Factors Influencing Ball-Player Impact Probability in Youth Baseball

PubMed Central

Matta, Philip A.; Myers, Joseph B.; Sawicki, Gregory S.

2015-01-01

Background: Altering the weight of baseballs for youth play has been studied out of concern for player safety. Research has shown that decreasing the weight of baseballs may limit the severity of both chronic arm and collision injuries. Unfortunately, reducing the weight of the ball also increases its exit velocity, leaving pitchers and nonpitchers with less time to defend themselves. The purpose of this study was to examine impact probability for pitchers and nonpitchers. Hypothesis: Reducing the available time to respond by 10% (expected from reducing ball weight from 142 g to 113 g) would increase impact probability for pitchers and nonpitchers, and players’ mean simple response time would be a primary predictor of impact probability for all participants. Study Design: Nineteen subjects between the ages of 9 and 13 years performed 3 experiments in a controlled laboratory setting: a simple response time test, an avoidance response time test, and a pitching response time test. Methods: Each subject performed these tests in order. The simple reaction time test tested the subjects’ mean simple response time, the avoidance reaction time test tested the subjects’ ability to avoid a simulated batted ball as a fielder, and the pitching reaction time test tested the subjects’ ability to avoid a simulated batted ball as a pitcher. Results: Reducing the weight of a standard baseball from 142 g to 113 g led to a less than 5% increase in impact probability for nonpitchers. However, the results indicate that the impact probability for pitchers could increase by more than 25%. Conclusion: Pitching may greatly increase the amount of time needed to react and defend oneself from a batted ball. Clinical Relevance: Impact injuries to youth baseball players may increase if a 113-g ball is used. PMID:25984261

Hypervelocity Impact (HVI). Volume 7; WLE High Fidelity Specimen RCC16R

NASA Technical Reports Server (NTRS)

Gorman, Michael R.; Ziola, Steven M.

2007-01-01

During 2003 and 2004, the Johnson Space Center's White Sands Testing Facility in Las Cruces, New Mexico conducted hypervelocity impact tests on the space shuttle wing leading edge. Hypervelocity impact tests were conducted to determine if Micro-Meteoroid/Orbital Debris impacts could be reliably detected and located using simple passive ultrasonic methods. The objective of Target RCC16R was to study hypervelocity impacts through the reinforced carbon-carbon (RCC) panels of the Wing Leading Edge. Impact damage was detected using lightweight, low power instrumentation capable of being used in flight.

The Impact of Escape Alternative Position Change in Multiple-Choice Test on the Psychometric Properties of a Test and Its Items Parameters

ERIC Educational Resources Information Center

Hamadneh, Iyad Mohammed

2015-01-01

This study aimed at investigating the impact changing of escape alternative position in multiple-choice test on the psychometric properties of a test and it's items parameters (difficulty, discrimination & guessing), and estimation of examinee ability. To achieve the study objectives, a 4-alternative multiple choice type achievement test…

The Impact of Scholastic Instrumental Music and Scholastic Chess Study on the Standardized Test Scores of Students in Grades Three, Four, and Five

ERIC Educational Resources Information Center

Martinez, Edwin E.

2012-01-01

This study examines the impact of instrumental music study and group chess lessons on the standardized test scores of suburban elementary public school students (grades three through five) in Levittown, New York. The study divides the students into the following groups and compares the standardized test scores of each: a) instrumental music…

An Exploration of the Impact of Accountability Testing on Teaching in Urban Elementary Classrooms

ERIC Educational Resources Information Center

Bisland, Beverly Milner

2015-01-01

This study explores accountability testing in the elementary schools of New York City with particular emphasis on the impact of a statewide social studies test on the value given to social studies instruction in comparison to other subjects. The attitudes of a group of elementary teachers are examined. Some of the teachers taught all subjects in…

Size Effects in Impact Damage of Composite Sandwich Panels

NASA Technical Reports Server (NTRS)

Dobyns, Alan; Jackson, Wade

2003-01-01

Panel size has a large effect on the impact response and resultant damage level of honeycomb sandwich panels. It has been observed during impact testing that panels of the same design but different panel sizes will show large differences in damage when impacted with the same impact energy. To study this effect, a test program was conducted with instrumented impact testing of three different sizes of sandwich panels to obtain data on panel response and residual damage. In concert with the test program. a closed form analysis method was developed that incorporates the effects of damage on the impact response. This analysis method will predict both the impact response and the residual damage of a simply-supported sandwich panel impacted at any position on the panel. The damage is incorporated by the use of an experimental load-indentation curve obtained for the face-sheet/honeycomb and indentor combination under study. This curve inherently includes the damage response and can be obtained quasi-statically from a rigidly-backed specimen or a specimen with any support conditions. Good correlation has been obtained between the test data and the analysis results for the maximum force and residual indentation. The predictions can be improved by using a dynamic indentation curve. Analyses have also been done using the MSC/DYTRAN finite element code.

Drop-Weight Impact Test on U-Shape Concrete Specimens with Statistical and Regression Analyses

PubMed Central

Zhu, Xue-Chao; Zhu, Han; Li, Hao-Ran

2015-01-01

According to the principle and method of drop-weight impact test, the impact resistance of concrete was measured using self-designed U-shape specimens and a newly designed drop-weight impact test apparatus. A series of drop-weight impact tests were carried out with four different masses of drop hammers (0.875, 0.8, 0.675 and 0.5 kg). The test results show that the impact resistance results fail to follow a normal distribution. As expected, U-shaped specimens can predetermine the location of the cracks very well. It is also easy to record the cracks propagation during the test. The maximum of coefficient of variation in this study is 31.2%; it is lower than the values obtained from the American Concrete Institute (ACI) impact tests in the literature. By regression analysis, the linear relationship between the first-crack and ultimate failure impact resistance is good. It can suggested that a minimum number of specimens is required to reliably measure the properties of the material based on the observed levels of variation. PMID:28793540

Methods Used in Economic Evaluations of Testing and Diagnosis for Ovarian Cancer: A Systematic Review.

PubMed

Sharma, Vishal; Sundar, Sudha S; Breheny, Katie; Monahan, Mark; Sutton, Andrew John

2016-06-01

There are multiple tests available that can help diagnose ovarian cancer, and the cost-effective analysis of these diagnostic interventions is essential for making well-informed decisions regarding resource allocation. There are multiple factors that can impact on the conclusions drawn from economic evaluations including test accuracy, the impact of the testing pathway on patient costs and outcomes, and delays along the ovarian cancer test-treat pathway. The objective of this study was to evaluate how test accuracy, the choice of perspective, and delays along the testing and diagnostic pathway have been incorporated in economic evaluations of testing for ovarian cancer. A systematic review of published literature was undertaken to identify economic evaluations (eg, cost-effectiveness, cost-utility analysis) focused on testing and diagnosis for ovarian cancer. Seven studies met the inclusion criteria. Six studies incorporated test accuracy and its impact on patients to some extent. Four studies adopted a societal perspective, but only one considered the costs incurred by patients on the testing and diagnosis pathway. Where delays on the testing pathway were incorporated into the analysis, these were frequently due to false-negative test results leading to delays in patients accessing treatment. Any anxiety that patients might experience as a result of a positive test was not considered in these studies. The impact on patients of receiving a positive test in terms of anxiety and the costs incurred by patients having to attend for testing and diagnosis are rarely considered. Delays along the testing and diagnosis pathway can have a major effect on patient outcomes, and it is important that these are acknowledged in economic evaluations focused on testing. Future economic analysis should incorporate these key determinants in order that diagnostic tests for ovarian cancer can be robustly evaluated.

Test plan. Task 5, subtask 5.2: Early on-orbit TPSdebris impact tests

NASA Technical Reports Server (NTRS)

Greenberg, H. S.

1994-01-01

The limitation of damage to, and survival of, the cryogenic tankage during the on-orbit stay despite potential impact of orbital debris, may be a significant discriminator in the RHCTS trade studies described in the TA-1 trade study plan (ref. RHCTS-TSP-1) dated July 29, 1994. The objective of this early phase of an overall debris impact test program is to provide the data to support assessment of the relative suitability of integral and non integral tanks.

Design of Orion Soil Impact Study using the Modern Design of Experiments

NASA Technical Reports Server (NTRS)

DeLoach, Richard

2010-01-01

Two conventional One Factor At a Time (OFAT) test matrices under consideration for an Orion Landing System subscale soil impact study are reviewed. Certain weaknesses in the designs, systemic to OFAT experiment designs generally, are identified. An alternative test matrix is proposed that is based in the Modern Design of Experiments (MDOE), which achieves certain synergies by combining the original two test matrices into one. The attendant resource savings are quantified and the impact on uncertainty is discussed.

Evaluation of a Singular Value Decomposition Approach for Impact Dynamic Data Correlation

NASA Technical Reports Server (NTRS)

Horta, Lucas G.; Lyle, Karen H.; Lessard, Wendy B.

2003-01-01

Impact dynamic tests are used in the automobile and aircraft industries to assess survivability of occupants during crash, to assert adequacy of the design, and to gain federal certification. Although there is no substitute for experimental tests, analytical models are often developed and used to study alternate test conditions, to conduct trade-off studies, and to improve designs. To validate results from analytical predictions, test and analysis results must be compared to determine the model adequacy. The mathematical approach evaluated in this paper decomposes observed time responses into dominant deformation shapes and their corresponding contribution to the measured response. To correlate results, orthogonality of test and analysis shapes is used as a criterion. Data from an impact test of a composite fuselage is used and compared to finite element predictions. In this example, the impact response was decomposed into multiple shapes but only two dominant shapes explained over 85% of the measured response

An Investigation of the Impact of Guessing on Coefficient α and Reliability

PubMed Central

2014-01-01

Guessing is known to influence the test reliability of multiple-choice tests. Although there are many studies that have examined the impact of guessing, they used rather restrictive assumptions (e.g., parallel test assumptions, homogeneous inter-item correlations, homogeneous item difficulty, and homogeneous guessing levels across items) to evaluate the relation between guessing and test reliability. Based on the item response theory (IRT) framework, this study investigated the extent of the impact of guessing on reliability under more realistic conditions where item difficulty, item discrimination, and guessing levels actually vary across items with three different test lengths (TL). By accommodating multiple item characteristics simultaneously, this study also focused on examining interaction effects between guessing and other variables entered in the simulation to be more realistic. The simulation of the more realistic conditions and calculations of reliability and classical test theory (CTT) item statistics were facilitated by expressing CTT item statistics, coefficient α, and reliability in terms of IRT model parameters. In addition to the general negative impact of guessing on reliability, results showed interaction effects between TL and guessing and between guessing and test difficulty.

The influence of validity criteria on Immediate Post-Concussion Assessment and Cognitive Testing (ImPACT) test-retest reliability among high school athletes.

PubMed

Brett, Benjamin L; Solomon, Gary S

2017-04-01

Research findings to date on the stability of Immediate Post-Concussion Assessment and Cognitive Testing (ImPACT) Composite scores have been inconsistent, requiring further investigation. The use of test validity criteria across these studies also has been inconsistent. Using multiple measures of stability, we examined test-retest reliability of repeated ImPACT baseline assessments in high school athletes across various validity criteria reported in previous studies. A total of 1146 high school athletes completed baseline cognitive testing using the online ImPACT test battery at two time periods of approximately two-year intervals. No participant sustained a concussion between assessments. Five forms of validity criteria used in previous test-retest studies were applied to the data, and differences in reliability were compared. Intraclass correlation coefficients (ICCs) ranged in composite scores from .47 (95% confidence interval, CI [.38, .54]) to .83 (95% CI [.81, .85]) and showed little change across a two-year interval for all five sets of validity criteria. Regression based methods (RBMs) examining the test-retest stability demonstrated a lack of significant change in composite scores across the two-year interval for all forms of validity criteria, with no cases falling outside the expected range of 90% confidence intervals. The application of more stringent validity criteria does not alter test-retest reliability, nor does it account for some of the variation observed across previously performed studies. As such, use of the ImPACT manual validity criteria should be utilized in the determination of test validity and in the individualized approach to concussion management. Potential future efforts to improve test-retest reliability are discussed.

The TOEFL Trump Card: An Investigation of Test Impact in an ESL Classroom

ERIC Educational Resources Information Center

Johnson, Karen E.; Jordan, Stefanie Rehn; Poehner, Matthew E.

2005-01-01

Much of the research on the effects of tests on foreign and second-language classrooms has examined the impact or washback effect that commercial/institutional language tests, such as the TOEFL, have on teachers' instructional practices (Hughes, 1998; Wall & Alderson, 1993). Using a case study methodology, this study uncovered the ways in…

The Impact of Time-Series Diagnostic Tests on the Writing Ability of Iranian EFL Learners

ERIC Educational Resources Information Center

Atashgahi, Bahareh Molazem

2014-01-01

This study aimed to show whether administering a battery of time-series diagnostic tests (screening) has any impact on Iranian EFL learners' writing ability. The study was conducted on the intermediate EFL learners at Islamic Azad University North Tehran branch. The researcher administered a homogenizing test in order to exclude the exceptional…

Hybrid composite laminates reinforced with Kevlar/carbon/glass woven fabrics for ballistic impact testing.

PubMed

Randjbaran, Elias; Zahari, Rizal; Jalil, Nawal Aswan Abdul; Majid, Dayang Laila Abang Abdul

2014-01-01

Current study reported a facile method to investigate the effects of stacking sequence layers of hybrid composite materials on ballistic energy absorption by running the ballistic test at the high velocity ballistic impact conditions. The velocity and absorbed energy were accordingly calculated as well. The specimens were fabricated from Kevlar, carbon, and glass woven fabrics and resin and were experimentally investigated under impact conditions. All the specimens possessed equal mass, shape, and density; nevertheless, the layers were ordered in different stacking sequence. After running the ballistic test at the same conditions, the final velocities of the cylindrical AISI 4340 Steel pellet showed how much energy was absorbed by the samples. The energy absorption of each sample through the ballistic impact was calculated; accordingly, the proper ballistic impact resistance materials could be found by conducting the test. This paper can be further studied in order to characterise the material properties for the different layers.

Structural Behavior Under Precision Impact Tests

DTIC Science & Technology

1996-08-01

ASPECTS OF IMPACT TESTING The problem of impact between two bodies has been studied extensively (for example, Eibl 1987, Feyerabend 1988, Krauthammer...Concrete for Hazard Protection, Edinburgh, Scotland, pp. 175-186. Feyerabend , M., 1988, "Der harte Querstoss auf Stützen aus Stahl und Stahlbeton

The Effectiveness of the Component Impact Test Method for the Side Impact Injury Assessment of the Door Trim

NASA Astrophysics Data System (ADS)

Youn, Younghan; Koo, Jeong-Seo

The complete evaluation of the side vehicle structure and the occupant protection is only possible by means of the full scale side impact crash test. But, auto part manufacturers such as door trim makers can not conduct the test especially when the vehicle is under the developing process. The main objective of this study is to obtain the design guidelines by a simple component level impact test. The relationship between the target absorption energy and impactor speed were examined using the energy absorbed by the door trim. Since each different vehicle type required different energy levels on the door trim. A simple impact test method was developed to estimate abdominal injury by measuring reaction force of the impactor. The reaction force will be converted to a certain level of the energy by the proposed formula. The target of absorption energy for door trim only and the impact speed of simple impactor are derived theoretically based on the conservation of energy. With calculated speed of dummy and the effective mass of abdomen, the energy allocated in the abdomen area of door trim was calculated. The impactor speed can be calculated based on the equivalent energy of door trim absorbed during the full crash test. With the proposed design procedure for the door trim by a simple impact test method was demonstrated to evaluate the abdominal injury. This paper describes a study that was conducted to determine sensitivity of several design factors for reducing abdominal injury values using the matrix of orthogonal array method. In conclusion, with theoretical considerations and empirical test data, the main objective, standardization of door trim design using the simple impact test method was established.

The Impact of Personality and Test Conditions on Mathematical Test Performance

ERIC Educational Resources Information Center

Hayes, Heather; Embretson, Susan E.

2013-01-01

Online and on-demand tests are increasingly used in assessment. Although the main focus has been cheating and test security (e.g., Selwyn, 2008) the cross-setting equivalence of scores as a function of contrasting test conditions is also an issue that warrants attention. In this study, the impact of environmental and cognitive distractions, as…

Testing of state roadside safety systems. Volume I, Technical report

DOT National Transportation Integrated Search

1999-04-01

The purpose of this study is to crash test and evaluate new or modified roadside safety hardware and, where necessary, redesign the devices to improve their impact performance. The three major areas addressed in this study are the impact performance ...

Evaluating the Impact of Guessing and Its Interactions with Other Test Characteristics on Confidence Interval Procedures for Coefficient Alpha

ERIC Educational Resources Information Center

Paek, Insu

2016-01-01

The effect of guessing on the point estimate of coefficient alpha has been studied in the literature, but the impact of guessing and its interactions with other test characteristics on the interval estimators for coefficient alpha has not been fully investigated. This study examined the impact of guessing and its interactions with other test…

Hypervelocity Impact (HVI). Volume 8; Tile Small Targets A-1, Ag-1, B-1, and Bg-1

NASA Technical Reports Server (NTRS)

Gorman, Michael R.; Ziola, Steven M.

2007-01-01

During 2003 and 2004, the Johnson Space Center's White Sands Testing Facility in Las Cruces, New Mexico conducted hypervelocity impact tests on the space shuttle wing leading edge. Hypervelocity impact tests were conducted to determine if Micro-Meteoroid/Orbital Debris impacts could be reliably detected and located using simple passive ultrasonic methods. The objective of Targets A-1, Ag-1, B-1, and Bg-1 was to study hypervelocity impacts on the reinforced Shuttle Heat Shield Tiles of the Wing. Impact damage was detected using lightweight, low power instrumentation capable of being used in flight.

Hypervelocity Impact (HVI). Volume 2; WLE Small-Scale Fiberglass Panel Flat Multi-Layer Targets A-1, A-2, and B-1

NASA Technical Reports Server (NTRS)

Gorman, Michael R.; Ziola, Steven M.

2007-01-01

During 2003 and 2004, the Johnson Space Center's White Sands Testing Facility in Las Cruces, New Mexico conducted hypervelocity impact tests on the space shuttle wing leading edge. Hypervelocity impact tests were conducted to determine if Micro-Meteoroid/Orbital Debris impacts could be reliably detected and located using simple passive ultrasonic methods. The objective of Targets A-1, A-2, and B-2 was to study hypervelocity impacts through multi-layered panels simulating Whipple shields on spacecraft. Impact damage was detected using lightweight, low power instrumentation capable of being used in flight.

Comparative Evaluation of Impact Strength of Fragment Bonded Teeth and Intact Teeth: An In Vitro Study

PubMed Central

Venugopal, L; Lakshmi, M Narasimha; Babu, Devatha Ashok; Kiran, V Ravi

2014-01-01

Background: To test and compare the impact strength of fragment bonded teeth with that of intact teeth by using impact testing machine (pendulum type) as a mode of load. Materials and Methods: Forty extracted, maxillary, central incisors selected for this study (20 control group and 20 experimental group). In experimental group, teeth crowns were fractured with a microtome at 2.5 mm from mesioincisal angle cervically, fractured portion is attached to original crown portion with 3 M single bond dentin bonding agent and 3 M Z ‘100’, composite resin. Impact strength of fragment bonded teeth and intact teeth tested with impact testing machine and compared. Results: Mean impact strength of fragment bonded teeth (30.76 KJ/M2 ) is not statistically significant deferent from mean impact strength of intact teeth (31.11 KJ/M2 ). Conclusion: Mean impact strength of fragment bonded teeth is not statistically different with that of intact teeth. Hence, after fracture of teeth if it is restored with fragment reattachment by using 3 M single bond dentin bonding agent and 3 M Z ‘100’ composite resin is having impact strength like that of intact teeth. How to cite the article: Venugopal L, Lakshmi MN, Babu DA, Kiran VR. Comparative evaluation of impact strength of fragment bonded teeth and intact teeth: An in vitro study. J Int Oral Health 2014;6(3):73-6. PMID:25083037

Teaching to and beyond the Test: The Influence of Mandated Accountability Testing in One Social Studies Teacher's Classroom

ERIC Educational Resources Information Center

Neumann, Jacob

2013-01-01

Background/Context: The nature of the impact of state-mandated accountability testing on teachers' classroom practices remains contested. While many researchers argue that teachers change their teaching in response to mandated testing, others contend that the nature and degree of the impact of testing on teaching remains unclear. The research on…

Test study on the performance of shielding configuration with stuffed layer under hypervelocity impact

NASA Astrophysics Data System (ADS)

Ke, Fa-wei; Huang, Jie; Wen, Xue-zhong; Ma, Zhao-xia; Liu, Sen

2016-10-01

In order to study the cracking and intercepting mechanism of stuffed layer configuration on the debris cloud and to develop stuffed layer configuration with better performance, the hypervelocity impact tests on shielding configurations with stuffed layer were carried out. Firstly, the hypervelocity impact tests on the shielding configuration with stuffed layer of 3 layer ceramic fibre and 3 layer aramid fibre were finished, the study results showed that the debris cloud generated by the aluminum sphere impacting bumper at the velocity of about 6.2 km/s would be racked and intercepted by the stuffed layer configuration efficiently when the ceramic fibre layers and aramid fibre layers were jointed together, however, the shielding performance would be declined when the ceramic fibre layers and aramid fibre layers were divided by some distance. The mechanism of stuffed layer racking and intercepting the debris cloud was analyzed according to the above test results. Secondly, based on the mechanism of the stuffed layer cracking and intercepint debirs cloud the hypervelocity impact tests on the following three stuffed layer structures with the equivalent areal density to the 1 mm-thick aluminum plate were also carried out to compare their performance of cracking and intercepting debris cloud. The mechanisms of stuffed layer racking and intercepting the debris cloud were validated by the test result. Thirdly, the influence of the stuffed layer position on the shielding performance was studied by the test, too. The test results would provide reference for the design of better performance shielding configuration with stuffed layer.

A damage tolerance comparison of IM7/8551 and IM8G/8553 carbon/epoxy composites

NASA Technical Reports Server (NTRS)

Lance, D. G.; Nettles, A. T.

1991-01-01

A damage tolerance study of two new toughened carbon fiber/epoxy resin systems was undertaken as a continuation of ongoing work into screening new opposites for resistance to foreign object impact. This report is intended to be a supplement to NASA TP 3029 in which four new fiber/resin systems were tested for damage tolerance. Instrumented drop weight impact testing was used to inflict damage to 16-ply quasi-isotropic specimens. Instrumented output data and cross-sectional examinations of the damage zone were utilized to quantify the damage. It was found that the two fiber/resin systems tested in this study were much more impact resistant than an untoughened composite such as T300/934, but were not as impact resistant as other materials previously studied.

Psychosocial impact of prognostic genetic testing in the care of uveal melanoma patients: protocol of a controlled prospective clinical observational study.

PubMed

Erim, Yesim; Scheel, Jennifer; Breidenstein, Anja; Metz, Claudia Hd; Lohmann, Dietmar; Friederich, Hans-Christoph; Tagay, Sefik

2016-07-07

Uveal melanoma patients with a poor prognosis can be detected through genetic analysis of the tumor, which has a very high sensitivity. A large number of patients with uveal melanoma decide to receive information about their individual risk and therefore routine prognostic genetic testing is being carried out on a growing number of patients. It is obvious that a positive prediction for recidivism in the future will emotionally burden the respective patients, but research on the psychosocial impact of this innovative method is lacking. The aim of the current study is therefore to investigate the psychosocial impact (psychological distress and quality of life) of prognostic genetic testing in patients with uveal melanoma. This study is a non-randomized controlled prospective clinical observational trial. Subjects are patients with uveal melanoma, in whom genetic testing is possible. Patients who consent to genetic testing are allocated to the intervention group and patients who refuse genetic testing form the observational group. Both groups receive cancer therapy and psycho-oncological intervention when needed. The psychosocial impact of prognostic testing is investigated with the following variables: resilience, social support, fear of tumor progression, depression, general distress, cancer-specific and general health-related quality of life, attitude towards genetic testing, estimation of the perceived risk of metastasis, utilization and satisfaction with psycho-oncological crisis intervention, and sociodemographic data. Data are assessed preoperatively (at initial admission in the clinic) and postoperatively (at discharge from hospital after surgery, 6-12 weeks, 6 and 12 months after initial admission). Genetic test results are communicated 6-12 weeks after initial admission to the clinic. We created optimal conditions for investigation of the psychosocial impact of prognostic genetic testing. This study will provide information on the course of disease and psychosocial outcomes after prognostic genetic testing. We expect that empirical data from our study will give a scientific basis for medico-ethical considerations.

Organizational Benchmarks for Test Utilization Performance: An Example Based on Positivity Rates for Genetic Tests.

PubMed

Rudolf, Joseph; Jackson, Brian R; Wilson, Andrew R; Smock, Kristi J; Schmidt, Robert L

2017-04-01

Health care organizations are under increasing pressure to deliver value by improving test utilization management. Many factors, including organizational factors, could affect utilization performance. Past research has focused on the impact of specific interventions in single organizations. The impact of organizational factors is unknown. The objective of this study is to determine whether testing patterns are subject to organizational effects, ie, are utilization patterns for individual tests correlated within organizations. Comparative analysis of ordering patterns (positivity rates for three genetic tests) across 659 organizations. Hierarchical regression was used to assess the impact of organizational factors after controlling for test-level factors (mutation prevalence) and hospital bed size. Test positivity rates were correlated within organizations. Organizations have a statistically significant impact on the positivity rate of three genetic tests. © American Society for Clinical Pathology, 2017. All rights reserved. For permissions, please e-mail: journals.permissions@oup.com

Personal Narratives of Genetic Testing: Expectations, Emotions, and Impact on Self and Family.

PubMed

Anderson, Emily E; Wasson, Katherine

2015-01-01

The stories in this volume shed light on the potential of narrative inquiry to fill gaps in knowledge, particularly given the mixed results of quantitative research on patient views of and experiences with genetic and genomic testing. Published studies investigate predictors of testing (particularly risk perceptions and worry); psychological and behavioral responses to testing; and potential impact on the health care system (e.g., when patients bring DTC genetic test results to their primary care provider). Interestingly, these themes did not dominate the narratives published in this issue. Rather, these narratives included consistent themes of expectations and looking for answers; complex emotions; areas of contradiction and conflict; and family impact. More narrative research on patient experiences with genetic testing may fill gaps in knowledge regarding how patients define the benefits of testing, changes in psychological and emotional reactions to test results over time, and the impact of testing on families.

Capabilities of the Impact Testing Facility at Marshall Space Flight Center

NASA Technical Reports Server (NTRS)

Finchum, Andy; Nehls, Mary; Young, Whitney; Gray, Perry; Suggs, Bart; Lowrey, Nikki M.

2011-01-01

The test and analysis capabilities of the Impact Testing Facility at NASA's Marshall Space Flight Center are described. Nine different gun systems accommodate a wide range of projectile and target sizes and shapes at velocities from subsonic through hypersonic, to accomplish a broad range of ballistic and hypervelocity impact tests. These gun systems include ballistic and microballistic gas and powder guns, a two-stage light gas gun, and specialty guns for weather encounter studies. The ITF "rain gun" is the only hydrometeor impact gun known to be in existence in the United States that can provide single impact performance data with known raindrop sizes. Simulation of high velocity impact is available using the Smooth Particle Hydrodynamic Code. The Impact Testing Facility provides testing, custom test configuration design and fabrication, and analytical services for NASA, the Department of Defense, academic institutions, international space agencies, and private industry in a secure facility located at Marshall Space Flight Center, on the US Army's Redstone Arsenal in Huntsville, Alabama. This facility performs tests that are subject to International Traffic in Arms Regulations (ITAR) and DoD secret classified restrictions as well as proprietary and unrestricted tests for civil space agencies, academic institutions, and commercial aerospace and defense companies and their suppliers.

Damage Tolerance of Pre-Stressed Composite Panels Under Impact Loads

NASA Astrophysics Data System (ADS)

Johnson, Alastair F.; Toso-Pentecôte, Nathalie; Schueler, Dominik

2014-02-01

An experimental test campaign studied the structural integrity of carbon fibre/epoxy panels preloaded in tension or compression then subjected to gas gun impact tests causing significant damage. The test programme used representative composite aircraft fuselage panels composed of aerospace carbon fibre toughened epoxy prepreg laminates. Preload levels in tension were representative of design limit loads for fuselage panels of this size, and maximum compression preloads were in the post-buckle region. Two main impact scenarios were considered: notch damage from a 12 mm steel cube projectile, at velocities in the range 93-136 m/s; blunt impact damage from 25 mm diameter glass balls, at velocities 64-86 m/s. The combined influence of preload and impact damage on panel residual strengths was measured and results analysed in the context of damage tolerance requirements for composite aircraft panels. The tests showed structural integrity well above design limit loads for composite panels preloaded in tension and compression with visible notch impact damage from hard body impact tests. However, blunt impact tests on buckled compression loaded panels caused large delamination damage regions which lowered plate bending stiffness and reduced significantly compression strengths in buckling.

Impact tests on fibrous composite sandwich structures

NASA Technical Reports Server (NTRS)

Rhodes, M. D.

1978-01-01

The effect of low velocity impact on the strength of laminates fabricated from graphite/epoxy and Kevlar 49/epoxy composite materials was studied. The test laminates were loaded statically either in uniaxial tension or compression when impact occurred to evaluate the effect of loading on the initiation of damage and/or failure. Typical aircraft service conditions such as runway debris encountered during landing were simulated by impacting 1.27-cm-diameter projectiles normal to the plane of the test laminates at velocities between 5.2 and 48.8 m/s.

Experimental and numerical study of drill bit drop tests on Kuru granite

NASA Astrophysics Data System (ADS)

Fourmeau, Marion; Kane, Alexandre; Hokka, Mikko

2017-01-01

This paper presents an experimental and numerical study of Kuru grey granite impacted with a seven-buttons drill bit mounted on an instrumented drop test machine. The force versus displacement curves during the impact, so-called bit-rock interaction (BRI) curves, were obtained using strain gauge measurements for two levels of impact energy. Moreover, the volume of removed rock after each drop test was evaluated by stereo-lithography (three-dimensional surface reconstruction). A modified version of the Holmquist-Johnson-Cook (MHJC) material model was calibrated using Kuru granite test results available from the literature. Numerical simulations of the single drop tests were carried out using the MHJC model available in the LS-DYNA explicit finite-element solver. The influence of the impact energy and additional confining pressure on the BRI curves and the volume of the removed rock is discussed. In addition, the influence of the rock surface shape before impact was evaluated using two different mesh geometries: a flat surface and a hyperbolic surface. The experimental and numerical results are compared and discussed in terms of drilling efficiency through the mechanical specific energy. This article is part of the themed issue 'Experimental testing and modelling of brittle materials at high strain rates'.

Methods Used in Economic Evaluations of Chronic Kidney Disease Testing — A Systematic Review

PubMed Central

Sutton, Andrew J.; Breheny, Katie; Deeks, Jon; Khunti, Kamlesh; Sharpe, Claire; Ottridge, Ryan S.; Stevens, Paul E.; Cockwell, Paul; Kalra, Philp A.; Lamb, Edmund J.

2015-01-01

Background The prevalence of chronic kidney disease (CKD) is high in general populations around the world. Targeted testing and screening for CKD are often conducted to help identify individuals that may benefit from treatment to ameliorate or prevent their disease progression. Aims This systematic review examines the methods used in economic evaluations of testing and screening in CKD, with a particular focus on whether test accuracy has been considered, and how analysis has incorporated issues that may be important to the patient, such as the impact of testing on quality of life and the costs they incur. Methods Articles that described model-based economic evaluations of patient testing interventions focused on CKD were identified through the searching of electronic databases and the hand searching of the bibliographies of the included studies. Results The initial electronic searches identified 2,671 papers of which 21 were included in the final review. Eighteen studies focused on proteinuria, three evaluated glomerular filtration rate testing and one included both tests. The full impact of inaccurate test results was frequently not considered in economic evaluations in this setting as a societal perspective was rarely adopted. The impact of false positive tests on patients in terms of the costs incurred in re-attending for repeat testing, and the anxiety associated with a positive test was almost always overlooked. In one study where the impact of a false positive test on patient quality of life was examined in sensitivity analysis, it had a significant impact on the conclusions drawn from the model. Conclusion Future economic evaluations of kidney function testing should examine testing and monitoring pathways from the perspective of patients, to ensure that issues that are important to patients, such as the possibility of inaccurate test results, are properly considered in the analysis. PMID:26465773

Quantifying Acoustic Impacts on Marine Mammals and Sea Turtles: Methods and Analytical Approach for Phase III Training and Testing

DTIC Science & Technology

2017-06-16

Acoustic Impacts on Marine Mammals and Sea Turtles: Methods and Analytical Approach for Phase III Training and Testing Sarah A. Blackstock Joseph O...December 2017 4. TITLE AND SUBTITLE Quantifying Acoustic Impacts on Marine Mammals and Sea Turtles: Methods and Analytical Approach for Phase III...Navy’s Phase III Study Areas as described in each Environmental Impact Statement/ Overseas Environmental Impact Statement and describes the methods

Hybrid Composite Laminates Reinforced with Kevlar/Carbon/Glass Woven Fabrics for Ballistic Impact Testing

PubMed Central

Randjbaran, Elias; Zahari, Rizal; Abdul Jalil, Nawal Aswan; Abang Abdul Majid, Dayang Laila

2014-01-01

Current study reported a facile method to investigate the effects of stacking sequence layers of hybrid composite materials on ballistic energy absorption by running the ballistic test at the high velocity ballistic impact conditions. The velocity and absorbed energy were accordingly calculated as well. The specimens were fabricated from Kevlar, carbon, and glass woven fabrics and resin and were experimentally investigated under impact conditions. All the specimens possessed equal mass, shape, and density; nevertheless, the layers were ordered in different stacking sequence. After running the ballistic test at the same conditions, the final velocities of the cylindrical AISI 4340 Steel pellet showed how much energy was absorbed by the samples. The energy absorption of each sample through the ballistic impact was calculated; accordingly, the proper ballistic impact resistance materials could be found by conducting the test. This paper can be further studied in order to characterise the material properties for the different layers. PMID:24955400

Modified Drop Tower Impact Tests for American Football Helmets.

PubMed

Rush, G Alston; Prabhu, R; Rush, Gus A; Williams, Lakiesha N; Horstemeyer, M F

2017-02-19

A modified National Operating Committee on Standards for Athletic Equipment (NOCSAE) test method for American football helmet drop impact test standards is presented that would provide better assessment of a helmet's on-field impact performance by including a faceguard on the helmet. In this study, a merger of faceguard and helmet test standards is proposed. The need for a more robust systematic approach to football helmet testing procedures is emphasized by comparing representative results of the Head Injury Criterion (HIC), Severity Index (SI), and peak acceleration values for different helmets at different helmet locations under modified NOCSAE standard drop tower tests. Essentially, these comparative drop test results revealed that the faceguard adds a stiffening kinematic constraint to the shell that lessens total energy absorption. The current NOCSAE standard test methods can be improved to represent on-field helmet hits by attaching the faceguards to helmets and by including two new helmet impact locations (Front Top and Front Top Boss). The reported football helmet test method gives a more accurate representation of a helmet's performance and its ability to mitigate on-field impacts while promoting safer football helmets.

The NASA JSC Hypervelocity Impact Test Facility (HIT-F)

NASA Technical Reports Server (NTRS)

Crews, Jeanne L.; Christiansen, Eric L.

1992-01-01

The NASA Johnson Space Center Hypervelocity Impact Test Facility was created in 1980 to study the hypervelocity impact characteristics of composite materials. The facility consists of the Hypervelocity Impact Laboratory (HIRL) and the Hypervelocity Analysis Laboratory (HAL). The HIRL supports three different-size light-gas gun ranges which provide the capability of launching particle sizes from 100 micron spheres to 12.7 mm cylinders. The HAL performs three functions: (1) the analysis of data collected from shots in the HIRL, (2) numerical and analytical modeling to predict impact response beyond test conditions, and (3) risk and damage assessments for spacecraft exposed to the meteoroid and orbital debris environments.

Study on Mechanical Properties of Barite Concrete under Impact Load

NASA Astrophysics Data System (ADS)

Chen, Z. F.; Cheng, K.; Wu, D.; Gan, Y. C.; Tao, Q. W.

2018-03-01

In order to research the mechanical properties of Barite concrete under impact load, a group of concrete compression tests was carried out under the impact load by using the drop test machine. A high-speed camera was used to record the failure process of the specimen during the impact process. The test results show that:with the increase of drop height, the loading rate, the peak load, the strain under peak load, the strain rate and the dynamic increase factor (DIF) all increase gradually. The ultimate tensile strain is close to each other, and the time of impact force decreases significantly, showing significant strain rate effect.

Predicting multi-wall structural response to hypervelocity impact using the hull code

NASA Technical Reports Server (NTRS)

Schonberg, William P.

1993-01-01

Previously, multi-wall structures have been analyzed extensively, primarily through experiment, as a means of increasing the meteoroid/space debris impact protection of spacecraft. As structural configurations become more varied, the number of tests required to characterize their response increases dramatically. As an alternative to experimental testing, numerical modeling of high-speed impact phenomena is often being used to predict the response of a variety of structural systems under different impact loading conditions. The results of comparing experimental tests to Hull Hydrodynamic Computer Code predictions are reported. Also, the results of a numerical parametric study of multi-wall structural response to hypervelocity cylindrical projectile impact are presented.

Is the psychological impact of genetic testing moderated by support and sharing of test results to family and friends?

PubMed

Lapointe, Julie; Dorval, Michel; Noguès, Catherine; Fabre, Roxane; Julian-Reynier, Claire

2013-12-01

Receiving the results of genetic tests for a breast and ovarian cancer susceptibility can be a stressful experience. Here we studied the effects of social support (SS) and the sharing of test results on the psychological impact of BRCA1/2 test result disclosure. We also compared carriers and non-carriers on sharing, SS and psychological impact. Five-hundred and twenty-two unaffected women were followed prospectively for 2 years after receiving their test results. Psychological impact was measured on the impact of event scale. Multivariate multi-level models were used, and all the analyses were stratified depending on mutation status (carriers vs non-carriers). Two weeks after receiving their BRCA1/2 results, carriers had shared their test results less frequently than non-carriers (p < 0.01). Sharing test results was not significantly associated with psychological impact. Availability of SS was significantly associated with better psychological adjustment across time among carriers (p < 0.01), but not among non-carriers. For female BRCA1/2 mutation carriers, the importance of SS should be stressed, and possible ways of enlisting people in their entourage for this purpose should be discussed in the context of clinical encounters.

Measuring cognitive change with ImPACT: the aggregate baseline approach.

PubMed

Bruce, Jared M; Echemendia, Ruben J; Meeuwisse, Willem; Hutchison, Michael G; Aubry, Mark; Comper, Paul

2017-11-01

The Immediate Post-Concussion Assessment and Cognitive Test (ImPACT) is commonly used to assess baseline and post-injury cognition among athletes in North America. Despite this, several studies have questioned the reliability of ImPACT when given at intervals employed in clinical practice. Poor test-retest reliability reduces test sensitivity to cognitive decline, increasing the likelihood that concussed athletes will be returned to play prematurely. We recently showed that the reliability of ImPACT can be increased when using a new composite structure and the aggregate of two baselines to predict subsequent performance. The purpose of the present study was to confirm our previous findings and determine whether the addition of a third baseline would further increase the test-retest reliability of ImPACT. Data from 97 English speaking professional hockey players who had received at least 4 ImPACT baseline evaluations were extracted from a National Hockey League Concussion Program database. Linear regression was used to determine whether each of the first three testing sessions accounted for unique variance in the fourth testing session. Results confirmed that the aggregate baseline approach improves the psychometric properties of ImPACT, with most indices demonstrating adequate or better test-retest reliability for clinical use. The aggregate baseline approach provides a modest clinical benefit when recent baselines are available - and a more substantial benefit when compared to approaches that obtain baseline measures only once during the course of a multi-year playing career. Pending confirmation in diverse samples, neuropsychologists are encouraged to use the aggregate baseline approach to best quantify cognitive change following sports concussion.

Perception on obesity among university students: A case study using factor analysis

NASA Astrophysics Data System (ADS)

Hassan, Suriani; Rahman, Nur Amira Abdol; Ghazali, Khadizah; Ismail, Norlita; Budin, Kamsia

2014-07-01

The purpose of this study was to examine the university students' perceptions on obesity and to compare the difference in mean scores factor based on demographic factors. Data was collected randomly using questionnaires. There were 321 university students participated in this study. Descriptive statistics, factor analysis, normality test, independent t test, one-way ANOVA and non-parametric tests were used in this study. Factor analysis results managed to retrieve three new factors namely impact of the health, impact of the physical appearance and personal factors. The study found that Science students have higher awareness and perceptions than Art students on Factor 1, impact of the health towards overweight problems and obesity. The findings of the study showed students, whose family background has obesity problem have higher awareness and perceptions than students' whose family background has no obesity problem on Factor 1, impact of the health towards overweight problems and obesity. The study also found that students' whose father with primary school level had the lowest awareness and perceptions on Factor 2, impact of the physical appearance towards overweight problems and obesity than other students whose father with higher academic level.

High-Impact Aerobic and Zumba Fitness on Increasing VO2MAX, Heart Rate Recovery and Skinfold Thickness

NASA Astrophysics Data System (ADS)

Suminar, T. J.; Kusnanik, N. W.; Wiriawan, O.

2018-01-01

Purpose of this study is to determine the significant effect of high-impact aerobics exercise, and Zumba fitness on increasing VO2Max, decreasing of heart rate recovery, and decreasing of skinfold thickness. A sample of this study is 30 members aerobics of student activity unit. Type of this study was quantitative by using a quasi-experimental design method. The design of this study used Matching-Only Design. Data were Analyzed by using the t test (paired t-test). The samples divided into three groups consisted of experimental group I, experimental group II, and control group. They were given a treatment for 8 weeks or 24 meeting. For the data, retrieval is done by MFT test, heart rate recovery test, and skinfold thickness test. Furthermore, the result was analyzed by using SPSS 21 series. In conclusion, significant effect of high-impact aerobics and Zumba fitness on increasing VO2Max, heart rate recovery, skinfold thickness.

The euglobulin clot lysis time to assess the impact of nanoparticles on fibrinolysis

NASA Astrophysics Data System (ADS)

Minet, Valentine; Alpan, Lutfiye; Mullier, François; Toussaint, Olivier; Lucas, Stéphane; Dogné, Jean-Michel; Laloy, Julie

2015-07-01

Nanoparticles (NPs) are developed for many applications in various fields, including nanomedicine. The NPs used in nanomedicine may disturb homeostasis in blood. Secondary hemostasis (blood coagulation) and fibrinolysis are complex physiological processes regulated by activators and inhibitors. An imbalance of this system can either lead to the development of hemorrhages or thrombosis. No data are currently available on the impact of NPs on fibrinolysis. The objectives of this study are (1) to select a screening test to study ex vivo the impact of NPs on fibrinolysis and (2) to test NPs with different physicochemical properties. Euglobulin clot lysis time test was selected to screen the impact of some NPs on fibrinolysis using normal pooled plasma. A dose-dependent decrease in the lysis time was observed with silicon dioxide and silver NPs without disturbing the fibrin network. Carbon black, silicon carbide, and copper oxide did not affect the lysis time at the tested concentrations.

Ballistic impact resistance of selected organic ophthalmic lenses.

PubMed

Chou, B Ralph; Yuen, Gloria S-C; Dain, Stephen J

2011-11-01

The aim was to assess the impact resistance of coated and uncoated mid-index spectacle lens materials using the ballistic impact test. Nominally plano lenses of each material in three thicknesses were obtained. The lenses were flat edged to a 50 mm diameter. Each lens was impacted by a 6.35 mm steel ball. Impact velocities were selected using the Zippy Estimation by Sequential Testing protocol to determine the threshold fracture impact velocity. Threshold fracture impact velocity generally increased with thickness; however, there was a wide variation in performance among the various lens materials at each thickness. In all but two instances, the differences in impact velocity at each thickness of lens material were significant. Comparison of the data for CR39 and Hoya Phoenix with the results of earlier studies showed that the lens mounting is a significant factor. The fracture velocities found in the present study were significantly lower than the fracture velocities found when the lens edge is restrained in the mounting. A scratch resistant coating reduced the impact resistance of CR39. The effect of the antireflection coating on the fracture velocity depended on the nature of the base scratch-resistant coating. Mid-index lens materials of the same thickness show widely varying levels of impact resistance under the ballistic test. Impact resistance increases non-linearly with centre thickness. The lens mounting might affect the results of the ballistic impact test. The presence of 'cushion coatings' might enhance impact resistance. © 2011 The Authors. Clinical and Experimental Optometry © 2011 Optometrists Association Australia.

The Impact of Cooperative Learning on Tertiary EFL Learners' Motivation

ERIC Educational Resources Information Center

Ning, Huiping; Hornby, Garry

2014-01-01

This study was aimed at investigating the impact of cooperative learning on the motivation of tertiary English learners. Participants were from two randomly assigned classes at a university in the north of China. A pre-test-post-test control group design was employed to compare the impact of the cooperative learning approach with that of…

Room-Temperature Charpy Impact Property of 3D-Printed 15-5 Stainless Steel

NASA Astrophysics Data System (ADS)

Sagar, Sugrim; Zhang, Yi; Wu, Linmin; Park, Hye-Young; Lee, Je-Hyun; Jung, Yeon-Gil; Zhang, Jing

2018-01-01

In this study, the room-temperature Charpy impact property of 3D-printed 15-5 stainless steel was investigated by a combined experimental and finite element modeling approach. The experimentally measured impact energy is 10.85 ± 1.20 J/cm2, which is comparable to the conventionally wrought and non-heat treated 15-5 stainless steel. In parallel to the impact test experiment, a finite element model using the Johnson-Cook material model with damage parameters was developed to simulate the impact test. The simulated impact energy is 10.46 J/cm2, which is in good agreement with the experimental data. The fracture surface from the experimentally tested specimen suggests that the 3D-printed specimens undergo predominately brittle fracture.

The Impact of Cooperative Learning on Critical Thinking Test Scores of Associate's Degree Graduates in Southwest Virginia

ERIC Educational Resources Information Center

Hodges, James Gregory

2013-01-01

This study examined the impact that the teaching technique known as cooperative learning had on the changes between pre- and post-test scores on all sub-categories ("induction, deduction, analysis, evaluation, inference", and "total composite") associated with the "California Critical Thinking Skills Test" (CCTST) for…

Can Ethics Be Taught? A Quasi-Experimental Study of the Impact of Class Size on the Cognitive Moral Reasoning of Freshmen Business Students

ERIC Educational Resources Information Center

Sullivan, Ethan A.

2011-01-01

The purpose of this study was to determine the impact of a business ethics course on the cognitive moral reasoning of freshmen business students. The sample consisted of 268 college students enrolled in a required business ethics course. The students took Rest's Defining Issues Test--Version 2 (DIT2) as a pre-test and then post-test (upon…

Performance Evaluation of Pressure Transducers for Water Impacts

NASA Technical Reports Server (NTRS)

Vassilakos, Gregory J.; Stegall, David E.; Treadway, Sean

2012-01-01

The Orion Multi-Purpose Crew Vehicle is being designed for water landings. In order to benchmark the ability of engineering tools to predict water landing loads, test programs are underway for scale model and full-scale water impacts. These test programs are predicated on the reliable measurement of impact pressure histories. Tests have been performed with a variety of pressure transducers from various manufacturers. Both piezoelectric and piezoresistive devices have been tested. Effects such as thermal shock, pinching of the transducer head, and flushness of the transducer mounting have been studied. Data acquisition issues such as sampling rate and anti-aliasing filtering also have been studied. The response of pressure transducers have been compared side-by-side on an impulse test rig and on a 20-inch diameter hemisphere dropped into a pool of water. The results have identified a range of viable configurations for pressure measurement dependent on the objectives of the test program.

Top tether effectiveness during side impacts.

PubMed

Majstorovic, Jordan; Bing, Julie; Dahle, Eric; Bolte, John; Kang, Yun-Seok

2018-02-28

Few studies have looked at the effectiveness of the top tether during side impacts. In these studies, limited anthropomorphic test device (ATD) data were collected and/or few side impact scenarios were observed. The goal of this study was to further understand the effects of the top tether on ATD responses and child restraint system (CRS) kinematics during various side impact conditions. A series of high-speed near-side and far-side sled tests were performed using the FMVSS213 side impact sled buck and Q3s ATD. Tests were performed at both 10° and 30° impacts with respect to the pure lateral direction. Two child restraints, CRS A and CRS B, were attached to the bench using flexible lower anchors. Each test scenario was performed with the presence and absence of a top tether. Instrumentation recorded Q3s responses and CRS kinematics, and the identical test scenarios with and without a top tether attachment were compared. For the far-side lateral (10°) and oblique (30°) impacts, top tether attachment increased resultant head accelerations by 8-38% and head injury criterion (HIC 15 ) values by 20-140%. However, the top tether was effective in reducing lateral head excursion by 5-25%. For near-side impacts, the top tether resulted in less than 10% increases in both resultant head acceleration and HIC 15 in the lateral impact direction. For near-side oblique impacts, the top tether increased HIC 15 by 17.3% for CRS A and decreased it by 19.5% for CRS B. However, the injury values determined from both impact conditions were below current injury assessment reference values (IARVs). Additionally, the top tether proved beneficial in preventing forward and lateral CRS rotations. The results show that the effects of the top tether on Q3s responses were dependent on impact type, impact angle, and CRS. Tether attachments that increased head accelerations and HIC 15 values were generally counterbalanced by a reduction in head excursion and CRS rotation compared to nontethered scenarios.

HIV Testing Among Young People Aged 16-24 in South Africa: Impact of Mass Media Communication Programs.

PubMed

Do, Mai; Figueroa, Maria Elena; Lawrence Kincaid, D

2016-09-01

Knowing one's serostatus is critical in the HIV prevention, care and treatment continuum. This study examines the impact of communication programs on HIV testing in South Africa. Data came from 2204 young men and women aged 16-24 who reported to be sexually active in a population based survey. Structural equation modeling was used to test the directions and causal pathways between communication program exposure, HIV testing discussion, and having a test in the last 12 months. Bivariate and multivariate probit regressions provided evidence of exogeneity of communication exposure and the two HIV-related outcomes. One in three sampled individuals had been tested in the last 12 months. Communication program exposure only had an indirect effect on getting tested by encouraging young people to talk about testing. The study suggests that communication programs may create an environment that supports open HIV-related discussions and may have a long-term impact on behavior change.

Use of LS-DYNA(Registered TradeMark) to Assess the Energy Absorption Performance of a Shell-Based Kevlar(TradeMark)/Epoxy Composite Honeycomb

NASA Technical Reports Server (NTRS)

Polanco, Michael

2010-01-01

The forward and vertical impact stability of a composite honeycomb Deployable Energy Absorber (DEA) was evaluated during a full-scale crash test of an MD-500 helicopter at NASA Langley?s Landing and Impact Research Facility. The lower skin of the helicopter was retrofitted with DEA components to protect the airframe subfloor upon impact and to mitigate loads transmitted to Anthropomorphic Test Device (ATD) occupants. To facilitate the design of the DEA for this test, an analytical study was conducted using LS-DYNA(Registered TradeMark) to evaluate the performance of a shell-based DEA incorporating different angular cell orientations as well as simultaneous vertical and forward impact conditions. By conducting this study, guidance was provided in obtaining an optimum design for the DEA that would dissipate the kinetic energy of the airframe while maintaining forward and vertical impact stability.

Using Numerical Modeling to Simulate Space Capsule Ground Landings

NASA Technical Reports Server (NTRS)

Heymsfield, Ernie; Fasanella, Edwin L.

2009-01-01

Experimental work is being conducted at the National Aeronautics and Space Administration s (NASA) Langley Research Center (LaRC) to investigate ground landing capabilities of the Orion crew exploration vehicle (CEV). The Orion capsule is NASA s replacement for the Space Shuttle. The Orion capsule will service the International Space Station and be used for future space missions to the Moon and to Mars. To evaluate the feasibility of Orion ground landings, a series of capsule impact tests are being performed at the NASA Langley Landing and Impact Research Facility (LandIR). The experimental results derived at LandIR provide means to validate and calibrate nonlinear dynamic finite element models, which are also being developed during this study. Because of the high cost and time involvement intrinsic to full-scale testing, numerical simulations are favored over experimental work. Subsequent to a numerical model validated by actual test responses, impact simulations will be conducted to study multiple impact scenarios not practical to test. Twenty-one swing tests using the LandIR gantry were conducted during the June 07 through October 07 time period to evaluate the Orion s impact response. Results for two capsule initial pitch angles, 0deg and -15deg , along with their computer simulations using LS-DYNA are presented in this article. A soil-vehicle friction coefficient of 0.45 was determined by comparing the test stopping distance with computer simulations. In addition, soil modeling accuracy is presented by comparing vertical penetrometer impact tests with computer simulations for the soil model used during the swing tests.

Simulations of hypervelocity impacts for asteroid deflection studies

NASA Astrophysics Data System (ADS)

Heberling, T.; Ferguson, J. M.; Gisler, G. R.; Plesko, C. S.; Weaver, R.

2016-12-01

The possibility of kinetic-impact deflection of threatening near-earth asteroids will be tested for the first time in the proposed AIDA (Asteroid Impact Deflection Assessment) mission, involving two independent spacecraft, NASAs DART (Double Asteroid Redirection Test) and ESAs AIM (Asteroid Impact Mission). The impact of the DART spacecraft onto the secondary of the binary asteroid 65803 Didymos, at a speed of 5 to 7 km/s, is expected to alter the mutual orbit by an observable amount. The velocity imparted to the secondary depends on the geometry and dynamics of the impact, and especially on the momentum enhancement factor, conventionally called beta. We use the Los Alamos hydrocodes Rage and Pagosa to estimate beta in laboratory-scale benchmark experiments and in the large-scale asteroid deflection test. Simulations are performed in two- and three-dimensions, using a variety of equations of state and strength models for both the lab-scale and large-scale cases. This work is being performed as part of a systematic benchmarking study for the AIDA mission that includes other hydrocodes.

A Study of the "toss Factor" in the Impact Testing of Cermets by the Izod Pendulum Test

NASA Technical Reports Server (NTRS)

Probst, H B; Mchenry, Howard T

1957-01-01

The test method presented shows that the "toss energy" contributed by the apparatus for brittle materials is negligible. The total toss energy is considered to consist of two components. (a) recovered stored elastic energy and (b) kinetic energy contributed directly by the apparatus. The results were verified by high-speed motion pictures of the test in operation. From these photographs, velocities of tossed specimens were obtained and toss energy computed. In addition, impact energies of some titanium carbide base cermets and high-temperature alloys, as measured by the low-capacity Izod pendulum test, compare well with impact energies measured by the NACA drop test.

Comparing Learning Style to Performance in On-Line Teaching: Impact of Proctored v. Un-Proctored Testing

ERIC Educational Resources Information Center

Wellman, Gregory S.

2005-01-01

The purpose of this study was to examine the impact that proctored versus un-proctored testing would have on learning for an on-line content module; and examine the relationship between LASSI variables and learning. A randomized, pre-test/post-test control group design was employed. College students in a pharmacy curriculum, were randomized to two…

Anonymous HIV testing: the impact of availability on demand in Arizona.

PubMed Central

Hirano, D; Gellert, G A; Fleming, K; Boyd, D; Englender, S J; Hawks, H

1994-01-01

The purpose of this study was to evaluate the impact of anonymous testing availability on human immunodeficiency virus (HIV) test demand in Arizona. Testing patterns before and after the introduction of anonymous testing were compared. Client knowledge of new test policy and delay in testing until an anonymous option was available were assessed. Test numbers among men who have sex with men showed a statistically significant increase after introduction of an anonymous testing option. Arizona continues to maintain anonymous testing availability. Public health agencies should consider how test policy may influence people's HIV test decisions. PMID:7998649

Experimental and numerical study of drill bit drop tests on Kuru granite.

PubMed

Fourmeau, Marion; Kane, Alexandre; Hokka, Mikko

2017-01-28

This paper presents an experimental and numerical study of Kuru grey granite impacted with a seven-buttons drill bit mounted on an instrumented drop test machine. The force versus displacement curves during the impact, so-called bit-rock interaction (BRI) curves, were obtained using strain gauge measurements for two levels of impact energy. Moreover, the volume of removed rock after each drop test was evaluated by stereo-lithography (three-dimensional surface reconstruction). A modified version of the Holmquist-Johnson-Cook (MHJC) material model was calibrated using Kuru granite test results available from the literature. Numerical simulations of the single drop tests were carried out using the MHJC model available in the LS-DYNA explicit finite-element solver. The influence of the impact energy and additional confining pressure on the BRI curves and the volume of the removed rock is discussed. In addition, the influence of the rock surface shape before impact was evaluated using two different mesh geometries: a flat surface and a hyperbolic surface. The experimental and numerical results are compared and discussed in terms of drilling efficiency through the mechanical specific energy.This article is part of the themed issue 'Experimental testing and modelling of brittle materials at high strain rates'. © 2016 The Author(s).

Experimental and numerical study of drill bit drop tests on Kuru granite

PubMed Central

Kane, Alexandre; Hokka, Mikko

2017-01-01

This paper presents an experimental and numerical study of Kuru grey granite impacted with a seven-buttons drill bit mounted on an instrumented drop test machine. The force versus displacement curves during the impact, so-called bit–rock interaction (BRI) curves, were obtained using strain gauge measurements for two levels of impact energy. Moreover, the volume of removed rock after each drop test was evaluated by stereo-lithography (three-dimensional surface reconstruction). A modified version of the Holmquist–Johnson–Cook (MHJC) material model was calibrated using Kuru granite test results available from the literature. Numerical simulations of the single drop tests were carried out using the MHJC model available in the LS-DYNA explicit finite-element solver. The influence of the impact energy and additional confining pressure on the BRI curves and the volume of the removed rock is discussed. In addition, the influence of the rock surface shape before impact was evaluated using two different mesh geometries: a flat surface and a hyperbolic surface. The experimental and numerical results are compared and discussed in terms of drilling efficiency through the mechanical specific energy. This article is part of the themed issue ‘Experimental testing and modelling of brittle materials at high strain rates’. PMID:27956511

The Impact Analysis of Psychological Reliability of Population Pilot Study for Selection of Particular Reliable Multi-Choice Item Test in Foreign Language Research Work

ERIC Educational Resources Information Center

Fazeli, Seyed Hossein

2010-01-01

The purpose of research described in the current study is the psychological reliability, its importance, application, and more to investigate on the impact analysis of psychological reliability of population pilot study for selection of particular reliable multi-choice item test in foreign language research work. The population for subject…

Development and Validation of an Instrument to Assess the Impact of Cyberbullying: The Cybervictimization Emotional Impact Scale.

PubMed

Elipe, Paz; Mora-Merchán, Joaquín A; Nacimiento, Lydia

2017-08-01

Cyberbullying is a phenomenon with important adverse consequences on victims. The emotional impact of this phenomenon has been well established. However, there is to date no instrument with good psychometric properties tested to assess such impact. The objective of this study was developing and testing the psychometric properties of an instrument to assess the emotional impact of cyberbullying: the "Cybervictimization Emotional Impact Scale, CVEIS." The sample included 1,016 Compulsory Secondary Education students (52.9 percent female) aged between 12 and 18 (M = 13.86, DT = 1.33) from three schools in southern Spain. The study used Confirmatory Factor Analyses to test the structure of the questionnaire and robustness of the scale. Internal consistency was also tested. The results supported the suitability of a three-factor model: active, depressed, and annoyed. This model showed an optimal adjustment, which was better than its competing models. It also demonstrated strong invariance among cybervictims and non-cybervictims and also among gender. The internal consistency of each factor, and the total scale, was also appropriate. The article concludes by discussing research and practical implications of the scale.

Characterization of pediatric wheelchair kinematics and wheelchair tiedown and occupant restraint system loading during rear impact.

PubMed

Fuhrman, Susan I; Karg, Patricia; Bertocci, Gina

2010-04-01

This study characterizes pediatric wheelchair kinematic responses and wheelchair tiedown and occupant restraint system (WTORS) loading during rear impact. It also examines the kinematic and loading effects of wheelchair headrest inclusion in rear impact. In two separate rear-impact test scenarios, identical WC19-compliant manual pediatric wheelchairs were tested using a seated Hybrid III 6-year-old anthropomorphic test device (ATD) to evaluate wheelchair kinematics and WTORS loading. Three wheelchairs included no headrests, and three were equipped with slightly modified wheelchair-mounted headrests. Surrogate WTORS properly secured the wheelchairs; three-point occupant restraints properly restrained the ATD. All tests used a 26km/h, 11g rear-impact test pulse. Headrest presence affected wheelchair kinematics and WTORS loading; headrest-equipped wheelchairs had greater mean seatback deflections, mean peak front and rear tiedown loads and decreased mean lap belt loads. Rear-impact tiedown loads differed from previously measured loads in frontal impact, with comparable tiedown load levels reversed in frontal and rear impacts. The front tiedowns in rear impact had the highest mean peak loads despite lower rear-impact severity. These outcomes have implications for wheelchair and tiedown design, highlighting the need for all four tiedowns to have an equally robust design, and have implications in the development of rear-impact wheelchair transportation safety standards. Copyright 2009 IPEM. Published by Elsevier Ltd. All rights reserved.

Ethics Standards Impacting Test Development and Use: A Review of 31 Ethics Codes Impacting Practices in 35 Countries

ERIC Educational Resources Information Center

Leach, Mark M.; Oakland, Thomas

2007-01-01

Ethics codes are designed to protect the public by prescribing behaviors professionals are expected to exhibit. Although test use is universal, albeit reflecting strong Western influences, previous studies that examine the degree issues pertaining to test development and use and that are addressed in ethics codes of national psychological…

Urineschool: A Study of the Impact of the Earls Decision on High School Random Drug Testing Policies.

ERIC Educational Resources Information Center

Conlon, Cynthia Kelly

2003-01-01

Examines impact of Supreme Court's 2002 decision in "Board of Education v. Earls" on high school random drug-testing policies and practices. Court held that random drug-testing policy at Tecumseh, Oklahoma, school district did not violate students' Fourth Amendment right against unreasonable searches. (Contains 46 references.) (PKP)

Detection of impact damage on thermal protection systems using thin-film piezoelectric sensors for integrated structural health monitoring

NASA Astrophysics Data System (ADS)

Na, Jeong K.; Kuhr, Samuel J.; Jata, Kumar V.

2008-03-01

Thermal Protection Systems (TPS) can be subjected to impact damage during flight and/or during ground maintenance and/or repair. AFRL/RXLP is developing a reliable and robust on-board sensing/monitoring capability for next generation thermal protection systems to detect and assess impact damage. This study was focused on two classes of metallic thermal protection tiles to determine threshold for impact damage and develop sensing capability of the impacts. Sensors made of PVDF piezoelectric film were employed and tested to evaluate the detectability of impact signals and assess the onset or threshold of impact damage. Testing was performed over a range of impact energy levels, where the sensors were adhered to the back of the specimens. The PVDF signal levels were analyzed and compared to assess damage, where digital microscopy, visual inspection, and white light interferometry were used for damage verification. Based on the impact test results, an assessment of the impact damage thresholds for each type of metallic TPS system was made.

Durability Assessment of Gamma Tial

NASA Technical Reports Server (NTRS)

Draper, Susan L.; Lerch, Bradley A.; Pereira, J. Michael; Miyoshi, Kazuhisa; Arya, Vinod K.; Zhuang, Wyman

2004-01-01

Gamma TiAl was evaluated as a candidate alloy for low-pressure turbine blades in aeroengines. The durability of g-TiAl was studied by examining the effects of impact or fretting on its fatigue strength. Cast-to-size Ti-48Al-2Cr-2Nb was studied in impact testing with different size projectiles at various impact energies as the reference alloy and subsequently fatigue tested. Impacting degraded the residual fatigue life. However, under the ballistic impact conditions studied, it was concluded that the impacts expected in an aeroengine would not result in catastrophic damage, nor would the damage be severe enough to result in a fatigue failure under the anticipated design loads. In addition, other gamma alloys were investigated including another cast-to-size alloy, several cast and machined specimens, and a forged alloy. Within this Ti-48-2-2 family of alloys aluminum content was also varied. The cracking patterns as a result of impacting were documented and correlated with impact variables. The cracking type and severity was reasonably predicted using finite element models. Mean stress affects were also studied on impact-damaged fatigue samples. The fatigue strength was accurately predicted based on the flaw size using a threshold-based, fracture mechanics approach. To study the effects of wear due to potential applications in a blade-disk dovetail arrangement, the machined Ti-47-2-2 alloy was fretted against In-718 using pin-on-disk experiments. Wear mechanisms were documented and compared to those of Ti-6Al-4V. A few fatigue samples were also fretted and subsequently fatigue tested. It was found that under the conditions studied, the fretting was not severe enough to affect the fatigue strength of g-TiAl.

Ultrasonic Assessment of Impact-Induced Damage and Microcracking in Polymer Matrix Composites

NASA Technical Reports Server (NTRS)

Liaw, Benjamin; Zeichner, Glenn; Liu, Yanxiong; Bowles, Kenneth J. (Technical Monitor)

2000-01-01

The main objective of this NASA FAR project is to conduct ultrasonic assessment of impact-induced damage and microcracking in polymer matrix composites at various temperatures. It is believed that the proposed study of impact damage assessment on polymer matrix composites will benefit several NASA's missions and current interests, such as ballistic impact testing of composite fan containment and high strain rate deformation modeling of polymer matrix composites. Currently, impact-induced delamination and fracture in 6061-T6 aluminum/cast acrylic sandwich plates adhered by epoxy were generated in an instrumented drop-weight impact machine. Although only a small dent was produced on the aluminum side when a hemispherical penetrator tup was dropped onto it from a couple of inches, a large ring of delamination at the interface was observed. The delamination damage was often accompanied by severe shattering in the acrylic substratum. Damage patterns in the acrylic layer include radial and ring cracks and, together with delamination at the interface, may cause peeling-off of acrylic material from the sandwich plate. Theory of stress-wave propagation can be used to explain these damage patterns. The impact tests were conducted at various temperatures. The results also show clearly that temperature effect is very important in impact damage. For pure cast acrylic nil-ductile transition (NDT) occurs between 185-195 F Excessive impact energy was dissipated into fracture energy when tested at temperature below this range or through plastic deformation when tested at temperature above the NDT temperature. Results from this study will be used as baseline data for studying fiber-metal laminates, such as GLARE and ARALL for advanced aeronautical and astronautical applications.

Game-Based Assessment: Investigating the Impact on Test Anxiety and Exam Performance

ERIC Educational Resources Information Center

Mavridis, A.; Tsiatsos, T.

2017-01-01

The aim of this study is to assess the impact of a 3D educational computer game on students' test anxiety and exam performance when used in evaluative situations as compared to the traditional method of examination. The participants of the study were students in tertiary education who were examined using game-based assessment and traditional…

The Impact of Authentic Material Use on Development of the Reading Comprehension, Writing Skills and Motivation in Language Course

ERIC Educational Resources Information Center

Belet Boyaci, S. Dilek; Güner, Mediha

2018-01-01

The objective of the present study was to determine the impact of authentic task-based authentic material on reading comprehension, writing skills and writing motivation in the Turkish language course. The study was conducted with mixed design methodology. Quantitative data were collected with the quasi-experimental with pre-test post-test with…

The Impact of Using Music on Teaching English Poetry in Jordanian Universities

ERIC Educational Resources Information Center

Hijazi, Dima; Al-natour, Amal

2012-01-01

The purpose of this study is to investigate the impact of using music on teaching English Poetry in Jordanian universities on students' performance. The researchers followed the equivalent pre/post T test two group designs. To achieve the aim of the study, a pre/post-test was constructed to measure students' performance in English poetry. The…

Simple go/no-go test for subcritical damage in body armor panels

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

Fisher, Jason; Chimenti, D. E.

2011-06-23

The development of a simple test for subcritical damage in body armor panels using pressure-sensitive dye-indicator film has been performed and demonstrated effective. Measurements have shown that static indicator levels are accurately reproduced in dynamic loading events. Impacts from hard blunt impactors instrumented with an accelerometer and embedded force transducer were studied. Reliable correlations between the indicator film and instrumented impact force are shown for a range of impact energies. Force and acceleration waveforms with corresponding indicator film results are presented for impact events onto damaged and undamaged panels. We find that panel damage can occur at impact levels farmore » below the National Institute of Justice acceptance test standard.« less

Prediction of the effect of temperature on impact damage in carbon/epoxy laminates

NASA Astrophysics Data System (ADS)

Gómez del Río, T.; Zaera, R.; Navarro, C.

2003-09-01

The effect of temperature on impact damage in Carbon Fiber Reinforced Plastic (CFRP) tape laminates produced by low velocity impact was studied by numerical simulations made to model drop weight tower impact tests on carbon/epoxy laminate composites. The damage model was implemented into a user subroutine of the finite element code ABAQUS. The model takes into account the thermal stresses resulting form the different thermal expansion coefficients in each ply of the laminate. The tests and simulations show how temperature affects the propagation of each damage mode. Matrix cracking and delamination are greatly affected by low temperature, white matrix crushing and fibre failure appear only in a small region at all the impact energies and test temperatures.

Effect of fiber fibrillation on impact and flexural strength of coir fiber reinforced epoxy hybrid composites

NASA Astrophysics Data System (ADS)

Mawardi, I.; Jufriadi; Hanif

2018-03-01

This study aims to develop fiber-reinforced epoxy resin composites. This study presents the effect of fiber fibrillation on the impact and flextural strength of the epoxy hybrid composite reinforced by coir fiber. Coir is soaked in 5% NaOH solution for 5 hours. Then fiber is rocessed using a blender of 2000 rpm density fibrillation. The length of time the fibrillation varied for 10, 20 and 30 minutes. Volume fraction of 30% fiber and matrix 70% composited. The composite uses a matrix of epoxy by hand lay up method. The implemented tests are impact and flexural tests. The test results show fiber fibrillation treatment can improve the composite mechanical properties. The highest impact and flexural strength, 24.45 kJ/m2 and 87.91 MPa were produced with fiber fibrillation for 10 minutes.

Safety assessment characteristics of pedestrian legform impactors in vehicle-front impact tests.

PubMed

Matsui, Yasuhiro

2014-12-01

This study investigated the characteristics of safety assessment results of front-area vehicle impact tests carried out using the Transport Research Laboratory (TRL) legform impactor and a flexible legform impactor (FLEX legform impactor). Different types of vehicles (sedan, sport utility vehicle, high-roof K-car, and light cargo van) were examined. The impact locations in the study were the center of the bumper and an extremely stiff structure of the bumper (i.e., in front of the side member) of each tested vehicle. The measured injury criteria were normalized by injury assessment reference values of each legform impactor. The test results for center and side-member impacts indicated that there were no significant differences in ligament injury assessments derived from the normalized knee ligament injury measures between the TRL legform impactor and the FLEX legform impactor. Evaluations made using the TRL legform impactor and the FLEX legform impactor are thus similar in the vehicle safety investigation for knee ligament injury. Vehicle-center impact test results revealed that the tibia fracture assessments derived from the normalized tibia fracture measures did not significantly differ between the TRL legform impactor and the FLEX legform impactor. However, for an impact against an extremely stiff structure, there was a difference in the tibia fracture assessment between the FLEX legform impactor and the TRL legform impactor owing to their different sensor types. Copyright © 2014 Elsevier Ltd. All rights reserved.

Occurrence of serious injury in real-world side impacts of vehicles with good side-impact protection ratings.

PubMed

Brumbelow, Matthew L; Mueller, Becky C; Arbelaez, Raul A

2015-01-01

The Insurance Institute for Highway Safety (IIHS) introduced its side impact consumer information test program in 2003. Since that time, side airbags and structural improvements have been implemented across the fleet and the proportion of good ratings has increased to 93% of 2012-2014 model year vehicles. Research has shown that drivers of good-rated vehicles are 70% less likely to die in a left-side crash than drivers of poor-rated vehicles. Despite these improvements, side impact fatalities accounted for about one quarter of passenger vehicle occupant fatalities in 2012. This study is a detailed analysis of real-world cases with serious injury resulting from side crashes of vehicles with good ratings in the IIHS side impact test. NASS-CDS and Crash Injury Research and Engineering Network (CIREN) were queried for occupants of good-rated vehicles who sustained an Abbreviated Injury Scale (AIS) ≥ 3 injury in a side-impact crash. The resulting 110 cases were categorized by impact configuration and other factors that contributed to injury. Patterns of impact configuration, restraint performance, and occupant injury were identified and discussed in the context of potential upgrades to the current IIHS side impact test. Three quarters of the injured occupants were involved in near-side impacts. For these occupants, the most common factors contributing to injury were crash severities greater than the IIHS test, inadequate side-airbag performance, and lack of side-airbag coverage for the injured body region. In the cases where an airbag was present but did not prevent the injury, occupants were often exposed to loading centered farther forward on the vehicle than in the IIHS test. Around 40% of the far-side occupants were injured from contact with the struck-side interior structure, and almost all of these cases were more severe than the IIHS test. The remaining far-side occupants were mostly elderly and sustained injury from the center console, instrument panel, or seat belt. In addition, many far-side occupants were likely out of position due to events preceding the side impact and/or being unbelted. Individual changes to the IIHS side impact test have the potential to reduce the number of serious injuries in real-world crashes. These include impacting the vehicle farther forward (relevant to 28% of all cases studied), greater test severity (17%), the inclusion of far-side occupants (9%), and more restrictive injury criteria (9%). Combinations of these changes could be more effective.

Permeability After Impact Testing of Composite Laminates

NASA Technical Reports Server (NTRS)

Nettles, Alan T.

2003-01-01

Since composite laminates are beginning to be identified for use in reusable launch vehicle propulsion systems, an understanding of their permeance is needed. A foreign object impact event can cause a localized area of permeability (leakage) in a polymer matrix composite and it is the aim of this study to assess a method of quantifying permeability-after-impact results. A simple test apparatus is presented and variables that could affect the measured values of permeability-after-impact were assessed. Once it was determined that valid numbers were being measured, a fiber/resin system was impacted at various impact levels and the resulting permeability measured, first with a leak check solution (qualitative) then using the new apparatus (quantitative). The results showed that as the impact level increased, so did the measured leakage. As the pressure to the specimen was increased, the leak rate was seen to increase in a non-linear fashion for almost all of the specimens tested.

Permeability After Impact Testing of Composite Laminates

NASA Technical Reports Server (NTRS)

Nettles, A.T.; Munafo, Paul (Technical Monitor)

2002-01-01

Since composite laminates are beginning to be identified for use in reusable launch vehicle propulsion systems, an understanding of their permeance is needed. A foreign object impact event can cause a localized area of permeability (leakage) in a polymer matrix composite and it is the aim of this study to assess a method of quantifying permeability-after-impact results. A simple test apparatus is presented and variables that could affect the measured values of permeability-after-impact were assessed. Once it was determined that valid numbers were being measured, a fiber/resin system was impacted at various impact levels and the resulting permeability measured, first with a leak check solution (qualitative) then using the new apparatus (quantitative). The results showed that as the impact level increased, so did the measured leakage. As the pressure to the specimen was increased, the leak rate was seen to increase in a non-linear fashion for almost all of the specimens tested.

The Impact of Linking Distinct Achievement Test Scores on the Interpretation of Student Growth in Achievement

ERIC Educational Resources Information Center

Airola, Denise Tobin

2011-01-01

Changes to state tests impact the ability of State Education Agencies (SEAs) to monitor change in performance over time. The purpose of this study was to evaluate the Standardized Performance Growth Index (PGIz), a proposed statistical model for measuring change in student and school performance, across transitions in tests. The PGIz is a…

Validation Study of Unnotched Charpy and Taylor-Anvil Impact Experiments using Kayenta

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

Kamojjala, Krishna; Lacy, Jeffrey; Chu, Henry S.

2015-03-01

Validation of a single computational model with multiple available strain-to-failure fracture theories is presented through experimental tests and numerical simulations of the standardized unnotched Charpy and Taylor-anvil impact tests, both run using the same material model (Kayenta). Unnotched Charpy tests are performed on rolled homogeneous armor steel. The fracture patterns using Kayenta’s various failure options that include aleatory uncertainty and scale effects are compared against the experiments. Other quantities of interest include the average value of the absorbed energy and bend angle of the specimen. Taylor-anvil impact tests are performed on Ti6Al4V titanium alloy. The impact speeds of the specimenmore » are 321 m/s and 393 m/s. The goal of the numerical work is to reproduce the damage patterns observed in the laboratory. For the numerical study, the Johnson-Cook failure model is used as the ductile fracture criterion, and aleatory uncertainty is applied to rate-dependence parameters to explore its effect on the fracture patterns.« less

Low Velocity Impact Testing and Nondestructive Evaluation of Transparent Materials

NASA Astrophysics Data System (ADS)

Brennan, R. E.; Green, W. H.

2011-06-01

Advanced transparent materials are used in protective systems for enhancing the survivability of ground vehicles, air vehicles, and personnel in applications such as face shields, riot gear, and vehicle windows. Low velocity impact damage can limit visibility and compromise the structural integrity of a transparent system, increasing the likelihood of further damage or penetration from a high velocity impact strike. For this reason, it is critical to determine damage tolerance levels of transparent systems to indicate whether or not a component should be replaced. In this study, transparent laminate systems will be tested by comparing baseline conditions to experimentally controlled damage states. Destructive testing including air gun and sphere impact testing will be used to replicate low velocity impacts in the field. Characterization of the damaged state will include basic visual inspection as well as nondestructive techniques including cross-polarization, x-ray, and ultrasound. The combination of destructive testing and characterization of the resulting damage can help to establish a damage acceptance criterion for materials used in protective systems.

Psychological Distress, Anxiety, and Depression of Cancer-Affected BRCA1/2 Mutation Carriers: a Systematic Review.

PubMed

Ringwald, Johanna; Wochnowski, Christina; Bosse, Kristin; Giel, Katrin Elisabeth; Schäffeler, Norbert; Zipfel, Stephan; Teufel, Martin

2016-10-01

Understanding the intermediate- and long-term psychological consequences of genetic testing for cancer patients has led to encouraging research, but a clear consensus of the psychosocial impact and clinical routine for cancer-affected BRCA1 and BRCA2 mutation carriers is still missing. We performed a systematic review of intermediate- and long-term studies investigating the psychological impact like psychological distress, anxiety, and depression in cancer-affected BRCA mutation carriers compared to unaffected mutation carriers. This review included the screening of 1243 studies. Eight intermediate- and long-term studies focusing on distress, anxiety, and depression symptoms among cancer-affected mutation carriers at least six months after the disclosure of genetic testing results were included. Studies reported a great variety of designs, methods, and patient outcomes. We found evidence indicating that cancer-affected mutation carriers experienced a negative effect in relation to psychological well-being in terms of an increase in symptoms of distress, anxiety, and depression in the first months after test disclosure. In the intermediate- and long-term, no significant clinical relevant symptoms occurred. However, none of the included studies used specific measurements, which can clearly identify psychological burdens of cancer-affected mutation carriers. We concluded that current well-implemented distress screening instruments are not sufficient for precisely identifying the psychological burden of genetic testing. Therefore, future studies should implement coping strategies, specific personality structures, the impact of genetic testing, supportive care needs and disease management behaviour to clearly screen for the possible intermediate- and long-term psychological impact of a positive test disclosure.

Finite Element Simulation of Three Full-Scale Crash Tests for Cessna 172 Aircraft

NASA Technical Reports Server (NTRS)

Mason, Brian H.; Warren, Jerry E., Jr.

2017-01-01

The NASA Emergency Locator Transmitter Survivability and Reliability (ELT-SAR) project was initiated in 2013 to assess the crash performance standards for the next generation of emergency locator transmitter (ELT) systems. Three Cessna 172 aircraft were acquired to perform crash testing at NASA Langley Research Center's Landing and Impact Research Facility. Full-scale crash tests were conducted in the summer of 2015 and each test article was subjected to severe, but survivable, impact conditions including a flare-to-stall during emergency landing, and two controlled-flight-into-terrain scenarios. Full-scale finite element analyses were performed using a commercial explicit solver, ABAQUS. The first test simulated impacting a concrete surface represented analytically by a rigid plane. Tests 2 and 3 simulated impacting a dirt surface represented analytically by an Eulerian grid of brick elements using a Mohr-Coulomb material model. The objective of this paper is to summarize the test and analysis results for the three full-scale crash tests. Simulation models of the airframe which correlate well with the tests are needed for future studies of alternate ELT mounting configurations.

Neurocognitive performance and symptom profiles of Spanish-speaking Hispanic athletes on the ImPACT test.

PubMed

Ott, Summer; Schatz, Philip; Solomon, Gary; Ryan, Joseph J

2014-03-01

This study documented baseline neurocognitive performance of 23,815 athletes on the Immediate Post-Concussion Assessment and Cognitive Testing (ImPACT) test. Specifically, 9,733 Hispanic, Spanish-speaking athletes who completed the ImPACT test in English and 2,087 Hispanic, Spanish-speaking athletes who completed the test in Spanish were compared with 11,955 English-speaking athletes who completed the test in English. Athletes were assigned to age groups (13-15, 16-18). Results revealed a significant effect of language group (p < .001; partial η(2) = 0.06) and age (p < .001; partial η(2) = 0.01) on test performance. Younger athletes performed more poorly than older athletes, and Spanish-speaking athletes completing the test in Spanish scored more poorly than Spanish-speaking and English-speaking athletes completing the test in English, on all Composite scores and Total Symptom scores. Spanish-speaking athletes completing the test in English also performed more poorly than English-speaking athletes completing the test in English on three Composite scores. These differences in performance and reported symptoms highlight the need for caution in interpreting ImPACT test data for Hispanic Americans.

Impact-initiated damage thresholds in composites

NASA Technical Reports Server (NTRS)

Sharma, A. V.

1980-01-01

An experimental investigation was conducted to study the effect of low velocity projectile impact on the sandwich-type structural components. The materials used in the fabrication of the impact surface were graphite-, Kevlar-, and boron-fibers with appropriate epoxy matrices. The testing of the specimens was performed at moderately low- and high-temperatures as well as at room temperature to assess the impact-initiated strength degradation of the laminates. Eleven laminates with different stacking sequences, orientations, and thicknesses were tested. The low energy projectile impact is considered to simulate the damage caused by runway debris, dropping of the hand tools during servicing, etc., on the secondary aircraft structures fabricated with the composite materials. The results show the preload and the impact energy combinations necessary to cause catastrophic failures in the laminates tested. A set of faired curves indicating the failure thresholds is shown separately for the tension- and compression-loaded laminates. The specific-strengths and -moduli for the various laminates tested are also given.

Impact Test and Simulation of Energy Absorbing Concepts for Earth Entry Vehicles

NASA Technical Reports Server (NTRS)

Billings, Marcus D.; Fasanella, Edwin L.; Kellas, Sotiris

2001-01-01

Nonlinear dynamic finite element simulations have been performed to aid in the design of an energy absorbing concept for a highly reliable passive Earth Entry Vehicle (EEV) that will directly impact the Earth without a parachute. EEV's are designed to return materials from asteroids, comets, or planets for laboratory analysis on Earth. The EEV concept uses an energy absorbing cellular structure designed to contain and limit the acceleration of space exploration samples during Earth impact. The spherical shaped cellular structure is composed of solid hexagonal and pentagonal foam-filled cells with hybrid graphite- epoxy/Kevlar cell walls. Space samples fit inside a smaller sphere at the center of the EEV's cellular structure. Comparisons of analytical predictions using MSC,Dytran with test results obtained from impact tests performed at NASA Langley Research Center were made for three impact velocities ranging from 32 to 40 m/s. Acceleration and deformation results compared well with the test results. These finite element models will be useful for parametric studies of off-nominal impact conditions.

Fall-to-Fall Testing versus Spring-to-Spring Testing: What Is the Impact on a Local Community's Chapter 1 Evaluation?

ERIC Educational Resources Information Center

Bushner, Diane E.

The impact of a decision by a local program under Chapter 1, the federally funded program of financial assistance to special educational needs of children, to test students fall-to-fall or spring-to-spring was studied. Students enrolled in a Chapter 1 reading program in 1988-89 were tested on a fall-to-spring basis, a spring-to-spring basis, and a…

Repeatability and uncertainty analyses of NASA/MSFC light gas gun test data

NASA Technical Reports Server (NTRS)

Schonberg, William P.; Cooper, David

1993-01-01

This Final Report presents an overview of the impact tests performed at NASA/MSFC in the time period 1985 to 1991 and the results of phenomena repeatability and data uncertainty studies performed using the information obtained from those tests. An analysis of the data from over 400 tests conducted between 1989 and 1991 was performed to generate a database to supplement the Hypervelocity Impact Damage Database developed under a previous effort.

Fabrication and Testing of Durable Redundant and Fluted-Core Joints for Composite Sandwich Structures

NASA Technical Reports Server (NTRS)

Lin, Shih-Yung; Splinter, Scott C.; Tarkenton, Chris; Paddock, David A.; Smeltzer, Stanley S.; Ghose, Sayata; Guzman, Juan C.; Stukus, Donald J.; McCarville, Douglas A.

2013-01-01

The development of durable bonded joint technology for assembling composite structures is an essential component of future space technologies. While NASA is working toward providing an entirely new capability for human space exploration beyond low Earth orbit, the objective of this project is to design, fabricate, analyze, and test a NASA patented durable redundant joint (DRJ) and a NASA/Boeing co-designed fluted-core joint (FCJ). The potential applications include a wide range of sandwich structures for NASA's future launch vehicles. Three types of joints were studied -- splice joint (SJ, as baseline), DRJ, and FCJ. Tests included tension, after-impact tension, and compression. Teflon strips were used at the joint area to increase failure strength by shifting stress concentration to a less sensitive area. Test results were compared to those of pristine coupons fabricated utilizing the same methods. Tensile test results indicated that the DRJ design was stiffer, stronger, and more impact resistant than other designs. The drawbacks of the DRJ design were extra mass and complex fabrication processes. The FCJ was lighter than the DRJ but less impact resistant. With barely visible but detectable impact damages, all three joints showed no sign of tensile strength reduction. No compression test was conducted on any impact-damaged sample due to limited scope and resource. Failure modes and damage propagation were also studied to support progressive damage modeling of the SJ and the DRJ.

Budget impact analysis of chronic kidney disease mass screening test in Japan.

PubMed

Kondo, Masahide; Yamagata, Kunihiro; Hoshi, Shu-Ling; Saito, Chie; Asahi, Koichi; Moriyama, Toshiki; Tsuruya, Kazuhiko; Konta, Tsuneo; Fujimoto, Shouichi; Narita, Ichiei; Kimura, Kenjiro; Iseki, Kunitoshi; Watanabe, Tsuyoshi

2014-12-01

Our recently published cost-effectiveness study on chronic kidney disease mass screening test in Japan evaluated the use of dipstick test, serum creatinine (Cr) assay or both in specific health checkup (SHC). Mandating the use of serum Cr assay additionally, or the continuation of current policy mandating dipstick test only was found cost-effective. This study aims to examine the affordability of previously suggested reforms. Budget impact analysis was conducted assuming the economic model would be good for 15 years and applying a population projection. Costs expended by social insurers without discounting were counted as budgets. Annual budget impacts of mass screening compared with do-nothing scenario were calculated as ¥79-¥-1,067 million for dipstick test only, ¥2,505-¥9,235 million for serum Cr assay only and ¥2,517-¥9,251 million for the use of both during a 15-year period. Annual budget impacts associated with the reforms were calculated as ¥975-¥4,129 million for mandating serum Cr assay in addition to the currently used mandatory dipstick test, and ¥963-¥4,113 million for mandating serum Cr assay only and abandoning dipstick test. Estimated values associated with the reform from ¥963-¥4,129 million per year over 15 years are considerable amounts of money under limited resources. The most impressive finding of this study is the decreasing additional expenditures in dipstick test only scenario. This suggests that current policy which mandates dipstick test only would contain medical care expenditure.

Influence of impact speed on head and brain injury outcome in vulnerable road user impacts to the car hood.

PubMed

Fredriksson, Rikard; Zhang, Liying; Boström, Ola; Yang, King

2007-10-01

EuroNCAP and regulations in Europe and Japan evaluate the pedestrian protection performance of cars. The test methods are similar and they all have requirements for the passive protection of the hood area at a pedestrian to car impact speed of 40 km/h. In Europe, a proposal for a second phase of the regulation mandates a brake-assist system along with passive requirements. The system assists the driver in optimizing the braking performance during panic braking, resulting in activation only when the driver brakes sufficiently. In a European study this was estimated to occur in about 50% of pedestrian accidents. A future system for brake assistance will likely include automatic braking, in response to a pre-crash sensor, to avoid or mitigate injuries of vulnerable road users. An important question is whether these systems will provide sufficient protection, or if a parallel, passive pedestrian protection system will be necessary. This study investigated the influence of impact speed on head and brain injury risk, in impacts to the carhood. One car model was chosen and a rigid adjustable plate was mounted under the hood. Free-flying headform impacts were carried out at 20 and 30 km/h head impact velocities at different under-hood distances, 20 to 100 mm; and were compared to earlier tests at 40 km/h. The EEVC WG17 adult pedestrian headform was used for non-rotating tests and a Hybrid III adult 50th percentile head was used for rotational tests where linear and rotational acceleration was measured. Data from the rotational tests was used as input to a validated finite element model of the human head, the Wayne State University Head Injury Model (WSUHIM). The model was utilized to assess brain injury risk and potential injury mechanism in a pedestrian-hood impact. Although this study showed that it was not necessarily true that a lower HIC value reduced the risk for brain injury, it appeared, for the tested car model, under-hood distances of 60 mm in 20 km/h and 80 mm in 30 km/h reduced head injury values for both skull fractures and brain injuries. An earlier study showed that the corresponding value for a test speed of 40 km/h is 100 mm. A 10 km/h reduction in head impact velocity, as in automatic braking, allowed 20 mm less under-hood clearance with maintained head protection of the vulnerable road user.

Impact of a Community-Based Programme for Motor Development on Gross Motor Skills and Cognitive Function in Preschool Children from Disadvantaged Settings

ERIC Educational Resources Information Center

Draper, Catherine E.; Achmat, Masturah; Forbes, Jared; Lambert, Estelle V.

2012-01-01

The aims of the studies were to assess the impact of the Little Champs programme for motor development on (1) the gross motor skills, and (2) cognitive function of children in the programme. In study 1, 118 children from one Early Childhood Development Centre (ECDC) were tested using the Test of Gross Motor Development-2, and in study 2, 83…

Temperature Effect of Low Velocity Impact Resistance of Glass/epoxy Laminates

NASA Astrophysics Data System (ADS)

Kang, Ki-Weon; Kim, Heung-Seob; Chung, Tae-Jin; Koh, Seung-Kee

This paper aims to evaluate the effect of temperature on impact damage resistance of glass/epoxy laminates. A series of impact tests were performed using an instrumented impact-testing machine at temperature ranging from -40°C to +80°C. The resulting impact damage was measured using back light method. The impact resistance parameters were employed to understand the damage resistance. It was observed that temperature has a little effect on the impact responses of composite laminates. The damage resistance of glass/epoxy laminates is somewhat deteriorated at two opposite extremes of the studied temperature range and this behavior is likely due to the property change of glass/epoxy laminates under extreme temperatures

Don't take another bite: how sociocultural norms for appearance affect women's eating behavior.

PubMed

Strahan, Erin J; Spencer, Steven J; Zanna, Mark P

2007-12-01

Four studies tested the impact of exposure to thin images on women's eating behavior. In Study 1, women who were exposed to commercials containing thin models ate less in a taste test than women exposed to neutral commercials. The next two studies revealed that the impact of the thin images could be reduced by challenging the sociocultural norms for appearance. In Study 2, including images of relatively heavier women who have been successful in life (an indirect challenge to the norm) attenuated the impact of the thin images on women's eating behavior. Study 3 demonstrated that convincing women that their peers do not endorse the sociocultural norms also reduced the impact of the thin images. In Study 4, we found that exposure to thin images led to activation of an association between heaviness and rejection and that the more this association was activated, the less participants ate.

Theoretical and experimental investigation on the sudden unbalance and rub-impact in rotor system caused by blade off

NASA Astrophysics Data System (ADS)

Wang, Cun; Zhang, Dayi; Ma, Yanhong; Liang, Zhichao; Hong, Jie

2016-08-01

Blade loss from a running turbofan rotor will introduce sudden unbalance into the dynamical system, and as a consequence leads to the rub-impact, the asymmetry of rotor and a series of interesting dynamic characteristics. The paper focuses on the theoretical study on the sudden unbalance and rub-impact caused by blade loss, in particular investigates the response of the rotor on a rotor test rig with sudden unbalance and rub-impact device designed respectively. The results reveal that the sudden unbalance will induce impact effect on the rotor, and critical speed frequency is excited in frequency spectrum. Meantime, the impact effect is more obvious for the rotor operating above critical speed. The influence of rub-impact is considered as additional constraint to the rotor, analyzed by the theory of time-varying system for the first time, and the results are evaluated by experimental tests. The study shows that great attention should be paid to the dynamical design for the overhung rotor system, additional constraint and corresponding analysis method in rub-impact need to be intensively studied.

NASA Double Asteroid Redirection Test (DART) Trajectory Validation and Robutness

NASA Technical Reports Server (NTRS)

Sarli, Bruno V.; Ozimek, Martin T.; Atchison, Justin A.; Englander, Jacob A.; Barbee, Brent W.

2017-01-01

The Double Asteroid Redirection Test (DART) mission will be the first to test the concept of a kinetic impactor. Several studies have been made on asteroid redirection and impact mitigation, however, to this date no mission tested the proposed concepts. An impact study on a representative body allows the measurement of the effects on the target's orbit and physical structure. With this goal, DART's objective is to verify the effectiveness of the kinetic impact concept for planetary defense. The spacecraft uses solar electric propulsion to escape Earth, fly by (138971) 2001 CB21 for impact rehearsal, and impact Didymos-B, the secondary body of the binary (65803) Didymos system. This work focuses on the heliocentric transfer design part of the mission with the validation of the baseline trajectory, performance comparison to other mission objectives, and assessment of the baseline robustness to missed thrust events. Results show a good performance of the selected trajectory for different mission objectives: latest possible escape date, maximum kinetic energy on impact, shortest possible time of flight, and use of an Earth swing-by. The baseline trajectory was shown to be robust to a missed thrust with 1% of fuel margin being enough to recover the mission for failures of more than 14 days.

Dynamic impact testing of hedgehog spines using a dual-arm crash pendulum.

PubMed

Swift, Nathan B; Hsiung, Bor-Kai; Kennedy, Emily B; Tan, Kwek-Tze

2016-08-01

Hedgehog spines are a potential model for impact resistant structures and material. While previous studies have examined static mechanical properties of individual spines, actual collision tests on spines analogous to those observed in the wild have not previously been investigated. In this study, samples of roughly 130 keratin spines were mounted vertically in thin substrates to mimic the natural spine layout on hedgehogs. A weighted crash pendulum was employed to induce and measure the effects of repeated collisions against samples, with the aim to evaluate the influence of various parameters including humidity effect, impact energy, and substrate hardness. Results reveal that softer samples-due to humidity conditioning and/or substrate material used-exhibit greater durability over multiple impacts, while the more rigid samples exhibit greater energy absorption performance at the expense of durability. This trend is exaggerated during high-energy collisions. Comparison of the results to baseline tests with industry standard impact absorbing foam, wherein the spines exhibit similar energy absorption, verifies the dynamic impact absorption capabilities of hedgehog spines and their candidacy as a structural model for engineered impact technology. Copyright © 2016 Elsevier Ltd. All rights reserved.

Objective biofidelity rating of a numerical human occupant model in frontal to lateral impact.

PubMed

de Lange, Ronald; van Rooij, Lex; Mooi, Herman; Wismans, Jac

2005-11-01

Both hardware crash dummies and mathematical human models have been developed largely using the same biomechanical data. For both, biofidelity is a main requirement. Since numerical modeling is not bound to hardware crash dummy design constraints, it allows more detailed modeling of the human and offering biofidelity for multiple directions. In this study the multi-directional biofidelity of the MADYMO human occupant model is assessed, to potentially protect occupants under various impact conditions. To evaluate the model's biofidelity, generally accepted requirements were used for frontal and lateral impact: tests proposed by EEVC and NHTSA and tests specified by ISO TR9790, respectively. A subset of the specified experiments was simulated with the human model. For lateral impact, the results were objectively rated according to the ISO protocol. Since no rating protocol was available for frontal impact, the ISO rating scheme for lateral was used for frontal, as far as possible. As a result, two scores show the overall model biofidelity for frontal and lateral impact, while individual ratings provide insight in the quality on body segment level. The results were compared with the results published for the THOR and WorldSID dummies, showing that the mathematical model exhibits a high level of multi-directional biofidelity. In addition, the performance of the human model in the NBDL 11G oblique test indicates a valid behavior of the model in intermediate directions as well. A new aspect of this study is the objective assessment of the multi-directional biofidelity of the mathematical human model according to accepted requirements. Although hardware dummies may always be used in regulations, it is expected that virtual testing with human models will serve in extrapolating outside the hardware test environment. This study was a first step towards simulating a wider range of impact conditions, such as angled impact and rollover.

Relationship between Particle Size Distribution of Low-Rank Pulverized Coal and Power Plant Performance

DOE PAGES

Ganguli, Rajive; Bandopadhyay, Sukumar

2012-01-01

Tmore » he impact of particle size distribution (PSD) of pulverized, low rank high volatile content Alaska coal on combustion related power plant performance was studied in a series of field scale tests. Performance was gauged through efficiency (ratio of megawatt generated to energy consumed as coal), emissions (SO 2 , NO x , CO), and carbon content of ash (fly ash and bottom ash). he study revealed that the tested coal could be burned at a grind as coarse as 50% passing 76 microns, with no deleterious impact on power generation and emissions. he PSD’s tested in this study were in the range of 41 to 81 percent passing 76 microns. here was negligible correlation between PSD and the followings factors: efficiency, SO 2 , NO x , and CO. Additionally, two tests where stack mercury (Hg) data was collected, did not demonstrate any real difference in Hg emissions with PSD. he results from the field tests positively impacts pulverized coal power plants that burn low rank high volatile content coals (such as Powder River Basin coal). hese plants can potentially reduce in-plant load by grinding the coal less (without impacting plant performance on emissions and efficiency) and thereby, increasing their marketability.« less

The Relationship between Dental Follicle Width and Maxillary Impacted Canines' Descriptive and Resorptive Features Using Cone-Beam Computed Tomography.

PubMed

Dağsuyu, İlhan Metin; Okşayan, Rıdvan; Kahraman, Fatih; Aydın, Mehmet; Bayrakdar, İbrahim Şevki; Uğurlu, Mehmet

2017-01-01

To assess the relationship between dental follicle width and maxillary impacted canines' descriptive and resorptive features with three-dimensional (3D) cone-beam computed tomography (CBCT). The study comprised 102 patients with cone-beam computed tomography 3D images and a total of 140 impacted canines. The association between maxillary impacted canine dental follicle width and the variables of gender, impaction side (right and left), localization of impacted canine (buccal, central, and palatal), and resorption of the adjacent laterals was compared. Measurements were analyzed with Student's t -test, Kruskal-Wallis test, and Mann-Whitney U statistical test. According to gender, no statistically significant differences were found in the follicle size of the maxillary impacted canine between males and females ( p > 0.05). Widths of the follicles were determined for the right and left impaction sides, and no statistically significant relation was found ( p > 0.05). There were statistically significant differences between root resorption degrees of lateral incisors and maxillary impacted canine follicle width ( p < 0.05). Statistically significant higher follicle width values were present in degree 2 (mild) resorption than in degree 1 (no) and degree 3 (moderate) resorption samples ( p < 0.05). No significant correlation was found between follicle width and the variables of gender, impaction side, and localization of maxillary impacted canines. Our study could not confirm that increased dental follicle width of the maxillary impacted canines exhibited more resorption risk for the adjacent lateral incisors.

Application of impact dampers in vibration control of flexible structures

NASA Technical Reports Server (NTRS)

Akl, Fred A.; Butt, Aamir S.

1995-01-01

Impact dampers belong to the category of passive vibration devices used to attenuate the vibration of discrete and continuous systems. An impact damper generally consists of a mass which is allowed to travel freely between two defined stops. Under the right conditions, the vibration of the structure to which the impact damper is attached will cause the mass of the impact damper to strike the structure. Previous analytical and experimental research work on the effect of impact dampers in attenuating the vibration of discrete and continuous systems have demonstrated their effectiveness. It has been shown in this study that impact dampers can increase the intrinsic damping of a lightly-damped flexible structure. The test structure consists of a slender flexible beam supported by a pin-type support at one end and supported by a linear helical flexible spring at another location. Sinusoidal excitation spanning the first three natural frequencies was applied in the horizontal plane. The orientation of the excitation and the test structure in the horizontal plane minimizes the effect of gravity on the behavior of the test structure. The excitation was applied using a linear sine sweep technique. The span of the test structure, the mass of the impact damper, the distance of travel, and the location of the impact damper along the span of the test structure were varied. The damping ratio are estimated for sixty test configurations. The results show that the impact damper significantly increases the damping ratio of the test structure. Statistical analysis of the results using the method of multiple linear regression indicates that a reasonable fit has been accomplished. It is concluded that additional experimental analysis of flexible structures in microgravity environment is needed in order to achieve a better understanding of the behavior of impact damper under conditions of microgravity. Numerical solution of the behavior of flexible structures equipped with impact dampers is also needed to predict stresses and deformations under operating conditions of microgravity in space applications.

High Speed Thermal Imaging on Ballistic Impact of Triaxially Braided Composites

NASA Technical Reports Server (NTRS)

Johnston, Joel P.; Pereira, J. Michael; Ruggeri, Charles R.; Roberts, Gary D.

2017-01-01

Ballistic impact experiments were performed on triaxially braided polymer matrix composites to study the heat generated in the material due to projectile velocity and penetration damage. Quantifying the heat generation phenomenon is crucial for attaining a better understanding of composite behavior and failure under impact loading. The knowledge gained can also be used to improve physics-based models which can numerically simulate impact of composites. Triaxially braided (0/+60/-60) composite panels were manufactured with T700S standard modulus carbon fiber and two epoxy resins. The PR520 (toughened) and 3502 (untoughened) resin systems were used to make different panels to study the effects of resin properties on temperature rise. Ballistic impact tests were conducted on these composite panels using a gas gun, and different projectile velocities were applied to study the effect on the temperature results. Temperature contours were obtained from the rear surface of the panel during the test through a high speed, infrared (IR) thermal imaging system. The contours show that high temperatures were locally generated and more pronounced along the axial tows for the T700S/PR520 composite specimens; whereas, tests performed on T700S/3502 composite panels using similar impact velocities demonstrated a widespread area of lower temperature rises. Nondestructive, ultrasonic C-scan analyses were performed to observe and verify the failure patterns in the impacted panels. Overall, the impact experimentation showed temperatures exceeding 525 K (485degF) in both composites which is well above the respective glass transition temperatures for the polymer constituents. This expresses the need for further high strain rate testing and measurement of the temperature and deformation fields to fully understand the complex behavior and failure of the material in order to improve the confidence in designing aerospace components with these materials.

The Impact of Test Dimensionality, Common-Item Set Format, and Scale Linking Methods on Mixed-Format Test Equating

ERIC Educational Resources Information Center

Öztürk-Gübes, Nese; Kelecioglu, Hülya

2016-01-01

The purpose of this study was to examine the impact of dimensionality, common-item set format, and different scale linking methods on preserving equity property with mixed-format test equating. Item response theory (IRT) true-score equating (TSE) and IRT observed-score equating (OSE) methods were used under common-item nonequivalent groups design.…

An Empirical Investigation of the Potential Impact of Item Misfit on Test Scores. Research Report. ETS RR-17-60

ERIC Educational Resources Information Center

Kim, Sooyeon; Robin, Frederic

2017-01-01

In this study, we examined the potential impact of item misfit on the reported scores of an admission test from the subpopulation invariance perspective. The target population of the test consisted of 3 major subgroups with different geographic regions. We used the logistic regression function to estimate item parameters of the operational items…

Supplemental final environmental impact statement for advanced solid rocket motor testing at Stennis Space Center

NASA Technical Reports Server (NTRS)

1990-01-01

Since the Final Environmental Impact Statement (FEIS) and Record of Decision on the FEIS describing the potential impacts to human health and the environment associated with the program, three factors have caused NASA to initiate additional studies regarding these issues. These factors are: (1) The U.S. Army Corps of Engineers and the Environmental Protection Agency (EPA) agreed to use the same comprehensive procedures to identify and delineate wetlands; (2) EPA has given NASA further guidance on how best to simulate the exhaust plume from the Advanced Solid Rocket Motor (ASRM) testing through computer modeling, enabling more realistic analysis of emission impacts; and (3) public concerns have been raised concerning short and long term impacts on human health and the environment from ASRM testing.

Explicit Finite Element Modeling of Multilayer Composite Fabric for Gas Turbine Engine Containment Systems. Part 2; Ballistic Impact Testing

NASA Technical Reports Server (NTRS)

Pereira, J. M.; Revilock, D. M.

2004-01-01

Under the Federal Aviation Administration's Airworthiness Assurance Center of Excellence and the Aircraft Catastrophic Failure Prevention Program, National Aeronautics and Space Administration Glenn Research Center collaborated with Arizona State University, Honeywell Engines, Systems and Services, and SRI International to develop improved computational models for designing fabric-based engine containment systems. In the study described in this report, ballistic impact tests were conducted on layered dry fabric rings to provide impact response data for calibrating and verifying the improved numerical models. This report provides data on projectile velocity, impact and residual energy, and fabric deformation for a number of different test conditions.

NASA Double Asteroid Redirection Test (Dart) Trajectory Validation and Robustness

NASA Technical Reports Server (NTRS)

Sarli, Bruno V.; Ozimek, Martin T.; Atchison, Justin A.; Englander, Jacob A.; Barbee, Brent W.

2017-01-01

The Double Asteroid Redirection Test (DART) mission will be the first to test the concept of a kinetic impactor. Several studies have been made on asteroid redirection and impact mitigation, however, to this date no mission tested the proposed concepts. An impact study on a representative body allows the measurement of the effects on the target's orbit and physical structure. With this goal, DART's objective is to verify the effectiveness of the kinetic impact concept for planetary defense. The spacecraft uses solar electric propulsion to escape Earth, flyby (138971) 2001 CB21 for impart rehearsal, and impact the secondary body of the (65803) Didymos system. This work focuses on the interplanetary trajectory design part of the mission with the validation of the baseline trajectory, performance comparison to other mission objectives, and assessment of the baseline robustness to missed thrust events. Results show a good performance of the selected trajectory for different mission objectives: latest possible escape date, maximum kinetic energy on impact, shortest possible time of flight, and use of an Earth swing-by. The baseline trajectory was shown to be robust to a missed thrust with 1% of fuel margin being enough to recover the mission for failures of more than 14 days.

Assessing Willingness to Test for HIV among Men who have Sex with Men Using Conjoint Analysis, Evidence for Uptake of the FDA-approved at-Home HIV Test

PubMed Central

Lee, Sung-Jae; Brooks, Ronald; Bolan, Robert K.; Flynn, Risa

2013-01-01

Men who have sex with men (MSM) in the United States represent a vulnerable population with lower rates of HIV testing. There are various specific attributes of HIV testing that may impact willingness to test (WTT) for HIV. Identifying specific attributes influencing patients’ decisions around WTT for HIV is critical to ensure improved HIV testing uptake. This study examined WTT for HIV by using conjoint analysis, an innovative method for systematically estimating consumer preferences across discrete attributes. WTT for HIV was assessed across eight hypothetical HIV testing scenarios varying across seven dichotomous attributes: location (home vs. clinic), price (free vs. $50), sample collection (finger prick vs. blood), timeliness of results (immediate vs. 1–2 weeks), privacy (anonymous vs. confidential), results given (by phone vs. in-person), and type of counseling (brochure vs. in-person). Seventy-five MSM were recruited from a community based organization providing HIV testing services in Los Angeles to participate in conjoint analysis. WTT for HIV score was based on a 100-point scale. Scores ranged from 32.2 to 80.3 for eight hypothetical HIV testing scenarios. Price of HIV testing (free vs. $50) had the highest impact on WTT (impact score=31.4, SD=29.2, p<.0001), followed by timeliness of results (immediate vs. 1–2 weeks) (impact score=13.9, SD=19.9, p=<.0001) and testing location (home vs. clinic) (impact score=10.3, SD=22.8, p=.0002). Impacts of other HIV testing attributes were not significant. Conjoint analysis method enabled direct assessment of HIV testing preferences and identified specific attributes that significantly impact WTT for HIV among MSM. This method provided empirical evidence to support the potential uptake of the newly FDA-approved over-the-counter HIV home-test kit with immediate results, with cautionary note on the cost of the kit. PMID:23651439

Economic impact of 21-gene recurrence score testing on early-stage breast cancer in Ireland.

PubMed

Smyth, Lillian; Watson, Geoff; Walsh, Elaine M; Kelly, Catherine M; Keane, Maccon; Kennedy, M John; Grogan, Liam; Hennessy, Bryan T; O'Reilly, Seamus; Coate, Linda E; O'Connor, Miriam; Quinn, Cecily; Verleger, Katharina; Schoeman, Olaf; O'Reilly, Susan; Walshe, Janice M

2015-10-01

The 21-gene test is a validated multi-gene diagnostic test that predicts chemotherapy (CT) benefit in oestrogen receptor positive (ER+), lymph node-negative (N0) breast cancer (BC) patients (pts). Ireland was the first public health care system to reimburse this test in Europe. Study objectives were to assess the impact of this test on decision-making and to analyse the economic impact of testing. Between October 2011 and February 2013, a national, retrospective, cross-sectional observational study of ER+, N0 BC pts tested with the 21-gene test was conducted. Surveyed breast medical oncologists, provided the assumption for the decision impact analysis that grade (G) 1 pts would not have received CT before testing and G2/3 pts would have received CT before testing. Descriptive statistical analyses were performed. 592 pts were identified; Low, intermediate and high recurrence score were identified in 53, 36 and 10 % pts, respectively. 384 (70 %) pts had G2, 129 (22 %) G3 and 76 (13 %) G1 tumours. Post testing, 345 pts (59 %) experienced a change in CT decision; 339 changed to hormone therapy alone and 6 advised to receive CT. 172 (30 %) pts received CT, 12 (3.9 %) of pts with low scores, 108 (50.9 %) of intermediate risk and 50 (90.9 %) of pts with high risk scores. Net reduction in CT use was 58 % and net savings achieved were €793,565. Since public reimbursement, the introduction of the 21-gene test has resulted in a significant reduction in chemotherapy administration and cost savings for the Irish public healthcare system.

Targeting a Novel Androgen Receptor-Repressed Pathway in Prostate Cancer Therapy

DTIC Science & Technology

2017-09-01

AURKA and CENPE. [ Study is on - going] Major Task 3: Test the hypothesis that androgen deprivation-induced PKD1 expression. Major Task 4: Test the...Subtask 3: Conduct detail analysis of the pathway identified in Subtask 2 and assessing its impact on PKD1 expression. This study is on -going. We...enzalutamide, in androgen-sensitivity PrCa cells. We have completed this subtask. In this study , although PKD2 overexpression had little impact on LNCaP

Effect of Point-of-Care Diagnostics on Maternal Outcomes in Human Immunodeficiency Virus–Infected Women: Systematic Review and Meta-analysis

PubMed Central

Mashamba-Thompson, Tivani P; Morgan, Rebecca L; Sartorius, Benn; Dennis, Brittany; Drain, Paul K; Thabane, Lehana

2017-01-01

Introduction The World Health Organization advocates for increased accessibility of HIV-related point-of-care (POC) diagnostics in settings that lack laboratory infrastructure. The aim of this study is to assess the impact of POC diagnostics on maternal health outcomes in HIV-infected women. Methods A systematic literature review used multiple data sources as follows: Cochrane Infectious Disease Group Specialized Register; Cochrane Central Register of Control Trials, published in The Cochrane Library; PubMed; EBSCOhost and LILACS from January 2000 to October 2015. References of included studies were hand searched. Randomized controlled trials (RCTs) and observational studies examining health outcomes of HIV-infected women were eligible for inclusion in this review. The Cochrane Risk of Bias tool was used for bias assessment of the included studies. PRISMA guidelines were used for reporting. Results Of the 695 studies identified, six retrievable studies (five cross-sectional studies and one case control study) met the inclusion criteria and were included in this study. These studies examined a total of 167 HIV-infected women in different study settings. No studies reported evidence of CD4 count, viral load and TB, and the syphilis POC test impact on HIV-infected women was not found by this study. Included studies reported the impact of various HIV rapid tests across the following five maternal outcomes: timely receipt of results with pooled effect size (ES) = 1.00 (95% confidence interval [CI]: (0.98; 1.02); enabling partner testing, ES = 0.95 (0.85; 1.04); prevention of mother-to-child transmission of HIV, ES = 0.86 (0.79; 0.93); linkage to antiretroviral treatment (ART), ES = 0.76 (0.69; 0.84); and linkage to HIV care, ES = 0.50 (0.18; 0.82). No studies reported evidence of the impact of POC testing on maternal mortality or maternal and child morbidity of HIV-infected women. Conclusions The review provides an international overview of the impact of HIV POC diagnostics on maternal outcomes in HIV-infected women, showing the evidence that the HIV POC test is significantly associated with decreased mother-to-child transmission of HIV and increased linkage to ART and HIV care for HIV-infected women. It also revealed a gap in the literature aimed at assessing the impact of POC diagnostics on maternal morbidity and mortality in HIV-infected women. PMID:29242711

Risk assessment test for lead bioaccessibility to waterfowl in mine-impacted soils

USGS Publications Warehouse

Furman, O.; Strawn, D.G.; Heinz, G.H.; Williams, B.

2006-01-01

Due to variations in soil physicochemical properties, species physiology, and contaminant speciation, Pb toxicity is difficult to evaluate without conducting in vivo dose-response studies. Such tests, however, are expensive and time consuming, making them impractical to use in assessment and management of contaminated environments. One possible alternative is to develop a physiologically based extraction test (PBET) that can be used to measure relative bioaccessibility. We developed and correlated a PBET designed to measure the bioaccessibility of Pb to waterfowl (W-PBET) in mine-impacted soils located in the Coeur d'Alene River Basin, Idaho. The W-PBET was also used to evaluate the impact of P amendments on Pb bioavailability. The W-PBET results were correlated to waterfowl-tissue Pb levels from a mallard duck [Anas platyrhynchos (L.)] feeding study. The W-PBET Pb concentrations were significantly less in the P-amended soils than in the unamended soils. Results from this study show that the W-PBET can be used to assess relative changes in Pb bioaccessibility to waterfowl in these mine-impacted soils, and therefore will be a valuable test to help manage and remediate contaminated soils.

Mechanisms and factors involved in hip injuries during frontal crashes.

PubMed

Yoganandan, N; Pintar, F A; Gennarelli, T A; Maltese, M R; Eppinger, R H

2001-11-01

This study was conducted to collect data and gain insights relative to the mechanisms and factors involved in hip injuries during frontal crashes and to study the tolerance of hip injuries from this type of loading. Unembalmed human cadavers were seated on a standard automotive seat (reinforced) and subjected to knee impact test to each lower extremity. Varying combinations of flexion and adduction/abduction were used for initial alignment conditions and pre-positioning. Accelerometers were fixed to the iliac wings and twelfth thoracic vertebral spinous process. A 23.4-kg padded pendulum impacted the knee at velocities ranging from 4.3 to 7.6 m/s. The impacting direction was along the anteroposterior axis, i.e., the global X-axis, in the body-fixed coordinate system. A load cell on the front of the pendulum recorded the impact force. Peak impact forces ranged from 2,450 to 10,950 N. The rate of loading ranged from 123 to 7,664 N/msec. The impulse values ranged from 12.4 to 31.9 Nsec. Injuries were not apparent in three tests. Eight tests resulted in trauma. Fractures involving the pelvis including the acetabulum and proximal femur occurred in five out of the eight tests, and distal femoral bone fracture occurred in one test. These results underscore the importance of leg pre-positioning and the orientation of the impacting axis to produce specific types of trauma to the pelvic region of the lower extremity.

NASA Marshall Impact Testing Facility Capabilities Applicable to Lunar Dust Work

NASA Technical Reports Server (NTRS)

Evans, Steven W.; Finchum, Andy; Hubbs, Whitney; Eskridge, Richard; Martin, Jim

2008-01-01

The Impact Testing Facility at Marshall Space Flight Center has several guns that would be of use in studying impact phenomena with respect to lunar dust. These include both ballistic guns, using compressed gas and powder charges, and hypervelocity guns, either light gas guns or an exploding wire gun. In addition, a plasma drag accelerator expected to reach 20 km/s for small particles is under development. Velocity determination and impact event recording are done using ultra-high-speed cameras. Simulation analysis is also available using the SPHC hydrocode.

Out-of-plane properties

NASA Technical Reports Server (NTRS)

Jackson, Wade C.; Portanova, Marc A.

1995-01-01

This paper summarizes three areas of research which were performed to characterize out-of-plane properties of composite materials. In the first investigation, a series of tests was run to characterize the through-the-thickness tensile strength for a variety of composites that included 2D braids, 2D and 3D weaves, and prepreg tapes. A new test method based on a curved beam was evaluated. Failures were significantly different between the 2D materials and the 3D weaves. The 2D materials delaminated between layers due to out-of-plane tensile stresses while the 3D weaves failed due to the formation of radial cracks between the surface plies caused by high circumferential stresses along the inner radius. The strength of the 2D textile composites did not increase relative to the tapes. Final failure in the 3D weaves was caused by a circumferential crack similar to the 2D materials and occurred at a lower bending moment than in other materials. The early failures in the 3D weaves were caused by radial crack formation rather than a low through-the-thickness strength. The second investigation focused on the development of a standard impact test method to measure impact damage resistance. The only impact tests that currently exist are compression after impact (CAI) tests which incorporate elements of both damage resistance and damage tolerance. A new impact test method is under development which uses a quasi-static indentation (QSI) test to directly measure damage resistance. Damage resistance is quantified in terms of the contact force to produce a unit of damage where a metric for damage may be area in C-scan, depth of residual dent , penetration, damage growth, etc. A final draft of an impact standard that uses a QSI test method will be presented to the ASTM Impact Task Group on impact. In the third investigation, the impact damage resistance behavior of a variety of textile materials was studied using the QSI test method. In this study, the force where large damage initiates was measured and the delamination size as a function of force was determined. The force to initiate large damage was significantly lower in braids and weaves. The delamination diameter - impact forace relationship was quanitfied using a damage resistance parameter, Q(*), which related delamination diameter to imapct force over a range of delamination sizes. Using this Q(*) parameter to rate the materials, the stitched uniweaves, toughened epoxy tapes, and through-the-thickness orthogonal interlock weave were the most damage resistant.

Development of a tornado safe room door from wood Products: door design and impact testing

Treesearch

Robert H. Falk; James J. Bridwell

2016-01-01

In this study, a tornado safe room door built from wood products and steel sheeting was developed and impact-tested according to tornado safe room standards. Results indicate that an door constructed from as few as two sheets of 23/32-in. (18.26-mm) construction-grade plywood and overlaid with 18-gauge (0.05-in.- (1.27- mm-) thick) steel can pass the required impact...

Impact and fracture analysis of fish scales from Arapaima gigas.

PubMed

Torres, F G; Malásquez, M; Troncoso, O P

2015-06-01

Fish scales from the Amazonian fish Arapaima gigas have been characterised to study their impact and fracture behaviour at three different environmental conditions. Scales were cut in two different directions to analyse the influence of the orientation of collagen layers. The energy absorbed during impact tests was measured for each sample and SEM images were taken after each test in order to analyse the failure mechanisms. The results showed that scales tested at cryogenic temperatures display fragile behaviour, while scales tested at room temperature did not fracture. Different failure mechanisms have been identified, analysed and compared with the failure modes that occur in bone. The impact energy obtained for fish scales was two to three times higher than the values reported for bone in the literature. Copyright © 2015 Elsevier B.V. All rights reserved.

Laboratory testing in primary care: A systematic review of health IT impacts.

PubMed

Maillet, Éric; Paré, Guy; Currie, Leanne M; Raymond, Louis; Ortiz de Guinea, Ana; Trudel, Marie-Claude; Marsan, Josianne

2018-08-01

Laboratory testing in primary care is a fundamental process that supports patient management and care. Any breakdown in the process may alter clinical information gathering and decision-making activities and can lead to medical errors and potential adverse outcomes for patients. Various information technologies are being used in primary care with the goal to support the process, maximize patient benefits and reduce medical errors. However, the overall impact of health information technologies on laboratory testing processes has not been evaluated. To synthesize the positive and negative impacts resulting from the use of health information technology in each phase of the laboratory 'total testing process' in primary care. We conducted a systematic review. Databases including Medline, PubMed, CINAHL, Web of Science and Google Scholar were searched. Studies eligible for inclusion reported empirical data on: 1) the use of a specific IT system, 2) the impacts of the systems to support the laboratory testing process, and were conducted in 3) primary care settings (including ambulatory care and primary care offices). Our final sample consisted of 22 empirical studies which were mapped to a framework that outlines the phases of the laboratory total testing process, focusing on phases where medical errors may occur. Health information technology systems support several phases of the laboratory testing process, from ordering the test to following-up with patients. This is a growing field of research with most studies focusing on the use of information technology during the final phases of the laboratory total testing process. The findings were largely positive. Positive impacts included easier access to test results by primary care providers, reduced turnaround times, and increased prescribed tests based on best practice guidelines. Negative impacts were reported in several studies: paper-based processes employed in parallel to the electronic process increased the potential for medical errors due to clinicians' cognitive overload; systems deemed not reliable or user-friendly hampered clinicians' performance; and organizational issues arose when results tracking relied on the prescribers' memory. The potential of health information technology lies not only in the exchange of health information, but also in knowledge sharing among clinicians. This review has underscored the important role played by cognitive factors, which are critical in the clinician's decision-making, the selection of the most appropriate tests, correct interpretation of the results and efficient interventions. By providing the right information, at the right time to the right clinician, many IT solutions adequately support the laboratory testing process and help primary care clinicians make better decisions. However, several technological and organizational barriers require more attention to fully support the highly fragmented and error-prone process of laboratory testing. Copyright © 2018 Elsevier B.V. All rights reserved.

Effectiveness of headgear in football

PubMed Central

Withnall, C; Shewchenko, N; Wonnacott, M; Dvorak, J; Scott, D

2005-01-01

Objectives: Commercial headgear is currently being used by football players of all ages and skill levels to provide protection from heading and direct impact. The clinical and biomechanical effectiveness of the headgear in attenuating these types of impact is not well defined or understood. This study was conducted to determine whether football headgear has an effect on head impact responses. Methods: Controlled laboratory tests were conducted with a human volunteer and surrogate head/neck system. The impact attenuation of three commercial headgears during ball impact speeds of 6–30 m/s and in head to head contact with a closing speed of 2–5 m/s was quantified. The human subject, instrumented to measure linear and angular head accelerations, was exposed to low severity impacts during heading in the unprotected and protected states. High severity heading contact and head to head impacts were studied with a biofidelic surrogate headform instrumented to measure linear and angular head responses. Subject and surrogate responses were compared with published injury assessment functions associated with mild traumatic brain injury (MTBI). Results: For ball impacts, none of the headgear provided attenuation over the full range of impact speeds. Head responses with or without headgear were not significantly different (p>0.05) and remained well below levels associated with MTBI. In head to head impact tests the headgear provided an overall 33% reduction in impact response. Conclusion: The football headgear models tested did not provide benefit during ball impact. This is probably because of the large amount of ball deformation relative to headband thickness. However, the headgear provided measurable benefit during head to head impacts. PMID:16046355

Public health and clinical impact of increasing emergency department-based HIV testing: perspectives from the 2007 conference of the National Emergency Department HIV Testing Consortium.

PubMed

Kecojevic, Aleksandar; Lindsell, Christopher J; Lyons, Michael S; Holtgrave, David; Torres, Gretchen; Heffelfinger, James; Brown, Jeremy; Couture, Eileen; Jung, Julianna; Connell, Samantha; Rothman, Richard E

2011-07-01

Understanding perceived benefits and disadvantages of HIV testing in emergency departments (EDs) is imperative to overcoming barriers to implementation. We codify those domains of public health and clinical care most affected by implementing HIV testing in EDs, as determined by expert opinion. Opinions were systematically collected from attendees of the 2007 National ED HIV Testing Consortium meeting. Structured evaluation of strengths, weaknesses, opportunities, and threats analysis was conducted to assess the impact of ED-based HIV testing on public health. A modified Delphi method was used to assess the impact of ED-based HIV testing on clinical care from both individual patient and individual provider perspectives. Opinions were provided by 98 experts representing 42 academic and nonacademic institutions. Factors most frequently perceived to affect public health were (strengths) high volume of ED visits and high prevalence of HIV, (weaknesses) undue burden on EDs, (opportunities) reduction of HIV stigma, and (threats) lack of resources in EDs. Diagnostic testing and screening for HIV were considered to have a favorable impact on ED clinical care from both individual patient and individual provider perspectives; however, negative test results were not perceived to have any benefit from the provider's perspective. The need for HIV counseling in the ED was considered to have a negative impact on clinical care from the provider's perspective. Experts in ED-based HIV testing perceived expanded ED HIV testing to have beneficial impacts for both the public health and individual clinical care; however, limited resources were frequently cited as a possible impediment. Many issues must be resolved through further study, education, and policy changes if the full potential of HIV testing in EDs is to be realized. Copyright © 2011. Published by Mosby, Inc.

Investigation of the Microstructural, Mechanical and Corrosion Properties of Grade A Ship Steel-Duplex Stainless Steel Composites Produced via Explosive Welding

NASA Astrophysics Data System (ADS)

Kaya, Yakup; Kahraman, Nizamettin; Durgutlu, Ahmet; Gülenç, Behçet

2017-08-01

Grade A ship-building steel-AISI 2304 duplex stainless steel composite plates were manufactured via explosive welding. The AISI 2304 plates were used to clad the Grade A plates. Optical microscopy studies were conducted on the joining interface for characterization of the manufactured composite plates. Notch impact, tensile-shear, microhardness, bending and twisting tests were carried out to determine the mechanical properties of the composites. In addition, the surfaces of fractured samples were examined by scanning electron microscopy (SEM), and neutral salt spray (NSS) and potentiodynamic polarization tests were performed to examine corrosion behavior. Near the explosion zone, the interface was completely flat, but became wavy as the distance from the explosion zone increased. The notch impact tests indicated that the impact strength of the composites decreased with increasing distance from the explosion zone. The SEM studies detected brittle behavior below the impact transition temperature and ductile behavior above this temperature. Microhardness tests revealed that the hardness values increased with increasing distance from the explosion zone and mechanical tests showed that no visible cracking or separation had occurred on the joining interface. The NSS and potentiodynamic polarization tests determined that the AISI 2304 exhibited higher corrosion resistance than the Grade A steel.

Failure mechanism of coated biomaterials under high impact-sliding contact stresses

NASA Astrophysics Data System (ADS)

Chen, Ying

This study uses a newly developed testing method--- inclined cyclic impact-sliding test to investigate the failure behaviors of different types of biomaterials, (SS316L, Ti6Al4V and CoCr) coated by different coatings (TiN, DLC and PEO), under extremely high dynamic contact stress conditions. This test method can simulate the combined impact and sliding/rolling loading conditions, which is very practical in many aspects of commercial usages. During the tests, fatigue cracking, chipping, peeling and material transferring were observed in damaged area. This research is mainly focused on the failure behaviors of load-bearing materials which cyclic impacting and sliding are always involved. This purpose was accomplished in the three stages: First, impact-sliding test was carried out on TiN coated unhardened M2. It was found that soft substrate can cause early failure of coating due to the considerable plastic deformation in the substrate. In this case, stronger substrate is required to support coating better when tested under high contact stresses. Second, PEO coated Ti-6Al-4V was tested under pure sliding and impact-sliding wear conditions. PEO coating was found not strong enough to afford the high contact pressure under cyclic impact-sliding wear test due to its porous surface structure. However, the wear performance of PEO coating was enhanced due to the sub-stoichiometric oxide. To sum up, for load-bearing biomedical implants involved in high impacting movement, PEO coating may not be a promising surface protection. Third, the dense, smooth PVD/CVD bio-inert coatings were reconsidered. DLC and TiN coatings, combined by different substrates together with different interface materials were tested under the cyclic impact-sliding test using a set of proper loading. The results show that to choose a proper combination of coating, interface and substrate based on their mechanical properties is of great importance under the test condition. Hard substrates provide support to coating better and a ductile and adhesive interface layer can delay the cracked coating from peeled-off.

Performance Evaluation of Child Safety Seats in Far-Side Lateral Sled Tests at Varying Speeds

PubMed Central

Ghati, Yoganand; Menon, Rajiv A.; Milone, Mary; Lankarani, Hamid; Oliveres, Gerardo

2009-01-01

Protection of children in Child Safety Seats (CSS) in side impact crashes has been a topic of recent studies. The objective of this study was to evaluate the performance of CSS in far-side impacts through a series of sled tests conducted at varying test speeds. Forty eight sled tests were conducted at three speeds (24 km/h, 29 km/h and 36 km/h), under two different CSS attachment conditions (LATCH and seat belt attached), using rear facing and forward facing CSS from four different manufacturers. Analyses were conducted to examine head retention within the CSS, velocity of the head as it passes an imaginary plane (cross over into other occupant space or door), lateral trajectory of the head and knee; head, chest and pelvis accelerations; neck and lumbar loads and moments. In addition to these parameters, the CSS were visually inspected for structural integrity after each test. Results from these sled tests highlighted the differential performance of CSS in far-side impacts. During the tests, all CSS experienced significant lateral movement irrespective of attachment type. In rear facing CSS tests, one of the designs failed as the seat disengaged from its base. In forward facing CSS tests, it was observed that the seat belt attached CSS experienced less rotational motion than the LATCH attached CSS. ATD head retention within the seat was not achieved with either CSS attachments at any speed. The findings from this study augment the current efforts to define regulatory sled setup procedure for far-side impact crashes involving children in CSS, which currently does not exist and will eventually further the protection of children in automobiles. PMID:20184846

Materials Database Development for Ballistic Impact Modeling

NASA Technical Reports Server (NTRS)

Pereira, J. Michael

2007-01-01

A set of experimental data is being generated under the Fundamental Aeronautics Program Supersonics project to help create and validate accurate computational impact models of jet engine impact events. The data generated will include material property data generated at a range of different strain rates, from 1x10(exp -4)/sec to 5x10(exp 4)/sec, over a range of temperatures. In addition, carefully instrumented ballistic impact tests will be conducted on flat plates and curved structures to provide material and structural response information to help validate the computational models. The material property data and the ballistic impact data will be generated using materials from the same lot, as far as possible. It was found in preliminary testing that the surface finish of test specimens has an effect on measured high strain rate tension response of AL2024. Both the maximum stress and maximum elongation are greater on specimens with a smoother finish. This report gives an overview of the testing that is being conducted and presents results of preliminary testing of the surface finish study.

Tests of the Performance of Coatings for Low Ice Adhesion

NASA Technical Reports Server (NTRS)

Anderson, David N.; Reich, Allen D.

1997-01-01

This paper reports studies of the performance of low-ice-adhesion coatings by NASA Lewis and BFGoodrich. Studies used impact ice accreted both in the NASA Lewis Icing Research Tunnel (IRT) and in the BFGoodrich Icing Wind Tunnel (IWT) and static ice in a BFGoodrich bench-top parallel-plate shear rig. Early tests at NASA Lewis involved simple qualitative evaluations of the ease of removing impact ice from a surface. Coated surfaces were compared with uncoated ones. Some of the coatings were tested again with static ice at BFGoodrich to obtain quantitative measurements. Later, methods to establish the adhesion force on surfaces subjected to impact ice were explored at Lewis. This paper describes the various test programs and the results of testing some of the coatings looked at over the past 5 years. None of the coatings were found to be truly ice-phobic; however, the most effective coatings were found to reduce the adhesion of ice to about 1/2 that of an uncoated aluminum sample.

The Effects of Foam Thermal Protection System on the Damage Tolerance Characteristics of Composite Sandwich Structures for Launch Vehicles

NASA Technical Reports Server (NTRS)

Nettles, A. T.; Hodge, A. J.; Jackson, J. R.

2011-01-01

For any structure composed of laminated composite materials, impact damage is one of the greatest risks and therefore most widely tested responses. Typically, impact damage testing and analysis assumes that a solid object comes into contact with the bare surface of the laminate (the outer ply). However, most launch vehicle structures will have a thermal protection system (TPS) covering the structure for the majority of its life. Thus, the impact response of the material with the TPS covering is the impact scenario of interest. In this study, laminates representative of the composite interstage structure for the Ares I launch vehicle were impact tested with and without the planned TPS covering, which consists of polyurethane foam. Response variables examined include maximum load of impact, damage size as detected by nondestructive evaluation techniques, and damage morphology and compression after impact strength. Results show that there is little difference between TPS covered and bare specimens, except the residual strength data is higher for TPS covered specimens.

Permeability Testing of Impacted Composite Laminates for Use on Reusable Launch Vehicles

NASA Technical Reports Server (NTRS)

Nettles, A. T.

2001-01-01

Since composite laminates are beginning to be identified for use in reusable launch vehicle propulsion systems, an understanding of their permeance is needed. A foreign object impact event can cause a localized area of permeability (leakage) in a polymer matrix composite, and it is the aim of this study to assess a method of quantifying permeability-after-impact results. A simple test apparatus is presented, and variables that could affect the measured values of permeability-after-impact were assessed. Once it was determined that valid numbers were being measured, a fiber/resin system was impacted at various impact levels and the resulting permeability measured, first with a leak check solution (qualitative) then using the new apparatus (quantitative). The results showed that as the impact level increased, so did the measured leakage. As the pressure to the specimen was increased, the leak rate was seen to increase in a nonlinear fashion for almost all the specimens tested.

Evaluating the test-retest reliability of symptom indices associated with the ImPACT post-concussion symptom scale (PCSS).

PubMed

Merritt, Victoria C; Bradson, Megan L; Meyer, Jessica E; Arnett, Peter A

2018-05-01

The Immediate Post-Concussion Assessment and Cognitive Testing (ImPACT) is a commonly used tool in sports concussion assessment. While test-retest reliabilities have been established for the ImPACT cognitive composites, few studies have evaluated the psychometric properties of the ImPACT's Post-Concussion Symptom Scale (PCSS). The purpose of this study was to establish the test-retest reliability of symptom indices associated with the PCSS. Participants included 38 undergraduate students (50.0% male) who underwent neuropsychological testing as part of their participation in their psychology department's research subject pool. The majority of the participants were Caucasian (94.7%) and had no history of concussion (73.7%). All participants completed the ImPACT at two time points, approximately 6 weeks apart. The PCSS was the main outcome measure, and eight symptom indices were calculated (a total symptom score, three symptom summary indices, and four symptom clusters). Pearson correlations (r) and intraclass correlation coefficients (ICCs) were computed as measures of test-retest reliability. Overall, reliabilities ranged from low to high (r = .44 to .80; ICC = .44 to .77). The cognitive symptom cluster exhibited the highest test-retest reliability (r = .80, ICC = .77), followed by the positive symptom total (PST) index, an indicator of the total number of symptoms endorsed (r = .71, ICC = .69). In contrast, the commonly used total symptom score showed lower test-retest reliability (r = .67, ICC = .62). Paired-samples t tests revealed no significant differences between test and retest for any of the symptom variables (all p > .01). Finally, reliable change indices (RCI) were computed to determine whether differences observed between test and retest represented clinically significant change. RCI values were provided for each symptom index at the 80%, 90%, and 95% confidence intervals. These results suggest that evaluating additional symptom indices beyond the total symptom score from the PCSS is beneficial. Findings from this study can be applied to athlete samples to assess reliable change in symptoms following concussion.

The impact of tinnitus upon cognition in adults: A systematic review.

PubMed

Tegg-Quinn, Susan; Bennett, Rebecca J; Eikelboom, Robert H; Baguley, David M

2016-10-01

To systematically review and analyse experimental outcomes of studies exploring the impact of tinnitus upon cognitive function and their implications for clinical management of invasive tinnitus. A systematic and descriptive review. Eighteen studies were identified investigating the impact of tinnitus on cognitive function. The 18 studies evaluated cognitive function using 24 different objective behavioural tests, nine electrophysiological recordings, one oculomotor test, and one self-report questionnaire. The studies spanned 18 years and revealed numerous interactions potentially contributing to the cognitive difficulties frequently reported by people with invasive tinnitus. The studies indicate a clear association between tinnitus and aspects of cognitive function, specifically the executive control of attention. Tinnitus impairs cognitive function by way of impact upon executive control of attention. Clinical management of patients reporting tinnitus and cognitive difficulties requires an understanding of the reciprocal relationship between tinnitus and cognitive function, with additive effects of anxiety, depression, and somatic cognitive bias. Further study is required to establish the impact of advancing age, hearing loss, anxiety, depression tinnitus duration, and distress upon cognitive function in people with invasive tinnitus.

Effect of education and language on baseline concussion screening tests in professional baseball players.

PubMed

Jones, Nathaniel S; Walter, Kevin D; Caplinger, Roger; Wright, Daniel; Raasch, William G; Young, Craig

2014-07-01

The purpose of the present study was to investigate the possible effects of sociocultural influences, specifically pertaining to language and education, on baseline neuropsychological concussion testing as obtained via immediate postconcussion assessment and cognitive testing (ImPACT) of players from a professional baseball team. A retrospective chart review. Baseline testing of a professional baseball organization. Four hundred five professional baseball players. Age, languages spoken, hometown country location (United States/Canada vs overseas), and years of education. The 5 ImPACT composite scores (verbal memory, visual memory, visual motor speed, reaction time, impulse control) and ImPACT total symptom score from the initial baseline testing. The result of t tests revealed significant differences (P < 0.05) when comparing native English to native Spanish speakers in many scores. Even when corrected for education, the significant differences (P < 0.05) remained in some scores. Sociocultural differences may result in differences in computer-based neuropsychological testing scores.

Impact evaluation of composite floor sections

NASA Technical Reports Server (NTRS)

Boitnott, Richard L.; Fasanella, Edwin L.

1989-01-01

Graphite-epoxy floor sections representative of aircraft fuselage construction were statically and dynamically tested to evaluate their response to crash loadings. These floor sections were fabricated using a frame-stringer design typical of present aluminum aircraft without features to enhance crashworthiness. The floor sections were tested as part of a systematic research program developed to study the impact response of composite components of increasing complexity. The ultimate goal of the research program is to develop crashworthy design features for future composite aircraft. Initially, individual frames of six-foot diameter were tested both statically and dynamically. The frames were then used to construct built-up floor sections for dynamic tests at impact velocities of approximately 20 feet/sec to simulate survivable crash velocities. In addition, static tests were conducted to gain a better understanding of the failure mechanisms seen in the dynamic tests.

The Impact of Peer Mentoring on Pupils' Emotional Literacy Competencies

ERIC Educational Resources Information Center

O'Hara, Donna

2011-01-01

Research suggests that peer mentoring can positively impact on emotional literacy competencies. This study explored the effects of peer mentoring on the emotional literacy competencies of Year 7 peer mentees using a quasi-experimental pre-test and post-test control group design. Results supported the hypothesis that peer mentoring has a positive…

Computerized neuropsychological test performance of youth football players at different positions: A comparison of high and low contact players.

PubMed

Tsushima, William T; Ahn, Hyeong Jun; Siu, Andrea M; Fukuyama, Tama; Murata, Nathan M

2017-02-28

The aim of this study was to examine the effects of head impact frequency on the neuropsychological test results of football players who participate in different positions on the team. Based on the biomechanical measures of head impact frequency reported in high school football, a High Contact group (n = 480) consisting of offensive and defensive linemen was compared with a Low Contact group (n = 640) comprised of receivers and defensive backs. The results revealed that the High Contact group obtained poorer performances on the Immediate Post-Concussion Assessment and Cognitive Testing (ImPACT) on three Composite scores (Verbal Memory, Visual Motor Speed, Impulse Control) and the Total Symptom score compared to the Low Contact group. The present study is the first, to date, to report differences in the neuropsychological test performances of athletes who participate in high and low contact football positions. The findings raise tentative concerns that youth football players exposed to repetitive head trauma, including subconcussive impacts, may be at risk for lowered neuropsychological functioning and increased symptoms.

76 FR 55653 - Notice of Intent To Prepare an Environmental Impact Statement/Overseas Environmental Impact...

Federal Register 2010, 2011, 2012, 2013, 2014

2011-09-08

...Pursuant to section 102(2)(c) of the National Environmental Policy Act of 1969, as implemented by the Council on Environmental Quality Regulations (40 Code of Federal Regulations parts 1500-1508), and Executive Order 12114, the Department of the Navy (DoN) announces its intent to prepare an Environmental Impact Statement (EIS)/Overseas Environmental Impact Statement (OEIS) to evaluate the potential environmental effects associated with maintaining military readiness training and research, development, testing, and evaluation (hereafter referred to as ``training and testing'') activities conducted in the Mariana Islands Training and Testing (MITT) EIS/OEIS Study Area. The MITT Study Area includes the existing Mariana Islands Range Complex (MIRC), additional areas on the high seas, and a general transit corridor between Hawaii to MITT where training and testing activities may occur. The MIRC is the only major Navy range complex in the Study Area. The DoN is preparing this EIS/OEIS to renew current regulatory permits and authorizations, address current training and testing not covered under existing permits and authorizations, and to obtain those permits and authorizations necessary to support force structure changes and emerging and future training and testing requirements including those associated with new platforms and weapons systems within the MITT Study Area, starting in 2015, thereby ensuring critical Department of Defense (DoD) requirements are met. The DoN will invite the National Marine Fisheries Service, United States (U.S.) Fish and Wildlife Service (Pacific Islands Fish and Wildlife Office), and U.S. Air Force, to be cooperating agencies in preparation of the EIS/OEIS.

Cryogenic performance of single polymer polypropylene composites

NASA Astrophysics Data System (ADS)

Atli-Veltin, Bilim

2018-03-01

The main objective of the experimental study detailed in this paper is to investigate the performance of fully recyclable, lightweight, low-cost, thermoplastic Polypropylene (PP) composite tapes at low temperatures. Coupons made of [±45] and [0/90] laminates are subjected to tensile and 3-point bending tests at room temperature as well as at -196 °C. In addition to that, cryogenic low velocity impact tests at 268 J and 777 J impact energies are performed on tubular structures. The results are indicating that the laminates made of PP tapes have sufficient ductility for cryogenic applications. Low velocity impact tests showed that the viscoelastic behavior of the material is preserved, even at such low temperatures and more than 72% of impact energy is absorbed by the material.

Train-to-train rear end impact tests - volume II - impact test summaries

DOT National Transportation Integrated Search

1977-03-31

This final report documents these nine tests. Volume I, Pre-Impact Determination of Vehicle Properties, summarizes the vehicle properties obtained prior to the impact tests. These vehicle properties were used in computer simulation of the impact test...

Correlation between Self-Citation and Impact Factor in Iranian English Medical Journals in WoS and ISC: A Comparative Approach.

PubMed

Ghazi Mirsaeid, Seyed Javad; Motamedi, Nadia; Ramezan Ghorbani, Nahid

2015-09-01

In this study, the impact of self-citation (Journal and Author) on impact factor of Iranian English Medical journals in two international citation databases, Web of Science (WoS) and Islamic world science citation center (ISC), were compared by citation analysis. Twelve journals in WoS and 26 journals in ISC databases indexed between the years (2006-2009) were selected and compared. For comparison of self-citation rate in two databases, we used Wilcoxon and Mann-whitney tests. We used Pearson test for correlation of self-citation and IF in WoS, and the Spearman's correlation coefficient for the ISC database. Covariance analysis was used for comparison of two correlation tests. P. value was 0.05 in all of tests. There was no significant difference between self-citation rates in two databases (P>0.05). Findings also showed no significant difference between the correlation of Journal self-citation and impact factor in two databases (P=0.526) however, there was significant difference between the author's self-citation and impact factor in these databases (P<0.001). The impact of Author's self-citation in the Impact Factor of WoS was higher than the ISC.

Is Test Taker Perception of Assessment Related to Construct Validity?

ERIC Educational Resources Information Center

Xie, Qin

2011-01-01

This study examined test takers' perception of assessment demand and its impact on the measurement of intended constructs. More than 800 test takers took a pre- and a posttest of College English Test Band 4 and filled in a perception questionnaire to report the skills they perceive as necessary for answering the test. The study found test takers…

Impact Delamination and Fracture in Aluminum/Acrylic Sandwich Plates

NASA Technical Reports Server (NTRS)

Liaw, Benjamin; Zeichner, Glenn; Liu, Yanxiong; Bowles, Kenneth J. (Technical Monitor)

2000-01-01

Impact-induced delamination and fracture in 6061-T6 aluminum/cast acrylic sandwich plates adhered by epoxy were generated in an instrumented drop-weight impact machine. Although only a small dent was produced on the aluminum side when a hemispherical penetrator tup was dropped onto it from a couple of inches, a large ring of delamination at the interface was observed. The delamination damage was often accompanied by severe shattering in the acrylic substratum. Damage patterns in the acrylic layer include radial and ring cracks and, together with delamination at the interface, may cause peeling-off of acrylic material from the sandwich plate. Theory of stress-wave propagation can be used to explain these damage patterns. The impact tests were conducted at various temperatures. The results also show clearly that temperature effect is very important in impact damage. For pure cast acrylic nil-ductile transition (NDT) occurs between 185-195 F. Excessive impact energy was dissipated into fracture energy when tested at temperature below this range or through plastic deformation when tested at temperature above the NDT temperature. Results from this study will be used as baseline data for studying fiber-metal laminates, such as GLARE and ARALL for advanced aeronautical and astronautical applications.

Prescription safety eyewear: impact studies of lens and frame failure.

PubMed

Vinger, P F; Woods, T A

2000-02-01

To determine if a plano lens could be the test lens for all prescription (Rx) lenses and to investigate why Rx lenses pop out of safety eyewear. Plano and Rx polycarbonate lenses (n = 641) with varying thickness and edge geometry, mounted on steel lens holders, and Rx safety eyewear (n = 128) placed on headforms were impacted with test objects of varying diameter and hardness. Impacts were studied with 500 to 2,000 frames-per-second motion analysis. Plano lenses were at least, or more, prone to failure (dislodgment, perforation, shatter, or crack) than -3.00 or +3.00 lenses of the same minimum thickness. More than 40% of safety frames with removable lenses broke or had lenses pop out when impacted with energies expected in industry and sports. Plano lenses can be used as the test lenses for all Rx lenses made of the same material with the same minimal thickness. The ANSI Z87.1-1989 industrial standard for Rx eyewear is inadequate for sports or other activities with high-impact potential. The best lens-retention system has, as a component, a frame with a bevel perpendicular to a frontal impact force.

Gender, Complexity, and Science for All: Systemizing and Its Impact on Motivation to Learn Science for Different Science Subjects

ERIC Educational Resources Information Center

Zeyer, Albert

2018-01-01

The present study is based on a large cross-cultural study, which showed that a systemizing cognition type has a high impact on motivation to learn science, while the impact of gender is only indirect thorough systemizing. The present study uses the same structural equation model as in the cross-cultural study and separately tests it for physics,…

Impact of family language and testing language on reading performance in a bilingual educational context.

PubMed

Elosua Oliden, Paula; Mujika Lizaso, Josu

2014-01-01

When different languages co-exist in one area, or when one person speaks more than one language, the impact of language on psychological and educational assessment processes can be considerable. The aim of this work was to study the impact of testing language in a community with two official languages: Spanish and Basque. By taking the PISA 2009 Reading Comprehension Test as a basis for analysis, four linguistic groups were defined according to the language spoken at home and the test language. Psychometric equivalence between test forms and differences in results among the four language groups were analyzed. The comparison of competence means took into account the effects of the index of socioeconomic and cultural status (ISEC) and gender. One reading unit with differential item functioning was detected. The reading competence means were considerably higher in the monolingual Spanish-Spanish group. No differences were found between the language groups based on family language when the test was conducted in Basque. The study illustrates the importance of taking into account psychometric, linguistic and sociolinguistic factors in linguistically diverse assessment contexts.

Laser-induced Microparticle Impact Experiments on Soft Materials

NASA Astrophysics Data System (ADS)

Kooi, Steven; Veysset, David; Maznev, Alexei; Yang, Yun Jung; Olsen, Bradley; Nelson, Keith

High-velocity impact testing is used to study fundamental aspects of materials behavior under high strain rates as well as in applications ranging from armor testing to the development of novel drug delivery platforms. In this work, we study high-velocity impact of micron-size projectiles on soft viscoelastic materials including synthetic hydrogels and gelatin samples. In an all optical laser-induced projectile impact test (LIPIT), a monolayer of microparticles is placed on a transparent substrate coated with a laser absorbing polymer layer. Ablation of a laser-irradiated polymer region accelerates the microparticles which are ejected from the launching pad into free space, reaching controllable speeds up to 1.5 km/s depending on the laser pulse energy and particle characteristics. The particles are monitored while in free space and after impact on the target surface with an ultrahigh-speed multi-frame camera that can record up to 16 images with time resolution of each frame as short as 3 ns. We present images and movies capturing individual particle impact and penetration in gels, and discuss the observed dynamics in the case of high Reynolds and Weber numbers. The results can provide direct input for modeling of high-velocity impact responses and high strain rate deformation in gels and other soft materials..

Rubber Impact on 3D Textile Composites

NASA Astrophysics Data System (ADS)

Heimbs, Sebastian; Van Den Broucke, Björn; Duplessis Kergomard, Yann; Dau, Frederic; Malherbe, Benoit

2012-06-01

A low velocity impact study of aircraft tire rubber on 3D textile-reinforced composite plates was performed experimentally and numerically. In contrast to regular unidirectional composite laminates, no delaminations occur in such a 3D textile composite. Yarn decohesions, matrix cracks and yarn ruptures have been identified as the major damage mechanisms under impact load. An increase in the number of 3D warp yarns is proposed to improve the impact damage resistance. The characteristic of a rubber impact is the high amount of elastic energy stored in the impactor during impact, which was more than 90% of the initial kinetic energy. This large geometrical deformation of the rubber during impact leads to a less localised loading of the target structure and poses great challenges for the numerical modelling. A hyperelastic Mooney-Rivlin constitutive law was used in Abaqus/Explicit based on a step-by-step validation with static rubber compression tests and low velocity impact tests on aluminium plates. Simulation models of the textile weave were developed on the meso- and macro-scale. The final correlation between impact simulation results on 3D textile-reinforced composite plates and impact test data was promising, highlighting the potential of such numerical simulation tools.

Prioritization in comparative effectiveness research: the CANCERGEN Experience.

PubMed

Thariani, Rahber; Wong, William; Carlson, Josh J; Garrison, Louis; Ramsey, Scott; Deverka, Patricia A; Esmail, Laura; Rangarao, Sneha; Hoban, Carolyn J; Baker, Laurence H; Veenstra, David L

2012-05-01

Systematic approaches to stakeholder-informed research prioritization are a central focus of comparative effectiveness research. Genomic testing in cancer is an ideal area to refine such approaches given rapid innovation and potentially significant impacts on patient outcomes. To develop and pilot test a stakeholder-informed approach to prioritizing genomic tests for future study in collaboration with the cancer clinical trials consortium SWOG. We conducted a landscape analysis to identify genomic tests in oncology using a systematic search of published and unpublished studies, and expert consultation. Clinically valid tests suitable for evaluation in a comparative study were presented to an external stakeholder group. Domains to guide the prioritization process were identified with stakeholder input, and stakeholders ranked tests using multiple voting rounds. A stakeholder group was created including representatives from patient-advocacy groups, payers, test developers, regulators, policy makers, and community-based oncologists. We identified 9 domains for research prioritization with stakeholder feedback: population impact; current standard of care, strength of association; potential clinical benefits, potential clinical harms, economic impacts, evidence of need, trial feasibility, and market factors. The landscape analysis identified 635 studies; of 9 tests deemed to have sufficient clinical validity, 6 were presented to stakeholders. Two tests in lung cancer (ERCC1 and EGFR) and 1 test in breast cancer (CEA/CA15-3/CA27.29) were identified as top research priorities. Use of a diverse stakeholder group to inform research prioritization is feasible in a pragmatic and timely manner. Additional research is needed to optimize search strategies, stakeholder group composition, and integration with existing prioritization mechanisms.

Prioritization in Comparative Effectiveness Research: The CANCERGEN Experience in Cancer Genomics

PubMed Central

Thariani, Rahber; Wong, William; Carlson, Josh J; Garrison, Louis; Ramsey, Scott; Deverka, Patricia A; Esmail, Laura; Rangarao, Sneha; Hoban, Carolyn J; Baker, Laurence H; Veenstra, David L

2012-01-01

Background Systematic approaches to stakeholder-informed research prioritization are a central focus of comparative effectiveness research. Genomic testing in cancer is an ideal area to refine such approaches given rapid innovation and potentially significant impacts on patient outcomes. Objective To develop and pilot-test a stakeholder-informed approach to prioritizing genomic tests for future study in collaboration with the cancer clinical trials consortium SWOG. Methods We conducted a landscape-analysis to identify genomic tests in oncology using a systematic search of published and unpublished studies, and expert consultation. Clinically valid tests suitable for evaluation in a comparative study were presented to an external stakeholder group. Domains to guide the prioritization process were identified with stakeholder input, and stakeholders ranked tests using multiple voting rounds. Results A stakeholder group was created including representatives from patient-advocacy groups, payers, test developers, regulators, policy-makers, and community-based oncologists. We identified nine domains for research prioritization with stakeholder feedback: population impact; current standard of care, strength of association; potential clinical benefits, potential clinical harms, economic impacts, evidence of need, trial feasibility, and market factors. The landscape-analysis identified 635 studies; of 9 tests deemed to have sufficient clinical validity, 6 were presented to stakeholders. Two tests in lung cancer (ERCC1 and EGFR) and one test in breast cancer (CEA/CA15-3/CA27.29) were identified as top research priorities. Conclusions Use of a diverse stakeholder group to inform research prioritization is feasible in a pragmatic and timely manner. Additional research is needed to optimize search strategies, stakeholder group composition and integration with existing prioritization mechanisms. PMID:22274803

Air and Water Quality Impacts of Brownfields Redevelopment: A Study of Five Communities

EPA Pesticide Factsheets

This Study of Five Communities tests an analytical approach to quantifying the environmental impacts of multiple redevelopment projects in a given municipal area in a manner that can be replicated in other regions.

Visual Confirmation (VICON) of Takeoff Clearance Signal System Impact Study

DOT National Transportation Integrated Search

1980-11-01

A study was performed to evaluate the impact on airport capacity and voice communications of the Visual Confirmation of Takeoff Clearance (VICON) Signal System. Befoe-and-after test data collection and analysis were conducted at Bradley International...

Testing of the masonry arches of the Brooklyn Bridge approaches

NASA Astrophysics Data System (ADS)

Limaye, Hemant S.

1996-11-01

Diagnostic procedures play an important role in performing a condition survey of a structure. Specialized tests are used during a field survey to supplement visual observations. The tests provide valuable information regarding the internal condition of the structure and quality of the construction materials. The tests also help in determining the extent of damage, if any. Recently, a team of consulting engineers performed a study to determine the remaining capacity of the Brooklyn Bridge approaches for the Department of Transportation, City of New York. Using advanced diagnostic procedures such as impact-echo and flatjack testing, additional information was gathered to assist in the study. Impact-echo testing was helpful in identifying the condition of the brick soffits which were covered with pneumatically- applied concrete, and flatjack testing was useful in determining in-situ compressive strength and compression modulus of the brick masonry. The paper describes the work and the testing results.

The Impact Response of Carbon/Epoxy Laminates (Center Director's Discretionary Fund, Project No. 94-13)

NASA Technical Reports Server (NTRS)

Nettles, A. T.; Hodge, A. J.

1997-01-01

Low velocity dropweight impact tests were conducted on carbon/epoxy laminates under various boundary conditions. The composite plates were 8-ply (+45,0,-45,90)s laminates supported in a clamped-clamped/free-free configuration with varying amounts of in-plane load, N(sub x), applied. Specimens were impacted at energies of 3.4, 4.5, and 6 Joules (2.5, 3.3, and 4.4 ft-lb). The amount of damage induced into the specimen was evaluated using instrumented impact techniques, x-ray inspection, and cross-sectional photomicroscopy. Some static identation tests were performed to examine if the impact events utilized in this study were of a quasi-static nature and also to gain insight into the shape of the deflected surface at various impact load combinations. Load-displacement curves from these tests were compared to those of the impact tests, as was damage determined from x-ray inspection. The finite element technique was used to model the impact event and determine the stress field within the laminae. Results showed that for a given impact energy level, more damage was induced into the specimen as the external in-plane load, N(sub x), was increased. The majority of damage observed consisted of back face splitting of the matrix parallel to the fibers in that ply, associated with delaminations emanating from these splits. The analysis showed qualitatively the results of impact conditions on maximum load of impact, maximum transverse deflection, and first failure mode and location.

Numerical simulation study on thermal response of PBX 9501 to low velocity impact

NASA Astrophysics Data System (ADS)

Lou, Jianfeng; Zhou, Tingting; Zhang, Yangeng; Zhang, Xiaoli

2017-01-01

Impact sensitivity of solid high explosives, an important index in evaluating the safety and performance of explosives, is an important concern in handling, storage, and shipping procedures. It is a great threat for either bare dynamite or shell charge when subjected to low velocity impact involved in traffic accidents or charge piece drops. The Steven test is an effective tool to study the relative sensitivity of various explosives. In this paper, we built the numerical simulation method involving mechanical, thermo and chemical properties of Steven test based on the thermo-mechanical coupled material model. In the model, the stress-strain relationship is described by dynamic plasticity model, the thermal effect of the explosive induced by impact is depicted by isotropic thermal material model, the chemical reaction of explosives is described by Arrhenius reaction rate law, and the effects of heating and melting on mechanical properties and thermal properties of materials are also taken into account. Specific to the standard Steven test, the thermal and mechanical response rules of PBX 9501 at various impact velocities were numerically analyzed, and the threshold velocity of explosive initiation was obtained, which is in good agreement with experimental results. In addition, the effect of confine condition of test device to the threshold velocity was explored.

Air jet erosion test on plasma sprayed surface by varying erodent impingement pressure and impingement angle

NASA Astrophysics Data System (ADS)

Behera, Ajit; Behera, Asit; Mishra, S. C.; Pani, S.; Parida, P.

2015-02-01

Fly-ash premixed with quartz and illmenite powder in different weight proportions are thermal sprayed on mild steel and copper substrates at various input power levels of the plasma torch ranging from 11 kW to 21 kW DC. The erosion test has done using Air Jet erosion test Reg (As per ASTM G76) with silica erodent typically 150-250 pm in size. Multiple tests were performed at increasing the time duration from 60 sec to 180 sec with increasing pressure (from 1 bar to 2.5 bar) and angle (60° & 90°). This study reveals that the impact velocity and impact angle are two most significant parameters among various factors influencing the wear rate of these coatings. The mechanisms and microstructural changes that arise during erosion wear are studied by using SEM. It is found that, when erodent are impacting the fresh un-eroded surface, material removal occurs by the continuous evolution of craters on the surface. Upper layer splats are removed out after 60 sec and second layer splat erosion starts. Based on these observations Physical models are developed. Some graphs plotted between mass loss-rate versus time period/impact Pressure/impact Angle gives good correlation with surface features observed.

Compression of thick laminated composite beams with initial impact-like damage

NASA Technical Reports Server (NTRS)

Breivik, N. L.; Guerdal, Z.; Griffin, O. H., Jr.

1992-01-01

While the study of compression after impact of laminated composites has been under consideration for many years, the complexity of the damage initiated by low velocity impact has not lent itself to simple predictive models for compression strength. The damage modes due to non-penetrating, low velocity impact by large diameter objects can be simulated using quasi-static three-point bending. The resulting damage modes are less coupled and more easily characterized than actual impact damage modes. This study includes the compression testing of specimens with well documented initial damage states obtained from three-point bend testing. Compression strengths and failure modes were obtained for quasi-isotropic stacking sequences from 0.24 to 1.1 inches thick with both grouped and interspersed ply stacking. Initial damage prior to compression testing was divided into four classifications based on the type, extent, and location of the damage. These classifications are multiple through-thickness delaminations, isolated delamination, damage near the surface, and matrix cracks. Specimens from each classification were compared to specimens tested without initial damage in order to determine the effects of the initial damage on the final compression strength and failure modes. A finite element analysis was used to aid in the understanding and explanation of the experimental results.

Butanol / Honda CRADA Report

DTIC Science & Technology

2015-02-01

study developed a test plan to test BU16 in CG boats, assessing boat performance, and the modifications required to use the fuel. The third study (and...current project) executed this test plan to quantify implementation issues, benefits and impacts of using the alternative fuel in CG boats under...4  2.2  Project 2: Test Plan Development

Influence of Stacking Sequence and Notch Angle on the Charpy Impact Behavior of Hybrid Composites

NASA Astrophysics Data System (ADS)

Behnia, S.; Daghigh, V.; Nikbin, K.; Fereidoon, A.; Ghorbani, J.

2016-09-01

The low-velocity impact behavior of hybrid composite laminates was investigated. The epoxy matrix was reinforced with aramid, glass, basalt, and carbon fabrics using the hand lay-up technique. Different stacking sequences and notch angles were and notch angles considered and tested using a Charpy impact testing machine to study the hybridization and notch angle effects on the impact response of the hybrid composites. The energy absorption capability of specimens with different stacking sequences and notch angles is compared and discussed. It is shown that the hybridization can enhance the mechanical performance of composite materials.

Study of austenitic stainless steel welded with low alloy steel filler metal. [tensile and impact strength tests

NASA Technical Reports Server (NTRS)

Burns, F. A.; Dyke, R. A., Jr.

1979-01-01

The tensile and impact strength properties of 316L stainless steel plate welded with low alloy steel filler metal were determined. Tests were conducted at room temperature and -100 F on standard test specimens machined from as-welded panels of various chemical compositions. No significant differences were found as the result of variations in percentage chemical composition on the impact and tensile test results. The weldments containing lower chromium and nickel as the result of dilution of parent metal from the use of the low alloy steel filler metal corroded more severely in a marine environment. The use of a protective finish, i.e., a nitrile-based paint containing aluminum powder, prevented the corrosive attack.

Impact of Environment-Based Teaching on Student Achievement: A Study of Washington State Middle Schools

ERIC Educational Resources Information Center

Bartosh, Oksana; Tudor, Margaret; Ferguson, Lynne; Taylor, Catherine

2009-01-01

This paper reports on a project which investigates the impact of systemic environmental education (EE) programs on student achievement on EE-based integrated tests and standardized tests in math, language arts, and listening. Systemic environmental education programs are defined by curriculum designed to align and integrate subjects around real…

The More, the Better? The Impact of Instructional Time on Student Performance

ERIC Educational Resources Information Center

Cattaneo, Maria A.; Oggenfuss, Chantal; Wolter, Stefan C.

2017-01-01

Building on earlier work that explored within-student variation in hours of instruction across school subjects, we investigate the impact of instruction time on student test scores in Switzerland, as measured by the PISA 2009 test. Our results confirm the results of previous studies of a positive effect of instruction time on student performance.…

Train-to-Train Rear End Impact Tests : Volume 3. Appendix A : Impact Test Data ; Appendix B : Report of Inventions

DOT National Transportation Integrated Search

1977-03-01

This final report documents these tests. Volume I, Pre-Impact Determination of Vehicle Properties, summarizes the vehicle properities obtained prior to the impact tests. These vehicle properties were used in computer simulation of the impact tests an...

Effect of Oxygen Concentration on Autogenous Ignition Temperature and Pneumatic Impact Ignitability of Nonmetallic Materials

NASA Technical Reports Server (NTRS)

Smith, Sarah

2009-01-01

Extensive test data exist on the ignitability of nonmetallic materials in pure oxygen, but these characteristics are not as well understood for lesser oxygen concentrations. In this study, autogenous ignition temperature testing and pneumatic impact testing were used to better understand the effects of oxygen concentration on ignition of nonmetallic materials. Tests were performed using oxygen concentrations of 21, 34, 45, and 100 %. The following materials were tested: PTFE Teflon(Registered Trademark), Buna-N, Silicone, Zytel(Registered Trademark) 42, Viton(registered Trademark) A, and Vespel(Registered Trademark) SP-21.

Comparison of ALE and SPH Simulations of Vertical Drop Tests of a Composite Fuselage Section into Water

NASA Technical Reports Server (NTRS)

Jackson, Karen E.; Fuchs, Yvonne T.

2008-01-01

Simulation of multi-terrain impact has been identified as an important research area for improved prediction of rotorcraft crashworthiness within the NASA Subsonic Rotary Wing Aeronautics Program on Rotorcraft Crashworthiness. As part of this effort, two vertical drop tests were conducted of a 5-ft-diameter composite fuselage section into water. For the first test, the fuselage section was impacted in a baseline configuration without energy absorbers. For the second test, the fuselage section was retrofitted with a composite honeycomb energy absorber. Both tests were conducted at a nominal velocity of 25-ft/s. A detailed finite element model was developed to represent each test article and water impact was simulated using both Arbitrary Lagrangian Eulerian (ALE) and Smooth Particle Hydrodynamics (SPH) approaches in LS-DYNA, a nonlinear, explicit transient dynamic finite element code. Analytical predictions were correlated with experimental data for both test configurations. In addition, studies were performed to evaluate the influence of mesh density on test-analysis correlation.

A Change Impact Analysis to Characterize Evolving Program Behaviors

NASA Technical Reports Server (NTRS)

Rungta, Neha Shyam; Person, Suzette; Branchaud, Joshua

2012-01-01

Change impact analysis techniques estimate the potential effects of changes made to software. Directed Incremental Symbolic Execution (DiSE) is an intraprocedural technique for characterizing the impact of software changes on program behaviors. DiSE first estimates the impact of the changes on the source code using program slicing techniques, and then uses the impact sets to guide symbolic execution to generate path conditions that characterize impacted program behaviors. DiSE, however, cannot reason about the flow of impact between methods and will fail to generate path conditions for certain impacted program behaviors. In this work, we present iDiSE, an extension to DiSE that performs an interprocedural analysis. iDiSE combines static and dynamic calling context information to efficiently generate impacted program behaviors across calling contexts. Information about impacted program behaviors is useful for testing, verification, and debugging of evolving programs. We present a case-study of our implementation of the iDiSE algorithm to demonstrate its efficiency at computing impacted program behaviors. Traditional notions of coverage are insufficient for characterizing the testing efforts used to validate evolving program behaviors because they do not take into account the impact of changes to the code. In this work we present novel definitions of impacted coverage metrics that are useful for evaluating the testing effort required to test evolving programs. We then describe how the notions of impacted coverage can be used to configure techniques such as DiSE and iDiSE in order to support regression testing related tasks. We also discuss how DiSE and iDiSE can be configured for debugging finding the root cause of errors introduced by changes made to the code. In our empirical evaluation we demonstrate that the configurations of DiSE and iDiSE can be used to support various software maintenance tasks

Morphology-Property relationship of high density Polyethylene/Hevea Brasiliensis Leaves/Imperata cylindrica hybrid composite: Impact strength

NASA Astrophysics Data System (ADS)

Rashidi, A. R.; Muhammad, A.; Roslan, A.

2017-09-01

This research studies about the Hevea Brasiliensis Leaves and Imperata Cylindrica that was used as filler in High Density Polyethylene (HDPE). The fillers content were varied in the composite by 5 wt%, 15 wt% and 25 wt% respectively. This polymer composite are being studied by using Impact Test and Scanning Electron Microscopy (SEM). The analysis show that the impact strength value increased when the percent of bio filler used is low. The result between pure HDPE and the composites shows an outcome of significant changes in impact energy values, while the values between different composite change slightly. A composite that contained 5 wt% of fillers is the better energy absorber than 15 wt% and 25 wt% according to impact testing. In addition, the morphology studies on the composite sample show that the bio-filler was successfully embedded. Overall, these finding suggest that HBL and IC can be an alternative filler to be incorporated in polymer matrix.

Test Expectancy and Memory for Important Information

ERIC Educational Resources Information Center

Middlebrooks, Catherine D.; Murayama, Kou; Castel, Alan D.

2017-01-01

Prior research suggests that learners study and remember information differently depending upon the type of test they expect to later receive. The current experiments investigate how testing expectations impact the study of and memory for valuable information. Participants studied lists of words ranging in value from 1 to 10 points with the goal…

Inhibited Shaped Charge Launcher Testing of Spacecraft Shield Designs

NASA Technical Reports Server (NTRS)

Grosch, Donald J.

1996-01-01

This report describes a test program in which several orbital debris shield designs were impact tested using the inhibited shaped charge launcher facility at Southwest Research Institute. This facility enables researchers to study the impact of one-gram aluminum projectiles on various shielding designs at velocities above 11 km/s. A total of twenty tests were conducted on targets provided by NASA-MSFC. This report discusses in detail the shield design, the projectile parameters and the test configuration used for each test. A brief discussion of the target damage is provided, as the detailed analysis of the target response will be done by NASA-MSFC.

Is the impact of fatigue related to walking capacity and perceived ability in persons with multiple sclerosis? A multicenter study.

PubMed

Dalgas, U; Langeskov-Christensen, M; Skjerbæk, A; Jensen, E; Baert, I; Romberg, A; Santoyo Medina, C; Gebara, B; Maertens de Noordhout, B; Knuts, K; Béthoux, F; Rasova, K; Severijns, D; Bibby, B M; Kalron, A; Norman, B; Van Geel, F; Wens, I; Feys, P

2018-04-15

The relationship between fatigue impact and walking capacity and perceived ability in patients with multiple sclerosis (MS) is inconclusive in the existing literature. A better understanding might guide new treatment avenues for fatigue and/or walking capacity in patients with MS. To investigate the relationship between the subjective impact of fatigue and objective walking capacity as well as subjective walking ability in MS patients. A cross-sectional multicenter study design was applied. Ambulatory MS patients (n = 189, age: 47.6 ± 10.5 years; gender: 115/74 women/men; Expanded Disability Status Scale (EDSS): 4.1 ± 1.8 [range: 0-6.5]) were tested at 11 sites. Objective tests of walking capacity included short walking tests (Timed 25-Foot Walk (T25FW), 10-Metre Walk Test (10mWT) at usual and fastest speed and the timed up and go (TUG)), and long walking tests (2- and 6-Minute Walk Tests (MWT). Subjective walking ability was tested applying the Multiple Sclerosis Walking Scale-12 (MSWS-12). Fatigue impact was measured by the self-reported modified fatigue impact scale (MFIS) consisting of a total score (MFIS total ) and three subscales (MFIS physical , MFIS cognitive and MFIS psychosocial ). Uni- and multivariate regression analysis were performed to evaluate the relation between walking and fatigue impact. MFIS total was negatively related with long (6MWT, r = -0.14, p = 0.05) and short composite (TUG, r = -0.22, p = 0.003) walking measures. MFIS physical showed a significant albeit weak relationship to walking speed in all walking capacity tests (r = -0.22 to -0.33, p < .0001), which persisted in the multivariate linear regression analysis. Subjective walking ability (MSWS-12) was related to MFIS total (r = 0.49, p < 0.0001), as well as to all other subscales of MFIS (r = 0.24-0.63, p < 0.001), showing stronger relationships than objective measures of walking. The physical impact of fatigue is weakly related to objective walking capacity, while general, physical, cognitive and psychosocial fatigue impact are weakly to moderately related to subjective walking ability, when analysed in a large heterogeneous sample of MS patients. Copyright © 2018 Elsevier B.V. All rights reserved.

Dynamic testing of airplane shock-absorbing struts

NASA Technical Reports Server (NTRS)

Langer, P; Thome, W

1932-01-01

Measurement of perpendicular impacts of a landing gear with different shock-absorbing struts against the drum testing stand. Tests were made with pneumatic shock absorbers having various degrees of damping, liquid shock absorbers, steel-spring shock absorbers and rigid struts. Falling tests and rolling tests. Maximum impact and gradual reduction of the impacts in number and time in the falling tests. Maximum impact and number of weaker impacts in rolling tests.

Research on environmental impact of water-based fire extinguishing agents

NASA Astrophysics Data System (ADS)

Wang, Shuai

2018-02-01

This paper offers current status of application of water-based fire extinguishing agents, the environmental and research considerations of the need for the study of toxicity research. This paper also offers systematic review of test methods of toxicity and environmental impact of water-based fire extinguishing agents currently available, illustrate the main requirements and relevant test methods, and offer some research findings for future research considerations. The paper also offers limitations of current study.

Invalid performance and the ImPACT in national collegiate athletic association division I football players.

PubMed

Szabo, Ashley J; Alosco, Michael L; Fedor, Andrew; Gunstad, John

2013-01-01

Immediate Post-Concussion Assessment and Cognitive Testing (ImPACT) is a computerized cognitive test battery commonly used for concussion evaluation. An important aspect of these procedures is baseline testing, but researchers have suggested that many users do not use validity indices to ensure adequate effort during testing. No one has examined the prevalence of invalid performance for college football players. To examine the prevalence of invalid scores on ImPACT testing. Cross-sectional study. National Collegiate Athletic Association Division I university. A total of 159 athletes (age = 20.3 ± 1.41 years; range = 17.8-23.7 years) from a Division I collegiate football team participated. An informational intervention regarding the importance of concussion testing to promote safety was administered before testing for the most recent season. We examined preseason ImPACT testing data across a 3-year period (total assessments = 269). Based on invalid and sandbagging indices denoted by the ImPACT manual, protocols were examined to indicate how many invalid indices each athlete had. A total of 27.9% (n = 75) of assessments were suggestive of invalid scores, with 4.1% (n = 11) suggesting invalid responding only, 17.5% (n = 47) indicating "sandbagging" only, and 6.3% (n = 17) showing both invalid and sandbagging responding. The informational intervention did not reduce the prevalence of invalid responding. These findings highlight the need for further information about the ImPACT validity indices and whether they truly reflect poor effort. Future work is needed to identify practices to reliably target and reduce invalid responding.

Antimisting kerosene JT3 engine fuel system integration study

NASA Technical Reports Server (NTRS)

Fiorentino, A.

1987-01-01

An analytical study and laboratory tests were conducted to assist NASA in determining the safety and mission suitability of the modified fuel system and flight tests for the Full-Scale Transport Controlled Impact Demonstration (CID) program. This twelve-month study reviewed and analyzed both the use of antimisting kerosene (AMK) fuel and the incorporation of a fuel degrader on the operational and performance characteristics of the engines tested. Potential deficiencies and/or failures were identified and approaches to accommodate these deficiencies were recommended to NASA Ames -Dryden Flight Research Facility. The result of flow characterization tests on degraded AMK fuel samples indicated levels of degradation satisfactory for the planned missions of the B-720 aircraft. The operability and performance with the AMK in a ground test engine and in the aircraft engines during the test flights were comparable to those with unmodified Jet A. For the final CID test, the JT-3C-7 engines performed satisfactorily while operating on AMK right up to impact.

Shock-absorbing effect of shoe insert materials commonly used in management of lower extremity disorders.

PubMed

Shiba, N; Kitaoka, H B; Cahalan, T D; Chao, E Y

1995-01-01

The efficacy of 3 shock-absorbing materials was compared by determining impact characteristics with a drop test method and also by testing the effect of each material when used as a shoe insert in 16 asymptomatic subjects. Peak vertical ground reaction force (F1, F2, F3) and temporal force factors (T1, T2, T3) were obtained with a force plate at a high-frequency sampling rate. Impact force, impact time, impact slope, and impact energy were determined. A standard weight was dropped from 3 heights on each material covering the force plate while reduction of peak force was compared. Impact force was attenuated most effectively by Insert 3 (polymeric foam rubber) and averaged 11% less than that in shoes without inserts. Impact time was increased for all 3 inserts. Impact slope and impact energy were reduced significantly in Insert 3. There was a significant difference in peak vertical force F1 for all 3 inserts, in vertical force F2 for Insert 2 (viscoelastic polymeric material), and in vertical force F3 for Insert 2. Drop-test studies showed that at all ball heights, the highest mean peak force was observed consistently in Insert 2.

Impact and residual fatigue behavior of ARALL and AS6/5245 composite materials

NASA Technical Reports Server (NTRS)

Johnson, W. S.

1986-01-01

Aramide fiber reinforced aluminum laminates (ARALL) represent a cross between resin matrix composites and metals. The purpose of this study was to evaluate the impact sensitivity of this concept. Two types of ARALL (7075 aluminum prestrained and 2024 aluminum not prestrained) were tested through static indentation and the results compared to sheet 2024-T3 and 7075-T6 aluminum alloys. A state-of-the-art composite (AS6/5245) was also tested and compared to the ARALL. Further, the two types of ARALL material and the composite were dynamically impacted at two energy levels and fatigue tested to determine residual fatigue strength. Both forms of the ARALL material had worse impact resistance than monolithic sheet aluminum. The ARALL material made with 2024-T3 aluminum had better impact resistance than did the laminates made with 7075-T6 aluminum. The ARALL materials are at least equal to the composite material in impact damage resistance and are better for impact detection. The composite material has higher residual fatigue strength after impact than the ARALL material and is 25 percent lighter. The prestraining of the ARALL greatly reduces the fatigue growth of impact damage.

Examining the Feasibility and Effect of Transitioning GED Tests to Computer

ERIC Educational Resources Information Center

Higgins, Jennifer; Patterson, Margaret Becker; Bozman, Martha; Katz, Michael

2010-01-01

This study examined the feasibility of administering GED Tests using a computer based testing system with embedded accessibility tools and the impact on test scores and test-taker experience when GED Tests are transitioned from paper to computer. Nineteen test centers across five states successfully installed the computer based testing program,…

Relationship between concussion history and neurocognitive test performance in National Football League draft picks.

PubMed

Solomon, Gary S; Kuhn, Andrew

2014-04-01

There are limited empirical data available regarding the relationship between concussion history and neurocognitive functioning in active National Football League (NFL) players in general and NFL draft picks in particular. Potential NFL draft picks undergo 2 neurocognitive tests at the National Invitational Camp (Scouting Combine) every year: the Wonderlic and, since 2011, the Immediate Post-concussion Assessment and Cognitive Testing (ImPACT). After conclusion of the combine and before the draft, NFL teams invite potential draft picks to their headquarters for individual visits where further assessment may occur. To examine the relationship between concussion history and neurocognitive performance (ImPACT and Wonderlic) in a sample of elite NFL draft picks. Cohort study; Level of evidence, 3. Over 7 years, 226 potential draft picks were invited to visit a specific NFL team's headquarters after the combine. The athletes were divided into 3 groups based on self-reported concussion history: no prior concussions, 1 prior concussion, and 2 or more prior concussions. Neurocognitive measures of interest included Wonderlic scores (provided by the NFL team) and ImPACT composite scores (administered either at the combine or during a visit to the team headquarters). The relationship between concussion history and neurocognitive scores was assessed, as were the relationships among the 2 neurocognitive tests. Concussion history had no relationship to neurocognitive performance on either the Wonderlic or ImPACT. Concussion history did not affect performance on either neurocognitive test, suggesting that for this cohort, a history of concussion may not have adverse effects on neurocognitive functioning as measured by these 2 tests. This study reveals no correlation between concussion history and neurocognitive test scores (ImPACT, Wonderlic) in soon-to-be active NFL athletes.

High Pressure Quick Disconnect Particle Impact Tests

NASA Technical Reports Server (NTRS)

Rosales, Keisa R.; Stoltzfus, Joel M.

2009-01-01

NASA Johnson Space Center White Sands Test Facility (WSTF) performed particle impact testing to determine whether there is a particle impact ignition hazard in the quick disconnects (QDs) in the Environmental Control and Life Support System (ECLSS) on the International Space Station (ISS). Testing included standard supersonic and subsonic particle impact tests on 15-5 PH stainless steel, as well as tests performed on a QD simulator. This paper summarizes the particle impact tests completed at WSTF. Although there was an ignition in Test Series 4, it was determined the ignition was caused by the presence of a machining imperfection. The sum of all the test results indicates that there is no particle impact ignition hazard in the ISS ECLSS QDs. KEYWORDS: quick disconnect, high pressure, particle impact testing, stainless steel

Test Expectancy and Memory for Important Information

PubMed Central

Middlebrooks, Catherine D.; Murayama, Kou; Castel, Alan D.

2016-01-01

Prior research suggests that learners study and remember information differently depending upon the type of test they expect to later receive. The current experiments investigate how testing expectations impact the study of and memory for valuable information. Participants studied lists of words ranging in value from 1–10 points with the goal being to maximize their score on a later memory test. Half of the participants were told to expect a recognition test after each list, while the other half were told to expect a recall test. After several lists of receiving tests congruent with expectations, participants studying for a recognition test instead received an unexpected recall test. In Experiment 1, participants who had studied for a recognition test recalled less of the valuable information than participants anticipating the recall format. These participants continued to attend less to item value on future (expected) recall tests than participants who had only ever experienced recall testing. When the recognition tests were made more demanding in Experiment 2, value-based recall improved relative to Experiment 1: though memory for the valuable information remained superior when participants studied with the expectation of having to recall the information, there were no longer significant differences after accounting for recall testing experience. Thus, recall-based testing encouraged strategic, value-based encoding and enhanced retrieval of important information, while recognition testing in some cases limited value-based study and memory. These results extend prior work concerning the impact of testing expectations on memory, offering further insight into how people study important information. PMID:28095010

Test Anxiety and Academic Performance among Undergraduates: The Moderating Role of Achievement Motivation.

PubMed

Balogun, Anthony Gbenro; Balogun, Shyngle Kolawole; Onyencho, Chidi Victor

2017-02-13

This study investigated the moderating role of achievement motivation in the relationship between test anxiety and academic performance. Three hundred and ninety three participants (192 males and 201 females) selected from a public university in Ondo State, Nigeria using a purposive sampling technique, participated in the study. They responded to measures of test anxiety and achievement motivation. Three hypotheses were tested using moderated hierarchical multiple regression analysis. Results showed that test anxiety had a negative impact on academic performance (β = -.23; p < .05). Achievement motivation had a positive impact on academic performance (β = .38; p < .05). Also, achievement motivation significantly moderated the relationship between test anxiety and academic performance (β = .10; p < .01). These findings suggest that university management should design appropriate psycho-educational interventions that would enhance students' achievement motivation.

Defining Group Membership: The Impact of Multiple versus Single Ethnic/Racial Categories on Testing Practices. Research Notes. RN-13

ERIC Educational Resources Information Center

Wendler, Cathy; Feigenbaum, Miriam; Escandón, Mérida

2001-01-01

The SAT Program undertook two studies aimed at evaluating the impact of allowing students to indicate more than one ethnic/racial category. Results of this study indicated that there is little impact on DIF [differential item functioning] analyses when different definitions of ethnic/racial classifications are used compared to traditionally…

Effect of Impact Damage and Open Hole on Compressive Strength of Hybrid Composite Laminates

NASA Technical Reports Server (NTRS)

Hiel, Clement; Brinson, H. F.

1993-01-01

Impact damage tolerance is a frequently listed design requirement for composites hardware. The effect of impact damage and open hole size on laminate compressive strength was studied on sandwich beam specimens which combine CFRP-GFRP hybrid skins and a syntactic foam core. Three test specimen configurations have been investigated for this study. The first two were sandwich beams which were loaded in pure bending (by four point flexure). One series had a skin damaged by impact, and the second series had a circular hole machined through one of the skins. The reduction of compressive strength with increasing damage (hole) size was compared. Additionally a third series of uniaxially loaded open hole compression coupons were tested to generate baseline data for comparison with both series of sandwich beams.

CEMS study of strain induced phase transformation in manganese Hadfield steel

NASA Astrophysics Data System (ADS)

Cabanillas, E. D.; Alvarez, E. P.; Hey, A.; Mercader, R. C.

1991-11-01

A Conversion Electron Mössbauer Spectroscopy, (CEMS), study of phase transformations in a Hadfield steel induced by high rate strains is reported. Hadfield steel samples were impact deformed and the ensuing changes in the magnetic properties at the deformed zone and its surroundings have been studied by CEMS. The CEMS results are compared with wear tests and optical microscopy and show a formation of martensite by impact deformation only at the surface. Martensite is not produced by compression or tensile stresses but appears after wear tests in proportions that depend on the load and velocity conditions of test. The understanding of martensite phase formation and its evolution during deformation processes is also addressed.

Introduction of a method for presenting health-based impacts of the emission from products, based on emission measurements of materials used in manufacturing of the products

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

Jørgensen, Rikke Bramming, E-mail: rikke.jorgensen@iot.ntnu.no

A method for presenting the health impact of emissions from furniture is introduced, which could be used in the context of environmental product declarations. The health impact is described by the negative indoor air quality potential, the carcinogenic potential, the mutagenic and reprotoxic potential, the allergenic potential, and the toxicological potential. An experimental study of emissions from four pieces of furniture is performed by testing both the materials used for production of the furniture and the complete piece of furniture, in order to compare the results gained by adding emissions of material with results gained from testing the finished piecemore » of furniture. Calculating the emission from a product based on the emission from materials used in the manufacture of the product is a new idea. The relation between calculated results and measured results from the same products differ between the four pieces of furniture tested. Large differences between measured and calculated values are seen for leather products. More knowledge is needed to understand why these differences arise. Testing materials allows us to compare different suppliers of the same material. Four different foams and three different timber materials are tested, and the results vary between materials of the same type. If the manufacturer possesses this type of knowledge of the materials from the subcontractors it could be used as a selection criterion according to production of low emission products. -- Highlights: • A method for presenting health impact of emissions is introduced. • An experimental study of emissions from four pieces of furniture is performed. • Health impact is calculated based on sum of contribution from the materials used. • Calculated health impact is compared to health impact of the manufactured product. • The results show that health impact could be useful in product development and for presentation in EPDs.« less

Biological responses to disturbance from simulated deep-sea polymetallic nodule mining.

PubMed

Jones, Daniel O B; Kaiser, Stefanie; Sweetman, Andrew K; Smith, Craig R; Menot, Lenaick; Vink, Annemiek; Trueblood, Dwight; Greinert, Jens; Billett, David S M; Arbizu, Pedro Martinez; Radziejewska, Teresa; Singh, Ravail; Ingole, Baban; Stratmann, Tanja; Simon-Lledó, Erik; Durden, Jennifer M; Clark, Malcolm R

2017-01-01

Commercial-scale mining for polymetallic nodules could have a major impact on the deep-sea environment, but the effects of these mining activities on deep-sea ecosystems are very poorly known. The first commercial test mining for polymetallic nodules was carried out in 1970. Since then a number of small-scale commercial test mining or scientific disturbance studies have been carried out. Here we evaluate changes in faunal densities and diversity of benthic communities measured in response to these 11 simulated or test nodule mining disturbances using meta-analysis techniques. We find that impacts are often severe immediately after mining, with major negative changes in density and diversity of most groups occurring. However, in some cases, the mobile fauna and small-sized fauna experienced less negative impacts over the longer term. At seven sites in the Pacific, multiple surveys assessed recovery in fauna over periods of up to 26 years. Almost all studies show some recovery in faunal density and diversity for meiofauna and mobile megafauna, often within one year. However, very few faunal groups return to baseline or control conditions after two decades. The effects of polymetallic nodule mining are likely to be long term. Our analyses show considerable negative biological effects of seafloor nodule mining, even at the small scale of test mining experiments, although there is variation in sensitivity amongst organisms of different sizes and functional groups, which have important implications for ecosystem responses. Unfortunately, many past studies have limitations that reduce their effectiveness in determining responses. We provide recommendations to improve future mining impact test studies. Further research to assess the effects of test-mining activities will inform ways to improve mining practices and guide effective environmental management of mining activities.

Biological responses to disturbance from simulated deep-sea polymetallic nodule mining

PubMed Central

Kaiser, Stefanie; Sweetman, Andrew K.; Smith, Craig R.; Menot, Lenaick; Vink, Annemiek; Trueblood, Dwight; Greinert, Jens; Billett, David S. M.; Arbizu, Pedro Martinez; Radziejewska, Teresa; Singh, Ravail; Ingole, Baban; Stratmann, Tanja; Simon-Lledó, Erik; Durden, Jennifer M.; Clark, Malcolm R.

2017-01-01

Commercial-scale mining for polymetallic nodules could have a major impact on the deep-sea environment, but the effects of these mining activities on deep-sea ecosystems are very poorly known. The first commercial test mining for polymetallic nodules was carried out in 1970. Since then a number of small-scale commercial test mining or scientific disturbance studies have been carried out. Here we evaluate changes in faunal densities and diversity of benthic communities measured in response to these 11 simulated or test nodule mining disturbances using meta-analysis techniques. We find that impacts are often severe immediately after mining, with major negative changes in density and diversity of most groups occurring. However, in some cases, the mobile fauna and small-sized fauna experienced less negative impacts over the longer term. At seven sites in the Pacific, multiple surveys assessed recovery in fauna over periods of up to 26 years. Almost all studies show some recovery in faunal density and diversity for meiofauna and mobile megafauna, often within one year. However, very few faunal groups return to baseline or control conditions after two decades. The effects of polymetallic nodule mining are likely to be long term. Our analyses show considerable negative biological effects of seafloor nodule mining, even at the small scale of test mining experiments, although there is variation in sensitivity amongst organisms of different sizes and functional groups, which have important implications for ecosystem responses. Unfortunately, many past studies have limitations that reduce their effectiveness in determining responses. We provide recommendations to improve future mining impact test studies. Further research to assess the effects of test-mining activities will inform ways to improve mining practices and guide effective environmental management of mining activities. PMID:28178346

Long-term reliability of ImPACT in professional ice hockey.

PubMed

Echemendia, Ruben J; Bruce, Jared M; Meeuwisse, Willem; Comper, Paul; Aubry, Mark; Hutchison, Michael

2016-02-01

This study sought to assess the test-retest reliability of Immediate Post-Concussion Assessment and Cognitive Testing (ImPACT) across 2-4 year time intervals and evaluate the utility of a newly proposed two-factor (Speed/Memory) model of ImPACT across multiple language versions. Test-retest data were collected from non-concussed National Hockey League (NHL) players across 2-, 3-, and 4-year time intervals. The two-factor model was examined using different language versions (English, French, Czech, Swedish) of the test using a one-year interval, and across 2-4 year intervals using the English version of the test. The two-factor Speed index improved reliability across multiple language versions of ImPACT. The Memory factor also improved but reliability remained below the traditional cutoff of .70 for use in clinical decision-making. ImPACT reliabilities remained low (below .70) regardless of whether the four-composite or the two-factor model was used across 2-, 3-, and 4-year time intervals. The two-factor approach increased ImPACT's one-year reliability over the traditional four-composite model among NHL players. The increased stability in test scores improves the test's ability to detect cognitive changes following injury, which increases the diagnostic utility of the test and allows for better return to play decision-making by reducing the risk of exposing an athlete to additional trauma while the brain may be at a heightened vulnerability to such trauma. Although the Speed Index increases the clinical utility of the test, the stability of the Memory index remains low. Irrespective of whether the two-factor or traditional four-composite approach is used, these data suggest that new baselines should occur on a yearly basis in order to maximize clinical utility.

Diverse Studies in the Reactivated NASA/Ames Radiation Facility: From Shock Layer Spectroscopy to Thermal Protection System Impact

NASA Technical Reports Server (NTRS)

Miller, Robert J.; Hartman, G. Joseph (Technical Monitor)

1994-01-01

NASA/Ames' Hypervelocity Free-Flight Radiation Facility has been reactivated after having been decommissioned for some 15 years, first tests beginning in early 1994. This paper discusses two widely different studies from the first series, one involving spectroscopic analysis of model shock-layer radiation, and the other the production of representative impact damage in space shuttle thermal protection tiles for testing in the Ames arc-jet facilities. These studies emphasize the interorganizational and interdisciplinary value of the facility in the newly-developing structure of NASA.

Hybrid carbon-glass fiber/toughened epoxy thick composites subject to drop-weight and ballistic impacts

NASA Astrophysics Data System (ADS)

Sevkat, Ercan

The goals of this study are to investigate the low velocity and ballistic impact response of thick-section hybrid fiber composites at room temperature. Plain-woven S2-Glass and IM7 Graphite fabrics are chosen as fiber materials reinforcing the SC-79 epoxy. Four different types of composites consisting of alternating layers of glass and graphite woven fabric sheets are considered. Tensile tests are conducted using 98 KN (22 kip) MTS testing machine equipped with environmental chamber. Low-velocity impact tests are conducted using an Instron-Dynatup 8250 impact test machine equipped with an environmental chamber. Ballistic impact tests are performed using helium pressured high-speed gas-gun. Tensile tests results were used to define the material behavior of the hybrid and non-hybrid composites in Finite Element modeling. The low velocity and ballistic impact tests showed that hybrid composites performance was somewhere between non-hybrid woven composites. Using woven glass fabrics as outer skin improved the impact performance of woven graphite composite. However hybrid composites are prone to delamination especially between dissimilar layers. The ballistic limit velocity V50 hybrid composites were higher that of woven graphite composite and lower than that of woven glass composite. Both destructive cross-sectional micrographs and nondestructive ultrasonic techniques are used to evaluate the damage created by impact. The Finite Element code LS-DYNA is chosen to perform numerical simulations of low velocity and ballistic impact on thick-section hybrid composites. The damage progression in these composites shows anisotropic nonlinearity. The material model to describe this behavior is not available in LS-DYNA material library. Initially, linear orthotropic material with damage (Chan-Chan Model) is employed to simulate some of the experimental results. Then, user-defined material subroutine is incorporated into LS-DYNA to simulate the nonlinear behavior. The experimentally obtained force-time histories, strain-time histories and damage patterns of impacted composites are compared with Finite element results. The results indicate that LS-DYNA could simulate the impact responses with sufficient accuracy once proper material models and boundary conditions are defined.

Constrained Laboratory vs. Unconstrained Steering-Induced Rollover Crash Tests.

PubMed

Kerrigan, Jason R; Toczyski, Jacek; Roberts, Carolyn; Zhang, Qi; Clauser, Mark

2015-01-01

The goal of this study was to evaluate how well an in-laboratory rollover crash test methodology that constrains vehicle motion can reproduce the dynamics of unconstrained full-scale steering-induced rollover crash tests in sand. Data from previously-published unconstrained steering-induced rollover crash tests using a full-size pickup and mid-sized sedan were analyzed to determine vehicle-to-ground impact conditions and kinematic response of the vehicles throughout the tests. Then, a pair of replicate vehicles were prepared to match the inertial properties of the steering-induced test vehicles and configured to record dynamic roof structure deformations and kinematic response. Both vehicles experienced greater increases in roll-axis angular velocities in the unconstrained tests than in the constrained tests; however, the increases that occurred during the trailing side roof interaction were nearly identical between tests for both vehicles. Both vehicles experienced linear accelerations in the constrained tests that were similar to those in the unconstrained tests, but the pickup, in particular, had accelerations that were matched in magnitude, timing, and duration very closely between the two test types. Deformations in the truck test were higher in the constrained than the unconstrained, and deformations in the sedan were greater in the unconstrained than the constrained as a result of constraints of the test fixture, and differences in impact velocity for the trailing side. The results of the current study suggest that in-laboratory rollover tests can be used to simulate the injury-causing portions of unconstrained rollover crashes. To date, such a demonstration has not yet been published in the open literature. This study did, however, show that road surface can affect vehicle response in a way that may not be able to be mimicked in the laboratory. Lastly, this study showed that configuring the in-laboratory tests to match the leading-side touchdown conditions could result in differences in the trailing side impact conditions.

Applications of computerized adaptive testing (CAT) to the assessment of headache impact.

PubMed

Ware, John E; Kosinski, Mark; Bjorner, Jakob B; Bayliss, Martha S; Batenhorst, Alice; Dahlöf, Carl G H; Tepper, Stewart; Dowson, Andrew

2003-12-01

To evaluate the feasibility of computerized adaptive testing (CAT) and the reliability and validity of CAT-based estimates of headache impact scores in comparison with 'static' surveys. Responses to the 54-item Headache Impact Test (HIT) were re-analyzed for recent headache sufferers (n = 1016) who completed telephone interviews during the National Survey of Headache Impact (NSHI). Item response theory (IRT) calibrations and the computerized dynamic health assessment (DYNHA) software were used to simulate CAT assessments by selecting the most informative items for each person and estimating impact scores according to pre-set precision standards (CAT-HIT). Results were compared with IRT estimates based on all items (total-HIT), computerized 6-item dynamic estimates (CAT-HIT-6), and a developmental version of a 'static' 6-item form (HIT-6-D). Analyses focused on: respondent burden (survey length and administration time), score distributions ('ceiling' and 'floor' effects), reliability and standard errors, and clinical validity (diagnosis, level of severity). A random sample (n = 245) was re-assessed to test responsiveness. A second study (n = 1103) compared actual CAT surveys and an improved 'static' HIT-6 among current headache sufferers sampled on the Internet. Respondents completed measures from the first study and the generic SF-8 Health Survey; some (n = 540) were re-tested on the Internet after 2 weeks. In the first study, simulated CAT-HIT and total-HIT scores were highly correlated (r = 0.92) without 'ceiling' or 'floor' effects and with a substantial reduction (90.8%) in respondent burden. Six of the 54 items accounted for the great majority of item administrations (3603/5028, 77.6%). CAT-HIT reliability estimates were very high (0.975-0.992) in the range where 95% of respondents scored, and relative validity (RV) coefficients were high for diagnosis (RV = 0.87) and severity (RV = 0.89); patient-level classifications were accurate 91.3% for a diagnosis of migraine. For all three criteria of change, CAT-HIT scores were more responsive than all other measures. In the second study, estimates of respondent burden, item usage, reliability and clinical validity were replicated. The test-retest reliability of CAT-HIT was 0.79 and alternate forms coefficients ranged from 0.85 to 0.91. All correlations with the generic SF-8 were negative. CAT-based administrations of headache impact items achieved very large reductions in respondent burden without compromising validity for purposes of patient screening or monitoring changes in headache impact over time. IRT models and CAT-based dynamic health assessments warrant testing among patients with other conditions.

High-Speed Photographic Study of Wave Propagation and Impact Damage in Fused Silica and AlON Using the Edge-On Impact (EOI) Method

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

Strassburger, E.; Patel, P.; McCauley, J. W.

An Edge-on Impact (EOI) technique, developed at the Ernst-Mach-Institute (EMI), coupled with a Cranz-Schardin high-speed camera, has been successfully utilized to visualize dynamic fracture in many brittle materials. In a typical test, the projectile strikes one edge of a specimen and damage formation and fracture propagation is recorded during the first 20 {mu}s after impact. In the present study, stress waves and damage propagation in fused silica and AlON were examined by means of two modified Edge-on Impact arrangements. In one arrangement, fracture propagation was observed simultaneously in side and top views of the specimens by means of two Cranz-Schardinmore » cameras. In another arrangement, the photographic technique was modified by placing the specimen between crossed polarizers and using the photo-elastic effect to visualize the stress waves. Pairs of impact tests at approximately equivalent velocities were carried out in transmitted plane (shadowgraphs) and crossed polarized light.« less

Effect of Reinforcement Using Stainless Steel Mesh, Glass Fibers, and Polyethylene on the Impact Strength of Heat Cure Denture Base Resin - An In Vitro Study.

PubMed

Murthy, H B Mallikarjuna; Shaik, Sharaz; Sachdeva, Harleen; Khare, Sumit; Haralur, Satheesh B; Roopa, K T

2015-06-01

The impact strength of denture base resin is of great concern and many approaches have been made to strengthen acrylic resin dentures. The objective of this study was to compare the impact strength of the denture base resin with and without reinforcement and to evaluate the impact strength of denture base resin when reinforced with stainless steel mesh, glass fiber, and polyethylene fibers in the woven form. The specimens (maxillary denture bases) were fabricated using a standard polyvinylsiloxane mold with conventional heat cured polymethyl methacrylate resin. The specimens were divided into four groups (n = 10). Group I specimens or control group were not reinforced. Group II specimens were reinforced with stainless steel mesh and Group III and Group IV specimens were reinforced with three percent by weight of glass fibers and polyethylene fibers in weave form respectively. All the specimens were immersed in water for 1-week before testing. The impact strength was measured with falling weight impact testing machine. One-way analysis of variance and Tukey's post-hoc test were used for statistical analysis. Highest impact strength values were exhibited by the specimens reinforced with polyethylene fibers followed by glass fibers, stainless steel mesh, and control group. Reinforcement of maxillary complete dentures showed a significant increase in impact strength when compared to unreinforced dentures. Polyethylene fibers exhibit better impact strength followed by glass fibers and stainless steel mesh. By using pre-impregnated glass and polyethylene fibers in woven form (prepregs) the impact strength of the denture bases can be increased effectively.

Impact reactivity of materials at very high oxygen pressure

NASA Technical Reports Server (NTRS)

Connor, H. W.; Minchey, J. G.; Crowder, R.; Davidson, R.

1983-01-01

The requirements for impact testing of materials in an oxygen atmosphere at pressures from 82.7 MPa (12,000 psi) to 172 MPa (25,000 psi) were evaluated. The impact tester system was evaluated for potential pressure increases from 69 MPa (10,000 psi) to 82.7 MPa (12,000 psi). The low pressure oxygen and nitrogen systems, the impact tower, the impact test cell, and the high pressure oxygen system were evaluated individually. Although the structural integrity of the impact test cell and the compressor were sufficient for operation at 82.7 MPa (12,000 psi), studies revealed possible material incompatibility at that pressure and above. It was recommended that if a component should be replaced for 82.7 MPa (12,000 psi) operation the replacement should meet the final objectives of 172 MPa (25,000 psi). Recommended changes in the system include; use of Monel 400 for pressures above 82.7 MPa (12,000 psi), use of bellows to replace the seal in the impact tester, use of a sapphire window attached to a fiber optic for event sensing, and use of a three diaphragm compressor.

Micrometeorite Impact Test of Flex Solar Array Coupon

NASA Technical Reports Server (NTRS)

Wright, K. H.; Schneider, T. A.; Vaughn, J. A.; Hoang, B.; Wong, F.; Gardiner, G.

2016-01-01

Spacecraft with solar arrays operate throughout the near earth environment and are increasingly planned for outer planet missions. An often overlooked test condition for solar arrays that is applicable to these missions is micrometeorite impacts and possibly electrostatic discharge (ESD) events resulting from these impacts. The Marshall Space Flight Center (MSFC) is partnering with Space Systems/Loral, LLC (SSL) to examine the results of simulated micrometeorite impacts on the electrical performance of an advanced, lightweight flexible solar array design. The test is performed at NASA MSFC's Microlight Gas Gun Facility. The SSL-provided coupons consist of three strings, each string with two solar cells in series. Five impacts will be induced at various locations on a powered test coupon under different string voltage (0 volts - 150 volts) and string current (1.1 amperes - 1.65 amperes) conditions. The maximum specified test voltage and current represent margins of 1.5 times for both voltage and current. The test parameters are chosen to demonstrate new array design robustness to any ESD event caused by plasma plumes resulting from a simulated micrometeorite impact. A second unpowered coupon will undergo two impacts: one impact on the front side and one impact on the back side. Following the impact testing, the second coupon will be exposed to a thermal cycle test to determine possible damage propagation and further electrical degradation due to thermally-induced stress. The setup, checkout, and results from the impact testing are discussed. The challenges for impact testing include precise coupon alignment to control impact location; pressure management during the impact process; and measurement of the true transient electrical response during impact on the powered coupon. Results from pre- and post-test visual and electrical functional testing are also discussed.

The psychological complexity of predictive testing for late onset neurogenetic diseases and hereditary cancers: implications for multidisciplinary counselling and for genetic education.

PubMed

Evers-Kiebooms, G; Welkenhuysen, M; Claes, E; Decruyenaere, M; Denayer, L

2000-09-01

Increasing knowledge about the human genome has resulted in the availability of a steadily increasing number of predictive DNA-tests for two major categories of diseases: neurogenetic diseases and hereditary cancers. The psychological complexity of predictive testing for these late onset diseases requires careful consideration. It is the main aim of the present paper to describe this psychological complexity, which necessitates an adequate and systematic multidisciplinary approach, including psychological counselling, as well as ongoing education of professionals and of the general public. Predictive testing for neurogenetic diseases--in an adequate counselling context--so far elicits optimism regarding the short- and mid-term impact of the predictive test result. The psychosocial impact has been most widely studied for Huntington's disease. Longitudinal studies are of the utmost importance in evaluating the long-term impact of predictive testing for neurogenetic diseases on the tested person and his/her family. Given the more recent experience with predictive DNA-testing for hereditary cancers, fewer published scientific data are available. Longitudinal research on the mid- and long-term psychological impact of the predictive test result is essential. Decision making regarding health surveillance or preventive surgery after being detected as a carrier of one of the relevant mutations should receive special attention. Tailoring the professional approach--inside and outside genetic centres--to the families' needs is a continuous challenge. Even if a continuous effort is made, several important questions remain unanswered, last but not least the question regarding the best strategy to guarantee that the availability of predictive genetic testing results in a reduction of suffering caused by genetic disease and in an improvement of the quality of life of families confronted with genetic disease.

Genomic tests for ovarian cancer detection and management.

PubMed

Myers, Evan R; Havrilesky, Laura J; Kulasingam, Shalini L; Sanders, Gillian D; Cline, Kathryn E; Gray, Rebecca N; Berchuck, Andrew; McCrory, Douglas C

2006-10-01

To assess the evidence that the use of genomic tests for ovarian cancer screening, diagnosis, and treatment leads to improved outcomes. PubMed and reference lists of recent reviews. We evaluated tests for: (a) single gene products; (b) genetic variations affecting risk of ovarian cancer; (c) gene expression; and (d) proteomics. For tests covered in recent evidence reports (cancer antigen 125 [CA-125] and breast cancer genes 1 and 2 [BRCA1/2]), we added studies published subsequent to the reports. We sought evidence on: (a) the analytic performance of tests in clinical laboratories; (b) the sensitivity and specificity of tests in different patient populations; (c) the clinical impact of testing in asymptomatic women, women with suspected ovarian cancer, and women with diagnosed ovarian cancer; (d) the harms of genomic testing; and (e) the impact of direct-to-consumer and direct-to-physician advertising on appropriate use of tests. We also constructed a computer simulation model to test the impact of different assumptions about ovarian cancer natural history on the relative effectiveness of different strategies. There are reasonable data on the clinical laboratory performance of most radioimmunoassays, but the majority of the data on other genomic tests comes from research laboratories. Genomic test sensitivity/specificity estimates are limited by small sample sizes, spectrum bias, and unrealistically large prevalences of ovarian cancer; in particular, estimates of positive predictive values derived from most of the studies are substantially higher than would be expected in most screening or diagnostic settings. We found no evidence relevant to the question of the impact of genomic tests on health outcomes in asymptomatic women. Although there is a relatively large literature on the association of test results and various clinical outcomes, the clinical utility of changing management based on these results has not been evaluated. We found no evidence that genomic tests for ovarian cancer have unique harms beyond those common to other tests for genetic susceptibility or other tests used in screening, diagnosis, and management of ovarian cancer. Studies of a direct-to-consumer campaign for BRCA1/2 testing suggest increased utilization, but the effect on "appropriateness" was unclear. Model simulations suggest that annual screening, even with a highly sensitive test, will not reduce ovarian cancer mortality by more than 50 percent; frequent screening has a very low positive predictive value, even with a highly specific test. Although research remains promising, adaptation of genomic tests into clinical practice must await appropriately designed and powered studies in relevant clinical settings.

Correlation between Self-Citation and Impact Factor in Iranian English Medical Journals in WoS and ISC: A Comparative Approach

PubMed Central

GHAZI MIRSAEID, Seyed Javad; MOTAMEDI, Nadia; RAMEZAN GHORBANI, Nahid

2015-01-01

Background: In this study, the impact of self-citation (Journal and Author) on impact factor of Iranian English Medical journals in two international citation databases, Web of Science (WoS) and Islamic world science citation center (ISC), were compared by citation analysis. Methods: Twelve journals in WoS and 26 journals in ISC databases indexed between the years (2006–2009) were selected and compared. For comparison of self-citation rate in two databases, we used Wilcoxon and Mann-whitney tests. We used Pearson test for correlation of self-citation and IF in WoS, and the Spearman’s correlation coefficient for the ISC database. Covariance analysis was used for comparison of two correlation tests. P. value was 0.05 in all of tests. Results: There was no significant difference between self-citation rates in two databases (P>0.05). Findings also showed no significant difference between the correlation of Journal self-citation and impact factor in two databases (P=0.526) however, there was significant difference between the author’s self-citation and impact factor in these databases (P<0.001). Conclusion: The impact of Author’s self-citation in the Impact Factor of WoS was higher than the ISC. PMID:26587498

Shatter resistance of spectacle lenses.

PubMed

Vinger, P F; Parver, L; Alfaro, D V; Woods, T; Abrams, B S

1997-01-08

To evaluate the relative strength and shatter resistance of spectacle lenses currently used in sunglasses and dress, sports, and industrial eyewear. Seven lenses that met the US American National Standards Institute (ANSI) Z80 standards for dress glasses (made of high-index plastic, allyl resin plastic, heat tempered glass, chemically tempered glass, and polycarbonate, and with center thickness ranging from 1 mm to 2.2 mm) and 4 lenses that met ANSI Z87 standards for industrial safety eyewear (allyl resin plastic, heat-tempered glass, chemically tempered glass, and polycarbonate, all with 3.0-mm center thickness) were tested for impact resistance to 5 projectiles (air gun pellets, golf balls, tennis balls, lacrosse balls, and baseballs). Impact energy required to shatter spectacle lenses. Based on 348 lens impacts, dress and industrial lenses made from glass, allyl resin plastic, and high-index plastic shattered at impact energies less than those expected to be encountered from the test projectiles during their routine use. Polycarbonate lenses demonstrated resistance to impact for all tested projectiles exceeding the impact potential expected during routine use. Under the test conditions of this study, polycarbonate lenses demonstrated greater impact resistance than other commonly used spectacle lenses that conform to prevailing eyewear standards. These findings suggest that current ANSI Z80 and ANSI Z87 standards should be reevaluated.

Measurement Agreement between Estimates of Aerobic Fitness in Youth: The Impact of Body Mass Index

ERIC Educational Resources Information Center

Saint-Maurice, Pedro F.; Welk, Gregory J.; Laurson, Kelly R.; Brown, Dale D.

2014-01-01

Purpose: The purpose of this study was to examine the impact of body mass index (BMI) on the agreement between aerobic capacity estimates from different Progressive Aerobic Cardiorespiratory Endurance Run (PACER) equations and the Mile Run Test. Method: The agreement between 2 different tests of aerobic capacity was examined on a large data set…

Students' Perception of the Condition of Their Classroom Physical Learning Environment and Its Impact on Their Learning and Motivation

ERIC Educational Resources Information Center

Asiyai, Romina

2014-01-01

This study examined the perception of secondary school students on the condition of their classroom physical learning environment and its impact on their learning and motivation. Four research questions were asked and answered using descriptive statistics while three hypotheses were formulated and tested using t-test statistics at 0.05 level of…

The Relationship between Processing and Storage in Working Memory Span: Not Two Sides of the Same Coin

ERIC Educational Resources Information Center

Maehara, Yukio; Saito, Satoru

2007-01-01

In working memory (WM) span tests, participants maintain memory items while performing processing tasks. In this study, we examined the impact of task processing requirements on memory-storage activities, looking at the stimulus order effect and the impact of storage requirements on processing activities, testing the processing time effect in WM…

A Report on the Findings of an Adult Education Client Impact Study: A Five Year Follow Up.

ERIC Educational Resources Information Center

Moore, Lawrence H.

A 1980 survey of General Educational Development (GED) equivalency certificate recipients who completed the GED test in 1975 measured influence and impact of successful GED completion on the individual. The sample consisted of 101 former adult students whose records came from the Murray and Paducah, Kentucky, GED testing centers. The survey…

The Impact of a Community-Based Comprehensive Sex Education Program on Chinese Adolescents' Sex-Related Knowledge and Attitudes

ERIC Educational Resources Information Center

Wang, Bo; Meier, Ann; Shah, Iqbal; Li, Xiaoming

2006-01-01

The purpose of this study was to evaluate a community-based comprehensive sex education program among unmarried youth in China. The impact of the intervention on sexual knowledge, attitudes, and sexual initiation were assessed, using a pre-test post-test quasi-experimental research design. The program used six methods for providing sex-related…

Response of an Impact Test Apparatus for Fall Protective Headgear Testing Using a Hybrid-III Head/Neck Assembly

PubMed Central

Caccese, V.; Ferguson, J.; Lloyd, J.; Edgecomb, M.; Seidi, M.; Hajiaghamemar, M.

2017-01-01

A test method based upon a Hybrid-III head and neck assembly that includes measurement of both linear and angular acceleration is investigated for potential use in impact testing of protective headgear. The test apparatus is based upon a twin wire drop test system modified with the head/neck assembly and associated flyarm components. This study represents a preliminary assessment of the test apparatus for use in the development of protective headgear designed to prevent injury due to falls. By including angular acceleration in the test protocol it becomes possible to assess and intentionally reduce this component of acceleration. Comparisons of standard and reduced durometer necks, various anvils, front, rear, and side drop orientations, and response data on performance of the apparatus are provided. Injury measures summarized for an unprotected drop include maximum linear and angular acceleration, head injury criteria (HIC), rotational injury criteria (RIC), and power rotational head injury criteria (PRHIC). Coefficient of variation for multiple drops ranged from 0.4 to 6.7% for linear acceleration. Angular acceleration recorded in a side drop orientation resulted in highest coefficient of variation of 16.3%. The drop test apparatus results in a reasonably repeatable test method that has potential to be used in studies of headgear designed to reduce head impact injury. PMID:28216804

Experimental Study of the Compression Response of Fluted-Core Composite Panels with Joints

NASA Technical Reports Server (NTRS)

Schultz, Marc R.; Rose, Cheryl A.; Guzman, J. Carlos; McCarville, Douglas; Hilburger, Mark W.

2012-01-01

Fluted-core sandwich composites consist of integral angled web members spaced between laminate face sheets, and may have the potential to provide benefits over traditional sandwich composites for certain aerospace applications. However, fabrication of large autoclave-cured fluted-core cylindrical shells with existing autoclaves will require that the shells be fabricated in segments, and joined longitudinally to form a complete barrel. Two different longitudinal fluted-core joint designs were considered experimentally in this study. In particular, jointed fluted-core-composite panels were tested in longitudinal compression because longitudinal compression is the primary loading condition in dry launch-vehicle barrel sections. One of the joint designs performed well in comparison with unjointed test articles, and the other joint design failed at loads approximately 14% lower than unjointed test articles. The compression-after-impact (CAI) performance of jointed fluted-core composites was also investigated by testing test articles that had been subjected to 6 ft-lb impacts. It was found that such impacts reduced the load-carrying capability by 9% to 40%. This reduction is dependent on the joint concept, component flute size, and facesheet thickness.

Train-to-train rear end impact tests - volume I - pre-impact determination of vehicle properties

DOT National Transportation Integrated Search

1999-03-31

This final report documents these nine tests. Volume I, Pre-Impact Determination of Vehicle Properties, summarizes the vehicle properties obtained prior to the impact tests. These vehicle properties were used in computer simulation of the impact test...

Impacts to the chest of PMHSs - Influence of impact location and load distribution on chest response.

PubMed

Holmqvist, Kristian; Svensson, Mats Y; Davidsson, Johan; Gutsche, Andreas; Tomasch, Ernst; Darok, Mario; Ravnik, Dean

2016-02-01

The chest response of the human body has been studied for several load conditions, but is not well known in the case of steering wheel rim-to-chest impact in heavy goods vehicle frontal collisions. The aim of this study was to determine the response of the human chest in a set of simulated steering wheel impacts. PMHS tests were carried out and analysed. The steering wheel load pattern was represented by a rigid pendulum with a straight bar-shaped front. A crash test dummy chest calibration pendulum was utilised for comparison. In this study, a set of rigid bar impacts were directed at various heights of the chest, spanning approximately 120mm around the fourth intercostal space. The impact energy was set below a level estimated to cause rib fracture. The analysed results consist of responses, evaluated with respect to differences in the impacting shape and impact heights on compression and viscous criteria chest injury responses. The results showed that the bar impacts consistently produced lesser scaled chest compressions than the hub; the Middle bar responses were around 90% of the hub responses. A superior bar impact provided lesser chest compression; the average response was 86% of the Middle bar response. For inferior bar impacts, the chest compression response was 116% of the chest compression in the middle. The damping properties of the chest caused the compression to decrease in the high speed bar impacts to 88% of that in low speed impacts. From the analysis it could be concluded that the bar impact shape provides lower chest criteria responses compared to the hub. Further, the bar responses are dependent on the impact location of the chest. Inertial and viscous effects of the upper body affect the responses. The results can be used to assess the responses of human substitutes such as anthropomorphic test devices and finite element human body models, which will benefit the development process of heavy goods vehicle safety systems. Copyright © 2015 Elsevier Ltd. All rights reserved.

76 FR 57720 - Notice of Intent To Prepare an Environmental Impact Statement/Overseas Environmental Impact...

Federal Register 2010, 2011, 2012, 2013, 2014

2011-09-16

...The Department of the Navy published a document in the Federal Register (76 FR 174) on September 8, 2011, concerning public scoping meetings to support the development of an Environmental Impact Statement/Overseas Environmental Impact Statement for the Mariana Islands Training and Testing Study Area. The document contained an incorrect scoping date.

Impact of genetic counseling and Connexin-26 and Connexin-30 testing on deaf identity and comprehension of genetic test results in a sample of deaf adults: a prospective, longitudinal study.

PubMed

Palmer, Christina G S; Boudreault, Patrick; Baldwin, Erin E; Sinsheimer, Janet S

2014-01-01

Using a prospective, longitudinal study design, this paper addresses the impact of genetic counseling and testing for deafness on deaf adults and the Deaf community. This study specifically evaluated the effect of genetic counseling and Connexin-26 and Connexin-30 genetic test results on participants' deaf identity and understanding of their genetic test results. Connexin-26 and Connexin-30 genetic testing was offered to participants in the context of linguistically and culturally appropriate genetic counseling. Questionnaire data collected from 209 deaf adults at four time points (baseline, immediately following pre-test genetic counseling, 1-month following genetic test result disclosure, and 6-months after result disclosure) were analyzed. Four deaf identity orientations (hearing, marginal, immersion, bicultural) were evaluated using subscales of the Deaf Identity Development Scale-Revised. We found evidence that participants understood their specific genetic test results following genetic counseling, but found no evidence of change in deaf identity based on genetic counseling or their genetic test results. This study demonstrated that culturally and linguistically appropriate genetic counseling can improve deaf clients' understanding of genetic test results, and the formation of deaf identity was not directly related to genetic counseling or Connexin-26 and Connexin-30 genetic test results.

Testing Factorial Invariance in Multilevel Data: A Monte Carlo Study

ERIC Educational Resources Information Center

Kim, Eun Sook; Kwok, Oi-man; Yoon, Myeongsun

2012-01-01

Testing factorial invariance has recently gained more attention in different social science disciplines. Nevertheless, when examining factorial invariance, it is generally assumed that the observations are independent of each other, which might not be always true. In this study, we examined the impact of testing factorial invariance in multilevel…

A Numerical/Experimental Study on the Impact and CAI Behaviour of Glass Reinforced Compsite Plates

NASA Astrophysics Data System (ADS)

Perillo, Giovanni; Jørgensen, Jens K.; Cristiano, Roberta; Riccio, Aniello

2018-04-01

This paper focuses on the development of an advance numerical model specifically for simulating low velocity impact events and related stiffness reduction on composite structures. The model is suitable for low cost thick composite structures like wind turbine blade and maritime vessels. The model consist of a combination of inter and intra laminar models. The intra-laminar model present a combination of Puck and Hashin failure theories for the evaluation of the fibre and matrix failure. The inter-laminar damage is instead simulated by Cohesive Zone Method based on energy approach. Basic material properties, easily measurable according to standardized tests, are required. The model has been used to simulate impact and compression after impact tests. Experimental tests have been carried out on thick E-Glass/Epoxy composite commonly used in the wind turbine industry. The clustering effect as well as the consequence of the impact energy have been experimentally tested. The accuracy of numerical model has been verified against experimental data showing a very good accuracy of the model.

Study of erosion characterization of carbon fiber reinforced composite material

NASA Astrophysics Data System (ADS)

Debnath, Uttam Kumar; Chowdhury, Mohammad Asaduzzaman; Kowser, Md. Arefin; Mia, Md. Shahin

2017-06-01

Carbon fiber composite materials are widely used at different engineering and industrial applications there are good physical, mechanical, chemical properties and light weight. Erosion behavior of materials depends on various factors such as impact angle, particle velocity, particle size, particle shape, particle type, particle flux, temperature of the tested materials. Among these factors impact angle and particle velocity have been recognized as two parameters that noticeably influence the erosion rates of all tested materials. Irregular shaped sand (SiO2) particles of various sizes (200-300 µm, 400-500 µm, and 500-600 µm) were selected erosive element. Tested conditions such as impingement angles between 15 degree to 90 degree, impact velocities between 30-50 m/sec, and stand-off distances 15-25 mm at surrounding room temperature were maintained. The highest level of erosion of the tested composite is obtained at 60° impact angle, which signifies the semi-ductile behavior of this material. Erosion showed increasing trend with impact velocity and decreasing nature in relation to stand-off distance. Surface damage was analyzed using SEM to examine the nature of the erosive wear mechanism.

Integrated Data Collection Analysis (IDCA) Program - AN and Bullseye Smokeless Powder

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

Sandstrom, Mary M.; Brown, Geoffrey W.; Preston, Daniel N.

The Integrated Data Collection Analysis (IDCA) program is conducting a proficiency study for Small- Scale Safety and Thermal (SSST) testing of homemade explosives (HMEs). Described here are the results for impact, friction, electrostatic discharge, and differential scanning calorimetry analysis of ammonium nitrate (AN) mixed with Bullseye® smokeless powder (Gunpowder). The participants found the AN/Gunpowder to: 1) have a range of sensitivity to impact, comparable to or less than RDX, 2) be fairly insensitive to friction as measured by BAM and ABL, 3) have a range for ESD, from insensitive to more sensitive than PETN, and 4) have thermal sensitivity aboutmore » the same as PETN and Gunpowder. This effort, funded by the Department of Homeland Security (DHS), is putting the issues of safe handling of these materials in perspective with standard military explosives. The study is adding SSST testing results for a broad suite of different HMEs to the literature. Ultimately the study has the potential to suggest new guidelines and methods and possibly establish the SSST testing accuracies needed when developing safe handling practices for HMEs. Each participating testing laboratory uses identical test materials and preparation methods. Note, however, the test procedures differ among the laboratories. The testing performers involved are Lawrence Livermore National Laboratory (LLNL), Los Alamos National Laboratory (LANL), Indian Head Division, Naval Surface Warfare Center, (NSWC IHD), Sandia National Laboratories (SNL), and Air Force Research Laboratory (AFRL/RXQL). These tests are conducted as a proficiency study in order to establish some consistency in test protocols, procedures, and experiments and to compare results when these testing variables cannot be made consistent. Keywords: Small-scale safety testing, proficiency test, impact-, friction-, spark discharge-, thermal testing, round-robin test, safety testing protocols, HME, RDX, potassium perchlorate, potassium chlorate, sodium chlorate, sugar, dodecane, PETN, carbon, ammonium nitrate, Gunpowder, Bullseye® smokeless powder.« less

The Effect of Pretest Exercise on Baseline Computerized Neurocognitive Test Scores.

PubMed

Pawlukiewicz, Alec; Yengo-Kahn, Aaron M; Solomon, Gary

2017-10-01

Baseline neurocognitive assessment plays a critical role in return-to-play decision making following sport-related concussions. Prior studies have assessed the effect of a variety of modifying factors on neurocognitive baseline test scores. However, relatively little investigation has been conducted regarding the effect of pretest exercise on baseline testing. The aim of our investigation was to determine the effect of pretest exercise on baseline Immediate Post-Concussion Assessment and Cognitive Testing (ImPACT) scores in adolescent and young adult athletes. We hypothesized that athletes undergoing self-reported strenuous exercise within 3 hours of baseline testing would perform more poorly on neurocognitive metrics and would report a greater number of symptoms than those who had not completed such exercise. Cross-sectional study; Level of evidence, 3. The ImPACT records of 18,245 adolescent and young adult athletes were retrospectively analyzed. After application of inclusion and exclusion criteria, participants were dichotomized into groups based on a positive (n = 664) or negative (n = 6609) self-reported history of strenuous exercise within 3 hours of the baseline test. Participants with a positive history of exercise were then randomly matched, based on age, sex, education level, concussion history, and hours of sleep prior to testing, on a 1:2 basis with individuals who had reported no pretest exercise. The baseline ImPACT composite scores of the 2 groups were then compared. Significant differences were observed for the ImPACT composite scores of verbal memory, visual memory, reaction time, and impulse control as well as for the total symptom score. No significant between-group difference was detected for the visual motor composite score. Furthermore, pretest exercise was associated with a significant increase in the overall frequency of invalid test results. Our results suggest a statistically significant difference in ImPACT composite scores between individuals who report strenuous exercise prior to baseline testing compared with those who do not. Since return-to-play decision making often involves documentation of return to neurocognitive baseline, the baseline test scores must be valid and accurate. As a result, we recommend standardization of baseline testing such that no strenuous exercise takes place 3 hours prior to test administration.

Integrated Cuing Requirements (ICR) Study: Demonstration Data Base and Users Guide.

DTIC Science & Technology

1983-07-01

viewed with a servo-mounted televison camera and used to provide a visual scene for an observer in an ATD. Modulation: Mathematically, the absolute...i(b). CROSS REFERENCE The impact of stationary scene RESULTS. . details was also tested in this See (c) study. See Figure 33.5-1. Ial TEST APPARATUS...size. (See the discussion of * the impact of perceived distance on perceived size in Section 31._.) Figure 33.4-1 Perceived Distance and Velocity of Self

On impact damage detection and quantification for CFRP laminates using structural response data only

NASA Astrophysics Data System (ADS)

Sultan, M. T. H.; Worden, K.; Pierce, S. G.; Hickey, D.; Staszewski, W. J.; Dulieu-Barton, J. M.; Hodzic, A.

2011-11-01

The overall purpose of the research is to detect and attempt to quantify impact damage in structures made from composite materials. A study that uses simplified coupon specimens made from a Carbon Fibre-Reinforced Polymer (CFRP) prepreg with 11, 12 and 13 plies is presented. PZT sensors were placed at three separate locations in each test specimen to record the responses from impact events. To perform damaging impact tests, an instrumented drop-test machine was used and the impact energy was set to cover a range of 0.37-41.72 J. The response signals captured from each sensor were recorded by a data acquisition system for subsequent evaluation. The impacted specimens were examined with an X-ray technique to determine the extent of the damaged areas and it was found that the apparent damaged area grew monotonically with impact energy. A number of simple univariate and multivariate features were extracted from the sensor signals recorded during impact by computing their spectra and calculating frequency centroids. The concept of discordancy from the statistical discipline of outlier analysis is employed in order to separate the responses from non-damaging and damaging impacts. The results show that the potential damage indices introduced here provide a means of identifying damaging impacts from the response data alone.

The effects of padded surfaces on the risk for cervical spine injury.

PubMed

Nightingale, R W; Richardson, W J; Myers, B S

1997-10-15

This is an in vitro study comparing cervical spine injuries produced in rigid head impacts and in padded head impacts. To test the hypothesis that deformable impact surfaces pose a greater risk for cervical spine injury than rigid surfaces using a cadaver-based model that includes the effects of the head and torso masses. It is widely assumed that energy-absorbing devices that protect the head from injury also reduce the risk for neck injury. However, this has not been demonstrated in any experimental or epidemiologic study. On the contrary, some studies have shown that padded surfaces have no effect on neck injury risk, and others have suggested that they can increase risk. Experiments were performed on 18 cadaveric cervical spines to test 6 combinations of impact angle and impact surface padding. The impact surface was oriented at -15 degrees (posterior impact), 0 degree (vertex impact), or +15 degrees (anterior impact). The impact surface was either a 3-mm sheet of lubricated Teflon or 5 cm of polyurethane foam. Impacts onto padded surfaces produced significantly larger neck impulses (P = 0.00023) and a significantly greater frequency of cervical spine injuries than rigid impacts (P = 0.0375). The impact angle was also correlated with injury risk (P < 0.00001). These experiments suggest that highly deformable, padded contact surfaces should be used carefully in environments where there is the risk for cervical spine injury. The results also suggest that the orientation of the head, neck, and torso relative to the impact surface is of equal if not greater importance in neck injury risk.

Cervical screening program and the psychological impact of an abnormal Pap smear: a self-assessment questionnaire study of 590 patients.

PubMed

Thangarajah, Fabinshy; Einzmann, Thomas; Bergauer, Florian; Patzke, Jan; Schmidt-Petruschkat, Silke; Theune, Monika; Engel, Katja; Puppe, Julian; Richters, Lisa; Mallmann, Peter; Kirn, Verena

2016-02-01

Invasive cervical cancer is today the fourth most common cancer of women in western civilization. Screening programs have led to a continuously decrease. Nevertheless, both screening and a positive test result are known to be associated with a negative psychological impact. Screening programs in European countries differ and thus psychological impact might as well. The aim of this study was to evaluate the psychological impact of women with an abnormal Pap smear in a German cohort. Between July 2013 and May 2014, a self-assessment questionnaire was distributed to 595 patients that were referred to a special clinic for cervical dysplasia for further evaluation of an abnormal Pap smear. Patients were recruited in five different centers. Most patients (45.9 %) were informed about the test result via phone call by their doctor. 68.8 % of the patients felt anxious and 26.3 % even felt panic. After having talked to their physician, 51.4 % of our cohort still felt worried and only 24.4 % felt reassured. Concerning disease management, 48.4 % underwent a control Pap smear in 6 months. The preferred information source was the physician (63.9 %). Compared to the results in other European countries, our study cohort showed differences concerning age distribution, patients living in a partnership, number of children and especially disease management. Cancer screening itself and abnormal test results have an impact on patient's feelings. To reduce the psychological impact, patients need to be better informed about the risks and benefits of cancer screening programs and in case of cervical cancer screening about the meaning of an abnormal test result. Our results underline the importance of a trustful physician-patient relationship in that matter.

Measuring the impact of complete streets projects : preliminary field testing : final report.

DOT National Transportation Integrated Search

2016-12-01

This report describes a field study that sought to assess the impact of Complete Streets (CS) projects in Buffalo, NY. Multiple data collection tools were deployed to capture a diversity of impacts on 8 street corridors where CS projects have been im...

Information Technology Diffusion: Impact on Student Achievement

ERIC Educational Resources Information Center

Lee, Gregory M.; Lind, Mary L.

2011-01-01

For student achievement, the diffusion and adoption of information technology (IT) infrastructure enabled by special funding was posited to have a positive impact on student achievement. Four urban school districts provided the context for this study to assess the impact of IT adoption on standardized test scores.

Comparison of Piezosurgery and Conventional Rotary Instruments for Removal of Impacted Mandibular Third Molars: A Randomized Controlled Clinical and Radiographic Trial

PubMed Central

Shokry, Mohamed; Aboelsaad, Nayer

2016-01-01

The purpose of this study was to test the effect of the surgical removal of impacted mandibular third molars using piezosurgery versus the conventional surgical technique on postoperative sequelae and bone healing. Material and Methods. This study was carried out as a randomized controlled clinical trial: split mouth design. Twenty patients with bilateral mandibular third molar mesioangular impaction class II position B indicated for surgical extraction were treated randomly using either the piezosurgery or the conventional bur technique on each site. Duration of the procedure, postoperative edema, trismus, pain, healing, and bone density and quantity were evaluated up to 6 months postoperatively. Results. Test and control sites were compared using paired t-test. There was statistical significance in reduction of pain and swelling in test sites, where the time of the procedure was statistically increased in test site. For bone quantity and quality, statistical difference was found where test site showed better results. Conclusion. Piezosurgery technique improves quality of patient's life in form of decrease of postoperative pain, trismus, and swelling. Furthermore, it enhances bone quality within the extraction socket and bone quantity along the distal aspect of the mandibular second molar. PMID:27597866

Gender and education impact on brain aging: a general cognitive factor approach.

PubMed

Proust-Lima, Cécile; Amieva, Hélène; Letenneur, Luc; Orgogozo, Jean-Marc; Jacqmin-Gadda, Hélène; Dartigues, Jean-François

2008-09-01

In cognitive aging research, the study of a general cognitive factor has been shown to have a substantial explanatory power over the study of isolated tests. The authors aimed at differentiating the impact of gender and education on global cognitive change with age from their differential impact on 4 psychometric tests using a new latent process approach, which intermediates between a single-factor longitudinal model for sum scores and an item-response theory approach for longitudinal data. The analysis was conducted on a sample of 2,228 subjects from PAQUID, a population-based cohort of older adults followed for 13 years with repeated measures of cognition. Adjusted for vascular factors, the analysis confirmed that women performed better in tests involving verbal components, while men performed better in tests involving visuospatial skills. In addition, the model suggested that women had a slightly steeper global cognitive decline with oldest age than men, even after excluding incident dementia or death. Subjects with higher education exhibited a better mean score for the 4 tests, but this difference tended to attenuate with age for tests involving a speed component. (c) 2008 APA, all rights reserved

Response of DP 600 products to dynamic impact loads

NASA Astrophysics Data System (ADS)

Clark, Deidra Darcell

The objective of this study was to compare the microstructural response of various DP 600 products subjected to low velocity, dynamic impact tests, typically encountered in a car crash. Since the response of steel is sensitive to its microstructure as controlled by the alloying elements, phase content, and processing; various DP 600 products may respond differently to crashes. The microstructure before and after dynamic impact deformation at 5 and 10 mph was characterized with regards to grain size, morphology, and phase content among vendors A, B, and C to evaluate efficiency in absorbing energy mechanisms during a crash simulated by dynamic impact testing in a drop tower.

Simulated hail impact testing of photovoltaic solar panels

NASA Technical Reports Server (NTRS)

Moore, D.; Wilson, A.; Ross, R.

1978-01-01

Techniques used to simulate and study the effect of hail on photovoltaic solar panels are described. Simulated hail stones (frozen ice spheres projected at terminal velocity) or steel balls were applied by air guns, gravity drop, or static loading. Tests with simulated hail and steel balls yielded different results. The impact strength of 10 commercially available flat-plate photovoltaic modules was tested. It was found that none of the six panel designs incorporating clear potting silicone material as the outermost layer remained undamaged by 1-in. simulated hailstones, while a photovoltaic module equipped with a 0.188-in.-thick acrylic cover sheet would be able to withstand the impact of a 2-in.-diameter hailstone.

Test and analysis results for composite transport fuselage and wing structures

NASA Technical Reports Server (NTRS)

Deaton, Jerry W.; Kullerd, Susan M.; Madan, Ram C.; Chen, Victor L.

1992-01-01

Automated tow placement (ATP) and stitching of dry textile composite preforms followed by resin transfer molding (RTM) are being studied as cost effective manufacturing processes for obtaining damage tolerant fuselage and wing structures for transport aircraft. Data are presented to assess the damage tolerance of ATP and RTM fuselage elements with stitched-on stiffeners from compression tests of impacted three J-stiffened panels and from stiffener pull-off tests. Data are also presented to assess the damage tolerance of RTM wing elements which had stitched skin and stiffeners from impacted single stiffener and three blade stiffened compression tests and stiffener pull-off tests.

Free Recall Enhances Subsequent Learning

PubMed Central

Arnold, Kathleen M.; McDermott, Kathleen B.

2013-01-01

Testing, or retrieval practice, has become a central topic in memory research. One potentially important effect of retrieval practice has received little attention, however: Retrieval practice may enhance, or potentiate, subsequent learning. We introduce a paradigm that can measure the indirect, potentiating effect of free recall tests on subsequent learning, and then test a hypothesis for why tests have this potentiating effect. In two experiments, the benefit of a restudy trial was enhanced when prior free recall tests had been taken. Results from a third correlational study suggest that this effect may be mediated by the effect of testing on organization. Not only do encoding conditions impact later retrievability, but also retrieval attempts impact subsequent encoding effectiveness. PMID:23297100

Georgia science curriculum alignment and accountability: A blueprint for student success

NASA Astrophysics Data System (ADS)

Reining-Gray, Kimberly M.

Current trends and legislation in education indicate an increased dependency on standardized test results as a measure for learner success. This study analyzed test data in an effort to assess the impact of curriculum alignment on learner success as well as teacher perceptions of the changes in classroom instruction due to curriculum alignment. Qualitative and quantitative design methods were used to determine the impact of science curriculum alignment in grades 9-12. To determine the impact of science curriculum alignment from the Quality Core Curriculum (QCC) to the Georgia Performance Standards (GPS) test data and teacher opinion surveys from one Georgia School system were examined. Standardized test scores before and after curriculum alignment were analyzed as well as teacher perception survey data regarding the impact of curriculum change. A quantitative teacher perception survey was administered to science teachers in the school system to identify significant changes in teacher perceptions or teaching strategies following curriculum realignment. Responses to the survey were assigned Likert scale values for analysis purposes. Selected teachers were also interviewed using panel-approved questions to further determine teacher opinions of curriculum realignment and the impact on student success and teaching strategies. Results of this study indicate significant changes related to curriculum alignment. Teachers reported a positive change in teaching strategies and instructional delivery as a result of curriculum alignment and implementation. Student scores also showed improvement, but more research is recommended in this area.

Development of a head impact monitoring "Intelligent Mouthguard".

PubMed

Hedin, Daniel S; Gibson, Paul L; Bartsch, Adam J; Samorezov, Sergey

2016-08-01

The authors present the development and laboratory system-level testing of an impact monitoring "Intelligent Mouthguard" intended to help with identification of potentially concussive head impacts and cumulative head impact dosage. The goal of Intelligent Mouthguard is to provide an indicator of potential concussion risk, and help caregiver identify athletes needing sideline concussion protocol testing. Intelligent Mouthguard may also help identify individuals who are at higher risk based on historical dosage. Intelligent Mouthguard integrates inertial sensors to provide 3-degree of freedom linear and rotational kinematics. The electronics are fully integrated into a custom mouthguard that couples tightly to the upper teeth. The combination of tight coupling and highly accurate sensor data means the Intelligent Mouthguard meets the National Football League (NFL) Level I validity specification based on laboratory system-level test data presented in this study.

Evaluation of the internal and external biofidelity of current rear impact ATDs to response targets developed from moderate-speed rear impacts of PMHS.

PubMed

Moorhouse, Kevin; Donnelly, Bruce; Kang, Yun-Seok; Bolte, John H; Herriott, Rodney

2012-10-01

The goal of this study is to evaluate both the internal and external biofidelity of existing rear impact anthropomorphic test devices (BioRID II, RID3D, Hybrid III 50th) in two moderate-speed rear impact sled test conditions (8.5g, 17 km/h; 10.5g, 24 km/h) by quantitatively comparing the ATD responses to biomechanical response targets developed from PMHS testing in a corresponding study. The ATDs and PMHS were tested in an experimental seat system that is capable of simulating the dynamic seat back rotation response of production seats. The experimental seat contains a total of fourteen load cells installed such that external loads from the ATDs and PMHS can be measured to evaluate external biofidelity. The PMHS were instrumented to correspond to the instrumentation contained in the ATDs so that direct comparison between ATDs and PMHS could be made to evaluate internal biofidelity. The NHTSA Biofidelity Ranking system was used to quantitatively evaluate the biofidelity of the ATDs and an additional tool was introduced and utilized which allows for the biofidelity score to be partitioned into components of amplitude, phase, and shape. For internal biofidelity, the BioRID II and RID3D were more biofidelic than the Hybrid III in the 17 km/h test, and the BioRID II was most biofidelic in the 24 km/h test. For external biofidelity, the BioRID II was most biofidelic in the 17 km/h test, while both the BioRID II and the RID3D were more biofidelic than the Hybrid III in the 24 km/h test. Overall, the BioRID II demonstrated the best biofidelity in both the 17 km/h and 24 km/h tests.

A Study on the Mechanical Properties and Impact-Induced Initiation Characteristics of Brittle PTFE/Al/W Reactive Materials.

PubMed

Ge, Chao; Maimaitituersun, Wubuliaisan; Dong, Yongxiang; Tian, Chao

2017-04-26

Polytetrafluoroethylene/aluminum/tungsten (PTFE/Al/W) reactive materials of three different component mass ratios (73.5/26.5/0, 68.8/24.2/7 and 63.6/22.4/14) were studied in this research. Different from the PTFE/Al/W composites published elsewhere, the materials in our research were fabricated under a much lower sintering temperature and for a much shorter duration to achieve a brittle property, which aims to provide more sufficient energy release upon impact. Quasi-static compression tests, dynamic compression tests at room and elevated temperatures, and drop weight tests were conducted to evaluate the mechanical and impact-induced initiation characteristics of the materials. The materials before and after compression tests were observed by a scanning electron microscope to relate the mesoscale structural characteristics to their macro properties. All the three types of materials fail at very low strains during both quasi-static and dynamic compression. The stress-strain curves for quasi-static tests show obvious deviations while that for the dynamic tests consist of only linear-elastic and failure stages typically. The materials were also found to exhibit thermal softening at elevated temperatures and were strain-rate sensitive during dynamic tests, which were compared using dynamic increase factors (DIFs). Drop-weight test results show that the impact-initiation sensitivity increases with the increase of W content due to the brittle mechanical property. The high-speed video sequences and recovered sample residues of the drop-weight tests show that the reaction is initiated at two opposite positions near the edges of the samples, where the shear force concentrates the most intensively, indicating a shear-induced initiation mechanism.

A Study on the Mechanical Properties and Impact-Induced Initiation Characteristics of Brittle PTFE/Al/W Reactive Materials

PubMed Central

Ge, Chao; Maimaitituersun, Wubuliaisan; Dong, Yongxiang; Tian, Chao

2017-01-01

Polytetrafluoroethylene/aluminum/tungsten (PTFE/Al/W) reactive materials of three different component mass ratios (73.5/26.5/0, 68.8/24.2/7 and 63.6/22.4/14) were studied in this research. Different from the PTFE/Al/W composites published elsewhere, the materials in our research were fabricated under a much lower sintering temperature and for a much shorter duration to achieve a brittle property, which aims to provide more sufficient energy release upon impact. Quasi-static compression tests, dynamic compression tests at room and elevated temperatures, and drop weight tests were conducted to evaluate the mechanical and impact-induced initiation characteristics of the materials. The materials before and after compression tests were observed by a scanning electron microscope to relate the mesoscale structural characteristics to their macro properties. All the three types of materials fail at very low strains during both quasi-static and dynamic compression. The stress-strain curves for quasi-static tests show obvious deviations while that for the dynamic tests consist of only linear-elastic and failure stages typically. The materials were also found to exhibit thermal softening at elevated temperatures and were strain-rate sensitive during dynamic tests, which were compared using dynamic increase factors (DIFs). Drop-weight test results show that the impact-initiation sensitivity increases with the increase of W content due to the brittle mechanical property. The high-speed video sequences and recovered sample residues of the drop-weight tests show that the reaction is initiated at two opposite positions near the edges of the samples, where the shear force concentrates the most intensively, indicating a shear-induced initiation mechanism. PMID:28772812

LEARNING AND MEMORY TESTS IN DEVELOPMENTAL NEUROTOXICITY TESTING: A CROSS-LABORATORY COMPARISON OF CONTROL DATA.

EPA Science Inventory

The US EPA Developmental Neurotoxicity (DNT) Study Test Guideline (OPPTS 870.6300) calls for functional tests to assess the impact of chemicals on cognitive function in offspring following maternal exposure. A test of associative learning and memory is to be conducted around th...

A combined CFD-experimental method for developing an erosion equation for both gas-sand and liquid-sand flows

NASA Astrophysics Data System (ADS)

Mansouri, Amir

The surface degradation of equipment due to consecutive impacts of abrasive particles carried by fluid flow is called solid particle erosion. Solid particle erosion occurs in many industries including oil and gas. In order to prevent abrupt failures and costly repairs, it is essential to predict the erosion rate and identify the locations of the equipment that are mostly at risk. Computational Fluid Dynamics (CFD) is a powerful tool for predicting the erosion rate. Erosion prediction using CFD analysis includes three steps: (1) obtaining flow solution, (2) particle tracking and calculating the particle impact speed and angle, and (3) relating the particle impact information to mass loss of material through an erosion equation. Erosion equations are commonly generated using dry impingement jet tests (sand-air), since the particle impact speed and angle are assumed not to deviate from conditions in the jet. However, in slurry flows, a wide range of particle impact speeds and angles are produced in a single slurry jet test with liquid and sand particles. In this study, a novel and combined CFD/experimental method for developing an erosion equation in slurry flows is presented. In this method, a CFD analysis is used to characterize the particle impact speed, angle, and impact rate at specific locations on the test sample. Then, the particle impact data are related to the measured erosion depth to achieve an erosion equation from submerged testing. Traditionally, it was assumed that the erosion equation developed based on gas testing can be used for both gas-sand and liquid-sand flows. The erosion equations developed in this work were implemented in a CFD code, and CFD predictions were validated for various test conditions. It was shown that the erosion equation developed based on slurry tests can significantly improve the local thickness loss prediction in slurry flows. Finally, a generalized erosion equation is proposed which can be used to predict the erosion rate in gas-sand, water-sand and viscous liquid-sand flows with high accuracy. Furthermore, in order to gain a better understanding of the erosion mechanism, a comprehensive experimental study was conducted to investigate the important factors influencing the erosion rate in gas-sand and slurry flows. The wear pattern and total erosion ratio were measured in a direct impingement jet geometry (for both dry impact and submerged impingement jets). The effects of fluid viscosity, abrasive particle size, particle impact speed, jet inclination angle, standoff distance, sand concentration, and exposure time were investigated. Also, the eroded samples were studied with Scanning Electron Microscopy (SEM) to understand the erosion micro-structure. Also, the sand particle impact speed and angle were measured using a Particle Image Velocimetry (PIV) system. The measurements were conducted in two types of erosion testers (gas-solid and liquid-solid impinging jets). The Particle Tracking Velocimetry (PTV) technique was utilized which is capable of tracking individual small particles. Moreover, CFD modeling was performed to predict the particle impact data. Very good agreement between the CFD results and PTV measurements was observed.

A Prospective, Longitudinal Study of the Impact of GJB2/GJB6 Genetic Testing on the Beliefs and Attitudes of Parents of Deaf and Hard-of-Hearing Infants

PubMed Central

Palmer, Christina G.S.; Martinez, Ariadna; Fox, Michelle; Zhou, Jin; Shapiro, Nina; Sininger, Yvonne; Grody, Wayne W.; Schimmenti, Lisa A.

2010-01-01

There are limited data on the impact of incorporating genetic counseling and testing into the newborn hearing screening process. We report on results from a prospective, longitudinal study to determine the impact of genetic counseling and GJB2/GJB6 genetic testing on parental knowledge, attitudes, and beliefs about genetic testing. One hundred thirty culturally hearing parents of 93 deaf or hard-of-hearing children ages 0 – 3 years primarily identified through newborn hearing screening received pre- and post-test genetic counseling for GJB2 and GJB6. Parents completed questionnaires following pre-test counseling, and 1- and 6-months post-test result disclosure. Results indicate that following pre-test counseling all parents perceived benefits to genetic testing. While parents who received positive results continued to perceive benefits from testing, perceived benefit declined among parents who received inconclusive or negative results. Parents did not perceive genetic testing as harmful following pre-test counseling or receipt of test results. Parents who received positive test results performed better in understanding recurrence and causation of their child’s deafness and indicated greater interest in prenatal genetic testing than those who received inconclusive or negative test results. Parents felt that pediatricians and audiologists should inform parents of genetic testing availability; however, there was no consensus on timing of this discussion. Thus culturally hearing parents do not perceive genetic testing of their deaf or hard-of-hearing infants/toddlers as harmful; they feel that primary care providers should discuss genetic testing with them; and positive genetic test results with genetic counseling give rise to better understanding and perceived benefit than negative or inconclusive results. PMID:19449415

A prospective, longitudinal study of the impact of GJB2/GJB6 genetic testing on the beliefs and attitudes of parents of deaf and hard-of-hearing infants.

PubMed

Palmer, Christina G S; Martinez, Ariadna; Fox, Michelle; Zhou, Jin; Shapiro, Nina; Sininger, Yvonne; Grody, Wayne W; Schimmenti, Lisa A

2009-06-01

There are limited data on the impact of incorporating genetic counseling and testing into the newborn hearing screening process. We report on results from a prospective, longitudinal study to determine the impact of genetic counseling and GJB2/GJB6 genetic testing on parental knowledge, attitudes, and beliefs about genetic testing. One hundred thirty culturally hearing parents of 93 deaf or hard-of-hearing children ages 0-3 years primarily identified through newborn hearing screening received pre- and post-test genetic counseling for GJB2 and GJB6. Parents completed questionnaires following pre-test counseling, and 1- and 6-month post-test result disclosure. Results indicate that following pre-test counseling all parents perceived benefits to genetic testing. While parents who received positive results continued to perceive benefits from testing, perceived benefit declined among parents who received inconclusive or negative results. Parents did not perceive genetic testing as harmful following pre-test counseling or receipt of test results. Parents who received positive test results performed better in understanding recurrence and causation of their child's deafness and indicated greater interest in prenatal genetic testing than those who received inconclusive or negative test results. Parents felt that pediatricians and audiologists should inform parents of genetic testing availability; however, there was no consensus on timing of this discussion. Thus culturally hearing parents do not perceive genetic testing of their deaf or hard-of-hearing infants/toddlers as harmful; they feel that primary care providers should discuss genetic testing with them; and positive genetic test results with genetic counseling give rise to better understanding and perceived benefit than negative or inconclusive results. (c) 2009 Wiley-Liss, Inc.

Deaf Adults' Reasons for Genetic Testing Depend on Cultural Affiliation: Results from a Prospective, Longitudinal Genetic Counseling and Testing Study

ERIC Educational Resources Information Center

Boudreault, Patrick; Baldwin, Erin E.; Fox, Michelle; Dutton, Loriel; Tullis, LeeElle; Linden, Joyce; Kobayashi, Yoko; Zhou, Jin; Sinsheimer, Janet S.; Sininger, Yvonne; Grody, Wayne W.; Palmer, Christina G. S.

2010-01-01

This article examines the relationship between cultural affiliation and deaf adults' motivations for genetic testing for deafness in the first prospective, longitudinal study to examine the impact of genetic counseling and genetic testing on deaf adults and the deaf community. Participants (n = 256), classified as affiliating with hearing, Deaf,…

Heading Frequency Is More Strongly Related to Cognitive Performance Than Unintentional Head Impacts in Amateur Soccer Players.

PubMed

Stewart, Walter F; Kim, Namhee; Ifrah, Chloe; Sliwinski, Martin; Zimmerman, Molly E; Kim, Mimi; Lipton, Richard B; Lipton, Michael L

2018-01-01

Compared to heading, unintentional head impacts (e.g., elbow to head, head to head, head to goalpost) in soccer are more strongly related to risk of moderate to very severe Central Nervous System (CNS) symptoms. But, most head impacts associated with CNS symptoms that occur in soccer are mild and are more strongly related to heading. We tested for a differential relation of heading and unintentional head impacts with neuropsychological (NP) test performance. Active adult amateur soccer players were recruited in New York City and the surrounding areas for this repeated measures longitudinal study of individuals who were enrolled if they had 5+ years of soccer play and were active playing soccer 6+ months/year. All participants completed a baseline validated questionnaire ("HeadCount-2w"), reporting 2-week recall of soccer activity, heading and unintentional head impacts. In addition, participants also completed NP tests of verbal learning, verbal memory, psychomotor speed, attention, and working memory. Most participants also completed one or more identical follow-up protocols (i.e., HeadCount-2w and NP tests) at 3- to 6-month intervals over a 2-year period. Repeated measures General Estimating Equations (GEE) linear models were used to determine if variation in NP tests at each visit was related to variation in either heading or unintentional head impacts in the 2-week period before testing. 308 players (78% male) completed 741 HeadCount-2w. Mean (median) heading/2-weeks was 50 (17) for men and 26 (7) for women. Heading was significantly associated with poorer performance on psychomotor speed ( p  < 0.001) and attention ( p  = 0.02) tasks and was borderline significant with poorer performance on the working memory ( p  = 0.06) task. Unintentional head impacts were not significantly associated with any NP test. Results did not differ after excluding 22 HeadCount-2w with reported concussive or borderline concussive symptoms. Poorer NP test performance was consistently related to frequent heading during soccer practice and competition in the 2 weeks before testing. In contrast, unintentional head impacts incurred during soccer were not related to cognitive performance.

'Isn't it ironic?' Beliefs about the unacceptability of emotions and emotional suppression relate to worse outcomes in fibromyalgia.

PubMed

Bowers, Hannah; Wroe, Abigail L; Pincus, Tamar

2017-05-01

Beliefs about the unacceptability of experiencing and expressing emotions have been found to be related to worse outcomes in people with persistent physical symptoms. The current study tested mediation models regarding emotional suppression, beliefs about emotions, support-seeking and global impact in fibromyalgia. One hundred eighty-two participants took part in an online questionnaire testing potential mechanisms of this relationship using mediation analysis. The model tested emotional suppression and affective distress as serial mediators of the relationship between beliefs about emotions and global impact. In parallel paths, two forms of support-seeking were tested (personal/emotional and symptom-related support-seeking) as mediators. Emotional suppression and affective distress significantly serially mediated the relationship between beliefs about emotions and global impact. Neither support-seeking variable significantly mediated this relationship. Results indicate a potential mechanism through which beliefs about emotions and global impact might relate which might provide a theoretical basis for future research on treatments for fibromyalgia.

Landing impact studies of a 0.3-scale model air cushion landing system for a Navy fighter airplane

NASA Technical Reports Server (NTRS)

Leland, T. J. W.; Thompson, W. C.

1975-01-01

An experimental study was conducted in order to determine the landing-impact behavior of a 0.3-scale, dynamically (but not physically) similar model of a high-density Navy fighter equipped with an air cushion landing system. The model was tested over a range of landing contact attitudes at high forward speeds and sink rates on a specialized test fixture at the Langley aircraft landing loads and traction facility. The investigation indicated that vertical acceleration at landing impact was highly dependent on the pitch angle at ground contact, the higher acceleration of approximately 5g occurring near zero body-pitch attitude. A limited number of low-speed taxi tests were made in order to determine model stability characteristics. The model was found to have good pitch-damping characteristics but stability in roll was marginal.

The psychological impact of genetic testing on parents.

PubMed

Dinc, Leyla; Terzioglu, Fusun

2006-01-01

The aim of this descriptive study was to explore the psychological impact of genetic testing on parents whose children have been referred for genetic testing. Genetic tests enable individuals to be informed about their health status and to have the opportunity of early diagnosis and treatment of their diseases. However undergoing genetic testing and receiving a positive test result may also cause stress and anxiety. This descriptive study was carried out at the genetic departments of two university hospitals in Ankara. The sample of this study consisted of 128 individuals whose children have been referred for chromosomal analysis. Data were collected through using a semi-structured interview method with a data collection form and the anxiety inventory and analysed using the percentages and independent samples t-test. The majority of our participants experienced distress before genetic testing. Their general trait anxiety score before receiving the test results was 47.38, and following the test results the state anxiety score was 50.65. Having a previous child with an abnormality, a positive test result, and being a mother elevated the anxiety of individuals. This paper supports the findings of previous studies, which indicated that genetic test results might lead to anxiety in individuals and reveals the importance of genetic counselling. As the results of this study indicated, genetic testing causes distress and anxiety in individuals. Nurses can play an important role in minimizing anxiety of parents whose children undergo genetic testing by providing information about genetic testing and by taking part in the counselling process.

The Impact of Academic Vocabulary Instruction on Reading Performance of Sophomore Students on the Florida Comprehensive Assessment Test from 2008 and 2009

ERIC Educational Resources Information Center

McMillen, Margaret

2009-01-01

This study investigated the change in sophomore reading scores on the Florida Comprehensive Assessment Test after the implementation of an academic vocabulary program and the change in teacher knowledge and professional practice after a program of staff development in academic vocabulary. The purpose was to determine if the impact of the…

The Impact of Year-Round Education on Fifth Grade African American Reading Achievement Scores in an Urban Illinois School

ERIC Educational Resources Information Center

Merrill, Carolyn Ann

2012-01-01

The purpose of this quantitative, causal-comparative study was to determine the impact of the year-round education school calendar on the standardized test performance of fifth grade African American students, as measured by the Illinois Standards Achievement Test (ISAT) in reading. The ISAT reading scores from two year-round education (YRE)…

The Impact of the Flynn Effect on LD Diagnoses in Special Education

ERIC Educational Resources Information Center

Kanaya, Tomoe; Ceci, Stephen

2012-01-01

Because of the Flynn effect, IQ scores rise as a test norm ages but drop on the introduction of a newly revised test norm. The purpose of the current study was to determine the impact of the Flynn effect on learning disability (LD) diagnoses, the most prevalent special education diagnosis in the United States. Using a longitudinal sample of 875…

A modified correlation between KJIC and Charpy V-notch impact energy of Chinese SA508-III steel at the upper shelf

NASA Astrophysics Data System (ADS)

Li, Xiangqing; Song, Yuxuan; Ding, Zhenyu; Bao, Shiyi; Gao, Zengliang

2018-07-01

The fracture toughness plays a significant role in the structural integrity assessment of reactor pressure vessels (RPVs) in service temperature. The Charpy V-notch (CVN) impact test is used to estimate fracture toughness (KIC or KJIC) indirectly since universal fracture toughness tests are costly, sophisticated and frequently invalid. In this study, a modified correlation which based on the typical model of KJIC-CVN at the upper shelf was established for Chinese SA508-III steel. Thereinto, the effect of test temperature (T) was directly considered in the correlation. To assess the accuracy of fracture toughness when calculating from the value of Charpy-V notch impact energy by using the modified correlation, both the Charpy-V notch impact tests and fracture toughness tests for Chinese SA508-III steel were conducted at different temperatures (100 °C, 150 °C, 200 °C, 250 °C and 320 °C). The results showed that the modified correlation exhibited the high precision for estimating fracture toughness of Chinese SA508-III steel and the relative error for tested and estimated results is within 8%, which is lower than that of other correlations.

A qualitative exploration of student perceptions of the impact of progress tests on learning and emotional wellbeing.

PubMed

Yielder, Jill; Wearn, Andy; Chen, Yan; Henning, Marcus A; Weller, Jennifer; Lillis, Steven; Mogol, Vernon; Bagg, Warwick

2017-08-29

Progress testing was introduced to the MBChB programme at the University of Auckland in 2013. As there has been a focus in published literature on aspects relating to the format or function of progress tests, the purpose of this study was to explore a qualitative student perspective on the introduction of progress testing and its impact on approaches to learning and perceived stress. This article presents the qualitative aspects of a longitudinal evaluation study. The qualitative data were derived from eight focus groups of Year 2-5 medical students in the University of Auckland medical programme. Two themes, 'Impact on Learning' and 'Emotional Wellbeing' and their subthemes offered insight into student perceptions and behaviour. Students described a variety of learning responses to progress testing that clustered around the employment of a range of learning strategies based on their experience of sitting progress tests and their individualised feedback. A range of emotional responses were also expressed, with some finding progress tests stressful, while others enjoyed not needing to intensively cram before the tests. Progress tests appear to influence the approach of students to their learning. They employ a mix of learning strategies, shaped by their performance, individualised feedback and the learning environment. While students expressed some stress and anxiety with respect to sitting progress tests, this form of testing was viewed by these students as no worse, and sometimes better than traditional assessments.

The effect of the impactor diameter and temperature on low velocity impact behavior of CFRP laminates

NASA Astrophysics Data System (ADS)

Evci, C.; Uyandıran, I.

2017-02-01

Impact damage is one of the major concerns that should be taken into account with the new aircraft and spacecraft structures which employ ever-growing use of composite materials. Considering the thermal loads encountered at different altitudes, both low and high temperatures can affect the properties and impact behavior of composite materials. This study aims to investigate the effect of temperature and impactor diameter on the impact behavior and damage development in balanced and symmetrical CFRP laminates which were manufactured by employing vacuum bagging process with autoclave cure. Instrumented drop-weight impact testing system is used to perform the low velocity impact tests in a range of temperatures ranged from 60 down to -50 °C. Impact tests for each temperature level were conducted using three different hemispherical impactor diameters varying from 10 to 20 mm. Energy profile method is employed to determine the impact threshold energies for damage evolution. The level of impact damage is determined from the dent depth on the impacted face and delamination damage detected using ultrasonic C-Scan technique. Test results reveal that the threshold of penetration energy, main failure force and delamination area increase with impactor diameter at all temperature levels. No clear influence of temperature on the critical force thresholds could be derived. However, penetration threshold energy decreased as the temperature was lowered. Drop in the penetration threshold was more obvious with quite low temperatures. Delamination damage area increased while the temperature decreased from +60 °C to -50 °C.

Practicing Accounting Profession Criterial Skills in the Classroom: A Study of Collaborative Testing and the Impact on Final Exam Scores

ERIC Educational Resources Information Center

VanderLaan, Ski R.

2010-01-01

This mixed methods study (Creswell, 2008) was designed to test the influence of collaborative testing on learning using a quasi-experimental approach. This study used a modified embedded mixed method design in which the qualitative and quantitative data, associated with the secondary questions, provided a supportive role in a study based primarily…

Southern Impact Testing Alliance (SITA)

NASA Technical Reports Server (NTRS)

Hubbs, Whitney; Roebuck, Brian; Zwiener, Mark; Wells, Brian

2009-01-01

Efforts to form this Alliance began in 2008 to showcase the impact testing capabilities within the southern United States. Impact testing customers can utilize SITA partner capabilities to provide supporting data during all program phases-materials/component/ flight hardware design, development, and qualification. This approach would allow programs to reduce risk by providing low cost testing during early development to flush out possible problems before moving on to larger scale1 higher cost testing. Various SITA partners would participate in impact testing depending on program phase-materials characterization, component/subsystem characterization, full-scale system testing for qualification. SITA partners would collaborate with the customer to develop an integrated test approach during early program phases. Modeling and analysis validation can start with small-scale testing to ensure a level of confidence for the next step large or full-scale conclusive test shots. Impact Testing Facility (ITF) was established and began its research in spacecraft debris shielding in the early 1960's and played a malor role in the International Space Station debris shield development. As a result of return to flight testing after the loss of STS-107 (Columbia) MSFC ITF realized the need to expand their capabilities beyond meteoroid and space debris impact testing. MSFC partnered with the Department of Defense and academic institutions as collaborative efforts to gain and share knowledge that would benefit the Space Agency as well as the DoD. MSFC ITF current capabilities include: Hypervelocity impact testing, ballistic impact testing, and environmental impact testing.

Study of Impact Damage in PVA-ECC Beam under Low-Velocity Impact Loading Using Piezoceramic Transducers and PVDF Thin-Film Transducers.

PubMed

Qi, Baoxin; Kong, Qingzhao; Qian, Hui; Patil, Devendra; Lim, Ing; Li, Mo; Liu, Dong; Song, Gangbing

2018-02-24

Compared to conventional concrete, polyvinyl alcohol fiber reinforced engineering cementitious composite (PVA-ECC) offers high-strength, ductility, formability, and excellent fatigue resistance. However, impact-induced structural damage is a major concern and has not been previously characterized in PVA-ECC structures. We investigate the damage of PVA-ECC beams under low-velocity impact loading. A series of ball-drop impact tests were performed at different drop weights and heights to simulate various impact energies. The impact results of PVA-ECC beams were compared with mortar beams. A combination of polyvinylidene fluoride (PVDF) thin-film sensors and piezoceramic-based smart aggregate were used for impact monitoring, which included impact initiation and crack evolution. Short-time Fourier transform (STFT) of the signal received by PVDF thin-film sensors was performed to identify impact events, while active-sensing approach was utilized to detect impact-induced crack evolution by the attenuation of a propagated guided wave. Wavelet packet-based energy analysis was performed to quantify failure development under repeated impact tests.

Study of Impact Damage in PVA-ECC Beam under Low-Velocity Impact Loading Using Piezoceramic Transducers and PVDF Thin-Film Transducers

PubMed Central

Qian, Hui; Li, Mo; Liu, Dong; Song, Gangbing

2018-01-01

Compared to conventional concrete, polyvinyl alcohol fiber reinforced engineering cementitious composite (PVA-ECC) offers high-strength, ductility, formability, and excellent fatigue resistance. However, impact-induced structural damage is a major concern and has not been previously characterized in PVA-ECC structures. We investigate the damage of PVA-ECC beams under low-velocity impact loading. A series of ball-drop impact tests were performed at different drop weights and heights to simulate various impact energies. The impact results of PVA-ECC beams were compared with mortar beams. A combination of polyvinylidene fluoride (PVDF) thin-film sensors and piezoceramic-based smart aggregate were used for impact monitoring, which included impact initiation and crack evolution. Short-time Fourier transform (STFT) of the signal received by PVDF thin-film sensors was performed to identify impact events, while active-sensing approach was utilized to detect impact-induced crack evolution by the attenuation of a propagated guided wave. Wavelet packet-based energy analysis was performed to quantify failure development under repeated impact tests. PMID:29495277

Comparison of shock transmission and forearm electromyography between experienced and recreational tennis players during backhand strokes.

PubMed

Wei, Shun-Hwa; Chiang, Jinn-Yen; Shiang, Tzyy-Yuang; Chang, Hsiao-Yun

2006-03-01

To test the hypothesis that recreational tennis players transmit more shock impact from the racket to the elbow joint than experienced tennis players during the backhand stroke. Also, to test whether recreational tennis players used higher electromyographic (EMG) activities in common wrist extensor and flexor around epicondylar region at follow-through phase. A repeated-measure, cross-sectional study. National College of Physical Education and Sports at Taipei, Taiwan. Twenty-four male tennis players with no abnormal forearm musculoskeletal injury participated in the study. According to performance level, subjects were categorized into 2 groups: experienced and recreational. Impact transmission and wrist extensor-flexor EMG for backhand acceleration, impact, and follow-through phases were recorded for each player. An independent t test with a significance level of 0.05 was used to examine mean differences of shock impact and EMG between the 2 test groups. One-way ANOVA associated with Tukey multiple comparisons was used to identify differences among different impact locations and EMG phases. Experienced athletes reduced the racket impact to the elbow joint by 89.2%, but recreational players reduced it by only 61.8%. The largest EMG differences were found in the follow-through phase (P<0.05). Experienced athletes showed that their extensor and flexor EMGs were at submaximal level for follow-through phase, whereas recreational players maintained their flexor and extensor EMGs at either supramaximal or maximal level. Our results support the hypothesis that recreational players transmit more shock impact from the racket to the elbow joint and use larger wrist flexor and extensor EMG activities at follow-through phase of the backhand stroke. Follow-through control is proposed as a critical factor for reduction of shock transmission. Clinicians or trainers should instruct beginners to quickly release their grip tightness after ball-to-racket impact to reduce shock impact transmission to the wrist and elbow.

Energy attenuation performance of impact protection worn by motorcyclists in real-world crashes.

PubMed

Albanese, Bianca; Gibson, Tom; Whyte, Tom; Meredith, Lauren; Savino, Giovanni; de Rome, Liz; Baldock, Matthew; Fitzharris, Michael; Brown, Julie

2017-05-29

Laboratory studies have demonstrated that impact protectors (IP) used in motorcycle clothing can reduce fracture severities. While crash studies have reported IP are associated with reduced likelihood of soft tissue injury, there is little evidence of their effectiveness in reducing fracture likelihood. This discrepancy might be related to IP quality. There are mandatory requirements for IP supplied with protective clothing in Europe, but not elsewhere. This study examines the energy attenuation performance of IP used by Australian riders. IP were harvested from clothing worn by crashed riders admitted to hospital. The IP were examined and energy attenuation properties were determined using EN 1621-1 test procedures. Impact injury was identified from medical records and defined as fractures, dislocations, and avulsions that occurred following impact to the rider's shoulders, elbows, hips, and/or knees. Fisher's exact test was used to examine the relationship between meeting the EN 1621-1 energy attenuation requirements and impact injury. The association between the average and maximum transmitted force, and impact injury was examined using generalized estimating equations. Motorcycle riders were recruited as part of an in-depth crash study through three hospitals in New South Wales, Australia, between 2012 and 2014. Riders were interviewed, and engineers conducted site, vehicle, and clothing inspections. Clothing was collected, or identical garments were purchased. Clothing was inspected for 62 riders. Of these, 19 wore clothing incorporating 76 IP. Twenty-six of these were impacted in the crash event. Almost all impacted IP (96%) were CE marked, and most (83%) met Level 1 energy attenuation requirements of EN 1621-1 when tested. Of the 26 impacted IP, four were associated with impact injuries, including midshaft and distal clavicle fractures and a scapula and olecranon fracture. No associations between meeting EN 1621-1 requirements and impact injury were found (p = 0.5). There was no association between average force transmitted and impact injury (95% CI: 0.91-1.24); however, as maximum force transmitted increased, the odds of impact injury increased (95% CI: 1.01-1.2). These results indicate a high probability of impact injury at 50 kN, the limit of maximum transmitted force specified in EN 1621-1. The allowable transmitted force of EN 1621-1 may be too high to effectively reduce the probability of impact injury. This is not surprising, given human tolerance levels that are reported in literature. Reducing the force limit below the reported fracture tolerance limits might be difficult with current technology. However, there is scope to reduce the EN 1621-1 maximum limit of 50 kN transmitted force. A reduction in the maximum force limit would improve rider protection and appears feasible, as 77% of tested IP recorded a maximum force <35 kN. This level of transmitted force is estimated to be associated with <20% probability of impact injury. While the performance of IP available to Australian riders is not regulated, most IP was CE marked. The results indicate a significant association between maximum transmitted force, tested according to EN 1621-1 procedures, and impact injury. Further investigation of the EN 1621-1 requirements may be warranted. This work will interest those targeting protective equipment for motorcyclists as a mechanism for reducing injury to these vulnerable road users.

Effect of Reinforcement Using Stainless Steel Mesh, Glass Fibers, and Polyethylene on the Impact Strength of Heat Cure Denture Base Resin - An In Vitro Study

PubMed Central

Murthy, H B Mallikarjuna; Shaik, Sharaz; Sachdeva, Harleen; Khare, Sumit; Haralur, Satheesh B; Roopa, K T

2015-01-01

Background: The impact strength of denture base resin is of great concern and many approaches have been made to strengthen acrylic resin dentures. The objective of this study was to compare the impact strength of the denture base resin with and without reinforcement and to evaluate the impact strength of denture base resin when reinforced with stainless steel mesh, glass fiber, and polyethylene fibers in the woven form. Materials and Methods: The specimens (maxillary denture bases) were fabricated using a standard polyvinylsiloxane mold with conventional heat cured polymethyl methacrylate resin. The specimens were divided into four groups (n = 10). Group I specimens or control group were not reinforced. Group II specimens were reinforced with stainless steel mesh and Group III and Group IV specimens were reinforced with three percent by weight of glass fibers and polyethylene fibers in weave form respectively. All the specimens were immersed in water for 1-week before testing. The impact strength was measured with falling weight impact testing machine. One-way analysis of variance and Tukey’s post-hoc test were used for statistical analysis. Results: Highest impact strength values were exhibited by the specimens reinforced with polyethylene fibers followed by glass fibers, stainless steel mesh, and control group. Conclusions: Reinforcement of maxillary complete dentures showed a significant increase in impact strength when compared to unreinforced dentures. Polyethylene fibers exhibit better impact strength followed by glass fibers and stainless steel mesh. By using pre-impregnated glass and polyethylene fibers in woven form (prepregs) the impact strength of the denture bases can be increased effectively. PMID:26124604

Impact Landing Dynamics Facility Crash Test

NASA Image and Video Library

1975-08-03

Photographed on: 08/03/75. -- By 1972 the Lunar Landing Research Facility was no longer in use for its original purpose. The 400-foot high structure was swiftly modified to allow engineers to study the dynamics of aircraft crashes. "The Impact Dynamics Research Facility is used to conduct crash testing of full-scale aircraft under controlled conditions. The aircraft are swung by cables from an A-frame structure that is approximately 400 ft. long and 230 foot high. The impact runway can be modified to simulate other grand crash environments, such as packed dirt, to meet a specific test requirement." "In 1972, NASA and the FAA embarked on a cooperative effort to develop technology for improved crashworthiness and passenger survivability in general aviation aircraft with little or no increase in weight and acceptable cost. Since then, NASA has "crashed" dozens of GA aircraft by using the lunar excursion module (LEM) facility originally built for the Apollo program." This photograph shows Crash Test No. 7. Crash Test: Test #7

Arcjet Testing of Micro-Meteoroid Impacted Thermal Protection Materials

NASA Technical Reports Server (NTRS)

Agrawal, Parul; Munk, Michelle M.; Glaab, Louis J.

2013-01-01

There are several harsh space environments that could affect thermal protection systems and in turn pose risks to the atmospheric entry vehicles. These environments include micrometeoroid impact, extreme cold temperatures, and ionizing radiation during deep space cruise, all followed by atmospheric entry heating. To mitigate these risks, different thermal protection material samples were subjected to multiple tests, including hyper velocity impact, cold soak, irradiation, and arcjet testing, at various NASA facilities that simulated these environments. The materials included a variety of honeycomb packed ablative materials as well as carbon-based non-ablative thermal protection systems. The present paper describes the results of the multiple test campaign with a focus on arcjet testing of thermal protection materials. The tests showed promising results for ablative materials. However, the carbon-based non-ablative system presented some concerns regarding the potential risks to an entry vehicle. This study provides valuable information regarding the capability of various thermal protection materials to withstand harsh space environments, which is critical to sample return and planetary entry missions.

Perceptions and performance using computer-based testing: One institution's experience.

PubMed

Bloom, Timothy J; Rich, Wesley D; Olson, Stephanie M; Adams, Michael L

2018-02-01

The purpose of this study was to evaluate student and faculty perceptions of the transition to a required computer-based testing format and to identify any impact of this transition on student exam performance. Separate questionnaires sent to students and faculty asked about perceptions of and problems with computer-based testing. Exam results from program-required courses for two years prior to and two years following the adoption of computer-based testing were compared to determine if this testing format impacted student performance. Responses to Likert-type questions about perceived ease of use showed no difference between students with one and three semesters experience with computer-based testing. Of 223 student-reported problems, 23% related to faculty training with the testing software. Students most commonly reported improved feedback (46% of responses) and ease of exam-taking (17% of responses) as benefits to computer-based testing. Faculty-reported difficulties were most commonly related to problems with student computers during an exam (38% of responses) while the most commonly identified benefit was collecting assessment data (32% of responses). Neither faculty nor students perceived an impact on exam performance due to computer-based testing. An analysis of exam grades confirmed there was no consistent performance difference between the paper and computer-based formats. Both faculty and students rapidly adapted to using computer-based testing. There was no evidence that switching to computer-based testing had any impact on student exam performance. Copyright © 2017 Elsevier Inc. All rights reserved.

Inverted drop testing and neck injury potential.

PubMed

Forrest, Stephen; Herbst, Brian; Meyer, Steve; Sances, Anthony; Kumaresan, Srirangam

2003-01-01

Inverted drop testing of vehicles is a methodology that has long been used by the automotive industry and researchers to test roof integrity and is currently being considered by the National Highway Traffic Safety Administration as a roof strength test. In 1990 a study was reported which involved 8 dolly rollover tests and 5 inverted drop tests. These studies were conducted with restrained Hybrid III instrumented Anthropometric Test Devices (ATD) in production and rollcaged vehicles to investigate the relationship between roof strength and occupant injury potential. The 5 inverted drop tests included in the study provided a methodology producing "repeatable roof impacts" exposing the ATDs to the similar impact environment as those seen in the dolly rollover tests. Authors have conducted two inverted drop test sets as part of an investigation of two real world rollover accidents. Hybrid-III ATD's were used in each test with instrumented head and necks. Both test sets confirm that reduction of roof intrusion and increased headroom can significantly enhance occupant protection. In both test pairs, the neck force of the dummy in the vehicle with less crush and more survival space was significantly lower. Reduced roof crush and dynamic preservation of the occupant survival space resulted in only minor occupant contact and minimal occupant loading, establishing a clear causal relationship between roof crush and neck injuries.

High Pressure Quick Disconnect Particle Impact Tests

NASA Technical Reports Server (NTRS)

Peralta, Stephen; Rosales, Keisa; Smith, Sarah R.; Stoltzfus, Joel M.

2007-01-01

To determine whether there is a particle impact ignition hazard in the quick disconnects (QDs) in the Environmental Control and Life Support System (ECLSS) on the International Space Station (ISS), NASA Johnson Space Center requested White Sands Test Facility (WSTF) to perform particle impact testing. Testing was performed from November 2006 through May 2007 and included standard supersonic and subsonic particle impact tests on 15-5 PH stainless steel, as well as tests performed on a QD simulator. This report summarizes the particle impact tests completed at WSTF. Although there was an ignition in Test Series 4, it was determined the ignition was caused by the presence of a machining imperfection. The sum of all the test results indicates that there is no particle impact ignition hazard in the ISS ECLSS QDs.

Response of Honeycomb Core Sandwich Panel with Minimum Gage GFRP Face-Sheets to Compression Loading After Impact

NASA Technical Reports Server (NTRS)

McQuigg, Thomas D.; Kapania, Rakesh K.; Scotti, Stephen J.; Walker, Sandra P.

2011-01-01

A compression after impact study has been conducted to determine the residual strength of three sandwich panel constructions with two types of thin glass fiber reinforced polymer face-sheets and two hexagonal honeycomb Nomex core densities. Impact testing is conducted to first determine the characteristics of damage resulting from various impact energy levels. Two modes of failure are found during compression after impact tests with the density of the core precipitating the failure mode present for a given specimen. A finite element analysis is presented for prediction of the residual compressive strength of the impacted specimens. The analysis includes progressive damage modeling in the face-sheets. Preliminary analysis results were similar to the experimental results; however, a higher fidelity core material model is expected to improve the correlation.

High velocity impact on composite link of aircraft wing flap mechanism

NASA Astrophysics Data System (ADS)

Heimbs, Sebastian; Lang, Holger; Havar, Tamas

2012-12-01

This paper describes the numerical investigation of the mechanical behaviour of a structural component of an aircraft wing flap support impacted by a wheel rim fragment. The support link made of composite materials was modelled in the commercial finite element code Abaqus/Explicit, incorporating intralaminar and interlaminar failure modes by adequate material models and cohesive interfaces. Validation studies were performed step by step using quasi-static tensile test data and low velocity impact test data. Finally, high velocity impact simulations with a metallic rim fragment were performed for several load cases involving different impact angles, impactor rotation and pre-stress. The numerical rim release analysis turned out to be an efficient approach in the development process of such composite structures and for the identification of structural damage and worst case impact loading scenarios.

Reducing stillbirths: screening and monitoring during pregnancy and labour

PubMed Central

Haws, Rachel A; Yakoob, Mohammad Yawar; Soomro, Tanya; Menezes, Esme V; Darmstadt, Gary L; Bhutta, Zulfiqar A

2009-01-01

Background Screening and monitoring in pregnancy are strategies used by healthcare providers to identify high-risk pregnancies so that they can provide more targeted and appropriate treatment and follow-up care, and to monitor fetal well-being in both low- and high-risk pregnancies. The use of many of these techniques is controversial and their ability to detect fetal compromise often unknown. Theoretically, appropriate management of maternal and fetal risk factors and complications that are detected in pregnancy and labour could prevent a large proportion of the world's 3.2 million estimated annual stillbirths, as well as minimise maternal and neonatal morbidity and mortality. Methods The fourth in a series of papers assessing the evidence base for prevention of stillbirths, this paper reviews available published evidence for the impact of 14 screening and monitoring interventions in pregnancy on stillbirth, including identification and management of high-risk pregnancies, advanced monitoring techniques, and monitoring of labour. Using broad and specific strategies to search PubMed and the Cochrane Library, we identified 221 relevant reviews and studies testing screening and monitoring interventions during the antenatal and intrapartum periods and reporting stillbirth or perinatal mortality as an outcome. Results We found a dearth of rigorous evidence of direct impact of any of these screening procedures and interventions on stillbirth incidence. Observational studies testing some interventions, including fetal movement monitoring and Doppler monitoring, showed some evidence of impact on stillbirths in selected high-risk populations, but require larger rigourous trials to confirm impact. Other interventions, such as amniotic fluid assessment for oligohydramnios, appear predictive of stillbirth risk, but studies are lacking which assess the impact on perinatal mortality of subsequent intervention based on test findings. Few rigorous studies of cardiotocography have reported stillbirth outcomes, but steep declines in stillbirth rates have been observed in high-income settings such as the U.S., where cardiotocography is used in conjunction with Caesarean section for fetal distress. Conclusion There are numerous research gaps and large, adequately controlled trials are still needed for most of the interventions we considered. The impact of monitoring interventions on stillbirth relies on use of effective and timely intervention should problems be detected. Numerous studies indicated that positive tests were associated with increased perinatal mortality, but while some tests had good sensitivity in detecting distress, false-positive rates were high for most tests, and questions remain about optimal timing, frequency, and implications of testing. Few studies included assessments of impact of subsequent intervention needed before recommending particular monitoring strategies as a means to decrease stillbirth incidence. In high-income countries such as the US, observational evidence suggests that widespread use of cardiotocography with Caesarean section for fetal distress has led to significant declines in stillbirth rates. Efforts to increase availability of Caesarean section in low-/middle-income countries should be coupled with intrapartum monitoring technologies where resources and provider skills permit. PMID:19426468

Research on resistance characteristics of YBCO tape under short-time DC large current impact

NASA Astrophysics Data System (ADS)

Zhang, Zhifeng; Yang, Jiabin; Qiu, Qingquan; Zhang, Guomin; Lin, Liangzhen

2017-06-01

Research of the resistance characteristics of YBCO tape under short-time DC large current impact is the foundation of the developing DC superconducting fault current limiter (SFCL) for voltage source converter-based high voltage direct current system (VSC-HVDC), which is one of the valid approaches to solve the problems of renewable energy integration. SFCL can limit DC short-circuit and enhance the interrupting capabilities of DC circuit breakers. In this paper, under short-time DC large current impacts, the resistance features of naked tape of YBCO tape are studied to find the resistance - temperature change rule and the maximum impact current. The influence of insulation for the resistance - temperature characteristics of YBCO tape is studied by comparison tests with naked tape and insulating tape in 77 K. The influence of operating temperature on the tape is also studied under subcooled liquid nitrogen condition. For the current impact security of YBCO tape, the critical current degradation and top temperature are analyzed and worked as judgment standards. The testing results is helpful for in developing SFCL in VSC-HVDC.

An Experimental Study of Applied Ground Loads in Landing

NASA Technical Reports Server (NTRS)

Milwitzky, Benjamin; Lindquist, Dean C; Potter, Dexter M

1955-01-01

Results are presented of an experimental investigation made of the applied ground loads and the coefficient of friction between the tire and the ground during the wheel spin-up process in impacts of a small landing gear under controlled conditions on a concrete landing strip in the Langley impact basin. The basic investigation included three major phases: impacts with forward speed at horizontal velocities up to approximately 86 feet per second, impacts with forward speed and reverse wheel rotation to simulate horizontal velocities up to about 273 feet per second, and spin-up drop tests for comparison with the other tests. In addition to the basic investigation, supplementary tests were made to evaluate the drag-load alleviating effects of prerotating the wheel before impact so as to reduce the relative velocity between the tire and ground. In the presentation of the results, an attempt has been made to interpret the experimental data so as to obtain some insight into the physical phenomena involved in the wheel spin-up process.

Normalizing and scaling of data to derive human response corridors from impact tests.

PubMed

Yoganandan, Narayan; Arun, Mike W J; Pintar, Frank A

2014-06-03

It is well known that variability is inherent in any biological experiment. Human cadavers (Post-Mortem Human Subjects, PMHS) are routinely used to determine responses to impact loading for crashworthiness applications including civilian (motor vehicle) and military environments. It is important to transform measured variables from PMHS tests (accelerations, forces and deflections) to a standard or reference population, termed normalization. The transformation process should account for inter-specimen variations with some underlying assumptions used during normalization. Scaling is a process by which normalized responses are converted from one standard to another (example, mid-size adult male to large-male and small-size female adults, and to pediatric populations). These responses are used to derive corridors to assess the biofidelity of anthropomorphic test devices (crash dummies) used to predict injury in impact environments and design injury mitigating devices. This survey examines the pros and cons of different approaches for obtaining normalized and scaled responses and corridors used in biomechanical studies for over four decades. Specifically, the equal-stress equal-velocity and impulse-momentum methods along with their variations are discussed in this review. Methods ranging from subjective to quasi-static loading to different approaches are discussed for deriving temporal mean and plus minus one standard deviation human corridors of time-varying fundamental responses and cross variables (e.g., force-deflection). The survey offers some insights into the potential efficacy of these approaches with examples from recent impact tests and concludes with recommendations for future studies. The importance of considering various parameters during the experimental design of human impact tests is stressed. Published by Elsevier Ltd.

Incendivity of some coal-cutter materials by impact-abrasion in air-methane

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

Blickensderfer, R.; Deardorff, D.K.; Kelley, J.E.

1974-01-01

Test equipment that simulated frictional impacts between coal-cutter bits and mineral inclusions at a coal face during operation of a continuous coal mining machine was used to study the incendivity of impacts between various rocks, metals, and hard-metal alloys in an explosive mixture of air-7 pct natural gas. Quartzitic sandstone was found to be the most incendive of several rocks tested. Limestone concretions from a coal seam, known locally as ''sulfur balls,'' sparked furiously but were not incendive. Among the metals tested, the type of steel used in commercial coal-cutter tools was the most incendive material tested. A 17-4PH stainlessmore » steel was less incendive and appears to be the most promising high-strength steel alloy, reasonably economical, for use in coal-cutter bits. Some hard-metal alloys, primarily titanium and zirconium diboride composites, were also evaluated as possible replacements for the conventional cobalt-bonded tungsten carbide used in the tip of coal-cutter bits. The metal-bonded diborides were generally less incendive (but more brittle) than the conventional tungsten carbide. Carbonitride coatings on tool bits were also tested but found to have no advantage. The source of ignition during frictional impact between metal and rock was studied. Immediately after impact, a yellow flash was observed and a smear of metal near its melting point occurred on the rock. This hotspot on the rock, rather than the yellow flash or sparks or metal fragments, was observed to be the cause of the ignition.« less

An experimental study of non-destructive testing on glass fibre reinforced polymer composites after high velocity impact event

NASA Astrophysics Data System (ADS)

Razali, N.; Sultan, M. T. H.; Cardona, F.

2016-10-01

A non-destructive testing method on Glass Fibre Reinforced Polymer (GFRP) after high velocity impact event using single stage gas gun (SSGG) is presented. Specimens of C- type and E-type fibreglass reinforcement, which were fabricated with 6mm, 8mm, 10mm and 12mm thicknesses and size 100 mm x 100 mm, were subjected to a high velocity impact with three types of bullets: conical, hemispherical and blunt at various gas gun pressure levels from 6 bar to 60 bar. Visual observation techniques using a lab microscope were used to determine the infringed damage by looking at the crack zone. Dye penetrants were used to inspect the area of damage, and to evaluate internal and external damages on the specimens after impact. The results from visual analysis of the impacted test laminates were discussed and presented. It was found that the impact damage started with induced delamination, fibre cracking and then failure, simultaneously with matrix cracking and breakage, and finally followed by the fibres pulled out. C-type experienced more damaged areas compared to E-type of GFRP.

Crash simulation of UNS electric vehicle under frontal front impact

NASA Astrophysics Data System (ADS)

Susilo, D. D.; Lukamana, N. I.; Budiana, E. P.; Tjahjana, D. D. D. P.

2016-03-01

Sebelas Maret University has been developing an Electric Vehicle namely SmarT-EV UNS. The main structure of the car are chasis and body. The chasis is made from steel and the body is made from fiberglass composite. To ensure the safety of the car, both static and dynamic tests were carried out to these structures, including their materials, like: tensile test, bending test, and impact test. Another test needed by this vehicle is crashworthiness test. To perform the test, it is needed complex equipments and it is quite expensive. Another way to obtain vehicle crashworthiness behaviour is by simulate it. The purpose of this study was to simulate the response of the Smart-EV UNS electric vehicle main structure when crashing rigid barrier from the front. The crash simulation was done in according to the NHTSA (National Highway Traffic Safety Administration) within the speed of the vehicle of 35 mph. The UNS Electric Vehicle was modelled using SolidWorks software, and the simulation process was done by finite element method using ANSYS software. The simulation result showed that the most internal impact energy was absorbed by chassis part. It absorbed 76.2% of impact energy, then the base absorbed 11.3 %, while the front body absorbed 2.5 %, and the rest was absorbed by fender, hood, and other parts.

Simulating the Impact Response of Full-Scale Composite Airframe Structures

NASA Technical Reports Server (NTRS)

Fasanella, Edwin L.; Jackson, Karen E.; Littell, Justin D.; Seal, Michael D.

2012-01-01

NASA Langley Research Center obtained a composite helicopter cabin structure in 2010 from the US Army's Survivable Affordable Repairable Airframe Program (SARAP) that was fabricated by Sikorsky Aircraft Corporation. The cabin had been subjected to a vertical drop test in 2008 to evaluate a tilting roof concept to limit the intrusion of overhead masses into the fuselage cabin. Damage to the cabin test article was limited primarily to the roof. Consequently, the roof area was removed and the remaining structure was cut into test specimens including a large subfloor section and a forward framed fuselage section. In 2011, NASA and Sikorsky entered into a cooperative research agreement to study the impact responses of composite airframe structures and to evaluate the capabilities of the explicit transient dynamic finite element code, LS-DYNA®, to simulate these responses including damage initiation and progressive failure. Most of the test articles were manufactured of graphite unidirectional tape composite with a thermoplastic resin system. However, the framed fuselage section was constructed primarily of a plain weave graphite fabric material with a thermoset resin system. Test data were collected from accelerometers and full-field photogrammetry. The focus of this paper will be to document impact testing and simulation results for the longitudinal impact of the subfloor section and the vertical drop test of the forward framed fuselage section.

The Dual Impact of Gender and the Influence of Timing of Parenthood on Men's and Women's Career Development: Longitudinal Findings

ERIC Educational Resources Information Center

Abele, Andrea E.; Spurk, Daniel

2011-01-01

This study investigated the impact of gender, the gender-related self-concept (agency and communion), and the timing of parenthood on objective career success of 1,015 highly educated professionals. Hypotheses derived from a dual-impact model of gender and career-related processes were tested in a 5-wave longitudinal study over a time span of 10…

Biofidelity assessment of the 6-year-old ATDs in lateral impact.

PubMed

Yaek, J L; Li, Y; Lemanski, P J; Begeman, P C; Rouhana, S W; Cavanaugh, J M

2016-07-03

The objective of this study was to assess and compare the current lateral impact biofidelity of the shoulder, thorax, abdomen, and pelvis of the Q6, Q6s, and Hybrid III (HIII) 6-year-old anthropomorphic test devices (ATDs) through lateral impact testing. A series of lateral impact pendulum tests, vertical drop tests, and Wayne State University (WSU) sled tests was performed, based on the procedures detailed in ISO/TR 9790 (1999) and scaling to the 6-year-old using Irwin et al. ( 2002 ). The HIII used in this study was tested with the Ford-designed abdomen described in Rouhana ( 2006 ) and Elhagediab et al. ( 2006 ). The data collected from the 3 different ATDs were filtered using SAE J211 (SAE International 2003 ), aligned using the methodology described by Donnelly and Moorhouse ( 2012 ), and compared for each body region tested (shoulder, thorax, abdomen, and pelvis). The biofidelity performance in lateral impact for the 3 ATDs was assessed against the scaled biofidelity targets published in Irwin et al. ( 2002 ), the abdominal biofidelity target suggested in van Ratingen et al. ( 1997 ), and the biofidelity targets published in Rhule et al. ( 2013 ). Regional and overall biofidelity rankings for each of the 3 ATDs were performed using both the ISO 9790 biofidelity rating system (ISO/TR 9790 1999) and the NHTSA's external biofidelity ranking system (BRS; Rhule et al. 2013 ). All 3 6-year-old ATD's pelvises were rated as least biofidelic of the 4 body regions tested, based on both the ISO and BRS biofidelity rating systems, followed by the shoulder and abdomen, respectively. The thorax of all 3 ATDs was rated as the most biofidelic body region using the aforementioned biofidelity rating systems. The HIII 6-year-old ATD was rated last in overall biofidelity of the 3 tested ATDs, based on both rating systems. The Q6s ATD was rated as having the best overall biofidelity using both rating systems. All 3 ATDs are more biofidelic in the thorax and abdomen than the shoulder and pelvis, with the pelvis being the least biofidelic of all 4 tested body regions. None of the 3 tested 6-year-old ATDs had an overall ranking of 2.0 or less, based on the BRS ranking. Therefore, it is expected that none of the 3 ATDs would mechanically respond like a postmortem human subject (PMHS) in a lateral impact crash test based on this ranking system. With respect to the ISO biofidelity rating, the HIII dummy would be considered unsuitable and the Q-series dummies would be considered marginal for assessing side impact occupant protection.

Simulated Waste Testing Of Glycolate Impacts On The 2H-Evaporator System

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

Martino, C. J.

2013-08-13

Glycolic acid is being studied as a total or partial replacement for formic acid in the Defense Waste Processing Facility (DWPF) feed preparation process. After implementation, the recycle stream from DWPF back to the high-level waste tank farm will contain soluble sodium glycolate. Most of the potential impacts of glycolate in the tank farm were addressed via a literature review, but several outstanding issues remained. This report documents the non-radioactive simulant tests impacts of glycolate on storage and evaporation of Savannah River Site high-level waste. The testing for which non-radioactive simulants could be used involved the following: the partitioning ofmore » glycolate into the evaporator condensate, the impacts of glycolate on metal solubility, and the impacts of glycolate on the formation and dissolution of sodium aluminosilicate scale within the evaporator. The following are among the conclusions from this work: Evaporator condensate did not contain appreciable amounts of glycolate anion. Of all tests, the highest glycolate concentration in the evaporator condensate was 0.38 mg/L. A significant portion of the tests had glycolate concentration in the condensate at less than the limit of quantification (0.1 mg/L). At ambient conditions, evaporator testing did not show significant effects of glycolate on the soluble components in the evaporator concentrates. Testing with sodalite solids and silicon containing solutions did not show significant effects of glycolate on sodium aluminosilicate formation or dissolution.« less

Scholastic Aptitude Test Preparation for the Adolescent Dyslexic.

ERIC Educational Resources Information Center

Rothschild, Lois H.

1987-01-01

Scholastic Aptitude Test skills of dyslexics can be enhanced through use of special test administration arrangements and a structured program of vocabulary development, test-taking strategies, and a pattern of analysis to improve reading comprehension. Two case studies illustrate the impact of drill and reinforcement, multimodal imagery…

An integrated draft gear model with the consideration of wagon body structural characteristics

NASA Astrophysics Data System (ADS)

Chang, Gao; Liangliang, Yang; Weihua, Ma; Min, Zhang; Shihui, Luo

2018-03-01

With the increase of railway wagon axle load and the growth of marshalling quantity, the problem caused by impact and vibration of vehicles is increasingly serious, which leads to the damage of vehicle structures and the components. In order to improve the reliability of longitudinal connection model for vehicle impact tests, a new railway wagon longitudinal connection model was developed to simulate and analyse vehicle impact tests. The new model is based on characteristics of longitudinal force transmission for vehicles and parts. In this model, carbodies and bogies were simplified to a particle system that can vibrate in the longitudinal direction, which corresponded to a stiffness-damping vibration system. The model consists of three sub-models, that is, coupler and draft gear sub-model, centre plate sub-model and carbody structure sub-model. Compared with conventional draft gear models, the new model was proposed with geometrical and mechanical relations of friction draft gears considered and with behaviours of sticking, sliding and impact between centre plate and centre bowl added. Besides, virtual springs between discrete carbodies were built to describe the structural deformation of carbody. A computation program for longitudinal dynamics based on vehicle impact tests was accomplished to simulate. Comparisons and analyses regarding the train dynamics outputs and vehicle impact tests were conducted. Simulation results indicate that the new wagon longitudinal connection model can provide a practical application environment for wagons, and the outputs of vehicle impact tests agree with those of field tests. The new model can also be used to study on longitudinal vibrations of different vehicles, of carbody and bogie, and of carbody itself.

Experimental and Modeling Studies of Crush, Puncture, and Perforation Scenarios in the Steven Impact Test

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

Vandersall, K S; Chidester, S K; Forbes, J W

2002-06-28

The Steven test and associated modeling has greatly increased the fundamental knowledge of practical predictions of impact safety hazards for confined and unconfined explosive charges. Building on a database of initial work, experimental and modeling studies of crush, puncture, and perforation scenarios were investigated using the Steven impact test. The descriptions of crush, puncture, and perforation arose from safety scenarios represented by projectile designs that ''crush'' the energetic material or either ''puncture'' with a pinpoint nose or ''perforate'' the front cover with a transportation hook. As desired, these scenarios offer different aspects of the known mechanisms that control ignition: friction,more » shear and strain. Studies of aged and previously damaged HMX-based high explosives included the use of embedded carbon foil and carbon resistor gauges, high-speed cameras, and blast wave gauges to determine the pressure histories, time required for an explosive reaction, and the relative violence of those reactions, respectively. Various ignition processes were modeled as the initial reaction rate expression in the Ignition and Growth reaction rate equations. Good agreement with measured threshold velocities, pressure histories, and times to reaction was calculated for LX-04 impacted by several projectile geometries using a compression dependent ignition term and an elastic-plastic model with a reasonable yield strength for impact strain rates.« less

Methodology for determining economic impacts of raised medians : data collection for additional case studies

DOT National Transportation Integrated Search

1998-10-01

The objective of this four-year resaerch effort is to develop and test a methodology to estimate the economic impact of median design. This report summarizes the work performed in the second year. The secnd year of this study included collecting data...

Female Leaders: Injurious or Inspiring Role Models for Women?

ERIC Educational Resources Information Center

Hoyt, Crystal L.; Simon, Stefanie

2011-01-01

The impact of female role models on women's leadership aspirations and self-perceptions after a leadership task were assessed across two laboratory studies. These studies tested the prediction that upward social comparisons to high-level female leaders will have a relatively detrimental impact on women's self-perceptions and leadership aspirations…

Impact of Intention on the ERP Correlates of Face Recognition

ERIC Educational Resources Information Center

Guillaume, Fabrice; Tiberghien, Guy

2013-01-01

The present study investigated the impact of study-test similarity on face recognition by manipulating, in the same experiment, the expression change (same vs. different) and the task-processing context (inclusion vs. exclusion instructions) as within-subject variables. Consistent with the dual-process framework, the present results showed that…

Comparative Evaluation of Immediate Post-Operative Sequelae after Surgical Removal of Impacted Mandibular Third Molar with or without Tube Drain - Split-Mouth Study.

PubMed

Kumar, Barun; Bhate, Kalyani; Dolas, R S; Kumar, Sn Santhosh; Waknis, Pushkar

2016-12-01

Third molar surgery is one of the most common surgical procedures performed in general dentistry. Post-operative variables such as pain, swelling and trismus are major concerns after impacted mandibular third molar surgery. Use of passive tube drain is supposed to help reduce these immediate post-operative sequelae. The current study was designed to compare the effect of tube drain on immediate post-operative sequelae following impacted mandibular third molar surgery. To compare the post-operative sequelae after surgical removal of impacted mandibular third molar surgery with or without tube drain. Thirty patients with bilateral impacted mandibular third molars were divided into two groups: Test (with tube drain) and control (without tube drain) group. In the test group, a tube drain was inserted through the releasing incision, and kept in place for three days. The control group was left without a tube drain. The post-operative variables like, pain, swelling, and trismus were calculated after 24 hours, 72 hours, 7 days, and 15 days in both the groups and analyzed statistically using chi-square and t-test analysis. The test group showed lesser swelling as compared to control group, with the swelling variable showing statistically significant difference at post-operative day 3 and 7 (p≤ 0.05) in both groups. There were no statistically significant differences in pain and trismus variables in both the groups. The use of tube drain helps to control swelling following impacted mandibular third molar surgery. However, it does not have much effect on pain or trismus.

Assessing the impact of a nurse-delivered home dried blood spot service on uptake of testing for household contacts of hepatitis B-infected pregnant women across two London trusts.

PubMed

Keel, P; Edwards, G; Flood, J; Nixon, G; Beebeejaun, K; Shute, J; Poh, J; Millar, A; Ijaz, S; Parry, J; Mandal, S; Ramsay, M; Amirthalingam, G

2016-07-01

Despite national guidance recommending testing and vaccination of household contacts of hepatitis B-infected pregnant women, provision and uptake of this is sub-optimal. The aim of this study was to evaluate the use of in-home dried blood spot (DBS) testing to increase testing and vaccination of household contacts of hepatitis B-infected pregnant women as an alternative approach to conventional primary-care follow-up. The study was conducted across two London maternity trusts (North Middlesex and Newham). All hepatitis B surface antigen-positive pregnant women identified through these trusts were eligible for inclusion. The intervention of in-home DBS testing for household contacts was introduced at North Middlesex Trust from November 2010 to December 2011. Data on testing and vaccination uptake from GP records across the two trusts were compared between baseline (2009) and intervention (2010-2011) periods. In-home DBS service increased testing uptake for all ages (P < 0·001) with the biggest impact seen in partners, where testing increased from 30·3% during the baseline period to 96·6% during the intervention period in North Middlesex Trust. Although impact on vaccine uptake was less marked, improvements were observed for adults. The provision of nurse-led home-based DBS may be useful in areas of high prevalence.

Impact response and biomechanical analysis of the knee-thigh-hip complex in frontal impacts with a full human body finite element model.

PubMed

Ruan, Jesse S; El-Jawahri, Raed; Barbat, Saeed; Rouhana, Stephen W; Prasad, Priya

2008-11-01

Changes in vehicle safety design technology and the increasing use of seat-belts and airbag restraint systems have gradually changed the relative proportion of lower extremity injuries. These changes in real world injuries have renewed interest and the need of further investigation into occupant injury mechanisms and biomechanical impact responses of the knee-thigh-hip complex during frontal impacts. This study uses a detailed finite element model of the human body to simulate occupant knee impacts experienced in frontal crashes. The human body model includes detailed anatomical features of the head, neck, shoulder, chest, thoracic and lumbar spine, abdomen, pelvis, and lower and upper extremities. The material properties used in the model for each anatomic part of the human body were obtained from test data reported in the literature. The human body model used in the current study has been previously validated in frontal and side impacts. It was further validated with cadaver knee-thigh-hip impact tests in the current study. The effects of impactor configuration and flexion angle of the knee on biomechanical impact responses of the knee-thigh-hip complex were studied using the validated human body finite element model. This study showed that the knee flexion angle and the impact direction and shape of the impactors affected the injury outcomes of the knee-thigh-hip complex significantly. The 60 degrees flexed knee impact showed the least impact force, knee pressure, femoral von Mises stress, and pelvic von Mises stress but largest relative displacements of the Posterior Cruciate Ligament (PCL) and Anterior Cruciate Ligament (ACL). The 90 degrees flexed knee impact resulted in a higher impact force, knee pressure, femoral von Mises stress, and pelvic von Mises stress; but smaller PCL and ACL displacements. Stress distributions of the patella, femur, and pelvis were also given for all the simulated conditions.

Neck injury tolerance under inertial loads in side impacts.

PubMed

McIntosh, Andrew S; Kallieris, Dimitrios; Frechede, Bertrand

2007-03-01

Neck injury remains a major issue in road safety. Current side impact dummies and side impact crashworthiness assessments do not assess the risk of neck injury. These assessments are limited by biofidelity and knowledge regarding neck injury criteria and tolerance levels in side impacts. Side impact tests with PMHS were performed at the Heidelberg University in the 1980s and 1990s to improve primarily the understanding of trunk dynamics, injury mechanisms and criteria. In order to contribute to the definition of human tolerances at neck level, this study presents an analysis of the head/neck biomechanical parameters that were measured in these tests and their relationship to neck injury severity. Data from 15 impact tests were analysed. Head accelerations, and neck forces and moments were calculated from 9-accelerometer array head data, X-rays and anthropometric data. Statistically significant relationships were observed between resultant head acceleration and neck force and neck injury severity. The average resultant head acceleration for AIS 2 neck injuries was 112 g, while resultant neck force was 4925 N and moment 241 Nm. The data compared well to other test data on cadavers and volunteers. It is hoped that the paper will assist in the understanding of neck injuries and the development of tolerance criteria.

Experimental Investigation of the Shuttle Transportation System Composite Overwrapped Pressure Vessels for Stress Rupture Life

NASA Technical Reports Server (NTRS)

Greene, Nathanael; Saulsberry, Regor; Yoder, Tommy; Forsyth, Brad; Carillo, Marlene; Thesken, John

2006-01-01

A viewgraph presentation describing stress rupture testing on Composite Overwrapped Pressure Vessels (COPV) is shown. The topics include: 1) Purpose for Testing; 2) NASA WSTF COPV Test Program; 3) NASA WSTF Test Facilities; 4) COPV Impact Study; 5) Fluids Compatibility Testing; 6) Stress Rupture Testing; and 7) COPV Lifting.

Impact of a pneumatic tube system transport on hemostasis parameters measurement: the experiment of Cochin universitary hospital (AP-HP, Paris, France).

PubMed

Calmette, Leyla; Ibrahim, Firas; Gouin, Isabelle; Horellou, Marie-Hélène; Mazoyer, Élisabeth; Fontenay, Michaela; Flaujac, Claire

2017-02-01

Samples transported by pneumatic tube system are submitted to forces of acceleration and deceleration which can affect laboratory parameters. At Cochin hospital, majority of samples of hemostasis, except for platelets tests, are transported by pneumatic tube system. The objective of this study was to evaluate the impact of a pneumatic tube system (PTS) transport compared to hand-delivered transport on samples and to qualify Cochin hospital PTS according to requirements of standard ISO 15189. A bibliographical study was made and showed that pneumatic tube system particularly influences platelets tests. Four citrate tubes were collected in 5 healthy volunteers in the maternity: 2 tubes were transported by PTS and 2 others were hand-delivered to the laboratory. Five coagulation tests were analyzed: prothrombine time (PT), activated partial thromboplastin time (aPTT), factor (F) V, FVIII and platelet closure time with PFA-100TM collagen/epinephrine. For each volunteer, the results obtained by PTS and by hand-delivered transport were compared with formula usually used for biological analysis retake: 2.8 x standard deviation of reproductibility variation coefficient (SH GTA 01, COFRAC). This study did not show an impact of PTS on PT, aPTT, FV and FVIII. For PFA-100TM collagen/epinephrine, we noted an impact on 2/5 volunteers. These results, in agreement with the literature, led to the conclusion that Cochin hospital PTS is in compliance to transport samples for usual coagulation tests except platelet tests. This study allowed to issue French recommendations for PTS transport of hemostasis tubes qualification available on "Groupe français d'hémostase et thrombose" Web site.

Impact of Genetic Counseling and Connexin-26 and Connexin-30 Testing on Deaf Identity and Comprehension of Genetic Test Results in a Sample of Deaf Adults: A Prospective, Longitudinal Study

PubMed Central

Palmer, Christina G. S.; Boudreault, Patrick; Baldwin, Erin E.; Sinsheimer, Janet S.

2014-01-01

Using a prospective, longitudinal study design, this paper addresses the impact of genetic counseling and testing for deafness on deaf adults and the Deaf community. This study specifically evaluated the effect of genetic counseling and Connexin-26 and Connexin-30 genetic test results on participants' deaf identity and understanding of their genetic test results. Connexin-26 and Connexin-30 genetic testing was offered to participants in the context of linguistically and culturally appropriate genetic counseling. Questionnaire data collected from 209 deaf adults at four time points (baseline, immediately following pre-test genetic counseling, 1-month following genetic test result disclosure, and 6-months after result disclosure) were analyzed. Four deaf identity orientations (hearing, marginal, immersion, bicultural) were evaluated using subscales of the Deaf Identity Development Scale-Revised. We found evidence that participants understood their specific genetic test results following genetic counseling, but found no evidence of change in deaf identity based on genetic counseling or their genetic test results. This study demonstrated that culturally and linguistically appropriate genetic counseling can improve deaf clients' understanding of genetic test results, and the formation of deaf identity was not directly related to genetic counseling or Connexin-26 and Connexin-30 genetic test results. PMID:25375116

Impact resistant boron/aluminum composites for large fan blades

NASA Technical Reports Server (NTRS)

Oller, T. L.; Salemme, C. T.; Bowden, J. H.; Doble, G. S.; Melnyk, P.

1977-01-01

Blade-like specimens were subjected to static ballistic impact testing to determine their relative FOD impact resistance levels. It was determined that a plus or minus 15 deg layup exhibited good impact resistance. The design of a large solid boron/aluminum fan blade was conducted based on the FOD test results. The CF6 fan blade was used as a baseline for these design studies. The solid boron/aluminum fan blade design was used to fabricate two blades. This effort enabled the assessment of the scale up of existing blade manufacturing details for the fabrication of a large B/Al fan blade. Existing CF6 fan blade tooling was modified for use in fabricating these blades.

Experimental injury study of children seated behind collapsing front seats in rear impacts.

PubMed

Saczalski, Kenneth J; Sances, Anthony; Kumaresan, Srirangam; Burton, Joseph L; Lewis, Paul R

2003-01-01

In the mid 1990's the U.S. Department of Transportation made recommendations to place children and infants into the rear seating areas of motor vehicles to avoid front seat airbag induced injuries and fatalities. In most rear-impacts, however, the adult occupied front seats will collapse into the rear occupant area and pose another potentially serious injury hazard to the rear-seated children. Since rear-impacts involve a wide range of speeds, impact severity, and various sizes of adults in collapsing front seats, a multi-variable experimental method was employed in conjunction with a multi-level "factorial analysis" technique to study injury potential of rear-seated children. Various sizes of Hybrid III adult surrogates, seated in a "typical" average strength collapsing type of front seat, and a three-year-old Hybrid III child surrogate, seated on a built-in booster seat located directly behind the front adult occupant, were tested at various impact severity levels in a popular "minivan" sled-buck test set up. A total of five test configurations were utilized in this study. Three levels of velocity changes ranging from 22.5 to 42.5 kph were used. The average of peak accelerations on the sled-buck tests ranged from approximately 8.2 G's up to about 11.1 G's, with absolute peak values of just over 14 G's at the higher velocity change. The parameters of the test configuration enabled the experimental data to be combined into a polynomial "injury" function of the two primary independent variables (i.e. front seat adult occupant weight and velocity change) so that the "likelihood" of rear child "injury potential" could be determined over a wide range of the key parameters. The experimentally derived head injury data was used to obtain a preliminary HIC (Head Injury Criteria) polynomial fit at the 900 level for the rear-seated child. Several actual accident cases were compared with the preliminary polynomial fit. This study provides a test efficient, multi-variable, method to compare the injury biomechanical data with actual accident cases.

Cognitive Behavioral Therapy: A Meta-Analysis of Race and Substance Use Outcomes

PubMed Central

Windsor, Liliane Cambraia; Jemal, Alexis; Alessi, Edward

2015-01-01

Cognitive behavioral therapy (CBT) is an effective intervention for reducing substance use. However, because CBT trials have included predominantly White samples caution must be used when generalizing these effects to Blacks and Hispanics. This meta-analysis compared the impact of CBT in reducing substance use between studies with a predominantly non-Hispanic White sample (hereafter NHW studies) and studies with a predominantly Black and/or Hispanic sample (hereafter BH studies). From 322 manuscripts identified in the literature, 17 met criteria for inclusion. Effect sizes between CBT and comparison group at posttest had similar effects on substance abuse across NHW and BH studies. However, when comparing pre-posttest effect sizes from groups receiving CBT between NHW and BH studies, CBT’s impact was significantly stronger in NHW studies. T-test comparisons indicated reduced retention/engagement in BH studies, albeit failing to reach statistical significance. Results highlight the need for further research testing CBT’s impact on substance use among Blacks and Hispanics. PMID:25285527

A comparison of impact force reduction by polymer materials used for mouthguard fabrication.

PubMed

Gawlak, Dominika; Mańka-Malara, Katarzyna; Mierzwińska-Nastalska, Elżbieta; Gieleta, Roman; Kamiński, Tomasz; Łuniewska, Magdalena

2017-01-01

The essential function of mouthguards is protection against the effects of injuries sustained during sports activities. This purpose will be successfully achieved if appropriate materials ensuring sufficient reduction of the injury force are used for mouthguard fabrication. The objective of the study was to investigate the force reduction capability of selected materials as well as to identify which material reduces the impact force to the highest degree. The material for the study were samples of polymers (6 samples in total), obtained during the process of deep pressing (2 samples), flasking (3 samples) and thermal injection (1 sample), which were tested for impact force damping using an impact device - Charpy impact hammer. The control group comprised of the ceramic material samples subjected to the hammer impact. The statistical analysis applied in this study were one-way Welch ANOVA with post-hoc Games-Howell pairwise comparisons. The test materials reduced the impact force of the impact hammer to varying degrees. The greatest damping capability was demonstrated for the following materials: Impak with 1:1 powder-to-liquid weight ratio polymerized with the conventional flasking technique, and Corflex Orthodontic used in the thermal injection technique of mouthguard fabrication. Impak with 1:1 weight ratio and Corflex Orthodontic should be recommended for the fabrication of mouthguards since they demonstrated the most advantageous damping properties.

Experimental Study on Stress Monitoring of Sand-Filled Steel Tube during Impact Using Piezoceramic Smart Aggregates.

PubMed

Du, Guofeng; Zhang, Juan; Zhang, Jicheng; Song, Gangbing

2017-08-22

The filling of thin-walled steel tubes with quartz sand can help to prevent the premature buckling of the steel tube at a low cost. During an impact, the internal stress of the quartz sand-filled steel tube column is subjected to not only axial force but also lateral confining force, resulting in complicated internal stress. A suitable sensor for monitoring the internal stress of such a structure under an impact is important for structural health monitoring. In this paper, piezoceramic Smart Aggregates (SAs) are embedded into a quartz Sand-Filled Steel Tube Column (SFSTC) to monitor the internal structural stress during impacts. The piezoceramic smart aggregates are first calibrated by an impact hammer. Tests are conducted to study the feasibility of monitoring the internal stress of a structure. The results reflect that the calibration value of the piezoceramic smart aggregate sensitivity test is in good agreement with the theoretical value, and the output voltage value of the piezoceramic smart aggregate has a good linear relationship with external forces. Impact tests are conducted on the sand-filled steel tube with embedded piezoceramic smart aggregates. By analyzing the output signal of the piezoceramic smart aggregates, the internal stress state of the structure can be obtained. Experimental results demonstrated that, under the action of impact loads, the piezoceramic smart aggregates monitor the compressive stress at different locations in the steel tube, which verifies the feasibility of using piezoceramic smart aggregate to monitor the internal stress of a structure.

The Impact of Mobile Learning on ESP Learners' Performance

ERIC Educational Resources Information Center

Alkhezzi, Fahad; Al-Dousari, Wadha

2016-01-01

This study explores the impact of using mobile phone applications, namely Telegram Messenger, on teaching and learning English in an ESP context. The main objective is to test whether using mobile phone applications have an impact on ESP learners' performance by mainly investigating the influence such teaching technique can have on learning…

Residual strength assessment of low velocity impact damage of graphite-epoxy laminates

NASA Technical Reports Server (NTRS)

Lal, K. M.

1983-01-01

This report contains the study of Low Velocity Transverse Impact Damage of graphite-epoxy T300/5208 composite laminates. The specimen, 100 mm diameter clamped plates, were impact damaged by a cantilever-type instrumented 1-inch diameter steel ball. Study was limited to impact velocity 6 m/sec. Rectangular strips, 50 mm x 125 mm, were cut from the impact-damage specimens so that the impact damage zone was in the center of the strips. These strips were tested in tension to obtain their residual strength. An energy dissipation model was developed to predict the residual strength from fracture mechanics concepts. Net energy absorbed I(a) was evaluated from coefficient of restitution concepts based on shear dominated theory of fiber-reinforced materials, with the modification that during loading and unloading the shear deformation are respectively elastic-plastic and elastic. Delamination energy I(d) was predicted by assuming that the stiffness of the laminate dropped due to debonding. Fiber-breakage energy, assumed to be equal to the difference of I(a) and I(d), was used to determine the residual strength. Predictions were compared with test results.

Development and validation of rear impact computer simulation model of an adult manual transit wheelchair with a seated occupant.

PubMed

Salipur, Zdravko; Bertocci, Gina

2010-01-01

It has been shown that ANSI WC19 transit wheelchairs that are crashworthy in frontal impact exhibit catastrophic failures in rear impact and may not be able to provide stable seating support and thus occupant protection for the wheelchair occupant. Thus far only limited sled test and computer simulation data have been available to study rear impact wheelchair safety. Computer modeling can be used as an economic and comprehensive tool to gain critical knowledge regarding wheelchair integrity and occupant safety. This study describes the development and validation of a computer model simulating an adult wheelchair-seated occupant subjected to a rear impact event. The model was developed in MADYMO and validated rigorously using the results of three similar sled tests conducted to specifications provided in the draft ISO/TC 173 standard. Outcomes from the model can provide critical wheelchair loading information to wheelchair and tiedown manufacturers, resulting in safer wheelchair designs for rear impact conditions. (c) 2009 IPEM. Published by Elsevier Ltd. All rights reserved.

COMMUNICATION IMPACT, A CONCEPTUAL MODEL ANALYSIS OF INDIVIDUAL PREDISPOSITIONS AND THE ANALYSIS OF THE IMPACT OF A COUNTY CIVIL DEFENSE EDUCATIONAL PROGRAM.

ERIC Educational Resources Information Center

BEAL, GEORGE M.; AND OTHERS

THIS STUDY DEALS WITH COMMUNICATION AT THREE LEVELS--DEVELOPMENT OF A GENERALIZED MODEL OF THE PROCESS WHEREBY COMMUNICATION ACHIEVES IMPACT, THE OPERATIONALIZATION OF THE MODEL, AND TESTING OF THE DEGREE TO WHICH THE MODEL PREDICTS THE RESPONSE OF MEMBERS OF THE POTENTIAL AUDIENCE TO A SPECIFIC COMMUNICATION EVENT. THIS IMPACT MODEL TAKES THE…

Assessment of satellite communications quality study. Addendum 1: Impact of propagation delay on data transmission

NASA Technical Reports Server (NTRS)

Campanella, S. J.; Chitre, D. M.

1988-01-01

The single factor that irrevocably distinguishes geostationary satellite telephony transmission from terrestrial transmission is the greater propagation delay over satellite links. This difference has always provoked vigorous debate over the impact of delay on the subscribers using services incorporating satellite links. The issue is addressed from a variety of directions including human factors studies, laboratory subjective tests that evaluate delay with and without echo, and field tests that obtain data on the opinion of subscribers regarding the quality of service of operational circuits in both national U.S. domestic and international trans-Atlantic network. The tests involved the use of both echo suppressors and echo cancellers.

Methylisothiazolinone contact allergy in Croatia: Epidemiology and course of disease following patch testing.

PubMed

Ljubojević Hadžavdić, Suzana; Uter, Wolfgang; Ilijanić Samošćanec, Maja; Johansen, Jeanne D

2018-05-30

Methylisothiazolinone (MI) caused an epidemic of contact allergy in Europe, as shown by data from many countries, but no studies from Croatia exist. Also, data are lacking on the severity of allergic contact dermatitis (ACD) caused by MI, and its impact on quality of life and prognosis. To determine the frequency of MI contact allergy among Croatian dermatitis patients, identify causative exposures, assess the impact of disease, and study the prognosis. Data were collected for consecutive dermatitis patients with MI contact allergy patch tested in Croatia between November 2, 2015 and November 3, 2016. MI contact allergy was diagnosed in 13.2% of 798 tested patients. The most frequent dermatitis locations were the hands (76%) and face (61%). In 89.3% of patients, MI contact allergy was found to be of current relevance. Considerable severity and impact on daily life of disease was found at the first consultation, but this significantly decreased until follow-up 3 months later. Patch testing is the standard method for the diagnosis of ACD, and it has been shown to have an important beneficial effect on prognosis. The severity of MI ACD and the impact on daily life emphasize the need for prevention. © 2018 John Wiley & Sons A/S. Published by John Wiley & Sons Ltd.

Ballistic impact velocity response of carbon fibre reinforced aluminium alloy laminates for aero-engine

NASA Astrophysics Data System (ADS)

Mohammed, I.; Abu Talib, A. R.; Sultan, M. T. H.; Saadon, S.

2017-12-01

Aerospace and other industries use fibre metal laminate composites extensively due to their high specific strength, stiffness and fire resistance, in addition to their capability to be tailored into different forms for specific purposes. The behaviours of such composites under impact loading is another factor to be considered due to the impacts that occur in take-off, landing, during maintenance and operations. The aim of the study is to determine the specific perforation energy and impact strength of the fibre metal laminates of different layering pattern of carbon fibre reinforced aluminium alloy and hybrid laminate composites of carbon fibre and natural fibres (kenaf and flax). The composites are fabricated using the hand lay-up method in a mould with high bonding polymer matrix and compressed by a compression machine, cured at room temperature for one day and post cure in an oven for three hours. The impact tests are conducted using a gun tunnel system with a flat cylindrical bullet fired using a helium gas at a distance of 14 inches to the target. Impact and residual velocity of the projectile are recorded by high speed video camera. Specific perforation energy of carbon fibre reinforced aluminium alloy (CF+AA) for both before and after fire test are higher than the specific perforation energy of the other composites considered before and after fire test respectively. CF +AA before fire test is 55.18% greater than after. The same thing applies to impact strength of the composites where CF +AA before the fire test has the highest percentage of 11.7%, 50.0% and 32.98% as respectively compared to carbon fibre reinforced aluminium alloy (CARALL), carbon fibre reinforced flax aluminium alloy (CAFRALL) and carbon fibre reinforced kenaf aluminium alloy (CAKRALL), and likewise for the composites after fire test. The considered composites in this test can be used in the designated fire zone of an aircraft engine to protect external debris from penetrating the engine shield due to higher values of impact strength and specific perforation energy as highlighted by the test results.

Acoustic fatigue and sound transmission characteristics of a ram composite panel design

NASA Technical Reports Server (NTRS)

Cockburn, J. A.; Chang, K. Y.; Kao, G. C.

1972-01-01

An experimental study to determine the acoustic fatigue characteristics of a flat multi-layered structural panel is described. The test panel represented a proposed design for the outer skin of a research application module to be housed within the space shuttle orbiter vehicle. The test specimen was mounted in one wall of the Wyle 100,000 cu ft reverberation room and exposed to a broadband acoustic environment having an overall level of 145 db. The test panel was exposed to nine separate applications of the acoustic environment, each application consisting of 250 seconds duration. Upon completion of the ninth test run, the specimen was exposed to a simulated micrometeoroid impact near the panel center. One additional test run of 250 seconds duration was then performed to complete the overall simulation of 50 flight missions. The experimental results show that no significant fatigue damage occurred until the test specimen was exposed to a simulated micrometeoroid impact. The intermediate foam layer forming the core of the test specimen suffered considerable damage due to this impact, causing a marked variation in the dynamic characteristics of the overall test panel. During the final application of the acoustic environment, the strain and acceleration response spectra showed considerable variation from those spectra obtained prior to impact of the panel. Fatigue damage from acoustic loading however, was limited to partial de-bonding around the edges of the composite panel.

Hybrid Effect Evaluation of Steel Fiber and Carbon Fiber on the Performance of the Fiber Reinforced Concrete

PubMed Central

Song, Weimin; Yin, Jian

2016-01-01

Fiber reinforcement is an important method to enhance the performance of concrete. In this study, the compressive test and impact test were conducted, and then the hybrid effect between steel fiber (SF) and carbon fiber (CF) was evaluated by employing the hybrid effect index. Compressive toughness and impact toughness of steel fiber reinforced concrete (SFRC), carbon fiber reinforced concrete (CFRC) and hybrid fiber reinforced concrete (HFRC) were explored at steel fiber volume fraction 0.5%, 1%, 1.5% and carbon fiber 0.1%, 0.2%, 0.3%. Results showed that the addition of steel fiber and carbon fiber can increase the compressive strength. SF, CF and the hybridization between them could increase the compressive toughness significantly. The impact test results showed that as the volume of fiber increased, the impact number of the first visible crack and the ultimate failure also increased. The improvement of toughness mainly lay in improving the crack resistance after the first crack. Based on the test results, the positive hybrid effect of steel fiber and carbon fiber existed in hybrid fiber reinforced concrete. The relationship between the compressive toughness and impact toughness was also explored. PMID:28773824

Hybrid Effect Evaluation of Steel Fiber and Carbon Fiber on the Performance of the Fiber Reinforced Concrete.

PubMed

Song, Weimin; Yin, Jian

2016-08-18

Fiber reinforcement is an important method to enhance the performance of concrete. In this study, the compressive test and impact test were conducted, and then the hybrid effect between steel fiber (SF) and carbon fiber (CF) was evaluated by employing the hybrid effect index. Compressive toughness and impact toughness of steel fiber reinforced concrete (SFRC), carbon fiber reinforced concrete (CFRC) and hybrid fiber reinforced concrete (HFRC) were explored at steel fiber volume fraction 0.5%, 1%, 1.5% and carbon fiber 0.1%, 0.2%, 0.3%. Results showed that the addition of steel fiber and carbon fiber can increase the compressive strength. SF, CF and the hybridization between them could increase the compressive toughness significantly. The impact test results showed that as the volume of fiber increased, the impact number of the first visible crack and the ultimate failure also increased. The improvement of toughness mainly lay in improving the crack resistance after the first crack. Based on the test results, the positive hybrid effect of steel fiber and carbon fiber existed in hybrid fiber reinforced concrete. The relationship between the compressive toughness and impact toughness was also explored.

Low Velocity Earth-Penetration Test and Analysis

NASA Technical Reports Server (NTRS)

Fasanella, Edwin L.; Jones, Yvonne; Knight, Norman F., Jr.; Kellas, Sotiris

2001-01-01

Modeling and simulation of structural impacts into soil continue to challenge analysts to develop accurate material models and detailed analytical simulations to predict the soil penetration event. This paper discusses finite element modeling of a series of penetrometer drop tests into soft clay. Parametric studies are performed with penetrometers of varying diameters, masses, and impact speeds to a maximum of 45 m/s. Parameters influencing the simulation such as the contact penalty factor and the material model representing the soil are also studied. An empirical relationship between key parameters is developed and is shown to correlate experimental and analytical results quite well. The results provide preliminary design guidelines for Earth impact that may be useful for future space exploration sample return missions.

ITOS/space shuttle study

NASA Technical Reports Server (NTRS)

1971-01-01

The results are reported of a study to explore the potential cost reductions in the operational ITOS weather satellite program as a consequence of shuttle/bug availability for satellite placement and retrieval, and satellite servicing and maintenance. The study program was divided into shuttle impact on equipment and testing costs, and shuttle impact on overall future ITOS operational program costs, and shuttle impact on configuration. It is concluded that savings in recurring spacecraft costs can be realized in the 1978 ITOS program, if a space shuttle is utilized.

The Impact of Advanced Placement Courses on High School Students Taking the Scholastic Aptitude Test.

ERIC Educational Resources Information Center

Thomas, L. M.; Thomas, Suzanne G.

This obtrusive post-hoc quasi-experimental study investigated Scholastic Assessment Test (SAT) scores of 111 high school students in grades 10 through 12. Fifty-three students were enrolled in at least one Advanced Placement (AP) course at the time of the study. General factorial analysis of variance (ANOVA) tested for significant differences…

WWC Review of the Report "Daily Online Testing in Large Classes: Boosting College Performance While Reducing Achievement Gaps." What Works Clearinghouse Single Study Review

ERIC Educational Resources Information Center

What Works Clearinghouse, 2014

2014-01-01

The 2013 study, "Daily Online Testing in Large Classes: Boosting College Performance While Reducing Achievement Gaps," examined the impact of frequent online testing and immediate feedback on the academic performance of college students. The study was conducted at the University of Texas in the fall of 2008 and 2011. Researchers found…

Foul tip impact attenuation of baseball catcher masks using head impact metrics

PubMed Central

White, Terrance R.; Cutcliffe, Hattie C.; Shridharani, Jay K.; Wood, Garrett W.; Bass, Cameron R.

2018-01-01

Currently, no scientific consensus exists on the relative safety of catcher mask styles and materials. Due to differences in mass and material properties, the style and material of a catcher mask influences the impact metrics observed during simulated foul ball impacts. The catcher surrogate was a Hybrid III head and neck equipped with a six degree of freedom sensor package to obtain linear accelerations and angular rates. Four mask styles were impacted using an air cannon for six 30 m/s and six 35 m/s impacts to the nasion. To quantify impact severity, the metrics peak linear acceleration, peak angular acceleration, Head Injury Criterion, Head Impact Power, and Gadd Severity Index were used. An Analysis of Covariance and a Tukey’s HSD Test were conducted to compare the least squares mean between masks for each head injury metric. For each injury metric a P-Value less than 0.05 was found indicating a significant difference in mask performance. Tukey’s HSD test found for each metric, the traditional style titanium mask fell in the lowest performance category while the hockey style mask was in the highest performance category. Limitations of this study prevented a direct correlation from mask testing performance to mild traumatic brain injury. PMID:29856814

The impact of federal policy on teachers' use of science manipulatives: A survey of teacher philosophy and practices

NASA Astrophysics Data System (ADS)

Helgoe, Catherine A.

Recently, educators in public K-12 schools have added testing of science knowledge to the measures of Adequate Yearly Progress required by the federal No Child Left Behind (NCLB) legislation. Research of the impact of NCLB policy on general teaching practices had credited the policy with improving instruction; however, negative impacts noted included the concern that teachers "teach to the test," narrowing the curriculum. Testing as an assessment strategy was not advocated by the professional educators and scientists responsible for the National Science Education Standards (NSES). Results from previous studies pointed to a potential conflict between the NCLB reforms and the National Science Education Standards science standards, in which teachers might reduce or eliminate hands-on activities and other constructivist practices in order to focus class time on other topics and tasks. Most research on NCLB policy, however, had not evaluated instructional practices regarding science education. This study examined the relationship among teacher beliefs, specifically the strength of their constructivist versus traditional beliefs, teachers' responses to NCLB policy, and teachers' use of constructivist practices in the form of manipulatives. This study showed that national policy did have an impact on teachers; however, that impact was not specific to the hands-on practices in science education. Teachers who responded to this survey had found many benefits in student learning using manipulatives and those positive impacts on their students justified the increased use of manipulatives in the classroom. The strength of teachers' constructivist beliefs showed a weak positive correlation to choices related to curriculum priorities, learning goals and advantages in using manipulatives. However, a relationship to beliefs was not found in the changes teachers made to various instructional practices, or in how they viewed certain manipulative materials, or in how they viewed federal policies. The impact of the federal policies was related more to school climate and teacher motivation than instructional choices. Most teachers reported positive impacts on student learning using manipulatives and these results, more than the pressure they felt to "cover the curriculum" or prepare students for standardized tests, provided reasons to continue using the practice.

Correcting power and p-value calculations for bias in diffusion tensor imaging.

PubMed

Lauzon, Carolyn B; Landman, Bennett A

2013-07-01

Diffusion tensor imaging (DTI) provides quantitative parametric maps sensitive to tissue microarchitecture (e.g., fractional anisotropy, FA). These maps are estimated through computational processes and subject to random distortions including variance and bias. Traditional statistical procedures commonly used for study planning (including power analyses and p-value/alpha-rate thresholds) specifically model variability, but neglect potential impacts of bias. Herein, we quantitatively investigate the impacts of bias in DTI on hypothesis test properties (power and alpha-rate) using a two-sided hypothesis testing framework. We present theoretical evaluation of bias on hypothesis test properties, evaluate the bias estimation technique SIMEX for DTI hypothesis testing using simulated data, and evaluate the impacts of bias on spatially varying power and alpha rates in an empirical study of 21 subjects. Bias is shown to inflame alpha rates, distort the power curve, and cause significant power loss even in empirical settings where the expected difference in bias between groups is zero. These adverse effects can be attenuated by properly accounting for bias in the calculation of power and p-values. Copyright © 2013 Elsevier Inc. All rights reserved.

Overview of High Speed Close-Up Imaging in an Icing Environment

NASA Technical Reports Server (NTRS)

Miller, Dean R.; Lynch, Christopher J.; Tate, Peter A.

2004-01-01

The Icing Branch and Imaging Technology Center at NASA Glenn Research Center have recently been involved in several projects where high speed close-up imaging was used to investigate water droplet impact/splash, and also ice particle impact/bounce in an icing wind tunnel. The combination of close-up and high speed imaging capabilities were required because the particles being studied were relatively small (d < 1 mm in diameter), and the impact process occurred in a very short time period (t(sub impact) << 1 sec). High speed close-up imaging was utilized to study the dynamics of droplet impact and splash in simulated Supercooled Large Droplet (SLD) icing conditions. The objective of this test was to evaluate the capability of a ultra high speed camera system to acquire quantitative information about the impact process (e.g., droplet size, velocity). Imaging data were obtained in an icing wind tunnel for spray cloud MVD > 50 m. High speed close-up imaging was also utilized to characterize the impact of ice particles on an airfoil with a thermally protected leading edge. The objective of this investigation was to determine whether ice particles tend to "stick" or "bounce" after impact. Imaging data were obtained for cases where the airfoil surface was heated and unheated. Based on the results from this test, follow on tests were conducted to investigate ice particle impact on the sensing elements of water content measurement devices. This paper will describe the use of the imaging systems to support these experimental investigations, present some representative results, and summarize what was learned about the use of these systems in an icing environment.

Investigating CSI: portrayals of DNA testing on a forensic crime show and their potential effects.

PubMed

Ley, Barbara L; Jankowski, Natalie; Brewer, Paul R

2012-01-01

The popularity of forensic crime shows such as CSI has fueled debate about their potential social impact. This study considers CSI's potential effects on public understandings regarding DNA testing in the context of judicial processes, the policy debates surrounding crime laboratory procedures, and the forensic science profession, as well as an effect not discussed in previous accounts: namely, the show's potential impact on public understandings of DNA and genetics more generally. To develop a theoretical foundation for research on the "CSI effect," it draws on cultivation theory, social cognitive theory, and audience reception studies. It then uses content analysis and textual analysis to illuminate how the show depicts DNA testing. The results demonstrate that CSI tends to depict DNA testing as routine, swift, useful, and reliable and that it echoes broader discourses about genetics. At times, however, the show suggests more complex ways of thinking about DNA testing and genetics.

Impact attenuation of protective boxing and taekwondo headgear.

PubMed

O'Sullivan, David M; Fife, Gabriel P

2016-11-01

This study aimed to compare the impact attenuation performance of boxing and taekwondo headgear in terms of peak linear and rotational acceleration. To measure the impact attenuation of headgear, a standardized (American Society for Testing and Materials (ASTM) F-2397) martial arts headgear striker was used to impart impacts to a 50th Percentile Male Hybrid III Crash Test Dummy head and neck complex. Two boxing (Adidas and Greenhill) and two taekwondo (Adidas and Nike) headgear, approved by the Association Internationale de Boxe Amateur and the World Taekwondo Federation (WTF), were selected. Each of the selected headgear was fitted to the Hybrid III head and subsequently subjected to five impacts at the front and side with a maximum impact interim time of 60 seconds by the rotating striker at 8 ± 0.3 m/s. Linear and rotational acceleration were recorded at 10,000 Hz. There were significant interactions of the impact location and brand on the rotational acceleration, F(3,40) = 6.7, p < .05. There were significant main effects of both impact location F(1,40) = 9.07, p < .05 and headgear brand F(3,40) = 9.9, p < .05 on the linear acceleration. Pairwise comparisons show significant differences between the front and side for both linear and rotational acceleration. The headgear tested failed the ASTM high impact test requirement to reduce the linear acceleration to below a threshold of 150 g. Further development of headgear to reduce impact linear and rotational acceleration magnitudes should be called for by the relevant sport governing bodies and initiated by headgear manufactures.

Experimental Approach on the Behavior of Composite Laminated Shell under Transverse Impact Loading

NASA Astrophysics Data System (ADS)

Kim, Y. N.; Im, K. H.; Lee, K. S.; Cho, Y. J.; Kim, S. H.; Yang, I. Y.

2005-04-01

Composites are to be considered for many structural applications structural weight. These materials have high strength-to-weight and stiffness-to-weight ratios. However, they are susceptible to impact loading because they are laminar systems with weak interfaces. Matrix cracking and delamination are the most common damage mechanisms of low velocity impact and are dependent on each other. This paper is to study the behavior of composite shell under transverse impact loading. In this study, carbon-epoxy composite laminates with various curvatures was used. Low velocity impact tests were performed using a drop weight testing machine. The 100mm×100mm shells were clamped in order to produce a central circular area (φ=80mm). An hemispherical impactor (m=0.1kg and φ=10mm) was used and the tests were done with velocities ranging from 2.8 to 4.8 m/s. The real curve force/time was registered in order to obtain the maximum contact force and contact time. And then, we know that contact force and delamination area of flat-plate is higher than cylindrical shell panel in the same kinetic energy level, and flat-plate is easily penetrated than cylindrical shell panel. And contact force, deflection and delamination area decrease as the curvature increase.

An investigation on impacts of scheduling configurations on Mississippi biology subject area testing

NASA Astrophysics Data System (ADS)

Marchette, Frances Lenora

The purpose of this mixed modal study was to compare the results of Biology Subject Area mean scores of students on a 4 x 4 block schedule, A/B block schedule, and traditional year-long schedule for 1A to 5A size schools. This study also reviewed the data to determine if minority or gender issues might influence the test results. Interviews with administrators and teachers were conducted about the type of schedule configuration they use and the influence that the schedule has on student academic performance on the Biology Subject Area Test. Additionally, this research further explored whether schedule configurations allow sufficient time for students to construct knowledge. This study is important to schools, teachers, and administrators because it can assist them in considering the impacts that different types of class schedules have on student performance and if ethnic or gender issues are influencing testing results. This study used the causal-comparative method for the quantitative portion of the study and constant comparative method for the qualitative portion to explore the relationship of school schedules on student academic achievement on the Mississippi Biology Subject Area Test. The aggregate means of selected student scores indicate that the Mississippi Biology Subject Area Test as a measure of student performance reveals no significant difference on student achievement for the three school schedule configurations. The data were adjusted for initial differences of gender, minority, and school size on the three schedule configurations. The results suggest that schools may employ various schedule configurations and expect student performance on the Mississippi Biology Subject Area Test to be unaffected. However, many areas of concern were identified in the interviews that might impact on school learning environments. These concerns relate to effective classroom management, the active involvement of students in learning, the adequacy of teacher education programs and the stress of testing on everyone involved in high-stakes testing.

Developing, testing, and implementing a survey of scientist mentoring teachers as part of an RET: The GABI RET mentor survey.

NASA Astrophysics Data System (ADS)

Davey, B.

2017-12-01

The impacts of mentoring in education have been well established. Mentors have a large impact on their mentees and have been show to affect mentee attitudes towards learning, interest in subjects, future success, and more. While mentoring has a well-documented impact on the mentees, mentoring also has an impact on the mentors themselves. However, little has been studied empirically about these impacts. When we looked for a validated instrument that measured the impact of mentoring on the scientists working with the teachers, we found many anecdotal reports but no instruments that meet our specific needs. To this end, we developed, tested, and implemented our own instrument for measuring the impacts of mentoring on our scientist mentors. Our instrument contained both quantitative and qualitative items designed to reveal the effects of mentoring in two areas: 1) cognitive domain (mentoring, teaching, understanding K-12) and 2) affective domain (professional, personal, participation). We first shared our survey with experts in survey development and mentoring, gathered their feedback, and incorporated their suggestions into our instrument. We then had a subsection of our mentors complete the survey and then complete it again three to four days later (test-retest). Our survey has a high correlation for the test-retest quantitative items (0.93) and a high correlation (0.90) between the three reviewers of the qualitative items. From our findings, we feel we have a validated instrument (face, content, and contruct validity) that answers our research questions reliably. Our contribution to the study of mentoring of science teachers reveals a broad range of impacts on the mentors themselves including an improved understanding of the challenges of classroom teaching, a recognition of the importance of scientists working with science teachers, an enhanced ability to communicate their research and findings, and an increased interest and excitement for their own work.

Damage Behaviors and Compressive Strength of Toughened CFRP Laminates with Thin Plies Subjected to Transverse Impact Loadings

NASA Astrophysics Data System (ADS)

Yokozeki, Tomohiro; Aoki, Yuichiro; Ogasawara, Toshio

It has been recognized that damage resistance and strength properties of CFRP laminates can be improved by using thin-ply prepregs. This study investigates the damage behaviors and compressive strength of CFRP laminates using thin-ply and standard prepregs subjected to out-of-plane impact loadings. CFRP laminates used for the evaluation are prepared using the standard prepregs, thin-ply prepregs, and combinations of the both. Weight-drop impact test and post-impact compression test of quasi-isotropic laminates are performed. It is shown that the damage behaviors are different between the thin-ply and the standard laminates, and the compression-after-impact strength is improved by using thin-ply prepregs. Effects of the use of thin-ply prepregs and the layout of thin-ply layers on the damage behaviors and compression-after-impact properties are discussed based on the experimental results.

Sleep disturbance and neurocognitive function during the recovery from a sport-related concussion in adolescents.

PubMed

Kostyun, Regina O; Milewski, Matthew D; Hafeez, Imran

2015-03-01

Sleep disturbances are a hallmark sign after a sport-related concussion (SRC). Poor sleep has been shown to adversely affect baseline neurocognitive test scores, but it is not comprehensively understood how neurocognitive function is affected by disrupted sleep during recovery from a concussion. To identify the correlation between adolescent athletes' neurocognitive function and their self-reported sleep quantity and sleep disturbance symptoms during recovery from SRC. Cross-sectional study; Level of evidence, 3. Immediate Post-Concussion Assessment and Cognition Testing (ImPACT) data were retrospectively collected for 545 adolescent athletes treated for SRC at a sports medicine concussion clinic. Patients were stratified into groups based on 2 criteria: self-reported sleep duration and self-reported sleep disturbance symptoms during postinjury ImPACT testing. Sleep duration was classified as short (<7 hours), intermediate (7-9 hours), and long (>9 hours). Sleep disturbance symptoms were self-reported as part of the Post-Concussion Symptom Scale (PCSS) as either sleeping less than normal, sleeping more than normal, or having trouble falling asleep. One-way analyses of variance were conducted to examine the effects that sleep duration as well as self-reported sleep disturbance symptoms had on composite scores. A total of 1067 ImPACT tests were analyzed: test 1, 545; test 2, 380; and test 3, 142. Sleeping fewer than 7 hours the night before testing correlated with higher PCSS scores (P < .001), whereas sleeping longer than 9 hours correlated with worse visual memory (P = .01), visual motor speed (P <.001), and reaction time (P = .04) composite scores. With regard to self-reported sleep disturbance symptoms, patients demonstrated worse composite scores during ImPACT testing when they self-reported sleeping more than normal (ImPACT test 1: verbal memory, P < .001; visual motor speed, P = .05; reaction time, P = .01; ImPACT test 2: verbal memory, P < .001; visual memory, P < .001; visual motor speed, P < .001; reaction time, P = .01). Adolescent patients recovering from SRC demonstrated higher (worse) PCSS scores (P < .001) when they sensed that their sleep had been disrupted. Adolescent patients who perceive that their sleep is somehow disrupted after SRC may report a greater number of concussion symptoms during their recovery. In addition, the study results suggest that sleeping more than normal may identify an individual who continues to be actively recovering from concussion, given the correlation between lower neurocognitive function and this self-reported symptom. © 2014 The Author(s).

Low Velocity Impact Behavior of Basalt Fiber-Reinforced Polymer Composites

NASA Astrophysics Data System (ADS)

Shishevan, Farzin Azimpour; Akbulut, Hamid; Mohtadi-Bonab, M. A.

2017-06-01

In this research, we studied low velocity impact response of homogenous basalt fiber-reinforced polymer (BFRP) composites and then compared the impact key parameters with carbon fiber-reinforced polymer (CFRP) homogenous composites. BFRPs and CFRPs were fabricated by vacuum-assisted resin transfer molding (VARTM) method. Fabricated composites included 60% fiber and 40% epoxy matrix. Basalt and carbon fibers used as reinforcement materials were weaved in 2/2 twill textile tip in the structures of BFRP and CFRP composites. We also utilized the energy profile method to determine penetration and perforation threshold energies. The low velocity impact tests were carried out in 30, 60, 80, 100, 120 and 160 J energy magnitudes, and impact response of BFRPs was investigated by related force-deflection, force-time, deflection-time and absorbed energy-time graphics. The related impact key parameters such as maximum contact force, absorbed energy, deflection and duration time were compared with CFRPs for various impact energy levels. As a result, due to the higher toughness of basalt fibers, a better low velocity impact performance of BFRP than that of CFRP was observed. The effects of fabrication parameters, such as curing process, were studied on the low velocity impact behavior of BFRP. The results of tested new fabricated materials show that the change of fabrication process and curing conditions improves the impact behavior of BFRPs up to 13%.

The Impact of Settable Test Item Exposure Control Interface Format on Postsecondary Business Student Test Performance

ERIC Educational Resources Information Center

Truell, Allen D.; Zhao, Jensen J.; Alexander, Melody W.

2005-01-01

The purposes of this study were to determine if there is a significant difference in postsecondary business student scores and test completion time based on settable test item exposure control interface format, and to determine if there is a significant difference in student scores and test completion time based on settable test item exposure…

Impact of Video Feedback on Teachers' Eye-Contact Mannerisms in Microteaching.

ERIC Educational Resources Information Center

Karasar, Niyazi

To test the impact of video feedback on teachers' eye-contact mannerisms in microteaching in inservice vocational teacher education, the study utilized video recordings from the data bank generated by previous studies conducted at the Ohio State University's Center for Vocational and Technical Education. The tapes were assigned through a…

Effects of Career-Related Continuous Learning: A Case Study

ERIC Educational Resources Information Center

Rowold, Jens; Hochholdinger, Sabine; Schilling, Jan

2008-01-01

Purpose: Although proposed from theory, the assumption that career-related continuous learning (CRCL) has a positive impact on subsequent job performance has not been tested empirically. The present study aims to close this gap in the literature. A model is derived from theory that predicts a positive impact of CRCL, learning climate, and initial…

Impact of Latino Parent Engagement on Student Academic Achievement: A Pilot Study

ERIC Educational Resources Information Center

Araque, Juan Carlos; Wietstock, Cathy; Cova, Heather M.; Zepeda, Steffanie

2017-01-01

The current pilot study examines the impact of the "Ten Education Commandments for Parents" program on (1) new immigrant Latino parents' knowledge of the U.S. public education system, (2) parent engagement, and (3) their children's academic achievement. Utilizing a pre-experimental, pre- and post-test research design, four schools with…

A Scale of Mobbing Impacts

ERIC Educational Resources Information Center

Yaman, Erkan

2012-01-01

The aim of this research was to develop the Mobbing Impacts Scale and to examine its validity and reliability analyses. The sample of study consisted of 509 teachers from Sakarya. In this study construct validity, internal consistency, test-retest reliabilities and item analysis of the scale were examined. As a result of factor analysis for…

Impact of Metacognitive Awareness on Performance of Students in Chemistry

ERIC Educational Resources Information Center

Rahman, Fazal ur; Jumani, Nabi Bux; Chaudry, Muhammad Ajmal; Chisti, Saeed ul Hasan; Abbasi, Fahim

2010-01-01

The impact of metacognitive awareness on students' performance has been examined in the present study. 900 students of grade X participated in the study. Metacognitive awareness was measured using inventory, while performance of students was measured with the help of researcher made test in the subject of chemistry. Results indicated that…

The Impact of Graphing Calculators on Math Achievement: A Quantitative, Longevity Analysis

ERIC Educational Resources Information Center

Arbini, Corey

2016-01-01

This study examined the impact of high school students' graphing calculator usage on their math achievement over time. Achievement growth was measured using nationally-recognized standardized test scores from EXPLORE, PLAN, and ACT. Two groups of students were used in this study; one group had graphing calculators integrated beginning in…

Impact of a Routine, Opt-Out HIV Testing Program on HIV Testing and Case Detection in North Carolina Sexually-Transmitted Disease Clinics

PubMed Central

Klein, Pamela W.; Messer, Lynne C.; Myers, Evan R.; Weber, David J.; Leone, Peter A.; Miller, William C.

2016-01-01

The impact of routine, opt-out HIV testing programs in clinical settings is inconclusive. The objective of this study was to estimate the impact of an expanded, routine HIV testing program in North Carolina sexually transmitted disease (STD) clinics on HIV testing and case detection. Adults aged 18–64 who received an HIV test in a North Carolina STD clinic July 1, 2005 through June 30, 2011 were included in this analysis, dichotomized at the date of implementation on November 1, 2007. HIV testing and case detection counts and rates were analyzed using interrupted time series analysis, and Poisson and multilevel logistic regression. Pre-intervention, 426 new HIV-infected cases were identified from 128,029 tests (0.33%), whereas 816 new HIV-infected cases were found from 274,745 tests post-intervention (0.30%). Pre-intervention, HIV testing increased by 55 tests per month (95% confidence interval [CI]: 41, 72), but only 34 tests per month (95% CI: 26, 42) post-intervention. Increases in HIV testing rates were most pronounced in females and non-Hispanic whites. A slight pre-intervention decline in case detection was mitigated by the intervention (mean difference [MD]=0.01; 95% CI: −0.02, 0.05). Increases in case detection rates were observed among females and non-Hispanic blacks. The impact of a routine HIV screening in North Carolina STD clinics was marginal, with the greatest benefit among persons not traditionally targeted for HIV testing. The use of a pre-intervention comparison period identified important temporal trends that otherwise would have been ignored. PMID:24825338

An exploration of the impact of invalid MMPI-2 protocols on collateral self-report measure scores.

PubMed

Forbey, Johnathan D; Lee, Tayla T C

2011-11-01

Although a number of studies have examined the impact of invalid MMPI-2 (Butcher et al., 2001) response styles on MMPI-2 scale scores, limited research has specifically explored the effects that such response styles might have on conjointly administered collateral self-report measures. This study explored the potential impact of 2 invalidating response styles detected by the Validity scales of the MMPI-2, overreporting and underreporting, on scores of collateral self-report measures administered conjointly with the MMPI-2. The final group of participants included in analyses was 1,112 college students from a Midwestern university who completed all measures as part of a larger study. Results of t-test analyses suggested that if either over- or underreporting was indicated by the MMPI-2 Validity scales, the scores of most conjointly administered collateral measures were also significantly impacted. Overall, it appeared that test-takers who were identified as either over- or underreporting relied on such a response style across measures. Limitations and suggestions for future study are discussed.

A Brief Study on Toxic Combustion Products of the Polymers Used in High-Pressure Oxygen Systems

NASA Technical Reports Server (NTRS)

Hshieh, Fu-Yu; Beeson, Harold D.

2005-01-01

One likely cause of polymer ignition in a high-pressure oxygen system is the adiabatic-compression heating of polymers caused by pneumatic impact. Oxidative pyrolysis or combustion of polymers in a high-pressure oxygen system could generate toxic gases. This paper investigates the feasibility of using the NASA pneumatic-impact system to conduct adiabatic-compression combustion tests and determines the toxic combustion products produced from the burning of five selected polymers. Five polymers commonly used in high-pressure oxygen systems, Zytel(Registered TradeMark) 42 (Nylon 6/6), Buna N (nitrile rubber), Witon(Registered TradeMark) A (copolymer of vinylidene fluoride and hexafluoropropylene), Neoflon(Registered TradeMark) (polychlorotrifluoroethylene), and Teflon(Registered TradeMark) (polytetrafluoroethylene), were tested in the NASA pneumatic-impact test system at 17.2-MPa oxygen pressure. The polymers were ignited and burned; combustion products were collected in a stainless-steel sample bottle and analyzed using various methods. The results show that the NASA pneumatic-impact system is an appropriate test system to conduct adiabatic-compression combustion tests and to collect combustion products for further chemical analysis. The composition of the combustion product gas generated from burning the five selected polymers are presented and discussed.

Protein Binding: Do We Ever Learn?▿

PubMed Central

Zeitlinger, Markus A.; Derendorf, Hartmut; Mouton, Johan W.; Cars, Otto; Craig, William A.; Andes, David; Theuretzbacher, Ursula

2011-01-01

Although the influence of protein binding (PB) on antibacterial activity has been reported for many antibiotics and over many years, there is currently no standardization for pharmacodynamic models that account for the impact of protein binding of antimicrobial agents in vitro. This might explain the somewhat contradictory results obtained from different studies. Simple in vitro models which compare the MIC obtained in protein-free standard medium versus a protein-rich medium are prone to methodological pitfalls and may lead to flawed conclusions. Within in vitro test systems, a range of test conditions, including source of protein, concentration of the tested antibiotic, temperature, pH, electrolytes, and supplements may influence the impact of protein binding. As new antibiotics with a high degree of protein binding are in clinical development, attention and action directed toward the optimization and standardization of testing the impact of protein binding on the activity of antibiotics in vitro become even more urgent. In addition, the quantitative relationship between the effects of protein binding in vitro and in vivo needs to be established, since the physiological conditions differ. General recommendations for testing the impact of protein binding in vitro are suggested. PMID:21537013

Policies of Global English Tests: Test-Takers' Perspectives on the IELTS Retake Policy

ERIC Educational Resources Information Center

Hamid, M. Obaidul

2016-01-01

Globalized English proficiency tests such as the International English Language Testing System (IELTS) are increasingly playing the role of gatekeepers in a globalizing world. Although the use of the IELTS as a "policy tool" for making decisions in the areas of study, work and migration impacts on test-takers' lives and life chances, not…

Modeling Local Item Dependence in Cloze and Reading Comprehension Test Items Using Testlet Response Theory

ERIC Educational Resources Information Center

Baghaei, Purya; Ravand, Hamdollah

2016-01-01

In this study the magnitudes of local dependence generated by cloze test items and reading comprehension items were compared and their impact on parameter estimates and test precision was investigated. An advanced English as a foreign language reading comprehension test containing three reading passages and a cloze test was analyzed with a…

The Positive and Negative Effects of Science Concept Tests on Student Conceptual Understanding

ERIC Educational Resources Information Center

Chang, Chun-Yen; Yeh, Ting-Kuang; Barufaldi, James P.

2010-01-01

This study explored the phenomenon of testing effect during science concept assessments, including the mechanism behind it and its impact upon a learner's conceptual understanding. The participants consisted of 208 high school students, in either the 11th or 12th grade. Three types of tests (traditional multiple-choice test, correct concept test,…

Photon Doppler Velocimeter to Measure Entrained Additive Manufactured Bulk Metal Powders in Hot Subsonic and Supersonic Oxygen Gas

NASA Technical Reports Server (NTRS)

Tylka, Jonathan

2016-01-01

Parts produced by additive manufacturing, particularly selective laser melting (SLM), have been shown to silt metal particulate even after undergoing stringent precision aerospace cleaning processes (Lowrey 2016). As printed parts are used in oxygen systems with increased pressures, temperatures, and gas velocity, the risk of ignition by particle impact, the most common direct ignition source of metals in oxygen, substantially increases. The White Sands Test Facility (WSTF), in collaboration with Marshall Space Flight Center (MSFC), desires to test the ignitability of SLM metals by particle impact in heated oxygen. The existing test systems rely on gas velocity calculations to infer particle velocity in both subsonic and supersonic particle impact systems. Until now, it was not possible to directly measure particle velocity. To increase the fidelity of planned SLM ignition studies, it is necessary to validate that the Photon Doppler Velocimetry(PDV) test system can accurately measure particle velocity.

Impact of rockfalls on protection measures: an experimental approach

NASA Astrophysics Data System (ADS)

Yuan, J.; Li, Y.; Huang, R.; Pei, X.

2015-01-01

The determination of rockfall impact force is crucial in designing the protection measures. In the present study, laboratory tests are carried out by taking the weight and shape of the falling rock fragments, drop height, incident angle, platform on the slideway and cushion layer on the protection measures as factors to investigate their influences on the impact force. The test results indicate that the impact force is positively exponential to the weight of rockfall and the instantaneous impact velocity of the rockfall approaching the protection measures. The impact velocity is found to be dominated not only by the drop height but also by the shape of rockfall as well as the length of the platform on the slideway. A great drop height and/or a short platform produce a fast impact velocity. Spherical rockfalls experience a reater impact velocity than cubic and cylindrical ones. A layer of cushion on the protection measures may reduce the impact force to a greater extent. The reduction effects are dominated by the cushion material and the thickness of the cushion layer. The thicker the cushion layer, the greater the reduction effect and the less the impact force. The stiffer the buffer material, the less the buffering effect and the greater the impact force. The present study indicates that the current standard in China for designing protection measures may overestimate the impact force by taking no consideration for the rockfall shape, platform and cushion layer.

Angular Impact Mitigation System for Bicycle Helmets to Reduce Head Acceleration and Risk of Traumatic Brain Injury

PubMed Central

Hansen, Kirk; Dau, Nathan; Feist, Florian; Deck, Caroline; Willinger, Rémy; Madey, Steven M.; Bottlang, Michael

2013-01-01

Angular acceleration of the head is a known cause of traumatic brain injury (TBI), but contemporary bicycle helmets lack dedicated mechanisms to mitigate angular acceleration. A novel Angular Impact Mitigation (AIM) system for bicycle helmets has been developed that employs an elastically suspended aluminum honeycomb liner to absorb linear acceleration in normal impacts as well as angular acceleration in oblique impacts. This study tested bicycle helmets with and without AIM technology to comparatively assess impact mitigation. Normal impact tests were performed to measure linear head acceleration. Oblique impact tests were performed to measure angular head acceleration and neck loading. Furthermore, acceleration histories of oblique impacts were analyzed in a computational head model to predict the resulting risk of TBI in the form of concussion and diffuse axonal injury (DAI). Compared to standard helmets, AIM helmets resulted in a 14% reduction in peak linear acceleration (p < 0.001), a 34% reduction in peak angular acceleration (p < 0.001), and a 22% to 32% reduction in neck loading (p < 0.001). Computational results predicted that AIM helmets reduced the risk of concussion and DAI by 27% and 44%, respectively. In conclusion, these results demonstrated that AIM technology could effectively improve impact mitigation compared to a contemporary expanded polystyrene-based bicycle helmet, and may enhance prevention of bicycle-related TBI. Further research is required. PMID:23770518

The Impact of Length of Study Abroad on Collocational Knowledge: The Case of Saudi Students in Australia

ERIC Educational Resources Information Center

Alqarni, Ibrahim R.

2017-01-01

This study investigates the impact that study in Australia has on the lexical knowledge of Saudi Arabian students. It focuses on: 1) the effects that the length of study in Australia has on the acquisition of lexical collocations, as reflected by lexical knowledge tests, and 2) whether there is a significant gender difference in the acquisition of…

Universal BRCA1/BRCA2 Testing for Ovarian Cancer Patients is Welcomed, but with Care: How Women and Staff Contextualize Experiences of Expanded Access.

PubMed

Shipman, Hannah; Flynn, Samantha; MacDonald-Smith, Carey F; Brenton, James; Crawford, Robin; Tischkowitz, Marc; Hulbert-Williams, Nicholas J

2017-12-01

Decreasing costs of genetic testing and advances in treatment for women with cancer with germline BRCA1/BRCA2 mutations have heralded more inclusive genetic testing programs. The Genetic Testing in Epithelial Ovarian Cancer (GTEOC) Study, investigates the feasibility and acceptability of offering genetic testing to all women recently diagnosed with epithelial ovarian cancer (universal genetic testing or UGT). Study participants and staff were interviewed to: (i) assess the impact of UGT (ii) integrate patients' and staff perspectives in the development of new UGT programs. Semi-structured interviews were conducted with twelve GTEOC Study participants and five members of staff involved in recruiting them. The transcripts were transcribed verbatim and analyzed using Interpretative Phenomenological Analysis. There are two super-ordinate themes: motivations and influences around offers of genetic testing and impacts of genetic testing in ovarian cancer patients. A major finding is that genetic testing is contextualized within the broader experiences of the women; the impact of UGT was minimized in comparison with the ovarian cancer diagnosis. Women who consent to UGT are motivated by altruism and by their relatives' influence, whilst those who decline are often considered overwhelmed or fearful. Those without a genetic mutation are usually reassured by this result, whilst those with a genetic mutation must negotiate new uncertainties and responsibilities towards their families. Our findings suggest that UGT in this context is generally acceptable to women. However, the period shortly after diagnosis is a sensitive time and some women are emotionally overburdened. UGT is considered a 'family affair' and staff must acknowledge this.

Simulating the Impact Response of Three Full-Scale Crash Tests of Cessna 172 Aircraft

NASA Technical Reports Server (NTRS)

Jackson, Karen E.; Fasanella, Edwin L.; Littell, Justin D.; Annett, Martin S.; Stimson, Chad M.

2017-01-01

During the summer of 2015, a series of three full-scale crash tests were performed at the Landing and Impact Research Facility located at NASA Langley Research Center of Cessna 172 aircraft. The first test (Test 1) represented a flare-to-stall emergency or hard landing onto a rigid surface. The second test (Test 2) represented a controlled-flight- into-terrain (CFIT) with a nose down pitch attitude of the aircraft, which impacted onto soft soil. The third test (Test 3) also represented a CFIT with a nose up pitch attitude of the aircraft, which resulted in a tail strike condition. Test 3 was also conducted onto soft soil. These crash tests were performed for the purpose of evaluating the performance of Emergency Locator Transmitters and to generate impact test data for model calibration. Finite element models were generated and impact analyses were conducted to simulate the three impact conditions using the commercial nonlinear, transient dynamic finite element code, LS-DYNA®. The objective of this paper is to summarize test-analysis results for the three full-scale crash tests.

Impact of information and communications technologies on residental customer energy services

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

Goldman, C.; Kempton, W.; Eide, A.

1996-10-01

This study analyzes the potential impact of information and communications technologies on utility delivery of residential customer energy services. Many utilities are conducting trials which test energy-related and non-energy services using advanced communications systems.

Thermal Management Coating As Thermal Protection System for Space Transportation System

NASA Technical Reports Server (NTRS)

Kaul, Raj; Stuckey, C. Irvin

2003-01-01

This paper presents viewgraphs on the development of a non-ablative thermal management coating used as the thermal protection system material for space shuttle rocket boosters and other launch vehicles. The topics include: 1) Coating Study; 2) Aerothermal Testing; 3) Preconditioning Environments; 4) Test Observations; 5) Lightning Strike Test Panel; 6) Test Panel After Impact Testing; 7) Thermal Testing; and 8) Mechanical Testing.

Impact of Training of Traditional Birth Attendants on Maternal Health Care: A Community-based Study.

PubMed

Satishchandra, D M; Naik, V A; Wantamutte, A S; Mallapur, M D; Sangolli, H N

2013-12-01

To study the impact of Training of Traditional Birth Attendants (TBAs) on maternal health care in a rural area. An interventional study in the Primary Health Center area was conducted over 1-year period between March 2006 and February 2007, which included all the 50 Traditional Birth Attendants (30 previously trained and 20 untrained), as study participants. Pretest evaluation regarding knowledge, attitude, and practices about maternal care was done. Post-test evaluation was done at the first month (early) and at the fifth month (late) after the training. Analysis was done by using Mc. Nemer's test, Chi-square test with Yates's correction and Fischer's exact test. Early and late post-test evaluation showed that there was a progressive improvement in the maternal health care provided by both the groups. Significant reduction in the maternal and perinatal deaths among the deliveries conducted by TBAs after the training was noted. Training programme for TBAs with regular follow-ups in the resource-poor setting will not only improve the quality of maternal care but also reduce perinatal deaths.

Developing a quality by design approach to model tablet dissolution testing: an industrial case study.

PubMed

Yekpe, Ketsia; Abatzoglou, Nicolas; Bataille, Bernard; Gosselin, Ryan; Sharkawi, Tahmer; Simard, Jean-Sébastien; Cournoyer, Antoine

2018-07-01

This study applied the concept of Quality by Design (QbD) to tablet dissolution. Its goal was to propose a quality control strategy to model dissolution testing of solid oral dose products according to International Conference on Harmonization guidelines. The methodology involved the following three steps: (1) a risk analysis to identify the material- and process-related parameters impacting the critical quality attributes of dissolution testing, (2) an experimental design to evaluate the influence of design factors (attributes and parameters selected by risk analysis) on dissolution testing, and (3) an investigation of the relationship between design factors and dissolution profiles. Results show that (a) in the case studied, the two parameters impacting dissolution kinetics are active pharmaceutical ingredient particle size distributions and tablet hardness and (b) these two parameters could be monitored with PAT tools to predict dissolution profiles. Moreover, based on the results obtained, modeling dissolution is possible. The practicality and effectiveness of the QbD approach were demonstrated through this industrial case study. Implementing such an approach systematically in industrial pharmaceutical production would reduce the need for tablet dissolution testing.

Integrating Formal Methods and Testing 2002

NASA Technical Reports Server (NTRS)

Cukic, Bojan

2002-01-01

Traditionally, qualitative program verification methodologies and program testing are studied in separate research communities. None of them alone is powerful and practical enough to provide sufficient confidence in ultra-high reliability assessment when used exclusively. Significant advances can be made by accounting not only tho formal verification and program testing. but also the impact of many other standard V&V techniques, in a unified software reliability assessment framework. The first year of this research resulted in the statistical framework that, given the assumptions on the success of the qualitative V&V and QA procedures, significantly reduces the amount of testing needed to confidently assess reliability at so-called high and ultra-high levels (10-4 or higher). The coming years shall address the methodologies to realistically estimate the impacts of various V&V techniques to system reliability and include the impact of operational risk to reliability assessment. Combine formal correctness verification, process and product metrics, and other standard qualitative software assurance methods with statistical testing with the aim of gaining higher confidence in software reliability assessment for high-assurance applications. B) Quantify the impact of these methods on software reliability. C) Demonstrate that accounting for the effectiveness of these methods reduces the number of tests needed to attain certain confidence level. D) Quantify and justify the reliability estimate for systems developed using various methods.

A multi-particle crushing apparatus for studying rock fragmentation due to repeated impacts

NASA Astrophysics Data System (ADS)

Huang, S.; Mohanty, B.; Xia, K.

2017-12-01

Rock crushing is a common process in mining and related operations. Although a number of particle crushing tests have been proposed in the literature, most of them are concerned with single-particle crushing, i.e., a single rock sample is crushed in each test. Considering the realistic scenario in crushers where many fragments are involved, a laboratory crushing apparatus is developed in this study. This device consists of a Hopkinson pressure bar system and a piston-holder system. The Hopkinson pressure bar system is used to apply calibrated dynamic loads to the piston-holder system, and the piston-holder system is used to hold rock samples and to recover fragments for subsequent particle size analysis. The rock samples are subjected to three to seven impacts under three impact velocities (2.2, 3.8, and 5.0 m/s), with the feed size of the rock particle samples limited between 9.5 and 12.7 mm. Several key parameters are determined from this test, including particle size distribution parameters, impact velocity, loading pressure, and total work. The results show that the total work correlates well with resulting fragmentation size distribution, and the apparatus provides a useful tool for studying the mechanism of crushing, which further provides guidelines for the design of commercial crushers.

Factor structure and measurement invariance of the Health Education Impact Questionnaire: Does the subjectivity of the response perspective threaten the contextual validity of inferences?

PubMed

Elsworth, Gerald R; Nolte, Sandra; Osborne, Richard H

2015-01-01

On-going evidence is required to support the validity of inferences about change and group differences in the evaluation of health programs, particularly when self-report scales requiring substantial subjectivity in response generation are used as outcome measures. Following this reasoning, the aim of this study was to replicate the factor structure and investigate the measurement invariance of the latest version of the Health Education Impact Questionnaire, a widely used health program evaluation measure. An archived dataset of responses to the most recent version of the English-language Health Education Impact Questionnaire that uses four rather than six response options (N = 3221) was analysed using exploratory structural equation modelling and confirmatory factor analysis appropriate for ordered categorical data. Metric and scalar invariance were studied following recent recommendations in the literature to apply fully invariant unconditional models with minimum constraints necessary for model identification. The original eight-factor structure was replicated and all but one of the scales (Self Monitoring and Insight) was found to consist of unifactorial items with reliability of ⩾0.8 and satisfactory discriminant validity. Configural, metric and scalar invariance were established across pre-test to post-test and population sub-groups (sex, age, education, ethnic background). The results support the high level of interest in the Health Education Impact Questionnaire, particularly for use as a pre-test/post-test measure in experimental studies, other pre-post evaluation designs and system-level monitoring and evaluation.

Perceived Impact of Entrepreneurship Education on Career Development among Undergraduates in South-South Universities in Nigeria: Implication for Counselling

ERIC Educational Resources Information Center

Akpochafo, Grace Omejevwe; Alika, Ijeoma Henrietta

2018-01-01

This study investigated the perceived impact of entrepreneurship education on career development among undergraduates in south-south universities in Nigeria. To guide the study four research questions were generated and one hypothesis formulated, which was tested at 0.05 level of significance. The study employed an expost facto research design.…

The Effects of Individual versus Cooperative Testing in a Flipped Classroom on the Academic Achievement, Motivation toward Science, and Study Time for 9th Grade Biology Students

ERIC Educational Resources Information Center

McCall, Megan O'Neill

2017-01-01

This study examined the effects of cooperative testing versus traditional or individual testing and the impacts on academic achievement, motivation toward science, and study time for 9th grade biology students. Research questions centered on weekly quizzes given in a flipped classroom format for a period of 13 weeks. The study used a mixed methods…

Self-Monitoring of Blood Glucose Levels: Evaluating the Impact of a Policy of Quantity Limits on Test-Strip Use and Costs.

PubMed

Gomes, Tara; Martins, Diana; Tadrous, Mina; Paterson, J Michael; Shah, Baiju R; Juurlink, David N; Singh, Samantha; Mamdani, Muhammad M

2016-10-01

To evaluate the impact of new quantity limits for blood glucose test strips (BGTS) in August 2013 on utilization patterns and costs in the elderly population of Ontario, Canada. We conducted a population-based, cross-sectional time series analysis of all individuals 65 years of age and older who received publically funded BGTSs between August 1, 2010, and July 31, 2015, in Ontario, Canada. The number of BGTSs dispensed and the associated costs were measured for 4 diabetes therapy subgroups-insulin, hypoglycemia-inducing oral agents, non-hypoglycemia-inducing oral agents, and no drug therapy-each month during the study period. We used interventional autoregressive integrated moving average (ARIMA) models to assess the impact of Ontario's policy change on test strip use and costs. In the course of the study period, 657,338,177 test strips were dispensed to elderly patients in Ontario, at a total cost of CAN$482.3 million. Introduction of quantity limits was associated with significant reductions in the number of monthly strips dispensed and the associated costs (p<0.0001). In the year following the policy's implementation, test strip use decreased by 22.2% compared with the prior year (from 145,232,024 test strips to 113,007,795 test strips, a net decrease of 32,224,229 strips), resulting in a 22.5% reduction in costs (from $106.5 million to $82.6 million, a net cost reduction of approximately $24 million). The introduction of quantity limits, aligned with guidance from the Canadian Diabetes Association, led to immediate significant reductions in BGTS dispensing and costs. More research is needed to assess the impact of this policy on patient outcomes. Copyright © 2016 Canadian Diabetes Association. Published by Elsevier Inc. All rights reserved.

English Reading Placement Recommendations at College of the Canyons: An Analysis of Disproportionate Impact.

ERIC Educational Resources Information Center

Gerda, Joseph

A study was undertaken at California's College of the Canyons (CC) to determine whether evidence existed of disproportionate impact in English reading course placement based on student ethnicity, gender, or age. Data were compiled for all 4,312 students tested between spring 1993 and fall 1995, while the standard for disproportionate impact was…

The Impact of Intimate Partner Violence on Decisions to Leave Dating Relationships: A Test of the Investment Model

ERIC Educational Resources Information Center

Rhatigan, Deborah L.; Street, Amy E.

2005-01-01

This study explored the impact of violence exposure on investment-model constructs within a sample of college women involved in heterosexual dating relationships. Results generally supported the "common sense" hypothesis, suggesting that violence negatively impacts satisfaction for and commitment to one's relationship and is positively associated…

Desire for predictive testing for Alzheimer's disease and impact on advance care planning: a cross-sectional study.

PubMed

Sheffrin, Meera; Stijacic Cenzer, Irena; Steinman, Michael A

2016-12-13

It is unknown whether older adults in the United States would be willing to take a test predictive of future Alzheimer's disease, or whether testing would change behavior. Using a nationally representative sample, we explored who would take a free and definitive test predictive of Alzheimer's disease, and examined how using such a test may impact advance care planning. A cross-sectional study within the 2012 Health and Retirement Study of adults aged 65 years or older asked questions about a test predictive of Alzheimer's disease (N = 874). Subjects were asked whether they would want to take a hypothetical free and definitive test predictive of future Alzheimer's disease. Then, imagining they knew they would develop Alzheimer's disease, subjects rated the chance of completing advance care planning activities from 0 to 100. We classified a score > 50 as being likely to complete that activity. We evaluated characteristics associated with willingness to take a test for Alzheimer's disease, and how such a test would impact completing an advance directive and discussing health plans with loved ones. Overall, 75% (N = 648) of the sample would take a free and definitive test predictive of Alzheimer's disease. Older adults willing to take the test had similar race and educational levels to those who would not, but were more likely to be ≤75 years old (odds ratio 0.71 (95% CI 0.53-0.94)). Imagining they knew they would develop Alzheimer's, 81% would be likely to complete an advance directive, although only 15% had done so already. In this nationally representative sample, 75% of older adults would take a free and definitive test predictive of Alzheimer's disease. Many participants expressed intent to increase activities of advance care planning with this knowledge. This confirms high public interest in predictive testing for Alzheimer's disease and suggests this may be an opportunity to engage patients in advance care planning discussions.

Awareness, knowledge, perceptions, and attitudes towards genetic testing for cancer risk among ethnic minority groups: a systematic review.

PubMed

Hann, Katie E J; Freeman, Madeleine; Fraser, Lindsay; Waller, Jo; Sanderson, Saskia C; Rahman, Belinda; Side, Lucy; Gessler, Sue; Lanceley, Anne

2017-05-25

Genetic testing for risk of hereditary cancer can help patients to make important decisions about prevention or early detection. US and UK studies show that people from ethnic minority groups are less likely to receive genetic testing. It is important to understand various groups' awareness of genetic testing and its acceptability to avoid further disparities in health care. This review aims to identify and detail awareness, knowledge, perceptions, and attitudes towards genetic counselling/testing for cancer risk prediction in ethnic minority groups. A search was carried out in PsycInfo, CINAHL, Embase and MEDLINE. Search terms referred to ethnicity, genetic testing/counselling, cancer, awareness, knowledge, attitudes, and perceptions. Quantitative and qualitative studies, written in English, and published between 2000 and 2015, were included. Forty-one studies were selected for review: 39 from the US, and two from Australia. Results revealed low awareness and knowledge of genetic counselling/testing for cancer susceptibility amongst ethnic minority groups including African Americans, Asian Americans, and Hispanics. Attitudes towards genetic testing were generally positive; perceived benefits included positive implications for personal health and being able to inform family. However, negative attitudes were also evident, particularly the anticipated emotional impact of test results, and concerns about confidentiality, stigma, and discrimination. Chinese Australian groups were less studied, but of interest was a finding from qualitative research indicating that different views of who close family members are could impact on reported family history of cancer, which could in turn impact a risk assessment. Interventions are needed to increase awareness and knowledge of genetic testing for cancer risk and to reduce the perceived stigma and taboo surrounding the topic of cancer in ethnic minority groups. More detailed research is needed in countries other than the US and across a broader spectrum of ethnic minority groups to develop effective culturally sensitive approaches for cancer prevention.

Performance enhanced headgear: a scientific approach to the development of protective headgear.

PubMed

McIntosh, A; McCrory, P; Finch, C F

2004-02-01

There is a continuing debate about the performance of protective headgear in rugby union, rugby league, and Australian rules football. To examine the impact energy attenuation performance of foam that could be incorporated into headgear and examine the performance of prototypes of modified headgear. Impact tests were conducted on polyethylene foams and protective headgear. Free fall drop tests with a rigid headform on to a flat rigid anvil were conducted. Resultant headform acceleration was measured. Means of the headform acceleration maxima for repeat tests were calculated. Tests on polyethylene foam indicated that an increase in thickness from 10 mm to 16 mm would improve headgear performance. These modifications were incorporated in part into two headgear models: the Albion Headpro and the Canterbury brand Body Armour honeycomb headgear. The headgear tests show that significant reductions in headform acceleration were achieved by increasing the foam density and thickness. Mean headform acceleration maxima for the 16 mm thick modified rugby headgear was about 25% of that of standard headgear for lateral impact 0.3 and 0.4 m drop heights and 27% for the centre front 0.3 m drop tests. At these impacts, the headform acceleration for the modified rugby headgear was below 200 g. Significant improvements in impact energy attenuation performance are possible with small design changes. Whether these are sufficient to reduce the rate or severity of concussion in rugby and Australian rules football can only be shown by formal prospective studies on the field.

A Comparison of Quasi-Static Indentation Testing to Low Velocity Impact Testing

NASA Technical Reports Server (NTRS)

Nettles, Alan T.; Douglas, Michael J.

2001-01-01

The need for a static test method for modeling low-velocity foreign object impact events to composites would prove to be very beneficial to researchers since much more data can be obtained from a static test than from an impact test. In order to examine if this is feasible, a series of static indentation and low velocity impact tests were carried out and compared. Square specimens of many sizes and thickness were utilized to cover the array of types of low velocity impact events. Laminates with a n/4 stacking sequence were employed since this is by the most common type of engineering laminate. Three distinct flexural rigidities under two different boundary conditions were tested in order to obtain damage due to large deflections, contact stresses and both to examine if the static indentation-impact comparisons are valid under the spectrum of damage modes that can be experienced. Comparisons between static indentation and low velocity impact tests were based on the maximum applied transverse load. The dependent parameters examined included dent depth, back surface crack length, delamination area and to a limited extent, load-deflection behavior. Results showed that no distinct differences could be seen between the static indentation tests and the low velocity impact tests, indicating that static indentation can be used to represent a low velocity impact event.

Impact Testing on Reinforced Carbon-Carbon Flat Panels with Ice Projectiles for the Space Shuttle Return to Flight Program

NASA Technical Reports Server (NTRS)

Melis, Matthew E.; Revilock, Duane M.; Pereira, Michael J.; Lyle, Karen H.

2009-01-01

Following the tragedy of the Orbiter Columbia (STS-107) on February 1, 2003, a major effort commenced to develop a better understanding of debris impacts and their effect on the space shuttle subsystems. An initiative to develop and validate physics-based computer models to predict damage from such impacts was a fundamental component of this effort. To develop the models it was necessary to physically characterize reinforced carbon-carbon (RCC) along with ice and foam debris materials, which could shed on ascent and impact the orbiter RCC leading edges. The validated models enabled the launch system community to use the impact analysis software LS-DYNA (Livermore Software Technology Corp.) to predict damage by potential and actual impact events on the orbiter leading edge and nose cap thermal protection systems. Validation of the material models was done through a three-level approach: Level 1--fundamental tests to obtain independent static and dynamic constitutive model properties of materials of interest, Level 2--subcomponent impact tests to provide highly controlled impact test data for the correlation and validation of the models, and Level 3--full-scale orbiter leading-edge impact tests to establish the final level of confidence for the analysis methodology. This report discusses the Level 2 test program conducted in the NASA Glenn Research Center (GRC) Ballistic Impact Laboratory with ice projectile impact tests on flat RCC panels, and presents the data observed. The Level 2 testing consisted of 54 impact tests in the NASA GRC Ballistic Impact Laboratory on 6- by 6-in. and 6- by 12-in. flat plates of RCC and evaluated three types of debris projectiles: Single-crystal, polycrystal, and "soft" ice. These impact tests helped determine the level of damage generated in the RCC flat plates by each projectile and validated the use of the ice and RCC models for use in LS-DYNA.

Impact Testing on Reinforced Carbon-Carbon Flat Panels With BX-265 and PDL-1034 External Tank Foam for the Space Shuttle Return to Flight Program

NASA Technical Reports Server (NTRS)

Melis, Matthew E.; Revilock, Duane M.; Pereira, Michael J.; Lyle, Karen H.

2009-01-01

Following the tragedy of the Orbiter Columbia (STS-107) on February 1, 2003, a major effort commenced to develop a better understanding of debris impacts and their effect on the space shuttle subsystems. An initiative to develop and validate physics-based computer models to predict damage from such impacts was a fundamental component of this effort. To develop the models it was necessary to physically characterize reinforced carbon-carbon (RCC) along with ice and foam debris materials, which could shed on ascent and impact the orbiter RCC leading edges. The validated models enabled the launch system community to use the impact analysis software LS-DYNA (Livermore Software Technology Corp.) to predict damage by potential and actual impact events on the orbiter leading edge and nose cap thermal protection systems. Validation of the material models was done through a three-level approach: Level 1-fundamental tests to obtain independent static and dynamic constitutive model properties of materials of interest, Level 2-subcomponent impact tests to provide highly controlled impact test data for the correlation and validation of the models, and Level 3-full-scale orbiter leading-edge impact tests to establish the final level of confidence for the analysis methodology. This report discusses the Level 2 test program conducted in the NASA Glenn Research Center (GRC) Ballistic Impact Laboratory with external tank foam impact tests on flat RCC panels, and presents the data observed. The Level 2 testing consisted of 54 impact tests in the NASA GRC Ballistic Impact Laboratory on 6- by 6-in. and 6- by 12-in. flat plates of RCC and evaluated two types of debris projectiles: BX-265 and PDL-1034 external tank foam. These impact tests helped determine the level of damage generated in the RCC flat plates by each projectile and validated the use of the foam and RCC models for use in LS-DYNA.

Stair negotiation in women with fibromyalgia: A descriptive correlational study.

PubMed

Collado-Mateo, Daniel; Domínguez-Muñoz, Francisco J; Olivares, Pedro R; Adsuar, José C; Gusi, Narcis

2017-10-01

Walking up and down stairs is a common and important activity of daily living. Women with fibromyalgia often show a reduced ability to perform this task.The objective of this study was to evaluate the test-retest reliability of stair negotiation tasks and to assess the impact of fibromyalgia symptoms on the ability to negotiate stairs.Forty-two women with fibromyalgia participated in this descriptive correlational study. The relevance of the stair negotiation (both walking up and down) was evaluated by assessing its association with the revised version of the fibromyalgia impact questionnaire (FIQ-R) and other health-related variables. Test-retest reliability was also analyzed. The main outcome measures were time spent walking up and down stairs and impact of fibromyalgia, quality of life, number of falls, weight, and lower limb strength and endurance.The intraclass correlation coefficient (ICC) for stair descent was 0.929 whereas that for ascent was 0.972. The score in these tests correlated significantly with the total score for the FIQ-R and the score for many of dimensions and symptoms: that is, physical function, overall impact of fibromyalgia, pain, energy, stiffness, restorative sleep, tenderness, self-perceived balance problems, and sensitivity.Given the importance of the stair negotiation as activity of daily living and the high reliability, both stair ascent and descent tasks may be useful as outcome measures in studies on patients with fibromyalgia.

Impact on learning of an e-learning module on leukaemia: a randomised controlled trial.

PubMed

Morgulis, Yuri; Kumar, Rakesh K; Lindeman, Robert; Velan, Gary M

2012-05-28

e-learning resources may be beneficial for complex or conceptually difficult topics. Leukaemia is one such topic, yet there are no reports on the efficacy of e-learning for leukaemia. This study compared the learning impact on senior medical students of a purpose-built e-learning module on leukaemia, compared with existing online resources. A randomised controlled trial was performed utilising volunteer senior medical students. Participants were randomly allocated to Study and Control groups. Following a pre-test on leukaemia administered to both groups, the Study group was provided with access to the new e-learning module, while the Control group was directed to existing online resources. A post-test and an evaluation questionnaire were administered to both groups at the end of the trial period. Study and Control groups were equivalent in gender distribution, mean academic ability, pre-test performance and time studying leukaemia during the trial. The Study group performed significantly better than the Control group in the post-test, in which the group to which the students had been allocated was the only significant predictor of performance. The Study group's evaluation of the module was overwhelmingly positive. A targeted e-learning module on leukaemia had a significant effect on learning in this cohort, compared with existing online resources. We believe that the interactivity, dialogic feedback and integration with the curriculum offered by the e-learning module contributed to its impact. This has implications for e-learning design in medicine and other disciplines.

Biomechanical responses of PMHS in moderate-speed rear impacts and development of response targets for evaluating the internal and external biofidelity of ATDS.

PubMed

Kang, Yun-Seok; Bolte, John H; Moorhouse, Kevin; Donnelly, Bruce; Herriott, Rodney; Mallory, Ann

2012-10-01

The objectives of this study were to obtain biomechanical responses of post mortem human subjects (PMHS) by subjecting them to two moderate-speed rear impact sled test conditions (8.5g, 17 km/h; 10.5g, 24 km/h) while positioned in an experimental seat system, and to create biomechanical targets for internal and external biofidelity evaluation of rear impact ATDs. The experimental seat was designed to measure external loads on the head restraint (4 load cells), seat back (6 load cells), and seat pan (4 load cells) such that subject dynamic interaction with the seat could be evaluated. This seat system was capable of simulating the dynamic characteristics of modern vehicle seat backs by considering the moment-rotation properties of a typical passenger vehicle, thus providing a more realistic test environment than using a rigid seat with a non-rotating seat back as done in previous studies. Instrumentation used to measure biomechanical responses of the PMHS included both accelerometers and angular rate sensors (ARS). A total of fourteen sled tests using eight PMHS (males 175.8 ± 6.2 cm of stature and 78.4 ± 7.2 kg of weight) provided data sets of seven PMHS for both test conditions. The biomechanical responses are described at both speeds, and cervical spine injuries are documented. Biomechanical targets are also created for internal and external biofidelity evaluation of rear impact anthropomorphic test devices (ATDs).

Physical basis of tap test as a quantitative imaging tool for composite structures on aircraft

NASA Astrophysics Data System (ADS)

Hsu, David K.; Barnard, Daniel J.; Peters, John J.; Dayal, Vinay

2000-05-01

Tap test is a simple but effective way for finding flaws in composite and honeycomb sandwich structures; it has been practiced in aircraft inspection for decades. The mechanics of tap test was extensively researched by P. Cawley et al., and several versions of instrumented tap test have emerged in recent years. This paper describes a quantitative study of the impact duration as a function of the mass, radius, velocity, and material property of the impactor. The impact response is compared to the predictions of Hertzian-type contact theory and a simple spring model. The electronically measured impact duration, τ, is used for generating images of the tapped region. Using the spring model, the images are converted into images of a spring constant, k, which is a measure of the local contact stiffness. The images of k, largely independent of tapper mass and impact velocity, reveal the size, shape and severity (cf. Percent stiffness reduction) of defects and damages, as well as the presence of substructures and the associated stiffness increase. The studies are carried out on a variety of real aircraft components and the results serve to guide the development of a fieldable tap test imaging system for aircraft inspection.—This material is based upon work supported by the Federal Aviation Administration under Contract #DTFA03-98-D-00008, Delivery Order No. IA016 and performed at Iowa State University's Center for NDE as part of the Center for Aviation Systems Reliability program.

Development and Evaluation of Stitched Sandwich Panels

NASA Technical Reports Server (NTRS)

Stanley, Larry E.; Adams, Daniel O.; Reeder, James R. (Technical Monitor)

2001-01-01

This study explored the feasibility and potential benefits provided by the addition of through-the-thickness reinforcement to sandwich structures. Through-the-thickness stitching is proposed to increase the interlaminar strength and damage tolerance of composite sandwich structures. A low-cost, out-of-autoclave processing method was developed to produce composite sandwich panels with carbon fiber face sheets, a closed-cell foam core, and through-the-thickness Kevlar stitching. The sandwich panels were stitched in a dry preform state, vacuum bagged, and infiltrated using Vacuum Assisted Resin Transfer Molding (VARTM) processing. For comparison purposes, unstitched sandwich panels were produced using the same materials and manufacturing methodology. Test panels were produced initially at the University of Utah and later at NASA Langley Research Center. Four types of mechanical tests were performed: flexural testing, flatwise tensile testing, core shear testing, and edgewise compression testing. Drop-weight impact testing followed by specimen sectioning was performed to characterize the damage resistance of stitched sandwich panels. Compression after impact (CAI) testing was performed to evaluate the damage tolerance of the sandwich panels. Results show significant increases in the flexural stiffness and strength, out-of-plane tensile strength, core shear strength, edgewise compression strength, and compression-after-impact strength of stitched sandwich structures.

Microstructural Modification of Sn-0.7Cu Solder Alloys by Fe/Bi-Addition for Achieving High Mechanical Performance

NASA Astrophysics Data System (ADS)

Ali, Bakhtiar; Sabri, Mohd Faizul Mohd; Said, Suhana Mohd; Mahdavifard, Mohammad Hossein; Sukiman, Nazatul Liana; Jauhari, Iswadi

2017-08-01

In this work, we studied the Fe/Bi-bearing tin-copper (Sn-0.7Cu) solders for their microstructural and mechanical properties. The microstructure was studied using field emission scanning electron microscopy (FESEM) with a backscattered electron (BSE) detector, x-ray diffraction (XRD) analysis, and energy-dispersive x-ray spectroscopy (EDX). The microstructure study showed that Fe forms very few FeSn2 intermetallic compounds (IMCs) and does not significantly alter the microstructure of Sn-0.7Cu, whereas Bi controls the size of inter-dendritic regions containing Cu6Sn5 and Ag3Sn IMCs of the alloy, as well as significantly refines its primary β-Sn dendrites. Moreover, Bi atoms dissolve in β-Sn matrix, which in turn strengthen the solder by the Bi solid solution strengthening mechanism. Such microstructural modification leads to significant improvements in various mechanical properties of the alloy, including shear strength, impact toughness, and hardness values. Shear tests were performed with a 0.25 mm/min shear speed. The results showed that shear strength improves from 16.57 MPa to 38.36 MPa with the addition of Fe/Bi to Sn-0.7Cu, raising by about 130%. The energy absorbed during impact tests was measured for samples with the help of a Charpy impact testing machine with a 5.4 m/s impact speed. The results revealed that the addition of Fe/Bi to Sn-0.7Cu improves its impact absorbed energy by over 35%, increasing it from 7.5 J to 10.3 J. Vickers hardness tests were carried out for the test samples with a 245.2 mN applied load and 10 s dwell time. The results showed that the hardness number improves from 9.89 to 24.13 with Fe/Bi to Sn-0.7Cu, increasing by about 140%.

Uptake contexts and perceived impacts of HIV testing and counselling among adults in East and Southern Africa: A meta-ethnographic review.

PubMed

Witzel, T Charles; Lora, Wezzie; Lees, Shelley; Desmond, Nicola

2017-01-01

HIV testing and counselling (HTC) interventions are key to controlling the HIV epidemic in East and Southern Africa where HTC is primarily delivered through voluntary counselling and testing (VCT), provider initiated testing and counselling (PITC), and home-based counselling and testing (HBVCT). Decision making processes around uptake of HTC models must be taken into account when designing new interventions. Counselling in HTC aims to reduce post-test risk taking behaviour and to link individuals to care but its efficacy is unclear. This meta-ethnography aims to understand the contexts of HTC uptake in East and Southern Africa and to analyse the perceived impacts of counselling-based interventions in relation to sexual behaviour and linkage to care. We conducted a systematic literature review of studies investigating HTC in East and Southern Africa from 2003 -April 2014. The search and additional snowballing identified 20 studies that fit our selection criteria. These studies were synthesised through a thematic framework analysis. Twenty qualitative and mixed-methods studies examining impacts of HTC models in East and Southern Africa were meta-synthesised. VCT decisions were made individually while HBVCT decisions were located in family and community units. PITC was associated with coercion from healthcare providers. Low quality counselling components and multiple-intersecting barriers faced by individuals mean that counselling in HTC was not perceived to be effective in reducing post-test risk behaviour and had limited perceived effect in facilitating linkage to care. HBVCT is associated with minimal stigma and should be considered as an area of priority. Counselling components in HTC interventions were effective in transmitting information about HIV and sexual risk, but were perceived as ineffective in addressing the broader personal circumstances preventing sexual behaviour change and modulating access to care.

The Impact of Teach for America on Non-Test Academic Outcomes

ERIC Educational Resources Information Center

Backes, Ben; Hansen, Michael

2018-01-01

Recent evidence on teacher productivity suggests that teachers meaningfully influence non-test academic student outcomes that are commonly overlooked by narrowly focusing on test scores. Despite a large number of studies investigating the Teach For America (TFA) effect on math and English achievement, little is known about non-tested academic…

The Impact of Partial Measurement Invariance on Testing Moderation for Single and Multi-Level Data

PubMed Central

Hsiao, Yu-Yu; Lai, Mark H. C.

2018-01-01

Moderation effect is a commonly used concept in the field of social and behavioral science. Several studies regarding the implication of moderation effects have been done; however, little is known about how partial measurement invariance influences the properties of tests for moderation effects when categorical moderators were used. Additionally, whether the impact is the same across single and multilevel data is still unknown. Hence, the purpose of the present study is twofold: (a) To investigate the performance of the moderation test in single-level studies when measurement invariance does not hold; (b) To examine whether unique features of multilevel data, such as intraclass correlation (ICC) and number of clusters, influence the effect of measurement non-invariance on the performance of tests for moderation. Simulation results indicated that falsely assuming measurement invariance lead to biased estimates, inflated Type I error rates, and more gain or more loss in power (depends on simulation conditions) for the test of moderation effects. Such patterns were more salient as sample size and the number of non-invariant items increase for both single- and multi-level data. With multilevel data, the cluster size seemed to have a larger impact than the number of clusters when falsely assuming measurement invariance in the moderation estimation. ICC was trivially related to the moderation estimates. Overall, when testing moderation effects with categorical moderators, employing a model that accounts for the measurement (non)invariance structure of the predictor and/or the outcome is recommended. PMID:29867692

The Impact of Partial Measurement Invariance on Testing Moderation for Single and Multi-Level Data.

PubMed

Hsiao, Yu-Yu; Lai, Mark H C

2018-01-01

Moderation effect is a commonly used concept in the field of social and behavioral science. Several studies regarding the implication of moderation effects have been done; however, little is known about how partial measurement invariance influences the properties of tests for moderation effects when categorical moderators were used. Additionally, whether the impact is the same across single and multilevel data is still unknown. Hence, the purpose of the present study is twofold: (a) To investigate the performance of the moderation test in single-level studies when measurement invariance does not hold; (b) To examine whether unique features of multilevel data, such as intraclass correlation (ICC) and number of clusters, influence the effect of measurement non-invariance on the performance of tests for moderation. Simulation results indicated that falsely assuming measurement invariance lead to biased estimates, inflated Type I error rates, and more gain or more loss in power (depends on simulation conditions) for the test of moderation effects. Such patterns were more salient as sample size and the number of non-invariant items increase for both single- and multi-level data. With multilevel data, the cluster size seemed to have a larger impact than the number of clusters when falsely assuming measurement invariance in the moderation estimation. ICC was trivially related to the moderation estimates. Overall, when testing moderation effects with categorical moderators, employing a model that accounts for the measurement (non)invariance structure of the predictor and/or the outcome is recommended.

Serologic Screening for Herpes Simplex Virus Among University Students: A Pilot Study

PubMed Central

Mark, Hayley; Nanda, Joy P.; Joffe, Alain; Roberts, Jessica; Rompalo, Anne; Melendez, Johan; Zenilman, Jonathan

2009-01-01

Objective The authors examined the feasibility of conducting serologic testing for the herpes simplex virus 2 (HSV-2) among university students and assessed the psychosocial impact of an HSV-2 diagnosis. Methods The authors recruited a convenience sample of 100 students (aged 18–39 years) without a history of genital herpes from 1 university between September 2004 and March 2006. Participants received HSV-2 antibody testing by Focus ELISA and Western Blot assays and completed a questionnaire that addressed psychological functioning. Twenty-eight participants completed the questionnaire again at a 3-month follow-up visit. Results The study revealed (1) low test-reliability in the student population, (2) that positive test results may cause a decline in psychological well-being, and (3) that substantial resources are required to support students with positive HSV-2 results. Conclusions Test performance, psychological impact, and availability of resources for counseling students with positive diagnoses should be considered before implementing HSV testing programs. PMID:18980884

Methods for evaluating the biological impact of potentially toxic waste applied to soils

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

Neuhauser, E.F.; Loehr, R.C.; Malecki, M.R.

1985-12-01

The study was designed to evaluate two methods that can be used to estimate the biological impact of organics and inorganics that may be in wastes applied to land for treatment and disposal. The two methods were the contact test and the artificial soil test. The contact test is a 48 hr test using an adult worm, a small glass vial, and filter paper to which the test chemical or waste is applied. The test is designed to provide close contact between the worm and a chemical similar to the situation in soils. The method provides a rapid estimate ofmore » the relative toxicity of chemicals and industrial wastes. The artificial soil test uses a mixture of sand, kaolin, peat, and calcium carbonate as a representative soil. Different concentrations of the test material are added to the artificial soil, adult worms are added and worm survival is evaluated after two weeks. These studies have shown that: earthworms can distinguish between a wide variety of chemicals with a high degree of accuracy.« less

A comparison of apical root resorption after orthodontic treatment with surgical exposure and traction of maxillary impacted canines versus that without impactions.

PubMed

Lempesi, Evangelia; Pandis, Nikolaos; Fleming, Padhraig S; Mavragani, Maria

2014-12-01

Orthodontic management of maxillary canine impaction (MCI), including forced eruption, may result in significant root resorption; however, the association between MCI and orthodontically induced root resorption (OIRR) is not yet sufficiently established. The purpose of this retrospective cohort study was to comparatively evaluate the severity of OIRR of maxillary incisors in orthodontically treated patients with MCI. Additionally, impaction characteristics were associated with OIRR severity. The sample comprised 48 patients undergoing fixed-appliance treatment-24 with unilateral/bilateral MCI and 24 matched controls without impaction. OIRR was calculated using pre- and post-operative panoramic tomograms. The orientation of eruption path, height, sector location, and follicle/tooth ratio of the impacted canine were also recorded. Mann-Whitney U-test and univariate and multivariate linear mixed models were used to test for the associations of interest. Maxillary central left incisor underwent more OIRR in the impaction group (mean difference = 0.58mm, P = 0.04). Overall, the impaction group had 0.38mm more OIRR compared to the control (95% confidence interval, CI: 0.03, 0.74; P = 0.04). However, multivariate analysis demonstrated no difference in the amount of OIRR between impaction and non-impaction groups overall. A positive association between OIRR and initial root length was observed (95% CI: 0.08, 0.27; P < 0.001). The severity of canine impaction was not found to be a significant predictor of OIRR. This study was a retrospective study and used panoramic tomograms for OIRR measurements. This study indicates that MCI is a weak OIRR predictor. Interpretation of the results needs caution due to the observational nature of the present study. © The Author 2014. Published by Oxford University Press on behalf of the European Orthodontic Society. All rights reserved. For permissions, please email: journals.permissions@oup.com.

Crash simulation of UNS electric vehicle under frontal front impact

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

Susilo, D. D., E-mail: djoksus-2010@yahoo.com; Lukamana, N. I., E-mail: n.indra.lukmana@gmail.com; Budiana, E. P., E-mail: budiana.e@gmail.com

Sebelas Maret University has been developing an Electric Vehicle namely SmarT-EV UNS. The main structure of the car are chasis and body. The chasis is made from steel and the body is made from fiberglass composite. To ensure the safety of the car, both static and dynamic tests were carried out to these structures, including their materials, like: tensile test, bending test, and impact test. Another test needed by this vehicle is crashworthiness test. To perform the test, it is needed complex equipments and it is quite expensive. Another way to obtain vehicle crashworthiness behaviour is by simulate it. Themore » purpose of this study was to simulate the response of the Smart-EV UNS electric vehicle main structure when crashing rigid barrier from the front. The crash simulation was done in according to the NHTSA (National Highway Traffic Safety Administration) within the speed of the vehicle of 35 mph. The UNS Electric Vehicle was modelled using SolidWorks software, and the simulation process was done by finite element method using ANSYS software. The simulation result showed that the most internal impact energy was absorbed by chassis part. It absorbed 76.2% of impact energy, then the base absorbed 11.3 %, while the front body absorbed 2.5 %, and the rest was absorbed by fender, hood, and other parts.« less

Service-learning's impact on dental students' attitude towards community service.

PubMed

Coe, J M; Best, A M; Warren, J J; McQuistan, M R; Kolker, J L; Isringhausen, K T

2015-08-01

This study evaluated service-learning programme's impact on senior dental students' attitude towards community service at Virginia Commonwealth University (VCU) School of Dentistry. Experience gained through service-learning in dental school may positively impact dental students' attitude towards community service that will eventually lead into providing care to the underserved. Two surveys (pre- and post-test) were administered to 105 senior dental students. For the first survey (post-test), seventy-six students of 105 responded and reported their attitude towards community service immediately after the service-learning programme completion. Three weeks later, 56 students of the 76 responded to the second survey (retrospective pre-test) and reported their recalled attitude prior to the programme retrospectively. A repeated-measure mixed-model analysis indicated that overall there was improvement between pre-test and post-test. Scales of connectedness, normative helping behaviour, benefits, career benefits and intention showed a significant pre-test and post-test difference. An association between attitude towards community service and student characteristics such as age, gender, ethnicity and volunteer activity was also examined. Only ethnicity showed an overall significant difference. White dental students appear to have a differing perception of the costs of community service. The service-learning programme at VCU School of Dentistry has positively impacted senior dental students' attitude towards community service. © 2014 John Wiley & Sons A/S. Published by John Wiley & Sons Ltd.

Service-learning’s Impact on Dental Students’ Attitude toward Community Service

PubMed Central

Coe, J. M.; Best, A. M.; Warren, J. J.; McQuistan, M. R.; Kolker, J. L.; Isringhausen, K. T.

2014-01-01

Introduction This study evaluated service-learning program’s impact on senior dental students’ attitude toward community service at Virginia Commonwealth University (VCU) School of Dentistry. Experience gained through service-learning in dental school may positively impact dental students’ attitude toward community service that will eventually lead into providing care to the underserved. Materials and methods Two surveys (pre and post-test) were administered to 105 senior dental students. For the first survey (post-test), seventy six students out of 105 responded and reported their attitude toward community service immediately after the service-learning program completion. Three weeks later, fifty six students out of the 76 responded to the second survey (retrospective pre-test) and reported their recalled attitude prior to the program retrospectively. Results A repeated-measure mixed-model analysis indicated that overall there was improvement between pre-test and post-test. Scales of connectedness, normative helping behavior, benefits1, career benefits, and intention showed a significant pre-test and post-test difference. An association between attitude toward community service and student characteristics such as age, gender, ethnicity, and volunteer activity was also examined. Only ethnicity showed an overall significant difference. White dental students appear to have a differing perception of the costs of community service. Conclusions The service-learning program at VCU School of Dentistry has positively impacted senior dental students’ attitude toward community service. PMID:25142286

Cognitive impact after short-term exposure to different proton pump inhibitors: assessment using CANTAB software.

PubMed

Akter, Sanjida; Hassan, Md Rajib; Shahriar, Mohammad; Akter, Nahia; Abbas, Md Golam; Bhuiyan, Mohiuddin Ahmed

2015-12-27

Studies have shown that proton pump inhibitors (PPIs) increase the brain burden of amyloid-beta (Aβ) and also create vitamin B12 deficiency. However, these two phenomena have deleterious effect on cognition and Alzheimer's disease (AD). Since the use of PPIs has increased tremendously for the last few years, it is of great public health importance to investigate the cognitive impact of PPIs. Hence, the purpose of this study was to investigate the degree of neuropsychological association of each PPI with different cognitive functions. Sixty volunteers of either gender were recruited and divided randomly into six groups: five test groups for five classes of PPIs and one control group. All the groups participated in the five computerized neuropsychological tests (nine subtests) of the Cambridge Neuropsychological Test Automated Battery twice: at the beginning of the study and 7 days thereafter. We found statistically and clinically significant impairment in visual memory, attention, executive function, and working and planning function. One-way analysis of variance findings showed that all PPIs had a similar negative impact on cognition. However, paired-samples t tests indicated that omeprazole showed significant (p < 0.05) results in seven subtests; lansoprazole and pantoprazole showed significant results in five subtests; and rabeprazole showed significant results in four subtests. Among five classes of PPIs, esomeprazole showed comparatively less impact on cognitive function with significant results in three subtests. The present study reveals for the first time that different PPIs have varying degrees of influence on different cognitive domains and have associations with AD. These findings should be considered when balancing the risks and benefits of prescribing these medications. A study done for a longer period of time with a larger sample size might yield better results.

Comparative Evaluation of Immediate Post-Operative Sequelae after Surgical Removal of Impacted Mandibular Third Molar with or without Tube Drain - Split-Mouth Study

PubMed Central

Bhate, Kalyani; Dolas, RS; Kumar, SN Santhosh; Waknis, Pushkar

2016-01-01

Introduction Third molar surgery is one of the most common surgical procedures performed in general dentistry. Post-operative variables such as pain, swelling and trismus are major concerns after impacted mandibular third molar surgery. Use of passive tube drain is supposed to help reduce these immediate post-operative sequelae. The current study was designed to compare the effect of tube drain on immediate post-operative sequelae following impacted mandibular third molar surgery. Aim To compare the post-operative sequelae after surgical removal of impacted mandibular third molar surgery with or without tube drain. Materials and Methods Thirty patients with bilateral impacted mandibular third molars were divided into two groups: Test (with tube drain) and control (without tube drain) group. In the test group, a tube drain was inserted through the releasing incision, and kept in place for three days. The control group was left without a tube drain. The post-operative variables like, pain, swelling, and trismus were calculated after 24 hours, 72 hours, 7 days, and 15 days in both the groups and analyzed statistically using chi-square and t-test analysis. Results The test group showed lesser swelling as compared to control group, with the swelling variable showing statistically significant difference at post-operative day 3 and 7 (p≤ 0.05) in both groups. There were no statistically significant differences in pain and trismus variables in both the groups. Conclusion The use of tube drain helps to control swelling following impacted mandibular third molar surgery. However, it does not have much effect on pain or trismus. PMID:28209003

A Malay version of the Child Oral Impacts on Daily Performances (Child-OIDP) index: assessing validity and reliability.

PubMed

Yusof, Zamros Y M; Jaafar, Nasruddin

2012-06-08

The study aimed to develop and test a Malay version of the Child-OIDP index, evaluate its psychometric properties and report on the prevalence of oral impacts on eight daily performances in a sample of 11-12 year old Malaysian schoolchildren. The Child-OIDP index was translated from English into Malay. The Malay version was tested for reliability and validity on a non-random sample of 132, 11-12 year old schoolchildren from two urban schools in Kuala Lumpur. Psychometric analysis of the Malay Child-OIDP involved face, content, criterion and construct validity tests as well as internal and test-retest reliability. Non-parametric statistical methods were used to assess relationships between Child-OIDP scores and other subjective outcome measures. The standardised Cronbach's alpha was 0.80 and the weighted Kappa was 0.84 (intraclass correlation = 0.79). The index showed significant associations with different subjective measures viz. perceived satisfaction with mouth, perceived needs for dental treatment, perceived oral health status and toothache experience in the previous 3 months (p < 0.05). Two-thirds (66.7%) of the sample had oral impacts affecting one or more performances in the past 3 months. The three most frequently affected performances were cleaning teeth (36.4%), eating foods (34.8%) and maintaining emotional stability (26.5%). In terms of severity of impact, the ability to relax was most severely affected by their oral conditions, followed by ability to socialise and doing schoolwork. Almost three-quarters (74.2%) of schoolchildren with oral impacts had up to three performances affected by their oral conditions. This study indicated that the Malay Child-OIDP index is a valid and reliable instrument to measure the oral impacts of daily performances in 11-12 year old urban schoolchildren in Malaysia.

Human-Robot Collaboration Dynamic Impact Testing and Calibration Instrument for Disposable Robot Safety Artifacts

PubMed Central

Dagalakis, Nicholas G.; Yoo, Jae Myung; Oeste, Thomas

2017-01-01

The Dynamic Impact Testing and Calibration Instrument (DITCI) is a simple instrument with a significant data collection and analysis capability that is used for the testing and calibration of biosimulant human tissue artifacts. These artifacts may be used to measure the severity of injuries caused in the case of a robot impact with a human. In this paper we describe the DITCI adjustable impact and flexible foundation mechanism, which allows the selection of a variety of impact force levels and foundation stiffness. The instrument can accommodate arrays of a variety of sensors and impact tools, simulating both real manufacturing tools and the testing requirements of standards setting organizations. A computer data acquisition system may collect a variety of impact motion, force, and torque data, which are used to develop a variety of mathematical model representations of the artifacts. Finally, we describe the fabrication and testing of human abdomen soft tissue artifacts, used to display the magnitude of impact tissue deformation. Impact tests were performed at various maximum impact force and average pressure levels. PMID:28579658

Human-Robot Collaboration Dynamic Impact Testing and Calibration Instrument for Disposable Robot Safety Artifacts.

PubMed

Dagalakis, Nicholas G; Yoo, Jae Myung; Oeste, Thomas

2016-01-01

The Dynamic Impact Testing and Calibration Instrument (DITCI) is a simple instrument with a significant data collection and analysis capability that is used for the testing and calibration of biosimulant human tissue artifacts. These artifacts may be used to measure the severity of injuries caused in the case of a robot impact with a human. In this paper we describe the DITCI adjustable impact and flexible foundation mechanism, which allows the selection of a variety of impact force levels and foundation stiffness. The instrument can accommodate arrays of a variety of sensors and impact tools, simulating both real manufacturing tools and the testing requirements of standards setting organizations. A computer data acquisition system may collect a variety of impact motion, force, and torque data, which are used to develop a variety of mathematical model representations of the artifacts. Finally, we describe the fabrication and testing of human abdomen soft tissue artifacts, used to display the magnitude of impact tissue deformation. Impact tests were performed at various maximum impact force and average pressure levels.

A National Survey of Middle and High School Science Teachers' Responses to Standardized Testing: Is Science Being Devalued in Schools?

ERIC Educational Resources Information Center

Aydeniz, Mehmet; Southerland, Sherry A.

2012-01-01

This study explored American high school and middle school science teachers' attitudes toward the use of standardized testing for accountability purposes, their justification for the attitudes they hold and the impact of standardized testing on their instructional and assessment practices. A total of 161 science teachers participated in the study.…

Impact of Inclusion or Exclusion of Repeaters on Test Equating

ERIC Educational Resources Information Center

Puhan, Gautam

2011-01-01

This study examined the effect of including or excluding repeaters on the equating process and results. New forms of two tests were equated to their respective old forms using either all examinees or only the first timer examinees in the new form sample. Results showed that for both tests used in this study, including or excluding repeaters in the…

Understanding the Role of "SES," Ethnicity, and Discipline Infractions in Students' Standardized Test Scores

ERIC Educational Resources Information Center

Koca, Fatih

2017-01-01

The goal of the current study is to examine the impact of students' social economic status, ethnicity, and discipline infractions on their standardized test scores in Indiana, the USA. Data from this study extracted from Indiana Department of Education. ISTEP is a criterion-referenced standardized test. It consists of items that assess a student's…

Pedestrian headform testing: inferring performance at impact speeds and for headform masses not tested, and estimating average performance in a range of real-world conditions.

PubMed

Hutchinson, T Paul; Anderson, Robert W G; Searson, Daniel J

2012-01-01

Tests are routinely conducted where instrumented headforms are projected at the fronts of cars to assess pedestrian safety. Better information would be obtained by accounting for performance over the range of expected impact conditions in the field. Moreover, methods will be required to integrate the assessment of secondary safety performance with primary safety systems that reduce the speeds of impacts. Thus, we discuss how to estimate performance over a range of impact conditions from performance in one test and how this information can be combined with information on the probability of different impact speeds to provide a balanced assessment of pedestrian safety. Theoretical consideration is given to 2 distinct aspects to impact safety performance: the test impact severity (measured by the head injury criterion, HIC) at a speed at which a structure does not bottom out and the speed at which bottoming out occurs. Further considerations are given to an injury risk function, the distribution of impact speeds likely in the field, and the effect of primary safety systems on impact speeds. These are used to calculate curves that estimate injuriousness for combinations of test HIC, bottoming out speed, and alternative distributions of impact speeds. The injuriousness of a structure that may be struck by the head of a pedestrian depends not only on the result of the impact test but also the bottoming out speed and the distribution of impact speeds. Example calculations indicate that the relationship between the test HIC and injuriousness extends over a larger range than is presently used by the European New Car Assessment Programme (Euro NCAP), that bottoming out at speeds only slightly higher than the test speed can significantly increase the injuriousness of an impact location and that effective primary safety systems that reduce impact speeds significantly modify the relationship between the test HIC and injuriousness. Present testing regimes do not take fully into account the relationship between impact severity and variations in impact conditions. Instead, they assess injury risk at a single impact speed. Hence, they may fail to differentiate risks due to the effects of bottoming out under different impact conditions. Because the level of injuriousness changes across a wide range of HIC values, even slight improvements to very stiff structures need to be encouraged through testing. Indications are that the potential of autonomous braking systems is substantial and needs to be weighted highly in vehicle safety assessments.

Notched bar Izod impact properties of zinc die castings

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

Schrems, K.K.; Dogan, O.N.; Goodwin, F.E.

2007-03-01

Notched bar Izod impact testing of zinc die cast Alloy 3, Alloy 5, ZA-8, and AcuZinc 5 was performed at five temperatures between -40\\mDC and room temperature in accordance with ASTM E23 for impact testing of metallic materials. A direct comparison between ASTM D256 for impact testing of plastics and ASTM E23 was performed using continuously cast zinc specimens of Alloy 5 and ZA-8 at -40\\mDC and room temperature. There are differences in sample sizes, impact velocity, and striker geometry between the two tests. Bulk zinc tested according to ASTM E23 resulted in higher impact energies at -40\\mDC and lowermore » impact energies at room temperature then did the same alloys when tested according to ASTM D256.« less

An Exploratory Study of Listening Practice Relative to Memory Testing and Lecture in Business Administration Courses

ERIC Educational Resources Information Center

Peterson, Robin T.

2007-01-01

This study investigates the combined impact of a memory test and subsequent listening practice in enhancing student listening abilities in collegiate business administration courses. The article reviews relevant literature and describes an exploratory study that was undertaken to compare the effectiveness of this technique with traditional…

Assessment of damage in 'green' composites

NASA Astrophysics Data System (ADS)

Malinowski, Paweł H.; Ostachowicz, Wiesław M.; Touchard, Fabienne; Boustie, Michel; Chocinski-Arnault, Laurence; Pascual Gonzalez, Pedro; Berthe, Laurent; de Vasconcellos, Davi; Sorrentino, Luigi

2017-04-01

The behaviour of eco-composites, when subjected to laser or mechanical impact loadings, is not well known yet. A research was proposed looking at the behaviour of `green' and synthetic composites under impact loading. The study was focused on composites reinforced with short, medium and long fibres. Short fibre composites were made of spruce fibres and ABS. The fibres were used both as received and after a thermal treatment. Another set of samples was made of 60 mm-long flax fibres. Two types of thermoplastic polymers were used as matrices: polypropylene and polylactide. Also a woven eco-composite was investigated. It was made of plain woven hemp fabric impregnated with epoxy resin. A fully synthetic woven composite, used as reference laminate for comparison with `green' composites, was prepared by using a plain weave woven glass fabric impregnated with epoxy resin. Mechanical impacts were performed by means of a falling dart impact testing machine. The specimens were tested at different impact energy levels (from 1J to 5J) by keeping constant the mass of the impactor and varying the drop height. Laser impact tests were performed by means of a high power laser shock facility. All the samples were tested at six different laser shock intensities, keeping constant the shock diameter and the pulse duration. Six assessment techniques were employed in order to analyse and compare impact damages: eye observation, back face relief, terahertz spectroscopy, laser vibrometry, X-ray micro-tomography and microscopic observations. Different damage detection thresholds for each material and technique were obtained.

Impact of effective versus sham continuous positive airway pressure on liver injury in obstructive sleep apnoea: Data from randomized trials.

PubMed

Jullian-Desayes, Ingrid; Tamisier, Renaud; Zarski, Jean-Pierre; Aron-Wisnewsky, Judith; Launois-Rollinat, Sandrine H; Trocme, Candice; Levy, Patrick; Joyeux-Faure, Marie; Pepin, Jean-Louis

2016-02-01

Obstructive sleep apnoea (OSA) could be an independent risk factor for non-alcoholic fatty liver disease (NAFLD) occurrence and progression. The impact of continuous positive airway pressure (CPAP) treatment on non-invasive markers of NAFLD has not been studied. The aim of this study was to evaluate the effect of 6-12 weeks of effective CPAP on the FibroMax test (comprising components including the SteatoTest, NashTest and FibroTest) through three randomized sham controlled studies. The FibroMax test was performed in 103 obstructive sleep apnoea patients (apnoea + hypopnoea index > 15/h) enrolled in a randomized study comparing sham versus effective CPAP. At baseline, 40.4% of patients in the sham CPAP group and 45.5% in the CPAP group exhibited liver steatosis. Furthermore, 39.6% of patients in the sham CPAP group and 58.4% in the CPAP group displayed borderline or possible non-alcoholic steatohepatitis (NASH). Six to twelve weeks of effective CPAP did not demonstrate any impact on reducing steatosis, NASH or liver fibrosis even after adjustment for gender, BMI, baseline apnoea + hypopnoea index and severity of liver injury. A number of non-invasive markers of liver damage are increased in untreated obstructive sleep apnoea patients, potentially contributing to cardiometabolic risk, but they do not improve after 6-12 weeks of effective CPAP treatment. NCT01196845 (ADISAS), NCT00464659 (MneSAS) and NCT00669695 (StatinflaSAS) at ClinicalTrials.gov. © 2015 Asian Pacific Society of Respirology.

A study on ground truth data for impact damaged polymer matrix composites

NASA Astrophysics Data System (ADS)

Wallentine, Sarah M.; Uchic, Michael D.

2018-04-01

This study presents initial results toward correlative characterization of barely-visible impact damage (BVID) in unidirectional carbon fiber reinforced polymer matrix composite laminate plates using nondestructive ultrasonic testing (UT) and destructive serial sectioning microscopy. To produce damage consistent with BVID, plates were impacted using an instrumented drop-weight tower with pneumatic anti-rebound brake. High-resolution, normal-incidence, single-sided, pulse-echo, immersion UT scans were performed to verify and map internal damage after impact testing. UT C-scans were registered to optical images of the specimen via landmark registration and the use of an affine transformation, allowing location of internal damage in reference to the overall plate and enabling specimen preparation for subsequent serial sectioning. The impact-damaged region was extracted from each plate, prepared and mounted for materialographic sectioning. A modified RoboMet.3D version 2 was employed for serial sectioning and optical microscopy characterization of the impact damaged regions. Automated montage capture of sub-micron resolution, bright-field reflection, 12-bit monochrome optical images was performed over the entire specimen cross-section. These optical images were post- processed to produce 3D data sets, including segmentation to improve visualization of damage features. Impact-induced delaminations were analyzed and characterized using both serial sectioning and ultrasonic methods. Those results and conclusions are presented, as well as future direction of the current study.

Cross-sectional examination of the damage zone in impacted specimens of carbon/epoxy and carbon/PEEK composites

NASA Technical Reports Server (NTRS)

Nettles, A. T.; Magold, N. J.

1990-01-01

Drop weight impact testing was utilized to inflict damage on eight-ply bidirectional and unidirectional samples of carbon/epoxy and carbon/PEEK (polyetheretherketone) test specimens with impact energies ranging from 0.80 J to 1.76 J. The impacting tip was of a smaller diameter (4.2-mm) than those used in most previous studies, and the specimens were placed with a diamond wheel wafering saw through the impacted area perpendicular to the outer fibers. Photographs at 12 x magnification were taken of these cross-sections and examined. The results on the bidirectional samples show little damage until 1.13 J, at which point delaminations were seen in the epoxy specimens. The PEEK specimens showed less delamination than the epoxy specimens for a given impact energy level. The unidirectional specimens displayed more damage than the bidirectional samples for a given impact energy, with the PEEK specimens showing much less damage than the epoxy material.

ACTUAL WASTE TESTING OF GYCOLATE IMPACTS ON THE SRS TANK FARM

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

Martino, C.

2014-05-28

Glycolic acid is being studied as a replacement for formic acid in the Defense Waste Processing Facility (DWPF) feed preparation process. After implementation, the recycle stream from DWPF back to the high-level waste Tank Farm will contain soluble sodium glycolate. Most of the potential impacts of glycolate in the Tank Farm were addressed via a literature review and simulant testing, but several outstanding issues remained. This report documents the actual-waste tests to determine the impacts of glycolate on storage and evaporation of Savannah River Site high-level waste. The objectives of this study are to address the following: Determine the extentmore » to which sludge constituents (Pu, U, Fe, etc.) dissolve (the solubility of sludge constituents) in the glycolate-containing 2H-evaporator feed. Determine the impact of glycolate on the sorption of fissile (Pu, U, etc.) components onto sodium aluminosilicate solids. The first objective was accomplished through actual-waste testing using Tank 43H and 38H supernatant and Tank 51H sludge at Tank Farm storage conditions. The second objective was accomplished by contacting actual 2H-evaporator scale with the products from the testing for the first objective. There is no anticipated impact of up to 10 g/L of glycolate in DWPF recycle to the Tank Farm on tank waste component solubilities as investigated in this test. Most components were not influenced by glycolate during solubility tests, including major components such as aluminum, sodium, and most salt anions. There was potentially a slight increase in soluble iron with added glycolate, but the soluble iron concentration remained so low (on the order of 10 mg/L) as to not impact the iron to fissile ratio in sludge. Uranium and plutonium appear to have been supersaturated in 2H-evaporator feed solution mixture used for this testing. As a result, there was a reduction of soluble uranium and plutonium as a function of time. The change in soluble uranium concentration was independent of added glycolate concentration. The change in soluble plutonium content was dependent on the added glycolate concentration, with higher levels of glycolate (5 g/L and 10 g/L) appearing to suppress the plutonium solubility. The inclusion of glycolate did not change the dissolution of or sorption onto actual-waste 2H-evaporator pot scale to an extent that will impact Tank Farm storage and concentration. The effects that were noted involved dissolution of components from evaporator scale and precipitation of components onto evaporator scale that were independent of the level of added glycolate.« less

Pyschometric testing of the Family Impact of Pain Scale using a sample of families in Australia.

PubMed

West, Caryn; Buettner, Petra; Foster, Kim; Usher, Kim

2012-01-01

To test the psychometric properties of the Family Impact of Pain Scale (FIPS) using a sample of families resident in North Queensland. While pain has a significant effect on the individual, the entire family can be affected when a member of the family has chronic pain. FIPS is the only tool designed to measure the effect of pain on the family. It was originally developed in the UK using a sample of people with dental pain, so to test the psychometric properties of the tool with Australians with chronic pain was essential. DATA SOURCES; Participants (n = 67) completed a survey consisting of four tools: FIPS, the Connor Davidson Resilience Scale (CD-RISC), the Medical Outcomes Study Short Form 36 (SF-36) and the Medical Outcomes Study Social Support Survey (MOS SSS). Psychometric characteristics of FIPS were consistent with previous studies, indicating that the tool can be used reliably to measure the impact of chronic pain on the family in Australia. The FIPS is a reliable tool for predicting the impact of chronic pain on the family and for use with an Australian population. The validation of a tool such as FIPS in an Australian population adds to the current body of knowledge and extends the use of the tool. Such validation supports its reliability and stability across populations and provides Australian healthcare workers with a valid tool to measure the impact of pain on the family.

A Combination of Traditional and Novel Methods Used to Evaluate the Impact of an EVA Glove on Hand Performance

NASA Technical Reports Server (NTRS)

Rajulu, Sudhakar; Benson, Elizabeth; England, Scott; Mesloh, Miranda; Thompson, Shelby

2009-01-01

The gloved hand is an astronaut s primary means of interacting with the environment, so performance on an EVA is strongly impacted by any restrictions imposed by the glove. As a result, these restrictions have been the subject of study for decades. However, previous studies have generally been unsuccessful in quantifying glove mobility and tactility. Instead, studies have tended to focus on the dexterity, strength and functional performance of the gloved hand. Therefore, it has been difficult to judge the impact of each type of restriction on the glove s overall capability. The lack of basic information on glove mobility in particular, is related to the difficulty in instrumenting a gloved hand to allow an accurate evaluation. However, the current study aims at developing novel technological capabilities to provide metrics for mobility and tactility that can be used to assess the performance of a glove in a way that could enable designers and engineers to improve upon their current designs. A series of evaluations were performed in ungloved, unpressurized and pressurized (4.3 psi) conditions, to allow a comparison across pressures and to the baseline barehanded condition. In addition, a subset of the testing was also performed with the Thermal Micrometeoroid Garment (TMG) removed. This test case in particular provided some interesting insight into how much of an impact the TMG has on gloved mobility -- in some cases, as much as pressurization of the glove. Previous rule-of-thumb estimates had assumed that the TMG would have a much lower impact on mobility, while these results suggest that an improvement in the TMG could actually have a significant impact on glove performance. Similarly, tactility testing illustrated the impact of glove pressurization on tactility and provided insight on the design of interfaces to the glove. The metrics described in this paper have been used to benchmark the Phase VI EVA glove and to develop requirements for the next generation glove for the Constellation program.

Psychological distress among low-income U.S.- and foreign-born women of Mexican descent: impact of acculturation.

PubMed

Bekteshi, Venera; Xu, Qingwen; Van Tran, Thanh

2015-01-01

After testing the capacity of Kessler's psychological distress (K6) scale to measure equally across low-income Mexican-born women (n=881) and U.S.-born women of Mexican descent (n=317), this study assesses the impact of acculturation on this group's psychological distress. We employ descriptive and confirmatory factor analyses to test the cross-cultural equivalence of K6. Multivariate and logistic regression is used to test the association between acculturation and psychological distress among low-income, Mexican-American women. The cross-cultural equivalence analysis shows that some of the scale's items have the capacity to measure psychological distress equally among participants. Regression results indicate that the more acculturated these women become, the greater their psychological distress is. The study recommends that researchers emphasize the cross-cultural equivalence of their measures and suggests a heightened awareness among practitioners of the multidimensional impact of acculturation on clients of Mexican descent. Copyright © 2015 Jacobs Institute of Women's Health. Published by Elsevier Inc. All rights reserved.

Calculating the momentum enhancement factor for asteroid deflection studies

DOE PAGES

Heberling, Tamra; Gisler, Galen; Plesko, Catherine; ...

2017-10-17

The possibility of kinetic-impact deflection of threatening near-Earth asteroids will be tested for the first time in the proposed AIDA (Asteroid Impact Deflection Assessment) mission, involving NASAs DART (Double Asteroid Redirection Test). The impact of the DART spacecraft onto the secondary of the binary asteroid 65803 Didymos at a speed of 5 to 7 km/s is expected to alter the mutual orbit by an observable amount. Furthermore, the velocity transferred to the secondary depends largely on the momentum enhancement factor, typically referred to as beta. Here, we use two hydrocodes developed at Los Alamos, RAGE and PAGOSA, to calculate anmore » approximate value for beta in laboratory-scale benchmark experiments. Convergence studies comparing the two codes show the importance of mesh size in estimating this crucial parameter.« less

Calculating the momentum enhancement factor for asteroid deflection studies

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

Heberling, Tamra; Gisler, Galen; Plesko, Catherine

The possibility of kinetic-impact deflection of threatening near-Earth asteroids will be tested for the first time in the proposed AIDA (Asteroid Impact Deflection Assessment) mission, involving NASAs DART (Double Asteroid Redirection Test). The impact of the DART spacecraft onto the secondary of the binary asteroid 65803 Didymos at a speed of 5 to 7 km/s is expected to alter the mutual orbit by an observable amount. Furthermore, the velocity transferred to the secondary depends largely on the momentum enhancement factor, typically referred to as beta. Here, we use two hydrocodes developed at Los Alamos, RAGE and PAGOSA, to calculate anmore » approximate value for beta in laboratory-scale benchmark experiments. Convergence studies comparing the two codes show the importance of mesh size in estimating this crucial parameter.« less

Impact sensitivity of materials in contact with liquid and gaseous oxygen at high pressure

NASA Technical Reports Server (NTRS)

Schwinghamer, R. J.

1972-01-01

As a result of the Apollo 13 incident, increased emphasis is being placed on materials compatibility in a high pressure GOX environment. It is known that in addition to impact sensitivity of materials, approximately adiabatic compression conditions can contrive to induce materials reactivity. Test runs at high pressure using the ABMA tester indicate the following: (1) The materials used in the tests showed an inverse relationship between thickness and impact sensitivity. (2) Several materials tested exhibited greater impact sensitivity in GOX than in LOX. (3) The impact sensitivity of the materials tested in GOX, at the pressures tested, showed enhanced impact sensitivity with higher pressure. (4) The rank ordering of the materials tested in LOX up to 1000 psia is the same as the rank ordering resulting from tests in LOX at 14.7 psia.

Structural properties of impact ices accreted on aircraft structures

NASA Technical Reports Server (NTRS)

Scavuzzo, R. J.; Chu, M. L.

1987-01-01

The structural properties of ice accretions formed on aircraft surfaces are studied. The overall objectives are to measure basic structural properties of impact ices and to develop finite element analytical procedures for use in the design of all deicing systems. The Icing Research Tunnel (IRT) was used to produce simulated natural ice accretion over a wide range of icing conditions. Two different test apparatus were used to measure each of the three basic mechanical properties: tensile, shear, and peeling. Data was obtained on both adhesive shear strength of impact ices and peeling forces for various icing conditions. The influences of various icing parameters such as tunnel air temperature and velocity, icing cloud drop size, material substrate, surface temperature at ice/material interface, and ice thickness were studied. A finite element analysis of the shear test apparatus was developed in order to gain more insight in the evaluation of the test data. A comparison with other investigators was made. The result shows that the adhesive shear strength of impact ice typically varies between 40 and 50 psi, with peak strength reaching 120 psi and is not dependent on the kind of substrate used, the thickness of accreted ice, and tunnel temperature below 4 C.

Impact of Learning Model Based on Cognitive Conflict toward Student’s Conceptual Understanding

NASA Astrophysics Data System (ADS)

Mufit, F.; Festiyed, F.; Fauzan, A.; Lufri, L.

2018-04-01

The problems that often occur in the learning of physics is a matter of misconception and low understanding of the concept. Misconceptions do not only happen to students, but also happen to college students and teachers. The existing learning model has not had much impact on improving conceptual understanding and remedial efforts of student misconception. This study aims to see the impact of cognitive-based learning model in improving conceptual understanding and remediating student misconceptions. The research method used is Design / Develop Research. The product developed is a cognitive conflict-based learning model along with its components. This article reports on product design results, validity tests, and practicality test. The study resulted in the design of cognitive conflict-based learning model with 4 learning syntaxes, namely (1) preconception activation, (2) presentation of cognitive conflict, (3) discovery of concepts & equations, (4) Reflection. The results of validity tests by some experts on aspects of content, didactic, appearance or language, indicate very valid criteria. Product trial results also show a very practical product to use. Based on pretest and posttest results, cognitive conflict-based learning models have a good impact on improving conceptual understanding and remediating misconceptions, especially in high-ability students.

Multi-Dimensional Calibration of Impact Dynamic Models

NASA Technical Reports Server (NTRS)

Horta, Lucas G.; Reaves, Mercedes C.; Annett, Martin S.; Jackson, Karen E.

2011-01-01

NASA Langley, under the Subsonic Rotary Wing Program, recently completed two helicopter tests in support of an in-house effort to study crashworthiness. As part of this effort, work is on-going to investigate model calibration approaches and calibration metrics for impact dynamics models. Model calibration of impact dynamics problems has traditionally assessed model adequacy by comparing time histories from analytical predictions to test at only a few critical locations. Although this approach provides for a direct measure of the model predictive capability, overall system behavior is only qualitatively assessed using full vehicle animations. In order to understand the spatial and temporal relationships of impact loads as they migrate throughout the structure, a more quantitative approach is needed. In this work impact shapes derived from simulated time history data are used to recommend sensor placement and to assess model adequacy using time based metrics and orthogonality multi-dimensional metrics. An approach for model calibration is presented that includes metric definitions, uncertainty bounds, parameter sensitivity, and numerical optimization to estimate parameters to reconcile test with analysis. The process is illustrated using simulated experiment data.

ORION Project-(SPLASH) Structural Passive Landing Attenuation fo

NASA Image and Video Library

2011-07-12

ORION Project-(SPLASH) Structural Passive Landing Attenuation for Survivability of Human Crew (BTA) Boiler Plate Test Article Water Impact Test-Pot Phase"0" Test Tested at the Hydro Impact Basin at the Landing and Impact Research Facility (Gantry)

Agreement between gastrointestinal panel testing and standard microbiology methods for detecting pathogens in suspected infectious gastroenteritis: Test evaluation and meta-analysis in the absence of a reference standard.

PubMed

Freeman, Karoline; Tsertsvadze, Alexander; Taylor-Phillips, Sian; McCarthy, Noel; Mistry, Hema; Manuel, Rohini; Mason, James

2017-01-01

Multiplex gastrointestinal pathogen panel (GPP) tests simultaneously identify bacterial, viral and parasitic pathogens from the stool samples of patients with suspected infectious gastroenteritis presenting in hospital or the community. We undertook a systematic review to compare the accuracy of GPP tests with standard microbiology techniques. Searches in Medline, Embase, Web of Science and the Cochrane library were undertaken from inception to January 2016. Eligible studies compared GPP tests with standard microbiology techniques in patients with suspected gastroenteritis. Quality assessment of included studies used tailored QUADAS-2. In the absence of a reference standard we analysed test performance taking GPP tests and standard microbiology techniques in turn as the benchmark test, using random effects meta-analysis of proportions. No study provided an adequate reference standard with which to compare the test accuracy of GPP and conventional tests. Ten studies informed a meta-analysis of positive and negative agreement. Positive agreement across all pathogens was 0.93 (95% CI 0.90 to 0.96) when conventional methods were the benchmark and 0.68 (95% CI: 0.58 to 0.77) when GPP provided the benchmark. Negative agreement was high in both instances due to the high proportion of negative cases. GPP testing produced a greater number of pathogen-positive findings than conventional testing. It is unclear whether these additional 'positives' are clinically important. GPP testing has the potential to simplify testing and accelerate reporting when compared to conventional microbiology methods. However the impact of GPP testing upon the management, treatment and outcome of patients is poorly understood and further studies are needed to evaluate the health economic impact of GPP testing compared with standard methods. The review protocol is registered with PROSPERO as CRD42016033320.

Correlation between strength properties in standard test specimens and molded phenolic parts

NASA Technical Reports Server (NTRS)

Turner, P S; Thomason, R H

1946-01-01

This report describes an investigation of the tensile, flexural, and impact properties of 10 selected types of phenolic molding materials. The materials were studied to see in what ways and to what extent their properties satisfy some assumptions on which the theory of strength of materials is based: namely, (a) isotropy, (b) linear stress-strain relationship for small strains, and (c) homogeneity. The effect of changing the dimensions of tensile and flexural specimens and the span-depth ratio in flexural tests were studied. The strengths of molded boxes and flexural specimens cut from the boxes were compared with results of tests on standard test specimens molded from the respective materials. The nonuniformity of a material, which is indicated by the coefficient of variation, affects the results of tests made with specimens of different sizes and tests with different methods of loading. The strength values were found to depend on the relationship between size and shape of the molded specimen and size and shape of the fillers. The most significant variations observed within a diversified group of materials were found to depend on the orientation of fibrous fillers. Of secondary importance was the dependence of the variability of test results on the pieces of filler incorporated into the molding powder as well as on the size of the piece. Static breaking strength tests on boxes molded from six representative phenolic materials correlated well with falling-ball impact tests on specimens cut from molded flat sheets. Good correlation was obtained with Izod impact tests on standard test specimens prepared from the molding materials. The static breaking strengths of the boxes do not correlate with the results of tensile or flexural tests on standard specimens.

Reinforced Carbon-Carbon Subcomponent Flat Plate Impact Testing for Space Shuttle Orbiter Return to Flight

NASA Technical Reports Server (NTRS)

Melis, Matthew E.; Brand, Jeremy H.; Pereira, J. Michael; Revilock, Duane M.

2007-01-01

Following the tragedy of the Space Shuttle Columbia on February 1, 2003, a major effort commenced to develop a better understanding of debris impacts and their effect on the Space Shuttle subsystems. An initiative to develop and validate physics-based computer models to predict damage from such impacts was a fundamental component of this effort. To develop the models it was necessary to physically characterize Reinforced Carbon-Carbon (RCC) and various debris materials which could potentially shed on ascent and impact the Orbiter RCC leading edges. The validated models enabled the launch system community to use the impact analysis software LS DYNA to predict damage by potential and actual impact events on the Orbiter leading edge and nose cap thermal protection systems. Validation of the material models was done through a three-level approach: fundamental tests to obtain independent static and dynamic material model properties of materials of interest, sub-component impact tests to provide highly controlled impact test data for the correlation and validation of the models, and full-scale impact tests to establish the final level of confidence for the analysis methodology. This paper discusses the second level subcomponent test program in detail and its application to the LS DYNA model validation process. The level two testing consisted of over one hundred impact tests in the NASA Glenn Research Center Ballistic Impact Lab on 6 by 6 in. and 6 by 12 in. flat plates of RCC and evaluated three types of debris projectiles: BX 265 External Tank foam, ice, and PDL 1034 External Tank foam. These impact tests helped determine the level of damage generated in the RCC flat plates by each projectile. The information obtained from this testing validated the LS DYNA damage prediction models and provided a certain level of confidence to begin performing analysis for full-size RCC test articles for returning NASA to flight with STS 114 and beyond.

Psychological impact of von Hippel-Lindau genetic screening in patients with a previous history of hemangioblastoma of the central nervous system.

PubMed

Rochette, Claire; Baumstarck, Karine; Canoni-Zattara, Hélène; Abdullah, Ahmad Esmaeel; Figarella-Branger, Dominique; Pertuit, Morgane; Barlier, Anne; Castinetti, Frédéric; Pacak, Karel; Metellus, Philippe; Taïeb, David

2018-05-15

Von Hippel-Lindau (VHL) syndrome is a hereditary cancer syndrome characterized by a high risk of developing benign and malignant tumors, including central nervous system hemangioblastomas (CNS HBs). For an early diagnosis of VHL, before the occurrence of cancers (especially renal cell carcinoma), it is of huge importance to initiate VHL genetic testing in at-risk patients. The aim of the study was to assess the psychological impact of VHL genetic testing in patients previously diagnosed with a CNS HB. From 1999 until 2015, 55 patients underwent surgery for CNS HBs. Eleven patients were already screened for VHL mutations and 3 patients deceased before the start of the study. From the remaining 42 patients, 24 were accepted to be enrolled in the study. Assessment of psychological impact of VHL genetic testing was performed by measuring anxiety levels, mood disorders, quality of life, and psychological consequences of genetic screening. Twenty-one of the enrolled 24 patients underwent VHL genetic testing and 12 patients came back for the communication of positive genetic results. The baseline psychological status did not differ between these 2 groups. Patients who attended the visit of communication of genetic results had similar anxiety levels compared to those who had not. Furthermore, they also experienced an improvement in the level of anxiety and two QoL dimension scores compared to their baseline status. In summary, there is no evidence of a negative psychosocial impact of VHL genetic testing in patients with a previous history of CNS HB. We, therefore, recommend the recall of patients who have not been previously screened.

Transport aircraft accident dynamics

NASA Technical Reports Server (NTRS)

Cominsky, A.

1982-01-01

A study was carried out of 112 impact survivable jet transport aircraft accidents (world wide) of 27,700 kg (60,000 lb.) aircraft and up extending over the last 20 years. This study centered on the effect of impact and the follow-on events on aircraft structures and was confined to the approach, landing and takeoff segments of the flight. The significant characteristics, frequency of occurrence and the effect on the occupants of the above data base were studied and categorized with a view to establishing typical impact scenarios for use as a basis of verifying the effectiveness of potential safety concepts. Studies were also carried out of related subjects such as: (1) assessment of advanced materials; (2) human tolerance to impact; (3) merit functions for safety concepts; and (4) impact analysis and test methods.

Sociotechnical Human Factors Involved in Remote Online Usability Testing of Two eHealth Interventions.

PubMed

Wozney, Lori M; Baxter, Pamela; Fast, Hilary; Cleghorn, Laura; Hundert, Amos S; Newton, Amanda S

2016-02-03

Research in the fields of human performance technology and human computer interaction are challenging the traditional macro focus of usability testing arguing for methods that help test moderators assess "use in context" (ie, cognitive skills, usability understood over time) and in authentic "real world" settings. Human factors in these complex test scenarios may impact on the quality of usability results being derived yet there is a lack of research detailing moderator experiences in these test environments. Most comparative research has focused on the impact of the physical environment on results, and rarely on how the sociotechnical elements of the test environment affect moderator and test user performance. Improving our understanding of moderator roles and experiences with conducting "real world" usability testing can lead to improved techniques and strategies To understand moderator experiences of using Web-conferencing software to conduct remote usability testing of 2 eHealth interventions. An exploratory case study approach was used to study 4 moderators' experiences using Blackboard Collaborate for remote testing sessions of 2 different eHealth interventions. Data collection involved audio-recording iterative cycles of test sessions, collecting summary notes taken by moderators, and conducting 2 90-minute focus groups via teleconference. A direct content analysis with an inductive coding approach was used to explore personal accounts, assess the credibility of data interpretation, and generate consensus on the thematic structure of the results. Following the convergence of data from the various sources, 3 major themes were identified: (1) moderators experienced and adapted to unpredictable changes in cognitive load during testing; (2) moderators experienced challenges in creating and sustaining social presence and untangling dialogue; and (3) moderators experienced diverse technical demands, but were able to collaboratively troubleshoot with test users. Results highlight important human-computer interactions and human factor qualities that impact usability testing processes. Moderators need an advanced skill and knowledge set to address the social interaction aspects of Web-based usability testing and technical aspects of conferencing software during test sessions. Findings from moderator-focused studies can inform the design of remote testing platforms and real-time usability evaluation processes that place less cognitive burden on moderators and test users.

49 CFR 572.191 - General description.

Code of Federal Regulations, 2013 CFR

2013-10-01

... ADMINISTRATION, DEPARTMENT OF TRANSPORTATION (CONTINUED) ANTHROPOMORPHIC TEST DEVICES SID-IIsD Side Impact Crash Test Dummy, Small Adult Female § 572.191 General description. (a) The SID-IIsD Side Impact Crash Test... test sensors for the SID-IIsD Side Impact Crash Test Dummy, 5th percentile adult female, is shown in...

49 CFR 572.191 - General description.

Code of Federal Regulations, 2014 CFR

2014-10-01

... ADMINISTRATION, DEPARTMENT OF TRANSPORTATION (CONTINUED) ANTHROPOMORPHIC TEST DEVICES SID-IIsD Side Impact Crash Test Dummy, Small Adult Female § 572.191 General description. (a) The SID-IIsD Side Impact Crash Test... test sensors for the SID-IIsD Side Impact Crash Test Dummy, 5th percentile adult female, is shown in...

Framework for Testing the Effectiveness of Bat and Eagle Impact-Reduction Strategies at Wind Energy Projects

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

Sinclair, Karin; DeGeorge, Elise

2016-04-13

The objectives of this framework are to facilitate the study design and execution to test the effectiveness of bat and eagle impact-reduction strategies at wind energy sites. Through scientific field research, the wind industry and its partners can help determine if certain strategies are ready for operational deployment or require further development. This framework should be considered a living document to be improved upon as fatality-reduction technologies advance from the initial concepts to proven readiness (through project- and technology-specific testing) and as scientific field methods improve.

Concussion in professional football: helmet testing to assess impact performance--part 11.

PubMed

Pellman, Elliot J; Viano, David C; Withnall, Chris; Shewchenko, Nick; Bir, Cynthia A; Halstead, P David

2006-01-01

National Football League (NFL) concussions occur at an impact velocity of 9.3 +/- 1.9 m/s (20.8 +/- 4.2 mph) oblique on the facemask, side, and back of the helmet. There is a need for new testing to evaluate helmet performance for impacts causing concussion. This study provides background on new testing methods that form a basis for supplemental National Operating Committee on Standards for Athletic Equipment (NOCSAE) helmet standards. First, pendulum impacts were used to simulate 7.4 and 9.3 m/s impacts causing concussion in NFL players. An instrumented Hybrid III head was helmeted and supported on the neck, which was fixed to a sliding table for frontal and lateral impacts. Second, a linear pneumatic impactor was used to evaluate helmets at 9.3 m/s and an elite impact condition at 11.2 m/s. The upper torso of the Hybrid III dummy was used. It allowed interactions with shoulder pads and other equipment. The severity of the head responses was measured by a severity index, translational and rotational acceleration, and other biomechanical responses. High-speed videos of the helmet kinematics were also recorded. The tests were evaluated for their similarity to conditions causing NFL concussions. Finally, a new linear impactor was developed for use by NOCSAE. The pendulum test closely simulated the conditions causing concussion in NFL players. Newer helmet designs and padding reduced the risk of concussion in 7.4 and 9.3 m/s impacts oblique on the facemask and lateral on the helmet shell. The linear impactor provided a broader speed range for helmet testing and more interactions with safety equipment. NOCSAE has prepared a draft supplemental standard for the 7.4 and 9.3 m/s impacts using a newly designed pneumatic impactor. No helmet designs currently address the elite impact condition at 11.2 m/s, as padding bottoms out and head responses dramatically increase. The proposed NOCSAE standard is the first to address helmet performance in reducing concussion risks in football. Helmet performance has improved with thicker padding and fuller coverage by the shell. However, there remains a challenge for innovative designs that reduce risks in the 11.2 m/s elite impact condition.

46 CFR 54.05-20 - Impact test properties for service of 0 °F and below.

Code of Federal Regulations, 2012 CFR

2012-10-01

... 46 Shipping 2 2012-10-01 2012-10-01 false Impact test properties for service of 0 °F and below. 54.05-20 Section 54.05-20 Shipping COAST GUARD, DEPARTMENT OF HOMELAND SECURITY (CONTINUED) MARINE ENGINEERING PRESSURE VESSELS Toughness Tests § 54.05-20 Impact test properties for service of 0 °F and below. (a) Test energy. The impact energies of...

Treatment of Test Anxiety: A Computerized Approach

ERIC Educational Resources Information Center

Pless, Anica

2010-01-01

Test anxiety creates problems for many students, and can have a negative impact on the academic performance of many who suffer from it (Jones & Petruzzi, 1995). Typical treatment components for test anxiety involve psychoeducation, relaxation training, gradual exposure, cognitive restructuring, study skills training, and relapse prevention.…

Crash test rating and likelihood of major thoracoabdominal injury in motor vehicle crashes: the new car assessment program side-impact crash test, 1998-2010.

PubMed

Figler, Bradley D; Mack, Christopher D; Kaufman, Robert; Wessells, Hunter; Bulger, Eileen; Smith, Thomas G; Voelzke, Bryan

2014-03-01

The National Highway Traffic Safety Administration's New Car Assessment Program (NCAP) implemented side-impact crash testing on all new vehicles since 1998 to assess the likelihood of major thoracoabdominal injuries during a side-impact crash. Higher crash test rating is intended to indicate a safer car, but the real-world applicability of these ratings is unknown. Our objective was to determine the relationship between a vehicle's NCAP side-impact crash test rating and the risk of major thoracoabdominal injury among the vehicle's occupants in real-world side-impact motor vehicle crashes. The National Automotive Sampling System Crashworthiness Data System contains detailed crash and injury data in a sample of major crashes in the United States. For model years 1998 to 2010 and crash years 1999 to 2010, 68,124 occupants were identified in the Crashworthiness Data System database. Because 47% of cases were missing crash severity (ΔV), multiple imputation was used to estimate the missing values. The primary predictor of interest was the occupant vehicle's NCAP side-impact crash test rating, and the outcome of interest was the presence of major (Abbreviated Injury Scale [AIS] score ≥ 3) thoracoabdominal injury. In multivariate analysis, increasing NCAP crash test rating was associated with lower likelihood of major thoracoabdominal injury at high (odds ratio [OR], 0.8; 95% confidence interval [CI], 0.7-0.9; p < 0.01) and medium (OR, 0.9; 95% CI, 0.8-1.0; p < 0.05) crash severity (ΔV), but not at low ΔV (OR, 0.95; 95% CI, 0.8-1.2; p = 0.55). In our model, older age and absence of seat belt use were associated with greater likelihood of major thoracoabdominal injury at low and medium ΔV (p < 0.001), but not at high ΔV (p ≥ 0.09). Among adults in model year 1998 to 2010 vehicles involved in medium and high severity motor vehicle crashes, a higher NCAP side-impact crash test rating is associated with a lower likelihood of major thoracoabdominal trauma. Epidemiologic study, level III.

Impact of dental caries on quality of life among preschool children: emphasis on the type of tooth and stages of progression.

PubMed

Ramos-Jorge, Joana; Alencar, Bruna Mota; Pordeus, Isabela Almeida; Soares, Maria Eliza da Consolação; Marques, Leandro Silva; Ramos-Jorge, Maria Letícia; Paiva, Saul Martins

2015-04-01

The aim of this cross-sectional study was to evaluate the impact of dental caries on the quality of life of preschool children and their parents/caretakers, with an emphasis on the type of tooth and stage of progression. A randomly selected sample of preschool children, 3-5 yrs of age, underwent an oral examination for the assessment of dental caries using the International Caries Detection and Assessment System II (ICDAS II) criteria. Parents/caretakers answered two questionnaires, one on the oral health-related quality of life (OHRQoL) of the child [the Early Childhood Oral Health Impact Scale (ECOHIS)], and the other on the socio-economic characteristics of the family. Statistical analyses were performed using the chi-square test, Kruskal-Wallis test, Mann-Whitney U-test, and Poisson regression. A total of 451 preschool children participated in the study. The majority of carious lesions exhibited severe decay (60.6%) and were found in both anterior (incisors/canines) and posterior (molars) teeth. The final Poisson model revealed negative impacts on quality of life from more advanced stages of dental caries, both in incisors/canines and molars. Child's age and household income were also associated with impact on quality of life. Carious lesions in more advanced stages of progression in anterior and posterior teeth were associated with a negative impact on the quality of life of preschool children. © 2014 Eur J Oral Sci.

Comparative difficulty and the strategic regulation of accuracy: the impact of test-list context on monitoring and meta-metacognition.

PubMed

Arnold, Michelle M; Prike, Toby

2015-05-01

A growing body of research has shown that context manipulations can have little or no impact on accuracy performance, yet still significantly influence metacognitive performance. For example, participants in a test-list context paradigm study one list of words with a medium levels-of-processing task and a second word list with either a shallow or deep task: Recognition for medium words does not differ across conditions, however medium words are significantly more likely to be labeled as "remembered" (vs. merely familiar) if they had been studied with a shallow word list (Bodner & Lindsay, 2003). The goal of the current studies was to extend the test-list context paradigm to strategic regulation (report/withhold recognition test), and broaden it to incorporate different types of stimuli (i.e., face stimuli in place of a medium word list). The paradigm also was modified to include separate answer (studied/new) confidence and decision (report/withhold) confidence ratings at test. Results showed that context did not impact recognition accuracy for faces across the context conditions, however participants were more likely to report (i.e., volunteer) their face responses if they had studied the shallow word list. The results also demonstrated a difference between answer confidence and decision confidence, and the pattern of this difference depended on whether responses were reported or withheld (Experiment 1). Overall, the data are presented as support for the functional account of memory, which views memory states as inferential and attributional rather than static categories. Copyright © 2015 Elsevier B.V. All rights reserved.

Classroom by Classroom Analysis of the Impact of a Compensatory Education Program.

ERIC Educational Resources Information Center

Forster, Fred; Carpenter, James

The objective of this study was to evaluate the impact of the CO-Plus project by organizing data to utilize the classroom as the basic unit of analysis. The study employed classroom observations, a variety of questionnaire responses from staff and pupils, achievement test scores, and related data. Questionnaire data were summarized using factor…

Consequences of ignoring geologic variation in evaluating grazing impacts

Treesearch

Jonathan W. Long; Alvin L. Medina

2006-01-01

The geologic diversity of landforms in the Southwest complicates efforts to evaluate impacts of land uses such as livestock grazing. We examined a research study that evaluated relationships between trout biomass and stream habitat in the White Mountains of east-central Arizona. That study interpreted results of stepwise regressions and a nonparametric test of “grazed...

Strain-age cracking in Rene 41 alloy

NASA Technical Reports Server (NTRS)

Prager, M.; Thompson, E. G.

1969-01-01

Weldability test determines the effects of material and process variables on the occurrence of strain-age cracking, and demonstrates effective and practical means for its reduction. Studies consist of tensile, impact, and stress-rupture tests.

The study of barium concentration in deciduous teeth, impacted teeth, and facial bones of Polish residents.

PubMed

Fischer, Agnieszka; Malara, Piotr; Wiechuła, Danuta

2014-10-01

The study determines the concentration of Ba in mineralized tissues of deciduous teeth, permanent impacted teeth, and facial bones. The study covers the population of children and adults (aged 6-78) living in an industrial area of Poland. Teeth were analyzed in whole, with no division into dentine and enamel. Facial bones and teeth were subjected to the following preparation: washing, drying, grinding in a porcelain mortar, sample weighing (about 0.2 g), and microwave mineralization with spectrally pure nitric acid. The aim of the study was to determinate the concentration of Ba in deciduous teeth, impacted permanent teeth, and facial bones. The concentration of barium in samples was determined over the ICP OES method. The Ba concentration in the tested bone tissues amounted to 2.2-15.5 μg/g (6.6 μg/g ± 3.9). The highest concentration of Ba was present in deciduous teeth (10.5 μg/g), followed by facial bones (5.2 μg/g), and impacted teeth (4.3 μg/g) (ANOVA Kruskal-Wallis rank test, p = 0.0002). In bone tissue and impacted teeth, Ba concentration increased with age. In deciduous teeth, the level of Ba decreased with children's age.

ORION Project-(SPLASH) Structural Passive Landing Attenuation fo

NASA Image and Video Library

2011-07-21

ORION Project-(SPLASH) Structural Passive Landing Attenuation for Survivability of Human Crew (BTA) Boiler Plate Test Article Water Impact Test-Pot Phase"0" Test POT#2 Tested at the Hydro Impact Basin at the Landing and Impact Research Facility (Gantry)

ORION Project-(SPLASH) Structural Passive Landing Attenuation fo

NASA Image and Video Library

2011-12-13

ORION Project-(SPLASH) Structural Passive Landing Attenuation for Survivability of Human Crew (BTA) Boiler Plate Test Article Water Impact Test-Pit Phase 4 Test or Pit 4 Tested at the Hydro Impact Basin at the Landing and Impact Research Facility (Gantry)

Using provider performance incentives to increase HIV testing and counseling services in Rwanda.

PubMed

de Walque, Damien; Gertler, Paul J; Bautista-Arredondo, Sergio; Kwan, Ada; Vermeersch, Christel; de Dieu Bizimana, Jean; Binagwaho, Agnès; Condo, Jeanine

2015-03-01

Paying for performance provides financial rewards to medical care providers for improvements in performance measured by utilization and quality of care indicators. In 2006, Rwanda began a pay for performance scheme to improve health services delivery, including HIV/AIDS services. Using a prospective quasi-experimental design, this study examines the scheme's impact on individual and couples HIV testing. We find a positive impact of pay for performance on HIV testing among married individuals (10.2 percentage points increase). Paying for performance also increased testing by both partners by 14.7 percentage point among discordant couples in which only one of the partners is an AIDS patient. Copyright © 2014. Published by Elsevier B.V.

A finite element model of a six-year-old child for simulating pedestrian accidents.

PubMed

Meng, Yunzhu; Pak, Wansoo; Guleyupoglu, Berkan; Koya, Bharath; Gayzik, F Scott; Untaroiu, Costin D

2017-01-01

Child pedestrian protection deserves more attention in vehicle safety design since they are the most vulnerable road users who face the highest mortality rate. Pediatric Finite Element (FE) models could be used to simulate and understand the pedestrian injury mechanisms during crashes in order to mitigate them. Thus, the objective of the study was to develop a computationally efficient (simplified) six-year-old (6YO-PS) pedestrian FE model and validate it based on the latest published pediatric data. The 6YO-PS FE model was developed by morphing the existing GHBMC adult pedestrian model. Retrospective scan data were used to locally adjust the geometry as needed for accuracy. Component test simulations focused only the lower extremities and pelvis, which are the first body regions impacted during pedestrian accidents. Three-point bending test simulations were performed on the femur and tibia with adult material properties and then updated using child material properties. Pelvis impact and knee bending tests were also simulated. Finally, a series of pediatric Car-to-Pedestrian Collision (CPC) were simulated with pre-impact velocities ranging from 20km/h up to 60km/h. The bone models assigned pediatric material properties showed lower stiffness and a good match in terms of fracture force to the test data (less than 6% error). The pelvis impact force predicted by the child model showed a similar trend with test data. The whole pedestrian model was stable during CPC simulations and predicted common pedestrian injuries. Overall, the 6YO-PS FE model developed in this study showed good biofidelity at component level (lower extremity and pelvis) and stability in CPC simulations. While more validations would improve it, the current model could be used to investigate the lower limb injury mechanisms and in the prediction of the impact parameters as specified in regulatory testing protocols. Copyright © 2016 Elsevier Ltd. All rights reserved.

Assessment and Quality Social Studies

ERIC Educational Resources Information Center

Savage, Tom V.

2003-01-01

Those anonymous individuals who develop high-stakes tests by which educational quality is measured exercise great influence in defining educational quality. In this article, the author examines the impact of high-stakes testing on the welfare of the children and the quality of social studies instruction. He presents the benefits and drawbacks of…

Reducing the Familiarity of Conjunction Lures with Pictures

ERIC Educational Resources Information Center

Lloyd, Marianne E.

2013-01-01

Four experiments were conducted to test whether conjunction errors were reduced after pictorial encoding and whether the semantic overlap between study and conjunction items would impact error rates. Across 4 experiments, compound words studied with a single-picture had lower conjunction error rates during a recognition test than those words…

System-Wide Tests of Occupational Programs.

ERIC Educational Resources Information Center

Perlmutter, Deborah E.

This report presents the background methodology, findings, and recommendations of three studies that comprised System-Wide Tests of Occupational Programs, a 4-year research program to assess the impact of vocational education using various followup techniques. Part 1 focuses on Project CATCH (Career Training Choice), a followup study of students…

Baseline neurocognitive testing in sports-related concussions: the importance of a prior night's sleep.

PubMed

McClure, D Jake; Zuckerman, Scott L; Kutscher, Scott J; Gregory, Andrew J; Solomon, Gary S

2014-02-01

The management of sports-related concussions (SRCs) utilizes serial neurocognitive assessments and self-reported symptom inventories to assess recovery and safety for return to play (RTP). Because postconcussive RTP goals include symptom resolution and a return to neurocognitive baseline levels, clinical decisions rest in part on understanding modifiers of this baseline. Several studies have reported age and sex to influence baseline neurocognitive performance, but few have assessed the potential effect of sleep. We chose to investigate the effect of reported sleep duration on baseline Immediate Post-Concussion Assessment and Cognitive Testing (ImPACT) performance and the number of patient-reported symptoms. We hypothesized that athletes receiving less sleep before baseline testing would perform worse on neurocognitive metrics and report more symptoms. Cross-sectional study; Level of evidence, 3. We retrospectively reviewed 3686 nonconcussed athletes (2371 male, 1315 female; 3305 high school, 381 college) with baseline symptom and ImPACT neurocognitive scores. Patients were stratified into 3 groups based on self-reported sleep duration the night before testing: (1) short, <7 hours; (2) intermediate, 7-9 hours; and (3) long, ≥9 hours. A multivariate analysis of covariance (MANCOVA) with an α level of .05 was used to assess the influence of sleep duration on baseline ImPACT performance. A univariate ANCOVA was performed to investigate the influence of sleep on total self-reported symptoms. When controlling for age and sex as covariates, the MANCOVA revealed significant group differences on ImPACT reaction time, verbal memory, and visual memory scores but not visual-motor (processing) speed scores. An ANCOVA also revealed significant group differences in total reported symptoms. For baseline symptoms and ImPACT scores, subsequent pairwise comparisons revealed these associations to be most significant when comparing the short and intermediate sleep groups. Our results indicate that athletes sleeping fewer than 7 hours before baseline testing perform worse on 3 of 4 ImPACT scores and report more symptoms. Because SRC management and RTP decisions hinge on the comparison with a reliable baseline evaluation, clinicians should consider sleep duration before baseline neurocognitive testing as a potential factor in the assessment of athletes' recovery.

English Writing Placement Recommendations at College of the Canyons: An Analysis of Disproportionate Impact.

ERIC Educational Resources Information Center

Gerda, Joseph

A study was undertaken at California's College of the Canyons (CoC) to determine whether evidence existed of disproportionate impact in English course placement based on student ethnicity, gender, or age. Data were compiled for all 4,309 students tested between spring 1993 and fall 1995, while the standard for disproportionate impact was taken…

The Impact of Back-Sputtered Carbon on the Accelerator Grid Wear Rates of the NEXT and NSTAR Ion Thrusters

NASA Technical Reports Server (NTRS)

Soulas, George C.

2013-01-01

A study was conducted to quantify the impact of back-sputtered carbon on the downstream accelerator grid erosion rates of the NEXT (NASA's Evolutionary Xenon Thruster) Long Duration Test (LDT1). A similar analysis that was conducted for the NSTAR (NASA's Solar Electric Propulsion Technology Applications Readiness Program) Life Demonstration Test (LDT2) was used as a foundation for the analysis developed herein. A new carbon surface coverage model was developed that accounted for multiple carbon adlayers before complete surface coverage is achieved. The resulting model requires knowledge of more model inputs, so they were conservatively estimated using the results of past thin film sputtering studies and particle reflection predictions. In addition, accelerator current densities across the grid were rigorously determined using an ion optics code to determine accelerator current distributions and an algorithm to determine beam current densities along a grid using downstream measurements. The improved analysis was applied to the NSTAR test results for evaluation. The improved analysis demonstrated that the impact of back-sputtered carbon on pit and groove wear rate for the NSTAR LDT2 was negligible throughout most of eroded grid radius. The improved analysis also predicted the accelerator current density for transition from net erosion to net deposition considerably more accurately than the original analysis. The improved analysis was used to estimate the impact of back-sputtered carbon on the accelerator grid pit and groove wear rate of the NEXT Long Duration Test (LDT1). Unlike the NSTAR analysis, the NEXT analysis was more challenging because the thruster was operated for extended durations at various operating conditions and was unavailable for measurements because the test is ongoing. As a result, the NEXT LDT1 estimates presented herein are considered preliminary until the results of future posttest analyses are incorporated. The worst-case impact of carbon back-sputtering was determined to be the full power operating condition, but the maximum impact of back-sputtered carbon was only a four percent reduction in wear rate. As a result, back-sputtered carbon is estimated to have an insignificant impact on the first failure mode of the NEXT LDT at all operating conditions.

Development, Evaluation, and Sensitivity Analysis of Parametric Finite Element Whole-Body Human Models in Side Impacts.

PubMed

Hwang, Eunjoo; Hu, Jingwen; Chen, Cong; Klein, Katelyn F; Miller, Carl S; Reed, Matthew P; Rupp, Jonathan D; Hallman, Jason J

2016-11-01

Occupant stature and body shape may have significant effects on injury risks in motor vehicle crashes, but the current finite element (FE) human body models (HBMs) only represent occupants with a few sizes and shapes. Our recent studies have demonstrated that, by using a mesh morphing method, parametric FE HBMs can be rapidly developed for representing a diverse population. However, the biofidelity of those models across a wide range of human attributes has not been established. Therefore, the objectives of this study are 1) to evaluate the accuracy of HBMs considering subject-specific geometry information, and 2) to apply the parametric HBMs in a sensitivity analysis for identifying the specific parameters affecting body responses in side impact conditions. Four side-impact tests with two male post-mortem human subjects (PMHSs) were selected to evaluate the accuracy of the geometry and impact responses of the morphed HBMs. For each PMHS test, three HBMs were simulated to compare with the test results: the original Total Human Model for Safety (THUMS) v4.01 (O-THUMS), a parametric THUMS (P-THUMS), and a subject-specific THUMS (S-THUMS). The P-THUMS geometry was predicted from only age, sex, stature, and BMI using our statistical geometry models of skeleton and body shape, while the S-THUMS geometry was based on each PMHS's CT data. The simulation results showed a preliminary trend that the correlations between the PTHUMS- predicted impact responses and the four PMHS tests (mean-CORA: 0.84, 0.78, 0.69, 0.70) were better than those between the O-THUMS and the normalized PMHS responses (mean-CORA: 0.74, 0.72, 0.55, 0.63), while they are similar to the correlations between S-THUMS and the PMHS tests (mean-CORA: 0.85, 0.85, 0.67, 0.72). The sensitivity analysis using the PTHUMS showed that, in side impact conditions, the HBM skeleton and body shape geometries as well as the body posture were more important in modeling the occupant impact responses than the bone and soft tissue material properties and the padding stiffness with the given parameter ranges. More investigations are needed to further support these findings.

A PVDF-Based Sensor for Internal Stress Monitoring of a Concrete-Filled Steel Tubular (CFST) Column Subject to Impact Loads.

PubMed

Du, Guofeng; Li, Zhao; Song, Gangbing

2018-05-23

Impact loads can have major adverse effects on the safety of civil engineering structures, such as concrete-filled steel tubular (CFST) columns. The study of mechanical behavior and stress analysis of CFST columns under impact loads is very important to ensure their safety against such loads. At present, the internal stress monitoring of the concrete cores CFST columns under impact loads is still a very challenging subject. In this paper, a PVDF (Polyvinylidene Fluoride) piezoelectric smart sensor was developed and successfully applied to the monitoring of the internal stress of the concrete core of a CFST column under impact loads. The smart sensor consists of a PVDF piezoelectric film sandwiched between two thin steel plates through epoxy. The protection not only prevents the PVDF film from impact damages but also ensures insulation and waterproofing. The smart sensors were embedded into the circular concrete-filled steel tube specimen during concrete pouring. The specimen was tested against impact loads, and testing data were collected. The time history of the stress obtained from the PVDF smart sensor revealed the evolution of core concrete internal stress under impact loads when compared with the impact force⁻time curve of the hammer. Nonlinear finite element simulations of the impact process were also carried out. The results of FEM simulations had good agreement with the test results. The results showed that the proposed PVDF piezoelectric smart sensors can effectively monitor the internal stress of concrete-filled steel tubular columns under impact loads.

Evaluating the Impact of Guessing and Its Interactions With Other Test Characteristics on Confidence Interval Procedures for Coefficient Alpha

PubMed Central

Paek, Insu

2015-01-01

The effect of guessing on the point estimate of coefficient alpha has been studied in the literature, but the impact of guessing and its interactions with other test characteristics on the interval estimators for coefficient alpha has not been fully investigated. This study examined the impact of guessing and its interactions with other test characteristics on four confidence interval (CI) procedures for coefficient alpha in terms of coverage rate (CR), length, and the degree of asymmetry of CI estimates. In addition, interval estimates of coefficient alpha when data follow the essentially tau-equivalent condition were investigated as a supplement to the case of dichotomous data with examinee guessing. For dichotomous data with guessing, the results did not reveal salient negative effects of guessing and its interactions with other test characteristics (sample size, test length, coefficient alpha levels) on CR and the degree of asymmetry, but the effect of guessing was salient as a main effect and an interaction effect with sample size on the length of the CI estimates, making longer CI estimates as guessing increases, especially when combined with a small sample size. Other important effects (e.g., CI procedures on CR) are also discussed. PMID:29795863

Advanced Crew Escape Suits (ACES): Particle Impact Test

NASA Technical Reports Server (NTRS)

Rosales, Keisa R.; Stoltzfus, Joel M.

2009-01-01

NASA Johnson Space Center (JSC) requested NASA JSC White Sands Test Facility to assist in determining the effects of impaired anodization on aluminum parts in advanced crew escape suits (ACES). Initial investigation indicated poor anodization could lead to an increased risk of particle impact ignition, and a lack of data was prevalent for particle impact of bare (unanodized) aluminum; therefore, particle impact tests were performed. A total of 179 subsonic and 60 supersonic tests were performed with no ignition of the aluminum targets. Based on the resulting test data, WSTF found no increased particle impact hazard was present in the ACES equipment.

Integrated Data Collection Analysis (IDCA) Program - SSST Testing Methods

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

Sandstrom, Mary M.; Brown, Geoffrey W.; Preston, Daniel N.

The Integrated Data Collection Analysis (IDCA) program is conducting a proficiency study for Small- Scale Safety and Thermal (SSST) testing of homemade explosives (HMEs). Described here are the methods used for impact, friction, electrostatic discharge, and differential scanning calorimetry analysis during the IDCA program. These methods changed throughout the Proficiency Test and the reasons for these changes are documented in this report. The most significant modifications in standard testing methods are: 1) including one specified sandpaper in impact testing among all the participants, 2) diversifying liquid test methods for selected participants, and 3) including sealed sample holders for thermal testingmore » by at least one participant. This effort, funded by the Department of Homeland Security (DHS), is putting the issues of safe handling of these materials in perspective with standard military explosives. The study is adding SSST testing results for a broad suite of different HMEs to the literature. Ultimately the study will suggest new guidelines and methods and possibly establish the SSST testing accuracies needed to develop safe handling practices for HMEs. Each participating testing laboratory uses identical test materials and preparation methods wherever possible. The testing performers involved are Lawrence Livermore National Laboratory (LLNL), Los Alamos National Laboratory (LANL), Indian Head Division, Naval Surface Warfare Center, (NSWC IHD), Sandia National Laboratories (SNL), and Air Force Research Laboratory (AFRL/RXQL). These tests are conducted as a proficiency study in order to establish some consistency in test protocols, procedures, and experiments and to compare results when these testing variables cannot be made consistent.« less

The use of impact force as a scale parameter for the impact response of composite laminates

NASA Technical Reports Server (NTRS)

Jackson, Wade C.; Poe, C. C., Jr.

1992-01-01

The building block approach is currently used to design composite structures. With this approach, the data from coupon tests is scaled up to determine the design of a structure. Current standard impact tests and methods of relating test data to other structures are not generally understood and are often used improperly. A methodology is outlined for using impact force as a scale parameter for delamination damage for impacts of simple plates. Dynamic analyses were used to define ranges of plate parameters and impact parameters where quasi-static analyses are valid. These ranges include most low velocity impacts where the mass of the impacter is large and the size of the specimen is small. For large mass impacts of moderately thick (0.35 to 0.70 cm) laminates, the maximum extent of delamination damage increased with increasing impact force and decreasing specimen thickness. For large mass impact tests at a given kinetic energy, impact force and hence delamination size depends on specimen size, specimen thickness, boundary conditions, and indenter size and shape. If damage is reported in terms of impact force instead of kinetic energy, large mass test results can be applied directly to other plates of the same size.

The use of impact force as a scale parameter for the impact response of composite laminates

NASA Technical Reports Server (NTRS)

Jackson, Wade C.; Poe, C. C., Jr.

1992-01-01

The building block approach is currently used to design composite structures. With this approach, the data from coupon tests are scaled up to determine the design of a structure. Current standard impact tests and methods of relating test data to other structures are not generally understood and are often used improperly. A methodology is outlined for using impact force as a scale parameter for delamination damage for impacts of simple plates. Dynamic analyses were used to define ranges of plate parameters and impact parameters where quasi-static analyses are valid. These ranges include most low-velocity impacts where the mass of the impacter is large, and the size of the specimen is small. For large-mass impacts of moderately thick (0.35-0.70 cm) laminates, the maximum extent of delamination damage increased with increasing impact force and decreasing specimen thickness. For large-mass impact tests at a given kinetic energy, impact force and hence delamination size depends on specimen size, specimen thickness, boundary conditions, and indenter size and shape. If damage is reported in terms of impact force instead of kinetic energy, large-mass test results can be applied directly to other plates of the same thickness.

Impact of the application of the Value Added Tax to imaging tests on out-of-pocket health expenses of households in Chile.

PubMed

Cuadrado, Cristóbal; Silva-Illanes, Nicolás

2015-12-09

Out-of-pocket healthcare expense represents a challenge for health systems for it constitutes a barrier to health care, impacting the equality of access to healthcare systems, something particularly important in the Chilean health system. In this context, the Government recently raised the possibility of incorporating a tax on imaging tests, creating debate over its potential consequences. To explore the impact on household out-of-pocket healthcare expense by the implementation of a value added tax to imaging tests in Chile. Cross-sectional study using data of household expenditures from the VII Household Budget Survey. Out-of-pocket healthcare expense and catastrophic household expenses are calculated comparing two scenarios, with and without the inclusion of the proposed tax. Analyses are presented by income deciles to explore the differential equality impact. 42.8% of diagnostic test expense on household corresponds to imaging studies. Under a scenario of tax implementation, a relative increase of 1.1% of out-of-pocket expenses and 2.2% of catastrophic household expenses is observed. The groups that suffer the greatest impact are those with lower income levels, concentrating in the first fifth deciles. We conclude that, although the increase in the average out-of- pocket spending is moderate, this policy may involve a significant increase in the catastrophic expense of the population with the lowest incomes, thereby increasing health inequalities. Considering the challenges of health system financing in Chile, it appears that such fiscal policy would only worsen the possibility of moving towards lower levels of out-of-pocket of household expenses.

Modeling occupants in far-side impacts.

PubMed

Douglas, Clay; Fildes, Brian; Gibson, Tom

2011-10-01

Far-side impacts are not part of any regulated NCAP, FMVSS, or similar test regime despite accounting for 43 percent of the seriously injured persons and 30 percent of the harm in U.S. side impact crashes. Furthermore, injuries to the head and thorax account for over half of the serious injuries sustained by occupants in far-side crashes. Despite this, there is no regulated or well-accepted anthropomorphic test device (ATD) or computer model available to investigate far-side impacts. As such, this presents an opportunity to assess a computer model that can be used to measure the effect of varying restraint parameters on occupant biomechanics in far-side impacts. This study sets out to demonstrate the modified TASS human facet model's (MOTHMO) capabilities in modeling whole-body response in far-side impacts. MOTHMO's dynamic response was compared to that of postmortem human subjects (PMHS), WorldSID, and Thor-NT in a series of far-side sled tests. The advantages, disadvantages, and differences of using MOTHMO compared to ATDs were highlighted and described in terms of model design and instrumentation. Potential applications and improvements for MOTHMO were also recommended. The results showed that MOTHMO is capable of replicating the seat belt-to-shoulder complex interaction, pelvis impacts, head displacement, neck and shoulder belt loading from inboard mounted belts, and impacts from multiple directions. Overall, the model performed better than Thor-NT and at least as well as WorldSID when compared to PMHS results. Though WorldSID and Thor-NT ATDs were capable of reproducing many of these impact loads, measuring the seat belt-to-shoulder complex interaction and thoracic deflection at multiple sites and directions was less accurately handled. This study demonstrated that MOTHMO is capable of modeling whole-body response in far-side impacts. Furthermore, MOTHMO can be used as a virtual design tool to explore the effect of varying restraint parameters on occupant kinematics in far-side crash configurations.

Development and field performance of indy race car head impact padding.

PubMed

Melvin, J W; Bock, H; Anderson, K; Gideon, T

2001-11-01

The close-fitting cockpit of the modern Indy car single seat race car has the potential to provide a high level of head and neck impact protection in rear and side impacts. Crash investigation has shown that a wide variety of materials have been used as the padding for these cockpits and, as a result, produced varying outcomes in crashes. Additionally, these pads have not always been positioned for optimal performance. The purpose of this study was to investigate the head impact performance of a variety of energy-absorbing padding materials under impact conditions typical of Indy car rear impacts and to identify superior materials and methods of improving their performance as race car head pads. An extensive series of tests with the helmeted Hybrid III test dummy head and neck on an impact mini-sled was conducted to explore head padding concepts. Following this, a performance specification for a simplified impact test using a rigid headform that simulates the helmeted head was developed and recommendations for performance levels of head padding based on biomechanical data on helmeted head impacts were made. In 1997, during the time that the head pad research was being performed, the Indy Racing League introduced a new chassis specification for their cars. There were a number of rear- and side-impact crashes during that season that resulted in seven severe head injuries. Examples of the head padding in those cars were included in the experimental study. The results of the head pad research were used to specify new padding materials that met the new biomechanical criteria. The placement of the head pads was also changed for better location of the padding. These changes instituted in 1998 have reduced the number of head injuries in crashes similar to or more severe than those of 1997 and have resulted in only occasional moderate head injuries (concussions) in the 1998 and 1999 seasons.

Elemental Water Impact Test: Phase 1 20-Inch Hemisphere

NASA Technical Reports Server (NTRS)

Vassilakos, Gregory J.

2015-01-01

Spacecraft are being designed based on LS-DYNA simulations of water landing impacts. The Elemental Water Impact Test (EWIT) series was undertaken to assess the accuracy of LS-DYNA water impact simulations. Phase 1 of the EWIT series featured water impact tests of a 20-inch hemisphere dropped from heights of 5 feet and 10 feet. The hemisphere was outfitted with an accelerometer and three pressure gages. The focus of this report is the correlation of analytical models against test data.

Supersonic Particle Impact Test Capabilities: Investigative Report

NASA Technical Reports Server (NTRS)

Rosales, Keisa

2007-01-01

NASA Johnson Space Center White Sands Test Facility (WSTF) performed particle impact flow tests to determine the maximum capabilities of the particle impact test systems in different configurations. Additional flow tests were performed to determine the target pressures at given upstream conditions to supplement the WSTF data located in ASTM Manual 36 (2000).

49 CFR 572.166 - Knees and knee impact test procedure.

Code of Federal Regulations, 2010 CFR

2010-10-01

... 49 Transportation 7 2010-10-01 2010-10-01 false Knees and knee impact test procedure. 572.166... Hybrid III Six-Year-Old Weighted Child Test Dummy § 572.166 Knees and knee impact test procedure. The knee assembly is assembled and tested as specified in 49 CFR 572.126 (Subpart N). ...

Impact analysis of air gap motion with respect to parameters of mooring system for floating platform

NASA Astrophysics Data System (ADS)

Shen, Zhong-xiang; Huo, Fa-li; Nie, Yan; Liu, Yin-dong

2017-04-01

In this paper, the impact analysis of air gap concerning the parameters of mooring system for the semi-submersible platform is conducted. It is challenging to simulate the wave, current and wind loads of a platform based on a model test simultaneously. Furthermore, the dynamic equivalence between the truncated and full-depth mooring system is still a tuff work. However, the wind and current loads can be tested accurately in wind tunnel model. Furthermore, the wave can be simulated accurately in wave tank test. The full-scale mooring system and the all environment loads can be simulated accurately by using the numerical model based on the model tests simultaneously. In this paper, the air gap response of a floating platform is calculated based on the results of tunnel test and wave tank. Meanwhile, full-scale mooring system, the wind, wave and current load can be considered simultaneously. In addition, a numerical model of the platform is tuned and validated by ANSYS AQWA according to the model test results. With the support of the tuned numerical model, seventeen simulation cases about the presented platform are considered to study the wave, wind, and current loads simultaneously. Then, the impact analysis studies of air gap motion regarding the length, elasticity, and type of the mooring line are performed in the time domain under the beam wave, head wave, and oblique wave conditions.

Experimental Study and Numerical Modelling of Low Velocity Impact on Laminated Composite Reinforced with Thin Film Made of Carbon Nanotubes

NASA Astrophysics Data System (ADS)

El Moumen, A.; Tarfaoui, M.; Hassoon, O.; Lafdi, K.; Benyahia, H.; Nachtane, M.

2018-04-01

In this work, polymer laminated composites based on Epon 862 Epoxy resin, T300 6 k carbon fibers and carbon nanotubes (CNTs) were tested with the aim to elucidate the effect of CNTs on impact properties including impact force and capacity to absorb impact energy. The polymer matrix was reinforced by a random distribution of CNTs with fraction ranging from 0.5 to 4.wt%. Composite panels were manufactured by using the infusion process. Taylor impact test was used to obtain the impact response of specimens. Projectile manufactured from a high strength and hardened steel with a diameter of 20 mm and 1.5 kg of mass was launched by a compressed gas gun within the velocity of 3 m/s. Impact force histories and absorbed energy of specimens were recorded. A numerical model was employed to simulate the impact performance. This model has been accomplished by forming a user established subroutine (VUMAT) and executing it in ABAQUS software. Finally, the effect of CNTs amount on dynamic properties of laminated composites was discussed.

A comparative study between experimental results and numerical predictions of multi-wall structural response to hypervelocity impact

NASA Technical Reports Server (NTRS)

Schonberg, William P.; Peck, Jeffrey A.

1992-01-01

Over the last three decades, multiwall structures have been analyzed extensively, primarily through experiment, as a means of increasing the protection afforded to spacecraft structure. However, as structural configurations become more varied, the number of tests required to characterize their response increases dramatically. As an alternative, numerical modeling of high-speed impact phenomena is often being used to predict the response of a variety of structural systems under impact loading conditions. This paper presents the results of a preliminary numerical/experimental investigation of the hypervelocity impact response of multiwall structures. The results of experimental high-speed impact tests are compared against the predictions of the HULL hydrodynamic computer code. It is shown that the hypervelocity impact response characteristics of a specific system cannot be accurately predicted from a limited number of HULL code impact simulations. However, if a wide range of impact loadings conditions are considered, then the ballistic limit curve of the system based on the entire series of numerical simulations can be used as a relatively accurate indication of actual system response.

30 CFR 7.46 - Impact test.

Code of Federal Regulations, 2010 CFR

2010-07-01

... 30 Mineral Resources 1 2010-07-01 2010-07-01 false Impact test. 7.46 Section 7.46 Mineral... MINING PRODUCTS TESTING BY APPLICANT OR THIRD PARTY Battery Assemblies § 7.46 Impact test. (a) Test... individual cells. At the test temperature range of 65 °F -80 °F (18.3 °C-26.7 °C), apply a dynamic force of...

30 CFR 7.46 - Impact test.

Code of Federal Regulations, 2013 CFR

2013-07-01

... 30 Mineral Resources 1 2013-07-01 2013-07-01 false Impact test. 7.46 Section 7.46 Mineral... MINING PRODUCTS TESTING BY APPLICANT OR THIRD PARTY Battery Assemblies § 7.46 Impact test. (a) Test... individual cells. At the test temperature range of 65 °F -80 °F (18.3 °C-26.7 °C), apply a dynamic force of...

30 CFR 7.46 - Impact test.

Code of Federal Regulations, 2011 CFR

2011-07-01

... 30 Mineral Resources 1 2011-07-01 2011-07-01 false Impact test. 7.46 Section 7.46 Mineral... MINING PRODUCTS TESTING BY APPLICANT OR THIRD PARTY Battery Assemblies § 7.46 Impact test. (a) Test... individual cells. At the test temperature range of 65 °F -80 °F (18.3 °C-26.7 °C), apply a dynamic force of...

The I Don't Know Option in the Vocabulary Size Test

ERIC Educational Resources Information Center

Zhang, Xian

2013-01-01

The current study evaluates guessing behaviors in a vocabulary size test (VST) and examines whether including an "I don't know" in a VST may have an impact on the results of the test. One-hundred-fifty first-year students at a university in China took part in the study. They were randomly assigned to three groups. Each group took a…

ACT Test Preparation Course and Its Impact on Students' College- and Career-Readiness

ERIC Educational Resources Information Center

Parrott, Timothy Nolan

2012-01-01

This study examined the effectiveness of an ACT intervention course developed for high school juniors at Anderson County High School during the 2011-2012 school year. This study compared the ACT composite test scores of the treatment group to the ACT composite test scores of the control group by using their PLAN scores as a baseline, to determine…

The Impact of Testing Frequency on Student Performance in a Marketing Course

ERIC Educational Resources Information Center

Kling, Nathan; McCorkle, Denny; Miller, Chip; Reardon, James

2005-01-01

Testing frequency has long been examined in the social sciences as an antecedent to student performance in the classroom. However, after nearly 70 years of study, the results are inconclusive. Given the developments in computerized testing over the last decade, professors now have the ability to create and conduct frequent tests without severely…

The Impact of Receiving the Same Items on Consecutive Computer Adaptive Test Administrations.

ERIC Educational Resources Information Center

O'Neill, Thomas; Lunz, Mary E.; Thiede, Keith

2000-01-01

Studied item exposure in a computerized adaptive test when the item selection algorithm presents examinees with questions they were asked in a previous test administration. Results with 178 repeat examinees on a medical technologists' test indicate that the combined use of an adaptive algorithm to select items and latent trait theory to estimate…

[Assessment of land use environmental impacts in urban built-up area: a case study in main built-up area of Nanchang City].

PubMed

Chen, Wen-Bo; Liu, Shi-Yu; Yu, Dun; Zou, Qiu-Ming

2009-07-01

Based on the relevant studies of land use environmental impacts and the characteristics of urban land use, a conceptual model on the assessment of land use environmental impacts in urban built-up area was established. This model grouped the land use environmental impacts in built-up area into four basic processes, i. e., detailization, abstractization, matching, and evaluation. A case study was conducted in the main built-up area of Nanchang City, with noise, smell, dust, and hazard as the impact factors. In the test area, noise had a widespread impact, its impacting area accounting for 59% of the total, smell and dust impacts centralized in the east and south parts, while hazard impact was centralized in the southeast part, an industrial area. This assessment model of four basic processes was practical, and could provide basis for the decision-making of urban land use management and planning.

A Comparison of Quasi-Static Indentation and Drop-Weight Impact Testing on Carbon-Epoxy Laminates

NASA Technical Reports Server (NTRS)

Prabhakaran, R.

2001-01-01

The project had two objectives: 1) The primary objective was to characterize damage tolerance of composite materials. To accomplish this, polymer matrix composites were to be subjected to static indentation as well as low-velocity impacts and the results analyzed. 2) A second objective was to investigate the effects of laser shock peening on the damage tolerance of aerospace materials, such as aluminum alloys, in terms of crack nucleation and crack propagation. The impact testing was proposed to be performed using a Dynatup drop tower. The specimens were to be placed over a square opening in a steel platen and impacted with a hemispherical tup. The damage was to be characterized in the laminate specimens. The damage tolerance of aerospace alloys was to be studied by conducting fatigue tests on aluminum alloy specimens with prior shock peening treatment. The crack length was to be monitored by a microscope and the crack propagation rate, da/dN, determined.

Limited evidence for affective and diurnal rhythm responses to dim light-at-night in male and female C57Bl/6 mice.

PubMed

Cleary-Gaffney, Michael; Coogan, Andrew N

2018-05-15

Circadian rhythms are recurring patterns in a range of behavioural, physiological and molecular parameters that display periods of near 24 h, and are underpinned by an endogenous biological timekeeping system. Circadian clocks are increasingly recognised as being key for health. Environmental light is the key stimulus that synchronises the internal circadian system with the external time cues. There are emergent health concerns regarding increasing worldwide prevalence of electric lighting, especially man-made light-at-night, and light's impact on the circadian system may be central to these effects. A number of previous studies have demonstrated increased depression-like behaviour in various rodent experimental models exposed to dim light-at-night. In this study we set out to study the impact of dim light-at-night on circadian and affective behaviours in C57Bl/6 mice. We set out specifically to examine the impact of sex on light at night's effects, as well as the impact of housing conditions. We report minimal impact of light-at-night on circadian and affective behaviours, as measured by the tail suspension test, the forced swim test, the sucrose preference test and the elevated plus maze. Light-at-night was also not associated with an increase in body weight, but was associated with a decrease in the cell proliferation marker Ki-67 in the dentate gyrus. In summary, we conclude that experimental contextual factors, such as model species or strain, may be considerable importance in the investigation of the impact of light at night on mood-related parameters. Copyright © 2018 Elsevier Inc. All rights reserved.

Impact of add-on laboratory testing at an academic medical center: a five year retrospective study.

PubMed

Nelson, Louis S; Davis, Scott R; Humble, Robert M; Kulhavy, Jeff; Aman, Dean R; Krasowski, Matthew D

2015-01-01

Clinical laboratories frequently receive orders to perform additional tests on existing specimens ('add-ons'). Previous studies have examined add-on ordering patterns over short periods of time. The objective of this study was to analyze add-on ordering patterns over an extended time period. We also analyzed the impact of a robotic specimen archival/retrieval system on add-on testing procedure and manual effort. In this retrospective study at an academic medical center, electronic health records from were searched to obtain all add-on orders that were placed in the time period of May 2, 2009 to December 31, 2014. During the time period of retrospective study, 880,359 add-on tests were ordered on 96,244 different patients. Add-on testing comprised 3.3 % of total test volumes. There were 443,411 unique ordering instances, leading to an average of 1.99 add-on tests per instance. Some patients had multiple episodes of add-on test orders at different points in time, leading to an average of 9.15 add-on tests per patient. The majority of add-on orders were for chemistry tests (78.8 % of total add-ons) with the next most frequent being hematology and coagulation tests (11.2 % of total add-ons). Inpatient orders accounted for 66.8 % of total add-on orders, while the emergency department and outpatient clinics had 14.8 % and 18.4 % of total add-on orders, respectively. The majority of add-ons were placed within 8 hours (87.3 %) and nearly all by 24 hours (96.8 %). Nearly 100 % of add-on orders within the emergency department were placed within 8 hours. The introduction of a robotic specimen archival/retrieval unit saved an average of 2.75 minutes of laboratory staff manual time per unique add-on order. This translates to 24.1 hours/day less manual effort in dealing with add-on orders. Our study reflects the previous literature in showing that add-on orders significantly impact the workload of the clinical laboratory. The majority of add-on orders are clinical chemistry tests, and most add-on orders occur within 24 hours of original specimen collection. Robotic specimen archival/retrieval units can reduce manual effort in the clinical laboratory associated with add-on orders.

Soil analyses and evaluations at the impact dynamics research facility for two full-scale aircraft crash tests

NASA Technical Reports Server (NTRS)

Cheng, R. Y. K.

1977-01-01

The aircraft structural crash behavior and occupant survivability for aircraft crashes on a soil surface was studied. The results of placement, compaction, and maintenance of two soil test beds are presented. The crators formed by the aircraft after each test are described.

"Tackling Test Anxiety": A Group for College Students

ERIC Educational Resources Information Center

Damer, Diana E.; Melendres, Lauren T.

2011-01-01

Test anxiety is ubiquitous on college campuses and negatively impacts academic progress as well as overall mental and physical health. Some students develop test anxiety due to poor study skills, while others experience debilitating anxiety despite adequate preparation. In this article, a session-by-session description of a 4-week group…

Standardized Test Results: An Opportunity for English Program Improvement

ERIC Educational Resources Information Center

Jiménez, Maureyra; Rodríguez, Caroll; Rey Paba, Lourdes

2017-01-01

This case study explores the relationship between the results obtained by a group of Industrial Engineering students on a national standardized English test and the impact these results had on language program improvement. The instruments used were interviews, document analysis, observations, surveys, and test results analysis. Findings indicate…

Credit Building in IDA Programs: Early Findings of a Longitudinal Study

ERIC Educational Resources Information Center

Birkenmaier, Julie; Curley, Jami; Kelly, Patrick

2012-01-01

Objective: This article reports on the impact of the Individual Development Account (IDA) program on credit. Method: Using a convenience sample of IDA participants (N = 165), data were analyzed using paired sample "t" tests, independent sample "t" test, one-way analysis of variance, Mann-Whitney "U" Tests, and…

75 FR 43988 - Agency Forms Undergoing Paperwork Reduction Act Review

Federal Register 2010, 2011, 2012, 2013, 2014

2010-07-27

.... Quantitative surveys will be administered by computers and personal interviews will be conducted to collect... approval to administer a survey, conduct interviews and offer HIV rapid testing in black men who have sex... testing, and declining an HIV test will not negatively impact their study participation. The research...

The Impact of Back-Sputtered Carbon on the Accelerator Grid Wear Rates of the NEXT and NSTAR Ion Thrusters

NASA Technical Reports Server (NTRS)

Soulas, George C.

2013-01-01

A study was conducted to quantify the impact of back-sputtered carbon on the downstream accelerator grid erosion rates of the NASA's Evolutionary Xenon Thruster (NEXT) Long Duration Test (LDT1). A similar analysis that was conducted for the NASA's Solar Electric Propulsion Technology Applications Readiness Program (NSTAR) Life Demonstration Test (LDT2) was used as a foundation for the analysis developed herein. A new carbon surface coverage model was developed that accounted for multiple carbon adlayers before complete surface coverage is achieved. The resulting model requires knowledge of more model inputs, so they were conservatively estimated using the results of past thin film sputtering studies and particle reflection predictions. In addition, accelerator current densities across the grid were rigorously determined using an ion optics code to determine accelerator current distributions and an algorithm to determine beam current densities along a grid using downstream measurements. The improved analysis was applied to the NSTAR test results for evaluation. The improved analysis demonstrated that the impact of back-sputtered carbon on pit and groove wear rate for the NSTAR LDT2 was negligible throughout most of eroded grid radius. The improved analysis also predicted the accelerator current density for transition from net erosion to net deposition considerably more accurately than the original analysis. The improved analysis was used to estimate the impact of back-sputtered carbon on the accelerator grid pit and groove wear rate of the NEXT Long Duration Test (LDT1). Unlike the NSTAR analysis, the NEXT analysis was more challenging because the thruster was operated for extended durations at various operating conditions and was unavailable for measurements because the test is ongoing. As a result, the NEXT LDT1 estimates presented herein are considered preliminary until the results of future post-test analyses are incorporated. The worst-case impact of carbon back-sputtering was determined to be the full power operating condition, but the maximum impact of back-sputtered carbon was only a 4 percent reduction in wear rate. As a result, back-sputtered carbon is estimated to have an insignificant impact on the first failure mode of the NEXT LDT1 at all operating conditions.

Middle School Mathematics: A Study of Three Programs in South Texas

ERIC Educational Resources Information Center

Ellis, Joanetta Dowell

2011-01-01

In 2010, the Texas Assessment of Knowledge and Skills (TAKS) began its seventh year of testing (Texas Education Agency, 2009a). High stakes testing is a reality. This study considered the impact on mathematics achievement based on the mathematics program students were receiving during their middle school years. The purpose of this study was to…

Genotoxicity potential of a new natural formicide.

PubMed

Cotelle, Sylvie; Testolin, Renan C; Foltête, Anne-Sophie; Bossardi-Rissardi, Georgiana; Silveira, Rosilene A; Radetski, Claudemir M

2012-03-01

Assessment of environmental impacts from pesticide utilization should include genotoxicity studies, where the possible effects of mutagenic/genotoxic substances on individuals are assessed. In this study, the genotoxicity profile of the new formicide Macex® was evaluated with two genotoxicity tests, namely, the micronucleus test with mouse bone marrow and Vicia faba, and a mutagenicity test using the Ames Salmonella assay. The bacterial reverse mutation test (Salmonella typhimurium strains TA97, TA98, TA100, TA102, and TA1535), the Vicia root tip and mouse micronucleus tests were conducted according to published protocols. In the range of the formicide Macex® concentrations tested from 0.06 to 1.0 g L⁻¹ (or mgkg⁻¹ in the mouse test), no genotoxicity was observed in the prokaryotic or eukaryotic test organisms. However, at Macex® concentrations of 0.5 g L⁻¹ and above a significant decrease in the mitotic index (P ≤ 0.05) in the V. faba was observed. Micronucleus formation was likewise increased in the test organism at concentrations starting at 2.0 g L⁻¹. These data allow us to classify this natural formicide preparation as a product with no geno-environmental-impact when applied at recommended concentrations.

The impact of problem solving strategy with online feedback on students’ conceptual understanding

NASA Astrophysics Data System (ADS)

Pratiwi, H. Y.; Winarko, W.; Ayu, H. D.

2018-04-01

The study aimed to determine the impact of the implementation of problem solving strategy with online feedback towards the students’ concept understanding. This study used quasi experimental design with post-test only control design. The participants were all Physics Education students of Kanjuruhan University year 2015. Then, they were divided into two different groups; 30 students belong to experiment class and the remaining 30 students belong to class of control. The students’ concept understanding was measured by the concept understanding test on multiple integral lesson. The result of the concept understanding test was analyzed by prerequisite test and stated to be normal and homogenic distributed, then the hypothesis was examined by T-test. The result of the study shows that there is difference in the concept understanding between experiment class and control class. Next, the result also shows that the students’ concept understanding which was taught using problem solving strategy with online feedback was higher than those using conventional learning; with average score of 72,10 for experiment class and 52,27 for control class.

The impact of an integrated hospital-community medical information system on quality and service utilization in hospital departments.

PubMed

Nirel, Nurit; Rosen, Bruce; Sharon, Assaf; Blondheim, Orna; Sherf, Michael; Samuel, Hadar; Cohen, Arnon D

2010-09-01

In 2005, an innovative system of hospital-community on-line medical records (OFEK) was implemented at Clalit Health Services (CHS). The goals of the study were to examine the extent of OFEK's use and its impact on quality indicators and medical-service utilization in Internal Medicine and General Surgery wards of CHS hospitals. Examining the frequency of OFEK's use with its own track-log data; comparing, "before" and "after", quality indicators and service utilization data in experimental (CHS patients) versus control groups (other patients). OFEK's use increased by tens of percentages each year, Internal Medicine wards showed a significant decrease in the number of laboratory tests and 3 CT tests performed compared with the control group. Wards using OFEK extensively showed a greater decrease in CT tests, in one imaging test, and in the average number of ambulatory hospitalizations. No similar changes were found in General Surgery wards. The study helps evaluate the extent to which OFEK's targets were achieved and contributes to the development of measures to examine the impact of such systems, which can be used to assess a broad range of Health Information Technology (HIT) systems. Copyright 2010 Elsevier Ireland Ltd. All rights reserved.

Utility of the ImPACT test with deaf adolescents.

PubMed

Reesman, Jennifer; Pineda, Jill; Carver, Jenny; Brice, Patrick J; Zabel, T Andrew; Schatz, Philip

2016-02-01

The goals of the study included empirical examination of the utility of the Immediate and Post-Concussion Assessment and Cognitive Testing (ImPACT) test with adolescents who are deaf or hard-of-hearing and to investigate patterns of performance at baseline that may arise in the assessment of this population. Baseline assessment of student-athletes has been conducted on a widespread scale with focus on performance of typically developing student-athletes and some clinical groups, though to date no studies have examined adolescents who are deaf or hard-of-hearing. Retrospective and de-identified ImPACT baseline test used with deaf and hard-of-hearing high-school student-athletes (N = 143; 66% male, mean age = 16.11) was examined. Review indicated significant differences in some composite scores between the deaf and hard-of-hearing group and hearing normative comparisons. A possible marker of task misunderstanding was identified to occur more frequently within the deaf and hard-of-hearing sample (13% in deaf sample vs. .31% in hearing sample). Results may provide support for the consideration and use of additional measures to ensure comprehension of task demands when considering this tool for use with deaf and hard-of-hearing adolescents.

Etude comparative sur la propagation de l'endommagement apres impact des composites carbone/epoxy renforces par piquage au fil Kevlar et titane-nickel

NASA Astrophysics Data System (ADS)

Vachon, Pierre-Luc

Composite laminates have strong in-plane mechanical properties, but they are generally weaker through their thickness. This specificity makes the laminates prone to delamination, particularly under low-velocity impact loads. Consequently numerous research efforts have been dedicated to developing interlaminar reinforcing methods, such as transverse stitching. The present project proposes the use of the stitching technique combined with a special stitching thread made of superelastic TiNi alloy. This technology is intended to improve the delamination toughness in composite laminates loaded in bending. In the first part of this study a numerical model was developed for analyzing composite structures. The 3-D finite element model was built with the ANSYS commercial software using 20-node solid and 8-node shell elements. The progressive damage modeling technique was used, allowing the prediction of delamination propagation in a laminate submitted to various loading modes. The model was validated for a plate under quasi-static traction load, and it was then used to simulate three-point bending tests. Secondly, carbon/epoxy composite panels were fabricated, with each panel containing unstitched and stitched specimens. Two different materials were used for the stitching thread: superelastic TiNi wires and Kevlar threads as a reference. Some stitched specimens were cut in slices in order to make some observations of the internal stitch using an optical microscope. Standardized low-velocity impact tests and compression after impact tests were carried out on stitched and unstitched specimens (ASTM D7136 and D7137). The Kevlar reinforcements have shown great performance in reducing the delaminated zone after impact, as well as in improving the residual compression strength. The TiNi reinforcements provided encouraging results during the impact tests, though being less effective than the Kevlar threads. During the compression after impact tests, only a slight difference could be measured between the TiNi-stitched and the unstitched specimens. Then the bending performance of the specimens was quantified experimentally by calculating the energy required to create a unit volume of damaged material (Gv, J/mm3). This metric is similar to the Strain Energy Release Rate (SERR) commonly used in studies on delamination. According to the experimental results, the damage resistance in three-point bending was not improved by the Kevlar reinforcements, despite the reduced damaged zone after the impact test. Indeed, when the strain energy in bending is relativized to the induced damaged volume during propagation, it turns out that the TiNi reinforcements are more effective than the Kevlar's for improving the damage resistance. Finally, the numerical study on the behavior of both types of stitched reinforcements allowed identifying subtle differences between those. Indeed, both stitching threads (TiNi and Kevlar) promoted the interlaminar propagation of the delamination during simulation of the bending test, with this behavior being less pronounced for the TiNi-stitched plate. However the Kevlar threads seemed more effective for stopping this propagation in the zones between the stitches. Keywords: composite materials, stitching, numerical model, shape memory alloy, three-point bending, low-velocity impact, ultrasound imaging.

Does fatigue have any impact on satisfaction of search?

NASA Astrophysics Data System (ADS)

Krupinski, Elizabeth A.; Schartz, Kevin; Caldwell, Robert; Madsen, Mark; Berbaum, Kevin S.

2017-03-01

Previous studies have demonstrated that fatigue impacts diagnostic accuracy, especially for those in training. We continued this line of investigation to determine if fatigue has any impact on a common source of errors - satisfaction of search (SOS). SOS requires subjects to participate in 2 sessions (SOS and non-SOS) and so does fatigue (fatigued and not fatigued) so we ran subjets in only the fatigued condition and used a previous non-fatigued study as the comparison. We used 64 chest computed radiographs half demonstrating various ``test'' abnormalities were read twice by 20 radiologists, once with and once without the addition of a simulated pulmonary nodule. Receiver-operating characteristic detection accuracy and decision thresholds were analyzed to study the effects of adding the nodule on detecting the test abnormalities. Adding nodules did not influence detection accuracy (ROC AUC SOS = 0.667; non-SOS = 0.679), but did induce a reluctance to report them. Adding nodules did not affect inspection time so the reluctance to report was not associated with reduced search. Fatigue did not appear to exacerbate the SOS effect. A second study with fractures revealed the same shift in performance but did reduce viewing times when fatigued. The results of these two studies suggest that the impact of fatigue on SOS is more complicated than expected and thus may require more investigation to fully understand its impact in the clinic.

Self-Reported Impact of Chlamydia Testing on Subsequent Behavior: Results of an Online Survey of Young Adults in England.

PubMed

Hartney, Thomas; Baraitser, Paula; Nardone, Anthony

2015-09-01

The National Chlamydia Screening Programme performs 1.7 million tests annually among young adults in England. The effect of chlamydia screening on subsequent behavior is unknown. This study examined the self-reported impact of testing on young adults' subsequent health care-seeking and sexual behavior. We conducted a cross-sectional Web-based anonymous survey using an online panel to recruit 1521 young adults aged 16 to 24 years and resident in England. Survey questions were developed using the theory of planned behavior. Multivariate log-binomial regression was used to identify the variables associated with an impact on subsequent behavior after testing. Most respondents reported that being tested for chlamydia had a positive effect on their subsequent sexual behavior (68.6%; 422/615) or health care-seeking behavior (80.0%; 492/615). In multivariate analysis, being female and having a high level of engagement at last test were both associated with positive impacts on sexual behavior (72.7% [adjusted prevalence ratio {aPR}, 1.19; 95% confidence interval {CI}, 1.07-1.33] and 82.7% [aPR, 1.55; 95% CI, 1.27-1.89], respectively), and health care-seeking behavior (84.4% [aPR, 1.13; 95% Cl, 1.04-1.24] and 86.3% [aPR, 1.23; 95% CI, 1.07-1.41], respectively). Among respondents with minimum level of engagement, 72.4% (76/105) reported an increase in subsequent health care-seeking behavior. Chlamydia testing had a positive impact on young adults' self-reported health care-seeking and sexual behavior. This suggests that chlamydia screening has a wider effect on young adults' sexual health beyond that of treatment alone.

Evaluation of wheelchair drop seat crashworthiness.

PubMed

Bertocci, G; Ha, D; van Roosmalen, L; Karg, P; Deemer, E

2001-05-01

Wheelchair seating crash performance is critical to protecting wheelchair users who remain seated in their wheelchairs during transportation. Relying upon computer simulation and sled testing seat loads associated with a 20 g/48 kph (20 g/30 mph) frontal impact and 50th percentile male occupant were estimated to develop test criteria. Using a static test setup we evaluated the performance of various types of commercially available drop seats against the loading test criteria. Five different types of drop seats (two specimens each) constructed of various materials (i.e. plastics, plywood, metal) were evaluated. Two types of drop seats (three of the total 10 specimens) met the 16650 N (3750 lb) frontal impact test criteria. While additional validation of the test protocol is necessary, this study suggests that some drop seat designs may be incapable of withstanding crash level loads.

Performance enhanced headgear: a scientific approach to the development of protective headgear

PubMed Central

McIntosh, A; McCrory, P; Finch, C

2004-01-01

Background: There is a continuing debate about the performance of protective headgear in rugby union, rugby league, and Australian rules football. Objectives: To examine the impact energy attenuation performance of foam that could be incorporated into headgear and examine the performance of prototypes of modified headgear. Methods: Impact tests were conducted on polyethylene foams and protective headgear. Free fall drop tests with a rigid headform on to a flat rigid anvil were conducted. Resultant headform acceleration was measured. Means of the headform acceleration maxima for repeat tests were calculated. Results: Tests on polyethylene foam indicated that an increase in thickness from 10 mm to 16 mm would improve headgear performance. These modifications were incorporated in part into two headgear models: the Albion Headpro and the Canterbury brand Body Armour honeycomb headgear. The headgear tests show that significant reductions in headform acceleration were achieved by increasing the foam density and thickness. Mean headform acceleration maxima for the 16 mm thick modified rugby headgear was about 25% of that of standard headgear for lateral impact 0.3 and 0.4 m drop heights and 27% for the centre front 0.3 m drop tests. At these impacts, the headform acceleration for the modified rugby headgear was below 200 g. Conclusions: Significant improvements in impact energy attenuation performance are possible with small design changes. Whether these are sufficient to reduce the rate or severity of concussion in rugby and Australian rules football can only be shown by formal prospective studies on the field. PMID:14751945

Hypervelocity Microparticle Impact Studies: Simulating Cosmic Dust Impacts on the Dustbuster

NASA Technical Reports Server (NTRS)

Austin, D. E.; Manning, H. L. K.; Bailey, C. L.; Farnsworth, J. T.; Ahrens, T. J.; Beauchamp, J. L.

2002-01-01

Iron and copper microparticles accelerated to 2-20 km/s in a 2 MV Van de Graaff accelerator were used to test a recently-developed cosmic dust mass spectrometer, known as the Dustbuster. Additional information is contained in the original extended abstract.

Threshold Studies on TNT, Composition B, and C-4 Explosives Using the Steven Impact Test

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

Vandersall, K S; Switzer, L L; Garcia, F

2005-09-26

Steven Impact Tests were performed at low velocity on the explosives TNT, Comp B, and C-4 in attempts to obtain a threshold for reaction. A 76 mm helium driven gas gun was used to accelerate the Steven Test projectiles up to approximately 200 m/s in attempts to react (ignite) the explosive samples. Blast overpressure gauges, acoustic microphones, standard video and high-speed photography were used to characterize the level of any high explosive reaction violence. No bulk reactions were observed in the TNT, Composition B, or C-4 explosive samples impacted up to velocities in the range of 190-200 m/s. This workmore » will outline the experimental details and discuss the lack of reaction when compared to the reaction thresholds of other common explosives.« less

Factors Influencing Occupant-To-Seat Belt Interaction in Far-Side Crashes

PubMed Central

Douglas, C.A.; Fildes, B.N.; Gibson, T.J.; Boström, O.; Pintar, F.A.

2007-01-01

Seat belt interaction with a far-side occupant’s shoulder and thorax is critical to governing excursion towards the struck-side of the vehicle in side impact. In this study, occupant-to-belt interaction was simulated using a modified MADYMO human model and finite element belts. Quasi-static tests with volunteers and dynamic sled tests with PMHS and WorldSID were used for model validation and comparison. Parameter studies were then undertaken to quantify the effect of impact direction, seat belt geometry and pretension on occupant-to-seat belt interaction. Results suggest that lowering the D-ring and increasing pretension reduces the likelihood of the belt slipping off the shoulder. Anthropometry was also shown to influence restraint provided by the shoulder belt. Furthermore, the belt may slip off the occupant’s shoulder at impact angles greater than 40 degrees from frontal when no pretension is used. However, the addition of pretension allowed the shoulder to engage the belt in all impacts from 30 to 90 degrees. PMID:18184500

A Comparison of Quasi-Static Indentation to Low-Velocity Impact

NASA Technical Reports Server (NTRS)

Nettles, A. T.; Douglas, M. J.

2000-01-01

A static test method for modeling low-velocity foreign object impact events to composites would prove to be very beneficial to researchers since much more data can be obtained from a static test than from an impact test. In order to examine if this is feasible, a series of static indentation and low-velocity impact tests were carried out and compared. Square specimens of many sizes and thicknesses were utilized to cover the array of types of low velocity impact events. Laminates with a pi/4 stacking sequence were employed since this is by far the most common type of engineering laminate. Three distinct flexural rigidities -under two different boundary conditions were tested in order to obtain damage ranging from that due to large deflection to contact stresses and levels in-between to examine if the static indentation-impact comparisons are valid under the spectrum of damage modes that can be experienced. Comparisons between static indentation and low-velocity impact tests were based on the maximum applied transverse load. The dependent parameters examined included dent depth, back surface crack length, delamination area, and to a limited extent, load-deflection behavior. Results showed that no distinct differences could be seen between the static indentation tests and the low-velocity impact tests, indicating that static indentation can be used to represent a low-velocity impact event.

Impact of Fibromyalgia in the Sit-to-Stand-to-Sit Performance Compared With Healthy Controls.

PubMed

Collado-Mateo, Daniel; Adsuar, Jose C; Dominguez-Muñoz, Francisco J; Olivares, Pedro R; Gusi, Narcis

2017-06-01

Fibromyalgia is associated with a reduction in the ability to perform activities of daily living. Sit-to-stand-to-sit performance is one of the most common activities of daily living and often is evaluated by counting the number of repetitions of the 30-second chair-stand test. No study, however, has examined the performance over the 30 seconds of this test of female patients with fibromyalgia on a phase-by-phase basis. To evaluate the impact of fibromyalgia on performance of the 30-second chair-stand test and to analyze how the kinematic performance changed over the 30-second test period. A cross-sectional study. Local association of fibromyalgia. Fifteen females with fibromyalgia and nine healthy female controls. Participants performed the 30-second chair-stand test while wearing a motion capture device. Duration of each sit-to-stand-to-sit phase within the 30-second time limit was compared between groups using repeated measures analysis of variance. The association between duration of phases and scores from the revised version of the Fibromyalgia Impact Questionnaire was tested using bivariate correlations. The duration of impulse and sit-to-stand phases were gradually increased over the 30 seconds of the chair-stand test for women with fibromyalgia compared with healthy controls (P = .04 and P = .02, respectively). The mean duration of these 2 phases was associated with symptom duration and the function domain of the revised version of the Fibromyalgia Impact Questionnaire (P < .05). Also, stiffness was directly associated with the duration of the stand-up phase (P = .04). Kinematic performance during the 30-second chair-stand test differed between women with fibromyalgia and healthy controls. Since sit-to-stand from a chair is a common daily activity, women with fibromyalgia may require specific exercises to improve performance of this task. Not applicable. Copyright © 2017 American Academy of Physical Medicine and Rehabilitation. Published by Elsevier Inc. All rights reserved.

Factor structure and measurement invariance of the Health Education Impact Questionnaire: Does the subjectivity of the response perspective threaten the contextual validity of inferences?

PubMed Central

Elsworth, Gerald R; Nolte, Sandra

2015-01-01

Objective: On-going evidence is required to support the validity of inferences about change and group differences in the evaluation of health programs, particularly when self-report scales requiring substantial subjectivity in response generation are used as outcome measures. Following this reasoning, the aim of this study was to replicate the factor structure and investigate the measurement invariance of the latest version of the Health Education Impact Questionnaire, a widely used health program evaluation measure. Methods: An archived dataset of responses to the most recent version of the English-language Health Education Impact Questionnaire that uses four rather than six response options (N = 3221) was analysed using exploratory structural equation modelling and confirmatory factor analysis appropriate for ordered categorical data. Metric and scalar invariance were studied following recent recommendations in the literature to apply fully invariant unconditional models with minimum constraints necessary for model identification. Results: The original eight-factor structure was replicated and all but one of the scales (Self Monitoring and Insight) was found to consist of unifactorial items with reliability of ⩾0.8 and satisfactory discriminant validity. Configural, metric and scalar invariance were established across pre-test to post-test and population sub-groups (sex, age, education, ethnic background). Conclusion: The results support the high level of interest in the Health Education Impact Questionnaire, particularly for use as a pre-test/post-test measure in experimental studies, other pre–post evaluation designs and system-level monitoring and evaluation. PMID:26770785

Effects of non-invasive brain stimulation on associative memory

DOE PAGES

Matzen, Laura E.; Trumbo, Michael C.; Leach, Ryan C.; ...

2015-07-30

Associative memory refers to remembering the association between two items, such as a face and a name. It is a crucial part of daily life, but it is also one of the first aspects of memory performance that is impacted by aging and by Alzheimer’s disease. Evidence suggests that transcranial direct current stimulation (tDCS) can improve memory performance, but few tDCS studies have investigated its impact on associative memory. In addition, no prior study of the effects of tDCS on memory performance has systematically evaluated the impact of tDCS on different types of memory assessments, such as recognition and recallmore » tests. In this study, we measured the effects of tDCS on associative memory performance in healthy adults, using both recognition and recall tests. Participants studied face-name pairs while receiving either active (30 minutes, 2 mA) or sham (30 minutes, 0.1 mA) stimulation with the anode placed at F9 and the cathode placed on the contralateral upper arm. Participants in the active stimulation group performed significantly better on the recall test than participants in the sham group, recalling 50% more names, on average, and making fewer recall errors. However, the two groups did not differ significantly in terms of their performance on the recognition memory test. This investigation provides evidence that stimulation at the time of study improves associative memory encoding, but that this memory benefit is evident only under certain retrieval conditions.« less

Effects of non-invasive brain stimulation on associative memory.

PubMed

Matzen, Laura E; Trumbo, Michael C; Leach, Ryan C; Leshikar, Eric D

2015-10-22

Associative memory refers to remembering the association between two items, such as a face and a name. It is a crucial part of daily life, but it is also one of the first aspects of memory performance that is impacted by aging and by Alzheimer's disease. Evidence suggests that transcranial direct current stimulation (tDCS) can improve memory performance, but few tDCS studies have investigated its impact on associative memory. In addition, no prior study of the effects of tDCS on memory performance has systematically evaluated the impact of tDCS on different types of memory assessments, such as recognition and recall tests. In this study, we measured the effects of tDCS on associative memory performance in healthy adults, using both recognition and recall tests. Participants studied face-name pairs while receiving either active (30 min, 2 mA) or sham (30 min, 0.1 mA) stimulation with the anode placed at F9 and the cathode placed on the contralateral upper arm. Participants in the active stimulation group performed significantly better on the recall test than participants in the sham group, recalling 50% more names, on average, and making fewer recall errors. However, the two groups did not differ significantly in terms of their performance on the recognition memory test. This investigation provides evidence that stimulation at the time of study improves associative memory encoding, but that this memory benefit is evident only under certain retrieval conditions. Copyright © 2015 Elsevier B.V. All rights reserved.

Effects of non-invasive brain stimulation on associative memory

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

Matzen, Laura E.; Trumbo, Michael C.; Leach, Ryan C.

Associative memory refers to remembering the association between two items, such as a face and a name. It is a crucial part of daily life, but it is also one of the first aspects of memory performance that is impacted by aging and by Alzheimer’s disease. Evidence suggests that transcranial direct current stimulation (tDCS) can improve memory performance, but few tDCS studies have investigated its impact on associative memory. In addition, no prior study of the effects of tDCS on memory performance has systematically evaluated the impact of tDCS on different types of memory assessments, such as recognition and recallmore » tests. In this study, we measured the effects of tDCS on associative memory performance in healthy adults, using both recognition and recall tests. Participants studied face-name pairs while receiving either active (30 minutes, 2 mA) or sham (30 minutes, 0.1 mA) stimulation with the anode placed at F9 and the cathode placed on the contralateral upper arm. Participants in the active stimulation group performed significantly better on the recall test than participants in the sham group, recalling 50% more names, on average, and making fewer recall errors. However, the two groups did not differ significantly in terms of their performance on the recognition memory test. This investigation provides evidence that stimulation at the time of study improves associative memory encoding, but that this memory benefit is evident only under certain retrieval conditions.« less

GED Test Changes and Attainment: Overview of 2014 GED Test Changes and Attainment in Washington State

ERIC Educational Resources Information Center

Larson, Kara; Gaeta, Cristina; Sager, Lou

2016-01-01

In January 2014, the GED Testing Service significantly redesigned the GED test to incorporate the Common Core State Standards and the College and Career Readiness Standards for Adult Education. The purpose of this study was to examine the significant changes made to the test in 2014, examine the impact of the changes on Washingtonians, and make…

Low velocity instrumented impact testing of four new damage tolerant carbon/epoxy composite systems

NASA Technical Reports Server (NTRS)

Lance, D. G.; Nettles, A. T.

1990-01-01

Low velocity drop weight instrumented impact testing was utilized to examine the damage resistance of four recently developed carbon fiber/epoxy resin systems. A fifth material, T300/934, for which a large data base exists, was also tested for comparison purposes. A 16-ply quasi-isotropic lay-up configuration was used for all the specimens. Force/absorbed energy-time plots were generated for each impact test. The specimens were cross-sectionally analyzed to record the damage corresponding to each impact energy level. Maximum force of impact versus impact energy plots were constructed to compare the various systems for impact damage resistance. Results show that the four new damage tolerant fiber/resin systems far outclassed the T300/934 material. The most damage tolerant material tested was the IM7/1962 fiber/resin system.

A Residual Mass Ballistic Testing Method to Compare Armor Materials or Components (Residual Mass Ballistic Testing Method)

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

Benjamin Langhorst; Thomas M Lillo; Henry S Chu

2014-05-01

A statistics based ballistic test method is presented for use when comparing multiple groups of test articles of unknown relative ballistic perforation resistance. The method is intended to be more efficient than many traditional methods for research and development testing. To establish the validity of the method, it is employed in this study to compare test groups of known relative ballistic performance. Multiple groups of test articles were perforated using consistent projectiles and impact conditions. Test groups were made of rolled homogeneous armor (RHA) plates and differed in thickness. After perforation, each residual projectile was captured behind the target andmore » its mass was measured. The residual masses measured for each test group were analyzed to provide ballistic performance rankings with associated confidence levels. When compared to traditional V50 methods, the residual mass (RM) method was found to require fewer test events and be more tolerant of variations in impact conditions.« less

Experimental and Numerical Investigation of Fiber Reinforced Laminated Composites Subject to Low-Velocity Impact

NASA Astrophysics Data System (ADS)

Thorsson, Solver I.

Foreign object impact on composite materials continues to be an active field due to its importance in the design of load bearing composite aerostructures. The problem has been studied by many through the decades. Extensive experimental studies have been performed to characterize the impact damage and failure mechanisms. Leaders in aerospace industry are pushing for reliable, robust and efficient computational methods for predicting impact response of composite structures. Experimental and numerical investigations on the impact response of fiber reinforced polymer matrix composite (FRPC) laminates are presented. A detailed face-on and edge-on impact experimental study is presented. A novel method for conducting coupon-level edge-on impact experiments is introduced. The research is focused on impact energy levels that are in the vicinity of the barely visible impact damage (BVID) limit of the material system. A detailed post-impact damage study is presented where non-destructive inspection (NDI) methods such as ultrasound scanning and computed tomography (CT) are used. Detailed fractography studies are presented for further investigation of the through-the-thickness damage due to the impact event. Following the impact study, specimens are subjected to compression after impact (CAI) to establish the effect of BVID on the compressive strength after impact (CSAI). A modified combined loading compression (CLC) test method is proposed for compression testing following an edge-on impact. Experimental work on the rate sensitivity of the mode I and mode II inter-laminar fracture toughness is also investigated. An improved wedge-insert fracture (WIF) method for conducting mode I inter-laminar fracture at elevated loading rates is introduced. Based on the experimental results, a computational modeling approach for capturing face-on impact and CAI is developed. The model is then extended to edge-on impact and CAI. Enhanced Schapery Theory (EST) is utilized for modeling the full field damage and failure present in a unidirectional (UD) lamina within a laminate. Schapery Theory (ST) is a thermodynamically based work potential material model which captures the pre-peak softening due to matrix micro-cracking such as hackling, micro fissures, etc. The Crack Band (CB) method is utilized to capture macroscopic matrix and fiber failure modes such as ply splitting and fiber rupture. Discrete Cohesive Zone Method (DCZM) elements are implemented for capturing inter-laminar delaminations, using discrete nodal traction-separation governed interactions. The model is verified against the impact experimental results and the associated CAI procedures. The model results are in good agreement with experimental findings. The model proved capable of predicting the representative experimental failure modes.