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1

Task-based Dermal Exposure Models for Regulatory Risk Assessment  

Microsoft Academic Search

The regulatory risk assessment of chemicals requires the estimation of occupational dermal exposure. Until recently, the models used were either based on limited data or were specific to a particular class of chemical or application. The EU project RISKOFDERM has gathered a considerable number of new measurements of dermal exposure together with detailed contex- tual information. This article describes the

NICHOLAS D. WARREN; HANS MARQUART; YVETTE CHRISTOPHER; JUHA LAITINEN; JOOP J. VAN HEMMEN

2006-01-01

2

Silica exposure during construction activities: statistical modeling of task-based measurements from the literature.  

PubMed

Many construction activities can put workers at risk of breathing silica containing dusts, and there is an important body of literature documenting exposure levels using a task-based strategy. In this study, statistical modeling was used to analyze a data set containing 1466 task-based, personal respirable crystalline silica (RCS) measurements gathered from 46 sources to estimate exposure levels during construction tasks and the effects of determinants of exposure. Monte-Carlo simulation was used to recreate individual exposures from summary parameters, and the statistical modeling involved multimodel inference with Tobit models containing combinations of the following exposure variables: sampling year, sampling duration, construction sector, project type, workspace, ventilation, and controls. Exposure levels by task were predicted based on the median reported duration by activity, the year 1998, absence of source control methods, and an equal distribution of the other determinants of exposure. The model containing all the variables explained 60% of the variability and was identified as the best approximating model. Of the 27 tasks contained in the data set, abrasive blasting, masonry chipping, scabbling concrete, tuck pointing, and tunnel boring had estimated geometric means above 0.1mg m(-3) based on the exposure scenario developed. Water-fed tools and local exhaust ventilation were associated with a reduction of 71 and 69% in exposure levels compared with no controls, respectively. The predictive model developed can be used to estimate RCS concentrations for many construction activities in a wide range of circumstances. PMID:23223272

Sauvé, Jean-François; Beaudry, Charles; Bégin, Denis; Dion, Chantal; Gérin, Michel; Lavoué, Jérôme

2013-05-01

3

Facilitating task based noise exposure assessments utilizing PDAs  

Microsoft Academic Search

The difficulties inherent in hand recording, editing, and coding observational data can limit both its utility and effectiveness as a tool in exposure assessments. Recently these limitations were noted during a noise exposure assessment of drill rig operators working at surface mines, where rapid changes in drilling operations and rig operator behaviors occurred simultaneously or in quick succession. In response

Dana C. Reinke; Paul Jurovcik; Barbara Fotta

4

Comparison of task-based estimates with full-shift measurements of noise exposure.  

PubMed

Using a large data set of noise exposure measurements on construction workers, task-based (TB) and full-shift (FS) exposure levels were compared and analyzed for the sources and magnitudes of the error associated with this methodology. Data-logging dosimeters recorded A-weighted sound pressure levels in decibels using Occupational Safety and Health Administration criteria for every minute of monitoring and were combined with information from task cards completed by subjects. Task-related information included trade, construction site type, location, activity, and tool. A total of 502 FS measurements were made, including 248,677 min of exposure on five construction trades. Six TB models of varying degrees of specificity were fit to the minute-level data and the results used to obtain TB estimates of the daily FS exposure levels. The TB estimates were derived using the predictions alone and also including subject and shift-specific residual means and variances. The predictions alone, which ignore within-task variability, produced a significant negative bias that was corrected by incorporation of the residual variance. This bias is only an issue in this setting in which the exposure of interest is noise, which follows a nonlinear averaging relationship. These estimates explained 10 to 60% of the variability in FS measures; adding the residual mean produced estimates that explained about 90% of the variability. In summary, TB estimates are important for exposure estimation when task time varies substantially. However, TB estimates include a substantial degree of error when there is large interindividual or intershift variability in exposure levels for a given task. Methods to improve the prediction of task-associated exposure, or adjusting for individual and shift differences, are needed. PMID:14674795

Seixas, Noah S; Sheppard, Lianne; Neitzel, Rick

2003-01-01

5

Computerized Task-Based Exposure, Explicitness, Type of Feedback, and Spanish L2 Development  

ERIC Educational Resources Information Center

This study examined whether exposure to second/foreign language (L2) data under different computerized task conditions had a differential impact on learners' ability to recognize and produce the target structure immediately after exposure to the input and over time. Learners' L2 development was assessed through recognition and…

Rosa, Elena M.; Leow, Ronald P.

2004-01-01

6

The use of a task-based exposure assessment model (T-BEAM) for assessment of metal fume exposures during welding and thermal cutting.  

PubMed

Elevated disease rates have been documented among construction workers for cancer, pneumonoconiosis, asbestosis, and silicosis. However, methodologies for exposure assessment in construction are not well described in the U.S. literature. Working through a cooperative agreement with the National Institute for Occupational Safety and Health (NIOSH), the Center to Protect Workers' Rights--a research arm of the Building and Construction Trades Department, AFL-CIO--has developed and used a "Task-Based Exposure Assessment Model (T-BEAM)" for construction. The characteristic elements of T-BEAM are: (1) an emphasis on the identification, implementation, and evaluation of engineering and work practice controls; and (2) use of experienced, specially trained construction workers (construction safety and health specialists) in the exposure assessment process. A task-based approach was used because tasks, or specialized skills, form the single greatest thread of continuity in the dynamic environment of construction. Workers in the construction industry come from several crafts and are typically employed by a large number of contractors throughout their career. Project types (e.g., residential or industrial rehabilitation) are also highly variable and present unique health risks. Finally, because construction involves building, renovating, or dismantling physical surroundings, the work site is constantly changing. Between 1995 and 1996, T-BEAM was applied to the collection of approximately 200 personal exposure measurements associated with "hot work tasks"--welding and thermal cutting. Data were collected with the assistance of specially trained, journeyman ironworkers, pipe fitters, and boilermakers on nine construction sites located throughout the United States. Portable local exhaust ventilation was provided to participating contractors with the intent of measuring its impact on exposure. Results indicate that data collected in a standardized, systematic fashion from multiple work sites can be used to characterize exposures among sampled trades. Comparison of results to American Conference of Governmental Industrial Hygienists (ACGIH) threshold limit values (TLVs) demonstrate a significant health hazard among sampled trades posed by welding and thermal cutting fume, manganese, nickel, and chromium VI. Direct estimates of the probability of exceeding the ACGIH TLV for respirable particulate suggests that boilermakers (100%) and ironworkers (71%) are at greatest risk. Other task variables evaluated with respect to exposure include task, whether work was performed indoors or outdoors, intermittency of work, and use of ventilation. Use of local or mechanical ventilation reduced mean exposures to fumes significantly. PMID:10660986

Susi, P; Goldberg, M; Barnes, P; Stafford, E

2000-01-01

7

Scenario-Based Tasks  

NSDL National Science Digital Library

This page from The Experiential Learning Center provides a number of scenario-based tasks for use in the classroom or for professional development training. The materials are freely available for download and use and would be applicable to learners in a variety of subjects including software development, faculty professional development, office system applications/ICT, biology/bioinformatics, environmental studies, Python programming, engineering, network security/MIS, computational thinking and English writing. Instructor guides and other classroom instructional materials are provided. The project requests that educators let them know when these materials are used in order to track dissemination of the work and in order to inform the community about upcoming workshops and presentations.

2012-10-09

8

Hexavalent chromium exposure and control in welding tasks.  

PubMed

Studies of exposure to the lung carcinogen hexavalent chromium (CrVI) from welding tasks are limited, especially within the construction industry where overexposure may be common. In addition, despite the OSHA requirement that the use of engineering controls such as local exhaust ventilation (LEV) first be considered before relying on other strategies to reduce worker exposure to CrVI, data on the effectiveness of LEV to reduce CrVI exposures from welding are lacking. The goal of the present study was to characterize breathing zone air concentrations of CrVI during welding tasks and primary contributing factors in four datasets: (1) OSHA compliance data; (2) a publicly available database from The Welding Institute (TWI); (3) field survey data of construction welders collected by the Center for Construction Research and Training (CPWR); and (4) controlled welding trials conducted by CPWR to assess the effectiveness of a portable LEV unit to reduce CrVI exposure. In the OSHA (n = 181) and TWI (n = 124) datasets, which included very few samples from the construction industry, the OSHA permissible exposure level (PEL) for CrVI (5 ?g/m(3)) was exceeded in 9% and 13% of samples, respectively. CrVI concentrations measured in the CPWR field surveys (n = 43) were considerably higher, and 25% of samples exceeded the PEL. In the TWI and CPWR datasets, base metal, welding process, and LEV use were important predictors of CrVI concentrations. Only weak-to-moderate correlations were found between total particulate matter and CrVI, suggesting that total particulate matter concentrations are not a good surrogate for CrVI exposure in retrospective studies. Finally, in the controlled welding trials, LEV reduced median CrVI concentrations by 68% (p = 0.02). In conclusion, overexposure to CrVI in stainless steel welding is likely widespread, especially in certain operations such as shielded metal arc welding, which is commonly used in construction. However, exposure could be substantially reduced with proper use of LEV. PMID:20845207

Meeker, John D; Susi, Pam; Flynn, Michael R

2010-11-01

9

Hexavalent Chromium Exposure and Control in Welding Tasks  

Microsoft Academic Search

Studies of exposure to the lung carcinogen hexavalent chromium (CrVI) from welding tasks are limited, especially within the construction industry where overexposure may be common. In addition, despite the OSHA requirement that the use of engineering controls such as local exhaust ventilation (LEV) first be considered before relying on other strategies to reduce worker exposure to CrVI, data on the

John D. Meeker; Pam Susi; Michael R. Flynn

2010-01-01

10

Accuracy of task recall for epidemiological exposure assessment to construction noise  

PubMed Central

Aims: To validate the accuracy of construction worker recall of task and environment based information; and to evaluate the effect of task recall on estimates of noise exposure. Methods: A cohort of 25 construction workers recorded tasks daily and had dosimetry measurements weekly for six weeks. Worker recall of tasks reported on the daily activity cards was validated with research observations and compared directly to task recall at a six month interview. Results: The mean LEQ noise exposure level (dBA) from dosimeter measurements was 89.9 (n = 61) and 83.3 (n = 47) for carpenters and electricians, respectively. The percentage time at tasks reported during the interview was compared to that calculated from daily activity cards; only 2/22 tasks were different at the nominal 5% significance level. The accuracy, based on bias and precision, of percentage time reported for tasks from the interview was 53–100% (median 91%). For carpenters, the difference in noise estimates derived from activity cards (mean 91.9 dBA) was not different from those derived from the questionnaire (mean 91.7 dBA). This trend held for electricians as well. For all subjects, noise estimates derived from the activity card and the questionnaire were strongly correlated with dosimetry measurements. The average difference between the noise estimate derived from the questionnaire and dosimetry measurements was 2.0 dBA, and was independent of the actual exposure level. Conclusions: Six months after tasks were performed, construction workers were able to accurately recall the percentage time they spent at various tasks. Estimates of noise exposure based on long term recall (questionnaire) were no different from estimates derived from daily activity cards and were strongly correlated with dosimetry measurements, overestimating the level on average by 2.0 dBA.

Reeb-Whitaker, C; Seixas, N; Sheppard, L; Neitzel, R

2004-01-01

11

Task-based nutrition labelling.  

PubMed

Task-based interface design principles (TBI) were evaluated as a framework for designing effective nutritional labels. In two experiments a total of 123 people assembled a packed lunch, selecting components using labels in GDA or TBI format, or when given only the names of the foods. Study 1 found that a GDA label helped people make healthier choices than the product name alone, but that for a number of types of food, most people would make the same decision with or without a GDA label. Moreover, decisions were much faster when made with the name alone. Study 2 introduced a TBI label in the context of the more specific task of keeping the salt in the lunch under 1g. TBI and GDA labels reduced salt equally, but only the TBI label was as quick as the name alone. Labels that are aligned with people's specific objectives are more efficient. TBI is a potentially useful framework, that can be deployed using mobile computing. PMID:20692310

Dunbar, George

2010-12-01

12

Agricultural task and exposure to organophosphate pesticides among farmworkers.  

PubMed Central

Little is known about pesticide exposure among farmworkers, and even less is known about the exposure associated with performing specific farm tasks. Using a random sample of 213 farmworkers in 24 communities and labor camps in eastern Washington State, we examined the association between occupational task and organophosphate (OP) pesticide residues in dust and OP metabolite concentrations in urine samples of adult farmworkers and their children. The data are from a larger study that sought to test a culturally appropriate intervention to break the take-home pathway of pesticide exposure. Commonly reported farm tasks were harvesting or picking (79.2%), thinning (64.2%), loading plants or produce (42.2%), planting or transplanting (37.6%), and pruning (37.2%). Mixing, loading, or applying pesticide formulations was reported by 20% of our sample. Workers who thinned were more likely than those who did not to have detectable levels of azinphos-methyl in their house dust (92.1% vs. 72.7%; p = 0.001) and vehicle dust (92.6% vs. 76.5%; p = 0.002). Thinning was associated with higher urinary pesticide metabolite concentrations in children (91.9% detectable vs. 81.3%; p = 0.02) but not in adults. Contrary to expectation, workers who reported mixing, loading, or applying pesticide formulations had lower detectable levels of pesticide residues in their house or vehicle dust, compared with those who did not perform these job tasks, though the differences were not significant. Future research should evaluate workplace protective practices of fieldworkers and the adequacy of reentry intervals for pesticides used during thinning.

Coronado, Gloria D; Thompson, Beti; Strong, Larki; Griffith, William C; Islas, Ilda

2004-01-01

13

A task-specific assessment of Swine worker exposure to airborne dust.  

PubMed

A task-based analysis of personal airborne dust exposures was performed in two swine confinement facilities used to house sows and their litters. Airborne particulate levels were assessed during summer, winter, and spring. Personal aerosol measurements of workers were made with a photometer every 15 sec and corrected to compare with an integrated concentration measurement made with a co-located IOM inhalable dust sampler. Task type and time period were recorded by the workers over an 8-hr work shift. There was a significant difference in dust concentrations between seasons (p < 0.001), with winter months providing the highest levels (geometric mean = 3.76 mg/m(3)). The application of a general linear model of log-transformed task concentrations relative to site, season, and task demonstrated significant differences (P < 0.001) among all three covariates. Tasks performed near moving animals, especially the weaning process, resulted in the greatest concentrations. These results indicate the need to evaluate the concentration levels for separate tasks during multi-task work shifts, such as swine rearing, to optimize efforts to minimize exposures by focusing on high-concentration tasks. PMID:19904655

O'Shaughnessy, Patrick T; Donham, Kelley J; Peters, Thomas M; Taylor, Craig; Altmaier, Ralph; Kelly, Kevin M

2010-01-01

14

In-Session Exposure Tasks and Therapeutic Alliance across the Treatment of Childhood Anxiety Disorders  

ERIC Educational Resources Information Center

The study examined the shape of therapeutic alliance using latent growth curve modeling and data from multiple informants (therapist, child, mother, father). Children (n = 86) with anxiety disorders were randomized to family-based cognitive-behavioral treatment (FCBT; N = 47) with exposure tasks or to family education, support, and attention…

Kendall, Philip C.; Comer, Jonathan S.; Marker, Craig D.; Creed, Torrey A.; Puliafico, Anthony C.; Hughes, Alicia A.; Martin, Erin D.; Suveg, Cynthia; Hudson, Jennifer

2009-01-01

15

Task-based Learning through Dialogue Management  

Microsoft Academic Search

We propose a new kind of task-oriented dialogue model designed to represent task-based learning (TBL) in second language learning. In order to evaluate a dialogue system that interacts with virtual learners in an Intelligent Tutoring System (ITS), this paper simulates learners' behavior by translating real learners' reactions into an Artificial Intelligence Mark- up Language (AIML) with a virtual tutor supported

Chin-Chien Wang; Chun-Hung Lu; Mon-Tin Tzou; Cheng-Wei Lee; Wen-Lian Hsu

16

Occupational exposure to asbestos in New South Wales, Australia (1970–1989): development of an asbestos task exposure matrix  

Microsoft Academic Search

ObjectivesTo design and construct a standardised tool to provide exposure information associated with commonly used asbestos products and their related tasks in New South Wales (NSW), Australia.MethodsAsbestos dust exposure measurements taken during workplace inspections in the 1970s and 1980s were collected and stored in an exposure database. Measurements were assigned to specific asbestos product and task groups and divided into

Rebecca A Hyland; Deborah H Yates; Geza Benke; Malcolm Sim; Anthony R Johnson

2010-01-01

17

Tool and Task Analysis Guide for Vocational Welding (150 Tasks). Performance Based Vocational Education.  

ERIC Educational Resources Information Center

This book contains a task inventory, a task analysis of 150 tasks from that inventory, and a tool list for performance-based welding courses in the state of Indiana. The task inventory and tool list reflect 28 job titles found in Indiana. In the first part of the guide, tasks are listed by these domains: carbon-arc, electron beam, G.M.A.W., gas…

John H. Hinds Area Vocational School, Elwood, IN.

18

Grammar-based task analysis of web logs  

Microsoft Academic Search

The daily use of Internet-based services is involved with hundreds of different tasks being performed by multiple users. A single task is typically involved with a sequence of Web URLs invocation. We study the problem of pattern detection in Web logs to identify tasks performed by users, and analyze task trends over time using a grammar-based framework. Our results are

Savitha Srinivasan; Arnon Amir; Prasad M. Deshpande; Vladimir Zbarsky

2004-01-01

19

Automated Video Exposure Assessment of Repetitive Hand Activity Level for a Load Transfer Task  

PubMed Central

Objective A new method is described for automatically quantifying repetitive hand activity using digital video processing. Background The hand activity level (HAL) is widely used for evaluating repetitive hand work. Conventional methods using either a trained observer on or off site, or manual off site video analysis, are often considered inaccurate, cumbersome or impractical for routine work assessment. Method A cross correlation-based template-matching algorithm was programmed to track the motion trajectory of a selected region of interest over successive video frames for a single camera to measure repetition frequency, duty cycle and HAL. A simple paced load transfer task was used to simulate a repetitive industrial activity. Twelve participants were videoed performing the task for varying HAL conditions. The automatically predicted HAL was compared to the manually measured HAL using frame-by-frame video analysis. Results Predicted frequency, duty cycle and HAL were in concert with the manually measured HAL conditions. The linear regression slope of the automatically predicted values with respect to the manually measured values were 0.98 (R2=.79), 1.27 (R2=.63), and 1.06 (R2=.77) for frequency, duty cycle, and HAL respectively. Conclusion A proof-of-concept for automatic video-based direct exposure assessment was demonstrated. Application The video assessment method for repetitive motion is promising for automatic, unobtrusive, and objective exposure assessment, which may offer broad availability using a camera enabled mobile device for helping evaluate, prevent and control exposure to repetitive motions related to upper extremity injuries in the workplace.

Chen, Chia-Hsiung; Hu, Yu Hen; Yen, Thomas Y.

2014-01-01

20

Characterization of occupational exposures to cleaning products used for common cleaning tasks-a pilot study of hospital cleaners  

PubMed Central

Background In recent years, cleaning has been identified as an occupational risk because of an increased incidence of reported respiratory effects, such as asthma and asthma-like symptoms among cleaning workers. Due to the lack of systematic occupational hygiene analyses and workplace exposure data, it is not clear which cleaning-related exposures induce or aggravate asthma and other respiratory effects. Currently, there is a need for systematic evaluation of cleaning products ingredients and their exposures in the workplace. The objectives of this work were to: a) identify cleaning products' ingredients of concern with respect to respiratory and skin irritation and sensitization; and b) assess the potential for inhalation and dermal exposures to these ingredients during common cleaning tasks. Methods We prioritized ingredients of concern in cleaning products commonly used in several hospitals in Massachusetts. Methods included workplace interviews, reviews of product Materials Safety Data Sheets and the scientific literature on adverse health effects to humans, reviews of physico-chemical properties of cleaning ingredients, and occupational hygiene observational analyses. Furthermore, the potential for exposure in the workplace was assessed by conducting qualitative assessment of airborne exposures and semi-quantitative assessment of dermal exposures. Results Cleaning products used for common cleaning tasks were mixtures of many chemicals, including respiratory and dermal irritants and sensitizers. Examples of ingredients of concern include quaternary ammonium compounds, 2-butoxyethanol, and ethanolamines. Cleaning workers are at risk of acute and chronic inhalation exposures to volatile organic compounds (VOC) vapors and aerosols generated from product spraying, and dermal exposures mostly through hands. Conclusion Cleaning products are mixtures of many chemical ingredients that may impact workers' health through air and dermal exposures. Because cleaning exposures are a function of product formulations and product application procedures, a combination of product evaluation with workplace exposure assessment is critical in developing strategies for protecting workers from cleaning hazards. Our task based assessment methods allowed classification of tasks in different exposure categories, a strategy that can be employed by epidemiological investigations related to cleaning. The methods presented here can be used by occupational and environmental health practitioners to identify intervention strategies.

2009-01-01

21

Acute effects of 50 Hz magnetic field exposure on human visual task and cardiovascular performance  

SciTech Connect

One hundred subjects, males and females with ages ranging between 18 and 48 years, were studied under both field-exposed and sham-exposed conditions. A 50 Hz, 100 {micro}T magnetic field (MF) was used. To examine the effect of field exposure on performance, a two-alternative, forced-choice, duration-discrimination task with three levels of difficulty was used. The subject`s task was to decide which of two sequentially presented light flashes had the longer duration. The standard duration was 50 ms, and the alternative durations were 65, 100, or 125 ms. Both reaction time and percentage of correct responses were recorded for each subject. MF and sham exposure were for 9 min each. Blood pressure and heart rate were also measured before and following MF exposure and sham-exposure trials. The study was performed double blind, with the exposure order counterbalanced. Compared to sham exposure, MF exposure significantly decreased reaction time on the hardest level of the performance task. MF exposure did not reliably affect percentage correct or cardiovascular performance. It was demonstrated that a relatively high level of statistical power was the basis for the observed MF effect, and the need to pay closer attention to power levels in future research is discussed.

Whittington, C.J.; Podd, J.V.; Rapley, B.R. [Massey Univ., Palmerston North (New Zealand). Dept. of Psychology] [Massey Univ., Palmerston North (New Zealand). Dept. of Psychology

1996-05-01

22

Preventing skin cancer: findings of the Task Force on Community Preventive Services On reducing Exposure to Ultraviolet Light.  

PubMed

Rates of skin cancer, the most common cancer in the United States, are increasing. The most preventable risk factor for skin cancer is unprotected ultraviolet (UV) exposure. Seeking to identify effective approaches to reducing the incidence of skin cancer by improving individual and community efforts to reduce unprotected UV exposure, the Task Force on Community Preventive Services conducted systematic reviews of community interventions to reduce exposure to ultraviolet light and increase protective behaviors. The Task Force found sufficient evidence to recommend two interventions that are based on improvements in sun protective or "covering-up" behavior (wearing protective clothing including long-sleeved clothing or hats): educational and policy approaches in two settings--primary schools and recreational or tourism sites. They found insufficient evidence to determine the effectiveness of a range of other population-based interventions and recommended additional research in these areas: educational and policy approaches in child care centers, secondary schools and colleges, recreational or tourism sites for children, and workplaces; interventions conducted in health-care settings and targeted to both providers and children's parents or caregivers; media campaigns alone; and community wide multicomponent interventions. This report also presents additional information regarding the recommended community interventions, briefly describes how the reviews were conducted, provides resources for further information, and provides information that can help in applying the interventions locally. The U.S. Preventive Services Task Force conducted a systematic review of counseling by primary care clinicians to prevent skin cancer (CDC. Counseling to prevent skin cancer: recommendation and rationale of the U.S. Preventive Services Task Force. MMWR 2003;52[No. RR-15]:13-17), which is also included in this issue, the first jointly released findings from the Task Force on Community Preventive Services and the U.S. Preventive Services Task Force. PMID:14561953

Saraiya, Mona; Glanz, Karen; Briss, Peter; Nichols, Phyllis; White, Cornelia; Das, Debjani

2003-10-17

23

Abuse pattern of toluene exposure alters mouse behavior in a waiting-for-reward operant task  

Microsoft Academic Search

Abuse Pattern of Toluene Exposure Alters Mouse Behavior in a Waiting-for-Reward Operant Task. Bowen, S.E. and McDonald, P., Neurotoxicology and Teratology, 2008.Inhaling solvents for recreational purposes continues to be a world-wide public health concern. Toluene, a volatile solvent in many abused products, adversely affects the central nervous system. However, the long-term neurobehavioral effects of exposure to high-concentration, binge patterns typical

Scott E. Bowen; Phillip McDonald

2009-01-01

24

Task-based decomposition of factored POMDPs.  

PubMed

Recently, partially observable Markov decision processes (POMDP) solvers have shown the ability to scale up significantly using domain structure, such as factored representations. In many domains, the agent is required to complete a set of independent tasks. We propose to decompose a factored POMDP into a set of restricted POMDPs over subsets of task relevant state variables. We solve each such model independently, acquiring a value function. The combination of the value functions of the restricted POMDPs is then used to form a policy for the complete POMDP. We explain the process of identifying variables that correspond to tasks, and how to create a model restricted to a single task, or to a subset of tasks. We demonstrate our approach on a number of benchmarks from the factored POMDP literature, showing that our methods are applicable to models with more than 100 state variables. PMID:23757544

Shani, Guy

2014-02-01

25

Dental Aide: Task Analyses. Competency-Based Education.  

ERIC Educational Resources Information Center

This task analysis guide is intended to help teachers and administrators develop instructional materials and implement competency-based education in the dental aide program. Section 1 contains a validated task inventory for dental aide. For each task, applicable information pertaining to performance and enabling objectives, criterion-referenced…

Newport News Public Schools, VA.

26

Human perceptual learning: the effect of pre-exposure schedule depends on task demands.  

PubMed

The effects of the pre-exposure schedule (concurrent, intermixed, and blocked) to two similar visual stimuli were assessed in three different tasks. Participants were more accurate identifying one of two pre-exposed stimuli as the target by means of same/different judgments after concurrent than intermixed or blocked pre-exposures. Regardless of pre-exposure schedule, participants were accurate in identifying the same target stimulus in a subsequent multiple choice task. However, the other pre-exposed stimulus was incorrectly chosen as the target in a greater proportion after blocked than intermixed or concurrent pre-exposure. Finally, participants who received the blocked schedule showed a greater ability to construct the target in a puzzle test than those who received a concurrent or intermixed schedule. These results suggest that the effect of pre-exposure schedule may depend on task-specific demands. But all these results might be explained by a selective attention mechanism like that proposed by Gibson (1969) to account for perceptual learning. PMID:23022603

Angulo, Rocío; Alonso, Gumersinda

2012-11-01

27

Team Task Analysis: Identifying Tasks and Jobs That Are Team Based  

Microsoft Academic Search

This paper presents initial information on the development and validation of three team task analysis scales. These scales were designed to quantitatively assess the extent to which a group of tasks or a job is team based. During a 2-week period, 52 male students working in 4-person teams were trained to perform a complex highly interdependent computer-simulated combat mission consisting

Winfred Arthur; Bryan D. Edwards; Suzanne T. Bell; Anton J. Villado; Winston Bennett

2005-01-01

28

Applications of Task-Based Learning in TESOL  

ERIC Educational Resources Information Center

Why are many teachers around the world moving toward task-based learning (TBL)? This shift is based on the strong belief that TBL facilitates second language acquisition and makes second language learning and teaching more principled and effective. Based on insights gained from using tasks as research tools, this volume shows how teachers can use…

Shehadeh, Ali, Ed.; Coombe, Christine, Ed.

2010-01-01

29

Ordering design tasks based on coupling strengths  

NASA Technical Reports Server (NTRS)

The design process associated with large engineering systems requires an initial decomposition of the complex system into modules of design tasks which are coupled through the transference of output data. In analyzing or optimizing such a coupled system, it is essential to be able to determine which interactions figure prominently enough to significantly affect the accuracy of the system solution. Many decomposition approaches assume the capability is available to determine what design tasks and interactions exist and what order of execution will be imposed during the analysis process. Unfortunately, this is often a complex problem and beyond the capabilities of a human design manager. A new feature for DeMAID (Design Manager's Aid for Intelligent Decomposition) will allow the design manager to use coupling strength information to find a proper sequence for ordering the design tasks. In addition, these coupling strengths aid in deciding if certain tasks or couplings could be removed (or temporarily suspended) from consideration to achieve computational savings without a significant loss of system accuracy. New rules are presented and two small test cases are used to show the effects of using coupling strengths in this manner.

Rogers, James L., Jr.; Bloebaum, Christina L.

1994-01-01

30

Ordering Design Tasks Based on Coupling Strengths  

NASA Technical Reports Server (NTRS)

The design process associated with large engineering systems requires an initial decomposition of the complex system into modules of design tasks which are coupled through the transference of output data. In analyzing or optimizing such a coupled system, it is essential to be able to determine which interactions figure prominently enough to significantly affect the accuracy of the system solution. Many decomposition approaches assume the capability is available to determine what design tasks and interactions exist and what order of execution will be imposed during the analysis process. Unfortunately, this is often a complex problem and beyond the capabilities of a human design manager. A new feature for DeMAID (Design Manager's Aid for Intelligent Decomposition) will allow the design manager to use coupling strength information to find a proper sequence for ordering the design tasks. In addition, these coupling strengths aid in deciding if certain tasks or couplings could be removed (or temporarily suspended) from consideration to achieve computational savings without a significant loss of system accuracy. New rules are presented and two small test cases are used to show the effects of using coupling strengths in this manner.

Rogers, J. L.; Bloebaum, C. L.

1994-01-01

31

An evaluation of classification algorithms for manual material handling tasks based on data obtained using wearable technologies.  

PubMed

With recent progress in wearable measurement systems, physical exposures can be feasibly assessed at high precision in the workplace. Such systems, however, generally lack contextual information for a given job (e.g. task type, duration). To extract such information, we explored three classification algorithms to classify manual material handling (MMH) tasks during a simulated job in a laboratory, using several combinations of outputs from commercially available inertial motion capture and in-shoe pressure measurement systems. A total of 10 participants completed three replications of four cycles of a simulated job. Precision and recall values of ? ?90% and 80%, respectively, and errors in estimated task duration of < ?14%, could be achieved across the MMH task examined. Classification performance, however, varied between classification algorithms, input data sets and task types. Overall, combining wearable technology with task classification could be an effective approach for field-based exposure assessment, though field-testing is needed to demonstrate the applicability of this method. Practitioner Summary: Combining wearable technologies with task classification was explored to extract exposure context, specifically task type and duration. Results supported that task classification can facilitate the use of wearable technologies in field-based exposure assessment, specifically by aiding in task identification from within the rather large data sets obtained from these technologies. PMID:24724567

Kim, Sunwook; Nussbaum, Maury A

2014-07-01

32

An Agent-Based Cockpit Task Management System  

NASA Technical Reports Server (NTRS)

An agent-based program to facilitate Cockpit Task Management (CTM) in commercial transport aircraft is developed and evaluated. The agent-based program called the AgendaManager (AMgr) is described and evaluated in a part-task simulator study using airline pilots.

Funk, Ken

1997-01-01

33

The Creative task Creator: a tool for the generation of customized, Web-based creativity tasks.  

PubMed

This article presents a Web-based tool for the creation of divergent-thinking and open-ended creativity tasks. A Java program generates HTML forms with PHP scripting that run an Alternate Uses Task and/or open-ended response items. Researchers may specify their own instructions, objects, and time limits, or use default settings. Participants can also be prompted to select their best responses to the Alternate Uses Task (Silvia et al., 2008). Minimal programming knowledge is required. The program runs on any server, and responses are recorded in a standard MySQL database. Responses can be scored using the consensual assessment technique (Amabile, 1996) or Torrance's (1998) traditional scoring method. Adoption of this Web-based tool should facilitate creativity research across cultures and access to eminent creators. The Creative Task Creator may be downloaded from the Psychonomic Society's Archive of Norms, Stimuli, and Data, www.psychonomic.org/archive. PMID:19001404

Pretz, Jean E; Link, John A

2008-11-01

34

Facilitating Experience Reuse: Towards a Task-Based Approach  

NASA Astrophysics Data System (ADS)

This paper proposes a task-based approach to facilitate experience reuse in knowledge-intensive work environments, such as the domain of Technical Support. We first present a real-world motivating scenario, product technical support in a global IT enterprise, by studying of which key characteristics of the application domain and user requirements are drawn and analysed. We then develop the associated architecture for enabling the work experience reuse process to address the issues identified from the motivating scenario. Central to the approach is the task ontology that seamlessly integrates different components of the architecture. Work experience reuse amounts to the discovery and retrieval of task instances. In order to compare task instances, we introduce the dynamic weighted task similarity measure that is able to tuning similarity value against the dynamically changing task contextual information. A case study has been carried out to evaluate the proposed approach.

Du, Ying; Chen, Liming; Hu, Bo; Patterson, David; Wang, Hui

35

Vietnamese Children and Language-Based Processing Tasks  

ERIC Educational Resources Information Center

Purpose: Vietnamese children's performance on language-based processing tasks of fast-mapping (FM) word-learning and dynamic assessment (DA) word- and rule-learning tasks were investigated. Method: Twenty-one first- and second-generation Vietnamese preschool children participated in this study. All children were enrolled in 2 Head Start programs…

Hwa-Froelich, Deborah A.; Matsuo, Hisako

2005-01-01

36

The Video-Based Short Comment Writing Task  

ERIC Educational Resources Information Center

Composing from sources may no longer be the exclusive domain of reading-to-write activities. The ever-increasing presence of video technology and broadcasting in academic settings could place listening-to-write tasks on a similar footing. This article describes a listening-to-write task, the video-based short comment, which (1) uses video as…

Pino-Silva, Juan

2007-01-01

37

IT-Based Open Learning: Tasks and Tools.  

ERIC Educational Resources Information Center

Discussion of the Just-in-Time Open Learning (JITOL) project supported by the European Commission in its DELTA Programme considers attributes of open learning and the main tasks of learners and tutors. Information technology-based tools for open learning are described and related to these tasks, and planned JITOL user trials are summarized. (17…

Goodyear, P.; Steeples, C.

1992-01-01

38

A Guide to Task Analysis for Competency Based Education. Trade and Technical Programs. Task Linkage Project Publication No. 2.  

ERIC Educational Resources Information Center

Developed through synthesis and review of existing task analysis literature, this guide lists tasks expected to be performed by workers in nine trade and industrial occupations and presents information for incorporating these tasks into articulated secondary and postsecondary competency based vocational education programs. Task listings are…

Georgia State Univ., Atlanta. School of Education.

39

Modeling a Team-Based Astronomy task Using LAMS  

Microsoft Academic Search

This presentation discusses modeling of a team-based astronomy task for school students using LAMS (the learning activity management system) including consideration of modeling and run-time issues, and facilities for observation, traces and adaptation

James Roland Dalziel

2006-01-01

40

Modeling a Team-Based Astronomy task Using LAMS  

Microsoft Academic Search

This presentation discusses modeling of a team- based astronomy task for school students using LAMS (the Learning Activity Management System) including consideration of modeling and run-time issues, and facilities for observation, traces and adaptation.

James Roland Dalziel

2006-01-01

41

Tinkering with Tasks Knows No Bounds: ESL Teachers' Adaptations of Task-Based Language-Teaching  

ERIC Educational Resources Information Center

Research on implementing task-based language-teaching (TBLT) shows that adapting TBLT in ways that are inconsistent with its principles is common among nonnative-speaker English-as-a-foreign-language teachers. Our study of Canadian native-speaker English-as-a-second language teachers reveals how they also adapt TBLT in ways that are incongruent…

Plews, John L.; Zhao, Kangxian

2010-01-01

42

Gender differences in workers with identical repetitive industrial tasks: exposure and musculoskeletal disorders  

Microsoft Academic Search

Objectives  For unknown reasons, females run a higher risk than males of work-related musculoskeletal disorders. The aim of this study\\u000a was to evaluate whether male and female workers, with identical repetitive work tasks, differ concerning risk of disorders,\\u000a physical or psychosocial exposures.\\u000a \\u000a \\u000a \\u000a Methods  Employees in two industries were studied; one rubber manufacturing and one mechanical assembly plant. These industries were\\u000a selected since

Catarina Nordander; Kerstina Ohlsson; Istvan Balogh; Gert-Åke Hansson; Anna Axmon; Roger Persson; Staffan Skerfving

2008-01-01

43

Age-Based Differences in Strategy Use in Choice Tasks  

PubMed Central

We incorporated behavioral and computational modeling techniques to examine age-based differences in strategy use in two four-choice decision-making tasks. Healthy older (aged 60–82?years) and younger adults (aged 18–23?years) performed one of two decision-making tasks that differed in the degree to which rewards for each option depended on the choices made on previous trials. In the choice-independent task rewards for each choice were not affected by the sequence of previous choices that had been made. In contrast, in the choice-dependent task rewards for each option were based on how often each option had been chosen in the past. We compared the fits of a model that assumes the use of a win-stay–lose-shift (WSLS) heuristic to make decisions, to the fits of a reinforcement-learning (RL) model that compared expected reward values for each option to make decisions. Younger adults were best fit by the RL model, while older adults showed significantly more evidence of being best fit by the WSLS heuristic model. This led older adults to perform worse than younger adults in the choice-independent task, but better in the choice-dependent task. These results coincide with previous work in our labs that also found better performance for older adults in choice-dependent tasks (Worthy et al., 2011), and the present results suggest that qualitative age-based differences in the strategies used in choice tasks may underlie older adults’ advantage in choice-dependent tasks. We discuss possible factors behind these differences such as neurobiological changes associated with aging, and increased use of heuristics by older adults.

Worthy, Darrell A.; Maddox, W. Todd

2012-01-01

44

Context-Based Task Ontologies for Clinical Guidelines  

Microsoft Academic Search

Evidence-based medicine relies on the execution of clinical practice guidelines and protocols. A great deal of effort has been invested in the development of tools which can automate the representation and execution of the recommendations contained within such guidelines, by creating Computer Interpretable Guideline Models (CIGMs). Context-based task ontologies (CTOs), based on standard terminology systems like UMLS, form one of

Anand KUMAR; Paolo CICCARESE; Barry SMITH; Matteo PIAZZA

45

Towards continualized task-based resolution modeling in PET imaging  

NASA Astrophysics Data System (ADS)

We propose a generalized resolution modeling (RM) framework, including extensive task-based optimization, wherein we continualize the conventionally discrete framework of RM vs. no RM, to include varying degrees of RM. The proposed framework has the advantage of providing a trade-off between the enhanced contrast recovery by RM and the reduced inter-voxel correlations in the absence of RM, and to enable improved task performance. The investigated context was that of oncologic lung FDG PET imaging. Given a realistic blurring kernel of FWHM h (`true PSF'), we performed iterative EM including RM using a wide range of `modeled PSF' kernels with varying widths h. In our simulations, h = 6mm, while h varied from 0 (no RM) to 12mm, thus considering both underestimation and overestimation of the true PSF. Detection task performance was performed using prewhitened (PWMF) and nonprewhitened matched filter (NPWMF) observers. It was demonstrated that an underestimated resolution blur (h = 4mm) enhanced task performance, while slight over-estimation (h = 7mm) also achieved enhanced performance. The latter is ironically attributed to the presence of ringing artifacts. Nonetheless, in the case of the NPWMF, the increasing intervoxel correlations with increasing values of h degrade detection task performance, and underestimation of the true PSF provides the optimal task performance. The proposed framework also achieves significant improvement of reproducibility, which is critical in quantitative imaging tasks such as treatment response monitoring.

Ashrafinia, Saeed; Karakatsanis, Nicolas; Mohy-ud-Din, Hassan; Rahmim, Arman

2014-03-01

46

EFL Reading Instruction: Communicative Task-Based Approach  

ERIC Educational Resources Information Center

The purpose of this study was to examine the overarching framework of EFL (English as a Foreign Language) reading instructional approach reflected in an EFL secondary school curriculum in Malaysia. Based on such analysis, a comparison was made if Communicative Task-Based Language is the overarching instructional approach for the Malaysian EFL…

Sidek, Harison Mohd

2012-01-01

47

Lead exposure and (n-3) fatty acid deficiency during rat neonatal development affect subsequent spatial task performance and olfactory discrimination.  

PubMed

Docosahexaenoic acid [22:6(n-3), DHA] is important for optimal infant central nervous system development, and lead (Pb) exposure during development can produce neurological deficits. Long-Evans strain rats were fed either an (n-3) deficient [(n-3) Def] diet to produce brain DHA deficiency, or an adequate [(n-3) Adq] diet through 2 generations. At the birth of the 2nd generation, the dams were subdivided into 4 groups and supplied drinking water containing either 5.27 mmol/L (Pb) or sodium (Na) acetate until weaning. Rats were killed at 3 wk (weaning) and 11 wk (maturity) for brain Pb and fatty acid analysis. Spatial task and olfactory-cued behavioral assessments were initiated at 9 wk. Rats in the (n-3) Def group had a 79% lower concentration of brain DHA compared with the (n-3) Adq group with no effect of Pb exposure. At weaning, Pb concentrations were 7.17 +/- 0.47 nmol Pb/g of brain (wet weight) in the (n-3) Adq-Pb group and 6.49 +/- 0.63 nmol Pb/g of brain (wet weight) in the (n-3) Def-Pb group. At maturity, the brains contained 1.30 +/- 0.22 and 1.07 +/- 0.12 nmol Pb/g (wet weight), respectively. In behavioral testing, significant effects of both Pb and DHA deficiency were observed in the Morris water maze probe trial and in 2-odor olfactory discrimination acquisition and olfactory-based reversal learning tasks. Both lactational Pb exposure and (n-3) fatty acid deficiency led to behavioral deficits with additive effects observed only in the acquisition of 2-odor discriminations. PMID:15867275

Lim, Sun-Young; Doherty, John D; McBride, Kathleen; Miller-Ihli, Nancy J; Carmona, Gilberto N; Stark, Ken D; Salem, Norman

2005-05-01

48

An ontology-based telemedicine tasks management system architecture.  

PubMed

The recent developments in ambient intelligence and ubiquitous computing offer new opportunities for the design of advanced Telemedicine systems providing high quality services, anywhere, anytime. In this paper we present an approach for building an ontology-based task-driven telemedicine system. The architecture is composed of a task management server, a communication server and a knowledge base for enabling decision makings taking account of different telemedical concepts such as actors, resources, services and the Electronic Health Record. The final objective is to provide an intelligent management of the different types of available human, material and communication resources. PMID:19162954

Nageba, Ebrahim; Fayn, Jocelyne; Rubel, Paul

2008-01-01

49

Reward-based learning of a redundant task.  

PubMed

Motor skill learning has different components. When we acquire a new motor skill we have both to learn a reliable action-value map to select a highly rewarded action (task model) and to develop an internal representation of the novel dynamics of the task environment, in order to execute properly the action previously selected (internal model). Here we focus on a 'pure' motor skill learning task, in which adaptation to a novel dynamical environment is negligible and the problem is reduced to the acquisition of an action-value map, only based on knowledge of results. Subjects performed point-to-point movement, in which start and target positions were fixed and visible, but the score provided at the end of the movement depended on the distance of the trajectory from a hidden viapoint. Subjects did not have clues on the correct movement other than the score value. The task is highly redundant, as infinite trajectories are compatible with the maximum score. Our aim was to capture the strategies subjects use in the exploration of the task space and in the exploitation of the task redundancy during learning. The main findings were that (i) subjects did not converge to a unique solution; rather, their final trajectories are determined by subject-specific history of exploration. (ii) with learning, subjects reduced the trajectory's overall variability, but the point of minimum variability gradually shifted toward the portion of the trajectory closer to the hidden via-point. PMID:24187205

Tamagnone, Irene; Casadio, Maura; Sanguineti, Vittorio

2013-06-01

50

Lead exposure among workers renovating a previously deleaded bridge: comparison of trades, work tasks.  

PubMed

Airborne and surface lead exposures were evaluated for construction trade groups at a previously deleaded bridge renovation site in the midwestern United States. Although all lead-based paint should have been removed, old layers of leaded paint were still present on some sections of the bridge. Ironworkers performing metal torch cutting had the highest exposures (188 microg/m3), followed by workers engaged in clean-up operations and paint removal (p < 0.001). Respirators were most frequently worn by workers with the greatest lead exposures; however, laborers performing clean-up operations had exposures to lead dust of 43 microg/m3 and often wore no respiratory protection. Wipe samples revealed that almost all contractor vehicles were contaminated with lead. Heavy equipment operators with low airborne lead exposure had the highest levels of surface contamination in personal vehicles (3,600 microg/m2). Laborers cleaning structural steel with compressed air and ironworkers exposed to lead fumes from cutting had the highest concentrations of lead dust on clothing (mean 4,766 microg/m2). Handwashing facilities were provided, but were infrequently used. No separate clothes changing facility was available at the site. The potential for "take-home" contamination was high, even though this site was thought to be relatively free of lead. Construction contractors and their workers need to be aware that previous deleading of a site may not preclude exposure to significant amounts of lead. PMID:11192213

Johnson, J C; Reynolds, S J; Fuortes, L J; Clarke, W R

2000-01-01

51

POPULATION-BASED EXPOSURE AND DOSE MODELING FOR AIR POLLUTANTS  

EPA Science Inventory

This task will address EPA's need to better understand the variability in personal exposure to air pollutants for the purpose of assessing what populations are at risk for adverse health outcomes due to air pollutant exposures. To improve our understanding of exposures to air po...

52

Children's Creative Collaboration during a Computer-Based Music Task  

ERIC Educational Resources Information Center

The purpose of this study was to identify and analyse specific instances of transactive communication as children engaged in a paired melody writing task using a computer-based composing environment. Transactive communication has been identified as one of the features of general collaborative engagement that is most helpful in an educational…

Hewitt, Allan

2008-01-01

53

Designing Spreadsheet-Based Tasks for Purposeful Algebra  

ERIC Educational Resources Information Center

We describe the design of a sequence of spreadsheet-based pedagogic tasks for the introduction of algebra in the early years of secondary schooling within the Purposeful Algebraic Activity project. This design combines two relatively novel features to bring a different perspective to research in the use of spreadsheets for the learning and…

Ainley, Janet; Bills, Liz; Wilson, Kirsty

2005-01-01

54

Television-Based Reading Instruction, Reading Achievement, and Task Involvement.  

ERIC Educational Resources Information Center

This study focused on whether reading instruction based on popular youth-oriented television programs increases task involvement or reading achievement scores. After one year, reading scores of classes using television scripts, in addition to regular materials, were significantly higher than those of nontreatment classes. (JN)

Szabo, Michael; Lamiell-Landy, Ann

1981-01-01

55

Task-based Learning (TBL) in Undergraduate Medical Education.  

ERIC Educational Resources Information Center

Describes task-based learning (TBL), a study module for fourth-year medical students (n=85), and experiences with implementing it at the University of Tampere in Finland. Indicates that this method works and that it leads to learning. Students evaluate their skills connected with a general practitioner's work in health center hospitals as better…

Virjo, Irma; Holmberg-Marttila, Doris; Mattila, Kari

2001-01-01

56

An exposure indicator for digital radiography: AAPM Task Group 116 (Executive Summary)  

SciTech Connect

Digital radiographic imaging systems, such as those using photostimulable storage phosphor, amorphous selenium, amorphous silicon, CCD, and MOSFET technology, can produce adequate image quality over a much broader range of exposure levels than that of screen/film imaging systems. In screen/film imaging, the final image brightness and contrast are indicative of over- and underexposure. In digital imaging, brightness and contrast are often determined entirely by digital postprocessing of the acquired image data. Overexposure and underexposures are not readily recognizable. As a result, patient dose has a tendency to gradually increase over time after a department converts from screen/film-based imaging to digital radiographic imaging. The purpose of this report is to recommend a standard indicator which reflects the radiation exposure that is incident on a detector after every exposure event and that reflects the noise levels present in the image data. The intent is to facilitate the production of consistent, high quality digital radiographic images at acceptable patient doses. This should be based not on image optical density or brightness but on feedback regarding the detector exposure provided and actively monitored by the imaging system. A standard beam calibration condition is recommended that is based on RQA5 but uses filtration materials that are commonly available and simple to use. Recommendations on clinical implementation of the indices to control image quality and patient dose are derived from historical tolerance limits and presented as guidelines.

Shepard, S. Jeff; Wang Jihong; Flynn, Michael [Imaging Physics Department 056, Division of Diagnostic Imaging, University of Texas M. D. Anderson Cancer Center, 1515 Holcombe Boulevard, Houston, Texas 77030 (United States); and others

2009-07-15

57

An exposure indicator for digital radiography: AAPM Task Group 116 (executive summary).  

PubMed

Digital radiographic imaging systems, such as those using photostimulable storage phosphor, amorphous selenium, amorphous silicon, CCD, and MOSFET technology, can produce adequate image quality over a much broader range of exposure levels than that of screen/film imaging systems. In screen/film imaging, the final image brightness and contrast are indicative of over- and underexposure. In digital imaging, brightness and contrast are often determined entirely by digital postprocessing of the acquired image data. Overexposure and underexposures are not readily recognizable. As a result, patient dose has a tendency to gradually increase over time after a department converts from screen/film-based imaging to digital radiographic imaging. The purpose of this report is to recommend a standard indicator which reflects the radiation exposure that is incident on a detector after every exposure event and that reflects the noise levels present in the image data. The intent is to facilitate the production of consistent, high quality digital radiographic images at acceptable patient doses. This should be based not on image optical density or brightness but on feedback regarding the detector exposure provided and actively monitored by the imaging system. A standard beam calibration condition is recommended that is based on RQA5 but uses filtration materials that are commonly available and simple to use. Recommendations on clinical implementation of the indices to control image quality and patient dose are derived from historical tolerance limits and presented as guidelines. PMID:19673189

Shepard, S Jeff; Wang, Jihong; Flynn, Michael; Gingold, Eric; Goldman, Lee; Krugh, Kerry; Leong, David L; Mah, Eugene; Ogden, Kent; Peck, Donald; Samei, Ehsan; Wang, Jihong; Willis, Charles E

2009-07-01

58

Automatic Test Task Allocation in Agent-Based Distributed Automated Testing Framework  

Microsoft Academic Search

In this paper, agent-based distributed automated testing framework is proposed, and for the current lack of automatic test task allocation function in distributed automated testing framework, an approach of automatic test task allocation based on the test node ability is given. The complex test task is broken down into atomic test tasks, the test tasks in the test definition file

Gao Jing; Lan Yuqing

2009-01-01

59

Evaluating the Semantic Web: A Task-Based Approach  

NASA Astrophysics Data System (ADS)

The increased availability of online knowledge has led to the design of several algorithms that solve a variety of tasks by harvesting the Semantic Web, i.e., by dynamically selecting and exploring a multitude of online ontologies. Our hypothesis is that the performance of such novel algorithms implicitly provides an insight into the quality of the used ontologies and thus opens the way to a task-based evaluation of the Semantic Web. We have investigated this hypothesis by studying the lessons learnt about online ontologies when used to solve three tasks: ontology matching, folksonomy enrichment, and word sense disambiguation. Our analysis leads to a suit of conclusions about the status of the Semantic Web, which highlight a number of strengths and weaknesses of the semantic information available online and complement the findings of other analysis of the Semantic Web landscape.

Sabou, Marta; Gracia, Jorge; Angeletou, Sofia; D'Aquin, Mathieu; Motta, Enrico

60

The Nature of Impulsivity: Visual Exposure to Natural Environments Decreases Impulsive Decision-Making in a Delay Discounting Task  

PubMed Central

The benefits of visual exposure to natural environments for human well-being in areas of stress reduction, mood improvement, and attention restoration are well documented, but the effects of natural environments on impulsive decision-making remain unknown. Impulsive decision-making in delay discounting offers generality, predictive validity, and insight into decision-making related to unhealthy behaviors. The present experiment evaluated differences in such decision-making in humans experiencing visual exposure to one of the following conditions: natural (e.g., mountains), built (e.g., buildings), or control (e.g., triangles) using a delay discounting task that required participants to choose between immediate and delayed hypothetical monetary outcomes. Participants viewed the images before and during the delay discounting task. Participants were less impulsive in the condition providing visual exposure to natural scenes compared to built and geometric scenes. Results suggest that exposure to natural environments results in decreased impulsive decision-making relative to built environments.

Berry, Meredith S.; Sweeney, Mary M.; Morath, Justice; Odum, Amy L.; Jordan, Kerry E.

2014-01-01

61

Cluster-based exposure variation analysis  

PubMed Central

Background Static posture, repetitive movements and lack of physical variation are known risk factors for work-related musculoskeletal disorders, and thus needs to be properly assessed in occupational studies. The aims of this study were (i) to investigate the effectiveness of a conventional exposure variation analysis (EVA) in discriminating exposure time lines and (ii) to compare it with a new cluster-based method for analysis of exposure variation. Methods For this purpose, we simulated a repeated cyclic exposure varying within each cycle between “low” and “high” exposure levels in a “near” or “far” range, and with “low” or “high” velocities (exposure change rates). The duration of each cycle was also manipulated by selecting a “small” or “large” standard deviation of the cycle time. Theses parameters reflected three dimensions of exposure variation, i.e. range, frequency and temporal similarity. Each simulation trace included two realizations of 100 concatenated cycles with either low (??=?0.1), medium (??=?0.5) or high (??=?0.9) correlation between the realizations. These traces were analyzed by conventional EVA, and a novel cluster-based EVA (C-EVA). Principal component analysis (PCA) was applied on the marginal distributions of 1) the EVA of each of the realizations (univariate approach), 2) a combination of the EVA of both realizations (multivariate approach) and 3) C-EVA. The least number of principal components describing more than 90% of variability in each case was selected and the projection of marginal distributions along the selected principal component was calculated. A linear classifier was then applied to these projections to discriminate between the simulated exposure patterns, and the accuracy of classified realizations was determined. Results C-EVA classified exposures more correctly than univariate and multivariate EVA approaches; classification accuracy was 49%, 47% and 52% for EVA (univariate and multivariate), and C-EVA, respectively (p?exposure patterns differing with respect to the variability in cycle time duration. Conclusion While C-EVA had a higher accuracy than conventional EVA, both failed to detect differences in temporal similarity. The data-driven optimality of data reduction and the capability of handling multiple exposure time lines in a single analysis are the advantages of the C-EVA.

2013-01-01

62

Task-based optimization of image reconstruction in breast CT  

NASA Astrophysics Data System (ADS)

We demonstrate a task-based assessment of image quality in dedicated breast CT in order to optimize the number of projection views acquired. The methodology we employ is based on the Hotelling Observer (HO) and its associated metrics. We consider two tasks: the Rayleigh task of discerning between two resolvable objects and a single larger object, and the signal detection task of classifying an image as belonging to either a signalpresent or signal-absent hypothesis. HO SNR values are computed for 50, 100, 200, 500, and 1000 projection view images, with the total imaging radiation dose held constant. We use the conventional fan-beam FBP algorithm and investigate the effect of varying the width of a Hanning window used in the reconstruction, since this affects both the noise properties of the image and the under-sampling artifacts which can arise in the case of sparse-view acquisitions. Our results demonstrate that fewer projection views should be used in order to increase HO performance, which in this case constitutes an upper-bound on human observer performance. However, the impact on HO SNR of using fewer projection views, each with a higher dose, is not as significant as the impact of employing regularization in the FBP reconstruction through a Hanning filter.

Sanchez, Adrian A.; Sidky, Emil Y.; Pan, Xiaochuan

2014-03-01

63

Assessing task compliance following mobile phone-based video reminders.  

PubMed

In the development of technology for people with mild dementia it is essential to achieve a combination of the features which provide both support and monitoring along with the ability to offer a level of personalization. Reminding support by means of personalized video reminders portraying a relative or friend combined with sensors to assess whether the requested task was performed lends itself as an ideal combination to achieve this aim. This study assesses the potential of using low cost, off the shelf sensors combined with a mobile phone-based video reminding system to assess compliance with task completion. A validation study has been conducted in a lab-based environment with 10 healthy young participants. The work presented discusses the implementation of the approach adopted, data analysis of the results attained along with outlining future developments of this approach. PMID:22255533

O'Neill, Sonja A; Parente, Guido; Donnelly, Mark P; Nugent, Chris D; Beattie, Mark P; McClean, Sally I; Scotney, Bryan W; Mason, Sarah C; Craig, David

2011-01-01

64

Prototype Videodisk-Based Part-Task Thermal Imaging Trainer  

NASA Technical Reports Server (NTRS)

Thermal images, or infrared images, are representations of the world based on heat, instead of visible light. Research has shown that the resulting thermal image results in perceptual differences leading to difficulties in interpretation (e.g., the determination of slope angle, concavity/convexity), or increased identification latencies. A joint research project between the United States (NASA and U.S. Army) and Israel (Ministry of Defense and Israel Air Force) has resulted in the development of a prototype part-task trainer for the acquisition of perceptual skills associated with thermal imaging usage. This prototype system is videodisk-based under computer control, using recordings of thermal images. A lesson section introduces declarative knowledge, in which the basic physics and heuristics of thermal imagery are taught. An exercise section teaches procedural knowledge, with the user viewing dynamic, actual imagery, with an interactive detection/location determination task. The general philosophy and design of the trainer will be demonstrated.

Brickner, Michael S.; Foyle, David C.; Sridhar, Banavar (Technical Monitor)

1995-01-01

65

NEGATIVE FEEDBACK AND POSITIVE EVIDENCE IN TASK-BASED INTERACTION  

Microsoft Academic Search

This study examines the role of task-based conversation in second language (L2) grammatical development, focusing on the short-term effects of both negative feedback and positive evidence on the ac- quisition of two Japanese structures. The data are drawn from 55 L2 learners of Japanese at a beginning level of proficiency in an Austra- lian tertiary institution. Five different types of

Noriko Iwashita

2003-01-01

66

Worker lead exposures during renovation of homes with lead-based paint  

SciTech Connect

The authors evaluated lead exposures among full-time home renovators and part-time volunteers working primarily in pre-1960 homes with lead-based paint. Potentially hazardous lead exposures were measured during two tasks: exterior dry scraping and wet scraping. Maximum exposures were 120 and 63 {micro}g/m{sup 3}, respectively. Exposures during other tasks, including general repair, weatherization, exterior scraping/painting, window replacement, demolition, and plumbing, were low, as were all 13 full-shift personal exposures. Blood lead levels for full-time workers ranged up to 17.5 {micro}g/dl, with a GM of 5.2 {micro}g/dl; the GM for volunteers was 3.2 {micro}g/dl. All of the paint samples collected from work surfaces had detectable amounts of lead, with 65% of the work surfaces tested having an average lead concentration of >0.5%.

Sussell, A.; Gittleman, J.; Singal, M. [National Inst. for Occupational Safety and Health, Cincinnati, OH (United States)

1998-11-01

67

Effect of continuous gamma-ray exposure on performance of learned tasks and effect of subsequent fractionated exposures on blood-forming tissue  

NASA Technical Reports Server (NTRS)

Sixteen monkeys trained to perform continuous and discrete-avoidance and fixed-ratio tasks with visual and auditory cues were performance-tested before, during, and after 10-day gamma-ray exposures totaling 0, 500, 750, and 1000 rads. Approximately 14 months after the performance-test exposures, surviving animals were exposed to 100-rad gamma-ray fractions at 56-day intervals to observe injury and recovery patterns of blood-forming tissues. The fixed-ratio, food-reward task performance showed a transient decline in all dose groups within 24 hours of the start of gamma-ray exposure, followed by recovery to normal food-consumption levels within 48 to 72 hours. Avoidance tasks were performed successfully by all groups during the 10-day exposure, but reaction times of the two higher dose-rate groups in which animals received 3 and 4 rads per hour or total doses of 750 and 1000 rads, respectively, were somewhat slower.

Spalding, J. F.; Holland, L. M.; Prine, J. R.; Farrer, D. N.; Braun, R. G.

1972-01-01

68

Comparing antimicrobial exposure based on sales data.  

PubMed

This paper explores the possibilities of making meaningful comparisons of the veterinary use of antimicrobial agents among countries, based on national total sales data. Veterinary antimicrobial sales data on country level and animal census data in both Denmark and the Netherlands were combined with information about estimated average dosages, to make model calculations of the average number of treatment days per average animal per year, at first based on the assumption that the treatment incidence is the same in all species and production types. Secondly, the exposure in respectively animals for meat production and dairy and other cattle (excluding veal and young beef) was estimated, assuming zero use in the dairy and other cattle, and thirdly by assuming respectively 100% oral and 100% parenteral administration. Subsequently, the outcomes of these model calculations were compared with treatment incidences calculated from detailed use data per animal species from the national surveillance programmes in these two countries, to assess their accuracy and relevancy. In Denmark and in the Netherlands, although the computed antimicrobial exposure would seem to be a reasonable estimation of the exposure for all animals as a whole, it differs significantly from the measured exposure for most species. The differences in exposure among animal species were much higher than the overall difference between the two countries. For example, the overall model estimate of 9 treatment days per year for Denmark is a severe overestimation of the true use in poultry (i.e. 3 days), and the overall model estimate of 13 treatment days per year for the Netherlands is a severe underestimation of the true use in veal calves (i.e. 66 days). The conclusion is that simple country comparisons, based on total sales figures, entail the risk of serious misinterpretations, especially if expressed in mg per kg. The use of more precise model calculations for making such comparisons, taking into account differences in dosages and in farm animal demographics, only slightly reduces this risk. Overall model estimates are strongly influenced by animal demographics and a very inaccurate indication of the true differences in exposure, per animal species. To get an appropriate certainty about the true differences in antimicrobial exposure between countries it is an absolute necessity to have reliable information about the use per animal species. PMID:22897857

Bondt, Nico; Jensen, Vibeke Frøkjær; Puister-Jansen, Linda F; van Geijlswijk, Ingeborg M

2013-01-01

69

Emotion-based learning: insights from the Iowa Gambling Task.  

PubMed

Interest in the cognitive and/or emotional basis of complex decision-making, and the related phenomenon of emotion-based learning, has been heavily influenced by the Iowa Gambling Task. A number of psychological variables have been investigated as potentially important in understanding emotion-based learning. This paper reviews the extent to which humans are explicitly aware of how we make such decisions; the biasing influence of pre-existing emotional labels; and the extent to which emotion-based systems are anatomically and functionally independent of episodic memory. Review of literature suggests that (i) an aspect of conscious awareness does appear to be readily achieved during the IGT, but as a relatively unfocused emotion-based "gut-feeling," akin to intuition; (ii) Several studies have manipulated the affective pre-loading of IGT tasks, and make it clear that such labeling has a substantial influence on performance, an experimental manipulation similar to the phenomenon of prejudice. (iii) Finally, it appears that complex emotion-based learning can remain intact despite profound amnesia, at least in some neurological patients, a finding with a range of potentially important clinical implications: in the management of dementia; in explaining infantile amnesia; and in understanding of the possible mechanisms of psychotherapy. PMID:24711796

Turnbull, Oliver H; Bowman, Caroline H; Shanker, Shanti; Davies, Julie L

2014-01-01

70

Task-based lens design, with application to digital mammography  

NASA Astrophysics Data System (ADS)

Recent advances in model observers that predict human perceptual performance now make it possible to optimize medical imaging systems for human task performance. We illustrate the procedure by considering the design of a lens for use in an optically coupled digital mammography system. The channelized Hotelling observer is used to model human performance, and the channels chosen are differences of Gaussians (DOGs). The task performed by the model observer is detection of a lesion at a random but known location in a clustered lumpy background mimicking breast tissue. The entire system is simulated with a Monte Carlo application according to the physics principles, and the main system component under study is the imaging lens that couples a fluorescent screen to a CCD detector. The SNR of the channelized Hotelling observer is used to quantify the detectability of the simulated lesion (signal) upon the simulated mammographic background. In this work, plots of channelized Hotelling SNR vs. signal location for various lens apertures, various working distances, and various focusing places are shown. These plots thus illustrate the trade-off between coupling efficiency and blur in a task-based manner. In this way, the channelized Hotelling SNR is used as a merit function for lens design.

Chen, Liying

71

Task-based lens design with application to digital mammography  

PubMed Central

Recent advances in model observers that predict human perceptual performance now make it possible to optimize medical imaging systems for human task performance. We illustrate the procedure by considering the design of a lens for use in an optically coupled digital mammography system. The channelized Hotelling observer is used to model human performance, and the channels chosen are differences of Gaussians. The task performed by the model observer is detection of a lesion at a random but known location in a clustered lumpy background mimicking breast tissue. The entire system is simulated with a Monte Carlo application according to physics principles, and the main system component under study is the imaging lens that couples a fluorescent screen to a CCD detector. The signal-to-noise ratio (SNR) of the channelized Hotelling observer is used to quantify this detectability of the simulated lesion (signal) on the simulated mammographic background. Plots of channelized Hotelling SNR versus signal location for various lens apertures, various working distances, and various focusing places are presented. These plots thus illustrate the trade-off between coupling efficiency and blur in a task-based manner. In this way, the channelized Hotelling SNR is used as a merit function for lens design.

Chen, Liying; Barrett, Harrison H.

2006-01-01

72

Hierarchical Matrix-Matrix Multiplication Based on Multiprocessor Tasks  

Microsoft Academic Search

We consider the realization of matrix-matrix multiplication and propose a hierarchical algorithm implemented in a task-parallel way using multiprocessor tasks on distributed memory. The algorithm has been designed to minimize the communication overhead while showing large locality of memory references. The task-parallel realization makes the algorithm especially suited for cluster of SMPs since tasks can then be mapped to the

Sascha Hunold; Thomas Rauber; Gudula Rünger

2004-01-01

73

The Task-Based Approach: Some Questions and Suggestions  

ERIC Educational Resources Information Center

This article first addresses the question of what tasks are. It suggests that rather than accept the common "communicative" definition, we should return to a broader definition and then focus on key dimensions that distinguish (from the learner's perspective) different types of task, notably degrees of task involvement and degrees of focus on form…

Littlewood, William

2004-01-01

74

Creative Disruption: A Task-Based Approach to Engaging With Original Works of Art  

ERIC Educational Resources Information Center

This paper examines the value of a task-based approach to engaging with original works of art and focuses in particular upon the experiences of a group of PGCE Art and Design trainees when they visited an exhibition entitled, Air Guitar: Art Reconsidering Rock Music, to carry out given tasks. The extent to which a task-based approach might…

Walker, Keith; Smith, Liz

2004-01-01

75

Gradient Field-Based Task Assignment in an AGV Transportation System  

Microsoft Academic Search

Assigning tasks to agents is complex, especially in highly dynamic environments. Typical protocol-based approaches for task assign- ment such as Contract Net have proven their value, however, they may not be flexible enough to cope with continuously changing cir- cumstances. In this paper we study and validate the feasibility of a field-based approach for task assignment in a complex problem

Danny Weyns; Nelis Boucké; Tom Holvoet; Wannes Schols

2005-01-01

76

Task technical and QA plan: Thermal effects study: To evaluate saltstone properties associated with performance criteria as a function of extended exposure to temperatures typical of adiabatic curing  

Microsoft Academic Search

The task to evaluate saltstone properties associated with performance criteria as a function of extended exposure to temperatures typical of adiabatic curing is described in this document and involves extension of previous qualification studies for DWPF Saltstone formulations.

Orebaugh

1990-01-01

77

A task-based approach for Gene Ontology evaluation  

PubMed Central

Background The Gene Ontology and its associated annotations are critical tools for interpreting lists of genes. Here, we introduce a method for evaluating the Gene Ontology annotations and structure based on the impact they have on gene set enrichment analysis, along with an example implementation. This task-based approach yields quantitative assessments grounded in experimental data and anchored tightly to the primary use of the annotations. Results Applied to specific areas of biological interest, our framework allowed us to understand the progress of annotation and structural ontology changes from 2004 to 2012. Our framework was also able to determine that the quality of annotations and structure in the area under test have been improving in their ability to recall underlying biological traits. Furthermore, we were able to distinguish between the impact of changes to the annotation sets and ontology structure. Conclusion Our framework and implementation lay the groundwork for a powerful tool in evaluating the usefulness of the Gene Ontology. We demonstrate both the flexibility and the power of this approach in evaluating the current and past state of the Gene Ontology as well as its applicability in developing new methods for creating gene annotations.

2013-01-01

78

On the Tractability of Digraph-Based Task Models  

Microsoft Academic Search

In formal analysis of real-time systems, a major concern is the analysis efficiency. As the expressiveness of models grows, so grows the complexity of their analysis. A recently pro- posed model, the digraph real-time task model (DRT), offers high expressiveness well beyond traditional periodic task models. Still, the associated feasibility problem on preemptive uniprocessors remains tractable. It is an open

Martin Stigge; Pontus Ekberg; Nan Guan; Wang Yi

2011-01-01

79

Product evaluation based in the association between intuition and tasks.  

PubMed

This paper explores the importance of researching the intuitiveness in the product use. It approaches the intuitiveness influence for users that already had a visual experience of the product. Finally, it is suggested the use of a table that relates the tasks performed while using a product, the features for an intuitive use and the performance metric "task success". PMID:22316865

Almeida e Silva, Caio Márcio; Okimoto, Maria Lúcia L R; Albertazzi, Deise; Calixto, Cyntia; Costa, Humberto

2012-01-01

80

Effects of Noise Exposure on Performance of a Simulated Radar Task.  

National Technical Information Service (NTIS)

The present study examined the effect of noise (radar control room sounds, 80 dBA) on the ability to sustain attention to a complex monitoring task. The visual display was designed to resemble that of a highly automated air traffic control radar system co...

R. I. Thackray R. M. Touchstone

1979-01-01

81

Agricultural Production: Task Analysis for Livestock Production. Competency-Based Education.  

ERIC Educational Resources Information Center

This task analysis guide is intended to help teachers and administrators develop instructional materials and implement competency-based education in the agricultural production program. Section 1 contains a validated task inventory for the livestock production portion of agricultural production IV and V. Tasks are divided into six duty areas:…

Henrico County Public Schools, Glen Allen, VA. Virginia Vocational Curriculum Center.

82

The Effects of Input-Based Tasks on the Development of Learners' Pragmatic Proficiency  

ERIC Educational Resources Information Center

The present study evaluates the relative effectiveness of three types of input-based approaches for teaching English polite request forms to sixty Japanese learners of English: (a) structured input tasks with explicit information; (b) problem-solving tasks; and (c) structured input tasks without explicit information. Treatment group performance…

Takimoto, Masahiro

2009-01-01

83

Importance effects on performance in event?based prospective memory tasks  

Microsoft Academic Search

In the present study we manipulated the importance of performing two event?based prospective memory tasks. In Experiment 1, the event?based task was assumed to rely on relatively automatic processes, whereas in Experiment 2 the event?based task was assumed to rely on a more demanding monitoring process. In contrast to the first experiment, the second experiment showed that importance had a

Matthias Kliegel; Mike Martin; Mark McDaniel; Gilles Einstein

2004-01-01

84

Personal exposure assessment to particulate metals using a paper-based analytical device  

NASA Astrophysics Data System (ADS)

The development of a paper-based analytical device (PAD) for assessing personal exposure to particulate metals will be presented. Human exposure to metal aerosols, such as those that occur in the mining, construction, and manufacturing industries, has a significant impact on the health of our workforce, costing an estimated $10B in the U.S and causing approximately 425,000 premature deaths world-wide each year. Occupational exposure to particulate metals affects millions of individuals in manufacturing, construction (welding, cutting, blasting), and transportation (combustion, utility maintenance, and repair services) industries. Despite these effects, individual workers are rarely assessed for their exposure to particulate metals, due mainly to the high cost and effort associated with personal exposure measurement. Current exposure assessment methods for particulate metals call for an 8-hour filter sample, after which time, the filter sample is transported to a laboratory and analyzed by inductively-coupled plasma (ICP). The time from sample collection to reporting is typically weeks and costs several hundred dollars per sample. To exacerbate the issue, method detection limits suffer because of sample dilution during digestion. The lack of sensitivity hampers task-based exposure assessment, for which sampling times may be tens of minutes. To address these problems, and as a first step towards using microfluidics for personal exposure assessment, we have developed PADs for measurement of Pb, Cd, Cr, Fe, Ni, and Cu in aerosolized particulate matter.

Cate, David; Volckens, John; Henry, Charles

2013-03-01

85

The Evaluation and Quantification of Respirable Coal and Silica Dust Concentrations: A Task-based Approach.  

PubMed

Silicosis and coal worker's pneumoconiosis are serious occupational respiratory diseases associated with the coal mining industry and the inhalation of respirable dusts containing crystalline silica. The purpose of this study (funded by the Mine Health and Safety Council of South Africa) was to evaluate the individual contributions of underground coal mining tasks to the respirable dust and respirable silica dust concentrations in an underground section by sampling the respirable dust concentrations at the intake and return of each task. The identified tasks were continuous miner (CM) cutting, construction, transfer of coal, tipping, and roof bolting. The respirable dust-generating hierarchy of the tasks from highest to lowest was: transfer of coal > CM right cutting > CM left cutting > CM face cutting > construction > roof bolting > tipping; and for respirable silica dust: CM left cutting > construction > transfer of coal > CM right cutting. Personal exposure levels were determined by sampling the exposures of workers performing tasks in the section. Respirable dust concentrations and low concentrations of respirable silica dust were found at the intake air side of the section, indicating that air entering the section is already contaminated. The hierarchy for personal respirable dust exposures was as follows, from highest to lowest: CM operator > cable handler > miner > roof bolt operator > shuttle car operator, and for respirable silica dust: shuttle car operator > CM operator > cable handler > roof bolt operator > miner. Dust control methods to lower exposures should include revision of the position of workers with regard to the task performed, positioning of the tasks with regard to the CM cutting, and proper use of the line curtains to direct ventilation appropriately. The correct use of respiratory protection should also be encouraged. PMID:24380473

Grové, T; Van Dyk, T; Franken, A; Du Plessis, J

2014-06-01

86

Gradient field-based task assignment in an AGV transportation system  

Microsoft Academic Search

ABSTRACT Assigning tasks to agents is complex, especially in highly dynamic environments. Typical protocol-based approaches for task assignment such as Contract Net have proven their value, however, they may,not be flexible enough,to cope with continuously changing circumstances. In this paper we study and validate the feasibility of a field-based approach,for task assignment,in a complex,problem domain. In particular, we apply the

Danny Weyns; Nelis Boucké; Tom Holvoet

2006-01-01

87

Center Based Task Allocation in Multi Agent Systems  

Microsoft Academic Search

There are some problems in RoboCupRescue Simulation system such as task allocation, path planning, inter-agent communication and so on. We use some algorithms to solve these problems. This paper describes the design and implementation of Rayan RoboCup Rescue Simulation team and the algorithms used to solve problems relevant to this system.

M. E. Shiri; A. Behzadian Nejad; E. Pasbani Houshyarifar

88

Attitudes toward Task-Based Language Learning: A Study of College Korean Language Learners  

ERIC Educational Resources Information Center

This study explores second/foreign language (L2) learners' attitudes toward task-based language learning (TBLL) and how these attitudes relate to selected learner variables, namely anxiety, integrated motivation, instrumental motivation, and self-efficacy. Ninety-one college students of Korean as a foreign language, who received task-based

Pyun, Danielle Ooyoung

2013-01-01

89

The measurement and facilitation of cooperative task performance. [reactions of humans to stress exposure  

NASA Technical Reports Server (NTRS)

Experiments were conducted to determine under what conditions jaw clenching will occur in humans as a response to stress exposure. The method for measuring reactions to stress involves a series of electrical recordings of the masseter and temporalis muscles. A high fixed-ratio response requirement in the first series of experiments shows that jaw clenching in humans occurs in situations analogous to those which produce biting in infrahuman subjects. In the second series, reduction in the amounts of money recieved by subjects is shown to cause increases in the jaw clench response and other negative effect motor behaviors. The third series demonstrates that perception of more favorable conditions existing for another person can increase anger and hostility in the subject.

Hutchinson, R. R.

1975-01-01

90

TADEUS: seamless development of task-based and user-oriented interfaces  

Microsoft Academic Search

Task-based and user-oriented user interfaces utilize knowledge about user tasks and user characteristics to the utmost extent. They support users throughout their work flows, and must be constructed by a development process that avoids loss of application context and involves user feedback, from requirements specification to code generation. The concepts behind the task analysis\\/design\\/end users systems (TADEUS) approach to enable

Christian Stary

2000-01-01

91

A Guide for the Management of Special Education Programs. 2.0 Procedures for Use of the Task Base Composite.  

ERIC Educational Resources Information Center

The second volume of an eight-part series on a task-based management system for special education programs offers detailed procedures for use of the task base composite (TBC), a listing of approximately 700 task descriptions classified under 20 functions and divided according to whether the task is necessary to support a program or directly…

Santa Cruz County Superintendent of Schools, CA.

92

CNTRICS Final Task Selection: Social Cognitive and Affective Neuroscience-Based Measures  

PubMed Central

This article describes the results and recommendations of the third Cognitive Neuroscience Treatment Research to Improve Cognition in Schizophrenia meeting related to measuring treatment effects on social and affective processing. At the first meeting, it was recommended that measurement development focuses on the construct of emotion identification and responding. Five Tasks were nominated as candidate measures for this construct via the premeeting web-based survey. Two of the 5 tasks were recommended for immediate translation, the Penn Emotion Recognition Task and the Facial Affect Recognition and the Effects of Situational Context, which provides a measure of emotion identification and responding as well as a related, higher level construct, context-based modulation of emotional responding. This article summarizes the criteria-based, consensus building analysis of each nominated task that led to these 2 paradigms being recommended as priority tasks for development as measures of treatment effects on negative symptoms in schizophrenia.

Carter, Cameron S.; Barch, Deanna M.; Gur, Ruben; Gur, Raquel; Pinkham, Amy; Ochsner, Kevin

2009-01-01

93

Measurement and Evidence of Computer-Based Task Switching and Multitasking by "Net Generation" Students  

ERIC Educational Resources Information Center

Logs of on-campus computer and Internet usage were used to conduct a study of computer-based task switching and multitasking by undergraduate medical students. A detailed analysis of over 6000 individual sessions revealed that while a majority of students engaged in both task switching and multitasking behaviours, they did so less frequently than…

Judd, Terry; Kennedy, Gregor

2011-01-01

94

Cognitive Style as a Factor Affecting Task-Based Reading Comprehension Test Scores  

ERIC Educational Resources Information Center

For purposes of the present study, it was hypothesized that field (in)dependence would introduce systematic variance into Iranian EFL learners' overall and task-specific performance on task-based reading comprehension tests. 1743 freshman, sophomore, junior, and senior students all majoring in English at different Iranian universities and colleges…

Salmani-Nodoushan, Mohammad Ali

2005-01-01

95

"Storyline": A Task-Based Approach for the Young Learner Classroom  

ERIC Educational Resources Information Center

The Storyline approach is little known in language teaching contexts although it has much in common with task-based education. Learners play the parts of characters in an unfolding narrative, collaborating on tasks in small groups, a method which combines the use of language skills with practical work. A word often used by participants in a…

Ahlquist, Sharon

2013-01-01

96

Frontal Lobe Involvement in a Task of Time-Based Prospective Memory  

ERIC Educational Resources Information Center

Time-based prospective memory (PM) has been found to be negatively affected by aging, possibly as a result of declining frontal lobe (FL) function. Despite a clear retrospective component to PM tasks, the medial temporal lobes (MTL) are thought to play only a secondary role in successful task completion. The present study investigated the role of…

McFarland, Craig P.; Glisky, Elizabeth L.

2009-01-01

97

Task Listing for Introduction to Health Occupations. Competency-Based Education.  

ERIC Educational Resources Information Center

This task listing is designed to be used in combination with the "Health Occupations Education Service Area Resource" in order to implement competency-based education in health occupations programs in Virginia. The task listing contains four major sections: (1) content/concept areas; (2) program and course description; (3) content outline; and (4)…

Henrico County Public Schools, Glen Allen, VA. Virginia Vocational Curriculum Center.

98

Task-based MT Evaluation: Tackling Software, Experimental Design, & Statistical Models  

Microsoft Academic Search

Even with recent, renewed attention to MT evaluation—due in part to n-gram-based metrics (Papineni et al., 2001; Doddington, 2002) and the extensive, online catalogue of MT metrics on the ISLE project (Hovy et al., 2001, 2003), few reports involving task-based metrics have surfaced. This paper presents our work on three parts of task- based MT evaluation: (i) software to track

Calandra Tate; Sooyon Lee; Clare R. Voss

99

A task-based comparison of two reconstruction algorithms for digital breast tomosynthesis  

NASA Astrophysics Data System (ADS)

Digital breast tomosynthesis (DBT) generates 3-D reconstructions of the breast by taking X-Ray projections at various angles around the breast. DBT improves cancer detection as it minimizes tissue overlap that is present in traditional 2-D mammography. In this work, two methods of reconstruction, filtered backprojection (FBP) and the Newton-Raphson iterative reconstruction were used to create 3-D reconstructions from phantom images acquired on a breast tomosynthesis system. The task based image analysis method was used to compare the performance of each reconstruction technique. The task simulated a 10mm lesion within the breast containing iodine concentrations between 0.0mg/ml and 8.6mg/ml. The TTF was calculated using the reconstruction of an edge phantom, and the NPS was measured with a structured breast phantom (CIRS 020) over different exposure levels. The detectability index d' was calculated to assess image quality of the reconstructed phantom images. Image quality was assessed for both conventional, single energy and dual energy subtracted reconstructions. Dose allocation between the high and low energy scans was also examined. Over the full range of dose allocations, the iterative reconstruction yielded a higher detectability index than the FBP for single energy reconstructions. For dual energy subtraction, detectability index was maximized when most of the dose was allocated to the high energy image. With that dose allocation, the performance trend for reconstruction algorithms reversed; FBP performed better than the corresponding iterative reconstruction. However, FBP performance varied very erratically with changing dose allocation. Therefore, iterative reconstruction is preferred for both imaging modalities despite underperforming dual energy FBP, as it provides stable results.

Mahadevan, Ravi; Ikejimba, Lynda C.; Lin, Yuan; Samei, Ehsan; Lo, Joseph Y.

2014-03-01

100

Exposure-Based Cat Modeling, Available data, Advantages, & Limitations  

NASA Astrophysics Data System (ADS)

This paper discusses the advantages and disadvantages of exposure data for cat-modeling and considers concepts of scale as well as the completeness of data and data scoring using field/model examples. Catastrophe modeling based on exposure data has been considered the panacea for insurance-related cat modeling since the late 1980's. Reasons for this include: • The ability to extend risk modeling to consider data beyond historical losses, • Usability across many relevant scales, • Flexibility in addressing complex structures and policy conditions, and • Ability to assess dependence of risk results on exposure-attributes and exposure-modifiers, such as lines of business, occupancy types, and mitigation features, at any given scale. In order to calculate related risk, monetary exposure is correlated to vulnerabilities that have been calibrated with historical results, plausibility concepts, and/or physical modeling. While exposure based modeling is widely adopted, we also need to be aware of its limitations which include: • Boundaries in our understanding of the distribution of exposure, • Spatial interdependence of exposure patterns and the time-dependence of exposure, • Incomplete availability of loss information to calibrate relevant exposure attributes/structure with related vulnerabilities and losses, • The scale-dependence of vulnerability, • Potential for missing or incomplete communication of assumptions made during model calibration, • Inefficiencies in the aggregation or disaggregation of vulnerabilities, and • Factors which can influence losses other than exposure, vulnerability, and hazard. Although we might assume that the higher the resolution the better, regional model calibration is often limited to lower than street level resolution with higher resolution being achieved by disaggregating results using topographic/roughness features with often loosely constrained and/or varying effects on losses. This suggests that higher accuracy might actually be achieved at resolutions lower than the maximum available in current exposure cat models and as yet undefined. Further, dominance of a few models, associated consensus results, and preeminence of exposure concepts can lead to the subjective interpretation of inaccuracies in exposure distribution/attribution that can result in biased model results. More extreme solutions have resulted in input exposure data being calibrated with model results in order to achieve pre-determined and self-fulfilling outcomes. These outcomes could be avoided by allowing realistic uncertainty ranges rather than restricting interpretation of risk results to misleading "consensus nutshell" numbers. The paper concludes by considering new concepts in the use of exposure models and describes potential scenarios for the future use of input data in cat models.

Michel, Gero; Hosoe, Taro; Schrah, Mike; Saito, Keiko

2010-05-01

101

Model-based estimation and prediction of task-imposed mental workload  

NASA Technical Reports Server (NTRS)

Mental workload has been an area of intensive research for better than a decade. One specific area of interest in aircrew related workload research is concerned with the development of quantitative indices of workload in aircraft piloting tasks. This paper presents a model-based approach for quantifying mental workload in operational terms. The suggested modeling framework is based on an interpreted Petri net characterization of a task in which 'places' are equated to specific task-related activities and 'transitions' are viewed as internal or external forcing events. It is shown that within this framework quantitative assessments can be made of both cumulative and instantaneous workload associated with the performance of a task and its individual component subtasks. It is suggested that insights gained from analyzing task-specific workload within this modeling paradigm can suggest plausible explanations for reconciling discrepancies between subjectively elicited workload estimates and behavioral/performance measures.

Madni, A. M.; Lyman, J.

1983-01-01

102

Lunar base surface mission operations. Lunar Base Systems Study (LBSS) task 4.1  

NASA Technical Reports Server (NTRS)

The purpose was to perform an analysis of the surface operations associated with a human-tended lunar base. Specifically, the study defined surface elements and developed mission manifests for a selected base scenario, determined the nature of surface operations associated with this scenario, generated a preliminary crew extravehicular and intravehicular activity (EVA/IVA) time resource schedule for conducting the missions, and proposed concepts for utilizing remotely operated equipment to perform repetitious or hazardous surface tasks. The operations analysis was performed on a 6 year period of human-tended lunar base operation prior to permanent occupancy. The baseline scenario was derived from a modified version of the civil needs database (CNDB) scenario. This scenario emphasizes achievement of a limited set of science and exploration objectives while emplacing the minimum habitability elements required for a permanent base.

1987-01-01

103

Energy-Based Approach for Task Scheduling under Time and Resource Constraints.  

National Technical Information Service (NTIS)

Independent tasks under time and resource constraints are scheduled. The method and techniques developed refer to the so called 'constraints-based analysis' in scheduling problems. This analysis aims to characterize admissible schedules in order to provid...

P. Lopez

1991-01-01

104

Market-based task allocation and control for distributed logistics  

Microsoft Academic Search

This position paper outlines possible research directions related to market-based methods, especially as they apply to logistic settings. First, we describe some of the characteristics of the logistics domain. Next, we identify and discuss some fundamental research problems which we consider open and relevant for this domain, from the agent-based electronic markets perspective.

Valentin Robu

2005-01-01

105

Internalizing versus externalizing control: Different ways to perform a time-based prospective memory task.  

PubMed

Time-based prospective memory (PM) refers to performing intended actions at a future time. Participants with time-based PM tasks can be slower to perform ongoing tasks (costs) than participants without PM tasks because internal control is required to maintain the PM intention or to make prospective-timing estimates. However, external control can be gained, and internal control minimized, by checking clocks or by using PM reminders. We present 3 experiments that examined how individuals externalize and internalize control of time-based PM tasks. The control condition performed a lexical decision task only, whereas the PM conditions were additionally required to make a time-based PM response after 11 min. We manipulated whether participants received a reminder, and whether clock checking was discouraged. In Experiments 1 and 3, no cost was found under standard clock check conditions. In contrast, when participants were discouraged from clock checking (Experiments 2 and 3), significant costs were found, accompanied by a decrease in clock checking. PM reminders prompted participants to check the clock, and improved PM accuracy if those reminders were expected. However, there was no evidence that participants could localize the internal or external control of the PM task to after the presentation of an expected reminder (Experiment 3). We conclude that much of the need for internal control can be transferred to the external world by performing a well-practiced task such as clock checking, which reminds participants of the PM task and reduces the internal control required to maintain the intention to perform the PM task. (PsycINFO Database Record (c) 2014 APA, all rights reserved). PMID:24548325

Huang, Tracy; Loft, Shayne; Humphreys, Michael S

2014-07-01

106

Task Based Automatic Examination System for Sequenced Test  

Microsoft Academic Search

Computer greatly influences our educational environment. Over the last years, automatic computer examination systems have been widely used for computer-based tests. But these systems are based on traditional question-answer examination style which is not fit for the sequenced test. The sequenced test should consider the context of the examinee, e.g. the order of questions or the permissions of the examinee,

Song Luo; Jianbin Hu; Zhong Chen

2009-01-01

107

Uranium internal exposure evaluation based on urine assay data  

SciTech Connect

The difficulties in assessing internal exposures to uranium from urine assay data are described. A simplified application of the ICRP-30 and ICRP Lung Model concepts to the estimation of uranium intake is presented. A discussion follows on the development of a computer code utilizing the ICRP-30-based uranium elimination model with the existing urine assay information. The calculated uranium exposures from 1949 through 1983 are discussed. 13 references, 1 table.

Lawrence, J.N.P.

1984-09-01

108

Realization of the Table Tennis Task Based on Virtual Targets  

Microsoft Academic Search

This paper describes how a table tennis robot with a fiat paddle coordinates its movement in order to achieve efficient strokes for any given ball. We pro- pose a method of generating stroke movement based on virtual targets that means the point at which the ball should be struck and the paddle velocity just be- fore hitting the ball. These

Fumio Miyazaki; Takeuchi Michiya Matsushima; Michiya Matsushima; Takamichi Kusano; Takaaki Hashimoto

2002-01-01

109

Behavioral Features for Different Haptic-based Biometric Tasks  

Microsoft Academic Search

The science of haptics or haptic technology has received enormous attention in the last decade for multiple applications. A new promising example is the use of haptic-based systems for individual authentication. A user 's behavioral characteristics captured while interacting with a virtual scene are significantly more difficult to compromise than traditional means (i.e. login ID and passwords). Moreover, another advantage

R. Iglesias; M. Orozco; J. J. Valdes; A. El Saddik

2007-01-01

110

Task-Based Lessons: The Central Focus of a Mathematics Content Course for Future Elementary Teachers  

Microsoft Academic Search

A task-based lesson serves as the organizing principle for a university mathematics content course for future elementary teachers.\\u000a The course, which provides the first semester of a year-long sequence, covers the arithmetic of numbers. The daily classroom\\u000a activities follow a Japanese-style lesson plan and use tasks developed through a didactical phenomenological analysis. A situated\\u000a learning perspective frames an understanding of

Anne R. Teppo

111

Reusing OWL-S to model knowledge intensive tasks performed by Knowledge Based Systems  

Microsoft Academic Search

This paper gives an overview of the work done to develop a task ontology based on the task templates provided by CommonKADS. It discusses how modeling of KBS is done in the CommonKADS and also gives a brief overview of OWL-S which an upper-level ontology for web services. Constructs of OWL-S ontology have been compared with constructs proposed by CommonKADS

Baby A. Gobin

2012-01-01

112

A task-oriented modular and agent-based collaborative design mechanism for distributed product development  

NASA Astrophysics Data System (ADS)

The rapid expansion of enterprises makes product collaborative design (PCD) a critical issue under the distributed heterogeneous environment, but as the collaborative task of large-scale network becomes more complicated, neither unified task decomposition and allocation methodology nor Agent-based network management platform can satisfy the increasing demands. In this paper, to meet requirements of PCD for distributed product development, a collaborative design mechanism based on the thought of modularity and the Agent technology is presented. First, the top-down 4-tier process model based on task-oriented modular and Agent is constructed for PCD after analyzing the mapping relationships between requirements and functions in the collaborative design. Second, on basis of sub-task decomposition for PCD based on a mixed method, the mathematic model of task-oriented modular based on multi-objective optimization is established to maximize the module cohesion degree and minimize the module coupling degree, while considering the module executable degree as a restriction. The mathematic model is optimized and simulated by the modified PSO, and the decomposed modules are obtained. Finally, the Agent structure model for collaborative design is put forward, and the optimism matching Agents are selected by using similarity algorithm to implement different task-modules by the integrated reasoning and decision-making mechanism with the behavioral model of collaborative design Agents. With the results of experimental studies for automobile collaborative design, the feasibility and efficiency of this methodology of task-oriented modular and Agent-based collaborative design in the distributed heterogeneous environment are verified. On this basis, an integrative automobile collaborative R&D platform is developed. This research provides an effective platform for automobile manufacturing enterprises to achieve PCD, and helps to promote product numeralization collaborative R&D and management development.

Liu, Jinfei; Chen, Ming; Wang, Lei; Wu, Qidi

2014-05-01

113

Risk-based indicators of Canadians' exposures to environmental carcinogens  

PubMed Central

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

2013-01-01

114

Co-Constructional Task Analysis: Moving beyond Adult-Based Models to Assess Young Children's Task Performance  

ERIC Educational Resources Information Center

The assessment of young children's thinking competence in task performances has typically followed the novice-to-expert regimen involving models of strategies that adults use when engaged in cognitive tasks such as problem-solving and decision-making. Socio-constructivists argue for a balanced pedagogical approach between the adult and child…

Lee, Scott Weng Fai

2013-01-01

115

Cerebellar potentiation and learning a whisker-based object localization task with a time response window.  

PubMed

Whisker-based object localization requires activation and plasticity of somatosensory and motor cortex. These parts of the cerebral cortex receive strong projections from the cerebellum via the thalamus, but it is unclear whether and to what extent cerebellar processing may contribute to such a sensorimotor task. Here, we subjected knock-out mice, which suffer from impaired intrinsic plasticity in their Purkinje cells and long-term potentiation at their parallel fiber-to-Purkinje cell synapses (L7-PP2B), to an object localization task with a time response window (RW). Water-deprived animals had to learn to localize an object with their whiskers, and based upon this location they were trained to lick within a particular period ("go" trial) or refrain from licking ("no-go" trial). L7-PP2B mice were not ataxic and showed proper basic motor performance during whisking and licking, but were severely impaired in learning this task compared with wild-type littermates. Significantly fewer L7-PP2B mice were able to learn the task at long RWs. Those L7-PP2B mice that eventually learned the task made unstable progress, were significantly slower in learning, and showed deficiencies in temporal tuning. These differences became greater as the RW became narrower. Trained wild-type mice, but not L7-PP2B mice, showed a net increase in simple spikes and complex spikes of their Purkinje cells during the task. We conclude that cerebellar processing, and potentiation in particular, can contribute to learning a whisker-based object localization task when timing is relevant. This study points toward a relevant role of cerebellum-cerebrum interaction in a sophisticated cognitive task requiring strict temporal processing. PMID:24478374

Rahmati, Negah; Owens, Cullen B; Bosman, Laurens W J; Spanke, Jochen K; Lindeman, Sander; Gong, Wei; Potters, Jan-Willem; Romano, Vincenzo; Voges, Kai; Moscato, Letizia; Koekkoek, Sebastiaan K E; Negrello, Mario; De Zeeuw, Chris I

2014-01-29

116

The relationship between maximal lifting capacity and maximum acceptable lift in strength-based soldiering tasks.  

PubMed

Psychophysical assessments, such as the maximum acceptable lift, have been used to establish worker capability and set safe load limits for manual handling tasks in occupational settings. However, in military settings, in which task demand is set and capable workers must be selected, subjective measurements are inadequate, and maximal capacity testing must be used to assess lifting capability. The aim of this study was to establish and compare the relationship between maximal lifting capacity and a self-determined tolerable lifting limit, maximum acceptable lift, across a range of military-relevant lifting tasks. Seventy male soldiers (age 23.7 ± 6.1 years) from the Australian Army performed 7 strength-based lifting tasks to determine their maximum lifting capacity and maximum acceptable lift. Comparisons were performed to identify maximum acceptable lift relative to maximum lifting capacity for each individual task. Linear regression was used to identify the relationship across all tasks when the data were pooled. Strong correlations existed between all 7 lifting tasks (rrange = 0.87-0.96, p < 0.05). No differences were found in maximum acceptable lift relative to maximum lifting capacity across all tasks (p = 0.46). When data were pooled, maximum acceptable lift was equal to 84 ± 8% of the maximum lifting capacity. This study is the first to illustrate the strong and consistent relationship between maximum lifting capacity and maximum acceptable lift for multiple single lifting tasks. The relationship developed between these indices may be used to help assess self-selected manual handling capability through occupationally relevant maximal performance tests. PMID:22643137

Savage, Robert J; Best, Stuart A; Carstairs, Greg L; Ham, Daniel J

2012-07-01

117

Collaborative Scaffolding in Online Task-Based Voice Interactions between Advanced Learners  

ERIC Educational Resources Information Center

This paper reports some of the findings of a distinctive innovative use of audio-conferencing involving a population (campus-based advanced learners) and a type of application (task-based language learning) that have received little attention to date: the use of Wimba Voice Tools to provide additional opportunities for spoken interactions between…

Kenning, Marie-Madeleine

2010-01-01

118

Cumulative lead exposure in community-dwelling adults and fine motor function: comparing standard and novel tasks in the VA Normative Aging Study  

PubMed Central

Background and Aims Lead exposure in children and occupationally-exposed adults has been associated with reduced visuomotor and fine motor function. However, associations in environmentally-exposed adults remain relatively unexplored. To address this, we examined the association between cumulative lead exposure—as measured by lead in bone—and performance on the Grooved Pegboard (GP) manual dexterity task, as well as on handwriting tasks using a novel assessment approach, among men in the VA Normative Aging Study (NAS). Methods GP testing was done with 362 NAS participants, and handwriting assessment with 328, who also had tibia and patella lead measurements made with K-X-Ray Fluorescence (KXRF). GP scores were time (sec) to complete the task with the dominant hand. The handwriting assessment approach assessed the production of signature and cursive lowercase l and m letter samples. Signature and lm task scores reflect consistency in repeated trials. We used linear regression to estimate associations and 95% confidence intervals (CI) with adjustment for age, smoking, education, income and computer experience. A backward elimination algorithm was used in the subset with both GP and handwriting assessment to identify variables predictive of each outcome. Results The mean (SD) participant age was 69.1 (7.2) years; mean patella and tibia concentrations were 25.0 (20.7) ?g/g and 19.2 (14.6) ?g/g, respectively. In multivariable-adjusted analyses, GP performance was associated with tibia (? per 15 ?g/g bone = 4.66, 95% CI: 1.73, 7.58, p=0.002) and patella (? per 20 ?g/g = 3.93, 95% CI: 1.11, 6.76, p = 0.006). In multivariable adjusted models of handwriting production, only the lm-pattern task showed a significant association with tibia (? per 15 ?g/g bone = 1.27, 95% CI: 0.24, 2.29, p = 0.015), such that lm pattern production was more stable with increasing lead exposure. GP and handwriting scores were differentially sensitive to education, smoking, computer experience, financial stability, income and alcohol consumption. Conclusions Long-term cumulative environmental lead exposure was associated with deficits in GP performance, but not handwriting production. Higher lead appeared to be associated with greater consistency on the lm task. Lead sensitivity differences could suggest that lead affects neural processing speed rather than motor function per se, or could result from distinct brain areas involved in the execution of different motor tasks.

Grashow, Rachel; Spiro, Avron; Taylor, Kathryn M.; Newton, Kimberly; Shrairman, Ruth; Landau, Alexander; Sparrow, David; Hu, Howard; Weisskopf, Marc

2013-01-01

119

The preliminary Long Duration Exposure Facility (LDEF) materials data base  

NASA Technical Reports Server (NTRS)

A preliminary Long Duration Exposure Facility (LDEF) Materials Data Base was developed by the LDEF Materials Special Investigation Group (MSIG). The LDEF Materials Data Base is envisioned to eventually contain the wide variety and vast quantity of materials data generated for LDEF. The data is searchable by optical, thermal, and mechanical properties, exposure parameters (such as atomic oxygen flux), and author(s) or principal investigator(s). The LDEF Materials Data Base was incorporated into the Materials and Processes Technical Information System (MAPTIS). MAPTIS is a collection of materials data which was computerized and is available to engineers, designers, and researchers in the aerospace community involved in the design and development of spacecraft and related hardware. This paper describes the LDEF Materials Data Base and includes step-by-step example searches using the data base. Information on how to become an authorized user of the system is included.

Funk, Joan G.; Strickland, John W.; Davis, John M.

1992-01-01

120

Biomonitoring Hexamethylene Diisocyanate (HDI) Exposure Based on Serum Levels of HDI-Specific IgG  

PubMed Central

Objectives: Isocyanate chemicals essential for polyurethane production are widely used industrially, and are increasingly found in consumer products. Asthma and other adverse health effects of isocyanates are well-documented and exposure surveillance is crucial to disease prevention. Hexamethylene diisocyanate (HDI)-specific serum immunoglobulin G (IgG) was evaluated as an exposure biomarker among workers at a US Air Force Air Logistics Center, which includes a large aircraft maintenance facility. Methods: HDI-specific IgG (HDI-IgG) titers in serum samples (n = 74) were measured using an enzyme-linked immunosorbent assay based upon the biuret form of HDI conjugated to human albumin. Information on personal protective equipment (PPE), work location/tasks, smoking, asthma history, basic demographics, and HDI skin exposure was obtained through questionnaire. Results: HDI-specific serum IgG levels were elevated in n = 17 (23%) of the workers studied. The prevalence and/or end-titer of the HDI-IgG was significantly (P < 0.05) associated with specific job titles, self-reported skin exposure, night-shift work, and respirator use, but not atopy, asthma, or other demographic information. The highest titers were localized to specific worksites (C-130 painting), while other worksites (generator painting) had no or few workers with detectable HDI-IgG. Conclusions: HDI-specific immune responses (IgG) provide a practical biomarker to aid in exposure surveillance and ongoing industrial hygiene efforts. The strategy may supplement current air sampling approaches, which do not assess exposures via skin, or variability in PPE use or effectiveness. The approach may also be applicable to evaluating isocyanate exposures in other settings, and may extend to other chemical allergens.

Wisnewski, Adam V.; Stowe, Meredith H.; Nerlinger, Abby; Opare-addo, Paul; Decamp, David; Kleinsmith, Christopher R.; Redlich, Carrie A.

2012-01-01

121

Exposure of baboons to combined 60 Hz electric and magnetic fields does not produce work stoppage or affect operant performance on a match-to-sample task  

Microsoft Academic Search

The authors examined the effects of combined 60 Hz electric and magnetic field (EMF) exposure on performance of delayed match-to-sample (MTS) procedure involving the flash rate of a light as the stimulus. Six baboons (Papio cynocephalus) fully acquired the task; four others functioned accurately only when cued. All ten subjects were assigned to EMF-exposed or sham-exposed groups of five and

John L. Orr; Walter R. Rogers; Houston D. Smith

1995-01-01

122

A Decision Analytic Approach to Exposure-Based Chemical Prioritization  

PubMed Central

The manufacture of novel synthetic chemicals has increased in volume and variety, but often the environmental and health risks are not fully understood in terms of toxicity and, in particular, exposure. While efforts to assess risks have generally been effective when sufficient data are available, the hazard and exposure data necessary to assess risks adequately are unavailable for the vast majority of chemicals in commerce. The US Environmental Protection Agency has initiated the ExpoCast Program to develop tools for rapid chemical evaluation based on potential for exposure. In this context, a model is presented in which chemicals are evaluated based on inherent chemical properties and behaviorally-based usage characteristics over the chemical’s life cycle. These criteria are assessed and integrated within a decision analytic framework, facilitating rapid assessment and prioritization for future targeted testing and systems modeling. A case study outlines the prioritization process using 51 chemicals. The results show a preliminary relative ranking of chemicals based on exposure potential. The strength of this approach is the ability to integrate relevant statistical and mechanistic data with expert judgment, allowing for an initial tier assessment that can further inform targeted testing and risk management strategies.

Mitchell, Jade; Pabon, Nicolas; Collier, Zachary A.; Egeghy, Peter P.; Cohen-Hubal, Elaine; Linkov, Igor; Vallero, Daniel A.

2013-01-01

123

Sensory-guided motor tasks benefit from mental training based on serial prediction.  

PubMed

Mental strategies have been suggested to constitute a promising approach to improve motor abilities in both healthy subjects and patients. This behavioural effect has been shown to be associated with changes of neural activity in premotor areas, not only during movement execution, but also while performing motor imagery or action observation. However, how well such mental tasks are performed is often difficult to assess, especially in patients. We here used a novel mental training paradigm based on the serial prediction task (SPT) in order to activate premotor circuits in the absence of a motor task. We then tested whether this intervention improves motor-related performance such as sensorimotor transformation. Two groups of healthy young participants underwent a single-blinded five-day cognitive training schedule and were tested in four different motor tests on the day before and after training. One group (N=22) received the SPT-training and the other one (N=21) received a control training based on a serial match-to-sample task. The results revealed significant improvements of the SPT-group in a sensorimotor timing task, i.e. synchronization of finger tapping to a visually presented rhythm, as well as improved visuomotor coordination in a sensory-guided pointing task compared to the group that received the control training. However, mental training did not show transfer effects on motor abilities in healthy subjects beyond the trained modalities as evident by non-significant changes in the Jebsen-Taylor handfunctiontest. In summary, the data suggest that mental training based on the serial prediction task effectively engages sensorimotor circuits and thereby improves motor behaviour. PMID:24321273

Binder, Ellen; Hagelweide, Klara; Wang, Ling E; Kornysheva, Katja; Grefkes, Christian; Fink, Gereon R; Schubotz, Ricarda I

2014-02-01

124

Measuring pilot workload in a moving-base simulator. I Asynchronous secondary choice-reaction task  

NASA Technical Reports Server (NTRS)

The de facto method for measuring airplane pilot workload is based upon subjective ratings. While researchers agree that such subjective data should be bolstered by using objective behavioral measures, results to date have been mixed. No clear objective technique has surfaced as the metric of choice. It is believed that this difficulty is in part due to neglect of theoretical work in psychology that predicts some of the difficulties that are inherent in a futile search for 'the one and only' best secondary task to measure workload. An initial study that used both subjective ratings and an asynchronous choice-reaction secondary task was conducted to determine if such a secondary task could indeed meet the methodological constraints imposed by current theories of attention. Two variants of a flight scenario were combined with two levels of the secondary task. Appropriate single-task control conditions were also included. Results give grounds for cautious optimism but indicate that future research should use synchronous secondary tasks where possible.

Kantowitz, B. H.; Hart, S. G.; Bortolussi, M. R.

1983-01-01

125

TESS-based dose-response using pediatric clonidine exposures  

SciTech Connect

Objective: The toxic and lethal doses of clonidine in children are unclear. This study was designed to determine whether data from the American Association of Poison Control Centers Toxic Exposure Surveillance System (TESS) could be utilized to determine a dose-response relationship for pediatric clonidine exposure. Methods: 3458 single-substance clonidine exposures in children <6 years of age reported to TESS from January 2000 through December 2003 were examined. Dose ingested, age, and medical outcome were available for 1550 cases. Respiratory arrest cases (n = 8) were classified as the most severe of the medical outcome categories (Arrest, Major, Moderate, Mild, and No effect). Exposures reported as a 'taste or lick' (n = 51) were included as a dose of 1/10 of the dosage form involved. Dose ranged from 0.4 to 1980 (median 13) {mu}g/kg. Weight was imputed based on a quadratic estimate of weight for age. Dose certainty was coded as exact (26% of cases) or not exact (74%). Medical outcome (response) was examined via logistic regression using SAS JMP (release 5.1). Results: The logistic model describing medical outcome (P < 0.0001) included Log dose/kg (P 0.0000) and Certainty (P = 0.045). Conclusion: TESS data can provide the basis for a statistically sound description of dose-response for pediatric clonidine poisoning exposures.

Benson, Blaine E. [New Mexico Poison and Drug Information Center and University of New Mexico College of Pharmacy, Albuquerque, NM 87131 (United States)]. E-mail: jebenson@salud.unm.edu; Spyker, Daniel A. [Alexza Pharmaceuticals, Palo Alto, CA 94303 (United States); Troutman, William G. [University of New Mexico College of Pharmacy, Albuquerque, NM 87131 (United States); Watson, William A. [American Association of Poison Control Centers, Washington, DC 20016 (United States)]. E-mail: http://www.aapcc.org/

2006-06-01

126

Automated Classification of fMRI Data Employing Trial-based Imagery Tasks  

PubMed Central

Automated interpretation and classification of functional MRI (fMRI) data is an emerging research field that enables the characterization of underlying cognitive processes with minimal human intervention. In this work, we present a method for the automated classification of human thoughts reflected on a trial-based paradigm using fMRI with a significantly shortened data acquisition time (less than one minute). Based on our preliminary experience with various cognitive imagery tasks, six characteristic thoughts were chosen as target tasks for the present work: right hand motor imagery, left hand motor imagery, right foot motor imagery, mental calculation, internal speech/word generation, and visual imagery. These six tasks were performed by five healthy volunteers and functional images were obtained using a T2*-weighted echo planar imaging (EPI) sequence. Feature vectors from activation maps, necessary for the classification of neural activity, were automatically extracted from the regions that were consistently and exclusively activated for a given task during the training process. Extracted feature vectors were classified using the support vector machine (SVM) algorithm. Parameter optimization, using a k-fold cross-validation scheme, allowed the successful recognition of the six different categories of administered thought tasks with an accuracy of 74.5% (mean) ± 14.3% (standard deviation) across all five subjects. Our proposed study for the automated classification of fMRI data may be utilized in further investigations to monitor/identify human thought processes and their potential link to hardware/computer control.

Lee, Jong-Hwan; Marzelli, Matthew; Jolesz, Ferenc A.; Yoo, Seung-Schik

2009-01-01

127

Brain Computer Interface based robotic rehabilitation with online modification of task speed.  

PubMed

We present a systematic approach that enables online modification/adaptation of robot assisted rehabilitation exercises by continuously monitoring intention levels of patients utilizing an electroencephalogram (EEG) based Brain-Computer Interface (BCI). In particular, we use Linear Discriminant Analysis (LDA) to classify event-related synchronization (ERS) and desynchronization (ERD) patterns associated with motor imagery; however, instead of providing a binary classification output, we utilize posterior probabilities extracted from LDA classifier as the continuous-valued outputs to control a rehabilitation robot. Passive velocity field control (PVFC) is used as the underlying robot controller to map instantaneous levels of motor imagery during the movement to the speed of contour following tasks. In other words, PVFC changes the speed of contour following tasks with respect to intention levels of motor imagery. PVFC also allows decoupling of the task and the speed of the task from each other, and ensures coupled stability of the overall robot patient system. The proposed framework is implemented on AssistOn-Mobile--a series elastic actuator based on a holonomic mobile platform, and feasibility studies with healthy volunteers have been conducted test effectiveness of the proposed approach. Giving patients online control over the speed of the task, the proposed approach ensures active involvement of patients throughout exercise routines and has the potential to increase the efficacy of robot assisted therapies. PMID:24187241

Sarac, Mine; Koyas, Ela; Erdogan, Ahmetcan; Cetin, Mujdat; Patoglu, Volkan

2013-06-01

128

Automated classification of fMRI data employing trial-based imagery tasks.  

PubMed

Automated interpretation and classification of functional MRI (fMRI) data is an emerging research field that enables the characterization of underlying cognitive processes with minimal human intervention. In this work, we present a method for the automated classification of human thoughts reflected on a trial-based paradigm using fMRI with a significantly shortened data acquisition time (less than one minute). Based on our preliminary experience with various cognitive imagery tasks, six characteristic thoughts were chosen as target tasks for the present work: right-hand motor imagery, left-hand motor imagery, right foot motor imagery, mental calculation, internal speech/word generation, and visual imagery. These six tasks were performed by five healthy volunteers and functional images were obtained using a T(*)(2)-weighted echo planar imaging (EPI) sequence. Feature vectors from activation maps, necessary for the classification of neural activity, were automatically extracted from the regions that were consistently and exclusively activated for a given task during the training process. Extracted feature vectors were classified using the support vector machine (SVM) algorithm. Parameter optimization, using a k-fold cross validation scheme, allowed the successful recognition of the six different categories of administered thought tasks with an accuracy of 74.5% (mean)+/-14.3% (standard deviation) across all five subjects. Our proposed study for the automated classification of fMRI data may be utilized in further investigations to monitor/identify human thought processes and their potential link to hardware/computer control. PMID:19233711

Lee, Jong-Hwan; Marzelli, Matthew; Jolesz, Ferenc A; Yoo, Seung-Schik

2009-06-01

129

Task-Based Authorization Controls (TBAC): A Family of Models for Active and Enterprise-Oriented Autorization Management  

Microsoft Academic Search

In this paper, we develop a new paradigm for access control and authorization management, called task-based authorization controls (TBAC). TBAC models access controls from a task-oriented perspective than the traditional subject-object one. Access mediation now involves authorizations at various points during the completion of tasks in accordance with some application logic. By taking a task- oriented view of access control

Roshan K. Thomas; Ravi S. Sandhu

1997-01-01

130

Modelling of occupational respirable crystalline silica exposure for quantitative exposure assessment in community-based case-control studies.  

PubMed

We describe an empirical model for exposure to respirable crystalline silica (RCS) to create a quantitative job-exposure matrix (JEM) for community-based studies. Personal measurements of exposure to RCS from Europe and Canada were obtained for exposure modelling. A mixed-effects model was elaborated, with region/country and job titles as random effect terms. The fixed effect terms included year of measurement, measurement strategy (representative or worst-case), sampling duration (minutes) and a priori exposure intensity rating for each job from an independently developed JEM (none, low, high). 23,640 personal RCS exposure measurements, covering a time period from 1976 to 2009, were available for modelling. The model indicated an overall downward time trend in RCS exposure levels of -6% per year. Exposure levels were higher in the UK and Canada, and lower in Northern Europe and Germany. Worst-case sampling was associated with higher reported exposure levels and an increase in sampling duration was associated with lower reported exposure levels. Highest predicted RCS exposure levels in the reference year (1998) were for chimney bricklayers (geometric mean 0.11 mg m(-3)), monument carvers and other stone cutters and carvers (0.10 mg m(-3)). The resulting model enables us to predict time-, job-, and region/country-specific exposure levels of RCS. These predictions will be used in the SYNERGY study, an ongoing pooled multinational community-based case-control study on lung cancer. PMID:22001827

Peters, Susan; Vermeulen, Roel; Portengen, Lützen; Olsson, Ann; Kendzia, Benjamin; Vincent, Raymond; Savary, Barbara; Lavoué, Jérôme; Cavallo, Domenico; Cattaneo, Andrea; Mirabelli, Dario; Plato, Nils; Fevotte, Joelle; Pesch, Beate; Brüning, Thomas; Straif, Kurt; Kromhout, Hans

2011-11-01

131

The Research of a New Workflow Model with Step-Task Layers Based on XML Documents  

Microsoft Academic Search

The research of workflow technology has been an active area for many years. Modeling of workflow is arguably the most important issue. In this paper, a workflow model with two layers named as S-T workflow model is created which is based on directed cyclic graph. We separate control node and task node in two layers. Step layer describes process control

Xing Jianping; Zhao Lin; Meng Lingguo

2006-01-01

132

Addressing the Intercultural via Task-Based Language Teaching: Possibility or Problem?  

ERIC Educational Resources Information Center

A frequent weakness of communicative approaches to foreign language teaching is a neglect of the intercultural dimension. Cultural knowledge is often treated as an addendum which focuses on learning facts about the target country. This article explores whether task-based language teaching (TBLT) can successfully address the intercultural…

East, Martin

2012-01-01

133

Using Virtual Reality for Task-Based Exercises in Teaching Non-Traditional Students of German  

ERIC Educational Resources Information Center

Using task-based exercises that required web searches and online activities, this course introduced non-traditional students to the sights and sounds of the German culture and language and simultaneously to computer technology. Through partner work that required negotiation of the net as well as of the language, these adult beginning German…

Libbon, Stephanie

2004-01-01

134

Samples of Students' Responses from the Grade 6 Science Performance-based Assessment Tasks, June 1994.  

ERIC Educational Resources Information Center

The performance-based assessment was developed to assess students' higher order thinking skills in real-life problem-solving situations in Alberta, Canada. These tasks assess aspects of science that cannot be measured easily by regular paper and pencil tests. The purpose of this document is to provide teachers, administrators, students, and…

Alberta Dept. of Education, Edmonton. Student Evaluation Branch.

135

Samples of Students' Responses from the Grade 9 Science Performance-Based Assessment Tasks, June 1993.  

ERIC Educational Resources Information Center

The purpose of this document is to provide teachers, administrators, students, and parents with samples of students' performances that exemplify standards in relation to the 1993 Grade 9 Science Performance-Based Assessment Tasks for the province of Alberta, Canada. A sample of 698 randomly selected students from 31 schools did the…

Alberta Dept. of Education, Edmonton. Student Evaluation Branch.

136

Negative Feedback in Adult NS-NNS Task-Based Conversation.  

ERIC Educational Resources Information Center

This study examined the availability and utility of negative feedback provided in the context of task-based adult conversations between native speakers and non-native speakers. Subjects were 10 dyads each consisting of a native English speaker and a college-level student of English as a Second Language. Analysis of conversational interactions…

Izumi, Shinichi

137

Visual-based Sensory Motor Learning During Dynamic Balance Tasks Viewed in a Virtual Environment  

Microsoft Academic Search

In this research, we applied a transformation to the normal trajectory used to move and track a visual target in a virtual environment, in order to evaluate adaptation to a visual-based sensory motor transformation. The ability to recalibrate internal to external spatial reference frames is important when changing the relationship between the self and the environment. The virtual task was

Aimee L. Betker; Zahra Moussavi; T. Szturm

2007-01-01

138

A Task-Based Production Environment for Intelligent Learning\\/Teaching Systems: The \\  

Microsoft Academic Search

After many studies, experiments, and assessments on the design and development of intelligent learning\\/teaching systems, we are now offering a production environment for these systems and shells. This environment is based on high abstraction level primitives: the 'NGE' kernel. Elaborated in a cognitive approach, these primitives have been defined on the notion of task (generic, cognitive, operating), not only to

C. Marie-françoise Canut; Murielle Eloi

1996-01-01

139

Hidden Markov Model and Auction-Based Formulations of Sensor Coordination Mechanisms in Dynamic Task Environments  

Microsoft Academic Search

In this paper, multistage auction-based intelligence, surveillance, and reconnaissance (ISR) sensor coordination mech- anisms are investigated in the context of dynamic and uncertain mission environments such as those faced by expeditionary strike groups. Each attribute of the mission task is modeled using a hidden Markov model (HMM) with controllable emission matri- ces, corresponding to each ISR asset package (subset of

Woosun An; Xu Han; Krishna R. Pattipati; David L. Kleinman; William G. Kemple

2011-01-01

140

The Impact of "Role Play" on Fostering EFL Learners' Speaking Ability: A Task-Based Approach  

ERIC Educational Resources Information Center

Marking as one dramatic turnover in language teaching, task-based language teaching (TBLT) has proved itself beneficial and effective in bringing about real situations of language use to take place and in satisfying communicative needs of learners while the former methods were unable to meet actual demands of learners to communicate in the target…

Aliakbari, Mohammad; Jamalvandi, Behroz

2010-01-01

141

Task-Based Oral Computer-Mediated Communication and L2 Vocabulary Acquisition  

ERIC Educational Resources Information Center

The present study adds to the computer-mediated communication (CMC) literature by exploring oral learner-to-learner interaction using Skype, a free and widely used Internet software program. In particular, this task-based study has a two-fold goal. Firstly, it explores possible differences between two modes of oral CMC (audio and video) and…

Yanguas, Inigo

2012-01-01

142

Task-based and stable telenanomanipulation in a nanoscale virtual environment  

Microsoft Academic Search

In a haptic interface system with a nanoscale virtual environment (NVE) using an atomic force microscope, not only is stability important, but task-based performance (or fidelity) is crucial. In this paper, we introduce a nanoscale virtual coupling (NSVC) concept and explicitly derive the relationship between performance, stability, and scaling factors of velocity (or position) and force. An available scaling factor

Sung-Gaun Kimand; Metin Sitti

2006-01-01

143

Evaluating Gaze-Based Interface Tools to Facilitate Point-and-Select Tasks with Small Targets  

ERIC Educational Resources Information Center

Gaze interaction affords hands-free control of computers. Pointing to and selecting small targets using gaze alone is difficult because of the limited accuracy of gaze pointing. This is the first experimental comparison of gaze-based interface tools for small-target (e.g. less than 12 x 12 pixels) point-and-select tasks. We conducted two…

Skovsgaard, Henrik; Mateo, Julio C.; Hansen, John Paulin

2011-01-01

144

Task-Based Learning and Teaching in China: Secondary School Teachers' Beliefs and Practices  

ERIC Educational Resources Information Center

While much has been written about task-based language teaching (TBLT), research examining teachers' understandings of what TBLT means remains limited. This article explores the understandings of TBLT of three Chinese secondary school teachers of English and the implementation of TBLT in their lessons. Narrative accounts were constructed for…

Zheng, Xinmin; Borg, Simon

2014-01-01

145

ESL Students' Interaction in Second Life: Task-Based Synchronous Computer-Mediated Communication  

ERIC Educational Resources Information Center

The purpose of the present study was to explore ESL students' interactions in task-based synchronous computer-mediated communication (SCMC) in Second Life, a virtual environment by which users can interact through representational figures. I investigated Low-Intermediate and High-Intermediate ESL students' interaction patterns before, during, and…

Jee, Min Jung

2010-01-01

146

Using Task Based Writing Instruction to Provide Differentiated Instruction for English Language Learners  

ERIC Educational Resources Information Center

The purpose of this study was to investigate the impact of task based writing instruction (TBwI) on English language acquisition and differentiated instruction for minority language students during the Independent Work Time instructional component of the Open Court Reading program. One teacher and 10 third grade students (8-9 years old)…

Bantis, Alexandros Merkouris

2008-01-01

147

Student Use of the Mother Tongue in the Task-Based Classroom  

ERIC Educational Resources Information Center

This article draws on an interview study with teachers and teacher educators on the topic of the feasibility of task-based teaching for implementation in schools. It focuses on a single theme from the study: student use of the mother tongue. A number of dimensions are addressed: the extent of classroom interaction in English in the context under…

Carless, David

2008-01-01

148

Gender Differences and Effects of Co-Operation in a Computer-Based Language Task.  

ERIC Educational Resources Information Center

Single- or mixed-gender pairs of elementary children were told either to work cooperatively on a computer-based language task or be assessed individually. Performance measures indicated a disadvantage for mixed pairs, improved performance for cooperative pairs. Girls tended to cooperate regardless of being told to or not; mixed pairs cooperated…

Underwood, Geoffrey; And Others

1994-01-01

149

Taking Teacher Education to Task: Exploring the Role of Teacher Education in Promoting the Utilization of Task-Based Language Teaching  

ERIC Educational Resources Information Center

Despite its theoretical appeal and research-based support, task-based language teaching (TBLT) continues to have a somewhat limited influence on actual second language teaching practices in many contexts. This study considers the relationship between teacher education and the broader use of TBLT. It investigates the effects of a…

Ogilvie, Greg; Dunn, William

2010-01-01

150

Quadrotor UAV Control for Vision-based Moving Target Tracking Task  

NASA Astrophysics Data System (ADS)

The problem of stand-off tracking of a moving target using a quadrotor unmanned aerial vehicle (UAV) based on vision-sensing is investigated. A PID (Proportional-Integral-Derivative) controller is implemented for attitude stabilization of the quadrotor. An LQG-based (Linear-Quadratic-Gaussian) control law is designed and implemented for position control of the quadrotor for a moving target tracking task. A novel vision-based estimation algorithm is developed, enabling estimation of quadrotor's position, altitude and yaw relative to the target based on limited information about the target. Two image processing algorithms are implemented and compared for the task of feature detection and feature tracking in a series of images. Image processing algorithms are integrated with quadrotor control and experiments are performed to validate proposed control and estimation approaches.

Bohdanov, Denys

151

Individual differences and task-based user interface evaluation: a case study of pending tasks in email  

Microsoft Academic Search

This paper addresses issues raised by the ever-expanding role of email as a multi-faceted application that combines communication, collaboration, and task management. Individual differences analysis was used to contrast two email user interfaces in terms of their demands on users. The results of this analysis were then interpreted in terms of their implications for designing more inclusive interfaces that meet

Jacek Gwizdka; Mark H. Chignell

2004-01-01

152

A Sensor-based Approach for Physical Interaction Based on Hand Grasp and Task Frames  

Microsoft Academic Search

Abstract— Robotic manipulation,of everyday,objects and execution of household chores is one of the most desired (and challenging) skills for future service robots. Most of the current research in robotic grasping is limited to pick-and-place tasks, without paying attention to the whole range of different tasks needed in human environments, such as opening doors, inter- acting with furniture, household electrical appliances,

Mario Prats; Pedro J. Sanz; Angel P. Del Pobil

153

Cognitive Load and Task Condition in Event and Time-Based Prospective Memory: An Experimental Investigation  

Microsoft Academic Search

Prospective memory is memory for the realization of delayed intention. Researchers distinguish 2 kinds of prospective memory: event- and time-based (G. O. Einstein & M. A. McDaniel, 1990). Taking that distinction into account, the present authors explored participants' comparative performance under event- and time-based tasks. In an experimental study of 80 participants, the authors investigated the roles of cognitive load

Azizuddin Khan; Narendra K. Sharma; Shikha Dixit

2008-01-01

154

A situated reasoning architecture for space-based repair and replace tasks  

NASA Technical Reports Server (NTRS)

Space-based robots need low level control for collision detection and avoidance, short-term load management, fine-grained motion, and other physical tasks. In addition, higher level control is required to focus strategic decision making as missions are assigned and carried out. Reasoning and control must be responsive to ongoing changes in the environment. Research aimed at bridging the gap between high level artificial intelligence (AI) planning techniques and task-level robot programming for telerobotic systems is described. Situated reasoning is incorporated into AI and Robotics systems in order to coordinate a robot's activity within its environment. An integrated system under development in a component maintenance domain is described. It is geared towards replacing worn and/or failed Orbital Replacement Units (ORUs) designed for use aboard NASA's Space Station Freedom based on the collection of components available at a given time. High level control reasons in component space in order to maximize the number operational component-cells over time, while the task-level controls sensors and effectors, detects collisions, and carries out pick and place tasks in physical space. Situated reasoning is used throughout the system to cope with component failures, imperfect information, and unexpected events.

Bloom, Ben; Mcgrath, Debra; Sanborn, Jim

1989-01-01

155

A latent discriminative model-based approach for classification of imaginary motor tasks from EEG data  

NASA Astrophysics Data System (ADS)

We consider the problem of classification of imaginary motor tasks from electroencephalography (EEG) data for brain-computer interfaces (BCIs) and propose a new approach based on hidden conditional random fields (HCRFs). HCRFs are discriminative graphical models that are attractive for this problem because they (1) exploit the temporal structure of EEG; (2) include latent variables that can be used to model different brain states in the signal; and (3) involve learned statistical models matched to the classification task, avoiding some of the limitations of generative models. Our approach involves spatial filtering of the EEG signals and estimation of power spectra based on autoregressive modeling of temporal segments of the EEG signals. Given this time-frequency representation, we select certain frequency bands that are known to be associated with execution of motor tasks. These selected features constitute the data that are fed to the HCRF, parameters of which are learned from training data. Inference algorithms on the HCRFs are used for the classification of motor tasks. We experimentally compare this approach to the best performing methods in BCI competition IV as well as a number of more recent methods and observe that our proposed method yields better classification accuracy.

Delgado Saa, Jaime F.; Çetin, Müjdat

2012-04-01

156

Hydrogen Embrittlement of Metal Fasteners Due to Phosphoric Acid Containment System (PACS) Exposure. Volume 5 - Delivery Order 4, Task 2.  

National Technical Information Service (NTIS)

The objective of this study was to determine if metal fasteners are susceptible to hydrogen embrittlement due to exposure to a phosphoric acid containment system (PACS) surface preparation. A PACS is used to anodize aluminum surfaces in preparation for ad...

W. B. Pinnell

1999-01-01

157

Frontal lobe involvement in a task of time-based prospective memory  

PubMed Central

Time-based prospective memory (PM) has been found to be negatively affected by aging, possibly as a result of declining frontal lobe (FL) function. Despite a clear retrospective component to PM tasks, the medial temporal lobes (MTL) are thought to play only a secondary role in successful task completion. The present study investigated the role of the FLs and MTLs in time-based PM, as well as their involvement in clock monitoring, plan generation, and time estimation, each of which may play a role in the execution of time-based PM tasks. Based upon their scores on composite measures of FL and MTL function, 32 older adults were divided into four groups, and were then tested on a time-based laboratory PM task. Overall age effects were also assessed and each of the four groups was compared to a group of 32 younger adults. High-frontal functioning participants demonstrated better prospective memory than low-frontal functioning participants, and were not distinguishable from younger adults. Older adults with high-MTL scores performed significantly better than those with low-MTL scores, but only if they were also high in FL function. FL function, but not MTL function, predicted patterns of clock monitoring, quality of plans generated to assist in time-based PM performance, and the accuracy of time estimation. Again, on each of these measures the performance of the high-frontal group was equivalent to that of the younger adults. The results of this study suggest that it is not aging per se that disrupts PM performance, but it is instead primarily the diminished frontal function seen in a subset of older adults.

McFarland, Craig P.; Glisky, Elizabeth L.

2009-01-01

158

Nanotechnology-Based Electrochemical Sensors for Biomonitoring Chemical Exposures  

PubMed Central

The coupling of dosimetry measurements and modeling represents a promising strategy for deciphering the relationship between chemical exposure and disease outcome. To support the development and implementation of biological monitoring programs, quantitative technologies for measuring xenobiotic exposure are needed. The development of portable nanotechnology-based electrochemical sensors has the potential to meet the needs for low cost, rapid, high-throughput and ultrasensitive detectors for biomonitoring an array of chemical markers. Highly selective electrochemical (EC) sensors capable of pM sensitivity, high-throughput and low sample requirements (<50uL) are discussed. These portable analytical systems have many advantages over currently available technologies, thus potentially representing the next-generation of biomonitoring analyzers. This manuscript highlights research focused on the development of field-deployable analytical instruments based on EC detection. Background information and a general overview of EC detection methods and integrated use of nanomaterials in the development of these sensors are provided. New developments in EC sensors using various types of screen-printed electrodes, integrated nanomaterials, and immunoassays are presented. Recent applications of EC sensors for assessing exposure to pesticides or detecting biomarkers of disease are highlighted to demonstrate the ability to monitor chemical metabolites, enzyme activity, or protein biomarkers of disease. In addition, future considerations and opportunities for advancing the use of EC platforms for dosimetric studies are discussed.

Barry, Richard C.; Lin, Yuehe; Wang, Jun; Liu, Guodong; Timchalk, Charles A.

2009-01-01

159

Exposure-driven risk assessment: applying exposure-based waiving of toxicity tests under REACH.  

PubMed

The REACH Regulation 1907/2006/EC aims to improve knowledge of the potential risks to humans and the environment of the large number of chemicals produced and used in the EU. The testing requirements are likely to trigger numerous toxicological studies, potentially involving millions of experimental animals, despite the professed goal of REACH to reduce vertebrate testing. It may be necessary therefore to shift emphasis away from animal studies towards more pragmatic strategies, reserving animal tests for the substances of greatest concern. One approach is to waive certain tests based on levels of exposure to the substance. This review explores application of 'Exposure-Based Waiving' (EBW) of toxicity studies, with a particular focus on inhalation where possible, considering the potential qualitative and quantitative supporting arguments that might be made, including the use of thresholds of toxicological concern. Incorporating EBW into intelligent testing strategies for substance registration could advance the goals of REACH and the 3Rs (reduction, replacement and refinement of animals in research) by reducing the usage of animals in toxicity tests, whilst maintaining appropriate protection of human health and the environment. However greater regulatory evaluation, acceptance and guidance are required for EBW to achieve its full impact. PMID:21458516

Rowbotham, Anna L; Gibson, Rosemary M

2011-08-01

160

Moving from Virtual Reality Exposure-Based Therapy to Augmented Reality Exposure-Based Therapy: A Review  

PubMed Central

This paper reviews the move from virtual reality exposure-based therapy to augmented reality exposure-based therapy (ARET). Unlike virtual reality (VR), which entails a complete virtual environment (VE), augmented reality (AR) limits itself to producing certain virtual elements to then merge them into the view of the physical world. Although, the general public may only have become aware of AR in the last few years, AR type applications have been around since beginning of the twentieth century. Since, then, technological developments have enabled an ever increasing level of seamless integration of virtual and physical elements into one view. Like VR, AR allows the exposure to stimuli which, due to various reasons, may not be suitable for real-life scenarios. As such, AR has proven itself to be a medium through which individuals suffering from specific phobia can be exposed “safely” to the object(s) of their fear, without the costs associated with programing complete VEs. Thus, ARET can offer an efficacious alternative to some less advantageous exposure-based therapies. Above and beyond presenting what has been accomplished in ARET, this paper covers some less well-known aspects of the history of AR, raises some ARET related issues, and proposes potential avenues to be followed. These include the type of measures to be used to qualify the user’s experience in an augmented reality environment, the exclusion of certain AR-type functionalities from the definition of AR, as well as the potential use of ARET to treat non-small animal phobias, such as social phobia.

Baus, Oliver; Bouchard, Stephane

2014-01-01

161

Moving from virtual reality exposure-based therapy to augmented reality exposure-based therapy: a review.  

PubMed

This paper reviews the move from virtual reality exposure-based therapy to augmented reality exposure-based therapy (ARET). Unlike virtual reality (VR), which entails a complete virtual environment (VE), augmented reality (AR) limits itself to producing certain virtual elements to then merge them into the view of the physical world. Although, the general public may only have become aware of AR in the last few years, AR type applications have been around since beginning of the twentieth century. Since, then, technological developments have enabled an ever increasing level of seamless integration of virtual and physical elements into one view. Like VR, AR allows the exposure to stimuli which, due to various reasons, may not be suitable for real-life scenarios. As such, AR has proven itself to be a medium through which individuals suffering from specific phobia can be exposed "safely" to the object(s) of their fear, without the costs associated with programing complete VEs. Thus, ARET can offer an efficacious alternative to some less advantageous exposure-based therapies. Above and beyond presenting what has been accomplished in ARET, this paper covers some less well-known aspects of the history of AR, raises some ARET related issues, and proposes potential avenues to be followed. These include the type of measures to be used to qualify the user's experience in an augmented reality environment, the exclusion of certain AR-type functionalities from the definition of AR, as well as the potential use of ARET to treat non-small animal phobias, such as social phobia. PMID:24624073

Baus, Oliver; Bouchard, Stéphane

2014-01-01

162

Development of an Airborne Fiber Size Specific Job-Exposure Matrix (JEM) Based on Transmission Electron microscopy (TEM) Data, Charleston, South Carolina Asbestos Textile Cohort.  

National Technical Information Service (NTIS)

This report is submitted in fulfillment of requirements of NIOSH Purchase Order No. 0000158283 dated September 17, 2001. The methods used for analyses of the TEM data and development of the Job-Exposure Matrix (JEM) are based on the Task 1 report (Protoco...

2005-01-01

163

Capturing Dynamic Patterns of Task-Based Functional Connectivity with EEG  

PubMed Central

A new approach to trace the dynamic patterns of task-based functional connectivity, by combining signal segmentation, dynamic time warping (DTW), and Quality Threshold (QT) clustering techniques, is presented. Electroencephalography (EEG) signals of 5 healthy subjects were recorded as they performed an auditory oddball and a visual modified oddball tasks. To capture the dynamic patterns of functional connectivity during the execution of each task, EEG signals are segmented into durations that correspond to the temporal windows of previously well-studied event-related potentials (ERPs). For each temporal window, DTW is employed to measure the functional similarities among channels. Unlike commonly used temporal similarity measures, such as cross correlation, DTW compares time series by taking into consideration that their alignment properties may vary in time. QT clustering analysis is then used to automatically identify the functionally connected regions in each temporal window. For each task, the proposed approach was able to establish a unique sequence of dynamic pattern (observed in all 5 subjects) for brain functional connectivity.

Karamzadeh, Nader; Medvedev, Andrei; Azari, Afrouz; Gandjbakhche, Amir; Najafizadeh, Laleh

2012-01-01

164

U.S. Department of Justice: Task Force for Faith-based & Community Initiatives  

NSDL National Science Digital Library

On January 29, 2001, President George W. Bush issued two executive orders related to faith-based and community organizations. The first established a base of operations within the White House for such initiatives, and the second established centers within various cabinet- level departments, including the Department of Justice (DOJ). As the latter's website notes, "The Task Force's purpose is to promote good works by neighbors, particularly in the areas of juvenile delinquency, prisoners and their families, victims of crime, domestic violence, and drug addiction/treatment/prevention." Visitors to the site can learn about funding opportunities administered by the DOJ and also read some of its publications, such as "Moving Beyond the Walls: Faith and Justice Partnerships Working for High Risk Youth". Interested parties may also want to look at the Task Force's FAQ section and sign up to receive email updates.

165

A swarm intelligence based memetic algorithm for task allocation in distributed systems  

NASA Astrophysics Data System (ADS)

This paper proposes a Swarm Intelligence based Memetic algorithm for Task Allocation and scheduling in distributed systems. The tasks scheduling in distributed systems is known as an NP-complete problem. Hence, many genetic algorithms have been proposed for searching optimal solutions from entire solution space. However, these existing approaches are going to scan the entire solution space without considering the techniques that can reduce the complexity of the optimization. Spending too much time for doing scheduling is considered the main shortcoming of these approaches. Therefore, in this paper memetic algorithm has been used to cope with this shortcoming. With regard to load balancing efficiently, Bee Colony Optimization (BCO) has been applied as local search in the proposed memetic algorithm. Extended experimental results demonstrated that the proposed method outperformed the existing GA-based method in terms of CPU utilization.

Sarvizadeh, Raheleh; Haghi Kashani, Mostafa

2011-12-01

166

A Project to Develop Performance Based Instruction through Task Analysis and In-Service Programs. Final Report.  

ERIC Educational Resources Information Center

The primary purposes of this project were to develop catalogs of performance objectives and performance guides based upon validated tasks performed by incumbent workers and to disseminate and diffuse catalogs through inservice activities. The five catalogs developed were based upon tasks performed in the occupations of banking clerk, diesel…

Ledoux, Clarence E.

167

Building Intelligent Agents for Web-Based Tasks: A Theory-Refinement Approach  

Microsoft Academic Search

We present and evaluate an infrastructure withwhich to rapidly and easily build intelligent softwareagents for Web-based tasks. Our design iscentered around two basic functions: ScoreThisLink and ScoreThisPage. If given highly accuratesuch functions, standard heuristic searchwould lead to efficient retrieval of useful information.Our approach allows users to tailor our system's behavior by providing approximate adviceabout the above functions. This advice is

Jude Shavlik; Tina Eliassi-rad

1998-01-01

168

Agent-Based Grid Load Balancing Using Performance-Driven Task Scheduling  

Microsoft Academic Search

Load balancing is a key concern when developing parallel and distributed computing applications. The emergence of computational grids extends this problem, where issues of cross-domain and large-scale scheduling must also be considered. In this work an agent-based grid management infrastructure is coupled with a performance-driven task scheduler that has been developed for local grid load balancing. Each grid scheduler utilises

Junwei Cao; Daniel P. Spooner; Stephen A. Jarvis; Subhash Saini; Graham R. Nudd

2003-01-01

169

Exposure of baboons to combined 60 Hz electric and magnetic fields does not produce work stoppage or affect operant performance on a match-to-sample task  

SciTech Connect

The authors examined the effects of combined 60 Hz electric and magnetic field (EMF) exposure on performance of delayed match-to-sample (MTS) procedure involving the flash rate of a light as the stimulus. Six baboons (Papio cynocephalus) fully acquired the task; four others functioned accurately only when cued. All ten subjects were assigned to EMF-exposed or sham-exposed groups of five and were used to test for a work-stoppage effect that was previously observed with initial exposure to electric fields (EF) of 30 or 60 kV/m. Here, the authors report the results of two experiments, each consisting of 6 week preexposure, exposure, and postexposure periods. They found no evidence of work stoppage with fields of 6 kV/m and 50 {micro}T (0.5 G) or with 30 kV/m and 100 {micro}T (1.0 G). In neither experiment was there evidence of an adverse effect of 60 Hz EMF exposure on MTS performance.

Orr, J.L.; Rogers, W.R.; Smith, H.D. [Southwest Research Inst., San Antonio, TX (United States). Dept. of Biosciences and Bioengineering

1995-12-31

170

Forecasting exposure to volcanic ash based on ash dispersion modeling  

NASA Astrophysics Data System (ADS)

A technique has been developed that uses Puff, a volcanic ash transport and dispersion (VATD) model, to forecast the relative exposure of aircraft and ground facilities to ash from a volcanic eruption. VATD models couple numerical weather prediction (NWP) data with physical descriptions of the initial eruptive plume, atmospheric dispersion, and settling of ash particles. Three distinct examples of variations on the technique are given using ERA-40 archived reanalysis NWP data. The Feb. 2000 NASA DC-8 event involving an eruption of Hekla volcano, Iceland is first used for analyzing a single flight. Results corroborate previous analyses that conclude the aircraft did encounter a diffuse cloud of volcanic origin, and indicate exposure within a factor of 10 compared to measurements made on the flight. The sensitivity of the technique to dispersion physics is demonstrated. The Feb. 2001 eruption of Mt. Cleveland, Alaska is used as a second example to demonstrate how this technique can be utilized to quickly assess the potential exposure of a multitude of aircraft during and soon after an event. Using flight tracking data from over 40,000 routes over three days, several flights that may have encountered low concentrations of ash were identified, and the exposure calculated. Relative changes in the quantity of exposure when the eruption duration is varied are discussed, and no clear trend is evident as the exposure increased for some flights and decreased for others. A third application of this technique is demonstrated by forecasting the near-surface airborne concentrations of ash that the cities of Yakima Washington, Boise Idaho, and Kelowna British Columbia might have experienced from an eruption of Mt. St. Helens anytime during the year 2000. Results indicate that proximity to the source does not accurately determine the potential hazard. Although an eruption did not occur during this time, the results serve as a demonstration of how existing cities or potential locations of research facilities or military bases can be assessed for susceptibility to hazardous and unhealthy concentrations of ash and other volcanic gases.

Peterson, Rorik A.; Dean, Ken G.

2008-03-01

171

Task Interference in Time-Based, Event-Based, and Dual Intention Prospective Memory Conditions  

ERIC Educational Resources Information Center

Forming the intention to complete an activity later is the standard definition of a prospective memory task. Recently, a debate has arisen concerning the degree to which near-term intentions usurp resources away from other ongoing activities. In four experiments the authors tested how much interference was caused by holding a variety of different…

Hicks, Jason L.; Marsh, Richard L.; Cook, Gabriel I.

2005-01-01

172

Task interference in time-based, event-based, and dual intention prospective memory conditions  

Microsoft Academic Search

Forming the intention to complete an activity later is the standard definition of a prospective memory task. Recently, a debate has arisen concerning the degree to which near-term intentions usurp resources away from other ongoing activities. In four experiments the authors tested how much interference was caused by holding a variety of different intentions. In all but one case, possessing

Jason L. Hicks; Richard L. Marsh; Gabriel I. Cook

2005-01-01

173

A computational knowledge-based model for emulating human performance in the Iowa Gambling Task.  

PubMed

A new computational knowledge-based model for emulating human performance in decision making tasks is proposed. This model is mainly based on the knowledge acquired through past experience, the knowledge extracted from the environment and the relationships between the concepts that represent these two kinds of knowledge. The proposed model divides the decision making process into two phases. The first phase lies in the estimation of the decision outcomes using a net of concepts. In the second phase, the proposed model uses a value function to score each possible alternative. The design of the model focuses on some psychological and neurophysiological evidence from current research. In order to validate the model, it is compared with other widely used models that implement different theories of decision making under risk and uncertainty. The model comparison is centered on a well defined task, the Iowa Gambling Task, used in several psychological experiments. The comparison applies an evaluation method based on the optimization of each model in order to emulate human performance individually starting both the participant and the model from the same environmentally available information. The results show that the performance of the proposed model is quantitatively better than the other compared models. Besides, using relevant concepts extracted from interviews with the participants increases the performance of the proposed model. PMID:22698633

Iglesias, A; Del Castillo, M D; Serrano, J I; Oliva, J

2012-09-01

174

Nanotechnology-Based Electrochemical Sensors for Biomonitoring Chemical Exposures  

SciTech Connect

This manuscript highlights research focused on the development of field-deployable analytical instruments based on EC detection. Background information and a general overview of EC detection methods and integrated use of nanomaterials in the development of these sensors are provided. New developments in EC sensors using various types of screen-printed electrodes, integrated nanomaterials, and immunoassays are discussed. Recent applications of EC sensors for assessing exposure to pesticides or detecting biomarkers of disease are highlighted to demonstrate the ability to monitor chemical metabolites, enzyme activity, or protein biomarkers of disease. In addition, future considerations and opportunities for advancing the use of EC platforms for dosimetric studies are covered.

Barry, Richard C.; Lin, Yuehe; Wang, Jun; Liu, Guodong; Timchalk, Charles

2009-01-01

175

Prenatal Exposure to Nicotine Impairs Performance of the 5Choice Serial Reaction Time Task in Adult Rats  

Microsoft Academic Search

Cigarette smoking is associated with a wide variety of adverse reproductive outcomes, including increased infant mortality and decreased birth weight. Prenatal exposure to tobacco smoke, of which nicotine is a major teratogenic component, has also been linked to the acceleration of the risk for different psychiatric disorders, including conduct disorder and attention deficit hyperactivity disorder (ADHD). Whether this increased risk

Tomasz Schneider; Nicholas Ilott; Giovana Brolese; Lisiane Bizarro; Philip J E Asherson; Ian P Stolerman

2011-01-01

176

Neonatal choline supplementation ameliorates the effects of prenatal alcohol exposure on a discrimination learning task in rats  

Microsoft Academic Search

Prenatal alcohol exposure can disrupt brain development and lead to a myriad of behavioral alterations, including motor coordination deficits, hyperactivity, and learning deficits. There remains a need, however, to identify treatments and interventions for reducing the severity of alcohol-related neurodevelopmental disorders. Some of the alcohol-induced deficits in learning may be related to alterations in cholinergic functioning. Interestingly, there is a

Jennifer D Thomas; Michael H La Fiette; Vincent R. E Quinn; Edward P Riley

2000-01-01

177

The Revised Observed Tasks of Daily Living: A Performance-Based Assessment of Everyday Problem Solving in Older Adults  

Microsoft Academic Search

The Revised Observed Tasks of Daily Living (OTDL-R), a performance-based test of everyday problem solving, was administered to a sample of community-dwelling older adults. The OTDLR included nine tasks, representing medication use, telephone use, and financial management. The OTDL-R had a desirable range of difficulty and satisfactory internal consistency and showed a relatively invariant pattern of relations between measured tasks

Manfred Diehl; Michael Marsiske; Ann L. Horgas; Adrienne Rosenberg; Jane S. Saczynski; Sherry L. Willis

2005-01-01

178

Development of vision-based autonomous robotic fish and its application in water-polo-attacking task  

Microsoft Academic Search

This paper presents the design and locomotion control of a vision-based autonomous robotic fish, and its application in water-polo-attacking task. Most of previous work on task strategies of autonomous robots is focused on the terrestrial robots and seldom deals with underwater applications. In fact, the tasks in underwater environment are more challenging than those in ground circumstances due to the

Wei Zhao; Yonghui Hu; Guangming Xie; Yingmin Jia

2008-01-01

179

Association of Silica Exposure with Anti-Neutrophil Cytoplasmic Autoantibody Small-Vessel Vasculitis: A Population-Based, Case-Control Study  

PubMed Central

Anti-neutrophil cytoplasmic autoantibodies (ANCA) are associated with a category of small-vessel vasculitis (SVV) with frequent glomerulonephritis. The goal of this study was to evaluate the association of lifetime silica exposure with development of ANCA-SVV, with particular attention to exposure dosage, intensity, and time since last exposure. A southeastern United States, population-based, case-control study was conducted. Case patients had ANCA-SVV with pauci-immune crescentic glomerulonephritis. Population-based control subjects were frequency-matched to case patients by age, gender, and state. Jobs were assessed in a telephone interview. Silica exposure scores incorporated exposure duration, intensity, and probability for each job and then were categorized as none, low/medium, or high lifetime exposure. Logistic regression models were used to estimate adjusted odds ratios (OR) and 95% confidence intervals (CI). Silica exposure was found in 78 (60%) of 129 case patients and in 49 (45%) of 109 control subjects. There was no increased risk for disease from low/medium exposure relative to no exposure (OR 1.0; 95% CI 0.4 to 2.2) but increased risk with high exposure (OR 1.9; 95% CI 1.0 to 3.5; P = 0.05). Crop harvesting was associated with elevated risk (OR 2.5; 95% CI 1.1 to 5.4; P = 0.03). However, both agricultural and traditional occupational sources contributed to the cumulative silica exposure scores; therefore, the overall effect could not be attributed to agricultural exposures alone. There was no evidence of decreasing by duration of time since last exposure. High lifetime silica exposure was associated with ANCA-SVV. Exposure to silica from specific farming tasks related to harvesting may be of particular importance in the southeastern United States. Interval of time since last exposure did not influence development of ANCA-SVV.

Hogan, Susan L.; Cooper, Glinda S.; Savitz, David A.; Nylander-French, Leena A.; Parks, Christine G.; Chin, Hyunsook; Jennette, Caroline E.; Lionaki, Sofia; Jennette, J. Charles; Falk, Ronald J.

2014-01-01

180

Evaluation of noise pollution level based upon community exposure and response data  

NASA Technical Reports Server (NTRS)

The results and procedures are reported from an evaluation of noise pollution level as a predictor of annoyance, based on aircraft noise exposure and community response data. The measures of noise exposure presented include composite noise rating, noise exposure forecast, noise and number index. A proposed measure as a universal noise exposure measure for noise pollution level (L sub NP) is discussed.

Edmiston, R. D.

1972-01-01

181

Fast Gaussian kernel learning for classification tasks based on specially structured global optimization.  

PubMed

For a practical pattern classification task solved by kernel methods, the computing time is mainly spent on kernel learning (or training). However, the current kernel learning approaches are based on local optimization techniques, and hard to have good time performances, especially for large datasets. Thus the existing algorithms cannot be easily extended to large-scale tasks. In this paper, we present a fast Gaussian kernel learning method by solving a specially structured global optimization (SSGO) problem. We optimize the Gaussian kernel function by using the formulated kernel target alignment criterion, which is a difference of increasing (d.i.) functions. Through using a power-transformation based convexification method, the objective criterion can be represented as a difference of convex (d.c.) functions with a fixed power-transformation parameter. And the objective programming problem can then be converted to a SSGO problem: globally minimizing a concave function over a convex set. The SSGO problem is classical and has good solvability. Thus, to find the global optimal solution efficiently, we can adopt the improved Hoffman's outer approximation method, which need not repeat the searching procedure with different starting points to locate the best local minimum. Also, the proposed method can be proven to converge to the global solution for any classification task. We evaluate the proposed method on twenty benchmark datasets, and compare it with four other Gaussian kernel learning methods. Experimental results show that the proposed method stably achieves both good time-efficiency performance and good classification performance. PMID:24929345

Zhong, Shangping; Chen, Tianshun; He, Fengying; Niu, Yuzhen

2014-09-01

182

Elementary Students' Learning of Materials Science Practices Through Instruction Based on Engineering Design Tasks  

NASA Astrophysics Data System (ADS)

Materials science, which entails the practices of selecting, testing, and characterizing materials, is an important discipline within the study of matter. This paper examines how third grade students' materials science performance changes over the course of instruction based on an engineering design challenge. We conducted a case study of nine students who participated in engineering design-based science instruction with the goal of constructing a stable, quiet, thermally comfortable model house. The learning outcome of materials science practices was assessed by clinical interviews conducted before and after the instruction, and the learning process was assessed by students' workbooks completed during the instruction. The interviews included two materials selection tasks for designing a sturdy stepstool and an insulated pet habitat. Results indicate that: (1) students significantly improved on both materials selection tasks, (2) their gains were significantly positively associated with the degree of completion of their workbooks, and (3) students who were highly engaged with the workbook's reflective record-keeping tasks showed the greatest improvement on the interviews. These findings suggest the important role workbooks can play in facilitating elementary students' learning of science through authentic activity such as engineering design.

Wendell, Kristen Bethke; Lee, Hee-Sun

2010-12-01

183

Exploring Fine-Grained Task-based Execution on Multi-GPU Systems  

SciTech Connect

Many-core Graphics Processing Units (GPUs) have been utilized as the computation engine in many scientific fields due to the high peak performance, cost effectiveness, and the availability of user friendly programming environments, e.g., NVIDIA CUDA. However, the conventional data parallel GPU programming paradigm cannot satisfactorily address issues such as load balancing and GPU resource utilization due to the irregular and unbalanced workload patterns exhibited in some applications. In this paper, we explore the design space of task-based solutions for multi-GPU systems. By employing finer-grained tasks than what is supported in the current CUDA, and allowing task sharing, our solutions enable dynamic load balancing. We evaluate our solutions with a Molecular Dynamics application with different atom distributions (from uniform distribution to highly non-uniform distribution). Experimental results obtained on a 4-GPU system show that, for non-uniform distributed systems, our solutions achieve excellent speedup, and significant performance improvement over other solutions based on the standard CUDA APIs.

Chen, Long; Villa, Oreste; Gao, Guang R.

2011-09-25

184

Extraversion differentiates between model-based and model-free strategies in a reinforcement learning task  

PubMed Central

Prominent computational models describe a neural mechanism for learning from reward prediction errors, and it has been suggested that variations in this mechanism are reflected in personality factors such as trait extraversion. However, although trait extraversion has been linked to improved reward learning, it is not yet known whether this relationship is selective for the particular computational strategy associated with error-driven learning, known as model-free reinforcement learning, vs. another strategy, model-based learning, which the brain is also known to employ. In the present study we test this relationship by examining whether humans' scores on an extraversion scale predict individual differences in the balance between model-based and model-free learning strategies in a sequentially structured decision task designed to distinguish between them. In previous studies with this task, participants have shown a combination of both types of learning, but with substantial individual variation in the balance between them. In the current study, extraversion predicted worse behavior across both sorts of learning. However, the hypothesis that extraverts would be selectively better at model-free reinforcement learning held up among a subset of the more engaged participants, and overall, higher task engagement was associated with a more selective pattern by which extraversion predicted better model-free learning. The findings indicate a relationship between a broad personality orientation and detailed computational learning mechanisms. Results like those in the present study suggest an intriguing and rich relationship between core neuro-computational mechanisms and broader life orientations and outcomes.

Skatova, Anya; Chan, Patricia A.; Daw, Nathaniel D.

2013-01-01

185

Autonomy, competence, and social relatedness in task interest within project-based education.  

PubMed

To prepare students for instructive collaboration, it is necessary to have insight into students' psychological needs and interest development. The framework of self-determination theory was used to conduct a field experiment involving 114 students in vocational education. These students followed a practical business course which required they work in small learning groups. During the course, students were asked to complete the Quality of Working in Groups Instrument, an online measure of how strong autonomy, competence, social relatedness, and task interest are fulfilled. SEM showed that students' psychological needs were jointly and uniquely related to task interest over time. The significance of this on-line test for the assessment of interest within project-based education is discussed. PMID:18175501

Minnaert, Alexander; Boekaerts, Monique; de Brabander, Cornelis

2007-10-01

186

Structural foundations of resting-state and task-based functional connectivity in the human brain  

PubMed Central

Magnetic resonance imaging enables the noninvasive mapping of both anatomical white matter connectivity and dynamic patterns of neural activity in the human brain. We examine the relationship between the structural properties of white matter streamlines (structural connectivity) and the functional properties of correlations in neural activity (functional connectivity) within 84 healthy human subjects both at rest and during the performance of attention- and memory-demanding tasks. We show that structural properties, including the length, number, and spatial location of white matter streamlines, are indicative of and can be inferred from the strength of resting-state and task-based functional correlations between brain regions. These results, which are both representative of the entire set of subjects and consistently observed within individual subjects, uncover robust links between structural and functional connectivity in the human brain.

Hermundstad, Ann M.; Bassett, Danielle S.; Brown, Kevin S.; Aminoff, Elissa M.; Clewett, David; Freeman, Scott; Frithsen, Amy; Johnson, Arianne; Tipper, Christine M.; Miller, Michael B.; Grafton, Scott T.; Carlson, Jean M.

2013-01-01

187

Feasibility of performing space surveillance tasks with a proposed space-based optical architecture  

NASA Astrophysics Data System (ADS)

Under ESA contract an industrial consortium including Aboa Space Research Oy (ASRO), the Astronomical Institute of the University of Bern (AIUB), and the Dutch National Aerospace Laboratory (NLR), proposed the observation concept, developed a suitable sensor architecture, and assessed the performance of a space-based optical (SBO) telescope in 2005. The goal of the SBO study was to analyse how the existing knowledge gap in the space debris population in the millimetre and centimetre regime may be closed by means of a passive optical instrument. The SBO instrument was requested to provide statistical information on the space debris population in terms of number of objects and size distribution. The SBO instrument was considered to be a cost-efficient with 20 cm aperture and 6° field-of-view and having flexible integration requirements. It should be possible to integrate the SBO instrument easily as a secondary payload on satellites launched into low-Earth orbits (LEO), or into geostationary orbit (GEO). Thus the selected mission concept only allowed for fix-mounted telescopes, and the pointing direction could be requested freely. Since 2007 ESA focuses space surveillance and tracking activities in the Space Situational Awareness (SSA) preparatory program. Ground-based radars and optical telescopes are studied for the build-up and maintenance of a catalogue of objects. In this paper we analyse how the proposed SBO architecture could contribute to the space surveillance tasks survey and tracking. We assume that the SBO instrumentation is placed into a circular sun-synchronous orbit at 800 km altitude. We discuss the observation conditions of objects at higher altitude, and select an orbit close to the terminator plane. A pointing of the sensor orthogonal to the orbital plane with optimal elevation slightly in positive direction (0° and +5°) is found optimal for accessing the entire GEO regime within one day, implying a very good coverage of controlled objects in GEO, too. Simulations using ESA’s Program for Radar and Optical Observation Forecasting (PROOF) in the version 2005 and a GEO reference population extracted from DISCOS revealed that the proposed pointing scenario provides low phase angles together with low angular velocities of the objects crossing the field-of-view. Radiometric simulations show that the optimal exposure time is 1-2 s, and that spherical objects in GEO with a diameter of below 1 m can be detected. The GEO population can be covered under proper illumination nearly completely, but seasonal drops of the coverage are possible. Subsequent observations of objects are on average at least every 1.5 days, not exceeding 3 days at maximum. A single observation arc spans 3° to 5° on average. Using a simulation environment that connects PROOF to AIUB’s program system CelMech we verify the consistency of the initial orbit determination for five selected test objects on subsequent days as a function of realistic astrometric noise levels. The initial orbit determination is possible. We define requirements for a correlator process essential for catalogue build-up and maintenance. Each single observation should provide an astrometric accuracy of at least 1”-1.5” so that the initially determined orbits are consistent within a few hundred kilometres for the semi-major axis, 0.01 for the eccentricity, and 0.1° for the inclination.

Flohrer, T.; Krag, H.; Klinkrad, H.; Schildknecht, T.

2011-03-01

188

Web-Based Undergraduate Chemistry Problem-Solving: The Interplay of Task Performance, Domain Knowledge and Web-Searching Strategies  

ERIC Educational Resources Information Center

This study investigates the effect of Web-based Chemistry Problem-Solving, with the attributes of Web-searching and problem-solving scaffolds, on undergraduate students' problem-solving task performance. In addition, the nature and extent of Web-searching strategies students used and its correlation with task performance and domain knowledge also…

She, Hsiao-Ching; Cheng, Meng-Tzu; Li, Ta-Wei; Wang, Chia-Yu; Chiu, Hsin-Tien; Lee, Pei-Zon; Chou, Wen-Chi; Chuang, Ming-Hua

2012-01-01

189

The Fundamentals of iSPARQL: A Virtual Triple Approach for Similarity-Based Semantic Web Tasks  

Microsoft Academic Search

This research explores three SPARQL-based techniques to solve Semantic Web tasks that often require similarity measures, such as semantic data integration, ontology mapping, and Semantic Web service matchmaking. Our aim is to see how far it is possible to integrate cus- tomized similarity functions (CSF) into SPARQL to achieve good results for these tasks. Our flrst approach exploits virtual triples

Christoph Kiefer; Abraham Bernstein; Markus Stocker

2007-01-01

190

A library of problem-solving components based on the integration of the search paradigm with task and method ontologies  

Microsoft Academic Search

In this paper we investigate the reuse of tasks and problem solving methods and we propose a model of how to organize a library of reusable components for knowledge based systems. In our approach we first describe a class of problems by means of a task ontology. Then we instantiate a generic model of problem solving as search in terms

Enrico Motta; Zdenek Zdráhal

1998-01-01

191

On the Relationship Between Effort Toward an Ongoing Task and Cue Detection in Event-Based Prospective Memory  

Microsoft Academic Search

In recent theories of event-based prospective memory, researchers have debated what degree of resources are necessary to identify a cue as related to a previously established intention. In order to simulate natural variations in attention, the authors manipulated effort toward an ongoing cognitive task in which intention-related cues were embedded in 3 experiments. High effort toward the ongoing task resulted

Richard L. Marsh; Jason L. Hicks; Gabriel I. Cook

2005-01-01

192

An Online Task-Based Language Learning Environment: Is It Better for Advanced- or Intermediate-Level Second Language Learners?  

ERIC Educational Resources Information Center

This study investigates the relationship of language proficiency to language production and negotiation of meaning that non-native speakers (NNSs) produced in an online task-based language learning (TBLL) environment. Fourteen NNS-NNS dyads collaboratively completed four communicative tasks, using an online TBLL environment specifically designed…

Arslanyilmaz, Abdurrahman

2012-01-01

193

Task-based modeling and optimization of a cone-beam CT scanner for musculoskeletal imaging  

PubMed Central

Purpose: This work applies a cascaded systems model for cone-beam CT imaging performance to the design and optimization of a system for musculoskeletal extremity imaging. The model provides a quantitative guide to the selection of system geometry, source and detector components, acquisition techniques, and reconstruction parameters. Methods: The model is based on cascaded systems analysis of the 3D noise-power spectrum (NPS) and noise-equivalent quanta (NEQ) combined with factors of system geometry (magnification, focal spot size, and scatter-to-primary ratio) and anatomical background clutter. The model was extended to task-based analysis of detectability index (d?) for tasks ranging in contrast and frequency content, and d? was computed as a function of system magnification, detector pixel size, focal spot size, kVp, dose, electronic noise, voxel size, and reconstruction filter to examine trade-offs and optima among such factors in multivariate analysis. The model was tested quantitatively versus the measured NPS and qualitatively in cadaver images as a function of kVp, dose, pixel size, and reconstruction filter under conditions corresponding to the proposed scanner. Results: The analysis quantified trade-offs among factors of spatial resolution, noise, and dose. System magnification (M) was a critical design parameter with strong effect on spatial resolution, dose, and x-ray scatter, and a fairly robust optimum was identified at M???1.3 for the imaging tasks considered. The results suggested kVp selection in the range of ?65–90 kVp, the lower end (65 kVp) maximizing subject contrast and the upper end maximizing NEQ (90 kVp). The analysis quantified fairly intuitive results—e.g., ?0.1–0.2 mm pixel size (and a sharp reconstruction filter) optimal for high-frequency tasks (bone detail) compared to ?0.4 mm pixel size (and a smooth reconstruction filter) for low-frequency (soft-tissue) tasks. This result suggests a specific protocol for 1?×?1 (full-resolution) projection data acquisition followed by full-resolution reconstruction with a sharp filter for high-frequency tasks along with 2?×?2 binning reconstruction with a smooth filter for low-frequency tasks. The analysis guided selection of specific source and detector components implemented on the proposed scanner. The analysis also quantified the potential benefits and points of diminishing return in focal spot size, reduced electronic noise, finer detector pixels, and low-dose limits of detectability. Theoretical results agreed quantitatively with the measured NPS and qualitatively with evaluation of cadaver images by a musculoskeletal radiologist. Conclusions: A fairly comprehensive model for 3D imaging performance in cone-beam CT combines factors of quantum noise, system geometry, anatomical background, and imaging task. The analysis provided a valuable, quantitative guide to design, optimization, and technique selection for a musculoskeletal extremities imaging system under development.

Prakash, P.; Zbijewski, W.; Gang, G. J.; Ding, Y.; Stayman, J. W.; Yorkston, J.; Carrino, J. A.; Siewerdsen, J. H.

2011-01-01

194

Pharmacokinetically based risk assessment of workplace exposure to benzene.  

PubMed

Cancer risk from exposure to benzene for a working lifetime was estimated from data obtained in studies with rodents. Cancers of the Zymbal gland and the blood-forming system were selected as endpoints for the assessment because of their consistent occurrence. The combined metabolites were judged from toxicological data to be the best representative of the reactive agent. Because of similarity in the percentages of lifetime exposed in the rodent studies and in the occupational setting, the amount metabolized/day as a result of exposures 5 days a week for a lifetime was judged to be an appropriate dose paradigm for this assessment. Derived Michaelis-Menton constants were used to convert the doses of combined metabolites from the pharmacokinetic studies to the doses used in the bioassays. Scaling across species was based on allometric relationships. Experimental data were used to scale doses across species with body weight ratios raised to the exponents of 0.74 for the inhalation route and 1.0 for the oral route. The occupational lifetime cancer risk estimated from rodent data was 6 to 14 cases/1000 workers, which is consistent with the 9.5 to 174 leukemia cases/1000 estimated by others from epidemiological data. Implications of these estimates and uncertainties associated with making them are discussed. PMID:2655040

Beliles, R P; Totman, L C

1989-04-01

195

Effects of occupational exposure - is there a link between exposure based on an occupational questionnaire and semen quality?  

PubMed

Abstract Several studies have suggested that human semen quality has declined over past decades and some have associated decline with occupational exposures. Many studies have been conducted in occupational settings, where exposure to occupational pollutants is intense. Our objective was to examine the association between exposure to occupational factors based on an occupational exposure questionnaire, and semen quality parameters (sperm concentration, motility, sperm morphology) and sperm chromatin structure. The study population consisted of 336 men who were attending an infertility clinic for diagnostic purposes and who had a normal semen concentration of ?15?mln/ml according to WHO criteria. All participants were interviewed and provided a semen sample. Additionally, a detailed questionnaire about the exposure to occupational factors was performed among the study participants. The results of the study suggest that occupational factors may affect semen quality. The exposure to noise during work was associated with decreased motility and increased DNA damage (p?=?0.005 and p?=?0.02, respectively). Exposure to polyvinyl chloride (PVC) decreased sperm concentration and motility (p?=?0.02 and p?=?0.03, respectively). Whereas exposure to high temperatures and sitting for more than 6 hours during work was positively associated with DNA fragmentation index (DFI) (p?=?0.03 and p?=?0.001, respectively). After applying the correction for multiple comparisons only the exposure to noise and sitting ?6 hours during work was associated with poorer semen quality (decreased motility and increased DFI, respectively). This study showed associations between self-reported occupational exposures and impaired semen parameters. The occupational exposure questionnaire may be useful in clinical practice for patients and physicians to identify the work factors associated with poorer semen quality. PMID:24702586

Jurewicz, Joanna; Radwan, Micha?; Sobala, Wojciech; Radwan, Pawe?; Bochenek, Micha?; Hanke, Wojciech

2014-08-01

196

[Exposure to vegetal esters based metal cutting fluids: health effects].  

PubMed

The aim of our research is to study respiratory and dermatologic diseases (irritative and allergic) in a cohort of workers exposed to vegetal esters based metal cutting fluids of the latest generation. A cohort of 81 workers (mean age 34.5 years, seniority 17.4 years), with mean exposure to vegetal esters based metal cutting fluids of 2.8 years, has been subjected to clinical evaluations. The investigation did not reveal any disease or disorder of the respiratory system, any folluculitis or any allergic contact dermatitis caused by sensitization to vegetal esters based metal cutting fluids. On the contrary we documented 5 cases of irritant contact dermatitis, even if favored by an improper use of protection devices. According to early results, the introduction of vegetal esters based metal cutting fluids seems to reduce the risk to the worker's health. A longitudinal surveillance is still needed to confirm that even in the medium and long-term sensitizations will not occur. PMID:23405602

Riva, M M; Bellini, M; Leghissa, P; Gambini, D; Mosconi, G

2012-01-01

197

Extraversion differentiates between model-based and model-free strategies in a reinforcement learning task.  

PubMed

Prominent computational models describe a neural mechanism for learning from reward prediction errors, and it has been suggested that variations in this mechanism are reflected in personality factors such as trait extraversion. However, although trait extraversion has been linked to improved reward learning, it is not yet known whether this relationship is selective for the particular computational strategy associated with error-driven learning, known as model-free reinforcement learning, vs. another strategy, model-based learning, which the brain is also known to employ. In the present study we test this relationship by examining whether humans' scores on an extraversion scale predict individual differences in the balance between model-based and model-free learning strategies in a sequentially structured decision task designed to distinguish between them. In previous studies with this task, participants have shown a combination of both types of learning, but with substantial individual variation in the balance between them. In the current study, extraversion predicted worse behavior across both sorts of learning. However, the hypothesis that extraverts would be selectively better at model-free reinforcement learning held up among a subset of the more engaged participants, and overall, higher task engagement was associated with a more selective pattern by which extraversion predicted better model-free learning. The findings indicate a relationship between a broad personality orientation and detailed computational learning mechanisms. Results like those in the present study suggest an intriguing and rich relationship between core neuro-computational mechanisms and broader life orientations and outcomes. PMID:24027514

Skatova, Anya; Chan, Patricia A; Daw, Nathaniel D

2013-01-01

198

Report of the Defense Science Board Task Force on Defense Science and Technology Base for the 21st Century.  

National Technical Information Service (NTIS)

This report examines issues involved in assuring that the United States has an adequate technology base to maintain military superiority into the 21st Century. The Terms of Reference directed that the Task Force make recommendations on the funding, manage...

1998-01-01

199

Acute exposure to power-frequency magnetic fields has no effect on the acquisition of a spatial learning task by adult male mice  

SciTech Connect

A series of four experiments was performed to determine whether acute exposure to a range of 50 Hz magnetic fields had any effect on a learning task in adult male CD1 mice. A radial-arm maze placed within the bore of an electromagnetic was used to assess spatial discrimination learning for food reward. Subjects were reduced to 85% of their free-feeding weight and were placed in the maze for up to 15 minutes each day for 10 days. Performance of the task was measured by using maximum likelihood techniques to calculate the probability that an animal would not reenter any given arm of the maze. Experimental subjects were exposed to a vertical, 50 Hz sinusoidal magnetic field at 5 {micro}T, 50 {micro}T, 0.5 mT, or 5.0 mT (rms). Control subjects were exposed only to a background time-varying field of less than 50 nT and the ambient static field of about 40 {micro}T. The variation in the applied magnetic field was less than 5% except at the ends of the arms, where is approached 10%. It was found that all eight groups of subjects (n = 10 in all cases) showed similar increases in performance with testing, and the acquisition curve for each group of experimental subjects was not significantly different from that of their control group (P > 0.05 in all cases). It was concluded that exposure had no effect on learning at any flux density. This result is contrary to the findings of a number of preliminary studies, although other studies have reported that magnetic fields do not affect spatial learning in adult male rodents. It is possible that differences between experimental conditions might explain some of this apparent discrepancy.

Sienkiewicz, Z.J.; Haylock, R.G.E.; Saunders, R.D. [National Radiological Protection Board, Chilton (United Kingdom)] [National Radiological Protection Board, Chilton (United Kingdom)

1996-12-01

200

The effects of exposure to traumatic stressors on inhibitory control in police officers: a dense electrode array study using a Go/NoGo continuous performance task.  

PubMed

Exposure to psychologically stressful and traumatic experiences and the requirement of heightened attention to environmental stimuli are common in police work. Police officers are at increased risk for stress-related disorders such as Post-Traumatic Stress Disorder (PTSD). Traumatic experiences can result in changes to brain structure and function associated with attention and cognitive control processes (such as response inhibition). Despite the significance that these cognitive functions may have on job performance in police officers, few studies have examined the effects of exposure to traumatic events on top-down cognitive control functions in police. In the present study, a dense electrode array system was used to examined the N2 and P3 components of the event-related potential (ERP) during a Go/NoGo continuous performance task (Go/NoGo CPT) in trauma-exposed police officers who did not meet criteria for a current diagnosis of PTSD and in non-trauma exposed civilian controls. Amplitude and latency were obtained to Go, NoGo, and non-target trials. The major between-group findings were for P3 amplitude. There were no group effects for N2. Both groups had an enhanced fronto-central P3 amplitude to NoGo compared to Go trials. However, police had greater P3 amplitude compared to controls for all trial types (Go, NoGo, non-target). PTSD symptom scores in police officers were positively correlated with fronto-central NoGo P3 amplitude, but not with posterior NoGo amplitude. This study provides evidence of heightened attention and/or arousal in police officers as indicated by the generally greater P3 amplitude in police compared to controls during a task requiring sustained attention and inhibitory control. Greater PTSD symptom severity in trauma-exposed individuals may affect frontal cognitive control systems related to response inhibition. PMID:23528305

Covey, Thomas J; Shucard, Janet L; Violanti, John M; Lee, Jeff; Shucard, David W

2013-03-01

201

Studying hemispheric lateralization during a Stroop task through near-infrared spectroscopy-based connectivity  

NASA Astrophysics Data System (ADS)

Near-infrared spectroscopy (NIRS) is a developing and promising functional brain imaging technology. Developing data analysis methods to effectively extract meaningful information from collected data is the major bottleneck in popularizing this technology. In this study, we measured hemodynamic activity of the prefrontal cortex (PFC) during a color-word matching Stroop task using NIRS. Hemispheric lateralization was examined by employing traditional activation and novel NIRS-based connectivity analyses simultaneously. Wavelet transform coherence was used to assess intrahemispheric functional connectivity. Spearman correlation analysis was used to examine the relationship between behavioral performance and activation/functional connectivity, respectively. In agreement with activation analysis, functional connectivity analysis revealed leftward lateralization for the Stroop effect and correlation with behavioral performance. However, functional connectivity was more sensitive than activation for identifying hemispheric lateralization. Granger causality was used to evaluate the effective connectivity between hemispheres. The results showed increased information flow from the left to the right hemispheres for the incongruent versus the neutral task, indicating a leading role of the left PFC. This study demonstrates that the NIRS-based connectivity can reveal the functional architecture of the brain more comprehensively than traditional activation, helping to better utilize the advantages of NIRS.

Zhang, Lei; Sun, Jinyan; Sun, Bailei; Luo, Qingming; Gong, Hui

2014-05-01

202

KERNEL-BASED MULTI-TASK JOINT SPARSE CLASSIFICATION FOR ALZHEIMER'S DISEASE  

PubMed Central

Multi-modality imaging provides complementary information for diagnosis of neurodegenerative disorders such as Alzheimer’s disease (AD) and its prodrome, mild cognitive impairment (MCI). In this paper, we propose a kernel-based multi-task sparse representation model to combine the strengths of MRI and PET imaging features for improved classification of AD. Sparse representation based classification seeks to represent the testing data with a sparse linear combination of training data. Here, our approach allows information from different imaging modalities to be used for enforcing class level joint sparsity via multi-task learning. Thus the common most representative classes in the training samples for all modalities are jointly selected to reconstruct the testing sample. We further improve the discriminatory power by extending the framework to the reproducing kernel Hilbert space (RKHS) so that nonlinearity in the features can be captured for better classification. Experiments on Alzheimer’s Disease Neuroimaging Initiative database shows that our proposed method can achieve 93.3% and 78.9% accuracy for classification of AD and MCI from healthy controls, respectively, demonstrating promising performance in AD study.

Wang, Yaping; Liu, Manhua; Guo, Lei; Shen, Dinggang

2013-01-01

203

Prospective and Retrospective Time Estimates of Children: A Comparison Based on Ecological Tasks  

PubMed Central

Children's time estimation literature lacks of studies comparing prospective and retrospective time estimates of long lasting ecological tasks, i.e. tasks reflecting children's daily activities. In the present study, children were asked to estimate prospectively or retrospectively how much time they played a video game or read a magazine. Regardless of the task, the results revealed that prospective time estimates were longer than the retrospective ones. Also, time estimates of the video game task were longer, less accurate and more variable than those of the reading task. The results are discussed in the light of the current literature about time estimation of long lasting ecological tasks.

Bisson, Nicolas; Tobin, Simon; Grondin, Simon

2012-01-01

204

Imaging Tasks Scheduling for High-Altitude Airship in Emergency Condition Based on Energy-Aware Strategy  

PubMed Central

Aiming to the imaging tasks scheduling problem on high-altitude airship in emergency condition, the programming models are constructed by analyzing the main constraints, which take the maximum task benefit and the minimum energy consumption as two optimization objectives. Firstly, the hierarchy architecture is adopted to convert this scheduling problem into three subproblems, that is, the task ranking, value task detecting, and energy conservation optimization. Then, the algorithms are designed for the sub-problems, and the solving results are corresponding to feasible solution, efficient solution, and optimization solution of original problem, respectively. This paper makes detailed introduction to the energy-aware optimization strategy, which can rationally adjust airship's cruising speed based on the distribution of task's deadline, so as to decrease the total energy consumption caused by cruising activities. Finally, the application results and comparison analysis show that the proposed strategy and algorithm are effective and feasible.

Zhimeng, Li; Chuan, He; Dishan, Qiu; Jin, Liu; Manhao, Ma

2013-01-01

205

Metaheuristic Based Scheduling Meta-Tasks in Distributed Heterogeneous Computing Systems  

PubMed Central

Scheduling is a key problem in distributed heterogeneous computing systems in order to benefit from the large computing capacity of such systems and is an NP-complete problem. In this paper, we present a metaheuristic technique, namely the Particle Swarm Optimization (PSO) algorithm, for this problem. PSO is a population-based search algorithm based on the simulation of the social behavior of bird flocking and fish schooling. Particles fly in problem search space to find optimal or near-optimal solutions. The scheduler aims at minimizing makespan, which is the time when finishes the latest task. Experimental studies show that the proposed method is more efficient and surpasses those of reported PSO and GA approaches for this problem.

Izakian, Hesam; Abraham, Ajith; Snasel, Vaclav

2009-01-01

206

Estimating cognitive workload using wavelet entropy-based features during an arithmetic task.  

PubMed

Electroencephalography (EEG) has shown promise as an indicator of cognitive workload; however, precise workload estimation is an ongoing research challenge. In this investigation, seven levels of workload were induced using an arithmetic task, and the entropy of wavelet coefficients extracted from EEG signals is shown to distinguish all seven levels. For a subject-independent multi-channel classification scheme, the entropy features achieved high accuracy, up to 98% for channels from the frontal lobes, in the delta frequency band. This suggests that a smaller number of EEG channels in only one frequency band can be deployed for an effective EEG-based workload classification system. Together with analysis based on phase locking between channels, these results consistently suggest increased synchronization of neural responses for higher load levels. PMID:24290935

Zarjam, Pega; Epps, Julien; Chen, Fang; Lovell, Nigel H

2013-12-01

207

The interacting role of media violence exposure and aggressive-disruptive behavior in adolescent brain activation during an emotional Stroop task.  

PubMed

Only recently have investigations of the relationship between media violence exposure (MVE) and aggressive behavior focused on brain functioning. In this study, we examined the relationship between brain activation and history of media violence exposure in adolescents, using functional magnetic resonance imaging (fMRI). Samples of adolescents with no psychiatric diagnosis or with disruptive behavior disorder (DBD) with aggression were compared to investigate whether the association of MVE history and brain activation is moderated by aggressive behavior/personality. Twenty-two adolescents with a history of aggressive behavior and diagnosis of either conduct disorder or oppositional-defiant disorder (DBD sample) and 22 controls completed an emotional Stroop task during fMRI. Primary imaging results indicated that controls with a history of low MVE demonstrated greater activity in the right inferior frontal gyrus and rostral anterior cingulate during the violent word condition. In contrast, in adolescents with DBD, those with high MVE exhibited decreased activation in the right amygdala, compared with those with low MVE. These findings are consistent with research demonstrating the importance of fronto-limbic structures for processing emotional stimuli, and with research suggesting that media violence may affect individuals in different ways depending on the presence of aggressive traits. PMID:21376543

Kalnin, Andrew J; Edwards, Chad R; Wang, Yang; Kronenberger, William G; Hummer, Tom A; Mosier, Kristine M; Dunn, David W; Mathews, Vincent P

2011-04-30

208

Age-Associated Effects of a Concurrent Cognitive Task on Gait Speed and Stability During Narrow-Base Walking  

PubMed Central

Background In older adults, changes in speed and stability during walking are associated with impaired balance and increased fall risk. Narrow-base walking requires increased frontal plane stability and can be used to assess postural control while walking. Performance of a concurrent cognitive task (dual task) may further increase the complexity of walking, potentially allowing identification of individuals with instability that is not detected under single-task conditions. The purpose of this study was to examine age-associated effects of a cognitive task on speed and frontal plane stability during narrow-base walking. Methods Thirty-four healthy adults participated, categorized by age: <65, 65–74, and ?75 years. Participants walked at a comfortable pace within a narrow path under both single- and dual-task conditions. We examined spatiotemporal variables and frontal plane center of mass (CoM) parameters using a 13-segment biomechanical model. Results Increasing age (p < .001) and the performance of a concurrent cognitive task (p < .001) were both associated with decreased speed, with no interaction between these factors. Frontal plane CoM displacement and velocity increased with increasing age (both p < .001), but dual-task performance had no effect on these variables (both p > .450). Conclusions Age-associated changes in both speed and stability are observed during narrow-base walking. Among this sample of healthy older adults, the addition of a concurrent cognitive task resulted in reduced speed, with no effect on frontal plane stability. Further research is needed to determine if dual-task, narrow-base walking is a sensitive and specific approach to identifying older adults at risk for falls.

Kelly, Valerie E.; Schrager, Matthew A.; Price, Robert; Ferrucci, Luigi; Shumway-Cook, Anne

2009-01-01

209

Development of the town data base: Estimates of exposure rates and times of fallout arrival near the Nevada Test Site  

SciTech Connect

As part of the U.S. Department of Energy`s Off-Site Radiation Exposure Review Project, the time of fallout arrival and the H+12 exposure rate were estimated for populated locations in Arizona, California, Nevada, and Utah that were affected by fallout from one or more nuclear tests at the Nevada Test Site. Estimates of exposure rate were derived from measured values recorded before and after each test by fallout monitors in the field. The estimate for a given location was obtained by retrieving from a data base all measurements made in the vicinity, decay-correcting them to H+12, and calculating an average. Estimates were also derived from maps produced after most events that show isopleths of exposure rate and time of fallout arrival. Both sets of isopleths on these maps were digitized, and kriging was used to interpolate values at the nodes of a 10-km grid covering the pattern. The values at any location within the grid were then estimated from the values at the surrounding grid nodes. Estimates of dispersion (standard deviation) were also calculated. The Town Data Base contains the estimates for all combinations of location and nuclear event for which the estimated mean H+12 exposure rate was greater than three times background. A listing of the data base is included as an appendix. The information was used by other project task groups to estimate the radiation dose that off-site populations and individuals may have received as a result of exposure to fallout from Nevada nuclear tests.

Thompson, C.B.; McArthur, R.D. [Univ. and Community College System of Nevada, Las Vegas, NV (United States); Hutchinson, S.W. [Mead Johnson Nutritional Group, Evansville, IN (United States)

1994-09-01

210

Complexity, Accuracy, Fluency and Lexis in Task-Based Performance: A Synthesis of the Ealing Research  

ERIC Educational Resources Information Center

This chapter will present a research synthesis of a series of studies, termed here the Ealing research. The studies use the same general framework to conceptualise tasks and task performance, enabling easier comparability. The different studies, although each is self-contained, build into a wider picture of task performance. The major point of…

Skehan, Peter; Foster, Pauline

2012-01-01

211

Model-Based Analysis and Classification of Driver Distraction Under Secondary Tasks  

Microsoft Academic Search

It is well established in the literature that secondary tasks adversely affect driving behavior. Previous research has focused on discovering the general trends by analyzing the average effects of secondary tasks on a population of drivers. This paper conjectures that there may also be individual effects, i.e., different effects of secondary tasks on individual drivers, which may be obscured within

Tulga Ersal; Helen J. A. Fuller; Omer Tsimhoni; Jeffrey L. Stein; Hosam K. Fathy

2010-01-01

212

Contextual Resource Negotiation-Based Task Allocation and Load Balancing in Complex Software Systems  

Microsoft Academic Search

In the complex software systems, software agents always need to negotiate with other agents within their physical and social contexts when they execute tasks. Obviously, the capacity of a software agent to execute tasks is determined by not only itself but also its contextual agents; thus, the number of tasks allocated on an agent should be directly proportional to its

Yichuan Jiang; Jiuchuan Jiang

2009-01-01

213

Testing and optimizing the performance of a floor-based task conditioning system  

Microsoft Academic Search

During recent years an increasing amount of attention has been paid to air distribution systems that individually condition the immediate environments of office workers within their workstations. As with task lighting systems, the controls for these ‘task conditioning’ systems are partially or entirely decentralized and under the control of the occupants. Among the primary types of task conditioning systems (floor-,

F. S. Bauman; E. A. Arens; S. Tanabe; H. Zhang; A. Baharlo

1995-01-01

214

Vision-Based Long-Range 3D Tracking, applied to Underground Surveying Tasks  

NASA Astrophysics Data System (ADS)

To address the need of highly automated positioning systems in underground construction, we present a long-range 3D tracking system based on infrared optical markers. It provides continuous 3D position estimation of static or kinematic targets with low latency over a tracking volume of 12 m x 8 m x 70 m (width x height x depth). Over the entire volume, relative 3D point accuracy with a maximal deviation ? 22 mm is ensured with possible target rotations of yaw, pitch = 0 - 45° and roll = 0 - 360°. No preliminary sighting of target(s) is necessary since the system automatically locks onto a target without user intervention and autonomously starts tracking as soon as a target is within the view of the system. The proposed system needs a minimal hardware setup, consisting of two machine vision cameras and a standard workstation for data processing. This allows for quick installation with minimal disturbance of construction work. The data processing pipeline ensures camera calibration and tracking during on-going underground activities. Tests in real underground scenarios prove the system's capabilities to act as 3D position measurement platform for multiple underground tasks that require long range, low latency and high accuracy. Those tasks include simultaneously tracking of personnel, machines or robots.

Mossel, Annette; Gerstweiler, Georg; Vonach, Emanuel; Kaufmann, Hannes; Chmelina, Klaus

2014-04-01

215

An Agent-Based Simulation for Investigating the Impact of Stereotypes on Task-Oriented Group Formation  

NASA Astrophysics Data System (ADS)

In this paper, we introduce an agent-based simulation for investigating the impact of social factors on the formation and evolution of task-oriented groups. Task-oriented groups are created explicitly to perform a task, and all members derive benefits from task completion. However, even in cases when all group members act in a way that is locally optimal for task completion, social forces that have mild effects on choice of associates can have a measurable impact on task completion performance. In this paper, we show how our simulation can be used to model the impact of stereotypes on group formation. In our simulation, stereotypes are based on observable features, learned from prior experience, and only affect an agent's link formation preferences. Even without assuming stereotypes affect the agents' willingness or ability to complete tasks, the long-term modifications that stereotypes have on the agents' social network impair the agents' ability to form groups with sufficient diversity of skills, as compared to agents who form links randomly. An interesting finding is that this effect holds even in cases where stereotype preference and skill existence are completely uncorrelated.

Maghami, Mahsa; Sukthankar, Gita

216

Population Based Exposure Assessment of Bioaccessible Arsenic in Carrots  

EPA Science Inventory

The two predominant arsenic exposure routes are food and water. Estimating the risk from dietary exposures is complicated, owing to the chemical form dependent toxicity of arsenic and the diversity of arsenicals present in dietary matrices. Two aspects of assessing dietary expo...

217

A distributed computing environment with support for constraint-based task scheduling and scientific experimentation  

SciTech Connect

This paper describes a computing environment which supports computer-based scientific research work. Key features include support for automatic distributed scheduling and execution and computer-based scientific experimentation. A new flexible and extensible scheduling technique that is responsive to a user`s scheduling constraints, such as the ordering of program results and the specification of task assignments and processor utilization levels, is presented. An easy-to-use constraint language for specifying scheduling constraints, based on the relational database query language SQL, is described along with a search-based algorithm for fulfilling these constraints. A set of performance studies show that the environment can schedule and execute program graphs on a network of workstations as the user requests. A method for automatically generating computer-based scientific experiments is described. Experiments provide a concise method of specifying a large collection of parameterized program executions. The environment achieved significant speedups when executing experiments; for a large collection of scientific experiments an average speedup of 3.4 on an average of 5.5 scheduled processors was obtained.

Ahrens, J.P.; Shapiro, L.G.; Tanimoto, S.L. [Univ. of Washington, Seattle, WA (United States). Dept. of Computer Science and Engineering

1997-04-01

218

Population-Based Case-Control Study of Occupational Exposure to Electromagnetic Fields and Breast Cancer  

Microsoft Academic Search

PURPOSE: This population-based case-control study examined occupational exposure to electromagnetic fields in relation to female breast cancer incidence among 843 breast cancer cases and 773 controls.METHODS: Exposure was classified based on work in the two longest-held jobs, and indices of cumulative exposure to magnetic fields based on a measurement survey.RESULTS: Female breast cancer was not associated with employment as an

Edwin Van Wijngaarden; Leena A Nylander-French; Robert C Millikan; David A Savitz; Dana Loomis

2001-01-01

219

Competition and performance on a computer-based complex perceptual-motor task.  

PubMed

Employees of temporary agencies practiced Space Fortress, a complex video game task, for 10 sessions, each consisting of 8 practice and 2 test games of 3 min each. Trainees practiced individually, in dyads, or in tetrads, and they were classified as having high or low aptitude based on computer attitude scores and baseline performance. Competition for monetary prizes was introduced early in training, late in training, or not at all. Competition facilitated high-aptitude trainees but not low-aptitude trainees. Group size and the timing of competition instructions had no main effects or interactions. The results are discussed in terms of social facilitation theory, according to which competition facilitates dominant responses, which helps high-skill trainees but not low-skill trainees. PMID:9394634

Worchel, S; Shebilske, W L; Jordan, J A; Prislin, R

1997-09-01

220

Real-Time Motion Planning for a Volleyball Robot Task Based on a Multi-Agent Technique  

Microsoft Academic Search

This paper takes the volleyball robot task as an example of a dynamic manipulation task and presents a multi-agent-based motion-planning\\u000a framework for it. Each subtask in the motion planning is defined as an agent. The motion planning is accomplished by the solution\\u000a of each agent activated by a blackboard. It is convenient to extend the module and enable real-time control

Pei-yan Zhang; Lü Tian-sheng

2007-01-01

221

GLMdenoise: a fast, automated technique for denoising task-based fMRI data.  

PubMed

In task-based functional magnetic resonance imaging (fMRI), researchers seek to measure fMRI signals related to a given task or condition. In many circumstances, measuring this signal of interest is limited by noise. In this study, we present GLMdenoise, a technique that improves signal-to-noise ratio (SNR) by entering noise regressors into a general linear model (GLM) analysis of fMRI data. The noise regressors are derived by conducting an initial model fit to determine voxels unrelated to the experimental paradigm, performing principal components analysis (PCA) on the time-series of these voxels, and using cross-validation to select the optimal number of principal components to use as noise regressors. Due to the use of data resampling, GLMdenoise requires and is best suited for datasets involving multiple runs (where conditions repeat across runs). We show that GLMdenoise consistently improves cross-validation accuracy of GLM estimates on a variety of event-related experimental datasets and is accompanied by substantial gains in SNR. To promote practical application of methods, we provide MATLAB code implementing GLMdenoise. Furthermore, to help compare GLMdenoise to other denoising methods, we present the Denoise Benchmark (DNB), a public database and architecture for evaluating denoising methods. The DNB consists of the datasets described in this paper, a code framework that enables automatic evaluation of a denoising method, and implementations of several denoising methods, including GLMdenoise, the use of motion parameters as noise regressors, ICA-based denoising, and RETROICOR/RVHRCOR. Using the DNB, we find that GLMdenoise performs best out of all of the denoising methods we tested. PMID:24381539

Kay, Kendrick N; Rokem, Ariel; Winawer, Jonathan; Dougherty, Robert F; Wandell, Brian A

2013-01-01

222

Integration of base rates and new information in an abstract hypothesis-testing task.  

PubMed

In two studies, we investigated how people use base rates and the presence versus the absence of new information to judge which of two hypotheses is more likely. Participants were given problems based on two decks of cards printed with 0-4 letters. A table showed the relative frequencies of the letters on the cards within each deck. Participants were told the letters that were printed on or absent from a card the experimenter had drawn. Base rates were conveyed by telling participants that the experimenter had chosen the deck by drawing from an urn containing, in different proportions, tickets marked either 'deck 1' or 'deck 2'. The task was to judge from which of the two decks the card was most likely drawn. Prior probabilities and the evidential strength of the subset of present clues (computed as 'weight of evidence') were the only significant predictors of participants' dichotomous (both studies) and continuous (Study 2) judgments. The evidential strength of all clues was not a significant predictor of participants' judgments in either study, and no significant interactions emerged. We discuss the results as evidence for additive integration of base rates and the new present information in hypothesis testing. PMID:23560666

Rusconi, Patrice; Marelli, Marco; Russo, Selena; D'Addario, Marco; Cherubini, Paolo

2013-05-01

223

Task-specific noise exposure during manual concrete surface grinding in enclosed areas-influence of operation variables and dust control methods.  

PubMed

Noise exposure is a distinct hazard during hand-held concrete grinding activities, and its assessment is challenging because of the many variables involved. Noise dosimeters were used to examine the extent of personal noise exposure while concrete grinding was performed with a variety of grinder sizes, types, accessories, and available dust control methods. Noise monitoring was conducted in an enclosed area covering 52 task-specific grinding sessions lasting from 6 to 72 minutes. Noise levels, either in minute average noise level (Lavg, dBA) or in minute peak (dBC), during concrete grinding were significantly (P < 0.01) correlated with general ventilation (GV: on, off), dust control methods (uncontrolled, wet, Shop-Vac, HEPA, HEPA-Cyclone), grinding cup wheel (blade) sizes of 4-inch (100 mm), 5-inch (125 mm) and 6-inch (150 mm), and surface orientation (horizontal, inclined). Overall, minute Lavg during grinding was 97.0 ± 3.3 (mean ± SD), ranging from 87.9 to 113. The levels of minute Lavg during uncontrolled grinding (98.9 ± 5.2) or wet-grinding (98.5 ± 2.7) were significantly higher than those during local exhaust ventilation (LEV) grinding (96.2 ± 2.8). A 6-inch grinding cup wheel generated significantly higher noise levels (98.7 ± 2.8) than 5-inch (96.3 ± 3.2) or 4-inch (95.3 ± 3.5) cup wheels. The minute peak noise levels (dBC) during grinding was 113 ± 5.2 ranging from 104 to 153. The minute peak noise levels during uncontrolled grinding (119 ± 10.2) were significantly higher than those during wet-grinding (115 ± 4.5) and LEV-grinding (112 ± 3.4). A 6-inch grinding cup wheel generated significantly higher minute peak noise levels (115 ± 5.3) than 5-inch (112 ± 4.5) or 4-inch (111 ± 5.4) cup wheels. Assuming an 8-hour work shift, the results indicated that noise exposure levels during concrete grinding in enclosed areas exceeded the recommended permissible exposure limits and workers should be protected by engineering control methods, safe work practices, and/or personal protective devices. PMID:23926952

Akbar-Khanzadeh, Farhang; Ames, April L; Milz, Sheryl A; Akbar-Khanzadeh, Mahboubeh

2013-01-01

224

Evaluating the impact of task demands and block resolution on the effectiveness of pixel-based visualization.  

PubMed

Pixel-based visualization is a popular method of conveying large amounts of numerical data graphically. Application scenarios include business and finance, bioinformatics and remote sensing. In this work, we examined how the usability of such visual representations varied across different tasks and block resolutions. The main stimuli consisted of temporal pixel-based visualization with a white-red color map, simulating monthly temperature variation over a six-year period. In the first study, we included 5 separate tasks to exert different perceptual loads. We found that performance varied considerably as a function of task, ranging from 75% correct in low-load tasks to below 40% in high-load tasks. There was a small but consistent effect of resolution, with the uniform patch improving performance by around 6% relative to higher block resolution. In the second user study, we focused on a high-load task for evaluating month-to-month changes across different regions of the temperature range. We tested both CIE L*u*v* and RGB color spaces. We found that the nature of the change-evaluation errors related directly to the distance between the compared regions in the mapped color space. We were able to reduce such errors by using multiple color bands for the same data range. In a final study, we examined more fully the influence of block resolution on performance, and found block resolution had a limited impact on the effectiveness of pixel-based visualization. PMID:20975133

Borgo, Rita; Proctor, Karl; Chen, Min; Jänicke, Heike; Murray, Tavi; Thornton, Ian M

2010-01-01

225

A tweaking principle for executive control: neuronal circuit mechanism for rule-based task switching and conflict resolution.  

PubMed

A hallmark of executive control is the brain's agility to shift between different tasks depending on the behavioral rule currently in play. In this work, we propose a "tweaking hypothesis" for task switching: a weak rule signal provides a small bias that is dramatically amplified by reverberating attractor dynamics in neural circuits for stimulus categorization and action selection, leading to an all-or-none reconfiguration of sensory-motor mapping. Based on this principle, we developed a biologically realistic model with multiple modules for task switching. We found that the model quantitatively accounts for complex task switching behavior: switch cost, congruency effect, and task-response interaction; as well as monkey's single-neuron activity associated with task switching. The model yields several testable predictions, in particular, that category-selective neurons play a key role in resolving sensory-motor conflict. This work represents a neural circuit model for task switching and sheds insights in the brain mechanism of a fundamental cognitive capability. PMID:24336717

Ardid, Salva; Wang, Xiao-Jing

2013-12-11

226

Fuel Hedging Task Group.  

National Technical Information Service (NTIS)

At the direction of the Under Secretary of Defense (Comptroller) (USD (C)), the Defense Business Board (formerly known as the Defense Business Practice Implementation Board) was tasked with examining potential ways to reduce the Department's exposure to f...

2004-01-01

227

Use of physiologically based pharmacokinetic models to establish biological exposure indexes  

SciTech Connect

This paper presents a simulation modeling approach to establish biological exposure indexes (BEIs) from ambient occupational exposure limits (OELs). A physiologically based pharmacokinetic (PB-PK) model was used to describe the disposition of volatile organic chemicals in the human. The model was used to simulate an exposure regimen similar to a typical work schedule. Exposure concentrations were set to equal the ambient OELs of the corresponding chemicals. Chemical concentrations in the expired air and blood and concentrations of metabolites in the urine were estimated with the PB-PK model for this exposure condition. Because the OELs establish the criteria for ambient exposure to chemicals, the concentrations of chemicals or their metabolites in biological media resulting from exposure to the OELs would likewise define acceptable exposure standards. On the basis of this rationale and method, BEIs were developed for 13 common industrial organic chemicals.

Leung, H.W. (Applied Toxicology, Health Safety and Environmental Affairs, Union Carbide Chemicals and Plastics Company Inc., Danbury, CT (United States))

1992-06-01

228

Non-linguistic learning and aphasia: Evidence from a paired associate and feedback-based task  

PubMed Central

Though aphasia is primarily characterized by impairments in the comprehension and/or expression of language, research has shown that patients with aphasia also show deficits in cognitive-linguistic domains such as attention, executive function, concept knowledge and memory (Helm-Estabrooks, 2002 for review). Research in aphasia suggests that cognitive impairments can impact the online construction of language, new verbal learning, and transactional success (Freedman & Martin, 2001; Hula & McNeil, 2008; Ramsberger, 2005). In our research, we extend this hypothesis to suggest that general cognitive deficits influence progress with therapy. The aim of our study is to explore learning, a cognitive process that is integral to relearning language, yet underexplored in the field of aphasia rehabilitation. We examine non-linguistic category learning in patients with aphasia (n=19) and in healthy controls (n=12), comparing feedback and non-feedback based instruction. Participants complete two computer-based learning tasks that require them to categorize novel animals based on the percentage of features shared with one of two prototypes. As hypothesized, healthy controls showed successful category learning following both methods of instruction. In contrast, only 60% of our patient population demonstrated successful non-linguistic category learning. Patient performance was not predictable by standardized measures of cognitive ability. Results suggest that general learning is affected in aphasia and is a unique, important factor to consider in the field of aphasia rehabilitation.

Vallila-Rohter, Sofia; Kiran, Swathi

2013-01-01

229

Object-based task-level control: A hierarchical control architecture for remote operation of space robots  

NASA Technical Reports Server (NTRS)

Expanding man's presence in space requires capable, dexterous robots capable of being controlled from the Earth. Traditional 'hand-in-glove' control paradigms require the human operator to directly control virtually every aspect of the robot's operation. While the human provides excellent judgment and perception, human interaction is limited by low bandwidth, delayed communications. These delays make 'hand-in-glove' operation from Earth impractical. In order to alleviate many of the problems inherent to remote operation, Stanford University's Aerospace Robotics Laboratory (ARL) has developed the Object-Based Task-Level Control architecture. Object-Based Task-Level Control (OBTLC) removes the burden of teleoperation from the human operator and enables execution of tasks not possible with current techniques. OBTLC is a hierarchical approach to control where the human operator is able to specify high-level, object-related tasks through an intuitive graphical user interface. Infrequent task-level command replace constant joystick operations, eliminating communications bandwidth and time delay problems. The details of robot control and task execution are handled entirely by the robot and computer control system. The ARL has implemented the OBTLC architecture on a set of Free-Flying Space Robots. The capability of the OBTLC architecture has been demonstrated by controlling the ARL Free-Flying Space Robots from NASA Ames Research Center.

Stevens, H. D.; Miles, E. S.; Rock, S. J.; Cannon, R. H.

1994-01-01

230

A Complete Methodology for Generating Multi-Robot Task Solutions using ASyMTRe-D and Market-Based Task Allocation  

Microsoft Academic Search

This paper presents an approach that enables heterogeneous robots to automatically form groups as needed to generate both strongly-cooperative and weakly-cooperative multi-robot task solutions in the same application. The funda- mental contribution of this work is the layering of our low- level coalition formation algorithm for generating strongly- cooperative task solutions, with high-level, traditional task allocation methods for weakly-cooperative task

Fang Tang; Lynne E. Parker

2007-01-01

231

Report of the Defense Science Board Task Force on Defense Science and Technology Base for the 21st Century.  

National Technical Information Service (NTIS)

The Defense Science Board Task Force on the Defense Science and Technology Base for the 21st Century was formed in May 1997 to address issues involved in assuring that the United States has an adequate technology base to maintain military superiority into...

1998-01-01

232

Historical limitations of determinant based exposure groupings in the rubber manufacturing industry  

PubMed Central

Aims: To study the validity of using a cross-sectional industry-wide exposure survey to develop exposure groupings for epidemiological purposes that extend beyond the time period in which the exposure data were collected. Methods: Exposure determinants were used to group workers into high, medium, and low exposure groups. The contrast of this grouping and other commonly used grouping schemes based on plant and department within this exposure survey and a previously conducted survey within the same industry (and factories) were estimated and compared. Results: Grouping of inhalable and dermal exposure based on exposure determinants resulted in the highest, but still modest, contrast (? ? 0.3). Classifying subjects based on a combination of plant and department resulted in a slightly lower contrast (? ? 0.2). If the determinant based grouping derived from the 1997 exposure survey was used to classify workers in the 1988 survey the average contrast decreased significantly for both exposures (? ? 0.1). On the contrary, the exposure classification based on plant and department increased in contrast (from ? ? 0.2 to ? ? 0.3) and retained its relative ranking overtime. Conclusions: Although determinant based groupings seem to result in more efficient groupings within a cross-sectional survey, they have to be used with caution as they might result in significant less contrast beyond the studied population or time period. It is concluded that a classification based on plant and department might be more desirable for retrospective studies in the rubber manufacturing industry, as they seem to have more historical relevance and are most likely more accurately recorded historically than information on exposure determinants in a particular industry.

Vermeulen, R; Kromhout, H

2005-01-01

233

Task performance in astronomical adaptive optics  

NASA Astrophysics Data System (ADS)

In objective or task-based assessment of image quality, figures of merit are defined by the performance of some specific observer on some task of scientific interest. This methodology is well established in medical imaging but is just beginning to be applied in astronomy. In this paper we survey the theory needed to understand the performance of ideal or ideal-linear (Hotelling) observers on detection tasks with adaptive-optical data. The theory is illustrated by discussing its application to detection of exoplanets from a sequence of short-exposure images.

Barrett, Harrison H.; Myers, Kyle J.; Devaney, Nicholas; Dainty, J. C.; Caucci, Luca

2006-07-01

234

Task-level imitation learning using variance-based movement optimization  

Microsoft Academic Search

Recent advances in the field of humanoid robotics increase the complexity of the tasks that such robots can perform. This makes it increasingly difficult and inconvenient to program these tasks manually. Furthermore, humanoid robots, in contrast to industrial robots, should in the distant future behave within a social environment. Therefore, it must be possible to extend the robot's abilities in

Manuel Mühlig; Michael Gienger; Sven Hellbach; Jochen J. Steil; Christian Goerick

2009-01-01

235

The Impact of Planning Time on Children's Task-Based Interactions  

ERIC Educational Resources Information Center

Recently, tasks have been advocated for their role in promoting participation in L2 interaction and the provision and use of feedback by language learners (Bygate, M., Skehan, P., Swain, M. (Eds.), 2001. "Researching Pedagogical Tasks: Second Language Learning, Teaching and Testing." Pearson Education, Harlow). The relationship between various…

Philp, Jenefer; Oliver, Rhonda; Mackey, Alison

2006-01-01

236

Lunar surface construction and assembly equipment study: Lunar Base Systems Study (LBSS) task 5.3  

NASA Technical Reports Server (NTRS)

A set of construction and assembly tasks required on the lunar surface was developed, different concepts for equipment applicable to the tasks determined, and leading candidate systems identified for future conceptual design. Data on surface construction and assembly equipment systems are necessary to facilitate an integrated review of a complete lunar scenario.

1988-01-01

237

Imprecise SPARQL: Towards a Unified Framework for Similarity-Based Semantic Web Tasks  

Microsoft Academic Search

This proposal explores a unifled framework to solve Semantic Web tasks that often require similarity measures, such as RDF retrieval, ontology alignment, and semantic service matchmaking. Our aim is to see how far it is possible to integrate user-deflned similarity functions (UDSF) into SPARQL to achieve good results for these tasks. We present some research questions, summarize the experimental work

Christoph Kiefer

2007-01-01

238

Machine Learning Based Online Performance Prediction for Runtime Parallelization and Task Scheduling  

SciTech Connect

With the emerging many-core paradigm, parallel programming must extend beyond its traditional realm of scientific applications. Converting existing sequential applications as well as developing next-generation software requires assistance from hardware, compilers and runtime systems to exploit parallelism transparently within applications. These systems must decompose applications into tasks that can be executed in parallel and then schedule those tasks to minimize load imbalance. However, many systems lack a priori knowledge about the execution time of all tasks to perform effective load balancing with low scheduling overhead. In this paper, we approach this fundamental problem using machine learning techniques first to generate performance models for all tasks and then applying those models to perform automatic performance prediction across program executions. We also extend an existing scheduling algorithm to use generated task cost estimates for online task partitioning and scheduling. We implement the above techniques in the pR framework, which transparently parallelizes scripts in the popular R language, and evaluate their performance and overhead with both a real-world application and a large number of synthetic representative test scripts. Our experimental results show that our proposed approach significantly improves task partitioning and scheduling, with maximum improvements of 21.8%, 40.3% and 22.1% and average improvements of 15.9%, 16.9% and 4.2% for LMM (a real R application) and synthetic test cases with independent and dependent tasks, respectively.

Li, J; Ma, X; Singh, K; Schulz, M; de Supinski, B R; McKee, S A

2008-10-09

239

Integration of a task knowledge base and a cooperative maneuvering system for the telerobot `MEISTER'  

Microsoft Academic Search

This paper describes the MEISTER (Model Enhanced Intelligent and Skilful TEleRobot) system, which integrates task oriented object models, and cooperative maneuvering system to realize cooperation between man and robot at both the intelligent and motion levels. The object models contain knowledge for executing tasks in unstructured environments with flexibility and robustness through the man\\/robot cooperation at the intelligent level. The

S. Hirai; T. Sato; T. Matsui; M. Kakikura

1990-01-01

240

Reliability-based optimal task-allocation in distributed-database management systems  

Microsoft Academic Search

A distributed database management system (DDBMS) manages a collection of data stored at various processing nodes of a computer network. Global queries are processed by DDBMS, and tasks (join operations in these queries) are assigned to various nodes in the network. Optimal allocation of these tasks are discussed, with reliability as the objective function and communication-cost as the constraint function.

Ajit Kumar Verma; Mangesh Trimbak Tamhankar

1997-01-01

241

Issues in evolving GP based classifiers for a pattern recognition task  

Microsoft Academic Search

This paper discusses issues when evolving genetic programming (GP) classifiers for a pattern recognition task such as handwritten digit recognition. Developing elegant solutions for handwritten digit classification is a challenging task. Similarly, design and training of classifiers using genetic programming is a relatively new approach in pattern recognition as compared to other traditional techniques. Several strategies for GP training are

Ankur M. Teredesai; Venu Govindaraju

2004-01-01

242

Windowed correlation: a suitable tool for providing dynamic fMRI-based functional connectivity neurofeedback on task difficulty.  

PubMed

The goal of neurofeedback training is to provide participants with relevant information on their ongoing brain processes in order to enable them to change these processes in a meaningful way. Under the assumption of an intrinsic brain-behavior link, neurofeedback can be a tool to guide a participant towards a desired behavioral state, such as a healthier state in the case of patients. Current research in clinical neuroscience regarding the most robust indicators of pathological brain processes in psychiatric and neurological disorders indicates that fMRI-based functional connectivity measures may be among the most important biomarkers of disease. The present study therefore investigated the general potential of providing fMRI neurofeedback based on functional correlations, computed from short-window time course data at the level of single task periods. The ability to detect subtle changes in task performance with block-wise functional connectivity measures was evaluated based on imaging data from healthy participants performing a simple motor task, which was systematically varied along two task dimensions representing two different aspects of task difficulty. The results demonstrate that fMRI-based functional connectivity measures may provide a better indicator for an increase in overall (motor) task difficulty than activation level-based measures. Windowed functional correlations thus seem to provide relevant and unique information regarding ongoing brain processes, which is not captured equally well by standard activation level-based neurofeedback measures. Functional connectivity markers, therefore, may indeed provide a valuable tool to enhance and monitor learning within an fMRI neurofeedback setup. PMID:24465794

Zilverstand, Anna; Sorger, Bettina; Zimmermann, Jan; Kaas, Amanda; Goebel, Rainer

2014-01-01

243

Sunlight Exposure and Breast Density: A Population-Based Study  

PubMed Central

Purpose This study aims to assess the association of sunlight exposure with breast cancer risk, measured by the breast density assessed from Tabár's mammographic pattern in Chinese women. Methods A total of 676 premenopausal women were recruited to participate in this study, in which 650 completed a validated sunlight exposure questionnaire via telephone. The mammograms were classified according to Tabár's classification for parenchyma, and patterns IV & V and I, II & III indicated respectively high and low risk mammographic patterns for breast cancer. The odds ratios (OR) and 95% confidence intervals (CIs) for sun exposure-related variables were estimated using unconditional logistic regression with adjustment for potential confounders. Results Among 646 participants, women with high breast cancer risk (Tabár's patterns IV &V) had less hours spent in the sun than those with low risk (I, II & III) at any age stage. A higher level of sunlight exposure was associated with a significantly lower risk having high risk Tabár's pattern. Women aged 40 to 44 years who were in the highest tertile of lifetime total hours spent in the sun had a multi-adjusted OR of 0.41 (95% CI, 0.18-0.92; p for trend=0.03) compared with those in the lowest tertile (>2.19 hr/day vs. <1.32 hr/day). For hours spent in the sun across the ages of 6 to 12 years, the comparable OR was 0.37 (95% CI, 0.15-0.91; p for trend=0.03). Conclusion These findings suggest that higher sunlight exposure is related to a lower risk of having high risk breast density pattern in premenopausal women. Our results also suggest the most relevant period of exposure is during earlier life.

Wu, Sheng-Hui; So, Edwin; Lam, Tsz-ping; Woo, Jean; Yuen, PY; Qin, Ling; Ku, Susanna

2013-01-01

244

A task-based analysis of machinery entanglement injuries among Western Canadian farmers.  

PubMed

Machinery entanglements are a leading cause of hospitalized injury on Canadian farms. This study evaluates the role farm tasks play in the occurrence of machinery entanglement events. A retrospective case series of 41 entanglement injuries involving 35 farm-machinery types was assembled. Only a few limited tasks were implicated in the majority of entanglements. These tasks were as follows: (1) field adjustments of machinery; (2) product handling and conveyance; and (3) driveline attachments and servicing. Hazards inherent and common to these tasks affected the behavior of farmers, leading to entanglements. This study establishes a need to identify hazards and assess risks associated with different tasks involving the use of farm machinery under actual field situations. Systemic changes are required to improve existing machinery safety practices through engineering, work methods, and work practice modifications. In addition to design solutions, occupational health and safety strategies should consider activities associated with hazardous situations to inform the content of injury prevention efforts. PMID:21958400

Narasimhan, Gopinath; Crowe, Trever G; Peng, Yingwei; Hagel, Louise; Dosman, James; Pickett, William

2011-10-01

245

Community-based rehabilitation programme as a model for task-shifting.  

PubMed

This article explores some of the implications of a non-governmental organisation (NGO) initiated community-based rehabilitation (CBR) programme, for HIV-related task-shifting programmes which have been recommended by the World Health Organisation (WHO) as an important aspect of HIV prevention, treatment and care programmes. The CBR programme is run by multi-skilled community rehabilitation facilitators (CRFs) in a low income, rural context in KwaZulu-Natal, South Africa, and explicitly recognises the multiple facets of disability. As such, the programme focuses on both the physical and social aspects of living with disabilities. A qualitative approach was used to conduct this study, and semi-structured interviews were conducted with beneficiaries of the programme (n?=?35), home and community-based care givers (HCBCs) (n?=?13), and managers (n?=?2). A focus group discussion was conducted with CRFs (n?=?5). We found that the CBR programme successfully delivered rehabilitation services at a community level and that multi-skilled CRFs are an effective means of implementing CBR programmes in low-income rural areas. The developmental focus of the programme created a range of benefits for people with disabilities, including: physical rehabilitation, emotional support and counselling, access to grants, social inclusion and accessing assistive devices. Central to the programme's success was the maintenance of relationships and partnerships at different levels in the community, these included relationships between HCBCs and CRFs, between CRFs and therapists, and between the NGO and the various participants in the programme. However, the NGO struggled to maintain a partnership with the relevant government departments and this had important implications for the programmes sustainability. In conclusion, we argue that this programme's use of multi-skilled mid-level workers who have undergone effective training programmes in CBR demonstrates that a wide range of rehabilitation activities can be effectively undertaken at a community level, and that this programme provides an important example of how the WHO's task-shifting guidelines for HIV treatment, care and prevention can be implemented. PMID:21291340

Dawad, Suraya; Jobson, Geoff

2011-01-01

246

Advanced Exposure Metrics For Chemical Risk Analysis: Systems Biology and 'Omic-based Biomarkers for Exposure Reconstruction  

EPA Science Inventory

Direct measurement of human exposure to environmental contaminants in real time (when the exposure is actually occurring) is rare and difficult to obtain. This frustrates both exposure assessments and investigations into the linkage between chemical exposure and human disease. ...

247

PHARMACOKINETICALLY BASED RISK ASSESSMENT OF WORKPLACE EXPOSURE OF BENZENE  

EPA Science Inventory

Cancer risk from exposure to benzene for a working lifetime was estimated from data obtained in studies with rodents. ancers of the Zymbal gland and the blood-forming system were selected as endpoints for the assessment because of their consistent occurrence. he combined metaboli...

248

Defense Science Board Task Force on the review of the Defense Nuclear Agency technology base program. Final report  

SciTech Connect

The purpose of this Defense Science Board Task Force review was to examine DNA's responsiveness to DoD needs and the appropriateness of its emphasis on emerging technologies, and to evaluate the relationships between DNA and Dept. of Energy laboratories, private consultants, university participants and Service users. The Task Force also addressed important technical and management issues confronting DNA. The Task Force concluded that DNA has been responsive to DoD needs, although the technology base program has a few specific areas of weakness. The Task Force expressed support of recent DNA initiatives to assign greater priority to the survivability of Theater Nuclear Forces and their associated C3. Also emphasized were the importance of underground nuclear explosion testing and the need for a review of several questions left unanswered by the ban on atmospheric testing. Principal Task Force recommendations include: 1) Resources provided to the DNA technology base longer-term programs should not be diverted into more-pressing short-term projects; 2) Relationships between DNA and other DoD and DoE laboratories should be strengthened by exchange programs of technical personnel; and 3) Technology transfer between DNA and the Services and the CINCs should be improved by annual reviews of user requirements and joint funding of projects where appropriate.

Not Available

1982-04-01

249

Exposure to indoor tanning in France: a population based study  

PubMed Central

Background Tanning lamp sessions have increased in Europe in recent years. Recent epidemiological studies have confirmed a proven link between melanoma and artificial UV exposure. However, in France, little information is available to determine the exposure of the population. This article presents the results from the ‘Baromètre cancer 2010’ concerning the proportion of users exposed to artificial UV radiation in France, their characteristics and level of information on the risks associated. Methods A two stage random sampling telephone survey assisted by CATI system (household, individual) was performed from 3 April 2010 to 7 August 2010 on a sample of 3,359 people aged 15 to 75 years old. Results In 2010, 13.4% of the French population reported to have tanning lamp sessions at least once in their lifetime and 3.5% of the total population reported the use of artificial UV radiation over the last twelve months. Exposure over the last twelve months is most commonly seen among females (5.0%) and young population between 20–25 years old (9.6%). In addition, 3.5% of those under 18 years report having attended UV booths at least once during their lifetime even though they are forbidden to minors. Moreover, more than one the third of users reported more than 10 exposures within a year. The places of exposure cited most often were beauty salons (50%) and tanning centers (46%). Only 49.2% of those surveyed felt that they were well informed on the risks of cancer associated with UV booths. Furthermore, the population was found to have misconceptions about artificial UV radiation. One quarter of the population, believe that artificial UV radiation use before vacation protects the skin from sunburn. Conclusions This first study on artificial UV radiation exposure in France has better quantified and characterized the users. It has also defined the state of knowledge and the perception of risk by the general French population. This work will contribute to determine actions of prevention to reduce cancer risk related to artificial UV radiation.

2013-01-01

250

Building Task-Based User Interfaces with ANSI\\/CEA2018  

Microsoft Academic Search

The recently approved ANSI\\/CEA-2018 standard is motivated by the current usability crisis in computer controlled electronic products. The standard facilitates a new user interface design methodology that uses a task model at runtime to guide users.

Charles Rich

2009-01-01

251

Simulator-Based Study of Human Errors in Nuclear Power Plant Control Room Tasks.  

National Technical Information Service (NTIS)

The purposes of this study were to empirically establish error rates for control selection and operation during the performance of proceduralized tasks in nuclear power plant control rooms during simulated casualties, and to compare the observed error rat...

A. N. Beare R. E. Dorris C. R. Bovell D. S. Crowe E. J. Kozinsky

1984-01-01

252

An Immune-based Genetic Algorithm with Reduced Search Space Coding for Multiprocessor Task Scheduling Problem  

Microsoft Academic Search

Multiprocessor task scheduling is an important problem in parallel applications and distributed systems. In this way, solving\\u000a the multiprocessor task scheduling problem (MTSP) by heuristic, meta-heuristic, and hybrid algorithms have been proposed in literature. Although the problem has been addressed\\u000a by many researchers, challenges to improve the convergence speed and the reliability of methods for solving the problem are\\u000a still

Mohsen Ebrahimi Moghaddam; Mohammad Reza Bonyadi

253

Enabling Dynamic Process Simulators to Perform Alternative Tasks: A Time-stepper Based Toolkit for Computer-Aided Analysis  

Microsoft Academic Search

We discuss computational superstructures that, using repeated, appropriately initialized short calls, enable temporal process simulators to perform alternative tasks such as fixed point computation, stability analysis and projective integration. We illustrate these concepts through the acceleration of a gPROMS-based Rapid Pressure Swing Adsorption simulation, and discuss their scope and possible extensions.

C. I. Siettos; C. C. Pantelides; I. G. Kevrekidis

2003-01-01

254

A Novel Set-Shifting Modification of the Iowa Gambling Task: Flexible Emotion-Based Learning in Schizophrenia  

Microsoft Academic Search

Although it might seem that people with schizophrenia would perform poorly on measures of emotion-based learning, several studies have shown normal levels of performance on the Iowa Gambling Task (IGT; C. E. Y. Evans, C. H. Bowman, & O. H. Turnbull, 2005; L. M. Ritter, J. H. Meador-Woodruff, & G. W. Dalack, 2004; B. Shurman, W. P. Horan, & K.

Oliver H. Turnbull; Cathryn E. Y. Evans; Karen Kemish; Sohee Park; Caroline H. Bowman

2006-01-01

255

Thinking Together: Exploring Aspects of Shared Thinking between Young Children during a Computer-Based Literacy Task  

ERIC Educational Resources Information Center

This study considers in what ways sustained shared thinking between young children aged 5-6 years can be facilitated by working in dyads on a computer-based literacy task. The study considers 107 observational records of 44 children from 6 different schools, in Oxfordshire in the UK, collected over the course of a school year. The study raises…

Wild, Mary

2011-01-01

256

A Location-Based Prompting System to Transition Autonomously through Vocational Tasks for Individuals with Cognitive Impairments  

ERIC Educational Resources Information Center

This study assessed the possibility of training two individuals with cognitive impairments using location-based task prompting system in a supported employment program. This study was carried out according to an ABAB sequence in which A represented the baseline and B represented intervention phases. Data showed that the two participants…

Chang, Yao-Jen; Wang, Tsen-Yung; Chen, Yan-Ru

2011-01-01

257

On the Relationship Between Effort Toward an Ongoing Task and Cue Detection in Event-Based Prospective Memory  

ERIC Educational Resources Information Center

In recent theories of event-based prospective memory, researchers have debated what degree of resources are necessary to identify a cue as related to a previously established intention. In order to simulate natural variations in attention, the authors manipulated effort toward an ongoing cognitive task in which intention-related cues were embedded…

Marsh, Richard L.; Hicks, Jason L.; Cook, Gabriel I.

2005-01-01

258

Reading Guided by Automated Graphical Representations: How Model-Based Text Visualizations Facilitate Learning in Reading Comprehension Tasks  

ERIC Educational Resources Information Center

Our study integrates automated natural language-oriented assessment and analysis methodologies into feasible reading comprehension tasks. With the newly developed T-MITOCAR toolset, prose text can be automatically converted into an association net which has similarities to a concept map. The "text to graph" feature of the software is based on…

Pirnay-Dummer, Pablo; Ifenthaler, Dirk

2011-01-01

259

Paleoglaciation of the Tibetan Plateau based on exposure ages and ELA depression estimates  

NASA Astrophysics Data System (ADS)

The Tibetan Plateau holds a major part of all glaciers outside the polar regions and an ample record of past glaciations. The glacial history of the Tibetan Plateau has attracted significant interest, with a large body of research investigating the extent, timing, and climatic implications of past glaciations. Here I present an extensive compilation of exposure ages and equilibrium line altitude (ELA) depression estimates from glacial deposits across the Tibetan Plateau to address the timing and degree of past glaciations. I compiled Be-10 exposure age data for a total of 1877 samples and recalculated exposure ages using an updated (lower) global Be-10 production rate. All samples were organized in groups of individual glacial deposits where each deposit represents one glacial event enabling evaluation of the exposure age clustering. For each glacial deposit I estimated the ELA depression based on a simple toe to headwall ratio approach using Google Earth. To discriminate good (well-clustered) from poor (scattered) exposure age groups the glacial deposits were divided into three groups based on exposure age clustering. A major part of the glacial deposits have scattered exposure ages affected by prior or incomplete exposure, complicating exposure age interpretations. The well-clustered exposure age groups are primarily from mountain ranges along the margins of the Tibetan Plateau with a main peak in age between 10 and 30 ka, indicating glacial advances during the global last glacial maximum (LGM). A large number of exposure ages older than 30 ka indicates maximum glaciation predating the LGM, but the exposure age scatter generally prohibits accurate definition of the glacial chronology. The ELA depression estimates scatter significantly, but a major part is remarkably low. Average ELA depressions of 333 ± 191 m for the LGM and 494 ± 280 m for the pre-LGM exposure indicate restricted glacier expansion and limited glacial cooling.

Heyman, Jakob

2014-05-01

260

Using a physiologically based pharmacokinetic model to link urinary biomarker concentrations to dietary exposure of perchlorate  

EPA Science Inventory

Exposure to perchlorate is widespread in the United States and many studies have attempted to character the perchlorate exposure by estimating the average daily intakes of perchlorate. These approaches provided population-based estimates, but did not provide individual-level exp...

261

EPA-Expo-Box: A web-based Toolbox for Exposure Assessors  

EPA Science Inventory

EPA EXPOsure toolBOX, or EPA-Expo-Box, is a web-based toolbox that has been developed by EPA’s Office of Research and Development (ORD), National Center for Environmental Assessment (NCEA). It is intended for exposure and risk assessors and it comprises a series of Tool Set...

262

A Comparison of Exposure Control Procedures in CAT Systems Based on Different Measurement Models for Testlets  

ERIC Educational Resources Information Center

This study compared several exposure control procedures for CAT systems based on the three-parameter logistic testlet response theory model (Wang, Bradlow, & Wainer, 2002) and Masters' (1982) partial credit model when applied to a pool consisting entirely of testlets. The exposure control procedures studied were the modified within 0.10 logits…

Boyd, Aimee M.; Dodd, Barbara; Fitzpatrick, Steven

2013-01-01

263

Determination of Occupational Exposure to Depleted Uranium Based on Inductively Coupled Plasma Mass Spectrometry.  

National Technical Information Service (NTIS)

We used a simple method based on inductively coupled plasma mass spectrometry (ICP-MS) to determine the isotopic composition of uranium in urine at levels that indicate occupational exposure to depleted uranium (DU). DU exposure is indicated by a range fo...

P. R. Boyd, R. W. Tardiff, J. W. Ejnik, A. J. Carmichael, M. M. Hamiliton

2000-01-01

264

Comparative evaluation of twenty pilot workload assessment measure using a psychomotor task in a moving base aircraft simulator  

NASA Technical Reports Server (NTRS)

A comparison of the sensitivity and intrusion of twenty pilot workload assessment techniques was conducted using a psychomotor loading task in a three degree of freedom moving base aircraft simulator. The twenty techniques included opinion measures, spare mental capacity measures, physiological measures, eye behavior measures, and primary task performance measures. The primary task was an instrument landing system (ILS) approach and landing. All measures were recorded between the outer marker and the middle marker on the approach. Three levels (low, medium, and high) of psychomotor load were obtained by the combined manipulation of windgust disturbance level and simulated aircraft pitch stability. Six instrument rated pilots participated in four seasons lasting approximately three hours each.

Connor, S. A.; Wierwille, W. W.

1983-01-01

265

Paleoglaciation of the Tibetan Plateau and surrounding mountains based on exposure ages and ELA depression estimates  

NASA Astrophysics Data System (ADS)

The Tibetan Plateau holds an ample record of past glaciations, and there is an extensive set of glacial deposits dated by exposure dating. Here a compilation is presented of 10Be exposure ages from 485 glacial deposits with 1855 individual samples on the Tibetan Plateau, and ELA depression estimates for the glacial deposits based on a simple toe to headwall ratio approach. To recalculate the Tibetan Plateau exposure ages, 10Be production rates from 24 calibration sites across the world are compiled and recalibrated yielding an updated global reference 10Be production rate. The recalculated exposure ages from the Tibetan Plateau glacial deposits are then divided into three groups based on exposure age clustering, to discriminate good (well-clustered) from poor (scattered) deglaciation ages. A major part of the glacial deposits have exposure ages affected by prior or incomplete exposure, complicating exposure age interpretations. The well-clustered deglaciation ages are primarily from mountain ranges along the margins of the Tibetan Plateau with a main peak between 10 and 30 ka, indicating glacial advances during the global LGM. A large number of deglaciation ages older than 30 ka indicates maximum glaciation predating the LGM, but the exposure age scatter generally prohibits accurate definition of the glacial chronology. The ELA depression estimates scatter significantly, but the main part is remarkably low. Average ELA depressions of 337 ± 197 m for the LGM and 494 ± 280 m for the pre-LGM indicate restricted glacier expansion.

Heyman, Jakob

2014-05-01

266

Cooperative Scheduling of Imaging Observation Tasks for High-Altitude Airships Based on Propagation Algorithm  

PubMed Central

The cooperative scheduling problem on high-altitude airships for imaging observation tasks is discussed. A constraint programming model is established by analyzing the main constraints, which takes the maximum task benefit and the minimum cruising distance as two optimization objectives. The cooperative scheduling problem of high-altitude airships is converted into a main problem and a subproblem by adopting hierarchy architecture. The solution to the main problem can construct the preliminary matching between tasks and observation resource in order to reduce the search space of the original problem. Furthermore, the solution to the sub-problem can detect the key nodes that each airship needs to fly through in sequence, so as to get the cruising path. Firstly, the task set is divided by using k-core neighborhood growth cluster algorithm (K-NGCA). Then, a novel swarm intelligence algorithm named propagation algorithm (PA) is combined with the key node search algorithm (KNSA) to optimize the cruising path of each airship and determine the execution time interval of each task. Meanwhile, this paper also provides the realization approach of the above algorithm and especially makes a detailed introduction on the encoding rules, search models, and propagation mechanism of the PA. Finally, the application results and comparison analysis show the proposed models and algorithms are effective and feasible.

Chuan, He; Dishan, Qiu; Jin, Liu

2012-01-01

267

38 CFR 3.316 - Claims based on chronic effects of exposure to mustard gas and Lewisite.  

Code of Federal Regulations, 2010 CFR

...false Claims based on chronic effects of exposure to mustard gas and Lewisite. 3.316 Section 3.316 Pensions...316 Claims based on chronic effects of exposure to mustard gas and Lewisite. (a) Except as provided in...

2010-07-01

268

38 CFR 3.316 - Claims based on chronic effects of exposure to mustard gas and Lewisite.  

Code of Federal Regulations, 2010 CFR

...false Claims based on chronic effects of exposure to mustard gas and Lewisite. 3.316 Section 3.316 Pensions...316 Claims based on chronic effects of exposure to mustard gas and Lewisite. (a) Except as provided in...

2009-07-01

269

Feasibility of performing space surveillance tasks with a proposed space-based optical architecture  

NASA Astrophysics Data System (ADS)

Under ESA contract an industrial consortium including Aboa Space Research Oy (ASRO), the Astronomical Institute of the University of Bern (AIUB), and the Dutch National Aerospace Laboratory (NLR), proposed the observation concept, developed a suitable sensor architecture, and assessed the performance of a space-based optical (SBO) telescope in 2005. The goal of the SBO instrumentation was to analyse how the existing knowledge gap in the space debris population in the millimetre and centimetre regime may be closed by means of a passive op-tical instrument. SBO was requested to provide statistical information on the space debris population, in terms of number of objects and size distribution. The SBO was considered to be a cost-efficient instrumentation of 20 cm aperture and 6 deg field-of-view with flexible integration requirements. It should be possible to integrate the SBO easily as a secondary payload on satellites launched into low-Earth orbits (LEO), or into geostationary orbit (GEO). Thus the selected mission concept only allowed for fix-mounted telescopes, and the pointing direction could be requested freely. It was shown in the performance analysis that the statistical information on small-sized space debris can only be collected if the observation ranges are comparatively small. Two of the most promising concepts were to observe objects in LEO from a sensor placed into a sun-synchronous LEO, while objects in GEO should be observed from a GEO satellite. Since 2007 ESA focuses space surveillance and tracking activities in the Space Situational Awareness (SSA) preparatory program. Ground-based radars and optical telescopes are stud-ied for the build-up and to maintenance of a catalogue of objects. In this paper we analyse how the SBO architecture could contribute to the space surveillance tasks survey and tracking. We assume that the SBO instrumentation is placed into a circular sun-synchronous orbit at 800 km altitude. We discuss the observation conditions of objects at higher altitude, such as GEO and Medium-Earth Orbits (MEO). Of particular interest are the radiometric performance from which we derive the detectable object diameters, the coverage of a reference population, and the covered arc lengths of individual objects. The latter is of particular interest for the simu-lation of the orbit determination, correlation, and cataloguing. Assuming realistic noise levels known from the SBO design we simulate first orbit determination of unknown objects (surveys) and orbit improvements (tracking) for sample objects. We use a simulation environment that comprises the ESA Program for Radar and Optical Observation Forecasting (PROOF) in the version 2005 and AIUB's program system CelMech. ESA's MASTER-2005 serves as reference population for all analyses.

Flohrer, Tim; Krag, Holger; Klinkrad, Heiner; Schildknecht, Thomas

270

Task-based evaluation of segmentation algorithms for diffusion-weighted MRI without using a gold standard  

PubMed Central

In many studies, the estimation of the apparent diffusion coefficient (ADC) of lesions in visceral organs in diffusion-weighted (DW) magnetic resonance images requires an accurate lesion-segmentation algorithm. To evaluate these lesion-segmentation algorithms, region-overlap measures are used currently. However, the end task from the DW images is accurate ADC estimation, and the region-overlap measures do not evaluate the segmentation algorithms on this task. Moreover, these measures rely on the existence of gold-standard segmentation of the lesion, which is typically unavailable. In this paper, we study the problem of task-based evaluation of segmentation algorithms in DW imaging in the absence of a gold standard. We first show that using manual segmentations instead of gold-standard segmentations for this task-based evaluation is unreliable. We then propose a method to compare the segmentation algorithms that does not require gold-standard or manual segmentation results. The no-gold-standard method estimates the bias and the variance of the error between the true ADC values and the ADC values estimated using the automated segmentation algorithm. The method can be used to rank the segmentation algorithms on the basis of both accuracy and precision. We also propose consistency checks for this evaluation technique.

Jha, Abhinav K.; Kupinski, Matthew A.; Rodriguez, Jeffrey J.; Stephen, Renu M.; Stopeck, Alison T.

2012-01-01

271

Designing simulator-based training: an approach integrating cognitive task analysis and four-component instructional design.  

PubMed

Most studies of simulator-based surgical skills training have focused on the acquisition of psychomotor skills, but surgical procedures are complex tasks requiring both psychomotor and cognitive skills. As skills training is modelled on expert performance consisting partly of unconscious automatic processes that experts are not always able to explicate, simulator developers should collaborate with educational experts and physicians in developing efficient and effective training programmes. This article presents an approach to designing simulator-based skill training comprising cognitive task analysis integrated with instructional design according to the four-component/instructional design model. This theory-driven approach is illustrated by a description of how it was used in the development of simulator-based training for the nephrostomy procedure. PMID:23088360

Tjiam, Irene M; Schout, Barbara M A; Hendrikx, Ad J M; Scherpbier, Albert J J M; Witjes, J Alfred; van Merriënboer, Jeroen J G

2012-01-01

272

Designing a Third-Year German Course for a Content-Oriented, Task-Based Curriculum.  

ERIC Educational Resources Information Center

Responding to the gap between language and content that prevails in most foreign language departments, discusses the reconceptualization of third-year German in the curricular reform at Georgetown University. Comments on the concept of "task" that guided the reform and outlines the design of the new advanced course, discusses one course module in…

Eigler, Friederike

2001-01-01

273

Classroom-Based Functional Analysis and Intervention for Disruptive and Off-Task Behaviors  

ERIC Educational Resources Information Center

Although there is a growing body of literature on the use of functional analysis in schools, there is a need for more demonstrations of this technology being used during the course of typical instruction. In this study, we conducted functional analyses of disruptive and off-task behavior in a reading classroom setting for 3 participants of typical…

Shumate, Emily D.; Wills, Howard P.

2010-01-01

274

Task based approach on trajectory planning with redundant manipulators, and its application to wheelchair propulsion  

Microsoft Academic Search

We introduce an optimization method for the trajectory planning of redundant manipulators which achieve a given task with high efficiency, and apply the method to a wheelchair propulsion problem. A GA is used to optimize the redundant variables of a manipulator. Additionally, the procedure of the method does not use any forward dynamics computation. The effectiveness of the proposed algorithm

Hiroki Miura; Goro Obinata; Atsushi Nakayama; K. Hase; Makoto Sasaki; Takehiro Iwami; H. Doki

2004-01-01

275

The Effects of Learning Style and Task Type on Hypermedia-Based Mental Models.  

ERIC Educational Resources Information Center

Investigates the effects of context-weak versus context-strong tasks and learning style on the citation-frequencies and citation-percentages of four mental models (semantic networks, concept maps, frames/scripts, and schemata) students perceived to be inherent in a hypermedia learning environment. (Author/AEF)

Reed, W. Michael; Ayersman, David J.; Kraus, Lee A.

1997-01-01

276

Learning Effects in the Block Design Task: A Stimulus Parameter-Based Approach  

ERIC Educational Resources Information Center

Learning effects were assessed for the block design (BD) task, on the basis of variation in 2 stimulus parameters: perceptual cohesiveness (PC) and set size uncertainty (U). Thirty-one nonclinical undergraduate students (19 female) each completed 3 designs for each of 4 varied sets of the stimulus parameters (high-PC/high-U, high-PC/low-U,…

Miller, Joseph C.; Ruthig, Joelle C.; Bradley, April R.; Wise, Richard A.; Pedersen, Heather A.; Ellison, Jo M.

2009-01-01

277

Evolution-Based Virtual Training in Extracting Fuzzy Knowledge for Deburring Tasks  

Microsoft Academic Search

In this research, the problems of how to teach a robot to execute skilled opera- tions are studied. Human workers usually accumulate their experience after execut- ing the same task repetitively. In the process of training, a worker needs to find ways of adjusting his\\/her execution. In our system, the parameters for an impedance con- trol scheme are considered as

Shun-feng Su; Ta-jyh Horng; Kuu-young Young

2000-01-01

278

Text, Graphics, and Multimedia Materials Employed in Learning a Computer-Based Procedural Task  

ERIC Educational Resources Information Center

The present research study investigated the interaction of graphic design students with different forms of software training materials. Four versions of the procedural task instructions were developed (A) Traditional Textbook with Still Images, (B) Modified Text with Integrated Still Images, (C) Onscreen Modified Text with Silent Onscreen Video…

Coffindaffer, Kari Christine Carlson

2010-01-01

279

Task Importance Affects Event-Based Prospective Memory Performance in Adults with HIV-Associated Neurocognitive Disorders and HIV-Infected Young Adults with Problematic Substance Use.  

PubMed

Two experiments were conducted to examine the effects of task importance on event-based prospective memory (PM) in separate samples of adults with HIV-associated neurocognitive disorders (HAND) and HIV-infected young adults with substance use disorders (SUD). All participants completed three conditions of an ongoing lexical decision task: (1) without PM task requirements; (2) with PM task requirements that emphasized the importance of the ongoing task; and (3) with PM task requirements that emphasized the importance of the PM task. In both experiments, all HIV+ groups showed the expected increase in response costs to the ongoing task when the PM task's importance was emphasized. In Experiment 1, individuals with HAND showed significantly lower PM accuracy as compared to HIV+ subjects without HAND when the importance of the ongoing task was emphasized, but improved significantly and no longer differed from HIV+ subjects without HAND when the PM task was emphasized. A similar pattern of findings emerged in Experiment 2, whereby HIV+ young adults with SUD (especially cannabis) showed significant improvements in PM accuracy when the PM task was emphasized. Findings suggest that both HAND and SUD may increase the amount of cognitive attentional resources that need to be allocated to support PM performance in persons living with HIV infection. (JINS, 2014, 21, 1-11). PMID:24834469

Woods, Steven Paul; Doyle, Katie L; Morgan, Erin E; Naar-King, Sylvie; Outlaw, Angulique Y; Nichols, Sharon L; Loft, Shayne

2014-07-01

280

Theory-based training strategies for modifying practitioner concerns about exposure therapy.  

PubMed

Despite the well-established efficacy of exposure therapy in the treatment of pathological anxiety, many therapists believe this treatment carries an unacceptably high risk for harm, is intolerable for patients, and poses a number of ethical quandaries. These beliefs have been shown to account for two related problems: (a) underutilization of exposure therapy, and (b) overly cautious and suboptimal delivery the treatment, which likely attenuates treatment outcomes. At present, there is little guidance for those who train exposure therapists to address these concerns. This article reviews therapist negative beliefs about exposure therapy and discusses their modification based on findings from social and cognitive psychology pertinent to belief change, including dual-processing in reasoning, the need for cognition and affect, and attitude inoculation. A number of strategies are offered for augmenting training in exposure therapy in order to promote positive beliefs about the treatment. These strategies involve: (a) therapists engaging in simulated exposure therapy exercises and presenting arguments in defense of exposure's safety, tolerability, and ethicality, and (b) training therapists using emotion-based appeals (e.g., case examples) to supplement research findings. Directions for future research on practitioner concerns about exposure therapy are discussed. PMID:24210013

Farrell, Nicholas R; Deacon, Brett J; Dixon, Laura J; Lickel, James J

2013-12-01

281

Exposure assessment of mobile phone base station radiation in an outdoor environment using sequential surrogate modeling.  

PubMed

Human exposure to background radiofrequency electromagnetic fields (RF-EMF) has been increasing with the introduction of new technologies. There is a definite need for the quantification of RF-EMF exposure but a robust exposure assessment is not yet possible, mainly due to the lack of a fast and efficient measurement procedure. In this article, a new procedure is proposed for accurately mapping the exposure to base station radiation in an outdoor environment based on surrogate modeling and sequential design, an entirely new approach in the domain of dosimetry for human RF exposure. We tested our procedure in an urban area of about 0.04?km(2) for Global System for Mobile Communications (GSM) technology at 900?MHz (GSM900) using a personal exposimeter. Fifty measurement locations were sufficient to obtain a coarse street exposure map, locating regions of high and low exposure; 70 measurement locations were sufficient to characterize the electric field distribution in the area and build an accurate predictive interpolation model. Hence, accurate GSM900 downlink outdoor exposure maps (for use in, e.g., governmental risk communication and epidemiological studies) are developed by combining the proven efficiency of sequential design with the speed of exposimeter measurements and their ease of handling. PMID:23315952

Aerts, Sam; Deschrijver, Dirk; Joseph, Wout; Verloock, Leen; Goeminne, Francis; Martens, Luc; Dhaene, Tom

2013-05-01

282

Conflict tasks and the diffusion framework: Insight in model constraints based on psychological laws.  

PubMed

Formal models of decision-making have traditionally focused on simple, two-choice perceptual decisions. To date, one of the most influential account of this process is Ratcliff's drift diffusion model (DDM). However, the extension of the model to more complex decisions is not straightforward. In particular, conflicting situations, such as the Eriksen, Stroop, or Simon tasks, require control mechanisms that shield the cognitive system against distracting information. We adopted a novel strategy to constrain response time (RT) models by concurrently investigating two well-known empirical laws in conflict tasks, both at experimental and modeling levels. The two laws, predicted by the DDM, describe the relationship between mean RT and (i) target intensity (Piéron's law), (ii) standard deviation of RT (Wagenmakers-Brown's law). Pioneering work has shown that Piéron's law holds in the Stroop task, and has highlighted an additive relationship between target intensity and compatibility. We found similar results in both Eriksen and Simon tasks. Compatibility also violated Wagenmakers-Brown's law in a very similar and particular fashion in the two tasks, suggesting a common model framework. To investigate the nature of this commonality, predictions of two recent extensions of the DDM that incorporate selective attention mechanisms were simulated and compared to the experimental results. Both models predict Piéron's law and the violation of Wagenmakers-Brown's law by compatibility. Fits of the models to the RT distributions and accuracy data allowed us to further reveal their relative strengths and deficiencies. Combining experimental and computational results, this study sets the groundwork for a unified model of decision-making in conflicting environments. PMID:24762975

Servant, Mathieu; Montagnini, Anna; Burle, Borís

2014-07-01

283

Too young or too old: Evaluating cosmogenic exposure dating based on an analysis of compiled boulder exposure ages  

NASA Astrophysics Data System (ADS)

Cosmogenic exposure dating has greatly enhanced our ability to define glacial chronologies spanning several global cold periods, and glacial boulder exposure ages are now routinely used to constrain deglaciation ages. However, exposure dating involves assumptions about the geological history of the sample that are difficult to test and yet may have a profound effect on the inferred age. Two principal geological factors yield erroneous inferred ages: exposure prior to glaciation (yielding exposure ages that are too old) and incomplete exposure due to post-depositional shielding (yielding exposure ages that are too young). Here we show that incomplete exposure is more important than prior exposure, using datasets of glacial boulder 10Be exposure ages from the Tibetan Plateau (1420 boulders), Northern Hemisphere palaeo-ice sheets (631 boulders), and present-day glaciers (208 boulders). No boulders from present-day glaciers and few boulders from the palaeo-ice sheets have exposure ages significantly older than independently known deglaciation ages, indicating that prior exposure is of limited significance. Further, while a simple post-depositional landform degradation model can predict the exposure age distribution of boulders from the Tibetan Plateau, a prior exposure model fails, indicating that incomplete exposure is important. The large global dataset demonstrates that, in the absence of other evidence, glacial boulder exposure ages should be viewed as minimum limiting deglaciation ages.

Heyman, Jakob; Stroeven, Arjen P.; Harbor, Jonathan M.; Caffee, Marc W.

2011-02-01

284

Calibrating a population-based job-exposure matrix using inspection measurements to estimate historical occupational exposure to lead for a population-based cohort in Shanghai, China.  

PubMed

The epidemiologic evidence for the carcinogenicity of lead is inconsistent and requires improved exposure assessment to estimate risk. We evaluated historical occupational lead exposure for a population-based cohort of women (n=74,942) by calibrating a job-exposure matrix (JEM) with lead fume (n=20,084) and lead dust (n=5383) measurements collected over four decades in Shanghai, China. Using mixed-effect models, we calibrated intensity JEM ratings to the measurements using fixed-effects terms for year and JEM rating. We developed job/industry-specific estimates from the random-effects terms for job and industry. The model estimates were applied to subjects' jobs when the JEM probability rating was high for either job or industry; remaining jobs were considered unexposed. The models predicted that exposure increased monotonically with JEM intensity rating and decreased 20-50-fold over time. The cumulative calibrated JEM estimates and job/industry-specific estimates were highly correlated (Pearson correlation=0.79-0.84). Overall, 5% of the person-years and 8% of the women were exposed to lead fume; 2% of the person-years and 4% of the women were exposed to lead dust. The most common lead-exposed jobs were manufacturing electronic equipment. These historical lead estimates should enhance our ability to detect associations between lead exposure and cancer risk in the future epidemiologic analyses. PMID:22910004

Koh, Dong-Hee; Bhatti, Parveen; Coble, Joseph B; Stewart, Patricia A; Lu, Wei; Shu, Xiao-Ou; Ji, Bu-Tian; Xue, Shouzheng; Locke, Sarah J; Portengen, Lutzen; Yang, Gong; Chow, Wong-Ho; Gao, Yu-Tang; Rothman, Nathaniel; Vermeulen, Roel; Friesen, Melissa C

2014-01-01

285

Occupational exposure to water based paint and symptoms from the skin and eyes  

Microsoft Academic Search

Water based paints contain organic solvents and many additives, such as biocides, surfactants, pigments, binders, amines, and monomers. The chemical complexity may introduce new potential health hazards to house painters, in particular irritative and allergic disorders. This study was performed to compare how house painters experience work with water based paints or solvent based paints, and to evaluate whether exposure

G Wieslander; D Norbäck; C Edling

1994-01-01

286

The effect of task-based instruction on the acquisition and use of English existential constructions by Iranian EFL learners  

Microsoft Academic Search

This study sought to measure the degree of students' success in learning and proper use of Existential Constructions (ECs), namely there is\\/are, in English as a foreign language through Focus on Form (FonF) techniques in Task-based language teaching. For this purpose, 60 Iranian learners of English were randomly selected and assigned to one experimental and two control groups. Analysis of

Hussein Muhammadi Farsani; Mansour Tavakoli; Ahmad Moinzadeh

2011-01-01

287

The effect of task-based instruction on the acquisition and use of English existential constructions by Iranian EFL learners  

Microsoft Academic Search

This study sought to measure the degree of students’ success in learning and proper use of Existential Constructions (ECs), namely there is\\/are, in English as a foreign language through Focus on Form (FonF) techniques in Task-based language teaching. For this purpose, 60 Iranian learners of English were randomly selected and assigned to one experimental and two control groups. Analysis of

Hussein Muhammadi Farsani; Mansour Tavakoli; Ahmad Moinzadeh

2012-01-01

288

Computer?based problem?solving: the effects of group composition and social skills on a cognitive, joint action task  

Microsoft Academic Search

Research concerning joint action for problem?solving on computer?based tasks in schools shows an increasing awareness that social context factors must be accounted for if cognitive development is to be effective. This study focuses on boys and girls working in single?sex or mixed?sex groups, and training for social skills as context factors and how these foci affect performance at the beginning

Peter Kutnick

1997-01-01

289

Current Processes of the U.S. Preventive Services Task Force: Refining Evidence-Based Recommendation Development  

Microsoft Academic Search

he U.S. Preventive Services Task Force (USPSTF) is an internationally recognized, independent panel of non- federal experts in primary care, prevention, and research methods that makes evidence-based recommendations to guide the delivery of clinical preventive services. Convened and supported by the Agency for Healthcare Research and Quality (AHRQ), the USPSTF is charged by the U.S. Congress to review the scientific

Janelle Guirguis-Blake; Ned Calonge; Therese Miller; Albert Siu; Steven Teutsch; Evelyn Whitlock

290

Hypergraph-based task-bundle scheduling towards efficiency and fairness in heterogeneous distributed systems  

Microsoft Academic Search

This paper investigates scheduling loosely coupled task-bundles in highly heterogeneous distributed systems. Two allocation quality metrics are used in pay-per-service distributed applications: efficiency in terms of social welfare, and fairness in terms of envy-freeness. The first contribution of this work is that we build a unified hypergraph scheduling model under which efficiency and fairness are compatible with each other. Second,

Han Zhao; Xinxin Liu; Xiaolin Li

2010-01-01

291

Odor Based Behavioral Tasks Confounded by Distance Dependent Detection: Modification of a Murine Digging Paradigm  

Microsoft Academic Search

ABSTRACT Tests of murine ,higher order cognition are important in order ,to fully explore the effects of genetic ,alterations and potential therapies in models ,of human mental retardation and other deficits of intellect. In this study, inbred and F1hybrid strains of mice,were assessed in a five odor sequence task previously described,for rats which ,employs ,buried ,food rewards. Data are provided

EMILY KATZ; OLIVER ROTHSCHILD; ANDRIANA HERRERA; SOFIA HUANG; ANNA WONG; YVETTE WOJCIECHOWSKI; AIDA GIL; QI JIANG YAN; ROBERT P. BAUCHWITZ

292

Classification of ECoG motor imagery tasks based on CSP and SVM  

Microsoft Academic Search

This paper mainly studies about the data processing of brain computer interface(BCI) and presents a kind of method for classifying the ECoG motor imagery tasks. Both the training and testing ECoG datasets were filtered with the frequency band of 8-30Hz according to the event-related desynchronization and synchronization(ERD\\/ERS) phenomenon. The features were extracted by using Common Spatial Pattern(CSP) and then the

Chong Liu; Hai-bin Zhao; Chun-sheng Li; Hong Wang

2010-01-01

293

Biomarker-based calibration of retrospective exposure predictions of perfluorooctanoic Acid.  

PubMed

Estimated historical exposures and serum concentrations of perfluorooctanoic acid (PFOA) have been extensively used in epidemiologic studies that examined associations between PFOA exposures and adverse health outcomes among residents in highly exposed areas in the Mid-Ohio Valley. Using measured serum PFOA levels in 2005-2006, we applied two calibration methods to these retrospective exposure predictions: (1) multiplicative calibration and (2) Bayesian pharmacokinetic calibration with larger adjustments to more recent exposure estimates and smaller adjustments to exposure estimates for years farther in the past. We conducted simulation studies of various hypothetical exposure scenarios and compared hypothetical true historical intake rates with estimates based on mis-specified baseline exposure and pharmacokinetic models to find the method with the least bias. The Bayesian method outperformed the multiplicative method if a change to bottled water consumption was not reported or if the half-life of PFOA was mis-specified. On the other hand, the multiplicative method outperformed the Bayesian method if actual tap water consumption rates were systematically overestimated. If tap water consumption rates gradually decreased over time because of substitution with bottled water or other liquids, neither method clearly outperformed another. Calibration of retrospective exposure estimates using recently collected biomarkers may help reduce uncertainties in environmental epidemiologic studies. PMID:24730513

Shin, Hyeong-Moo; Steenland, Kyle; Ryan, P Barry; Vieira, Verónica M; Bartell, Scott M

2014-05-20

294

Adjustments of response threshold during task switching: a model-based functional magnetic resonance imaging study.  

PubMed

Adjustment of response threshold for speed compared with accuracy instructions in two-choice decision-making tasks is associated with activation in the fronto-striatal network, including the pre-supplementary motor area (pre-SMA) and striatum (Forstmann et al., 2008). In contrast, increased response conservativeness is associated with activation of the subthalamic nucleus (STN) (Frank et al., 2007). We investigated the involvement of these regions in trial-by-trial adjustments of response threshold in humans, using a cued-trials task-switching paradigm. Fully and partially informative switch cues produced more conservative thresholds than repeat cues. Repeat cues were associated with higher activation in pre-SMA and striatum than switch cues. For all cue types, individual variability in response threshold was associated with activation level in pre-SMA, with higher activation linked to lower threshold setting. In the striatum, this relationship was found for repeat cues only. These findings support the notion that pre-SMA biases the striatum to lower response threshold under more liberal response regimens. In contrast, a high threshold for switch cues was associated with greater activation in right STN, consistent with increasing response caution under conservative response regimens. We conclude that neural models of response threshold adjustment can help explain executive control processes in task switching. PMID:21994385

Mansfield, Elise L; Karayanidis, Frini; Jamadar, Sharna; Heathcote, Andrew; Forstmann, Birte U

2011-10-12

295

An events based algorithm for distributing concurrent tasks on multi-core architectures  

NASA Astrophysics Data System (ADS)

In this paper, a programming model is presented which enables scalable parallel performance on multi-core shared memory architectures. The model has been developed for application to a wide range of numerical simulation problems. Such problems involve time stepping or iteration algorithms where synchronization of multiple threads of execution is required. It is shown that traditional approaches to parallelism including message passing and scatter-gather can be improved upon in terms of speed-up and memory management. Using spatial decomposition to create orthogonal computational tasks, a new task management algorithm called H-Dispatch is developed. This algorithm makes efficient use of memory resources by limiting the need for garbage collection and takes optimal advantage of multiple cores by employing a "hungry" pull strategy. The technique is demonstrated on a simple finite difference solver and results are compared to traditional MPI and scatter-gather approaches. The H-Dispatch approach achieves near linear speed-up with results for efficiency of 85% on a 24-core machine. It is noted that the H-Dispatch algorithm is quite general and can be applied to a wide class of computational tasks on heterogeneous architectures involving multi-core and GPGPU hardware.

Holmes, David W.; Williams, John R.; Tilke, Peter

2010-02-01

296

OccIDEAS: Retrospective Occupational Exposure Assessment in Community-Based Studies Made Easier  

PubMed Central

Assessing occupational exposure in retrospective community-based case-control studies is difficult as measured exposure data are very seldom available. The expert assessment method is considered the most accurate way to attribute exposure but it is a time consuming and expensive process and may be seen as subjective, nonreproducible, and nontransparent. In this paper, we describe these problems and outline our solutions as operationalized in a web-based software application (OccIDEAS). The novel aspects of OccIDEAS are combining all steps in the assessment into one software package; enmeshing the process of assessment into the development of questionnaires; selecting the exposure(s) of interest; specifying rules for exposure assignment; allowing manual or automatic assessments; ensuring that circumstances in which exposure is possible for an individual are highlighted for review; providing reports to ensure consistency of assessment. Development of this application has the potential to make high-quality occupational assessment more efficient and accessible for epidemiological studies.

Fritschi, Lin; Friesen, Melissa C.; Glass, Deborah; Benke, Geza; Girschik, Jennifer; Sadkowsky, Troy

2009-01-01

297

Adult age differences, response management, and cue focality in event-based prospective memory: a meta-analysis on the role of task order specificity.  

PubMed

The present meta-analysis investigated whether event-based prospective memory (PM) age effects differ by task order specificity. In specified PM tasks, the order of the ongoing and the PM task response is predetermined, which imposes demands on cognitive control to navigate the possible response options. In contrast, unspecified PM tasks do not require responding in a particular order. Based on 57 studies and more than 5,500 younger and older adults, results showed larger PM age effects in specified compared with unspecified PM tasks. Additionally, the effect of task focality on age differences was replicated. Results suggest that both pre- and postretrieval processes independently affect PM age effects. PMID:24041004

Ihle, Andreas; Hering, Alexandra; Mahy, Caitlin E V; Bisiacchi, Patrizia S; Kliegel, Matthias

2013-09-01

298

Exposure fusion based on steerable pyramid for displaying high dynamic range scenes  

Microsoft Academic Search

Currently, most exposure fusion algorithms are put forward on the assumption that the source images are aligned prior to fusion. As a result, some artifacts, such as haloing, may be caused due to the slight misalignment in the source images. In order to reduce the influence induced by the misalignment, a novel shift-invariant and rotation-invariant steerable pyramid-based exposure fusion (SPBEF)

Jinhua Wang; De Xu; Bing Li

2009-01-01

299

Persistent Spatial Information in the FEF during Object-based Short-term Memory Does Not Contribute to Task Performance.  

PubMed

We previously reported the existence of a persistent spatial signal in the FEF during object-based STM. This persistent activity reflected the location at which the sample appeared, irrespective of the location of upcoming targets. We hypothesized that such a spatial signal could be used to maintain or enhance object-selective memory activity elsewhere in cortex, analogous to the role of a spatial signal during attention. Here, we inactivated a portion of the FEF with GABAa agonist muscimol to test whether the observed activity contributes to object memory performance. We found that, although RTs were slowed for saccades into the inactivated portion of retinotopic space, performance for samples appearing in that region was unimpaired. This contrasts with the devastating effects of the same FEF inactivation on purely spatial working memory, as assessed with the memory-guided saccade task. Thus, in a task in which a significant fraction of FEF neurons displayed persistent, sample location-based activity, disrupting this activity had no impact on task performance. PMID:24673408

Clark, Kelsey L; Noudoost, Behrad; Moore, Tirin

2014-06-01

300

The Secure Base Script and the Task of Caring for Elderly Parents: Implications for Attachment Theory and Clinical Practice  

PubMed Central

This study explores links between adults’ attachment representations and the task of caring for elderly parents with dementia. Participants were 87 adults serving as primary caregivers of a parent or parent-in-law with dementia. Waters and Waters’ (2006) Attachment Script Assessment was adapted to assess script-like attachment representation in the context of caring for their elderly parent. The quality of adult-elderly parent interactions was assessed using the Level of Expressed Emotions Scale (Cole & Kazarian, 1988) and self-report measures of caregivers’ perception of caregiving as difficult. Caregivers’ secure base script knowledge predicted lower levels of negative expressed emotion. This effect was moderated by the extent to which participants experienced caring for elderly parents as difficult. Attachment representations played a greater role in caregiving when caregiving tasks were perceived as more difficult. These results support the hypothesis that attachment representations influence the quality of care that adults provide their elderly parents. Clinical implications are discussed.

Chen, Cory K.; Waters, Harriet Salatas; Hartman, Marilyn; Zimmerman, Sheryl; Miklowitz, David J.; Waters, Everett

2013-01-01

301

Current processes of the U.S. Preventive Services Task Force: refining evidence-based recommendation development.  

PubMed

The U.S. Preventive Services Task Force (USPSTF), an independent panel that has provided the gold standard for evidence-based guidelines in prevention for the past 2 decades, continuously refines its methodology. To keep up with the evolving field of evidence- based medicine and to update recommendations in a timely, efficient, and transparent manner, the USPSTF has developed new methods for evidence reviews and recommendation development. This article summarizes the most recent changes in the recommendation development process, including how the USPSTF solicits and prioritizes topics for review, updates evidence reviews and recommendations, and communicates with its audience. PMID:17576998

Guirguis-Blake, Janelle; Calonge, Ned; Miller, Therese; Siu, Albert; Teutsch, Steven; Whitlock, Evelyn

2007-07-17

302

A Community-Based Initiative to Reduce Children's Exposure to Toxics in Household Products  

ERIC Educational Resources Information Center

Purpose--The purpose of this paper is to explore the efficacy of a community-based outreach initiative, piloted in Worcester, Massachusetts, to reduce children's exposure to toxic chemicals in common household products by changing parental behavior regarding product purchase and use. Design/methodology/approach--The program model was based on the…

Blackman, Anne Berlin; Luskin, Jack

2006-01-01

303

"Development of Model-Based Air Pollution Exposure Metrics for use in Epidemiologic Studies"  

EPA Science Inventory

Population-based epidemiological studies of air pollution have traditionally relied upon imperfect surrogates of personal exposures, such as area-wide ambient air pollution levels based on readily available concentrations from central monitoring sites. U.S. EPA in collaboration w...

304

Sensitivity Analyses of Exposure Estimates from a Quantitative Job-exposure Matrix (SYN-JEM) for Use in Community-based Studies  

PubMed Central

Objectives: We describe the elaboration and sensitivity analyses of a quantitative job-exposure matrix (SYN-JEM) for respirable crystalline silica (RCS). The aim was to gain insight into the robustness of the SYN-JEM RCS estimates based on critical decisions taken in the elaboration process. Methods: SYN-JEM for RCS exposure consists of three axes (job, region, and year) based on estimates derived from a previously developed statistical model. To elaborate SYN-JEM, several decisions were taken: i.e. the application of (i) a single time trend; (ii) region-specific adjustments in RCS exposure; and (iii) a prior job-specific exposure level (by the semi-quantitative DOM-JEM), with an override of 0 mg/m3 for jobs a priori defined as non-exposed. Furthermore, we assumed that exposure levels reached a ceiling in 1960 and remained constant prior to this date. We applied SYN-JEM to the occupational histories of subjects from a large international pooled community-based case–control study. Cumulative exposure levels derived with SYN-JEM were compared with those from alternative models, described by Pearson correlation (Rp) and differences in unit of exposure (mg/m3-year). Alternative models concerned changes in application of job- and region-specific estimates and exposure ceiling, and omitting the a priori exposure ranking. Results: Cumulative exposure levels for the study subjects ranged from 0.01 to 60 mg/m3-years, with a median of 1.76 mg/m3-years. Exposure levels derived from SYN-JEM and alternative models were overall highly correlated (Rp > 0.90), although somewhat lower when omitting the region estimate (Rp = 0.80) or not taking into account the assigned semi-quantitative exposure level (Rp = 0.65). Modification of the time trend (i.e. exposure ceiling at 1950 or 1970, or assuming a decline before 1960) caused the largest changes in absolute exposure levels (26–33% difference), but without changing the relative ranking (Rp = 0.99). Conclusions: Exposure estimates derived from SYN-JEM appeared to be plausible compared with (historical) levels described in the literature. Decisions taken in the development of SYN-JEM did not critically change the cumulative exposure levels. The influence of region-specific estimates needs to be explored in future risk analyses.

Peters, Susan

2013-01-01

305

Comparative international analysis of radiofrequency exposure surveys of mobile communication radio base stations.  

PubMed

This paper presents analyses of data from surveys of radio base stations in 23 countries across five continents from the year 2000 onward and includes over 173,000 individual data points. The research compared the results of the national surveys, investigated chronological trends and compared exposures by technology. The key findings from this data are that irrespective of country, the year and cellular technology, exposures to radio signals at ground level were only a small fraction of the relevant human exposure standards. Importantly, there has been no significant increase in exposure levels since the widespread introduction of 3G mobile services, which should be reassuring for policy makers and negate the need for post-installation measurements at ground level for compliance purposes. There may be areas close to antennas where compliance levels could be exceeded. Future potential work includes extending the study to additional countries, development of cumulative exposure distributions and investigating the possibility of linking exposure measurements to population statistics to assess the distribution of exposure levels relative to population percentiles. PMID:22377680

Rowley, Jack T; Joyner, Ken H

2012-01-01

306

Studying permethrin exposure in flight attendants using a physiologically based pharmacokinetic model.  

PubMed

Assessment of potential health risks to flight attendants from exposure to pyrethroid insecticides, used for aircraft disinsection, is limited because of (a) lack of information on exposures to these insecticides, and (b) lack of tools for linking these exposures to biomarker data. We developed and evaluated a physiologically based pharmacokinetic (PBPK) model to assess the exposure of flight attendants to the pyrethroid insecticide permethrin attributable to aircraft disinsection. The permethrin PBPK model was developed by adapting previous models for pyrethroids, and was parameterized using currently available metabolic parameters for permethrin. The human permethrin model was first evaluated with data from published human studies. Then, it was used to estimate urinary metabolite concentrations of permethrin in flight attendants who worked in aircrafts, which underwent residual and pre-flight spray treatments. The human model was also applied to analyze the toxicokinetics following permethrin exposures attributable to other aircraft disinsection scenarios. Predicted levels of urinary 3-phenoxybenzoic acid (3-PBA), a metabolite of permethrin, following residual disinsection treatment were comparable to the measurements made for flight attendants. Simulations showed that the median contributions of the dermal, oral and inhalation routes to permethrin exposure in flight attendants were 83.5%, 16.1% and 0.4% under residual treatment scenario, respectively, and were 5.3%, 5.0% and 89.7% under pre-flight spray scenario, respectively. The PBPK model provides the capability to simulate the toxicokinetic profiles of permethrin, and can be used in the studies on human exposure to permethrin. PMID:23462847

Wei, Binnian; Isukapalli, Sastry S; Weisel, Clifford P

2013-07-01

307

Studying permethrin exposure in flight attendants using a physiologically based pharmacokinetic model  

PubMed Central

Assessment of potential health risks to flight attendants from exposure to pyrethroid insecticides, used for aircraft disinsection, is limited because of (a) lack of information on exposures to these insecticides, and (b) lack of tools for linking these exposures to biomarker data. We developed and evaluated a physiologically based pharmacokinetic (PBPK) model to assess the exposure of flight attendants to the pyrethroid insecticide permethrin attributable to aircraft disinsection. The permethrin PBPK model was developed by adapting previous models for pyrethroids, and was parameterized using currently available metabolic parameters for permethrin. The human permethrin model was first evaluated with data from published human studies. Then, it was used to estimate urinary metabolite concentrations of permethrin in flight attendants who worked in aircrafts, which underwent residual and pre-flight spray treatments. The human model was also applied to analyze the toxicokinetics following permethrin exposures attributable to other aircraft disinsection scenarios. Predicted levels of urinary 3-phenoxybenzoic acid (3-PBA), a metabolite of permethrin, following residual disinsection treatment were comparable to the measurements made for flight attendants. Simulations showed that the median contributions of the dermal, oral and inhalation routes to permethrin exposure in flight attendants were 83.5%, 16.1% and 0.4% under residual treatment scenario, respectively, and were 5.3%, 5.0% and 89.7% under pre-flight spray scenario, respectively. The PBPK model provides the capability to simulate the toxicokinetic profiles of permethrin, and can be used in the studies on human exposure to permethrin.

Wei, Binnian; Isukapalli, Sastry S.; Weisel, Clifford P.

2014-01-01

308

Task-based imaging of colon cancer in the Apc(Min/+) mouse model.  

PubMed

Optical coherence tomography (OCT), laser-induced fluorescence (LIF), and laser-scanning confocal microscopy (LSCM) were used for the task of multimodal study of healthy and adenomatous mouse colon. The results from each modality were compared with histology, which served as the gold standard. The Apc(Min/+) genetic mouse model of colon cancer was compared with wild-type mice. In addition, a special diet was used for the task of studying the origins of a 680 nm autofluorescent signal that was previously observed in colon. The study found close agreement among each of the modalities and with histology. All four modalities were capable of identifying diseased tissue accurately. The OCT and LSCM images provided complementary structural information about the tissue, while the autofluorescence signal measured by LIF and LSCM provided biochemical information. OCT and LIF were performed in vivo and nondestructively, while the LSCM and histology required extraction of the tissue. The magnitude of the 680 nm signal correlates with chlorophyll content in the mouse diet, suggesting that the autofluorescent compound is a dietary metabolite. PMID:16639453

McNally, James B; Kirkpatrick, Nathaniel D; Hariri, Lida P; Tumlinson, Alexandre R; Besselsen, David G; Gerner, Eugene W; Utzinger, Urs; Barton, Jennifer K

2006-05-01

309

Task-based imaging of colon cancer in the ApcMin/+ mouse model  

NASA Astrophysics Data System (ADS)

Optical coherence tomography (OCT), laser-induced fluorescence (LIF), and laser-scanning confocal microscopy (LSCM) were used for the task of multimodal study of healthy and adenomatous mouse colon. The results from each modality were compared with histology, which served as the gold standard. The ApcMin/+ genetic mouse model of colon cancer was compared with wild-type mice. In addition, a special diet was used for the task of studying the origins of a 680 nm autofluorescent signal that was previously observed in colon. The study found close agreement among each of the modalities and with histology. All four modalities were capable of identifying diseased tissue accurately. The OCT and LSCM images provided complementary structural information about the tissue, while the autofluorescence signal measured by LIF and LSCM provided biochemical information. OCT and LIF were performed in vivo and nondestructively, while the LSCM and histology required extraction of the tissue. The magnitude of the 680 nm signal correlates with chlorophyll content in the mouse diet, suggesting that the autofluorescent compound is a dietary metabolite.

McNally, James B.; Kirkpatrick, Nathaniel D.; Hariri, Lida P.; Tumlinson, Alexandre R.; Besselsen, David G.; Gerner, Eugene W.; Utzinger, Urs; Barton, Jennifer K.

2006-05-01

310

AutomaDeD: Automata-Based Debugging for Dissimilar Parallel Tasks  

SciTech Connect

Today's largest systems have over 100,000 cores, with million-core systems expected over the next few years. This growing scale makes debugging the applications that run on them a daunting challenge. Few debugging tools perform well at this scale and most provide an overload of information about the entire job. Developers need tools that quickly direct them to the root cause of the problem. This paper presents AutomaDeD, a tool that identifies which tasks of a large-scale application first manifest a bug at a specific code region at a specific point during program execution. AutomaDeD creates a statistical model of the application's control-flow and timing behavior that organizes tasks into groups and identifies deviations from normal execution, thus significantly reducing debugging effort. In addition to a case study in which AutomaDeD locates a bug that occurred during development of MVAPICH, we evaluate AutomaDeD on a range of bugs injected into the NAS parallel benchmarks. Our results demonstrate that detects the time period when a bug first manifested itself with 90% accuracy for stalls and hangs and 70% accuracy for interference faults. It identifies the subset of processes first affected by the fault with 80% accuracy and 70% accuracy, respectively and the code region where where the fault first manifested with 90% and 50% accuracy, respectively.

Bronevetsky, G; Laguna, I; Bagchi, S; de Supinski, B R; Ahn, D; Schulz, M

2010-03-23

311

Grid Task Execution  

NASA Technical Reports Server (NTRS)

IPG Execution Service is a framework that reliably executes complex jobs on a computational grid, and is part of the IPG service architecture designed to support location-independent computing. The new grid service enables users to describe the platform on which they need a job to run, which allows the service to locate the desired platform, configure it for the required application, and execute the job. After a job is submitted, users can monitor it through periodic notifications, or through queries. Each job consists of a set of tasks that performs actions such as executing applications and managing data. Each task is executed based on a starting condition that is an expression of the states of other tasks. This formulation allows tasks to be executed in parallel, and also allows a user to specify tasks to execute when other tasks succeed, fail, or are canceled. The two core components of the Execution Service are the Task Database, which stores tasks that have been submitted for execution, and the Task Manager, which executes tasks in the proper order, based on the user-specified starting conditions, and avoids overloading local and remote resources while executing tasks.

Hu, Chaumin

2007-01-01

312

Modifying Exposure-Based CBT for Cambodian Refugees with Posttraumatic Stress Disorder  

PubMed Central

Cambodian refugees represent a severely traumatized population living in the United States. In this paper, we describe the modification of a cognitive-behavior therapy program to facilitate delivery of an exposure-based treatment for posttraumatic stress disorder while addressing some of the challenges brought by differences in language and culture between providers and patients. Our treatment modifications include the use of metaphors and culturally relevant examples to aid the communication of core concepts by interpreters, an emphasis on teaching the “process” of exposure therapy rather than relying on specific exposure practice in the group setting, a focus on interoceptive exposure to allow more effective group practice and to address culturally specific symptom interpretations, attention to the way in which treatment procedures interacted with culturally specific beliefs, and efforts to integrate treatment services within the community. Although data are limited, results to date suggest that this modified treatment was acceptable to patients and offered benefits on the order of large effect sizes.

Otto, Michael W.; Hinton, Devon E.

2009-01-01

313

Pharmacological enhancement of exposure-based treatment in PTSD: a qualitative review  

PubMed Central

There is a good amount of evidence that exposure therapy is an effective treatment for posttraumatic stress disorder (PTSD). Notwithstanding its efficacy, there is room for improvement, since a large proportion of patients does not benefit from treatment. Recently, an interesting new direction in the improvement of exposure therapy efficacy for PTSD emerged. Basic research found evidence of the pharmacological enhancement of the underlying learning and memory processes of exposure therapy. The current review aims to give an overview of clinical studies on pharmacological enhancement of exposure-based treatment for PTSD. The working mechanisms, efficacy studies in PTSD patients, and clinical utility of four different pharmacological enhancers will be discussed: d-cycloserine, MDMA, hydrocortisone, and propranolol.

de Kleine, Rianne A.; Rothbaum, Barbara O.; van Minnen, Agnes

2013-01-01

314

Computer-Based Video Instruction to Teach Young Adults with Moderate Intellectual Disabilities to Perform Multiple Step, Job Tasks in a Generalized Setting  

ERIC Educational Resources Information Center

This study evaluated the effectiveness of computer-based video instruction (CBVI) to teach three young adults with moderate intellectual disabilities to perform complex, multiple step, job tasks in a generalized setting. A multiple probe design across three job tasks and replicated across three students was used to evaluate the effectiveness of…

Mechling, Linda C.; Ortega-Hurndon, Fanny

2007-01-01

315

Odor valence linearly modulates attractiveness, but not age assessment, of invariant facial features in a memory-based rating task.  

PubMed

Scented cosmetic products are used across cultures as a way to favorably influence one's appearance. While crossmodal effects of odor valence on perceived attractiveness of facial features have been demonstrated experimentally, it is unknown whether they represent a phenomenon specific to affective processing. In this experiment, we presented odors in the context of a face battery with systematic feature manipulations during a speeded response task. Modulatory effects of linear increases of odor valence were investigated by juxtaposing subsequent memory-based ratings tasks - one predominantly affective (attractiveness) and a second, cognitive (age). The linear modulation pattern observed for attractiveness was consistent with additive effects of face and odor appraisal. Effects of odor valence on age perception were not linearly modulated and may be the result of cognitive interference. Affective and cognitive processing of faces thus appear to differ in their susceptibility to modulation by odors, likely as a result of privileged access of olfactory stimuli to affective brain networks. These results are critically discussed with respect to potential biases introduced by the preceding speeded response task. PMID:24874703

Seubert, Janina; Gregory, Kristen M; Chamberland, Jessica; Dessirier, Jean-Marc; Lundström, Johan N

2014-01-01

316

Classification effects of real and imaginary movement selective attention tasks on a P300-based brain-computer interface  

NASA Astrophysics Data System (ADS)

Brain-computer interfaces (BCIs) rely on various electroencephalography methodologies that allow the user to convey their desired control to the machine. Common approaches include the use of event-related potentials (ERPs) such as the P300 and modulation of the beta and mu rhythms. All of these methods have their benefits and drawbacks. In this paper, three different selective attention tasks were tested in conjunction with a P300-based protocol (i.e. the standard counting of target stimuli as well as the conduction of real and imaginary movements in sync with the target stimuli). The three tasks were performed by a total of 10 participants, with the majority (7 out of 10) of the participants having never before participated in imaginary movement BCI experiments. Channels and methods used were optimized for the P300 ERP and no sensory-motor rhythms were explicitly used. The classifier used was a simple Fisher's linear discriminant. Results were encouraging, showing that on average the imaginary movement achieved a P300 versus No-P300 classification accuracy of 84.53%. In comparison, mental counting, the standard selective attention task used in previous studies, achieved 78.9% and real movement 90.3%. Furthermore, multiple trial classification results were recorded and compared, with real movement reaching 99.5% accuracy after four trials (12.8 s), imaginary movement reaching 99.5% accuracy after five trials (16 s) and counting reaching 98.2% accuracy after ten trials (32 s).

Salvaris, Mathew; Sepulveda, Francisco

2010-10-01

317

Odor Valence Linearly Modulates Attractiveness, but Not Age Assessment, of Invariant Facial Features in a Memory-Based Rating Task  

PubMed Central

Scented cosmetic products are used across cultures as a way to favorably influence one's appearance. While crossmodal effects of odor valence on perceived attractiveness of facial features have been demonstrated experimentally, it is unknown whether they represent a phenomenon specific to affective processing. In this experiment, we presented odors in the context of a face battery with systematic feature manipulations during a speeded response task. Modulatory effects of linear increases of odor valence were investigated by juxtaposing subsequent memory-based ratings tasks – one predominantly affective (attractiveness) and a second, cognitive (age). The linear modulation pattern observed for attractiveness was consistent with additive effects of face and odor appraisal. Effects of odor valence on age perception were not linearly modulated and may be the result of cognitive interference. Affective and cognitive processing of faces thus appear to differ in their susceptibility to modulation by odors, likely as a result of privileged access of olfactory stimuli to affective brain networks. These results are critically discussed with respect to potential biases introduced by the preceding speeded response task.

Seubert, Janina; Gregory, Kristen M.; Chamberland, Jessica; Dessirier, Jean-Marc; Lundstrom, Johan N.

2014-01-01

318

In vitro vs. canine data for assessing early exposure of doxazosin base and its mesylate salt.  

PubMed

In this study, we evaluated the usefulness of biorelevant in vitro data and of canine data in forecasting early exposure after the administration of two phases of a BCS Class II compound, i.e., doxazosin base (DB) and its mesylate salt (DM). DB, DM, and doxazosin hydrochloride (DH) were prepared and characterized. In vitro data were collected in various media, including human aspirates. Solubilities of DB and DM in human gastric fluid were forecasted by data in fasted state simulating gastric fluid containing physiological components (FaSSGF-V2) but not by data in HCl(pH 1.8). Unlike data in FaSSGF-V2, dissolution of DB and DM tablets in HCl(pH 1.6) is rapid. Dissolution of DB tablet in FaSSGF-V2 is incomplete and conversion to DH seems to occur. Differences between DB and DM in dissolution in the small intestine are overestimated in the absence of physiological solubilizers. Using the in vitro data and previously described modeling procedures, the cumulative doxazosin profile in plasma was simulated and the 0-2h profile was used for evaluating early exposure. Individual cumulative doxazosin profiles in plasma, after single DM tablet administrations to 24 adults, were constructed from corresponding actual plasma profiles. Compared with in vitro DM data in pure aqueous buffers, DM data in biorelevant media led to better prediction of early exposure. Based on intersubject variability in early exposure after DM administration and simulated profiles, the administered phase, DB or DM, does not have a significant impact on early exposure. Partial AUCs were used for evaluating early exposure after DB and DM administration in 4 dogs. Early exposure was significantly higher after administration of DM to dogs. Dogs are not appropriate for evaluating differences in early exposure after DB and DM administrations. PMID:22019530

Erceg, Marijana; Vertzoni, Maria; Ceri?, Helena; Dumi?, Miljenko; Cetina-?ižmek, Biserka; Reppas, Christos

2012-02-01

319

Health effects of gasoline exposure. I. Exposure assessment for U.S. distribution workers.  

PubMed Central

Personal exposures were estimated for a large cohort of workers in the U.S. domestic system for distributing gasoline by trucks and marine vessels. This assessment included development of a rationale and methodology for extrapolating vapor exposures prior to the availability of measurement data, analysis of existing measurement data to estimate task and job exposures during 1975-1985, and extrapolation of truck and marine job exposures before 1975. A worker's vapor exposure was extrapolated from three sets of factors: the tasks in his or her job associated with vapor sources, the characteristics of vapor sources (equipment and other facilities) at the work site, and the composition of petroleum products producing vapors. Historical data were collected on the tasks in job definitions, on work-site facilities, and on product composition. These data were used in a model to estimate the overall time-weighted-average vapor exposure for jobs based on estimates of task exposures and their duration. Task exposures were highest during tank filling in trucks and marine vessels. Measured average annual, full-shift exposures during 1975-1985 ranged from 9 to 14 ppm of total hydrocarbon vapor for truck drivers and 2 to 35 ppm for marine workers on inland waterways. Extrapolated past average exposures in truck operations were highest for truck drivers before 1965 (range 140-220 ppm). Other jobs in truck operations resulted in much lower exposures. Because there were few changes in marine operations before 1979, exposures were assumed to be the same as those measured during 1975-1985. Well-defined exposure gradients were found across jobs within time periods, which were suitable for epidemiologic analyses.

Smith, T J; Hammond, S K; Wong, O

1993-01-01

320

Template-based approach for detecting motor task activation-related hyperperfusion in pulsed ASL data.  

PubMed

Arterial spin labeling (ASL) permits the noninvasive measurement of quantitative values of cerebral blood flow (CBF) and is thus well adapted to study inter- and intrasubject perfusion variations whether at rest or during an fMRI task. In this study, a template approach to detect brain activation as a CBF difference between resting and activated groups was compared with a standard generalized linear model (GLM) analysis. A basal perfusion template of PICORE-Q2TIPS ASL images acquired at 3T from a group of 25 healthy subjects (mean age 31.6 ± 8.3 years) was created. The second group of 12 healthy subjects (mean age 28.6 ± 2.7 years) performed a block-design motor task. The template was compared with the mean activated image of the second group both at the individual and at the group level to extract activation maps. The results obtained using a GLM analysis of the whole sequence was used as ground truth for comparison. The influences of spatial normalization using DARTEL registration and of correction of partial volume effects (PVE) in the construction of the template were assessed. Results showed that a basal perfusion template can detect activation-related hyperperfusion in motor areas. The true positive ratio was increased by 2.5% using PVE-correction and by 3.2% using PVE-correction with DARTEL registration. On average, the group comparison presented a 2.2% higher true positive ratio than the one-to-many comparison. PMID:23408457

Petr, Jan; Ferré, Jean-Christophe; Raoult, Hélène; Bannier, Elise; Gauvrit, Jean-Yves; Barillot, Christian

2014-04-01

321

Student Off-Task Behavior in Computer-Based Learning in the Philippines: Comparison to Prior Research in the USA  

ERIC Educational Resources Information Center

Background: Off-task behavior can be defined as any behavior that does not involve the learning task or material, or where learning from the material is not the primary goal. One suggested path for understanding how to address off-task behavior is to study classrooms where off-task behavior is less common, particularly in Asia, in order to…

Rodrigo, Ma. Mercedes T.; Baker, Ryan S. J. D.; Rossi, Lisa

2013-01-01

322

Varying the importance of a prospective memory task: Differential effects across time - and event-based prospective memory  

Microsoft Academic Search

Only few studies have addressed the issue of task importance in prospective memory. Most of them, but not all, have shown that perceived task importance does improve prospective memory performance. However, there is little understanding of (1) the conditions under which importance of the prospective memory task makes a difference in performance and (2) the mechanisms by which perceived task

Matthias Kliegel; Mike Martin; Mark A. McDaniel; Gilles O. Einstein

2001-01-01

323

Effects of periodic task-specific test feedback on physical performance in older adults undertaking band-based resistance exercise.  

PubMed

The purpose of this study was to determine the effects of periodic task-specific test feedback on performance improvement in older adults undertaking community- and home-based resistance exercises (CHBRE). Fifty-two older adults (65-83 years) were assigned to a muscular perfsormance feedback group (MPG, n = 32) or a functional mobility feedback group (FMG, n = 20). Both groups received exactly the same 9-week CHBRE program comprising one community-based and two home-based sessions per week. Muscle performance included arm curls and chair stands in 30 seconds, while functional mobility was determined by the timed up and go (TUG) test. MPG received fortnightly test feedback only on muscle performance and FMG received feedback only on the TUG. Following training, there was a significant (P < 0.05) interaction for all performance tests with MPG improving more for the arm curls (MPG 31.4%, FMG 15.9%) and chair stands (MPG 33.7%, FMG 24.9%) while FMG improved more for the TUG (MPG-3.5%, FMG-9.7%). Results from this nonrandomized study suggest that periodic test feedback during resistance training may enhance task-specific physical performance in older persons, thereby augmenting reserve capacity or potentially reducing the time required to recover functional abilities. PMID:24616808

Hasegawa, Ryuichi; Islam, Mohammod Monirul; Watanabe, Ryuji; Tomiyama, Naoki; Taaffe, Dennis R

2014-01-01

324

Effects of Periodic Task-Specific Test Feedback on Physical Performance in Older Adults Undertaking Band-Based Resistance Exercise  

PubMed Central

The purpose of this study was to determine the effects of periodic task-specific test feedback on performance improvement in older adults undertaking community- and home-based resistance exercises (CHBRE). Fifty-two older adults (65–83 years) were assigned to a muscular perfsormance feedback group (MPG, n = 32) or a functional mobility feedback group (FMG, n = 20). Both groups received exactly the same 9-week CHBRE program comprising one community-based and two home-based sessions per week. Muscle performance included arm curls and chair stands in 30 seconds, while functional mobility was determined by the timed up and go (TUG) test. MPG received fortnightly test feedback only on muscle performance and FMG received feedback only on the TUG. Following training, there was a significant (P < 0.05) interaction for all performance tests with MPG improving more for the arm curls (MPG 31.4%, FMG 15.9%) and chair stands (MPG 33.7%, FMG 24.9%) while FMG improved more for the TUG (MPG-3.5%, FMG-9.7%). Results from this nonrandomized study suggest that periodic test feedback during resistance training may enhance task-specific physical performance in older persons, thereby augmenting reserve capacity or potentially reducing the time required to recover functional abilities.

Islam, Mohammod Monirul; Watanabe, Ryuji; Taaffe, Dennis R.

2014-01-01

325

Likelihood-based methods for regression analysis with binary exposure status assessed by pooling  

PubMed Central

The need for resource-intensive laboratory assays to assess exposures in many epidemiologic studies provides ample motivation to consider study designs that incorporate pooled samples. In this paper, we consider the case in which specimens are combined for the purpose of determining the presence or absence of a pool-wise exposure, in lieu of assessing the actual binary exposure status for each member of the pool. We presume a primary logistic regression model for an observed binary outcome, together with a secondary regression model for exposure. We facilitate maximum likelihood analysis by complete enumeration of the possible implications of a positive pool, and we discuss the applicability of this approach under both cross-sectional and case-control sampling. We also provide a maximum likelihood approach for longitudinal or repeated measures studies where the binary outcome and exposure are assessed on multiple occasions and within-subject pooling is conducted for exposure assessment. Simulation studies illustrate the performance of the proposed approaches along with their computational feasibility using widely available software. We apply the methods to investigate gene–disease association in a population-based case-control study of colorectal cancer.

Lyles, Robert H.; Tang, Li; Lin, Ji; Zhang, Zhiwei; Mukherjee, Bhramar

2012-01-01

326

Noise exposure reconstruction and evaluation of exposure trends in two large automotive plants.  

PubMed

This study used a task-based approach to reconstruct employee noise exposures at two large automotive manufacturing plants for the period 1970-1989, utilizing historic noise measurement data, work history records, documented changes in plant operations, focus group discussions, structured interviews with long-tenure employees, and task-based job profiles. Task-based job noise exposure profiles were developed in the 1990s when the plants conducted task-based noise monitoring. Under the assumption that tasks and time-at-task profile within jobs did not change over time, these profiles were applied to historic jobs. By linking historic noise exposure measurements to job tasks, this approach allowed task-based reconstructed noise exposure profiles to capture variability of daily noise exposures. Reconstructed noise exposures, along with task-based noise exposure measurements collected at each plant during the 1990s, were analyzed to examine time trends in workplace noise levels and worker noise exposure. Our analysis of noise exposure trends revealed that noise levels for many jobs declined by ?3 dBA from 1970 to 1998 as operational and equipment changes occurred in the plants and some noise control measures were implemented, but for some jobs, noise levels increased in the mid- to late 1990s, most likely because of an increase in production at that time. Overall, the percentage of workers exposed to noise levels >90 dBA decreased from 95% in 1970 to 54% in 1998 at one of the plants and decreased from 36% in 1970 to ~5% in 1999 at the other plant. These reductions indicate a degree of success for the hearing conservation program. However, the actual number of employees with noise exposure >90 dBA increased because of a substantial increase in the number of production employees, particularly in jobs with high noise levels, which shows a hearing conservation program challenge that companies face during periods of increased production. Future analysis of hearing levels in these plant populations will help determine whether noise level reduction translates into decreased hearing loss at these plants. PMID:23852046

Brueck, Scott E; Prince Panaccio, Mary; Stancescu, Daniel; Woskie, Susan; Estill, Cheryl; Waters, Martha

2013-11-01

327

Air Vehicle Integration and Technology Research (AVIATR). Task Order 0003: Condition-Based Maintenance Plus Structural Integrity (CBM+SI) Demonstration (September 2011 to March 2012).  

National Technical Information Service (NTIS)

This report summarizes progress made on the AVIATR contract, Task Order 0003, Condition-Based Maintenance Plus Structural Integrity - Option Phase during the reporting period September 2011 through March 2012. The updated CBM+SI process flowchart is prese...

H. Millwater K. Halbert L. Fitzwater P. Kesler T. Torng

2012-01-01

328

Exposure and mindfulness based therapy for irritable bowel syndrome – An open pilot study  

Microsoft Academic Search

We conducted a study of a group therapy based on exposure and mindfulness in the treatment of irritable bowel syndrome (IBS). Out of 49 outpatients, most of whom were referred from gastroenterological clinics, 34 entered into the 10-week treatment. Patients were assessed before, immediately after and 6 months after treatment. The assessments consisted of a gastrointestinal symptom diary, self-report questionnaires

Brjánn Ljótsson; Sergej Andréewitch; Erik Hedman; Christian Rück; Gerhard Andersson; Nils Lindefors

2010-01-01

329

POTENTIAL INHALATION EXPOSURE TO VOLATILE CHEMICALS IN WATER-BASED HARD-SURFACE CLEANERS  

EPA Science Inventory

Potential inhalation exposure of building occupants to volatile chemicals in water-based hard-surface cleaners was evaluated by analyzing 267 material safety data sheets (MSDSs). Among the 154 chemicals reported, 44 are volatile or semi-volatile. Hazardous air pollutants (HAPs) r...

330

Near field in the vicinity of wireless base-station antennas: an exposure compliance approach  

Microsoft Academic Search

Great social concern has risen about the potential health hazard of living near a cellular telephony base-station antenna, and certain technical questions have been posed on the appropriate way to measure exposure in its vicinity. In this paper, a standard spherical near-near field transformation is proposed to obtain the electromagnetic field close to the antenna in free space conditions. The

Sebastián Blanch; Jordi Romeu; Angel Cardama

2002-01-01

331

Aggression and Violence Exposure in Adolescence and the Role of School-Based Policy Initiatives  

ERIC Educational Resources Information Center

This article reports on an exploratory study into young people's exposure to aggression and violence. It undertakes a collective examination of the domains occupied by young people and in doing so focuses on an area that has for the most part been overlooked by previous researchers in the UK. The analysis is based on the responses of 98 young…

Kennedy, Anne

2011-01-01

332

Development of a health risk-based surface contamination cleanup standard for occupational exposure to beryllium.  

PubMed

A health risk-based surface contamination cleanup standard (SCS) for beryllium (BE) was developed to facilitate the safe transfer of property (equipment and buildings) previously used in BE-related processes. Previous SCSs for BE were primarily based on Department of Energy (DOE) housekeeping criteria rather than health risks. Quantitative health risk assessment methods were used to develop an occupational SCS that explicitly considers the relevant exposure pathways and toxicity endpoints, including both cancer and non-cancer endpoints. For the cancer endpoint at the 1E-06 risk level, the analysis resulted in an SCS of 17 ?g/100 cm(2) based on resuspension of settled dust and subsequent inhalation exposure only (BE is regulated as a carcinogen by the inhalation route only). For the non-cancer endpoint, the analysis resulted in an SCS of 0.07 ?g/100 cm(2) based on dermal absorption, incidental ingestion following dermal contact, and inhalation. The non-cancer SCS was determined virtually entirely by the dermal absorption exposure pathway, with negligible contributions from the incidental ingestion and inhalation pathways. This analysis shows that application of the non-cancer SCS in BE monitoring and control programs will adequately protect workers from both the cancer and non-cancer health effects of BE when surface contamination is the primary source of BE exposure. PMID:20649413

Damian, Paul

2011-02-01

333

In vitro vs. canine data for assessing early exposure of doxazosin base and its mesylate salt  

Microsoft Academic Search

In this study, we evaluated the usefulness of biorelevant in vitro data and of canine data in forecasting early exposure after the administration of two phases of a BCS Class II compound, i.e., doxazosin base (DB) and its mesylate salt (DM). DB, DM, and doxazosin hydrochloride (DH) were prepared and characterized. In vitro data were collected in various media, including

Marijana Erceg; Maria Vertzoni; Helena Ceri?; Miljenko Dumi?; Biserka Cetina-?ižmek; Christos Reppas

334

Risk of lung cancer mortality after expsosure to radon decay products in the Beaverlodge cohort based on revised exposure estimates  

SciTech Connect

Exposures to radon decay products have been re-estimated for 65 men who died of lung cancer between 1950 and 1980, and 126 matched controls selected from the Beaverlodge cohort of 8,487 workers at the Beaverlodge mine in Northern Saskatchewan. The revised exposure estimates were based on a more thorough review of individual employment records for the study subjects than originally conducted, together with historic data from area-specific measurements of exposure rates in the mine. The revised cumulative exposures are approximately 60% higher than the original exposure estimates, which were based on mine-wide averages for those exposures incurred prior to 1967, and which used geometric rather than arithmetic means for area exposure rates. Despite the increase in estimated exposures using the revised estimates, the excess relative risk per 100 working level months has increased from 2.70 to 3.25, most likely due to a substantial reduction in random exposure measurement error. The new data show similar modifying effects of risk by time since exposure and age at risk as other studies of underground miners, but provide no evidence of an inverse exposure-rate effect, in contrast to a strong effect seen in the analyses based on the original exposure estimates. 11 refs. 3 tabs.

Howe, G.R. [Columbia Univ., New York, NY (United States); Stager, R.H. [SENES Consultants Limited, Richmond Hill, Ontario (Canada)

1996-07-01

335

Teaching computer-based spelling to individuals with developmental and hearing disabilities: transfer of stimulus control to writing tasks.  

PubMed Central

Computer-based instruction may yield widely useful handwritten spelling. Illustrative cases involved individuals with mental retardation and hearing impairments. The participant in Study 1 matched computer pictures and printed words to one another but did not spell the words to pictures. Spelling was then taught using a computerized procedure. In general, increases in the accuracy of computer spelling were accompanied by improvements in written spelling to pictures. Study 2 extended these results with a 2nd participant. After initial training, spelling improved in the context of a retrieval task in which the participant (a) wrote a list of the names of objects displayed on a table, (b) selected the objects from a shelf, and (c) returned the objects to the table. Nearly perfect accuracy scores declined on some retrieval trials conducted without a list, suggesting that the list may have served a mediating function during retrieval. Transfer of stimulus control of computer-based teaching to the retrieval task may have been attributable to the existence of stimulus classes involving pictures, objects, and printed words. Images Figure 1 Figure 3

Stromer, R; Mackay, H A; Howell, S R; McVay, A A; Flusser, D

1996-01-01

336

Occupational exposure to asbestos and lung cancer in men: evidence from a population-based case-control study in eight Canadian provinces  

PubMed Central

Background Asbestos is classified as a human carcinogen, and studies have consistently demonstrated that workplace exposure to it increases the risk of developing lung cancer. Few studies have evaluated risks in population-based settings where there is a greater variety in the types of occupations, and exposures. Methods This was a population based case–control study with 1,681 incident cases of lung cancer, and 2,053 controls recruited from 8 Canadian provinces between 1994 and 1997. Self-reported questionnaires were used to elicit a lifetime occupational history, including general tasks, and information for other risk factors. Occupational hygienists, who were blinded to case–control status, assigned asbestos exposures to each job on the basis of (i) concentration (low, medium, high), (ii) frequency (<5%, 5-30%, and >30% of the time in a normal work week), and (iii) reliability (possible, probable, definite). Logistic regression was used to estimate odds ratios (ORs) and their corresponding 95% confidence intervals (CI). Results Those occupationally exposed to (i) low, and (ii) medium or high concentrations of asbestos had ORs for lung cancer of 1.17 (95% CI=0.92 – 1.50) and 2.16 (95% CI=1.21-3.88), respectively, relative to those who were unexposed. Medium or high exposure to asbestos roughly doubled the risk for lung cancer across all three smoking pack-year categories. The joint relationship between smoking and asbestos was consistent with a multiplicative risk model. Conclusions Our findings provide further evidence that exposure to asbestos has contributed to an increased risk of lung cancer in Canadian workplaces, and suggests that nearly 3% of lung cancers among Canadian men are caused by occupational exposure to asbestos.

2012-01-01

337

Exposure based waiving: the application of the toxicological threshold of concern (TTC) to inhalation exposure for aerosol ingredients in consumer products.  

PubMed

The inhalation toxicology studies available in the public domain have been reviewed to establish a database for inhalation toxicology and derive thresholds of toxicological concern (TTC) for effects in the respiratory tract and systemically for Cramer class 1 and 3 chemicals. These TTCs can be used as the basis for developing an exposure based waiving (EBW) approach to evaluating the potential for adverse effects from exposure to ingredients in aerosol products, used by consumers. The measurement of consumer exposure in simulated product use is key to the application of an exposure based waiving approach to evaluating potential consumer risk. The detailed exposure evaluation for aerosol ingredients with defined use scenarios, in conjunction with an evaluation of the potential structure activity relationship for toxicity and the TTCs for inhalation exposure could be used to waive undertaking inhalation toxicology studies under REACH. Not all classes of chemicals are suitable for such an approach, but for chemicals with a predictable low potential toxicity, and very low levels of exposure, this approach, could reduce the amount of inhalation toxicology studies required for the implementation of the European REACH legislation. Such an approach is consistent with the concept of developing 'intelligent testing strategies' for REACH. PMID:19275927

Carthew, P; Clapp, C; Gutsell, S

2009-06-01

338

Applicability of an exposure model for the determination of emissions from mobile phone base stations.  

PubMed

Applicability of a model to estimate radiofrequency electromagnetic field (RF-EMF) strength in households from mobile phone base stations was evaluated with technical data of mobile phone base stations available from the German Net Agency, and dosimetric measurements, performed in an epidemiological study. Estimated exposure and exposure measured with dosemeters in 1322 participating households were compared. For that purpose, the upper 10th percentiles of both outcomes were defined as the 'higher exposed' groups. To assess the agreement of the defined 'higher' exposed groups, kappa coefficient, sensitivity and specificity were calculated. The present results show only a weak agreement of calculations and measurements (kappa values between -0.03 and 0.28, sensitivity between 7.1 and 34.6). Only in some of the sub-analyses, a higher agreement was found, e.g. when measured instead of interpolated geo-coordinates were used to calculate the distance between households and base stations, which is one important parameter in modelling exposure. During the development of the exposure model, more precise input data were available for its internal validation, which yielded kappa values between 0.41 and 0.68 and sensitivity between 55 and 76 for different types of housing areas. Contrary to this, the calculation of exposure-on the basis of the available imprecise data from the epidemiological study-is associated with a relatively high degree of uncertainty. Thus, the model can only be applied in epidemiological studies, when the uncertainty of the input data is considerably reduced. Otherwise, the use of dosemeters to determine the exposure from RF-EMF in epidemiological studies is recommended. PMID:18676976

Breckenkamp, J; Neitzke, H P; Bornkessel, C; Berg-Beckhoff, G

2008-01-01

339

The Importance of the Secure Base Effect for Domestic Dogs - Evidence from a Manipulative Problem-Solving Task  

PubMed Central

Background It has been suggested that dogs display a secure base effect similar to that found in human children (i.e., using the owner as a secure base for interacting with the environment). In children, this effect influences their daily lives and importantly also their performance in cognitive testing. Here, we investigate the importance of the secure base effect for dogs in a problem-solving task. Methodology/Principal Findings Using a manipulative task, we tested dogs in three conditions, in which we varied the owner's presence and behavior (Experiment 1: “Absent owner”, “Silent owner”, “Encouraging owner”) and in one additional condition, in which the owner was replaced by an unfamiliar human (Experiment 2: “Replaced owner”). We found that the dogs' duration of manipulating the apparatus was longer when their owner was present than absent, irrespective of the owner's behavior. The presence of an unfamiliar human however did not increase their manipulation. Furthermore, the reduced manipulation during the absence of the owner was not correlated with the dog's degree of separation distress scored in a preceding attachment experiment. Conclusions/Significance Our study is the first to provide evidence for an owner-specific secure base effect in dogs that extends from attachment tests to other areas of dogs' lives and also manifests itself in cognitive testing – thereby confirming the remarkable similarity between the secure base effect in dogs and in human children. These results also have important implications for behavioral testing in dogs, because the presence or absence of the owner during a test situation might substantially influence dogs' motivation and therefore the outcome of the test.

Horn, Lisa; Huber, Ludwig; Range, Friederike

2013-01-01

340

Eva: an evaluation tool for comparing descriptors in content-based image retrieval tasks  

Microsoft Academic Search

This paper presents Eva, a tool for evaluating image descriptors for content-based image retrieval. Eva integrates the most common stages of an image retrieval process and provides functionalities to facilitate the comparison of image descriptors in the context of content-based image retrieval. Eva supports the management of image descriptors and image collections and creates a standardized environment to run comparative

Otávio Augusto Bizetto Penatti; Ricardo da Silva Torres

2010-01-01

341

Samples of Students' Responses from the Grade 3 Mathematics Performance-based Assessment Tasks, June 1994.  

ERIC Educational Resources Information Center

As part of Alberta Education's (Canada) broadened assessment initiatives, a sample of 693 Grade 3 students from across the province participated in the Mathematics Performance-based Assessment, 1994. This activity-based assessment, using picture books and manipulatives, was developed by Grade 3 teachers to assess a broad range of skills not easily…

Alberta Dept. of Education, Edmonton. Student Evaluation Branch.

342

An integrated exposure/pharmacokinetic based approach to the assessment of complex exposures. Lead: a case study  

SciTech Connect

A problem in evaluating the hazard represented by an environmental toxicant is that exposures can occur via multiple media such as water, land, and air. Lead is one of the toxicants of concern that has been associated with adverse effects on heme metabolism, serum vitamin D levels, and the mental and physical development of infants and children exposed at very low environmental levels. Effects of lead on development are particularly disturbing in that the consequences of early delays or deficits in physical or mental development may have long-term consequences over the lifetime of affected individuals. Experimental and epidemiologic studies have indicated that blood lead levels in the range of 10-15 micrograms/dl, or possibly lower, are likely to produce subclinical toxicity. Since a discernible threshold has not been demonstrated, it is prudent to preclude development of a Reference Dose (RfD) for lead. As an alternate, the U.S. Environmental Protection Agency (U.S. EPA) has developed the uptake/biokinetic lead model that provides a means for evaluating the relative contribution of various media to establishing blood lead levels in children. This approach will allow for the identification of site- and situation-specific abatement strategies based on projected blood lead levels in vulnerable human populations exposed to lead in air, diet, water, soil/dust, and paint; thus making it possible to evaluate regulatory decisions concerning each medium on blood levels and potential health effects.35 references.

DeRosa, C.T.; Choudhury, H.; Peirano, W.B. (Environmental Criteria and Assessment Office, U.S. Environmental Protection Agency, Cincinnati, OH (United States))

1991-07-01

343

Increase in physical activities in kindergarten children with cerebral palsy by employing MaKey-MaKey-based task systems.  

PubMed

In this study, we employed Flash- and Scratch-based multimedia by using a MaKey-MaKey-based task system to increase the motivation level of children with cerebral palsy to perform physical activities. MaKey MaKey is a circuit board that converts physical touch to a digital signal, which is interpreted by a computer as a keyboard message. In this study, we used conductive materials to control this interaction. This study followed single-case design using ABAB models in which A indicated the baseline and B indicated the intervention. The experiment period comprised 1 month and a half. The experimental results demonstrated that in the case of two kindergarten children with cerebral palsy, their scores were considerably increased during the intervention phrases. The developmental applications of the results are also discussed. PMID:24864049

Lin, Chien-Yu; Chang, Yu-Ming

2014-09-01

344

Saccades to future ball location reveal memory-based prediction in a virtual-reality interception task  

PubMed Central

Despite general agreement that prediction is a central aspect of perception, there is relatively little evidence concerning the basis on which visual predictions are made. Although both saccadic and pursuit eye-movements reveal knowledge of the future position of a moving visual target, in many of these studies targets move along simple trajectories through a fronto-parallel plane. Here, using a naturalistic and racquet-based interception task in a virtual environment, we demonstrate that subjects make accurate predictions of visual target motion, even when targets follow trajectories determined by the complex dynamics of physical interactions and the head and body are unrestrained. Furthermore, we found that, following a change in ball elasticity, subjects were able to accurately adjust their prebounce predictions of the ball's post-bounce trajectory. This suggests that prediction is guided by experience-based models of how information in the visual image will change over time.

Diaz, Gabriel; Cooper, Joseph; Rothkopf, Constantin; Hayhoe, Mary

2013-01-01

345

Attentional spreading to task-irrelevant object features: experimental support and a 3-step model of attention for object-based selection and feature-based processing modulation.  

PubMed

Directing attention to a specific feature of an object has been linked to different forms of attentional modulation. Object-based attention theory founds on the finding that even task-irrelevant features at the selected object are subject to attentional modulation, while feature-based attention theory proposes a global processing benefit for the selected feature even at other objects. Most studies investigated either the one or the other form of attention, leaving open the possibility that both object- and feature-specific attentional effects do occur at the same time and may just represent two sides of a single attention system. We here investigate this issue by testing attentional spreading within and across objects, using reaction time (RT) measurements to changes of attended and unattended features on both attended and unattended objects. We asked subjects to report color and speed changes occurring on one of two overlapping random dot patterns (RDPs), presented at the center of gaze. The key property of the stimulation was that only one of the features (e.g., motion direction) was unique for each object, whereas the other feature (e.g., color) was shared by both. The results of two experiments show that co-selection of unattended features even occurs when those features have no means for selecting the object. At the same time, they demonstrate that this processing benefit is not restricted to the selected object but spreads to the task-irrelevant one. We conceptualize these findings by a 3-step model of attention that assumes a task-dependent top-down gain, object-specific feature selection based on task- and binding characteristics, and a global feature-specific processing enhancement. The model allows for the unification of a vast amount of experimental results into a single model, and makes various experimentally testable predictions for the interaction of object- and feature-specific processes. PMID:24959132

Wegener, Detlef; Galashan, Fingal Orlando; Aurich, Maike Kathrin; Kreiter, Andreas Kurt

2014-01-01

346

Attentional spreading to task-irrelevant object features: experimental support and a 3-step model of attention for object-based selection and feature-based processing modulation  

PubMed Central

Directing attention to a specific feature of an object has been linked to different forms of attentional modulation. Object-based attention theory founds on the finding that even task-irrelevant features at the selected object are subject to attentional modulation, while feature-based attention theory proposes a global processing benefit for the selected feature even at other objects. Most studies investigated either the one or the other form of attention, leaving open the possibility that both object- and feature-specific attentional effects do occur at the same time and may just represent two sides of a single attention system. We here investigate this issue by testing attentional spreading within and across objects, using reaction time (RT) measurements to changes of attended and unattended features on both attended and unattended objects. We asked subjects to report color and speed changes occurring on one of two overlapping random dot patterns (RDPs), presented at the center of gaze. The key property of the stimulation was that only one of the features (e.g., motion direction) was unique for each object, whereas the other feature (e.g., color) was shared by both. The results of two experiments show that co-selection of unattended features even occurs when those features have no means for selecting the object. At the same time, they demonstrate that this processing benefit is not restricted to the selected object but spreads to the task-irrelevant one. We conceptualize these findings by a 3-step model of attention that assumes a task-dependent top-down gain, object-specific feature selection based on task- and binding characteristics, and a global feature-specific processing enhancement. The model allows for the unification of a vast amount of experimental results into a single model, and makes various experimentally testable predictions for the interaction of object- and feature-specific processes.

Wegener, Detlef; Galashan, Fingal Orlando; Aurich, Maike Kathrin; Kreiter, Andreas Kurt

2014-01-01

347

Accuracy of MLP Based Data Visualization Used in Oil Prices Forecasting Task  

Microsoft Academic Search

\\u000a We investigate accuracy, neural network complexity and sample size problem in multilayer perceptron (MLP) based (neuro-linear)\\u000a feature extraction. For feature extraction we use weighted sums calculated in hidden units of the MLP based classifier. Extracted\\u000a features are utilized for data visualisation in 2D and 3D spaces and interactive formation of the pattern classes. We show\\u000a analytically how complexity of feature

Aistis Raudys

2005-01-01

348

Exposure assessment in front of a multi-band base station antenna.  

PubMed

This study investigates occupational exposure to electromagnetic fields in front of a multi-band base station antenna for mobile communications at 900, 1800, and 2100?MHz. Finite-difference time-domain method was used to first validate the antenna model against measurement results published in the literature and then investigate the specific absorption rate (SAR) in two heterogeneous, anatomically correct human models (Virtual Family male and female) at distances from 10 to 1000?mm. Special attention was given to simultaneous exposure to fields of three different frequencies, their interaction and the additivity of SAR resulting from each frequency. The results show that the highest frequency--2100?MHz--results in the highest spatial-peak SAR averaged over 10?g of tissue, while the whole-body SAR is similar at all three frequencies. At distances > 200?mm from the antenna, the whole-body SAR is a more limiting factor for compliance to exposure guidelines, while at shorter distances the spatial-peak SAR may be more limiting. For the evaluation of combined exposure, a simple summation of spatial-peak SAR maxima at each frequency gives a good estimation for combined exposure, which was also found to depend on the distribution of transmitting power between the different frequency bands. PMID:21365667

Kos, Bor; Vali?, Blaž; Kotnik, Tadej; Gajšek, Peter

2011-04-01

349

Association Between Trauma Exposure and Smoking in a Population-Based Sample of Young Adults  

PubMed Central

Purpose To evaluate the relationship between smoking and trauma exposure in a population-based, longitudinal sample. Contrary to current smoking trends in the general population, recent findings indicate continued high smoking rates in trauma-exposed samples. Methods A nationally representative sample of 15,197 adolescents was followed from 1995 (mean age=15.6) to 2002 (mean age=22) as part of 3 waves of The National Longitudinal Study of Adolescent Health (Add Health). We examined the relation between self-reported trauma exposure and smoking behaviors (lifetime regular, current regular), nicotine dependence (Fagerström Test of Nicotine Dependence (FTND)), number of cigarettes per day, and age of onset of regular smoking. Results Controlling for demographics and depressive symptoms, exposure to traumatic events yielded a significant increase in the odds of lifetime regular smoking. Nicotine dependence and cigarettes smoked per day was also significantly related to exposure to Childhood Physical and Sexual Abuse. Decreased age of regular smoking onset was seen for those reporting Childhood Physical Abuse and Childhood Sexual Abuse. Conclusions Exposure to traumatic life events during childhood and young adulthood increases the risk of smoking, highlighting the need to prevent and treat tobacco use in this vulnerable population.

Roberts, Miguel E.; Fuemmeler, Bernard F.; McClernon, F. Joseph; Beckham, Jean C.

2009-01-01

350

An Agent-Based Model of Inflammation and Fibrosis Following Particulate Exposure in the Lung  

PubMed Central

Inflammation and airway remodeling occur in a variety of airway diseases. Modeling aspects of the inflammatory and fibrotic processes following repeated exposure to particulate matter may provide insights into a spectrum of airway diseases, as well as prevention/treatment strategies. An agent-based model (ABM) was created to examine the response of an abstracted population of inflammatory cells (nominally macrophages, but possibly including other inflammatory cells such as lymphocytes) and cells involved in remodeling (nominally fibroblasts) to particulate exposure. The model focused on a limited number of relevant interactions, specifically those among macrophages, fibroblasts, a pro-inflammatory cytokine (TNF-?), an anti-inflammatory cytokine (TGF-?1), collagen deposition, and tissue damage. The model yielded three distinct states that were equated with (1) self-resolving inflammation and a return to baseline, (2) a pro-inflammatory process of localized tissue damage and fibrosis, and (3) elevated pro- and anti-inflammatory cytokines, persistent tissue damage, and fibrosis outcomes. Experimental results consistent with these predicted states were observed in histology sections of lung tissue from mice exposed to particulate matter. Systematic in silico studies suggested that the development of each state depended primarily upon the degree and duration of exposure. Thus, a relatively simple ABM resulted in several, biologically feasible, emergent states, suggesting that the model captures certain salient features of inflammation following exposure of the lung to particulate matter. This ABM may hold future utility in the setting of airway disease resulting from inflammation and fibrosis following particulate exposure.

Brown, Bryan N.; Price, Ian M.; Toapanta, Franklin R.; DeAlmeida, Dilhari R.; Wiley, Clayton A.; Ross, Ted M.; Oury, Tim D.; Vodovotz, Yoram

2011-01-01

351

Sinonasal Cancer and Occupational Exposure in a Population-Based Registry  

PubMed Central

We examined occupational exposures among subjects with sinonasal cancer (SNC) recorded in a population-based registry in the Lombardy Region, the most populated and industrialized Italian region. The registry collects complete clinical information and exposure to carcinogens regarding all SNC cases occurring in the population of the region. In the period 2008–2011, we recorded 210 SNC cases (137 men, 73 women). The most frequent occupational exposures were to wood (44 cases, 21.0%) and leather dust (29 cases, 13.8%), especially among men: 39 cases (28.5%) to wood and 23 cases (16.8%) to leather dust. Exposure to other agents was infrequent (<2%). Among 62 subjects with adenocarcinoma, 50% had been exposed to wood dust and 30.7% to leather dust. The proportions were around 10% in subjects with squamous cell carcinoma and about 20% for tumors with another histology. The age-standardized rates (×100,000 person-years) were 0.7 in men and 0.3 in women. Complete collection of cases and their occupational history through a specialized cancer registry is fundamental to accurately monitor SNC occurrence in a population and to uncover exposure to carcinogens in different industrial sectors, even those not considered as posing a high risk of SNC, and also in extraoccupational settings.

Mensi, Carolina; Sieno, Claudia; Riboldi, Luciano; Bertazzi, Pier Alberto

2013-01-01

352

The Web as a Baseline: Evaluating the Performance of Unsupervised Web-based Models for a Range of NLP Tasks  

Microsoft Academic Search

Previous work demonstrated that web counts can be used to approximate bigram frequen- cies, and thus should be useful for a wide va- riety of NLP tasks. So far, only two gener- ation tasks (candidate selection for machine translation and confusion-set disambiguation) have been tested using web-scale data sets. The present paper investigates if these results gener- alize to tasks

Mirella Lapata; Frank Keller

2004-01-01

353

The Effectiveness of a Task-Based Instruction Program in Developing the English Language Speaking Skills of Secondary Stage Students  

ERIC Educational Resources Information Center

Communicative tasks are defined as activities in which meaning is primary, there is a goal which needs to be worked toward, there is a real world relationship and the interaction among students is the means for achieving the task outcome. However, it was assumed that adopting communicative tasks alone is not adequate as it leads the learner to…

Torky, Shaimaa Abd EL Fattah

2006-01-01

354

A modular design kit for task-adaptable low-cost robots based on BaPaMan design  

NASA Astrophysics Data System (ADS)

This paper discusses the redesign of a binary parallel manipulator named BaPaMan (Binary Actuated Parallel Manipulator). The aim of this work is the improvement of the structures stiffness of BaPaMan. Additionally this paper shows the implementation of a construction kit which allows task-adaptation of low-cost robots based on the BaPaMan structure. BaPaMan is a three degree of freedom (DOF) spatial parallel robot which comprises flexure hinges and Shape Memory Alloy (SMA) actuators to achieve a low-cost design, well suited for easy operation applications. Measurements have shown that this comes at the cost of poor structural stiffness and end effector accuracy. To counter these issues BaPaMan2 and BaPaMan3 have been developed and are elaborated within this work. During the design phase, an empirical FEA is used to improve the flexure hinge performance, which analyses relations between several design parameters and the stiffness of the entire system. Finally, task-adaptation is achieved by using a design methodology and a parametric CAD model for BaPaMan. Besides the paper introduces first applications of the BaPaMan structure and shows future work.

Borchert, G.; Löchte, C.; Carbone, G.; Raatz, A.

2013-03-01

355

Functional near-infrared spectroscopy-based correlates of prefrontal cortical dynamics during a cognitive-motor executive adaptation task.  

PubMed

This study investigated changes in brain hemodynamics, as measured by functional near infrared spectroscopy, during performance of a cognitive-motor adaptation task. The adaptation task involved the learning of a novel visuomotor transformation (a 60° counterclockwise screen-cursor rotation), which required inhibition of a prepotent visuomotor response. A control group experienced a familiar transformation and thus, did not face any executive challenge. Analysis of the experimental group hemodynamic responses revealed that the performance enhancement was associated with a monotonic reduction in the oxygenation level in the prefrontal cortex. This finding confirms and extends functional magnetic resonance imaging and electroencephalography studies of visuomotor adaptation and learning. The changes in prefrontal brain activation suggest an initial recruitment of frontal executive functioning to inhibit prepotent visuomotor mappings followed by a progressive de-recruitment of the same prefrontal regions. The prefrontal hemodynamic changes observed in the experimental group translated into enhanced motor performance revealed by a reduction in movement time, movement extent, root mean square error and the directional error. These kinematic adaptations are consistent with the acquisition of an internal model of the novel visuomotor transformation. No comparable change was observed in the control group for either the hemodynamics or for the kinematics. This study (1) extends our understanding of the frontal executive processes from the cognitive to the cognitive-motor domain and (2) suggests that optical brain imaging can be employed to provide hemodynamic based-biomarkers to assess and monitor the level of adaptive cognitive-motor performance. PMID:23847489

Gentili, Rodolphe J; Shewokis, Patricia A; Ayaz, Hasan; Contreras-Vidal, José L

2013-01-01

356

Functional near-infrared spectroscopy-based correlates of prefrontal cortical dynamics during a cognitive-motor executive adaptation task  

PubMed Central

This study investigated changes in brain hemodynamics, as measured by functional near infrared spectroscopy, during performance of a cognitive-motor adaptation task. The adaptation task involved the learning of a novel visuomotor transformation (a 60° counterclockwise screen-cursor rotation), which required inhibition of a prepotent visuomotor response. A control group experienced a familiar transformation and thus, did not face any executive challenge. Analysis of the experimental group hemodynamic responses revealed that the performance enhancement was associated with a monotonic reduction in the oxygenation level in the prefrontal cortex. This finding confirms and extends functional magnetic resonance imaging and electroencephalography studies of visuomotor adaptation and learning. The changes in prefrontal brain activation suggest an initial recruitment of frontal executive functioning to inhibit prepotent visuomotor mappings followed by a progressive de-recruitment of the same prefrontal regions. The prefrontal hemodynamic changes observed in the experimental group translated into enhanced motor performance revealed by a reduction in movement time, movement extent, root mean square error and the directional error. These kinematic adaptations are consistent with the acquisition of an internal model of the novel visuomotor transformation. No comparable change was observed in the control group for either the hemodynamics or for the kinematics. This study (1) extends our understanding of the frontal executive processes from the cognitive to the cognitive-motor domain and (2) suggests that optical brain imaging can be employed to provide hemodynamic based-biomarkers to assess and monitor the level of adaptive cognitive-motor performance.

Gentili, Rodolphe J.; Shewokis, Patricia A.; Ayaz, Hasan; Contreras-Vidal, Jose L.

2013-01-01

357

Decomposing Decision Components in the Stop-signal Task: A Model-based Approach to Individual Differences in Inhibitory Control.  

PubMed

The stop-signal task, in which participants must inhibit prepotent responses, has been used to identify neural systems that vary with individual differences in inhibitory control. To explore how these differences relate to other aspects of decision making, a drift-diffusion model of simple decisions was fitted to stop-signal task data from go trials to extract measures of caution, motor execution time, and stimulus processing speed for each of 123 participants. These values were used to probe fMRI data to explore individual differences in neural activation. Faster processing of the go stimulus correlated with greater activation in the right frontal pole for both go and stop trials. On stop trials, stimulus processing speed also correlated with regions implicated in inhibitory control, including the right inferior frontal gyrus, medial frontal gyrus, and BG. Individual differences in motor execution time correlated with activation of the right parietal cortex. These findings suggest a robust relationship between the speed of stimulus processing and inhibitory processing at the neural level. This model-based approach provides novel insight into the interrelationships among decision components involved in inhibitory control and raises interesting questions about strategic adjustments in performance and inhibitory deficits associated with psychopathology. PMID:24405185

White, Corey N; Congdon, Eliza; Mumford, Jeanette A; Karlsgodt, Katherine H; Sabb, Fred W; Freimer, Nelson B; London, Edythe D; Cannon, Tyrone D; Bilder, Robert M; Poldrack, Russell A

2014-08-01

358

Reward-based decision making and electrodermal responding by young children with autism spectrum disorders during a gambling task.  

PubMed

In this study, we explore reward-based decision making and electrodermal responding (EDR) among children with autism spectrum disorder (ASD) during a children's gambling task. In addition, we examine whether individual behavioral and EDR responses predict social communication, repetitive symptoms, parent reports of executive function, and behavioral challenges. The ability to form advantageous strategies for long-term gain is of interest for children with ASD, who exhibit both difficulty with executive function and atypical responses to reward. Twenty-one children ages 6-7 years with ASD and no intellectual disability, and 21 age- and IQ-matched typically developing children participated. Both groups exhibited a similar pattern of gambling selections, but children with ASD showed less knowledge of the reward contingencies of the decks after playing. In addition, although EDR was similar between groups in anticipation of selections, children with ASD exhibited greater EDR during feedback about rewards as the task progressed. Children with ASD who exhibited the greatest increases in EDR were more likely to exhibit repetitive symptoms, particularly rituals and the need for sameness, as well as internalizing behaviors and reduced executive function in other settings. PMID:23893954

Faja, Susan; Murias, Michael; Beauchaine, Theodore P; Dawson, Geraldine

2013-12-01

359

Welding technology transfer task/laser based weld joint tracking system for compressor girth welds  

NASA Technical Reports Server (NTRS)

Sensors to control and monitor welding operations are currently being developed at Marshall Space Flight Center. The laser based weld bead profiler/torch rotation sensor was modified to provide a weld joint tracking system for compressor girth welds. The tracking system features a precision laser based vision sensor, automated two-axis machine motion, and an industrial PC controller. The system benefits are elimination of weld repairs caused by joint tracking errors which reduces manufacturing costs and increases production output, simplification of tooling, and free costly manufacturing floor space.

Looney, Alan

1991-01-01

360

Potential for exposure to engineered nanoparticles from nanotechnology-based consumer spray products  

PubMed Central

The potential for human exposure to engineered nanoparticles due to the use of nanotechnology-based consumer sprays (categorized as such by the Nanotechnology Consumer Products Inventory) is examined along with analogous products, which are not specified as nanotechnology-based (regular products). Photon correlation spectroscopy was used to obtain particle size distributions in the initial liquid products. Transmission electron microscopy was used to determine particle size, shape, and agglomeration of the particles. Realistic application of the spray products near the human breathing zone characterized airborne particles that are released during use of the sprays. Aerosolization of sprays with standard nebulizers was used to determine their potential for inhalation exposure. Electron microscopy detected the presence of nanoparticles in some nanotechnology-based sprays as well as in several regular products, whereas the photon correlation spectroscopy indicated the presence of particles <100 nm in all investigated products. During the use of most nanotechnology-based and regular sprays, particles ranging from 13 nm to 20 ?m were released, indicating that they could he inhaled and consequently deposited in all regions of the respiratory system. The results indicate that exposures to nanoparticles as well as micrometer-sized particles can be encountered owing to the use of nanotechnology-based sprays as well as regular spray products.

NAZARENKO, YEVGEN; HAN, TAE WON; LIOY, PAUL J.; MAINELIS, GEDIMINAS

2014-01-01

361

CENTRALIZED VERSUS MARKET-BASED APPROACHES TO MOBILE TASK ALLOCATION PROBLEM: STATE-OF-THE- ART  

Microsoft Academic Search

Centralized approach has been adopted for finding solutions to resource allocation problems (RAPs) in many real-life applications. On the other hand, market-based approach has been proposed as an alternative to solve the problem due to recent advancement in ICT technologies. In spite of the existence of some efforts to review the pros and cons of each approach in RAPs, the

Karim Al-Yafi; Habin Lee

2009-01-01

362

Task-Based Navigation of a Taxonomy Interface to a Digital Repository  

ERIC Educational Resources Information Center

Introduction: This is a study of hierarchical navigation; how users browse a taxonomy-based interface to an organizational repository to locate information resources. The study is part of a project to develop a taxonomy for an library and information science department to organize resources and support user browsing in a digital repository.…

Khoo, Christopher S. G.; Wang, Zhonghong; Chaudhry, Abdus Sattar

2012-01-01

363

Confronting prospective teachers' ideas of evolution and scientific inquiry using technology and inquiry-based tasks  

Microsoft Academic Search

This study addresses the need for research in three areas: (1) teachers' understandings of scientific inquiry; (2) conceptual understandings of evolutionary processes; and (3) technology-enhanced instruction using an inquiry approach. The purpose of this study was to determine in what ways The Galapagos Finches software-based materials created a context for learning and teaching about the nature of scientific knowledge and

Barbara A. Crawford; Carla Zembal-Saul; Danusa Munford; Patricia Friedrichsen

2005-01-01

364

Feasibility of performing space surveillance tasks with a proposed space-based optical architecture  

Microsoft Academic Search

Under ESA contract an industrial consortium including Aboa Space Research Oy (ASRO), the Astronomical Institute of the University of Bern (AIUB), and the Dutch National Aerospace Laboratory (NLR), proposed the observation concept, developed a suitable sensor architecture, and assessed the performance of a space-based optical (SBO) telescope in 2005. The goal of the SBO instrumentation was to analyse how the

Tim Flohrer; Holger Krag; Heiner Klinkrad; Thomas Schildknecht

2010-01-01

365

Feasibility of performing space surveillance tasks with a proposed space-based optical architecture  

Microsoft Academic Search

Under ESA contract an industrial consortium including Aboa Space Research Oy (ASRO), the Astronomical Institute of the University of Bern (AIUB), and the Dutch National Aerospace Laboratory (NLR), proposed the observation concept, developed a suitable sensor architecture, and assessed the performance of a space-based optical (SBO) telescope in 2005. The goal of the SBO study was to analyse how the

T. Flohrer; H. Krag; H. Klinkrad; T. Schildknecht

2011-01-01

366

Web-Based Learning: How Task Scaffolding and Web Site Design Support Knowledge Acquisition  

ERIC Educational Resources Information Center

Using WebQuests for inquiry-based learning represents a higher-order use of technology requiring students to exercise information seeking, analyzing, and synthesizing strategies. This research was designed to obtain a better understanding of how to enhance the pedagogical effectiveness of WebQuests and of how students interact with the various…

MacGregor, S. Kim; Lou, Yiping

2005-01-01

367

Information-based sensor tasking wireless body area networks in U-health systems  

Microsoft Academic Search

In this paper, we focus on the problem of constructing an information gain model for stroke prevention in Ubiquitous Healthcare (U-Health) Wireless Body Area Networks (WBANs). We have constructed an information-based probabilistic relation model among the key indicators and sequenced their data gathering priority and precedence in the WBAN. Then, we constructed a cost function over the energy expenditure involved

Hui Wang; Hyeok-soo Choi; Nazim Agoulmine; M. Jamal Deen; James Won-Ki Hong

2010-01-01

368

Application Of Eigenstrugture Based Bispectrum Estimation: Eeg Wave Coupling In Cognitive Tasks  

Microsoft Academic Search

An orthogonal subspace-based approach for two dimensional sinusoids can be applied to the bispectrum and the estimation of the frequencies of quadratically phase coupled sinusoids. The method determines peaks in the bispectral domain by the direct partitioning of noise and signal subspaces without the need for transfer function parametrization. It can be used for determining domainant fre- quencies involved in

David L. Sherman; Michael D. Zoltowski

1989-01-01

369

Laboratory-Based and Autobiographical Retrieval Tasks Differ Substantially in Their Neural Substrates  

ERIC Educational Resources Information Center

In designing experiments to investigate retrieval of event memory, researchers choose between utilizing laboratory-based methods (in which to-be-remembered materials are presented to participants) and autobiographical approaches (in which the to-be-remembered materials are events from the participant's pre-experimental life). In practice, most…

McDermott, Kathleen B.; Szpunar, Karl K.; Christ, Shawn E.

2009-01-01

370

Elementary Students' Learning of Materials Science Practices through Instruction Based on Engineering Design Tasks  

ERIC Educational Resources Information Center

Materials science, which entails the practices of selecting, testing, and characterizing materials, is an important discipline within the study of matter. This paper examines how third grade students' materials science performance changes over the course of instruction based on an engineering design challenge. We conducted a case study of nine…

Wendell, Kristen Bethke; Lee, Hee-Sun

2010-01-01

371

Exposure fusion based on steerable pyramid for displaying high dynamic range scenes  

NASA Astrophysics Data System (ADS)

Currently, most exposure fusion algorithms are put forward on the assumption that the source images are aligned prior to fusion. As a result, some artifacts, such as haloing, may be caused due to the slight misalignment in the source images. In order to reduce the influence induced by the misalignment, a novel shift-invariant and rotation-invariant steerable pyramid-based exposure fusion (SPBEF) algorithm is proposed. It can combine multiple color images of a scene with different exposures to one image with high quality. First, instead of processing of R, G, and B channels separately, the chrominance information of the scene is obtained by the average image of the median two images. The strategy can greatly reduce the computational complexity. Second, the luminance images of source images are then transferred to frequency domain and are fused to one luminance image using different fusion rules in different frequencies. In this process, fusion is performed in a hierarchical fashion. Last, the final color image is generated by combining the data of the fused luminance image and the chrominance information. Experiments show that SPBEF can give comparative or even better results compared to other exposure fusion algorithms, as well as other traditional pyramid-based fusion algorithms

Wang, Jinhua; Xu, De; Li, Bing

2009-11-01

372

Task Description Language  

NASA Technical Reports Server (NTRS)

Task Description Language (TDL) is an extension of the C++ programming language that enables programmers to quickly and easily write complex, concurrent computer programs for controlling real-time autonomous systems, including robots and spacecraft. TDL is based on earlier work (circa 1984 through 1989) on the Task Control Architecture (TCA). TDL provides syntactic support for hierarchical task-level control functions, including task decomposition, synchronization, execution monitoring, and exception handling. A Java-language-based compiler transforms TDL programs into pure C++ code that includes calls to a platform-independent task-control-management (TCM) library. TDL has been used to control and coordinate multiple heterogeneous robots in projects sponsored by NASA and the Defense Advanced Research Projects Agency (DARPA). It has also been used in Brazil to control an autonomous airship and in Canada to control a robotic manipulator.

Simmons, Reid; Apfelbaum, David

2005-01-01

373

Task-based parallel H.264 video encoding for explicit communication architectures  

Microsoft Academic Search

Future multi-core processors will necessitate ex- ploitation of fine-grain, architecture-independent parallelism from applications to utilize many cores with relatively small local memories. We use c264, an end-to-end H.264 video encoder for the Cell processor based on x264, to show that exploiting fine- grain parallelism remains challenging and requires significant advancement in runtime support. Our implementation of c264 achieves speedup between

Michail Alvanos; George Tzenakis; Dimitrios S. Nikolopoulos; Angelos Bilas

2011-01-01

374

Context-based automatic reconstruction and texturing of 3D urban terrain for quick-response tasks  

NASA Astrophysics Data System (ADS)

Highly detailed 3D urban terrain models are the base for quick response tasks with indispensable human participation, e.g., disaster management. Thus, it is important to automate and accelerate the process of urban terrain modeling from sensor data such that the resulting 3D model is semantic, compact, recognizable, and easily usable for training and simulation purposes. To provide essential geometric attributes, buildings and trees must be identified among elevated objects in digital surface models. After building ground-plan estimation and roof details analysis, images from oblique airborne imagery are used to cover building faces with up-to-date texture thus achieving a better recognizability of the model. The three steps of the texturing procedure are sensor pose estimation, assessment of polygons projected into the images, and texture synthesis. Free geographic data, providing additional information about streets, forest areas, and other topographic object types, suppress false alarms and enrich the reconstruction results.

Bulatov, Dimitri; Häufel, Gisela; Meidow, Jochen; Pohl, Melanie; Solbrig, Peter; Wernerus, Peter

2014-07-01

375

Variable sensitivity in unsupervised clustering tasks with an n-tuple-based self-organising neural network.  

PubMed

This article investigates the application of the SOLNN (Self-Organising Logic Neural Network) n-tuple-based network to character recognition and image segmentation clustering tasks, where the classes consist of a large number of distinct sub-classes. It is shown that the SOLNN clustering performance and node utilisation are both improved by virtue of the distribution constraint mechanism. The clustering results are supported by means of a detailed analysis of the characteristics of each pattern space. This analysis, coupled with comparative results obtained using other self-organising models, illustrates that the SOLNN clusters the patterns in accordance to the pattern space characteristics and thus is well-suited to clustering complex datasets. PMID:10939344

Tambouratzis, G

2000-04-01

376

Exploring the Synergism of a Multiple Auction-Based Task Allocation Scheme for Power-Aware Intrusion Detection in Wireless Ad-Hoc Networks  

Microsoft Academic Search

In this paper we propose a multiple auction-based task allocation scheme for identifying and distributing network-monitoring and decision-making tasks amongst the various nodes in a wireless ad-hoc network for performing power-aware intrusion detection. By iteratively performing this scheme we show that a power-optimal solution can be reached in a bandwidth constrained and energy-preserving network with only the nodes capable of

T. Srinivasan; R. Chandrasekar; Vivek Vijaykumar; V. Mahadevan; A. Meyyappan; M. Nivedita

2006-01-01

377

Long-term methionine exposure induces memory impairment on inhibitory avoidance task and alters acetylcholinesterase activity and expression in zebrafish (Danio rerio).  

PubMed

Hypermethioninemic patients exhibit a variable degree of neurological dysfunction. However, the mechanisms involved in these alterations have not been completely clarified. Cholinergic system has been implicated in many physiological processes, including cognitive performances, as learning, and memory. Parameters of cholinergic signaling have already been characterized in zebrafish brain. Since zebrafish is a small freshwater teleost which is a vertebrate model for modeling behavioral and functional parameters related to human pathogenesis and for clinical treatment screenings, in the present study we investigated the effects of short- and long-term methionine exposure on cognitive impairment, AChE activity and gene expression in zebrafish. For the studies, animals were exposed at two methionine concentrations (1.5 and 3.0 mM) during 1 h or 7 days (short- or long-term treatments, respectively). We observed a significant increase in AChE activity of zebrafish brain membranes after long-term methionine exposure at 3.0 mM. However, AChE gene expression decreased significantly in both concentrations tested after 7 days of treatment, suggesting that post-translational events are involved in the enhancement of AChE activity. Methionine treatment induces memory deficit in zebrafish after long-term exposure to this amino acid, which could be related, at least in part, with cognitive impairment observed in hypermethioninemia. Therefore, the results here presented raise a new perspective to use the zebrafish as a complementary vertebrate model for studying inborn errors of metabolism, which may help to better understand the pathophysiology of this disease. PMID:22437435

Vuaden, Fernanda Cenci; Savio, Luiz Eduardo B; Piato, Angelo L; Pereira, Talita C; Vianna, Mônica R; Bogo, Maurício R; Bonan, Carla D; Wyse, Angela T S

2012-07-01

378

Interest contagion in violation-of-expectation-based false-belief tasks.  

PubMed

In the debate about how to interpret Violation-of-Expectation (VoE) based false-belief experiments, it has been suggested that infants are predicting the actions of the agent based on more or less sophisticated cognitive means. We present an alternative, more parsimonious interpretation, exploring the possibility that the infants' reactions are not governed by rational expectation but rather of memory strength due to differences in the allocation of cognitive resources earlier in the experiment. Specifically, it is argued that (1) infants' have a tendency to find more interest in events that observed agents are attending to as opposed to unattended events ("interest contagion"), (2) the object-location configurations that result from such interesting events are remembered more strongly by the infants, and (3) the VoE contrast arises as a consequence of the difference in memory strength between more and less interesting object-location configurations. We discuss two published experiments, one which we argue that our model can explain (Kovács etal., 2010), and one which we argue cannot be readily explained by our model (Onishi and Baillargeon, 2005). PMID:24523706

Falck, Andreas; Brinck, Ingar; Lindgren, Magnus

2014-01-01

379

Interest contagion in violation-of-expectation-based false-belief tasks  

PubMed Central

In the debate about how to interpret Violation-of-Expectation (VoE) based false-belief experiments, it has been suggested that infants are predicting the actions of the agent based on more or less sophisticated cognitive means. We present an alternative, more parsimonious interpretation, exploring the possibility that the infants’ reactions are not governed by rational expectation but rather of memory strength due to differences in the allocation of cognitive resources earlier in the experiment. Specifically, it is argued that (1) infants’ have a tendency to find more interest in events that observed agents are attending to as opposed to unattended events (“interest contagion”), (2) the object-location configurations that result from such interesting events are remembered more strongly by the infants, and (3) the VoE contrast arises as a consequence of the difference in memory strength between more and less interesting object-location configurations. We discuss two published experiments, one which we argue that our model can explain (Kovács etal., 2010), and one which we argue cannot be readily explained by our model (Onishi and Baillargeon, 2005).

Falck, Andreas; Brinck, Ingar; Lindgren, Magnus

2014-01-01

380

A size-based probabilistic assessment of PCB exposure from Lake Michigan fish consumption  

SciTech Connect

The state of Wisconsin has recently issued a fish consumption advisory that includes suggested consumption rates for Lake Michigan fish, based on fish size and PCB concentration. To evaluate the size-based exposure risk from Lake Michigan fish consumption, the authors estimated PCB exposure probabilities for five Lake Michigan fish species using two Bayesian models. The models confirm that very few individuals of any of the five species are likely to have PCB concentrations low enough to fall into the category in which consumption is unrestricted. Among smaller fish (<50 cm), brown trout have the highest PCB levels, while lake trout are the most contaminated among larger fish (>60 cm). Eating meals from multiple individuals of some species results in a high probability that at least one of the meals will exceed 1.9 mg/kg, the upper PCB concentration recommended for consumption in the advisory.

Stow, C.A. [Duke Univ., Durham, NC (United States). Nicholas School of the Environment] [Duke Univ., Durham, NC (United States). Nicholas School of the Environment; Qian, S.S. [Portland State Univ., OR (United States)] [Portland State Univ., OR (United States)

1998-08-01

381

Combining group-based exposure therapy with prolonged exposure to treat U.S. Vietnam veterans with PTSD: a case study.  

PubMed

Group-based exposure therapy (GBET) of 16-week duration was developed to treat combat-related posttraumatic stress disorder (PTSD) and decreased PTSD symptoms in 3 noncontrolled open trials with low attrition (0%-5%). Group-based exposure therapy has not produced as much PTSD symptom reduction as Prolonged Exposure (PE) within a U.S. Veterans Affairs PTSD treatment program, although PE had more dropouts (20%). This pilot study was of a model that combined key elements of GBET with components of PE in an effort to increase the effectiveness of a group-based treatment while reducing its length and maintaining low attrition. Twice per week, 8 Vietnam combat veterans with PTSD were treated for 12 weeks, with an intervention that included 2 within-group war trauma presentations per participant, 6 PE style individual imaginal exposure (IE) sessions per participant, daily listening to recorded IE sessions, and daily in vivo exposure exercises. All completed treatment and showed Significant reductions on all measures of PTSD with large effect sizes; 7 participants no longer met PTSD criteria on treating clinician administered interviews and a self-report measure at posttreatment. Significant reductions in depression with large effect sizes and moderate reductions in PTSD-related cognitions were also found. Most gains were maintained 6 months posttreatment. PMID:22965936

Ready, David J; Vega, Edward M; Worley, Virginia; Bradley, Bekh

2012-10-01

382

Temperature elevation in the eye of anatomically based human head models for plane-wave exposures  

Microsoft Academic Search

This study investigated the temperature elevation in the eye of anatomically based human head models for plane-wave exposures. The finite-difference time-domain method is used for analyzing electromagnetic absorption and temperature elevation. The eyes in the anatomic models have average dimensions and weight. Computational results show that the ratio of maximum temperature in the lens to the eye-average SAR (named 'heating

A. Hirata; S. Watanabe; O. Fujiwara; M. Kojima; K. Sasaki; T. Shiozawa

2007-01-01

383

Scheduling Tasks  

Microsoft Academic Search

\\u000a In this book, you’ve learned about various tasks you can perform to keep Ubuntu running smoothly. Although some of these tasks\\u000a require human intervention, many—such as backing up your important files or clearing the clutter from the tmp folder to ensure\\u000a that you always have enough free disk space— can be automated relatively easily by using the methods in this

Emilio Raggi; Keir Thomas; Trevor Parsons; Andy Channelle; Sander Vugt

384

Application of physiologically based pharmacokinetic modeling in setting acute exposure guideline levels for methylene chloride.  

PubMed

Acute exposure guideline levels (AEGLs) are derived to protect the human population from adverse health effects in case of single exposure due to an accidental release of chemicals into the atmosphere. AEGLs are set at three different levels of increasing toxicity for exposure durations ranging from 10 min to 8 h. In the AEGL setting for methylene chloride, specific additional topics had to be addressed. This included a change of relevant toxicity endpoint within the 10-min to 8-h exposure time range from central nervous system depression caused by the parent compound to formation of carboxyhemoglobin (COHb) via biotransformation to carbon monoxide. Additionally, the biotransformation of methylene chloride includes both a saturable step as well as genetic polymorphism of the glutathione transferase involved. Physiologically based pharmacokinetic modeling was considered to be the appropriate tool to address all these topics in an adequate way. Two available PBPK models were combined and extended with additional algorithms for the estimation of the maximum COHb levels. The model was validated and verified with data obtained from volunteer studies. It was concluded that all the mentioned topics could be adequately accounted for by the PBPK model. The AEGL values as calculated with the model were substantiated by experimental data with volunteers and are concluded to be practically applicable. PMID:16569727

Bos, Peter Martinus Jozef; Zeilmaker, Marco Jacob; van Eijkeren, Jan Cornelis Henri

2006-06-01

385

Development of a fluorescence-based sensor for rapid diagnosis of cyanide exposure.  

PubMed

Although commonly known as a highly toxic chemical, cyanide is also an essential reagent for many industrial processes in areas such as mining, electroplating, and synthetic fiber production. The "heavy" use of cyanide in these industries, along with its necessary transportation, increases the possibility of human exposure. Because the onset of cyanide toxicity is fast, a rapid, sensitive, and accurate method for the diagnosis of cyanide exposure is necessary. Therefore, a field sensor for the diagnosis of cyanide exposure was developed based on the reaction of naphthalene dialdehyde, taurine, and cyanide, yielding a fluorescent ?-isoindole. An integrated cyanide capture "apparatus", consisting of sample and cyanide capture chambers, allowed rapid separation of cyanide from blood samples. Rabbit whole blood was added to the sample chamber, acidified, and the HCN gas evolved was actively transferred through a stainless steel channel to the capture chamber containing a basic solution of naphthalene dialdehyde (NDA) and taurine. The overall analysis time (including the addition of the sample) was <3 min, the linear range was 3.13-200 ?M, and the limit of detection was 0.78 ?M. None of the potential interferents investigated (NaHS, NH4OH, NaSCN, and human serum albumin) produced a signal that could be interpreted as a false positive or a false negative for cyanide exposure. Most importantly, the sensor was 100% accurate in diagnosing cyanide poisoning for acutely exposed rabbits. PMID:24383576

Jackson, Randy; Oda, Robert P; Bhandari, Raj K; Mahon, Sari B; Brenner, Matthew; Rockwood, Gary A; Logue, Brian A

2014-02-01

386

Understanding fragrance allergy using an exposure-based risk assessment approach.  

PubMed

Conducting a sound skin sensitization risk assessment prior to the introduction of new ingredients and products into the market place is essential. The process by which low-molecular-weight chemicals induce and elicit skin sensitization is dependent on many factors, including the ability of the chemical to penetrate the skin, react with protein, and trigger a cell-mediated immune response. Based on our chemical, cellular and molecular understanding of allergic contact dermatitis, it is possible to carry out a quantitative risk assessment. Specifically, by estimating the exposure to the allergen and its allergenic potency, it is feasible to assess quantitatively the sensitization risk of an ingredient in a particular product type. This paper focuses on applying exposure-based risk assessment tools to understanding fragrance allergy for 2 hypothetical products containing the fragrance allergen cinnamic aldehyde. The risk assessment process predicts that an eau de toilette leave-on product containing 1000 ppm or more cinnamic aldehyde would pose an unacceptable risk of induction of skin sensitization, while a shampoo, containing the same level of cinnamic aldehyde, would pose an acceptable risk of induction of skin sensitization, based on limited exposure to the ingredient from a rinse-off product application. PMID:11846748

Gerberick, G F; Robinson, M K; Felter, S P; White, I R; Basketter, D A

2001-12-01

387

Probabilistic modeling of percutaneous absorption for risk-based exposure assessments and transdermal drug delivery.  

SciTech Connect

Chemical transport through human skin can play a significant role in human exposure to toxic chemicals in the workplace, as well as to chemical/biological warfare agents in the battlefield. The viability of transdermal drug delivery also relies on chemical transport processes through the skin. Models of percutaneous absorption are needed for risk-based exposure assessments and drug-delivery analyses, but previous mechanistic models have been largely deterministic. A probabilistic, transient, three-phase model of percutaneous absorption of chemicals has been developed to assess the relative importance of uncertain parameters and processes that may be important to risk-based assessments. Penetration routes through the skin that were modeled include the following: (1) intercellular diffusion through the multiphase stratum corneum; (2) aqueous-phase diffusion through sweat ducts; and (3) oil-phase diffusion through hair follicles. Uncertainty distributions were developed for the model parameters, and a Monte Carlo analysis was performed to simulate probability distributions of mass fluxes through each of the routes. Sensitivity analyses using stepwise linear regression were also performed to identify model parameters that were most important to the simulated mass fluxes at different times. This probabilistic analysis of percutaneous absorption (PAPA) method has been developed to improve risk-based exposure assessments and transdermal drug-delivery analyses, where parameters and processes can be highly uncertain.

Ho, Clifford Kuofei

2004-06-01

388

Base camp personnel exposure to particulate matter during wildland fire suppression activities.  

PubMed

Wildland fire base camps commonly house thousands of support personnel for weeks at a time. The selection of the location of these base camps is largely a strategic decision that incorporates many factors, one of which is the potential impact of biomass smoke from the nearby fire event. Biomass smoke has many documented adverse health effects due, primarily, to high levels of fine particulate matter (PM(2.5)). Minimizing particulate matter exposure to potentially susceptible individuals working as support personnel in the base camp is vital. In addition to smoke from nearby wildland fires, base camp operations have the potential to generate particulate matter via vehicle emissions, dust, and generator use. We monitored particulate matter at three base camps during the fire season of 2009 in Washington, Oregon, and California. During the sampling events, 1-min time-weighted averages of PM(2.5) and particle counts from three size fractions (0.3-0.5 microns, 0.5-1.0 microns, and 1.0-2.5 microns) were measured. Results showed that all PM size fractions (as well as overall PM(2.5) concentrations) were higher during the overnight hours, a trend that was consistent at all camps. Our results provide evidence of camp-based, site-specific sources of PM(2.5) that could potentially exceed the contributions from the nearby wildfire. These exposures could adversely impact wildland firefighters who sleep in the camp, as well as the camp support personnel, who could include susceptible individuals. A better understanding of the sources and patterns of poor air quality within base camps would help to inform prevention strategies to reduce personnel exposures. PMID:22364357

McNamara, Marcy L; Semmens, Erin O; Gaskill, Steven; Palmer, Charles; Noonan, Curtis W; Ward, Tony J

2012-01-01

389

The double task of preventing malnutrition and overweight: a quasi-experimental community-based trial  

PubMed Central

Background The Maternal-Child Pastoral is a volunteer-based community organization of the Dominican Republic that works with families to improve child survival and development. A program that promotes key practices of maternal and child care through meetings with pregnant women and home visits to promote child growth and development was designed and implemented. This study aims to evaluate the impact of the program on nutritional status indicators of children in the first two years of age. Methods A quasi-experimental design was used, with groups paired according to a socioeconomic index, comparing eight geographical areas of intervention with eight control areas. The intervention was carried out by lay health volunteers. Mothers in the intervention areas received home visits each month and participated in a group activity held biweekly during pregnancy and monthly after birth. The primary outcomes were length and body mass index for age. Statistical analyses were based on linear and logistic regression models. Results 196 children in the intervention group and 263 in the control group were evaluated. The intervention did not show statistically significant effects on length, but point estimates found were in the desired direction: mean difference 0.21 (95%CI ?0.02; 0.44) for length-for-age Z-score and OR 0.50 (95%CI 0.22; 1.10) for stunting. Significant reductions of BMI-for-age Z-score (?0.31, 95%CI ?0.49; -0.12) and of BMI-for-age > 85th percentile (0.43, 95%CI 0.23; 0.77) were observed. The intervention showed positive effects in some indicators of intermediary factors such as growth monitoring, health promotion activities, micronutrient supplementation, exclusive breastfeeding and complementary feeding. Conclusions Despite finding effect measures pointing to effects in the desired direction related to malnutrition, we could only detect a reduction in the risk of overweight attributable to the intervention. The findings related to obesity prevention may be of interest in the context of the nutritional transition. Given the size of this study, the results are encouraging and we believe a larger study is warranted.

2013-01-01

390

Confronting prospective teachers' ideas of evolution and scientific inquiry using technology and inquiry-based tasks  

NASA Astrophysics Data System (ADS)

This study addresses the need for research in three areas: (1) teachers' understandings of scientific inquiry; (2) conceptual understandings of evolutionary processes; and (3) technology-enhanced instruction using an inquiry approach. The purpose of this study was to determine in what ways The Galapagos Finches software-based materials created a context for learning and teaching about the nature of scientific knowledge and evolutionary concepts. The research used a design experiment in which researchers significantly modified a secondary science methods course. The multiple data sources included: audiotaped conversations of two focus pairs of participants as they interacted with the software; written pre- and posttests on concepts of natural selection of the 21 prospective teachers; written pre- and posttests on views of the nature of science; three e-mail journal questions; and videotaped class discussions. Findings indicate that prospective teachers initially demonstrated alternative understandings of evolutionary concepts; there were uninformed understandings of the nature of scientific inquiry; there was little correlation between understandings and disciplines; and even the prospective teachers with research experience failed to understand the diverse methods used by scientists. Following the module there was evidence of enhanced understandings through metacognition, and the potential for interactive software to provide promising context for enhancing content understandings.

Crawford, Barbara A.; Zembal-Saul, Carla; Munford, Danusa; Friedrichsen, Patricia

2005-08-01

391

Cognitive task analysis-based design and authoring software for simulation training.  

PubMed

The development of more effective medical simulators requires a collaborative team effort where three kinds of expertise are carefully coordinated: (1) exceptional medical expertise focused on providing complete and accurate information about the medical challenges (i.e., critical skills and knowledge) to be simulated; (2) instructional expertise focused on the design of simulation-based training and assessment methods that produce maximum learning and transfer to patient care; and (3) software development expertise that permits the efficient design and development of the software required to capture expertise, present it in an engaging way, and assess student interactions with the simulator. In this discussion, we describe a method of capturing more complete and accurate medical information for simulators and combine it with new instructional design strategies that emphasize the learning of complex knowledge. Finally, we describe three different types of software support (Development/Authoring, Run Time, and Post Run Time) required at different stages in the development of medical simulations and the instructional design elements of the software required at each stage. We describe the contributions expected of each kind of software and the different instructional control authoring support required. PMID:24084300

Munro, Allen; Clark, Richard E

2013-10-01

392

ECONOMIC EVALUATION OF CO2 SEQUESTRATION TECHNOLOGIES TASK 4, BIOMASS GASIFICATION-BASED PROCESSING  

SciTech Connect

Biomass derived energy currently accounts for about 3 quads of total primary energy use in the United States. Of this amount, about 0.8 quads are used for power generation. Several biomass energy production technologies exist today which contribute to this energy mix. Biomass combustion technologies have been the dominant source of biomass energy production, both historically and during the past two decades of expansion of modern biomass energy in the U. S. and Europe. As a research and development activity, biomass gasification has usually been the major emphasis as a method of more efficiently utilizing the energy potential of biomass, particularly wood. Numerous biomass gasification technologies exist today in various stages of development. Some are simple systems, while others employ a high degree of integration for maximum energy utilization. The purpose of this study is to conduct a technical and economic comparison of up to three biomass gasification technologies, including the carbon dioxide emissions reduction potential of each. To accomplish this, a literature search was first conducted to determine which technologies were most promising based on a specific set of criteria. During this reporting period, the technical and economic performances of the selected processes were evaluated using computer models and available literature. The results of these evaluations are summarized in this report.

Martha L. Rollins; Les Reardon; David Nichols; Patrick Lee; Millicent Moore; Mike Crim; Robert Luttrell; Evan Hughes

2002-04-01

393

ECONOMIC EVALUATION OF CO2 SEQUESTRATION TECHNOLOGIES TASK 4, BIOMASS GASIFICATION-BASED PROCESSING  

SciTech Connect

Biomass derived energy currently accounts for about 3 quads of total primary energy use in the United States. Of this amount, about 0.8 quads are used for power generation. Several biomass energy production technologies exist today which contribute to this energy mix. Biomass combustion technologies have been the dominant source of biomass energy production, both historically and during the past two decades of expansion of modern biomass energy in the U. S. and Europe. As a research and development activity, biomass gasification has usually been the major emphasis as a method of more efficiently utilizing the energy potential of biomass, particularly wood. Numerous biomass gasification technologies exist today in various stages of development. Some are simple systems, while others employ a high degree of integration for maximum energy utilization. The purpose of this study is to conduct a technical and economic comparison of up to three biomass gasification technologies, including the carbon dioxide emissions reduction potential of each. To accomplish this, a literature search was first conducted to determine which technologies were most promising based on a specific set of criteria. The technical and economic performances of the selected processes were evaluated using computer models and available literature. Using these results, the carbon sequestration potential of the three technologies was then evaluated. The results of these evaluations are given in this final report.

Martha L. Rollins; Les Reardon; David Nichols; Patrick Lee; Millicent Moore; Mike Crim; Robert Luttrell; Evan Hughes

2002-06-01

394

Task-Based Core-Periphery Organization of Human Brain Dynamics  

PubMed Central

As a person learns a new skill, distinct synapses, brain regions, and circuits are engaged and change over time. In this paper, we develop methods to examine patterns of correlated activity across a large set of brain regions. Our goal is to identify properties that enable robust learning of a motor skill. We measure brain activity during motor sequencing and characterize network properties based on coherent activity between brain regions. Using recently developed algorithms to detect time-evolving communities, we find that the complex reconfiguration patterns of the brain's putative functional modules that control learning can be described parsimoniously by the combined presence of a relatively stiff temporal core that is composed primarily of sensorimotor and visual regions whose connectivity changes little in time and a flexible temporal periphery that is composed primarily of multimodal association regions whose connectivity changes frequently. The separation between temporal core and periphery changes over the course of training and, importantly, is a good predictor of individual differences in learning success. The core of dynamically stiff regions exhibits dense connectivity, which is consistent with notions of core-periphery organization established previously in social networks. Our results demonstrate that core-periphery organization provides an insightful way to understand how putative functional modules are linked. This, in turn, enables the prediction of fundamental human capacities, including the production of complex goal-directed behavior.

Bassett, Danielle S.; Wymbs, Nicholas F.; Rombach, M. Puck; Porter, Mason A.; Mucha, Peter J.; Grafton, Scott T.

2013-01-01

395

Preoperative Mapping of the Sensorimotor Cortex: Comparative Assessment of Task-Based and Resting-State fMRI  

PubMed Central

Resting state fMRI (rs-fMRI) has recently been considered as a possible complement or alternative to task-based fMRI (tb-fMRI) for presurgical mapping. However, evidence of its usefulness remains scant, because existing studies have investigated relatively small samples and focused primarily on qualitative evaluation. The aim of this study is to investigate the clinical usefulness of rs-fMRI in the context of presurgical mapping of motor functions, and in particular to determine the degree of correspondence with tb-fMRI which, while not a gold-standard, is commonly used in preoperative setting. A group of 13 patients with lesions close to the sensorimotor cortex underwent rs-fMRI and tb-fMRI to localize the hand, foot and mouth motor areas. We assessed quantitatively the degree of correspondence between multiple rs-fMRI analyses (independent-component and seed-based analyses) and tb-fMRI, with reference to sensitivity and specificity of rs-fMRI with respect to tb-fMRI, and centre-of-mass distances. Agreement with electro-cortical stimulation (ECS) was also investigated, and a traditional map thresholding approach based on agreement between two experienced operators was compared to an automatic threshold determination method. Rs-fMRI can localize the sensorimotor cortex successfully, providing anatomical specificity for hand, foot and mouth motor subregions, in particular with seed-based analyses. Agreement with tb-fMRI was only partial and rs-fMRI tended to provide larger patterns of correlated activity. With respect to the ECS data available, rs-fMRI and tb-fMRI performed comparably, even though the shortest distance to stimulation points was observed for the latter. Notably, the results of both were on the whole robust to thresholding procedure. Localization performed by rs-fMRI is not equivalent to tb-fMRI, hence rs-fMRI cannot be considered as an outright replacement for tb-fMRI. Nevertheless, since there is significant agreement between the two techniques, rs-fMRI can be considered with caution as a potential alternative to tb-fMRI when patients are unable to perform the task.

Rosazza, Cristina; Aquino, Domenico; D'Incerti, Ludovico; Cordella, Roberto; Andronache, Adrian; Zaca, Domenico; Bruzzone, Maria Grazia; Tringali, Giovanni; Minati, Ludovico

2014-01-01

396

Assessment of outdoor radiofrequency electromagnetic field exposure through hotspot localization using kriging-based sequential sampling.  

PubMed

In this study, a novel methodology is proposed to create heat maps that accurately pinpoint the outdoor locations with elevated exposure to radiofrequency electromagnetic fields (RF-EMF) in an extensive urban region (or, hotspots), and that would allow local authorities and epidemiologists to efficiently assess the locations and spectral composition of these hotspots, while at the same time developing a global picture of the exposure in the area. Moreover, no prior knowledge about the presence of radiofrequency radiation sources (e.g., base station parameters) is required. After building a surrogate model from the available data using kriging, the proposed method makes use of an iterative sampling strategy that selects new measurement locations at spots which are deemed to contain the most valuable information-inside hotspots or in search of them-based on the prediction uncertainty of the model. The method was tested and validated in an urban subarea of Ghent, Belgium with a size of approximately 1 km2. In total, 600 input and 50 validation measurements were performed using a broadband probe. Five hotspots were discovered and assessed, with maximum total electric-field strengths ranging from 1.3 to 3.1 V/m, satisfying the reference levels issued by the International Commission on Non-Ionizing Radiation Protection for exposure of the general public to RF-EMF. Spectrum analyzer measurements in these hotspots revealed five radiofrequency signals with a relevant contribution to the exposure. The radiofrequency radiation emitted by 900 MHz Global System for Mobile Communications (GSM) base stations was always dominant, with contributions ranging from 45% to 100%. Finally, validation of the subsequent surrogate models shows high prediction accuracy, with the final model featuring an average relative error of less than 2dB (factor 1.26 in electric-field strength), a correlation coefficient of 0.7, and a specificity of 0.96. PMID:23759207

Aerts, Sam; Deschrijver, Dirk; Verloock, Leen; Dhaene, Tom; Martens, Luc; Joseph, Wout

2013-10-01

397

Incidence of prenatal alcohol exposure in Prince Edward Island: a population-based descriptive study  

PubMed Central

Background Fetal alcohol spectrum disorder (FASD) is a leading preventable cause of neurodevelopmental disability in North America. The stigma associated with alcohol use and abuse during pregnancy makes it difficult to obtain information on prenatal alcohol use through self-reporting. We assessed the incidence of prenatal alcohol exposure in Prince Edward Island to facilitate future public health initiatives addressing FASD. Methods Prenatal alcohol exposure was examined via population-based collection of meconium and analysis of fatty acid ethyl esters (FAEEs). Fatty acid ethyl esters are nonoxidative metabolites of ethanol that are produced in the fetus. Meconium FAEE concentrations of 2.0 nmol/g or greater are indicative of frequent prenatal alcohol exposure during the last 2 trimesters of pregnancy. Samples were collected from 1307 neonates between Nov. 8, 2010, and Nov. 8, 2011, in hospitals in PEI, or from those born to mothers who resided in PEI but gave birth in Halifax, Nova Scotia. Samples were frozen and shipped for analysis. Fatty acid ethyl esters were analyzed by gas chromatography–mass spectrometry and quantified by means of deuterated internal standards. Results Of the 1307 samples collected, 1271 samples were successfully analyzed. Positive results for FAEEs were obtained in 3.1% (n = 39) of samples collected within the first 24 hours after birth. Interpretation Not all neonates exposed to heavy prenatal alcohol in utero will exhibit FASD; based on current estimates of predictive value for disease by exposure, our findings suggest that 1.3% of neonates born in PEI during this 1-year period will have FASD. In its application to an entire provincial birth cohort, this study successfully implemented a public health–centred approach for evaluating population-based risk of FASD, with implications for practice across Canada.

Bryanton, Janet; Boswall, Diane; McCarthy, Mary Jean; Fraser, Bonnie; Walsh, Donna; Freeman, Bridget; Koren, Gideon; Bigsby, Kathy

2014-01-01

398

Assessing Visual Arts Talents of Hong Kong Chinese Gifted Students: The Development of the Impossible Figures Task  

ERIC Educational Resources Information Center

The Impossible Figures Task (IFT-28), which consisted of 28 possible and impossible figures assembled for brief exposure and recognition, was completed by 297 Hong Kong Chinese gifted students. Expert judges (N = 2) rated these students' drawing abilities based on their performance on 2 drawing tasks adapted from Clark's Drawing Abilities Test…

Chan, David W.

2008-01-01

399

Occupational exposure to base stations-compliance with EU directive 2004/40/EC.  

PubMed

The rapid growth of mobile communications has not only led to a rising number of mobile telephones. It has also made base stations essential for these services widespread on many roofs. However, not everyone is aware that working close to sources of high frequency electromagnetic fields (EMF), such as transmitter antennas for mobile phones, pagers and police, fire and other emergency services, can result in high EMF exposure. This paper deals with measurements and calculations of the compliance boundary for workers in one typical roof top base station setting according to EU Directive and other relevant EN standards. PMID:16790176

Gajsek, Peter; Simuni?, Dina

2006-01-01

400

Workgroup Report: Base Stations and Wireless Networks--Radiofrequency (RF) Exposures and Health Consequences  

PubMed Central

Radiofrequency (RF) waves have long been used for different types of information exchange via the airwaves—wireless Morse code, radio, television, and wireless telephony (i.e., construction and operation of telephones or telephonic systems). Increasingly larger numbers of people rely on mobile telephone technology, and health concerns about the associated RF exposure have been raised, particularly because the mobile phone handset operates in close proximity to the human body, and also because large numbers of base station antennas are required to provide widespread availability of service to large populations. The World Health Organization convened an expert workshop to discuss the current state of cellular-telephone health issues, and this article brings together several of the key points that were addressed. The possibility of RF health effects has been investigated in epidemiology studies of cellular telephone users and workers in RF occupations, in experiments with animals exposed to cell-phone RF, and via biophysical consideration of cell-phone RF electric-field intensity and the effect of RF modulation schemes. As summarized here, these separate avenues of scientific investigation provide little support for adverse health effects arising from RF exposure at levels below current international standards. Moreover, radio and television broadcast waves have exposed populations to RF for > 50 years with little evidence of deleterious health consequences. Despite unavoidable uncertainty, current scientific data are consistent with the conclusion that public exposures to permissible RF levels from mobile telephony and base stations are not likely to adversely affect human health.

Valberg, Peter A.; van Deventer, T. Emilie; Repacholi, Michael H.

2007-01-01

401

Murine pulmonary responses after sub-chronic exposure to aluminum oxide-based nanowhiskers  

PubMed Central

Background Aluminum oxide-based nanowhiskers (AO nanowhiskers) have been used in manufacturing processes as catalyst supports, flame retardants, adsorbents, or in ceramic, metal and plastic composite materials. They are classified as high aspect ratio nanomaterials. Our aim was to assess in vivo toxicity of inhaled AO nanowhisker aerosols. Methods Primary dimensions of AO nanowhiskers specified by manufacturer were 2–4?nm x 2800?nm. The aluminum content found in this nanomaterial was 30% [mixed phase material containing Al(OH)3 and AlOOH]. Male mice (C57Bl/6?J) were exposed to AO nanowhiskers for 4?hrs/day, 5?days/wk for 2 or 4 wks in a dynamic whole body exposure chamber. The whiskers were aerosolized with an acoustical dry aerosol generator that included a grounded metal elutriator and a venturi aspirator to enhance deagglomeration. Average concentration of aerosol in the chamber was 3.3?±?0.6?mg/m3 and the mobility diameter was 150?±?1.6?nm. Both groups of mice (2 or 4 wks exposure) were necropsied immediately after the last exposure. Aluminum content in the lung, heart, liver, and spleen was determined. Pulmonary toxicity assessment was performed by evaluation of bronchoalveolar lavage (BAL) fluid (enumeration of total and differential cells, total protein, activity of lactate dehydrogenase [LDH] and cytokines), blood (total and differential cell counts), lung histopathology and pulmonary mechanics. Results Following exposure, mean Al content of lungs was 0.25, 8.10 and 15.37??g/g lung (dry wt) respectively for sham, 2 wk and 4 wk exposure groups. The number of total cells and macrophages in BAL fluid was 2-times higher in animals exposed for 2 wks and 6-times higher in mice exposed for 4 wks, compared to shams (p?exposures to aluminum-oxide based nanowhiskers induced increased lung macrophages, but no inflammatory or toxic responses were observed.

2012-01-01

402

Potential for Inhalation Exposure to Engineered Nanoparticles from Nanotechnology-Based Cosmetic Powders  

PubMed Central

Background: The market of nanotechnology-based consumer products is rapidly expanding, and the lack of scientific evidence describing the accompanying exposure and health risks stalls the discussion regarding its guidance and regulation. Objectives: We investigated the potential for human contact and inhalation exposure to nanomaterials when using nanotechnology-based cosmetic powders and compare them with analogous products not marketed as nanotechnology based. Methods: We characterized the products using transmission electron microscopy (TEM) and laser diffraction spectroscopy and found nanoparticles in five of six tested products. TEM photomicrographs showed highly agglomerated states of nanoparticles in the products. We realistically simulated the use of cosmetic powders by applying them to the face of a human mannequin head while simultaneously sampling the released airborne particles through the ports installed in the mannequin’s nostrils. Results: We found that a user would be exposed to nanomaterial predominantly through nanoparticle-containing agglomerates larger than the 1–100-nm aerosol fraction. Conclusions: Predominant deposition of nanomaterial(s) will occur in the tracheobronchial and head airways—not in the alveolar region as would be expected based on the size of primary nanoparticles. This could potentially lead to different health effects than expected based on the current understanding of nanoparticle behavior and toxicology studies for the alveolar region.

Nazarenko, Yevgen; Zhen, Huajun; Han, Taewon; Lioy, Paul J.

2012-01-01

403

Community-Based Participatory Research and Policy Advocacy to Reduce Diesel Exposure in West Oakland, California  

PubMed Central

We conducted a multimethod case study analysis of a community-based participatory research partnership in West Oakland, California, and its efforts to study and address the neighborhood's disproportionate exposure to diesel air pollution. We employed 10 interviews with partners and policymakers, participant observation, and a review of documents. Results of the partnership's truck count and truck idling studies suggested substantial exposure to diesel pollution and were used by the partners and their allies to make the case for a truck route ordinance. Despite weak enforcement, the partnership's increased political visibility helped change the policy environment, with the community partner now heavily engaged in environmental decision-making on the local and regional levels. Finally, we discussed implications for research, policy, and practice.

Gonzalez, Priscilla A.; Garcia, Analilia P.; Gordon, Margaret; Garzon, Catalina; Palaniappan, Meena; Prakash, Swati; Beveridge, Brian

2011-01-01

404

Myocardial infarction and occupational exposure to motor exhaust: a population-based case-control study in Sweden.  

PubMed

There is a well-established association between particulate urban air pollution and cardiovascular disease, but few studies have investigated the risk associated with occupational exposure to particles from motor exhaust. This study investigated the risk of myocardial infarction (MI) after occupational exposure to motor exhaust, using elemental carbon (EC) as a marker of exposure. A population-based case-control study of first-time non-lethal MI was conducted among Swedish citizens in ages 45-70 living in Stockholm County 1992-1994, including 1,643 cases and 2,235 controls. Working histories and data on potential confounders were collected by questionnaire and medical examination. The exposure to EC was assessed through a job-exposure matrix. Odds ratios (ORs) and corresponding 95 % confidence intervals (CIs) were estimated by unconditional logistic regression. We investigated various exposure metrics: intensity, cumulative exposure and years since exposure. There was an exposure-response relation between the highest average exposure intensity during the work history and the risk of MI when adjusting for smoking and alcohol drinking (p for trend 0.034), with an OR of 1.30 (95 % CI 0.99-1.71) in the highest tertile of exposure compared to the unexposed. An exposure-response pattern was observed in the analysis of years since exposure cessation among formerly exposed. Additional adjustments for markers of the metabolic syndrome reduced ORs and trends to non-significant levels, although this might be an over-adjustment since the metabolic syndrome may be part of the causal pathway. Occupational exposure to motor exhaust was associated with a moderately increased risk of MI. PMID:24981789

Ilar, Anna; Lewné, Marie; Plato, Nils; Hallqvist, Johan; Alderling, Magnus; Bigert, Carolina; Hogstedt, Christer; Gustavsson, Per

2014-07-01

405

Monitoring behaviour in a time-based prospective memory task: The involvement of executive functions and time perception.  

PubMed

This study investigated time-based prospective memory (PM) performance in 76 younger and 76 older adults with a time-monitoring task in which participants were required to press a designated key every 5 minutes while watching a movie. Participants were assigned to two conditions, free and fixed monitoring. In free monitoring participants could check a clock when they wanted, but in fixed monitoring they were restricted a maximum of six times every 5 minutes. We also investigated the involvement of time perception, inhibition, and updating in time-based PM performance. We hypothesised that participants with inefficiencies in those three cognitive functions would have less strategic monitoring behaviour and would also be less accurate at the target time. In the free-monitoring condition older adults checked the clock more frequently than younger participants, but presented with a similar pattern of monitoring behaviour and increased their frequency of clock checking closer to the target time. In the fixed-monitoring condition younger participants checked the clock more frequently than older adults and showed a strategic pattern of monitoring. Older adults did not show strategic use of clock checking and their monitoring function remained unchanged. Differences in PM accuracy and monitoring behaviour are discussed according to different involvement of cognitive abilities. PMID:23734633

Mioni, Giovanna; Stablum, Franca

2014-07-01

406

Human Exposure to Selected Animal Neurocarcinogens: A Biomarker-Based Assessment and Implications for Brain Tumor Epidemiology  

PubMed Central

This review is based on the proceedings from the Second Lebow Conference held in Chicago in 2007. The conference concentrated on developing a framework for innovative studies in the epidemiology of environmental exposures, focusing specifically on the potential relationship with brain tumors. Researchers with different perspectives, including toxicology, pharmacokinetics, and epidemiological exposure assessment, exchanged information and ideas on the use of biomarkers of exposure in molecular epidemiology studies and summarized the current knowledge on methods and approaches for biomarker-based exposure assessment. This report presents the state of science regarding biomarker-based exposure assessment of the 4 most common neurocarcinogens: acrylamide, 1,3-butadiene, N-nitroso compounds, and polycyclic aromatic hydrocarbons. Importantly, these chemicals are also carcinogenic in other organs; therefore, this discussion is useful for environmental epidemiologists studying all cancer types.

Il'yasova, Dora; McCarthy, Bridget J.; Erdal, Serap; Shimek, Joanna; Goldstein, Jennifer; Doerge, Daniel R.; Myers, Steven R.; Vineis, Paolo; Wishnok, John S.; Swenberg, James A.; Bigner, Darell D.; Davis, Faith G.

2013-01-01

407

Human exposure to selected animal neurocarcinogens: a biomarker-based assessment and implications for brain tumor epidemiology.  

PubMed

This review is based on the proceedings from the Second Lebow Conference, held in Chicago in 2007. The conference concentrated on developing a framework for innovative studies in the epidemiology of environmental exposures, focusing specifically on the potential relationship with brain tumors. Researchers with different perspectives, including toxicology, pharmacokinetics, and epidemiological exposure assessment, exchanged information and ideas on the use of biomarkers of exposure in molecular epidemiology studies and summarized the current knowledge on methods and approaches for biomarker-based exposure assessment. This report presents the state of science regarding biomarker-based exposure assessment of the four most common neurocarcinogens: acrylamide, 1,3-butadiene, N-nitroso compounds, and polycyclic aromatic hydrocarbons. Importantly, these chemicals are also carcinogenic in other organs; therefore, this discussion is useful for environmental epidemiologists studying all cancer types. PMID:19466671

Il'yasova, Dora; McCarthy, Bridget J; Erdal, Serap; Shimek, Joanna; Goldstein, Jennifer; Doerge, Daniel R; Myers, Steven R; Vineis, Paolo; Wishnok, John S; Swenberg, James A; Bigner, Darell D; Davis, Faith G

2009-03-01

408

Cigarette Filter-based Assays as Proxies for Toxicant Exposure and Smoking Behavior A Literature Review  

PubMed Central

Background Cigarettes are being marketed with filters that differ in composition and design. The filters have different toxicant trapping efficiency and smoking stains reflect variations in smoking behavior. Presented herein are the results of a structured literature review that was performed to identify cigarette filter-based assays that may serve as proxies for mouth-level exposure and assessing smoking methods. Methods A search of the published scientific literature and internal tobacco company documents from 1954 to 2009 was performed. Results The literature search identified diverse schemes for assessing cigarette filters, including visual inspection and digital imaging of smoked-stained spent filters, and quantitative determinations for total particulate matter (TPM), nicotine, and solanesol. The results also showed that: (a) there is sufficient data to link filter-based chemical measures to standardized smoking machine-measured yields of tar and nicotine; (b) TPM eluted from filters or in chemical digest of filters can be used to estimate the efficiency of the filter for trapping smoke solids; (c) visual and digital inspection of spent filters are useful as indicators of variations in smoking behaviors; and (d) there is a correlation between solanesol and nicotine measured in filters and exposure biomarkers in smokers. Conclusions The cigarette filter may prove useful in estimating smoking behaviors such as filter vent blocking and puffing intensity, and may have utility as proxy measures of mouth-level smoke exposure in clinical trials. Additional investigations are needed to compare the different proposed assay schemes and the assay results with measurements of human biomarker assays of smoke exposure.

Pauly, John L.; O'Connor, Richard J.; Paszkiewicz, Geraldine M.; Cummings, K. Michael; Djordjevic, Mirjana V.; Shields, Peter G.

2009-01-01

409

Predictive Engineering Models Based on the EPIC Architecture for a Multimodal High-Performance Human-Computer Interaction Task  

Microsoft Academic Search

Engineering models of human performance permit some aspects of usability of interface designs to be predicted from an analysis of the task, and thus they can replace to some extent expensive user-testing data. We successfully predicted human performance in telephone operator tasks with engineering models constructed in the EPIC (Executive Process-Interac- tive Control) architecture for human information processing, which is

DAVID E. KIERAS; SCOTT D. WOOD; DAVID E. MEYER

1996-01-01

410

Cognitive Constructs Measured in Word Problems: A Comparison of Students' Responses in Performance-Based Tasks and Multiple-Choice Tasks for Reasoning.  

ERIC Educational Resources Information Center

This study investigated cognitive constructs to be measured by word problems in algebra. One performance-based assessment was administered to 290 high school students. Students' responses were scored by three scoring systems: the correct/incorrect criterion (0/1); a holistic scoring rubric (0-4); and an analytical scoring rubric for measuring…

Suzuki, Kyoko

411

SPME-based air sampling method for inhalation exposure assessment studies: case study on perchlorethylene exposure in dry cleaning.  

PubMed

Exposure to perchlorethylene, especially for dry cleaning workers and for people living near dry cleaning shops, could lead to several diseases and disorders. This study examines the value of solid-phase microextraction (SPME) for sampling perchlorethylene in the atmosphere of dry cleaning shops. Carboxen/polydimethylsiloxane (CAR/PDMS) in 0.5-cm retracted mode was selected. There were no significant differences between sampling rates at different temperatures (range of 20 to 30 °C) and air velocities (2 to 50 cm/s). On the opposite, relative humidity (RH) had a significant effect on sampling rates. Method reproducibility was realized in the laboratory and field conditions and was 6.2 % and 7 to 11 %, respectively. Repeatability was also determined as 8.9 %. Comparison of the results according to the American Industrial Hygiene Association exposure assessment strategy showed the SPME sampler yields more conservative results in comparison with traditional standard method. PMID:23054278

Zare Sakhvidi, Mohammad Javad; Bahrami, Abdul Rahman; Ghiasvand, Alireza; Mahjub, Hossein; Tuduri, Ludovic

2013-06-01

412

Disparities in Secondhand Smoke Exposure: Using TUS in a "non-ATS" state to Build Support for Evidence Based Policy  

Cancer.gov

Disparities in Secondhand Smoke Exposure: Using TUS in a “non-ATS” state to Build Support for Evidence Based Policy Sally Herndon Malek, MPH Marcus Plescia, MD MPH NC Division of Public Health Don Shopland, PHS Retired Goal: Eliminate Exposure to

413

The Association between Biomarker-Based Exposure Estimates for Phthalates and Demographic Factors in a Human Reference Population  

Microsoft Academic Search

Population-based estimates of environmental exposures using biomarkers can be difficult to obtain for a variety of reasons, including problems with limits of detection, undersampling of key strata, time between exposure and sampling, variation across individuals, variation within individ- uals, and the ability to find and interpret a given biomarker. In this article, we apply statistical likelihoods, weighted sampling, and regression

Jung-Wan Koo; Frederick Parham; Michael C. Kohn; Scott A. Masten; John W. Brock; Larry L. Needham; Christopher J. Portier

2002-01-01

414

A New Stress-Based Model of Political Extremism: Personal Exposure to Terrorism, Psychological Distress, and Exclusionist Political Attitudes  

ERIC Educational Resources Information Center

Does exposure to terrorism lead to hostility toward minorities? Drawing on theories from clinical and social psychology, we propose a stress-based model of political extremism in which psychological distress--which is largely overlooked in political scholarship--and threat perceptions mediate the relationship between exposure to terrorism and…

Canetti-Nisim, Daphna; Halperin, Eran; Sharvit, Keren; Hobfoll, Stevan E.

2009-01-01

415

Conceptual design of a space-based multimegawatt MHD power system, task 1 topical report; Volume 1: Technical discussion. Topical report  

SciTech Connect

This Topical Report presents the results of Task 1 of the Feasibility Assessment for Space Based Multimegawatt MHD Power Systems program. It consists of two volumes. Volume 1 contains the results of the work performed in Task 1 as presented and discussed in Sections 2 through 6. Section 2 is an executive summary of the work. Section 3 contains a complete description of the space based multimegawatt MHD power system conceptual design. System performance and operations characteristics are also identified. It has been assumed in Task 1 that the system provides power to a Neutral Particle Beam (NPB) Weapon, for which generic load requirements are presented. Integration of the power system and NPB with alternative space launch vehicles is also discussed in this section. Section 4 contains a discussion of key technical issues and questions requiring additional investigation. Section 5 presents the Research and Development plan which is proposed for Task 2. Conclusions and Recommendations are contained in Section 6. Volume 2 of the report contains the System Requirements, Design Guidelines and Assumptions for the space based multimegawatt MHD power system. This is an initial system specification document which will be refined during the course of Task 2.

Dana, R.A.

1988-01-01

416

Assessment of outdoor radiofrequency electromagnetic field exposure through hotspot localization using kriging-based sequential sampling  

SciTech Connect

In this study, a novel methodology is proposed to create heat maps that accurately pinpoint the outdoor locations with elevated exposure to radiofrequency electromagnetic fields (RF-EMF) in an extensive urban region (or, hotspots), and that would allow local authorities and epidemiologists to efficiently assess the locations and spectral composition of these hotspots, while at the same time developing a global picture of the exposure in the area. Moreover, no prior knowledge about the presence of radiofrequency radiation sources (e.g., base station parameters) is required. After building a surrogate model from the available data using kriging, the proposed method makes use of an iterative sampling strategy that selects new measurement locations at spots which are deemed to contain the most valuable information—inside hotspots or in search of them—based on the prediction uncertainty of the model. The method was tested and validated in an urban subarea of Ghent, Belgium with a size of approximately 1 km{sup 2}. In total, 600 input and 50 validation measurements were performed using a broadband probe. Five hotspots were discovered and assessed, with maximum total electric-field strengths ranging from 1.3 to 3.1 V/m, satisfying the reference levels issued by the International Commission on Non-Ionizing Radiation Protection for exposure of the general public to RF-EMF. Spectrum analyzer measurements in these hotspots revealed five radiofrequency signals with a relevant contribution to the exposure. The radiofrequency radiation emitted by 900 MHz Global System for Mobile Communications (GSM) base stations was always dominant, with contributions ranging from 45% to 100%. Finally, validation of the subsequent surrogate models shows high prediction accuracy, with the final model featuring an average relative error of less than 2 dB (factor 1.26 in electric-field strength), a correlation coefficient of 0.7, and a specificity of 0.96. -- Highlights: • We present an iterative measurement and modeling method for outdoor RF-EMF exposure. • Hotspots are rapidly identified, and accurately characterized. • An accurate graphical representation, or heat map, is created, using kriging. • Random validation shows good correlation (0.7) and low relative errors (2 dB)

Aerts, Sam, E-mail: sam.aerts@intec.ugent.be; Deschrijver, Dirk; Verloock, Leen; Dhaene, Tom; Martens, Luc; Joseph, Wout

2013-10-15

417

A population-based study on welding exposures at work and respiratory symptoms.  

PubMed

In the first European Community Respiratory Health Survey (ECRHS I), an excess asthma risk was associated with high exposure to gases and fumes, mineral and biological dusts. In a 9-year follow-up study (ECRHS II), the aim was to study if welding at work increases the risk of asthma symptoms, wheeze and chronic bronchitis symptoms. The study also aimed to identify specific welding risk factors. In a random population sample of individuals from 22 European centres in 10 countries, 316 males reported welding at work during the follow-up period. These individuals responded to a supplemental questionnaire about frequency of welding, use of different methods and materials, welding environment and respiratory protection. Cumulative exposure to welding fumes for the follow-up period was estimated by using a database on welding fume exposures. Log-binomial regression models were used to estimate prevalence ratios (PR) with 95% confidence intervals (CIs) for prevalence of asthma symptoms or asthma medication, wheeze and chronic bronchitis symptoms in relation to welding methods and welded materials as well as estimated cumulative welding fume exposure compared to an external reference group. In the study population of 316 males, 62% performed welding <1 h day(-1), 23% 1-3 h day(-1) and 15% >4 h day(-1). Welding was a common task in many occupations and only 7% of the individuals actually called themselves welders and flame cutters, while the largest groups doing welding worked in construction or were motor, agricultural and industrial mechanics and fitters. Welding at work was not associated with an increased prevalence of asthma symptoms or wheeze but there was an association with chronic bronchitis symptoms (PR = 1.33, 1.00-1.76). Using assigned cumulative exposure in tertiles showed that the lowest exposed tertile had the highest PR of bronchitis symptoms. Chronic bronchitis symptoms was significantly higher in those frequently welding in galvanized steel or iron (PR = 2.14, 1.24-3.68) and in those frequently manual welding stainless steel (PR = 1.92, 1.00-3.66). There was also an increase in the prevalence of wheeze in individuals welding painted metal (PR = 1.66, 0.99-2.78; PR = 1.83, 0.90-3.71). Welding with manual metal arc technique <1 day week(-1) showed a prevalence risk of 1.69 for wheeze (CI = 1.16-2.46). In conclusion, the present study shows an association between welding in galvanized material and stainless steel and chronic bronchitis symptoms. There was also an increased prevalence of wheeze and welding in painted metal. The results support that welding in coated material is a respiratory hazard underscoring the importance of preventive actions. PMID:18216372

Lillienberg, L; Zock, J-P; Kromhout, H; Plana, E; Jarvis, D; Torén, K; Kogevinas, M

2008-03-01

418

Conceptual design of a lunar base solar power plant lunar base systems study task 3.3  

NASA Technical Reports Server (NTRS)

The best available concepts for a 100 kW Solar Lunar Power Plant based on static and dynamic conversion concepts have been examined. The two concepts which emerged for direct comparison yielded a difference in delivered mass of 35 MT, the mass equivalent of 1.4 lander payloads, in favor of the static concept. The technologies considered for the various elements are either state-of-the-art or near-term. Two photovoltaic cell concepts should receive high priority for development: i.e., amorphous silicon and indium phosphide cells. The amorphous silicon, because it can be made so light weight and rugged; and the indium phosphide, because it shows very high efficiency potential and is reportedly not degraded by radiation. Also the amorphous silicon cells may be mounted on flexible backing that may roll up much like a carpet for compact storage, delivery, and ease of deployment at the base. The fuel cell and electrolysis cell technology is quite well along for lunar base applications, and because both the Shuttle and the forthcoming Space Station incorporate these devices, the status quo will be m