Virtual reality simulators and training in laparoscopic surgery.

PubMed

Yiannakopoulou, Eugenia; Nikiteas, Nikolaos; Perrea, Despina; Tsigris, Christos

2015-01-01

Virtual reality simulators provide basic skills training without supervision in a controlled environment, free of pressure of operating on patients. Skills obtained through virtual reality simulation training can be transferred on the operating room. However, relative evidence is limited with data available only for basic surgical skills and for laparoscopic cholecystectomy. No data exist on the effect of virtual reality simulation on performance on advanced surgical procedures. Evidence suggests that performance on virtual reality simulators reliably distinguishes experienced from novice surgeons Limited available data suggest that independent approach on virtual reality simulation training is not different from proctored approach. The effect of virtual reality simulators training on acquisition of basic surgical skills does not seem to be different from the effect the physical simulators. Limited data exist on the effect of virtual reality simulation training on the acquisition of visual spatial perception and stress coping skills. Undoubtedly, virtual reality simulation training provides an alternative means of improving performance in laparoscopic surgery. However, future research efforts should focus on the effect of virtual reality simulation on performance in the context of advanced surgical procedure, on standardization of training, on the possibility of synergistic effect of virtual reality simulation training combined with mental training, on personalized training. Copyright © 2014 Surgical Associates Ltd. Published by Elsevier Ltd. All rights reserved.

The Relationship between Learning Effectiveness, Teacher Competence and Teachers Performance Madrasah Tsanawiyah at Serang, Banten, Indonesia

ERIC Educational Resources Information Center

Rahmatullah, Mamat

2016-01-01

In this study, the problem is limited factors relating to the learning effectiveness and teacher competence in improving the teacher performance. Therefore, this study will try to get explanations from some main issues which include the learning effectiveness issue, and teacher competence to increase teacher performance in Madrasah Tsanawiyah at…

Effect of hysteretic and non-hysteretic negative capacitance on tunnel FETs DC performance

NASA Astrophysics Data System (ADS)

Saeidi, Ali; Jazaeri, Farzan; Stolichnov, Igor; Luong, Gia V.; Zhao, Qing-Tai; Mantl, Siegfried; Ionescu, Adrian M.

2018-03-01

This work experimentally demonstrates that the negative capacitance effect can be used to significantly improve the key figures of merit of tunnel field effect transistor (FET) switches. In the proposed approach, a matching condition is fulfilled between a trained-polycrystalline PZT capacitor and the tunnel FET (TFET) gate capacitance fabricated on a strained silicon-nanowire technology. We report a non-hysteretic switch configuration by combining a homojunction TFET and a negative capacitance effect booster, suitable for logic applications, for which the on-current is increased by a factor of 100, the transconductance by 2 orders of magnitude, and the low swing region is extended. The operation of a hysteretic negative capacitance TFET, when the matching condition for the negative capacitance is fulfilled only in a limited region of operation, is also reported and discussed. In this late case, a limited improvement in the device performance is observed. Overall, the paper demonstrates the main beneficial effects of negative capacitance on TFETs are the overdrive and transconductance amplification, which exactly address the most limiting performances of current TFETs.

Physics issues in diffraction limited storage ring design

NASA Astrophysics Data System (ADS)

Fan, Wei; Bai, ZhengHe; Gao, WeiWei; Feng, GuangYao; Li, WeiMin; Wang, Lin; He, DuoHui

2012-05-01

Diffraction limited electron storage ring is considered a promising candidate for future light sources, whose main characteristics are higher brilliance, better transverse coherence and better stability. The challenge of diffraction limited storage ring design is how to achieve the ultra low beam emittance with acceptable nonlinear performance. Effective linear and nonlinear parameter optimization methods based on Artificial Intelligence were developed for the storage ring physical design. As an example of application, partial physical design of HALS (Hefei Advanced Light Source), which is a diffraction limited VUV and soft X-ray light source, was introduced. Severe emittance growth due to the Intra Beam Scattering effect, which is the main obstacle to achieve ultra low emittance, was estimated quantitatively and possible cures were discussed. It is inspiring that better performance of diffraction limited storage ring can be achieved in principle with careful parameter optimization.

Physical activity limits the effects of age and Alzheimer's disease on postural control.

PubMed

Debove, Lola; Bru, Noelle; Couderc, Martine; Noé, Frederic; Paillard, Thierry

2017-09-01

The aim was to study the possible influence of physical activity on the postural performance of subjects with Alzheimer's disease (AD). The postural performance (i.e. surface area of the center of foot pressure displacement) of 3 groups was compared: Alzheimer active group (AA), Alzheimer non-active group (ANA) and healthy non-active group (HNA). The AA group's postural performance was superior to that of the ANA and HNA groups. AD disturbed postural performance but participation in regular physical activity made it possible to limit the disturbing effects of AD to a surprising extent, since the postural performance of active AD subjects was also superior to that of healthy subjects. Copyright © 2017 Elsevier Masson SAS. All rights reserved.

Long-Term Effects of Teacher Performance Pay: Experimental Evidence from India

ERIC Educational Resources Information Center

Muralidharan, Karthik

2012-01-01

While the idea of teacher performance-pay is increasingly making its way into policy, the evidence on the effectiveness of such programs is both limited and mixed. The central questions in the literature on teacher performance pay to date have been whether teacher performance pay based on test scores can improve student achievement, and whether…

Increasing Capacity: Practice Effects in Absolute Identification

ERIC Educational Resources Information Center

Dodds, Pennie; Donkin, Christopher; Brown, Scott D.; Heathcote, Andrew

2011-01-01

In most of the long history of the study of absolute identification--since Miller's (1956) seminal article--a severe limit on performance has been observed, and this limit has resisted improvement even by extensive practice. In a startling result, Rouder, Morey, Cowan, and Pfaltz (2004) found substantially improved performance with practice in the…

The effects of temperature and pressure on airborne exposure concentrations when performing compliance evaluations using ACGIH TLVs and OSHA PELs.

PubMed

Stephenson, D J; Lillquist, D R

2001-04-01

Occupational hygienists perform air sampling to characterize airborne contaminant emissions, assess occupational exposures, and establish allowable workplace airborne exposure concentrations. To perform these air sampling applications, occupational hygienists often compare an airborne exposure concentration to a corresponding American Conference of Governmental Industrial Hygienists (ACGIH) threshold limit value (TLV) or an Occupational Safety and Health Administration (OSHA) permissible exposure limit (PEL). To perform such comparisons, one must understand the physiological assumptions used to establish these occupational exposure limits, the relationship between a workplace airborne exposure concentration and its associated TLV or PEL, and the effect of temperature and pressure on the performance of an accurate compliance evaluation. This article illustrates the correct procedure for performing compliance evaluations using airborne exposure concentrations expressed in both parts per million and milligrams per cubic meter. In so doing, a brief discussion is given on the physiological assumptions used to establish TLVs and PELs. It is further shown how an accurate compliance evaluation is fundamentally based on comparison of a measured work site exposure dose (derived from the sampling site exposure concentration estimate) to an estimated acceptable exposure dose (derived from the occupational exposure limit concentration). In addition, this article correctly illustrates the effect that atmospheric temperature and pressure have on airborne exposure concentrations and the eventual performance of a compliance evaluation. This article also reveals that under fairly moderate conditions of temperature and pressure, 30 degrees C and 670 torr, a misunderstanding of how varying atmospheric conditions affect concentration values can lead to a 15 percent error in assessing compliance.

Laser-only Adaptive Optics Achieves Significant Image Quality Gains Compared to Seeing-limited Observations over the Entire Sky

NASA Astrophysics Data System (ADS)

Howard, Ward S.; Law, Nicholas M.; Ziegler, Carl A.; Baranec, Christoph; Riddle, Reed

2018-02-01

Adaptive optics laser guide-star systems perform atmospheric correction of stellar wavefronts in two parts: stellar tip-tilt and high-spatial-order laser correction. The requirement of a sufficiently bright guide star in the field-of-view to correct tip-tilt limits sky coverage. In this paper, we show an improvement to effective seeing without the need for nearby bright stars, enabling full sky coverage by performing only laser-assisted wavefront correction. We used Robo-AO, the first robotic AO system, to comprehensively demonstrate this laser-only correction. We analyze observations from four years of efficient robotic operation covering 15000 targets and 42000 observations, each realizing different seeing conditions. Using an autoguider (or a post-processing software equivalent) and the laser to improve effective seeing independent of the brightness of a target, Robo-AO observations show a 39% ± 19% improvement to effective FWHM, without any tip-tilt correction. We also demonstrate that 50% encircled energy performance without tip-tilt correction remains comparable to diffraction-limited, standard Robo-AO performance. Faint-target science programs primarily limited by 50% encircled energy (e.g., those employing integral field spectrographs placed behind the AO system) may see significant benefits to sky coverage from employing laser-only AO.

Self-efficacy: Implications for Physical Activity, Function, and Functional Limitations in Older Adults.

PubMed

McAuley, Edward; Szabo, Amanda; Gothe, Neha; Olson, Erin A

2011-07-01

Attenuating the physical decline and increases in disability associated with the aging process is an important public health priority. Evidence suggests that regular physical activity participation improves functional performance, such as walking, standing balance, flexibility, and getting up out of a chair, and also plays an important role in the disablement process by providing a protective effect against functional limitations. Whether these effects are direct or indirect has yet to be reliably established. In this review, the authors take the perspective that such relationships are indirect and operate through self-efficacy expectations. They first provide an introduction to social cognitive theory followed by an overview of self-efficacy's reciprocal relationship with physical activity. They then consider the literature that documents the effects of physical activity on functional performance and functional limitations in older adults and the extent to which self-efficacy might mediate these relationships. Furthermore, they also present evidence that suggests that self-efficacy plays a pivotal role in a model in which the protective effects conferred by physical activity on functional limitations operate through functional performance. The article concludes with a brief section making recommendations for the development of strategies within physical activity and rehabilitative programs for maximizing the major sources of efficacy information.

Self-efficacy: Implications for Physical Activity, Function, and Functional Limitations in Older Adults

PubMed Central

McAuley, Edward; Szabo, Amanda; Gothe, Neha; Olson, Erin A.

2013-01-01

Attenuating the physical decline and increases in disability associated with the aging process is an important public health priority. Evidence suggests that regular physical activity participation improves functional performance, such as walking, standing balance, flexibility, and getting up out of a chair, and also plays an important role in the disablement process by providing a protective effect against functional limitations. Whether these effects are direct or indirect has yet to be reliably established. In this review, the authors take the perspective that such relationships are indirect and operate through self-efficacy expectations. They first provide an introduction to social cognitive theory followed by an overview of self-efficacy's reciprocal relationship with physical activity. They then consider the literature that documents the effects of physical activity on functional performance and functional limitations in older adults and the extent to which self-efficacy might mediate these relationships. Furthermore, they also present evidence that suggests that self-efficacy plays a pivotal role in a model in which the protective effects conferred by physical activity on functional limitations operate through functional performance. The article concludes with a brief section making recommendations for the development of strategies within physical activity and rehabilitative programs for maximizing the major sources of efficacy information. PMID:24353482

Long-Term Effects of Habitual Barefoot Running and Walking: A Systematic Review.

PubMed

Hollander, Karsten; Heidt, Christoph; VAN DER Zwaard, Babette C; Braumann, Klaus-Michael; Zech, Astrid

2017-04-01

Barefoot locomotion is widely believed to be beneficial for motor development and biomechanics but are implied to be responsible for foot pathologies and running-related injuries. Although most of available studies focused on acute effects of barefoot running and walking little is known regarding the effects of long-term barefoot versus shod locomotion. The purpose of this study was to systematically review the literature to evaluate current evidence of habitual barefoot (HB) versus habitual shod locomotion on foot anthropometrics, biomechanics, motor performance, and pathologies. Four electronic databases were searched using terms related to habitually barefoot locomotion. Relevant studies were identified based on title, abstract, and full text, and a forward (citation tracking) and backward (references) search was performed. Risk of bias was assessed, data pooling, and meta-analysis (random effects model) performed and finally levels of evidence determined. Fifteen studies with 8399 participants were included. Limited evidence was found for a reduced ankle dorsiflexion at footstrike (pooled effect size, -3.47; 95% confidence interval [CI], -5.18 to -1.76) and a lower pedobarographically measured hallux angle (-1.16; 95% CI, -1.64 to -0.68). HB populations had wider (0.55; 95% CI, 0.06-1.05) but no shorter (-0.22; 95% CI, -0.51 to 0.08) feet compared with habitual shod populations. No differences in relative injury rates were found, with limited evidence for a different body part distribution of musculoskeletal injuries and more foot pathologies and less foot deformities and defects in HB runners. Only limited or very limited evidence is found for long-term effects of HB locomotion regarding biomechanics or health-related outcomes. Moreover, no evidence exists for motor performance. Future research should include prospective study designs.

Bridging developmental boundaries: lifelong dietary patterns modulate life histories in a parthenogenetic insect.

PubMed

Roark, Alison M; Bjorndal, Karen A

2014-01-01

Determining the effects of lifelong intake patterns on performance is challenging for many species, primarily because of methodological constraints. Here, we used a parthenogenetic insect (Carausius morosus) to determine the effects of limited and unlimited food availability across multiple life-history stages. Using a parthenogen allowed us to quantify intake by juvenile and adult females and to evaluate the morphological, physiological, and life-history responses to intake, all without the confounding influences of pair-housing, mating, and male behavior. In our study, growth rate prior to reproductive maturity was positively correlated with both adult and reproductive lifespans but negatively correlated with total lifespan. Food limitation had opposing effects on lifespan depending on when it was imposed, as it protracted development in juveniles but hastened death in adults. Food limitation also constrained reproduction regardless of when food was limited, although decreased fecundity was especially pronounced in individuals that were food-limited as late juveniles and adults. Additional carry-over effects of juvenile food limitation included smaller adult size and decreased body condition at the adult molt, but these effects were largely mitigated in insects that were switched to ad libitum feeding as late juveniles. Our data provide little support for the existence of a trade-off between longevity and fecundity, perhaps because these functions were fueled by different nutrient pools. However, insects that experienced a switch to the limited diet at reproductive maturity seem to have fueled egg production by drawing down body stores, thus providing some evidence for a life-history trade-off. Our results provide important insights into the effects of food limitation and indicate that performance is modulated by intake both within and across life-history stages.

No Evidence for Improved Associative Memory Performance Following Process-Based Associative Memory Training in Older Adults

PubMed Central

Bellander, Martin; Eschen, Anne; Lövdén, Martin; Martin, Mike; Bäckman, Lars; Brehmer, Yvonne

2017-01-01

Studies attempting to improve episodic memory performance with strategy instructions and training have had limited success in older adults: their training gains are limited in comparison to those of younger adults and do not generalize to untrained tasks and contexts. This limited success has been partly attributed to age-related impairments in associative binding of information into coherent episodes. We therefore investigated potential training and transfer effects of process-based associative memory training (i.e., repeated practice). Thirty-nine older adults (Mage = 68.8) underwent 6 weeks of either adaptive associative memory training or item recognition training. Both groups improved performance in item memory, spatial memory (object-context binding) and reasoning. A disproportionate effect of associative memory training was only observed for item memory, whereas no training-related performance changes were observed for associative memory. Self-reported strategies showed no signs of spontaneous development of memory-enhancing associative memory strategies. Hence, the results do not support the hypothesis that process-based associative memory training leads to higher associative memory performance in older adults. PMID:28119597

No Evidence for Improved Associative Memory Performance Following Process-Based Associative Memory Training in Older Adults.

PubMed

Bellander, Martin; Eschen, Anne; Lövdén, Martin; Martin, Mike; Bäckman, Lars; Brehmer, Yvonne

2016-01-01

Studies attempting to improve episodic memory performance with strategy instructions and training have had limited success in older adults: their training gains are limited in comparison to those of younger adults and do not generalize to untrained tasks and contexts. This limited success has been partly attributed to age-related impairments in associative binding of information into coherent episodes. We therefore investigated potential training and transfer effects of process-based associative memory training (i.e., repeated practice). Thirty-nine older adults ( M age = 68.8) underwent 6 weeks of either adaptive associative memory training or item recognition training. Both groups improved performance in item memory, spatial memory (object-context binding) and reasoning. A disproportionate effect of associative memory training was only observed for item memory, whereas no training-related performance changes were observed for associative memory. Self-reported strategies showed no signs of spontaneous development of memory-enhancing associative memory strategies. Hence, the results do not support the hypothesis that process-based associative memory training leads to higher associative memory performance in older adults.

The Effect of Flipped Teaching Combined with Modified Team-Based Learning on Student Performance in Physiology

ERIC Educational Resources Information Center

Gopalan, Chaya; Klann, Megan C.

2017-01-01

Flipped classroom is a hybrid educational format that shifts guided teaching out of class, thus allowing class time for student-centered learning. Although this innovative teaching format is gaining attention, there is limited evidence on the effectiveness of flipped teaching on student performance. We compared student performance and student…

Orbiter fuel cell performance constraints. STS/OPS Pratt Whitney fuel cells. Operating limits for mission planning

NASA Technical Reports Server (NTRS)

Kolkhorst, H. E.

1980-01-01

The orbiter fuel cell powerplant (FCP) performance constraints listed in the Shuttle Operational Data Book (SODB) were analyzed using the shuttle environmental control requirements evaluation tool. The effects of FCP lifetime, coolant loops, and FCP voltage output were considered. Results indicate that the FCP limits defined in the SODB are not valid.

Beliefs about willpower determine the impact of glucose on self-control.

PubMed

Job, Veronika; Walton, Gregory M; Bernecker, Katharina; Dweck, Carol S

2013-09-10

Past research found that the ingestion of glucose can enhance self-control. It has been widely assumed that basic physiological processes underlie this effect. We hypothesized that the effect of glucose also depends on people's theories about willpower. Three experiments, both measuring (experiment 1) and manipulating (experiments 2 and 3) theories about willpower, showed that, following a demanding task, only people who view willpower as limited and easily depleted (a limited resource theory) exhibited improved self-control after sugar consumption. In contrast, people who view willpower as plentiful (a nonlimited resource theory) showed no benefits from glucose--they exhibited high levels of self-control performance with or without sugar boosts. Additionally, creating beliefs about glucose ingestion (experiment 3) did not have the same effect as ingesting glucose for those with a limited resource theory. We suggest that the belief that willpower is limited sensitizes people to cues about their available resources including physiological cues, making them dependent on glucose boosts for high self-control performance.

Beliefs about willpower determine the impact of glucose on self-control

PubMed Central

Job, Veronika; Walton, Gregory M.; Bernecker, Katharina; Dweck, Carol S.

2013-01-01

Past research found that the ingestion of glucose can enhance self-control. It has been widely assumed that basic physiological processes underlie this effect. We hypothesized that the effect of glucose also depends on people’s theories about willpower. Three experiments, both measuring (experiment 1) and manipulating (experiments 2 and 3) theories about willpower, showed that, following a demanding task, only people who view willpower as limited and easily depleted (a limited resource theory) exhibited improved self-control after sugar consumption. In contrast, people who view willpower as plentiful (a nonlimited resource theory) showed no benefits from glucose—they exhibited high levels of self-control performance with or without sugar boosts. Additionally, creating beliefs about glucose ingestion (experiment 3) did not have the same effect as ingesting glucose for those with a limited resource theory. We suggest that the belief that willpower is limited sensitizes people to cues about their available resources including physiological cues, making them dependent on glucose boosts for high self-control performance. PMID:23959900

48 CFR 17.605 - Award, renewal, and extension.

Code of Federal Regulations, 2014 CFR

2014-10-01

... Award, renewal, and extension. (a) Effective work performance under management and operating contracts... requirements and the unusual (sometimes unique) nature of the work performed under management and operating contracts, the Government is often limited in its ability to effect competition or to replace a contractor...

Does stronger pollen competition improve offspring fitness when pollen load does not vary?

PubMed

Pélabon, Christophe; Hennet, Lauriane; Bolstad, Geir H; Albertsen, Elena; Opedal, Øystein H; Ekrem, Runa K; Armbruster, W Scott

2016-03-01

Competition among pollen grains from a single donor is expected to increase the quality of the offspring produced because of the recessive deleterious alleles expressed during pollen-tube growth. However, evidence for such an effect is inconclusive; a large number of studies suffer from confounding variation in pollen competition with variation in pollen load. In this study, we tested the effect of pollen competition on offspring performance independently of pollen-load variation. We compared seed mass and early seedling performance in Dalechampia scandens (Euphorbiaceae) between crosses in which variation in pollen competition was achieved, without variation in pollen load, by manipulating the dispersion of pollen grains on the stigmas. Despite a large sample size (211 crosses on 20 maternal plants), we failed to find an effect of pollen competition on seed characteristics or early seedling performance. Paternal effects were always limited, and pollen competition never reduced the within-father (residual) variance. These results suggest that limited within-donor variation in genetic quality of pollen grains reduces the potential benefits of pollen competition in the study population. The lack of paternal effects on early sporophyte performance further suggests that benefits of pollen competition among pollen from multiple donors should be limited as well, and it raises questions about the significance of pollen competition as a mechanism of sexual selection. © 2016 Botanical Society of America.

Advanced binary geothermal power plants: Limits of performance

NASA Astrophysics Data System (ADS)

Bliem, C. J.; Mines, G. L.

1991-01-01

The Heat Cycle Research Program is investigating potential improvements to power cycles utilizing moderate temperature geothermal resources to produce electrical power. Investigations have specifically examined Rankine cycle binary power systems. Binary Rankine cycles are more efficient than the flash steam cycles at moderate resource temperature, achieving a higher net brine effectiveness. At resource conditions similar to those at the Heber binary plant, it has been shown that mixtures of saturated hydrocarbons (alkanes) or halogenated hydrocarbons operating in a supercritical Rankine cycle gave improved performance over Rankine cycles with the pure working fluids executing single or dual boiling cycles or supercritical cycles. Recently, other types of cycles have been proposed for binary geothermal service. The feasible limits on efficiency of a plant given practical limits on equipment performance is explored and the methods used in these advanced concept plants to achieve the maximum possible efficiency are discussed. (Here feasible is intended to mean reasonably achievable and not cost effective.) No direct economic analysis was made because of the sensitivity of economic results to site specific input. The limit of performance of three advanced plants were considered. The performance predictions were taken from the developers of each concept. The advanced plants considered appear to be approaching the feasible limit of performance. Ultimately, the plant designer must weigh the advantages and disadvantages of the the different cycles to find the best plant for a given service. In addition, a standard is presented of comparison of the work which has been done in the Heat Cycle Research Program and in the industrial sector by Exergy, Inc. and Polythermal Technologies.

Effect of a limited-enforcement intelligent tutoring system in dermatopathology on student errors, goals and solution paths.

PubMed

Payne, Velma L; Medvedeva, Olga; Legowski, Elizabeth; Castine, Melissa; Tseytlin, Eugene; Jukic, Drazen; Crowley, Rebecca S

2009-11-01

Determine effects of a limited-enforcement intelligent tutoring system in dermatopathology on student errors, goals and solution paths. Determine if limited enforcement in a medical tutoring system inhibits students from learning the optimal and most efficient solution path. Describe the type of deviations from the optimal solution path that occur during tutoring, and how these deviations change over time. Determine if the size of the problem-space (domain scope), has an effect on learning gains when using a tutor with limited enforcement. Analyzed data mined from 44 pathology residents using SlideTutor-a Medical Intelligent Tutoring System in Dermatopathology that teaches histopathologic diagnosis and reporting skills based on commonly used diagnostic algorithms. Two subdomains were included in the study representing sub-algorithms of different sizes and complexities. Effects of the tutoring system on student errors, goal states and solution paths were determined. Students gradually increase the frequency of steps that match the tutoring system's expectation of expert performance. Frequency of errors gradually declines in all categories of error significance. Student performance frequently differs from the tutor-defined optimal path. However, as students continue to be tutored, they approach the optimal solution path. Performance in both subdomains was similar for both errors and goal differences. However, the rate at which students progress toward the optimal solution path differs between the two domains. Tutoring in superficial perivascular dermatitis, the larger and more complex domain was associated with a slower rate of approximation towards the optimal solution path. Students benefit from a limited-enforcement tutoring system that leverages diagnostic algorithms but does not prevent alternative strategies. Even with limited enforcement, students converge toward the optimal solution path.

Effects of Heat of Vaporization and Octane Sensitivity on Knock-Limited Spark Ignition Engine Performance

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

Ratcliff, Matthew A; Burton, Jonathan L; Sindler, Petr

Knock-limited loads for a set of surrogate gasolines all having nominal 100 research octane number (RON), approximately 11 octane sensitivity (S), and a heat of vaporization (HOV) range of 390 to 595 kJ/kg at 25 degrees C were investigated. A single-cylinder spark-ignition engine derived from a General Motors Ecotec direct injection (DI) engine was used to perform load sweeps at a fixed intake air temperature (IAT) of 50 degrees C, as well as knock-limited load measurements across a range of IATs up to 90 degrees C. Both DI and pre-vaporized fuel (supplied by a fuel injector mounted far upstream ofmore » the intake valves and heated intake runner walls) experiments were performed to separate the chemical and thermal effects of the fuels' knock resistance. The DI load sweeps at 50 degrees C intake air temperature showed no effect of HOV on the knock-limited performance. The data suggest that HOV acts as a thermal contributor to S under the conditions studied. Measurement of knock-limited loads from the IAT sweeps for DI at late combustion phasing showed that a 40 vol% ethanol (E40) blend provided additional knock resistance at the highest temperatures, compared to a 20 vol% ethanol blend and hydrocarbon fuel with similar RON and S. Using the pre-vaporized fuel system, all the high S fuels produced nearly identical knock-limited loads at each temperature across the range of IATs studied. For these fuels RON ranged from 99.2 to 101.1 and S ranged from 9.4 to 12.2, with E40 having the lowest RON and highest S. The higher knock-limited loads for E40 at the highest IATs examined were consistent with the slightly higher S for this fuel, and the lower engine operating condition K values arising from use of this fuel. The study highlights how fuel HOV can affect the temperature at intake valve closing, and consequently the pressure-temperature history of the end gas leading to more negative values of K, thereby enhancing the effect of S on knock resistance.« less

Effect of local cooling on short-term, intense exercise.

PubMed

Kwon, Young S; Robergs, Robert A; Schneider, Suzanne M

2013-07-01

The widespread belief that local cooling impairs short-term, strenuous exercise performance is controversial. Eighteen original investigations involving cooling before and intermittent cooling during short-term, intensive exercise are summarized in this review. Previous literature examining short-term intensive exercise and local cooling primarily has been limited to the effects on muscle performance immediately or within minutes following cold application. Most previous cooling studies used equal and longer than 10 minutes of pre-cooling, and found that cooling reduced strength, performance and endurance. Because short duration, high intensity exercise requires adequate warm-up to prepare for optimal performance, prolonged pre-cooling is not an effective method to prepare for this type of exercise. The literature related to the effect of acute local cooling immediately before short duration, high intensity isotonic exercise such as weight lifting is limited. However, local intermittent cooling during short-term, high intense exercise may provide possible beneficial effects; first, by pain reduction, caused by an "irritation effect" from hand thermal receptors which block pain sensation, or second, by a cooling effect, whereby stimulation of hand thermal receptors or a slight lowering of blood temperature might alter central fatigue.

40 CFR 197.36 - Are there limits on what DOE must consider in the performance assessments?

Code of Federal Regulations, 2013 CFR

2013-07-01

... effects of climate change. The climate change analysis may be limited to the effects of increased water flow through the repository as a result of climate change, and the resulting transport and release of radionuclides to the accessible environment. The nature and degree of climate change may be represented by...

40 CFR 197.36 - Are there limits on what DOE must consider in the performance assessments?

Code of Federal Regulations, 2014 CFR

2014-07-01

... effects of climate change. The climate change analysis may be limited to the effects of increased water flow through the repository as a result of climate change, and the resulting transport and release of radionuclides to the accessible environment. The nature and degree of climate change may be represented by...

40 CFR 197.36 - Are there limits on what DOE must consider in the performance assessments?

Code of Federal Regulations, 2012 CFR

2012-07-01

... effects of climate change. The climate change analysis may be limited to the effects of increased water flow through the repository as a result of climate change, and the resulting transport and release of radionuclides to the accessible environment. The nature and degree of climate change may be represented by...

40 CFR 197.36 - Are there limits on what DOE must consider in the performance assessments?

Code of Federal Regulations, 2011 CFR

2011-07-01

... effects of climate change. The climate change analysis may be limited to the effects of increased water flow through the repository as a result of climate change, and the resulting transport and release of radionuclides to the accessible environment. The nature and degree of climate change may be represented by...

40 CFR 197.36 - Are there limits on what DOE must consider in the performance assessments?

Code of Federal Regulations, 2010 CFR

2010-07-01

... effects of climate change. The climate change analysis may be limited to the effects of increased water flow through the repository as a result of climate change, and the resulting transport and release of radionuclides to the accessible environment. The nature and degree of climate change may be represented by...

The fundamental downscaling limit of field effect transistors

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

Mamaluy, Denis, E-mail: mamaluy@sandia.gov; Gao, Xujiao

2015-05-11

We predict that within next 15 years a fundamental down-scaling limit for CMOS technology and other Field-Effect Transistors (FETs) will be reached. Specifically, we show that at room temperatures all FETs, irrespective of their channel material, will start experiencing unacceptable level of thermally induced errors around 5-nm gate lengths. These findings were confirmed by performing quantum mechanical transport simulations for a variety of 6-, 5-, and 4-nm gate length Si devices, optimized to satisfy high-performance logic specifications by ITRS. Different channel materials and wafer/channel orientations have also been studied; it is found that altering channel-source-drain materials achieves only insignificant increasemore » in switching energy, which overall cannot sufficiently delay the approaching downscaling limit. Alternative possibilities are discussed to continue the increase of logic element densities for room temperature operation below the said limit.« less

The fundamental downscaling limit of field effect transistors

DOE PAGES

Mamaluy, Denis; Gao, Xujiao

2015-05-12

We predict that within next 15 years a fundamental down-scaling limit for CMOS technology and other Field-Effect Transistors (FETs) will be reached. Specifically, we show that at room temperatures all FETs, irrespective of their channel material, will start experiencing unacceptable level of thermally induced errors around 5-nm gate lengths. These findings were confirmed by performing quantum mechanical transport simulations for a variety of 6-, 5-, and 4-nm gate length Si devices, optimized to satisfy high-performance logic specifications by ITRS. Different channel materials and wafer/channel orientations have also been studied; it is found that altering channel-source-drain materials achieves only insignificant increasemore » in switching energy, which overall cannot sufficiently delay the approaching downscaling limit. Alternative possibilities are discussed to continue the increase of logic element densities for room temperature operation below the said limit.« less

Removing the current-limit of vertical organic field effect transistors

NASA Astrophysics Data System (ADS)

Sheleg, Gil; Greenman, Michael; Lussem, Bjorn; Tessler, Nir

2017-11-01

The reported Vertical Organic Field Effect Transistors (VOFETs) show either superior current and switching speeds or well-behaved transistor performance, especially saturation in the output characteristics. Through the study of the relationship between the device architecture or dimensions and the device performance, we find that achieving a saturation regime in the output characteristics requires that the device operates in the injection limited regime. In current structures, the existence of the injection limited regime depends on the source's injection barrier as well as on the buried semiconductor layer thickness. To overcome the injection limit imposed by the necessity of injection barrier, we suggest a new architecture to realize VOFETs. This architecture shows better gate control and is independent of the injection barrier at the source, thus allowing for several A cm-2 for a semiconductor having a mobility value of 0.1 cm2 V-1 s-1.

The Effects of Different Lengths of Pretask Planning Time on L2 Learners' Oral Test Performance

ERIC Educational Resources Information Center

Li, Lanlan; Chen, Jiliang; Sun, Lan

2015-01-01

The effect of planning on second language (L2) learners' oral performance is a hotly debated topic in the field of second language acquisition. However, studies on the effect of different amounts of planning time have been quite limited, especially in a testing context. The present study investigated the effects of different lengths of…

The Effects of Extended Time on Writing Performance

ERIC Educational Resources Information Center

Goegan, Lauren D.; Harrison, Gina L.

2017-01-01

The effects of extended time on the writing performance of university students with learning disabilities (LD) was examined. Thirty-eight students (19 LD; 19 non-LD) completed a collection of cognitive, linguistic, and literacy measures, and wrote essays under regular and extended time conditions. Limited evidence was found to support the…

Effects of Testosterone Therapy on Muscle Performance and Physical Function in Older Men with Mobility Limitations (The TOM Trial): Design and Methods

PubMed Central

LeBrasseur, Nathan K.; Lajevardi, Newsha; Miciek, Renee; Mazer, Norman; Storer, Thomas W.; Bhasin, Shalender

2010-01-01

The TOM study is the first, single-site, placebo-controlled, randomized clinical trial designed to comprehensively determine the effects of testosterone administration on muscle strength and physical function in older men with mobility limitations. A total of 252 community dwelling individuals aged 65 and older with low testosterone levels and self-reported limitations in mobility and short physical performance battery (SPPB) score between 4 and 9 will be randomized to receive either placebo or testosterone therapy for 6 months. The primary objective is to determine whether testosterone therapy improves maximal voluntary muscle strength as quantified by the one repetition maximum. Secondary outcomes will include measures of physical function (walking, stair climbing and a lifting and lowering task), habitual physical activity and self-reported disability. The effects of testosterone on affect, fatigue and sense of well being will also be assessed. Unique aspects of the TOM Trial include selection of men with self-reported as well as objectively demonstrable functional limitations, community-based screening and recruitment, adjustment of testosterone dose to ensure serum testosterone levels in the target range while maintaining blinding, and inclusion of a range of self-reported and performance-based physical function measures as outcomes. Clinicaltrials.gov identifier: NCT00240981. PMID:18996225

Effects of testosterone therapy on muscle performance and physical function in older men with mobility limitations (The TOM Trial): design and methods.

PubMed

LeBrasseur, Nathan K; Lajevardi, Newsha; Miciek, Renee; Mazer, Norman; Storer, Thomas W; Bhasin, Shalender

2009-03-01

The TOM study is the first, single-site, placebo-controlled, randomized clinical trial designed to comprehensively determine the effects of testosterone administration on muscle strength and physical function in older men with mobility limitations. A total of 252 community dwelling individuals aged 65 and older with low testosterone levels and self-reported limitations in mobility and short physical performance battery (SPPB) scores between 4 and 9 will be randomized to receive either placebo or testosterone therapy for 6 months. The primary objective is to determine whether testosterone therapy improves maximal voluntary muscle strength as quantified by the one repetition maximum. Secondary outcomes will include measures of physical function (walking, stair climbing and a lifting and lowering task), habitual physical activity and self-reported disability. The effects of testosterone on affect, fatigue and sense of well being will also be assessed. Unique aspects of the TOM Trial include selection of men with self-reported as well as objectively demonstrable functional limitations, community-based screening and recruitment, adjustment of testosterone dose to ensure serum testosterone levels in the target range while maintaining blinding, and inclusion of a range of self-reported and performance-based physical function measures as outcomes. Clinicaltrials.gov identifier: NCT00240981.

Above- and belowground competition from longleaf pine plantations limits performance of reintroduced herbaceous species

Treesearch

Timothy B. Harrington; Christa M. Dagley; M. Boyd Edwards

2002-01-01

Although overstory trees limit the abundance and species richness of herbaceous vegetation in longleaf pine (Pinus palustris Mill.) plantations, the responsible mechanisms are poorly understood because of confounding among limiting factors. In fall 1998, research was initiated to determine the separate effects of above- and belowground competition...

Elucidating the Performance Limitations of Lithium-ion Batteries due to Species and Charge Transport through Five Characteristic Parameters

PubMed Central

Jiang, Fangming; Peng, Peng

2016-01-01

Underutilization due to performance limitations imposed by species and charge transports is one of the key issues that persist with various lithium-ion batteries. To elucidate the relevant mechanisms, two groups of characteristic parameters were proposed. The first group contains three characteristic time parameters, namely: (1) te, which characterizes the Li-ion transport rate in the electrolyte phase, (2) ts, characterizing the lithium diffusion rate in the solid active materials, and (3) tc, describing the local Li-ion depletion rate in electrolyte phase at the electrolyte/electrode interface due to electrochemical reactions. The second group contains two electric resistance parameters: Re and Rs, which represent respectively, the equivalent ionic transport resistance and the effective electronic transport resistance in the electrode. Electrochemical modeling and simulations to the discharge process of LiCoO2 cells reveal that: (1) if te, ts and tc are on the same order of magnitude, the species transports may not cause any performance limitations to the battery; (2) the underlying mechanisms of performance limitations due to thick electrode, high-rate operation, and large-sized active material particles as well as effects of charge transports are revealed. The findings may be used as quantitative guidelines in the development and design of more advanced Li-ion batteries. PMID:27599870

Time-resolved analysis of nonlinear optical limiting for laser synthesized carbon nanoparticles

NASA Astrophysics Data System (ADS)

Chen, G. X.; Hong, M. H.

2010-11-01

Nonlinear optical limiting materials have attracted much research interest in recent years. Carbon nanoparticles suspended in liquids show a strong nonlinear optical limiting function. It is important to investigate the nonlinear optical limiting process of carbon nanoparticles for further improving their nonlinear optical limiting performance. In this study, carbon nanoparticles were prepared by laser ablation of a carbon target in tetrahydrofuran (THF). Optical limiting properties of the samples were studied with 532-nm laser light, which is in the most sensitive wavelength band for human eyes. The shape of the laser pulse plays an important role for initializing the nonlinear optical limiting effect. Time-resolved analysis of laser pulses discovered 3 fluence stages of optical limiting. Theoretical simulation indicates that the optical limiting is initialized by a near-field optical enhancement effect.

Strain-induced extinction of hydrogen-air counterflow diffusion flames - Effects of steam, CO2, N2, and O2 additives to air

NASA Technical Reports Server (NTRS)

Pellett, G. L.; Northam, G. B.; Wilson, L. G.

1992-01-01

A fundamental study was performed using axisymmetric nozzle and tubular opposed jet burners to measure the effects of laminar plug flow and parabolic input velocity profiles on the extinction limits of H2-air counterflow diffusion flames. Extinction limits were quantified by 'flame strength', (average axial air jet velocity) at blowoff of the central flame. The effects of key air contaminants, on the extinction limits, are characterized and analyzed relative to utilization of combustion contaminated vitiated air in high enthalpy supersonic test facilities.

Pre-cooling for endurance exercise performance in the heat: a systematic review

PubMed Central

2012-01-01

Background Endurance exercise capacity diminishes under hot environmental conditions. Time to exhaustion can be increased by lowering body temperature prior to exercise (pre-cooling). This systematic literature review synthesizes the current findings of the effects of pre-cooling on endurance exercise performance, providing guidance for clinical practice and further research. Methods The MEDLINE, EMBASE, CINAHL, Web of Science and SPORTDiscus databases were searched in May 2012 for studies evaluating the effectiveness of pre-cooling to enhance endurance exercise performance in hot environmental conditions (≥ 28°C). Studies involving participants with increased susceptibility to heat strain, cooling during or between bouts of exercise, and protocols where aerobic endurance was not the principle performance outcome were excluded. Potential publications were assessed by two independent reviewers for inclusion and quality. Means and standard deviations of exercise performance variables were extracted or sought from original authors to enable effect size calculations. Results In all, 13 studies were identified. The majority of studies contained low participant numbers and/or absence of sample size calculations. Six studies used cold water immersion, four crushed ice ingestion and three cooling garments. The remaining study utilized mixed methods. Large heterogeneity in methodological design and exercise protocols was identified. Effect size calculations indicated moderate evidence that cold water immersion effectively improved endurance performance, and limited evidence that ice slurry ingestion improved performance. Cooling garments were ineffective. Most studies failed to document or report adverse events. Low participant numbers in each study limited the statistical power of certain reported trends and lack of blinding could potentially have introduced either participant or researcher bias in some studies. Conclusions Current evidence indicates cold water immersion may be the most effective method of pre-cooling to improve endurance performance in hot conditions, although practicality must be considered. Ice slurry ingestion appears to be the most promising practical alternative. Interestingly, cooling garments appear of limited efficacy, despite their frequent use. Mechanisms behind effective pre-cooling remain uncertain, and optimal protocols have yet to be established. Future research should focus on standardizing exercise performance protocols, recruiting larger participant numbers to enable direct comparisons of effectiveness and practicality for each method, and ensuring potential adverse events are evaluated. PMID:23249542

A Dynamic Model of Sustainment Investment

DTIC Science & Technology

2015-02-01

Sustainment System Dynamics Model 11 Figure 7: Core Structure of Sustainment Work 12 Figure 8: Bandwagon Effect Loop 13 Figure 9: Limits to Growth Loop 14...Dynamics Model sustainment capacity sustainment performance gap Bandwagon Effect R1 Limits to Growth B1 S Work Smarter B3 Work Bigger B2 desired...which is of concern primarily when using the model as a vehicle for research. Figure 8 depicts a reinforcing loop called the “ Bandwagon Effect

Interactions between nutrition and gastrointestinal parasitism in sheep.

PubMed

Sykes, A R; Coop, R L

2001-12-01

Effects of gastrointestinal nematode infection on metabolism and nutrient utilisation in sheep are reviewed. Infection induces protein deficiency by increasing the demand for amino acids in the alimentary tract while reducing supply through depression of appetite. Mechanisms through which improved protein nutrition could improve the performance of the host are then discussed. Opportunities for capitalising on such effects are limited by our rudimentary understanding of the cell-mediated immune response in gastrointestinal epithelial tissue. Both resistance of the animal to larval establishment and performance in the face of larval challenge can be enhanced by improved protein nutrition. However, enhanced immune responses may not necessarily be synonymous with improved productivity except at luxurious levels of protein intake, because of apparently competing demands for protein. Such levels of protein nutrition are difficult to achieve in pasture-based systems, because of the protein limiting role of the rumen. Work with proteinprotecting tannins to overcome this limitation is discussed. The much more limited evidence for effect of mineral nutrition, particularly copper (Cu), molybdenum (Mo), cobalt (Co) and phosphorus (P), on outcome of larval challenge is also reviewed.

Thermocapillary phenomena and performance limitations of a wickless heat pipe in microgravity.

PubMed

Kundan, Akshay; Plawsky, Joel L; Wayner, Peter C; Chao, David F; Sicker, Ronald J; Motil, Brian J; Lorik, Tibor; Chestney, Louis; Eustace, John; Zoldak, John

2015-04-10

A counterintuitive, thermocapillary-induced limit to heat- pipe performance was observed that is not predicted by current thermal-fluid models. Heat pipes operate under a number of physical constraints including the capillary, boiling, sonic, and entrainment limits that fundamentally affect their performance. Temperature gradients near the heated end may be high enough to generate significant Marangoni forces that oppose the return flow of liquid from the cold end. These forces are believed to exacerbate dry out conditions and force the capillary limit to be reached prematurely. Using a combination of image and thermal data from experiments conducted on the International Space Station with a transparent heat pipe, we show that in the presence of significant Marangoni forces, dry out is not the initial mechanism limiting performance, but that the physical cause is exactly the opposite behavior: flooding of the hot end with liquid. The observed effect is a consequence of the competition between capillary and Marangoni-induced forces. The temperature signature of flooding is virtually identical to dry out, making diagnosis difficult without direct visual observation of the vapor-liquid interface.

The Effects of Job Sharing on Student Performance Literature Review.

ERIC Educational Resources Information Center

Garman, Dorothy

The River Forest (Illinois) District 90 wished to examine the educational literature on the effects of job sharing by teachers on student performance. This document presents a review of the literature and summarizes and synthesizes this information. Only limited information was found on this subject. However, anecdotal reports of the impact of job…

Effects of Year-Round Schooling on Disadvantaged Students and the Distribution of Standardized Test Performance

ERIC Educational Resources Information Center

Graves, Jennifer

2011-01-01

Using detailed longitudinal data for the state of California, this paper estimates the effect of year-round school calendars on nationally standardized test performance of traditionally disadvantaged students. The student subgroups studied in this paper are: low socioeconomic status, limited English proficiency, Hispanic and Latino, and African…

Aerobic scope fails to explain the detrimental effects on growth resulting from warming and elevated CO2 in Atlantic halibut.

PubMed

Gräns, Albin; Jutfelt, Fredrik; Sandblom, Erik; Jönsson, Elisabeth; Wiklander, Kerstin; Seth, Henrik; Olsson, Catharina; Dupont, Sam; Ortega-Martinez, Olga; Einarsdottir, Ingibjörg; Björnsson, Björn Thrandur; Sundell, Kristina; Axelsson, Michael

2014-03-01

As a consequence of increasing atmospheric CO2, the world's oceans are becoming warmer and more acidic. Whilst the ecological effects of these changes are poorly understood, it has been suggested that fish performance including growth will be reduced mainly as a result of limitations in oxygen transport capacity. Contrary to the predictions given by the oxygen- and capacity-limited thermal tolerance hypothesis, we show that aerobic scope and cardiac performance of Atlantic halibut (Hippoglossus hippoglossus) increase following 14-16 weeks exposure to elevated temperatures and even more so in combination with CO2-acidified seawater. However, the increase does not translate into improved growth, demonstrating that oxygen uptake is not the limiting factor for growth performance at high temperatures. Instead, long-term exposure to CO2-acidified seawater reduces growth at temperatures that are frequently encountered by this species in nature, indicating that elevated atmospheric CO2 levels may have serious implications on fish populations in the future.

Transition phase clothing strategies and their effect on body temperature and 100-m swimming performance.

PubMed

Galbraith, Andy; Willmott, Aimee

2018-03-01

Effective warm-ups are attributed to several temperature-related mechanisms. Strategies during the transition phase, preceding swimming competition, have been shown to prolong temperature-related warm-up effects. The purpose of this study was to evaluate the effects of two different clothing strategies during the transition phase, on subsequent 100-m maximal swimming performance. Nine competitive swimmers (3 female, 21 ± 3 yrs; 6 male 20 ± 2 yrs, mean performance standard 702 FINA Points, mean 100-m seasons best time 61.54 s) completed their own 30-min individual pool warm-up, followed by 7-min changing time and a 30-min transition phase, straight into a 100-m maximal effort time-trial. During the transition phase, swimmers remained seated, either wearing warm or limited clothing. Swimmers returned 1 week later, where clothing conditions were alternated. Post-transition phase skin and core temperature remained higher in the warm clothing condition compared to the limited clothing condition (Mean Core: 36.90 ± 0.17°C, 36.61 ± 0.15°C, P < .01; Mean Skin: 33.49 ± 0.59°C, 31.94 ± 0.59°C, P < .01). One hundred-metre finish times were 0.6% faster in the warm clothing condition compared to the limited clothing condition (62.63 ± 7.69 s, 63.00 ± 7.75 s, P < .01). Wearing warm clothing during a 30-min transition phase improved swimming performance by 0.6%, compared to limited clothing.

Energy Drink Consumption: Beneficial and Adverse Health Effects.

PubMed

Alsunni, Ahmed Abdulrahman

2015-10-01

Consumption of energy drinks has been increasing dramatically in the last two decades, particularly amongst adolescents and young adults. Energy drinks are aggressively marketed with the claim that these products give an energy boost to improve physical and cognitive performance. However, studies supporting these claims are limited. In fact, several adverse health effects have been related to energy drink; this has raised the question of whether these beverages are safe. This review was carried out to identify and discuss the published articles that examined the beneficial and adverse health effects related to energy drink. It is concluded that although energy drink may have beneficial effects on physical performance, these products also have possible detrimental health consequences. Marketing of energy drinks should be limited or forbidden until independent research confirms their safety, particularly among adolescents.

Supplementing biomechanical modeling with EMG analysis

NASA Technical Reports Server (NTRS)

Lewandowski, Beth; Jagodnik, Kathleen; Crentsil, Lawton; Humphreys, Bradley; Funk, Justin; Gallo, Christopher; Thompson, William; DeWitt, John; Perusek, Gail

2016-01-01

It is well established that astronauts experience musculoskeletal deconditioning when exposed to microgravity environments for long periods of time. Spaceflight exercise is used to counteract these effects, and the Advanced Resistive Exercise Device (ARED) on the International Space Station (ISS) has been effective in minimizing musculoskeletal losses. However, the exercise devices of the new exploration vehicles will have requirements of limited mass, power and volume. Because of these limitations, there is a concern that the exercise devices will not be as effective as ARED in maintaining astronaut performance. Therefore, biomechanical modeling is being performed to provide insight on whether the small Multi-Purpose Crew Vehicle (MPCV) device, which utilizes a single-strap design, will provide sufficient physiological loading to maintain musculoskeletal performance. Electromyography (EMG) data are used to supplement the biomechanical model results and to explore differences in muscle activation patterns during exercises using different loading configurations.

Clinically Normal Stereopsis Does Not Ensure a Performance Benefit from Stereoscopic 3D Depth Cues

NASA Astrophysics Data System (ADS)

McIntire, John P.; Havig, Paul R.; Harrington, Lawrence K.; Wright, Steve T.; Watamaniuk, Scott N. J.; Heft, Eric L.

2014-09-01

To investigate the effect of manipulating disparity on task performance and viewing comfort, twelve participants were tested on a virtual object precision placement task while viewing a stereoscopic 3D (S3D) display. All participants had normal or corrected-to-normal visual acuity, passed the Titmus stereovision clinical test, and demonstrated normal binocular function, including phorias and binocular fusion ranges. Each participant completed six experimental sessions with different maximum binocular disparity limits. The results for ten of the twelve participants were generally as expected, demonstrating a large performance advantage when S3D cues were provided. The sessions with the larger disparity limits typically resulted in the best performance, and the sessions with no S3D cues the poorest performance. However, one participant demonstrated poorer performance in sessions with smaller disparity limits but improved performance in sessions with the larger disparity limits. Another participant's performance declined whenever any S3D cues were provided. Follow-up testing suggested that the phenomenon of pseudo-stereoanomaly may account for one viewer's atypical performance, while the phenomenon of stereoanomaly might account for the other. Overall, the results demonstrate that a subset of viewers with clinically normal binocular and stereoscopic vision may have difficulty performing depth-related tasks on S3D displays. The possibility of the vergence-accommodation conflict contributing to individual performance differences is also discussed.

More oxygen during development enhanced flight performance but not thermal tolerance of Drosophila melanogaster.

PubMed

Shiehzadegan, Shayan; Le Vinh Thuy, Jacqueline; Szabla, Natalia; Angilletta, Michael J; VandenBrooks, John M

2017-01-01

High temperatures can stress animals by raising the oxygen demand above the oxygen supply. Consequently, animals under hypoxia could be more sensitive to heating than those exposed to normoxia. Although support for this model has been limited to aquatic animals, oxygen supply might limit the heat tolerance of terrestrial animals during energetically demanding activities. We evaluated this model by studying the flight performance and heat tolerance of flies (Drosophila melanogaster) acclimated and tested at different concentrations of oxygen (12%, 21%, and 31%). We expected that flies raised at hypoxia would develop into adults that were more likely to fly under hypoxia than would flies raised at normoxia or hyperoxia. We also expected flies to benefit from greater oxygen supply during testing. These effects should have been most pronounced at high temperatures, which impair locomotor performance. Contrary to our expectations, we found little evidence that flies raised at hypoxia flew better when tested at hypoxia or tolerated extreme heat better than did flies raised at normoxia or hyperoxia. Instead, flies raised at higher oxygen levels performed better at all body temperatures and oxygen concentrations. Moreover, oxygen supply during testing had the greatest effect on flight performance at low temperature, rather than high temperature. Our results poorly support the hypothesis that oxygen supply limits performance at high temperatures, but do support the idea that hyperoxia during development improves performance of flies later in life.

Advanced analytical modeling of double-gate Tunnel-FETs - A performance evaluation

NASA Astrophysics Data System (ADS)

Graef, Michael; Hosenfeld, Fabian; Horst, Fabian; Farokhnejad, Atieh; Hain, Franziska; Iñíguez, Benjamín; Kloes, Alexander

2018-03-01

The Tunnel-FET is one of the most promising devices to be the successor of the standard MOSFET due to its alternative current transport mechanism, which allows a smaller subthreshold slope than the physically limited 60 mV/dec of the MOSFET. Recently fabricated devices show smaller slopes already but mostly not over multiple decades of the current transfer characteristics. In this paper the performance limiting effects, occurring during the fabrication process of the device, such as doping profiles and midgap traps are analyzed by physics-based analytical models and their performance limiting abilities are determined. Additionally, performance enhancing possibilities, such as hetero-structures and ambipolarity improvements are introduced and discussed. An extensive double-gate n-Tunnel-FET model is presented, which meets the versatile device requirements and shows a good fit with TCAD simulations and measurement data.

Study of Synthetic Vision Systems (SVS) and Velocity-vector Based Command Augmentation System (V-CAS) on Pilot Performance

NASA Technical Reports Server (NTRS)

Liu, Dahai; Goodrich, Ken; Peak, Bob

2006-01-01

This study investigated the effects of synthetic vision system (SVS) concepts and advanced flight controls on single pilot performance (SPP). Specifically, we evaluated the benefits and interactions of two levels of terrain portrayal, guidance symbology, and control-system response type on SPP in the context of lower-landing minima (LLM) approaches. Performance measures consisted of flight technical error (FTE) and pilot perceived workload. In this study, pilot rating, control type, and guidance symbology were not found to significantly affect FTE or workload. It is likely that transfer from prior experience, limited scope of the evaluation task, specific implementation limitations, and limited sample size were major factors in obtaining these results.

Athlete Characteristics and Team Competitive Performance as Moderators for the Relationship Between Coach Transformational Leadership and Athlete Performance.

PubMed

Bormann, Kai C; Schulte-Coerne, Paul; Diebig, Mathias; Rowold, Jens

2016-06-01

The goal of this study is to examine the effects of coaches' transformational leadership on player performance. To advance existing research, we examine (a) effects on individual and team performance and (b) consider joint moderating effects of players' win orientation and teams' competitive performance on the leadership- individual performance link. In a three-source sample from German handball teams, we collected data on 336 players and 30 coaches and teams. Results showed positive main effects of transformational leadership's facet of articulating a vision (AV) on team and individual performance and negative main effects of providing an appropriate model (PAM) on team performance. With regard to moderating effects, AV increased and PAM decreased individual performance when both moderators were low, and intellectual stimulation had a positive effect when both were high. This study expands insights into the potential and limitation of transformational leadership with a strong focus on the role of situational contingencies.

Measuring human performance on NASA's microgravity aircraft

NASA Technical Reports Server (NTRS)

Morris, Randy B.; Whitmore, Mihriban

1993-01-01

Measuring human performance in a microgravity environment will aid in identifying the design requirements, human capabilities, safety, and productivity of future astronauts. The preliminary understanding of the microgravity effects on human performance can be achieved through evaluations conducted onboard NASA's KC-135 aircraft. These evaluations can be performed in relation to hardware performance, human-hardware interface, and hardware integration. Measuring human performance in the KC-135 simulated environment will contribute to the efforts of optimizing the human-machine interfaces for future and existing space vehicles. However, there are limitations, such as limited number of qualified subjects, unexpected hardware problems, and miscellaneous plane movements which must be taken into consideration. Examples for these evaluations, the results, and their implications are discussed in the paper.

Effect of In-Vehicle Audio Warning System on Driver’s Speed Control Performance in Transition Zones from Rural Areas to Urban Areas

PubMed Central

Yan, Xuedong; Wang, Jiali; Wu, Jiawei

2016-01-01

Speeding is a major contributing factor to traffic crashes and frequently happens in areas where there is a mutation in speed limits, such as the transition zones that connect urban areas from rural areas. The purpose of this study is to investigate the effects of an in-vehicle audio warning system and lit speed limit sign on preventing drivers’ speeding behavior in transition zones. A high-fidelity driving simulator was used to establish a roadway network with the transition zone. A total of 41 participants were recruited for this experiment, and the driving speed performance data were collected from the simulator. The experimental results display that the implementation of the audio warning system could significantly reduce drivers’ operating speed before they entered the urban area, while the lit speed limit sign had a minimal effect on improving the drivers’ speed control performance. Without consideration of different types of speed limit signs, it is found that male drivers generally had a higher operating speed both upstream and in the transition zones and have a larger maximum deceleration for speed reduction than female drivers. Moreover, the drivers who had medium-level driving experience had the higher operating speed and were more likely to have speeding behaviors in the transition zones than those who had low-level and high-level driving experience in the transition zones. PMID:27347990

Modeling road-cycling performance.

PubMed

Olds, T S; Norton, K I; Lowe, E L; Olive, S; Reay, F; Ly, S

1995-04-01

This paper presents a complete set of equations for a "first principles" mathematical model of road-cycling performance, including corrections for the effect of winds, tire pressure and wheel radius, altitude, relative humidity, rotational kinetic energy, drafting, and changed drag. The relevant physiological, biophysical, and environmental variables were measured in 41 experienced cyclists completing a 26-km road time trial. The correlation between actual and predicted times was 0.89 (P < or = 0.0001), with a mean difference of 0.74 min (1.73% of mean performance time) and a mean absolute difference of 1.65 min (3.87%). Multiple simulations were performed where model inputs were randomly varied using a normal distribution about the measured values with a SD equivalent to the estimated day-to-day variability or technical error of measurement in each of the inputs. This analysis yielded 95% confidence limits for the predicted times. The model suggests that the main physiological factors contributing to road-cycling performance are maximal O2 consumption, fractional utilization of maximal O2 consumption, mechanical efficiency, and projected frontal area. The model is then applied to some practical problems in road cycling: the effect of drafting, the advantage of using smaller front wheels, the effects of added mass, the importance of rotational kinetic energy, the effect of changes in drag due to changes in bicycle configuration, the normalization of performances under different conditions, and the limits of human performance.

Use of the Occupational Therapy Task-Oriented Approach to optimize the motor performance of a client with cognitive limitations.

PubMed

Preissner, Katharine

2010-01-01

This case report describes the use of the Occupational Therapy Task-Oriented Approach with a client with occupational performance limitations after a cerebral vascular accident. The Occupational Therapy Task-Oriented Approach is often suggested as a preferred neurorehabilitation intervention to improve occupational performance by optimizing motor behavior. One common critique of this approach, however, is that it may seem inappropriate or have limited application for clients with cognitive deficits. This case report demonstrates how an occupational therapist working in an inpatient rehabilitation setting used the occupational therapy task-oriented evaluation framework and treatment principles described by Mathiowetz (2004) with a person with significant cognitive limitations. This approach was effective in assisting the client in meeting her long-term goals, maximizing her participation in meaningful occupations, and successfully transitioning to home with her daughter.

Reading in Examination-Type Situations: The Effects of Text Layout on Performance

ERIC Educational Resources Information Center

Lonsdale, Maria dos Santos; Dyson, Mary C.; Reynolds, Linda

2006-01-01

Examinations are conventionally used to measure candidates' achievement in a limited time period. However, the influence of text layout on performance may compromise the construct validity of the examination. An experimental study looked at the effects of the text layout on the speed and accuracy of a reading task in an examination-type situation.…

Effects of color temperatures (Kelvin) of LED bulbs on growth performance, carcass characteristics, and ocular welfare indices of broilers grown to heavy weights

USDA-ARS?s Scientific Manuscript database

Limited data are available for comparing light-emitting diode (LED) bulbs that are currently available in commercial broiler production facilities. We evaluated the effects of color temperatures (Kelvin) of LED bulbs on growth performance, carcass characteristics, and ocular welfare indices of broil...

The reliability and validity of the Caregiver Work Limitations Questionnaire.

PubMed

Lerner, Debra; Parsons, Susan K; Chang, Hong; Visco, Zachary L; Pawlecki, J Brent

2015-01-01

To test a new Caregiver Work Limitations Questionnaire (WLQ). On the basis of the original WLQ, this new survey instrument assesses the effect of caregiving for ill and/or disabled persons on the caregiver's work performance. A questionnaire was administered anonymously to employees of a large business services company. Scale reliability and validity were tested with psychometric methods. Of 4128 survey participants, 18.3% currently were caregivers, 10.2% were past caregivers, and 71.5% were not caregivers. Current caregivers were limited in their ability to perform basic job tasks between mean 10.3% and 16.8% of the time. Confirmatory factor analysis yielded a scale structure similar to the WLQ's. Scales reliabilities (the Cronbach's α) ranged from 0.91 to 0.95. The Caregiver WLQ is a new tool for understanding the workplace effect of caregiving.

School Performance and Disease Interference in Adolescents with Sickle Cell Disease

ERIC Educational Resources Information Center

Crosby, Lori E.; Joffe, Naomi E.; Irwin, Mary Kay; Strong, Heather; Peugh, James; Shook, Lisa; Kalinyak, Karen A.; Mitchell, Monica J.

2015-01-01

Sickle cell disease (SCD) results in neuropsychological complications that place adolescents at higher risk for limited educational achievement. A first step to developing effective educational interventions is to understand the impact of SCD on school performance. The current study assessed perceptions of school performance, SCD interference and…

Integration of Mobile AR Technology in Performance Assessment

ERIC Educational Resources Information Center

Kuo-Hung, Chao; Kuo-En, Chang; Chung-Hsien, Lan; Kinshuk; Yao-Ting, Sung

2016-01-01

This study was aimed at exploring how to use augmented reality (AR) technology to enhance the effect of performance assessment (PA). A mobile AR performance assessment system (MARPAS) was developed by integrating AR technology to reduce the limitations in observation and assessment during PA. This system includes three modules: Authentication, AR…

Loss of thermal refugia near equatorial range limits.

PubMed

Lima, Fernando P; Gomes, Filipa; Seabra, Rui; Wethey, David S; Seabra, Maria I; Cruz, Teresa; Santos, António M; Hilbish, Thomas J

2016-01-01

This study examines the importance of thermal refugia along the majority of the geographical range of a key intertidal species (Patella vulgata Linnaeus, 1758) on the Atlantic coast of Europe. We asked whether differences between sun-exposed and shaded microhabitats were responsible for differences in physiological stress and ecological performance and examined the availability of refugia near equatorial range limits. Thermal differences between sun-exposed and shaded microhabitats are consistently associated with differences in physiological performance, and the frequency of occurrence of high temperatures is most probably limiting the maximum population densities supported at any given place. Topographical complexity provides thermal refugia throughout most of the distribution range, although towards the equatorial edges the magnitude of the amelioration provided by shaded microhabitats is largely reduced. Importantly, the limiting effects of temperature, rather than being related to latitude, seem to be tightly associated with microsite variability, which therefore is likely to have profound effects on the way local populations (and consequently species) respond to climatic changes. © 2015 John Wiley & Sons Ltd.

AGARD Bulletin Technical Programme 1986.

DTIC Science & Technology

1985-08-01

basic research findings are being exploited by the pharmaceutical industry to develop new performance enhancing drugs with limited side effects and to... effects of nutrients on performance will also be considered. SHORT COURSE ( K Subject to final approval by the National Delegates Board at its Fall...coordinated with the AVP. WORKING GROUP The EPP will initiate Working Group-02 on "Near Water Propagation Effects and Modem System Adaptation". This

Medical and Genetic Differences in the Adverse Impact of Sleep Loss on Performance: Ethical Considerations for the Medical Profession

PubMed Central

Czeisler, Charles A.

2009-01-01

The Institute of Medicine recently concluded that-on average-medical residents make more serious medical errors and have more motor vehicle crashes when they are deprived of sleep. In the interest of public safety, society has required limitations on work hours in many other safety sensitive occupations, including transportation and nuclear power generation. Those who argue in favor of traditional extended duration resident work hours often suggest that there are inter- individual differences in response to acute sleep loss or chronic sleep deprivation, implying that physicians may be more resistant than the average person to the detrimental effects of sleep deprivation on performance, although there is no evidence that physicians are particularly resistant to such effects. Indeed, recent investigations have identified genetic polymorphisms that may convey a relative resistance to the effects of prolonged wakefulness on a subset of the healthy population, although there is no evidence that physicians are over-represented in this cohort. Conversely, there are also genetic polymorphisms, sleep disorders and other inter-individual differences that appear to convey an increased vulnerability to the performance-impairing effects of 24 hours of wakefulness. Given the magnitude of inter-individual differences in the effect of sleep loss on cognitive performance, and the sizeable proportion of the population affected by sleep disorders, hospitals face a number of ethical dilemmas. How should the work hours of physicians be limited to protect patient safety optimally? For example, some have argued that, in contrast to other professions, work schedules that repeatedly induce acute and chronic sleep loss are uniquely essential to the training of physicians. If evidence were to prove this premise to be correct, how should such training be ethically accomplished in the quartile of physicians and surgeons who are most vulnerable to the effects of sleep loss on performance without unacceptably compromising patient safety? Moreover, once it is possible to identify reliably those most vulnerable to the adverse effects of sleep loss on performance, will academic medical centers have an obligation to evaluate the proficiency of both residents and staff physicians under conditions of acute and chronic sleep deprivation? Should work-hour policy limits be modified to ensure that they are not hazardous for the patients of the most vulnerable quartile of physicians, or should the limits be personalized to enable the most resistant quartile to work longer hours? Given that the prevalence of sleep disorders has increased in our society overall, and increases markedly with age, how should fitness for extended duration work hours be monitored over a physician's career? In the spirit of the dictum to do no harm, advances in understanding the medical and genetic basis of inter-individual differences in the performance vulnerability to sleep loss should be incorporated into the development of work-hour policy limits for both physicians and surgeons. PMID:19768182

Medical and genetic differences in the adverse impact of sleep loss on performance: ethical considerations for the medical profession.

PubMed

Czeisler, Charles A

2009-01-01

The Institute of Medicine recently concluded that-on average-medical residents make more serious medical errors and have more motor vehicle crashes when they are deprived of sleep. In the interest of public safety, society has required limitations on work hours in many other safety sensitive occupations, including transportation and nuclear power generation. Those who argue in favor of traditional extended duration resident work hours often suggest that there are inter- individual differences in response to acute sleep loss or chronic sleep deprivation, implying that physicians may be more resistant than the average person to the detrimental effects of sleep deprivation on performance, although there is no evidence that physicians are particularly resistant to such effects. Indeed, recent investigations have identified genetic polymorphisms that may convey a relative resistance to the effects of prolonged wakefulness on a subset of the healthy population, although there is no evidence that physicians are over-represented in this cohort. Conversely, there are also genetic polymorphisms, sleep disorders and other inter-individual differences that appear to convey an increased vulnerability to the performance-impairing effects of 24 hours of wakefulness. Given the magnitude of inter-individual differences in the effect of sleep loss on cognitive performance, and the sizeable proportion of the population affected by sleep disorders, hospitals face a number of ethical dilemmas. How should the work hours of physicians be limited to protect patient safety optimally? For example, some have argued that, in contrast to other professions, work schedules that repeatedly induce acute and chronic sleep loss are uniquely essential to the training of physicians. If evidence were to prove this premise to be correct, how should such training be ethically accomplished in the quartile of physicians and surgeons who are most vulnerable to the effects of sleep loss on performance without unacceptably compromising patient safety? Moreover, once it is possible to identify reliably those most vulnerable to the adverse effects of sleep loss on performance, will academic medical centers have an obligation to evaluate the proficiency of both residents and staff physicians under conditions of acute and chronic sleep deprivation? Should work-hour policy limits be modified to ensure that they are not hazardous for the patients of the most vulnerable quartile of physicians, or should the limits be personalized to enable the most resistant quartile to work longer hours? Given that the prevalence of sleep disorders has increased in our society overall, and increases markedly with age, how should fitness for extended duration work hours be monitored over a physician's career? In the spirit of the dictum to do no harm, advances in understanding the medical and genetic basis of inter-individual differences in the performance vulnerability to sleep loss should be incorporated into the development of work-hour policy limits for both physicians and surgeons.

Climate induced temperature effects on growth performance, fecundity and recruitment in marine fish: developing a hypothesis for cause and effect relationships in Atlantic cod ( Gadus morhua) and common eelpout ( Zoarces viviparus)

NASA Astrophysics Data System (ADS)

Pörtner, H. O.; Berdal, B.; Blust, R.; Brix, O.; Colosimo, A.; De Wachter, B.; Giuliani, A.; Johansen, T.; Fischer, T.; Knust, R.; Lannig, G.; Naevdal, G.; Nedenes, A.; Nyhammer, G.; Sartoris, F. J.; Serendero, I.; Sirabella, P.; Thorkildsen, S.; Zakhartsev, M.

2001-12-01

Effects of global warming on animal distribution and performance become visible in many marine ecosystems. The present study was designed to develop a concept for a cause and effect understanding with respect to temperature changes and to explain ecological findings based on physiological processes. The concept is based on a wide comparison of invertebrate and fish species with a special focus on recent data obtained in two model species of fish. These fish species are both characterized by northern and southern distribution limits in the North Atlantic: eelpout ( Zoarces viviparus), as a typical non-migrating inhabitant of the coastal zone and the cod ( Gadus morhua), as a typical inhabitant of the continental shelf with a high importance for fisheries. Mathematical modelling demonstrates a clear significant correlation between climate induced temperature fluctuations and the recruitment of cod stocks. Growth performance in cod is optimal at temperatures close to 10°C, regardless of the population investigated in a latitudinal cline. However, temperature specific growth rates decrease at higher latitudes. Also, fecundity is less in White Sea than in North and Baltic Sea cod or eelpout populations. These findings suggest that a cold-induced shift in energy budget occurs which is unfavorable for growth performance and fecundity. Thermal tolerance limits shift depending on latitude and are characterized by oxygen limitation at both low or high temperatures. Oxygen supply to tissues is optimized at low temperature by a shift in hemoglobin isoforms and oxygen binding properties to lower affinities and higher unloading potential. Protective stimulation of heat shock protein synthesis was not observed. According to a recent model of thermal tolerance the downward shift of tolerance limits during cold adaptation is associated with rising mitochondrial densities and, thus, aerobic capacity and performance in the cold, especially in eurythermal species. At the same time the costs of mitochondrial maintenance reflected by mitochondrial proton leakage should rise leaving a lower energy fraction for growth and reproduction. The preliminary conclusion can be drawn that warming will cause a northern shift of distribution limits for both species with a rise in growth performance and fecundity larger than expected from the Q 10 effect in the north and lower growth or even extinction of the species in the south. Such a shift may heavily affect fishing activities in the North Sea.

Knock-limited performance of several internal coolants

NASA Technical Reports Server (NTRS)

Bellman, Donald R; Evvard, John C

1945-01-01

The effect of internal cooling on the knock-limited performance of an-f-28 fuel was investigated in a CFR engine, and the following internal coolants were used: (1) water, (2), methyl alcohol-water mixture, (3) ammonia-methyl alcohol-water mixture, (4) monomethylamine-water mixture, (5) dimethylamine-water mixture, and (6) trimethylamine-water mixture. Tests were run at inlet-air temperatures of 150 degrees and 250 degrees F. to indicate the temperature sensitivity of the internal-coolant solutions.

High temperature, oxygen, and performance: Insights from reptiles and amphibians.

PubMed

Gangloff, Eric J; Telemeco, Rory S

2018-04-25

Much recent theoretical and empirical work has sought to describe the physiological mechanisms underlying thermal tolerance in animals. Leading hypotheses can be broadly divided into two categories that primarily differ in organizational scale: 1) high temperature directly reduces the function of subcellular machinery, such as enzymes and cell membranes, or 2) high temperature disrupts system-level interactions, such as mismatches in the supply and demand of oxygen, prior to having any direct negative effect on the subcellular machinery. Nonetheless, a general framework describing the contexts under which either subcellular component or organ system failure limits organisms at high temperatures remains elusive. With this commentary, we leverage decades of research on the physiology of ectothermic tetrapods (amphibians and non-avian reptiles) to address these hypotheses. Available data suggest both mechanisms are important. Thus, we expand previous work and propose the Hierarchical Mechanisms of Thermal Limitation (HMTL) hypothesis, which explains how subcellular and organ system failures interact to limit performance and set tolerance limits at high temperatures. We further integrate this framework with the thermal performance curve paradigm commonly used to predict the effects of thermal environments on performance and fitness. The HMTL framework appears to successfully explain diverse observations in reptiles and amphibians and makes numerous predictions that remain untested. We hope that this framework spurs further research in diverse taxa and facilitates mechanistic forecasts of biological responses to climate change.

Systematic review of effectiveness of situated e-learning on medical and nursing education.

PubMed

Feng, Jui-Ying; Chang, Yi-Ting; Chang, Hsin-Yi; Erdley, William Scott; Lin, Chyi-Her; Chang, Ying-Ju

2013-08-01

Because of the complexity of clinical situations, traditional didactic education is limited in providing opportunity for student-patient interaction. Situated e-learning can enhance learners' knowledge and associated abilities through a variety of activities. Healthcare providers who interact with virtual patients in designed situations may avoid unnecessary risks and encounters with real patients. However, the effectiveness of situated e-learning is inconsistent. The purpose of this study is to determine the effectiveness of situated e-learning in prelicensure and postlicensure medical and nursing education. Literature databases of PubMed, Medline, CINAHL, ERIC, and Cochrane Library were searched. The study eligibility criteria included articles published in English, which examined the effectiveness of situated e-learning on the outcomes of knowledge and performance for clinicians or students in medicine and nursing. Effect sizes were calculated with 95% confidence intervals. Fourteen articles were included for meta-analysis. Situated e-learning could effectively enhance learners' knowledge and performance when the control group received no training. Compared to traditional learning, the effectiveness of situated e-learning on performance diminished but still remained significant whereas the effect become insignificant on knowledge. The subgroup analyses indicate the situated e-learning program significantly improved students' clinical performance but not for clinicians. Situated e-learning is an effective method to improve novice learners' performance. The effect of situated e-learning on the improvement of cognitive ability is limited when compared to traditional learning. Situated e-learning is a useful adjunct to traditional learning for medical and nursing students. © 2013 Sigma Theta Tau International.

Human Factors Assessment of Vibration Effects on Visual Performance During Launch

NASA Technical Reports Server (NTRS)

Holden, Kritina

2009-01-01

The Human Factors Assessment of Vibration Effects on Visual Performance During Launch (Visual Performance) investigation will determine visual performance limits during operational vibration and g-loads on the Space Shuttle, specifically through the determination of minimum readable font size during ascent using planned Orion display formats. Research Summary: The aim of the Human Factors Assessment of Vibration Effects on Visual Performance during Launch (Visual Performance) investigation is to provide supplementary data to that collected by the Thrust Oscillation Seat Detailed Technical Objective (DTO) 695 (Crew Seat DTO) which will measure seat acceleration and vibration from one flight deck and two middeck seats during ascent. While the Crew Seat DTO data alone are important in terms of providing a measure of vibration and g-loading, human performance data are required to fully interpret the operational consequences of the vibration values collected during Space Shuttle ascent. During launch, crewmembers will be requested to view placards with varying font sizes and indicate the minimum readable size. In combination with the Crew Seat DTO, the Visual Performance investigation will: Provide flight-validated evidence that will be used to establish vibration limits for visual performance during combined vibration and linear g-loading. o Provide flight data as inputs to ongoing ground-based simulations, which will further validate crew visual performance under vibration loading in a controlled environment. o Provide vibration and performance metrics to help validate procedures for ground tests and analyses of seats, suits, displays and controls, and human-in-the-loop performance.

Field-effect transistor improves electrometer amplifier

NASA Technical Reports Server (NTRS)

Munoz, R.

1964-01-01

An electrometer amplifier uses a field effect transistor to measure currents of low amperage. The circuit, developed as an ac amplifier, is used with an external filter which limits bandwidth to achieve optimum noise performance.

Animal studies on growth and development.

PubMed

Lerchl, Alexander

2011-12-01

Despite the fact that no plausible biological mechanism has yet been identified how electromagnetic fields below recommended exposure limits could negatively affect health of animals or humans, many experiments have been performed in various animal species, mainly mice and rats, to investigate the possible effects on growth and development. While older studies often suffered from sub-optimal exposure conditions, recent investigations, using sophisticated exposure devices and thus preventing thermal effects, have been performed without these limitations. In principle, two types of studies can be addressed: those which have investigated the carcinogenic or co-carcinogenic effects of exposure in developing animals, and those which have been done in developing animals without the focus on carcinogenic or co-carcinogenic effects. In both areas, the vast majority of publications did not show adverse effects. The largest study so far has been done in normal mice which have been chronically exposed to UMTS signals up to 1.3 W/kg SAR, thus 16 times higher than the whole-body exposure limit for humans. Even after four generations, no systematic or dose-dependent alterations in development or fertility could be found, supporting the view that negative effects on humans are very unlikely. Ongoing experiments in our laboratory investigate the effects of head-only exposure in rats (up to 10 W/kg local SAR) which are exposed from 14 days of age daily for 2 h. A battery of behavioral tests is performed in young, adult, and pre-senile animals. The results will help to clarify possible effects of exposure on brain development. Copyright © 2011 Elsevier Ltd. All rights reserved.

Characteristics of Whipple Shield Performance in the Shatter Regime

NASA Technical Reports Server (NTRS)

Ryan, S.; Bjorkman, M.; Christiansen, E. L.

2010-01-01

Ballistic limit equations define the failure of metallic Whipple shields in three parts: low velocity, shatter, and hypervelocity. Failure limits in the shatter regime are based on a linear interpolation between the onset of projectile fragmentation, and impulsive rupture of the shield rear wall. A series of hypervelocity impact tests have been performed on aluminum alloy Whipple shields to investigate failure mechanisms and performance limits in the shatter regime. Test results demonstrated a more rapid increase in performance than predicted by the latest iteration of the JSC Whipple shield BLE following the onset of projectile fragmentation. This increase in performance was found to level out between 4.0-5.0 km/s, with a subsequent decrease in performance for velocities up to 6.0 km/s. For a detached spall failure criterion, the failure limit was found to continually decrease up to a velocity of 7.0 km/s, substantially varying from the BLE, while for perforation-based failure an increase in performance was observed. An existing phenomenological ballistic limit curve was found to provide a more accurate reproduction of shield behavior that the BLE, however a number of underlying assumptions such as the occurrence of complete projectile fragmentation and the effect on performance of incipient projectile melt were found to be inaccurate. A cratering relationship based on the largest residual fragment size has been derived for application at velocities between 3.0-4.0 km/s, and was shown to accurately reproduce the trends of the experimental data. Further investigation is required to allow a full analytical description of shatter regime performance for metallic Whipple shields.

Carbohydrate intake and tennis: are there benefits?

PubMed Central

Kovacs, M S

2006-01-01

Carbohydrate supplementation in prolonged aerobic exercise has been shown to be effective in improving performance and deferring fatigue. However, there is confounding evidence with regard to carbohydrate supplementation and tennis performance, which may be due to the limited number of studies on this topic. This evidence based review, using database searches of Medline and SPORTDiscus, summarises the limited relevant literature to determine if carbohydrate supplementation benefits tennis performance, and, if so, the appropriate amounts and timing. Although more research is required, it appears that it may be beneficial in tennis sessions lasting more than 90 minutes. PMID:16632561

LOAD-ENHANCED MOVEMENT QUALITY SCREENING AND TACTICAL ATHLETICISM: AN EXTENSION OF EVIDENCE

PubMed Central

Schmitz, Randy J.; Rhea, Christopher K.; Ross, Scott E.

2017-01-01

Background Military organizations use movement quality screening for prediction of injury risk and performance potential. Currently, evidence of an association between movement quality and performance is limited. Recent work has demonstrated that external loading strengthens the relationship between movement screens and performance outcomes. Such loading may therefore steer us toward robust implementations of movement quality screens while maintaining their appeal as cost effective, field-expedient tools. Purpose The purpose of the current study was to quantify the effect of external load-bearing on the relationship between clinically rated movement quality and tactical performance outcomes while addressing the noted limitations. Study Design Crossover Trial. Methods Fifty young adults (25 male, 25 female, 22.98 ± 3.09 years, 171.95 ± 11.46 cm, 71.77 ± 14.03 kg) completed the Functional Movement Screen™ with (FMS™W) and without (FMS™C) a weight vest in randomized order. Following FMS™ testing, criterion measures of tactical performance were administered, including agility T-Tests, sprints, a 400-meter run, the Mobility for Battle (MOB) course, and a simulated casualty rescue. For each performance outcome, regression models were selected via group lasso with smoothed FMS™ item scores as candidate predictor variables. Results For all outcomes, proportion of variance accounted for was greater in FMS™W (R2 = ;0.22 [T-Test], 0.29 [Sprint], 0.17 [400 meter], 0.29 [MOB], and 0.11 [casualty rescue]) than in FMS™C (R2 = ;0.00 [T-Test], 0.11 [Sprint], 0.00 [400 meter], 0.19 [MOB], and 0.00 [casualty rescue]). From the FMS™W condition, beneficial performance effects (p<0.05) were observed for Deep Squat (sprint, casualty rescue), Hurdle Step (T-Agility, 400 meter run), Inline Lunge (sprint, MOB), and Trunk Stability Push Up (all models). Similar effects for FMS™C item scores were limited to Trunk Stability Push Up (p<0.05, all models). Conclusions The present study extends evidence supporting the validity of load-enhanced movement quality screening as a predictor of tactical performance ability. Future designs should seek to identify mechanisms explaining this effect. Level of Evidence 3 PMID:28593095

LOAD-ENHANCED MOVEMENT QUALITY SCREENING AND TACTICAL ATHLETICISM: AN EXTENSION OF EVIDENCE.

PubMed

Glass, Stephen M; Schmitz, Randy J; Rhea, Christopher K; Ross, Scott E

2017-06-01

Military organizations use movement quality screening for prediction of injury risk and performance potential. Currently, evidence of an association between movement quality and performance is limited. Recent work has demonstrated that external loading strengthens the relationship between movement screens and performance outcomes. Such loading may therefore steer us toward robust implementations of movement quality screens while maintaining their appeal as cost effective, field-expedient tools. The purpose of the current study was to quantify the effect of external load-bearing on the relationship between clinically rated movement quality and tactical performance outcomes while addressing the noted limitations. Crossover Trial. Fifty young adults (25 male, 25 female, 22.98 ± 3.09 years, 171.95 ± 11.46 cm, 71.77 ± 14.03 kg) completed the Functional Movement Screen™ with (FMS™W) and without (FMS™C) a weight vest in randomized order. Following FMS™ testing, criterion measures of tactical performance were administered, including agility T-Tests, sprints, a 400-meter run, the Mobility for Battle (MOB) course, and a simulated casualty rescue. For each performance outcome, regression models were selected via group lasso with smoothed FMS™ item scores as candidate predictor variables. For all outcomes, proportion of variance accounted for was greater in FMS™W (R 2 = ;0.22 [T-Test], 0.29 [Sprint], 0.17 [400 meter], 0.29 [MOB], and 0.11 [casualty rescue]) than in FMS™C (R 2 = ;0.00 [T-Test], 0.11 [Sprint], 0.00 [400 meter], 0.19 [MOB], and 0.00 [casualty rescue]). From the FMS™W condition, beneficial performance effects (p<0.05) were observed for Deep Squat (sprint, casualty rescue), Hurdle Step (T-Agility, 400 meter run), Inline Lunge (sprint, MOB), and Trunk Stability Push Up (all models). Similar effects for FMS™C item scores were limited to Trunk Stability Push Up (p<0.05, all models). The present study extends evidence supporting the validity of load-enhanced movement quality screening as a predictor of tactical performance ability. Future designs should seek to identify mechanisms explaining this effect. 3.

Interactive effect of warming, nitrogen and phosphorus limitation on phytoplankton cell size

PubMed Central

Peter, Kalista Higini; Sommer, Ulrich

2015-01-01

Cell size is one of the ecologically most important traits of phytoplankton. The cell size variation is frequently related to temperature and nutrient limitation. In order to disentangle the role of both factors, an experiment was conducted to determine the possible interactions of these factors. Baltic Sea water containing the natural plankton community was used. We performed a factorial combined experiment of temperature, type of nutrient limitation (N vs. P), and strength of nutrient limitation. The type of nutrient limitation was manipulated by altering the N:P ratio of the medium (balanced, N and P limitation) and strength by the dilution rate (0% and 50%) of the semicontinuous cultures. The negative effect of temperature on cell size was strongest under N limitation, intermediate under P limitation, and weakest when N and P were supplied at balanced ratios. However, temperature also influenced the intensity of nutrient imitation, because at higher temperature there was a tendency for dissolved nutrient concentrations to be lower, while the C:N or C:P ratio being higher…higher at identical dilution rates and medium composition. Analyzing the response of cell size to C:N ratios (as index of N limitation) and C:P ratios (as index of P limitation) indicated a clear dominance of the nutrient effect over the direct temperature effect, although the temperature effect was also significant. PMID:25798219

Effect of medical conditions on improvement in self-reported and observed functional performance of elders.

PubMed

Miller, Ram R; Zhang, Yuqing; Silliman, Rebecca A; Hayes, Margaret Kelly; Leveille, Suzanne G; Murabito, Joanne M; Kiel, Douglas; O'Connor, George T; Felson, David T

2004-02-01

To evaluate the effect of nine disabling medical conditions upon recovery from functional limitations by elders. Retrospective analysis of prospective longitudinal cohort. Community. Persons aged 65 and older in Framingham Heart Study. Change in function in elders from biennial Examinations 18 (1983-85; baseline) through 23 (1994-96). At each examination, subjects reported limitations in heavy household work, walking up and down stairs, walking half a mile, bathing, toileting, and continence. They were also directly observed for performance of transferring in and out of a chair, dressing, walking 50 feet, and carrying a 10-pound object 10 feet. The prevalence of functional limitations and the incidence of recovery from functional limitation by the subsequent examination for each task were calculated. The effects of congestive heart failure, cognitive impairment, diabetes mellitus, stroke, depressive symptoms, hip fracture, knee pain, claudication, and chronic obstructive pulmonary disease were evaluated. The relationship between the total number of comorbid conditions present (0, 1, 2, 3 or more), the presence of each individual condition at the start of each examination cycle, and the incidence of recovery from functional limitations were examined using generalized estimating equations. One thousand eight hundred twenty-five subjects were studied at baseline; 1,026 were available 10 years later. Mean age of subjects at baseline was 73.5 (range 61-95); 60.7% were women. The prevalence of functional limitations ranged from 3.1% to 29.8% at biennial Examination 18 and increased to 15.1% to 32.4% at Examination 23. The incidence of recovery ranged from 3.2% to 78.4% depending upon the task and the examination cycle. Increasing disease burden, as measured by the number of comorbidities, was associated with a decreased likelihood of recovery from functional limitations. Diabetes mellitus, stroke, depressive symptoms, hip fracture, and knee pain had the strongest adverse effect upon recovery from functional limitations. In these community-dwelling elders, recovery from prevalent functional limitations was frequent. Increasing disease burden was associated with a decreased incidence of recovery. Diabetes mellitus, stroke, depressive symptoms, hip fracture, and knee pain had the strongest adverse effect on recovery from functional limitations.

Accelerating a Particle-in-Cell Simulation Using a Hybrid Counting Sort

NASA Astrophysics Data System (ADS)

Bowers, K. J.

2001-11-01

In this article, performance limitations of the particle advance in a particle-in-cell (PIC) simulation are discussed. It is shown that the memory subsystem and cache-thrashing severely limit the speed of such simulations. Methods to implement a PIC simulation under such conditions are explored. An algorithm based on a counting sort is developed which effectively eliminates PIC simulation cache thrashing. Sustained performance gains of 40 to 70 percent are measured on commodity workstations for a minimal 2d2v electrostatic PIC simulation. More complete simulations are expected to have even better results as larger simulations are usually even more memory subsystem limited.

Limiting neutrino magnetic moments with Borexino Phase-II solar neutrino data

NASA Astrophysics Data System (ADS)

Agostini, M.; Altenmüller, K.; Appel, S.; Atroshchenko, V.; Bagdasarian, Z.; Basilico, D.; Bellini, G.; Benziger, J.; Bick, D.; Bonfini, G.; Bravo, D.; Caccianiga, B.; Calaprice, F.; Caminata, A.; Caprioli, S.; Carlini, M.; Cavalcante, P.; Chepurnov, A.; Choi, K.; Collica, L.; D'Angelo, D.; Davini, S.; Derbin, A.; Ding, X. F.; Di Ludovico, A.; Di Noto, L.; Drachnev, I.; Fomenko, K.; Formozov, A.; Franco, D.; Froborg, F.; Gabriele, F.; Galbiati, C.; Ghiano, C.; Giammarchi, M.; Goretti, A.; Gromov, M.; Guffanti, D.; Hagner, C.; Houdy, T.; Hungerford, E.; Ianni, Aldo; Ianni, Andrea; Jany, A.; Jeschke, D.; Kobychev, V.; Korablev, D.; Korga, G.; Kryn, D.; Laubenstein, M.; Litvinovich, E.; Lombardi, F.; Lombardi, P.; Ludhova, L.; Lukyanchenko, G.; Lukyanchenko, L.; Machulin, I.; Manuzio, G.; Marcocci, S.; Martyn, J.; Meroni, E.; Meyer, M.; Miramonti, L.; Misiaszek, M.; Muratova, V.; Neumair, B.; Oberauer, L.; Opitz, B.; Orekhov, V.; Ortica, F.; Pallavicini, M.; Papp, L.; Penek, Ã.-.; Pilipenko, N.; Pocar, A.; Porcelli, A.; Ranucci, G.; Razeto, A.; Re, A.; Redchuk, M.; Romani, A.; Roncin, R.; Rossi, N.; Schönert, S.; Semenov, D.; Skorokhvatov, M.; Smirnov, O.; Sotnikov, A.; Stokes, L. F. F.; Suvorov, Y.; Tartaglia, R.; Testera, G.; Thurn, J.; Toropova, M.; Unzhakov, E.; Vishneva, A.; Vogelaar, R. B.; von Feilitzsch, F.; Wang, H.; Weinz, S.; Wojcik, M.; Wurm, M.; Yokley, Z.; Zaimidoroga, O.; Zavatarelli, S.; Zuber, K.; Zuzel, G.; Borexino Collaboration

2017-11-01

A search for the solar neutrino effective magnetic moment has been performed using data from 1291.5 days exposure during the second phase of the Borexino experiment. No significant deviations from the expected shape of the electron recoil spectrum from solar neutrinos have been found, and a new upper limit on the effective neutrino magnetic moment of μνeff<2.8×10 -11 μB at 90% C.L. has been set using constraints on the sum of the solar neutrino fluxes implied by the radiochemical gallium experiments. Using the limit for the effective neutrino moment, new limits for the magnetic moments of the neutrino flavor states, and for the elements of the neutrino magnetic moments matrix for Dirac and Majorana neutrinos, are derived.

The Effects of Aerobic Exercise and Gaming on Cognitive Performance.

PubMed

Douris, Peter C; Handrakis, John P; Apergis, Demitra; Mangus, Robert B; Patel, Rima; Limtao, Jessica; Platonova, Svetlana; Gregorio, Aladino; Luty, Elliot

2018-03-01

The purpose of our study was to investigate the effects of video gaming, aerobic exercise (biking), and the combination of these two activities on the domains of cognitive performance: selective attention, processing speed, and executive functioning. The study was a randomized clinical trial with 40 subjects (mean age 23.7 ± 1.8 years) randomized to one of four thirty-minute conditions: video gaming, biking, simultaneous gaming and biking, and a control condition. Cognitive performance was measured pre and post condition using the Stroop test and Trails B test. A mixed design was utilized. While video gaming, biking, simultaneous gaming and biking conditions improved selective attention and processing speed (p < 0.05), only the bike condition improved the highest order of cognitive performance, executive function (p < 0.01). There were no changes in cognitive performance for the control condition. Previous studies have shown that if tasks approach the limits of attentional capacity there is an increase in the overall chance for errors, known as the dual-task deficit. Simultaneous biking and gaming may have surpassed attentional capacity limits, ultimately increasing errors during the executive function tests of our cognitive performance battery. The results suggest that the fatiguing effects of a combined physically and mentally challenging task that extends after the exercise cessation may overcome the eventual beneficial cognitive effects derived from the physical exercise.

Central dopaminergic neurotransmission plays an important role in thermoregulation and performance during endurance exercise.

PubMed

Zheng, Xinyan; Hasegawa, Hiroshi

2016-10-01

Dopamine (DA) has been widely investigated for its potential role in determining exercise performance. It was originally thought that DA's ergogenic effect was by mediating psychological responses. Recently, some studies have also suggested that DA may regulate physiological responses, such as thermoregulation. Hyperthermia has been demonstrated as an important limiting factor during endurance exercise. DA is prominent in the thermoregulatory centre, and changes in DA concentration have been shown to affect core temperature regulation during exercise. Some studies have proposed that DA or DA/noradrenaline (NA) reuptake inhibitors can improve exercise performance, despite hyperthermia during exercise in the heat. DA/NA reuptake inhibitors also increase catecholamine release in the thermoregulatory centre. Intracerebroventricularly injected DA has been shown to improve exercise performance through inhibiting hyperthermia-induced fatigue, even at normal ambient temperatures. Further, caffeine has been reported to increase DA release in the thermoregulatory centre and improves endurance exercise performance despite increased core body temperature. Taken together, DA has been shown to have ergogenic effects and increase heat storage and hyperthermia tolerance. The mechanisms underlying these effects seem to involve limiting/overriding the inhibitory signals from the central nervous system that result in cessation of exercise due to hyperthermia.

More oxygen during development enhanced flight performance but not thermal tolerance of Drosophila melanogaster

PubMed Central

Shiehzadegan, Shayan; Le Vinh Thuy, Jacqueline; Szabla, Natalia; Angilletta, Michael J.

2017-01-01

High temperatures can stress animals by raising the oxygen demand above the oxygen supply. Consequently, animals under hypoxia could be more sensitive to heating than those exposed to normoxia. Although support for this model has been limited to aquatic animals, oxygen supply might limit the heat tolerance of terrestrial animals during energetically demanding activities. We evaluated this model by studying the flight performance and heat tolerance of flies (Drosophila melanogaster) acclimated and tested at different concentrations of oxygen (12%, 21%, and 31%). We expected that flies raised at hypoxia would develop into adults that were more likely to fly under hypoxia than would flies raised at normoxia or hyperoxia. We also expected flies to benefit from greater oxygen supply during testing. These effects should have been most pronounced at high temperatures, which impair locomotor performance. Contrary to our expectations, we found little evidence that flies raised at hypoxia flew better when tested at hypoxia or tolerated extreme heat better than did flies raised at normoxia or hyperoxia. Instead, flies raised at higher oxygen levels performed better at all body temperatures and oxygen concentrations. Moreover, oxygen supply during testing had the greatest effect on flight performance at low temperature, rather than high temperature. Our results poorly support the hypothesis that oxygen supply limits performance at high temperatures, but do support the idea that hyperoxia during development improves performance of flies later in life. PMID:28542380

QUEST FOR A NEW WORKING POINT IN RHIC.

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

TOMAS,R.BAI,M.FISCHER,W.PTITSYN,V.SATOGATA,T.ROSER,T.

2004-07-05

The beam-beam interaction is a limiting factor in RHIC's performance, particularly in proton operation. Changing the working point is a strategy to alleviate the beam-beam effect and improve the performance of the machine. Experiments at injection energy and simulations have been performed for a set of working points to determine the best candidates.

How Six Sigma Methodology Improved Doctors' Performance

ERIC Educational Resources Information Center

Zafiropoulos, George

2015-01-01

Six Sigma methodology was used in a District General Hospital to assess the effect of the introduction of an educational programme to limit unnecessary admissions. The performance of the doctors involved in the programme was assessed. Ishikawa Fishbone and 5 S's were initially used and Pareto analysis of their findings was performed. The results…

Quantification of sulphur amino acids by ultra-high performance liquid chromatography in aquatic invertebrates.

PubMed

Thera, Jennifer C; Kidd, Karen A; Dodge-Lynch, M Elaine; Bertolo, Robert F

2017-12-15

We examined the performance of an ultra-high performance liquid chromatography method to quantify protein-bound sulphur amino acids in zooplankton. Both cysteic acid and methionine sulfone were linear from 5 to 250 pmol (r 2  = 0.99), with a method detection limit of 13 pmol and 9 pmol, respectively. Although there was no matrix effect on linearity, adjacent peaks and co-eluting noise from the invertebrate proteins increased the detection limits when compared to common standards. Overall, performance characteristics were reproducible and accurate, and provide a means for quantifying sulphur amino acids in aquatic invertebrates, an understudied group. Copyright © 2017 Elsevier Inc. All rights reserved.

The Effect of Job Performance Aids on Quality Assurance

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

Fosshage, Erik

Job performance aids (JPAs) have been studied for many decades in a variety of disciplines and for many different types of tasks, yet this is the first known research experiment using JPAs in a quality assurance (QA) context. The objective of this thesis was to assess whether a JPA has an effect on the performance of a QA observer performing the concurrent dual verification technique for a basic assembly task. The JPA used in this study was a simple checklist, and the design borrows heavily from prior research on task analysis and other human factors principles. The assembly task andmore » QA construct of concurrent dual verification are consistent with those of a high consequence manufacturing environment. Results showed that the JPA had only a limited effect on QA performance in the context of this experiment. However, there were three important and unexpected findings that may draw interest from a variety of practitioners. First, a novel testing methodology sensitive enough to measure the effects of a JPA on performance was created. Second, the discovery that there are different probabilities of detection for different types of error in a QA context may be the most far-reaching results. Third, these results highlight the limitations of concurrent dual verification as a control against defects. It is hoped that both the methodology and results of this study are an effective baseline from which to launch future research activities.« less

High-contrast coronagraph performance in the presence of focal plane mask defects

NASA Astrophysics Data System (ADS)

Sidick, Erkin; Shaklan, Stuart; Balasubramanian, Kunjithapatham; Cady, Eric

2014-08-01

We have carried out a study of the performance of high-contrast coronagraphs in the presence of mask defects. We have considered the effects of opaque and dielectric particles of various dimensions, as well as systematic mask fabrication errors and the limitations of material properties in creating dark holes. We employ sequential deformable mirrors to compensate for phase and amplitude errors, and show the limitations of this approach in the presence of coronagraph image-mask defects.

Application of Mixed Effects Limits of Agreement in the Presence of Multiple Sources of Variability: Exemplar from the Comparison of Several Devices to Measure Respiratory Rate in COPD Patients

PubMed Central

Weir, Christopher J.; Rubio, Noah; Rabinovich, Roberto; Pinnock, Hilary; Hanley, Janet; McCloughan, Lucy; Drost, Ellen M.; Mantoani, Leandro C.; MacNee, William; McKinstry, Brian

2016-01-01

Introduction The Bland-Altman limits of agreement method is widely used to assess how well the measurements produced by two raters, devices or systems agree with each other. However, mixed effects versions of the method which take into account multiple sources of variability are less well described in the literature. We address the practical challenges of applying mixed effects limits of agreement to the comparison of several devices to measure respiratory rate in patients with chronic obstructive pulmonary disease (COPD). Methods Respiratory rate was measured in 21 people with a range of severity of COPD. Participants were asked to perform eleven different activities representative of daily life during a laboratory-based standardised protocol of 57 minutes. A mixed effects limits of agreement method was used to assess the agreement of five commercially available monitors (Camera, Photoplethysmography (PPG), Impedance, Accelerometer, and Chest-band) with the current gold standard device for measuring respiratory rate. Results Results produced using mixed effects limits of agreement were compared to results from a fixed effects method based on analysis of variance (ANOVA) and were found to be similar. The Accelerometer and Chest-band devices produced the narrowest limits of agreement (-8.63 to 4.27 and -9.99 to 6.80 respectively) with mean bias -2.18 and -1.60 breaths per minute. These devices also had the lowest within-participant and overall standard deviations (3.23 and 3.29 for Accelerometer and 4.17 and 4.28 for Chest-band respectively). Conclusions The mixed effects limits of agreement analysis enabled us to answer the question of which devices showed the strongest agreement with the gold standard device with respect to measuring respiratory rates. In particular, the estimated within-participant and overall standard deviations of the differences, which are easily obtainable from the mixed effects model results, gave a clear indication that the Accelerometer and Chest-band devices performed best. PMID:27973556

Near-thermal limit gating in heavily doped III-V semiconductor nanowires using polymer electrolytes

NASA Astrophysics Data System (ADS)

Ullah, A. R.; Carrad, D. J.; Krogstrup, P.; Nygârd, J.; Micolich, A. P.

2018-02-01

Doping is a common route to reducing nanowire transistor on-resistance but it has limits. A high doping level gives significant loss in gate performance and ultimately complete gate failure. We show that electrolyte gating remains effective even when the Be doping in our GaAs nanowires is so high that traditional metal-oxide gates fail. In this regime we obtain a combination of subthreshold swing and contact resistance that surpasses the best existing p -type nanowire metal-oxide semiconductor field-effect transistors (MOSFETs). Our subthreshold swing of 75 mV/dec is within 25 % of the room-temperature thermal limit and comparable with n -InP and n -GaAs nanowire MOSFETs. Our results open a new path to extending the performance and application of nanowire transistors, and motivate further work on improved solid electrolytes for nanoscale device applications.

A control system design approach for flexible spacecraft

NASA Technical Reports Server (NTRS)

Silverberg, L. M.

1985-01-01

A control system design approach for flexible spacecraft is presented. The control system design is carried out in two steps. The first step consists of determining the ideal control system in terms of a desirable dynamic performance. The second step consists of designing a control system using a limited number of actuators that possess a dynamic performance that is close to the ideal dynamic performance. The effects of using a limited number of actuators is that the actual closed-loop eigenvalues differ from the ideal closed-loop eigenvalues. A method is presented to approximate the actual closed-loop eigenvalues so that the calculation of the actual closed-loop eigenvalues can be avoided. Depending on the application, it also may be desirable to apply the control forces as impulses. The effect of digitizing the control to produce the appropriate impulses is also examined.

Effects of visual feedback balance training on the balance and ankle instability in adult men with functional ankle instability.

PubMed

Nam, Seung-Min; Kim, Kyoung; Lee, Do Youn

2018-01-01

[Purpose] This study examined the effects of visual feedback balance training on the balance and ankle instability in adult men with functional ankle instability. [Subjects and Methods] Twenty eight adults with functional ankle instability, divided randomly into an experimental group, which performed visual feedback balance training for 20 minutes and ankle joint exercises for 10 minutes, and a control group, which performed ankle joint exercise for 30 minutes. Exercises were completed three times a week for 8 weeks. Bio rescue was used for balance ability. It measured limit of stability at one minute. For ankle instability was measured using Cumberland ankle instability tool (CAIT). This measure was performed before and after the experiments in each group. [Results] The experimental group had significant increase in the Limit of Stability and CAIT score. The control group had significant increase in CAIT score. While the Limit of Stability increased without significance. [Conclusion] In conclusion, visual feedback balance training can be recommended as a treatment method for patients with functional ankle instability.

Determination of benzothiazole and benzotriazole derivates in tire and clothing textile samples by high performance liquid chromatography-electrospray ionization tandem mass spectrometry.

PubMed

Avagyan, Rozanna; Sadiktsis, Ioannis; Thorsén, Gunnar; Östman, Conny; Westerholm, Roger

2013-09-13

A high performance liquid chromatography-tandem mass spectrometry method utilizing electrospray ionization in positive and negative mode has been developed for the separation and detection of benzothiazole and benzotriazole derivates. Ultra-sonication assisted solvent extraction of these compounds has also been developed and the overall method demonstrated on a selected clothing textile and an automobile tire sample. Matrix effects and extraction recoveries, as well as linearity and limits of detection have been evaluated. The calibration curves spanned over more than two orders of magnitude with coefficients of correlation R(2)>0.99 and the limits of detection and the limits of quantification were in the range 1.7-58pg injected and 18-140pg/g, respectively. The extraction recoveries ranged between 69% and 102% and the matrix effects between 75% and 101%. Benzothiazole and benzotriazole derivates were determined in the textile sample and benzothiazole derivatives determined in the tire sample with good analytical performance. Copyright © 2013 Elsevier B.V. All rights reserved.

Reconsidering community-based health promotion: promise, performance, and potential.

PubMed

Merzel, Cheryl; D'Afflitti, Joanna

2003-04-01

Contemporary public health emphasizes a community-based approach to health promotion and disease prevention. The evidence from the past 20 years indicates, however, that many community-based programs have had only modest impact, with the notable exception of a number of HIV prevention programs. To better understand the reasons for these outcomes, we conducted a systematic literature review of 32 community-based prevention programs. Reasons for poor performance include methodological challenges to study design and evaluation, concurrent secular trends, smaller-than-expected effect sizes, limitations of the interventions, and limitations of theories used. The effectiveness of HIV programs appears to be related in part to extensive formative research and an emphasis on changing social norms.

Effects of 4-week self cross body stretching with scapular stabilization on shoulder motions and horizontal adductor strength in subjects with limited shoulder horizontal adduction.

PubMed

Joung, Ha-Na; Yi, Chung-Hwi; Jeon, Hye-Seon; Hwang, Ui-Jae; Kwon, Oh-Yun

2018-05-29

Posterior shoulder tightness (PST) is related to shoulder conditions such as shoulder impingement and limited shoulder horizontal adduction (SHA). The purpose of this study was to compare the effects of self cross body stretching (CBS) with and without scapular stabilization (SS) on SHA and shoulder internal rotation (SIR) range of motion (ROM) and shoulder horizontal adductor strength (SHAS) in subjects with limited SHA. Twenty-six subjects (14 males, 12 females) with limited SHA was participated in this study. The SS group and without stabilization (WS) group were assigned randomly. The SS group performed self CBS with SS by applying belt just under the subject's axilla. The subjects were asked to perform self CBS in 4 times a week for 4 weeks. SHA and SIR RM were measured by Clinometer smartphone application, and SHAS by hand-held dynamometer (HHD) before and after 4-week self CBS. 2 × 2 mixed analysis of variance (ANOVA) was used to identify the significance. If there was an interaction effect, t-test was used to confirm the simple effect. There was a significant interaction in SHA ROM and SHAS. The post-test value of SHA ROM was significantly greater in SS group than WS group (p < 0.0125). In SHAS, there was no significant difference between groups (p > 0.0125). SS during self CBS could enhance to improve SHA, SIR ROM, and SHAS in individuals with limited SHA.

The Buffering Effect of Mindfulness on Abusive Supervision and Creative Performance: A Social Cognitive Framework.

PubMed

Zheng, Xiaoming; Liu, Xin

2017-01-01

Our research draws upon social cognitive theory and incorporates a regulatory approach to investigate why and when abusive supervision influences employee creative performance. The analyses of data from multiple time points and multiple sources reveal that abusive supervision hampers employee self-efficacy at work, which in turn impairs employee creative performance. Further, employee mindfulness buffers the negative effects of abusive supervision on employee self-efficacy at work as well as the indirect effects of abusive supervision on employee creative performance. Our findings have implications for both theory and practice. Limitations and directions for future research are also discussed.

The Buffering Effect of Mindfulness on Abusive Supervision and Creative Performance: A Social Cognitive Framework

PubMed Central

Zheng, Xiaoming; Liu, Xin

2017-01-01

Our research draws upon social cognitive theory and incorporates a regulatory approach to investigate why and when abusive supervision influences employee creative performance. The analyses of data from multiple time points and multiple sources reveal that abusive supervision hampers employee self-efficacy at work, which in turn impairs employee creative performance. Further, employee mindfulness buffers the negative effects of abusive supervision on employee self-efficacy at work as well as the indirect effects of abusive supervision on employee creative performance. Our findings have implications for both theory and practice. Limitations and directions for future research are also discussed. PMID:28955285

Numerical simulation of divergent rocket-based-combined-cycle performances under the flight condition of Mach 3

NASA Astrophysics Data System (ADS)

Cui, Peng; Xu, WanWu; Li, Qinglian

2018-01-01

Currently, the upper operating limit of the turbine engine is Mach 2+, and the lower limit of the dual-mode scramjet is Mach 4. Therefore no single power systems can operate within the range between Mach 2 + and Mach 4. By using ejector rockets, Rocket-based-combined-cycle can work well in the above scope. As the key component of Rocket-based-combined-cycle, the ejector rocket has significant influence on Rocket-based-combined-cycle performance. Research on the influence of rocket parameters on Rocket-based-combined-cycle in the speed range of Mach 2 + to Mach 4 is scarce. In the present study, influences of Mach number and total pressure of the ejector rocket on Rocket-based-combined-cycle were analyzed numerically. Due to the significant effects of the flight conditions and the Rocket-based-combined-cycle configuration on Rocket-based-combined-cycle performances, flight altitude, flight Mach number, and divergence ratio were also considered. The simulation results indicate that matching lower altitude with higher flight Mach numbers can increase Rocket-based-combined-cycle thrust. For another thing, with an increase of the divergent ratio, the effect of the divergent configuration will strengthen and there is a limit on the divergent ratio. When the divergent ratio is greater than the limit, the effect of divergent configuration will gradually exceed that of combustion on supersonic flows. Further increases in the divergent ratio will decrease Rocket-based-combined-cycle thrust.

Shot noise limit of chemically amplified resists with photodecomposable quenchers used for extreme ultraviolet lithography

NASA Astrophysics Data System (ADS)

Kozawa, Takahiro; Santillan, Julius Joseph; Itani, Toshiro

2017-06-01

In lithography using high-energy photons such as an extreme ultraviolet (EUV) radiation, the shot noise of photons is a critical issue. The shot noise is a cause of line edge/width roughness (LER/LWR) and stochastic defect generation and limits the resist performance. In this study, the effects of photodecomposable quenchers were investigated from the viewpoint of the shot noise limit. The latent images of line-and-space patterns with 11 nm half-pitch were calculated using a Monte Carlo method. In the simulation, the effect of secondary electron blur was eliminated to clarify the shot noise limits regarding stochastic phenomena such as LER. The shot noise limit for chemically amplified resists with acid generators and photodecomposable quenchers was approximately the same as that for chemically amplified resists with acid generators and conventional quenchers when the total sensitizer concentration was the same. The effect of photodecomposable quenchers on the shot noise limit was essentially the same as that of acid generators.

Work Functioning Among Firefighters: A Comparison Between Self-Reported Limitations and Functional Task Performance.

PubMed

MacDermid, Joy C; Tang, Kenneth; Sinden, Kathryn E; D'Amico, Robert

2018-05-25

Purpose Performance-based and disease indicators have been widely studied in firefighters; self-reported work role limitations have not. The aim of this study was to describe the distributions and correlations of a generic self-reported Work Limitations Questionnaire (WLQ-26) and firefighting-specific task performance-based tests. Methods Active firefighters from the City of Hamilton Fire Services (n = 293) were recruited. Participants completed the WLQ-26 to quantify on-the-job difficulties over five work domains: work scheduling (4 items), output demands (7 items), physical demands (8 items), mental demands (4 items), and social demands (3 items). A subset of participants (n = 149) were also assessed on hose drag and stair climb with a high-rise pack performance-based tests. Descriptive statistics and correlations were used to compare item/subscale performance; and to describe the inter-relationships between tests. Results The mean WLQ-26 item scores (/5) ranged from 4.1 to 4.4 (median = 5 for all items); most firefighters (54.5-80.5%) selected "difficult none of the time" response option on all items. A substantial ceiling effect was observed across all five WLQ-26 subscales as 44.0-55.6% were in the highest category. Subscale means ranged from 61.8 (social demands) to 78.7 (output demands and physical demands). Internal consistency exceeded 0.90 on all subscales. For the hose drag task, the mean time-to-completion was 48.0 s (SD = 14.5; range 20.4-95.0). For the stair climb task, the mean time-to-completion was 76.7 s (SD = 37.2; range 21.0-218.0). There were no significant correlations between self-report work limitations and performance of firefighting tasks. Conclusions The WLQ-26 measured five domains, but had ceiling effects in firefighters. Performance-based testing showed wider score range, lacked ceiling effects and did not correlate to the WLQ-26. A firefighter-specific, self-report role functioning scale may be needed to identify compromised work role capabilities in firefighters.

Effect of Temporal and Spatial Rainfall Resolution on HSPF Predictive Performance and Parameter Estimation

EPA Science Inventory

Watershed scale rainfall‐runoff models are used for environmental management and regulatory modeling applications, but their effectiveness are limited by predictive uncertainties associated with model input data. This study evaluated the effect of temporal and spatial rainfall re...

Task demands moderate stereotype threat effects on memory performance.

PubMed

Hess, Thomas M; Emery, Lisa; Queen, Tara L

2009-06-01

Previous research has demonstrated that older adults' memory performance is adversely affected by the explicit activation of negative stereotypes about aging. In this study, we examined the impact of stereotype threat on recognition memory, with specific interest in (a) the generalizability of previously observed effects, (b) the subjective experience of memory, and (c) the moderating effects of task demands. Older participants subjected to threat performed worse than did those in a nonthreat condition but only when performance constraints were high (i.e., memory decisions had to be made within a limited time frame). This effect was reflected in the subjective experience of memory, with participants in this condition having a lower ratio of "remember" to "know" responses. The absence of threat effects when constraints were minimal provides important boundary information regarding stereotype influences on memory performance.

Effect of Variable Chord Length on Transonic Axial Rotor Performance Investigated

NASA Technical Reports Server (NTRS)

Suder, Kenneth L.

2002-01-01

During the life of any gas turbine, blade erosion is present, especially for those units that are exposed to unfiltered air, such as aviation turbofan engines. The effect of this erosion is to reduce the blade chord progressively from the midspan to the tip region and to roughen and distort the blade surface. The effects of roughness on rotor performance have been documented by Suder et al. and Roberts. These papers indicate that the penalty for leading-edge roughness and erosion can be significant. Turbofan operators, therefore, restore chord length at routine maintenance intervals to regain performance before deterioration is too severe to salvage blades. As the rotor blades erode, the leading edge becomes rough - blunt and distorted from the nominal shape - and the aerodynamic performance suffers. Nominal performance can be recovered by recontouring the leading edges. This process, which inherently shortens the blade chord, can be used until the blade chord erodes to the stall limit. Below this chord length, which varies among engine-compressor types, a decrease of stall margin is likely. After compressor blade rework that includes leading edge recontouring, the blades have different chord lengths, ranging from blades that are near nominal chord length down to those near the stall chord limit. Furthermore, as blades erode below the stall limit, they must be replaced with new blades that have the full nominal chord length. Consequently, a set of compressor blades with varying chord lengths will be installed into each turbofan engine that goes through a complete maintenance cycle. The question arises, "Does fan or compressor performance depend on the order in which mixed-chord blades are installed into a fan or compressor disk?"

Evaluation of the effects of low energetic microwave irradiation on anaerobic digestion.

PubMed

Bastiaens, Bert; Van den Broeck, Rob; Appels, Lise; Dewil, Raf

2017-11-01

The present study investigates the effects of microwave irradiation on the performance of anaerobic digestion processes. A first set of experiments is performed to distinguish the upper limit of the applied energy levels. Secondly, the effects of these treatments on the performance of the digestion process are evaluated in 3 experimental setups: (i) monitoring the acetic acid degradation, (ii) performing a biological methane potential (BMP) assay and (iii) conducting a specific methanogenic activity (SMA) test. The solubilisation experiment reveals a limited degree of disintegration of anaerobic biomass up to a microwave treatment of 10000 kJ/kg TS. Above this threshold value the soluble COD level started to rise, with up to 350% at 30000 kJ/kg TS regardless of the microwave output power. Because solubilisation of the biomass increases the easily degradable content, this would lead to false observations regarding increased activity. Therefore, solubilisation is minimized by limiting the microwave treatment to a maximum of 6000 kJ/kg TS during the second part of the experiments. Monitoring the degradation of acetic acid after a low intensity microwave treatment, reveals that microwave irradiation shortens the lag phase, e.g., from 21 to 3 h after a microwave treatment of 1000 kJ/kg TS at 100 W. However most treatments also result in a decrease of the maximum degradation and of the degradation rate of acetic acid. BMP assays are performed to evaluate the activity and performance of the entire anaerobic community. Every treatment results in a decreased biogas production potential and decreased biogas production rate. Moreover, each treatment induced an increase of the lag phase. The SMA experiments show no influence of the microwave irradiation in terms of biogas or methane production. Copyright © 2017 Elsevier Ltd. All rights reserved.

Physical limits to biochemical signaling

NASA Astrophysics Data System (ADS)

Bialek, William; Setayeshgar, Sima

2005-07-01

Many crucial biological processes operate with surprisingly small numbers of molecules, and there is renewed interest in analyzing the impact of noise associated with these small numbers. Twenty-five years ago, Berg and Purcell showed that bacterial chemotaxis, where a single-celled organism must respond to small changes in concentration of chemicals outside the cell, is limited directly by molecule counting noise and that aspects of the bacteria's behavioral and computational strategies must be chosen to minimize the effects of this noise. Here, we revisit and generalize their arguments to estimate the physical limits to signaling processes within the cell and argue that recent experiments are consistent with performance approaching these limits. Author contributions: W.B. and S.S. designed research, performed research, and wrote the paper.†Present address: Department of Physics, Indiana University, Bloomington, IN 47405.

The Effect of Class Session Length on Student Performance, Homework, and Instructor Evaluations in an Introductory Accounting Course

ERIC Educational Resources Information Center

Trout, Brian

2018-01-01

The author examines the effect of class format on student performance, time spent on homework, and instructor evaluations. The findings are unique and add to a limited body of literature. Each group comprised similar undergraduate students who received the same number of instructional hours, same assignments and were taught by the same instructor.…

Probabilistic Approaches to Examining Linguistic Features of Test Items and Their Effect on the Performance of English Language Learners

ERIC Educational Resources Information Center

Solano-Flores, Guillermo

2014-01-01

This article addresses validity and fairness in the testing of English language learners (ELLs)--students in the United States who are developing English as a second language. It discusses limitations of current approaches to examining the linguistic features of items and their effect on the performance of ELL students. The article submits that…

Debriefing after simulation-based non-technical skill training in healthcare: a systematic review of effective practice.

PubMed

Garden, A L; Le Fevre, D M; Waddington, H L; Weller, J M

2015-05-01

Non-technical skills training in healthcare frequently uses high-fidelity simulation followed by a facilitated discussion known as debriefing. This type of training is mandatory for anaesthesia training in Australia and New Zealand. Debriefing by a skilled facilitator is thought to be essential for new learning through feedback and reflective processes. Key elements of effective debriefing need to be clearly identified to ensure that the training is evidence-based. We undertook a systematic review of empirical studies where elements of debriefing have been systematically manipulated during non-technical skills training. Eight publications met the inclusion criteria, but seven of these were of limited generalisability. The only study that was generalisable found that debriefing by novice instructors using a script improved team leader performance in paediatric resuscitation. The remaining seven publications were limited by the small number of debriefers included in each study and these reports were thus analogous to case reports. Generally, performance improved after debriefing by a skilled facilitator. However, the debriefer provided no specific advantage over other post-experience educational interventions. Acknowledging their limitations, these studies found that performance improved after self-led debrief, no debrief (with experienced practitioners), standardised multimedia debrief or after reviewing a DVD of the participants' own eye-tracking. There was no added performance improvement when review of a video recording was added to facilitator-led debriefing. One study reported no performance improvement after debriefing. Without empirical evidence that is specific to the healthcare domain, theories of learning from education and psychology should continue to inform practices and teaching for effective debriefing.

Team performance in networked supervisory control of unmanned air vehicles: effects of automation, working memory, and communication content.

PubMed

McKendrick, Ryan; Shaw, Tyler; de Visser, Ewart; Saqer, Haneen; Kidwell, Brian; Parasuraman, Raja

2014-05-01

Assess team performance within a net-worked supervisory control setting while manipulating automated decision aids and monitoring team communication and working memory ability. Networked systems such as multi-unmanned air vehicle (UAV) supervision have complex properties that make prediction of human-system performance difficult. Automated decision aid can provide valuable information to operators, individual abilities can limit or facilitate team performance, and team communication patterns can alter how effectively individuals work together. We hypothesized that reliable automation, higher working memory capacity, and increased communication rates of task-relevant information would offset performance decrements attributed to high task load. Two-person teams performed a simulated air defense task with two levels of task load and three levels of automated aid reliability. Teams communicated and received decision aid messages via chat window text messages. Task Load x Automation effects were significant across all performance measures. Reliable automation limited the decline in team performance with increasing task load. Average team spatial working memory was a stronger predictor than other measures of team working memory. Frequency of team rapport and enemy location communications positively related to team performance, and word count was negatively related to team performance. Reliable decision aiding mitigated team performance decline during increased task load during multi-UAV supervisory control. Team spatial working memory, communication of spatial information, and team rapport predicted team success. An automated decision aid can improve team performance under high task load. Assessment of spatial working memory and the communication of task-relevant information can help in operator and team selection in supervisory control systems.

Laser diode technology for coherent communications

NASA Technical Reports Server (NTRS)

Channin, D. J.; Palfrey, S. L.; Toda, M.

1989-01-01

The effect of diode laser characteristics on the overall performance capabilities of coherent communication systems is discussed. In particular, attention is given to optical performance issues for diode lasers in coherent systems, measurements of key performance parameters, and optical requirements for coherent single-channel and multichannel communication systems. The discussion also covers limitations imposed by diode laser optical performance on multichannel system capabilities and implications for future developments.

Objective Work-Nonwork Conflict: From Incompatible Demands to Decreased Work Role Performance

ERIC Educational Resources Information Center

Haun, Sascha; Steinmetz, Holger; Dormann, Christian

2011-01-01

Research on work-nonwork conflict (WNC) is based on the assumption that incompatible demands from the work and the nonwork domain hamper role performance. This assumption implies that role demands from both domains interact in predicting role performance, but research has been largely limited to main effects. In this multi-source study, we analyze…

Effect of laser frequency noise on fiber-optic frequency reference distribution

NASA Technical Reports Server (NTRS)

Logan, R. T., Jr.; Lutes, G. F.; Maleki, L.

1989-01-01

The effect of the linewidth of a single longitude-mode laser on the frequency stability of a frequency reference transmitted over a single-mode optical fiber is analyzed. The interaction of the random laser frequency deviations with the dispersion of the optical fiber is considered to determine theoretically the effect on the Allan deviation (square root of the Allan variance) of the transmitted frequency reference. It is shown that the magnitude of this effect may determine the limit of the ultimate stability possible for frequency reference transmission on optical fiber, but is not a serious limitation to present system performance.

Noise analysis for near-field 3D FM-CW radar imaging systems

NASA Astrophysics Data System (ADS)

Sheen, David M.

2015-05-01

Near field radar imaging systems are used for demanding security applications including concealed weapon detection in airports and other high-security venues. Despite the near-field operation, phase noise and thermal noise can limit performance in several ways. Practical imaging systems can employ arrays with low gain antennas and relatively large signal distribution networks that have substantial losses which limit transmit power and increase the effective noise figure of the receiver chain, resulting in substantial thermal noise. Phase noise can also limit system performance. The signal coupled from transmitter to receiver is much larger than expected target signals. Phase noise from this coupled signal can set the system noise floor if the oscillator is too noisy. Frequency modulated continuous wave (FM-CW) radar transceivers used in short range systems are relatively immune to the effects of the coupled phase noise due to range correlation effects. This effect can reduce the phase-noise floor such that it is below the thermal noise floor for moderate performance oscillators. Phase noise is also manifested in the range response around bright targets, and can cause smaller targets to be obscured. Noise in synthetic aperture imaging systems is mitigated by the processing gain of the system. In this paper, the effects of thermal noise, phase noise, and processing gain are analyzed in the context of a near field 3-D FM-CW imaging radar as might be used for concealed weapon detection. In addition to traditional frequency domain analysis, a time-domain simulation is employed to graphically demonstrate the effect of these noise sources on a fast-chirping FM-CW system.

22 CFR 96.2 - Definitions.

Code of Federal Regulations, 2011 CFR

2011-04-01

... means a social work professional or organization that performs a home study on prospective adoptive..., but not limited to, photographs, videos, correspondence, personal effects, medical and social... of parental rights and to adoption; (3) Performing a background study on a child or a home study on a...

22 CFR 96.2 - Definitions.

Code of Federal Regulations, 2010 CFR

2010-04-01

... means a social work professional or organization that performs a home study on prospective adoptive..., but not limited to, photographs, videos, correspondence, personal effects, medical and social... of parental rights and to adoption; (3) Performing a background study on a child or a home study on a...

22 CFR 96.2 - Definitions.

Code of Federal Regulations, 2014 CFR

2014-04-01

... means a social work professional or organization that performs a home study on prospective adoptive..., but not limited to, photographs, videos, correspondence, personal effects, medical and social... of parental rights and to adoption; (3) Performing a background study on a child or a home study on a...

22 CFR 96.2 - Definitions.

Code of Federal Regulations, 2013 CFR

2013-04-01

... means a social work professional or organization that performs a home study on prospective adoptive..., but not limited to, photographs, videos, correspondence, personal effects, medical and social... of parental rights and to adoption; (3) Performing a background study on a child or a home study on a...

Performance-Based Measurement: Action for Organizations and HPT Accountability

ERIC Educational Resources Information Center

Larbi-Apau, Josephine A.; Moseley, James L.

2010-01-01

Basic measurements and applications of six selected general but critical operational performance-based indicators--effectiveness, efficiency, productivity, profitability, return on investment, and benefit-cost ratio--are presented. With each measurement, goals and potential impact are explored. Errors, risks, limitations to measurements, and a…

Effect of limit feeding and genomic residual feed intake on bred dairy heifer performance

USDA-ARS?s Scientific Manuscript database

The objective of this study was to evaluate growth, intake, and feed efficiency of dairy heifers with different predicted genomic residual feed intakes as lactating cows (RFI) offered diets for ad-libitum intake or limit-fed. Post-bred Holstein heifers (128, ages 14-20 months), were blocked by initi...

Issues of Teacher Performance Stability Are Not New: Limitations and Possibilities

ERIC Educational Resources Information Center

Good, Thomas L.; Lavigne, Alyson L.

2015-01-01

Morgan, Hodge, Trepinski, and Anderson (2014) have written an article that continues to confirm what we have known for some time-teacher effects on student achievement have limited stability. In this commentary, we address the other potential contributions this work can make to inform practice, policy, and research. While illustrating Morgan et…

Bristol Ridge: A 28-nm $$\\times$$ 86 Performance-Enhanced Microprocessor Through System Power Management

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

Sundaram, Sriram; Grenat, Aaron; Naffziger, Samuel

Power management techniques can be effective at extracting more performance and energy efficiency out of mature systems on chip (SoCs). For instance, the peak performance of microprocessors is often limited by worst case technology (Vmax), infrastructure (thermal/electrical), and microprocessor usage assumptions. Performance/watt of microprocessors also typically suffers from guard bands associated with the test and binning processes as well as worst case aging/lifetime degradation. Similarly, on multicore processors, shared voltage rails tend to limit the peak performance achievable in low thread count workloads. In this paper, we describe five power management techniques that maximize the per-part performance under the before-mentionedmore » constraints. Using these techniques, we demonstrate a net performance increase of up to 15% depending on the application and TDP of the SoC, implemented on 'Bristol Ridge,' a 28-nm CMOS, dual-core x 86 accelerated processing unit.« less

Extensive but not Limited Repeated Trials in Passive Avoidance Task Induce Stress-like Symptoms and Affect Memory Function in Rats.

PubMed

Tabassum, Saiqa; Haider, Saida

2018-02-10

Stressful and emotionally arousing experiences are remembered, and previous reports show that repeated exposure to stressful condition enhances emotional learning. However, the usefulness of the repeated exposure depends on the intensity and duration. Although repeated training as a strategy to improve memory performance is receiving increased attention from researchers, repeated training may induce stressful effects that have not yet been considered. The present study investigated whether exposure to repetitive learning trials with limited or extensive durations in a passive avoidance task (PAT) would be beneficial or harmful to emotional memory performance in rats. Rats were exposed to repetitive learning trials for two different durations in the limited exposure (exposure to four repetitive trials) and extensive exposure groups (exposure to 16 repetitive trials) in a single day to compare the impact of both conditions on rat emotional memory performance. Alterations in corticosterone content and associated oxidative and neurochemical systems were assessed to explore the underlying mechanism responsible for changes in emotional memory. Following extensive exposure, a negative impact on emotional memory was observed compared with the limited exposure group. A lack of any further improvement in memory function following extensive training exposure was supported by increased corticosterone levels, decreased 5-hydroxytryptamine (5-HT) levels and abnormal oxidative stress levels, which may induce negative effects on memory consolidation. It is suggested that limited exposure to repetitive learning trials is more useful for studying improvement in emotional memory, whereas extensive exposure may produce chronic stress-like condition that can be detrimental and responsible for compromised memory performance. Copyright © 2017 IBRO. Published by Elsevier Ltd. All rights reserved.

Designing healthcare information technology to catalyse change in clinical care.

PubMed

Lester, William T; Zai, Adrian H; Grant, Richard W; Chueh, Henry C

2008-01-01

The gap between best practice and actual patient care continues to be a pervasive problem in our healthcare system. Efforts to improve on this knowledge-performance gap have included computerised disease management programs designed to improve guideline adherence. However, current computerised reminder and decision support interventions directed at changing physician behaviour have had only a limited and variable effect on clinical outcomes. Further, immediate pay-for-performance financial pressures on institutions have created an environment where disease management systems are often created under duress, appended to existing clinical systems and poorly integrated into the existing workflow, potentially limiting their real-world effectiveness. The authors present a review of disease management as well as a conceptual framework to guide the development of more effective health information technology (HIT) tools for translating clinical information into clinical action.

Reproduction Alters Hydration State but Does Not Impact the Positive Effects of Dehydration on Innate Immune Function in Children's Pythons (Antaresia childreni).

PubMed

Brusch, George A; Billy, Gopal; Blattman, Joseph N; DeNardo, Dale F

Resource availability can impact immune function, with the majority of studies of such influences focusing on the allocation of energy investment into immune versus other physiological functions. When energy is a limited resource, performance trade-offs can result, compromising immunity. Dehydration is also considered a physiological challenge resulting from the limitation of a vital resource, yet previous research has found a positive relationship between dehydration and innate immune performance. However, these studies did not examine the effects of dehydration on immunity when there was another concurrent, substantial physiological challenge. Thus, we examined the impact of reproduction and water deprivation, individually and in combination, on immune performance in Children's pythons (Antaresia childreni). We collected blood samples from free-ranging A. childreni to evaluate osmolality and innate immune function (lysis, agglutination, bacterial growth inhibition) during the austral dry season, when water availability is limited and this species is typically reproducing. To examine how reproduction and water imbalance, both separately and combined, impact immune function, we used a laboratory-based 2 × 2 experiment. Our results demonstrate that A. childreni experience significant dehydration during the dry season and that, overall, osmolality, regardless of the underlying cause (seasonal rainfall, water deprivation, or reproduction), is positively correlated with increased innate immune performance.

Hollow cathode plasma coupling study, 1986

NASA Technical Reports Server (NTRS)

Wilbur, Paul J.

1986-01-01

The electron collection and emission characteristics of a simple hollow cathode contactor, an extended anode hollow cathode contactor supplied by JSC, and a ring cusp magnetic field contactor are presented and the effects of discharge power and argon or xenon expellant flowrate on these characteristics are examined. All of the contactors are shown to exhibit good electron emission performance over a wide range of discharge power and expellant type and flowrate. Good electron performance is shown to be more difficult to achieve. Results suggest that the extended anode and ring cusp contactors should perform satisfactorily to electron emission currents beyond 1000 mA and electron collection currents beyond 500 mA. All contactors performed better on xenon than argon. A general theory of plasma contactor operation in both the electron collection and electron emission modes, which describes the current-limiting effects of space-charge phenomena is given. This current-limiting and collecting phenomenon is shown to be a function of driving potential differences and emitting and collecting surface radius ratio for the case of a spherical geometry. Discharge power did not appear to influence the electron collection current substantially in the experiments so it is suggested in light of the model that the contactors are generally not limited by their ion production capabilities under conditions at which they were tested.

Effects of liquid chromatography mobile phases and buffer salts on phosphorus inductively coupled plasma atomic emission and mass spectrometries utilizing ultrasonic nebulization and membrane desolvation.

PubMed

Carr, John E; Kwok, Kaho; Webster, Gregory K; Carnahan, Jon W

2006-01-23

Atomic spectrometry, specifically inductively coupled plasma atomic emission spectrometry (ICP-AES) and mass spectrometry (ICP-MS) show promise for heteroatom-based detection of pharmaceutical compounds. The combination of ultrasonic nebulization (USN) with membrane desolvation (MD) greatly enhances detection limits with these approaches. Because pharmaceutical analyses often incorporate liquid chromatography, the study herein was performed to examine the effects of solvent composition on the analytical behaviors of these approaches. The target analyte was phosphorus, introduced as phosphomycin. AES response was examined at the 253.7 nm atom line and mass 31 ions were monitored for the MS experiments. With pure aqueous solutions, detection limits of 5 ppb (0.5 ng in 0.1 mL injection volumes) were obtained with ICP-MS. The ICP-AES detection limit was 150 ppb. Solvent compositions were varied from 0 to 80% organic (acetonitrile and methanol) with nine buffers at concentrations typically used in liquid chromatography. In general, solvents and buffers had statistically significant, albeit small, effects on ICP-AES sensitivities. A few exceptions occurred in cases where typical liquid chromatography buffer concentrations produced higher mass loadings on the plasma. Indications are that isocratic separations can be reliably performed. Within reasonable accuracy tolerances, it appears that gradient chromatography can be performed without the need for signal response normalization. Organic solvent and buffer effects were more significant with ICP-MS. Sensitivities varied significantly with different buffers and organic solvent content. In these cases, gradient chromatography will require careful analytical calibration as solvent and buffer content is varied. However, for most buffer and solvent combinations, signal and detection limits are only moderately affected. Isocratic separations and detection are feasible.

Collective Effects in a Diffraction Limited Storage Ring

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

Nagaoka, Ryutaro; Bane, Karl L.F.

Our paper gives an overview of collective effects that are likely to appear and possibly limit the performance in a diffraction-limited storage ring (DLSR) that stores a high-intensity ultra-low-emittance beam. Beam instabilities and other intensity-dependent effects that may significantly impact the machine performance are covered. The latter include beam-induced machine heating, Touschek scattering, intra-beam scattering, as well as incoherent tune shifts. The general trend that the efforts to achieve ultra-low emittance result in increasing the machine coupling impedance and the beam sensitivity to instability is reviewed. The nature of coupling impedance in a DLSR is described, followed by a seriesmore » of potentially dangerous beam instabilities driven by the former, such as resistive-wall, TMCI (transverse mode coupling instability), head-tail and microwave instabilities. Additionally, beam-ion and CSR (coherent synchrotron radiation) instabilities are also treated. Means to fight against collective effects such as lengthening of the bunch with passive harmonic cavities and bunch-by-bunch transverse feedback are introduced. Numerical codes developed and used to evaluate the machine coupling impedance, as well as to simulate beam instability using the former as inputs are described.« less

Collective Effects in a Diffraction Limited Storage Ring

DOE PAGES

Nagaoka, Ryutaro; Bane, Karl L.F.

2015-10-20

Our paper gives an overview of collective effects that are likely to appear and possibly limit the performance in a diffraction-limited storage ring (DLSR) that stores a high-intensity ultra-low-emittance beam. Beam instabilities and other intensity-dependent effects that may significantly impact the machine performance are covered. The latter include beam-induced machine heating, Touschek scattering, intra-beam scattering, as well as incoherent tune shifts. The general trend that the efforts to achieve ultra-low emittance result in increasing the machine coupling impedance and the beam sensitivity to instability is reviewed. The nature of coupling impedance in a DLSR is described, followed by a seriesmore » of potentially dangerous beam instabilities driven by the former, such as resistive-wall, TMCI (transverse mode coupling instability), head-tail and microwave instabilities. Additionally, beam-ion and CSR (coherent synchrotron radiation) instabilities are also treated. Means to fight against collective effects such as lengthening of the bunch with passive harmonic cavities and bunch-by-bunch transverse feedback are introduced. Numerical codes developed and used to evaluate the machine coupling impedance, as well as to simulate beam instability using the former as inputs are described.« less

Effect of P.G. 600 on rebreeding performance in sows limit-fed during lactation.

PubMed

Estienne, Mark J; Harper, Allen F; Horsley, B Ryan

2006-03-01

The objective was to determine whether treatment with 400 IU PMSG and 200 IU hCG (P.G. 600; Intervet America, Inc., Millsboro, DE, USA) at weaning improved rebreeding performance in sows that were limit-fed during lactation. Crossbred sows were allowed ad libitum access to feed or were limited to 3.2 kg of feed/day during an 18-day lactation. At weaning, limit-fed sows received im treatment with P.G. 600 (n = 16) or saline (n = 19) and ad libitum-fed sows received saline (n = 18). The percentage of sows in estrus by day 7 post-weaning was greater (p<0.05), and the weaning-to-estrus interval was shorter (p<0.05), for ad libitum-fed sows compared to limit-fed, saline-treated sows, with limit-fed, P.G. 600-treated sows having intermediate values that were not different from the other two groups. The percentage of sows pregnant and the numbers of corpora lutea and embryos at day 30 post-mating were not different (p>0.1) among groups. In summary, low feed intake during lactation decreased the percentage of sows that displayed estrus within 7 days after weaning and increased the weaning-to-estrus interval. These effects were at least partially remediated by gonadotropin treatment. Pregnancy rate, and litter size at day 30 of gestation, were similar for ad libitum- and limit-fed sows and not affected by P.G. 600 treatment in limit-fed sows.

Optical Vector Receiver Operating Near the Quantum Limit

NASA Astrophysics Data System (ADS)

Vilnrotter, V. A.; Lau, C.-W.

2005-05-01

An optical receiver concept for binary signals with performance approaching the quantum limit at low average-signal energies is developed and analyzed. A conditionally nulling receiver that reaches the quantum limit in the absence of background photons has been devised by Dolinar. However, this receiver requires ideal optical combining and complicated real-time shaping of the local field; hence, it tends to be difficult to implement at high data rates. A simpler nulling receiver that approaches the quantum limit without complex optical processing, suitable for high-rate operation, had been suggested earlier by Kennedy. Here we formulate a vector receiver concept that incorporates the Kennedy receiver with a physical beamsplitter, but it also utilizes the reflected signal component to improve signal detection. It is found that augmenting the Kennedy receiver with classical coherent detection at the auxiliary beamsplitter output, and optimally processing the vector observations, always improves on the performance of the Kennedy receiver alone, significantly so at low average-photon rates. This is precisely the region of operation where modern codes approach channel capacity. It is also shown that the addition of background radiation has little effect on the performance of the coherent receiver component, suggesting a viable approach for near-quantum-limited performance in high background environments.

Design of coated standing nanowire array solar cell performing beyond the planar efficiency limits

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

Zeng, Yang; Ye, Qinghao; Shen, Wenzhong, E-mail: wzshen@sjtu.edu.cn

2016-05-28

The single standing nanowire (SNW) solar cells have been proven to perform beyond the planar efficiency limits in both open-circuit voltage and internal quantum efficiency due to the built-in concentration and the shifting of the absorption front. However, the expandability of these nano-scale units to a macro-scale photovoltaic device remains unsolved. The main difficulty lies in the simultaneous preservation of an effective built-in concentration in each unit cell and a broadband high absorption capability of their array. Here, we have provided a detailed theoretical guideline for realizing a macro-scale solar cell that performs furthest beyond the planar limits. The keymore » lies in a complementary design between the light-trapping of the single SNWs and that of the photonic crystal slab formed by the array. By tuning the hybrid HE modes of the SNWs through the thickness of a coaxial dielectric coating, the optimized coated SNW array can sustain an absorption rate over 97.5% for a period as large as 425 nm, which, together with the inherited carrier extraction advantage, leads to a cell efficiency increment of 30% over the planar limit. This work has demonstrated the viability of a large-size solar cell that performs beyond the planar limits.« less

The spacing effect in intentional and incidental free recall by children and adults: Limits on the automaticity hypothesis.

PubMed

Toppino, Thomas C; Fearnow-Kenney, Melodie D; Kiepert, Marissa H; Teremula, Amanda C

2009-04-01

Preschoolers, elementary school children, and college students exhibited a spacing effect in the free recall of pictures when learning was intentional. When learning was incidental and a shallow processing task requiring little semantic processing was used during list presentation, young adults still exhibited a spacing effect, but children consistently failed to do so. Children, however, did manifest a spacing effect in incidental learning when an elaborate semantic processing task was used. These results limit the hypothesis that the spacing effect in free recall occurs automatically and constrain theoretical accounts of why the spacing between repetitions affects recall performance.

Transforming cold chain performance and management in lower-income countries.

PubMed

Brison, Mike; LeTallec, Yann

2017-04-19

In many countries, one of the common factors limiting full and equitable access to effective immunization is the existence of gaps in cold chain and logistics (CCL) systems. This article focuses on the critical contribution that better management of CCL performance can make in addressing these barriers, as well as some essential practices needed to achieve and sustain these gains. These include (i) an emphasis on continuous improvement in CCL performance indicators, (ii) strong coordination and accountability across multiple stakeholders, and (iii) making the most of limited financial resources. This article is informed by the Clinton Health Access Initiative's (CHAI's) experience working with National Immunization Programs (NIPs) and immunization partners to improve the effectiveness and efficiency of CCL systems (including CCE deployment and maintenance, temperature monitoring and control, stock management and distribution) across ten Gavi-supported "focus" countries. Copyright © 2016 The Authors. Published by Elsevier Ltd.. All rights reserved.

Computer controlled performance mapping of thermionic converters: effect of collector, guard-ring potential imbalances on the observed collector current-density, voltage characteristics and limited range performance map of an etched-rhenium, niobium planar converter

NASA Technical Reports Server (NTRS)

Manista, E. J.

1972-01-01

The effect of collector, guard-ring potential imbalance on the observed collector-current-density J, collector-to-emitter voltage V characteristic was evaluated in a planar, fixed-space, guard-ringed thermionic converter. The J,V characteristic was swept in a period of 15 msec by a variable load. A computerized data acquisition system recorded test parameters. The results indicate minimal distortion of the J,V curve in the power output quadrant for the nominal guard-ring circuit configuration. Considerable distortion, along with a lowering of the ignited-mode striking voltage, was observed for the configuration with the emitter shorted to the guard ring. A limited-range performance map of an etched-rhenium, niobium, planar converter was obtained by using an improved computer program for the data acquisition system.

Effects of competitive pressure on expert performance: underlying psychological, physiological, and kinematic mechanisms.

PubMed

Cooke, Andrew; Kavussanu, Maria; McIntyre, David; Boardley, Ian D; Ring, Christopher

2011-08-01

Although it is well established that performance is influenced by competitive pressure, our understanding of the mechanisms which underlie the pressure-performance relationship is limited. The current experiment examined mediators of the relationship between competitive pressure and motor skill performance of experts. Psychological, physiological, and kinematic responses to three levels of competitive pressure were measured in 50 expert golfers, during a golf putting task. Elevated competitive pressure increased putting accuracy, anxiety, effort, and heart rate, but decreased grip force. Quadratic effects of pressure were noted for self-reported conscious processing and impact velocity. Mediation analyses revealed that effort and heart rate partially mediated improved performance. The findings indicate that competitive pressure elicits effects on expert performance through both psychological and physiological pathways. Copyright © 2011 Society for Psychophysiological Research.

Effect of air velocity on laying hen performance and egg quality

USDA-ARS?s Scientific Manuscript database

Increasing convective cooling can improve performance and thermal comfort of commercial poultry when weather or system design limit cooling through other means such as evaporative cooling. Previous work in young hens showed increased egg production rate as feed intake is maintained under heat stres...

Some design considerations for solar-powered aircraft

NASA Technical Reports Server (NTRS)

Phillips, W. H.

1980-01-01

Performance and operating characteristics are presented for a solar powered aircraft intended to remain aloft for long periods. The critical technologies which limit the performance are identified. By using the techniques presented, the effects of variation in the system parameters are studied. Practical design consideration are discussed.

A non-linear steady state characteristic performance curve for medium temperature solar energy collectors

NASA Astrophysics Data System (ADS)

Eames, P. C.; Norton, B.

A numerical simulation model was employed to investigate the effects of ambient temperature and insolation on the efficiency of compound parabolic concentrating solar energy collectors. The limitations of presently-used collector performance characterization curves were investigated and a new approach proposed.

Physical Performance Limitations in Adolescent and Adult Survivors of Childhood Cancer and Their Siblings

PubMed Central

Rueegg, Corina S.; Michel, Gisela; Wengenroth, Laura; von der Weid, Nicolas X.; Bergstraesser, Eva; Kuehni, Claudia E.; Ammann, R.; Angst, R.; Beck Popovic, M.; Bergstraesser, E.; Brazzola, P.; Caflisch, U.; Greiner, J.; Grotzer, M.; Hengartner, H.; Kühne, T.; Leibundgut, K.; Niggli, F.; Nobile Buetti, L.; Ozsahin, H.; Paulussen, M.; Rischewski, J.; von der Weid, N.

2012-01-01

Purpose This study investigates physical performance limitations for sports and daily activities in recently diagnosed childhood cancer survivors and siblings. Methods The Swiss Childhood Cancer Survivor Study sent a questionnaire to all survivors (≥16 years) registered in the Swiss Childhood Cancer Registry, who survived >5 years and were diagnosed 1976–2003 aged <16 years. Siblings received similar questionnaires. We assessed two types of physical performance limitations: 1) limitations in sports; 2) limitations in daily activities (using SF-36 physical function score). We compared results between survivors diagnosed before and after 1990 and determined predictors for both types of limitations by multivariable logistic regression. Results The sample included 1038 survivors and 534 siblings. Overall, 96 survivors (9.5%) and 7 siblings (1.1%) reported a limitation in sports (Odds ratio 5.5, 95%CI 2.9-10.4, p<0.001), mainly caused by musculoskeletal and neurological problems. Findings were even more pronounced for children diagnosed more recently (OR 4.8, CI 2.4–9.6 and 8.3, CI 3.7–18.8 for those diagnosed <1990 and ≥1990, respectively; p = 0.025). Mean physical function score for limitations in daily activities was 49.6 (CI 48.9–50.4) in survivors and 53.1 (CI 52.5–53.7) in siblings (p<0.001). Again, differences tended to be larger in children diagnosed more recently. Survivors of bone tumors, CNS tumors and retinoblastoma and children treated with radiotherapy were most strongly affected. Conclusion Survivors of childhood cancer, even those diagnosed recently and treated with modern protocols, remain at high risk for physical performance limitations. Treatment and follow-up care should include tailored interventions to mitigate these late effects in high-risk patients. PMID:23082232

Brilliant Blue G double staining enhances successful internal limiting membrane peeling with minimal adverse effect by low cellular permeability into live cells.

PubMed

Hisatomi, Toshio; Notomi, Shoji; Tachibana, Takashi; Oishi, Seiichiro; Asato, Ryo; Yamashita, Takehiro; Murakami, Yusuke; Ikeda, Yasuhiro; Enaida, Hiroshi; Sakamoto, Taiji; Ishibashi, Tatsuro

2015-02-01

Brilliant Blue G is used as a surgical adjuvant for retinal surgery. Although BBG double or multiple staining was reported, the effectiveness and safety of repeated staining is still elusive. To further examine the effectiveness and safety, we examined BBG in clinical cases in vivo, primary cell culture in vitro, and surgically resected specimen ex vivo. A retrospective interventional case series with in vitro and ex vivo studies were performed. Vitrectomy was performed in 28 cases of epiretinal membrane with BBG single to multiple staining. The surgically resected membranes were stained by BBG with or without cellular fixation. Primary cell cultures were examined with BBG and live/death cell markers, such as Calcein AM and TUNEL. Single staining provided satisfactory staining in seven cases. Double or multiple staining substantially visualized internal limiting membrane (21 cases), especially the edges of remaining internal limiting membrane (11 cases). Adverse retinal staining was not noted and the final visual acuity showed no difference with multiple staining. The live cells barely stained with BBG, while some dead cells were stained. Brilliant Blue G multiple staining substantially enhanced the visualization of internal limiting membrane. The absence of abnormal staining supports the safety of repeated BBG staining.

CHRONIC ZINC SCREENING WATER EFFECT RATIO FOR THE H-12 OUTFALL, SAVANNAH RIVER SITE

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

Coughlin, D.; Looney, B.; Millings, M.

2009-01-13

In response to proposed Zn limits for the NPDES outfall H-12, a Zn screening Water Effects Ratio (WER) study was conducted to determine if a full site-specific WER is warranted. Using standard assumptions for relating the lab results to the stream, the screening WER data were consistent with the proposed Zn limit and suggest that a full WER would result in a similar limit. Addition of a humate amendment to the outfall water reduced Zn toxicity, but the toxicity reduction was relatively small and unlikely to impact proposed Zn limits. The screening WER data indicated that the time and expensemore » required to perform a full WER for Zn is not warranted.« less

Performance evaluation of parallel electric field tunnel field-effect transistor by a distributed-element circuit model

NASA Astrophysics Data System (ADS)

Morita, Yukinori; Mori, Takahiro; Migita, Shinji; Mizubayashi, Wataru; Tanabe, Akihito; Fukuda, Koichi; Matsukawa, Takashi; Endo, Kazuhiko; O'uchi, Shin-ichi; Liu, Yongxun; Masahara, Meishoku; Ota, Hiroyuki

2014-12-01

The performance of parallel electric field tunnel field-effect transistors (TFETs), in which band-to-band tunneling (BTBT) was initiated in-line to the gate electric field was evaluated. The TFET was fabricated by inserting an epitaxially-grown parallel-plate tunnel capacitor between heavily doped source wells and gate insulators. Analysis using a distributed-element circuit model indicated there should be a limit of the drain current caused by the self-voltage-drop effect in the ultrathin channel layer.

SU-C-BRD-03: Analysis of Accelerator Generated Text Logs for Preemptive Maintenance

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

Able, CM; Baydush, AH; Nguyen, C

2014-06-15

Purpose: To develop a model to analyze medical accelerator generated parameter and performance data that will provide an early warning of performance degradation and impending component failure. Methods: A robust 6 MV VMAT quality assurance treatment delivery was used to test the constancy of accelerator performance. The generated text log files were decoded and analyzed using statistical process control (SPC) methodology. The text file data is a single snapshot of energy specific and overall systems parameters. A total of 36 system parameters were monitored which include RF generation, electron gun control, energy control, beam uniformity control, DC voltage generation, andmore » cooling systems. The parameters were analyzed using Individual and Moving Range (I/MR) charts. The chart limits were calculated using a hybrid technique that included the use of the standard 3σ limits and the parameter/system specification. Synthetic errors/changes were introduced to determine the initial effectiveness of I/MR charts in detecting relevant changes in operating parameters. The magnitude of the synthetic errors/changes was based on: the value of 1 standard deviation from the mean operating parameter of 483 TB systems, a small fraction (≤ 5%) of the operating range, or a fraction of the minor fault deviation. Results: There were 34 parameters in which synthetic errors were introduced. There were 2 parameters (radial position steering coil, and positive 24V DC) in which the errors did not exceed the limit of the I/MR chart. The I chart limit was exceeded for all of the remaining parameters (94.2%). The MR chart limit was exceeded in 29 of the 32 parameters (85.3%) in which the I chart limit was exceeded. Conclusion: Statistical process control I/MR evaluation of text log file parameters may be effective in providing an early warning of performance degradation or component failure for digital medical accelerator systems. Research is Supported by Varian Medical Systems, Inc.« less

Reliability analysis of degradable networks with modified BPR

NASA Astrophysics Data System (ADS)

Wang, Yu-Qing; Zhou, Chao-Fan; Jia, Bin; Zhu, Hua-Bing

2017-12-01

In this paper, the effect of the speed limit on degradable networks with capacity restrictions and the forced flow is investigated. The link performance function considering the road capacity is proposed. Additionally, the probability density distribution and the cumulative distribution of link travel time are introduced in the degradable network. By the mean of distinguishing the value of the speed limit, four cases are discussed, respectively. Means and variances of link travel time and route one of the degradable road network are calculated. Besides, by the mean of performing numerical simulation experiments in a specific network, it is found that the speed limit strategy can reduce the travel time budget and mean travel time of link and route. Moreover, it reveals that the speed limit strategy can cut down variances of the travel time of networks to some extent.

The Effect of Stress on Self-Reported Academic Performance Measures among Hispanic Undergraduate Students at Arizona State University

ERIC Educational Resources Information Center

Moses, Karen S.

2012-01-01

Research on the impact of stress on the academic performance of Hispanic undergraduate students is limited, leaving institutions of higher education without needed information about how to better support this growing population of students. The purpose of this study was to identify stressors that have a negative impact on academic performance of…

The effect of incomplete fuel-air mixing on the lean blowout limit, lean stability limit and NO(x) emissions in lean premixed gas turbine combustors

NASA Technical Reports Server (NTRS)

Shih, W.-P.; Lee, J. G.; Santavicca, D. A.

1994-01-01

Gas turbine engines for both land-based and aircraft propulsion applications are facing regulations on NOx emissions which cannot be met with current combustor technology. A number of alternative combustor strategies are being investigated which have the potential capability of achieving ultra-low NOx emissions, including lean premixed combustors, direct injection combustors, rich burn-quick quench-lean burn combustors and catalytic combustors. The research reported in this paper addresses the effect of incomplete fuel-air mixing on the lean limit performance and the NOx emissions characteristics of lean premixed combustors.

[The relationship between ischemic preconditioning-induced infarction size limitation and duration of test myocardial ischemia].

PubMed

Blokhin, I O; Galagudza, M M; Vlasov, T D; Nifontov, E M; Petrishchev, N N

2008-07-01

Traditionally infarction size reduction by ischemic preconditioning is estimated in duration of test ischemia. This approach limits the understanding of real antiischemic efficacy of ischemic preconditioning. Present study was performed in the in vivo rat model of regional myocardial ischemia-reperfusion and showed that protective effect afforded by ischemic preconditioning progressively decreased with prolongation of test ischemia. There were no statistically significant differences in infarction size between control and preconditioned animals when the duration of test ischemia was increased up to 1 hour. Preconditioning ensured maximal infarction-limiting effect in duration of test ischemia varying from 20 to 40 minutes.

3D Simulations of Void collapse in Energetic Materials

NASA Astrophysics Data System (ADS)

Rai, Nirmal Kumar; Udaykumar, H. S.

2017-06-01

Voids present in the microstructure of heterogeneous energetic materials effect the sensitivity towards ignition. It is established that the morphology of voids can play a significant role in sensitivity enhancement of energetic materials. Depending on the void shape, sensitivity can be either increased or decreased under given loading conditions. In the past, effects of different void shapes i.e. triangular, ellipse, cylindrical etc. on the sensitivity of energetic materials have been analyzed. However, most of these studies are performed in 2D and are limited under the plain strain assumption. Axisymmetric studies have also been performed in the past to incorporate the 3D effects, however axisymmetric modeling is limited to only certain geometries i.e. sphere. This work analyzes the effects of various void shapes in three dimensions on the ignition behavior of HMX. Various void shapes are analyzed including spherical, prolate and oblate speheroid oriented at different orientations, etc. Three dimensional void collapse simulations are performed on a single void to quantify the effects void morphology on initiation. A Cartesian grid based Eulerian solver SCIMITAR3D is used to perform the void collapse simulations. Various aspects of void morphology i.e. size, thickness of voids, elongation, orientation etc. are considered to obtain a comprehensive analysis. Also, 2D plane strain calculations are compared with the three dimensional analysis to evaluate the salient differences between 2D and 3D modeling.

Heterogeneous Mixtures as NLO Christiansen Filters for Optical Limiting

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

Exarhos, Gregory J.; Ferris, Kim F.; Samuels, William D.

Mixtures of two non-absorbing and index-matched materials with contrasting nonlinear optical response have been shown to optically limit above a critical fluence of pulsed nanosecond laser light. Under these conditions, index mismatch is induced between the disparate phases leading to strong Tyndall scattering. The effect has been demonstrated previously by the authors in both solid-liquid mixtures (hexadecane and calcium fluoride), and surfactant-stabilized liquid-liquid emulsions consisting of dichloroethane as the organic phase and a concentrated aqueous phase of sodium thiocyanate (NaSCN). Materials used in these studies exhibit low absorption coefficients over extended wavelength regions allowing for a broadband response of themore » limiter. Recently, limiting has been observed at 532 nm in a polymer composite consisting of barium fluoride and poly-(n-butyl acrylate). A modified open-aperture z-scan method was used to quantify optical limiter performance in this system. Modeling studies provide the basis for designing optical limiters based upon this light scattering mechanism and show the importance of size resonance and constituent optical properties on limiter performance.« less

Perspective: A new model of leadership performance in health care.

PubMed

Souba, Wiley

2011-10-01

Current leadership models are based largely on concepts and explanations, which provide limited access to the being and actions of an effective leader in health care. Rather than teaching leadership from a theoretical vantage point, the ontological perspective teaches leadership as it is lived and experienced. When one exercises leadership "as lived," concurrently informed by theories, one performs at one's best. A distinctive feature of the ontological approach resides in its capacity to disclose human ways of being and acting that limit our freedom to lead effectively as our natural self-expression. Ontological leadership maintains that our worldviews and mental maps affect the way we lead and are shaped by and accessible through language--hence, to lead more effectively, mastery of a new conversational domain of leadership is required. This emerging model of leadership performance reveals that (1) our actions as leaders are correlated with the way in which the leadership situation we are dealing with occurs for us, and (2) this "occurring" is shaped by the context we bring to that situation. Master leaders use language to recontextualize their leadership challenges so that their naturally correlated ways of being and acting can emerge, resulting in effective leadership. When leaders linguistically unveil limiting contexts, they are freed up to create new contexts that shift the way leadership challenges occur for them. This provides leaders--physicians, scientists, educators, executives--with new opportunity sets (previously unavailable) for exercising exemplary leadership. The ontological approach to leadership offers a powerful framework for tackling health care's toughest challenges.

The Effect of a Microprocessor Prosthetic Foot on Function and Quality of Life in Transtibial Amputees Who Are Limited Community Ambulators

DTIC Science & Technology

with greater range of motion and active power, will translate into improved functional performance, ambulatory safety (risk of falls) and quality of... life in trans-tibial amputees (TTA) who function as limited community ambulators. We will assess these outcomes in 54 veterans with TTA by randomizing

Effect of volume of milk consumed on the attenuation of exercise-induced muscle damage.

PubMed

Cockburn, Emma; Robson-Ansley, Paula; Hayes, Philip R; Stevenson, Emma

2012-09-01

Exercise-induced muscle damage (EIMD) leads to decrements in muscle performance, increases in intramuscular proteins and delayed-onset of muscle soreness (DOMS). Previous research demonstrated that one litre of milk-based protein-carbohydrate (CHO) consumed immediately following muscle damaging exercise can limit changes in markers of EIMD possibly due to attenuating protein degradation and/or increasing protein synthesis. If the attenuation of EIMD is derived from changes in protein metabolism then it can be hypothesised that consuming a smaller volume of CHO and protein will elicit similar effects. Three independent matched groups of 8 males consumed 500 mL of milk, 1,000 mL of milk or a placebo immediately following muscle damaging exercise. Passive and active DOMS, isokinetic muscle performance, creatine kinase (CK), myoglobin and interleukin-6 were assessed immediately before and 24, 48 and 72 h after EIMD. After 72 h 1,000 mL of milk had a likely benefit for limiting decrements in peak torque compared to the placebo. After 48 h, 1,000 mL of milk had a very likely benefit of limiting increases in CK in comparison to the placebo. There were no differences between consuming 500 or 1,000 mL of milk for changes in peak torque and CK. In conclusion, decrements in isokinetic muscle performance and increases in CK can be limited with the consumption of 500 mL of milk.

Takeoff certification considerations for large subsonic and supersonic transport airplanes using the Ames flight simulator for advanced aircraft

NASA Technical Reports Server (NTRS)

Snyder, C. T.; Drinkwater, F. J., III; Fry, E. B.; Forrest, R. D.

1973-01-01

Data for use in development of takeoff airworthiness standards for new aircraft designs such as the supersonic transport (SST) and the large wide-body subsonic jet transport are provided. An advanced motion simulator was used to compare the performance and handling characteristics of three representative large jet transports during specific flight certification tasks. Existing regulatory constraints and methods for determining rotation speed were reviewed, and the effects on takeoff performance of variations in rotation speed, pitch attitude, and pitch attitude rate during the rotation maneuver were analyzed. A limited quantity of refused takeoff information was obtained. The aerodynamics, wing loading, and thrust-to-weight ratio of the subject SST resulted in takeoff speeds limited by climb (rather than lift-off) considerations. Take-off speeds based on U.S. subsonic transport requirements were found unacceptable because of the criticality of rotation-abuse effects on one-engine-inoperative climb performance. Adequate safety margin was provided by takeoff speeds based on proposed Anglo-French supersonic transport (TSS) criteria, with the limiting criterion being that takeoff safety speed be at least 1.15 times the one-engine-inoperative zero-rate-of-climb speed. Various observations related to SST certification are presented.

Intelligent transportation systems field operational test cross-cutting study incident management : detection, verification, and traffic management

DOT National Transportation Integrated Search

2000-01-01

Although the effects of climatic factors on pavement performance have long been recognized as important, those effects remain largely unquantified because individual pavement research projects to date generally have been restricted to limited geograp...

Beliefs about willpower moderate the effect of previous day demands on next day’s expectations and effective goal striving

PubMed Central

Bernecker, Katharina; Job, Veronika

2015-01-01

Research suggests that beliefs about willpower affect self-regulation following previous self-regulatory demands (Job et al., 2010). Some people believe that their willpower is limited, meaning that after a demanding task it needs to be replenished (limited theory). By contrast, others believe that willpower is not limited and that previous self-control tasks even activate willpower (non-limited theory). We hypothesized that when people experience a demanding day their beliefs about willpower predict their expected capacity to self-regulate and their actual self-regulation on the following day. In a daily diary study (N = 157), we measured students’ daily level of demands, their expected performance in unpleasant tasks, and their effective goal striving. Results showed that following a demanding day, students with a non-limited theory had higher expectations about their progress in unpleasant tasks and were striving more efficiently for their goals than students with a limited theory. These findings suggest that beliefs about willpower affect whether demands experienced on a previous day have positive or negative consequences on people’s self-regulation. PMID:26528198

Some characteristics of the international space channel

NASA Technical Reports Server (NTRS)

Noack, T. L.; Poland, W. B., Jr.

1975-01-01

Some physical characteristics of radio transmission links and the technology of PCM modulation combine with the Radio Regulations of the International Telecommunications Union to define a communications channel having a determinable channel capacity, error rate, and sensitivity to interference. These characteristics and the corresponding limitations on EIRP, power flux density, and power spectral density for space service applications are described. The ITU regulations create a critical height of 1027 km where some parameters of the limitation rules change. The nature of restraints on power spectral density are discussed and an approach to a standardized representation of Necessary Bandwidth for the Space Services is described. It is shown that, given the PFD (power flux density) and PSD (power spectral density) limitations of radio regulations, the channel performance is determined by the ratio of effective receiving antenna aperture to system noise temperature. Based on this approach, the method for a quantitative trade-off between spectrum spreading and system performance is presented. Finally, the effects of radio frequency interference between standard systems is analyzed.

Pollen limitation and Allee effect related to population size and sex ratio in the endangered Ottelia acuminata (Hydrocharitaceae): implications for conservation and reintroduction.

PubMed

Xia, J; Lu, J; Wang, Z X; Hao, B B; Wang, H B; Liu, G H

2013-03-01

Small populations may suffer more severe pollen limitation and result in Allee effects. Sex ratio may also affect pollination and reproduction success in dioecious species, which is always overlooked when performing conservation and reintroduction tasks. In this study, we investigated whether and how population size and sex ratio affected pollen limitation and reproduction in the endangered Ottelia acuminata, a dioecious submerged species. We established experimental plots with increasing population size and male sex ratio. We observed insect visitation, estimated pollen limitation by hand-pollinations and counted fruit set and seed production per fruit. Fruit set and seed production decreased significantly in small populations due to pollinator scarcity and thus suffered more severe pollen limitation. Although frequently visited, female-biased larger populations also suffered severe pollen limitation due to few effective visits and insufficient pollen availability. Rising male ratio enhanced pollination service and hence reproduction. Unexpectedly, pollinator preferences did not cause reduced reproduction in male-biased populations because of high pollen availability. However, reproductive outputs showed more variability in severe male-biased populations. Our results revealed two component Allee effects in fruit set and seed production, mediated by pollen limitation in O. acuminata. Moreover, reproduction decreased significantly in larger female-biased populations, increasing the risk of an Allee effect. © 2012 German Botanical Society and The Royal Botanical Society of the Netherlands.

Adaptation to heat and exercise performance under cooler conditions: a new hot topic.

PubMed

Corbett, Jo; Neal, Rebecca A; Lunt, Heather C; Tipton, Michael J

2014-10-01

Chronic exposure to a stressor elicits adaptations enhancing the tolerance to that stressor. These adaptive responses might also improve tolerance under less stressful conditions. For example, historically there has been much interest in the adaptive responses to high-altitude, or hypoxia, and their ergogenic potential under sea-level, or normoxic, conditions. In contrast, the influence of the adaptive responses to heat on exercise under cooler conditions has received relatively little interest. Heat acclimation/acclimatization (HA) is known to increase work capacity in hot environments. Yet, aerobic exercise performance can progressively deteriorate as ambient temperature increases beyond ~10 °C, indicating a thermal limitation even under relatively cool conditions. The improved thermoregulatory capability induced by HA might attenuate this thermal decrement in a manner similar to that seen when exposed to hotter temperatures. Moreover, the suite of adaptations elicited by HA has the potential to increase maximal oxygen uptake, lactate threshold and economy, and thus may be ergogenic even under conditions where performance is not thermally limited. Indeed, evidence is now emerging to support an ergogenic effect of HA but the number of studies is limited and in some instances lack appropriate control, are confounded by methodological limitations, or do not address the mechanisms of action. Nevertheless, these tantalising insights into the ergogenic potential of heat will likely generate considerable interest in this new 'hot topic'. Future research will need to employ well-designed studies to clarify the exercise conditions under which ergogenic effects of HA are apparent, to elucidate the precise mechanisms, and to optimise HA strategies for performance.

The effect of coworker knowledge sharing on performance and its boundary conditions: an interactional perspective.

PubMed

Kim, Seckyoung Loretta; Yun, Seokhwa

2015-03-01

Considering the importance of coworkers and knowledge sharing in current business environment, this study intends to advance understanding by investigating the effect of coworker knowledge sharing on focal employees' task performance. Furthermore, by taking an interactional perspective, this study examines the boundary conditions of coworker knowledge sharing on task performance. Data from 149 samples indicate that there is a positive relationship between coworker knowledge sharing and task performance, and this relationship is strengthened when general self-efficacy or abusive supervision is low rather than high. Our findings suggest that the recipients' characteristics and leaders' behaviors could be important contingent factors that limit the effect of coworker knowledge sharing on task performance. Implications for theory and practice are discussed. PsycINFO Database Record (c) 2015 APA, all rights reserved.

Choosing the Most Effective Pattern Classification Model under Learning-Time Constraint.

PubMed

Saito, Priscila T M; Nakamura, Rodrigo Y M; Amorim, Willian P; Papa, João P; de Rezende, Pedro J; Falcão, Alexandre X

2015-01-01

Nowadays, large datasets are common and demand faster and more effective pattern analysis techniques. However, methodologies to compare classifiers usually do not take into account the learning-time constraints required by applications. This work presents a methodology to compare classifiers with respect to their ability to learn from classification errors on a large learning set, within a given time limit. Faster techniques may acquire more training samples, but only when they are more effective will they achieve higher performance on unseen testing sets. We demonstrate this result using several techniques, multiple datasets, and typical learning-time limits required by applications.

Scaling of graphene field-effect transistors supported on hexagonal boron nitride: radio-frequency stability as a limiting factor

NASA Astrophysics Data System (ADS)

Feijoo, Pedro C.; Pasadas, Francisco; Iglesias, José M.; Martín, María J.; Rengel, Raúl; Li, Changfeng; Kim, Wonjae; Riikonen, Juha; Lipsanen, Harri; Jiménez, David

2017-12-01

The quality of graphene in nanodevices has increased hugely thanks to the use of hexagonal boron nitride as a supporting layer. This paper studies to which extent hBN together with channel length scaling can be exploited in graphene field-effect transistors (GFETs) to get a competitive radio-frequency (RF) performance. Carrier mobility and saturation velocity were obtained from an ensemble Monte Carlo simulator that accounted for the relevant scattering mechanisms (intrinsic phonons, scattering with impurities and defects, etc). This information is fed into a self-consistent simulator, which solves the drift-diffusion equation coupled with the two-dimensional Poisson’s equation to take full account of short channel effects. Simulated GFET characteristics were benchmarked against experimental data from our fabricated devices. Our simulations show that scalability is supposed to bring to RF performance an improvement that is, however, highly limited by instability. Despite the possibility of a lower performance, a careful choice of the bias point can avoid instability. Nevertheless, maximum oscillation frequencies are still achievable in the THz region for channel lengths of a few hundreds of nanometers.

Numerical study of metal oxide hetero-junction solar cells with defects and interface states

NASA Astrophysics Data System (ADS)

Zhu, Le; Shao, Guosheng; Luo, J. K.

2013-05-01

Further to our previous work on ideal metal oxide (MO) hetero-junction solar cells, a systematic simulation has been carried out to investigate the effects of defects and interface states on the cells. Two structures of the window/absorber (WA) and window/absorber/voltage-enhancer (WAV) were modelled with defect concentration, defect energy level, interface state (ISt) density and ISt energy level as parameters. The simulation showed that the defects in the window layer and the voltage-enhancer layer have very limited effects on the performance of the cells, but those in the absorption layer have profound effects on the cell performance. The interface states at the W/A interface have a limited effect on the performance even for a density up to 1013 cm-2, while those at the A/V interface cause the solar cell to deteriorate severely even at a low density of lower than 1 × 1011 cm-2. It also showed that the back surface field (BSF) induced by band gap off-set in the WAV structure loses its function when defects with a modest concentration exist in the absorption layer and does not improve the open voltage at all.

Work support, psychological well-being and safety performance among nurses in Hong Kong.

PubMed

Wong, Kenchi C K

2018-02-06

This study investigated the mediating role of psychological well-being between work support and safety performance of 314 Hong Kong nurses, using self-reported questionnaires. Results showed that psychological well-being mediated the effects of work support on safety performance. The findings illustrate that work support was an important element to improve psychological well-being. This could generate better safety performance of the nurses. Implications and limitations are discussed.

Simulated Seasonal Photoperiods and Fluctuating Temperatures Have Limited Effects on Blood Feeding and Life History in Aedes triseriatus (Diptera: Culicidae)

PubMed Central

Westby, K. M.

2015-01-01

Biotic and abiotic factors change seasonally and impact life history in temperate-zone ectotherms. Temperature and photoperiod are factors that change in predictable ways. Most studies testing for effects of temperature on vectors use constant temperatures and ignore potential correlated effects of photoperiod. In two experiments, we tested for effects of larval rearing environments creating ecologically relevant temperatures and photoperiods simulating early and late season conditions (June and August), or constant temperatures (cool and warm) with the June or August photoperiods, respectively. We determined effects on survivorship, development, size, and a composite performance index in a temperate-zone population of Aedes triseriatus (Say). We followed cohorts of resulting females, all held under the same environmental conditions, to assess carry-over effects of rearing conditions for larvae on longevity, blood feeding, and egg production. Larval survivorship was affected by treatment in one experiment. Development time was greater in the June and cool treatments, but the constant and fluctuating temperatures did not differ. Significantly larger mosquitoes were produced in fluctuating versus constant temperature treatments. There were no significant treatment effects on the composite performance index. Adult female longevity was lower after rearing at constant versus fluctuating temperature, but there was no difference between June and August, nor did size affect longevity. There was no effect of treatments on blood feeding and a limited effect on egg production. We conclude that seasonal temperatures and photoperiods during development have limited effects on this population of A. triseriatus and find little evidence of strong effects of fluctuating versus constant temperatures. PMID:26336255

Measurement of the Behavioural, Cognitive, and Motivational Factors Underlying Team Performance

DTIC Science & Technology

2007-06-01

shown to posses high internal consistency (Cronbach’s alphas of .91 and .89, respectively). 5.4 Applications and Conclusions The research reviewed...measurement of the variables underlying effective team performance is fundamental to both team training and team training research , as it enables the...team performance and the ways in which these variables have been operationalised and measured in the research literature. RELEASE LIMITATION

The Academic Performance of Catholic Schools.

ERIC Educational Resources Information Center

Morris, Andrew B.

1994-01-01

Although the (British) government's "league tables" may be an inappropriate method of comparing schools' relative effectiveness, analysis of the 1992 examination results points to Catholic schools' apparent success. A summary of the limited research evidence on Catholic school effectiveness suggests that a rigorous study of their…

Advances in SAW gas sensors based on the condensate-adsorption effect.

PubMed

Liu, Jiuling; Wang, Wen; Li, Shunzhou; Liu, Minghua; He, Shitang

2011-01-01

A surface-acoustic-wave (SAW) gas sensor with a low detection limit and fast response for volatile organic compounds (VOCs) based on the condensate-adsorption effect detection is developed. In this sensor a gas chromatography (GC) column acts as the separator element and a dual-resonator oscillator acts as the detector element. Regarding the surface effective permittivity method, the response mechanism analysis, which relates the condensate-adsorption effect, is performed, leading to the sensor performance prediction prior to fabrication. New designs of SAW resonators, which act as feedback of the oscillator, are devised in order to decrease the insertion loss and to achieve single-mode control, resulting in superior frequency stability of the oscillator. Based on the new phase modulation approach, excellent short-term frequency stability (±3 Hz/s) is achieved with the SAW oscillator by using the 500 MHz dual-port resonator as feedback element. In a sensor experiment investigating formaldehyde detection, the implemented SAW gas sensor exhibits an excellent threshold detection limit as low as 0.38 pg.

Local oscillator induced degradation of medium-term stability in passive atomic frequency standards

NASA Technical Reports Server (NTRS)

Dick, G. John; Prestage, John D.; Greenhall, Charles A.; Maleki, Lute

1990-01-01

As the performance of passive atomic frequency standards improves, a new limitation is encountered due to frequency fluctuations in an ancillary local oscillator (L.O.). The effect is due to time variation in the gain of the feedback which compensates L.O. frequency fluctuations. The high performance promised by new microwave and optical trapped ion standards may be severely compromised by this effect. Researchers present an analysis of this performance limitation for the case of sequentially interrogated standards. The time dependence of the sensitivity of the interrogation process to L.O. frequency fluctuations is evaluated for single-pulse and double-pulse Ramsey RF interrogation and for amplitude modulated pulses. The effect of these various time dependencies on performance of the standard is calculated for an L.O. with frequency fluctuations showing a typical 1/f spectral density. A limiting 1/sq. root gamma dependent deviation of frequency fluctuations is calculated as a function of pulse lengths, dead time, and pulse overlap. Researchers also present conceptual and hardware-oriented solutions to this problem which achieve a much more nearly constant sensitivity to L.O. fluctuations. Solutions involve use of double-pulse interrogation; alternate interrogation of multiple traps so that the dead time of one trap can be covered by operation of the other; and the use of double-pulse interrogation for two traps, so that during the time of the RF pulses, the increasing sensitivity of one trap tends to compensate for the decreasing sensitivity of the other. A solution making use of amplified-modulated pulses is also presented which shows nominally zero time variation.

Does greater thermal plasticity facilitate range expansion of an invasive terrestrial anuran into higher latitudes?

PubMed

Winwood-Smith, Hugh S; Alton, Lesley A; Franklin, Craig E; White, Craig R

2015-01-01

Temperature has pervasive effects on physiological processes and is critical in setting species distribution limits. Since invading Australia, cane toads have spread rapidly across low latitudes, but slowly into higher latitudes. Low temperature is the likely factor limiting high-latitude advancement. Several previous attempts have been made to predict future cane toad distributions in Australia, but understanding the potential contribution of phenotypic plasticity and adaptation to future range expansion remains challenging. Previous research demonstrates the considerable thermal metabolic plasticity of the cane toad, but suggests limited thermal plasticity of locomotor performance. Additionally, the oxygen-limited thermal tolerance hypothesis predicts that reduced aerobic scope sets thermal limits for ectotherm performance. Metabolic plasticity, locomotor performance and aerobic scope are therefore predicted targets of natural selection as cane toads invade colder regions. We measured these traits at temperatures of 10, 15, 22.5 and 30°C in low- and high-latitude toads acclimated to 15 and 30°C, to test the hypothesis that cane toads have adapted to cooler temperatures. High-latitude toads show increased metabolic plasticity and higher resting metabolic rates at lower temperatures. Burst locomotor performance was worse for high-latitude toads. Other traits showed no regional differences. We conclude that increased metabolic plasticity may facilitate invasion into higher latitudes by maintaining critical physiological functions at lower temperatures.

Local performance optimization for a class of redundant eight-degree-of-freedom manipulators

NASA Technical Reports Server (NTRS)

Williams, Robert L., II

1994-01-01

Local performance optimization for joint limit avoidance and manipulability maximization (singularity avoidance) is obtained by using the Jacobian matrix pseudoinverse and by projecting the gradient of an objective function into the Jacobian null space. Real-time redundancy optimization control is achieved for an eight-joint redundant manipulator having a three-axis spherical shoulder, a single elbow joint, and a four-axis spherical wrist. Symbolic solutions are used for both full-Jacobian and wrist-partitioned pseudoinverses, partitioned null-space projection matrices, and all objective function gradients. A kinematic limitation of this class of manipulators and the limitation's effect on redundancy resolution are discussed. Results obtained with graphical simulation are presented to demonstrate the effectiveness of local redundant manipulator performance optimization. Actual hardware experiments performed to verify the simulated results are also discussed. A major result is that the partitioned solution is desirable because of low computation requirements. The partitioned solution is suboptimal compared with the full solution because translational and rotational terms are optimized separately; however, the results show that the difference is not significant. Singularity analysis reveals that no algorithmic singularities exist for the partitioned solution. The partitioned and full solutions share the same physical manipulator singular conditions. When compared with the full solution, the partitioned solution is shown to be ill-conditioned in smaller neighborhoods of the shared singularities.

An improved low-voltage ride-through performance of DFIG based wind plant using stator dynamic composite fault current limiter.

PubMed

Gayen, P K; Chatterjee, D; Goswami, S K

2016-05-01

In this paper, an enhanced low-voltage ride-through (LVRT) performance of a grid connected doubly fed induction generator (DFIG) has been presented with the usage of stator dynamic composite fault current limiter (SDCFCL). This protection circuit comprises of a suitable series resistor-inductor combination and parallel bidirectional semiconductor switch. The SDCFCL facilitates double benefits such as reduction of rotor induced open circuit voltage due to increased value of stator total inductance and concurrent increase of rotor impedance. Both effects will limit rotor circuit over current and over voltage situation more secured way in comparison to the conventional scheme like the dynamic rotor current limiter (RCL) during any type of fault situation. The proposed concept is validated through the simulation study of the grid integrated 2.0MW DFIG. Copyright © 2016 ISA. Published by Elsevier Ltd. All rights reserved.

What's All the Noise? Differentiating Dimensions of Acoustic Stress and the Limits to Meta-Analysis: Reply to Smith (2012)

ERIC Educational Resources Information Center

Szalma, J. L.; Hancock, P. A.

2012-01-01

Smith (2012) has provided pertinent observations on our recently published meta-analytic review (Szalma & Hancock, 2011) of the effects of acoustic noise on performance. His main points are as follows: (a) our review excluded some areas of research; (b) there were conceptual problems with our moderator analyses; and (c) limitations to…

Limited English Proficiency, Race/Ethnicity and Socio-Economic Status as Influences on Scores in Large-Scale Assessments

ERIC Educational Resources Information Center

Terwilliger, James S.; Magnuson, Paul

2005-01-01

The purpose of this study was to examine the effects of three basic demographic variables on reading test scores for students in the middle elementary grades. Limited English proficiency (LEP), race/ethnicity and socio-economic status (SES) were studied to determine their influence individually and in combination on performance in large-scale…

Medication and finance management among HIV-infected adults: the impact of age and cognition.

PubMed

Thames, April D; Kim, Michelle S; Becker, Brian W; Foley, Jessica M; Hines, Lindsay J; Singer, Elyse J; Heaton, Robert K; Castellon, Steven A; Hinkin, Charles H

2011-02-01

This study examined the effects of aging and cognitive impairment on medication and finance management in an HIV sample. We observed main effects of age (older < younger) and neuropsychological impairment on functional task performance. Interactions between age and cognition demonstrated that older impaired individuals performed significantly more poorly than all other comparison groups. There were no relationships between laboratory performance and self-reported medication and finance management. The interaction of advancing age and cognitive impairment may confer significant functional limitations for HIV individuals that may be better detected by performance-based measures of functional abilities rather than patient self-report.

Medication and finance management among HIV-infected adults: The impact of age and cognition

PubMed Central

Thames, April D.; Kim, Michelle S.; Becker, Brian W.; Foley, Jessica M.; Hines, Lindsay J.; Singer, Elyse J.; Heaton, Robert K.; Castellon, Steven A.; Hinkin, Charles H.

2013-01-01

This study examined the effects of aging and cognitive impairment on medication and finance management in an HIV sample. We observed main effects of age (older < younger) and neuropsychological impairment on functional task performance. Interactions between age and cognition demonstrated that older impaired individuals performed significantly more poorly than all other comparison groups. There were no relationships between laboratory performance and self-reported medication and finance management. The interaction of advancing age and cognitive impairment may confer significant functional limitations for HIV individuals that may be better detected by performance-based measures of functional abilities rather than patient self-report. PMID:20694873

Major Management Challenges and Program Risks, Department of Education. Performance and Accountability Series.

ERIC Educational Resources Information Center

Comptroller General of the U.S., Washington, DC.

This report addresses the major performance and management challenges that have limited the effectiveness of the Department of Education in carrying out its mission. The booklet addresses corrective actions that Education has taken or initiated on these challenges--including a number of management initiatives to improve controls over the…

The Effect of Glycerol Ingestion on Performance during Simulated Multisport Activity

ERIC Educational Resources Information Center

Knight, Christopher; Braakhuis, Andrea; Paton, Carl

2010-01-01

Glycerol-induced hyperhydration has been applied to endurance sport with limited success as a performance enhancement strategy. Glycerol has been used as a hyperhydrating agent, because it has been shown to be rapidly absorbed and osmotically active; therefore, the fluid intake with glycerol is distributed throughout the body. Hyperhydration with…

Enhancing Learning in Africa through Students' Collaboration with Parents, Teachers and Peers

ERIC Educational Resources Information Center

Maganda, Dainess

2016-01-01

Education scholars agree on the positive role that parents play in fostering educational success. Much research done also shows ways in which teachers contribute greatly to students' performance in school. Limited research focuses on how students' interactions with one another effect their academic performance. This study examines ways in which…

The Best Laid Plans: Pay for Performance Incentive Programs for School Leaders

ERIC Educational Resources Information Center

Goff, Peter; Goldring, Ellen; Canney, Melissa

2016-01-01

In an era of heightened accountability and limited fiscal resources, school districts have sought novel ways to increase the effectiveness of their principals in an effort to increase student proficiency. To address these needs, some districts have turned to pay-for-performance programs, aligning leadership goals with financial incentives to…

Effect of the Use of Instructional Anatomy Videos on Student Performance

ERIC Educational Resources Information Center

Saxena, Varun; Natarajan, Pradeep; O'Sullivan, Patricia S.; Jain, Sharad

2008-01-01

Medical schools have reduced the time allotted to anatomy instruction. Consequently, schools engage students in more independent settings using information and communication technologies (ICT). There has been limited research in the use of video aids, a type of ICT, to enhance anatomy examination performance. The objective of this study is to…

Water hammer effect in the spiral case and penstock of Francis turbines

NASA Astrophysics Data System (ADS)

Pepa, D.; Ursoniu, C.; Gillich, R. N.; Campian, C. V.

2017-01-01

Sudden pressure increases in the penstock or spiral case of a hydraulic turbine are the effect of sudden flow variation that occur during transient processes of type opening / closing or load rejection of the hydro unit. The consequence of the pressure rise in the spiral case and penstock is the water hammer phenomenon, whose effects can be devastating in some cases, up to breaking pipes and calamities produced in the area. This paper aims to analyze the method of calculation of the maximum pressure values that might occur in load rejection situations to a hydraulic turbine, in spiral case and in penstock, conditioned by the limiting of the values of the over speed and measures of limiting the increase in pressure in conjunction with limiting the increase in speed in these specific processes. As an example, we studied and analyzed the situation of a hydroelectric power plant equipped with a 7.8 MW Francis turbine without pressure regulator and the inflow surge. The results of analytical calculation overlaid on the experimental measurements performed during the performance tests of the hydro unit lead to the conclusion that the calculation algorithm proposed has been chosen correctly and the 2-stage closing law of the wicket gate promoted in this case is effective in such situations.

Cathode limited charge transport and performance of thin-film rechargeable lithium batteries

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

Bates, J.B.; Hart, F.X.; Lubben, D.

1994-11-01

Several types of thin-film rechargeable batteries based on lithium metal anodes and amorphous V{sub 2}O{sub 5} (aV{sub 2}O{sub 5}), LiMn{sub 2}O{sub 4}, and LiCoO{sub 2} cathodes have been investigated in this laboratory. In all cases, the current density of these cells is limited by lithium ion transport in the cathodes. This paper, discusses sources of this impedance in Li-aV{sub 2}O{sub 5} and Li-LiMn{sub 2}O{sub 4} thin-film cells and their effect on cell performance.

Accuracy and Radiation Dose Reduction of Limited-Range CT in the Evaluation of Acute Appendicitis in Pediatric Patients.

PubMed

Jin, Michael; Sanchez, Thomas R; Lamba, Ramit; Fananapazir, Ghaneh; Corwin, Michael T

2017-09-01

The purpose of this article is to determine the accuracy and radiation dose reduction of limited-range CT prescribed from the top of L2 to the top of the pubic symphysis in children with suspected acute appendicitis. We performed a retrospective study of 210 consecutive pediatric patients from December 11, 2012, through December 11, 2014, who underwent abdominopelvic CT for suspected acute appendicitis. Two radiologists independently reviewed the theoretic limited scans from the superior L2 vertebral body to the top of the pubic symphysis, to assess for visualization of the appendix, acute appendicitis, alternative diagnoses, and incidental findings. Separately, the same parameters were assessed on the full scan by the same two reviewers. Whole-body effective doses were determined for the full- and limited-range scans and were compared using the paired t test. The appendix or entire cecum was visualized on the limited scan in all cases, and no cases of acute appendicitis were missed on the simulated limited scan compared with the full scan. Two alternative diagnoses were missed with the limited scan: one case of hydronephrosis and one of acute acalculous cholecystitis. The mean effective dose for the original scan was 5.6 mSv and that for the simulated limited scan was 3.0 mSv, resulting in a dose reduction of 46.4% (p < 0.001). A limited-range CT examination performed from the top of L2 to the top of the pubic symphysis is as accurate as a full-range abdominopelvic CT in evaluating pediatric patients with suspected appendicitis and reduces the dose by approximately 46%.

14 CFR 135.398 - Commuter category airplanes performance operating limitations.

Code of Federal Regulations, 2011 CFR

2011-01-01

... all commuter category airplanes notwithstanding their stated applicability to turbine-engine-powered... used, the elevation of the airport, the effective runway gradient, and ambient temperature, and wind...

14 CFR 135.398 - Commuter category airplanes performance operating limitations.

Code of Federal Regulations, 2010 CFR

2010-01-01

... all commuter category airplanes notwithstanding their stated applicability to turbine-engine-powered... used, the elevation of the airport, the effective runway gradient, and ambient temperature, and wind...

A speed limit compliance model for dynamic speed display sign.

PubMed

Ardeshiri, Anam; Jeihani, Mansoureh

2014-12-01

Violating speed limits is a major cause of motor vehicle crashes. Various techniques have been adopted to ensure that posted speed limits are obeyed by drivers. This study investigates the effect of dynamic speed display signs (DSDSs) on drivers' compliance with posted speed limit. An extensive speed data collection upstream of, adjacent to, and downstream of DSDS locations on multiple road classes with different speed limits (25, 35, and 45 mph) was performed short-term and long-term after DSDS installation. Conventional statistical analysis, regression models, and a Bayesian network were developed to assess the DSDS's effectiveness. General compliance with speed limit (upstream of the DSDS location), time of day, day of week, duration of DSDS operation, and distance from the DSDS location were significantly correlated with speed limit compliance adjacent to the DSDS. While compliance with the speed limit due to the DSDS increased by 5%, speed reduction occurred in 40% of the cases. Since drivers were likely to increase their speed after passing the DSDS, it should be installed on critical points supplemented with enforcement. Copyright © 2014 Elsevier Ltd. All rights reserved.

How jet lag impairs Major League Baseball performance.

PubMed

Song, Alex; Severini, Thomas; Allada, Ravi

2017-02-07

Laboratory studies have demonstrated that circadian clocks align physiology and behavior to 24-h environmental cycles. Examination of athletic performance has been used to discern the functions of these clocks in humans outside of controlled settings. Here, we examined the effects of jet lag, that is, travel that shifts the alignment of 24-h environmental cycles relative to the endogenous circadian clock, on specific performance metrics in Major League Baseball. Accounting for potential differences in home and away performance, travel direction, and team confounding variables, we observed that jet-lag effects were largely evident after eastward travel with very limited effects after westward travel, consistent with the >24-h period length of the human circadian clock. Surprisingly, we found that jet lag impaired major parameters of home-team offensive performance, for example, slugging percentage, but did not similarly affect away-team offensive performance. On the other hand, jet lag impacted both home and away defensive performance. Remarkably, the vast majority of these effects for both home and away teams could be explained by a single measure, home runs allowed. Rather than uniform effects, these results reveal surprisingly specific effects of circadian misalignment on athletic performance under natural conditions.

How jet lag impairs Major League Baseball performance

PubMed Central

Song, Alex; Severini, Thomas; Allada, Ravi

2017-01-01

Laboratory studies have demonstrated that circadian clocks align physiology and behavior to 24-h environmental cycles. Examination of athletic performance has been used to discern the functions of these clocks in humans outside of controlled settings. Here, we examined the effects of jet lag, that is, travel that shifts the alignment of 24-h environmental cycles relative to the endogenous circadian clock, on specific performance metrics in Major League Baseball. Accounting for potential differences in home and away performance, travel direction, and team confounding variables, we observed that jet-lag effects were largely evident after eastward travel with very limited effects after westward travel, consistent with the >24-h period length of the human circadian clock. Surprisingly, we found that jet lag impaired major parameters of home-team offensive performance, for example, slugging percentage, but did not similarly affect away-team offensive performance. On the other hand, jet lag impacted both home and away defensive performance. Remarkably, the vast majority of these effects for both home and away teams could be explained by a single measure, home runs allowed. Rather than uniform effects, these results reveal surprisingly specific effects of circadian misalignment on athletic performance under natural conditions. PMID:28115724

Chip-integrated optical power limiter based on an all-passive micro-ring resonator

NASA Astrophysics Data System (ADS)

Yan, Siqi; Dong, Jianji; Zheng, Aoling; Zhang, Xinliang

2014-10-01

Recent progress in silicon nanophotonics has dramatically advanced the possible realization of large-scale on-chip optical interconnects integration. Adopting photons as information carriers can break the performance bottleneck of electronic integrated circuit such as serious thermal losses and poor process rates. However, in integrated photonics circuits, few reported work can impose an upper limit of optical power therefore prevent the optical device from harm caused by high power. In this study, we experimentally demonstrate a feasible integrated scheme based on a single all-passive micro-ring resonator to realize the optical power limitation which has a similar function of current limiting circuit in electronics. Besides, we analyze the performance of optical power limiter at various signal bit rates. The results show that the proposed device can limit the signal power effectively at a bit rate up to 20 Gbit/s without deteriorating the signal. Meanwhile, this ultra-compact silicon device can be completely compatible with the electronic technology (typically complementary metal-oxide semiconductor technology), which may pave the way of very large scale integrated photonic circuits for all-optical information processors and artificial intelligence systems.

Effects of a Novel Cooling Shirt on Various Physical Performance Parameters in Elite Athletes

DTIC Science & Technology

2015-06-03

operations and sport matches. The primary purpose of this short-term field observation was to determine the effects of a technical cooling shirt and...limit these individuals’ ability to sustain and satisfactorily continue a high level of performance required during intense ground operations and sport ...specially cut-to-size cryotherapy material in place. The subjects were then counter-balanced, with half of the subjects “loaded” with the cooling material

The time dependence of the effect of ischemic preconditioning on successive sprint swimming performance.

PubMed

Lisbôa, Felipe D; Turnes, Tiago; Cruz, Rogério S O; Raimundo, João A G; Pereira, Gustavo S; Caputo, Fabrizio

2017-05-01

The present study aimed to determine the effects of ischemic preconditioning on performance in three successive 50-m swimming trials and to measure stroke rate, stroke length and blood lactate accumulation. Counterbalanced, repeated-measures cross-over study. On two separate days, eleven competitive male swimmers (20±3 years, 182±5cm, 77±5kg) performed three successive 50-m trials in a 50-m swimming pool, preceded by intermittent bilateral cuff inflation (4× 5-min of blood flow restriction+5-min of cuff deflation) at either 220 for thighs and 180mmHg for arms (ischemic preconditioning) or 20mmHg for both limbs (control-treatment). The 50-m trials were conducted 1-, 2-, and 8-h after the procedure. While no ergogenic effect of ischemic preconditioning was observed for 1-h (0.4%, 95% confidence limits of ±0.6%, p=0.215), there were clear beneficial effects of ischemic preconditioning on 2- and 8-h (1.0% and 1.2%, respectively; 95% confidence limits of ±0.6% in both cases, p≤0.002). Furthermore, ischemic preconditioning increased blood lactate accumulation in 2-(p<0.001) and 8-h (p=0.010) and stroke rate for 2- and 8-h in specific 10-m segments (p<0.05). These findings suggest a time-dependent effect of ischemic preconditioning on 50-m swimming performance for competitive athletes, with the time window of the beneficial effect starting after about 2-h and lasting for at least 8-h after ischemic preconditioning. This change in performance was accompanied by an increase in blood lactate accumulation and faster strokes in front crawl. Copyright © 2016 Sports Medicine Australia. Published by Elsevier Ltd. All rights reserved.

Investigation of Near Shannon Limit Coding Schemes

NASA Technical Reports Server (NTRS)

Kwatra, S. C.; Kim, J.; Mo, Fan

1999-01-01

Turbo codes can deliver performance that is very close to the Shannon limit. This report investigates algorithms for convolutional turbo codes and block turbo codes. Both coding schemes can achieve performance near Shannon limit. The performance of the schemes is obtained using computer simulations. There are three sections in this report. First section is the introduction. The fundamental knowledge about coding, block coding and convolutional coding is discussed. In the second section, the basic concepts of convolutional turbo codes are introduced and the performance of turbo codes, especially high rate turbo codes, is provided from the simulation results. After introducing all the parameters that help turbo codes achieve such a good performance, it is concluded that output weight distribution should be the main consideration in designing turbo codes. Based on the output weight distribution, the performance bounds for turbo codes are given. Then, the relationships between the output weight distribution and the factors like generator polynomial, interleaver and puncturing pattern are examined. The criterion for the best selection of system components is provided. The puncturing pattern algorithm is discussed in detail. Different puncturing patterns are compared for each high rate. For most of the high rate codes, the puncturing pattern does not show any significant effect on the code performance if pseudo - random interleaver is used in the system. For some special rate codes with poor performance, an alternative puncturing algorithm is designed which restores their performance close to the Shannon limit. Finally, in section three, for iterative decoding of block codes, the method of building trellis for block codes, the structure of the iterative decoding system and the calculation of extrinsic values are discussed.

Uniformity of LED light illumination in application to direct imaging lithography

NASA Astrophysics Data System (ADS)

Huang, Ting-Ming; Chang, Shenq-Tsong; Tsay, Ho-Lin; Hsu, Ming-Ying; Chen, Fong-Zhi

2016-09-01

Direct imaging has widely applied in lithography for a long time because of its simplicity and easy-maintenance. Although this method has limitation of lithography resolution, it is still adopted in industries. Uniformity of UV irradiance for a designed area is an important requirement. While mercury lamps were used as the light source in the early stage, LEDs have drawn a lot of attention for consideration from several aspects. Although LED has better and better performance, arrays of LEDs are required to obtain desired irradiance because of limitation of brightness for a single LED. Several effects are considered that affect the uniformity of UV irradiance such as alignment of optics, temperature of each LED, performance of each LED due to production uniformity, and pointing of LED module. Effects of these factors are considered to study the uniformity of LED Light Illumination. Numerical analysis is performed by assuming a serious of control factors to have a better understanding of each factor.

Automatic control design procedures for restructurable aircraft control

NASA Technical Reports Server (NTRS)

Looze, D. P.; Krolewski, S.; Weiss, J.; Barrett, N.; Eterno, J.

1985-01-01

A simple, reliable automatic redesign procedure for restructurable control is discussed. This procedure is based on Linear Quadratic (LQ) design methodologies. It employs a robust control system design for the unfailed aircraft to minimize the effects of failed surfaces and to extend the time available for restructuring the Flight Control System. The procedure uses the LQ design parameters for the unfailed system as a basis for choosing the design parameters of the failed system. This philosophy alloys the engineering trade-offs that were present in the nominal design to the inherited by the restructurable design. In particular, it alloys bandwidth limitations and performance trade-offs to be incorporated in the redesigned system. The procedure also has several other desirable features. It effectively redistributes authority among the available control effectors to maximize the system performance subject to actuator limitations and constraints. It provides a graceful performance degradation as the amount of control authority lessens. When given the parameters of the unfailed aircraft, the automatic redesign procedure reproduces the nominal control system design.

Amperometric Detection in Microchip Electrophoresis Devices: Effect of Electrode Material and Alignment on Analytical Performance

PubMed Central

Fischer, David J.; Hulvey, Matthew K.; Regel, Anne R.; Lunte, Susan M.

2012-01-01

The fabrication and evaluation of different electrode materials and electrode alignments for microchip electrophoresis with electrochemical (EC) detection is described. The influences of electrode material, both metal and carbon-based, on sensitivity and limits of detection (LOD) were examined. In addition, the effects of working electrode alignment on analytical performance (in terms of peak shape, resolution, sensitivity, and LOD) were directly compared. Using dopamine (DA), norepinephrine (NE), and catechol (CAT) as test analytes, it was found that pyrolyzed photoresist electrodes with end-channel alignment yielded the lowest limit of detection (35 nM for DA). In addition to being easier to implement, end-channel alignment also offered better analytical performance than off-channel alignment for the detection of all three analytes. In-channel electrode alignment resulted in a 3.6-fold reduction in peak skew and reduced peak tailing by a factor of 2.1 for catechol in comparison to end-channel alignment. PMID:19802847

Chewing Gum: Cognitive Performance, Mood, Well-Being, and Associated Physiology

PubMed Central

Allen, Andrew P.; Smith, Andrew P.

2015-01-01

Recent evidence has indicated that chewing gum can enhance attention, as well as promoting well-being and work performance. Four studies (two experiments and two intervention studies) examined the robustness of and mechanisms for these effects. Study 1 investigated the acute effect of gum on mood in the absence of task performance. Study 2 examined the effect of rate and force of chewing on mood and attention performance. Study 3 assessed the effects of chewing gum during one working day on well-being and performance, as well as postwork mood and cognitive performance. In Study 4, performance and well-being were reported throughout the workday and at the end of the day, and heart rate and cortisol were measured. Under experimental conditions, gum was associated with higher alertness regardless of whether performance tasks were completed and altered sustained attention. Rate of chewing and subjective force of chewing did not alter mood but had some limited effects on attention. Chewing gum during the workday was associated with higher productivity and fewer cognitive problems, raised cortisol levels in the morning, and did not affect heart rate. The results emphasise that chewing gum can attenuate reductions in alertness, suggesting that chewing gum enhances worker performance. PMID:26075253

Impacts of Climate Variability and Change on (Marine) Animals: Physiological Underpinnings and Evolutionary Consequences.

PubMed

Pörtner, Hans O; Gutt, Julian

2016-07-01

Understanding thermal ranges and limits of organisms becomes important in light of climate change and observed effects on ecosystems as reported by the IPCC (2014). Evolutionary adaptation to temperature is presently unable to keep animals and other organisms in place; if they can these rather follow the moving isotherms. These effects of climate change on aquatic and terrestrial ecosystems have brought into focus the mechanisms by which temperature and its oscillations shape the biogeography and survival of species. For animals, the integrative concept of oxygen and capacity limited thermal tolerance (OCLTT) has successfully characterized the sublethal limits to performance and the consequences of such limits for ecosystems. Recent models illustrate how routine energy demand defines the realized niche. Steady state temperature-dependent performance profiles thus trace the thermal window and indicate a key role for aerobic metabolism, and the resulting budget of available energy (power), in defining performance under routine conditions, from growth to exercise and reproduction. Differences in the performance and productivity of marine species across latitudes relate to changes in mitochondrial density, capacity, and other features of cellular design. Comparative studies indicate how and why such mechanisms underpinning OCLTT may have developed on evolutionary timescales in different climatic zones and contributed to shaping the functional characteristics and species richness of the respective fauna. A cause-and-effect understanding emerges from considering the relationships between fluctuations in body temperature, cellular design, and performance. Such principles may also have been involved in shaping the functional characteristics of survivors in mass extinction events during earth's history; furthermore, they may provide access to understanding the evolution of endothermy in mammals and birds. Accordingly, an understanding is emerging how climate changes and variability throughout earth's history have influenced animal evolution and co-defined their success or failure from a bio-energetic point of view. Deepening such understanding may further reduce uncertainty about projected impacts of anthropogenic climate variability and change on the distribution, productivity and last not least, survival of aquatic and terrestrial species. © The Author 2016. Published by Oxford University Press on behalf of the Society for Integrative and Comparative Biology. All rights reserved. For permissions please email: journals.permissions@oup.com.

Effects of Surface Nonuniformities on the Mean Transverse Energy from Photocathodes

NASA Astrophysics Data System (ADS)

Karkare, Siddharth; Bazarov, Ivan

2015-08-01

The performance of photoinjectors is limited by the lowest value of the mean transverse energy of the electrons obtained from photocathodes. The factors that influence the mean transverse energy are poorly understood. In this paper, we develop models to calculate the effect of spatial work-function variations and subnanometer-scale roughness and surface defects on the mean transverse energy. We show that these can limit the lowest value of mean transverse energy achieved and that atomically perfect surfaces will be required to further reduce the mean transverse energy obtained from photocathodes.

AN EXAMINATION OF DATA ON IOWA SCHOOL CHILDREN TO DETERMINE PATTERNS OF PERFORMANCE AND "DOWNSTREAM EFFECTS" OF EARLY DEPRESSED SCORES.

ERIC Educational Resources Information Center

FITZSIMMONS, STEPHEN J.

VARIOUS PERFORMANCE PATTERNS WERE STUDIED TO DETERMINE IF EARLY LIMITED FAILURE LEADS TO GENERALIZED FAILURE IN A NUMBER OF AREAS. THE SUBJECTS, 258 DISADVANTAGED URBAN CHILDREN FROM FOUR SCHOOL DISTRICTS IN IOWA, HAD ONE OR MORE SCORES ON THE IOWA TEST OF BASIC SKILLS (ITBS) AT OR BELOW THE 33D PERCENTILE ON NATIONAL NORMS. THEIR PERFORMANCES ON…

Time-resolved speckle effects on the estimation of laser-pulse arrival times

NASA Technical Reports Server (NTRS)

Tsai, B.-M.; Gardner, C. S.

1985-01-01

A maximum-likelihood (ML) estimator of the pulse arrival in laser ranging and altimetry is derived for the case of a pulse distorted by shot noise and time-resolved speckle. The performance of the estimator is evaluated for pulse reflections from flat diffuse targets and compared with the performance of a suboptimal centroid estimator and a suboptimal Bar-David ML estimator derived under the assumption of no speckle. In the large-signal limit the accuracy of the estimator was found to improve as the width of the receiver observational interval increases. The timing performance of the estimator is expected to be highly sensitive to background noise when the received pulse energy is high and the receiver observational interval is large. Finally, in the speckle-limited regime the ML estimator performs considerably better than the suboptimal estimators.

Effects of field-of-view restrictions on speed and accuracy of manoeuvring.

PubMed

Toet, Alexander; Jansen, Sander E M; Delleman, Nico J

2007-12-01

Effects of field-of-view restrictions on the speed and accuracy of participants performing a real-world manoeuvring task through an obstacled environment were investigated. Although field-of-view restrictions are known to affect human behaviour and to degrade performance for a range of different tasks, the relationship between human manoeuvring performance and field-of-view size is not known. This knowledge is essential to evaluate a trade-off between human performance, cost, and ergonomic aspects of field-of-view limiting devises like head-mounted displays and night vision goggles which are frequently deployed for tasks involving human motion through environments with obstacles. In this study the speed and accuracy of movement were measured in 15 participants (8 men, 7 women, 22.9 +/- 2.8 yr. of age) traversing a course formed by three wall segments for different field-of-view restrictions. Analysis showed speed decreased linearly with decreasing field-of-view extent, while accuracy was consistently reduced for all restricted field-of-view conditions. Present results may be used to evaluate cost and performance trade-offs for field-of-view restricting devices deployed to perform time-limited human-locomotion tasks in complex structured environments, such as night-vision goggles and head-mounted displays.

Optimal Design of Cable-Driven Manipulators Using Particle Swarm Optimization.

PubMed

Bryson, Joshua T; Jin, Xin; Agrawal, Sunil K

2016-08-01

The design of cable-driven manipulators is complicated by the unidirectional nature of the cables, which results in extra actuators and limited workspaces. Furthermore, the particular arrangement of the cables and the geometry of the robot pose have a significant effect on the cable tension required to effect a desired joint torque. For a sufficiently complex robot, the identification of a satisfactory cable architecture can be difficult and can result in multiply redundant actuators and performance limitations based on workspace size and cable tensions. This work leverages previous research into the workspace analysis of cable systems combined with stochastic optimization to develop a generalized methodology for designing optimized cable routings for a given robot and desired task. A cable-driven robot leg performing a walking-gait motion is used as a motivating example to illustrate the methodology application. The components of the methodology are described, and the process is applied to the example problem. An optimal cable routing is identified, which provides the necessary controllable workspace to perform the desired task and enables the robot to perform that task with minimal cable tensions. A robot leg is constructed according to this routing and used to validate the theoretical model and to demonstrate the effectiveness of the resulting cable architecture.

Measuring the Hydraulic Effectiveness of Low Impact Development Practices in a Heavily Urbanised Environment: A Case Study from London, UK

NASA Astrophysics Data System (ADS)

El Hattab, M. H.; Vernon, D.; Mijic, A.

2017-12-01

Low impact development practices (LID) are deemed to have a synergetic effect in mitigating urban storm water flooding. Designing and implementing effective LID practices require reliable real-life data about their performance in different applications; however, there are limited studies providing such data. In this study an innovative micro-monitoring system to assess the performance of porous pavement and rain gardens as retrofitting technologies was developed. Three pilot streets in London, UK were selected as part of Thames Water Utilities Limited's Counters Creek scheme. The system includes a V-notch weir installed at the outlet of each LID device to provide an accurate and reliable quantification over a wide range of discharges. In addition to, a low flow sensor installed downstream of the V-notch to cross-check the readings. Having a flow survey time-series of the pre-retrofitting conditions from the study streets, extensive laboratory calibrations under different flow conditions depicting the exact site conditions were performed prior to installing the devices in the field. The micro-monitoring system is well suited for high-resolution temporal monitoring and enables accurate long-term evaluation of LID components' performance. Initial results from the field validated the robustness of the system in fulfilling its requirements.

Processing bottlenecks in dual-task performance: structural limitation or strategic postponement?

NASA Technical Reports Server (NTRS)

Ruthruff, E.; Pashler, H. E.; Klaassen, A.

2001-01-01

Recent evidence indicates that a central bottleneck causes much of the slowing that occurs when two tasks are performed at the same time. This bottleneck might reflect a structural limitation inherent in the cognitive architecture. Alternatively, the bottleneck might reflect strategic (i.e., voluntary) postponement, induced by instructions to emphasize one task over the other. To distinguish structural limitations from strategic postponement, we examine a new paradigm in which subjects are told to place equal emphasis on both tasks and to emit both responses at about the same time. An experiment using this paradigm demonstrated patterns of interference that cannot easily be attributed to strategic postponement, preparation effects, or conflicts in response production. The data conform closely to the predictions of structural central bottleneck models.

Dual-balanced detection scheme with optical hard-limiters in an optical code division multiple access system

NASA Astrophysics Data System (ADS)

Liu, Maw-Yang; Hsu, Yi-Kai

2017-03-01

Three-arm dual-balanced detection scheme is studied in an optical code division multiple access system. As the MAI and beat noise are the main deleterious source of system performance, we utilize optical hard-limiters to alleviate such channel impairment. In addition, once the channel condition is improved effectively, the proposed two-dimensional error correction code can remarkably enhance the system performance. In our proposed scheme, the optimal thresholds of optical hard-limiters and decision circuitry are fixed, and they will not change with other system parameters. Our proposed scheme can accommodate a large number of users simultaneously and is suitable for burst traffic with asynchronous transmission. Therefore, it is highly recommended as the platform for broadband optical access network.

Aerodynamic Limits on Large Civil Tiltrotor Sizing and Efficiency

NASA Technical Reports Server (NTRS)

Acree, C W.

2014-01-01

The NASA Large Civil Tiltrotor (2nd generation, or LCTR2) is a useful reference design for technology impact studies. The present paper takes a broad view of technology assessment by examining the extremes of what aerodynamic improvements might hope to accomplish. Performance was analyzed with aerodynamically idealized rotor, wing, and airframe, representing the physical limits of a large tiltrotor. The analysis was repeated with more realistic assumptions, which revealed that increased maximum rotor lift capability is potentially more effective in improving overall vehicle efficiency than higher rotor or wing efficiency. To balance these purely theoretical studies, some practical limitations on airframe layout are also discussed, along with their implications for wing design. Performance of a less efficient but more practical aircraft with non-tilting nacelles is presented.

Analysis of Risks to Oxygen Systems from Particulate and Fiber Contaminants and Derivation of Cleanliness Requirements

NASA Technical Reports Server (NTRS)

Lowrey, Nikki M.

2016-01-01

It has been well documented in the literature that contamination within oxygen systems can create significant fire hazards. Cleanliness limits for nonvolatile residues, ranging from 10 to 500 milligrams per square meter, have been established for various industries and types of oxygen systems to reduce the risk of ignition of flammable organic films. Particulate cleanliness limits used for oxygen systems, however, vary considerably, notably within the aerospace industry. Maximum allowed particle size, quantity limits, and allocations for fibers or metallic particles are all variables seen in aerospace cleanliness limits. Particles are known to have the potential to ignite within oxygen systems and must be limited to prevent fires. Particulate contamination may also pose risks to the performance of oxygen systems that are unrelated to ignition hazards. An extensive literature search was performed to better understand the relative importance of particle ignition mechanisms versus other deleterious effects of particles on oxygen systems and to identify rationale for derivation of particulate cleanliness limits for specific systems. The identified risks of different types and sizes of particles and fibers were analyzed. This paper summarizes the risks identified and rationale that may be used to derive particulate cleanliness limits for specific oxygen systems.

Analysis of Risks to Oxygen Systems from Particulate and Fiber Contaminants and Derivation of Cleanliness Requirements

NASA Technical Reports Server (NTRS)

Lowrey, Nikki M.

2016-01-01

It has been well documented in the literature that contamination within oxygen systems can create significant fire hazards. Cleanliness limits for nonvolatile residues, ranging from 10 to 500 mg/sq m, have been established for various industries and types of oxygen systems to reduce the risk of ignition of flammable organic films. Particulate cleanliness limits used for oxygen systems vary considerably. Maximum allowed particle size, quantity limits, and allocations for fibers or metallic particles are all variables seen in aerospace cleanliness limits. Particles are known to have the potential to ignite within oxygen systems and must be limited to prevent fires. Particulate contamination may also pose risks to the performance of oxygen systems that are unrelated to ignition hazards. An extensive literature search was performed to better understand the relative importance of particle ignition mechanisms versus other deleterious effects of particles on oxygen systems and to identify rationale for derivation of particulate cleanliness limits for specific systems. The identified risks of different types and sizes of particles and fibers were analyzed. This paper summarizes the risks identified and rationale that may be used to derive particulate cleanliness limits for specific oxygen systems.

Statistical properties and pre-hit dynamics of price limit hits in the Chinese stock markets.

PubMed

Wan, Yu-Lei; Xie, Wen-Jie; Gu, Gao-Feng; Jiang, Zhi-Qiang; Chen, Wei; Xiong, Xiong; Zhang, Wei; Zhou, Wei-Xing

2015-01-01

Price limit trading rules are adopted in some stock markets (especially emerging markets) trying to cool off traders' short-term trading mania on individual stocks and increase market efficiency. Under such a microstructure, stocks may hit their up-limits and down-limits from time to time. However, the behaviors of price limit hits are not well studied partially due to the fact that main stock markets such as the US markets and most European markets do not set price limits. Here, we perform detailed analyses of the high-frequency data of all A-share common stocks traded on the Shanghai Stock Exchange and the Shenzhen Stock Exchange from 2000 to 2011 to investigate the statistical properties of price limit hits and the dynamical evolution of several important financial variables before stock price hits its limits. We compare the properties of up-limit hits and down-limit hits. We also divide the whole period into three bullish periods and three bearish periods to unveil possible differences during bullish and bearish market states. To uncover the impacts of stock capitalization on price limit hits, we partition all stocks into six portfolios according to their capitalizations on different trading days. We find that the price limit trading rule has a cooling-off effect (object to the magnet effect), indicating that the rule takes effect in the Chinese stock markets. We find that price continuation is much more likely to occur than price reversal on the next trading day after a limit-hitting day, especially for down-limit hits, which has potential practical values for market practitioners.

Experimental investigation of control/display augmentation effects in a compensatory tracking task

NASA Technical Reports Server (NTRS)

Garg, Sanjay; Schmidt, David K.

1988-01-01

The effects of control/display augmentation on human performance and workload have been investigated for closed-loop, continuous-tracking tasks by a real-time, man-in-the-loop simulation study. The experimental results obtained indicate that only limited improvement in actual tracking performance is obtainable through display augmentation alone; with a very high level of display augmentation, tracking error will actually deteriorate. Tracking performance improves when status information is furnished for reasonable levels of display quickening; again, very high quickening levels lead to tracking error deterioration due to the incompatibility between the status information and the quickened signal.

Adaptive Wing Camber Optimization: A Periodic Perturbation Approach

NASA Technical Reports Server (NTRS)

Espana, Martin; Gilyard, Glenn

1994-01-01

Available redundancy among aircraft control surfaces allows for effective wing camber modifications. As shown in the past, this fact can be used to improve aircraft performance. To date, however, algorithm developments for in-flight camber optimization have been limited. This paper presents a perturbational approach for cruise optimization through in-flight camber adaptation. The method uses, as a performance index, an indirect measurement of the instantaneous net thrust. As such, the actual performance improvement comes from the integrated effects of airframe and engine. The algorithm, whose design and robustness properties are discussed, is demonstrated on the NASA Dryden B-720 flight simulator.

20 CFR 641.710 - How are the performance indicators defined?

Code of Federal Regulations, 2014 CFR

2014-04-01

... prospects; (vi) Have limited English proficiency; (vii) Have low literacy skills; (viii) Have a disability... information collection and recordkeeping requirements and will not become effective until approval has been...

20 CFR 641.710 - How are the performance indicators defined?

Code of Federal Regulations, 2013 CFR

2013-04-01

... prospects; (vi) Have limited English proficiency; (vii) Have low literacy skills; (viii) Have a disability... information collection and recordkeeping requirements and will not become effective until approval has been...

20 CFR 641.710 - How are the performance indicators defined?

Code of Federal Regulations, 2012 CFR

2012-04-01

... prospects; (vi) Have limited English proficiency; (vii) Have low literacy skills; (viii) Have a disability... information collection and recordkeeping requirements and will not become effective until approval has been...

77 FR 29167 - Effluent Limitations Guidelines and New Source Performance Standards for the Airport Deicing...

Federal Register 2010, 2011, 2012, 2013, 2014

2012-05-16

... reductions in dissolved oxygen, fish kills, reduced organism abundance and species diversity, contamination... 13045: Protection of Children From Environmental Health and Safety Risks H. EO 13211: Energy Effects I... water in residential areas and parkland, and other effects. Today, EPA is promulgating effluent...

Understanding Stress.

ERIC Educational Resources Information Center

Bellott, Fred K.

Stress affects everyone in his/her work and everyday life. Some persons are more effective when they are under a certain level of stress, but there are limits to the amount of stress under which one can perform effectively. Competition within complex organizations today is a risk factor not often recognized by the organizations. All organizations…

Physical performance limitations among adult survivors of childhood brain tumors

PubMed Central

Ness, Kirsten K.; Morris, E. Brannon; Nolan, Vikki G.; Howell, Carrie R.; Gilchrist, Laura S.; Stovall, Marilyn; Cox, Cheryl L.; Klosky, James L.; Gajjar, Amar; Neglia, Joseph P.

2013-01-01

Background Young adult survivors of childhood brain tumors (BT) may have late-effects that compromise physical performance and everyday task participation. Objective To evaluate muscle strength, fitness, physical performance, and task participation among adult survivors of childhood BT. Design/Method In-home evaluations and interviews were conducted for 156 participants (54% male). Results on measures of muscle strength, fitness, physical performance, and participation were compared between survivors and population-group members with chi-squared statistics and two-sample t-tests. Associations between late effects and physical performance, and physical performance and participation, were evaluated in regression models. Results BT survivors were a median age of 22 (18–58), and 14.7 (6.5–45.9) years from diagnosis. Survivors had lower estimates of grip strength (Female: 24.7±9.2 vs. 31.5±5.8, Male: 39.0±12.2 vs. 53.0±10.1 kilograms), knee extension strength (Female: 246.6±95.5 vs. 331.5±5.8, Male: 304.7±116.4 vs. 466.6±92.1 Newtons) and peak oxygen uptake (Female: 25.1±8.8 vs. 31.3±5.1, Male: 24.6±9.5 vs. 33.2±3.4 milliliters/kilogram/minute) than population-group members. Physical performance was lower among survivors and associated with not living independently (OR=5.0, 95% CI=2.0–12.2) and not attending college (OR=2.3, 95% CI 1.2–4.4). Conclusion Muscle strength and fitness values among BT survivors are similar to those among persons 60+ years, and are associated with physical performance limitations. Physical performance limitations are associated with poor outcomes in home and school environments. These data indicate an opportunity for interventions targeted at improving long-term physical function in this survivor population. PMID:20564409

Indirect genetic effects from competition in the clonal herb Sedum album (Crassulaceae).

PubMed

Andersson, Stefan

2014-01-01

Recent years have seen increasing interest in indirect genetic effects, i.e. influences on the phenotype that depend on the genotype of other conspecific individuals; however, the empirical evidence for such effects is still limited, especially in wild plant species. The present study of the clonal herb Sedum album assessed direct and indirect genetic effects on performance-related traits in a 4-year experiment with clonally replicated genotypes, grown in pairs and differing in anthocyanin pigmentation to allow separation of individuals during data collection. In agreement with the existence of indirect genetic effects, the experimentally-paired plants not only expressed their own genotype but were also affected by the genotype of their pair mate. The effect of neighbour genotype explained up to one-fourth of the variation in performance and most likely resulted from competition, imposed by the close physical contact between paired individuals and the limiting conditions used in the garden environment. Indirect genetic effects from competition have the potential to enhance the efficacy of group-level selection relative to individual selection, given the nutrient-poor and spatially-confined substrate available to plants of S. album in the natural habitat.

Advanced Computer Image Generation Techniques Exploiting Perceptual Characteristics

DTIC Science & Technology

1981-08-01

the capabilities/limitations of the human visual perceptual processing system and improve the training effectiveness of visual simulation systems...Myron Braunstein of the University of California at Irvine performed all the work in the perceptual area. Mr. Timothy A. Zimmerlin contributed the... work . Thus, while some areas are related, each is resolved independently in order to focus on the basic perceptual limitation. In addition, the

Snap-through instability analysis of dielectric elastomers with consideration of chain entanglements

NASA Astrophysics Data System (ADS)

Zhu, Jiakun; Luo, Jun; Xiao, Zhongmin

2018-06-01

It is widely recognized that the extension limit of polymer chains has a significant effect on the snap-through instability of dielectric elastomers (DEs). The snap-through instability performance of DEs has been extensively studied by two limited-stretch models, i.e., the eight-chain model and Gent model. However, the real polymer networks usually have many entanglements due to the impenetrability of the network chains as well as a finite extensibility resulting from the full stretching of the polymer chains. The effects of entanglements on the snap-through instability of DEs cannot be captured by the previous two limited-stretch models. In this paper, the nonaffine model proposed by Davidson and Goulbourne is adopted to characterize the influence of entanglements and extension limit of the polymer chains. It is demonstrated that the nonaffine model is almost identical to the eight-chain model and is close to the Gent model if we ignore the effects of chain entanglements and adopt the affine assumption. The suitability of the nonaffine model to characterize the mechanical behavior of elastomers is validated by fitting the experimental results reported in the open literature. After that, the snap-through stability performance of an ideal DE membrane under equal-biaxial prestretches is studied with the nonaffine model. It is revealed that besides the prestretch and chain extension limit, the chain entanglements can markedly influence the snap-through instability and the path to failure of DEs. These results provide a more comprehensive understanding on the snap-through instability of a DE and may be helpful to guide the design of DE devices.

Management practices and performance of mergers and acquisitions in Pakistan: mediating role of psychological contract.

PubMed

Bari, Muhammad Waseem; Fanchen, Meng; Baloch, Muhammad Awais

2016-01-01

The objective of this study is to examine the direct and indirect effect of management practices (procedural justice, coordination approach, communication system, integration strategy, and coping programs) on merger and acquisition (M&A) performance in the Pakistan banking industry. Psychological contract (PC) acts as a mediator between Management practices and M&A performance. The Present study distributes a structured questionnaire to 700 bank employees of different management cadres. The useful response rate is 76 % (536 employees). It uses PLS-SEM technique for data analysis. (1) procedural justice is a key strategy which has highly significant direct and indirect effect on M&A performance; however integration strategy and the communication system have an only direct effect. (2) PC performs partial mediation at different levels between management practices and M&A financial and non-financial performance. This study provides an effective solution to solve the soft issues during and post-M&A process. This is one of the few studies which effectively integrate the five constructs into a single framework to study their effects on M&A performance. Limitations and future research directions are presented in the last section of the study.

The Differential Effects of Gender and Mathematics Anxiety-Apprehension on Developmental Students' Academic Performance and Persistence.

ERIC Educational Resources Information Center

Ikegulu, T. Nelson

The performance of 244 (111 male and 133 female) developmental college students was studied in relation to their perceived levels of mathematics anxiety (123 low and 121 high). The Mathematics Anxiety-Apprehension Survey (MAAS) (T. Ikegulu, 1998) was administered to students in four classes from two institutions. The product limit estimator…

The Effects of Achievement Goals and Self-Regulated Learning Behaviors on Reading Comprehension in Technology-Enhanced Learning Environments

ERIC Educational Resources Information Center

Bernacki, Matthew L.; Byrnes, James P.; Cromley, Jennifer G.

2012-01-01

Studies examining students' achievement goals, cognitive engagement strategies and performance have found that achievement goals tend to predict classes of cognitive strategy use which predict performance on measures of learning. These studies have led to deeper theoretical understanding, but their reliance on self-report data limit the…

Confidence and Competence among Community College Students: Self-Efficacy and Performance in Grammar

ERIC Educational Resources Information Center

Collins, Steve; Bissell, Kimberly

2004-01-01

Proper grammar is crucial for effective communication. Two surveys of students in an introductory writing course sought to identify predictors of grammar ability. Students demonstrated a limited grasp of the language, struggling with such issues as the distinction between "it's" and "its." Women performed better than men at the beginning of the…

Exceptions to the PRP Effect? A Comparison of Prepared and Unconditioned Reflexes

ERIC Educational Resources Information Center

Janczyk, Markus; Pfister, Roland; Wallmeier, Gloria; Kunde, Wilfried

2014-01-01

Psychological research has documented again and again marked performance decrements whenever humans perform 2 or more tasks at the same time. In fact, the available evidence seems to suggest that any type of behavior is subject to such limitations. The present experiments employed the psychological refractory period (PRP) paradigm to identify a…

INFLUENCE OF LARVAL EXPOSURE TO SALINITY AND CADMIUM STRESS ON JUVENILE PERFORMANCE OF TWO MARINE INVERTEBRATES, CAPITELLA SP I AND CREPIDULA FORNICATA

EPA Science Inventory

Delayed metamorphosis and short-term food limitation reduce juvenile or adult fitness in a number of marine invertebrate species. In this study, we tested the ability of pollutant and salinity stress to bring about similar effects on juvenile or adult performance. Larvae of the p...

A STUDY OF CERTAIN FACTORS AFFECTING CHILDRENS' SCHOOL PERFORMANCE.

ERIC Educational Resources Information Center

SPENCE, JANET T.

AS PART OF THE RESEARCH ON THE INFLUENCE OF RESPONSE-CONTINGENT REINFORCERS ON THE LEARNING AND PROBLEM-SOLVING BEHAVIOR OF CHILDREN, THE EFFECTS OF A LIMITED NUMBER OF VARIABLES ON THE PERFORMANCE OF CHILDREN OF THREE AGE LEVELS (4-5, 7-8, AND 10-11), SELECTED EQUALLY FROM MIDDLE- AND LOWER-CLASS BACKGROUNDS, WERE INVESTIGATED. THE EXPERIMENTAL…

A Regression Model with a New Tool: IDB Analyzer for Identifying Factors Predicting Mathematics Performance Using PISA 2012 Indices

ERIC Educational Resources Information Center

Arikan, Serkan

2014-01-01

There are many studies that focus on factors affecting achievement. However, there is limited research that used student characteristics indices reported by the Programme for International Student Assessment (PISA). Therefore, this study investigated the predictive effects of student characteristics on mathematics performance of Turkish students.…

Direct Object Predictability: Effects on Young Children's Imitation of Sentences

ERIC Educational Resources Information Center

Valian, Virginia; Prasada, Sandeep; Scarpa, Jodi

2006-01-01

We hypothesize that the conceptual relation between a verb and its direct object can make a sentence easier ("the cat is eating some food") or harder ("the cat is eating a sock") to parse and understand. If children's limited performance systems contribute to the ungrammatical brevity of their speech, they should perform better on sentences that…

Human Factors Engineering and Ergonomics in Systems Engineering

NASA Technical Reports Server (NTRS)

Whitmore, Mihriban

2017-01-01

The study, discovery, and application of information about human abilities, human limitations, and other human characteristics to the design of tools, devices, machines, systems, job tasks and environments for effective human performance.

Minnesota Local Agency Pavement Marking : Mining Existing Data

DOT National Transportation Integrated Search

2017-11-01

Pavement marking is important for safety. Maximizing pavement marking performance in terms of increased retroreflectivity, within limited budget constraints, allows agencies to make better decisions toward providing more effective pavement marking pe...

Comparison of SeaWinds Backscatter Imaging Algorithms

PubMed Central

Long, David G.

2017-01-01

This paper compares the performance and tradeoffs of various backscatter imaging algorithms for the SeaWinds scatterometer when multiple passes over a target are available. Reconstruction methods are compared with conventional gridding algorithms. In particular, the performance and tradeoffs in conventional ‘drop in the bucket’ (DIB) gridding at the intrinsic sensor resolution are compared to high-spatial-resolution imaging algorithms such as fine-resolution DIB and the scatterometer image reconstruction (SIR) that generate enhanced-resolution backscatter images. Various options for each algorithm are explored, including considering both linear and dB computation. The effects of sampling density and reconstruction quality versus time are explored. Both simulated and actual data results are considered. The results demonstrate the effectiveness of high-resolution reconstruction using SIR as well as its limitations and the limitations of DIB and fDIB. PMID:28828143

Microbial community activities during establishment, performance, and decline of bench-scale passive treatment systems for mine drainage.

PubMed

Logan, Miranda V; Reardon, Kenneth F; Figueroa, Linda A; McLain, Jean E T; Ahmann, Dianne M

2005-11-01

Permeable reactive barrier (PRB) technology, in which sulfate-reducing bacteria (SRB) facilitate precipitation of metal sulfides, is a promising approach for remediation of sulfate- and metal-laden mine drainage. While PRBs are easily established, they often decline for reasons not well understood. SRB depend on or compete with multiple dynamic microbial populations within a PRB; as a result, performance depends on the changing PRB chemical composition and on succession and competition within the microbial community. To investigate these interactions, we constructed and monitored eight bench-scale PRBs to define periods of establishment, performance, and decline. We then conducted short-term batch studies, using substrate-supplemented column materials, on Days 0 (pre-establishment), 27 (establishment), 41 (performance), and 99 (decline) to reveal potential activities of cellulolytic bacteria, fermenters + anaerobic respirers, SRB, and methanogens. PRBs showed active sulfate reduction, with sulfate removal rates (SRR) of approximately 1-3 mol/m3/d, as well as effective removal of Zn2+. Potential activities of fermentative + anaerobic respiratory bacteria were initially high but diminished greatly during establishment and dropped further during performance and decline. In contrast, potential SRB activity rose during establishment, peaked during performance, and diminished as performance declined. Potential methanogen activity was low; in addition, SRB-methanogen substrate competition was shown not to limit SRB activity. Cellulolytic bacteria showed no substrate limitation at any time. However, fermenters experienced substrate limitation by Day 0, SRB by Day 27, and methanogens by Day 41, showing the dependence of each group on upstream populations to provide substrates. All potential activities, except methanogenesis, were ultimately limited by cellulose hydrolysis; in addition, all potential activities except methanogenesis declined substantially by Day 99, showing that long-term substrate deprivation strongly diminished the intrinsic capacity of the PRB community to perform.

Simultaneous effects of food limitation and inducible resistance on herbivore population dynamics.

PubMed

Abbott, Karen C; Morris, William F; Gross, Kevin

2008-02-01

Many herbivore populations fluctuate temporally, but the causes of those fluctuations remain unclear. Plant inducible resistance can theoretically cause herbivore population fluctuations, because herbivory may induce plant changes that reduce the survival or reproduction of later-feeding herbivores. Herbivory can also simply reduce the quantity of food available for later feeders and this, too, can cause population fluctuations. Inducible resistance and food limitation often occur simultaneously, yet whether they jointly facilitate or suppress herbivore fluctuations remains largely unexplored. We present models that suggest that food limitation and inducible resistance may have synergistic effects on herbivore population dynamics. The population-level response of the food plant to herbivory and the details of how inducible resistance affects herbivore performance both influence the resulting herbivore dynamics. Our results identify some biological properties of plant-herbivore systems that might determine whether or not cycles occur, and suggest that future empirical and theoretical population dynamics studies should account for the effects of both food limitation and inducible resistance.

An empirical/theoretical model with dimensionless numbers to predict the performance of electrodialysis systems on the basis of operating conditions.

PubMed

Karimi, Leila; Ghassemi, Abbas

2016-07-01

Among the different technologies developed for desalination, the electrodialysis/electrodialysis reversal (ED/EDR) process is one of the most promising for treating brackish water with low salinity when there is high risk of scaling. Multiple researchers have investigated ED/EDR to optimize the process, determine the effects of operating parameters, and develop theoretical/empirical models. Previously published empirical/theoretical models have evaluated the effect of the hydraulic conditions of the ED/EDR on the limiting current density using dimensionless numbers. The reason for previous studies' emphasis on limiting current density is twofold: 1) to maximize ion removal, most ED/EDR systems are operated close to limiting current conditions if there is not a scaling potential in the concentrate chamber due to a high concentration of less-soluble salts; and 2) for modeling the ED/EDR system with dimensionless numbers, it is more accurate and convenient to use limiting current density, where the boundary layer's characteristics are known at constant electrical conditions. To improve knowledge of ED/EDR systems, ED/EDR models should be also developed for the Ohmic region, where operation reduces energy consumption, facilitates targeted ion removal, and prolongs membrane life compared to limiting current conditions. In this paper, theoretical/empirical models were developed for ED/EDR performance in a wide range of operating conditions. The presented ion removal and selectivity models were developed for the removal of monovalent ions and divalent ions utilizing the dominant dimensionless numbers obtained from laboratory scale electrodialysis experiments. At any system scale, these models can predict ED/EDR performance in terms of monovalent and divalent ion removal. Copyright © 2016 Elsevier Ltd. All rights reserved.

Effects of Indoor Footwear on Balance and Gait Patterns in Community-Dwelling Older Women.

PubMed

Menz, Hylton B; Auhl, Maria; Munteanu, Shannon E

2017-01-01

Footwear worn indoors is generally less supportive than outdoor footwear and may increase the risk of falls. To evaluate balance ability and gait patterns in older women while wearing different styles of indoor footwear: a backless slipper and an enclosed slipper designed to optimise balance. Older women (n = 30) aged 65-83 years (mean 74.4, SD 5.6) performed a series of laboratory tests of balance ability (postural sway, limits of stability, and tandem walking, measured with the NeuroCom® Balance Master) and gait patterns (walking speed, cadence, and step length, measured with the GAITRite® walkway) while wearing (1) socks, (2) backless slippers with a soft sole, and (3) enclosed slippers with a firm sole and Velcro® fastening. Perceptions of the footwear were also documented using a structured questionnaire. Significant overall effects of footwear were observed for postural sway, the limits of stability test (directional control), the tandem walk test (step width and end sway), and temporospatial gait patterns (walking speed, cadence, and step length). No footwear effects were observed for maximum excursion when performing the limits of stability test or for speed when performing the tandem walk test. Post hoc tests indicated that performances were best while wearing the enclosed slippers, intermediate with socks, and worst with backless slippers. The enclosed slippers were perceived to be more attractive, comfortable, and well fitted, but heavier than the backless slippers. Most participants (n = 23; 77%) reported that they would consider wearing the enclosed slippers to reduce their risk of falling. Indoor footwear with an enclosed heel, Velcro® fastening, and a firm sole optimises balance and gait compared to backless slippers, and is therefore recommended to reduce the risk of falling. © 2016 The Author(s) Published by S. Karger AG, Basel.

Improvement of SPM nonlinear limit by chirped duobinary PolSK transmission

NASA Astrophysics Data System (ADS)

Yang, Lixiu; Fan, Jiayu; Wang, Lutang; Huang, Zhaoming

2005-02-01

In today's terrestrial long-haul optical fiber communication systems, high channel powers are required to obtain a large transmission distance with reasonable optical amplifier spacing. In such systems, however, the presence of nonlinear effects such as the self-phase modulation (SPM) and the fiber dispersion as well as their combined effects, called SPM-induced nonlinear limitation or SPM limit, will seriously degrade the system performances in respect of the effective transmission distance and ultimately become a limiting factor in high-speed, long-haul optical fiber transmission.In this paper, a new transmission format: chirped duobinary PolSK transmission, has been proposed to generate a pre-chirped duobianry signal with fixed polarity (either positive or negative), which is modulated by a PolSK modulator. This format is based on a transmitter setup consisting of a duobinary PolSK Modulation transmitter followed by an additional phase modulator. The chirped duobinary PolSK transmission reduces the signal degradation and spectral broadening in the nonlinear regime significantly. Thus it shifts this SPM nonlinear limit to enable more relaxed dispersion compensation at high optical power compared to the conventional duobinary schemes.The simulation results show chirped duobinary PolSK transmission enlarges the dispersion limited transmission distance, increases the dispersion tolerance and overcome the SPM nonlinear limit.

Effect of a curved duct upstream on performance of small centrifugal compressors for automobile turbochargers

NASA Astrophysics Data System (ADS)

Kikuchi, Shigeta; Yamasaki, Nobuhiko; Yamagata, Akihiro

2013-02-01

Since the automobile turbochargers are installed in an engine compartment with limited space, the ducts upstream of the turbocharger compressor may be curved in a complex manner. In the present paper, the effect of a curved duct upstream on performance of small centrifugal compressors for automobile turbochargers is discussed. The computational fluid dynamics (CFD) analysis of a turbocharger compressor validated for the compressor model with the straight pipe applied to the compressor with the curved pipe are executed, and the deterioration of the performance for the curved pipe is confirmed. It is also found that the deterioration of compressor performance is caused by the interaction of the secondary flow and the impeller.

Nutritional Supplements for Endurance Athletes

NASA Astrophysics Data System (ADS)

Rasmussen, Christopher J.

Athletes engaged in heavy endurance training often seek additional nutritional strategies to help maximize performance. Specific nutritional supplements exist to combat certain factors that limit performance beginning with a sound everyday diet. Research has further demonstrated that safe, effective, legal supplements are in fact available for today's endurance athletes. Several of these supplements are marketed not only to aid performance but also to combat the immunosuppressive effects of intense endurance training. It is imperative for each athlete to research the legality of certain supplements for their specific sport or event. Once the legality has been established, it is often up to each individual athlete to decipher the ethics involved with ingesting nutritional supplements with the sole intent of improving performance.

Knee joint stabilization therapy in patients with osteoarthritis of the knee: a randomized, controlled trial.

PubMed

Knoop, J; Dekker, J; van der Leeden, M; van der Esch, M; Thorstensson, C A; Gerritsen, M; Voorneman, R E; Peter, W F; de Rooij, M; Romviel, S; Lems, W F; Roorda, L D; Steultjens, M P M

2013-08-01

To investigate whether an exercise program, initially focusing on knee stabilization and subsequently on muscle strength and performance of daily activities is more effective than an exercise program focusing on muscle strength and performance of daily activities only, in reducing activity limitations in patients with knee osteoarthritis (OA) and instability of the knee joint. A single-blind, randomized, controlled trial involving 159 knee OA patients with self-reported and/or biomechanically assessed knee instability, randomly assigned to two treatment groups. Both groups received a supervised exercise program for 12 weeks, consisting of muscle strengthening exercises and training of daily activities, but only in the experimental group specific knee joint stabilization training was provided. Outcome measures included activity limitations (Western Ontario and McMaster Universities Osteoarthritis Index - WOMAC physical function, primary outcome), pain, global perceived effect and knee stability. Both treatment groups demonstrated large (∼20-40%) and clinically relevant reductions in activity limitations, pain and knee instability, which were sustained 6 months post-treatment. No differences in effectiveness between experimental and control treatment were found on WOMAC physical function (B (95% confidence interval - CI) = -0.01 (-2.58 to 2.57)) or secondary outcome measures, except for a higher global perceived effect in the experimental group (P = 0.04). Both exercise programs were highly effective in reducing activity limitations and pain and restoring knee stability in knee OA patients with instability of the knee. In knee OA patients suffering from knee instability, specific knee joint stabilization training, in addition to muscle strengthening and functional exercises, does not seem to have any additional value. Dutch Trial Register (NTR) registration number: NTR1475. Copyright © 2013 Osteoarthritis Research Society International. Published by Elsevier Ltd. All rights reserved.

The culture of time in neuropsychological assessment: exploring the effects of culture-specific time attitudes on timed test performance in Russian and American samples.

PubMed

Agranovich, Anna V; Panter, A T; Puente, Antonio E; Touradji, Pegah

2011-07-01

Cultural differences in time attitudes and their effect on timed neuropsychological test performance were examined in matched non-clinical samples of 100 Russian and American adult volunteers using 8 tests that were previously reported to be relatively free of cultural bias: Color Trails Test (CTT); Ruff Figural Fluency Test (RFFT); Symbol Digit Modalities Test (SDMT); and Tower of London-Drexel Edition (ToL(Dx)). A measure of time attitudes, the Culture of Time Inventory (COTI-33) was used to assess time attitudes potentially affecting time-limited testing. Americans significantly outscored Russians on CTT, SDMT, and ToL(Dx) (p,.05) while differences in RFFT scores only approached statistical significance. Group differences also emerged in COTI-33 factor scores, which partially mediated differences in performance on CTT-1, SDMT, and ToL(Dx) initiation time, but did not account for the effect of culture on CTT-2. Significant effect of culture was revealed in ratings of familiarity with testing procedures that was negatively related to CTT, ToL(Dx), and SDMT scores. Current findings indicated that attitudes toward time may influence results of time limited testing and suggested that individuals who lack familiarity with timed testing procedures tend to obtain lower scores on timed tests.

Cost-effective Diagnostic Checklists for Meningitis in Resource Limited Settings

PubMed Central

Durski, Kara N.; Kuntz, Karen M.; Yasukawa, Kosuke; Virnig, Beth A.; Meya, David B.; Boulware, David R.

2013-01-01

Background Checklists can standardize patient care, reduce errors, and improve health outcomes. For meningitis in resource-limited settings, with high patient loads and limited financial resources, CNS diagnostic algorithms may be useful to guide diagnosis and treatment. However, the cost-effectiveness of such algorithms is unknown. Methods We used decision analysis methodology to evaluate the costs, diagnostic yield, and cost-effectiveness of diagnostic strategies for adults with suspected meningitis in resource limited settings with moderate/high HIV prevalence. We considered three strategies: 1) comprehensive “shotgun” approach of utilizing all routine tests; 2) “stepwise” strategy with tests performed in a specific order with additional TB diagnostics; 3) “minimalist” strategy of sequential ordering of high-yield tests only. Each strategy resulted in one of four meningitis diagnoses: bacterial (4%), cryptococcal (59%), TB (8%), or other (aseptic) meningitis (29%). In model development, we utilized prevalence data from two Ugandan sites and published data on test performance. We validated the strategies with data from Malawi, South Africa, and Zimbabwe. Results The current comprehensive testing strategy resulted in 93.3% correct meningitis diagnoses costing $32.00/patient. A stepwise strategy had 93.8% correct diagnoses costing an average of $9.72/patient, and a minimalist strategy had 91.1% correct diagnoses costing an average of $6.17/patient. The incremental cost effectiveness ratio was $133 per additional correct diagnosis for the stepwise over minimalist strategy. Conclusions Through strategically choosing the order and type of testing coupled with disease prevalence rates, algorithms can deliver more care more efficiently. The algorithms presented herein are generalizable to East Africa and Southern Africa. PMID:23466647

Optimal control of 2-wheeled mobile robot at energy performance index

NASA Astrophysics Data System (ADS)

Kaliński, Krzysztof J.; Mazur, Michał

2016-03-01

The paper presents the application of the optimal control method at the energy performance index towards motion control of the 2-wheeled mobile robot. With the use of the proposed method of control the 2-wheeled mobile robot can realise effectively the desired trajectory. The problem of motion control of mobile robots is usually neglected and thus performance of the realisation of the high level control tasks is limited.

Separate and combined effects of the GABAA positive allosteric modulator diazepam and Δ⁹-THC in humans discriminating Δ⁹-THC.

PubMed

Lile, Joshua A; Kelly, Thomas H; Hays, Lon R

2014-10-01

Our previous research suggested the involvement of γ-aminobutyric acid (GABA), in particular the GABAB receptor subtype, in the interoceptive effects of Δ(9)-tetrahydrocannabinol (Δ(9)-THC). The aim of the present study was to determine the potential involvement of the GABAA receptor subtype by assessing the separate and combined effects of the GABAA positive allosteric modulator diazepam and Δ(9)-THC using pharmacologically selective drug-discrimination procedures. Ten cannabis users learned to discriminate 30 mg oral Δ(9)-THC from placebo and then received diazepam (5 and 10mg), Δ(9)-THC (5, 15 and 30 mg) and placebo, alone and in combination. Self-report, task performance and physiological measures were also collected. Δ(9)-THC functioned as a discriminative stimulus, produced subjective effects typically associated with cannabinoids (e.g., High, Stoned, Like Drug) and elevated heart rate. Diazepam alone impaired performance on psychomotor performance tasks and increased ratings on a limited number of self-report questionnaire items (e.g., Any Effect, Sedated), but did not substitute for the Δ(9)-THC discriminative stimulus or alter the Δ(9)-THC discrimination dose-response function. Similarly, diazepam had limited impact on the other behavioral effects of Δ(9)-THC. These results suggest that the GABAA receptor subtype has minimal involvement in the interoceptive effects of Δ(9)-THC, and by extension cannabis, in humans. Copyright © 2014 Elsevier Ireland Ltd. All rights reserved.

A chromogranin A ELISA absent of an apparent high-dose hook effect observed in other chromogranin A ELISAs.

PubMed

Erickson, J Alan; Grenache, David G

2016-01-15

Routine testing for chromogranin A (CgA) using an established commercial ELISA revealed an apparent high-dose hook effect in approximately 15% of specimens. Investigations found the same effect in two additional ELISAs. We hypothesized that a CgA derived peptide(s) at high concentrations was responsible but experiments were inconclusive. Here we describe the analytical performance characteristics of the Chromoa™ CgA ELISA that did not display the apparent high-dose hook effect. Performance characteristics of the Chromoa ELISA were assessed. The reference interval was established utilizing healthy volunteers. Specimens producing the apparent high-dose hook effect in other assays were evaluated using the Chromoa ELISA. The limit of detection was 8ng/ml. Linearity was acceptable (slope=1.04, intercept=18.1 and r(2)=0.997). CVs were ≤4.6 and ≤9.3% for repeatability and within-laboratory imprecision, respectively. CgA was stable at ambient and refrigerated temperatures for a minimum of two and 14days, respectively. An upper reference interval limit of 95ng/ml was established. Specimens demonstrating the apparent high-dose hook effect in other ELISAs did not exhibit the phenomenon using the Chromoa ELISA. The Chromoa ELISA demonstrates acceptable performance for quantifying serum CgA. The apparent high-dose hook effect exhibited in other ELISAs was absent using the Chromoa assay. Copyright © 2015 Elsevier B.V. All rights reserved.

Safety Validation of Repeated Blood-Brain Barrier Disruption Using Focused Ultrasound.

PubMed

Kobus, Thiele; Vykhodtseva, Natalia; Pilatou, Magdalini; Zhang, Yongzhi; McDannold, Nathan

2016-02-01

The purpose of this study was to investigate the effects on the brain of multiple sessions of blood-brain barrier (BBB) disruption using focused ultrasound (FUS) in combination with micro-bubbles over a range of acoustic exposure levels. Six weekly sessions of FUS, using acoustical pressures between 0.66 and 0.80 MPa, were performed under magnetic resonance guidance. The success and degree of BBB disruption was estimated by signal enhancement of post-contrast T1-weighted imaging of the treated area. Histopathological analysis was performed after the last treatment. The consequences of repeated BBB disruption varied from no indications of vascular damage to signs of micro-hemorrhages, macrophage infiltration, micro-scar formations and cystic cavities. The signal enhancement on the contrast-enhanced T1-weighted imaging had limited value for predicting small-vessel damage. T2-weighted imaging corresponded well with the effects on histopathology and could be used to study treatment effects over time. This study demonstrates that repeated BBB disruption by FUS can be performed with no or limited damage to the brain tissue. Copyright © 2016 World Federation for Ultrasound in Medicine & Biology. Published by Elsevier Inc. All rights reserved.

Pursuing Polymer Dielectric Interfacial Effect in Organic Transistors for Photosensing Performance Optimization.

PubMed

Wu, Xiaohan; Chu, Yingli; Liu, Rui; Katz, Howard E; Huang, Jia

2017-12-01

Polymer dielectrics in organic field-effect transistors (OFETs) are essential to provide the devices with overall flexibility, stretchability, and printability and simultaneously introduce charge interaction on the interface with organic semiconductors (OSCs). The interfacial effect between various polymer dielectrics and OSCs significantly and intricately influences device performance. However, understanding of this effect is limited because the interface is buried and the interfacial charge interaction is difficult to stimulate and characterize. Here, this challenge is overcome by utilizing illumination to stimulate the interfacial effect in various OFETs and to characterize the responses of the effect by measuring photoinduced changes of the OFETs performances. This systemic investigation reveals the mechanism of the intricate interfacial effect in detail, and mathematically explains how the photosensitive OFETs characteristics are determined by parameters including polar group of the polymer dielectric and the OSC side chain. By utilizing this mechanism, performance of organic electronics can be precisely controlled and optimized. OFETs with strong interfacial effect can also show a signal additivity caused by repeated light pulses, which is applicable for photostimulated synapse emulator. Therefore, this work enlightens a detailed understanding on the interface effect and provides novel strategies for optimizing OFET photosensory performances.

Thermodynamic fingerprints of non-Markovianity in a system of coupled superconducting qubits

NASA Astrophysics Data System (ADS)

Hamedani Raja, Sina; Borrelli, Massimo; Schmidt, Rebecca; Pekola, Jukka P.; Maniscalco, Sabrina

2018-03-01

The exploitation and characterization of memory effects arising from the interaction between system and environment is a key prerequisite for quantum reservoir engineering beyond the standard Markovian limit. In this paper we investigate a prototype of non-Markovian dynamics experimentally implementable with superconducting qubits. We rigorously quantify non-Markovianity, highlighting the effects of the environmental temperature on the Markovian to non-Markovian crossover. We investigate how memory effects influence, and specifically suppress, the ability to perform work on the driven qubit. We show that the average work performed on the qubit can be used as a diagnostic tool to detect the presence or absence of memory effects.

MHD limits and plasma response in high-beta hybrid operations in ASDEX Upgrade

NASA Astrophysics Data System (ADS)

Igochine, V.; Piovesan, P.; Classen, I. G. J.; Dunne, M.; Gude, A.; Lauber, P.; Liu, Y.; Maraschek, M.; Marrelli, L.; McDermott, R.; Reich, M.; Ryan, D.; Schneller, M.; Strumberger, E.; Suttrop, W.; Tardini, G.; Zohm, H.; The ASDEX Upgrade Team; The EUROfusion MST1 Team

2017-11-01

The improved H-mode scenario (or high β hybrid operations) is one of the main candidates for high-fusion performance tokamak operation that offers a potential steady-state scenario. In this case, the normalized pressure {{β }N} must be maximized and pressure-driven instabilities will limit the plasma performance. These instabilities could have either resistive ((m  =  2, n  =  1) and (3,2) neoclassical tearing modes (NTMs)) or ideal character (n  =  1 ideal kink mode). In ASDEX Upgrade (AUG), the first limit for maximum achievable {{β }N} is set by the NTMs. The application of pre-emptive electron cyclotron current drive at the q  =  2 and q  =  1.5 resonant surfaces reduces this problem, so that higher values of {{β }N} can be reached. AUG experiments have shown that, in spite of the fact that hybrids are mainly limited by NTMs, the proximity to the no-wall limit leads to amplification of the external fields that strongly influence the plasma profiles. For example, rotation braking is observed throughout the plasma and peaks in the core. In this situation, even small external fields are amplified and their effect becomes visible. To quantify these effects, the plasma response to the magnetic fields produced by B-coils is measured as {{β }N} approaches the no-wall limit. These experiments and corresponding modeling allow the identification of the main limiting factors, which depend on the stabilizing influence of the conducting components facing the plasma surface, the existence of external actuators, and the kinetic interaction between the plasma and the marginally stable ideal modes. Analysis of the plasma reaction to external perturbations allowed us to identify optimal correction currents for compensating the intrinsic error field in the device. Such correction, together with the analysis of kinetic effects, will help to increase {{β }N} further in future experiments.

Testosterone Attenuates Age-Related Fall in Aerobic Function in Mobility Limited Older Men With Low Testosterone.

PubMed

Storer, Thomas W; Bhasin, Shalender; Travison, Thomas G; Pencina, Karol; Miciek, Renee; McKinnon, Jennifer; Basaria, Shehzad

2016-06-01

Testosterone increases skeletal muscle mass and strength, but the effects of testosterone on aerobic performance in mobility-limited older men have not been evaluated. To determine the effects of testosterone supplementation on aerobic performance, assessed as peak oxygen uptake (V̇O2peak) and gas exchange lactate threshold (V̇O2θ), during symptom-limited incremental cycle ergometer exercise. Subgroup analysis of the Testosterone in Older Men with Mobility Limitations Trial. Exercise physiology laboratory in an academic medical center. Sixty-four mobility-limited men 65 years or older with low total (100-350 ng/dL) or free (<50 pg/dL) testosterone. Participants were randomized to receive 100-mg testosterone gel or placebo gel daily for 6 months. V̇O2peak and V̇O2θ from a symptom-limited cycle exercise test. Mean (SD) baseline V̇O2peak was 20.5 (4.3) and 19.9 (4.7) mL/kg/min for testosterone and placebo, respectively. V̇O2peak increased by 0.83 (2.4) mL/kg/min in testosterone but decreased by -0.89 (2.5) mL/kg/min in placebo (P = .035); between group difference in change in V̇O2peak was significant (P = .006). This 6-month reduction in placebo was greater than the expected -0.4-mL/kg/min/y rate of decline in the general population. V̇O2θ did not change significantly in testosterone but decreased by 1.1 (1.8) mL/kg/min in placebo, P = .011 for between-group comparisons. Hemoglobin increased by 1.0 ± 3.5 and 0.1 ± 0.8 g/dL in testosterone and placebo groups, respectively. Testosterone supplementation in mobility-limited older men increased hemoglobin and attenuated the age-related declines in V̇O2peak and V̇O2θ. Long-term intervention studies are needed to determine the durability of this effect.

A Limiting Feature of the Mozart Effect: Listening Enhances Mental Rotation Abilities in Non-Musicians but Not Musicians

ERIC Educational Resources Information Center

Aheadi, Afshin; Dixon, Peter; Glover, Scott

2010-01-01

The "Mozart effect" occurs when performance on spatial cognitive tasks improves following exposure to Mozart. It is hypothesized that the Mozart effect arises because listening to complex music activates similar regions of the right cerebral hemisphere as are involved in spatial cognition. A counter-intuitive prediction of this hypothesis (and one…

Increasing On-Task Behavior in Students in a Regular Classroom: Effectiveness of a Self-Management Procedure Using a Tactile Prompt

ERIC Educational Resources Information Center

Moore, Dennis W.; Anderson, Angelika; Glassenbury, Michele; Lang, Russell; Didden, Robert

2013-01-01

Self-management strategies have been shown to be widely effective. However, limited classroom-based research exists involving low performing but developmentally normal high school-aged participants. This study examined the effectiveness of a self-management strategy aimed at increasing on-task behavior in general education classrooms with students…

Effect of Neurocognition and Concussion on Musculoskeletal Injury Risk

PubMed Central

Herman, Daniel C.; Zaremski, Jason L.; Vincent, Heather K.; Vincent, Kevin R.

2015-01-01

Research regarding musculoskeletal injury risk has focused primarily on anatomical, neuromuscular, hormonal, and environmental risk factors; however, subsequent injury risk screening and intervention programs have been largely limited to neuromuscular factors and have faced challenges in both implementation and efficacy. Recent studies indicate that poor neurocognitive performance, either at baseline or in the aftermath of a concussion, is associated with elevated risk of musculoskeletal injury. Despite the relatively limited current understanding regarding the nature of the relationship between different aspects of neurocognitive performance and musculoskeletal injury risk, this is a promising area of research that may yield significant advances in musculoskeletal injury risk stratification, rehabilitation, and prevention. PMID:25968852

Cost-effective particulate control options at Potomac Electric Power Company's Dickerson Station: An integrated approach to current and future particulate limits

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

Christoffersen, S.W.; Rouse, G.T.; Krasnopoler, M.J.

1998-07-01

The Dickerson Generating Station evaluated several particulate control options to identify the most cost-effective option. The study's goals were to: eliminate the particulate scrubber and its high maintenance costs, and incorporate flexibility for low-sulfur coal and possible stricter emission limits. Each of the three Dickerson 190 MW units has a small 37-year-old electrostatic precipitator and a wet particulate scrubber. The study evaluated alternatives to replace the scrubber and enhance ESP performance: Existing ESP alternatives--Extend height of existing ESP; Flue gas conditioning. Scrubber stream alternatives--Partial-flow ESP or pulse jet baghouse. Full-flow alternatives--Supplemental ESP; COHPAC baghouse; replacement ESP or baghouse. A technicalmore » and economic prescreening eliminated some of the options. Capital, operating, and life cycle costs were estimated for the remaining options to determine the most cost-effective alternative. This paper will present the technical and economic evaluations done for this study, including performance and costs.« less

Effects of cognitive impairment and functional limitation on depressive symptoms among community-dwelling older Korean immigrants in the U.S.

PubMed

Kim, Bum Jung; Liu, Lin; Cheung, Christabel; Ahn, Joonhee

2018-01-01

The present study examined the effects of cognitive impairment and functional limitation on depressive symptoms among older Korean American immigrants. The sample was drawn from a cross-sectional survey of 210 older Korean immigrants (aged 65 years or older) in Los Angeles County. Based on robust hierarchical regression, the study found that cognitive ability and functional status were significant explanatory factors related to depressive symptoms among older Korean immigrants. In addition, the interaction of instrumental activities of daily living (IADL) and cognitive function (MMSE) had a significant effect on depressive symptoms. This finding suggests that older Korean immigrants in the U.S. who experience deficits in cognitive function and/or IADL performance are vulnerable to psychological distress as indicated by depressive symptoms. Recommendations include implementing culturally-responsive health interventions aimed at enabling accessibility to dementia care services and supporting improvement of IADL performance among older Korean American immigrants.

The Effect of Age, Race, and Sex on Social Cognitive Performance in Individuals With Schizophrenia.

PubMed

Pinkham, Amy E; Kelsven, Skylar; Kouros, Chrystyna; Harvey, Philip D; Penn, David L

2017-05-01

Age, race, and sex are linked to social cognitive performance among healthy individuals, but whether similar effects are evident in schizophrenia is unknown. Data from 170 individuals with schizophrenia or schizoaffective disorder and 98 healthy controls were used to examine relations between these demographic factors and performance across multiple domains and measures of social cognition. Sex was not related to performance on any domain, but older age was related to poorer emotion recognition from dynamic stimuli in both patients and controls. In patients, older age was also associated with better abilities to decipher hints. Both Caucasian patients and controls performed better than African American individuals on emotion recognition and mental state attribution tasks that use only Caucasian individuals as visual stimuli. Findings suggest rather limited influences of demographic factors but do demonstrate normative age and race effects among patients. Findings also highlight important methodological considerations for measurement of social cognition.

Walking the talk: how effective boards accelerate performance. Interview by Elizabeth Preiss, Ron Shulman, and Patrick O'Callaghan.

PubMed

Bisson, A; Blais, B; Cullen, M; Gagné-Koch, G; Hassen, P C; Hearn, A; Tegenfeldt, J H

1993-01-01

The interviews demonstrated the belief that boards are accountable for ensuring the effective performance of their organizations. A board's obligation and authority is not limited to recruiting, appointing and replacing the organization's CEO and officers. It must also guide, shape, improve and reward what people do on the job. Performance management is not a simple process. It depends on a number of contributing factors operating in concert. To perform well, people must understand what is expected of them, their work context and their role. They must receive appropriate feedback on how they are doing from someone whom they respect and trust, someone with insight into their jobs and authority to manage them. The board's ability and obligation to contribute leadership, to be the primary force steering the organization, rests on the effectiveness with which it is able to play the performance management role.

Fundamentals of Free-Space Optical Communications

NASA Technical Reports Server (NTRS)

Dolinar, Sam; Moision, Bruce; Erkmen, Baris

2012-01-01

Free-space optical communication systems potentially gain many dBs over RF systems. There is no upper limit on the theoretically achievable photon efficiency when the system is quantum-noise-limited: a) Intensity modulations plus photon counting can achieve arbitrarily high photon efficiency, but with sub-optimal spectral efficiency. b) Quantum-ideal number states can achieve the ultimate capacity in the limit of perfect transmissivity. Appropriate error correction codes are needed to communicate reliably near the capacity limits. Poisson-modeled noises, detector losses, and atmospheric effects must all be accounted for: a) Theoretical models are used to analyze performance degradations. b) Mitigation strategies derived from this analysis are applied to minimize these degradations.

The Influence of Restricted Visual Feedback on Dribbling Performance in Youth Soccer Players.

PubMed

Fransen, Job; Lovell, Thomas W J; Bennett, Kyle J M; Deprez, Dieter; Deconinck, Frederik J A; Lenoir, Matthieu; Coutts, Aaron J

2017-04-01

The aim of the current study was to examine the influence of restricted visual feedback using stroboscopic eyewear on the dribbling performance of youth soccer players. Three dribble test conditions were used in a within-subjects design to measure the effect of restricted visual feedback on soccer dribbling performance in 189 youth soccer players (age: 10-18 y) classified as fast, average or slow dribblers. The results showed that limiting visual feedback increased dribble test times across all abilities. Furthermore, the largest performance decrement between stroboscopic and full vision conditions was in fast dribblers, showing that fast dribblers were most affected by reduced visual information. This may be due to a greater dependency on visual feedback at increased speeds, which may limit the ability to maintain continuous control of the ball. These findings may have important implications for the development of soccer dribbling ability.

To Refer or Not To Refer...What Are the Questions? Evaluative Questions for Procedural Implementation of an Effective Prereferral Phase for Culturally Diverse and Limited English Proficient Students.

ERIC Educational Resources Information Center

Ruz, Magdalena

Culturally specific behaviors must be considered in the pre-referral phase of assessing culturally diverse/limited-English-proficient students. Inferences regarding the reasons for students' performance reflect the knowledge base acquired by the school staff concerning a student's culture. Evaluative questions can gather data to assure non-biased…

Splitting attention reduces temporal resolution from 7 Hz for tracking one object to <3 Hz when tracking three.

PubMed

Holcombe, Alex O; Chen, Wei-Ying

2013-01-09

Overall performance when tracking moving targets is known to be poorer for larger numbers of targets, but the specific effect on tracking's temporal resolution has never been investigated. We document a broad range of display parameters for which visual tracking is limited by temporal frequency (the interval between when a target is at each location and a distracter moves in and replaces it) rather than by object speed. We tested tracking of one, two, and three moving targets while the eyes remained fixed. Variation of the number of distracters and their speed revealed both speed limits and temporal frequency limits on tracking. The temporal frequency limit fell from 7 Hz with one target to 4 Hz with two targets and 2.6 Hz with three targets. The large size of this performance decrease implies that in the two-target condition participants would have done better by tracking only one of the two targets and ignoring the other. These effects are predicted by serial models involving a single tracking focus that must switch among the targets, sampling the position of only one target at a time. If parallel processing theories are to explain why dividing the tracking resource reduces temporal resolution so markedly, supplemental assumptions will be required.

The Effect of Pre-Task Planning Time on L2 Learners' Narrative Writing Performance

ERIC Educational Resources Information Center

Seyyedi, Keivan; Ismail, Shaik Abdul Malik Mohamed; Orang, Maryam; Nejad, Maryam Sharafi

2013-01-01

Building on Baddeley's cognitive psychology (2007) and Skehan's Limited Attentional Capacity Model (2009), this article reports a study of the effects of pre-task planning time (strategic planning time) on Malaysian English learners' written narratives elicited by means of a picture composition. 50 first-year undergraduate students studying at…

Extending Cognitive Load Theory to Incorporate Working Memory Resource Depletion: Evidence from the Spacing Effect

ERIC Educational Resources Information Center

Chen, Ouhao; Castro-Alonso, Juan C.; Paas, Fred; Sweller, John

2018-01-01

Depletion of limited working memory resources may occur following extensive mental effort resulting in decreased performance compared to conditions requiring less extensive mental effort. This "depletion effect" can be incorporated into cognitive load theory that is concerned with using the properties of human cognitive architecture,…

Effects of exposure to HZE particles on the cognitive performance of ovariectomized and intact female rats

USDA-ARS?s Scientific Manuscript database

INTRODUCTION It is likely that both male and female astronauts will comprise the crew on exploratory class missions. Despite this, the majority of the research using animal models has utilized male subjects. However, the limited data currently available suggests that the cognitive effects of exposu...

Not All Created Equally: Exploring Calculator Use by Students with Mild Intellectual Disability

ERIC Educational Resources Information Center

Yakubova, Gulnoza; Bouck, Emily C.

2014-01-01

Calculators are widely used in mathematics education, yet limited research examines the effects of calculators for students with mild intellectual disability. An alternating treatments design was used to study the effects of calculator types (i.e., scientific and graphing) on the mathematical performance (i.e., computation and word problems) of…

Effectiveness of Software Training Using Simulations: An Exploratory Study

ERIC Educational Resources Information Center

McElroy, Arnold D., Jr.; Pan, Cheng-Chang

2009-01-01

This study was designed to explore the effectiveness in student performance and confidence of limited and full device simulators. The 30 employees from an information technology company who participated in this study were assigned to one of three groups. Each group received practice for learning a complex software procedure using traditional…

The Effect of a Workload-Preview on Task-Prioritization and Task-Performance

ERIC Educational Resources Information Center

Minotra, Dev

2012-01-01

With increased volume and sophistication of cyber attacks in recent years, maintaining situation awareness and effective task-prioritization strategy is critical to the task of cybersecurity analysts. However, high levels of mental-workload associated with the task of cybersecurity analyst's limits their ability to prioritize tasks.…

Resource- and Approach-Driven Multidimensional Change: Three-Year Effects of School Improvement Grants

ERIC Educational Resources Information Center

Sun, Min; Penner, Emily K.; Loeb, Susanna

2017-01-01

Hoping to spur dramatic school turnaround, the federal government channeled resources to the country's lowest-performing schools through School Improvement Grants (SIG). However, prior research on SIG effectiveness is limited and focuses primarily on student achievement. This study uses a difference-in-differences strategy to estimate program…

An evaluation of training effectiveness of an intelligent tutoring system

NASA Technical Reports Server (NTRS)

Johnson, Debra Steele; Pieper, Kalen F.; Culbert, Chris

1992-01-01

The study evaluated the training effectiveness of an intelligent tutoring system (ITS) for the Remote Manipulator System (RMS). The study examined how well individuals learn the training content and skills from the RMS ITS and to what extent the content and skills learned using the ITS transfer to RMS task performance in the SES, a high fidelity simulator. Three astronauts completed 8 2-hour ITS sessions addressing movement in three coordinate systems, grapple, ungrapple, berth, and unberth procedures, and singularities and reach limits. Their performance was also observed in an SES training session. Performance data were collected using multiple measures: ITS task performance, transfer performance on the SES, a conceptual knowledge test, an opinion survey completed by astronauts, and comments and observations from astronauts and trainers. Results indicated the RMS ITS to be moderately effective and provided evidence of the efficacy of ITS's, in general. Comments and suggestions are provided relating to how the ITS could be improved and to enable decision makers to judge the effectiveness of the RMS ITS.

Climate change affects marine fishes through the oxygen limitation of thermal tolerance.

PubMed

Pörtner, Hans O; Knust, Rainer

2007-01-05

A cause-and-effect understanding of climate influences on ecosystems requires evaluation of thermal limits of member species and of their ability to cope with changing temperatures. Laboratory data available for marine fish and invertebrates from various climatic regions led to the hypothesis that, as a unifying principle, a mismatch between the demand for oxygen and the capacity of oxygen supply to tissues is the first mechanism to restrict whole-animal tolerance to thermal extremes. We show in the eelpout, Zoarces viviparus, a bioindicator fish species for environmental monitoring from North and Baltic Seas (Helcom), that thermally limited oxygen delivery closely matches environmental temperatures beyond which growth performance and abundance decrease. Decrements in aerobic performance in warming seas will thus be the first process to cause extinction or relocation to cooler waters.

Short-Term Effects of Methylphenidate on Math Productivity in Children With Attention-Deficit/Hyperactivity Disorder are Mediated by Symptom Improvements: Evidence From a Placebo-Controlled Trial.

PubMed

Kortekaas-Rijlaarsdam, Anne Fleur; Luman, Marjolein; Sonuga-Barke, Edmund; Bet, Pierre M; Oosterlaan, Jaap

2017-04-01

Although numerous studies report positive effects of methylphenidate on academic performance, the mechanism behind these improvements remains unclear. This study investigates the effects of methylphenidate on academic performance in children with attention-deficit/hyperactivity disorder (ADHD) and the mediating and moderating influence of ADHD severity, academic performance, and ADHD symptom improvement. Sixty-three children with ADHD participated in a double-blind placebo-controlled crossover study comparing the effects of long-acting methylphenidate and placebo. Dependent variables were math, reading, and spelling performance. The ADHD group performance was compared with a group of 67 typically developing children. Methylphenidate improved math productivity and accuracy in children with ADHD. The effect of methylphenidate on math productivity was partly explained by parent-rated symptom improvement, with greater efficacy for children showing more symptom improvement. Further, children showing below-average math performance while on placebo profited more from methylphenidate than children showing above-average math performance. The results from this study indicate positive effects of methylphenidate on academic performance, although these were limited to math abilities. In light of these results, expectations of parents, teachers, and treating physicians about the immediate effects of methylphenidate on academic improvement should be tempered. Moreover, our results implicate that positive effects of methylphenidate on math performance are in part due directly to effects on math ability and in part due to reductions in ADHD symptoms.

Statistical Properties and Pre-Hit Dynamics of Price Limit Hits in the Chinese Stock Markets

PubMed Central

Wan, Yu-Lei; Xie, Wen-Jie; Gu, Gao-Feng; Jiang, Zhi-Qiang; Chen, Wei; Xiong, Xiong; Zhang, Wei; Zhou, Wei-Xing

2015-01-01

Price limit trading rules are adopted in some stock markets (especially emerging markets) trying to cool off traders’ short-term trading mania on individual stocks and increase market efficiency. Under such a microstructure, stocks may hit their up-limits and down-limits from time to time. However, the behaviors of price limit hits are not well studied partially due to the fact that main stock markets such as the US markets and most European markets do not set price limits. Here, we perform detailed analyses of the high-frequency data of all A-share common stocks traded on the Shanghai Stock Exchange and the Shenzhen Stock Exchange from 2000 to 2011 to investigate the statistical properties of price limit hits and the dynamical evolution of several important financial variables before stock price hits its limits. We compare the properties of up-limit hits and down-limit hits. We also divide the whole period into three bullish periods and three bearish periods to unveil possible differences during bullish and bearish market states. To uncover the impacts of stock capitalization on price limit hits, we partition all stocks into six portfolios according to their capitalizations on different trading days. We find that the price limit trading rule has a cooling-off effect (object to the magnet effect), indicating that the rule takes effect in the Chinese stock markets. We find that price continuation is much more likely to occur than price reversal on the next trading day after a limit-hitting day, especially for down-limit hits, which has potential practical values for market practitioners. PMID:25874716

Laterality of brain activity during motor imagery is modulated by the provision of source level neurofeedback.

PubMed

Boe, Shaun; Gionfriddo, Alicia; Kraeutner, Sarah; Tremblay, Antoine; Little, Graham; Bardouille, Timothy

2014-11-01

Motor imagery (MI) may be effective as an adjunct to physical practice for motor skill acquisition. For example, MI is emerging as an effective treatment in stroke neurorehabilitation. As in physical practice, the repetitive activation of neural pathways during MI can drive short- and long-term brain changes that underlie functional recovery. However, the lack of feedback about MI performance may be a factor limiting its effectiveness. The provision of feedback about MI-related brain activity may overcome this limitation by providing the opportunity for individuals to monitor their own performance of this endogenous process. We completed a controlled study to isolate neurofeedback as the factor driving changes in MI-related brain activity across repeated sessions. Eighteen healthy participants took part in 3 sessions comprised of both actual and imagined performance of a button press task. During MI, participants in the neurofeedback group received source level feedback based on activity from the left and right sensorimotor cortex obtained using magnetoencephalography. Participants in the control group received no neurofeedback. MI-related brain activity increased in the sensorimotor cortex contralateral to the imagined movement across sessions in the neurofeedback group, but not in controls. Task performance improved across sessions but did not differ between groups. Our results indicate that the provision of neurofeedback during MI allows healthy individuals to modulate regional brain activity. This finding has the potential to improve the effectiveness of MI as a tool in neurorehabilitation. Copyright © 2014 Elsevier Inc. All rights reserved.

Thermodynamic Analysis of TEG-TEC Device Including Influence of Thomson Effect

NASA Astrophysics Data System (ADS)

Feng, Yuanli; Chen, Lingen; Meng, Fankai; Sun, Fengrui

2018-01-01

A thermodynamic model of a thermoelectric cooler driven by thermoelectric generator (TEG-TEC) device is established considering Thomson effect. The performance is analyzed and optimized using numerical calculation based on non-equilibrium thermodynamic theory. The influence characteristics of Thomson effect on the optimal performance and variable selection are investigated by comparing the condition with and without Thomson effect. The results show that Thomson effect degrades the performance of TEG-TEC device, it decreases the cooling capacity by 27 %, decreases the coefficient of performance (COP) by 19 %, decreases the maximum cooling temperature difference by 11 % when the ratio of thermoelectric elements number is 0.6, the cold junction temperature of thermoelectric cooler (TEC) is 285 K and the hot junction temperature of thermoelectric generator (TEG) is 450 K. Thomson effect degrades the optimal performance of TEG-TEC device, it decreases the maximum cooling capacity by 28 % and decreases the maximum COP by 28 % under the same junction temperatures. Thomson effect narrows the optimal variable range and optimal working range. In the design of the devices, limited-number thermoelectric elements should be more allocated appropriately to TEG when consider Thomson effect. The results may provide some guidelines for the design of TEG-TEC devices.

Vitamin and mineral status: effects on physical performance.

PubMed

Lukaski, Henry C

2004-01-01

Public health recommendations encourage the selection of a balanced diet and increasing physical activity to foster health and well-being. Whereas the adverse effects of restricted intakes of protein, fat, and carbohydrate on physical performance are well known, there is limited information about the impact of low intakes of vitamins and minerals on the exercise capacity and performance of humans. Physically active people generally consume amounts of vitamins and minerals consistent with the recommendations for the general public. However, when intakes are less than recommendations, some noticeable functional impairments occur. Acute or short-term marginal deficiencies, identified by blood biochemical measures of vitamin B status, had no impacts on performance measures. Severe deprivation of folate and vitamin B12 result in anemia and reduce endurance work performance. Evidence of vitamin A and E deficiencies in athletic individuals is lacking apparently because body storage is appreciable. In contrast to vitamins, marginal mineral deficiencies impair performance. Iron deficiency, with or without anemia, impairs muscle function and limits work capacity. Magnesium deprivation increases oxygen requirements to complete submaximal exercise and reduces endurance performance. Use of vitamin and mineral supplements does not improve measures of performance in people consuming adequate diets. Young girls and individuals participating in activities with weight classifications or aesthetic components are prone to nutrient deficiencies because they restrict food intake and specific micronutrient-rich foods. This information will be useful to professionals who counsel physically active people and scientific groups who make dietary recommendations to improve health and optimize genetic potential.

Dynamic probability control limits for risk-adjusted CUSUM charts based on multiresponses.

PubMed

Zhang, Xiang; Loda, Justin B; Woodall, William H

2017-07-20

For a patient who has survived a surgery, there could be several levels of recovery. Thus, it is reasonable to consider more than two outcomes when monitoring surgical outcome quality. The risk-adjusted cumulative sum (CUSUM) chart based on multiresponses has been developed for monitoring a surgical process with three or more outcomes. However, there is a significant effect of varying risk distributions on the in-control performance of the chart when constant control limits are applied. To overcome this disadvantage, we apply the dynamic probability control limits to the risk-adjusted CUSUM charts for multiresponses. The simulation results demonstrate that the in-control performance of the charts with dynamic probability control limits can be controlled for different patient populations because these limits are determined for each specific sequence of patients. Thus, the use of dynamic probability control limits for risk-adjusted CUSUM charts based on multiresponses allows each chart to be designed for the corresponding patient sequence of a surgeon or a hospital and therefore does not require estimating or monitoring the patients' risk distribution. Copyright © 2017 John Wiley & Sons, Ltd. Copyright © 2017 John Wiley & Sons, Ltd.

Massive Memory Revisited: Limitations on Storage Capacity for Object Details in Visual Long-Term Memory

ERIC Educational Resources Information Center

Cunningham, Corbin A.; Yassa, Michael A.; Egeth, Howard E.

2015-01-01

Previous work suggests that visual long-term memory (VLTM) is highly detailed and has a massive capacity. However, memory performance is subject to the effects of the type of testing procedure used. The current study examines detail memory performance by probing the same memories within the same subjects, but using divergent probing methods. The…

Performance evaluation of radiation sensors with internal signal amplification based on the BJT effect

NASA Astrophysics Data System (ADS)

Bosisio, Luciano; Batignani, Giovanni; Bettarini, Stefano; Boscardin, Maurizio; Dalla Betta, Gian-Franco; Giacomini, Gabriele; Piemonte, Claudio; Verzellesi, Giovanni; Zorzi, Nicola

2006-11-01

Prototypes of ionizing radiation detectors with internal signal amplification based on the bipolar transistor effect have been fabricated at ITC-irst (Trento, Italy). Results from the electrical characterization and preliminary functional tests of the devices have been previously reported. Here, we present a more detailed investigation of the performance of this type of detector, with particular attention to their noise and rate limits. Measurements of the signal waveform and of the gain versus frequency dependence are performed by illuminating the devices with, respectively, pulsed or sinusoidally modulated IR light. Pulse height spectra of X-rays from an Am241 source have been taken with very simple front-end electronics (an LF351 operational amplifier) or by directly reading with an oscilloscope the voltage drop across a load resistor connected to the emitter. An equivalent noise charge (referred to input) of 380 electrons r.m.s. has been obtained with the first setup for a small device, with an active area of 0.5×0.5 mm2 and a depleted thickness of 0.6 mm. The corresponding power dissipation in the BJT was 17 μW. The performance limitations of the devices are discussed.

A Preliminary Model for Spacecraft Propulsion Performance Analysis Based on Nuclear Gain and Subsystem Mass-Power Balances

NASA Technical Reports Server (NTRS)

Chakrabarti, S.; Schmidt, G. R.; Thio, Y. C.; Hurst, C. M.

1999-01-01

Rapid transportation of human crews to destinations throughout the solar system will require propulsion systems having not only very high exhaust velocities (i.e., I(sub sp) >= 10(exp 4) to 10(exp 5) sec) but also extremely low mass-power ratios (i.e., alpha <= 10(exp -2) kg/kW). These criteria are difficult to meet with electric propulsion and other power-limited systems, but may be achievable with propulsion concepts that use onboard power to produce a net gain in energy via fusion or some other nuclear process. This paper compares the fundamental performance of these gain-limited systems with that of power-limited systems, and determines from a generic power balance the gains required for ambitious planetary missions ranging up to 100 AU. Results show that energy gain reduces the required effective mass-power ratio of the system, thus enabling shorter trip times than those of power-limited concepts.

First faint dual-field off-axis observations in optical long baseline interferometry

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

Woillez, J.; Wizinowich, P.; Ragland, S.

2014-03-10

Ground-based long baseline interferometers have long been limited in sensitivity in part by the short integration periods imposed by atmospheric turbulence. The first observation fainter than this limit was performed on 2011 January 22 when the Keck Interferometer observed a K = 11.5 target, about 1 mag fainter than its K = 10.3 atmospherically imposed limit; the currently demonstrated limit is K = 12.5. These observations were made possible by the Dual-Field Phase-Referencing (DFPR) instrument, part of the NSF-funded ASTrometry and phase-Referenced Astronomy project; integration times longer than the turbulence time scale are made possible by its ability to simultaneouslymore » measure the real-time effects of the atmosphere on a nearby bright guide star and correct for it on the faint target. We present the implementation of DFPR on the Keck Interferometer. Then, we detail its on-sky performance focusing on the accuracy of the turbulence correction and the resulting fringe contrast stability.« less

Effects of simulated artificial gravity on human performance

NASA Technical Reports Server (NTRS)

Green, J. A.; Peacock, J. L.

1972-01-01

The ability of test subjects to perform operational type tasks was evaluated at rotational rates to 6 rpm and radii to 78 ft (24 m). The tasks included fine motor activity, mental operations, postural equilibrium, cargo handling, radial and tangential locomotion. Performance data indicate that 6 rpm presents a physiological limit at radii to 75 ft (23 m). Radial locomotion was not found to produce excessive adverse stimuli, and tangential locomotion was readily accomplished at walking rates of 2 of 4.8 ft/s (.6 to 1.4 m/s). The absence of vision dramatically reduced an individual's postural equilibrium during rotation. The use of selected anti-motion pharmaceuticals had, generally, a positive effect upon psychomotor performance at 6 rpm, but did not prove to be a panacea for the adverse effects of rotation at this rate.

Numerical investigation of tip clearance effects on the performance of ducted propeller

NASA Astrophysics Data System (ADS)

Ding, Yongle; Song, Baowei; Wang, Peng

2015-09-01

Tip clearance loss is a limitation of the improvement of turbomachine performance. Previous studies show the Tip clearance loss is generated by the leakage flow through the tip clearance, and is roughly linearly proportional to the gap size. This study investigates the tip clearance effects on the performance of ducted propeller. The investigation was carried out by solving the Navier-Stokes equations with the commercial Computational Fluid Dynamic (CFD) code CFX14.5. These simulations were carried out to determine the underlying mechanisms of the tip clearance effects. The calculations were performed at three different chosen advance ratios. Simulation results showed that the tip loss slope was not linearly at high advance due to the reversed pressure at the leading edge. Three type of vortical structures were observed in the tip clearance at different clearance size.

Carbon Nanotubes as FET Channel: Analog Design Optimization considering CNT Parameter Variability

NASA Astrophysics Data System (ADS)

Samar Ansari, Mohd.; Tripathi, S. K.

2017-08-01

Carbon nanotubes (CNTs), both single-walled as well as multi-walled, have been employed in a plethora of applications pertinent to semiconductor materials and devices including, but not limited to, biotechnology, material science, nanoelectronics and nano-electro mechanical systems (NEMS). The Carbon Nanotube Field Effect Transistor (CNFET) is one such electronic device which effectively utilizes CNTs to achieve a boost in the channel conduction thereby yielding superior performance over standard MOSFETs. This paper explores the effects of variability in CNT physical parameters viz. nanotube diameter, pitch, and number of CNT in the transistor channel, on the performance of a chosen analog circuit. It is further shown that from the analyses performed, an optimal design of the CNFETs can be derived for optimizing the performance of the analog circuit as per a given specification set.

Above- and belowground competition from longleaf pine plantations limits performance of reintroduced herbaceous species.

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

T.B. Harrington; C.M. Dagley; M.B. Edwards.

2003-10-01

Although overstory trees limit the abundance and species richness of herbaceous vegetation in longleaf pine (Pinus palustris Mill.) plantations, the responsible mechanisms are poorly understood because of confounding among limiting factors. In fall 1998, research was initiated to determine the separate effects of above- and belowground competition and needlefall from overstory pines on understory plant performance. Three 13- to 15-yr-old plantations near Aiken, SC, were thinned to 0, 25, 50, or 100% of nonthinned basal area (19.5 m2 ha-1). Combinations of trenching (to eliminate root competition) and needlefall were applied to areas within each plot, and containerized seedlings of 14more » perennial herbaceous species and longleaf pine were planted within each. Overstory crown closure ranged from 0 to 81%, and soil water and available nitrogen varied consistently with pine stocking, trenching, or their combination. Cover of planted species decreased an average of 16.5 and 14.1% as a result of above- and below-ground competition, respectively. Depending on species, needlefall effects were positive, negative, or negligible. Results indicate that understory restoration will be most successful when herbaceous species are established within canopy openings (0.1-0.2 ha) managed to minimize negative effects from above- and belowground competition and needlefall.« less

Characteristics of Whipple Shield Performance in the Shatter Regime

NASA Technical Reports Server (NTRS)

Ryan, Shannon; Bjorkman, Michael; Christiansen, Eric L.

2009-01-01

Between the onset of projectile fragmentation and the assumption of rear wall failure due to an impulsive load, multi-wall ballistic limit equations are linearly interpolated to provide reasonable yet conservative predictions of perforation thresholds with conveniently simple mathematics. Although low velocity and hypervelocity regime predictions are based on analytical expressions, there is no such scientific foundation for predictions in the intermediate (or shatter) regime. As the debris flux in low earth orbit (LEO) becomes increasingly dominated by manmade pollution, the profile of micrometeoroid and orbital debris (MMOD) risk shifts continually towards lower velocities. For the International Space Station (ISS), encounter velocities below 7 km/s now constitute approximately 50% of the penetration risk. Considering that the transition velocity from shatter to hypervelocity impact regimes described by common ballistic limit equations (e.g. new non-optimum Whipple shield equation [1]) occurs at 7 km/s, 50% of station risk is now calculated based on failure limit equations with little analytical foundation. To investigate projectile and shield behavior for impact conditions leading to projectile fragmentation and melt, a series of hypervelocity impact tests have been performed on aluminum Whipple shields. In the experiments projectile diameter, bumper thickness, and shield spacing were kept constant, while rear wall thickness was adjusted to determine spallation and perforation limits at various impact velocities and angles. The results, shown in Figure 1 for normal and 45 impacts, demonstrated behavior that was not sufficiently described by the simplified linear interpolation of the NNO equation (also shown in Figure 1). Hopkins et al. [2] investigated the performance of a nominally-identical aluminum Whipple shield, identifying the effects of phase change in the shatter regime. The results (conceptually represented in Figure 2) were found to agree well with those obtained in this study at normal incidence, suggesting that shielding performance in the shatter regime could be well described by considering more complex phase conditions than currently implemented in most BLEs. Furthermore, evidence of these phase effects were found in the oblique test results, providing the basis for an empirical description of these effects that can be applied in MMOD risk assessment software. In this paper, results of the impact experiments are presented, and characteristics of target damage are evaluated. A comparison of intermediate velocity impact failure mechanisms in current BLEs are discussed and compared to the findings of the experimental study. Risk assessment calculations have been made on a simplified structure using currently implemented penetration equations and predicted limits from the experimental program, and the variation in perceived mission risk is discussed. It was found that ballistic limit curves that explicitly incorporated phase change effects within the intermediate regime lead to a decrease in predicted MMOD risk for ISS-representative orbits. When considered for all Whipple-based shielding configurations onboard the ISS, intermediate phase change effects could lead to significant variations in predicted mission risk.

Osteoarthritis year in review: rehabilitation and outcomes.

PubMed

Davis, A M

2012-03-01

This review highlights seminal publications of rehabilitation interventions and outcomes in osteoarthritis (OA) of the hip or knee. Medline, CINAHL, and Embase databases from September 2010 through August 2011 were searched using the key words 'osteoarthritis', rehabilitation, physical therapy, exercise, and outcome(s), limited to human and English. Rehabilitation intervention studies were included if they were randomized trials (RCT), systematic reviews or meta-analyses. Studies of surgical interventions were excluded unless they included evaluation of a rehabilitation intervention. Outcome studies were included if they contributed methodologically to advancing outcome measurement. Reviews of measurement properties of outcomes were excluded. Eight publications were selected and reviewed that relate to interventions evaluating manual therapy in hip or knee OA, tele-rehabilitation and performance and participation measures as outcomes. One systematic review of hip and knee OA, one meta-analysis of knee OA provide limited support for the benefit of manual therapy with exercise for improving pain and function to a lesser extent in the short-term (3 months). Study quality overall was low. One high quality RCT in knee replacement of usual outpatient physiotherapy vs internet-based tele-rehabilitation based on a non-inferiority analysis demonstrated comparable outcomes on Western Ontario McMaster Universities' Osteoarthritis questionnaire (WOMAC) pain and function and performance measures. Three studies demonstrated that observed performance measures such as timed walk tests and stair-climbing and timed-up-and-go measure concepts differ from self-report of difficulty with physical function. Additionally, two studies showed differential times of recovery following total knee replacement (TKR). Two studies evaluated participation. One demonstrated the conceptual distinction of activity limitations and participation and a second re-analyzed trial data from knee OA studies. In one study, there were larger effects in combined activity/participation than for activity alone for arthroscopic lavage compared to intraarticular steroid and, in a second study, the effect was larger for activity with an advanced pharmacy intervention whereas the physiotherapy intervention demonstrated a larger effect for activity/participation. Interventions of manual therapy for hip and knee OA provided limited evidence of effectiveness. These studies are of limited quality due to lack of blinding and disclosure of co-intervention. Tele-rehabilitation may be a viable option to improve access to rehabilitation post joint replacement for those in rural and remote areas. Data continue to support the need to include performance measures as well as patient-reported outcomes in evaluating outcomes in OA. Additionally, measures of participation should be considered as core outcomes. Copyright © 2012 Osteoarthritis Research Society International. Published by Elsevier Ltd. All rights reserved.

An Astronomical Test of CCD Photometric Precision

NASA Technical Reports Server (NTRS)

Koch, David G.; Dunham, Edward W.; Borucki, William J.; Jenkins, Jon M.

2001-01-01

Ground-based differential photometry is limited to a precision of order 10(exp -3) because of atmospheric effects. A space-based photometer should be limited only by the inherent instrument precision and shot noise. Laboratory tests have shown that a precision of order 10-5 is achievable with commercially available charged coupled devices (CCDs). We have proposed to take this one step further by performing measurements at a telescope using a Wollaston prism as a beam splitter First-order atmospheric effects (e.g., extinction) will appear to be identical in the two images of each star formed by the prism and will be removed in the data analysis. This arrangement can determine the precision that is achievable under the influence of second-order atmospheric effects (e.g., variable point-spread function (PSF) from seeing). These telescopic observations will thus provide a lower limit to the precision that can be realized by a space-based differential photometer.

Thermal Evaluation of Fiber Bragg Gratings at Extreme Temperatures

NASA Technical Reports Server (NTRS)

Juergens, Jeffrey; Adamovsky, Grigory; Bhatt, Ramakrishna; Morscher, Gregory; Floyd, Bertram

2005-01-01

The development of integrated fiber optic sensors for use in aerospace health monitoring systems demands that the sensors be able to perform in extreme environments. In order to use fiber optic sensors effectively in an extreme environment one must have a thorough understanding of the sensor's capabilities, limitations, and performance under extreme environmental conditions. This paper reports on our current sensor evaluation examining the performance of freestanding fiber Bragg gratings (FBG) at extreme temperatures. While the ability of FBGs to survive at extreme temperatures has been established, their performance and long term survivability is not well documented. At extreme temperatures the grating structure would be expected to dissipate, degrading the sensors performance and eventually ceasing to return a detectable signal. The fiber jacket will dissipate leaving a brittle, unprotected fiber. For FBGs to be used in aerospace systems their performance and limitations need to be thoroughly understood at extreme temperatures. As the limits of the FBGs performance are pushed the long term survivability and performance of the sensor comes into question. We will not only examine the ability of FBGs to survive extreme temperatures but also look at their performance during many thermal cycles. This paper reports on test results of the performance of thermal cycling commercially available FBGs, at temperatures up to 1000 C, seen in aerospace applications. Additionally this paper will report on the performance of commercially available FBGs held at 1000 C for hundreds of hours. Throughout the evaluation process, various parameters of the FBGs performance were monitored and recorded. Several test samples were subjected to identical test conditions to allow for statistical analysis of the data. Test procedures, calibrations, referencing techniques, performance data, and interpretations and explanations of results are presented in the paper along with directions for future research.

Hilfiker retaining walls with full height cast-in-place panels

DOT National Transportation Integrated Search

1998-02-01

Construction of retaining walls utilizing full height panels introduces a degree of indeterminacy to the structure. The ability to effectively analyze the internal behavior of such systems, and limited field performance, qualifies them as appropriate...

Theoretical detection limit of PIXE analysis using 20 MeV proton beams

NASA Astrophysics Data System (ADS)

Ishii, Keizo; Hitomi, Keitaro

2018-02-01

Particle-induced X-ray emission (PIXE) analysis is usually performed using proton beams with energies in the range 2∼3 MeV because at these energies, the detection limit is low. The detection limit of PIXE analysis depends on the X-ray production cross-section, the continuous background of the PIXE spectrum and the experimental parameters such as the beam currents and the solid angle and detector efficiency of X-ray detector. Though the continuous background increases as the projectile energy increases, the cross-section of the X-ray increases as well. Therefore, the detection limit of high energy proton PIXE is not expected to increase significantly. We calculated the cross sections of continuous X-rays produced in several bremsstrahlung processes and estimated the detection limit of a 20 MeV proton PIXE analysis by modelling the Compton tail of the γ-rays produced in the nuclear reactions, and the escape effect on the secondary electron bremsstrahlung. We found that the Compton tail does not affect the detection limit when a thin X-ray detector is used, but the secondary electron bremsstrahlung escape effect does have an impact. We also confirmed that the detection limit of the PIXE analysis, when used with 4 μm polyethylene backing film and an integrated beam current of 1 μC, is 0.4∼2.0 ppm for proton energies in the range 10∼30 MeV and elements with Z = 16-90. This result demonstrates the usefulness of several 10 MeV cyclotrons for performing PIXE analysis. Cyclotrons with these properties are currently installed in positron emission tomography (PET) centers.

Effects of Motion in the Far Peripheral Visual Field on Cognitive Test Performance and Cognitive Load.

PubMed

Bevilacqua, Andy; Paas, Fred; Krigbaum, Genomary

2016-04-01

Cognitive load theory posits that limited attention is in actuality a limitation in working memory resources. The load theory of selective attention and cognitive control sees the interplay between attention and awareness as separate modifying functions that act on working memory. Reconciling the theoretical differences in these two theories has important implications for learning. Thirty-nine adult participants performed a cognitively demanding test, with and without movement in the far peripheral field. Although the results for movement effects on cognitive load in this experiment were not statistically significant, men spent less time on the cognitive test in the peripheral movement condition than in the conditions without peripheral movement. No such difference was found for women. The implications of these results and recommendations for future research that extends the present study are presented. © The Author(s) 2016.

Mixed-effects location and scale Tobit joint models for heterogeneous longitudinal data with skewness, detection limits, and measurement errors.

PubMed

Lu, Tao

2017-01-01

The joint modeling of mean and variance for longitudinal data is an active research area. This type of model has the advantage of accounting for heteroscedasticity commonly observed in between and within subject variations. Most of researches focus on improving the estimating efficiency but ignore many data features frequently encountered in practice. In this article, we develop a mixed-effects location scale joint model that concurrently accounts for longitudinal data with multiple features. Specifically, our joint model handles heterogeneity, skewness, limit of detection, measurement errors in covariates which are typically observed in the collection of longitudinal data from many studies. We employ a Bayesian approach for making inference on the joint model. The proposed model and method are applied to an AIDS study. Simulation studies are performed to assess the performance of the proposed method. Alternative models under different conditions are compared.

Wave Rotor Research and Technology Development

NASA Technical Reports Server (NTRS)

Welch, Gerard E.

1998-01-01

Wave rotor technology offers the potential to increase the performance of gas turbine engines significantly, within the constraints imposed by current material temperature limits. The wave rotor research at the NASA Lewis Research Center is a three-element effort: 1) Development of design and analysis tools to accurately predict the performance of wave rotor components; 2) Experiments to characterize component performance; 3) System integration studies to evaluate the effect of wave rotor topping on the gas turbine engine system.

Two-IMU FDI performance of the sequential probability ratio test during shuttle entry

NASA Technical Reports Server (NTRS)

Rich, T. M.

1976-01-01

Performance data for the sequential probability ratio test (SPRT) during shuttle entry are presented. Current modeling constants and failure thresholds are included for the full mission 3B from entry through landing trajectory. Minimum 100 percent detection/isolation failure levels and a discussion of the effects of failure direction are presented. Finally, a limited comparison of failures introduced at trajectory initiation shows that the SPRT algorithm performs slightly worse than the data tracking test.

LADAR Performance Simulations with a High Spectral Resolution Atmospheric Transmittance and Radiance Model-LEEDR

DTIC Science & Technology

2012-03-01

such as FASCODE is accomplished. The assessment is limited by the correctness of the models used; validating the models is beyond the scope of this...comparisons with other models and validation against data sets (Snell et al. 2000). 2.3.2 Previous Research Several LADAR simulations have been produced...performance models would better capture the atmosphere physics and climatological effects on these systems. Also, further validation needs to be performed

Chemical calculations on Cray computers

NASA Technical Reports Server (NTRS)

Taylor, Peter R.; Bauschlicher, Charles W., Jr.; Schwenke, David W.

1989-01-01

The influence of recent developments in supercomputing on computational chemistry is discussed with particular reference to Cray computers and their pipelined vector/limited parallel architectures. After reviewing Cray hardware and software the performance of different elementary program structures are examined, and effective methods for improving program performance are outlined. The computational strategies appropriate for obtaining optimum performance in applications to quantum chemistry and dynamics are discussed. Finally, some discussion is given of new developments and future hardware and software improvements.

Cancer and treatment effects on job task performance for gynecological cancer survivors.

PubMed

Nachreiner, Nancy M; Shanley, Ryan; Ghebre, Rahel G

2013-01-01

Over 91,000 new cases of gynecological cancers are expected to be diagnosed in 2013 in the US alone. As cancer detection technology and treatment options improve, the number of working-age cancer survivors continues to grow. To describe US gynecological cancer survivors' perceptions of the effects of cancer and treatment on their job tasks. 104 adult gynecological cancer survivors who were working at the time of their cancer diagnosis, treated at a University-based women's health clinic, diagnosed in the previous 24 months, and spoke English. Women completed written surveys to describe their work experiences following diagnosis. Clinical characteristics were obtained through medical record review. Descriptive statistics and cross tabulations were performed to describe characteristics and associations. Fifteen percent of women had chemotherapy and radiation treatment; 48% had only chemotherapy, 9% only radiation therapy, and 28% had neither. Survivors described the frequency of performing seven job tasks, such as 'intense concentration', 'analyzing data', and 'lifting heavy loads.' Women who had undergone radiation treatment were more likely to indicate limitations for physical tasks; women undergoing chemotherapy were more likely to report limitations in more analytic tasks. Only 29% of women noted an employer-based policy facilitated their return-to-work process. Cancer and treatment have important effects on job performance and may vary by type of treatment. Employer-based policies focusing on improved communication and work accommodations may improve the return to work process.

Evaluation of the Maximum Allowable Cost Program

PubMed Central

Lee, A. James; Hefner, Dennis; Dobson, Allen; Hardy, Ralph

1983-01-01

This article summarizes an evaluation of the Maximum Allowable Cost (MAC)-Estimated Acquisition Cost (EAC) program, the Federal Government's cost-containment program for prescription drugs.1 The MAC-EAC regulations which became effective on August 26, 1976, have four major components: (1) Maximum Allowable Cost reimbursement limits for selected multisource or generically available drugs; (2) Estimated Acquisition Cost reimbursement limits for all drugs; (3) “usual and customary” reimbursement limits for all drugs; and (4) a directive that professional fee studies be performed by each State. The study examines the benefits and costs of the MAC reimbursement limits for 15 dosage forms of five multisource drugs and EAC reimbursement limits for all drugs for five selected States as of 1979. PMID:10309857

Water Stress Affects Development Time but Not Takeoff Performance in the Butterfly Pararge aegeria.

PubMed

Lailvaux, Simon P; Breuker, Casper J; Van Damme, Raoul

Most organisms are limited in the amount and type of resources they are able to extract from the environment. The juvenile environment is particularly important in this regard, as conditions over ontogeny can influence the adult phenotype. Whole-organism performance traits, such as locomotion, are susceptible to such environmental effects, yet the specific biotic and abiotic factors driving performance plasticity have received little attention. We tested whether speckled wood Pararge aegeria L. butterflies reared under conditions of water stress exhibited poorer flight morphology and performance than control individuals. Despite large differences in mortality between treatments, we found no effects of water stress treatment on takeoff performance and only minor treatment effects on flight morphology. However, butterflies reared on water-stressed diets exhibited both significantly greater mortality and longer development times than did control individuals. Pararge aegeria larvae may compensate for this stress by prolonging development, resulting in similar realized performance capacities at least in takeoff performance in surviving adult butterflies; other measures of flight performance remain to be considered. Alternatively, the adult phenotype may be insulated from environmental effects at the larval stage in these insects.

Comparison of oral surgery task performance in a virtual reality surgical simulator and an animal model using objective measures.

PubMed

Ioannou, Ioanna; Kazmierczak, Edmund; Stern, Linda

2015-01-01

The use of virtual reality (VR) simulation for surgical training has gathered much interest in recent years. Despite increasing popularity and usage, limited work has been carried out in the use of automated objective measures to quantify the extent to which performance in a simulator resembles performance in the operating theatre, and the effects of simulator training on real world performance. To this end, we present a study exploring the effects of VR training on the performance of dentistry students learning a novel oral surgery task. We compare the performance of trainees in a VR simulator and in a physical setting involving ovine jaws, using a range of automated metrics derived by motion analysis. Our results suggest that simulator training improved the motion economy of trainees without adverse effects on task outcome. Comparison of surgical technique on the simulator with the ovine setting indicates that simulator technique is similar, but not identical to real world technique.

Programming generality into a performance feedback writing intervention: A randomized controlled trial.

PubMed

Hier, Bridget O; Eckert, Tanya L

2016-06-01

Substantial numbers of students in the United States are performing below grade-level expectations in core academic areas, and these deficits are most pronounced in the area of writing. Although performance feedback procedures have been shown to produce promising short-term improvements in elementary-aged students' writing skills, evidence of maintenance and generalization of these intervention effects is limited. The purpose of this study was to examine the immediate, generalized, and sustained effects of incorporating multiple exemplar training into the performance feedback procedures of a writing intervention using a randomized controlled trial (RCT). Results indicated that although the addition of multiple exemplar training did not improve students' writing performance on measures of stimulus and response generalization, it did result in greater maintenance of intervention effects in comparison to students who received performance feedback without generality programming and students who engaged in weekly writing practice alone. Copyright © 2016 Society for the Study of School Psychology. Published by Elsevier Ltd. All rights reserved.

Composite catalyst surfaces: Effect of inert and active heterogeneities on pattern formation

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

Baer, M.; Bangia, A.K.; Kevrekidis, I.G.

1996-12-05

Spatiotemporal dynamics in reaction-diffusion systems can be altered through the properties (reactivity, diffusivity) of the medium in which they occur. We construct active heterogeneous media (composite catalytic surfaces with inert as well as active illusions) using microelectronics fabrication techniques and study the spatiotemporal dynamics of heterogeneous catalytic reactions on these catalysts. In parallel, we perform simulations as well as numerical stability and bifurcation analysis of these patterns using mechanistic models. At the limit of large heterogeneity `grain size` (compared to the wavelength of spontaneously arising structures) the interaction patterns with inert or active boundaries dominates (e.g., pinning, transmission, and boundarymore » breakup of spirals, interaction of pulses with corners, `pacemaker` effects). At the opposite limit of very small or very finely distributed heterogeneity, effective behavior is observed (slight modulation of pulses, nearly uniform oscillations, effective spirals). Some representative studies of transitions between the two limits are presented. 48 refs., 11 figs.« less

Non-additive effects of pollen limitation and self-incompatibility reduce plant reproductive success and population viability

PubMed Central

Young, Andrew G.; Broadhurst, Linda M.; Thrall, Peter H.

2012-01-01

Background and Aims Mating system is a primary determinant of the ecological and evolutionary dynamics of wild plant populations. Pollen limitation and loss of self-incompatibility genotypes can both act independently to reduce seed set and these effects are commonly observed in fragmented landscapes. This study used a simulation modelling approach to assess the interacting effects of these two processes on plant reproductive performance and population viability for a range of pollination likelihood, self-incompatibility systems and S-allele richness conditions. Methods A spatially explicit, individual-based, genetic and demographic simulation model parameterized to represent a generic self-incompatible, short-lived perennial herb was used to conduct simulation experiments in which pollination probability, self-incompatibility type (gametophytic and sporophytic) and S-allele richness were systematically varied in combination to assess their independent and interacting effects on the demographic response variables of mate availability, seed set, population size and population persistence. Key Results Joint effects of reduced pollination probability and low S-allele richness were greater than independent effects for all demographic response variables except population persistence under high pollinator service (>50 %). At intermediate values of 15–25 % pollination probability, non-linear interactions with S-allele richness generated significant reductions in population performance beyond those expected by the simple additive effect of each independently. This was due to the impacts of reduced effective population size on the ability of populations to retain S alleles and maintain mate availability. Across a limited set of pollination and S-allele conditions (P = 0·15 and S = 20) populations with gametophytic SI showed reduced S-allele erosion relative to those with sporophytic SI, but this had limited effects on individual fecundity and translated into only modest increases in population persistence. Conclusions Interactions between pollen limitation and loss of S alleles have the potential to significantly reduce the viability of populations of a few hundred plants. Population decline may occur more rapidly than expected when pollination probabilities drop below 25 % and S alleles are fewer than 20 due to non-additive interactions. These are likely to be common conditions experienced by plants in small populations in fragmented landscapes and are also those under which differences in response between gameptophytic and sporophtyic systems are observed. PMID:22184620

Non-additive effects of pollen limitation and self-incompatibility reduce plant reproductive success and population viability.

PubMed

Young, Andrew G; Broadhurst, Linda M; Thrall, Peter H

2012-02-01

Mating system is a primary determinant of the ecological and evolutionary dynamics of wild plant populations. Pollen limitation and loss of self-incompatibility genotypes can both act independently to reduce seed set and these effects are commonly observed in fragmented landscapes. This study used a simulation modelling approach to assess the interacting effects of these two processes on plant reproductive performance and population viability for a range of pollination likelihood, self-incompatibility systems and S-allele richness conditions. A spatially explicit, individual-based, genetic and demographic simulation model parameterized to represent a generic self-incompatible, short-lived perennial herb was used to conduct simulation experiments in which pollination probability, self-incompatibility type (gametophytic and sporophytic) and S-allele richness were systematically varied in combination to assess their independent and interacting effects on the demographic response variables of mate availability, seed set, population size and population persistence. Joint effects of reduced pollination probability and low S-allele richness were greater than independent effects for all demographic response variables except population persistence under high pollinator service (>50 %). At intermediate values of 15-25 % pollination probability, non-linear interactions with S-allele richness generated significant reductions in population performance beyond those expected by the simple additive effect of each independently. This was due to the impacts of reduced effective population size on the ability of populations to retain S alleles and maintain mate availability. Across a limited set of pollination and S-allele conditions (P = 0·15 and S = 20) populations with gametophytic SI showed reduced S-allele erosion relative to those with sporophytic SI, but this had limited effects on individual fecundity and translated into only modest increases in population persistence. Interactions between pollen limitation and loss of S alleles have the potential to significantly reduce the viability of populations of a few hundred plants. Population decline may occur more rapidly than expected when pollination probabilities drop below 25 % and S alleles are fewer than 20 due to non-additive interactions. These are likely to be common conditions experienced by plants in small populations in fragmented landscapes and are also those under which differences in response between gameptophytic and sporophtyic systems are observed.

Performance assessment of static lead-lag feedforward controllers for disturbance rejection in PID control loops.

PubMed

Yu, Zhenpeng; Wang, Jiandong

2016-09-01

This paper assesses the performance of feedforward controllers for disturbance rejection in univariate feedback plus feedforward control loops. The structures of feedback and feedforward controllers are confined to proportional-integral-derivative and static-lead-lag forms, respectively, and the effects of feedback controllers are not considered. The integral squared error (ISE) and total squared variation (TSV) are used as performance metrics. A performance index is formulated by comparing the current ISE and TSV metrics to their own lower bounds as performance benchmarks. A controller performance assessment (CPA) method is proposed to calculate the performance index from measurements. The proposed CPA method resolves two critical limitations in the existing CPA methods, in order to be consistent with industrial scenarios. Numerical and experimental examples illustrate the effectiveness of the obtained results. Copyright © 2016 ISA. Published by Elsevier Ltd. All rights reserved.

Genotypic diversity effects on the performance of Taraxacum officinale populations increase with time and environmental favorability.

PubMed

Drummond, Emily B M; Vellend, Mark

2012-01-01

Within-population genetic diversity influences many ecological processes, but few studies have examined how environmental conditions may impact these short-term diversity effects. Over four growing seasons, we followed experimental populations of a clonal, ubiquitous weed, Taraxacum officinale, with different numbers of genotypes in relatively favorable fallow field and unfavorable mowed lawn environmental treatments. Population performance (measured as total leaf area, seed production or biomass) clearly and consistently increased with diversity, and this effect became stronger over the course of the experiment. Diversity effects were stronger, and with different underlying mechanisms, in the fallow field versus the mowed lawn. Large genotypes dominated in the fallow field driving overyielding (via positive selection effects), whereas in the mowed lawn, where performance was limited by regular disturbance, there was evidence for complementarity among genotypes (with one compact genotype in particular performing better in mixture than monoculture). Hence, we predict stronger genotypic diversity effects in environments where intense intraspecific competition enhances genotypic differences. Our four-year field experiment plus seedling establishment trials indicate that genotypic diversity effects have far-reaching and context-dependent consequences across generations.

In-plane Schottky-barrier field-effect transistors based on 1T/2H heterojunctions of transition-metal dichalcogenides

NASA Astrophysics Data System (ADS)

Fan, Zhi-Qiang; Jiang, Xiang-Wei; Luo, Jun-Wei; Jiao, Li-Ying; Huang, Ru; Li, Shu-Shen; Wang, Lin-Wang

2017-10-01

As Moore's law approaches its end, two-dimensional (2D) materials are intensely studied for their potentials as one of the "More than Moore' (MM) devices. However, the ultimate performance limits and the optimal design parameters for such devices are still unknown. One common problem for the 2D-material-based device is the relative weak on-current. In this study, two-dimensional Schottky-barrier field-effect transistors (SBFETs) consisting of in-plane heterojunctions of 1T metallic-phase and 2H semiconducting-phase transition-metal dichalcogenides (TMDs) are studied following the recent experimental synthesis of such devices at a much larger scale. Our ab initio simulation reveals the ultimate performance limits of such devices and offers suggestions for better TMD materials. Our study shows that the Schottky-barrier heights (SBHs) of the in-plane 1T/2H contacts are smaller than the SBHs of out-of-plane contacts, and the contact coupling is also stronger in the in-plane contact. Due to the atomic thickness of the monolayer TMD, the average subthreshold swing of the in-plane TMD-SBFETs is found to be close to the limit of 60 mV/dec, and smaller than that of the out-of-plane TMD-SBFET device. Different TMDs are considered and it is found that the in-plane WT e2-SBFET provides the best performance and can satisfy the performance requirement of the sub-10-nm high-performance transistor outlined by the International Technology Roadmap for Semiconductors, and thus could be developed into a viable sub-10-nm MM device in the future.

Neural suppression of irrelevant information underlies optimal working memory performance.

PubMed

Zanto, Theodore P; Gazzaley, Adam

2009-03-11

Our ability to focus attention on task-relevant information and ignore distractions is reflected by differential enhancement and suppression of neural activity in sensory cortex (i.e., top-down modulation). Such selective, goal-directed modulation of activity may be intimately related to memory, such that the focus of attention biases the likelihood of successfully maintaining relevant information by limiting interference from irrelevant stimuli. Despite recent studies elucidating the mechanistic overlap between attention and memory, the relationship between top-down modulation of visual processing during working memory (WM) encoding, and subsequent recognition performance has not yet been established. Here, we provide neurophysiological evidence in healthy, young adults that top-down modulation of early visual processing (< 200 ms from stimulus onset) is intimately related to subsequent WM performance, such that the likelihood of successfully remembering relevant information is associated with limiting interference from irrelevant stimuli. The consequences of a failure to ignore distractors on recognition performance was replicated for two types of feature-based memory, motion direction and color. Moreover, attention to irrelevant stimuli was reflected neurally during the WM maintenance period as an increased memory load. These results suggest that neural enhancement of relevant information is not the primary determinant of high-level performance, but rather optimal WM performance is dependent on effectively filtering irrelevant information through neural suppression to prevent overloading a limited memory capacity.

Detection methods and performance criteria for genetically modified organisms.

PubMed

Bertheau, Yves; Diolez, Annick; Kobilinsky, André; Magin, Kimberly

2002-01-01

Detection methods for genetically modified organisms (GMOs) are necessary for many applications, from seed purity assessment to compliance of food labeling in several countries. Numerous analytical methods are currently used or under development to support these needs. The currently used methods are bioassays and protein- and DNA-based detection protocols. To avoid discrepancy of results between such largely different methods and, for instance, the potential resulting legal actions, compatibility of the methods is urgently needed. Performance criteria of methods allow evaluation against a common standard. The more-common performance criteria for detection methods are precision, accuracy, sensitivity, and specificity, which together specifically address other terms used to describe the performance of a method, such as applicability, selectivity, calibration, trueness, precision, recovery, operating range, limit of quantitation, limit of detection, and ruggedness. Performance criteria should provide objective tools to accept or reject specific methods, to validate them, to ensure compatibility between validated methods, and be used on a routine basis to reject data outside an acceptable range of variability. When selecting a method of detection, it is also important to consider its applicability, its field of applications, and its limitations, by including factors such as its ability to detect the target analyte in a given matrix, the duration of the analyses, its cost effectiveness, and the necessary sample sizes for testing. Thus, the current GMO detection methods should be evaluated against a common set of performance criteria.

Effect of Detector Dead Time on the Performance of Optical Direct-Detection Communication Links

NASA Technical Reports Server (NTRS)

Chen, C.-C.

1988-01-01

Avalanche photodiodes (APDs) operating in the Geiger mode can provide a significantly improved single-photon detect ion sensitivity over conventional photodiodes. However, the quenching circuit required to remove the excess charge carriers after each photon event can introduce an undesirable dead time into the detection process. The effect of this detector dead time on the performance of a binary pulse-position-modulted (PPM) channel is studied by analyzing the error probability. It is shown that, when back- ground noise is negligible, the performance of the detector with dead time is similar to that o f a quantum-limited receiver. For systems with increasing background intensities, the error rate of the receiver starts to degrade rapidly with increasing dead time. The power penalty due to detector dead time is also evaluated and shown to depend critically on background intensity as well as dead time. Given the expected background strength in an optical channel, therefore, a constraint must be placed on the bandwidth of the receiver to limit the amount of power penalty due to detector dead time.

Performance limits of tunnel transistors based on mono-layer transition-metal dichalcogenides

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

Jiang, Xiang-Wei, E-mail: xwjiang@semi.ac.cn; Li, Shu-Shen; Synergetic Innovation Center of Quantum Information and Quantum Physics, University of Science and Technology of China, Hefei, Anhui 230026

2014-05-12

Performance limits of tunnel field-effect transistors based on mono-layer transition metal dichalcogenides are investigated through numerical quantum mechanical simulations. The atomic mono-layer nature of the devices results in a much smaller natural length λ, leading to much larger electric field inside the tunneling diodes. As a result, the inter-band tunneling currents are found to be very high as long as ultra-thin high-k gate dielectric is possible. The highest on-state driving current is found to be close to 600 μA/μm at V{sub g} = V{sub d} = 0.5 V when 2 nm thin HfO{sub 2} layer is used for gate dielectric, outperforming most of the conventional semiconductor tunnelmore » transistors. In the five simulated transition-metal dichalcogenides, mono-layer WSe{sub 2} based tunnel field-effect transistor shows the best potential. Deep analysis reveals that there is plenty room to further enhance the device performance by either geometry, alloy, or strain engineering on these mono-layer materials.« less

Anaerobic digestion of straw and corn stover: The effect of biological process optimization and pre-treatment on total bio-methane yield and energy performance.

PubMed

Croce, Serena; Wei, Qiao; D'Imporzano, Giuliana; Dong, Renjie; Adani, Fabrizio

2016-12-01

Anaerobic digestion (AD) is a useful method for producing renewable energy/biofuel. Today, biogas production uses a large amount of energy crops (EC), with the effect of increasing AD costs and creating conflict between food/feed vs. energy use. A partial solution to this might be the substitution of EC with agricultural wastes, e.g. straw. Straw and corn stover are widely available in the world and approximately 1600millionMgyear -1 of these substrates are available. Straw can be useful used for biogas production but its characteristics limit its performance so that sometimes the energetic balance can be negative. In this review, the limits for the conversion of this substrate into biogas were investigated and solutions/proposals for getting higher straw biogas production performance are reported. In addition, energetic balances for untreated and pre-treated substrates are reported, giving indicative evaluations of the sustainability of straw and corn stover use for biogas production. Copyright © 2016 Elsevier Inc. All rights reserved.

Effect of detector dead time on the performance of optical direct-detection communication links

NASA Astrophysics Data System (ADS)

Chen, C.-C.

1988-05-01

Avalanche photodiodes (APDs) operating in the Geiger mode can provide a significantly improved single-photon detection sensitivity over conventional photodiodes. However, the quenching circuit required to remove the excess charge carriers after each photon event can introduce an undesirable dead time into the detection process. The effect of this detector dead time on the performance of a binary pulse-position-modulated (PPM) channel is studied by analyzing the error probability. It is shown that, when background noise is negligible, the performance of the detector with dead time is similar to that of a quantum-limited receiver. For systems with increasing background intensities, the error rate of the receiver starts to degrade rapidly with increasing dead time. The power penalty due to detector dead time is also evaluated and shown to depend critically on badkground intensity as well as dead time. Given the expected background strength in an optical channel, therefore, a constraint must be placed on the bandwidth of the receiver to limit the amount of power penalty due to detector dead time.

In-flight performance optimization for rotorcraft with redundant controls

NASA Astrophysics Data System (ADS)

Ozdemir, Gurbuz Taha

A conventional helicopter has limits on performance at high speeds because of the limitations of main rotor, such as compressibility issues on advancing side or stall issues on retreating side. Auxiliary lift and thrust components have been suggested to improve performance of the helicopter substantially by reducing the loading on the main rotor. Such a configuration is called the compound rotorcraft. Rotor speed can also be varied to improve helicopter performance. In addition to improved performance, compound rotorcraft and variable RPM can provide a much larger degree of control redundancy. This additional redundancy gives the opportunity to further enhance performance and handling qualities. A flight control system is designed to perform in-flight optimization of redundant control effectors on a compound rotorcraft in order to minimize power required and extend range. This "Fly to Optimal" (FTO) control law is tested in simulation using the GENHEL model. A model of the UH-60, a compound version of the UH-60A with lifting wing and vectored thrust ducted propeller (VTDP), and a generic compound version of the UH-60A with lifting wing and propeller were developed and tested in simulation. A model following dynamic inversion controller is implemented for inner loop control of roll, pitch, yaw, heave, and rotor RPM. An outer loop controller regulates airspeed and flight path during optimization. A Golden Section search method was used to find optimal rotor RPM on a conventional helicopter, where the single redundant control effector is rotor RPM. The FTO builds off of the Adaptive Performance Optimization (APO) method of Gilyard by performing low frequency sweeps on a redundant control for a fixed wing aircraft. A method based on the APO method was used to optimize trim on a compound rotorcraft with several redundant control effectors. The controller can be used to optimize rotor RPM and compound control effectors through flight test or simulations in order to establish a schedule. The method has been expanded to search a two-dimensional control space. Simulation results demonstrate the ability to maximize range by optimizing stabilator deflection and an airspeed set point. Another set of results minimize power required in high speed flight by optimizing collective pitch and stabilator deflection. Results show that the control laws effectively hold the flight condition while the FTO method is effective at improving performance. Optimizations show there can be issues when the control laws regulating altitude push the collective control towards it limits. So a modification was made to the control law to regulate airspeed and altitude using propeller pitch and angle of attack while the collective is held fixed or used as an optimization variable. A dynamic trim limit avoidance algorithm is applied to avoid control saturation in other axes during optimization maneuvers. Range and power optimization FTO simulations are compared with comprehensive sweeps of trim solutions and FTO optimization shown to be effective and reliable in reaching an optimal when optimizing up to two redundant controls. Use of redundant controls is shown to be beneficial for improving performance. The search method takes almost 25 minutes of simulated flight for optimization to be complete. The optimization maneuver itself can sometimes drive the power required to high values, so a power limit is imposed to restrict the search to avoid conditions where power is more than5% higher than that of the initial trim state. With this modification, the time the optimization maneuver takes to complete is reduced down to 21 minutes without any significant change in the optimal power value.

Quantum limited performance of optical receivers

NASA Astrophysics Data System (ADS)

Farrell, Thomas C.

2018-05-01

While the fundamental performance limit for traditional radio frequency (RF) communications is often set by background noise on the channel, the fundamental limit for optical communications is set by the quantum nature of light. Both types of systems are based on electro-magnetic waves, differing only in carrier frequency. It is, in fact, the frequency that determines which of these limits dominates. We explore this in the first part of this paper. This leads to a difference in methods of analysis of the two different types of systems. While equations predicting the probability of bit error for RF systems are usually based on the signal to background noise ratio, similar equations for optical systems are often based on the physics of the quantum limit and are simply a function of the detected signal energy received per bit. These equations are derived in the second part of this paper for several frequently used modulation schemes: On-off keying (OOK), pulse position modulation (PPM), and binary differential phase shift keying (DPSK). While these equations ignore the effects of background noise and non-quantum internal noise sources in the detector and receiver electronics, they provide a useful bound for obtainable performance of optical communication systems. For example, these equations may be used in initial link budgets to assess the feasibility of system architectures, even before specific receiver designs are considered.

Intelligent advisory speed limit dedication in highway using VANET.

PubMed

Jalooli, Ali; Shaghaghi, Erfan; Jabbarpour, Mohammad Reza; Noor, Rafidah Md; Yeo, Hwasoo; Jung, Jason J

2014-01-01

Variable speed limits (VSLs) as a mean for enhancing road traffic safety are studied for decades to modify the speed limit based on the prevailing road circumstances. In this study the pros and cons of VSL systems and their effects on traffic controlling efficiency are summarized. Despite the potential effectiveness of utilizing VSLs, we have witnessed that the effectiveness of this system is impacted by factors such as VSL control strategy used and the level of driver compliance. Hence, the proposed approach called Intelligent Advisory Speed Limit Dedication (IASLD) as the novel VSL control strategy which considers the driver compliance aims to improve the traffic flow and occupancy of vehicles in addition to amelioration of vehicle's travel times. The IASLD provides the advisory speed limit for each vehicle exclusively based on the vehicle's characteristics including the vehicle type, size, and safety capabilities as well as traffic and weather conditions. The proposed approach takes advantage of vehicular ad hoc network (VANET) to accelerate its performance, in the way that simulation results demonstrate the reduction of incident detection time up to 31.2% in comparison with traditional VSL strategy. The simulation results similarly indicate the improvement of traffic flow efficiency, occupancy, and travel time in different conditions.

Nutrition and Performance at Environmental Extremes

DTIC Science & Technology

1994-01-01

hypocaloric diets .8 More commonly, the upper limit of power output during endurance exercise with intensity greater than 60% VO, max is limited"’ during energy...J. Sports Sci.. 9, 1. 1991. I8. Barclay, C. J. and Lolseile, D. S.. Dependence of muscle fatigue on stimulation protocol: effect of hypocaloric diet ...the energy density of their diets . Under most circumstances, relying upon dietary or body fat stores to meet energy require- ments in high energy

Amplitude-phase cross talk as a deterioration factor of signal-to-noise ratio in phase-detection noise-cancellation technique for spectral pump/probe measurements and compensation of the amplitude-phase cross talk

NASA Astrophysics Data System (ADS)

Seto, Keisuke; Tarumi, Takashi; Tokunaga, Eiji

2018-06-01

Noise cancellation of the light source is an important method to enhance the signal-to-noise ratio (SNR) and facilitate high-speed detection in pump/probe measurements. We developed a method to eliminate the noise for the multichannel spectral pump/probe measurements with a spectral dispersion of a white probe pulse light. In this method, the sample-induced intensity modulation is converted to the phase modulation of the pulse repetition irrespective of the intensity noise of the light source. The SNR is enhanced through the phase detection of the observed signal with the signal synchronized to the pulse repetition serving as the phase reference (synchronized signal). However, the shot-noise limited performance is not achieved with an intense probe light. In this work, we demonstrate that the performance limitation below the shot noise limit is caused by the amplitude-phase cross talk. It converts the amplitude noise into the phase noise and is caused by the space-charge effect in the photodetector, the reverse bias voltage drop across the load impedance, and the phase detection circuit. The phase delay occurs with an intense light at a PIN photodiode, whereas the phase is advanced in an avalanche photodiode. Although the amplitude distortion characteristics also reduce the performance, the distortion effect is equivalent to the amplitude-phase cross talk. We also propose possible ways to compensate the cross talk effect by using the phase modulation of the synchronized signal for the phase detection based on the instantaneous amplitude.

The impact of nontechnical skills on technical performance in surgery: a systematic review.

PubMed

Hull, Louise; Arora, Sonal; Aggarwal, Rajesh; Darzi, Ara; Vincent, Charles; Sevdalis, Nick

2012-02-01

Failures in nontechnical and teamwork skills frequently lie at the heart of harm and near-misses in the operating room (OR). The purpose of this systematic review was to assess the impact of nontechnical skills on technical performance in surgery. MEDLINE, EMBASE, PsycINFO databases were searched, and 2,041 articles were identified. After limits were applied, 341 articles were retrieved for evaluation. Of these, 28 articles were accepted for this review. Data were extracted from the articles regarding sample population, study design and setting, measures of nontechnical skills and technical performance, study findings, and limitations. Of the 28 articles that met inclusion criteria, 21 articles assessed the impact of surgeons' nontechnical skills on their technical performance. The evidence suggests that receiving feedback and effectively coping with stressful events in the OR has a beneficial impact on certain aspects of technical performance. Conversely, increased levels of fatigue are associated with detriments to surgical skill. One article assessed the impact of anesthesiologists' nontechnical skills on anesthetic technical performance, finding a strong positive correlation between the 2 skill sets. Finally, 6 articles assessed the impact of multiple nontechnical skills of the entire OR team on surgical performance. A strong relationship between teamwork failure and technical error was empirically demonstrated in these studies. Evidence suggests that certain nontechnical aspects of performance can enhance or, if lacking, contribute to deterioration of surgeons' technical performance. The precise extent of this effect remains to be elucidated. Copyright © 2012 American College of Surgeons. Published by Elsevier Inc. All rights reserved.

Radar cross section models for limited aspect angle windows

NASA Astrophysics Data System (ADS)

Robinson, Mark C.

1992-12-01

This thesis presents a method for building Radar Cross Section (RCS) models of aircraft based on static data taken from limited aspect angle windows. These models statistically characterize static RCS. This is done to show that a limited number of samples can be used to effectively characterize static aircraft RCS. The optimum models are determined by performing both a Kolmogorov and a Chi-Square goodness-of-fit test comparing the static RCS data with a variety of probability density functions (pdf) that are known to be effective at approximating the static RCS of aircraft. The optimum parameter estimator is also determined by the goodness of-fit tests if there is a difference in pdf parameters obtained by the Maximum Likelihood Estimator (MLE) and the Method of Moments (MoM) estimators.

Flight mechanics and control of escape manoeuvres in hummingbirds. II. Aerodynamic force production, flight control and performance limitations.

PubMed

Cheng, Bo; Tobalske, Bret W; Powers, Donald R; Hedrick, Tyson L; Wang, Yi; Wethington, Susan M; Chiu, George T-C; Deng, Xinyan

2016-11-15

The superior manoeuvrability of hummingbirds emerges from complex interactions of specialized neural and physiological processes with the unique flight dynamics of flapping wings. Escape manoeuvring is an ecologically relevant, natural behaviour of hummingbirds, from which we can gain understanding into the functional limits of vertebrate locomotor capacity. Here, we extend our kinematic analysis of escape manoeuvres from a companion paper to assess two potential limiting factors of the manoeuvring performance of hummingbirds: (1) muscle mechanical power output and (2) delays in the neural sensing and control system. We focused on the magnificent hummingbird (Eugenes fulgens, 7.8 g) and the black-chinned hummingbird (Archilochus alexandri, 3.1 g), which represent large and small species, respectively. We first estimated the aerodynamic forces, moments and the mechanical power of escape manoeuvres using measured wing kinematics. Comparing active-manoeuvring and passive-damping aerodynamic moments, we found that pitch dynamics were lightly damped and dominated by the effect of inertia, while roll dynamics were highly damped. To achieve observed closed-loop performance, pitch manoeuvres required faster sensorimotor transduction, as hummingbirds can only tolerate half the delay allowed in roll manoeuvres. Accordingly, our results suggested that pitch control may require a more sophisticated control strategy, such as those based on prediction. For the magnificent hummingbird, we estimated that escape manoeuvres required muscle mass-specific power 4.5 times that during hovering. Therefore, in addition to the limitation imposed by sensorimotor delays, muscle power could also limit the performance of escape manoeuvres. © 2016. Published by The Company of Biologists Ltd.

What can isolated skeletal muscle experiments tell us about the effects of caffeine on exercise performance?

PubMed Central

Tallis, Jason; Duncan, Michael J; James, Rob S

2015-01-01

Caffeine is an increasingly popular nutritional supplement due to the legal, significant improvements in sporting performance that it has been documented to elicit, with minimal side effects. Therefore, the effects of caffeine on human performance continue to be a popular area of research as we strive to improve our understanding of this drug and make more precise recommendations for its use in sport. Although variations in exercise intensity seems to affect its ergogenic benefits, it is largely thought that caffeine can induce significant improvements in endurance, power and strength-based activities. There are a number of limitations to testing caffeine-induced effects on human performance that can be better controlled when investigating its effects on isolated muscles under in vitro conditions. The hydrophobic nature of caffeine results in a post-digestion distribution to all tissues of the body making it difficult to accurately quantify its key mechanism of action. This review considers the contribution of evidence from isolated muscle studies to our understating of the direct effects of caffeine on muscle during human performance. The body of in vitro evidence presented suggests that caffeine can directly potentiate skeletal muscle force, work and power, which may be important contributors to the performance-enhancing effects seen in humans. PMID:25988508

Effect of hypoxia and hyperoxia on exercise performance in healthy individuals and in patients with pulmonary hypertension: a systematic review.

PubMed

Ulrich, Silvia; Schneider, Simon R; Bloch, Konrad E

2017-12-01

Exercise performance is determined by oxygen supply to working muscles and vital organs. In healthy individuals, exercise performance is limited in the hypoxic environment at altitude, when oxygen delivery is diminished due to the reduced alveolar and arterial oxygen partial pressures. In patients with pulmonary hypertension (PH), exercise performance is already reduced near sea level due to impairments of the pulmonary circulation and gas exchange, and, presumably, these limitations are more pronounced at altitude. In studies performed near sea level in healthy subjects, as well as in patients with PH, maximal performance during progressive ramp exercise and endurance of submaximal constant-load exercise were substantially enhanced by breathing oxygen-enriched air. Both in healthy individuals and in PH patients, these improvements were mediated by a better arterial, muscular, and cerebral oxygenation, along with a reduced sympathetic excitation, as suggested by the reduced heart rate and alveolar ventilation at submaximal isoloads, and an improved pulmonary gas exchange efficiency, especially in patients with PH. In summary, in healthy individuals and in patients with PH, alterations in the inspiratory Po 2 by exposure to hypobaric hypoxia or normobaric hyperoxia reduce or enhance exercise performance, respectively, by modifying oxygen delivery to the muscles and the brain, by effects on cardiovascular and respiratory control, and by alterations in pulmonary gas exchange. The understanding of these physiological mechanisms helps in counselling individuals planning altitude or air travel and prescribing oxygen therapy to patients with PH.

The Effect of Precommitment on Student Achievement within a Technology-Rich Project-Based Learning Environment

ERIC Educational Resources Information Center

Hao, Qiang; Branch, Robert Maribe; Jensen, Lucas

2016-01-01

This study investigated the effects of precommitment on college students' goal setting and academic performance, and students' attitude towards precommitment-related activities. Precommitment refers to a procedure in which students set up learning goals, possibly with a time limit at the beginning of a learning phase, then report the comparison…

Model-based transportation performance : a comparative framework and literature synthesis.

DOT National Transportation Integrated Search

2012-03-01

In an era of limited resources and a proliferation of data, there is increasing pressure to conduct careful evaluations of the economic, environmental, and equity effects of investments and policies that influence transportation and land-use systems....

Rethinking the Rush to Team Up.

ERIC Educational Resources Information Center

Zemke, Ron

1993-01-01

Work teams can be highly motivating and can reduce overhead costs. Teams with clear, limited objectives and the right skills, feedback, and incentives will perform well. Personality difficulties, resistance to change, and lack of training can short circuit their effectiveness. (SK)

Probiotic supplementation in sports and physical exercise: Does it present any ergogenic effect?

PubMed

Coqueiro, Audrey Yule; de Oliveira Garcia, Amanda Beatriz; Rogero, Marcelo Macedo; Tirapegui, Julio

2017-12-01

Probiotics are live microorganisms that promote health benefits to the host. Evidence indicates that some probiotic strains play an immunomodulatory role and reduce the incidence of respiratory and gastrointestinal infections in athletes and in physical activity practitioners. For this reason, probiotic supplementation could indirectly improve exercise performance. However, recent studies have observed direct ergogenic effects of probiotics, but the mechanisms of action are poorly elucidated. In this study, we aim to synthesize available knowledge on the effect of probiotics on physical exercise, identify the mechanisms of action by which probiotics could improve performance directly and indirectly, and verify whether probiotics have any ergogenic effect. The study was performed in the PubMed database in February 2017, without limitation as to the publication period. The keyword combinations used were: 'Probiotics' and 'Sports' ( n = 17 articles), 'Probiotics' and 'Exercise' ( n = 26 articles) and 'Probiotics' and 'Athletes' ( n = 11 articles). Of the 16 studies evaluated, only six applied performance tests, of which only two demonstrated that probiotic supplementation increases performance, but one of them was performed with mice. According to the studies evaluated, probiotic supplementation does not present ergogenic effect, however, considering the small number of studies, this subject should be better investigated.

MPD thruster technology

NASA Technical Reports Server (NTRS)

Myers, Roger M.

1991-01-01

Inhouse magnetoplasmadynamic (MPD) thruster technology is discussed. The study focussed on steady state thrusters at powers of less than 1 MW. Performance measurement and diagnostics technologies were developed for high power thrusters. Also developed was a MPD computer code. The stated goals of the program are to establish: performance and life limitation; influence of applied fields; propellant effects; and scaling laws. The presentation is mostly through graphs and charts.

Effects of a Program of Sport Schools on Development of Social and Psychomotor Skills of People with Autistic Spectrum Disorders: A Pilot Project

ERIC Educational Resources Information Center

López, José María; Moreno-Rodríguez, Ricardo; Alcover, Carlos-María; Garrote, Inmaculada; Sánchez, Sergio

2017-01-01

Individuals with Autistic Spectrum Disorder (ASD) present learning difficulties and limited performance of social skills, besides lower motor skills performance in comparison with their peers. Owing to these difficulties, most of children with ASD are at risk of social exclusion or a poor inclusion due to their behavior, mainly playing with other…

Operator Performance Measures for Assessing Voice Communication Effectiveness

DTIC Science & Technology

1989-07-01

performance and work- load assessment techniques have been based.I Broadbent (1958) described a limited capacity filter model of human information...INFORMATION PROCESSING 20 3.1.1. Auditory Attention 20 3.1.2. Auditory Memory 24 3.2. MODELS OF INFORMATION PROCESSING 24 3.2.1. Capacity Theories 25...Learning 0 Attention * Language Specialization • Decision Making• Problem Solving Auditory Information Processing Models of Processing Ooemtor

Factor-Analysis Methods for Higher-Performance Neural Prostheses

PubMed Central

Santhanam, Gopal; Yu, Byron M.; Gilja, Vikash; Ryu, Stephen I.; Afshar, Afsheen; Sahani, Maneesh; Shenoy, Krishna V.

2009-01-01

Neural prostheses aim to provide treatment options for individuals with nervous-system disease or injury. It is necessary, however, to increase the performance of such systems before they can be clinically viable for patients with motor dysfunction. One performance limitation is the presence of correlated trial-to-trial variability that can cause neural responses to wax and wane in concert as the subject is, for example, more attentive or more fatigued. If a system does not properly account for this variability, it may mistakenly interpret such variability as an entirely different intention by the subject. We report here the design and characterization of factor-analysis (FA)–based decoding algorithms that can contend with this confound. We characterize the decoders (classifiers) on experimental data where monkeys performed both a real reach task and a prosthetic cursor task while we recorded from 96 electrodes implanted in dorsal premotor cortex. The decoder attempts to infer the underlying factors that comodulate the neurons' responses and can use this information to substantially lower error rates (one of eight reach endpoint predictions) by ≲75% (e.g., ∼20% total prediction error using traditional independent Poisson models reduced to ∼5%). We also examine additional key aspects of these new algorithms: the effect of neural integration window length on performance, an extension of the algorithms to use Poisson statistics, and the effect of training set size on the decoding accuracy of test data. We found that FA-based methods are most effective for integration windows >150 ms, although still advantageous at shorter timescales, that Gaussian-based algorithms performed better than the analogous Poisson-based algorithms and that the FA algorithm is robust even with a limited amount of training data. We propose that FA-based methods are effective in modeling correlated trial-to-trial neural variability and can be used to substantially increase overall prosthetic system performance. PMID:19297518

Engineering Nanowire n-MOSFETs at L_{g}<8 nm

NASA Astrophysics Data System (ADS)

Mehrotra, Saumitra R.; Kim, SungGeun; Kubis, Tillmann; Povolotskyi, Michael; Lundstrom, Mark S.; Klimeck, Gerhard

2013-07-01

As metal-oxide-semiconductor field-effect transistors (MOSFET) channel lengths (Lg) are scaled to lengths shorter than Lg<8 nm source-drain tunneling starts to become a major performance limiting factor. In this scenario a heavier transport mass can be used to limit source-drain (S-D) tunneling. Taking InAs and Si as examples, it is shown that different heavier transport masses can be engineered using strain and crystal orientation engineering. Full-band extended device atomistic quantum transport simulations are performed for nanowire MOSFETs at Lg<8 nm in both ballistic and incoherent scattering regimes. In conclusion, a heavier transport mass can indeed be advantageous in improving ON state currents in ultra scaled nanowire MOSFETs.

(abstract) Effect of Electrolyte Composition on Carbon Electrode Performance

NASA Technical Reports Server (NTRS)

Huang, C-K.; Surampudi, S.; Shen, D. H.; Halpert, G.

1993-01-01

Rechargeable lithium cells containing lithium foil anodes are reported to have limited cycle life (at 100% DOD) performance and safety problems. These limitations are understood to be due to the high reactivity of elemental Li with the electrolyte and the formation of high surface area Li during cycling. To mitigate these problems, several lithium alloys and lithium intercalation compounds are being investigated as alternate lithium anode materials. Li(sub x)C has been identified as a promising lithium anode material due to its low equivalent weight, low voltage vs. Li, and improved stability towards various electrolytes. In this paper, we report the results of our studies on the electrolyte evaluation for the Li(sub x)C anode.

High-efficiency cell concepts on low-cost silicon sheets

NASA Technical Reports Server (NTRS)

Bell, R. O.; Ravi, K. V.

1985-01-01

The limitations on sheet growth material in terms of the defect structure and minority carrier lifetime are discussed. The effect of various defects on performance are estimated. Given these limitations designs for a sheet growth cell that will make the best of the material characteristics are proposed. Achievement of optimum synergy between base material quality and device processing variables is proposed. A strong coupling exists between material quality and the variables during crystal growth, and device processing variables. Two objectives are outlined: (1) optimization of the coupling for maximum performance at minimal cost; and (2) decoupling of materials from processing by improvement in base material quality to make it less sensitive to processing variables.

Eeap-lighting survey study at the Red River Army Depot Texarkana, Texas. Final report, 17 October 1994-14 April 1995

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

Pieper, C.A.; Luckett, T.

This energy conservation study was performed by Huitt-Zollars Inc, for the U.S. Army Engineer District (USAED), Fort Worth, under contract number DACAC63-94-D-00l5. The study was conducted at Red River Army Depot (RRAD) in Texarkana, Texas, between October 17, 1994 and April 14, 1995. The site survey and data collection were performed by C.A. Pieper, P.E. and Tom Luckett, Lighting Designer. The purpose of the study was to perform a limited site survey of specific buildings at the facility, identify Conservation Opportunities (ECOs) that exist, and then evaluate these ECOs for technical and economic feasibility. These ECOs were limited to buildingmore » interior lighting and it`s effects on the heating, ventilating and air conditioning (HVAC) systems.« less

Enhanced acoustic sensing through wave compression and pressure amplification in anisotropic metamaterials.

PubMed

Chen, Yongyao; Liu, Haijun; Reilly, Michael; Bae, Hyungdae; Yu, Miao

2014-10-15

Acoustic sensors play an important role in many areas, such as homeland security, navigation, communication, health care and industry. However, the fundamental pressure detection limit hinders the performance of current acoustic sensing technologies. Here, through analytical, numerical and experimental studies, we show that anisotropic acoustic metamaterials can be designed to have strong wave compression effect that renders direct amplification of pressure fields in metamaterials. This enables a sensing mechanism that can help overcome the detection limit of conventional acoustic sensing systems. We further demonstrate a metamaterial-enhanced acoustic sensing system that achieves more than 20 dB signal-to-noise enhancement (over an order of magnitude enhancement in detection limit). With this system, weak acoustic pulse signals overwhelmed by the noise are successfully recovered. This work opens up new vistas for the development of metamaterial-based acoustic sensors with improved performance and functionalities that are highly desirable for many applications.

Virtual data

NASA Astrophysics Data System (ADS)

Bjorklund, E.

1994-12-01

In the 1970s, when computers were memory limited, operating system designers created the concept of "virtual memory", which gave users the ability to address more memory than physically existed. In the 1990s, many large control systems have the potential of becoming data limited. We propose that many of the principles behind virtual memory systems (working sets, locality, caching and clustering) can also be applied to data-limited systems, creating, in effect, "virtual data systems". At the Los Alamos National Laboratory's Clinton P. Anderson Meson Physics Facility (LAMPF), we have applied these principles to a moderately sized (10 000 data points) data acquisition and control system. To test the principles, we measured the system's performance during tune-up, production, and maintenance periods. In this paper, we present a general discussion of the principles of a virtual data system along with some discussion of our own implementation and the results of our performance measurements.

Body size and predatory performance in wolves: is bigger better?

PubMed

MacNulty, Daniel R; Smith, Douglas W; Mech, L David; Eberly, Lynn E

2009-05-01

1. Large body size hinders locomotor performance in ways that may lead to trade-offs in predator foraging ability that limit the net predatory benefit of larger size. For example, size-related improvements in handling prey may come at the expense of pursuing prey and thus negate any enhancement in overall predatory performance due to increasing size. 2. This hypothesis was tested with longitudinal data from repeated observations of 94 individually known wolves (Canis lupus) hunting elk (Cervus elaphus) in Yellowstone National Park, USA. Wolf size was estimated from an individually based sex-specific growth model derived from body mass measurements of 304 wolves. 3. Larger size granted individual wolves a net predatory advantage despite substantial variation in its effect on the performance of different predatory tasks; larger size improved performance of a strength-related task (grappling and subduing elk) but failed to improve performance of a locomotor-related task (selecting an elk from a group) for wolves > 39 kg. 4. Sexual dimorphism in wolf size also explained why males outperformed females in each of the three tasks considered (attacking, selecting, and killing). 5. These findings support the generalization that bigger predators are overall better hunters, but they also indicate that increasing size ultimately limits elements of predatory behaviour that require superior locomotor performance. We argue that this could potentially narrow the dietary niche of larger carnivores as well as limit the evolution of larger size if prey are substantially more difficult to pursue than to handle.

Body size and predatory performance in wolves: Is bigger better?

USGS Publications Warehouse

MacNulty, D.R.; Smith, D.W.; Mech, L.D.; Eberly, L.E.

2009-01-01

Large body size hinders locomotor performance in ways that may lead to trade-offs in predator foraging ability that limit the net predatory benefit of larger size. For example, size-related improvements in handling prey may come at the expense of pursuing prey and thus negate any enhancement in overall predatory performance due to increasing size. 2. This hypothesis was tested with longitudinal data from repeated observations of 94 individually known wolves (Canis lupus) hunting elk (Cervus elaphus) in Yellowstone National Park, USA. Wolf size was estimated from an individually based sex-specific growth model derived from body mass measurements of 304 wolves. 3. Larger size granted individual wolves a net predatory advantage despite substantial variation in its effect on the performance of different predatory tasks; larger size improved performance of a strength-related task (grappling and subduing elk) but failed to improve performance of a locomotor-related task (selecting an elk from a group) for wolves > 39 kg. 4. Sexual dimorphism in wolf size also explained why males outperformed females in each of the three tasks considered (attacking, selecting, and killing). 5. These findings support the generalization that bigger predators are overall better hunters, but they also indicate that increasing size ultimately limits elements of predatory behaviour that require superior locomotor performance. We argue that this could potentially narrow the dietary niche of larger carnivores as well as limit the evolution of larger size if prey are substantially more difficult to pursue than to handle. ?? 2009 British Ecological Society.

Energy saving in WWTP: Daily benchmarking under uncertainty and data availability limitations.

PubMed

Torregrossa, D; Schutz, G; Cornelissen, A; Hernández-Sancho, F; Hansen, J

2016-07-01

Efficient management of Waste Water Treatment Plants (WWTPs) can produce significant environmental and economic benefits. Energy benchmarking can be used to compare WWTPs, identify targets and use these to improve their performance. Different authors have performed benchmark analysis on monthly or yearly basis but their approaches suffer from a time lag between an event, its detection, interpretation and potential actions. The availability of on-line measurement data on many WWTPs should theoretically enable the decrease of the management response time by daily benchmarking. Unfortunately this approach is often impossible because of limited data availability. This paper proposes a methodology to perform a daily benchmark analysis under database limitations. The methodology has been applied to the Energy Online System (EOS) developed in the framework of the project "INNERS" (INNovative Energy Recovery Strategies in the urban water cycle). EOS calculates a set of Key Performance Indicators (KPIs) for the evaluation of energy and process performances. In EOS, the energy KPIs take in consideration the pollutant load in order to enable the comparison between different plants. For example, EOS does not analyse the energy consumption but the energy consumption on pollutant load. This approach enables the comparison of performances for plants with different loads or for a single plant under different load conditions. The energy consumption is measured by on-line sensors, while the pollutant load is measured in the laboratory approximately every 14 days. Consequently, the unavailability of the water quality parameters is the limiting factor in calculating energy KPIs. In this paper, in order to overcome this limitation, the authors have developed a methodology to estimate the required parameters and manage the uncertainty in the estimation. By coupling the parameter estimation with an interval based benchmark approach, the authors propose an effective, fast and reproducible way to manage infrequent inlet measurements. Its use enables benchmarking on a daily basis and prepares the ground for further investigation. Copyright © 2016 Elsevier Inc. All rights reserved.

Non-Foster Circuits for High Performance Antennas: Advantages and Practical Limitations

NASA Astrophysics Data System (ADS)

Jacob, Minu Mariam

The demand for miniaturized, broadband communication systems has created a need for electrically small, broadband antennas. However, all passive electrically small antennas have a fundamental gain-bandwidth limitation related to their electrical size, as first described by Wheeler and Chu. This limitation can be overcome using active non-Foster circuits (negative inductors and/or negative capacitors), which can deliver a broadband input match with active matching techniques, or can help reduce phase dispersion using negative delay effects. This thesis will illustrate the advantages of non-Foster circuits in obtaining broadband small antennas, in addition to examining their practical limitations due to noise in receive applications, and nonlinearity in transmit applications.

A new method for analysis of limit cycle behavior of the NASA/JPL 70-meter antenna axis servos

NASA Technical Reports Server (NTRS)

Hill, R. E.

1989-01-01

A piecewise linear method of analyzing the effects of discontinuous nonlinearities on control system performance is described. The limit cycle oscillatory behavior of the system resulting from the nonlinearities is described in terms of a sequence of linear system transient responses. The equations are derived which relate the initial and the terminal conditions of successive transients and the boundary conditions imposed by the non-linearities. The method leads to a convenient computation algorithm for prediction of limit cycle characteristics resulting from discontinuous nonlinearities such as friction, deadzones, and hysteresis.

Flight simulator platform motion and air transport pilot training

NASA Technical Reports Server (NTRS)

Lee, Alfred T.; Bussolari, Steven R.

1987-01-01

The effect of a flight simulator platform motion on the performance and training of a pilot was evaluated using subjective ratings and objective performance data obtained on experienced B-727 pilots and pilots with no prior heavy aircraft flying experience flying B-727-200 aircraft simulator used by the FAA in the upgrade and transition training for air carrier operations. The results on experienced pilots did not reveal any reliable effects of wide variations in platform motion design. On the other hand, motion variations significantly affected the behavior of pilots without heavy-aircraft experience. The effect was limited to pitch attitude control inputs during the early phase of landing training.

The multi-axis vibration environment and man.

PubMed

Lovesey, E J

1970-12-01

Many investigations into the effects of vibration on man have been performed since Mallock's first study of London Underground vibrations in 1902. The vibration research has tended to be confined to the vertical (heave) axis, yet recent experiments have indicated that low frequency vibration along the lateral (sway) axis has a greater adverse effect upon comfort and performance. Measurements of the vibration environments in current forms of transport including motor vehicles, hovercraft and aircraft etc have shown that appreciable quantities of vibration along all three axes exist. Further vibration research should consider the effects of multi-axis vibrations upon man rather than limit tests to single axis vibration.

Describing-function analysis of a ripple regulator with slew-rate limits and time delays

NASA Technical Reports Server (NTRS)

Wester, Gene W.

1990-01-01

The effects of time delays and slew-rate limits on the steady-state operating points and performance of a free-running ripple regulator are evaluated using describing-function analysis. The describing function of an ideal comparator (no time delays or slew rate limits) has no phase shift and is independent of frequency. It is found that turn-on delay and turn-off delay have different effects on gain and phase and cannot be combined. Comparator hysteresis affects both gain and phase; likewise, time delays generally affect both gain and phase. It is found that the effective time delay around the feedback loop is one half the sum of turn-on and turn-off delays, regardless of whether the delays are caused by storage time or slew rate limits. Expressions are formulated for the switching frequency, switch duty ratio, dc output, and output ripple. For the case of no hysteresis, a simple, graphical solution for the switching frequency is possible, and the resulting switching frequency is independent of first-order variations of input or load.

Effect of dewatering on seismic performance of multi-anchor wall due to high ground water level

NASA Astrophysics Data System (ADS)

Kobayashi, Makoto; Miura, Kinya; Konami, Takeharu; Hayashi, Taketo; Sato, Hiroki

2017-10-01

Previous research reported that the ground water in the backfill of reinforced soil wall made it deteriorate. According to the damage investigation of Great East Earthquake 2011, the reinforced soil structure due to high ground water level by seismic wave were deformed remarkably. Some of them classified ultimate limit state or restorability limit state. However, more than 90% of reinforced soil structure, which suffered from this earthquake, were classified into no damage condition. Therefore, it is necessary that the seismic behaviors of multi-anchor wall due to seepage flow should be clarified in order to adopt the performance-based design in such reinforced soil structure. In this study, a series of centrifugal shaking table tests were conducted to investigate the seismic behavior of multi-anchor wall due to high ground water level. The reinforced drainage pipes were installed into the backfill in order to verify the dewatering effect and additional reinforcement. Furthermore, to check only the dewatering effect, the model tests was carried out with several ground water table that was modeled the case reinforced drainage pipes installed. The test results show unique behavior of reinforced region that moved integrally. This implies that the reinforced region has been behaved as if it became one mass, and this behavior make this structure increase seismic performance. Thus, the effectiveness of dewatering was observed remarkably because of decreasing the inertial force during earthquake.

Performance of the split-symbol moments SNR estimator in the presence of inter-symbol interference

NASA Technical Reports Server (NTRS)

Shah, B.; Hinedi, S.

1989-01-01

The Split-Symbol Moments Estimator (SSME) is an algorithm that is designed to estimate symbol signal-to-noise ratio (SNR) in the presence of additive white Gaussian noise (AWGN). The performance of the SSME algorithm in band-limited channels is examined. The effects of the resulting inter-symbol interference (ISI) are quantified. All results obtained are in closed form and can be easily evaluated numerically for performance prediction purposes. Furthermore, they are validated through digital simulations.

Extending the limits of operating pressure of narrow-bore column liquid chromatography instrumentation.

PubMed

Pauw, Ruben De; Degreef, Bart; Ritchie, Harald; Eeltink, Sebastiaan; Desmet, Gert; Broeckhoven, Ken

2014-06-20

The increase of the operating pressure in Liquid Chromatography, has been one of the crucial steps toward faster and more efficient separations. In the present contribution, it was investigated if the pressure limits for narrow-bore columns (2.1mm ID) could be increased beyond those of commercially available (1300bar) instrumentation without performance loss. Whereas previous studies applying pressures higher than 2000bar were limited to the use of columns with a diameter smaller or equal to 1mm, it is a difficult feat to expand this to 2.1mm ID given that viscous-heating effects increase according to the fifth power of the column radius. A prototype LC set-up was realized, allowing to operate at pressures up to 2600bar (260MPa) for large separation volumes (>5mL). The performance of an in-house-built injector was compared at 800bar to commercially available injectors, yielding equal performance but twice the maximum pressure rating. The performance of (coupled) custom columns packed with fully porous and superficially porous particles were assessed at ultra-high-pressure conditions. Increasing the inlet pressure from 800 to 2400bar and scaling the column length proportionally (from 150mm to 450mm), resulted in the theoretically expected linear increase in plate count from 20,000 to 59,000. A maximum plate number of 81,000 was realized using a 600mm long (coupled) column at 2600bar. Viscous-heating effects were diminished by insulating coupled columns and applying an intermediate-cooling strategy in a forced-air oven. Copyright © 2014 Elsevier B.V. All rights reserved.

RADIOISOTOPE-DRIVEN DUAL-MODE PROPULSION SYSTEM FOR CUBESAT-SCALE PAYLOADS TO THE OUTER PLANETS

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

N. D. Jerred; T. M. Howe; S. D. Howe

It is apparent the cost of planetary exploration is rising as mission budgets declining. Currently small scientific beds geared to performing limited tasks are being developed and launched into low earth orbit (LEO) in the form of small-scale satellite units, i.e., CubeSats. These micro- and nano-satellites are gaining popularity among the university and science communities due to their relatively low cost and design flexibility. To date these small units have been limited to performing tasks in LEO utilizing solar-based power. If a reasonable propulsion system could be developed, these CubeSat platforms could perform exploration of various extra-terrestrial bodies within themore » solar system engaging a broader range of researchers. Additionally, being mindful of mass, smaller cheaper launch vehicles (approximately 1,000 kgs to LEO) can be targeted. Thus, in effect, allows for beneficial exploration to be conducted within limited budgets. Researchers at the Center for Space Nuclear Research (CSNR) are proposing a low mass, radioisotope-based, dual-mode propulsion system capable of extending the exploration realm of these CubeSats out of LEO.« less

Node Immunization with Time-Sensitive Restrictions.

PubMed

Cui, Wen; Gong, Xiaoqing; Liu, Chen; Xu, Dan; Chen, Xiaojiang; Fang, Dingyi; Tang, Shaojie; Wu, Fan; Chen, Guihai

2016-12-15

When we encounter a malicious rumor or an infectious disease outbreak, immunizing k nodes of the relevant network with limited resources is always treated as an extremely effective method. The key challenge is how we can insulate limited nodes to minimize the propagation of those contagious things. In previous works, the best k immunised nodes are selected by learning the initial status of nodes and their strategies even if there is no feedback in the propagation process, which eventually leads to ineffective performance of their solutions. In this paper, we design a novel vaccines placement strategy for protecting much more healthy nodes from being infected by infectious nodes. The main idea of our solution is that we are not only utilizing the status of changing nodes as auxiliary knowledge to adjust our scheme, but also comparing the performance of vaccines in various transmission slots. Thus, our solution has a better chance to get more benefit from these limited vaccines. Extensive experiments have been conducted on several real-world data sets and the results have shown that our algorithm has a better performance than previous works.

Node Immunization with Time-Sensitive Restrictions

PubMed Central

Cui, Wen; Gong, Xiaoqing; Liu, Chen; Xu, Dan; Chen, Xiaojiang; Fang, Dingyi; Tang, Shaojie; Wu, Fan; Chen, Guihai

2016-01-01

When we encounter a malicious rumor or an infectious disease outbreak, immunizing k nodes of the relevant network with limited resources is always treated as an extremely effective method. The key challenge is how we can insulate limited nodes to minimize the propagation of those contagious things. In previous works, the best k immunised nodes are selected by learning the initial status of nodes and their strategies even if there is no feedback in the propagation process, which eventually leads to ineffective performance of their solutions. In this paper, we design a novel vaccines placement strategy for protecting much more healthy nodes from being infected by infectious nodes. The main idea of our solution is that we are not only utilizing the status of changing nodes as auxiliary knowledge to adjust our scheme, but also comparing the performance of vaccines in various transmission slots. Thus, our solution has a better chance to get more benefit from these limited vaccines. Extensive experiments have been conducted on several real-world data sets and the results have shown that our algorithm has a better performance than previous works. PMID:27983680

Practical performance of real-time shot-noise measurement in continuous-variable quantum key distribution

NASA Astrophysics Data System (ADS)

Wang, Tao; Huang, Peng; Zhou, Yingming; Liu, Weiqi; Zeng, Guihua

2018-01-01

In a practical continuous-variable quantum key distribution (CVQKD) system, real-time shot-noise measurement (RTSNM) is an essential procedure for preventing the eavesdropper exploiting the practical security loopholes. However, the performance of this procedure itself is not analyzed under the real-world condition. Therefore, we indicate the RTSNM practical performance and investigate its effects on the CVQKD system. In particular, due to the finite-size effect, the shot-noise measurement at the receiver's side may decrease the precision of parameter estimation and consequently result in a tight security bound. To mitigate that, we optimize the block size for RTSNM under the ensemble size limitation to maximize the secure key rate. Moreover, the effect of finite dynamics of amplitude modulator in this scheme is studied and its mitigation method is also proposed. Our work indicates the practical performance of RTSNM and provides the real secret key rate under it.

Development of bimanual performance in young children with cerebral palsy.

PubMed

Klevberg, Gunvor L; Elvrum, Ann-Kristin G; Zucknick, Manuela; Elkjaer, Sonja; Østensjø, Sigrid; Krumlinde-Sundholm, Lena; Kjeken, Ingvild; Jahnsen, Reidun

2018-05-01

To describe the development of bimanual performance among young children with unilateral or bilateral cerebral palsy (CP). A population-based sample of 102 children (53 males, 49 females), median age 28.5 months (interquartile range [IQR] 16mo) at first assessment and 47 months (IQR 18mo) at last assessment, was assessed half-yearly with the Assisting Hand Assessment (AHA) or the Both Hands Assessment (BoHA) for a total of 329 assessments. Developmental limits and rates were estimated by nonlinear mixed-effects models. Developmental trajectories were compared between levels of manual ability (Mini-Manual Ability Classification System [Mini-MACS] and MACS) and AHA or BoHA performance at 18 months of age (AHA-18/BoHA-18) for both CP subgroups, and additionally between children with bilateral CP with symmetric or asymmetric hand use. For both CP subgroups, children classified in Mini-MACS/MACS level I, and those with high AHA-18 or BoHA-18 reached the highest limits of performance. For children with bilateral CP the developmental change was small, and children with symmetric hand use reached the highest limits. Mini-MACS/MACS levels and AHA-18 or BoHA-18 distinguished between various developmental trajectories both for children with unilateral and bilateral CP. Children with bilateral CP changed their performance to a smaller extent than children with unilateral CP. Manual Ability Classification System levels and Assisting Hand Assessment/Both Hands Assessment performance at 18 months are important predictors of hand use development in cerebral palsy (CP). Children with bilateral CP improved less than those with unilateral CP. Children with bilateral CP and symmetric hand use reached higher limits than those with asymmetry. © 2018 Mac Keith Press.

Topological properties of the limited penetrable horizontal visibility graph family

NASA Astrophysics Data System (ADS)

Wang, Minggang; Vilela, André L. M.; Du, Ruijin; Zhao, Longfeng; Dong, Gaogao; Tian, Lixin; Stanley, H. Eugene

2018-05-01

The limited penetrable horizontal visibility graph algorithm was recently introduced to map time series in complex networks. In this work, we extend this algorithm to create a directed-limited penetrable horizontal visibility graph and an image-limited penetrable horizontal visibility graph. We define two algorithms and provide theoretical results on the topological properties of these graphs associated with different types of real-value series. We perform several numerical simulations to check the accuracy of our theoretical results. Finally, we present an application of the directed-limited penetrable horizontal visibility graph to measure real-value time series irreversibility and an application of the image-limited penetrable horizontal visibility graph that discriminates noise from chaos. We also propose a method to measure the systematic risk using the image-limited penetrable horizontal visibility graph, and the empirical results show the effectiveness of our proposed algorithms.

Enhanced optical limiting effects in a double-decker bis(phthalocyaninato) rare earth complex using radially polarized beams

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

Wu, Jia-Lu; Gu, Bing, E-mail: gubing@seu.edu.cn; Liu, Dahui

2014-10-27

Optical limiting (OL) effects can be enhanced by exploiting various limiting mechanisms and by designing nonlinear optical materials. In this work, we present the large enhancement of OL effects by manipulating the polarization distribution of the light field. Theoretically, we develop the Z-scan and nonlinear transmission theories on a two-photon absorber under the excitation of cylindrical vector beams. It is shown that both the sensitivity of Z-scan technique and the OL effect using radially polarized beams have the large enhancement compared with that using linearly polarized beams (LPBs). Experimentally, we investigate the nonlinear absorption properties of a double-decker Pr[Pc(OC{sub 8}H{submore » 17}){sub 8}]{sub 2} rare earth complex by performing Z-scan measurements with femtosecond-pulsed radially polarized beams at 800 nm wavelength. The observed two-photon absorption process, which originates from strong intramolecular π–π interaction, is exploited for OL application. The results demonstrate the large enhancement of OL effects using radially polarized beams instead of LPBs.« less

Physical performance limitations among adult survivors of childhood brain tumors.

PubMed

Ness, Kirsten K; Morris, E Brannon; Nolan, Vikki G; Howell, Carrie R; Gilchrist, Laura S; Stovall, Marilyn; Cox, Cheryl L; Klosky, James L; Gajjar, Amar; Neglia, Joseph P

2010-06-15

Young adult survivors of childhood brain tumors (BTs) may have late effects that compromise physical performance and everyday task participation. The objective of this study was to evaluate muscle strength, fitness, physical performance, and task participation among adult survivors of childhood BTs. In-home evaluations and interviews were conducted for 156 participants (54% men). Results on measures of muscle strength, fitness, physical performance, and participation were compared between BT survivors and members of a population-based comparison group by using chi-square statistics and 2-sample t tests. Associations between late effects and physical performance and between physical performance and participation were evaluated in regression models. : The median age of BT survivors was 22 years (range, 18-58 years) at the time of the current evaluation, and they had survived for a median of 14.7 years (range, 6.5-45.9 years) postdiagnosis. Survivors had lower estimates of grip strength (women, 24.7 + or - 9.2 kg vs 31.5 + or - 5.8 kg; men, 39.0 + or - 12.2 kg vs 53.0 + or - 10.1 kg), knee extension strength (women, 246.6 + or - 95.5 Newtons [N] vs 331.5 + or - 5.8 N; men, 304.7 + or - 116.4 N vs 466.6 + or - 92.1 N), and peak oxygen uptake (women, 25.1 + or - 8.8 mL/kg per minute vs 31.3 + or - 5.1 mL/kg per minute; men, 24.6 + or - 9.5 mL/kg per minute vs 33.2 + or - 3.4 mL/kg per minute) than members of the population-based comparison group. Physical performance was lower among survivors and was associated with not living independently (odds ratio [OR], 5.0; 95% confidence interval [CI], 2.0-12.2) and not attending college (OR, 2.3; 95% CI 1.2-4.4). Muscle strength and fitness values among BT survivors were similar to those among individuals aged > or = 60 years and were associated with physical performance limitations. Physical performance limitations were associated with poor outcomes in home and school environments. The current data indicated an opportunity for interventions targeted at improving long-term physical function in this survivor population.

Using the Networked Fire Chief for ego-depletion research: measuring dynamic decision-making effort and performance.

PubMed

Barber, Larissa K; Smit, Brandon W

2014-01-01

This study replicated ego-depletion predictions from the self-control literature in a computer simulation task that requires ongoing decision-making in relation to constantly changing environmental information: the Network Fire Chief (NFC). Ego-depletion led to decreased self-regulatory effort, but not performance, on the NFC task. These effects were also buffered by task enjoyment so that individuals who enjoyed the dynamic decision-making task did not experience ego-depletion effects. These findings confirm that past ego-depletion effects on decision-making are not limited to static or isolated decision-making tasks and can be extended to dynamic, naturalistic decision-making processes more common to naturalistic settings. Furthermore, the NFC simulation provides a methodological mechanism for independently measuring effort and performance when studying ego-depletion.

Thruster Limitation Consideration for Formation Flight Control

NASA Technical Reports Server (NTRS)

Xu, Yunjun; Fitz-Coy, Norman; Mason, Paul

2003-01-01

Physical constraints of any real system can have a drastic effect on its performance. Some of the more recognized constraints are actuator and sensor saturation and bandwidth, power consumption, sampling rate (sensor and control-loop) and computation limits. These constraints can degrade system s performance, such as settling time, overshoot, rising time, and stability margins. In order to address these issues, researchers have investigated the use of robust and nonlinear controllers that can incorporate uncertainty and constraints into a controller design. For instance, uncertainties can be addressed in the synthesis model used in such algorithms as H(sub infinity), or mu. There is a significant amount of literature addressing this type of problem. However, there is one constraint that has not often been considered; that is, actuator authority resolution. In this work, thruster resolution and controller schemes to compensate for this effect are investigated for position and attitude control of a Low Earth Orbit formation flight system In many academic problems, actuators are assumed to have infinite resolution. In real system applications, such as formation flight systems, the system actuators will not have infinite resolution. High-precision formation flying requires the relative position and the relative attitude to be controlled on the order of millimeters and arc-seconds, respectively. Therefore, the minimum force resolution is a significant concern in this application. Without the sufficient actuator resolution, the system may be unable to attain the required pointing and position precision control. Furthermore, fuel may be wasted due to high-frequency chattering phenomena when attempting to provide a fine control with inadequate actuators. To address this issue, a Sliding Mode Controller is developed along with the boundary Layer Control to provide the best control resolution constraints. A Genetic algorithm is used to optimize the controller parameters according to the states error and fuel consumption criterion. The tradeoffs and effects of the minimum force limitation on performance are studied and compared to the case without the limitation. Furthermore, two methods are proposed to reduce chattering and improve precision.

Sodium effects on mechanical performance and consideration in high temperature structural design for advanced reactors

NASA Astrophysics Data System (ADS)

Natesan, K.; Li, Meimei; Chopra, O. K.; Majumdar, S.

2009-07-01

Sodium environmental effects are key limiting factors in the high temperature structural design of advanced sodium-cooled reactors. A guideline is needed to incorporate environmental effects in the ASME design rules to improve the performance reliability over long operating times. This paper summarizes the influence of sodium exposure on mechanical performance of selected austenitic stainless and ferritic/martensitic steels. Focus is on Type 316SS and mod.9Cr-1Mo. The sodium effects were evaluated by comparing the mechanical properties data in air and sodium. Carburization and decarburization were found to be the key factors that determine the tensile and creep properties of the steels. A beneficial effect of sodium exposure on fatigue life was observed under fully reversed cyclic loading in both austenitic stainless steels and ferritic/martensitic steels. However, when hold time was applied during cyclic loading, the fatigue life was significantly reduced. Based on the mechanical performance of the steels in sodium, consideration of sodium effects in high temperature structural design of advanced fast reactors is discussed.

Using the balanced scorecard to measure Chinese and Japanese hospital performance.

PubMed

Chen, Xiao-yun; Yamauchi, Kazunobu; Kato, Ken; Nishimura, Akio; Ito, Katuski

2006-01-01

The objective of the paper is to confirm the feasibility and value of using the balanced scorecard (BSC) to measure performance in two hospitals in different countries. One hospital from China and another from Japan were chosen and key indicators were selected according to the BSC framework. A comparative hospital performance measurement model was set up using the BSC framework to comprehensively compare hospital performance in two countries. The BSC was found to be effective for underlining existing problems and identifying opportunities for improvements. The BSC also revealed the hospitals' contribution to performance improvement of each country's total health system. Hospital performance comparisons between countries using the BSC depend on the selection of feasible and appropriate key performance indicators, which is occasionally limited by data collection problems. The first use of the BSC to compare hospital performance between China and Japan shows benefits that not only suggests performance improvements in individual hospitals but also reveals effective health factors allowing implementation of valid national health policies.

Waggle dance effect: dancing in autumn reduces the mass loss of a honeybee colony.

PubMed

Okada, Ryuichi; Akamatsu, Tadaaki; Iwata, Kanako; Ikeno, Hidetoshi; Kimura, Toshifumi; Ohashi, Mizue; Aonuma, Hitoshi; Ito, Etsuro

2012-05-15

A honeybee informs her nestmates about the location of a profitable food source that she has visited by means of a waggle dance: a round dance and a figure-of-eight dance for a short- and long-distance food source, respectively. Consequently, the colony achieves an effective collection of food. However, it is still not fully understood how much effect the dance behavior has on the food collection, because most of the relevant experiments have been performed only in limited locations under limited experimental conditions. Here, we examined the efficacy of the waggle dances by physically preventing bees from dancing and then analyzing the changes in daily mass of the hive as an index of daily food collection. To eliminate place- and year-specific effects, the experiments were performed under fully natural conditions in three different cities in Japan from mid September to early October in three different years. Because the experiments were performed in autumn, all six of the tested colonies lost mass on most of the experimental days. When the dance was prevented, the daily reduction in mass change was greater than when the dance was allowed, i.e. the dance inhibited the reduction of the hive mass. This indicates that dance is effective for food collection. Furthermore, clear inhibition was observed on the first two days of the experiments; after that, inhibition was no longer evident. This result suggests that the bee colony adapted to the new environment.

Indirect competition for pollinators is weak compared to direct resource competition: pollination and performance in the face of an invader.

PubMed

Palladini, Jennifer D; Maron, John L

2013-08-01

Invasive plants have the potential to reduce native plant abundance through both direct and indirect interactions. Direct interactions, such as competition for soil resources, and indirect interactions, such as competition for shared pollinators, have been shown to influence native plant performance; however, we know much less about how these interactions influence native plant abundance in the field. While direct competitive interactions are often assumed to drive declines in native abundance, an evaluation of their influence relative to indirect mechanisms is needed to more fully understand invasive plant impacts. We quantified the direct effects of resource competition by the invasive perennial forb, Euphorbia esula (Euphorbiaceae), on the recruitment, subsequent performance, and ultimate adult abundance of the native annual, Clarkia pulchella (Onagraceae). We contrast these direct effects with those that indirectly resulted from competition for shared pollinators. Although E. esula dramatically reduced pollinator visitation to C. pulchella, plants were only weakly pollen-limited. Pollen supplementation increased the number of seeds per fruit from 41.28 to 46.38. Seed addition experiments revealed that the impacts of ameliorating pollen limitation only increased potential recruitment by 12.3 %. In contrast, seed addition experiments that ameliorated direct competition with E. esula resulted in an increase in potential future recruitment of 574 %. Our results show that, while the indirect effects of competition for pollinators can influence plant abundance, its effects are dwarfed by the magnitude of direct effects of competition for resources.

Artificial time constraints on the Iowa Gambling Task: the effects on behavioural performance and subjective experience.

PubMed

Bowman, Caroline H; Evans, Cathryn E Y; Turnbull, Oliver H

2005-02-01

In the last decade, the Iowa Gambling Task (IGT) has become a widely employed neuropsychological research instrument for the investigation of executive function. The task has been employed in a wide range of formats, from 'manual' procedures to more recently introduced computerised versions. Computer-based formats often require that responses on the task should be artificially delayed by a number of seconds between trials to collect skin-conductance data. Participants, however, may become frustrated when they want to select from a particular deck in the time-limited versions--so that an unintended emotional experience of frustration might well disrupt a task presumed to be reliant on emotion-based learning. We investigated the effect of the various types of Iowa Gambling Task format on performance, using three types of task: the classic manual administration, with no time limitations; a computerised administration with a 6-s enforced delay; and a control computerised version which had no time constraints. We also evaluated the subjective experience of participants on each task. There were no significant differences in performance, between formats, in behavioural terms. Subjective experience measures on the task also showed consistent effects across all three formats-with substantial, and rapidly developing, awareness of which decks were 'good' and 'bad.'

Effects of line dancing on physical function and perceived limitation in older adults with self-reported mobility limitations.

PubMed

Bennett, Crystal G; Hackney, Madeleine E

2018-06-01

Older adults with mobility limitations are at greater risk for aging-related declines in physical function. Line dancing is a popular form of exercise that can be modified, and is thus feasible for older adults with mobility limitations. The purpose of this study was to assess the effects of 8 weeks of line dancing on balance, muscle strength, lower extremity function, endurance, gait speed, and perceived mobility limitations. An experimental design randomly assigned older adults to either an 8-week line dancing or usual care group. The convenience sample consisted of 23 participants with mobility limitations (age range: 65-93 years). The intervention used simple routines from novice line dance classes. At baseline and at 8 weeks, balance, knee muscle strength, lower extremity function, endurance, gait speed, and mobility limitations were measured. ANCOVA tests were conducted on each dependent variable to assess the effects of the intervention over time. Results found significant positive differences for the intervention group in lower extremity function (p < 0.01); endurance (p < 0.01); gait speed (p < 0.001); and self-reported mobility limitations (p < 0.05). Eight weeks of line dancing significantly improved physical function and reduced self-reported mobility limitations in these individuals. Line dancing could be recommended by clinicians as a potential adjunct therapy that addresses mobility limitations. Implications for Rehabilitation Line dancing may be an alternative exercise for older adults who need modifications due to mobility limitations. Line dancing incorporates cognitive and motor control. Line dancing can be performed alone or in a group setting. Dancing improves balance which can reduce risk of falls.

Biotherapeutics as alternatives to antibiotics

USDA-ARS?s Scientific Manuscript database

Increasing pressure to limit antibiotic use in agriculture is heightening the need for alternative methods to reduce the adverse effects of clinical and subclinical disease on livestock performance that are currently managed by in-feed antibiotic usage. Immunomodulators have long been sought as such...

Redundant Coding in Visual Search Displays: Effects of Shape and Colour.

DTIC Science & Technology

1997-02-01

results for refining color selection algorithms and for color coding in situations where the gamut of available colors is limited. In a secondary set of analyses, we note large performance differences as a function of target shape.

An experimental investigation with artificial sunlight of a solar hot-water heater

NASA Technical Reports Server (NTRS)

Simon, F. F.

1976-01-01

Thermal performance measurements were made of a commercial solar hot water heater in a solar simulator to determine basic performance characteristics of a traditional type of flat plate collector, with and without side reflectors (to increase the solar flux). Information on each of the following was obtained; (1) the effect of flow and incidence angle on the efficiency of a flat plate collector (but only without side reflectors); (2) transient performance under flow and nonflow conditions; (3) the effectiveness of reflectors to increase collector efficiency for a zero radiation angle at fluid temperatures required for solar air conditioning; and (4) the limits of applicability of a collector efficiency correlation based on the Hottel Whillier equation.

Performance of (CoPC)n catalyst in active lithium-thionyl chloride cells

NASA Technical Reports Server (NTRS)

Shah, Pinakin M.

1990-01-01

An experimental study was conducted with anode limited D size cells to characterize the performance of an active lithium-thionyl chloride (Li/SOCl2) system using the polymeric cobalt phthalocyanine, (CoPC)n, catalyst in carbon cathodes. The author describes the results of this experiment with respect to initial voltage delays, operating voltages, and capacities. The effectiveness of the preconditioning methods evolved to alleviate passivation effects on storage are also discussed. The results clearly demonstrated the superior high rate capability of cells with the catalyst. The catalyst did not adversely impact the performance of cells after active storage for up to 6 months, while retaining its beneficial influences.

Holt film wall shear instrumentation for boundary layer transition research

NASA Technical Reports Server (NTRS)

Schneider, Steven P.

1994-01-01

Measurements of the performance of hot-film wall-shear sensors were performed to aid development of improved sensors. The effect of film size and substrate properties on the sensor performance was quantified through parametric studies carried out both electronically and in a shock tube. The results show that sensor frequency response increases with decreasing sensor size, while at the same time sensitivity decreases. Substrate effects were also studied, through parametric variation of thermal conductivity and heat capacity. Early studies used complex dual-layer substrates, while later studies were designed for both single-layer and dual-layer substrates. Sensor failures and funding limitations have precluded completion of the substrate thermal-property tests.

Radiation Protection for Lunar Mission Scenarios

NASA Technical Reports Server (NTRS)

Clowdsley, Martha S.; Nealy, John E.; Wilson, John W.; Anderson, Brooke M.; Anderson, Mark S.; Krizan, Shawn A.

2005-01-01

Preliminary analyses of shielding requirements to protect astronauts from the harmful effects of radiation on both short-term and long-term lunar missions have been performed. Shielding needs for both solar particle events (SPEs) and galactic cosmic ray (GCR) exposure are discussed for transit vehicles and surface habitats. This work was performed under the aegis of two NASA initiatives. The first study was an architecture trade study led by Langley Research Center (LaRC) in which a broad range of vehicle types and mission scenarios were compared. The radiation analysis for this study primarily focused on the additional shielding mass required to protect astronauts from the rare occurrence of a large SPE. The second study, led by Johnson Space Center (JSC), involved the design of lunar habitats. Researchers at LaRC were asked to evaluate the changes to mission architecture that would be needed if the surface stay were lengthened from a shorter mission duration of 30 to 90 days to a longer stay of 500 days. Here, the primary radiation concern was GCR exposure. The methods used for these studies as well as the resulting shielding recommendations are discussed. Recommendations are also made for more detailed analyses to minimize shielding mass, once preliminary vehicle and habitat designs have been completed. Here, methodologies are mapped out and available radiation analysis tools are described. Since, as yet, no dosimetric limits have been adopted for missions beyond low earth orbit (LEO), radiation exposures are compared to LEO limits. Uncertainties associated with the LEO career effective dose limits and the effects of lowering these limits on shielding mass are also discussed.

There are limits to the effects of task instructions: Making the automatic effects of task instructions context-specific takes practice.

PubMed

Braem, Senne; Liefooghe, Baptist; De Houwer, Jan; Brass, Marcel; Abrahamse, Elger L

2017-03-01

Unlike other animals, humans have the unique ability to share and use verbal instructions to prepare for upcoming tasks. Recent research showed that instructions are sufficient for the automatic, reflex-like activation of responses. However, systematic studies into the limits of these automatic effects of task instructions remain relatively scarce. In this study, the authors set out to investigate whether this instruction-based automatic activation of responses can be context-dependent. Specifically, participants performed a task of which the stimulus-response rules and context (location on the screen) could either coincide or not with those of an instructed to-be-performed task (whose instructions changed every run). In 2 experiments, the authors showed that the instructed task rules had an automatic impact on performance-performance was slowed down when the merely instructed task rules did not coincide, but, importantly, this effect was not context-dependent. Interestingly, a third and fourth experiment suggests that context dependency can actually be observed, but only when practicing the task in its appropriate context for over 60 trials or after a sufficient amount of practice on a fixed context (the context was the same for all instructed tasks). Together, these findings seem to suggest that instructions can establish stimulus-response representations that have a reflexive impact on behavior but are insensitive to the context in which the task is known to be valid. Instead, context-specific task representations seem to require practice. (PsycINFO Database Record (c) 2017 APA, all rights reserved).

The Brain-Derived Neurotrophic Factor Val66Met Polymorphism Moderates an Effect of Physical Activity on Working Memory Performance

PubMed Central

Erickson, Kirk I.; Banducci, Sarah E.; Weinstein, Andrea M.; MacDonald, Angus W.; Ferrell, Robert E.; Halder, Indrani; Flory, Janine D.; Manuck, Stephen B.

2014-01-01

Physical activity enhances cognitive performance, yet individual variability in its effectiveness limits its widespread therapeutic application. Genetic differences might be one source of this variation. For example, carriers of the methionine-specifying (Met) allele of the brain-derived neurotrophic factor (BDNF) Val66Met polymorphism have reduced secretion of BDNF and poorer memory, yet physical activity increases BDNF levels. To determine whether the BDNF polymorphism moderated an association of physical activity with cognitive functioning among 1,032 midlife volunteers (mean age = 44.59 years), we evaluated participants’ performance on a battery of tests assessing memory, learning, and executive processes, and evaluated their physical activity with the Paffenbarger Physical Activity Questionnaire. BDNF genotype interacted robustly with physical activity to affect working memory, but not other areas of cognitive functioning. In particular, greater levels of physical activity offset a deleterious effect of the Met allele on working memory performance. These findings suggest that physical activity can modulate domain-specific genetic (BDNF) effects on cognition. PMID:23907543

Effects of landscape composition and configuration on pollination in a native herb: a field experiment.

PubMed

Ekroos, Johan; Jakobsson, Anna; Wideen, Joel; Herbertsson, Lina; Rundlöf, Maj; Smith, Henrik G

2015-10-01

Bumble bee abundance in agricultural landscapes is known to decrease with increasing distance from seminatural grasslands, but whether the pollination of bumble-bee-pollinated wild plants shows a similar pattern is less well known. In addition, the relative effects of landscape composition (landscape heterogeneity) and landscape configuration (distance from seminatural grassland) on wild plant pollination, and the interaction between these landscape effects, have not been studied using landscape-level replication. We performed a field experiment to disentangle these landscape effects on the pollination of a native herb, the sticky catchfly (Lychnis viscaria), while accounting for the proportion of oilseed rape across landscapes and the local abundance of bee forage flowers. We measured pollen limitation (the degree to which seed set is pollen-limited), seed set, and seed set stability using potted plants placed in landscapes that differed in heterogeneity (composition) and distance from seminatural grassland (configuration). Pollen limitation and seed set in individual plants did not respond to landscape composition, landscape configuration, or proportion of oilseed rape. Instead, seed set increased with increasing local bee forage flower cover. However, we found within-plant variability in pollen limitation and seed set to increase with increasing distance from seminatural pasture. Our results suggest that average within-plant levels of pollen limitation and seed set respond less swiftly than the within-plant variability in pollen limitation and seed set to changes in landscape configuration. Although landscape effects on pollination were less important than predicted, we conclude that landscape configuration and local habitat characteristics play larger roles than landscape composition in the pollination of L. viscaria.

Effectiveness of the surgical torque limiter: a model comparing drill- and hand-based screw insertion into locking plates.

PubMed

Ioannou, Christopher; Knight, Matthew; Daniele, Luca; Flueckiger, Lee; Tan, Ezekiel S L

2016-10-17

The objective of this study is to analyse the effectiveness of the surgical torque limiter during operative use. The study also investigates the potential differences in torque between hand and drill-based screw insertion into locking plates using a standardised torque limiter. Torque for both hand and power screw insertion was measured through a load cell, registering 6.66 points per second. This was performed in a controlled environment using synthetic bone, a locking plate and locking screws to simulate plate fixation. Screws were inserted by hand and by drill with torque values measured. The surgical torque limiter (1.5 Nm) was effective as the highest recorded reading in the study was 1.409 Nm. Comparatively, there is a statistically significant difference between screw insertion methods. Torque produced for manually driven screw insertion into locking plates was 1.289 Nm (95 % CI 1.269-1.308) with drill-powered screw insertion at 0.740 Nm (95 % CI 0.723-0.757). The surgical torque limiter proved to be effective as per product specifications. Screws inserted under power produce significantly less torque when compared to manual insertion by hand. This is likely related to the mechanism of the torque limiter when being used at higher speeds for which it was designed. We conclude that screws may be inserted using power to the plate with the addition of a torque limiter. It is recommended that all screws inserted by drill be hand tightened to achieve adequate torque values.

The Knock-Limited Performance of Fuel Blends Containing Aromatics V : N-Propylbenzene, N-Butylbenzene, Isobutylbenzene, M-Xylene, and 1-Isopropyl-4-Methylbenzene

NASA Technical Reports Server (NTRS)

Meyer, Carl L.; Branstetter, J. Robert

1946-01-01

Results are reported of knock-limited tests of five aromatics, each individually blended with selected base fuels and tested with and without TEL, using 17.6, F-4, and F-3 small-scale engines. The five aromatics rated in the following order of decreasing antiknock effectiveness at fuel/air ratio 0.10: m-xylene, 1-isopropyl-4-methylbenzene, n-propylbenzene, isobutylbenzene, and n-butylbenzene.

EEAP lighting survey study at the Red River Army Depot, Texarkana, Texas. Final report

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

NONE

The purpose of the study was to perform a limited site survey of specific buildings at the facility, identify specific Energy Conservation Opportunities (ECOs) that exist, and then evaluate these ECOs for technical and economic feasibility. These ECOs were limited to building interior lighting and it`s effects on the heating, ventilating and air conditioning (HVAC) systems. This survey was conducted with the assistance of many individuals at the facility.

Analysis of metalaxyl racemate using high performance liquid chromatography coupled with four kinds of detectors.

PubMed

Chen, Tao; Fan, Jun; Gao, Ruiqi; Wang, Tai; Yu, Ying; Zhang, Weiguang

2016-10-07

Chiral stationary phase-high performance liquid chromatography coupled with various detectors has been one of most commonly used methods for analysis and separation of chiral compounds over the past decades. Various detectors exhibit different characteristics in qualitative and quantitative studies under different chromatographic conditions. Herein, a comparative evaluation of HPLC coupled with ultraviolet, optical rotation, refractive index, and evaporative light scattering detectors has been conducted for qualitative and quantitative analyses of metalaxyl racemate. Effects of separation conditions on the peak area ratio between two enantiomers, including sample concentration, column temperature, mobile phase composition, as well as flow rate, have been investigated in detail. In addition, the limits of detection, the limits of quantitation, quantitative range and precision for these two enantiomers by using four detectors have been also studied. As indicated, the chromatographic separation conditions have been slight effects on ultraviolet and refractive index detections and the peak area ratio between two enantiomers remains almost unchanged, but the evaporative light scattering detection has been significantly affected by the above-mentioned chromatographic conditions and the corresponding peak area ratios varied greatly. Moreover, the limits of detection, the limits of quantitation, and the quantitative ranges of two enantiomers with UV detection were remarkably lower by 1-2 magnitudes than the others. Copyright © 2016 Elsevier B.V. All rights reserved.

Detection of β-Lactams and Chloramphenicol Residues in Raw Milk-Development and Application of an HPLC-DAD Method in Comparison with Microbial Inhibition Assays.

PubMed

Karageorgou, Eftychia; Christoforidou, Sofia; Ioannidou, Maria; Psomas, Evdoxios; Samouris, Georgios

2018-06-01

The present study was carried out to assess the detection sensitivity of four microbial inhibition assays (MIAs) in comparison with the results obtained by the High Performance Liquid Chromatography with Diode-Array Detection (HPLC-DAD) method for antibiotics of the β-lactam group and chloramphenicol in fortified raw milk samples. MIAs presented fairly good results when detecting β-lactams, whereas none were able to detect chloramphenicol at or above the permissible limits. HPLC analysis revealed high recoveries of examined compounds, whereas all detection limits observed were lower than their respective maximum residue limits (MRL) values. The extraction and clean-up procedure of antibiotics was performed by a modified matrix solid phase dispersion procedure using a mixture of Plexa by Agilent and QuEChERS as a sorbent. The HPLC method developed was validated, determining the accuracy, precision, linearity, decision limit, and detection capability. Both methods were used to monitor raw milk samples of several cows and sheep, obtained from producers in different regions of Greece, for the presence of examined antibiotic residues. Results obtained showed that MIAs could be used effectively and routinely to detect antibiotic residues in several milk types. However, in some cases, spoilage of milk samples revealed that the kits' sensitivity could be strongly affected, whereas this fact does not affect the effectiveness of HPLC-DAD analysis.

Improved Cognition While Cycling in Parkinson’s Disease Patients and Healthy Adults

PubMed Central

Hazamy, Audrey A.; Altmann, Lori J. P.; Stegemöller, Elizabeth; Bowers, Dawn; Lee, Hyo Keun; Wilson, Jonathan; Okun, Michael S.; Hass, Chris J.

2017-01-01

Persons with Parkinson’s disease (PD) are typically more susceptible than healthy adults to impaired performance when two tasks (dual task interference) are performed simultaneously. This limitation has by many experts been attributed to limitations in cognitive resources. Nearly all studies of dual task performance in PD employ walking or balance-based motor tasks, which are commonly impaired in PD. These tasks can be performed using a combination of one or two executive function tasks. The current study examined whether persons with PD would demonstrate greater dual task effects on cognition compared to healthy older adults (HOAs) during a concurrent cycling task. Participants with and without PD completed a battery of 12 cognitive tasks assessing visual and verbal processing in the following cognitive domains: speed of processing, controlled processing, working memory and executive function. Persons with PD exhibited impairments compared to healthy participants in select tasks (i.e., 0-Back, 2-Back and operation span). Further, both groups unexpectedly exhibited dual task facilitation of response times in visual tasks across cognitive domains, and improved verbal recall during an executive function task. Only one measure, 2-back, showed a speed-accuracy trade-off in the dual task. These results demonstrate that, when paired with a motor task in which they are not impaired, people with PD exhibit similar dual task effects on cognitive tasks as HOAs, even when these dual task effects are facilitative. More generally, these findings demonstrate that pairing cognitive tasks with cycling may actually improve cognitive performance which may have therapeutic relevance to cognitive decline associated with aging and PD pathology. PMID:28088064

Feasibility and Limitations of Vaccine Two-Dimensional Barcoding Using Mobile Devices.

PubMed

Bell, Cameron; Guerinet, Julien; Atkinson, Katherine M; Wilson, Kumanan

2016-06-23

Two-dimensional (2D) barcoding has the potential to enhance documentation of vaccine encounters at the point of care. However, this is currently limited to environments equipped with dedicated barcode scanners and compatible record systems. Mobile devices may present a cost-effective alternative to leverage 2D vaccine vial barcodes and improve vaccine product-specific information residing in digital health records. Mobile devices have the potential to capture product-specific information from 2D vaccine vial barcodes. We sought to examine the feasibility, performance, and potential limitations of scanning 2D barcodes on vaccine vials using 4 different mobile phones. A unique barcode scanning app was developed for Android and iOS operating systems. The impact of 4 variables on the scan success rate, data accuracy, and time to scan were examined: barcode size, curvature, fading, and ambient lighting conditions. Two experimenters performed 4 trials 10 times each, amounting to a total of 2160 barcode scan attempts. Of the 1832 successful scans performed in this evaluation, zero produced incorrect data. Five-millimeter barcodes were the slowest to scan, although only by 0.5 seconds on average. Barcodes with up to 50% fading had a 100% success rate, but success rate deteriorated beyond 60% fading. Curved barcodes took longer to scan compared with flat, but success rate deterioration was only observed at a vial diameter of 10 mm. Light conditions did not affect success rate or scan time between 500 lux and 20 lux. Conditions below 20 lux impeded the device's ability to scan successfully. Variability in scan time was observed across devices in all trials performed. 2D vaccine barcoding is possible using mobile devices and is successful under the majority of conditions examined. Manufacturers utilizing 2D barcodes should take into consideration the impact of factors that limit scan success rates. Future studies should evaluate the effect of mobile barcoding on workflow and vaccine administrator acceptance.

The effect of water temperature and flow on respiration in barnacles: patterns of mass transfer versus kinetic limitation.

PubMed

Nishizaki, Michael T; Carrington, Emily

2014-06-15

In aquatic systems, physiological processes such as respiration, photosynthesis and calcification are potentially limited by the exchange of dissolved materials between organisms and their environment. The nature and extent of physiological limitation is, therefore, likely to be dependent on environmental conditions. Here, we assessed the metabolic sensitivity of barnacles under a range of water temperatures and velocities, two factors that influence their distribution. Respiration rates increased in response to changes in temperature and flow, with an interaction where flow had less influence on respiration at low temperatures, and a much larger effect at high temperatures. Model analysis suggested that respiration is mass transfer limited under conditions of low velocity (<7.5 cm (-1)) and high temperature (20-25°C). In contrast, limitation by uptake reaction kinetics, when the biotic capacity of barnacles to absorb and process oxygen is slower than its physical delivery by mass transport, prevailed at high flows (40-150 cm s(-1)) and low temperatures (5-15°C). Moreover, there are intermediate flow-temperature conditions where both mass transfer and kinetic limitation are important. Behavioral monitoring revealed that barnacles fully extend their cirral appendages at low flows and display abbreviated 'testing' behaviors at high flows, suggesting some form of mechanical limitation. In low flow-high temperature treatments, however, barnacles displayed distinct 'pumping' behaviors that may serve to increase ventilation. Our results suggest that in slow-moving waters, respiration may become mass transfer limited as temperatures rise, whereas faster flows may serve to ameliorate the effects of elevated temperatures. Moreover, these results underscore the necessity for approaches that evaluate the combined effects of multiple environmental factors when examining physiological and behavioral performance. © 2014. Published by The Company of Biologists Ltd.

Effects of Between- and Within-Subject Variability on Autonomic Cardiorespiratory Activity during Sleep and Their Limitations on Sleep Staging: A Multilevel Analysis

PubMed Central

Long, Xi; Haakma, Reinder; Leufkens, Tim R. M.; Fonseca, Pedro; Aarts, Ronald M.

2015-01-01

Autonomic cardiorespiratory activity changes across sleep stages. However, it is unknown to what extent it is affected by between- and within-subject variability during sleep. As it is hypothesized that the variability is caused by differences in subject demographics (age, gender, and body mass index), time, and physiology, we quantified these effects and investigated how they limit reliable cardiorespiratory-based sleep staging. Six representative parameters obtained from 165 overnight heartbeat and respiration recordings were analyzed. Multilevel models were used to evaluate the effects evoked by differences in sleep stages, demographics, time, and physiology between and within subjects. Results show that the between- and within-subject effects were found to be significant for each parameter. When adjusted by sleep stages, the effects in physiology between and within subjects explained more than 80% of total variance but the time and demographic effects explained less. If these effects are corrected, profound improvements in sleep staging can be observed. These results indicate that the differences in subject demographics, time, and physiology present significant effects on cardiorespiratory activity during sleep. The primary effects come from the physiological variability between and within subjects, markedly limiting the sleep staging performance. Efforts to diminish these effects will be the main challenge. PMID:26366167

Creatine Use in Sports.

PubMed

Butts, Jessica; Jacobs, Bret; Silvis, Matthew

The use of creatine as a dietary supplement has become increasingly popular over the past several decades. Despite the popularity of creatine, questions remain with regard to dosing, effects on sports performance, and safety. PubMed was searched for articles published between 1980 and January 2017 using the terms creatine, creatine supplementation, sports performance, and dietary supplements. An additional Google search was performed to capture National Collegiate Athletic Association-specific creatine usage data and US dietary supplement and creatine sales. Clinical review. Level 4. Short-term use of creatine is considered safe and without significant adverse effects, although caution should be advised as the number of long-term studies is limited. Suggested dosing is variable, with many different regimens showing benefits. The safety of creatine supplementation has not been studied in children and adolescents. Currently, the scientific literature best supports creatine supplementation for increased performance in short-duration, maximal-intensity resistance training. While creatine appears to be safe and effective for particular settings, whether creatine supplementation leads to improved performance on the field of play remains unknown.

Malaysian and Singaporean students' affective characteristics and mathematics performance: evidence from PISA 2012.

PubMed

Thien, Lei Mee; Ong, Mei Yean

2015-01-01

This paper attempts to identify the extent to which the affective characteristics of Malaysian and Singaporean students' attainment compared to the OECD average in Programme for International Student Assessment (PISA) 2012, and examine the influence of students' affective characteristics, gender, and their socioeconomic status on mathematics performance at both student and school levels. Sample consisted of 5197 and 5546 15-year-old Malaysian and Singaporean students. Data were analysed using hierarchical linear modelling approach with HLM 7.0 software. Results showed that the Index of economic, social, and cultural status (ESCS), mathematics self-efficacy, and mathematics anxiety have significant effects on mathematics performance in Malaysia and Singapore at the student level. Proportion of boys at the school level has no significant effects on mathematics performance for both Malaysian and Singaporean students. ESCS mean at the school level has positive and significant effects on mathematics performance in Malaysia, but not in Singapore. Limitations, implications, and future studies were discussed.

Impact of Dietary Antioxidants on Sport Performance: A Review.

PubMed

Braakhuis, Andrea J; Hopkins, Will G

2015-07-01

Many athletes supplement with antioxidants in the belief this will reduce muscle damage, immune dysfunction and fatigue, and will thus improve performance, while some evidence suggests it impairs training adaptations. Here we review the effect of a range of dietary antioxidants and their effects on sport performance, including vitamin E, quercetin, resveratrol, beetroot juice, other food-derived polyphenols, spirulina and N-acetylcysteine (NAC). Older studies suggest vitamin E improves performance at altitude, with possible harmful effects on sea-level performance. Acute intake of vitamin E is worthy of further consideration, if plasma levels can be elevated sufficiently. Quercetin has a small beneficial effect for exercise of longer duration (>100 min), but it is unclear whether this benefits athletes. Resveratrol benefits trained rodents; more research is needed in athletes. Meta-analysis of beetroot juice studies has revealed that the nitrate component of beetroot juice had a substantial but unclear effect on performance when averaged across athletes, non-athletes and modes of exercise (single dose 1.4 ± 2.0%, double dose 0.5 ± 1.9%). The effect of addition of polyphenols and other components to beetroot juice was trivial but unclear (single dose 0.4 ± 3.2%, double dose -0.5 ± 3.3%). Other food-derived polyphenols indicate a range of performance outcomes from a large improvement to moderate impairment. Limited evidence suggests spirulina enhances endurance performance. Intravenous NAC improved endurance cycling performance and reduced muscle fatigue. On the basis of vitamin E and NAC studies, acute intake of antioxidants is likely to be beneficial. However, chronic intakes of most antioxidants have a harmful effect on performance.

C-SPECT - a Clinical Cardiac SPECT/Tct Platform: Design Concepts and Performance Potential

PubMed Central

Chang, Wei; Ordonez, Caesar E.; Liang, Haoning; Li, Yusheng; Liu, Jingai

2013-01-01

Because of scarcity of photons emitted from the heart, clinical cardiac SPECT imaging is mainly limited by photon statistics. The sub-optimal detection efficiency of current SPECT systems not only limits the quality of clinical cardiac SPECT imaging but also makes more advanced potential applications difficult to be realized. We propose a high-performance system platform - C-SPECT, which has its sampling geometry optimized for detection of emitted photons in quality and quantity. The C-SPECT has a stationary C-shaped gantry that surrounds the left-front side of a patient’s thorax. The stationary C-shaped collimator and detector systems in the gantry provide effective and efficient detection and sampling of photon emission. For cardiac imaging, the C-SPECT platform could achieve 2 to 4 times the system geometric efficiency of conventional SPECT systems at the same sampling resolution. This platform also includes an integrated transmission CT for attenuation correction. The ability of C-SPECT systems to perform sequential high-quality emission and transmission imaging could bring cost-effective high-performance to clinical imaging. In addition, a C-SPECT system could provide high detection efficiency to accommodate fast acquisition rate for gated and dynamic cardiac imaging. This paper describes the design concepts and performance potential of C-SPECT, and illustrates how these concepts can be implemented in a basic system. PMID:23885129

Is math anxiety in the secondary classroom limiting physics mastery? A study of math anxiety and physics performance

NASA Astrophysics Data System (ADS)

Mercer, Gary J.

This quantitative study examined the relationship between secondary students with math anxiety and physics performance in an inquiry-based constructivist classroom. The Revised Math Anxiety Rating Scale was used to evaluate math anxiety levels. The results were then compared to the performance on a physics standardized final examination. A simple correlation was performed, followed by a multivariate regression analysis to examine effects based on gender and prior math background. The correlation showed statistical significance between math anxiety and physics performance. The regression analysis showed statistical significance for math anxiety, physics performance, and prior math background, but did not show statistical significance for math anxiety, physics performance, and gender.

Design and Testing of a Hall Effect Thruster with 3D Printed Channel and Propellant Distributor

NASA Technical Reports Server (NTRS)

Hopping, Ethan P.; Xu, Kunning G.

2017-01-01

The UAH-78AM is a low-power Hall effect thruster developed at the University of Alabama in Huntsville with channel walls and a propellant distributor manufactured using 3D printing. The goal of this project is to assess the feasibility of using unconventional materials to produce a low-cost functioning Hall effect thruster and consider how additive manufacturing can expand the design space and provide other benefits. A version of the thruster was tested at NASA Glenn Research Center to obtain performance metrics and to validate the ability of the thruster to produce thrust and sustain a discharge. An overview of the thruster design and transient performance measurements are presented here. Measured thrust ranged from 17.2 millinewtons to 30.4 millinewtons over a discharge power of 280 watts to 520 watts with an anode I (sub SP)(Specific Impulse) range of 870 seconds to 1450 seconds. Temperature limitations of materials used for the channel walls and propellant distributor limit the ability to run the thruster at thermal steady-state.

Effects of atmospheric turbulence on the imaging performance of optical system

NASA Astrophysics Data System (ADS)

Al-Hamadani, Ali H.; Zainulabdeen, Faten Sh.; Karam, Ghada Sabah; Nasir, Eman Yousif; Al-Saedi, Abaas

2018-05-01

Turbulent effects are very complicated and still not entirely understood. Light waves from an astronomical object are distorted as they pass through the atmosphere. The refractive index fluctuations in the turbulent atmosphere induce an optical path difference (OPD) between different parts of the wavefront, distorted wavefronts produce low-quality images and degrade the image beyond the diffraction limit. In this paper the image degradation due to 2-D Gaussian atmospheric turbulence is considered in terms of the point spread function (PSF), and Strehl ratio as an image quality criteria for imaging systems with different apertures using the pupil function teqneque. A general expression for the degraded PSF in the case of circular and square apertures (with half diagonal = √{π/2 } , and 1) diffraction limited and defocused optical system is considered. Based on the derived formula, the effect of the Gaussian atmospheric turbulence on circular and square pupils has been studied with details. Numerical results show that the performance of optical systems with square aperture is more efficient at high levels of atmospheric turbulence than the other apertures.

Influence of temperature on the hydrolysis, acidogenesis and methanogenesis in mesophilic anaerobic digestion: parameter identification and modeling application.

PubMed

Donoso-Bravo, A; Retamal, C; Carballa, M; Ruiz-Filippi, G; Chamy, R

2009-01-01

The effect of temperature on the kinetic parameters involved in the main reactions of the anaerobic digestion process was studied. Batch tests with starch, glucose and acetic acid as substrates for hydrolysis, acidogenesis and methanogenesis, respectively, were performed in a temperature range between 15 and 45 degrees C. First order kinetics was assumed to determine the hydrolysis rate constant, while Monod and Haldane kinetics were considered for acidogenesis and methanogenesis, respectively. The results obtained showed that the anaerobic process is strongly influenced by temperature, with acidogenesis exerting the highest effect. The Cardinal Temperature Model 1 with an inflection point (CTM1) fitted properly the experimental data in the whole temperature range, except for the maximum degradation rate of acidogenesis. A simple case-study assessing the effect of temperature on an anaerobic CSTR performance indicated that with relatively simple substrates, like starch, the limiting reaction would change depending on temperature. However, when more complex substrates are used (e.g. sewage sludge), the hydrolysis might become more quickly into the limiting step.

PDC bits break ground with advanced vibration mitigation

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

NONE

1995-10-01

Advancements in PDC bit technology have resulted in the identification and characterization of different types of vibrational modes that historically have limited PDC bit performance. As a result, concepts have been developed that prevent the initiation of vibration and also mitigate its damaging effects once it occurs. This vibration-reducing concept ensures more efficient use of the energy available to a PDC bit performance. As a result, concepts have been developed that prevent the imitation of vibration and also mitigate its damaging effects once it occurs. This vibration-reducing concept ensures more efficient use of the energy available to a PDC bit,more » thereby improving its performance. This improved understanding of the complex forces affecting bit performance is driving bit customization for specific drilling programs.« less

75 FR 2796 - Revisions to the California State Implementation Plan, San Joaquin Valley Air Pollution Control...

Federal Register 2010, 2011, 2012, 2013, 2014

2010-01-19

... noted that the limit for baked extreme performance coatings in the rule is less stringent than the limit... the VOC limit for baked extreme performance coatings and the exemption for repair and touch-up operations. As to the emission limit for baked extreme performance coatings, the VOC limit in Rule 4603 is...

Hematocrit correction does not improve glucose monitor accuracy in the assessment of neonatal hypoglycemia.

PubMed

Wang, Li; Sievenpiper, John L; de Souza, Russell J; Thomaz, Michele; Blatz, Susan; Grey, Vijaylaxmi; Fusch, Christoph; Balion, Cynthia

2013-08-01

The lack of accuracy of point of care (POC) glucose monitors has limited their use in the diagnosis of neonatal hypoglycemia. Hematocrit plays an important role in explaining discordant results. The objective of this study was to to assess the effect of hematocrit on the diagnostic performance of Abbott Precision Xceed Pro (PXP) and Nova StatStrip (StatStrip) monitors in neonates. All blood samples ordered for laboratory glucose measurement were analyzed using the PXP and StatStrip and compared with the laboratory analyzer (ABL 800 Blood Gas analyzer [ABL]). Acceptable error targets were ±15% for glucose monitoring and ±5% for diagnosis. A total of 307 samples from 176 neonates were analyzed. Overall, 90% of StatStrip and 75% of PXP values met the 15% error limit and 45% of StatStrip and 32% of PXP values met the 5% error limit. At glucose concentrations ≤4 mmol/L, 83% of StatStrip and 79% of PXP values met the 15% error limit, while 37% of StatStrip and 38% of PXP values met the 5% error limit. Hematocrit explained 7.4% of the difference between the PXP and ABL whereas it accounted for only 0.09% of the difference between the StatStrip and ABL. The ROC analysis showed the screening cut point with the best performance for identifying neonatal hypoglycemia was 3.2 mmol/L for StatStrip and 3.3 mmol/L for PXP. Despite a negligible hematocrit effect for the StatStrip, it did not achieve recommended error limits. The StatStrip and PXP glucose monitors remain suitable only for neonatal hypoglycemia screening with confirmation required from a laboratory analyzer.

Soil phosphorus and water effects on growth, nutrient and carbohydrate concentrations, d13C, and nodulation of mimosa (Albizia julibrissin Durz.) on a highly weathered soil

USDA-ARS?s Scientific Manuscript database

Growth and physiological performance of multipurpose tree species can be severely constrained by nutrient shortages such as of phosphorus (P) in highly-weathered soils. Limitations to plant growth are accentuated by seasonal dry periods. We examined P fertilization and irrigation effects on growth...

A Pilot Study Examining the Effects of Time Constraints on Student Performance in Accounting Classes

ERIC Educational Resources Information Center

Morris, David E., Sr.; Scott, John

2017-01-01

The purpose of this study was to examine the effects, if any, of time constraints on the success of accounting students completing exams. This study examined how time allowed to take exams affected the grades on examinations in three different accounting classes. Two were sophomore classes and one was a senior accounting class. This limited pilot…

¹³C-based metabolic flux analysis of Saccharomyces cerevisiae with a reduced Crabtree effect.

PubMed

Kajihata, Shuichi; Matsuda, Fumio; Yoshimi, Mika; Hayakawa, Kenshi; Furusawa, Chikara; Kanda, Akihisa; Shimizu, Hiroshi

2015-08-01

Saccharomyces cerevisiae shows a Crabtree effect that produces ethanol in a high glucose concentration even under fully aerobic condition. For efficient production of cake yeast or compressed yeast for baking, ethanol by-production is not desired since glucose limited chemostat or fed-batch cultivations are performed to suppress the Crabtree effect. In this study, the (13)C-based metabolic flux analysis ((13)C-MFA) was performed for the S288C derived S. cerevisiae strain to characterize a metabolic state under the reduced Crabtree effect. S. cerevisiae cells were cultured at a low dilution rate (0.1 h(-1)) under the glucose-limited chemostat condition. The estimated metabolic flux distribution showed that the acetyl-CoA in mitochondria was mainly produced from pyruvate by pyruvate dehydrogenase (PDH) reaction and that the level of the metabolic flux through the pentose phosphate pathway was much higher than that of the Embden-Meyerhof-Parnas pathway, which contributes to high biomass yield at low dilution rate by supplying NADPH required for cell growth. Copyright © 2015 The Society for Biotechnology, Japan. Published by Elsevier B.V. All rights reserved.

Qualitative Process Theory.

DTIC Science & Technology

1982-02-01

4. PERFORMING ORG. REPORT NUMBER S 7. AUTNOR(a) S.CONTRACT OR GRANT NUMBER(.j- Kenneth .D. Forbus NOq,,4-8o-C-o5o5 S. PERFORMING ORGANIZATION NAME...AND ADDRESS 10. PROGRAM ELEMENT. PROjECT. TASK Artificial Intelligence Laboratory. AREA & WORK UNIT NUMBERS 545 -Technology Square Cambridge...about processes, their effects , and their limits. Qualitati e rocess theory defines a simple notion of Reasoning about process also Imotivates a new

Hydrogen-oxygen auxiliary propulsion for the space shuttle. Volume 1: High pressure thrusters

NASA Technical Reports Server (NTRS)

1973-01-01

Technology for long life, high performing, gaseous hydrogen-gaseous oxygen rocket engines suitable for auxiliary propulsion was provided by a combined analytical and experimental program. Propellant injectors, fast response valves, igniters, and regeneratively and film-cooled thrust chambers were tested over a wide range of operating conditions. Data generated include performance, combustion efficiency, thermal characteristics film cooling effectiveness, dynamic response in pulsing, and cycle life limitations.

Planar-Processed Polymer Transistors.

PubMed

Xu, Yong; Sun, Huabin; Shin, Eul-Yong; Lin, Yen-Fu; Li, Wenwu; Noh, Yong-Young

2016-10-01

Planar-processed polymer transistors are proposed where the effective charge injection and the split unipolar charge transport are all on the top surface of the polymer film, showing ideal device characteristics with unparalleled performance. This technique provides a great solution to the problem of fabrication limitations, the ambiguous operating principle, and the performance improvements in practical applications of conjugated-polymer transistors. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Practical considerations for bicarbonate loading and sports performance.

PubMed

Burke, Louise M

2013-01-01

Consumption of sodium bicarbonate (300 mg/kg 1-2 h before exercise) can temporarily increase blood bicarbonate concentrations, enhancing extracellular buffering of hydrogen ions which accumulate and efflux from the working muscle. Such 'bicarbonate loading' provides an ergogenic strategy for sporting events involving high rates of anaerobic glycolysis which are otherwise limited by the body's capacity to manage the progressive increase in intracellular acidity. Studies show that bicarbonate loading strategies have a moderate positive effect on the performance of sports involving 1-7 min of sustained strenuous exercise, and may also be useful for prolonged sports involving intermittent or sustained periods of high-intensity work rates. This potential to enhance sports performance requires further investigation using appropriate research design, but may be limited by practical considerations such as gut discomfort or the logistics of the event. The effect of chronic use of bicarbonate supplementation prior to high-intensity workouts to promote better training performance and adaptations is worthy of further investigation. While this relatively simple dietary strategy has been studied and used by sports people for over 80 years, it is likely that there are still ways in which further benefits from bicarbonate supplementation can be developed and individualized for specific athletes or specific events. Copyright © 2013 Nestec Ltd., Vevey/S. Karger AG, Basel.

Increased Needle Nitrogen Contents Did Not Improve Shoot Photosynthetic Performance of Mature Nitrogen-Poor Scots Pine Trees.

PubMed

Tarvainen, Lasse; Lutz, Martina; Räntfors, Mats; Näsholm, Torgny; Wallin, Göran

2016-01-01

Numerous studies have shown that temperate and boreal forests are limited by nitrogen (N) availability. However, few studies have provided a detailed account of how carbon (C) acquisition of such forests reacts to increasing N supply. We combined measurements of needle-scale biochemical photosynthetic capacities and continuous observations of shoot-scale photosynthetic performance from several canopy positions with simple mechanistic modeling to evaluate the photosynthetic responses of mature N-poor boreal Pinus sylvestris to N fertilization. The measurements were carried out in August 2013 on 90-year-old pine trees growing at Rosinedalsheden research site in northern Sweden. In spite of a nearly doubling of needle N content in response to the fertilization, no effect on the long-term shoot-scale C uptake was recorded. This lack of N-effect was due to strong light limitation of photosynthesis in all investigated canopy positions. The effect of greater N availability on needle photosynthetic capacities was also constrained by development of foliar phosphorus (P) deficiency following N addition. Thus, P deficiency and accumulation of N in arginine appeared to contribute toward lower shoot-scale nitrogen-use efficiency in the fertilized trees, thereby additionally constraining tree-scale responses to increasing N availability. On the whole our study suggests that the C uptake response of the studied N-poor boreal P. sylvestris stand to enhanced N availability is constrained by the efficiency with which the additional N is utilized. This efficiency, in turn, depends on the ability of the trees to use the greater N availability for additional light capture. For stands that have not reached canopy closure, increase in leaf area following N fertilization would be the most effective way for improving light capture and C uptake while for mature stands an increased leaf area may have a rather limited effect on light capture owing to increased self-shading. This raises the question if N limitation in boreal forests acts primarily by constraining growth of young stands while the commonly recorded increase in stem growth of mature stands following N addition is primarily the result of altered allocation and only to a limited extent the result of increased stand C-capture.

Performance evaluation capabilities for the design of physical systems

NASA Technical Reports Server (NTRS)

Pilkey, W. D.; Wang, B. P.

1972-01-01

The results are presented of a study aimed at developing and formulating a capability for the limiting performance of large steady state systems. The accomplishments reported include: (1) development of a theory of limiting performance of large systems subject to steady state inputs; (2) application and modification of PERFORM, the computational capability for the limiting performance of systems with transient inputs; and (3) demonstration that use of an inherently smooth control force for a limiting performance calculation improves the system identification phase of the design process for physical systems subjected to transient loading.

Testosterone Attenuates Age-Related Fall in Aerobic Function in Mobility Limited Older Men With Low Testosterone

PubMed Central

Bhasin, Shalender; Travison, Thomas G.; Pencina, Karol; Miciek, Renee; McKinnon, Jennifer; Basaria, Shehzad

2016-01-01

Context: Testosterone increases skeletal muscle mass and strength, but the effects of testosterone on aerobic performance in mobility-limited older men have not been evaluated. Objective: To determine the effects of testosterone supplementation on aerobic performance, assessed as peak oxygen uptake (V̇O2peak) and gas exchange lactate threshold (V̇O2θ), during symptom-limited incremental cycle ergometer exercise. Design: Subgroup analysis of the Testosterone in Older Men with Mobility Limitations Trial. Setting: Exercise physiology laboratory in an academic medical center. Participants: Sixty-four mobility-limited men 65 years or older with low total (100–350 ng/dL) or free (<50 pg/dL) testosterone. Interventions: Participants were randomized to receive 100-mg testosterone gel or placebo gel daily for 6 months. Main Outcome Measures: V̇O2peak and V̇O2θ from a symptom-limited cycle exercise test. Results: Mean (SD) baseline V̇O2peak was 20.5 (4.3) and 19.9 (4.7) mL/kg/min for testosterone and placebo, respectively. V̇O2peak increased by 0.83 (2.4) mL/kg/min in testosterone but decreased by −0.89 (2.5) mL/kg/min in placebo (P = .035); between group difference in change in V̇O2peak was significant (P = .006). This 6-month reduction in placebo was greater than the expected −0.4-mL/kg/min/y rate of decline in the general population. V̇O2θ did not change significantly in testosterone but decreased by 1.1 (1.8) mL/kg/min in placebo, P = .011 for between-group comparisons. Hemoglobin increased by 1.0 ± 3.5 and 0.1 ± 0.8 g/dL in testosterone and placebo groups, respectively. Conclusion: Testosterone supplementation in mobility-limited older men increased hemoglobin and attenuated the age-related declines in V̇O2peak and V̇O2θ. Long-term intervention studies are needed to determine the durability of this effect. PMID:27050869

14 CFR 135.398 - Commuter category airplanes performance operating limitations.

Code of Federal Regulations, 2012 CFR

2012-01-01

... 14 Aeronautics and Space 3 2012-01-01 2012-01-01 false Commuter category airplanes performance... ON BOARD SUCH AIRCRAFT Airplane Performance Operating Limitations § 135.398 Commuter category airplanes performance operating limitations. (a) No person may operate a commuter category airplane unless...

14 CFR 135.398 - Commuter category airplanes performance operating limitations.

Code of Federal Regulations, 2013 CFR

2013-01-01

... 14 Aeronautics and Space 3 2013-01-01 2013-01-01 false Commuter category airplanes performance... ON BOARD SUCH AIRCRAFT Airplane Performance Operating Limitations § 135.398 Commuter category airplanes performance operating limitations. (a) No person may operate a commuter category airplane unless...

14 CFR 135.398 - Commuter category airplanes performance operating limitations.

Code of Federal Regulations, 2014 CFR

2014-01-01

... 14 Aeronautics and Space 3 2014-01-01 2014-01-01 false Commuter category airplanes performance... ON BOARD SUCH AIRCRAFT Airplane Performance Operating Limitations § 135.398 Commuter category airplanes performance operating limitations. (a) No person may operate a commuter category airplane unless...

Arthrometric Evaluation of Stabilizing Effect of Knee Functional Bracing at Different Flexion Angles

PubMed Central

Seyed Mohseni, Saeedeh; Moss, Farzam; Karimi, Hossein; Kamali, Mohammad

2009-01-01

Previous in-vivo investigations on the stabilizing efficacy of knee bracing for ACL reconstructed patients have been often limited to 20-30 degrees of knee flexion. In this study, the effectiveness of a uniaxial hinged functional brace to improve the knee stability was assessed at 30, 60 and 90 degrees of knee flexion. Arthrometry tests were conducted on 15 healthy subjects before and following wearing the brace and the tibial displacements were measured at up to 150 N anterior forces. Results indicated that functional bracing has a significant stabilizing effect throughout the range of knee flexion examined (p < 0.05). The rate of effectiveness, however, was not consistent across the flexion range, e.g., 50% at 30 degrees and only 4% at 90 degrees. It was suggested that accurate sizing and fitting as well as attention to correct hinge placement relative to the femoral condyles can limit brace migration and improve its effectiveness in mid and deep knee flexion. With using adaptive limb fittings, through flexible pads, and a polycentric joint a more significant improvement of the overall brace performance and efficacy might be obtained. Key points Functional bracing improves the knee joint stability mostly in extension posture. Unlike the non-braced condition, the least knee joint stability appears in mid and deep flexion angles when using a hinged brace. Accurate sizing and fitting and attention to correct hinge placement relative to the femoral condyles can limit brace migration and improve its effectiveness in mid and deep knee flexion. The overall brace performance and efficacy might be improved significantly using adaptive limb fittings through flexible pads and/or polycentric joints. PMID:24149533

An Integrating Framework for Interdisciplinary Military Analyses

DTIC Science & Technology

2017-04-01

Effectiveness, System Performance, Task Prosecution, War Gaming 16. SECURITY CLASSIFICATION OF: 17. LIMITATION OF ABSTRACT 18. NUMBER OF PAGES...and space for every play of the game . Called plays can be compared to collective tasks with each player responsible for executing one or more

Influence of analytical bias and imprecision on the number of false positive results using Guideline-Driven Medical Decision Limits.

PubMed

Hyltoft Petersen, Per; Klee, George G

2014-03-20

Diagnostic decisions based on decision limits according to medical guidelines are different from the majority of clinical decisions due to the strict dichotomization of patients into diseased and non-diseased. Consequently, the influence of analytical performance is more critical than for other diagnostic decisions where much other information is included. The aim of this opinion paper is to investigate consequences of analytical quality and other circumstances for the outcome of "Guideline-Driven Medical Decision Limits". Effects of analytical bias and imprecision should be investigated separately and analytical quality specifications should be estimated accordingly. Use of sharp decision limits doesn't consider biological variation and effects of this variation are closely connected with the effects of analytical performance. Such relationships are investigated for the guidelines for HbA1c in diagnosis of diabetes and in risk of coronary heart disease based on serum cholesterol. The effects of a second sampling in diagnosis give dramatic reduction in the effects of analytical quality showing minimal influence of imprecision up to 3 to 5% for two independent samplings, whereas the reduction in bias is more moderate and a 2% increase in concentration doubles the percentage of false positive diagnoses, both for HbA1c and cholesterol. An alternative approach comes from the current application of guidelines for follow-up laboratory tests according to clinical procedure orders, e.g. frequency of parathyroid hormone requests as a function of serum calcium concentrations. Here, the specifications for bias can be evaluated from the functional increase in requests for increasing serum calcium concentrations. In consequence of the difficulties with biological variation and the practical utilization of concentration dependence of frequency of follow-up laboratory tests already in use, a kind of probability function for diagnosis as function of the key-analyte is proposed. Copyright © 2013 Elsevier B.V. All rights reserved.

Reprint of "Influence of analytical bias and imprecision on the number of false positive results using Guideline-Driven Medical Decision Limits".

PubMed

Hyltoft Petersen, Per; Klee, George G

2014-05-15

Diagnostic decisions based on decision limits according to medical guidelines are different from the majority of clinical decisions due to the strict dichotomization of patients into diseased and non-diseased. Consequently, the influence of analytical performance is more critical than for other diagnostic decisions where much other information is included. The aim of this opinion paper is to investigate consequences of analytical quality and other circumstances for the outcome of "Guideline-Driven Medical Decision Limits". Effects of analytical bias and imprecision should be investigated separately and analytical quality specifications should be estimated accordingly. Use of sharp decision limits doesn't consider biological variation and effects of this variation are closely connected with the effects of analytical performance. Such relationships are investigated for the guidelines for HbA1c in diagnosis of diabetes and in risk of coronary heart disease based on serum cholesterol. The effects of a second sampling in diagnosis give dramatic reduction in the effects of analytical quality showing minimal influence of imprecision up to 3 to 5% for two independent samplings, whereas the reduction in bias is more moderate and a 2% increase in concentration doubles the percentage of false positive diagnoses, both for HbA1c and cholesterol. An alternative approach comes from the current application of guidelines for follow-up laboratory tests according to clinical procedure orders, e.g. frequency of parathyroid hormone requests as a function of serum calcium concentrations. Here, the specifications for bias can be evaluated from the functional increase in requests for increasing serum calcium concentrations. In consequence of the difficulties with biological variation and the practical utilization of concentration dependence of frequency of follow-up laboratory tests already in use, a kind of probability function for diagnosis as function of the key-analyte is proposed. Copyright © 2014. Published by Elsevier B.V.

Active Video Games for Improving Physical Performance Measures in Older People: A Meta-analysis

PubMed Central

Taylor, Lynne M.; Kerse, Ngaire; Frakking, Tara; Maddison, Ralph

2018-01-01

Background and Purpose: Participation in regular physical activity is associated with better physical function in older people (>65 years); however, older people are the least active of all age groups. Exercise-based active video games (AVGs) offer an alternative to traditional exercise programs aimed at maintaining or enhancing physical performance measures in older people. This review systematically evaluated whether AVGs could improve measures of physical performance in older people. Secondary measures of safety, game appeal, and usability were also considered. Methods: Electronic databases were searched for randomized controlled trials published up to April 2015. Included were trials with 2 or more arms that evaluated the effect of AVGs on outcome measures of physical performance in older people. Results: Eighteen randomized controlled trials (n = 765) were included. Most trials limited inclusion to healthy community-dwelling older people. With the exception of 1 trial, all AVG programs were supervised. Using meta-analyses, AVGs were found to be more effective than conventional exercise (mean difference [MD], 4.33; 95% confidence intervals [CIs], 2.93-5.73) or no intervention (MD, 0.73; 95% CI, 0.17-1.29) for improving Berg Balance scores in community-dwelling older people. Active video games were also more effective than control for improving 30-second sit-to-stand scores (MD, 3.99; 95% CI, 1.92-6.05). No significant differences in Timed Up and Go scores were found when AVGs were compared with no intervention or with conventional exercise. Conclusions: Active video games can improve measures of mobility and balance in older people when used either on their own or as part of an exercise program. It is not yet clear whether AVGs are equally suitable for older people with significant cognitive impairments or balance or mobility limitations. Given the positive findings to date, consideration could be given to further development of age-appropriate AVGs for use by older people with balance or mobility limitations. PMID:26974212

Giant spin-torque diode sensitivity in the absence of bias magnetic field.

PubMed

Fang, Bin; Carpentieri, Mario; Hao, Xiaojie; Jiang, Hongwen; Katine, Jordan A; Krivorotov, Ilya N; Ocker, Berthold; Langer, Juergen; Wang, Kang L; Zhang, Baoshun; Azzerboni, Bruno; Amiri, Pedram Khalili; Finocchio, Giovanni; Zeng, Zhongming

2016-04-07

Microwave detectors based on the spin-torque diode effect are among the key emerging spintronic devices. By utilizing the spin of electrons in addition to charge, they have the potential to overcome the theoretical performance limits of their semiconductor (Schottky) counterparts. However, so far, practical implementations of spin-diode microwave detectors have been limited by the necessity to apply a magnetic field. Here, we demonstrate nanoscale magnetic tunnel junction microwave detectors, exhibiting high-detection sensitivity of 75,400 mV mW(-1) at room temperature without any external bias fields, and for low-input power (micro-Watts or lower). This sensitivity is significantly larger than both state-of-the-art Schottky diode detectors and existing spintronic diodes. Micromagnetic simulations and measurements reveal the essential role of injection locking to achieve this sensitivity performance. This mechanism may provide a pathway to enable further performance improvement of spin-torque diode microwave detectors.

Giant spin-torque diode sensitivity in the absence of bias magnetic field

PubMed Central

Fang, Bin; Carpentieri, Mario; Hao, Xiaojie; Jiang, Hongwen; Katine, Jordan A.; Krivorotov, Ilya N.; Ocker, Berthold; Langer, Juergen; Wang, Kang L.; Zhang, Baoshun; Azzerboni, Bruno; Amiri, Pedram Khalili; Finocchio, Giovanni; Zeng, Zhongming

2016-01-01

Microwave detectors based on the spin-torque diode effect are among the key emerging spintronic devices. By utilizing the spin of electrons in addition to charge, they have the potential to overcome the theoretical performance limits of their semiconductor (Schottky) counterparts. However, so far, practical implementations of spin-diode microwave detectors have been limited by the necessity to apply a magnetic field. Here, we demonstrate nanoscale magnetic tunnel junction microwave detectors, exhibiting high-detection sensitivity of 75,400 mV mW−1 at room temperature without any external bias fields, and for low-input power (micro-Watts or lower). This sensitivity is significantly larger than both state-of-the-art Schottky diode detectors and existing spintronic diodes. Micromagnetic simulations and measurements reveal the essential role of injection locking to achieve this sensitivity performance. This mechanism may provide a pathway to enable further performance improvement of spin-torque diode microwave detectors. PMID:27052973

Class attendance, peer similarity, and academic performance in a large field study

PubMed Central

Bjerre-Nielsen, Andreas; Mones, Enys; Lehmann, Sune; Lassen, David Dreyer

2017-01-01

Identifying the factors that determine academic performance is an essential part of educational research. Existing research indicates that class attendance is a useful predictor of subsequent course achievements. The majority of the literature is, however, based on surveys and self-reports, methods which have well-known systematic biases that lead to limitations on conclusions and generalizability as well as being costly to implement. Here we propose a novel method for measuring class attendance that overcomes these limitations by using location and bluetooth data collected from smartphone sensors. Based on measured attendance data of nearly 1,000 undergraduate students, we demonstrate that early and consistent class attendance strongly correlates with academic performance. In addition, our novel dataset allows us to determine that attendance among social peers was substantially correlated (>0.5), suggesting either an important peer effect or homophily with respect to attendance. PMID:29117190

Class attendance, peer similarity, and academic performance in a large field study.

PubMed

Kassarnig, Valentin; Bjerre-Nielsen, Andreas; Mones, Enys; Lehmann, Sune; Lassen, David Dreyer

2017-01-01

Identifying the factors that determine academic performance is an essential part of educational research. Existing research indicates that class attendance is a useful predictor of subsequent course achievements. The majority of the literature is, however, based on surveys and self-reports, methods which have well-known systematic biases that lead to limitations on conclusions and generalizability as well as being costly to implement. Here we propose a novel method for measuring class attendance that overcomes these limitations by using location and bluetooth data collected from smartphone sensors. Based on measured attendance data of nearly 1,000 undergraduate students, we demonstrate that early and consistent class attendance strongly correlates with academic performance. In addition, our novel dataset allows us to determine that attendance among social peers was substantially correlated (>0.5), suggesting either an important peer effect or homophily with respect to attendance.

Modeling node bandwidth limits and their effects on vector combining algorithms

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

Littlefield, R.J.

Each node in a message-passing multicomputer typically has several communication links. However, the maximum aggregate communication speed of a node is often less than the sum of its individual link speeds. Such computers are called node bandwidth limited (NBL). The NBL constraint is important when choosing algorithms because it can change the relative performance of different algorithms that accomplish the same task. This paper introduces a model of communication performance for NBL computers and uses the model to analyze the overall performance of three algorithms for vector combining (global sum) on the Intel Touchstone DELTA computer. Each of the threemore » algorithms is found to be at least 33% faster than the other two for some combinations of machine size and vector length. The NBL constraint is shown to significantly affect the conditions under which each algorithm is fastest.« less

Flammability Limits of Gases Under Low Gravity Conditions

NASA Technical Reports Server (NTRS)

Strehlow, R. A.

1985-01-01

The purpose of this combustion science investigation is to determine the effect of zero, fractional, and super gravity on the flammability limits of a premixed methane air flame in a standard 51 mm diameter flammability tube and to determine, if possible, the fluid flow associated with flame passage under zero-g conditions and the density (and hence, temperature) profiles associated with the flame under conditions of incipient extinction. This is accomplished by constructing an appropriate apparatus for placement in NASA's Lewis Research Center Lear Jet facility and flying the prescribed g-trajectories while the experiment is being performed. Data is recorded photographically using the visible light of the flame. The data acquired is: (1) the shape and propagation velocity of the flame under various g-conditions for methane compositions that are inside the flammable limits, and (2) the effect of gravity on the limits. Real time accelerometer readings for the three orthogonal directions are displayed in full view of the cameras and the framing rate of the cameras is used to measure velocities.

Constraints on the double-parton scattering cross section from same-sign W boson pair production in proton-proton collisions at √{s}=8 TeV

NASA Astrophysics Data System (ADS)

Sirunyan, A. M.; Tumasyan, A.; Adam, W.; Ambrogi, F.; Asilar, E.; Bergauer, T.; Brandstetter, J.; Brondolin, E.; Dragicevic, M.; Erö, J.; Flechl, M.; Friedl, M.; Frühwirth, R.; Ghete, V. M.; Grossmann, J.; Hrubec, J.; Jeitler, M.; König, A.; Krammer, N.; Krätschmer, I.; Liko, D.; Madlener, T.; Mikulec, I.; Pree, E.; Rabady, D.; Rad, N.; Rohringer, H.; Schieck, J.; Schöfbeck, R.; Spanring, M.; Spitzbart, D.; Waltenberger, W.; Wittmann, J.; Wulz, C.-E.; Zarucki, M.; Chekhovsky, V.; Mossolov, V.; Suarez Gonzalez, J.; De Wolf, E. A.; Di Croce, D.; Janssen, X.; Lauwers, J.; Van De Klundert, M.; Van Haevermaet, H.; Van Mechelen, P.; Van Remortel, N.; Abu Zeid, S.; Blekman, F.; D'Hondt, J.; De Bruyn, I.; De Clercq, J.; Deroover, K.; Flouris, G.; Lontkovskyi, D.; Lowette, S.; Moortgat, S.; Moreels, L.; Python, Q.; Skovpen, K.; Tavernier, S.; Van Doninck, W.; Van Mulders, P.; Van Parijs, I.; Beghin, D.; Brun, H.; Clerbaux, B.; De Lentdecker, G.; Delannoy, H.; Dorney, B.; Fasanella, G.; Favart, L.; Goldouzian, R.; Grebenyuk, A.; Karapostoli, G.; Lenzi, T.; Luetic, J.; Maerschalk, T.; Marinov, A.; Randle-conde, A.; Seva, T.; Vander Velde, C.; Vanlaer, P.; Vannerom, D.; Yonamine, R.; Zenoni, F.; Zhang, F.; Cimmino, A.; Cornelis, T.; Dobur, D.; Fagot, A.; Gul, M.; Khvastunov, I.; Poyraz, D.; Roskas, C.; Salva, S.; Tytgat, M.; Verbeke, W.; Zaganidis, N.; Bakhshiansohi, H.; Bondu, O.; Brochet, S.; Bruno, G.; Caputo, C.; Caudron, A.; De Visscher, S.; Delaere, C.; Delcourt, M.; Francois, B.; Giammanco, A.; Jafari, A.; Komm, M.; Krintiras, G.; Lemaitre, V.; Magitteri, A.; Mertens, A.; Musich, M.; Piotrzkowski, K.; Quertenmont, L.; Vidal Marono, M.; Wertz, S.; Beliy, N.; Aldá Júnior, W. L.; Alves, F. L.; Alves, G. A.; Brito, L.; Correa Martins Junior, M.; Hensel, C.; Moraes, A.; Pol, M. E.; Rebello Teles, P.; Belchior Batista Das Chagas, E.; Carvalho, W.; Chinellato, J.; Coelho, E.; Da Costa, E. M.; Da Silveira, G. G.; De Jesus Damiao, D.; Fonseca De Souza, S.; Huertas Guativa, L. M.; Malbouisson, H.; Melo De Almeida, M.; Mora Herrera, C.; Mundim, L.; Nogima, H.; Santoro, A.; Sznajder, A.; Tonelli Manganote, E. J.; Torres Da Silva De Araujo, F.; Vilela Pereira, A.; Ahuja, S.; Bernardes, C. A.; Fernandez Perez Tomei, T. R.; Gregores, E. M.; Mercadante, P. G.; Novaes, S. F.; Padula, Sandra S.; Romero Abad, D.; Ruiz Vargas, J. C.; Aleksandrov, A.; Hadjiiska, R.; Iaydjiev, P.; Misheva, M.; Rodozov, M.; Shopova, M.; Sultanov, G.; Dimitrov, A.; Glushkov, I.; Litov, L.; Pavlov, B.; Petkov, P.; Fang, W.; Gao, X.; Ahmad, M.; Bian, J. G.; Chen, G. M.; Chen, H. S.; Chen, M.; Chen, Y.; Jiang, C. H.; Leggat, D.; Liao, H.; Liu, Z.; Romeo, F.; Shaheen, S. M.; Spiezia, A.; Tao, J.; Wang, C.; Wang, Z.; Yazgan, E.; Zhang, H.; Zhang, S.; Zhao, J.; Ban, Y.; Chen, G.; Li, Q.; Liu, S.; Mao, Y.; Qian, S. J.; Wang, D.; Xu, Z.; Avila, C.; Cabrera, A.; Chaparro Sierra, L. F.; Florez, C.; González Hernández, C. F.; Ruiz Alvarez, J. D.; Courbon, B.; Godinovic, N.; Lelas, D.; Puljak, I.; Ribeiro Cipriano, P. M.; Sculac, T.; Antunovic, Z.; Kovac, M.; Brigljevic, V.; Ferencek, D.; Kadija, K.; Mesic, B.; Starodumov, A.; Susa, T.; Ather, M. W.; Attikis, A.; Mavromanolakis, G.; Mousa, J.; Nicolaou, C.; Ptochos, F.; Razis, P. A.; Rykaczewski, H.; Finger, M.; Finger, M.; Carrera Jarrin, E.; Assran, Y.; Mahmoud, M. A.; Mahrous, A.; Dewanjee, R. 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T.; Meister, D.; Micheli, F.; Musella, P.; Nessi-Tedaldi, F.; Pandolfi, F.; Pata, J.; Pauss, F.; Perrin, G.; Perrozzi, L.; Quittnat, M.; Reichmann, M.; Schönenberger, M.; Shchutska, L.; Tavolaro, V. R.; Theofilatos, K.; Vesterbacka Olsson, M. L.; Wallny, R.; Zhu, D. H.; Aarrestad, T. K.; Amsler, C.; Canelli, M. F.; De Cosa, A.; Del Burgo, R.; Donato, S.; Galloni, C.; Hreus, T.; Kilminster, B.; Pinna, D.; Rauco, G.; Robmann, P.; Salerno, D.; Seitz, C.; Takahashi, Y.; Zucchetta, A.; Candelise, V.; Doan, T. H.; Jain, Sh.; Khurana, R.; Kuo, C. M.; Lin, W.; Pozdnyakov, A.; Yu, S. S.; Kumar, Arun; Chang, P.; Chao, Y.; Chen, K. F.; Chen, P. H.; Fiori, F.; Hou, W.-S.; Hsiung, Y.; Liu, Y. F.; Lu, R.-S.; Paganis, E.; Psallidas, A.; Steen, A.; Tsai, J. f.; Asavapibhop, B.; Kovitanggoon, K.; Singh, G.; Srimanobhas, N.; Bakirci, M. N.; Boran, F.; Cerci, S.; Damarseckin, S.; Demiroglu, Z. S.; Dozen, C.; Eskut, E.; Girgis, S.; Gokbulut, G.; Guler, Y.; Hos, I.; Kangal, E. E.; Kara, O.; Kiminsu, U.; Oglakci, M.; Onengut, G.; Ozdemir, K.; Polatoz, A.; Topakli, H.; Turkcapar, S.; Zorbakir, I. S.; Zorbilmez, C.; Bilin, B.; Karapinar, G.; Ocalan, K.; Yalvac, M.; Zeyrek, M.; Gülmez, E.; Kaya, M.; Kaya, O.; Tekten, S.; Yetkin, E. A.; Agaras, M. N.; Atay, S.; Cakir, A.; Cankocak, K.; Grynyov, B.; Levchuk, L.; Aggleton, R.; Ball, F.; Beck, L.; Brooke, J. J.; Burns, D.; Clement, E.; Cussans, D.; Davignon, O.; Flacher, H.; Goldstein, J.; Grimes, M.; Heath, G. P.; Heath, H. F.; Jacob, J.; Kreczko, L.; Lucas, C.; Newbold, D. M.; Paramesvaran, S.; Poll, A.; Sakuma, T.; Seif El Nasr-storey, S.; Smith, D.; Smith, V. J.; Bell, K. W.; Belyaev, A.; Brew, C.; Brown, R. M.; Calligaris, L.; Cieri, D.; Cockerill, D. J. A.; Coughlan, J. A.; Harder, K.; Harper, S.; Olaiya, E.; Petyt, D.; Shepherd-Themistocleous, C. H.; Thea, A.; Tomalin, I. R.; Williams, T.; Auzinger, G.; Bainbridge, R.; Borg, J.; Breeze, S.; Buchmuller, O.; Bundock, A.; Casasso, S.; Citron, M.; Colling, D.; Corpe, L.; Dauncey, P.; Davies, G.; De Wit, A.; Della Negra, M.; Di Maria, R.; Elwood, A.; Haddad, Y.; Hall, G.; Iles, G.; James, T.; Lane, R.; Laner, C.; Lyons, L.; Magnan, A.-M.; Malik, S.; Mastrolorenzo, L.; Matsushita, T.; Nash, J.; Nikitenko, A.; Palladino, V.; Pesaresi, M.; Raymond, D. M.; Richards, A.; Rose, A.; Scott, E.; Seez, C.; Shtipliyski, A.; Summers, S.; Tapper, A.; Uchida, K.; Vazquez Acosta, M.; Virdee, T.; Wardle, N.; Winterbottom, D.; Wright, J.; Zenz, S. C.; Cole, J. E.; Hobson, P. R.; Khan, A.; Kyberd, P.; Reid, I. D.; Symonds, P.; Teodorescu, L.; Turner, M.; Borzou, A.; Call, K.; Dittmann, J.; Hatakeyama, K.; Liu, H.; Pastika, N.; Smith, C.; Bartek, R.; Dominguez, A.; Buccilli, A.; Cooper, S. I.; Henderson, C.; Rumerio, P.; West, C.; Arcaro, D.; Avetisyan, A.; Bose, T.; Gastler, D.; Rankin, D.; Richardson, C.; Rohlf, J.; Sulak, L.; Zou, D.; Benelli, G.; Cutts, D.; Garabedian, A.; Hakala, J.; Heintz, U.; Hogan, J. M.; Kwok, K. H. M.; Laird, E.; Landsberg, G.; Mao, Z.; Narain, M.; Pazzini, J.; Piperov, S.; Sagir, S.; Syarif, R.; Yu, D.; Band, R.; Brainerd, C.; Breedon, R.; Burns, D.; Calderon De La Barca Sanchez, M.; Chertok, M.; Conway, J.; Conway, R.; Cox, P. T.; Erbacher, R.; Flores, C.; Funk, G.; Gardner, M.; Ko, W.; Lander, R.; Mclean, C.; Mulhearn, M.; Pellett, D.; Pilot, J.; Shalhout, S.; Shi, M.; Smith, J.; Stolp, D.; Tos, K.; Tripathi, M.; Wang, Z.; Bachtis, M.; Bravo, C.; Cousins, R.; Dasgupta, A.; Florent, A.; Hauser, J.; Ignatenko, M.; Mccoll, N.; Regnard, S.; Saltzberg, D.; Schnaible, C.; Valuev, V.; Bouvier, E.; Burt, K.; Clare, R.; Ellison, J.; Gary, J. W.; Ghiasi Shirazi, S. M. A.; Hanson, G.; Heilman, J.; Kennedy, E.; Lacroix, F.; Long, O. R.; Olmedo Negrete, M.; Paneva, M. I.; Shrinivas, A.; Si, W.; Wang, L.; Wei, H.; Wimpenny, S.; Yates, B. R.; Branson, J. G.; Cittolin, S.; Derdzinski, M.; Gerosa, R.; Hashemi, B.; Holzner, A.; Klein, D.; Kole, G.; Krutelyov, V.; Letts, J.; Macneill, I.; Masciovecchio, M.; Olivito, D.; Padhi, S.; Pieri, M.; Sani, M.; Sharma, V.; Simon, S.; Tadel, M.; Vartak, A.; Wasserbaech, S.; Wood, J.; Würthwein, F.; Yagil, A.; Zevi Della Porta, G.; Amin, N.; Bhandari, R.; Bradmiller-Feld, J.; Campagnari, C.; Dishaw, A.; Dutta, V.; Franco Sevilla, M.; George, C.; Golf, F.; Gouskos, L.; Gran, J.; Heller, R.; Incandela, J.; Mullin, S. D.; Ovcharova, A.; Qu, H.; Richman, J.; Stuart, D.; Suarez, I.; Yoo, J.; Anderson, D.; Bendavid, J.; Bornheim, A.; Lawhorn, J. M.; Newman, H. B.; Nguyen, T.; Pena, C.; Spiropulu, M.; Vlimant, J. R.; Xie, S.; Zhang, Z.; Zhu, R. Y.; Andrews, M. B.; Ferguson, T.; Mudholkar, T.; Paulini, M.; Russ, J.; Sun, M.; Vogel, H.; Vorobiev, I.; Weinberg, M.; Cumalat, J. P.; Ford, W. T.; Jensen, F.; Johnson, A.; Krohn, M.; Leontsinis, S.; Mulholland, T.; Stenson, K.; Wagner, S. R.; Alexander, J.; Chaves, J.; Chu, J.; Dittmer, S.; Mcdermott, K.; Mirman, N.; Patterson, J. R.; Rinkevicius, A.; Ryd, A.; Skinnari, L.; Soffi, L.; Tan, S. M.; Tao, Z.; Thom, J.; Tucker, J.; Wittich, P.; Zientek, M.; Abdullin, S.; Albrow, M.; Alyari, M.; Apollinari, G.; Apresyan, A.; Apyan, A.; Banerjee, S.; Bauerdick, L. A. T.; Beretvas, A.; Berryhill, J.; Bhat, P. C.; Bolla, G.; Burkett, K.; Butler, J. N.; Canepa, A.; Cerati, G. B.; Cheung, H. W. K.; Chlebana, F.; Cremonesi, M.; Duarte, J.; Elvira, V. D.; Freeman, J.; Gecse, Z.; Gottschalk, E.; Gray, L.; Green, D.; Grünendahl, S.; Gutsche, O.; Harris, R. M.; Hasegawa, S.; Hirschauer, J.; Hu, Z.; Jayatilaka, B.; Jindariani, S.; Johnson, M.; Joshi, U.; Klima, B.; Kreis, B.; Lammel, S.; Lincoln, D.; Lipton, R.; Liu, M.; Liu, T.; Lopes De Sá, R.; Lykken, J.; Maeshima, K.; Magini, N.; Marraffino, J. M.; Mason, D.; McBride, P.; Merkel, P.; Mrenna, S.; Nahn, S.; O'Dell, V.; Pedro, K.; Prokofyev, O.; Rakness, G.; Ristori, L.; Schneider, B.; Sexton-Kennedy, E.; Soha, A.; Spalding, W. J.; Spiegel, L.; Stoynev, S.; Strait, J.; Strobbe, N.; Taylor, L.; Tkaczyk, S.; Tran, N. V.; Uplegger, L.; Vaandering, E. W.; Vernieri, C.; Verzocchi, M.; Vidal, R.; Wang, M.; Weber, H. A.; Whitbeck, A.; Acosta, D.; Avery, P.; Bortignon, P.; Bourilkov, D.; Brinkerhoff, A.; Carnes, A.; Carver, M.; Curry, D.; Field, R. D.; Furic, I. K.; Konigsberg, J.; Korytov, A.; Kotov, K.; Ma, P.; Matchev, K.; Mei, H.; Mitselmakher, G.; Rank, D.; Sperka, D.; Terentyev, N.; Thomas, L.; Wang, J.; Wang, S.; Yelton, J.; Joshi, Y. R.; Linn, S.; Markowitz, P.; Rodriguez, J. L.; Ackert, A.; Adams, T.; Askew, A.; Hagopian, S.; Hagopian, V.; Johnson, K. F.; Kolberg, T.; Martinez, G.; Perry, T.; Prosper, H.; Saha, A.; Santra, A.; Sharma, V.; Yohay, R.; Baarmand, M. M.; Bhopatkar, V.; Colafranceschi, S.; Hohlmann, M.; Noonan, D.; Roy, T.; Yumiceva, F.; Adams, M. R.; Apanasevich, L.; Berry, D.; Betts, R. R.; Cavanaugh, R.; Chen, X.; Evdokimov, O.; Gerber, C. E.; Hangal, D. A.; Hofman, D. J.; Jung, K.; Kamin, J.; Sandoval Gonzalez, I. D.; Tonjes, M. B.; Trauger, H.; Varelas, N.; Wang, H.; Wu, Z.; Zhang, J.; Bilki, B.; Clarida, W.; Dilsiz, K.; Durgut, S.; Gandrajula, R. P.; Haytmyradov, M.; Khristenko, V.; Merlo, J.-P.; Mermerkaya, H.; Mestvirishvili, A.; Moeller, A.; Nachtman, J.; Ogul, H.; Onel, Y.; Ozok, F.; Penzo, A.; Snyder, C.; Tiras, E.; Wetzel, J.; Yi, K.; Blumenfeld, B.; Cocoros, A.; Eminizer, N.; Fehling, D.; Feng, L.; Gritsan, A. V.; Maksimovic, P.; Roskes, J.; Sarica, U.; Swartz, M.; Xiao, M.; You, C.; Al-bataineh, A.; Baringer, P.; Bean, A.; Boren, S.; Bowen, J.; Castle, J.; Khalil, S.; Kropivnitskaya, A.; Majumder, D.; Mcbrayer, W.; Murray, M.; Royon, C.; Sanders, S.; Schmitz, E.; Tapia Takaki, J. D.; Wang, Q.; Ivanov, A.; Kaadze, K.; Maravin, Y.; Mohammadi, A.; Saini, L. K.; Skhirtladze, N.; Toda, S.; Rebassoo, F.; Wright, D.; Anelli, C.; Baden, A.; Baron, O.; Belloni, A.; Calvert, B.; Eno, S. C.; Ferraioli, C.; Hadley, N. J.; Jabeen, S.; Jeng, G. Y.; Kellogg, R. G.; Kunkle, J.; Mignerey, A. C.; Ricci-Tam, F.; Shin, Y. H.; Skuja, A.; Tonwar, S. C.; Abercrombie, D.; Allen, B.; Azzolini, V.; Barbieri, R.; Baty, A.; Bi, R.; Brandt, S.; Busza, W.; Cali, I. A.; D'Alfonso, M.; Demiragli, Z.; Gomez Ceballos, G.; Goncharov, M.; Hsu, D.; Iiyama, Y.; Innocenti, G. M.; Klute, M.; Kovalskyi, D.; Lai, Y. S.; Lee, Y.-J.; Levin, A.; Luckey, P. D.; Maier, B.; Marini, A. C.; Mcginn, C.; Mironov, C.; Narayanan, S.; Niu, X.; Paus, C.; Roland, C.; Roland, G.; Salfeld-Nebgen, J.; Stephans, G. S. F.; Tatar, K.; Velicanu, D.; Wang, J.; Wang, T. W.; Wyslouch, B.; Benvenuti, A. C.; Chatterjee, R. M.; Evans, A.; Hansen, P.; Kalafut, S.; Kubota, Y.; Lesko, Z.; Mans, J.; Nourbakhsh, S.; Ruckstuhl, N.; Rusack, R.; Turkewitz, J.; Acosta, J. G.; Oliveros, S.; Avdeeva, E.; Bloom, K.; Claes, D. R.; Fangmeier, C.; Gonzalez Suarez, R.; Kamalieddin, R.; Kravchenko, I.; Monroy, J.; Siado, J. E.; Snow, G. R.; Stieger, B.; Dolen, J.; Godshalk, A.; Harrington, C.; Iashvili, I.; Nguyen, D.; Parker, A.; Rappoccio, S.; Roozbahani, B.; Alverson, G.; Barberis, E.; Hortiangtham, A.; Massironi, A.; Morse, D. M.; Orimoto, T.; Teixeira De Lima, R.; Trocino, D.; Wood, D.; Bhattacharya, S.; Charaf, O.; Hahn, K. A.; Mucia, N.; Odell, N.; Pollack, B.; Schmitt, M. H.; Sung, K.; Trovato, M.; Velasco, M.; Dev, N.; Hildreth, M.; Hurtado Anampa, K.; Jessop, C.; Karmgard, D. J.; Kellams, N.; Lannon, K.; Loukas, N.; Marinelli, N.; Meng, F.; Mueller, C.; Musienko, Y.; Planer, M.; Reinsvold, A.; Ruchti, R.; Smith, G.; Taroni, S.; Wayne, M.; Wolf, M.; Woodard, A.; Alimena, J.; Antonelli, L.; Bylsma, B.; Durkin, L. S.; Flowers, S.; Francis, B.; Hart, A.; Hill, C.; Ji, W.; Liu, B.; Luo, W.; Puigh, D.; Winer, B. L.; Wulsin, H. W.; Cooperstein, S.; Driga, O.; Elmer, P.; Hardenbrook, J.; Hebda, P.; Higginbotham, S.; Lange, D.; Luo, J.; Marlow, D.; Mei, K.; Ojalvo, I.; Olsen, J.; Palmer, C.; Piroué, P.; Stickland, D.; Tully, C.; Malik, S.; Norberg, S.; Barker, A.; Barnes, V. E.; Das, S.; Folgueras, S.; Gutay, L.; Jha, M. K.; Jones, M.; Jung, A. W.; Khatiwada, A.; Miller, D. H.; Neumeister, N.; Peng, C. C.; Schulte, J. F.; Sun, J.; Wang, F.; Xie, W.; Cheng, T.; Parashar, N.; Stupak, J.; Adair, A.; Akgun, B.; Chen, Z.; Ecklund, K. M.; Geurts, F. J. M.; Guilbaud, M.; Li, W.; Michlin, B.; Northup, M.; Padley, B. P.; Roberts, J.; Rorie, J.; Tu, Z.; Zabel, J.; Bodek, A.; de Barbaro, P.; Demina, R.; Duh, Y. t.; Ferbel, T.; Galanti, M.; Garcia-Bellido, A.; Han, J.; Hindrichs, O.; Khukhunaishvili, A.; Lo, K. H.; Tan, P.; Verzetti, M.; Ciesielski, R.; Goulianos, K.; Mesropian, C.; Agapitos, A.; Chou, J. P.; Gershtein, Y.; Gómez Espinosa, T. A.; Halkiadakis, E.; Heindl, M.; Hughes, E.; Kaplan, S.; Kunnawalkam Elayavalli, R.; Kyriacou, S.; Lath, A.; Montalvo, R.; Nash, K.; Osherson, M.; Saka, H.; Salur, S.; Schnetzer, S.; Sheffield, D.; Somalwar, S.; Stone, R.; Thomas, S.; Thomassen, P.; Walker, M.; Delannoy, A. G.; Foerster, M.; Heideman, J.; Riley, G.; Rose, K.; Spanier, S.; Thapa, K.; Bouhali, O.; Castaneda Hernandez, A.; Celik, A.; Dalchenko, M.; De Mattia, M.; Delgado, A.; Dildick, S.; Eusebi, R.; Gilmore, J.; Huang, T.; Kamon, T.; Mueller, R.; Pakhotin, Y.; Patel, R.; Perloff, A.; Perniè, L.; Rathjens, D.; Safonov, A.; Tatarinov, A.; Ulmer, K. A.; Akchurin, N.; Damgov, J.; De Guio, F.; Dudero, P. R.; Faulkner, J.; Gurpinar, E.; Kunori, S.; Lamichhane, K.; Lee, S. W.; Libeiro, T.; Peltola, T.; Undleeb, S.; Volobouev, I.; Wang, Z.; Greene, S.; Gurrola, A.; Janjam, R.; Johns, W.; Maguire, C.; Melo, A.; Ni, H.; Padeken, K.; Sheldon, P.; Tuo, S.; Velkovska, J.; Xu, Q.; Arenton, M. W.; Barria, P.; Cox, B.; Hirosky, R.; Joyce, M.; Ledovskoy, A.; Li, H.; Neu, C.; Sinthuprasith, T.; Wang, Y.; Wolfe, E.; Xia, F.; Harr, R.; Karchin, P. E.; Sturdy, J.; Zaleski, S.; Brodski, M.; Buchanan, J.; Caillol, C.; Dasu, S.; Dodd, L.; Duric, S.; Gomber, B.; Grothe, M.; Herndon, M.; Hervé, A.; Hussain, U.; Klabbers, P.; Lanaro, A.; Levine, A.; Long, K.; Loveless, R.; Polese, G.; Ruggles, T.; Savin, A.; Smith, N.; Smith, W. H.; Taylor, D.; Woods, N.

2018-02-01

A first search for same-sign WW production via double-parton scattering is performed based on proton-proton collision data at a center-of-mass energy of 8 TeV using dimuon and electron-muon final states. The search is based on the analysis of data corresponding to an integrated luminosity of 19.7 fb-1. No significant excess of events is observed above the expected single-parton scattering yields. A 95% confidence level upper limit of 0.32 pb is set on the inclusive cross section for same-sign WW production via the double-parton scattering process. This upper limit is used to place a 95% confidence level lower limit of 12.2 mb on the effective double-parton cross section parameter, closely related to the transverse distribution of partons in the proton. This limit on the effective cross section is consistent with previous measurements as well as with Monte Carlo event generator predictions.

Limitations of and Barriers to Using Performance Measurement: Purchasers' Perspectives

PubMed Central

Ginsberg, Caren; Sheridan, Samantha

2001-01-01

Although health plan performance data are becoming increasingly more available, many purchasers are still not using these data to make their purchasing decisions. In this article, we review barriers that private purchasers face to using performance data. In addition, we consider the effects of the larger health care purchasing environment and employers' quality improvement activities on their use of the data. We conclude that a variety of factors, including trends, the health care purchasing environment, characteristics of firms, and problems with performance data and their presentation to users create barriers to incorporating this information into health care decisionmaking. PMID:25372184

Ride qualities criteria validation/pilot performance study: Flight test results

NASA Technical Reports Server (NTRS)

Nardi, L. U.; Kawana, H. Y.; Greek, D. C.

1979-01-01

Pilot performance during a terrain following flight was studied for ride quality criteria validation. Data from manual and automatic terrain following operations conducted during low level penetrations were analyzed to determine the effect of ride qualities on crew performance. The conditions analyzed included varying levels of turbulence, terrain roughness, and mission duration with a ride smoothing system on and off. Limited validation of the B-1 ride quality criteria and some of the first order interactions between ride qualities and pilot/vehicle performance are highlighted. An earlier B-1 flight simulation program correlated well with the flight test results.

Thermal evaluation of advanced solar dynamic heat receiver performance

NASA Technical Reports Server (NTRS)

Crane, Roger A.

1989-01-01

The thermal performance of a variety of concepts for thermal energy storage as applied to solar dynamic applications is discussed. It is recognized that designs providing large thermal gradients or large temperature swings during orbit are susceptible to early mechanical failure. Concepts incorporating heat pipe technology may encounter operational limitations over sufficiently large ranges. By reviewing the thermal performance of basic designs, the relative merits of the basic concepts are compared. In addition the effect of thermal enhancement and metal utilization as applied to each design provides a partial characterization of the performance improvements to be achieved by developing these technologies.

The use of creatine supplements in the military.

PubMed

Havenetidis, Konstantinos

2016-08-01

Creatine is considered an effective nutritional ergogenic aid to enhance exercise performance. In spite of the publication of several reviews in the last decade on the topic of exercise performance/sports and creatine there is a need for an update related to the military given the lack of information in this area. The aim of this study was to critically assess original research addressing the use of creatine supplements in the military. A search of the electronic databases PubMed and SPORTDiscus, for the following key words: military personnel, trainees, recruit, soldier, physical fitness, physical conditioning, creatine supplementation, creatine ingestion, nutritional supplements to identify surveys and randomised clinical trials from journal articles and technical reports investigating the effect of creatine supplementation on military populations. Thirty-three out of 90 articles examined the use of creatine as a dietary supplement in military personnel. Twenty-one studies were finally selected on the basis of stated inclusion criteria for military surveys and randomised clinical trials. Most of the surveys (15/17) in the military indicate a high popularity of creatine (average 27%) among supplement users. In contrast, in most of the exercise protocols used (6/9) during randomised clinical trials creatine has produced a non-significant performance-enhancing effect. Creatine is one of the most widely used supplemental compounds in the military. It is not considered a doping infraction or related to any adverse health effects but its long-term usage needs further investigation. Experimental research suggests that creatine supplementation does not enhance physical performance in the military. However, limitations in creatine dosage, military fitness testing and sample group selection might have underestimated the ergogenic properties of creatine. Recent studies also indicate positive effects on various aspects of total force fitness such as cognitive-psychomotor performance, bone health, musculoskeletal damage and neuromuscular function. Published by the BMJ Publishing Group Limited. For permission to use (where not already granted under a licence) please go to http://www.bmj.com/company/products-services/rights-and-licensing/

Pay-for-performance in disease management: a systematic review of the literature.

PubMed

de Bruin, Simone R; Baan, Caroline A; Struijs, Jeroen N

2011-10-14

Pay-for-performance (P4P) is increasingly implemented in the healthcare system to encourage improvements in healthcare quality. P4P is a payment model that rewards healthcare providers for meeting pre-established targets for delivery of healthcare services by financial incentives. Based on their performance, healthcare providers receive either additional or reduced payment. Currently, little is known about P4P schemes intending to improve delivery of chronic care through disease management. The objectives of this paper are therefore to provide an overview of P4P schemes used to stimulate delivery of chronic care through disease management and to provide insight into their effects on healthcare quality and costs. A systematic PubMed search was performed for English language papers published between 2000 and 2010 describing P4P schemes related to the implementation of disease management. Wagner's chronic care model was used to make disease management operational. Eight P4P schemes were identified, introduced in the USA (n = 6), Germany (n = 1), and Australia (n = 1). Five P4P schemes were part of a larger scheme of interventions to improve quality of care, whereas three P4P schemes were solely implemented. Most financial incentives were rewards, selective, and granted on the basis of absolute performance. More variation was found in incented entities and the basis for providing incentives. Information about motivation, certainty, size, frequency, and duration of the financial incentives was generally limited. Five studies were identified that evaluated the effects of P4P on healthcare quality. Most studies showed positive effects of P4P on healthcare quality. No studies were found that evaluated the effects of P4P on healthcare costs. The number of P4P schemes to encourage disease management is limited. Hardly any information is available about the effects of such schemes on healthcare quality and costs. © 2011 de Bruin et al; licensee BioMed Central Ltd.

Pay-for-performance in disease management: a systematic review of the literature

PubMed Central

2011-01-01

Background Pay-for-performance (P4P) is increasingly implemented in the healthcare system to encourage improvements in healthcare quality. P4P is a payment model that rewards healthcare providers for meeting pre-established targets for delivery of healthcare services by financial incentives. Based on their performance, healthcare providers receive either additional or reduced payment. Currently, little is known about P4P schemes intending to improve delivery of chronic care through disease management. The objectives of this paper are therefore to provide an overview of P4P schemes used to stimulate delivery of chronic care through disease management and to provide insight into their effects on healthcare quality and costs. Methods A systematic PubMed search was performed for English language papers published between 2000 and 2010 describing P4P schemes related to the implementation of disease management. Wagner's chronic care model was used to make disease management operational. Results Eight P4P schemes were identified, introduced in the USA (n = 6), Germany (n = 1), and Australia (n = 1). Five P4P schemes were part of a larger scheme of interventions to improve quality of care, whereas three P4P schemes were solely implemented. Most financial incentives were rewards, selective, and granted on the basis of absolute performance. More variation was found in incented entities and the basis for providing incentives. Information about motivation, certainty, size, frequency, and duration of the financial incentives was generally limited. Five studies were identified that evaluated the effects of P4P on healthcare quality. Most studies showed positive effects of P4P on healthcare quality. No studies were found that evaluated the effects of P4P on healthcare costs. Conclusion The number of P4P schemes to encourage disease management is limited. Hardly any information is available about the effects of such schemes on healthcare quality and costs. PMID:21999234

The role of age in the perceptions of politics--job performance relationship: a three-study constructive replication.

PubMed

Treadway, Darren C; Ferris, Gerald R; Hochwarter, Wayne; Perrewé, Pamela; Witt, L A; Goodman, Joseph M

2005-09-01

This research examined the interaction of organizational politics perceptions and employee age on job performance in 3 studies. On the basis of conservation of resources theory, the authors predicted that perceptions of politics would demonstrate their most detrimental effects on job performance for older workers. Results across the 3 studies provided strong support for the hypothesis that increases in politics perceptions are associated with decreases in job performance for older employees and that perceptions of politics do not affect younger employees' performance. Implications of these results, strengths and limitations, and directions for future research are discussed. Copyright 2005 APA, all rights reserved.

Short-channel field-effect transistors with 9-atom and 13-atom wide graphene nanoribbons

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

Llinas, Juan Pablo; Fairbrother, Andrew; Borin Barin, Gabriela

Bottom-up synthesized graphene nanoribbons and graphene nanoribbon heterostructures have promising electronic properties for high-performance field-effect transistors and ultra-low power devices such as tunneling field-effect transistors. However, the short length and wide band gap of these graphene nanoribbons have prevented the fabrication of devices with the desired performance and switching behavior. Here, by fabricating short channel (L ch ~ 20 nm) devices with a thin, high-κ gate dielectric and a 9-atom wide (0.95 nm) armchair graphene nanoribbon as the channel material, we demonstrate field-effect transistors with high on-current (I on > 1 μA at V d = -1 V) and highmore » I on /I off ~ 10 5 at room temperature. We find that the performance of these devices is limited by tunneling through the Schottky barrier at the contacts and we observe an increase in the transparency of the barrier by increasing the gate field near the contacts. Our results thus demonstrate successful fabrication of high-performance short-channel field-effect transistors with bottom-up synthesized armchair graphene nanoribbons.« less

Short-channel field-effect transistors with 9-atom and 13-atom wide graphene nanoribbons

DOE PAGES

Llinas, Juan Pablo; Fairbrother, Andrew; Borin Barin, Gabriela; ...

2017-09-21

Bottom-up synthesized graphene nanoribbons and graphene nanoribbon heterostructures have promising electronic properties for high-performance field-effect transistors and ultra-low power devices such as tunneling field-effect transistors. However, the short length and wide band gap of these graphene nanoribbons have prevented the fabrication of devices with the desired performance and switching behavior. Here, by fabricating short channel (L ch ~ 20 nm) devices with a thin, high-κ gate dielectric and a 9-atom wide (0.95 nm) armchair graphene nanoribbon as the channel material, we demonstrate field-effect transistors with high on-current (I on > 1 μA at V d = -1 V) and highmore » I on /I off ~ 10 5 at room temperature. We find that the performance of these devices is limited by tunneling through the Schottky barrier at the contacts and we observe an increase in the transparency of the barrier by increasing the gate field near the contacts. Our results thus demonstrate successful fabrication of high-performance short-channel field-effect transistors with bottom-up synthesized armchair graphene nanoribbons.« less

Digital nonlinearity compensation in high-capacity optical communication systems considering signal spectral broadening effect.

PubMed

Xu, Tianhua; Karanov, Boris; Shevchenko, Nikita A; Lavery, Domaniç; Liga, Gabriele; Killey, Robert I; Bayvel, Polina

2017-10-11

Nyquist-spaced transmission and digital signal processing have proved effective in maximising the spectral efficiency and reach of optical communication systems. In these systems, Kerr nonlinearity determines the performance limits, and leads to spectral broadening of the signals propagating in the fibre. Although digital nonlinearity compensation was validated to be promising for mitigating Kerr nonlinearities, the impact of spectral broadening on nonlinearity compensation has never been quantified. In this paper, the performance of multi-channel digital back-propagation (MC-DBP) for compensating fibre nonlinearities in Nyquist-spaced optical communication systems is investigated, when the effect of signal spectral broadening is considered. It is found that accounting for the spectral broadening effect is crucial for achieving the best performance of DBP in both single-channel and multi-channel communication systems, independent of modulation formats used. For multi-channel systems, the degradation of DBP performance due to neglecting the spectral broadening effect in the compensation is more significant for outer channels. Our work also quantified the minimum bandwidths of optical receivers and signal processing devices to ensure the optimal compensation of deterministic nonlinear distortions.

Investigation of Short Channel Effects on Device Performance for 60nm NMOS Transistor

NASA Astrophysics Data System (ADS)

Chinnappan, U.; Sanudin, R.

2017-08-01

In the aggressively scaled complementary metal oxide semiconductor (CMOS) devices, shallower p-n junctions and low sheet resistances are essential for short-channel effect (SCE) control and high device performance. The SCE are attributed to two physical phenomena that are the limitation imposed on electron drift characteristics in channel and the modification of the threshold voltage (Vth) due to the shortening channel length. The decrement of Vth with decrement in gate length is a well-known attribute in SCE known as “threshold voltage roll-off’. In this research, the Technology Computer Aided Design (TCAD) was used to model the SCE phenomenon effect on 60nm n-type metal oxide semiconductor (NMOS) transistor. There are three parameters being investigated, which are the oxide thickness (Tox), gate length (L), acceptor concentration (Na). The simulation data were used to visualise the effect of SCE on the 60nm NMOS transistor. Simulation data suggest that all three parameters have significant effect on Vth, and hence on the transistor performance. It is concluded that there is a trade-off among these three parameters to obtain an optimized transistor performance.

REMR (Repair, Evaluation, Maintenance, and Rehabilitation) Research Program Development Report.

DTIC Science & Technology

1983-02-01

that can halt fur- ther damage. Cases where rock reinforcement has been used to limit dis- tress will be evaluated to examine the effectiveness of the...Corps to perform its REMR activities in a rapid, quality- oriented, and cost- effective manner. b. Increase the service life of all Civil Works projects...environmental effects of REMR and development of an operations management system to provide guidance on scheduling REMR activities. REMR Terminology The

Making the case for mobile cognition: EEG and sports performance.

PubMed

Park, Joanne L; Fairweather, Malcolm M; Donaldson, David I

2015-05-01

In the high stakes world of International sport even the smallest change in performance can make the difference between success and failure, leading sports professionals to become increasingly interested in the potential benefits of neuroimaging. Here we describe evidence from EEG studies that either identify neural signals associated with expertise in sport, or employ neurofeedback to improve performance. Evidence for the validity of neurofeedback as a technique for enhancing sports performance remains limited. By contrast, progress in characterizing the neural correlates of sporting behavior is clear: frequency domain studies link expert performance to changes in alpha rhythms, whilst time-domain studies link expertise in response evaluation and motor output with modulations of P300 effects and readiness potentials. Despite early promise, however, findings have had relatively little impact for sports professionals, at least in part because there has been a mismatch between lab tasks and real sporting activity. After selectively reviewing existing findings and outlining limitations, we highlight developments in mobile EEG technology that offer new opportunities for sports neuroscience. Copyright © 2015 The Authors. Published by Elsevier Ltd.. All rights reserved.

Sensitivity of a critical tracking task to alcohol impairment

NASA Technical Reports Server (NTRS)

Tennant, J. A.; Thompson, R. R.

1973-01-01

A first order critical tracking task is evaluated for its potential to discriminate between sober and intoxicated performances. Mean differences between predrink and postdrink performances as a function of BAC are analyzed. Quantification of the results shows that intoxicated failure rates of 50% for blood alcohol concentrations (BACs) at or above 0.1%, and 75% for BACs at or above 0.14%, can be attained with no sober failure rates. A high initial rate of learning is observed, perhaps due to the very nature of the task whereby the operator is always pushed to his limit, and the scores approach a stable asymptote after approximately 50 trials. Finally, the implementation of the task as an ignition interlock system in the automobile environment is discussed. It is pointed out that lower critical performance limits are anticipated for the mechanized automotive units because of the introduction of larger hardware and neuromuscular lags. Whether such degradation in performance would reduce the effectiveness of the device or not will be determined in a continuing program involving a broader based sample of the driving population and performance correlations with both BACs and driving proficiency.

Stress shielding and fatigue limits of poly-ether-ether-ketone dental implants.

PubMed

Lee, Woo-Taek; Koak, Jai-Young; Lim, Young-Jun; Kim, Seong-Kyun; Kwon, Ho-Beom; Kim, Myung-Joo

2012-05-01

The poly-ether-ether-ketone (PEEK) polymer is of great interest as an alternative to titanium in orthopedics because of its biocompatibility and low elastic modulus. This study evaluated the fatigue limits of PEEK and the effects of the low elastic modulus PEEK in relation to existing dental implants. Compressive loading tests were performed with glass fiber-reinforced PEEK (GFR-PEEK), carbon fiber-reinforced PEEK (CFR-PEEK), and titanium rods. Among these tests, GFR-PEEK fatigue tests were performed according to ISO 14801. For the finite element analysis, three-dimensional models of dental implants and bone were constructed. The implants in the test groups were coated with a 0.5-mm thick and 5-mm long PEEK layer on the upper intrabony area. The strain energy densities (SED) were calculated, and the bone resorption was predicted. The fatigue limits of GFR-PEEK were 310 N and were higher than the static compressive strength of GFR-PEEK. The bone around PEEK-coated implants showed higher levels of SED than the bone in direct contact with the implants, and the wider diameter and stiffer implants showed lower levels of SED. The compressive strength of the GFR-PEEK and CFR-PEEK implants ranged within the bite force of the anterior and posterior dentitions, respectively, and the PEEK implants showed adequate fatigue limits for replacing the anterior teeth. Dental implants with PEEK coatings and PEEK implants may reduce stress shielding effects. Dental implant application of PEEK polymer-fatigue limit and stress shielding. Copyright © 2012 Wiley Periodicals, Inc.

Comparative research on tillable properties of diatomite-improved soils in the Yangtze River Delta region, China.

PubMed

Qu, Ji-Li; Zhao, Dong-Xue

2016-10-15

To improve soil texture and structure, techniques associated with physical, biological or chemical aspects are generally adopted, among which diatomite is an important soil conditioner. However, few studies have been conducted to investigate the physical, hydraulic and tillage performance of diatomite-improved soils. Consistency limits and compaction properties were investigated in this study, and several performance indicators were compared, such as the liquid limit, plastic limit and compactability, of silt, silt loam and silty-clay loam soils to which diatomite was added at volumetric ratios of 0%, 10%, 20%, and 30%. The results showed that diatomite significantly (p<0.05) improved the consistency limits, with the most preferred effects in the silt soil. The liquid limits were increased by 53.9%, 27.3%, and 14.7%, in the silt, silt loam and silty-clay loam soils, respectively, when the volumetric ratio was 30%. While diatomite lowered the maximum dry bulk density (MBD) of the classified soils, the optimum moisture content (OMC) was increased overall. The trend was consistent with the proportion of diatomite, and MBD decreased by 8.7%, 10.3%, and 13.2% in the silt, silt loam and silty-clay loam soils when 30% diatomite was mixed, whereas OMC increased by 28.7%, 22.4%, and 25.3%, respectively. Additionally, aggregate stability was negatively correlated with MBD but positively correlated with OMC. Diatomite exerts positive effects on soil mechanical strength, suggesting that soils from sludge farms are more tillable with a larger stabilized and workable matrix. Copyright © 2016 Elsevier B.V. All rights reserved.

Bottlenecks of the wavefront sensor based on the Talbot effect.

PubMed

Podanchuk, Dmytro; Kovalenko, Andrey; Kurashov, Vitalij; Kotov, Myhaylo; Goloborodko, Andrey; Danko, Volodymyr

2014-04-01

Physical constraints and peculiarities of the wavefront sensing technique, based on the Talbot effect, are discussed. The limitation on the curvature of the measurable wavefront is derived. The requirements to the Fourier spectrum of the periodic mask are formulated. Two kinds of masks are studied for their performance in the wavefront sensor. It is shown that the boundary part of the mask aperture does not contribute to the initial data for wavefront restoration. It is verified by experiment and computer simulation that the performance of the Talbot sensor, which meets established conditions, is similar to that of the Shack-Hartmann sensor.

ADHD and Adolescent Athletes

PubMed Central

Nazeer, Ahsan; Mansour, Miriam; Gross, Kathleen A.

2014-01-01

Attention-deficit hyperactivity disorder (ADHD) is a common neurodevelopmental disorder that affects the child and adolescent population. It is characterized by impairment in attention/concentration, hyperactivity, and impulsivity, all of which can impact performance of athletes. ADHD treatment within the athletic population is a unique challenge. The research in this field has been relatively limited. The National Collegiate Athletic Association and International Olympic Committee both regulate the use of psychostimulants for treatment of ADHD due to their performance-enhancing effects. In this article, authors have discussed the screening methods, pharmacological treatment, side effects, and behavioral approaches for the treatment of ADHD in adolescent athletes. PMID:24987666

Mastitis effects on reproductive performance in dairy cattle: a review.

PubMed

Kumar, Narender; Manimaran, A; Kumaresan, A; Jeyakumar, S; Sreela, L; Mooventhan, P; Sivaram, M

2017-04-01

The reproductive performance of dairy animals is influenced by several factors, and accumulating lines of evidence indicate that mastitis is one of the determinants. Most of the published information relating mastitis with reproduction has evolved based on retrospective approach rather than controlled clinical studies. The complex nature of both mastitis and reproduction could be a limiting factor for understanding their relationship in detail. In this review, we analyzed the available retrospective studies on the effects of clinical mastitis on reproductive function and explained the possible mechanisms by which mastitis affects reproduction in dairy animals.

NASA Glenn Research Center Experience with LENR Phenomenon

NASA Technical Reports Server (NTRS)

Wrbanek, Susan Y.; Fralick, Gustave C.; Wrbanek, John D.; Niedra, Janis M.

2012-01-01

Since 1989 NASA Glenn Research Center (GRC) has performed some small-scale limited experiments that show evidence of effects claimed by some to be evidence of Low Energy Nuclear Reactions (LENR). The research at GRC has involved observations and work on measurement techniques for observing the temperature effects in reactions of isotopes of hydrogen with palladium hydrides. The various experiments performed involved loading Pd with gaseous H2 and D2, and exposing Pd thin films to multi-bubble sonoluminescence in regular and deuterated water. An overview of these experiments and their results will be presented.

Propeller propulsion system integration: State of technology survey

NASA Technical Reports Server (NTRS)

Miley, S. J.; Vonlavante, E.

1985-01-01

A literature survey was performed to identify and review technical material applicable to the problem area of propeller propulsion system integration. The survey covered only aerodynamic interference aspects of the problem, and was restricted primarily to propeller effects on the airframe. The subject of airframe aerodynamic interference on the propeller was limited to the problem of vibration due to nonuniform inflow. The problem of airframe effects on propeller performance was not included. A total of 1121 references are given. The references are grouped into the subject areas of Aircraft Stability, Propulsive Efficiency, Aerodynamic Interference, Aerodynamic Interference-Propeller Vibration, and Miscellaneous.

NASA Glenn Research Center Experience with "LENR Phenomenon"

NASA Technical Reports Server (NTRS)

Wrbanek, Susan Y.; Fralick, Gustave C.; Wrbanek, John D.; Niedra, Janis M.

2012-01-01

Since 1989 NASA Glenn Research Center (GRC) has performed some small-scale limited experiments that show evidence of effects claimed by some to be evidence of Low Energy Nuclear Reactions (LENR). The research at GRC has involved observations and work on measurement techniques for observing the temperature effects in reactions of isotopes of hydrogen with palladium hydrides. The various experiments performed involved loading Pd with gaseous H2 and D2, and exposing Pd thin films to multi-bubble sonoluminescence in regular and deuterated water. An overview of these experiments and their results will be presented.

A model-based analysis of extinction ratio effects on phase-OTDR distributed acoustic sensing system performance

NASA Astrophysics Data System (ADS)

Aktas, Metin; Maral, Hakan; Akgun, Toygar

2018-02-01

Extinction ratio is an inherent limiting factor that has a direct effect on the detection performance of phase-OTDR based distributed acoustics sensing systems. In this work we present a model based analysis of Rayleigh scattering to simulate the effects of extinction ratio on the received signal under varying signal acquisition scenarios and system parameters. These signal acquisition scenarios are constructed to represent typically observed cases such as multiple vibration sources cluttered around the target vibration source to be detected, continuous wave light sources with center frequency drift, varying fiber optic cable lengths and varying ADC bit resolutions. Results show that an insufficient ER can result in high optical noise floor and effectively hide the effects of elaborate system improvement efforts.

Heisenberg limit for displacements with semiclassical states

NASA Astrophysics Data System (ADS)

Luis, Alfredo

2004-04-01

We analyze the quantum limit to the sensitivity of the detection of small displacements. We focus on the case of free particles and harmonic oscillators as the systems experiencing the displacement. We show that the minimum displacement detectable is proportional to the inverse of the square root of the mean value of the energy in the state experiencing the displacement (Heisenberg limit). We present a measuring scheme that reaches this limit using semiclassical states. We examine the performance of this strategy under realistic practical conditions by computing the effect of imperfections such as losses and nonunit detection efficiencies. This analysis confirms the robustness of this measuring strategy by showing that the experimental imperfections can be suitably compensated by increasing the mean energy of the input state.

Optical limiting properties of optically active phthalocyanine derivatives

NASA Astrophysics Data System (ADS)

Wang, Peng; Zhang, Shuang; Wu, Peiji; Ye, Cheng; Liu, Hongwei; Xi, Fu

2001-06-01

The optical limiting properties of four optically active phthalocyanine derivatives in chloroform solutions and epoxy resin thin plates were measured at 532 nm with 10 ns pulses. The excited state absorption cross-section σex and refractive-index cross-section σr were determined with the Z-scan technique. These chromophores possess larger σex than the ground state absorption cross-section σ0, indicating that they are the potential materials for reverse saturable absorption (RSA). The negative σr values of these chromophores add to the thermal contribution, producing a larger defocusing effect, which may be helpful in further enhancing their optical limiting performance. The optical limiting responses of the thin plate samples are stronger than those of the chloroform solutions.

Health economic value of an innovation: delimiting the scope and framework of future market entry agreements.

PubMed

Launois, Robert; Navarrete, Lucia Fiestas; Ethgen, Olivier; Le Moine, Jean-Gabriel; Gatsinga, René

2014-01-01

The objective of our paper is to offer a new, payer-friendly taxonomy of market entry agreements (MEAs) that aims to twin contracts with their methodological designs in an effort to clarify the distinction between contracts that are based on performance and those that are based on demonstrated effect. Our analysis proceeds in two stages: First, we delimit the scope and framework of pay for performance (P4P) and pay for demonstrated effect (P4E) agreements. Second, we distinguish the methodological designs supporting the implementation of each of these contracts. We elucidate why P4P contracts prevent the payer from funding the true effectiveness of an innovation by expanding on their limitations. These include: 1) the normative nature of comparisons, 2) the impossibility of true effect imputability for each individual, and 3) the use of intermediary outcome measures. We then explore three main criticisms that payers must take into account when reasoning in terms of performance rather than in terms of the product effectiveness. The potential effect that performance-based reimbursements may have on dissociating the components of the cost-effectiveness ratio constitutes an obstacle to a true health economic reasoning.

Genotypic Diversity Effects on the Performance of Taraxacum officinale Populations Increase with Time and Environmental Favorability

PubMed Central

Drummond, Emily B. M.; Vellend, Mark

2012-01-01

Within-population genetic diversity influences many ecological processes, but few studies have examined how environmental conditions may impact these short-term diversity effects. Over four growing seasons, we followed experimental populations of a clonal, ubiquitous weed, Taraxacum officinale, with different numbers of genotypes in relatively favorable fallow field and unfavorable mowed lawn environmental treatments. Population performance (measured as total leaf area, seed production or biomass) clearly and consistently increased with diversity, and this effect became stronger over the course of the experiment. Diversity effects were stronger, and with different underlying mechanisms, in the fallow field versus the mowed lawn. Large genotypes dominated in the fallow field driving overyielding (via positive selection effects), whereas in the mowed lawn, where performance was limited by regular disturbance, there was evidence for complementarity among genotypes (with one compact genotype in particular performing better in mixture than monoculture). Hence, we predict stronger genotypic diversity effects in environments where intense intraspecific competition enhances genotypic differences. Our four-year field experiment plus seedling establishment trials indicate that genotypic diversity effects have far-reaching and context-dependent consequences across generations. PMID:22348004

Setting limits on Effective Field Theories: the case of Dark Matter

NASA Astrophysics Data System (ADS)

Pobbe, Federico; Wulzer, Andrea; Zanetti, Marco

2017-08-01

The usage of Effective Field Theories (EFT) for LHC new physics searches is receiving increasing attention. It is thus important to clarify all the aspects related with the applicability of the EFT formalism in the LHC environment, where the large available energy can produce reactions that overcome the maximal range of validity, i.e. the cutoff, of the theory. We show that this does not forbid to set rigorous limits on the EFT parameter space through a modified version of the ordinary binned likelihood hypothesis test, which we design and validate. Our limit-setting strategy can be carried on in its full-fledged form by the LHC experimental collaborations, or performed externally to the collaborations, through the Simplified Likelihood approach, by relying on certain approximations. We apply it to the recent CMS mono-jet analysis and derive limits on a Dark Matter (DM) EFT model. DM is selected as a case study because the limited reach on the DM production EFT Wilson coefficient and the structure of the theory suggests that the cutoff might be dangerously low, well within the LHC reach. However our strategy can also be applied, if needed, to EFT's parametrising the indirect effects of heavy new physics in the Electroweak and Higgs sectors.

Intelligent Advisory Speed Limit Dedication in Highway Using VANET

PubMed Central

Md Noor, Rafidah; Yeo, Hwasoo; Jung, Jason J.

2014-01-01

Variable speed limits (VSLs) as a mean for enhancing road traffic safety are studied for decades to modify the speed limit based on the prevailing road circumstances. In this study the pros and cons of VSL systems and their effects on traffic controlling efficiency are summarized. Despite the potential effectiveness of utilizing VSLs, we have witnessed that the effectiveness of this system is impacted by factors such as VSL control strategy used and the level of driver compliance. Hence, the proposed approach called Intelligent Advisory Speed Limit Dedication (IASLD) as the novel VSL control strategy which considers the driver compliance aims to improve the traffic flow and occupancy of vehicles in addition to amelioration of vehicle's travel times. The IASLD provides the advisory speed limit for each vehicle exclusively based on the vehicle's characteristics including the vehicle type, size, and safety capabilities as well as traffic and weather conditions. The proposed approach takes advantage of vehicular ad hoc network (VANET) to accelerate its performance, in the way that simulation results demonstrate the reduction of incident detection time up to 31.2% in comparison with traditional VSL strategy. The simulation results similarly indicate the improvement of traffic flow efficiency, occupancy, and travel time in different conditions. PMID:24999493

Effects of Inboard Horizontal Field of View Display Limitations on Pilot Path Control During Total In-Flight Simulator (TIFS) Flight Test

NASA Technical Reports Server (NTRS)

Kramer, Lynda J.; Parrish, Russell V.; Williams, Steven P.; Lavell, Jeffrey S.

1999-01-01

A flight test was conducted aboard Calspan's Total In-Flight Simulator (TIFS) aircraft by researchers within the External Visibility System (XVS) element of the High-Speed Research program. The purpose was to investigate the effects of inboard horizontal field of view (FOV) display limitations on pilot path control and to learn about the TIFS capabilities and limitations for possible use in future XVS flight tests. The TIFS cockpit windows were masked to represent the front XVS display area and the High-Speed Civil Transport side windows, as viewed by the pilot. Masking limited the forward FOV to 40 deg. horizontal and 50 deg. vertical for the basic flight condition, With an increase of 10 deg. horizontal in the inboard direction for the increased FOV flight condition. Two right-hand approach tasks (base-downwind-final) with a left crosswind on final were performed by three pilots using visual flight rules at Niagara Falls Airport. Each of the two tasks had three replicates for both horizontal FOV conditions, resulting in twelve approaches per test subject. Limited objective data showed that an increase of inboard FOV had no effect (deficiences in objective data measurement capabilities were noted). However, subjective results showed that a 50 deg. FOV was preferred over the 40 deg. FOV.

Tailored instructor feedback leads to more effective virtual-reality laparoscopic training.

PubMed

Paschold, M; Huber, T; Zeißig, S R; Lang, H; Kneist, Werner

2014-03-01

Laparoscopic novices begin at different performance levels, and studies on tailored training concepts are warranted. The effect of verbal instructor feedback has been investigated with varying results, and its effectiveness in virtual-reality laparoscopic (VRL) simulations still is unclear. This study aimed to determine whether laparoscopic novices with lower initial performance statuses may profit from training with intensive instructor feedback. A prospective, single-blinded study was performed within a week-long curricular course. In this study, 20 medical students performed a complex bimanual maneuver on a VRL simulator. There was a division in performance levels, with a high-performer group (HPG) that received a better median score and a low-performer group (LPG). During the training phase, only the initial LPG received standardized instructor feedback in a one-to-one setting. The final assessment of skills for both groups involved performing the task without feedback at the end of the course. The HPG and LPG showed significantly different initial performance levels according global and categorized (time, economics, error) scores (p < 0.005). This difference disappeared quickly throughout the instructor feedback phase. The final assessment demonstrated that both groups were at the same level of performance. This is the first study to use a tailored training concept with instructor feedback limited to the LPG. The tailored training was effective and economic for the laparoscopic novices and their teachers.

The Effects of Block Size on the Performance of Coherent Caches in Shared-Memory Multiprocessors

DTIC Science & Technology

1993-05-01

increase with the bandwidth and latency. For those applications with poor spatial locality, the best choice of cache line size is determined by the...observation was used in the design of two schemes: LimitLESS di- rectories and Tag caches. LimitLESS directories [15] were designed for the ALEWIFE...small packets may be used to avoid network congestion. The most important factor influencing the choice of cache line size for a multipro- cessor is the

Sensitivity to Change and Responsiveness of Four Balance Measures for Community-Dwelling Older Adults

PubMed Central

Latham, Nancy K.; Jette, Alan M.; Wagenaar, Robert C.; Ni, Pengsheng; Slavin, Mary D.; Bean, Jonathan F.

2012-01-01

Background Impaired balance has a significant negative impact on mobility, functional independence, and fall risk in older adults. Although several, well-respected balance measures are currently in use, there is limited evidence regarding the most appropriate measure to assess change in community-dwelling older adults. Objective The aim of this study was to compare floor and ceiling effects, sensitivity to change, and responsiveness across the following balance measures in community-dwelling elderly people with functional limitations: Berg Balance Scale (BBS), Performance-Oriented Mobility Assessment total scale (POMA-T), POMA balance subscale (POMA-B), and Dynamic Gait Index (DGI). Design Retrospective data from a 16-week exercise trial were used. Secondary analyses were conducted on the total sample and by subgroups of baseline functional limitation or baseline balance scores. Methods Participants were 111 community-dwelling older adults 65 years of age or older, with functional limitations. Sensitivity to change was assessed using effect size, standardized response mean, and paired t tests. Responsiveness was assessed using minimally important difference (MID) estimates. Results No floor effects were noted. Ceiling effects were observed on all measures, including in people with moderate to severe functional limitations. The POMA-T, POMA-B, and DGI showed significantly larger ceiling effects compared with the BBS. All measures had low sensitivity to change in total sample analyses. Subgroup analyses revealed significantly better sensitivity to change in people with lower compared with higher baseline balance scores. Although both the total sample and lower baseline balance subgroups showed statistically significant improvement from baseline to 16 weeks on all measures, only the lower balance subgroup showed change scores that consistently exceeded corresponding MID estimates. Limitations This study was limited to comparing 4 measures of balance, and anchor-based methods for assessing MID could not be reported. Conclusions Important limitations, including ceiling effects and relatively low sensitivity to change and responsiveness, were noted across all balance measures, highlighting their limited utility across the full spectrum of the community-dwelling elderly population. New, more challenging measures are needed for better discrimination of balance ability in community-dwelling elderly people at higher functional levels. PMID:22114200

[Effects of performance-volume limit on the institutional financing of the Clinical Centre of the University of Pécs, Hungary].

PubMed

Endrei, Dóra; Kollár, Lajos; Bódis, József; Imhof, Gábor; Zemplényi, Antal; Vas, Gábor; Boncz, Imre

2010-08-01

The aim of our study is to demonstrate the effects of performance-volume limit (PVL) on the institutional financing of the Clinical Centre of the University of Pécs (CC UP). The data involved in the analysis are based on the reports towards the National Health Insurance Fund Administration (NHIFA), concerning the active inpatient care by specialist in the period between 2004 and 2008. We determined the real NHIFA reimbursement per weighted case number and the financial loss caused by the PVL. We analyzed the proportion of local health care obligation and urgency cases in comparison of various clinics. The reimbursement per weighted case number of CC UP has been less than the pre-announced NHIFA amounts after the installation of PVL. During the examined 5 years, i.e. 2004-2008, the loss in case of CC UP has been up to 3.256 million HUF due to the PVL. Concerning the whole of CC UP it means that 25.3 % of the treated cases and 24.5 % of the executed weighted case number has been out of local health care obligation. Studying the ratio of urgency cases inside the total volume of medical attendance, it is represented that 31.5 % of the cases and 36.1 % of the weighted case numbers came from the treatment of urgency cases. The introduction of performance-volume limit considerably reduced the health insurance financing of CC UP between 2004 and 2008.

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

Sevik, James; Wallner, Thomas; Pamminger, Michael

The efficiency improvement and emissions reduction potential of lean and exhaust gas recirculation (EGR)-dilute operation of spark-ignition gasoline engines is well understood and documented. However, dilute operation is generally limited by deteriorating combustion stability with increasing inert gas levels. The combustion stability decreases due to reduced mixture flame speeds resulting in significantly increased combustion initiation periods and burn durations. A study was designed and executed to evaluate the potential to extend lean and EGR-dilute limits using a low-energy transient plasma ignition system. The low-energy transient plasma was generated by nanosecond pulses and its performance compared to a conventional transistorized coilmore » ignition (TCI) system operated on an automotive, gasoline direct-injection (GDI) single-cylinder research engine. The experimental assessment was focused on steady-state experiments at the part load condition of 1500 rpm 5.6 bar indicated mean effective pressure (IMEP), where dilution tolerance is particularly critical to improving efficiency and emission performance. Experimental results suggest that the energy delivery process of the low-energy transient plasma ignition system significantly improves part load dilution tolerance by reducing the early flame development period. Statistical analysis of relevant combustion metrics was performed in order to further investigate the effects of the advanced ignition system on combustion stability. Results confirm that at select operating conditions EGR tolerance and lean limit could be improved by as much as 20% (from 22.7 to 27.1% EGR) and nearly 10% (from λ = 1.55 to 1.7) with the low-energy transient plasma ignition system.« less

Performance Evaluation and Improvement of Ferroelectric Field-Effect Transistor Memory

NASA Astrophysics Data System (ADS)

Yu, Hyung Suk

Flash memory is reaching scaling limitations rapidly due to reduction of charge in floating gates, charge leakage and capacitive coupling between cells which cause threshold voltage fluctuations, short retention times, and interference. Many new memory technologies are being considered as alternatives to flash memory in an effort to overcome these limitations. Ferroelectric Field-Effect Transistor (FeFET) is one of the main emerging candidates because of its structural similarity to conventional FETs and fast switching speed. Nevertheless, the performance of FeFETs have not been systematically compared and analyzed against other competing technologies. In this work, we first benchmark the intrinsic performance of FeFETs and other memories by simulations in order to identify the strengths and weaknesses of FeFETs. To simulate realistic memory applications, we compare memories on an array structure. For the comparisons, we construct an accurate delay model and verify it by benchmarking against exact HSPICE simulations. Second, we propose an accurate model for FeFET memory window since the existing model has limitations. The existing model assumes symmetric operation voltages but it is not valid for the practical asymmetric operation voltages. In this modeling, we consider practical operation voltages and device dimensions. Also, we investigate realistic changes of memory window over time and retention time of FeFETs. Last, to improve memory window and subthreshold swing, we suggest nonplanar junctionless structures for FeFETs. Using the suggested structures, we study the dimensional dependences of crucial parameters like memory window and subthreshold swing and also analyze key interference mechanisms.

Frequency-Limiting Effects on Speech and Environmental Sound Identification for Cochlear Implant and Normal Hearing Listeners

PubMed Central

Chang, Son-A; Won, Jong Ho; Kim, HyangHee; Oh, Seung-Ha; Tyler, Richard S.; Cho, Chang Hyun

2018-01-01

Background and Objectives It is important to understand the frequency region of cues used, and not used, by cochlear implant (CI) recipients. Speech and environmental sound recognition by individuals with CI and normal-hearing (NH) was measured. Gradients were also computed to evaluate the pattern of change in identification performance with respect to the low-pass filtering or high-pass filtering cutoff frequencies. Subjects and Methods Frequency-limiting effects were implemented in the acoustic waveforms by passing the signals through low-pass filters (LPFs) or high-pass filters (HPFs) with seven different cutoff frequencies. Identification of Korean vowels and consonants produced by a male and female speaker and environmental sounds was measured. Crossover frequencies were determined for each identification test, where the LPF and HPF conditions show the identical identification scores. Results CI and NH subjects showed changes in identification performance in a similar manner as a function of cutoff frequency for the LPF and HPF conditions, suggesting that the degraded spectral information in the acoustic signals may similarly constraint the identification performance for both subject groups. However, CI subjects were generally less efficient than NH subjects in using the limited spectral information for speech and environmental sound identification due to the inefficient coding of acoustic cues through the CI sound processors. Conclusions This finding will provide vital information in Korean for understanding how different the frequency information is in receiving speech and environmental sounds by CI processor from normal hearing. PMID:29325391

Frequency-Limiting Effects on Speech and Environmental Sound Identification for Cochlear Implant and Normal Hearing Listeners.

PubMed

Chang, Son-A; Won, Jong Ho; Kim, HyangHee; Oh, Seung-Ha; Tyler, Richard S; Cho, Chang Hyun

2017-12-01

It is important to understand the frequency region of cues used, and not used, by cochlear implant (CI) recipients. Speech and environmental sound recognition by individuals with CI and normal-hearing (NH) was measured. Gradients were also computed to evaluate the pattern of change in identification performance with respect to the low-pass filtering or high-pass filtering cutoff frequencies. Frequency-limiting effects were implemented in the acoustic waveforms by passing the signals through low-pass filters (LPFs) or high-pass filters (HPFs) with seven different cutoff frequencies. Identification of Korean vowels and consonants produced by a male and female speaker and environmental sounds was measured. Crossover frequencies were determined for each identification test, where the LPF and HPF conditions show the identical identification scores. CI and NH subjects showed changes in identification performance in a similar manner as a function of cutoff frequency for the LPF and HPF conditions, suggesting that the degraded spectral information in the acoustic signals may similarly constraint the identification performance for both subject groups. However, CI subjects were generally less efficient than NH subjects in using the limited spectral information for speech and environmental sound identification due to the inefficient coding of acoustic cues through the CI sound processors. This finding will provide vital information in Korean for understanding how different the frequency information is in receiving speech and environmental sounds by CI processor from normal hearing.

More than a score: a qualitative study of ancillary benefits of performance measurement.

PubMed

Powell, Adam A; White, Katie M; Partin, Melissa R; Halek, Krysten; Hysong, Sylvia J; Zarling, Edwin; Kirsh, Susan R; Bloomfield, Hanna E

2014-08-01

Prior research has examined clinical effects of performance measurement systems. To the extent that non-clinical effects have been researched, the focus has been on negative unintended consequences. Yet, these same systems may also have ancillary benefits for patients and providers--that is, benefits that extend beyond improvements on clinical measures. The purpose of this study is to identify and describe potential ancillary benefits of performance measures as perceived by primary care staff and facility leaders in a large US healthcare system. In-person individual semistructured interviews were conducted with 59 primary care staff and facility leaders at four Veterans Health Administration facilities. Transcribed interviews were coded and organised into thematic categories. Interviewed staff observed that local performance measurement implementation practices can result in increased patient knowledge and motivation. These effects on patients can lead to improved performance scores and additional ancillary benefits. Performance measurement implementation can also directly result in ancillary benefits for the patients and providers. Patients may experience greater satisfaction with care and psychosocial benefits associated with increased provider-patient communication. Ancillary benefits of performance measurement for providers include increased pride in individual or organisational performance and greater confidence that one's practice is grounded in evidence-based medicine. A comprehensive understanding of the effects of performance measurement systems needs to incorporate ancillary benefits as well as effects on clinical performance scores and negative unintended consequences. Although clinical performance has been the focus of most evaluations of performance measurement to date, both patient care and provider satisfaction may improve more rapidly if all three categories of effects are considered when designing and evaluating performance measurement systems. Published by the BMJ Publishing Group Limited. For permission to use (where not already granted under a licence) please go to http://group.bmj.com/group/rights-licensing/permissions.

Origin of the performances degradation of two-dimensional-based metal-oxide-semiconductor field effect transistors in the sub-10 nm regime: A first-principles study

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

Lu, Anh Khoa Augustin; IMEC, 75 Kapeldreef, B-3001 Leuven; Pourtois, Geoffrey

2016-01-25

The impact of the scaling of the channel length on the performances of metal-oxide-semiconductor field effect transistors, based on two-dimensional (2D) channel materials, is theoretically investigated, using density functional theory combined with the non-equilibrium Green's function method. It is found that the scaling of the channel length below 10 nm leads to strong device performance degradations. Our simulations reveal that this degradation is essentially due to the tunneling current flowing between the source and the drain in these aggressively scaled devices. It is shown that this electron tunneling process is modulated by the effective mass of the 2D channel material, andmore » sets the limit of the scaling in future transistor designs.« less

Analytical study of the cruise performance of a class of remotely piloted, microwave-powered, high-altitude airplane platforms

NASA Technical Reports Server (NTRS)

Morris, C. E. K., Jr.

1981-01-01

Each cycle of the flight profile consists of climb while the vehicle is tracked and powered by a microwave beam, followed by gliding flight back to a minimum altitude. Parameter variations were used to define the effects of changes in the characteristics of the airplane aerodynamics, the power transmission systems, the propulsion system, and winds. Results show that wind effects limit the reduction of wing loading and increase the lift coefficient, two effective ways to obtain longer range and endurance for each flight cycle. Calculated climb performance showed strong sensitivity to some power and propulsion parameters. A simplified method of computing gliding endurance was developed.

Closed-form confidence intervals for functions of the normal mean and standard deviation.

PubMed

Donner, Allan; Zou, G Y

2012-08-01

Confidence interval methods for a normal mean and standard deviation are well known and simple to apply. However, the same cannot be said for important functions of these parameters. These functions include the normal distribution percentiles, the Bland-Altman limits of agreement, the coefficient of variation and Cohen's effect size. We present a simple approach to this problem by using variance estimates recovered from confidence limits computed for the mean and standard deviation separately. All resulting confidence intervals have closed forms. Simulation results demonstrate that this approach performs very well for limits of agreement, coefficients of variation and their differences.

Channel interaction limits melodic pitch perception in simulated cochlear implants

PubMed Central

Crew, Joseph D.; Galvin, John J.; Fu, Qian-Jie

2012-01-01

In cochlear implants (CIs), melodic pitch perception is limited by the spectral resolution, which in turn is limited by the number of spectral channels as well as interactions between adjacent channels. This study investigated the effect of channel interaction on melodic contour identification (MCI) in normal-hearing subjects listening to novel 16-channel sinewave vocoders that simulated channel interaction in CI signal processing. MCI performance worsened as the degree of channel interaction increased. Although greater numbers of spectral channels may be beneficial to melodic pitch perception, the present data suggest that it is also important to improve independence among spectral channels. PMID:23145706

The forward masking effects of low-level laser glare on target location performance in a visual search task

NASA Astrophysics Data System (ADS)

Reddix, M. D.; Dandrea, J. A.; Collyer, P. D.

1992-01-01

The present study examined the effects of low-intensity laser glue, far below a level that would cause ocular damage or flashblindness, on the visually guided performance of aviators. With a forward-masking paradigm, this study showed that the time at which laser glare is experienced, relative to initial acquisition of visual information, differentially affects the speed and accuracy of target-location performance. Brief exposure (300 ms) to laser glare, terminating with a visual scene's onset, produced significant decrements in target-location performance relative to a no-glare control whereas a 150 and 300-ms delay of display onset (DDO) had very little effect. The intensity of the light entering the eye and producing these effects was far below the Maximum Permissible Exposure (MPE) limit for safe viewing of coherent light produced by an argon laser. In addition, these effects were modulated by the distance of the target from the center of the visual display. This study demonstrated that the presence of laser glare is not sufficient, in and of itself, to diminish target-location performance. The time at which laser glare is experienced is an important factor in determining the probability and extent of visually mediated performance decrements.

The relationship between employees' perceptions of human resource systems and organizational performance: examining mediating mechanisms and temporal dynamics.

PubMed

Piening, Erk P; Baluch, Alina M; Salge, Torsten Oliver

2013-11-01

Given the limited understanding of temporal issues in extant theorizing about the link between human resource management (HRM) and performance, in this study we aim to shed light on how, when, and why HR interventions affect organizational performance. On the basis of longitudinal, multi-informant and multisource data from public hospital services in England, we provide new insights into the complex interplay between employees' perceptions of HR systems, job satisfaction, and performance outcomes over time. The dynamic panel data analyses provide support for changes in employees' experience of an HR system being related to subsequent changes in customer satisfaction, as mediated by changes in job satisfaction, albeit these effects decrease over time. Moreover, our longitudinal analyses highlight the importance of feedback effects in the HRM-performance chain, which otherwise appears to evolve in a cyclical manner. (c) 2013 APA, all rights reserved.

Providers with Limited Experience Perform Better in Advanced Life Support with Assistance Using an Interactive Device with an Automated External Defibrillator Linked to a Ventilator.

PubMed

Busch, Christian Werner; Qalanawi, Mohammed; Kersten, Jan Felix; Kalwa, Tobias Johannes; Scotti, Norman Alexander; Reip, Wikhart; Doehn, Christoph; Maisch, Stefan; Nitzschke, Rainer

2015-10-01

Medical teams with limited experience in performing advanced life support (ALS) or with a low frequency of cardiopulmonary resuscitation (CPR) while on duty, often have difficulty complying with CPR guidelines. This study evaluated whether the quality of CPR of trained medical students, who served as an example of teams with limited experience in ALS, could be improved with device assistance. The primary outcome was the hands-off time (i.e., the percentage of the entire CPR time without chest compressions). The secondary outcome was seven time intervals, which should be as short as possible, and the quality of ventilations and chest compressions on the mannequin. We compared standard CPR equipment to an interactive device with visual and acoustic instructions for ALS workflow measures to guide briefly trained medical students through the ALS algorithm in a full-scale mannequin simulation study with a randomized crossover study design. The study equipment consisted of an automatic external defibrillator and ventilator that were electronically linked and communicating as a single system. Included were regular medical students in the third to sixth years of medical school of one class who provided written informed consent for voluntary participation and for the analysis of their CPR performance data. No exclusion criteria were applied. For statistical measures of evaluation we used an analysis of variance for crossover trials accounting for treatment effect, sequence effect, and carry-over effect, with adjustment for prior practical experience of the participants. Forty-two medical students participated in 21 CPR sessions, each using the standard and study equipment. Regarding the primary end point, the study equipment reduced the hands-off time from 40.1% (95% confidence interval [CI] 36.9-43.4%) to 35.6% (95% CI 32.4-38.9%, p = 0.031) compared with the standard equipment. Within the prespecified secondary end points, study equipment reduced the time interval until the first rescuer changeover from 273 s (95% CI 244-302 s) to 223 s (95% CI 194-253 s, p = 0.001) and increased the percentage of ventilations with a correct tidal volume of 400-600 mL from 34.3% (95% CI 19.0-49.6%) to 60.9% (95% CI 45.6-76.2%, p = 0.018). The assist device increased the rescuers' CPR quality. CPR providers with limited experience or a limited frequency of CPR performance (i.e., rural Emergency Medical Services crew) may potentially benefit from this assist device. Copyright © 2015 Elsevier Inc. All rights reserved.

Effects of helicopter noise and vibration on pilot performance (as measured in a fixed-base flight simulator)

NASA Technical Reports Server (NTRS)

Stave, A. M.

1973-01-01

The effects of noise and vibration on pilot performance are described. Pilot subjects were required to fly VTOL commercial IFR schedules using the computer simulation facilities. The routes flown simulated closely metropolitan routes flown currently by a helicopter airline. The duration of simulator flights ranged from 3 to 8 hours. Subjects were exposed to noise sound pressure levels ranging from 74dB (ambient) to 100dB and 17 Hz vibration stimuli ranging from .1 g to .3 g measured at the floor directly beneath the pilot's seat. Despite subject reports of extreme fatigue in these long flights, performance did not degrade. A curve of performance shows a slow improvement for the first three hours of exposure and a slight loss in performance during the remainder of the flight. As environmental stress conditions (noise, vibration, and time in the simulator) increased, subject performance improved. Within the limits of this study, the higher the stress the better the performance.

40 CFR 59.202 - Definitions.

Code of Federal Regulations, 2013 CFR

2013-07-01

... effectiveness of laundry detergents and/or provides specialized performance. Laundry starch product means a... prolong a crisp look and may also facilitate ironing of the fabric. “Laundry starch product” includes, but it not limited to, fabric finish, sizing, and starch. Lawn and garden insecticide means an...

40 CFR 59.202 - Definitions.

Code of Federal Regulations, 2014 CFR

2014-07-01

... effectiveness of laundry detergents and/or provides specialized performance. Laundry starch product means a... prolong a crisp look and may also facilitate ironing of the fabric. “Laundry starch product” includes, but it not limited to, fabric finish, sizing, and starch. Lawn and garden insecticide means an...

40 CFR 59.202 - Definitions.

Code of Federal Regulations, 2012 CFR

2012-07-01

... effectiveness of laundry detergents and/or provides specialized performance. Laundry starch product means a... prolong a crisp look and may also facilitate ironing of the fabric. “Laundry starch product” includes, but it not limited to, fabric finish, sizing, and starch. Lawn and garden insecticide means an...

Effects of extended discharge time and revolution counts for ready-mixed concrete.

DOT National Transportation Integrated Search

2014-12-01

Specifications for ready-mixed concrete limit drum revolution and mixing time to 250 drum revolutions and/or : 1.5 hours before discharge. These specifications have been in place for many years with the objective of ensuring : the quality and perform...

Barriers to Evaluation

ERIC Educational Resources Information Center

Charley, Lois

2007-01-01

According to the Department of Health and Human Services, "good program evaluations assess programs performance, measure impacts on families and communities, and document program successes." With this information, programs are able to direct limited resources to where they are most needed and most effective in their communities. This article is…

Demonstration and Evaluation of Innovative Wastewater Main Rehabilitation Technologies (WERF Report INFR4R11)

EPA Science Inventory

The lack of knowledge on the performance of innovative wastewater rehabilitation technologies, specifically for large-diameter pipes, and the limited ability to determine the most cost-effective, long-term rehabilitation methods for wastewater collection systems, has been identif...

Test Operations Procedure (TOP) 01-1-025 Camouflage Performance Testing Using Observers

DTIC Science & Technology

2016-05-05

15. SUBJECT TERMS camouflage, detection, blending , signatures 16. SECURITY CLASSIFICATION OF: 17. LIMITATION OF ABSTRACT SAR 18...21 6.2 Blending Data... learning effect on observers. If military personnel are required for testing, determine if Military Occupational Specialty (MOS) qualified Soldier

Effect of Nonlocal Electron Transport in Both Directions on the Symmetry of Polar-Drive--Ignition Targets

NASA Astrophysics Data System (ADS)

Delettrez, J. A.; Collins, T. J. B.; Shvydky, A.; Moses, G.; Cao, D.; Marinak, M. M.

2012-10-01

A nonlocal, multigroup diffusion model for thermal electron transportfootnotetextG. P. Schurtz, Ph. D. Nicola"i, and M. Busquet, Phys. Plasmas 7, 4238 (2000). has been added to the 2-D hydrodynamic code DRACO. This model has been applied to simulations of polar-drive (PD) NIF ignition designs. Previous simulations were carried out with a constant flux-limiter model in both the radial and transverse directions. Due to the nonsymmetry of PD illumination, these implosions suffer from low-mode nonuniformities that affect their performance. Nonlocal electron transport in both directions is expected to reduce these nonuniformities. The 2-D thermal electron flux from simulations, using either the nonlocal model or the standard flux-limited approach, will be compared and the effect of the nonlocal transport model on the growth of the nonuniformities and on target performance will be presented. This work was supported by the U.S. Department of Energy Office of Inertial Confinement Fusion under Cooperative Agreement No. DE-FC52-08NA28302.

The measured performance of a grazing incidence relay optics telescope for solar X-ray astronomy

NASA Technical Reports Server (NTRS)

Moses, Dan; Krieger, Allen S.; Davis, John M.

1986-01-01

The design, fabrication, and test performance of a grazing-incidence diverging magnifier (GIDM) for use in high-resolution X-ray imaging of the solar corona are described. The GIDM, designed to be mounted in front of the focus of a 30.48-cm Wolter-Schwarzschild primary, is an Ni-coated Be hyperboloid-hyperboloid structure of principal diameter 3.15 cm; the two components are mounted on a central steel plate which acts as a support and spacer. The combined instrument has overall length 1.9 m, effective focal length 5.4 m, and plate scale 26.0 micron/arcsec. In point- and line-source measurements in an 89.5-m vacuum test facility, the on-axis resolution is shown to be equal to that of the primary alone. The field of view for 1-arcsec resolution is limited to 1.25 arcmin in radius, but the effective-area limitation is less significant when CCD detectors of high quantum efficiency are used instead of film.

Limits to Open Class Performance?

NASA Technical Reports Server (NTRS)

Bowers, Albion H.

2007-01-01

This viewgraph presentation describes the limits to open class performance. The contents include: 1) Standard Class; 2) 15m/Racing Class; 3) Open Class; and 4) Design Solutions associated with assumptions, limiting parameters, airfoil performance, current trends, and analysis.

Determination of ametoctradin residue in fruits and vegetables by modified quick, easy, cheap, effective, rugged, and safe method using ultra-performance liquid chromatography/tandem mass spectrometry.

PubMed

Hu, Mingfeng; Liu, Xingang; Dong, Fengshou; Xu, Jun; Li, Shasha; Xu, Hanqing; Zheng, Yongquan

2015-05-15

A rapid, effective and sensitive method to quantitatively determine ametoctradin residue in apple, cucumber, cabbage, tomato and grape was developed and validated using ultra-performance liquid chromatography coupled with tandem mass spectrometry (UPLC-MS/MS). The target compound was determined in less than 5.0 min using an electrospray ionisation source in positive mode (ESI+). The limit of detection was below 0.043 μg kg(-1), whereas the limits of quantification did not exceed 0.135 μg kg(-1) in all five matrices. The method showed excellent linearity (R(2)>0.9969) for the target compound. Recovery studies were performed in all matrices at three spiked levels (1, 10 and 100 μg L(-1)). The mean recoveries from five matrices ranged from 81.81% to 100.1%, with intra-day relative standard deviations (RSDr) in the range of 0.65-7.88% for the test compound. This method will be useful for the quick and routine detection of ametoctradin residues in potato, grape, cucumber, apple and tomato. Copyright © 2014 Elsevier Ltd. All rights reserved.