric work (i.e., tests of reliability and validity).

Development of a New Intelligent Joystick for People with Reduced Mobility.

PubMed

Mrabet, Makrem; Rabhi, Yassine; Fnaiech, Farhat

2018-01-01

Despite the diversity of electric wheelchairs, many people with physical limitations and seniors have difficulty using their standard joystick. As a result, they cannot meet their needs or ensure safe travel. Recent assistive technologies can help to give them autonomy and independence. This work deals with the real-time implementation of an artificial intelligence device to overcome these problems. Following a review of the literature from previous work, we present the methodology and process for implementing our intelligent control system on an electric wheelchair. The system is based on a neural algorithm that overcomes problems with standard joystick maneuvers such as the inability to move correctly in one direction. However, this implies the need for an appropriate methodology to map the position of the joystick handle. Experiments on a real wheelchair are carried out with real patients of the Mohamed Kassab National Institute Orthopedic, Physical and Functional Rehabilitation Hospital of Tunis. The proposed intelligent system gives good results compared to the use of a standard joystick.

Clarifying the Behavioral Economics of Social Anxiety Disorder: Effects of Interpersonal Problems and Symptom Severity on Generosity

PubMed Central

Rodebaugh, Thomas L.; Heimberg, Richard G.; Taylor, Kristin P.; Lenze, Eric J.

2015-01-01

Social anxiety disorder is associated with lower interpersonal warmth, possibly explaining its associated interpersonal impairment. Across two samples, we attempted to replicate previous findings that the disorder’s constraint of interpersonal warmth can be detected via behavioral economic tasks. We also tested the test-retest stability of task indices. Results indicated that factors associated with social anxiety disorder (and not the disorder itself), such as the severity of social anxiety and more extreme interpersonal problems, lead to less generous behavior on the economic task examined. Results were clearest regarding fine-grained indices derived from latent trajectories. Unexpectedly, the combination of generalized anxiety disorder and higher depression also restricted generosity. Two of three indices showed acceptable test-retest stability. Maladaptive giving behavior may be a treatment target to improve interpersonal functioning in psychiatric disorders; therefore, future work should more precisely characterize behavioral economic tasks, including basic psychometric work (i.e., tests of reliability and validity). PMID:27034911

Neural network application to comprehensive engine diagnostics

NASA Technical Reports Server (NTRS)

Marko, Kenneth A.

1994-01-01

We have previously reported on the use of neural networks for detection and identification of faults in complex microprocessor controlled powertrain systems. The data analyzed in those studies consisted of the full spectrum of signals passing between the engine and the real-time microprocessor controller. The specific task of the classification system was to classify system operation as nominal or abnormal and to identify the fault present. The primary concern in earlier work was the identification of faults, in sensors or actuators in the powertrain system as it was exercised over its full operating range. The use of data from a variety of sources, each contributing some potentially useful information to the classification task, is commonly referred to as sensor fusion and typifies the type of problems successfully addressed using neural networks. In this work we explore the application of neural networks to a different diagnostic problem, the diagnosis of faults in newly manufactured engines and the utility of neural networks for process control.

Development of a New Intelligent Joystick for People with Reduced Mobility

PubMed Central

Mrabet, Makrem; Fnaiech, Farhat

2018-01-01

Despite the diversity of electric wheelchairs, many people with physical limitations and seniors have difficulty using their standard joystick. As a result, they cannot meet their needs or ensure safe travel. Recent assistive technologies can help to give them autonomy and independence. This work deals with the real-time implementation of an artificial intelligence device to overcome these problems. Following a review of the literature from previous work, we present the methodology and process for implementing our intelligent control system on an electric wheelchair. The system is based on a neural algorithm that overcomes problems with standard joystick maneuvers such as the inability to move correctly in one direction. However, this implies the need for an appropriate methodology to map the position of the joystick handle. Experiments on a real wheelchair are carried out with real patients of the Mohamed Kassab National Institute Orthopedic, Physical and Functional Rehabilitation Hospital of Tunis. The proposed intelligent system gives good results compared to the use of a standard joystick. PMID:29765462

Syndemic theory and HIV-related risk among young transgender women: the role of multiple, co-occurring health problems and social marginalization.

PubMed

Brennan, Julia; Kuhns, Lisa M; Johnson, Amy K; Belzer, Marvin; Wilson, Erin C; Garofalo, Robert

2012-09-01

We assessed whether multiple psychosocial factors are additive in their relationship to sexual risk behavior and self-reported HIV status (i.e., can be characterized as a syndemic) among young transgender women and the relationship of indicators of social marginalization to psychosocial factors. Participants (n = 151) were aged 15 to 24 years and lived in Chicago or Los Angeles. We collected data on psychosocial factors (low self-esteem, polysubstance use, victimization related to transgender identity, and intimate partner violence) and social marginalization indicators (history of commercial sex work, homelessness, and incarceration) through an interviewer-administered survey. Syndemic factors were positively and additively related to sexual risk behavior and self-reported HIV infection. In addition, our syndemic index was significantly related to 2 indicators of social marginalization: a history of sex work and previous incarceration. These findings provide evidence for a syndemic of co-occurring psychosocial and health problems in young transgender women, taking place in a context of social marginalization.

Mental health and sexual identity in a sample of male sex workers in the Czech Republic.

PubMed

Bar-Johnson, Michael; Weiss, Petr

2014-09-20

Previous qualitative research has examined male sex workers in the Czech Republic, but this mapping study is the first to investigate male sex work in a quantitative research design and focus on the mental health of these sex workers. This study also examines male sex workers' mental health problems in relation to their sexual identity or orientation. A sample of Czech male sex workers (N=40) were examined on a range of sexual and psychological variables using a quantitative survey administered face-to-face. The study employed locally validated versions of Beck's Depression Inventory and Zung's Self-Report Anxiety Scale. The results indicate that for homosexuals, working as a male sex worker is not related to any serious mental health problems. However, those identifying as heterosexual and bisexual more frequently reported symptoms of depression and bisexuals showed significantly more anxiety. These findings suggest sexual identity is an important issue to consider when addressing the mental health needs of this population.

A splitting algorithm for a novel regularization of Perona-Malik and application to image restoration

NASA Astrophysics Data System (ADS)

Karami, Fahd; Ziad, Lamia; Sadik, Khadija

2017-12-01

In this paper, we focus on a numerical method of a problem called the Perona-Malik inequality which we use for image denoising. This model is obtained as the limit of the Perona-Malik model and the p-Laplacian operator with p→ ∞. In Atlas et al., (Nonlinear Anal. Real World Appl 18:57-68, 2014), the authors have proved the existence and uniqueness of the solution of the proposed model. However, in their work, they used the explicit numerical scheme for approximated problem which is strongly dependent to the parameter p. To overcome this, we use in this work an efficient algorithm which is a combination of the classical additive operator splitting and a nonlinear relaxation algorithm. At last, we have presented the experimental results in image filtering show, which demonstrate the efficiency and effectiveness of our algorithm and finally, we have compared it with the previous scheme presented in Atlas et al., (Nonlinear Anal. Real World Appl 18:57-68, 2014).

Impact of herpes zoster and post-herpetic neuralgia on patients’ quality of life: a patient-reported outcomes survey

PubMed Central

Edte, Alexander; Schmitt, Sonja; Lukas, Kati

2010-01-01

Background The impact of herpes zoster (HZ) and post-herpetic neuralgia (PHN) on patients’ quality of life (QoL) is currently poorly documented. Subjects and methods Telephone interviews in Germany identified patients ≥50 years old with painful HZ diagnosed during the previous 5 years. Bespoke questions evaluated previous HZ episodes. Results Of 11,009 respondents, 280 met the screening criteria, and 32 (11%) developed PHN. PHN was associated with significantly worse outcomes than HZ (all P < 0.05). Mean pain scores associated with PHN and HZ, respectively, were 7.1 and 6.2 (average) and 8.2 and 7.0 (worst). Many patients with PHN (91%) and HZ (73%) experienced problems with daily activities, including work, studies, housework, family and leisure activities. Mean pain interference scores in patients with PHN versus HZ were highest for sleep (6.5 versus 4.9), normal work (6.1 versus 4.4) and mood (5.9 versus 4.4). Most employed interviewees with PHN (70%) and HZ (64%) stopped work during the disease. Pain and QoL outcomes were not significantly different between all patients versus those diagnosed during the previous 12 months or between patients aged 50–59 years versus ≥60 years. Conclusions HZ causes substantial pain, which seriously interferes with many aspects of daily life, particularly in patients with PHN. PMID:21124645

Structural health monitoring of cylindrical bodies under impulsive hydrodynamic loading by distributed FBG strain measurements

NASA Astrophysics Data System (ADS)

Fanelli, Pierluigi; Biscarini, Chiara; Jannelli, Elio; Ubertini, Filippo; Ubertini, Stefano

2017-02-01

Various mechanical, ocean, aerospace and civil engineering problems involve solid bodies impacting the water surface and often result in complex coupled dynamics, characterized by impulsive loading conditions, high amplitude vibrations and large local deformations. Monitoring in such problems for purposes such as remaining fatigue life estimation and real time damage detection is a technical and scientific challenge of primary concern in this context. Open issues include the need for developing distributed sensing systems able to operate at very high acquisition frequencies, to be utilized to study rapidly varying strain fields, with high resolution and very low noise, while scientific challenges mostly relate to the definition of appropriate signal processing and modeling tools enabling the extraction of useful information from distributed sensing signals. Building on previous work by some of the authors, we propose an enhanced method for real time deformed shape reconstruction using distributed FBG strain measurements in curved bodies subjected to impulsive loading and we establish a new framework for applying this method for structural health monitoring purposes, as the main focus of the work. Experiments are carried out on a cylinder impacting the water at various speeds, proving improved performance in displacement reconstruction of the enhanced method compared to its previous version. A numerical study is then carried out considering the same physical problem with different delamination damages affecting the body. The potential for detecting, localizing and quantifying this damage using the reconstruction algorithm is thoroughly investigated. Overall, the results presented in the paper show the potential of distributed FBG strain measurements for real time structural health monitoring of curved bodies under impulsive hydrodynamic loading, defining damage sensitive features in terms of strain or displacement reconstruction errors at selected locations along the structure.

Psychosocial Problems of War-Affected Youth in Northern Uganda: A Qualitative Study

PubMed Central

Speelman, Liesbeth; Onyango, Grace; Bolton, Paul

2008-01-01

Multiple studies have found that children from a variety of cultures who have been affected by war are at increased risk for a range of psychosocial problems. However, most studies are based on Western concepts and assume that these are locally applicable. Very few have investigated how psychosocial problems are perceived by the affected communities, families and the young people themselves. Understanding local perceptions is important to ensuring that local priorities are addressed, and addressed in ways that are likely to be acceptable and effective. In this study we used a previously developed rapid ethnographic assessment method to explore local perceptions of psychosocial problems among issues among children and adults from the Acholi ethnic group that have been displaced by the war in northern Uganda. We conducted 45 free list interviews (N= 30 10-17 year olds, N=15 adults) and 57 key informant interviews (N=32 10-17 year olds, N=25 adults) Our purpose was twofold: 1) To test whether this rapid ethnographic assessment approach previously used among adults would be suitable for use with children; and 2) To use this approach to understand the psychosocial problems affecting local children from their own viewpoint and that of their caretakers, in order to inform subsequent assessment and intervention efforts by organizations serving this population. The rapid assessment approach appears to have worked well for interviewing caretakers and children aged 10-17 years. Several locally defined syndromes were described: two tam/par/kumu (depression and dysthymia-like syndromes), ma lwor (an anxiety-like syndrome), and a category of conduct problems referred to as kwo maraco/gin lugero. The descriptions of these local syndromes are similar to Western mood, anxiety and conduct disorders, but contain some culture-specific elements. PMID:19541749

Patterns, correlates, and reduction of homework copying

NASA Astrophysics Data System (ADS)

Palazzo, David J.; Lee, Young-Jin; Warnakulasooriya, Rasil; Pritchard, David E.

2010-06-01

Submissions to an online homework tutor were analyzed to determine whether they were copied. The fraction of copied submissions increased rapidly over the semester, as each weekly deadline approached and for problems later in each assignment. The majority of students, who copied less than 10% of their problems, worked steadily over the three days prior to the deadline, whereas repetitive copiers (those who copied >30% of their submitted problems) exerted little effort early. Importantly, copying homework problems that require an analytic answer correlates with a 2(σ) decline over the semester in relative score for similar problems on exams but does not significantly correlate with the amount of conceptual learning as measured by pretesting and post-testing. An anonymous survey containing questions used in many previous studies of self-reported academic dishonesty showed ˜1/3 less copying than actually was detected. The observed patterns of copying, free response questions on the survey, and interview data suggest that time pressure on students who do not start their homework in a timely fashion is the proximate cause of copying. Several measures of initial ability in math or physics correlated with copying weakly or not at all. Changes in course format and instructional practices that previous self-reported academic dishonesty surveys and/or the observed copying patterns suggested would reduce copying have been accompanied by more than a factor of 4 reduction of copying from ˜11% of all electronic problems to less than 3%. As expected (since repetitive copiers have approximately three times the chance of failing), this was accompanied by a reduction in the overall course failure rate. Survey results indicate that students copy almost twice as much written homework as online homework and show that students nationally admit to more academic dishonesty than MIT students.

Uplink transmit beamforming design for SINR maximization with full multiuser channel state information

NASA Astrophysics Data System (ADS)

Xi, Songnan; Zoltowski, Michael D.

2008-04-01

Multiuser multiple-input multiple-output (MIMO) systems are considered in this paper. We continue our research on uplink transmit beamforming design for multiple users under the assumption that the full multiuser channel state information, which is the collection of the channel state information between each of the users and the base station, is known not only to the receiver but also to all the transmitters. We propose an algorithm for designing optimal beamforming weights in terms of maximizing the signal-to-interference-plus-noise ratio (SINR). Through statistical modeling, we decouple the original mathematically intractable optimization problem and achieved a closed-form solution. As in our previous work, the minimum mean-squared error (MMSE) receiver with successive interference cancellation (SIC) is adopted for multiuser detection. The proposed scheme is compared with an existing jointly optimized transceiver design, referred to as the joint transceiver in this paper, and our previously proposed eigen-beamforming algorithm. Simulation results demonstrate that our algorithm, with much less computational burden, accomplishes almost the same performance as the joint transceiver for spatially independent MIMO channel and even better performance for spatially correlated MIMO channels. And it always works better than our previously proposed eigen beamforming algorithm.

Electroosmotic Mixing in Nanochannels

NASA Astrophysics Data System (ADS)

Conlisk, A. T.; Chen, Lei

2004-11-01

Electroosmotic flow in nanochannels is characterized by low Reynolds number in which flow mixing is difficult because of the dominance of molecular diffusion. Previous work shows that heterogenerous surface potential could generate a circulation region within the bulk flow near the surface. But all of this work requires that the ionic species be pairs of ions of equal and opposite valence and the distribution of ions is not considered. In the present work the electroosmotic flow in a rectangular channel with non-uniform zeta potential is examined. A model for the two dimensional electroosmotic flow problem is established. The distributions of potential, velocity and mole fractions are calculated numerically. Vortex formation is observed within the bulk flow near the the region of non-uniform zeta potential which suggests mixing can be induced.

Alternative approximation concepts for space frame synthesis

NASA Technical Reports Server (NTRS)

Lust, R. V.; Schmit, L. A.

1985-01-01

A structural synthesis methodology for the minimum mass design of 3-dimensionall frame-truss structures under multiple static loading conditions and subject to limits on displacements, rotations, stresses, local buckling, and element cross-sectional dimensions is presented. A variety of approximation concept options are employed to yield near optimum designs after no more than 10 structural analyses. Available options include: (A) formulation of the nonlinear mathematcal programming problem in either reciprocal section property (RSP) or cross-sectional dimension (CSD) space; (B) two alternative approximate problem structures in each design space; and (C) three distinct assumptions about element end-force variations. Fixed element, design element linking, and temporary constraint deletion features are also included. The solution of each approximate problem, in either its primal or dual form, is obtained using CONMIN, a feasible directions program. The frame-truss synthesis methodology is implemented in the COMPASS computer program and is used to solve a variety of problems. These problems were chosen so that, in addition to exercising the various approximation concepts options, the results could be compared with previously published work.

Validity of the Addiction Severity Index (adapted version) in a Costa Rican population group.

PubMed

Sandí Esquivel, L E; Avila Corrales, K

1990-01-01

Until recently, no adapted and validated instrument was available for assessing the alcohol and drug problems of individuals in Costa Rica. This article reports the results of a study performed by Costa Rica's Institute on Alcoholism and Drug Dependence in order to test an adapted version of one such instrument, the Addiction Severity Index (ASI), in a Costa Rican setting. The instrument was used to interview 100 male subjects 18 to 64 years old (51 with diagnosed alcohol or drug problems and 49 controls). In general, the subjects with previously diagnosed alcohol or drug problems were assigned substantially higher scores. More specifically, statistical analysis indicated highly significant correlations (p less than 0.001) between the type of subject (test subject or control) and the likelihood that noteworthy problems would be found in the areas of alcohol use, family/social relations, work/finances, and psychological status. Overall, the study demonstrated that the instrument was capable of distinguishing between the affected and unaffected populations, and also of gauging the severity of the problems involved and the patients' treatment needs.

Mass and Volume Optimization of Space Flight Medical Kits

NASA Technical Reports Server (NTRS)

Keenan, A. B.; Foy, Millennia Hope; Myers, Jerry

2014-01-01

Resource allocation is a critical aspect of space mission planning. All resources, including medical resources, are subject to a number of mission constraints such a maximum mass and volume. However, unlike many resources, there is often limited understanding in how to optimize medical resources for a mission. The Integrated Medical Model (IMM) is a probabilistic model that estimates medical event occurrences and mission outcomes for different mission profiles. IMM simulates outcomes and describes the impact of medical events in terms of lost crew time, medical resource usage, and the potential for medically required evacuation. Previously published work describes an approach that uses the IMM to generate optimized medical kits that maximize benefit to the crew subject to mass and volume constraints. We improve upon the results obtained previously and extend our approach to minimize mass and volume while meeting some benefit threshold. METHODS We frame the medical kit optimization problem as a modified knapsack problem and implement an algorithm utilizing dynamic programming. Using this algorithm, optimized medical kits were generated for 3 mission scenarios with the goal of minimizing the medical kit mass and volume for a specified likelihood of evacuation or Crew Health Index (CHI) threshold. The algorithm was expanded to generate medical kits that maximize likelihood of evacuation or CHI subject to mass and volume constraints. RESULTS AND CONCLUSIONS In maximizing benefit to crew health subject to certain constraints, our algorithm generates medical kits that more closely resemble the unlimited-resource scenario than previous approaches which leverage medical risk information generated by the IMM. Our work here demonstrates that this algorithm provides an efficient and effective means to objectively allocate medical resources for spaceflight missions and provides an effective means of addressing tradeoffs in medical resource allocations and crew mission success parameters.

The study of topics of Astronomy in Physics teaching that addresses the significant learning

NASA Astrophysics Data System (ADS)

Santos Neta, M. L.; Voelzke, M. R.

2017-12-01

In this work are discussed the results of the case study on the oceanic tides for which it was used didactic sequences, based on the Cycle of Experience of George Kelly (Kelly 1963), applied in four groups of the first year of the integral medium teaching. The data obtained in two same tests - Pre and Post-Test - before and after the application of the didactic sequences, as well as the verification of the significant learning analysed as for the conditions of the previous knowledge considering authors Boczko (1984), Horvath (2008) and Kepler & Saraiva (2013). Also the values were analysed obtained the Post-Test II applied to the long period. The results reveal that the worked groups presented previous knowledge in conditions adapted for the understanding of the event, as well as, for they be used in the situation-problem resolution that demands the understanding. Verify also that the idea of the didactic sequence can be used as tool in the relationship teaching-learning addressed to the significant learning.

Scalable detection of statistically significant communities and hierarchies, using message passing for modularity

PubMed Central

Zhang, Pan; Moore, Cristopher

2014-01-01

Modularity is a popular measure of community structure. However, maximizing the modularity can lead to many competing partitions, with almost the same modularity, that are poorly correlated with each other. It can also produce illusory ‘‘communities’’ in random graphs where none exist. We address this problem by using the modularity as a Hamiltonian at finite temperature and using an efficient belief propagation algorithm to obtain the consensus of many partitions with high modularity, rather than looking for a single partition that maximizes it. We show analytically and numerically that the proposed algorithm works all of the way down to the detectability transition in networks generated by the stochastic block model. It also performs well on real-world networks, revealing large communities in some networks where previous work has claimed no communities exist. Finally we show that by applying our algorithm recursively, subdividing communities until no statistically significant subcommunities can be found, we can detect hierarchical structure in real-world networks more efficiently than previous methods. PMID:25489096

Impact of compressibility and a guide field on Fermi acceleration during magnetic island coalescence

NASA Astrophysics Data System (ADS)

Montag, Peter; Egedal, Jan; Lichko, Emily; Wetherton, Blake

2017-10-01

Previous work has shown that Fermi acceleration can be an effective heating mechanism during magnetic island coalescence, where electrons may undergo repeated reflections as the magnetic field lines contract. This energization has the potential to account for the power-law distributions of particle energy inferred from observations of solar flares. Here, we develop a generalized framework for the analysis of Fermi acceleration that can incorporate the effects of compressibility and non-uniformity along field lines, which have commonly been neglected in previous treatments of the problem. Applying this framework to the simplified case of the uniform flux tube allows us to find both the power-law scaling of the distribution function and the rate at which the power-law behavior develops. We find that a guide magnetic field of order unity effectively suppresses the development of power-law distributions. The work was supported by NASA Grant No. NNX14AC68G, NSF GEM Grant No. 1405166, NSF Award 1404166, and NASA Award NNX15AJ73G.

Representational task formats and problem solving strategies in kinematics and work

NASA Astrophysics Data System (ADS)

Ibrahim, Bashirah; Rebello, N. Sanjay

2012-06-01

Previous studies have reported that students employed different problem solving approaches when presented with the same task structured with different representations. In this study, we explored and compared students’ strategies as they attempted tasks from two topical areas, kinematics and work. Our participants were 19 engineering students taking a calculus-based physics course. The tasks were presented in linguistic, graphical, and symbolic forms and requested either a qualitative solution or a value. The analysis was both qualitative and quantitative in nature focusing principally on the characteristics of the strategies employed as well as the underlying reasoning for their applications. A comparison was also made for the same student’s approach with the same kind of representation across the two topics. Additionally, the participants’ overall strategies across the different tasks, in each topic, were considered. On the whole, we found that the students prefer manipulating equations irrespective of the representational format of the task. They rarely recognized the applicability of a “qualitative” approach to solve the problem although they were aware of the concepts involved. Even when the students included visual representations in their solutions, they seldom used these representations in conjunction with the mathematical part of the problem. Additionally, the students were not consistent in their approach for interpreting and solving problems with the same kind of representation across the two topical areas. The representational format, level of prior knowledge, and familiarity with a topic appeared to influence their strategies, their written responses, and their ability to recognize qualitative ways to attempt a problem. The nature of the solution does not seem to impact the strategies employed to handle the problem.

Non-erotic thoughts, attentional focus, and sexual problems in a community sample.

PubMed

Nelson, Andrea L; Purdon, Christine

2011-04-01

According to Barlow's model of sexual dysfunction, anxiety in sexual situations leads to attentional focus on sexual performance at the expense of erotic cues, which compromises sexual arousal. This negative experience will enhance anxiety in future sexual situations, and non-erotic thoughts (NETs) relevant to performance will receive attentional priority. Previous research with student samples (Purdon & Holdaway, 2006; Purdon & Watson, 2010) has found that people experience many types of NETs in addition to performance-relevant thoughts, and that, consistent with Barlow's model, the frequency of and anxiety evoked by these thoughts is positively associated with sexual problems. Extending this previous work, the current study found that, in a community sample of women (N = 81) and men (N = 72) in long-term relationships, women were more likely to report body image concerns and external consequences of the sexual activity, while men were more likely to report performance-related concerns. Equally likely among men and women were thoughts about emotional consequences of the sexual activity. Regardless of thought content, experiencing more frequent NETs was associated with more sexual problems in both women and men. Moreover, as per Barlow's model, greater negative affect in anticipation of and during sexual activity predicted greater frequency of NETs and greater anxiety in response to NETs was associated with greater difficulty dismissing the thoughts. However, greater difficulty in refocusing on erotic thoughts during sexual activity uniquely predicted more sexual problems above the frequency and dismissability of NETs. Together, these data support the cognitive interference mechanism implicated by Barlow's causal model of sexual dysfunction and have implications for the treatment of sexual problems.

Stress-Constrained Structural Topology Optimization with Design-Dependent Loads

NASA Astrophysics Data System (ADS)

Lee, Edmund

Topology optimization is commonly used to distribute a given amount of material to obtain the stiffest structure, with predefined fixed loads. The present work investigates the result of applying stress constraints to topology optimization, for problems with design-depending loading, such as self-weight and pressure. In order to apply pressure loading, a material boundary identification scheme is proposed, iteratively connecting points of equal density. In previous research, design-dependent loading problems have been limited to compliance minimization. The present study employs a more practical approach by minimizing mass subject to failure constraints, and uses a stress relaxation technique to avoid stress constraint singularities. The results show that these design dependent loading problems may converge to a local minimum when stress constraints are enforced. Comparisons between compliance minimization solutions and stress-constrained solutions are also given. The resulting topologies of these two solutions are usually vastly different, demonstrating the need for stress-constrained topology optimization.

Symbolically Modeling Concurrent MCAPI Executions

NASA Technical Reports Server (NTRS)

Fischer, Topher; Mercer, Eric; Rungta, Neha

2011-01-01

Improper use of Inter-Process Communication (IPC) within concurrent systems often creates data races which can lead to bugs that are challenging to discover. Techniques that use Satisfiability Modulo Theories (SMT) problems to symbolically model possible executions of concurrent software have recently been proposed for use in the formal verification of software. In this work we describe a new technique for modeling executions of concurrent software that use a message passing API called MCAPI. Our technique uses an execution trace to create an SMT problem that symbolically models all possible concurrent executions and follows the same sequence of conditional branch outcomes as the provided execution trace. We check if there exists a satisfying assignment to the SMT problem with respect to specific safety properties. If such an assignment exists, it provides the conditions that lead to the violation of the property. We show how our method models behaviors of MCAPI applications that are ignored in previously published techniques.

Target Fishing for Chemical Compounds using Target-Ligand Activity data and Ranking based Methods

PubMed Central

Wale, Nikil; Karypis, George

2009-01-01

In recent years the development of computational techniques that identify all the likely targets for a given chemical compound, also termed as the problem of Target Fishing, has been an active area of research. Identification of likely targets of a chemical compound helps to understand problems such as toxicity, lack of efficacy in humans, and poor physical properties associated with that compound in the early stages of drug discovery. In this paper we present a set of techniques whose goal is to rank or prioritize targets in the context of a given chemical compound such that most targets that this compound may show activity against appear higher in the ranked list. These methods are based on our extensions to the SVM and Ranking Perceptron algorithms for this problem. Our extensive experimental study shows that the methods developed in this work outperform previous approaches by 2% to 60% under different evaluation criterions. PMID:19764745

Solving Assembly Sequence Planning using Angle Modulated Simulated Kalman Filter

NASA Astrophysics Data System (ADS)

Mustapa, Ainizar; Yusof, Zulkifli Md.; Adam, Asrul; Muhammad, Badaruddin; Ibrahim, Zuwairie

2018-03-01

This paper presents an implementation of Simulated Kalman Filter (SKF) algorithm for optimizing an Assembly Sequence Planning (ASP) problem. The SKF search strategy contains three simple steps; predict-measure-estimate. The main objective of the ASP is to determine the sequence of component installation to shorten assembly time or save assembly costs. Initially, permutation sequence is generated to represent each agent. Each agent is then subjected to a precedence matrix constraint to produce feasible assembly sequence. Next, the Angle Modulated SKF (AMSKF) is proposed for solving ASP problem. The main idea of the angle modulated approach in solving combinatorial optimization problem is to use a function, g(x), to create a continuous signal. The performance of the proposed AMSKF is compared against previous works in solving ASP by applying BGSA, BPSO, and MSPSO. Using a case study of ASP, the results show that AMSKF outperformed all the algorithms in obtaining the best solution.

The early benefits of a problem-based approach to teaching social inclusion using an online virtual town.

PubMed

Beadle, Mary; Santy, Julie

2008-05-01

This article describes the delivery of a core pre-registration nursing and midwifery module centred on social inclusion. The module was previously delivered using a classroom-based problem-based learning approach. Difficulties with this approach led to changes to the module and its delivery. Logistic issues encouraged the module team to implement a blended learning approach using a virtual town to facilitate online learning and discussion activities. The paper describes and discusses the use of online learning technology to support student nurses and midwives. It highlights the benefits of this approach and outlines some of the experiences of the students including their evaluation of the virtual town. There is also an examination of some of the practical and theoretical issues related to both problem-based learning, online working and using a virtual town to support learning. This article outlines the approach taken and its implications.

Convex formulation of multiple instance learning from positive and unlabeled bags.

PubMed

Bao, Han; Sakai, Tomoya; Sato, Issei; Sugiyama, Masashi

2018-05-24

Multiple instance learning (MIL) is a variation of traditional supervised learning problems where data (referred to as bags) are composed of sub-elements (referred to as instances) and only bag labels are available. MIL has a variety of applications such as content-based image retrieval, text categorization, and medical diagnosis. Most of the previous work for MIL assume that training bags are fully labeled. However, it is often difficult to obtain an enough number of labeled bags in practical situations, while many unlabeled bags are available. A learning framework called PU classification (positive and unlabeled classification) can address this problem. In this paper, we propose a convex PU classification method to solve an MIL problem. We experimentally show that the proposed method achieves better performance with significantly lower computation costs than an existing method for PU-MIL. Copyright © 2018 Elsevier Ltd. All rights reserved.

Self-inflicted injuries. Challenging knowledge, skill, and compassion.

PubMed

Haswell, D E; Graham, M

1996-09-01

Self-inflicted injuries and other serious self-destructive behaviours are common and difficult to recognize, prevent, and manage. Although they have previously been understood as repeated, failed attempts at suicide, they are better understood as maladaptive coping strategies. Women who present repeatedly with self-inflicted injuries need help to control this self-destructive behaviour and substitute more positive coping strategies. Physicians also need help in working with patients who respond to problems in this way. The program is made up of two broad sections. The first section involves understanding the problem and its origins in post-traumatic stress disorders. The second section offers a practical approach to helping patients presenting with injuries inflict upon themselves. A deeper understanding of the etiology and management of repeated self-inflicted injuries will enable physicians to help patients with this difficult problem while minimizing their own anxiety and frustration.

On sufficient statistics of least-squares superposition of vector sets.

PubMed

Konagurthu, Arun S; Kasarapu, Parthan; Allison, Lloyd; Collier, James H; Lesk, Arthur M

2015-06-01

The problem of superposition of two corresponding vector sets by minimizing their sum-of-squares error under orthogonal transformation is a fundamental task in many areas of science, notably structural molecular biology. This problem can be solved exactly using an algorithm whose time complexity grows linearly with the number of correspondences. This efficient solution has facilitated the widespread use of the superposition task, particularly in studies involving macromolecular structures. This article formally derives a set of sufficient statistics for the least-squares superposition problem. These statistics are additive. This permits a highly efficient (constant time) computation of superpositions (and sufficient statistics) of vector sets that are composed from its constituent vector sets under addition or deletion operation, where the sufficient statistics of the constituent sets are already known (that is, the constituent vector sets have been previously superposed). This results in a drastic improvement in the run time of the methods that commonly superpose vector sets under addition or deletion operations, where previously these operations were carried out ab initio (ignoring the sufficient statistics). We experimentally demonstrate the improvement our work offers in the context of protein structural alignment programs that assemble a reliable structural alignment from well-fitting (substructural) fragment pairs. A C++ library for this task is available online under an open-source license.

Burnout in the working population: relations to psychosocial work factors.

PubMed

Lindblom, Karin M; Linton, Steven J; Fedeli, Cecilia; Bryngelsson, Ing-Liss

2006-01-01

This study investigated levels of burnout in the general population irrespective of occupation and relations between burnout and psychosocial work factors. A cross-sectional survey featuring sleep problems, psychological distress, burnout (Maslach Burnout Inventory-General Survey), and psychosocial factors at work, was mailed to a random sample of 3,000 participants, aged 20-60. Response rate was 61%. A high level (18%), a low level (19%), and an intermediate group (63%) for burnout were constructed. The high level group was associated with those who were > 50 years old, women, those experiencing psychological distress, and those with a poor psychosocial work climate. The analyses on variables significant in previous analyses showed that the high level group was strongly related to high demands, low control, lack of social support, and disagreeing about values at the workplace even when accounting for age, gender, and psychological distress. We conclude that psychosocial work factors are important in association to burnout regardless of occupation.

Congested Aggregation via Newtonian Interaction

NASA Astrophysics Data System (ADS)

Craig, Katy; Kim, Inwon; Yao, Yao

2018-01-01

We consider a congested aggregation model that describes the evolution of a density through the competing effects of nonlocal Newtonian attraction and a hard height constraint. This provides a counterpoint to existing literature on repulsive-attractive nonlocal interaction models, where the repulsive effects instead arise from an interaction kernel or the addition of diffusion. We formulate our model as the Wasserstein gradient flow of an interaction energy, with a penalization to enforce the constraint on the height of the density. From this perspective, the problem can be seen as a singular limit of the Keller-Segel equation with degenerate diffusion. Two key properties distinguish our problem from previous work on height constrained equations: nonconvexity of the interaction kernel (which places the model outside the scope of classical gradient flow theory) and nonlocal dependence of the velocity field on the density (which causes the problem to lack a comparison principle). To overcome these obstacles, we combine recent results on gradient flows of nonconvex energies with viscosity solution theory. We characterize the dynamics of patch solutions in terms of a Hele-Shaw type free boundary problem and, using this characterization, show that in two dimensions patch solutions converge to a characteristic function of a disk in the long-time limit, with an explicit rate on the decay of the energy. We believe that a key contribution of the present work is our blended approach, combining energy methods with viscosity solution theory.

Impact of computer use on children's vision.

PubMed

Kozeis, N

2009-10-01

Today, millions of children use computers on a daily basis. Extensive viewing of the computer screen can lead to eye discomfort, fatigue, blurred vision and headaches, dry eyes and other symptoms of eyestrain. These symptoms may be caused by poor lighting, glare, an improper work station set-up, vision problems of which the person was not previously aware, or a combination of these factors. Children can experience many of the same symptoms related to computer use as adults. However, some unique aspects of how children use computers may make them more susceptible than adults to the development of these problems. In this study, the most common eye symptoms related to computer use in childhood, the possible causes and ways to avoid them are reviewed.

Optimal design of FIR triplet halfband filter bank and application in image coding.

PubMed

Kha, H H; Tuan, H D; Nguyen, T Q

2011-02-01

This correspondence proposes an efficient semidefinite programming (SDP) method for the design of a class of linear phase finite impulse response triplet halfband filter banks whose filters have optimal frequency selectivity for a prescribed regularity order. The design problem is formulated as the minimization of the least square error subject to peak error constraints and regularity constraints. By using the linear matrix inequality characterization of the trigonometric semi-infinite constraints, it can then be exactly cast as a SDP problem with a small number of variables and, hence, can be solved efficiently. Several design examples of the triplet halfband filter bank are provided for illustration and comparison with previous works. Finally, the image coding performance of the filter bank is presented.

Machine learning for inverse lithography: using stochastic gradient descent for robust photomask synthesis

NASA Astrophysics Data System (ADS)

Jia, Ningning; Y Lam, Edmund

2010-04-01

Inverse lithography technology (ILT) synthesizes photomasks by solving an inverse imaging problem through optimization of an appropriate functional. Much effort on ILT is dedicated to deriving superior masks at a nominal process condition. However, the lower k1 factor causes the mask to be more sensitive to process variations. Robustness to major process variations, such as focus and dose variations, is desired. In this paper, we consider the focus variation as a stochastic variable, and treat the mask design as a machine learning problem. The stochastic gradient descent approach, which is a useful tool in machine learning, is adopted to train the mask design. Compared with previous work, simulation shows that the proposed algorithm is effective in producing robust masks.

[The infertile couple: between biology and psyche].

PubMed

Dudkiewicz-Sibony, Charlotte

2012-09-01

In this paper, we tried to show through some clinical examples that there is not on the one side the body, and on the other the psyche. The Assisted Reproductive Technology (ART), because the field it covers, namely procreation, is a magnificent observatory of interactions between body and psyche, desire and inhibition, request and mental block, hatred and love… Assisted reproduction techniques are often indicative of links between these terms, and of what symbols are at stake in the couples concerned. It is interesting to see how these sophisticated techniques not only work as a solution to infertility problems -which are plural and diverse- but as a developer of human problems that we previously thought we would escape. Copyright © 2012. Published by Elsevier SAS.

Expatriates' Multiple Fears, from Terrorism to Working Conditions: Development of a Model.

PubMed

Giorgi, Gabriele; Montani, Francesco; Fiz-Perez, Javier; Arcangeli, Giulio; Mucci, Nicola

2016-01-01

Companies' internationalization appears to be fundamental in the current globalized and competitive environment and seems important not only for organizational success, but also for societal development and sustainability. On one hand, global business increases the demand for managers for international assignment. On the other hand, emergent fears, such as terrorism, seem to be developing around the world, enhancing the risk of expatriates' potential health problems. The purpose of this paper is to examine the relationships between the emergent concept of fear of expatriation with further workplace fears (economic crisis and dangerous working conditions) and with mental health problems. The study uses a quantitative design. Self-reported data were collected from 265 Italian expatriate workers assigned to both Italian and worldwide projects. Structural equation model analyses showed that fear of expatriation mediates the relationship of mental health with fear of economic crisis and with perceived dangerous working conditions. As expected, in addition to fear, worries of expatriation are also related to further fears. Although, the study is based on self-reports and the cross-sectional study design limits the possibility of making causal inferences, the new constructs introduced add to previous research.

Children’s Emotional and Behavioral Problems and Their Mothers’ Labor Supply

PubMed Central

Gaskin, Darrell J.; Alexandre, Pierre K.; Burke, Laura S.; Younis, Mustafa

2014-01-01

It has been documented that about 20% of children and adolescents suffer from a diagnosable mental or addictive disorder in the United States. The high prevalence of children’s emotional and behavioral problems (EBP) might have a negative effect on their mothers’ labor market outcomes because children with EBP require additional time for treatment. However, these children may require additional financial resources, which might promote mothers’ labor supply. Previous studies have only considered chronic conditions in analyzing the impact of children’s health on parental work activities. Moreover, most of these studies have not accounted for endogeneity in children’s health. This article estimates the effects of children’s EBP on their mothers’ labor supply by family structure while accounting for endogeneity in children’s health. We used the 1997 and 2002 Child Development Supplements (CDS) to the Panel Study of Income Dynamics (PSID). We used probit and bivariate probit models to estimate mothers’ probability of employment, and tobit and instrumental variable tobit models to estimate the effects of children’s EBP on their mothers’ work hours. Findings show negative effects of children’s EBP on their married mothers’ employment and on their single mothers’ work hours. PMID:25466413

Z2Pack: Numerical implementation of hybrid Wannier centers for identifying topological materials

NASA Astrophysics Data System (ADS)

Gresch, Dominik; Autès, Gabriel; Yazyev, Oleg V.; Troyer, Matthias; Vanderbilt, David; Bernevig, B. Andrei; Soluyanov, Alexey A.

2017-02-01

The intense theoretical and experimental interest in topological insulators and semimetals has established band structure topology as a fundamental material property. Consequently, identifying band topologies has become an important, but often challenging, problem, with no exhaustive solution at the present time. In this work we compile a series of techniques, some previously known, that allow for a solution to this problem for a large set of the possible band topologies. The method is based on tracking hybrid Wannier charge centers computed for relevant Bloch states, and it works at all levels of materials modeling: continuous k .p models, tight-binding models, and ab initio calculations. We apply the method to compute and identify Chern, Z2, and crystalline topological insulators, as well as topological semimetal phases, using real material examples. Moreover, we provide a numerical implementation of this technique (the Z2Pack software package) that is ideally suited for high-throughput screening of materials databases for compounds with nontrivial topologies. We expect that our work will allow researchers to (a) identify topological materials optimal for experimental probes, (b) classify existing compounds, and (c) reveal materials that host novel, not yet described, topological states.

The role of collaborative ontology development in the knowledge negotiation process

NASA Astrophysics Data System (ADS)

Rivera, Norma

Interdisciplinary research (IDR) collaboration can be defined as the process of integrating experts' knowledge, perspectives, and resources to advance scientific discovery. The flourishing of more complex research problems, together with the growth of scientific and technical knowledge has resulted in the need for researchers from diverse fields to provide different expertise and points of view to tackle these problems. These collaborations, however, introduce a new set of "culture" barriers as participating experts are trained to communicate in discipline-specific languages, theories, and research practices. We propose that building a common knowledge base for research using ontology development techniques can provide a starting point for interdisciplinary knowledge exchange, negotiation, and integration. The goal of this work is to extend ontology development techniques to support the knowledge negotiation process in IDR groups. Towards this goal, this work presents a methodology that extends previous work in collaborative ontology development and integrates learning strategies and tools to enhance interdisciplinary research practices. We evaluate the effectiveness of applying such methodology in three different scenarios that cover educational and research settings. The results of this evaluation confirm that integrating learning strategies can, in fact, be advantageous to overall collaborative practices in IDR groups.

Children's emotional and behavioral problems and their mothers' labor supply.

PubMed

Richard, Patrick; Gaskin, Darrell J; Alexandre, Pierre K; Burke, Laura S; Younis, Mustafa

2014-01-01

It has been documented that about 20% of children and adolescents suffer from a diagnosable mental or addictive disorder in the United States. The high prevalence of children's emotional and behavioral problems (EBP) might have a negative effect on their mothers' labor market outcomes because children with EBP require additional time for treatment. However, these children may require additional financial resources, which might promote mothers' labor supply. Previous studies have only considered chronic conditions in analyzing the impact of children's health on parental work activities. Moreover, most of these studies have not accounted for endogeneity in children's health. This article estimates the effects of children's EBP on their mothers' labor supply by family structure while accounting for endogeneity in children's health. We used the 1997 and 2002 Child Development Supplements (CDS) to the Panel Study of Income Dynamics (PSID). We used probit and bivariate probit models to estimate mothers' probability of employment, and tobit and instrumental variable tobit models to estimate the effects of children's EBP on their mothers' work hours. Findings show negative effects of children's EBP on their married mothers' employment and on their single mothers' work hours. © The Author(s) 2014.

Expatriates’ Multiple Fears, from Terrorism to Working Conditions: Development of a Model

PubMed Central

Giorgi, Gabriele; Montani, Francesco; Fiz-Perez, Javier; Arcangeli, Giulio; Mucci, Nicola

2016-01-01

Companies’ internationalization appears to be fundamental in the current globalized and competitive environment and seems important not only for organizational success, but also for societal development and sustainability. On one hand, global business increases the demand for managers for international assignment. On the other hand, emergent fears, such as terrorism, seem to be developing around the world, enhancing the risk of expatriates’ potential health problems. The purpose of this paper is to examine the relationships between the emergent concept of fear of expatriation with further workplace fears (economic crisis and dangerous working conditions) and with mental health problems. The study uses a quantitative design. Self-reported data were collected from 265 Italian expatriate workers assigned to both Italian and worldwide projects. Structural equation model analyses showed that fear of expatriation mediates the relationship of mental health with fear of economic crisis and with perceived dangerous working conditions. As expected, in addition to fear, worries of expatriation are also related to further fears. Although, the study is based on self-reports and the cross-sectional study design limits the possibility of making causal inferences, the new constructs introduced add to previous research. PMID:27790173

Study of grid independence of finite element method on MHD free convective casson fluid flow with slip effect

NASA Astrophysics Data System (ADS)

Raju, R. Srinivasa; Ramesh, K.

2018-05-01

The purpose of this work is to study the grid independence of finite element method on MHD Casson fluid flow past a vertically inclined plate filled in a porous medium in presence of chemical reaction, heat absorption, an external magnetic field and slip effect has been investigated. For this study of grid independence, a mathematical model is developed and analyzed by using appropriate mathematical technique, called finite element method. Grid study discussed with the help of numerical values of velocity, temperature and concentration profiles in tabular form. avourable comparisons with previously published work on various special cases of the problem are obtained.

Decentralised control of continuous Petri nets

NASA Astrophysics Data System (ADS)

Wang, Liewei; Wang, Xu

2017-05-01

This paper focuses on decentralised control of systems modelled by continuous Petri nets, in which a target marking control problem is discussed. In some previous works, an efficient ON/OFF strategy-based minimum-time controller was developed. Nevertheless, the convergence is only proved for subclasses like Choice-Free nets. For a general net, the pre-conditions of applying the ON/OFF strategy are not given; therefore, the application scope of the method is unclear. In this work, we provide two sufficient conditions of applying the ON/OFF strategy-based controller to general nets. Furthermore, an extended algorithm for general nets is proposed, in which control laws are computed based on some limited information, without knowing the detailed structure of subsystems.

Biometric recognition using 3D ear shape.

PubMed

Yan, Ping; Bowyer, Kevin W

2007-08-01

Previous works have shown that the ear is a promising candidate for biometric identification. However, in prior work, the preprocessing of ear images has had manual steps and algorithms have not necessarily handled problems caused by hair and earrings. We present a complete system for ear biometrics, including automated segmentation of the ear in a profile view image and 3D shape matching for recognition. We evaluated this system with the largest experimental study to date in ear biometrics, achieving a rank-one recognition rate of 97.8 percent for an identification scenario and an equal error rate of 1.2 percent for a verification scenario on a database of 415 subjects and 1,386 total probes.

A Cross-Domain Collaborative Filtering Algorithm Based on Feature Construction and Locally Weighted Linear Regression

PubMed Central

Jiang, Feng; Han, Ji-zhong

2018-01-01

Cross-domain collaborative filtering (CDCF) solves the sparsity problem by transferring rating knowledge from auxiliary domains. Obviously, different auxiliary domains have different importance to the target domain. However, previous works cannot evaluate effectively the significance of different auxiliary domains. To overcome this drawback, we propose a cross-domain collaborative filtering algorithm based on Feature Construction and Locally Weighted Linear Regression (FCLWLR). We first construct features in different domains and use these features to represent different auxiliary domains. Thus the weight computation across different domains can be converted as the weight computation across different features. Then we combine the features in the target domain and in the auxiliary domains together and convert the cross-domain recommendation problem into a regression problem. Finally, we employ a Locally Weighted Linear Regression (LWLR) model to solve the regression problem. As LWLR is a nonparametric regression method, it can effectively avoid underfitting or overfitting problem occurring in parametric regression methods. We conduct extensive experiments to show that the proposed FCLWLR algorithm is effective in addressing the data sparsity problem by transferring the useful knowledge from the auxiliary domains, as compared to many state-of-the-art single-domain or cross-domain CF methods. PMID:29623088

A Cross-Domain Collaborative Filtering Algorithm Based on Feature Construction and Locally Weighted Linear Regression.

PubMed

Yu, Xu; Lin, Jun-Yu; Jiang, Feng; Du, Jun-Wei; Han, Ji-Zhong

2018-01-01

Cross-domain collaborative filtering (CDCF) solves the sparsity problem by transferring rating knowledge from auxiliary domains. Obviously, different auxiliary domains have different importance to the target domain. However, previous works cannot evaluate effectively the significance of different auxiliary domains. To overcome this drawback, we propose a cross-domain collaborative filtering algorithm based on Feature Construction and Locally Weighted Linear Regression (FCLWLR). We first construct features in different domains and use these features to represent different auxiliary domains. Thus the weight computation across different domains can be converted as the weight computation across different features. Then we combine the features in the target domain and in the auxiliary domains together and convert the cross-domain recommendation problem into a regression problem. Finally, we employ a Locally Weighted Linear Regression (LWLR) model to solve the regression problem. As LWLR is a nonparametric regression method, it can effectively avoid underfitting or overfitting problem occurring in parametric regression methods. We conduct extensive experiments to show that the proposed FCLWLR algorithm is effective in addressing the data sparsity problem by transferring the useful knowledge from the auxiliary domains, as compared to many state-of-the-art single-domain or cross-domain CF methods.

Examining the concurrent and longitudinal relationship between diurnal cortisol rhythms and conduct problems during childhood.

PubMed

Salis, Katie Lee; Bernard, Kristin; Black, Sarah R; Dougherty, Lea R; Klein, Daniel

2016-09-01

Previous literature indicates that both hypoactivity and hyperactivity of the HPA axis may be related to conduct disorder and externalizing behaviors in young children. Using a longitudinal sample of 283 typically-developing children, the current study examined both the concurrent and the longitudinal association between HPA functioning and externalizing behavior problems, such as conduct problems. Diurnal cortisol rhythms and externalizing problems were assessed at ages 6 and 9. Results suggest that concurrent HPA functioning is not significantly related to externalizing behavior at ages 6 or 9. However, more blunted cortisol rhythms at age 6 (less change across the day from morning to evening) predicted a greater increase in externalizing behavior between age 6 and age 9 than did steeper cortisol rhythms. Further analyses revealed that this association was driven by conduct problems and aggressive behavior, rather than attention problems. The relationship between HPA functioning and subsequent externalizing behavior in children adds to the limited longitudinal work on this topic, suggesting that the association changes over time. These results may serve to clarify the inconsistencies in the cross-sectional literature, particularly with respect to young school-age children. Copyright © 2016 Elsevier Ltd. All rights reserved.

Examining the Concurrent and Longitudinal Relationship between Diurnal Cortisol Rhythms and Conduct Problems during Childhood

PubMed Central

Salis, Katie Lee; Bernard, Kristin; Black, Sarah R.; Dougherty, Lea R.; Klein, Daniel

2017-01-01

Previous literature indicates that both hypoactivity and hyperactivity of the HPA axis may be related to conduct disorder and externalizing behaviors in young children. Using a longitudinal sample of 283 typically-developing children, the current study examined both the concurrent and the longitudinal association between HPA functioning and externalizing behavior problems, such as conduct problems. Diurnal cortisol rhythms and externalizing problems were assessed at ages 6 and 9. Results suggest that concurrent HPA functioning is not significantly related to externalizing behavior at ages 6 or 9. However, more blunted cortisol rhythms at age 6 (less change across the day from morning to evening) predicted a greater increase in externalizing behavior between age 6 and age 9 than did steeper cortisol rhythms. Further analyses revealed that this association was driven by conduct problems and aggressive behavior, rather than attention problems. The relationship between HPA functioning and subsequent externalizing behavior in children adds to the limited longitudinal work on this topic, suggesting that the association changes over time. These results may serve to clarify the inconsistencies in the cross-sectional literature, particularly with respect to young school-age children. PMID:27266968

On Making a Distinguished Vertex Minimum Degree by Vertex Deletion

NASA Astrophysics Data System (ADS)

Betzler, Nadja; Bredereck, Robert; Niedermeier, Rolf; Uhlmann, Johannes

For directed and undirected graphs, we study the problem to make a distinguished vertex the unique minimum-(in)degree vertex through deletion of a minimum number of vertices. The corresponding NP-hard optimization problems are motivated by applications concerning control in elections and social network analysis. Continuing previous work for the directed case, we show that the problem is W[2]-hard when parameterized by the graph's feedback arc set number, whereas it becomes fixed-parameter tractable when combining the parameters "feedback vertex set number" and "number of vertices to delete". For the so far unstudied undirected case, we show that the problem is NP-hard and W[1]-hard when parameterized by the "number of vertices to delete". On the positive side, we show fixed-parameter tractability for several parameterizations measuring tree-likeness, including a vertex-linear problem kernel with respect to the parameter "feedback edge set number". On the contrary, we show a non-existence result concerning polynomial-size problem kernels for the combined parameter "vertex cover number and number of vertices to delete", implying corresponding nonexistence results when replacing vertex cover number by treewidth or feedback vertex set number.

Parameter identification for nonlinear aerodynamic systems

NASA Technical Reports Server (NTRS)

Pearson, Allan E.

1993-01-01

This final technical report covers a three and one-half year period preceding February 28, 1993 during which support was provided under NASA Grant NAG-1-1065. Following a general description of the system identification problem and a brief survey of methods to attack it, the basic ideas behind the approach taken in this research effort are presented. The results obtained are described with reference to the published work, including the five semiannual progress reports previously submitted and two interim technical reports.

Nickel-hydrogen separator development

NASA Technical Reports Server (NTRS)

Gonzalez-Sanabria, O. D.

1986-01-01

The separator technology is a critical element in the nickel-hydrogen (Ni-H2) systems. Previous research and development work carried out at NASA Lewis Research Center has determined that separators made from zirconium oxide (ZrO2) and potassium titanate (PKT) fibers will function satisfactorily in Ni-H2 cells without exhibiting the problems associated with the asbestos separators. A program has been established to transfer the separator technology into a commercial production line. A detailed plan of this program will be presented and the preliminary results will be discussed.

Using Hysteretic Energy to Evaluate Damping Characteristics of Hard Coating on Titanium

DTIC Science & Technology

2013-03-21

Ivancic, Frank T. The Effect of a Hard Coating on the Damping and Fatigue Life of Titanium. Air Force Institute of Technology (AU), Wright-Patterson AFB... aluminum specimens to determine the effects of losses for different grip mechanisms, a suspected problem in previous work with this method. Peak...done in a vacuum, and the nature of the free-decay test also confines strain to relatively low values for coated specimens (< 1000 µε) (Reed 2007

Phase retrieval from local measurements in two dimensions

NASA Astrophysics Data System (ADS)

Iwen, Mark; Preskitt, Brian; Saab, Rayan; Viswanathan, Aditya

2017-08-01

The phase retrieval problem has appeared in a multitude of applications for decades. While ad hoc solutions have existed since the early 1970s, recent developments have provided algorithms that offer promising theoretical guarantees under increasingly realistic assumptions. Motivated by ptychographic imaging, we generalize a recent result on phase retrieval of a one dimensional objective vector x ∈ ℂd to recover a two dimensional sample Q ∈ ℂd x d from phaseless measurements, using a tensor product formulation to extend the previous work.

ADAPT.DCU at TREC LiveQA: A Sentence Retrieval based Approach to Live Question Answering

DTIC Science & Technology

2015-11-20

list of conceptually similar questions from an index of previously asked on “ Yahoo ! An- swers”. We then extract the best matching sentences from the...answer Japanese why questions. The work in Surdeanu et al. (2011) address the problem of ranking answers to non-factoid how questions from Yahoo ...answering real questions from Yahoo ! Answers in real time. each participant needed to submit a web service application that on receiving a question responds

Experimental Measurements of Store Separation Using Dry Ice Models in a Subsonic Flow

DTIC Science & Technology

2011-03-01

slender bodies separating from rectangular cavities into low subsonic freestreams. The first part of their work presents the three phases of...aerodynamic problems relevant to separation of a thin body of revolution from rectangular cavities into subsonic or transonic flows” 13 [3]. Like many... cavity dimensions of 1.5 x 1.5 x 5.0 inches, resulting in a length-to-depth ratio of 3.33, slightly less the 3.6-6.0 used in previous research

Sociodemographic variables and social values: relationship with work-attendance problems in Brunei public- and private-sector employees.

PubMed

Mundia, Lawrence; Mahalle, Salwa; Matzin, Rohani; Zakaria, Gamal Abdul Nasir; Abdullah, Nor Zaiham Midawati

2017-01-01

The study investigated the degree to which selected sociodemographic variables and social values were related to work-attendance problems in a random sample of 860 Brunei public- and private-sector employees and the nature of this relationship. This quantitative study used the field-survey approach to administer research instruments directly to participants. This enabled the researchers to help participants who needed assistance in completing the measures properly, so as to increase the number of usable returns. Two sociodemographic variables (seeking help from a counselor/psychologist and marital status) correlated significantly with work attendance. Private-sector employees were more likely to have work-attendance problems than government workers. Both single and married employees and the chief wage earner in the household were more likely to have work-attendance issues to deal with compared to their counterparts. However, employees who sought help from a counselor/psychologist were far less likely to have work-attendance problems compared to those who did not get such help. The most significant social-value correlates with work-attendance problems were interpersonal communication, employer-employee relationship, work-stress problems, self-presentation, self-regulation, self-direction, and interpersonal trust. Self-regulation, self-direction, and satisfaction with work-related achievements significantly predicted work-attendance problems positively, while interpersonal communication problems and work-stress problems predicted work-attendance problems negatively. Low scorers on self-regulation and self-direction, as well as on satisfaction with work-related achievements, were more likely to have work-attendance problems compared to high scorers. However, low scorers on interpersonal communication and work-stress problems were less likely to have work-attendance problems compared to high-scoring peers. Ample evidence from this study showed that sociodemographic variables and social values contribute to work-attendance problems in various ways, and need to be incorporated in counseling interventions for affected employees.

Sociodemographic variables and social values: relationship with work-attendance problems in Brunei public- and private-sector employees

PubMed Central

Mundia, Lawrence; Mahalle, Salwa; Matzin, Rohani; Zakaria, Gamal Abdul Nasir; Abdullah, Nor Zaiham Midawati

2017-01-01

Objective The study investigated the degree to which selected sociodemographic variables and social values were related to work-attendance problems in a random sample of 860 Brunei public- and private-sector employees and the nature of this relationship. Materials and methods This quantitative study used the field-survey approach to administer research instruments directly to participants. This enabled the researchers to help participants who needed assistance in completing the measures properly, so as to increase the number of usable returns. Results Two sociodemographic variables (seeking help from a counselor/psychologist and marital status) correlated significantly with work attendance. Private-sector employees were more likely to have work-attendance problems than government workers. Both single and married employees and the chief wage earner in the household were more likely to have work-attendance issues to deal with compared to their counterparts. However, employees who sought help from a counselor/psychologist were far less likely to have work-attendance problems compared to those who did not get such help. The most significant social-value correlates with work-attendance problems were interpersonal communication, employer–employee relationship, work-stress problems, self-presentation, self-regulation, self-direction, and interpersonal trust. Self-regulation, self-direction, and satisfaction with work-related achievements significantly predicted work-attendance problems positively, while interpersonal communication problems and work-stress problems predicted work-attendance problems negatively. Low scorers on self-regulation and self-direction, as well as on satisfaction with work-related achievements, were more likely to have work-attendance problems compared to high scorers. However, low scorers on interpersonal communication and work-stress problems were less likely to have work-attendance problems compared to high-scoring peers. Conclusion Ample evidence from this study showed that sociodemographic variables and social values contribute to work-attendance problems in various ways, and need to be incorporated in counseling interventions for affected employees. PMID:28919763

Ideal-Magnetohydrodynamic-Stable Tilting in Field-Reversed Configurations

NASA Astrophysics Data System (ADS)

Kanno, Ryutaro; Ishida, Akio; Steinhauer, Loren

1995-02-01

The tilting mode in field-reversed configurations (FRC) is examined using ideal-magnetohydrodynamic stability theory. Tilting, a global mode, is the greatest threat for disruption of FRC confinement. Previous studies uniformly found tilting to be unstable in ideal theory: the objective here is to ascertain if stable equilibria were overlooked in past work. Solving the variational problem with the Rayleigh-Ritz technique, tilting-stable equilibria are found for sufficiently hollow current profile and sufficient racetrackness of the separatrix shape. Although these equilibria were not examined previously, the present conclusion is quite surprising. Consequently checks of the method are offered. Even so it cannot yet be claimed with complete certainty that stability has been proved: absolute confirmation of ideal-stable tilting awaits the application of more complete methods.

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

Zou, Ling; Zhao, Haihua; Zhang, Hongbin

Here, the one-dimensional water faucet problem is one of the classical benchmark problems originally proposed by Ransom to study the two-fluid two-phase flow model. With certain simplifications, such as massless gas phase and no wall and interfacial frictions, analytical solutions had been previously obtained for the transient liquid velocity and void fraction distribution. The water faucet problem and its analytical solutions have been widely used for the purposes of code assessment, benchmark and numerical verifications. In our previous study, the Ransom’s solutions were used for the mesh convergence study of a high-resolution spatial discretization scheme. It was found that, atmore » the steady state, an anticipated second-order spatial accuracy could not be achieved, when compared to the existing Ransom’s analytical solutions. A further investigation showed that the existing analytical solutions do not actually satisfy the commonly used two-fluid single-pressure two-phase flow equations. In this work, we present a new set of analytical solutions of the water faucet problem at the steady state, considering the gas phase density’s effect on pressure distribution. This new set of analytical solutions are used for mesh convergence studies, from which anticipated second-order of accuracy is achieved for the 2nd order spatial discretization scheme. In addition, extended Ransom’s transient solutions for the gas phase velocity and pressure are derived, with the assumption of decoupled liquid and gas pressures. Numerical verifications on the extended Ransom’s solutions are also presented.« less

The influence of chronic health problems on work ability and productivity at work: a longitudinal study among older employees.

PubMed

Leijten, Fenna R M; van den Heuvel, Swenne G; Ybema, Jan Fekke; van der Beek, Allard J; Robroek, Suzan J W; Burdorf, Alex

2014-09-01

This study aimed to assess the influence of chronic health problems on work ability and productivity at work among older employees using different methodological approaches in the analysis of longitudinal studies. Data from employees, aged 45-64, of the longitudinal Study on Transitions in Employment, Ability and Motivation was used (N=8411). Using three annual online questionnaires, we assessed the presence of seven chronic health problems, work ability (scale 0-10), and productivity at work (scale 0-10). Three linear regression generalized estimating equations were used. The time-lag model analyzed the relation of health problems with work ability and productivity at work after one year; the autoregressive model adjusted for work ability and productivity in the preceding year; and the third model assessed the relation of incidence and recovery with changes in work ability and productivity at work within the same year. Workers with health problems had lower work ability at one-year follow-up than workers without these health problems, varying from a 2.0% reduction with diabetes mellitus to a 9.5% reduction with psychological health problems relative to the overall mean (time-lag). Work ability of persons with health problems decreased slightly more during one-year follow-up than that of persons without these health problems, ranging from 1.4% with circulatory to 5.9% with psychological health problems (autoregressive). Incidence related to larger decreases in work ability, from 0.6% with diabetes mellitus to 19.0% with psychological health problems, than recovery related to changes in work ability, from a 1.8% decrease with circulatory to an 8.5% increase with psychological health problems (incidence-recovery). Only workers with musculoskeletal and psychological health problems had lower productivity at work at one-year follow-up than workers without those health problems (1.2% and 5.6%, respectively, time-lag). All methodological approaches indicated that chronic health problems were associated with decreased work ability and, to a much lesser extent, lower productivity at work. The choice for a particular methodological approach considerably influenced the strength of the associations, with the incidence of health problems resulting in the largest decreases in work ability and productivity at work.

Emotional Intelligence and cognitive abilities - associations and sex differences.

PubMed

Pardeller, Silvia; Frajo-Apor, Beatrice; Kemmler, Georg; Hofer, Alex

2017-09-01

In order to expand on previous research, this cross-sectional study investigated the relationship between Emotional Intelligence (EI) and cognitive abilities in healthy adults with a special focus on potential sex differences. EI was assessed by means of the Mayer-Salovey-Caruso-Emotional-Intelligence Test (MSCEIT), whereas cognitive abilities were investigated using the Brief Assessment of Cognition in Schizophrenia (BACS), which measures key aspects of cognitive functioning, i.e. verbal memory, working memory, motor speed, verbal fluency, attention and processing speed, and reasoning and problem solving. 137 subjects (65% female) with a mean age of 38.7 ± 11.8 years were included into the study. While males and females were comparable with regard to EI, men achieved significantly higher BACS composite scores and outperformed women in the BACS subscales motor speed, attention and processing speed, and reasoning and problem solving. Verbal fluency significantly predicted EI, whereas the MSCEIT subscale understanding emotions significantly predicted the BACS composite score. Our findings support previous research and emphasize the relevance of considering cognitive abilities when assessing ability EI in healthy individuals.

Heat Transfer in a Turbulent Liquid or Gas Stream

NASA Technical Reports Server (NTRS)

Latzko, H.

1944-01-01

The,theory of heat.transfer from a solid body to a liquid stream could he presented previously** only with limiting assumptions about the movement of the fluid (potential flow, laminar frictional flow). (See references 1, 2, and 3). For turbulent flow, the most important practical case, the previous theoretical considerations did not go beyond dimensionless formulas and certain conclusions as to the analogy between the friction factor and the unit thermal conductance, (See references 4, 5, 6, and 7,) In order to obtain numerical results, an experimental treatment of the problem was resorted to, which gave rise to numerous investigations because of the importance of this problem in many branches of technology. However, the results of these investigations frequently deviate from one another. The experimental results are especially dependent upon the overall dimensions and the specific proportions of the equipment. In the present work, the attempt will be made to develop systematically the theory of the heat transfer and of the dependence of the unit thermal conductance upon shape and dimensions, using as a basis the velocity distribution for turbulent flow set up by Prandtl and Von Karman.

Robust automatic line scratch detection in films.

PubMed

Newson, Alasdair; Almansa, Andrés; Gousseau, Yann; Pérez, Patrick

2014-03-01

Line scratch detection in old films is a particularly challenging problem due to the variable spatiotemporal characteristics of this defect. Some of the main problems include sensitivity to noise and texture, and false detections due to thin vertical structures belonging to the scene. We propose a robust and automatic algorithm for frame-by-frame line scratch detection in old films, as well as a temporal algorithm for the filtering of false detections. In the frame-by-frame algorithm, we relax some of the hypotheses used in previous algorithms in order to detect a wider variety of scratches. This step's robustness and lack of external parameters is ensured by the combined use of an a contrario methodology and local statistical estimation. In this manner, over-detection in textured or cluttered areas is greatly reduced. The temporal filtering algorithm eliminates false detections due to thin vertical structures by exploiting the coherence of their motion with that of the underlying scene. Experiments demonstrate the ability of the resulting detection procedure to deal with difficult situations, in particular in the presence of noise, texture, and slanted or partial scratches. Comparisons show significant advantages over previous work.

Alcohol dependence and criminal behavior: preliminary results of an association study of environmental and genetic factors in an Italian male population.

PubMed

Terranova, Claudio; Tucci, Marianna; Sartore, Daniela; Cavarzeran, Fabiano; Barzon, Luisa; Palù, Giorgio; Ferrara, Santo D

2012-09-01

The aim of this study is to propose an innovative approach evaluating the connection between alcohol use disorders and criminal behavior. The research, structured as a case-control study, was based on the analysis of environmental (social variables) and genetic factors (single nucleotide polymorphisms of glutamic acid decarboxylase) in a population (N = 173) of Italian alcohol-dependent men. Group 1 (N = 47, convicted subjects) was compared with Group 2 (N = 126, no previous criminal conduct). Grade repetition, work problems, and drug problems were statistically associated with criminal behavior. Having daily family meals together and having children were inversely related to convictions. The genotype distribution of the two groups was similar. The association between environmental factors and antisocial behavior confirms previous findings in the literature. The lack of genetic association does not exclude the role of the gamma-aminobutyric acid (GABA) system in determining antisocial behavior; further studies with larger samples are needed, together with investigation of other components of the GABA pathway. © 2012 American Academy of Forensic Sciences.

A convex optimization method for self-organization in dynamic (FSO/RF) wireless networks

NASA Astrophysics Data System (ADS)

Llorca, Jaime; Davis, Christopher C.; Milner, Stuart D.

2008-08-01

Next generation communication networks are becoming increasingly complex systems. Previously, we presented a novel physics-based approach to model dynamic wireless networks as physical systems which react to local forces exerted on network nodes. We showed that under clear atmospheric conditions the network communication energy can be modeled as the potential energy of an analogous spring system and presented a distributed mobility control algorithm where nodes react to local forces driving the network to energy minimizing configurations. This paper extends our previous work by including the effects of atmospheric attenuation and transmitted power constraints in the optimization problem. We show how our new formulation still results in a convex energy minimization problem. Accordingly, an updated force-driven mobility control algorithm is presented. Forces on mobile backbone nodes are computed as the negative gradient of the new energy function. Results show how in the presence of atmospheric obscuration stronger forces are exerted on network nodes that make them move closer to each other, avoiding loss of connectivity. We show results in terms of network coverage and backbone connectivity and compare the developed algorithms for different scenarios.

The Resistance of Spheres in Wind Tunnels and In Air

NASA Technical Reports Server (NTRS)

Bacon, D L; Reid, E G

1924-01-01

To supplement the standardization tests now in progress at several laboratories, a broad investigation of the resistance of spheres in wind tunnels and free air has been carried out by the National Advisory Committee for Aeronautics. The subject has been classed in aerodynamic research, and in consequence there is available a great mass of data from previous investigations. This material was given careful consideration in laying out the research, and explanation of practically all the disagreement between former experiments has resulted. A satisfactory confirmation of Reynolds law has been accomplished, the effect of means of support determined, the range of experiment greatly extended by work in the new variable density wind tunnel, and the effects of turbulence investigated by work in the tunnels and by towing and dropping tests in free air. It is concluded that the erratic nature of most of the previous work is due to support interference and differing turbulence conditions. While the question of support has been investigated thoroughly, a systematic and comprehensive study of the effects of scale and quality of turbulence will be necessary to complete the problem, as this phase was given only general treatment.

When is working memory important for arithmetic? The impact of strategy and age.

PubMed

Cragg, Lucy; Richardson, Sophie; Hubber, Paula J; Keeble, Sarah; Gilmore, Camilla

2017-01-01

Our ability to perform arithmetic relies heavily on working memory, the manipulation and maintenance of information in mind. Previous research has found that in adults, procedural strategies, particularly counting, rely on working memory to a greater extent than retrieval strategies. During childhood there are changes in the types of strategies employed, as well as an increase in the accuracy and efficiency of strategy execution. As such it seems likely that the role of working memory in arithmetic may also change, however children and adults have never been directly compared. This study used traditional dual-task methodology, with the addition of a control load condition, to investigate the extent to which working memory requirements for different arithmetic strategies change with age between 9-11 years, 12-14 years and young adulthood. We showed that both children and adults employ working memory when solving arithmetic problems, no matter what strategy they choose. This study highlights the importance of considering working memory in understanding the difficulties that some children and adults have with mathematics, as well as the need to include working memory in theoretical models of mathematical cognition.

A general framework for characterizing studies of brain interface technology.

PubMed

Mason, S G; Jackson, M M Moore; Birch, G E

2005-11-01

The development of brain interface (BI) technology continues to attract researchers with a wide range of backgrounds and expertise. Though the BI community is committed to accurate and objective evaluation of methods, systems, and technology, the very diversity of the methods and terminology used in the field hinders understanding and impairs technology cross-fertilization and cross-group validation of findings. Underlying this dilemma is a lack of common perspective and language. As seen in our previous works in this area, our approach to remedy this problem is to propose language in the form of taxonomy and functional models. Our intent is to document and validate our best thinking in this area and publish a perspective that will stimulate discussion. We encourage others to do the same with the belief that focused discussion on language issues will accelerate the inherently slow natural evolution of language selection and thus alleviate related problems. In this work, we propose a theoretical framework for describing BI-technology-related studies. The proposed framework is based on the theoretical concepts and terminology from classical science, assistive technology development, human-computer interaction, and previous BI-related works. Using a representative set of studies from the literature, the proposed BI study framework was shown to be complete and appropriate perspective for thoroughly characterizing a BI study. We have also demonstrated that this BI study framework is useful for (1) objectively reviewing existing BI study designs and results, (2) comparing designs and results of multiple BI studies, (3) designing new studies or objectively reporting BI study results, and (4) facilitating intra- and inter-group communication and the education of new researchers. As such, it forms a sound and appropriate basis for community discussion.

New low back pain in nurses: work activities, work stress and sedentary lifestyle.

PubMed

Yip, Vera Yin Bing

2004-05-01

Low back pain is common among nurses. Previous studies have shown that the risk of low back pain increases rapidly with greater amounts of physical work and psychological stress, but is inversely related to leisure activities. However, these previous studies were predominantly retrospective in design and not many took account of three factors simultaneously. This 12-month prospective study examined the relationships between work activities, work stress, sedentary lifestyle and new low back pain. A total of 144 nurses from six Hong Kong district hospitals completed a face-to-face baseline interview, which was followed-up by a telephone interview. The main study measures were demographic characteristics, work activities, work stress, physical leisure activities and the nature of new low back pain during the 12-month follow-up period. Level of work stress, quality of relationships at work, level of enjoyment experienced at work, and work satisfaction were self-reported. Fifty-six (38.9%) nurses reported experiencing new low back pain. Sedentary leisure time activity was not associated with new low back pain. Being comparatively new on a ward (adjusted relative risk 2.90), working in bending postures (adjusted relative risk 2.76) and poor work relationships with colleagues (adjusted relative risk 2.52) were independent predictors of new low back pain. The findings of this study suggest that low back pain is a common problem in the population of nurses in Hong Kong. Being comparatively new on a ward, bending frequently during work and having poor work relationships with colleagues are independent predictors of new low back pain. Training for high-risk work activities and ergonomic assessment of awkward work postures are essential. Moreover, relaxation and team-building workshops for nurses, especially those who are less experienced in the type of work on their current ward, are recommended.

Psychoeducation to facilitate return to work in individuals on sick leave and at risk of having a mental disorder: protocol of a randomised controlled trial.

PubMed

Pedersen, Pernille; Søgaard, Hans Jørgen; Yde, Bjarne Frostholm; Labriola, Merete; Nohr, Ellen A; Jensen, Chris

2014-12-17

Sickness absence due to poor mental health is a common problem in many Western countries. To facilitate return to work, it may be important to identify individuals on sick leave and at risk of having a mental disorder and subsequently to offer appropriate treatment. Psychoeducation alone has not previously been used as a return to work intervention, but may be a promising tool to facilitate return to work. Therefore, the aim of the study is to evaluate the effectiveness of psychoeducation designed specifically to facilitate return to work for individuals on sick leave and at risk of having a mental disorder. The psychoeducation was a supplement to the various standard offers provided by the job centres. The study is a randomised controlled trial, in which individuals on sick leave either receive psychoeducation and standard case management or standard case management alone. Participants were individuals with mental health symptoms, who had been on sick leave from part-time or full-time work or unemployment for about 4-8 weeks. The psychoeducational intervention was group-based and the course consisted of 2 hour sessions once a week for 6 weeks. The course was given by psychiatric nurses, a psychologist, a social worker, a physiotherapist and a person who had previously been on sick leave due to mental health problems. The sessions focused on stress and work life, and the purpose was to provide individuals on sick leave the skills to understand and improve their mental functioning.The primary outcome is the duration of sickness absence measured by register data. Secondary outcomes include psychological symptoms, mental health-related quality of life, and locus of control. These outcomes are measured by questionnaires at the start of the intervention and at 3 and 6 months follow-up. On the basis of this trial, the effect of psychoeducation for individuals on sick leave and at risk of having a mental disorder will be studied. The results will contribute to the continuing research on sickness absence and mental health. It will primarily show whether psychoeducation can lead to faster and sustainable return to work. Clinical Trial.gov NCT01637363. Registered 6 July 2012.

Discrete bacteria foraging optimization algorithm for graph based problems - a transition from continuous to discrete

NASA Astrophysics Data System (ADS)

Sur, Chiranjib; Shukla, Anupam

2018-03-01

Bacteria Foraging Optimisation Algorithm is a collective behaviour-based meta-heuristics searching depending on the social influence of the bacteria co-agents in the search space of the problem. The algorithm faces tremendous hindrance in terms of its application for discrete problems and graph-based problems due to biased mathematical modelling and dynamic structure of the algorithm. This had been the key factor to revive and introduce the discrete form called Discrete Bacteria Foraging Optimisation (DBFO) Algorithm for discrete problems which exceeds the number of continuous domain problems represented by mathematical and numerical equations in real life. In this work, we have mainly simulated a graph-based road multi-objective optimisation problem and have discussed the prospect of its utilisation in other similar optimisation problems and graph-based problems. The various solution representations that can be handled by this DBFO has also been discussed. The implications and dynamics of the various parameters used in the DBFO are illustrated from the point view of the problems and has been a combination of both exploration and exploitation. The result of DBFO has been compared with Ant Colony Optimisation and Intelligent Water Drops Algorithms. Important features of DBFO are that the bacteria agents do not depend on the local heuristic information but estimates new exploration schemes depending upon the previous experience and covered path analysis. This makes the algorithm better in combination generation for graph-based problems and combination generation for NP hard problems.

Asking for work adjustments or initiating behavioural changes - what makes a 'problematic co-worker' score Brownie points? An experimental study on the reactions towards colleagues with a personality disorder.

PubMed

Muschalla, Beate; Fay, Doris; Seemann, Anne

2016-10-01

People with mental disorders, especially personality disorders, often face low acceptance at work. This is particularly problematic when returning to work after sick leave, because it impedes reintegration into the former workplace. This study explores colleagues' reactions towards a problematic worker dependent on the returning person's reintegration strategy: The returning person undertaking changes in their behaviour is compared with the person requesting adjustments of the workplace. In an experimental study, 188 employed persons read one of four vignettes that described a return-to-work-situation of a problematic co-worker. Across all vignettes, the co-worker was depicted as having previously caused problems in the work team. In the first vignette, the co-worker did not change anything (control condition) when she returned to work; in the second, she asked for workplace adjustments; in the third vignette she initiated efforts to change her own behaviour; and the fourth vignette combined both workplace adjustments and behavioural change. Study participants were asked for their reactions towards the problematic co-worker. Vignettes that included a behavioural change evoked more positive reactions towards the co-worker than vignettes without any behavioural change. Asking for workplace adjustments alone did not yield more positive reactions compared to not initiating any change. When preparing employees with interactional problems for their return to work, it is not effective to only instruct them on their statutory entitlement for workplace adjustments. Instead, it is advisable to encourage them to proactively strive for behaviour changes.

Exploring the relationship between quality of life and mental health problems in children: implications for measurement and practice.

PubMed

Sharpe, Helen; Patalay, Praveetha; Fink, Elian; Vostanis, Panos; Deighton, Jessica; Wolpert, Miranda

2016-06-01

Quality of life is typically reduced in children with mental health problems. Understanding the relationship between quality of life and mental health problems and the factors that moderate this association is a pressing priority. This was a cross-sectional study involving 45,398 children aged 8-13 years from 880 schools in England. Self-reported quality of life was assessed using nine items from the KIDSCREEN-10 and mental health was assessed using the Me and My School Questionnaire. Demographic information (gender, age, ethnicity, socio-economic status) was also recorded. Quality of life was highest in children with no problems and lowest in children with both internalising and externalising problems. There was indication that quality of life may be reduced in children with internalising problems compared with externalising problems. Approximately 12 % children with mental health problems reported high quality of life. The link between mental health and quality of life was moderated by gender and age but not by socio-economic status or ethnicity. This study supports previous work showing mental health and quality of life are related but not synonymous. The findings have implications for measuring quality of life in child mental health settings and the need for approaches to support children with mental health problems that are at particular risk of poor quality of life.

QUICR-learning for Multi-Agent Coordination

NASA Technical Reports Server (NTRS)

Agogino, Adrian K.; Tumer, Kagan

2006-01-01

Coordinating multiple agents that need to perform a sequence of actions to maximize a system level reward requires solving two distinct credit assignment problems. First, credit must be assigned for an action taken at time step t that results in a reward at time step t > t. Second, credit must be assigned for the contribution of agent i to the overall system performance. The first credit assignment problem is typically addressed with temporal difference methods such as Q-learning. The second credit assignment problem is typically addressed by creating custom reward functions. To address both credit assignment problems simultaneously, we propose the "Q Updates with Immediate Counterfactual Rewards-learning" (QUICR-learning) designed to improve both the convergence properties and performance of Q-learning in large multi-agent problems. QUICR-learning is based on previous work on single-time-step counterfactual rewards described by the collectives framework. Results on a traffic congestion problem shows that QUICR-learning is significantly better than a Q-learner using collectives-based (single-time-step counterfactual) rewards. In addition QUICR-learning provides significant gains over conventional and local Q-learning. Additional results on a multi-agent grid-world problem show that the improvements due to QUICR-learning are not domain specific and can provide up to a ten fold increase in performance over existing methods.

Graphical models for optimal power flow

DOE PAGES

Dvijotham, Krishnamurthy; Chertkov, Michael; Van Hentenryck, Pascal; ...

2016-09-13

Optimal power flow (OPF) is the central optimization problem in electric power grids. Although solved routinely in the course of power grid operations, it is known to be strongly NP-hard in general, and weakly NP-hard over tree networks. In this paper, we formulate the optimal power flow problem over tree networks as an inference problem over a tree-structured graphical model where the nodal variables are low-dimensional vectors. We adapt the standard dynamic programming algorithm for inference over a tree-structured graphical model to the OPF problem. Combining this with an interval discretization of the nodal variables, we develop an approximation algorithmmore » for the OPF problem. Further, we use techniques from constraint programming (CP) to perform interval computations and adaptive bound propagation to obtain practically efficient algorithms. Compared to previous algorithms that solve OPF with optimality guarantees using convex relaxations, our approach is able to work for arbitrary tree-structured distribution networks and handle mixed-integer optimization problems. Further, it can be implemented in a distributed message-passing fashion that is scalable and is suitable for “smart grid” applications like control of distributed energy resources. In conclusion, numerical evaluations on several benchmark networks show that practical OPF problems can be solved effectively using this approach.« less

STS-42 Commander Grabe works with MWPE at IML-1 Rack 8 aboard OV-103

NASA Technical Reports Server (NTRS)

1992-01-01

STS-42 Commander Ronald J. Grabe works with the Mental Workload and Performance Evaluation Experiment (MWPE) (portable laptop computer, keyboard cursor keys, a two-axis joystick, and a track ball) at Rack 8 in the International Microgravity Laboratory 1 (IML-1) module. The test was designed as a result of difficulty experienced by crewmembers working at a computer station on a previous Space Shuttle mission. The problem was due to the workstation's design being based on Earth-bound conditions with the operator in a typical one-G standing position. For STS-42, the workstation was redesigned to evaluate the effects of microgravity on the ability of crewmembers to interact with a computer workstation. Information gained from this experiment will be used to design workstations for future Spacelab missions and Space Station Freedom (SSF).

Work-related suicide in Victoria, Australia: a broad perspective.

PubMed

Routley, Virginia Hazel; Ozanne-Smith, Joan E

2012-01-01

While unintentional work-related injury is increasingly recognised as important and preventable, population studies of the full range of work related suicides have received less attention. The objective of this study is to investigate the epidemiology of work-related suicide in Victoria, July 2000-December 2007. The study draws on a database of all work-related deaths reported to the Victorian Coroner, inclusive of broadly defined work-relatedness. Inclusion criteria for work-related suicide were at least one of: suicide means was work related, work stressors were identified in police reports to the Coroners or the Coroner's finding, the suicide method involved another person's work (e.g. rail suicide, heavy vehicle) or the suicide location was a workplace. Cases still open for investigation were excluded. Of 642 work-related suicides, 55% had an association with work stressors; 32% jumped or lay in front of a train or heavy vehicle; 7% involved a work location and 6% involved work agents. Work stressor cases identified included business difficulties, recent or previous work injury, unemployment/redundancy or conflict with supervisors/colleagues (including workplace bullying). Work-related suicide is a substantial problem, for which few detailed population wide studies are available. Further research is required to understand the contribution of work stressors and effective interventions.

On the diversity of compact objects within supernova remnants - I. A parametric model for magnetic field evolution

NASA Astrophysics Data System (ADS)

Rogers, Adam; Safi-Harb, Samar

2016-04-01

A wealth of X-ray and radio observations has revealed in the past decade a growing diversity of neutron stars (NSs) with properties spanning orders of magnitude in magnetic field strength and ages, and with emission processes explained by a range of mechanisms dictating their radiation properties. However, serious difficulties exist with the magneto-dipole model of isolated NS fields and their inferred ages, such as a large range of observed braking indices (n, with values often <3) and a mismatch between the NS and associated supernova remnant (SNR) ages. This problem arises primarily from the assumptions of a constant magnetic field with n = 3, and an initial spin period that is much smaller than the observed current period. It has been suggested that a solution to this problem involves magnetic field evolution, with some NSs having magnetic fields buried within the crust by accretion of fall-back supernova material following their birth. In this work, we explore a parametric phenomenological model for magnetic field growth that generalizes previous suggested field evolution functions, and apply it to a variety of NSs with both secure SNR associations and known ages. We explore the flexibility of the model by recovering the results of previous work on buried magnetic fields in young NSs. Our model fits suggest that apparently disparate classes of NSs may be related to one another through the time evolution of the magnetic field.

Motion-compensated compressed sensing for dynamic imaging

NASA Astrophysics Data System (ADS)

Sundaresan, Rajagopalan; Kim, Yookyung; Nadar, Mariappan S.; Bilgin, Ali

2010-08-01

The recently introduced Compressed Sensing (CS) theory explains how sparse or compressible signals can be reconstructed from far fewer samples than what was previously believed possible. The CS theory has attracted significant attention for applications such as Magnetic Resonance Imaging (MRI) where long acquisition times have been problematic. This is especially true for dynamic MRI applications where high spatio-temporal resolution is needed. For example, in cardiac cine MRI, it is desirable to acquire the whole cardiac volume within a single breath-hold in order to avoid artifacts due to respiratory motion. Conventional MRI techniques do not allow reconstruction of high resolution image sequences from such limited amount of data. Vaswani et al. recently proposed an extension of the CS framework to problems with partially known support (i.e. sparsity pattern). In their work, the problem of recursive reconstruction of time sequences of sparse signals was considered. Under the assumption that the support of the signal changes slowly over time, they proposed using the support of the previous frame as the "known" part of the support for the current frame. While this approach works well for image sequences with little or no motion, motion causes significant change in support between adjacent frames. In this paper, we illustrate how motion estimation and compensation techniques can be used to reconstruct more accurate estimates of support for image sequences with substantial motion (such as cardiac MRI). Experimental results using phantoms as well as real MRI data sets illustrate the improved performance of the proposed technique.

Classification of burn wounds using support vector machines

NASA Astrophysics Data System (ADS)

Acha, Begona; Serrano, Carmen; Palencia, Sergio; Murillo, Juan Jose

2004-05-01

The purpose of this work is to improve a previous method developed by the authors for the classification of burn wounds into their depths. The inputs of the system are color and texture information, as these are the characteristics observed by physicians in order to give a diagnosis. Our previous work consisted in segmenting the burn wound from the rest of the image and classifying the burn into its depth. In this paper we focus on the classification problem only. We already proposed to use a Fuzzy-ARTMAP neural network (NN). However, we may take advantage of new powerful classification tools such as Support Vector Machines (SVM). We apply the five-folded cross validation scheme to divide the database into training and validating sets. Then, we apply a feature selection method for each classifier, which will give us the set of features that yields the smallest classification error for each classifier. Features used to classify are first-order statistical parameters extracted from the L*, u* and v* color components of the image. The feature selection algorithms used are the Sequential Forward Selection (SFS) and the Sequential Backward Selection (SBS) methods. As data of the problem faced here are not linearly separable, the SVM was trained using some different kernels. The validating process shows that the SVM method, when using a Gaussian kernel of variance 1, outperforms classification results obtained with the rest of the classifiers, yielding an error classification rate of 0.7% whereas the Fuzzy-ARTMAP NN attained 1.6 %.

Assessing the impact of caring for a child with Dravet syndrome: Results of a caregiver survey.

PubMed

Campbell, Jonathan D; Whittington, Melanie D; Kim, Chong H; VanderVeen, Gina R; Knupp, Kelly G; Gammaitoni, Arnold

2018-03-01

The objective of this study was to describe and quantify the impact of caring for a child with Dravet syndrome (DS) on caregivers. We surveyed DS caregivers at a single institution with a large population of patient with DS. Survey domains included time spent/difficulty performing caregiving tasks (Oberst Caregiving Burden Scale, OCBS); caregiver health-related quality of life (EuroQoL 5D-5L, EQ-5D); and work/activity impairment (Work Productivity and Activity Impairment questionnaire, WPAI). Modified National Health Interview Survey (NHIS) questions were included to assess logistical challenges associated with coordinating medical care. Thirty-four primary caregivers responded, and 30/34 respondents completed the survey. From OCBS, providing transportation, personal care, and additional household tasks required the greatest caregiver time commitment; arranging for child care, communication, and managing behavioral problems presented the greatest difficulty. EuroQoL 5D-5L domains with the greatest impact on caregivers (0=none, 5=unable/extreme) were anxiety/depression (70% of respondents≥slight problems, 34%≥moderate) and discomfort/pain (57% of respondents≥slight problems, 23%≥moderate). The mean EQ-5D general health visual analogue scale (VAS) score (0=death; 100=perfect health) was 67 (range, 11-94). Respondents who scored <65 were two- to fourfold more likely to report ≥moderate time spent and difficulty managing child behavior problems and assisting with walking, suggesting that children with DS with high degrees of motor or neurodevelopmental problems have an especially high impact on caregiver health. On the WPAI, 26% of caregivers missed >1day of work in the previous week, with 43% reporting substantial impact (≥6, scale=1-10) on work productivity; 65% reported switching jobs, quitting jobs, or losing a job due to caregiving responsibilities. National Health Interview Survey responses indicated logistical burdens beyond the home; 50% of caregivers made ≥10 outpatient visits in the past year with their child with DS. Caring for patients with DS exerts physical, emotional, and time burdens on caregivers. Supportive services for DS families are identified to highlight an unmet need for DS treatments. Copyright © 2018 The Authors. Published by Elsevier Inc. All rights reserved.

Initial Implementation of Transient VERA-CS

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

Gerlach, Andrew; Kochunas, Brendan; Salko, Robert

In this milestone the capabilities of both CTF and MPACT were extended to perform coupled transient calculations. This required several small changes in MPACT to setup the problems correctly, perform the edits correctly, and call the appropriate CTF interfaces in the right order. For CTF, revisions and corrections to the transient timestepping algorithm were made, as well as the addition of a new interface subroutine to allow MPACT to drive CTF at each timestep. With the modifications completed, the initial coupled capability was demonstrated on some problems used for code verification, a hypothetical small mini-core, and a Watts Bar demonstrationmore » problem. For each of these cases the results showed good agreement with the previous MPACT internal TH feedback model that relied on a simplified fuel heat conduction model and simplified coolant treatment. After the pulse the results are notably different as expected, where the effects of convection of heat to the coolant can be observed. Areas for future work were discussed, including assessment and development of the CTF dynamic fuel deformation and gap conductance models, addition of suitable transient boiling and CHF models for the rapid heating and cooling rates seen in RIAs, additional validation and demonstration work, and areas for improvement to the code input and output capabilities.« less

Investigation on factors that contribute to the abandonment of building in construction industry in Malaysia

NASA Astrophysics Data System (ADS)

Farhayu Ariffin, Nur; Jaafar, Mohd Faizal Md; Idris Ali, Mohamad; Irwan Ramli, Noram; Muthusamy, Khairunisa; Shukor Lim, Nor Hasanah Abdul

2018-03-01

In Malaysia, the construction sector is one of the important sectors that contribute to economic growth and employments. However, a major concern facing the construction industry is the growing rate of delays in project delivery. In the worse cases, the projects were abandoned due to some reasons when the contract period ended. Abandoned building defines as construction work that has been continuously stalled for 6 months or more, during the project completion period or beyond the scheduled date of completion. When the projects become abandoned, it gives an adverse effect on many parties such as the developer, contractor, consultant and also client. According to previous researchers, the abandonment of building causes a serious problem and need some mitigation plan to avoid this problem from occurring. This study will investigate the fundamental factors that contribute to the abandonment of building and projects in Malaysia based on the current data of the abandoned building in most states in Malaysia. The data was collected from the respondents who is in the construction industry and had experience working with abandoned housing project. Form the respondents perspective, it shows that the main factor contribute to the building abandonment is due to the financial problem facing by the developer company.

Iron and aluminum soil/paleosol extractions as age/environment indicators: Some examples from a catchment in southern Ontario, Canada

NASA Astrophysics Data System (ADS)

Mahaney, William C.; Hancock, Ronald G. V.; Somelar, Peeter; Milan, Alison

2016-10-01

Various chemical extractions of Fe and Al from bulk soil samples, including Na-pyrophosphate (Fep, Alp), acid ammonium oxalate (Feo, Alo), and Na-dithionite (Fed, Ald), have been used over the last half century to distinguish soil ages over varying time frames from 102 to 106 years and even as far into antiquity as the Oligocene (30 × 106) years. Problems with mineral/chemical uniformity of sediments, free drainage of open system profiles, and variable climate over long time frames have produced problems and uncertainties as to just what each extraction removes from the bulk material analyzed. Some problems have been resolved by the work of Parfitt and Childs (1988); but some persist, especially with respect to the solubility of some extractant forms and the actual composition of others, particularly Alp, Alo, and Ald. A recent test of soils and paleosols in a fluvial chronosequence in southern Ontario illustrates the soil-paleosol evolutionary time trend over a period of ~ 11 ky, essentially post-Iroquois time in the Ontario basin (Jackson et al., 2000). This work highlights the importance of isolated, free draining weathering systems, mineral uniformity, and new relationships between secondary forms of Fed and Ald, the latter previously considered of little importance in age relationship quests.

Design space pruning heuristics and global optimization method for conceptual design of low-thrust asteroid tour missions

NASA Astrophysics Data System (ADS)

Alemany, Kristina

Electric propulsion has recently become a viable technology for spacecraft, enabling shorter flight times, fewer required planetary gravity assists, larger payloads, and/or smaller launch vehicles. With the maturation of this technology, however, comes a new set of challenges in the area of trajectory design. Because low-thrust trajectory optimization has historically required long run-times and significant user-manipulation, mission design has relied on expert-based knowledge for selecting departure and arrival dates, times of flight, and/or target bodies and gravitational swing-bys. These choices are generally based on known configurations that have worked well in previous analyses or simply on trial and error. At the conceptual design level, however, the ability to explore the full extent of the design space is imperative to locating the best solutions in terms of mass and/or flight times. Beginning in 2005, the Global Trajectory Optimization Competition posed a series of difficult mission design problems, all requiring low-thrust propulsion and visiting one or more asteroids. These problems all had large ranges on the continuous variables---launch date, time of flight, and asteroid stay times (when applicable)---as well as being characterized by millions or even billions of possible asteroid sequences. Even with recent advances in low-thrust trajectory optimization, full enumeration of these problems was not possible within the stringent time limits of the competition. This investigation develops a systematic methodology for determining a broad suite of good solutions to the combinatorial, low-thrust, asteroid tour problem. The target application is for conceptual design, where broad exploration of the design space is critical, with the goal being to rapidly identify a reasonable number of promising solutions for future analysis. The proposed methodology has two steps. The first step applies a three-level heuristic sequence developed from the physics of the problem, which allows for efficient pruning of the design space. The second phase applies a global optimization scheme to locate a broad suite of good solutions to the reduced problem. The global optimization scheme developed combines a novel branch-and-bound algorithm with a genetic algorithm and an industry-standard low-thrust trajectory optimization program to solve for the following design variables: asteroid sequence, launch date, times of flight, and asteroid stay times. The methodology is developed based on a small sample problem, which is enumerated and solved so that all possible discretized solutions are known. The methodology is then validated by applying it to a larger intermediate sample problem, which also has a known solution. Next, the methodology is applied to several larger combinatorial asteroid rendezvous problems, using previously identified good solutions as validation benchmarks. These problems include the 2nd and 3rd Global Trajectory Optimization Competition problems. The methodology is shown to be capable of achieving a reduction in the number of asteroid sequences of 6-7 orders of magnitude, in terms of the number of sequences that require low-thrust optimization as compared to the number of sequences in the original problem. More than 70% of the previously known good solutions are identified, along with several new solutions that were not previously reported by any of the competitors. Overall, the methodology developed in this investigation provides an organized search technique for the low-thrust mission design of asteroid rendezvous problems.

Impact of Cancer on Work and Education Among Adolescent and Young Adult Cancer Survivors

PubMed Central

Parsons, Helen M.; Harlan, Linda C.; Lynch, Charles F.; Hamilton, Ann S.; Wu, Xiao-Cheng; Kato, Ikuko; Schwartz, Stephen M.; Smith, Ashley W.; Keel, Gretchen; Keegan, Theresa H.M.

2012-01-01

Purpose To examine the impact of cancer on work and education in a sample of adolescent and young adult (AYA) patients with cancer. Patients and Methods By using the Adolescent and Young Adult Health Outcomes and Patient Experience Study (AYA HOPE)—a cohort of 463 recently diagnosed patients age 15 to 39 years with germ cell cancer, Hodgkin's lymphoma, non-Hodgkin's lymphoma, sarcoma, and acute lymphocytic leukemia from participating Surveillance, Epidemiology, and End Results (SEER) cancer registries—we evaluated factors associated with return to work/school after cancer diagnosis, a belief that cancer had a negative impact on plans for work/school, and reported problems with work/school after diagnosis by using descriptive statistics, χ2 tests, and multivariate logistic regression. Results More than 72% (282 of 388) of patients working or in school full-time before diagnosis had returned to full-time work or school 15 to 35 months postdiagnosis compared with 34% (14 of 41) of previously part-time workers/students, 7% (one of 14) of homemakers, and 25% (five of 20) of unemployed/disabled patients (P < .001). Among full-time workers/students before diagnosis, patients who were uninsured (odds ratio [OR], 0.21; 95% CI, 0.07 to 0.67; no insurance v employer-/school-sponsored insurance) or quit working directly after diagnosis (OR, 0.15; 95% CI, 0.06 to 0.37; quit v no change) were least likely to return. Very intensive cancer treatment and quitting work/school were associated with a belief that cancer negatively influenced plans for work/school. Finally, more than 50% of full-time workers/students reported problems with work/studies after diagnosis. Conclusion Although most AYA patients with cancer return to work after cancer, treatment intensity, not having insurance, and quitting work/school directly after diagnosis can influence work/educational outcomes. Future research should investigate underlying causes for these differences and best practices for effective transition of these cancer survivors to the workplace/school after treatment. PMID:22614977

Bipolar Ag-Zn battery

NASA Astrophysics Data System (ADS)

Giltner, L. John

1994-02-01

The silver-zinc (AgZn) battery system has been unique in its ability to safely satisfy high power demand applications with low mass and volume. However, a new generation of defense, aerospace, and commercial applications will impose even higher power demands. These new power demands can be satisfied by the development of a bipolar battery design. In this configuration the power consuming, interelectrode current conductors are eliminated while the current is then conducted via the large cross-section electrode substrate. Negative and positive active materials are applied to opposite sides of a solid silver foil substrate. In addition to reducing the weight and volume required for a specified power level, the output voltage performance is also improved as follows. Reduced weight through: elimination of the plastic cell container; elimination of plate leads and intercell connector; and elimination of internal plate current collector. Increased voltage through: elimination of resistance of current collector; elimination of resistance of plate lead; and elimination of resistance of intercell connector. EPI worked previously on development of a secondary bipolar silver zinc battery. This development demonstrated the electrical capability of the system and manufacturing techniques. One difficulty with this development was mechanical problems with the seals. However, recent improvements in plastics and adhesives should eliminate the major problem of maintaining a seal around the periphery of the bipolar module. The seal problem is not as significant for a primary battery application or for a requirement for only a few discharge cycles. A second difficulty encountered was with activation (introducing electrolyte into the cell) and with venting gas from the cell without loss of electrolyte. During previous work, the following projections for energy density were made from test data for a high power system which demonstrated in excess of 50 discharge/charge cycles. Projected system power = 100 kilowatts; discharge time = 30 seconds; discharge current density = 1.75 amps/sq in.; system weight = 86 lbs (9.7 WH/lb); and system volume = 1071 cu. in. (.78 WH/cu. in.). EPI is currently working on a development program to produce a bipolar silver-zinc battery design for NASA. The potential application would be to power electromechanical actuators for space launch vehicles.

Bipolar Ag-Zn battery

NASA Technical Reports Server (NTRS)

Giltner, L. John

1994-01-01

The silver-zinc (AgZn) battery system has been unique in its ability to safely satisfy high power demand applications with low mass and volume. However, a new generation of defense, aerospace, and commercial applications will impose even higher power demands. These new power demands can be satisfied by the development of a bipolar battery design. In this configuration the power consuming, interelectrode current conductors are eliminated while the current is then conducted via the large cross-section electrode substrate. Negative and positive active materials are applied to opposite sides of a solid silver foil substrate. In addition to reducing the weight and volume required for a specified power level, the output voltage performance is also improved as follows. Reduced weight through: elimination of the plastic cell container; elimination of plate leads and intercell connector; and elimination of internal plate current collector. Increased voltage through: elimination of resistance of current collector; elimination of resistance of plate lead; and elimination of resistance of intercell connector. EPI worked previously on development of a secondary bipolar silver zinc battery. This development demonstrated the electrical capability of the system and manufacturing techniques. One difficulty with this development was mechanical problems with the seals. However, recent improvements in plastics and adhesives should eliminate the major problem of maintaining a seal around the periphery of the bipolar module. The seal problem is not as significant for a primary battery application or for a requirement for only a few discharge cycles. A second difficulty encountered was with activation (introducing electrolyte into the cell) and with venting gas from the cell without loss of electrolyte. During previous work, the following projections for energy density were made from test data for a high power system which demonstrated in excess of 50 discharge/charge cycles. Projected system power = 100 kilowatts; discharge time = 30 seconds; discharge current density = 1.75 amps/sq in.; system weight = 86 lbs (9.7 WH/lb); and system volume = 1071 cu. in. (.78 WH/cu. in.). EPI is currently working on a development program to produce a bipolar silver-zinc battery design for NASA. The potential application would be to power electromechanical actuators for space launch vehicles.

The conformal transformation of an airfoil into a straight line and its application to the inverse problem of airfoil theory

NASA Technical Reports Server (NTRS)

Mutterperl, William

1944-01-01

A method of conformal transformation is developed that maps an airfoil into a straight line, the line being chosen as the extended chord line of the airfoil. The mapping is accomplished by operating directly with the airfoil ordinates. The absence of any preliminary transformation is found to shorten the work substantially over that of previous methods. Use is made of the superposition of solutions to obtain a rigorous counterpart of the approximate methods of thin-airfoils theory. The method is applied to the solution of the direct and inverse problems for arbitrary airfoils and pressure distributions. Numerical examples are given. Applications to more general types of regions, in particular to biplanes and to cascades of airfoils, are indicated. (author)

Enhanced, targeted sampling of high-dimensional free-energy landscapes using variationally enhanced sampling, with an application to chignolin

PubMed Central

Shaffer, Patrick; Valsson, Omar; Parrinello, Michele

2016-01-01

The capabilities of molecular simulations have been greatly extended by a number of widely used enhanced sampling methods that facilitate escaping from metastable states and crossing large barriers. Despite these developments there are still many problems which remain out of reach for these methods which has led to a vigorous effort in this area. One of the most important problems that remains unsolved is sampling high-dimensional free-energy landscapes and systems that are not easily described by a small number of collective variables. In this work we demonstrate a new way to compute free-energy landscapes of high dimensionality based on the previously introduced variationally enhanced sampling, and we apply it to the miniprotein chignolin. PMID:26787868

Designing divertor targets for uniform power load

NASA Astrophysics Data System (ADS)

Dekeyser, W.; Reiter, D.; Baelmans, M.

2015-08-01

Divertor design for next step fusion reactors heavily relies on 2D edge plasma modeling with codes as e.g. B2-EIRENE. While these codes are typically used in a design-by-analysis approach, in previous work we have shown that divertor design can alternatively be posed as a mathematical optimization problem, and solved very efficiently using adjoint methods adapted from computational aerodynamics. This approach has been applied successfully to divertor target shape design for more uniform power load. In this paper, the concept is further extended to include all contributions to the target power load, with particular focus on radiation. In a simplified test problem, we show the potential benefits of fully including the radiation load in the design cycle as compared to only assessing this load in a post-processing step.

Reciprocal Effects between Adolescent Externalizing Problems and Measures of Achievement

ERIC Educational Resources Information Center

Zimmermann, Friederike; Schütte, Kerstin; Taskinen, Päivi; Köller, Olaf

2013-01-01

Student misbehavior is a pervasive problem and may seriously affect academic achievement. Previous research hints at different effects depending on whether achievement tests or achievement judgments are used as academic outcomes. Previous research also indicates that low achievement can conversely contribute to problem behavior and that low…

Semantic relatedness for evaluation of course equivalencies

NASA Astrophysics Data System (ADS)

Yang, Beibei

Semantic relatedness, or its inverse, semantic distance, measures the degree of closeness between two pieces of text determined by their meaning. Related work typically measures semantics based on a sparse knowledge base such as WordNet or Cyc that requires intensive manual efforts to build and maintain. Other work is based on a corpus such as the Brown corpus, or more recently, Wikipedia. This dissertation proposes two approaches to applying semantic relatedness to the problem of suggesting transfer course equivalencies. Two course descriptions are given as input to feed the proposed algorithms, which output a value that can be used to help determine if the courses are equivalent. The first proposed approach uses traditional knowledge sources such as WordNet and corpora for courses from multiple fields of study. The second approach uses Wikipedia, the openly-editable encyclopedia, and it focuses on courses from a technical field such as Computer Science. This work shows that it is promising to adapt semantic relatedness to the education field for matching equivalencies between transfer courses. A semantic relatedness measure using traditional knowledge sources such as WordNet performs relatively well on non-technical courses. However, due to the "knowledge acquisition bottleneck," such a resource is not ideal for technical courses, which use an extensive and growing set of technical terms. To address the problem, this work proposes a Wikipedia-based approach which is later shown to be more correlated to human judgment compared to previous work.

A classical Perron method for existence of smooth solutions to boundary value and obstacle problems for degenerate-elliptic operators via holomorphic maps

NASA Astrophysics Data System (ADS)

Feehan, Paul M. N.

2017-09-01

We prove existence of solutions to boundary value problems and obstacle problems for degenerate-elliptic, linear, second-order partial differential operators with partial Dirichlet boundary conditions using a new version of the Perron method. The elliptic operators considered have a degeneracy along a portion of the domain boundary which is similar to the degeneracy of a model linear operator identified by Daskalopoulos and Hamilton [9] in their study of the porous medium equation or the degeneracy of the Heston operator [21] in mathematical finance. Existence of a solution to the partial Dirichlet problem on a half-ball, where the operator becomes degenerate on the flat boundary and a Dirichlet condition is only imposed on the spherical boundary, provides the key additional ingredient required for our Perron method. Surprisingly, proving existence of a solution to this partial Dirichlet problem with ;mixed; boundary conditions on a half-ball is more challenging than one might expect. Due to the difficulty in developing a global Schauder estimate and due to compatibility conditions arising where the ;degenerate; and ;non-degenerate boundaries; touch, one cannot directly apply the continuity or approximate solution methods. However, in dimension two, there is a holomorphic map from the half-disk onto the infinite strip in the complex plane and one can extend this definition to higher dimensions to give a diffeomorphism from the half-ball onto the infinite ;slab;. The solution to the partial Dirichlet problem on the half-ball can thus be converted to a partial Dirichlet problem on the slab, albeit for an operator which now has exponentially growing coefficients. The required Schauder regularity theory and existence of a solution to the partial Dirichlet problem on the slab can nevertheless be obtained using previous work of the author and C. Pop [16]. Our Perron method relies on weak and strong maximum principles for degenerate-elliptic operators, concepts of continuous subsolutions and supersolutions for boundary value and obstacle problems for degenerate-elliptic operators, and maximum and comparison principle estimates previously developed by the author [13].

Design of Composite Structures Using Knowledge-Based and Case Based Reasoning

NASA Technical Reports Server (NTRS)

Lambright, Jonathan Paul

1996-01-01

A method of using knowledge based and case based reasoning to assist designers during conceptual design tasks of composite structures was proposed. The cooperative use of heuristics, procedural knowledge, and previous similar design cases suggests a potential reduction in design cycle time and ultimately product lead time. The hypothesis of this work is that the design process of composite structures can be improved by using Case-Based Reasoning (CBR) and Knowledge-Based (KB) reasoning in the early design stages. The technique of using knowledge-based and case-based reasoning facilitates the gathering of disparate information into one location that is easily and readily available. The method suggests that the inclusion of downstream life-cycle issues into the conceptual design phase reduces potential of defective, and sub-optimal composite structures. Three industry experts were interviewed extensively. The experts provided design rules, previous design cases, and test problems. A Knowledge Based Reasoning system was developed using the CLIPS (C Language Interpretive Procedural System) environment and a Case Based Reasoning System was developed using the Design Memory Utility For Sharing Experiences (MUSE) xviii environment. A Design Characteristic State (DCS) was used to document the design specifications, constraints, and problem areas using attribute-value pair relationships. The DCS provided consistent design information between the knowledge base and case base. Results indicated that the use of knowledge based and case based reasoning provided a robust design environment for composite structures. The knowledge base provided design guidance from well defined rules and procedural knowledge. The case base provided suggestions on design and manufacturing techniques based on previous similar designs and warnings of potential problems and pitfalls. The case base complemented the knowledge base and extended the problem solving capability beyond the existence of limited well defined rules. The findings indicated that the technique is most effective when used as a design aid and not as a tool to totally automate the composites design process. Other areas of application and implications for future research are discussed.

Variable neighborhood search to solve the vehicle routing problem for hazardous materials transportation.

PubMed

Bula, Gustavo Alfredo; Prodhon, Caroline; Gonzalez, Fabio Augusto; Afsar, H Murat; Velasco, Nubia

2017-02-15

This work focuses on the Heterogeneous Fleet Vehicle Routing problem (HFVRP) in the context of hazardous materials (HazMat) transportation. The objective is to determine a set of routes that minimizes the total expected routing risk. This is a nonlinear function, and it depends on the vehicle load and the population exposed when an incident occurs. Thus, a piecewise linear approximation is used to estimate it. For solving the problem, a variant of the Variable Neighborhood Search (VNS) algorithm is employed. To improve its performance, a post-optimization procedure is implemented via a Set Partitioning (SP) problem. The SP is solved on a pool of routes obtained from executions of the local search procedure embedded on the VNS. The algorithm is tested on two sets of HFVRP instances based on literature with up to 100 nodes, these instances are modified to include vehicle and arc risk parameters. The results are competitive in terms of computational efficiency and quality attested by a comparison with Mixed Integer Linear Programming (MILP) previously proposed. Copyright © 2016 Elsevier B.V. All rights reserved.

The Subset Sum game.

PubMed

Darmann, Andreas; Nicosia, Gaia; Pferschy, Ulrich; Schauer, Joachim

2014-03-16

In this work we address a game theoretic variant of the Subset Sum problem, in which two decision makers (agents/players) compete for the usage of a common resource represented by a knapsack capacity. Each agent owns a set of integer weighted items and wants to maximize the total weight of its own items included in the knapsack. The solution is built as follows: Each agent, in turn, selects one of its items (not previously selected) and includes it in the knapsack if there is enough capacity. The process ends when the remaining capacity is too small for including any item left. We look at the problem from a single agent point of view and show that finding an optimal sequence of items to select is an [Formula: see text]-hard problem. Therefore we propose two natural heuristic strategies and analyze their worst-case performance when (1) the opponent is able to play optimally and (2) the opponent adopts a greedy strategy. From a centralized perspective we observe that some known results on the approximation of the classical Subset Sum can be effectively adapted to the multi-agent version of the problem.

The Subset Sum game☆

PubMed Central

Darmann, Andreas; Nicosia, Gaia; Pferschy, Ulrich; Schauer, Joachim

2014-01-01

In this work we address a game theoretic variant of the Subset Sum problem, in which two decision makers (agents/players) compete for the usage of a common resource represented by a knapsack capacity. Each agent owns a set of integer weighted items and wants to maximize the total weight of its own items included in the knapsack. The solution is built as follows: Each agent, in turn, selects one of its items (not previously selected) and includes it in the knapsack if there is enough capacity. The process ends when the remaining capacity is too small for including any item left. We look at the problem from a single agent point of view and show that finding an optimal sequence of items to select is an NP-hard problem. Therefore we propose two natural heuristic strategies and analyze their worst-case performance when (1) the opponent is able to play optimally and (2) the opponent adopts a greedy strategy. From a centralized perspective we observe that some known results on the approximation of the classical Subset Sum can be effectively adapted to the multi-agent version of the problem. PMID:25844012

The Double ITCZ Syndrome in GCMs: A Coupled Problem among Convection, Atmospheric and Ocean Circulations

NASA Astrophysics Data System (ADS)

Zhang, G. J.; Song, X.

2017-12-01

The double ITCZ bias has been a long-standing problem in coupled atmosphere-ocean models. A previous study indicates that uncertainty in the projection of global warming due to doubling of CO2 is closely related to the double ITCZ biases in global climate models. Thus, reducing the double ITCZ biases is not only important to getting the current climate features right, but also important to narrowing the uncertainty in future climate projection. In this work, we will first review the possible factors contributing to the ITCZ problem. Then, we will focus on atmospheric convection, presenting recent progress in alleviating the double ITCZ problem and its sensitivity to details of convective parameterization, including trigger conditions for convection onset, convective memory, entrainment rate, updraft model and closure in the NCAR CESM1. These changes together can result in dramatic improvements in the simulation of ITCZ. Results based on both atmospheric only and coupled simulations with incremental changes of convection scheme will be shown to demonstrate the roles of convection parameterization and coupled interaction between convection, atmospheric circulation and ocean circulation in the simulation of ITCZ.

Achieving Crossed Strong Barrier Coverage in Wireless Sensor Network.

PubMed

Han, Ruisong; Yang, Wei; Zhang, Li

2018-02-10

Barrier coverage has been widely used to detect intrusions in wireless sensor networks (WSNs). It can fulfill the monitoring task while extending the lifetime of the network. Though barrier coverage in WSNs has been intensively studied in recent years, previous research failed to consider the problem of intrusion in transversal directions. If an intruder knows the deployment configuration of sensor nodes, then there is a high probability that it may traverse the whole target region from particular directions, without being detected. In this paper, we introduce the concept of crossed barrier coverage that can overcome this defect. We prove that the problem of finding the maximum number of crossed barriers is NP-hard and integer linear programming (ILP) is used to formulate the optimization problem. The branch-and-bound algorithm is adopted to determine the maximum number of crossed barriers. In addition, we also propose a multi-round shortest path algorithm (MSPA) to solve the optimization problem, which works heuristically to guarantee efficiency while maintaining near-optimal solutions. Several conventional algorithms for finding the maximum number of disjoint strong barriers are also modified to solve the crossed barrier problem and for the purpose of comparison. Extensive simulation studies demonstrate the effectiveness of MSPA.

Synapse-Centric Mapping of Cortical Models to the SpiNNaker Neuromorphic Architecture

PubMed Central

Knight, James C.; Furber, Steve B.

2016-01-01

While the adult human brain has approximately 8.8 × 1010 neurons, this number is dwarfed by its 1 × 1015 synapses. From the point of view of neuromorphic engineering and neural simulation in general this makes the simulation of these synapses a particularly complex problem. SpiNNaker is a digital, neuromorphic architecture designed for simulating large-scale spiking neural networks at speeds close to biological real-time. Current solutions for simulating spiking neural networks on SpiNNaker are heavily inspired by work on distributed high-performance computing. However, while SpiNNaker shares many characteristics with such distributed systems, its component nodes have much more limited resources and, as the system lacks global synchronization, the computation performed on each node must complete within a fixed time step. We first analyze the performance of the current SpiNNaker neural simulation software and identify several problems that occur when it is used to simulate networks of the type often used to model the cortex which contain large numbers of sparsely connected synapses. We then present a new, more flexible approach for mapping the simulation of such networks to SpiNNaker which solves many of these problems. Finally we analyze the performance of our new approach using both benchmarks, designed to represent cortical connectivity, and larger, functional cortical models. In a benchmark network where neurons receive input from 8000 STDP synapses, our new approach allows 4× more neurons to be simulated on each SpiNNaker core than has been previously possible. We also demonstrate that the largest plastic neural network previously simulated on neuromorphic hardware can be run in real time using our new approach: double the speed that was previously achieved. Additionally this network contains two types of plastic synapse which previously had to be trained separately but, using our new approach, can be trained simultaneously. PMID:27683540

Use of satellite imagery for wildland resource evaluation in the Great Basin

NASA Technical Reports Server (NTRS)

Tueller, P. T. (Principal Investigator)

1973-01-01

The author has identified the following significant results. Most major vegetation types of Nevada have been mapped with success. The completed set of mosaic overlays will be more accurate and detailed than previous maps compiled by various State and Federal agencies due to the excellent vantage point that ERTS-1 data affords. This new vegetation type map will greatly aid resource agencies in their daily work. Such information as suitable grazing areas, wildlife habitat, forage production, and approximate wildland production potentials can be inferred from such a map. There has been some success in detecting vegetational changes with the use of ERTS-1 MSS imagery, but exposure differences have somewhat confounded the results. Future plans include work to solve this problem.

Generalized Robertson-Walker Space-Time Admitting Evolving Null Horizons Related to a Black Hole Event Horizon.

PubMed

Duggal, K L

2016-01-01

A new technique is used to study a family of time-dependent null horizons, called " Evolving Null Horizons " (ENHs), of generalized Robertson-Walker (GRW) space-time [Formula: see text] such that the metric [Formula: see text] satisfies a kinematic condition. This work is different from our early papers on the same issue where we used (1 + n )-splitting space-time but only some special subcases of GRW space-time have this formalism. Also, in contrast to previous work, we have proved that each member of ENHs is totally umbilical in [Formula: see text]. Finally, we show that there exists an ENH which is always a null horizon evolving into a black hole event horizon and suggest some open problems.

Origin of the asteroid belt

NASA Technical Reports Server (NTRS)

Wetherill, George W.

1989-01-01

Earlier and current concepts relevant to the origin of the asteroid belt are discussed and are considered in the framework of the solar system origin. Numerical and analytical solutions of the dynamical theory of planetesimal accumulation are characterized by bifurcations into runaway and nonrunaway solutions, and it is emphasized that the differences in time scales resulting from runaway and nonrunaway growth can be more important than conventional time scale differences determined by heliocentric distances. It is concluded that, in principle, it is possible to combine new calculations with previous work to formulate a theory of the asteroidal accumulation consistent with the meteoritic record and with work on the formation of terrestrial planets. Problems remaining to be addressed before a mature theory can be formulated are discussed.

Magnetically tunable 1D Coulomb drag: Theory

NASA Astrophysics Data System (ADS)

Tylan-Tyler, Anthony; Tang, Yuhe; Levy, Jeremy

In this work, we examine the Coulomb drag effect in 1D nanowires in close proximity, focusing on experimental parameters relevant to complex-oxide nanostructures. Previous work on this problem examined Coulomb drag through quantum point contacts, where effective capacitive coupling between the 2D leads of the system generates the drag voltage. In our case, the entire system is composed of 1D components and thus a more careful treatment of the Coulomb interactions is required. This more complex environment then leads to the ability to switch the drag voltage by an applied magnetic field without altering the current supplied to the drive system. We gratefully acknowledge financial support from ONR N00014-15-1-2847 and DOE DE-SC0014417.

An Alternate Set of Basis Functions for the Electromagnetic Solution of Arbitrarily-Shaped, Three-Dimensional, Closed, Conducting Bodies Using Method of Moments

NASA Technical Reports Server (NTRS)

Mackenzie, Anne I.; Baginski, Michael E.; Rao, Sadasiva M.

2008-01-01

In this work, we present an alternate set of basis functions, each defined over a pair of planar triangular patches, for the method of moments solution of electromagnetic scattering and radiation problems associated with arbitrarily-shaped, closed, conducting surfaces. The present basis functions are point-wise orthogonal to the pulse basis functions previously defined. The prime motivation to develop the present set of basis functions is to utilize them for the electromagnetic solution of dielectric bodies using a surface integral equation formulation which involves both electric and magnetic cur- rents. However, in the present work, only the conducting body solution is presented and compared with other data.

Workplace problems and solutions for employees with chronic diseases.

PubMed

Varekamp, I; van Dijk, F J H

2010-06-01

While many employees who have a chronic disease manage their jobs well, others are hampered in work performance, experience work-related problems and are at risk for job loss. To identify the practical and psychosocial barriers recognized by employees with chronic disease who experience work-related problems and to examine preferred work accommodations. A questionnaire was sent by mail and completed by current workers who have a chronic disease and experience serious problems at work. One hundred and twenty-two employees participated in this study. On average, they had been ill for 10 years and 44% had more than one disease. The most outstanding work-related problems were psychosocial, including work-home interference and a lack of acceptance of the chronic disease. Performing and finishing work tasks and social relationships with supervisors or colleagues were also felt to be slightly problematic. The most preferred work accommodations included fewer work hours, working from home, a slower work pace and more autonomy in planning work tasks. Almost three-quarters of the respondents were so fatigued that they were at risk of sickness absence or work disability. A chronic physical disease may lead to both practical and psychosocial problems and serious fatigue. Managing psychosocial problems may decrease fatigue.

Use cases and DEMO: aligning functional features of ICT-infrastructure to business processes.

PubMed

Maij, E; Toussaint, P J; Kalshoven, M; Poerschke, M; Zwetsloot-Schonk, J H M

2002-11-12

The proper alignment of functional features of the ICT-infrastructure to business processes is a major challenge in health care organisations. This alignment takes into account that the organisational structure not only shapes the ICT-infrastructure, but that the inverse also holds. To solve the alignment problem, relevant features of the ICT-infrastructure should be derived from the organisational structure and the influence of this envisaged ICT to the work practices should be pointed out. The objective of our study was to develop a method to solve this alignment problem. In a previous study we demonstrated the appropriateness of the business process modelling methodology Dynamic Essential Modelling of Organizations (DEMO). A proven and widely used modelling language for expressing functional features is Unified Modelling Language (UML). In the context of a specific case study at the University Medical Centre Utrecht in the Netherlands we investigated if the combined use of DEMO and UML could solve the alignment problem. The study demonstrated that the DEMO models were suited as a starting point in deriving system functionality by using the use case concept of UML. Further, the case study demonstrated that in using this approach for the alignment problem, insight is gained into the mutual influence of ICT-infrastructure and organisation structure: (a) specification of independent, re-usable components-as a set of related functionalities-is realised, and (b) a helpful representation of the current and future work practice is provided for in relation to the envisaged ICT support.

Disruptions of working memory and inhibition mediate the association between exposure to institutionalization and symptoms of attention deficit hyperactivity disorder.

PubMed

Tibu, F; Sheridan, M A; McLaughlin, K A; Nelson, C A; Fox, N A; Zeanah, C H

2016-02-01

Young children raised in institutions are exposed to extreme psychosocial deprivation that is associated with elevated risk for psychopathology and other adverse developmental outcomes. The prevalence of attention deficit hyperactivity disorder (ADHD) is particularly high in previously institutionalized children, yet the mechanisms underlying this association are poorly understood. We investigated whether deficits in executive functioning (EF) explain the link between institutionalization and ADHD. A sample of 136 children (aged 6-30 months) was recruited from institutions in Bucharest, Romania, and 72 never institutionalized community children matched for age and gender were recruited through general practitioners' offices. At 8 years of age, children's performance on a number of EF components (working memory, response inhibition and planning) was evaluated. Teachers completed the Health and Behavior Questionnaire, which assesses two core features of ADHD, inattention and impulsivity. Children with history of institutionalization had higher inattention and impulsivity than community controls, and exhibited worse performance on working memory, response inhibition and planning tasks. Lower performances on working memory and response inhibition, but not planning, partially mediated the association between early institutionalization and inattention and impulsivity symptom scales at age 8 years. Institutionalization was associated with decreased EF performance and increased ADHD symptoms. Deficits in working memory and response inhibition were specific mechanisms leading to ADHD in previously institutionalized children. These findings suggest that interventions that foster the development of EF might reduce risk for psychiatric problems in children exposed to early deprivation.

Designing teams of unattended ground sensors using genetic algorithms

NASA Astrophysics Data System (ADS)

Yilmaz, Ayse S.; McQuay, Brian N.; Wu, Annie S.; Sciortino, John C., Jr.

2004-04-01

Improvements in sensor capabilities have driven the need for automated sensor allocation and management systems. Such systems provide a penalty-free test environment and valuable input to human operators by offering candidate solutions. These abilities lead, in turn, to savings in manpower and time. Determining an optimal team of cooperating sensors for military operations is a challenging task. There is a tradeoff between the desire to decrease the cost and the need to increase the sensing capabilities of a sensor suite. This work focuses on unattended ground sensor networks consisting of teams of small, inexpensive sensors. Given a possible configuration of enemy radar, our goal isto generate sensor suites that monitor as many enemy radar as possible while minimizing cost. In previous work, we have shown that genetic algorithms (GAs) can be used to evolve successful teams of sensors for this problem. This work extends our previous work in two ways: we use an improved simulator containing a more accurate model of radar and sensor capabilities for out fitness evaluations and we introduce two new genetic operators, insertion and deletion, that are expected to improve the GA's fine tuning abilities. Empirical results show that our GA approach produces near optimal results under a variety of enemy radar configurations using sensors with varying capabilities. Detection percentage remains stable regardless of changes in the enemy radar placements.

Do work technique and musculoskeletal symptoms differ between men and women performing the same type of work tasks?

PubMed

Dahlberg, Raymond; Karlqvist, Lena; Bildt, Carina; Nykvist, Karin

2004-11-01

Musculoskeletal disorders are more common among women than among men. When comparing the difference between men and women in the prevalence of musculoskeletal disorders, methodological problems arise as men and women seldom perform the same type of activities, neither at work nor at home. The main objective of this cross-sectional case study was to compare work technique and self-reported musculoskeletal symptoms between men and women performing the same type of work tasks within a metal industry. Other factors, such as leisure activities, were also taken into consideration. Three data collection methods were used; questionnaire, interviews and systematic observations. The results from the observations revealed that women worked more frequently and during longer times with their hands above shoulder height than men. Working with hands above shoulder height is considered a risk factor for neck and shoulder disorders according to previous studies. Workplace design factors were probably a reason for differences in working technique between men and women. A higher proportion of women than men reported shoulder symptoms. Women spent more time on household activities than men, which indicates a higher total workload in paid and unpaid work.

On the verification of intransitive noninterference in mulitlevel security.

PubMed

Ben Hadj-Alouane, Nejib; Lafrance, Stéphane; Lin, Feng; Mullins, John; Yeddes, Mohamed Moez

2005-10-01

We propose an algorithmic approach to the problem of verification of the property of intransitive noninterference (INI), using tools and concepts of discrete event systems (DES). INI can be used to characterize and solve several important security problems in multilevel security systems. In a previous work, we have established the notion of iP-observability, which precisely captures the property of INI. We have also developed an algorithm for checking iP-observability by indirectly checking P-observability for systems with at most three security levels. In this paper, we generalize the results for systems with any finite number of security levels by developing a direct method for checking iP-observability, based on an insightful observation that the iP function is a left congruence in terms of relations on formal languages. To demonstrate the applicability of our approach, we propose a formal method to detect denial of service vulnerabilities in security protocols based on INI. This method is illustrated using the TCP/IP protocol. The work extends the theory of supervisory control of DES to a new application domain.

Automatic segmentation of colon glands using object-graphs.

PubMed

Gunduz-Demir, Cigdem; Kandemir, Melih; Tosun, Akif Burak; Sokmensuer, Cenk

2010-02-01

Gland segmentation is an important step to automate the analysis of biopsies that contain glandular structures. However, this remains a challenging problem as the variation in staining, fixation, and sectioning procedures lead to a considerable amount of artifacts and variances in tissue sections, which may result in huge variances in gland appearances. In this work, we report a new approach for gland segmentation. This approach decomposes the tissue image into a set of primitive objects and segments glands making use of the organizational properties of these objects, which are quantified with the definition of object-graphs. As opposed to the previous literature, the proposed approach employs the object-based information for the gland segmentation problem, instead of using the pixel-based information alone. Working with the images of colon tissues, our experiments demonstrate that the proposed object-graph approach yields high segmentation accuracies for the training and test sets and significantly improves the segmentation performance of its pixel-based counterparts. The experiments also show that the object-based structure of the proposed approach provides more tolerance to artifacts and variances in tissues.

The little death: Rigoni-Stern and the problem of sex and cancer in 20th-century biomedical research.

PubMed

Aviles, Natalie B

2015-06-01

Approaches to the organization and conduct of cancer research changed dramatically throughout the 20th century. Despite marked differences between the epidemiological approaches of the first half of the century and molecular techniques that gained dominance in the 1980s, prominent 20th-century researchers investigating the link between sexual activity and anogenital cancers continuously invoked the same 1842 treatise by Italian surgeon Domenico Rigoni-Stern, who is said to originate the problem of establishing a causal link between sex and cancer. In this article, I investigate 20th-century references to Rigoni-Stern as a case of a broader phenomenon: scientists situating their work through narratives of venerated ancestors, or originators. By explaining shifting versions of originator narratives in light of their authors' cultural context and research practices, we can reimagine as meaningful cultural symbols the references that previous scholars have treated as specious rhetorical maneuvers. In this case, references to Rigoni-Stern provide an interpretive anchor for American scientists to construct continuity between their work and a diverse historical legacy of cancer research.

On hyperbolicity and Gevrey well-posedness. Part two: Scalar or degenerate transitions

NASA Astrophysics Data System (ADS)

Morisse, Baptiste

2018-04-01

For first-order quasi-linear systems of partial differential equations, we formulate an assumption of a transition from initial hyperbolicity to ellipticity. This assumption bears on the principal symbol of the first-order operator. Under such an assumption, we prove a strong Hadamard instability for the associated Cauchy problem, namely an instantaneous defect of Hölder continuity of the flow from Gσ to L2, with 0 < σ <σ0, the limiting Gevrey index σ0 depending on the nature of the transition. We restrict here to scalar transitions, and non-scalar transitions in which the boundary of the hyperbolic zone satisfies a flatness condition. As in our previous work for initially elliptic Cauchy problems [B. Morisse, On hyperbolicity and Gevrey well-posedness. Part one: the elliptic case, arxiv:arXiv:1611.07225], the instability follows from a long-time Cauchy-Kovalevskaya construction for highly oscillating solutions. This extends recent work of N. Lerner, T. Nguyen, and B. Texier [The onset of instability in first-order systems, to appear in J. Eur. Math. Soc.].

Nonlinear Burn Control in Tokamaks using Heating, Non-axisymmetric Magnetic Fields, Isotopic fueling and Impurity injection

NASA Astrophysics Data System (ADS)

Pajares, Andres; Schuster, Eugenio

2016-10-01

Plasma density and temperature regulation in future tokamaks such as ITER is arising as one of the main problems in nuclear-fusion control research. The problem, known as burn control, is to regulate the amount of fusion power produced by the burning plasma while avoiding thermal instabilities. Prior work in the area of burn control considered different actuators, such as modulation of the auxiliary power, modulation of the fueling rate, and controlled impurity injection. More recently, the in-vessel coil system was suggested as a feasible actuator since it has the capability of modifying the plasma confinement by generating non-axisymmetric magnetic fields. In this work, a comprehensive, model-based, nonlinear burn control strategy is proposed to integrate all the previously mentioned actuators. A model to take into account the influence of the in-vessel coils on the plasma confinement is proposed based on the plasma collisionality and the density. A simulation study is carried out to show the capability of the controller to drive the system between different operating points while rejecting perturbations. Supported by the US DOE under DE-SC0010661.

A visualization framework for design and evaluation

NASA Astrophysics Data System (ADS)

Blundell, Benjamin J.; Ng, Gary; Pettifer, Steve

2006-01-01

The creation of compelling visualisation paradigms is a craft often dominated by intuition and issues of aesthetics, with relatively few models to support good design. The majority of problem cases are approached by simply applying a previously evaluated visualisation technique. A large body of work exists covering the individual aspects of visualisation design such as the human cognition aspects visualisation methods for specific problem areas, psychology studies and so forth, yet most frameworks regarding visualisation are applied after-the-fact as an evaluation measure. We present an extensible framework for visualisation aimed at structuring the design process, increasing decision traceability and delineating the notions of function, aesthetics and usability. The framework can be used to derive a set of requirements for good visualisation design and evaluating existing visualisations, presenting possible improvements. Our framework achieves this by being both broad and general, built on top of existing works, with hooks for extensions and customizations. This paper shows how existing theories of information visualisation fit into the scheme, presents our experience in the application of this framework on several designs, and offers our evaluation of the framework and the designs studied.

Syndemic Theory and HIV-Related Risk Among Young Transgender Women: The Role of Multiple, Co-Occurring Health Problems and Social Marginalization

PubMed Central

Brennan, Julia; Kuhns, Lisa M.; Johnson, Amy K.; Belzer, Marvin; Wilson, Erin C.

2012-01-01

Objectives. We assessed whether multiple psychosocial factors are additive in their relationship to sexual risk behavior and self-reported HIV status (i.e., can be characterized as a syndemic) among young transgender women and the relationship of indicators of social marginalization to psychosocial factors. Methods. Participants (n = 151) were aged 15 to 24 years and lived in Chicago or Los Angeles. We collected data on psychosocial factors (low self-esteem, polysubstance use, victimization related to transgender identity, and intimate partner violence) and social marginalization indicators (history of commercial sex work, homelessness, and incarceration) through an interviewer-administered survey. Results. Syndemic factors were positively and additively related to sexual risk behavior and self-reported HIV infection. In addition, our syndemic index was significantly related to 2 indicators of social marginalization: a history of sex work and previous incarceration. Conclusions. These findings provide evidence for a syndemic of co-occurring psychosocial and health problems in young transgender women, taking place in a context of social marginalization. PMID:22873480

Contributing factors in construction accidents.

PubMed

Haslam, R A; Hide, S A; Gibb, A G F; Gyi, D E; Pavitt, T; Atkinson, S; Duff, A R

2005-07-01

This overview paper draws together findings from previous focus group research and studies of 100 individual construction accidents. Pursuing issues raised by the focus groups, the accident studies collected qualitative information on the circumstances of each incident and the causal influences involved. Site based data collection entailed interviews with accident-involved personnel and their supervisor or manager, inspection of the accident location, and review of appropriate documentation. Relevant issues from the site investigations were then followed up with off-site stakeholders, including designers, manufacturers and suppliers. Levels of involvement of key factors in the accidents were: problems arising from workers or the work team (70% of accidents), workplace issues (49%), shortcomings with equipment (including PPE) (56%), problems with suitability and condition of materials (27%), and deficiencies with risk management (84%). Employing an ergonomics systems approach, a model is proposed, indicating the manner in which originating managerial, design and cultural factors shape the circumstances found in the work place, giving rise to the acts and conditions which, in turn, lead to accidents. It is argued that attention to the originating influences will be necessary for sustained improvement in construction safety to be achieved.

Psychosocial work factors and sleep problems: findings from the French national SIP survey.

PubMed

Chazelle, Emilie; Chastang, Jean-François; Niedhammer, Isabelle

2016-04-01

This study aimed at exploring the cross-sectional and prospective associations between psychosocial work factors and sleep problems. The study population consisted of a national representative sample of the French working population (SIP survey). The sample sizes were 7506 and 3555 for the cross-sectional and prospective analyses. Sleep problems were defined by either sleep disturbances or insufficient sleep duration at least several times a week. Psychosocial work factors included classical (job strain model factors) and emergent factors (recognition, insecurity, role/ethical conflict, emotional demands, work-life imbalance, etc.). Occupational factors related to working time/hours and physical work environment were also included as well as covariates related to factors outside work. Statistical analyses were performed using weighted Poisson regression analysis. In the cross-sectional analyses, psychological demands, low social support, low recognition, emotional demands, perception of danger, work-life imbalance and night work were found to be associated with sleep problems. In the prospective analyses, psychological demands and night work were predictive of sleep problems. Using a less conservative method, more factors were found to be associated with sleep problems. Dose-response associations were observed, showing that the more frequent the exposure to these factors, the higher the risk of sleep problems. No effect of repeated exposure was found on sleep problems. Classical and emergent psychosocial work factors were associated with sleep problems. More prospective studies and prevention policies may be needed.

Work-related burnout, job satisfaction, intent to leave, and nurse-assessed quality of care among travel nurses.

PubMed

Faller, Marcia S; Gates, Michael G; Georges, Jane M; Connelly, Cynthia D

2011-02-01

This research study examines work-related burnout, job satisfaction, nurse-assessed quality of care, and intent to leave in travel nurses, a population that has not been studied previously. Travel nurses are frequently used to supplement nursing staff in acute care hospitals, especially in times of shortage--understanding their satisfaction with the job may further illuminate the problem of nurse job dissatisfaction in general. Ordinary least-squares regression analyses were used to examine the influence of nurse and workplace characteristics on work-related burnout, job satisfaction, intent to leave, and perceived quality of care. Quality of care and job satisfaction were significantly influenced by whether a hospital held Magnet designation. As the number of patients cared for increases, there was a significant increase in work-related burnout. Work-related burnout was also significantly lower for nurses working in California. The results of this study suggest that different workplace characteristics influence the perceptions of quality of care provided at a hospital facility and the degree to which a nurse is either burned out or satisfied with his/her job.

Alcohol abuse management in primary care: an e-learning course.

PubMed

Pereira, Celina Andrade; Wen, Chao Lung; Tavares, Hermano

2015-03-01

The mental health knowledge gap challenges public health. The Alcohol Abuse Management in Primary Care (AAMPC) is an e-learning course designed to cover alcohol-related problems from the primary care perspective. The goal of this study was to verify if the AAMPC was able to enhance healthcare professionals' alcohol-related problems knowledge. One hundred subscriptions for the AAMPC were offered through the federal telehealth program. The course was instructor-led and had nine weekly classes, delivered synchronously or asynchronously, at the students' convenience, using a varied array of learning tools. At the beginning, students took a test that provided a positive score, related to critical knowledge for clinical management, and a negative score, related to misconceptions about alcohol-related problems. The test was repeated 2 months after course completion. Thirty-three students completed the course. The positive score improved significantly (p<0.001), but not the negative score. Students with previous experience with e-courses presented greater improvement on the positive score (p<0.036). Eighty-percent of the students thought the course excelled in meeting its objectives. Web conferences and video and audio recordings were the most appreciated learning tools. Course satisfaction was negatively related to frequency of Internet access (Spearman's rho=-0.455, p=0.022). E-learning was highly appreciated as a learning tool, especially by students with the least frequency of Internet use. Nonetheless, it worked better for those previously familiar with e-courses. The AAMPC e-course provided effective knowledge transmission and retention. Complementary strategies to reduce misconceptions about alcohol-related problems must be developed for the training of primary care staff.

COVARIANCE ESTIMATION USING CONJUGATE GRADIENT FOR 3D CLASSIFICATION IN CRYO-EM.

PubMed

Andén, Joakim; Katsevich, Eugene; Singer, Amit

2015-04-01

Classifying structural variability in noisy projections of biological macromolecules is a central problem in Cryo-EM. In this work, we build on a previous method for estimating the covariance matrix of the three-dimensional structure present in the molecules being imaged. Our proposed method allows for incorporation of contrast transfer function and non-uniform distribution of viewing angles, making it more suitable for real-world data. We evaluate its performance on a synthetic dataset and an experimental dataset obtained by imaging a 70S ribosome complex.

Hybrid Discrete-Continuous Markov Decision Processes

NASA Technical Reports Server (NTRS)

Feng, Zhengzhu; Dearden, Richard; Meuleau, Nicholas; Washington, Rich

2003-01-01

This paper proposes a Markov decision process (MDP) model that features both discrete and continuous state variables. We extend previous work by Boyan and Littman on the mono-dimensional time-dependent MDP to multiple dimensions. We present the principle of lazy discretization, and piecewise constant and linear approximations of the model. Having to deal with several continuous dimensions raises several new problems that require new solutions. In the (piecewise) linear case, we use techniques from partially- observable MDPs (POMDPS) to represent value functions as sets of linear functions attached to different partitions of the state space.

AN IMPORTED CASE OF ACUTE MELIOIDOSIS CAUSED BY ST881 BURKHOLDERIA PSEUDOMALLEI.

PubMed

Zong, Zhiyong; Wang, Xiaohui; Deng, Yiyun

2016-03-01

A previously healthy Chinese male working in Malaysia returned to China with high fever. A blood culture showed Burkholderia pseudomallei strain WCBP1. This isolate was sequenced, showing type, ST881, which appears to be present in Malaysia. WCP1 had unusual susceptibility to aminoglycosides and habored the Yersinia-like fimbrial gene cluster for virulence. The patient's condition deteriorated rapidly but he recovered after receiving meropenem and intensive care support. Melioidosis is a potential problem among Chinese imigrant workers with strains new to China being identified.

The optimal manufacturing batch size with rework under time-varying demand process for a finite time horizon

NASA Astrophysics Data System (ADS)

Musa, Sarah; Supadi, Siti Suzlin; Omar, Mohd

2014-07-01

Rework is one of the solutions to some of the main issues in reverse logistic and green supply chain as it reduces production cost and environmental problem. Many researchers focus on developing rework model, but to the knowledge of the author, none of them has developed a model for time-varying demand rate. In this paper, we extend previous works and develop multiple batch production system for time-varying demand rate with rework. In this model, the rework is done within the same production cycle.

Complexity reduction of rate-equations models for two-choice decision-making.

PubMed

Carrillo, José Antonio; Cordier, Stéphane; Deco, Gustavo; Mancini, Simona

2013-01-01

We are concerned with the complexity reduction of a stochastic system of differential equations governing the dynamics of a neuronal circuit describing a decision-making task. This reduction is based on the slow-fast behavior of the problem and holds on the whole phase space and not only locally around the spontaneous state. Macroscopic quantities, such as performance and reaction times, computed applying this reduction are in agreement with previous works in which the complexity reduction is locally performed at the spontaneous point by means of a Taylor expansion.

On the computation of steady Hopper flows. II: von Mises materials in various geometries

NASA Astrophysics Data System (ADS)

Gremaud, Pierre A.; Matthews, John V.; O'Malley, Meghan

2004-11-01

Similarity solutions are constructed for the flow of granular materials through hoppers. Unlike previous work, the present approach applies to nonaxisymmetric containers. The model involves ten unknowns (stresses, velocity, and plasticity function) determined by nine nonlinear first order partial differential equations together with a quadratic algebraic constraint (yield condition). A pseudospectral discretization is applied; the resulting problem is solved with a trust region method. The important role of the hopper geometry on the flow is illustrated by several numerical experiments of industrial relevance.

Pseudoracemic amino acid complexes: blind predictions for flexible two-component crystals.

PubMed

Görbitz, Carl Henrik; Dalhus, Bjørn; Day, Graeme M

2010-08-14

Ab initio prediction of the crystal packing in complexes between two flexible molecules is a particularly challenging computational chemistry problem. In this work we present results of single crystal structure determinations as well as theoretical predictions for three 1 ratio 1 complexes between hydrophobic l- and d-amino acids (pseudoracemates), known from previous crystallographic work to form structures with one of two alternative hydrogen bonding arrangements. These are accurately reproduced in the theoretical predictions together with a series of patterns that have never been observed experimentally. In this bewildering forest of potential polymorphs, hydrogen bonding arrangements and molecular conformations, the theoretical predictions succeeded, for all three complexes, in finding the correct hydrogen bonding pattern. For two of the complexes, the calculations also reproduce the exact space group and side chain orientations in the best ranked predicted structure. This includes one complex for which the observed crystal packing clearly contradicted previous experience based on experimental data for a substantial number of related amino acid complexes. The results highlight the significant recent advances that have been made in computational methods for crystal structure prediction.

Parameter Estimation as a Problem in Statistical Thermodynamics.

PubMed

Earle, Keith A; Schneider, David J

2011-03-14

In this work, we explore the connections between parameter fitting and statistical thermodynamics using the maxent principle of Jaynes as a starting point. In particular, we show how signal averaging may be described by a suitable one particle partition function, modified for the case of a variable number of particles. These modifications lead to an entropy that is extensive in the number of measurements in the average. Systematic error may be interpreted as a departure from ideal gas behavior. In addition, we show how to combine measurements from different experiments in an unbiased way in order to maximize the entropy of simultaneous parameter fitting. We suggest that fit parameters may be interpreted as generalized coordinates and the forces conjugate to them may be derived from the system partition function. From this perspective, the parameter fitting problem may be interpreted as a process where the system (spectrum) does work against internal stresses (non-optimum model parameters) to achieve a state of minimum free energy/maximum entropy. Finally, we show how the distribution function allows us to define a geometry on parameter space, building on previous work[1, 2]. This geometry has implications for error estimation and we outline a program for incorporating these geometrical insights into an automated parameter fitting algorithm.

Uniformity and nonuniformity of neural activities correlated to different insight problem solving.

PubMed

Zhao, Q; Li, Y; Shang, X; Zhou, Z; Han, L

2014-06-13

Previous studies on the neural basis of insight reflected weak consistency except for the anterior cingulate cortex. The present work adopted the semantic and homophonic punny riddle to explore the uniformity and nonuniformity of neural activities correlated to different insight problem solving. Results showed that in the early period of insight solving, the semantic and homophonic punny riddles induced a common N350-500 over the central scalp. However, during -400 to 0 ms before the riddles were solved, the semantic punny riddles induced a positive event-related potential (ERP) deflection over the temporal cortex for retrieving the extensive semantic information, while the homophonic punny riddles induced a positive ERP deflection over the temporal cortex and a negative one in the left frontal cortex which might reflect the semantic and phonological information processing respectively. Our study indicated that different insight problem solving should have the same cognitive process of detecting cognitive conflicts, but have different ways to solve the conflicts. Copyright © 2014 IBRO. Published by Elsevier Ltd. All rights reserved.

An analytic-geometric model of the effect of spherically distributed injection errors for Galileo and Ulysses spacecraft - The multi-stage problem

NASA Technical Reports Server (NTRS)

Longuski, James M.; Mcronald, Angus D.

1988-01-01

In previous work the problem of injecting the Galileo and Ulysses spacecraft from low earth orbit into their respective interplanetary trajectories has been discussed for the single stage (Centaur) vehicle. The central issue, in the event of spherically distributed injection errors, is what happens to the vehicle? The difficulties addressed in this paper involve the multi-stage problem since both Galileo and Ulysses will be utilizing the two-stage IUS system. Ulysses will also include a third stage: the PAM-S. The solution is expressed in terms of probabilities for total percentage of escape, orbit decay and reentry trajectories. Analytic solutions are found for Hill's Equations of Relative Motion (more recently called Clohessy-Wiltshire Equations) for multi-stage injections. These solutions are interpreted geometrically on the injection sphere. The analytic-geometric models compare well with numerical solutions, provide insight into the behavior of trajectories mapped on the injection sphere and simplify the numerical two-dimensional search for trajectory families.

Study of flow over object problems by a nodal discontinuous Galerkin-lattice Boltzmann method

NASA Astrophysics Data System (ADS)

Wu, Jie; Shen, Meng; Liu, Chen

2018-04-01

The flow over object problems are studied by a nodal discontinuous Galerkin-lattice Boltzmann method (NDG-LBM) in this work. Different from the standard lattice Boltzmann method, the current method applies the nodal discontinuous Galerkin method into the streaming process in LBM to solve the resultant pure convection equation, in which the spatial discretization is completed on unstructured grids and the low-storage explicit Runge-Kutta scheme is used for time marching. The present method then overcomes the disadvantage of standard LBM for depending on the uniform meshes. Moreover, the collision process in the LBM is completed by using the multiple-relaxation-time scheme. After the validation of the NDG-LBM by simulating the lid-driven cavity flow, the simulations of flows over a fixed circular cylinder, a stationary airfoil and rotating-stationary cylinders are performed. Good agreement of present results with previous results is achieved, which indicates that the current NDG-LBM is accurate and effective for flow over object problems.

Improving information filtering via network manipulation

NASA Astrophysics Data System (ADS)

Zhang, Fuguo; Zeng, An

2012-12-01

The recommender system is a very promising way to address the problem of overabundant information for online users. Although the information filtering for the online commercial systems has received much attention recently, almost all of the previous works are dedicated to design new algorithms and consider the user-item bipartite networks as given and constant information. However, many problems for recommender systems such as the cold-start problem (i.e., low recommendation accuracy for the small-degree items) are actually due to the limitation of the underlying user-item bipartite networks. In this letter, we propose a strategy to enhance the performance of the already existing recommendation algorithms by directly manipulating the user-item bipartite networks, namely adding some virtual connections to the networks. Numerical analyses on two benchmark data sets, MovieLens and Netflix, show that our method can remarkably improves the recommendation performance. Specifically, it not only improves the recommendations accuracy (especially for the small-degree items), but also helps the recommender systems generate more diverse and novel recommendations.

Integer Linear Programming for Constrained Multi-Aspect Committee Review Assignment

PubMed Central

Karimzadehgan, Maryam; Zhai, ChengXiang

2011-01-01

Automatic review assignment can significantly improve the productivity of many people such as conference organizers, journal editors and grant administrators. A general setup of the review assignment problem involves assigning a set of reviewers on a committee to a set of documents to be reviewed under the constraint of review quota so that the reviewers assigned to a document can collectively cover multiple topic aspects of the document. No previous work has addressed such a setup of committee review assignments while also considering matching multiple aspects of topics and expertise. In this paper, we tackle the problem of committee review assignment with multi-aspect expertise matching by casting it as an integer linear programming problem. The proposed algorithm can naturally accommodate any probabilistic or deterministic method for modeling multiple aspects to automate committee review assignments. Evaluation using a multi-aspect review assignment test set constructed using ACM SIGIR publications shows that the proposed algorithm is effective and efficient for committee review assignments based on multi-aspect expertise matching. PMID:22711970

Exploring Psychosocial Mechanisms and Interactions: Links Between Adolescent Emotional Distress, School Connectedness, and Educational Achievement

PubMed Central

Pate, Christina M.; Maras, Melissa A.; Whitney, Stephen D.; Bradshaw, Catherine P.

2017-01-01

Internalizing mental health issues are a significant developmental and clinical concern during adolescence, but rarely identified as a problem among school staff. Using data from the National Longitudinal Study of Adolescent Health, this study examined the associations between adolescent emotional distress, school connectedness, and educational achievement by exploring potential mechanistic and interactive roles of perceived school connectedness on the emotion–education association. Emotional distress was negatively associated with adolescents’ perceptions of belonging to school, which, in turn, may negatively influence educational achievement. School connectedness also had both additive and multiplicative interaction effects on the emotion–education relationship. Results support previous evidence of school connectedness as a protective factor for adolescents with internalizing mental health concerns, although much of the work to date has focused on externalizing problems. This study informs our understanding of how, why, and for whom emotional problems influence educational outcomes in light of social support in the school context. PMID:28947921

On the computation of molecular surface correlations for protein docking using fourier techniques.

PubMed

Sakk, Eric

2007-08-01

The computation of surface correlations using a variety of molecular models has been applied to the unbound protein docking problem. Because of the computational complexity involved in examining all possible molecular orientations, the fast Fourier transform (FFT) (a fast numerical implementation of the discrete Fourier transform (DFT)) is generally applied to minimize the number of calculations. This approach is rooted in the convolution theorem which allows one to inverse transform the product of two DFTs in order to perform the correlation calculation. However, such a DFT calculation results in a cyclic or "circular" correlation which, in general, does not lead to the same result as the linear correlation desired for the docking problem. In this work, we provide computational bounds for constructing molecular models used in the molecular surface correlation problem. The derived bounds are then shown to be consistent with various intuitive guidelines previously reported in the protein docking literature. Finally, these bounds are applied to different molecular models in order to investigate their effect on the correlation calculation.

Artificial neural network methods in quantum mechanics

NASA Astrophysics Data System (ADS)

Lagaris, I. E.; Likas, A.; Fotiadis, D. I.

1997-08-01

In a previous article we have shown how one can employ Artificial Neural Networks (ANNs) in order to solve non-homogeneous ordinary and partial differential equations. In the present work we consider the solution of eigenvalue problems for differential and integrodifferential operators, using ANNs. We start by considering the Schrödinger equation for the Morse potential that has an analytically known solution, to test the accuracy of the method. We then proceed with the Schrödinger and the Dirac equations for a muonic atom, as well as with a nonlocal Schrödinger integrodifferential equation that models the n + α system in the framework of the resonating group method. In two dimensions we consider the well-studied Henon-Heiles Hamiltonian and in three dimensions the model problem of three coupled anharmonic oscillators. The method in all of the treated cases proved to be highly accurate, robust and efficient. Hence it is a promising tool for tackling problems of higher complexity and dimensionality.

Perspectives on the geographic stability and mobility of people in cities

PubMed Central

Hanson, Susan

2005-01-01

A class of questions in the human environment sciences focuses on the relationship between individual or household behavior and local geographic context. Central to these questions is the nature of people's geographic mobility as well as the duration of their locational stability at varying spatial and temporal scales. The problem for researchers is that the processes of mobility/stability are temporally and spatially dynamic and therefore difficult to measure. Whereas time and space are continuous, analysts must select levels of aggregation for both length of time in place and spatial scale of place that fit with the problem in question. Previous work has emphasized mobility and suppressed stability as an analytic category. I focus here on stability and show how analyzing individuals' stability requires also analyzing their mobility. Through an empirical example centered on the relationship between entrepreneurship and place, I demonstrate how a spotlight on stability illuminates a resolution to the measurement problem by highlighting the interdependence between the time and space dimensions of stability/mobility. PMID:16230616

Listening to food workers: Factors that impact proper health and hygiene practice in food service.

PubMed

Clayton, Megan L; Clegg Smith, Katherine; Neff, Roni A; Pollack, Keshia M; Ensminger, Margaret

2015-01-01

Foodborne disease is a significant problem worldwide. Research exploring sources of outbreaks indicates a pronounced role for food workers' improper health and hygiene practice. To investigate food workers' perceptions of factors that impact proper food safety practice. Interviews with food service workers in Baltimore, MD, USA discussing food safety practices and factors that impact implementation in the workplace. A social ecological model organizes multiple levels of influence on health and hygiene behavior. Issues raised by interviewees include factors across the five levels of the social ecological model, and confirm findings from previous work. Interviews also reveal many factors not highlighted in prior work, including issues with food service policies and procedures, working conditions (e.g., pay and benefits), community resources, and state and federal policies. Food safety interventions should adopt an ecological orientation that accounts for factors at multiple levels, including workers' social and structural context, that impact food safety practice.

The riddle of Tasmanian languages

PubMed Central

Bowern, Claire

2012-01-01

Recent work which combines methods from linguistics and evolutionary biology has been fruitful in discovering the history of major language families because of similarities in evolutionary processes. Such work opens up new possibilities for language research on previously unsolvable problems, especially in areas where information from other sources may be lacking. I use phylogenetic methods to investigate Tasmanian languages. Existing materials are so fragmentary that scholars have been unable to discover how many languages are represented in the sources. Using a clustering algorithm which identifies admixture, source materials representing more than one language are identified. Using the Neighbor-Net algorithm, 12 languages are identified in five clusters. Bayesian phylogenetic methods reveal that the families are not demonstrably related; an important result, given the importance of Tasmanian Aborigines for information about how societies have responded to population collapse in prehistory. This work provides insight into the societies of prehistoric Tasmania and illustrates a new utility of phylogenetics in reconstructing linguistic history. PMID:23015621

Effective Coping With Supervisor Conflict Depends on Control: Implications for Work Strains.

PubMed

Eatough, Erin M; Chang, Chu-Hsiang

2018-01-11

This study examined the interactive effects of interpersonal conflict at work, coping strategy, and perceived control specific to the conflict on employee work strain using multisource and time-lagged data across two samples. In Sample 1, multisource data was collected from 438 employees as well as data from participant-identified secondary sources (e.g., significant others, best friends). In Sample 2, time-lagged data from 100 full-time employees was collected in a constructive replication. Overall, findings suggested that the success of coping efforts as indicated by lower strains hinges on the combination of the severity of the stressor, perceived control over the stressor, and coping strategy used (problem-focused vs. emotion-focused coping). Results from the current study provide insights for why previous efforts to document the moderating effects of coping have been inconsistent, especially with regards to emotion-focused coping. (PsycINFO Database Record (c) 2018 APA, all rights reserved).

IAA Space Terminological Multilingual Data Bank Towards an On- Line Dictionary with Definitions in French and in English

NASA Astrophysics Data System (ADS)

Bensaid, R.

2002-01-01

It has been emphasized in previous papers that the bilingual "basic list" of the IAA multilingual terminological data bank (MTDB) needed improvement before beginning works on definitions. In this communication, in a first part, we report, on the works (corrections and additions) done to improve the scope of the "basic list" . These works have yet to be done by coordinators for the others twelve languages concerned by the IAA MTBD. In a second part, according to the decision of the IAA MTDB committee to complete the MTDB with definitions in French and in English, we describe the methodology adopted and the problems encountered to elaborate a mock-up of a space dictionary, including in a first step definitions in English and in French, of the English terms and expressions beginning by the letter "A" in the basic list.

When is working memory important for arithmetic? The impact of strategy and age

PubMed Central

Richardson, Sophie; Hubber, Paula J.; Keeble, Sarah; Gilmore, Camilla

2017-01-01

Our ability to perform arithmetic relies heavily on working memory, the manipulation and maintenance of information in mind. Previous research has found that in adults, procedural strategies, particularly counting, rely on working memory to a greater extent than retrieval strategies. During childhood there are changes in the types of strategies employed, as well as an increase in the accuracy and efficiency of strategy execution. As such it seems likely that the role of working memory in arithmetic may also change, however children and adults have never been directly compared. This study used traditional dual-task methodology, with the addition of a control load condition, to investigate the extent to which working memory requirements for different arithmetic strategies change with age between 9–11 years, 12–14 years and young adulthood. We showed that both children and adults employ working memory when solving arithmetic problems, no matter what strategy they choose. This study highlights the importance of considering working memory in understanding the difficulties that some children and adults have with mathematics, as well as the need to include working memory in theoretical models of mathematical cognition. PMID:29228008

Stress and psychiatric disorder in healthcare professionals and hospital staff.

PubMed

Weinberg, A; Creed, F

2000-02-12

Previous studies of stress in healthcare staff have indicated a probable high prevalence of distress. Whether this distress can be attributed to the stressful nature of the work situation is not clear. No previous study has used a detailed interview method to ascertain the link between stress in and outside of work and anxiety and depressive disorders. Doctors, nurses, and administrative and ancillary staff were screened using the general health questionnaire (GHQ). High scorers (GHQ>4) and matched individuals with low GHQ scores were interviewed by means of the clinical interview schedule to ascertain definite anxiety and depressive disorders (cases). Cases and controls, matched for age, sex, and occupational group were interviewed with the life events and difficulties schedule classification and an objective measure of work stress to find out the amount of stress at work and outside of work. Sociodemographic and stress variables were entered into a logistic-regression analysis to find out the variables associated with anxiety and depressive disorders. 64 cases and 64 controls were matched. Cases and controls did not differ on demographic variables but cases were less likely to have a confidant (odds ratio 0.09 [95% CI 0.01-0.79]) and more likely to have had a previous episode of psychiatric disorder (3.07 [1.10-8.57]). Cases and controls worked similar hours and had similar responsibility but cases had a greater number of objective stressful situations both in and out of work (severe event or substantial difficulty in and out of work-45 cases vs 18 controls 6.05 [2.81-13.00], p<0.001; severe chronic difficulty outside of work-27 vs 8, 5.12 [2.09-12.46], p<0.001). Cases had significantly more objective work problems than controls (median 6 vs 4, z=3.81, p<0.001). The logistic-regression analyses indicated that even after the effects of personal vulnerability to psychiatric disorder and ongoing social stress outside of work had been taken into account, stressful situations at work contributed to anxiety and depressive disorders. Both stress at work and outside of work contribute to the anxiety and depressive disorders experienced by healthcare staff. Our findings suggest that the best way to decrease the prevalence of these disorders is individual treatment, which may focus on personal difficulties outside of work, combined with organisational attempts to reduce work stress. The latter may involve more assistance for staff who have a conflict between their managerial role and clinical role.

Alkali activated solidification/stabilisation of air pollution control residues and co-fired pulverised fuel ash.

PubMed

Shirley, Robin; Black, Leon

2011-10-30

This paper examines the potential treatment by solidification/stabilisation (S/S) of air pollution control (APC) residues using only waste materials otherwise bound for disposal, namely a pulverised fuel ash (PFA) from a co-fired power station and a waste caustic solution. The use of waste materials to stabilise hazardous wastes in order to meet waste acceptance criteria (WAC) would offer an economical and efficient method for reducing the environmental impact of the hazardous waste. The potential is examined against leach limits for chlorides, sulphates and total dissolved solids, and compressive strength performance described in the WAC for stable non-reactive (SNR) hazardous waste landfill cells in England and Wales. The work demonstrates some potential for the treatment, including suitable compressive strengths to meet regulatory limits. Monolithic leach results showed good encapsulation compared to previous work using a more traditional cement binder. However, consistent with previous work, SNR WAC for chlorides was not met, suggesting the need for a washing stage. The potential problems of using a non-EN450 PFA for S/S applications were also highlighted, as well as experimental results which demonstrate the effect of ionic interactions on the mobility of phases during regulatory leach testing. Copyright © 2011 Elsevier B.V. All rights reserved.

A Kalman Filtering Perspective for Multiatlas Segmentation*

PubMed Central

Gao, Yi; Zhu, Liangjia; Cates, Joshua; MacLeod, Rob S.; Bouix, Sylvain; Tannenbaum, Allen

2016-01-01

In multiatlas segmentation, one typically registers several atlases to the novel image, and their respective segmented label images are transformed and fused to form the final segmentation. In this work, we provide a new dynamical system perspective for multiatlas segmentation, inspired by the following fact: The transformation that aligns the current atlas to the novel image can be not only computed by direct registration but also inferred from the transformation that aligns the previous atlas to the image together with the transformation between the two atlases. This process is similar to the global positioning system on a vehicle, which gets position by inquiring from the satellite and by employing the previous location and velocity—neither answer in isolation being perfect. To solve this problem, a dynamical system scheme is crucial to combine the two pieces of information; for example, a Kalman filtering scheme is used. Accordingly, in this work, a Kalman multiatlas segmentation is proposed to stabilize the global/affine registration step. The contributions of this work are twofold. First, it provides a new dynamical systematic perspective for standard independent multiatlas registrations, and it is solved by Kalman filtering. Second, with very little extra computation, it can be combined with most existing multiatlas segmentation schemes for better registration/segmentation accuracy. PMID:26807162

Don't wait to incubate: immediate versus delayed incubation in divergent thinking.

PubMed

Gilhooly, Kenneth J; Georgiou, George J; Garrison, Jane; Reston, Jon D; Sirota, Miroslav

2012-08-01

Previous evidence for the effectiveness of immediate incubation in divergent creative tasks has been weak, because earlier studies exhibited a range of methodological problems. This issue is theoretically important, as a demonstration of the effects of immediate incubation would strengthen the case for the involvement of unconscious work in incubation effects. For the present experiment, we used a creative divergent-thinking task (alternative uses) in which separate experimental groups had incubation periods that were either delayed or immediate and that consisted of either spatial or verbal tasks. Control groups were tested without incubation periods, and we carried out checks for intermittent conscious work on the target task during the incubation periods. The results showed significant incubation effects that were stronger for immediate than for delayed incubation. Performance was not different between the verbal and spatial incubation conditions, and we found no evidence for intermittent conscious working during the incubation periods. These results support a role for unconscious work in creative divergent thinking, particularly in the case of immediate incubation.

Pathways through which health influences early retirement: a qualitative study

PubMed Central

2013-01-01

Background Due to the aeging of the population, there is a societal need for workers to prolong their working lives. In the Netherlands, many employees still leave the workforce before the official retirement age of 65. Previous quantitative research showed that poor self-perceived health is a risk factor of (non-disability) early retirement. However, little is known on how poor health may lead to early retirement, and why poor health leads to early retirement in some employees, but not in others. Therefore, the present qualitative study aims to identify in which ways health influences early retirement. Methods Face-to-face semi-structured interviews were conducted with 30 employees (60–64 years) who retired before the official retirement age of 65. Participants were selected from the Study on Transitions in Employment, Ability and Motivation. The interviews were transcribed verbatim, a summary was made including a timeline, and the interviews were open coded. Results In 15 of the 30 persons, health played a role in early retirement. Both poor and good health influenced early retirement. For poor health, four pathways were identified. First, employees felt unable to work at all due to health problems. Second, health problems resulted in a self-perceived (future) decline in the ability to work, and employees chose to retire early. Third, employees with health problems were afraid of a further decline in health, and chose to retire early. Fourth, employees with poor health retired early because they felt pushed out by their employer, although they themselves did not experience a reduced work ability. A good health influenced early retirement, since persons wanted to enjoy life while their health still allowed to do so. The financial opportunity to retire sometimes triggered the influence of poor health on early retirement, and often triggered the influence of good health. Employees and employers barely discussed opportunities to prolong working life. Conclusions Poor and good health influence early retirement via several different pathways. To prolong working life, a dialogue between employers and employees and tailored work-related interventions may be helpful. PMID:23551994

Pathways through which health influences early retirement: a qualitative study.

PubMed

de Wind, Astrid; Geuskens, Goedele A; Reeuwijk, Kerstin G; Westerman, Marjan J; Ybema, Jan Fekke; Burdorf, Alex; Bongers, Paulien M; van der Beek, Allard J

2013-04-03

Due to the aging of the population, there is a societal need for workers to prolong their working lives. In the Netherlands, many employees still leave the workforce before the official retirement age of 65. Previous quantitative research showed that poor self-perceived health is a risk factor of (non-disability) early retirement. However, little is known on how poor health may lead to early retirement, and why poor health leads to early retirement in some employees, but not in others. Therefore, the present qualitative study aims to identify in which ways health influences early retirement. Face-to-face semi-structured interviews were conducted with 30 employees (60-64 years) who retired before the official retirement age of 65. Participants were selected from the Study on Transitions in Employment, Ability and Motivation. The interviews were transcribed verbatim, a summary was made including a timeline, and the interviews were open coded. In 15 of the 30 persons, health played a role in early retirement. Both poor and good health influenced early retirement. For poor health, four pathways were identified. First, employees felt unable to work at all due to health problems. Second, health problems resulted in a self-perceived (future) decline in the ability to work, and employees chose to retire early. Third, employees with health problems were afraid of a further decline in health, and chose to retire early. Fourth, employees with poor health retired early because they felt pushed out by their employer, although they themselves did not experience a reduced work ability. A good health influenced early retirement, since persons wanted to enjoy life while their health still allowed to do so. The financial opportunity to retire sometimes triggered the influence of poor health on early retirement, and often triggered the influence of good health. Employees and employers barely discussed opportunities to prolong working life. Poor and good health influence early retirement via several different pathways. To prolong working life, a dialogue between employers and employees and tailored work-related interventions may be helpful.

When Best Intentions Go Awry: The Failures of Concrete Representations to Help Solve Probability Word Problems

ERIC Educational Resources Information Center

Beitzel, Brian D.; Staley, Richard K.; DuBois, Nelson F.

2011-01-01

Previous research has cast doubt on the efficacy of utilizing external representations as an aid to solving word problems. The present study replicates previous findings that concrete representations hinder college students' ability to solve probability word problems, and extends those findings to apply to a multimedia instructional context. Our…

Trait liabilities and specific promotive processes in psychopathology: The example of suicidal behavior.

PubMed

Buchman-Schmitt, Jennifer M; Brislin, Sarah J; Venables, Noah C; Joiner, Thomas E; Patrick, Christopher J

2017-07-01

The RDoC matrix framework calls for investigation of mental health problems through analysis of core biobehavioral processes quantified and studied across multiple domains of measurement. Critics have raised concerns about RDoC, including overemphasis on biological concepts/measures and disregard for the principle of multifinality, which holds that identical biological predispositions can give rise to differing behavioral outcomes. The current work illustrates an ontogenetic process approach to addressing these concerns, focusing on biobehavioral traits corresponding to RDoC constructs as predictors, and suicidal behavior as the outcome variable. Data were collected from a young adult sample (N=105), preselected to enhance rates of suicidality. Participants completed self-report measures of traits (threat sensitivity, response inhibition) and suicide-specific processes. We show that previously reported associations for traits of threat sensitivity and weak inhibitory control with suicidal behavior are mediated by more specific suicide-promoting processes-namely, thwarted belongingness, perceived burdensomeness, and capability for suicide. The sample was relatively small and the data were cross-sectional, limiting conclusions that can be drawn from the mediation analyses. Given prior research documenting neurophysiological as well as psychological bases to these trait dispositions, the current work sets the stage for an intensive RDoC-oriented investigation of suicidal tendencies in which both traits and suicide-promoting processes are quantified using indicators from different domains of measurement. More broadly, this work illustrates how an RDoC research approach can contribute to a nuanced understanding of specific clinical problems, through consideration of how general biobehavioral liabilities interface with distinct problem-promoting processes. Copyright © 2016 Elsevier B.V. All rights reserved.

Retreatment Predictions in Odontology by means of CBR Systems.

PubMed

Campo, Livia; Aliaga, Ignacio J; De Paz, Juan F; García, Alvaro Enrique; Bajo, Javier; Villarubia, Gabriel; Corchado, Juan M

2016-01-01

The field of odontology requires an appropriate adjustment of treatments according to the circumstances of each patient. A follow-up treatment for a patient experiencing problems from a previous procedure such as endodontic therapy, for example, may not necessarily preclude the possibility of extraction. It is therefore necessary to investigate new solutions aimed at analyzing data and, with regard to the given values, determine whether dental retreatment is required. In this work, we present a decision support system which applies the case-based reasoning (CBR) paradigm, specifically designed to predict the practicality of performing or not performing a retreatment. Thus, the system uses previous experiences to provide new predictions, which is completely innovative in the field of odontology. The proposed prediction technique includes an innovative combination of methods that minimizes false negatives to the greatest possible extent. False negatives refer to a prediction favoring a retreatment when in fact it would be ineffective. The combination of methods is performed by applying an optimization problem to reduce incorrect classifications and takes into account different parameters, such as precision, recall, and statistical probabilities. The proposed system was tested in a real environment and the results obtained are promising.

Retreatment Predictions in Odontology by means of CBR Systems

PubMed Central

Campo, Livia; Aliaga, Ignacio J.; García, Alvaro Enrique; Villarubia, Gabriel; Corchado, Juan M.

2016-01-01

The field of odontology requires an appropriate adjustment of treatments according to the circumstances of each patient. A follow-up treatment for a patient experiencing problems from a previous procedure such as endodontic therapy, for example, may not necessarily preclude the possibility of extraction. It is therefore necessary to investigate new solutions aimed at analyzing data and, with regard to the given values, determine whether dental retreatment is required. In this work, we present a decision support system which applies the case-based reasoning (CBR) paradigm, specifically designed to predict the practicality of performing or not performing a retreatment. Thus, the system uses previous experiences to provide new predictions, which is completely innovative in the field of odontology. The proposed prediction technique includes an innovative combination of methods that minimizes false negatives to the greatest possible extent. False negatives refer to a prediction favoring a retreatment when in fact it would be ineffective. The combination of methods is performed by applying an optimization problem to reduce incorrect classifications and takes into account different parameters, such as precision, recall, and statistical probabilities. The proposed system was tested in a real environment and the results obtained are promising. PMID:26884749

Finite-time synchronization of fractional-order memristor-based neural networks with time delays.

PubMed

Velmurugan, G; Rakkiyappan, R; Cao, Jinde

2016-01-01

In this paper, we consider the problem of finite-time synchronization of a class of fractional-order memristor-based neural networks (FMNNs) with time delays and investigated it potentially. By using Laplace transform, the generalized Gronwall's inequality, Mittag-Leffler functions and linear feedback control technique, some new sufficient conditions are derived to ensure the finite-time synchronization of addressing FMNNs with fractional order α:1<α<2 and 0<α<1. The results from the theory of fractional-order differential equations with discontinuous right-hand sides are used to investigate the problem under consideration. The derived results are extended to some previous related works on memristor-based neural networks. Finally, three numerical examples are presented to show the effectiveness of our proposed theoretical results. Copyright © 2015 Elsevier Ltd. All rights reserved.

Contact stresses in pin-loaded orthotropic plates

NASA Technical Reports Server (NTRS)

Hyer, M. W.; Klang, E. C.

1984-01-01

The effects of pin elasticity, friction, and clearance on the stresses near the hole in a pin-loaded orthotropic plate are described. The problem is modeled as a contact elasticity problem using complex variable theory, the pin and the plate being two elastic bodies interacting through contact. This modeling is in contrast to previous works which assumed that the pin is rigid or that it exerts a known cosinusoidal radial traction on the hole boundary. Neither of these approaches explicitly involves a pin. A collocation procedure and iteration were used to obtain numerical results for a variety of plate and pin elastic properties and various levels of friction and clearance. Collocation was used to enforce the boundary and iteration was used to find the contact and no-slip regions on the boundary. Details of the numerical scheme are discussed.

Problems in merging Earth sensing satellite data sets

NASA Technical Reports Server (NTRS)

Smith, Paul H.; Goldberg, Michael J.

1987-01-01

Satellite remote sensing systems provide a tremendous source of data flow to the Earth science community. These systems provide scientists with data of types and on a scale previously unattainable. Looking forward to the capabilities of Space Station and the Earth Observing System (EOS), the full realization of the potential of satellite remote sensing will be handicapped by inadequate information systems. There is a growing emphasis in Earth science research to ask questions which are multidisciplinary in nature and global in scale. Many of these research projects emphasize the interactions of the land surface, the atmosphere, and the oceans through various physical mechanisms. Conducting this research requires large and complex data sets and teams of multidisciplinary scientists, often working at remote locations. A review of the problems of merging these large volumes of data into spatially referenced and manageable data sets is presented.

Exploration of the short-term and long-term effects of parental illness on children's educational and behavioral functioning using a large Taiwanese sample.

PubMed

Chen, Yung-Chi

2014-05-01

This study used data from Waves I and II of the Taiwan Educational Panel Survey (TEPS) to explore the potential short-term and long-term effects of parental illness and health condition on children's behavioral and educational functioning. A sample of 11,018 junior high school students and their parents and teachers in Taiwan were included in this present study. The results supported previous work that parental illness may place children at slight risk for poor psychosocial adjustment and behavioral problems. Parental illness was associated with lower adaptive skills and more behavioral problems in children. Children of ill parents showed resilience in their educational functioning in the event of parental illness as children's academic achievement and learning skills were not related to parental illness/health condition.

Automatic Constraint Detection for 2D Layout Regularization.

PubMed

Jiang, Haiyong; Nan, Liangliang; Yan, Dong-Ming; Dong, Weiming; Zhang, Xiaopeng; Wonka, Peter

2016-08-01

In this paper, we address the problem of constraint detection for layout regularization. The layout we consider is a set of two-dimensional elements where each element is represented by its bounding box. Layout regularization is important in digitizing plans or images, such as floor plans and facade images, and in the improvement of user-created contents, such as architectural drawings and slide layouts. To regularize a layout, we aim to improve the input by detecting and subsequently enforcing alignment, size, and distance constraints between layout elements. Similar to previous work, we formulate layout regularization as a quadratic programming problem. In addition, we propose a novel optimization algorithm that automatically detects constraints. We evaluate the proposed framework using a variety of input layouts from different applications. Our results demonstrate that our method has superior performance to the state of the art.

Working memory and organizational skills problems in ADHD.

PubMed

Kofler, Michael J; Sarver, Dustin E; Harmon, Sherelle L; Moltisanti, Allison; Aduen, Paula A; Soto, Elia F; Ferretti, Nicole

2018-01-01

This study tested model-driven predictions regarding working memory's role in the organizational problems associated with ADHD. Children aged 8-13 (M = 10.33, SD = 1.42) with and without ADHD (N = 103; 39 girls; 73% Caucasian/Non-Hispanic) were assessed on multiple, counterbalanced working memory tasks. Parents and teachers completed norm-referenced measures of organizational problems (Children's Organizational Skills Scale; COSS). Results confirmed large magnitude working memory deficits (d = 1.24) and organizational problems in ADHD (d = 0.85). Bias-corrected, bootstrapped conditional effects models linked impaired working memory with greater parent- and teacher-reported inattention, hyperactivity/impulsivity, and organizational problems. Working memory predicted organization problems across all parent and teacher COSS subscales (R 2  = .19-.23). Approximately 38%-57% of working memory's effect on organization problems was conveyed by working memory's association with inattentive behavior. Unique effects of working memory remained significant for both parent- and teacher-reported task planning, as well as for teacher-reported memory/materials management and overall organization problems. Attention problems uniquely predicted worse organizational skills. Hyperactivity was unrelated to parent-reported organizational skills, but predicted better teacher-reported task planning. Children with ADHD exhibit multisetting, broad-based organizational impairment. These impaired organizational skills are attributable in part to performance deficits secondary to working memory dysfunction, both directly and indirectly via working memory's role in regulating attention. Impaired working memory in ADHD renders it extraordinarily difficult for these children to consistently anticipate, plan, enact, and maintain goal-directed actions. © 2017 Association for Child and Adolescent Mental Health.

Working, declarative and procedural memory in specific language impairment

PubMed Central

Lum, Jarrad A.G.; Conti-Ramsden, Gina; Page, Debra; Ullman, Michael T.

2012-01-01

According to the Procedural Deficit Hypothesis (PDH), abnormalities of brain structures underlying procedural memory largely explain the language deficits in children with specific language impairment (SLI). These abnormalities are posited to result in core deficits of procedural memory, which in turn explain the grammar problems in the disorder. The abnormalities are also likely to lead to problems with other, non-procedural functions, such as working memory, that rely at least partly on the affected brain structures. In contrast, declarative memory is expected to remain largely intact, and should play an important compensatory role for grammar. These claims were tested by examining measures of working, declarative and procedural memory in 51 children with SLI and 51 matched typically-developing (TD) children (mean age 10). Working memory was assessed with the Working Memory Test Battery for Children, declarative memory with the Children’s Memory Scale, and procedural memory with a visuo-spatial Serial Reaction Time task. As compared to the TD children, the children with SLI were impaired at procedural memory, even when holding working memory constant. In contrast, they were spared at declarative memory for visual information, and at declarative memory in the verbal domain after controlling for working memory and language. Visuo-spatial short-term memory was intact, whereas verbal working memory was impaired, even when language deficits were held constant. Correlation analyses showed neither visuo-spatial nor verbal working memory was associated with either lexical or grammatical abilities in either the SLI or TD children. Declarative memory correlated with lexical abilities in both groups of children. Finally, grammatical abilities were associated with procedural memory in the TD children, but with declarative memory in the children with SLI. These findings replicate and extend previous studies of working, declarative and procedural memory in SLI. Overall, we suggest that the evidence largely supports the predictions of the PDH. PMID:21774923

Using a Process Dissociation Approach to Assess Verbal Short-Term Memory for Item and Order Information in a Sample of Individuals with a Self-Reported Diagnosis of Dyslexia

PubMed Central

Wang, Xiaoli; Xuan, Yifu; Jarrold, Christopher

2016-01-01

Previous studies have examined whether difficulties in short-term memory for verbal information, that might be associated with dyslexia, are driven by problems in retaining either information about to-be-remembered items or the order in which these items were presented. However, such studies have not used process-pure measures of short-term memory for item or order information. In this work we adapt a process dissociation procedure to properly distinguish the contributions of item and order processes to verbal short-term memory in a group of 28 adults with a self-reported diagnosis of dyslexia and a comparison sample of 29 adults without a dyslexia diagnosis. In contrast to previous work that has suggested that individuals with dyslexia experience item deficits resulting from inefficient phonological representation and language-independent order memory deficits, the results showed no evidence of specific problems in short-term retention of either item or order information among the individuals with a self-reported diagnosis of dyslexia, despite this group showing expected difficulties on separate measures of word and non-word reading. However, there was some suggestive evidence of a link between order memory for verbal material and individual differences in non-word reading, consistent with other claims for a role of order memory in phonologically mediated reading. The data from the current study therefore provide empirical evidence to question the extent to which item and order short-term memory are necessarily impaired in dyslexia. PMID:26941679

Using a Process Dissociation Approach to Assess Verbal Short-Term Memory for Item and Order Information in a Sample of Individuals with a Self-Reported Diagnosis of Dyslexia.

PubMed

Wang, Xiaoli; Xuan, Yifu; Jarrold, Christopher

2016-01-01

Previous studies have examined whether difficulties in short-term memory for verbal information, that might be associated with dyslexia, are driven by problems in retaining either information about to-be-remembered items or the order in which these items were presented. However, such studies have not used process-pure measures of short-term memory for item or order information. In this work we adapt a process dissociation procedure to properly distinguish the contributions of item and order processes to verbal short-term memory in a group of 28 adults with a self-reported diagnosis of dyslexia and a comparison sample of 29 adults without a dyslexia diagnosis. In contrast to previous work that has suggested that individuals with dyslexia experience item deficits resulting from inefficient phonological representation and language-independent order memory deficits, the results showed no evidence of specific problems in short-term retention of either item or order information among the individuals with a self-reported diagnosis of dyslexia, despite this group showing expected difficulties on separate measures of word and non-word reading. However, there was some suggestive evidence of a link between order memory for verbal material and individual differences in non-word reading, consistent with other claims for a role of order memory in phonologically mediated reading. The data from the current study therefore provide empirical evidence to question the extent to which item and order short-term memory are necessarily impaired in dyslexia.

Maternal pre-pregnancy obesity and risk for inattention and negative emotionality in children.

PubMed

Rodriguez, Alina

2010-02-01

This study aimed to replicate and extend previous work showing an association between maternal pre-pregnancy adiposity and risk for attention deficit hyperactivity disorder (ADHD) symptoms in children. A Swedish population-based prospective pregnancy-offspring cohort was followed up when children were 5 years old (N = 1,714). Mothers and kindergarten teachers rated children's ADHD symptoms, presence and duration of problems, and emotionality. Dichotomized outcomes examined difficulties of clinical relevance (top 15% of the distribution). Analyses adjusted for pregnancy (maternal smoking, depressive symptoms, life events, education, age, family structure), birth outcomes (birth weight, gestational age, infant sex) and concurrent variables (family structure, maternal depressive symptoms, parental ADHD symptoms, and child overweight) in an attempt to rule out confounding. Maternal pre-pregnancy overweight and obesity predicted high inattention symptom scores and obesity was associated with a two-fold increase in risk of difficulties with emotion intensity and emotion regulation according to teacher reports. Means of maternal ratings were unrelated to pre-pregnancy body mass index (BMI). Presence and duration of problems were associated with both maternal over and underweight according to teachers. Despite discrepancies between maternal and teacher reports, these results provide further evidence that maternal pre-pregnancy overweight and obesity are associated with child inattention symptoms and extend previous work by establishing a link between obesity and emotional difficulties. Maternal adiposity at the time of conception may be instrumental in programming child mental health, as prenatal brain development depends on maternal energy supply. Possible mechanisms include disturbed maternal metabolic function. If maternal pre-pregnancy obesity is a causal risk factor, the potential for prevention is great.

A divide and conquer approach to cope with uncertainty, human health risk, and decision making in contaminant hydrology

NASA Astrophysics Data System (ADS)

de Barros, Felipe P. J.; Bolster, Diogo; Sanchez-Vila, Xavier; Nowak, Wolfgang

2011-05-01

Assessing health risk in hydrological systems is an interdisciplinary field. It relies on the expertise in the fields of hydrology and public health and needs powerful translation concepts to provide decision support and policy making. Reliable health risk estimates need to account for the uncertainties and variabilities present in hydrological, physiological, and human behavioral parameters. Despite significant theoretical advancements in stochastic hydrology, there is still a dire need to further propagate these concepts to practical problems and to society in general. Following a recent line of work, we use fault trees to address the task of probabilistic risk analysis and to support related decision and management problems. Fault trees allow us to decompose the assessment of health risk into individual manageable modules, thus tackling a complex system by a structural divide and conquer approach. The complexity within each module can be chosen individually according to data availability, parsimony, relative importance, and stage of analysis. Three differences are highlighted in this paper when compared to previous works: (1) The fault tree proposed here accounts for the uncertainty in both hydrological and health components, (2) system failure within the fault tree is defined in terms of risk being above a threshold value, whereas previous studies that used fault trees used auxiliary events such as exceedance of critical concentration levels, and (3) we introduce a new form of stochastic fault tree that allows us to weaken the assumption of independent subsystems that is required by a classical fault tree approach. We illustrate our concept in a simple groundwater-related setting.

Photoactivable caps for reactive metal nanoparticles

NASA Astrophysics Data System (ADS)

Patel, Ashish

The synthesis and stabilization of reactive metal nanoparticles is often challenging under normal atmospheric conditions. This problem can be alleviated by capping and passivation. Our lab has focused on forming polymer coatings on the surface of reactive metal nanoparticles. We discovered a convenient and effective route for stabilization of aluminum nanoparticles (Al NPs), which uses the nascent metal core as a polymerization initiator for various organic monomers. In our previous work, we used this method to passivate the Al NPs using variety of epoxides and copolymers of epoxides and alkenes. These products have demonstrated air stability for weeks to months with little to no degradation in the active Al content. Since our previously synthesized Al NP's were not beneficial for rapid and efficient thermodynamic access to the active Al core, our goal was find polymers that could easily be photochemically activated to enhance such access. Since poly(methyl methacrylate) (PMMA) has photodegrading properties, we used PMMA as a capping agent to passivate Al NPs. In this work, we present capping and stabilization of Al NPs with PMMA, and also with 1,2-epoxyhexane/ PMMA. In our previous work, we increased the stability of Al NP capped with 1,2-epoxy-9-decene by adding 1,13-tetradecadiene as a cross-linker. Here, we used the methyl methacrylate (MMA) monomer as cross-linker for Al NP capped with 1,2-epoxy-9-decene. We have also used the MMA as capping agent. We use powder x-ray diffractametry (PXRD), differential scanning calorimetry (DSC), and thermogravity analysis (TGA) to confirm the presence of elemental Al and ATR-FTIR to confirm the presence of polymers.

Psychosocial stressors and cigarette smoking among African American adults in midlife.

PubMed

Slopen, Natalie; Dutra, Lauren M; Williams, David R; Mujahid, Mahasin S; Lewis, Tené T; Bennett, Gary G; Ryff, Carol D; Albert, Michelle A

2012-10-01

Psychosocial stress is a significant risk factor for smoking, and Blacks experience higher levels of psychosocial stress relative to other racial/ethnic groups. Limited research has comprehensively examined psychosocial stressors in relation to smoking among Blacks. We examined psychosocial stressors in relation to smoking status (current, previous, and never) in middle-aged Blacks (34-85 years, n = 592) from Milwaukee, Wisconsin, a subset of the Midlife in the United States Study II (2004-2006). Eleven stressor domains were assessed, including psychological and physical work stress, work-family conflict, perceived inequality, relationship stress, neighborhood stress, discrimination, financial stress, recent problems, stressful events, and childhood adversity. We also calculated a cumulative score. Multinomial models were adjusted for age, gender, education, and income. Seven of the 11 stressors and the cumulative score were associated with higher odds of being a current smoker compared with a never-smoker: neighborhood, financial, relationship, and psychological work stress, perceived inequality, stressful events, childhood adversity (p values <.05; ORs ranged from 1.28 to 1.77). Three stressors and the cumulative score were associated with higher odds of being a previous smoker versus a never-smoker (p < .05). Individuals who scored in the top quartile on 5 or more stressors were 3.74 (95% CI = 2.09-6.71) times as likely to be current smokers, and more than twice as likely to be previous smokers, compared with individuals with no high stressors. These results demonstrate a strong relationship between stress and smoking among urban middle-aged Blacks and suggest that cessation programs should address modifiable individual and community-level stressors.

Study protocol: the JEU cohort study--transversal multiaxial evaluation and 5-year follow-up of a cohort of French gamblers.

PubMed

Challet-Bouju, Gaëlle; Hardouin, Jean-Benoit; Vénisse, Jean-Luc; Romo, Lucia; Valleur, Marc; Magalon, David; Fatséas, Mélina; Chéreau-Boudet, Isabelle; Gorsane, Mohamed-Ali; Grall-Bronnec, Marie

2014-08-20

There is abundant literature on how to distinguish problem gambling (PG) from social gambling, but there are very few studies of the long-term evolution of gambling practice. As a consequence, the correlates of key state changes in the gambling trajectory are still unknown. The objective of the JEU cohort study is to identify the determinants of key state changes in the gambling practice, such as the emergence of a gambling problem, natural recovery from a gambling problem, resolution of a gambling problem with intermediate care intervention, relapses or care recourse. The present study was designed to overcome the limitations of previous cohort study on PG. Indeed, this longitudinal case-control cohort is the first which plans to recruit enough participants from different initial gambling severity levels to observe these rare changes. In particular, we plan to recruit three groups of gamblers: non-problem gamblers, problem gamblers without treatment and problem gamblers seeking treatment.Recruitment takes place in various gambling places, through the press and in care centers. Cohort participants are gamblers of both sexes who reported gambling on at least one occasion in the previous year and who were aged between 18 and 65. They were assessed through a structured clinical interview and self-assessment questionnaires at baseline and then once a year for five years. Data collection comprises sociodemographic characteristics, gambling habits (including gambling trajectory), the PG section of the DSM-IV, the South Oaks Gambling Screen, the Gambling Attitudes and Beliefs Survey - 23, the Mini International Neuropsychiatric Interview, the Wender-Utah Rating Scale-Child, the Adult ADHD Self-report Scale, somatic comorbidities (especially current treatment and Parkinson disease) and the Temperament and Character Inventory - 125. The JEU cohort study is the first study which proposes to identify the predictive factors of key state changes in gambling practice. This is the first case-control cohort on gambling which mixes non-problem gamblers, problem gamblers without treatment and problem gamblers seeking treatment in almost equal proportions. This work may help providing a fresh perspective on the etiology of pathological gambling, which may provide support for future research, care and preventive actions. (ClinicalTrials.gov): NCT01207674.

Disparities in self reported oral health problems among a young Syrian adult population.

PubMed

Alkhatib, M Nour; Gilthorpe, Mark S; McGrath, Colman

2002-12-01

To describe the prevalence of dental pain and other oral health problems among a young Syrian adult population and to identify socio-demographic factors associated with these experiences. An industrial sample of 400 men and women aged 18-34 years from Damascus, Syria. Study participants were interviewed about their experience of oral health problems in the previous year (1998). Socio-demographic information was collected. 93% (369) of the interviews were completed. The prevalence of oral health problems was high, with 96% (353) of respondents claiming that they experienced one or more problems in the previous year. Two thirds of participants (65%, 239) claimed they had dental pain in the previous year. Analysis revealed that dental pain experience was significantly associated with age and gender. Analysis considering all factors revealed that the odds of experiencing dental pain were higher amongst the younger age group (18-24 compared to 25-34 year-olds). The prevalence of oral health problems was high among the population studied. Socio-demographic variations in experience of dental pain were apparent, with young men of lower education having the greatest odds of dental pain experience in the previous year.

Responses to different types of inquiry prompts: college students' discourse, performance, and perceptions of group work in an engineering class

NASA Astrophysics Data System (ADS)

Balgopal, Meena M.; Casper, Anne Marie A.; Atadero, Rebecca A.; Rambo-Hernandez, Karen E.

2017-08-01

Working in small groups to solve problems is an instructional strategy that allows university students in science, technology, engineering, and mathematics disciplines the opportunity to practice interpersonal and professional skills while gaining and applying discipline-specific content knowledge. Previous research indicates that not all group work prompts result in the same experiences for students. In this study we posed two types of prompts (guided and open) to undergraduate engineering students in a statics course as they participated in group work projects. We measured student discourse, student performance, and perceptions of group work. We found that guided prompts were associated with higher-level discourse and higher performance (project scores) than open prompts. Students engaged in guided prompts were more likely to discuss distribution of labour and design/calculation details of their projects than when students responded to open prompts. We posit that guided prompts, which more clearly articulate expectations of students, help students determine how to divide tasks amongst themselves and, subsequently, jump to higher levels of discourse.

Rethinking "Generation Me": A Study of Cohort Effects From 1976-2006.

PubMed

Trzesniewski, Kali H; Donnellan, M Brent

2010-01-01

Social commentators have argued that changes over the last decades have coalesced to create a relatively unique generation of young people. However, using large samples of U.S. high-school seniors from 1976 to 2006 (Total N = 477,380), we found little evidence of meaningful change in egotism, self-enhancement, individualism, self-esteem, locus of control, hopelessness, happiness, life satisfaction, loneliness, antisocial behavior, time spent working or watching television, political activity, the importance of religion, and the importance of social status over the last 30 years. Today's youth are less fearful of social problems than previous generations and they are also more cynical and less trusting. In addition, today's youth have higher educational expectations than previous generations. However, an inspection of effect sizes provided little evidence for strong or widespread cohort-linked changes. © The Author(s) 2010.

Percolation of binary disk systems: Modeling and theory

DOE PAGES

Meeks, Kelsey; Tencer, John; Pantoya, Michelle L.

2017-01-12

The dispersion and connectivity of particles with a high degree of polydispersity is relevant to problems involving composite material properties and reaction decomposition prediction and has been the subject of much study in the literature. This paper utilizes Monte Carlo models to predict percolation thresholds for a two-dimensional systems containing disks of two different radii. Monte Carlo simulations and spanning probability are used to extend prior models into regions of higher polydispersity than those previously considered. A correlation to predict the percolation threshold for binary disk systems is proposed based on the extended dataset presented in this work and comparedmore » to previously published correlations. Finally, a set of boundary conditions necessary for a good fit is presented, and a condition for maximizing percolation threshold for binary disk systems is suggested.« less

Generalized Robertson-Walker Space-Time Admitting Evolving Null Horizons Related to a Black Hole Event Horizon

PubMed Central

2016-01-01

A new technique is used to study a family of time-dependent null horizons, called “Evolving Null Horizons” (ENHs), of generalized Robertson-Walker (GRW) space-time (M¯,g¯) such that the metric g¯ satisfies a kinematic condition. This work is different from our early papers on the same issue where we used (1 + n)-splitting space-time but only some special subcases of GRW space-time have this formalism. Also, in contrast to previous work, we have proved that each member of ENHs is totally umbilical in (M¯,g¯). Finally, we show that there exists an ENH which is always a null horizon evolving into a black hole event horizon and suggest some open problems. PMID:27722202

Stored energy in irradiated silicon carbide

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

Snead, L.L.; Burchell, T.D.

1997-04-01

This report presents a short review of the phenomenon of Wigner stored energy release from irradiated graphite and discusses it in relation to neutron irradiation of silicon carbide. A single published work in the area of stored energy release in SiC is reviewed and the results are discussed. It appears from this previous work that because the combination of the comparatively high specific heat of SiC and distribution in activation energies for recombining defects, the stored energy release of SiC should only be a problem at temperatures lower than those considered for fusion devices. The conclusion of this preliminary reviewmore » is that the stored energy release in SiC will not be sufficient to cause catastrophic heating in fusion reactor components, though further study would be desirable.« less

Air transportation in the California Corridor of 2010

NASA Technical Reports Server (NTRS)

Cameron, M.; Mahaffy, K.; Yanagi, G.; Lechmanski, L.; Riddle, T.; Howard, K.; Chan, C.; Gorman, M.; Bauer, B.

1989-01-01

The topic of the 1988-1989 NASA/USRA Advanced Design Project at California Polytechnic State University, San Luis Obispo, was the development of an air transportation system to meet the needs of the California Corridor for the year 2010. As aircraft design is taught by two instructors having different philosophies about the teaching process, the two classes took different approaches to address the problem. The first part of this summary (California Air Transit System) represents the work done by the students of Professor A. E. Andreoli, who followed a systems approach, emphasizing the determination of the proper mission. The second part of the summary (Four Aircraft to Service the California Corridor) contains the four aircraft designed by Dr. D. R. Sandlin's class based on specifications determined from work done in previous years.

User guide for MODPATH Version 7—A particle-tracking model for MODFLOW

USGS Publications Warehouse

Pollock, David W.

2016-09-26

MODPATH is a particle-tracking post-processing program designed to work with MODFLOW, the U.S. Geological Survey (USGS) finite-difference groundwater flow model. MODPATH version 7 is the fourth major release since its original publication. Previous versions were documented in USGS Open-File Reports 89–381 and 94–464 and in USGS Techniques and Methods 6–A41.MODPATH version 7 works with MODFLOW-2005 and MODFLOW–USG. Support for unstructured grids in MODFLOW–USG is limited to smoothed, rectangular-based quadtree and quadpatch grids.A software distribution package containing the computer program and supporting documentation, such as input instructions, output file descriptions, and example problems, is available from the USGS over the Internet (http://water.usgs.gov/ogw/modpath/).

Anxiety Sensitivity as a Mediator of the Relationship between Moderate-Intensity Exercise and Coping-Oriented Marijuana Use Motives

PubMed Central

Smits, Jasper A. J.; Bonn-Miller, Marcel O.; Tart, Candyce D.; Irons, Jessica G.; Zvolensky, Michael J.

2011-01-01

The present study examined the working hypothesis that moderate-intensity exercise is associated with coping-oriented marijuana use motives through its association with the fear of somatic arousal (i.e., anxiety sensitivity). Using data from 146 young adult current marijuana users we found evidence consistent with this hypothesis. Specifically, moderate-intensity exercise was associated with coping-oriented use motives, even after controlling for frequency of current marijuana use and other co-occurring marijuana use motives. This relationship became non-significant after entering anxiety sensitivity as an additional predictor variable, denoting a putative mediational role for this cognitve factor. These findings extend previous work and offer support for the potential utility of moderate-intensity aerobic exercise for the treatment of marijuana use problems. PMID:21314753

Outer synchronization of complex networks with internal delay and coupling delay via aperiodically intermittent pinning control

NASA Astrophysics Data System (ADS)

Zhang, Chuan; Wang, Xingyuan; Wang, Chunpeng; Xia, Zhiqiu

This paper concerns the outer synchronization problem between two complex delayed networks via the method of aperiodically intermittent pinning control. Apart from previous works, internal delay and coupling delay are both involved in this model, and the designed intermittent controllers can be aperiodic. The main work in this paper can be summarized as follows: First, two cases of aperiodically intermittent control with constant gain and adaptive gain are implemented, respectively. The intermittent control and pinning control are combined to reduce consumptions further. Then, based on the Lyapunov stability theory, synchronization protocols are given by strict derivation. Especially, the designed controllers are indeed simple and valid in application of theory to practice. Finally, numerical examples put the proposed control methods to the test.

Investigation of Nonlinear Pressurization and Model Restart in MSC/NASTRAN for Modeling Thin Film Inflatable Structures

NASA Technical Reports Server (NTRS)

Smalley, Kurt B.; Tinker, Michael L.; Fischer, Richard T.

2001-01-01

This paper is written for the purpose of providing an introduction and set of guidelines for the use of a methodology for NASTRAN eigenvalue modeling of thin film inflatable structures. It is hoped that this paper will spare the reader from the problems and headaches the authors were confronted with during their investigation by presenting here not only an introduction and verification of the methodology, but also a discussion of the problems that this methodology can ensue. Our goal in this investigation was to verify the basic methodology through the creation and correlation of a simple model. An overview of thin film structures, their history, and their applications is given. Previous modeling work is then briefly discussed. An introduction is then given for the method of modeling. The specific mechanics of the method are then discussed in parallel with a basic discussion of NASTRAN s implementation of these mechanics. The problems encountered with the method are then given along with suggestions for their work-a-rounds. The methodology is verified through the correlation between an analytical model and modal test results of a thin film strut. Recommendations are given for the needed advancement of our understanding of this method and ability to accurately model thin film structures. Finally, conclusions are drawn regarding the usefulness of the methodology.

The EMIR experience in the use of software control simulators to speed up the time to telescope

NASA Astrophysics Data System (ADS)

Lopez Ramos, Pablo; López-Ruiz, J. C.; Moreno Arce, Heidy; Rosich, Josefina; Perez Menor, José Maria

2012-09-01

One of the main problems facing development teams working on instrument control systems consists on the need to access mechanisms which are not available until well into the integration phase. The need to work with real hardware creates additional problems like, among others: certain faults cannot be tested due to the possibility of hardware damage, taking the system to the limit may shorten its operational lifespan and the full system may not be available during some periods due to maintenance and/or testing of individual components. These problems can be treated with the use of simulators and by applying software/hardware standards. Since information on the construction and performance of electro-mechanical systems is available at relatively early stages of the project, simulators are developed in advance (before the existence of the mechanism) or, if conventions and standards have been correctly followed, a previously developed simulator might be used. This article describes our experience in building software simulators and the main advantages we have identified, which are: the control software can be developed even in the absence of real hardware, critical tests can be prepared using the simulated systems, test system behavior for hardware failure situations that represent a risk of the real system, and the speed up of in house integration of the entire instrument. The use of simulators allows us to reduce development, testing and integration time.

Future orientation, school contexts, and problem behaviors: a multilevel study.

PubMed

Chen, Pan; Vazsonyi, Alexander T

2013-01-01

The association between future orientation and problem behaviors has received extensive empirical attention; however, previous work has not considered school contextual influences on this link. Using a sample of N = 9,163 9th to 12th graders (51.0 % females) from N = 85 high schools of the National Longitudinal Study of Adolescent Health, the present study examined the independent and interactive effects of adolescent future orientation and school contexts (school size, school location, school SES, school future orientation climate) on problem behaviors. Results provided evidence that adolescent future orientation was associated independently and negatively with problem behaviors. In addition, adolescents from large-size schools reported higher levels of problem behaviors than their age mates from small-size schools, controlling for individual-level covariates. Furthermore, an interaction effect between adolescent future orientation and school future orientation climate was found, suggesting influences of school future orientation climate on the link between adolescent future orientation and problem behaviors as well as variations in effects of school future orientation climate across different levels of adolescent future orientation. Specifically, the negative association between adolescent future orientation and problem behaviors was stronger at schools with a more positive climate of future orientation, whereas school future orientation climate had a significant and unexpectedly positive relationship with problem behaviors for adolescents with low levels of future orientation. Findings implicate the importance of comparing how the future orientation-problem behaviors link varies across different ecological contexts and the need to understand influences of school climate on problem behaviors in light of differences in psychological processes among adolescents.

Standardized assessment of psychosocial factors and their influence on medically confirmed health outcomes in workers: a systematic review.

PubMed

Rosário, Susel; Fonseca, João A; Nienhaus, Albert; da Costa, José Torres

2016-01-01

Previous studies of psychosocial work factors have indicated their importance for workers' health. However, to what extent health problems can be attributed to the nature of the work environment or other psychosocial factors is not clear. No previous systematic review has used inclusion criteria based on specific medical evaluation of work-related health outcomes and the use of validated instruments for the assessment of the psychosocial (work) environment. The aim of this systematic review is to summarize the evidence assessing the relationship between the psychosocial work environment and workers' health based on studies that used standardized and validated instruments to assess the psychosocial work environment and that focused on medically confirmed health outcomes. A systematic review of the literature was carried out by searching the databases PubMed, B-ON, Science Direct, Psycarticles, Psychology and Behavioral Sciences Collection and the search engine (Google Scholar) using appropriate words for studies published from 2004 to 2014. This review follows the recommendations of the Statement for Reporting Systematic Reviews (PRISMA). Studies were included in the review if data on psychosocial validated assessment method(s) for the study population and specific medical evaluation of health-related work outcome(s) were presented. In total, the search strategy yielded 10,623 references, of which 10 studies (seven prospective cohort and three cross-sectional) met the inclusion criteria. Most studies (7/10) observed an adverse effect of poor psychosocial work factors on workers' health: 3 on sickness absence, 4 on cardiovascular diseases. The other 3 studies reported detrimental effects on sleep and on disease-associated biomarkers. A more consistent effect was observed in studies of higher methodological quality that used a prospective design jointly with the use of validated instruments for the assessment of the psychosocial (work) environment and clinical evaluation. More prospective studies are needed to assess the evidence of work-related psychosocial factors on workers´ health.

[Influence of mental rotation of objects on psychophysiological functions of women].

PubMed

Chikina, L V; Fedorchuk, S V; Trushina, V A; Ianchuk, P I; Makarchuk, M Iu

2012-01-01

An integral part of activity of modern human beings is an involvement to work with the computer systems which, in turn, produces a nervous - emotional tension. Hence, a problem of control of the psychophysiological state of workmen with the purpose of health preservation and success of their activity and the problem of application of rehabilitational actions are actual. At present it is known that the efficiency of rehabilitational procedures rises following application of the complex of regenerative programs. Previously performed by us investigation showed that mental rotation is capable to compensate the consequences of a nervous - emotional tension. Therefore, in the present work we investigated how the complex of spatial tasks developed by us influences psychophysiological performances of tested women for which the psycho-emotional tension with the usage of computer technologies is more essential, and the procedure of mental rotation is more complex task for them, than for men. The complex of spatial tasks applied in the given work included: mental rotation of simple objects (letters and digits), mental rotation of complex objects (geometrical figures) and mental rotation of complex objects with the usage of a short-term memory. Execution of the complex of spatial tasks reduces the time of simple and complex sensomotor response, raises parameters of a short-term memory, brain work capacity and improves nervous processes. Collectively, mental rotation of objects can be recommended as a rehabilitational resource for compensation of consequences of any psycho-emotional strain, both for men, and for women.

Integrated language education - a means of enhancing engineers' social competences

NASA Astrophysics Data System (ADS)

Lappalainen, P.

2010-08-01

The changes facing industries are necessitating a concomitant change in university curriculum. Before instigating a reform, however, education providers need to acquire an understanding of the most pertinent development needs essential for filling industrial competence gaps. The Language Centre at the Helsinki University of Technology in Finland set out to respond to the emerging competence demands by examining industrial requirements through previous research and stakeholder analyses. Surveys conducted among employers and students corroborated a need to shift focus towards oral communication abilities. More specifically, university education needs to address interaction skills essential in meetings and managerial tasks. As a result, a so-called integrated language course was designed and piloted to train students into multi-disciplinary, culturally and ethically aware communicators who possess leveraged self-leadership and managerial abilities. 'Organisational Communications' integrates substance matters such as finance, strategy, leadership and ethics into a language course, while harnessing the English language as a tool. Course methodology is based on project- and problem-based learning and situational learning, rooting the students in real working life by imitating authentic corporate cases and industrial contexts. The course aims to provide the students with preparedness, ability and mindset to deal with working life challenges and ways of working while applying their specialist discourse, that is, the appropriate industrial jargon and linguistic practices. The learning outcomes and student feedback from this course indicate that the pedagogy in use in this experiment, drawing from exercises emulating authentic, industrial problems, offers an effective method of preparing students for working life requirements.

Difficulties facing physician mothers in Japan.

PubMed

Yamazaki, Yuka; Kozono, Yuki; Mori, Ryo; Marui, Eiji

2011-11-01

Despite recent increases in the number of female physicians graduating in Japan, their premature resignations after childbirth are contributing to the acute shortage of physicians. Previous Japanese studies have explored supportive measures in the workplace, but have rarely focused on the specific problems or concerns of physician-mothers. Therefore, this study explored the challenges facing Japanese physician-mothers in efforts to identify solutions for their retention. Open-ended questionnaires were mailed to 646 alumnae of Juntendo University School of Medicine. We asked subjects to describe their opinions about 'The challenges related to female physicians' resignations'. Comments gathered from alumnae who graduated between 6 and 30 years ago and have children were analyzed qualitatively. Overall, 249 physicians returned the questionnaire (response rate 38.5%), and 73 alumnae with children who graduated in the stated time period provided comments. The challenges facing physician-mothers mainly consisted of factors associated with Japanese society, family responsibilities, and work environment. Japanese society epitomized by traditional gender roles heightened stress related to family responsibilities and promoted gender discrimination at work environment. Additionally, changing Japanese society positively influenced working atmosphere and husband's support. Moreover, the introduction of educational curriculums that alleviated traditional gender role was proposed for pre- and post- medical students. Traditional gender roles encourage discrimination by male physicians or work-family conflicts. The problems facing female physicians involve more than just family responsibilities: diminishing the notion of gender role is key to helping retain them in the workforce. © 2011 Tohoku University Medical Press

The importance, measurement and practical implications of worker's expectations for return to work.

PubMed

Young, Amanda E; Besen, Elyssa; Choi, YoonSun

2015-01-01

Workers' own expectations for return to work consistently predict work status. To advance the understanding of the relationship between RTW expectations and outcomes, we reviewed existing measures to determine those which we felt were the most likely to capture the construct. A comprehensive search of the work-disability rehabilitation literature was undertaken. The review of the measures was conducted in three steps: first, a review of terminology; second, an examination of whether a time reference was included; third, an evaluation of ease of comprehension, and applicability across contexts. A total of 42 different measures were identified. One of the most striking findings was the inconsistency in terminology. Measures were also limited by not including a time reference. Problems were also identified with regards to ease of understanding, utility of response options, and applicability in a wide variety of research and applied settings. Most previously used measures contain elements that potentially limit utility. However, it would seem that further development can overcome these, resulting in a tool that provides risk prediction information, and an opportunity to start a conversation to help identify problems that might negatively impact a worker's movement through the RTW process and the outcomes achieved. Implications for Rehabilitation Return to work is an integral part of workplace injury management. The capture of RTW expectations affords a way to identify the potential for less than optimal RTW processes and outcomes. A mismatch between an injured worker's expectations and what other stakeholders might expect suggests that efforts could be made to determine what is causing the injured worker's concerns. Once underling issues are identified, work can be put into resolving these so that the worker's return to the workplace is not impeded.

[The Significance of Work Motivation for Rehabilitation Success].

PubMed

Kessemeier, Franziska; Stöckler, Christiane; Petermann, Franz; Bassler, Markus; Pfeiffer, Wolfgang; Kobelt, Axel

2017-11-28

Aim of this study Apart from the reduction of symptoms and the restoration of working ability, return to work is a long-term goal of medical rehabilitation. The aim of this study is to analyze the influence of work motivation on the outcome of rehabilitation. Methods The data basis consists of N=998 patients at the psychosomatic department of the Oberharz Rehabilitation Center as well as data from insurance accounts. Using multiple linear regression analysis the predictive power of work motivation on rehabilitation outcome as well as different facets of work motivation in their function as predictors are analyzed. Results Only minor statistical relations could be found between work motivation and rehabilitation success when also taking employment status of the previous year and subjective vocational disability into account. A small predictive power can be attributed to work motivation as a factor in rehabilitation success in the sense of a reduction of symptoms. Particular facets of work motivation are suitable to predict rehabilitation success. Patients with a work motivation risk profile differ from patients with a normal work motivation profile as regards their capacity to work in the year following rehabilitation treatment. Conclusion Work motivation represents a relevant construct in rehabilitation success but is strongly influenced by individual factors. During rehabilitation, individual problems which influence work motivation should be taken into account more strongly. © Georg Thieme Verlag KG Stuttgart · New York.

Tool use in neurodegenerative diseases: Planning or technical reasoning?

PubMed

Baumard, Josselin; Lesourd, Mathieu; Remigereau, Chrystelle; Jarry, Christophe; Etcharry-Bouyx, Frédérique; Chauviré, Valérie; Osiurak, François; Le Gall, Didier

2017-04-29

Recent works showed that tool use can be impaired in stroke patients because of either planning or technical reasoning deficits, but these two hypotheses have not yet been compared in the field of neurodegenerative diseases. The aim of this study was to address the relationships between real tool use, mechanical problem-solving, and planning skills in patients with Alzheimer's disease (AD, n = 32), semantic dementia (SD, n = 16), and corticobasal syndrome (CBS, n = 9). Patients were asked to select and use ten common tools, to solve three mechanical problems, and to complete the Tower of London test. Motor function and episodic memory were controlled using the Purdue Pegboard Test and the BEC96 questionnaire, respectively. A data-transformation method was applied to avoid ceiling effects, and single-case analysis was performed based on raw scores and completion time. All groups demonstrated either impaired or slowed tool use. Planning deficits were found only in the AD group. Mechanical problem-solving deficits were observed only in the AD and CBS groups. Performance in the Tower of London test was the best predictor of tool use skills in the AD group, suggesting these patients had general rather than mechanical problem-solving deficits. Episodic memory seemed to play little role in performance. Motor dysfunction tended to be associated with tool use skills in CBS patients, while tool use disorders are interpreted as a consequence of the semantic loss in SD in line with previous works. These findings may encourage caregivers to set up disease-centred interventions. © 2017 The British Psychological Society.

Problem-Based Learning: Using Ill-Structured Problems in Biology Project Work

ERIC Educational Resources Information Center

Chin, Christine; Chia, Li-Gek

2006-01-01

This case study involved year 9 students carrying out project work in biology via problem-based learning. The purpose of the study was to (a) find out how students approach and work through ill-structured problems, (b) identify some issues and challenges related to the use of such problems, and (c) offer some practical suggestions on the…

Solving Connected Subgraph Problems in Wildlife Conservation

NASA Astrophysics Data System (ADS)

Dilkina, Bistra; Gomes, Carla P.

We investigate mathematical formulations and solution techniques for a variant of the Connected Subgraph Problem. Given a connected graph with costs and profits associated with the nodes, the goal is to find a connected subgraph that contains a subset of distinguished vertices. In this work we focus on the budget-constrained version, where we maximize the total profit of the nodes in the subgraph subject to a budget constraint on the total cost. We propose several mixed-integer formulations for enforcing the subgraph connectivity requirement, which plays a key role in the combinatorial structure of the problem. We show that a new formulation based on subtour elimination constraints is more effective at capturing the combinatorial structure of the problem, providing significant advantages over the previously considered encoding which was based on a single commodity flow. We test our formulations on synthetic instances as well as on real-world instances of an important problem in environmental conservation concerning the design of wildlife corridors. Our encoding results in a much tighter LP relaxation, and more importantly, it results in finding better integer feasible solutions as well as much better upper bounds on the objective (often proving optimality or within less than 1% of optimality), both when considering the synthetic instances as well as the real-world wildlife corridor instances.

Task-specific modulation of adult humans' tool preferences: number of choices and size of the problem.

PubMed

Silva, Kathleen M; Gross, Thomas J; Silva, Francisco J

2015-03-01

In two experiments, we examined the effect of modifications to the features of a stick-and-tube problem on the stick lengths that adult humans used to solve the problem. In Experiment 1, we examined whether people's tool preferences for retrieving an out-of-reach object in a tube might more closely resemble those reported with laboratory crows if people could modify a single stick to an ideal length to solve the problem. Contrary to when adult humans have selected a tool from a set of ten sticks, asking people to modify a single stick to retrieve an object did not generally result in a stick whose length was related to the object's distance. Consistent with the prior research, though, the working length of the stick was related to the object's distance. In Experiment 2, we examined the effect of increasing the scale of the stick-and-tube problem on people's tool preferences. Increasing the scale of the task influenced people to select relatively shorter tools than had selected in previous studies. Although the causal structures of the tasks used in the two experiments were identical, their results were not. This underscores the necessity of studying physical cognition in relation to a particular causal structure by using a variety of tasks and methods.

Personality Disorder Models and their Coverage of Interpersonal Problems

PubMed Central

Williams, Trevor F.; Simms, Leonard J.

2015-01-01

Interpersonal dysfunction is a defining feature of personality disorders (PDs) and can serve as a criterion for comparing PD models. In this study, the interpersonal coverage of four competing PD models was examined using a sample of 628 current or recent psychiatric patients who completed the NEO Personality Inventory-3 First Half (NEO-PI-3FH; McCrae & Costa, 2007), Personality Inventory for the DSM-5 (PID-5; Krueger et al., 2012), Computerized Adaptive Test of Personality Disorder-Static Form (CAT-PD-SF; Simms et al., 2011), and Structured Clinical Interview for DSM-IV Personality Questionnaire (SCID-II PQ; First, Spitzer, Gibbon, & Williams, 1995). Participants also completed the Inventory of Interpersonal Problems-Short Circumplex (IIP-SC; Soldz, Budman, Demby, & Merry, 1995) to assess interpersonal dysfunction. Analyses compared the severity and style of interpersonal problems that characterize PD models. Previous research with DSM-5 Section II and III models was generally replicated. Extraversion and Agreeableness facets related to the most well defined interpersonal problems across normal-range and pathological traits. Pathological trait models provided more coverage of dominance problems, whereas normal-range traits covered nonassertiveness better. These results suggest that more work may be needed to reconcile descriptions of personality pathology at the level of specific constructs. PMID:26168406

Kernel-based least squares policy iteration for reinforcement learning.

PubMed

Xu, Xin; Hu, Dewen; Lu, Xicheng

2007-07-01

In this paper, we present a kernel-based least squares policy iteration (KLSPI) algorithm for reinforcement learning (RL) in large or continuous state spaces, which can be used to realize adaptive feedback control of uncertain dynamic systems. By using KLSPI, near-optimal control policies can be obtained without much a priori knowledge on dynamic models of control plants. In KLSPI, Mercer kernels are used in the policy evaluation of a policy iteration process, where a new kernel-based least squares temporal-difference algorithm called KLSTD-Q is proposed for efficient policy evaluation. To keep the sparsity and improve the generalization ability of KLSTD-Q solutions, a kernel sparsification procedure based on approximate linear dependency (ALD) is performed. Compared to the previous works on approximate RL methods, KLSPI makes two progresses to eliminate the main difficulties of existing results. One is the better convergence and (near) optimality guarantee by using the KLSTD-Q algorithm for policy evaluation with high precision. The other is the automatic feature selection using the ALD-based kernel sparsification. Therefore, the KLSPI algorithm provides a general RL method with generalization performance and convergence guarantee for large-scale Markov decision problems (MDPs). Experimental results on a typical RL task for a stochastic chain problem demonstrate that KLSPI can consistently achieve better learning efficiency and policy quality than the previous least squares policy iteration (LSPI) algorithm. Furthermore, the KLSPI method was also evaluated on two nonlinear feedback control problems, including a ship heading control problem and the swing up control of a double-link underactuated pendulum called acrobot. Simulation results illustrate that the proposed method can optimize controller performance using little a priori information of uncertain dynamic systems. It is also demonstrated that KLSPI can be applied to online learning control by incorporating an initial controller to ensure online performance.