Science.gov

Sample records for plants feedback experience

  1. Range-Expanding Populations of a Globally Introduced Weed Experience Negative Plant-Soil Feedbacks

    PubMed Central

    Andonian, Krikor; Hierro, José L.; Khetsuriani, Liana; Becerra, Pablo; Janoyan, Grigor; Villarreal, Diego; Cavieres, Lohengrin; Fox, Laurel R.; Callaway, Ragan M.

    2011-01-01

    Background Biological invasions are fundamentally biogeographic processes that occur over large spatial scales. Interactions with soil microbes can have strong impacts on plant invasions, but how these interactions vary among areas where introduced species are highly invasive vs. naturalized is still unknown. In this study, we examined biogeographic variation in plant-soil microbe interactions of a globally invasive weed, Centaurea solstitialis (yellow starthistle). We addressed the following questions (1) Is Centaurea released from natural enemy pressure from soil microbes in introduced regions? and (2) Is variation in plant-soil feedbacks associated with variation in Centaurea's invasive success? Methodology/Principal Findings We conducted greenhouse experiments using soils and seeds collected from native Eurasian populations and introduced populations spanning North and South America where Centaurea is highly invasive and noninvasive. Soil microbes had pervasive negative effects in all regions, although the magnitude of their effect varied among regions. These patterns were not unequivocally congruent with the enemy release hypothesis. Surprisingly, we also found that Centaurea generated strong negative feedbacks in regions where it is the most invasive, while it generated neutral plant-soil feedbacks where it is noninvasive. Conclusions/Significance Recent studies have found reduced below-ground enemy attack and more positive plant-soil feedbacks in range-expanding plant populations, but we found increased negative effects of soil microbes in range-expanding Centaurea populations. While such negative feedbacks may limit the long-term persistence of invasive plants, such feedbacks may also contribute to the success of invasions, either by having disproportionately negative impacts on competing species, or by yielding relatively better growth in uncolonized areas that would encourage lateral spread. Enemy release from soil-borne pathogens is not sufficient to

  2. Technical performance of thermal plants worldwide: Experience feedback and objectives for the future

    SciTech Connect

    Glorian, D.

    1996-12-31

    For future thermal electricity generation, the electricity producer facing needs for extension or renewal of his own generating capacity can choose among a large number of proven technologies. These technologies can be nuclear or conventional (fossil-fired): steam turbines, cogeneration or gas turbines. The economic competitiveness of these different types of installations over their entire lifetime is calculated on the basis of various cost assumptions and/or scenarios, taking into account capital investment, fuel, operating and maintenance costs, etc. Equally important are such factors as construction duration, discount rate, service lifetime, usage mode (baseload, intermediate load or peak load). In addition, costs and hypotheses in relation to the environment should be taken into account, including the cost of dismantling nuclear power plants. Hypotheses concerning the service delivered to the grid -- i.e. the expected availability of the plant -- is one of the main factors governing the quality of service provided. It is evident that this factor is an almost perfect mirror of quality of service for units operated in baseload mode. For intermediate or peak load operation, other factors such as successful startup rate and load following capabilities must also be considered. This paper deals with experience feedback in the area of availability factors for nuclear and conventional power plants (steam turbines) of over 100MW around the world. The assumptions for future -- i.e. new -- plants are compared against experience feedback. These results are presented in this paper.

  3. Assessment of Habitat Suitability Is Affected by Plant-Soil Feedback: Comparison of Field and Garden Experiment

    PubMed Central

    Hemrová, Lucie; Knappová, Jana; Münzbergová, Zuzana

    2016-01-01

    Background Field translocation experiments (i.e., the introduction of seeds or seedlings of different species into different localities) are commonly used to study habitat associations of species, as well as factors limiting species distributions and local abundances. Species planted or sown in sites where they naturally occur are expected to perform better or equally well compared to sites at which they do not occur or are rare. This, however, contrasts with the predictions of the Janzen-Connell hypothesis and commonly reported intraspecific negative plant-soil feedback. The few previous studies indicating poorer performance of plants at sites where they naturally occur did not explore the mechanisms behind this pattern. Aims and Methods In this study, we used field translocation experiments established using both seeds and seedlings to study the determinants of local abundance of four dominant species in grasslands. To explore the possible effects of intraspecific negative plant-soil feedback on our results, we tested the effect of local species abundance on the performance of the plants in the field experiment. In addition, we set up a garden experiment to explore the intensity of intraspecific as well as interspecific feedback between the dominants used in the experiment. Key Results In some cases, the distribution and local abundances of the species were partly driven by habitat conditions at the sites, and species performed better at their own sites. However, the prevailing pattern was that the local dominants performed worse at sites where they naturally occur than at any other sites. Moreover, the success of plants in the field experiment was lower in the case of higher intraspecific abundance prior to experimental setup. In the garden feedback experiment, two of the species performed significantly worse in soils conditioned by their species than in soils conditioned by the other species. In addition, the performance of the plants was significantly

  4. Native and non-native ruderals experience similar plant-soil feedbacks and neighbor effects in a system where they coexist.

    PubMed

    Chiuffo, Mariana C; MacDougall, Andrew S; Hierro, José L

    2015-11-01

    Recent applications of coexistence theory to plant invasions posit that non-natives establish in resident communities through either niche differences or traits conferring them with fitness advantages, the former being associated with coexistence and the latter with dominance and competitive exclusion. Plant-soil feedback is a mechanism that is known to explain both coexistence and dominance. In a system where natives and non-natives appear to coexist, we explored how plant-soil feedbacks affect the performance of nine native and nine non-native ruderal species-the prevalent life-history strategy among non-natives-when grown alone and with a phytometer. We also conducted field samplings to estimate the abundance of the 18 species, and related feedbacks to abundances. We found that groups of native and non-native ruderals displayed similar frequencies of negative, positive, and neutral feedbacks, resulting in no detectable differences between natives and non-natives. Likewise, the phytometer exerted comparable negative impacts on native and non-native plants, which were unchanged by plant-soil feedbacks. Finally, feedbacks explained plant abundances only after removing one influential species which exhibited strong positive feedbacks but low abundance. Importantly, however, four out of five species with negative feedbacks were rare in the field. These findings suggest that soil feedbacks and plant-plant interactions do not confer an advantage to non-native over native species, but do contribute to the observed coexistence of these groups in the system. By comparing natives and non-natives with overlapping abundances and strategies, our work broadens understanding of the consequences of plant-soil feedbacks in plant invasion and, more generally, coexistence within plant communities.

  5. A field experiment demonstrating plant life-history evolution and its eco-evolutionary feedback to seed predator populations.

    PubMed

    Agrawal, Anurag A; Johnson, Marc T J; Hastings, Amy P; Maron, John L

    2013-05-01

    The extent to which evolutionary change occurs in a predictable manner under field conditions and how evolutionary changes feed back to influence ecological dynamics are fundamental, yet unresolved, questions. To address these issues, we established eight replicate populations of native common evening primrose (Oenothera biennis). Each population was planted with 18 genotypes in identical frequency. By tracking genotype frequencies with microsatellite DNA markers over the subsequent three years (up to three generations, ≈5,000 genotyped plants), we show rapid and consistent evolution of two heritable plant life-history traits (shorter life span and later flowering time). This rapid evolution was only partially the result of differential seed production; genotypic variation in seed germination also contributed to the observed evolutionary response. Since evening primrose genotypes exhibited heritable variation for resistance to insect herbivores, which was related to flowering time, we predicted that evolutionary changes in genotype frequencies would feed back to influence populations of a seed predator moth that specializes on O. biennis. By the conclusion of the experiment, variation in the genotypic composition among our eight replicate field populations was highly predictive of moth abundance. These results demonstrate how rapid evolution in field populations of a native plant can influence ecological interactions.

  6. [Feedback control mechanisms of plant cell expansion

    SciTech Connect

    Cosgrove, D.J.

    1992-01-01

    We have generated considerable evidence for the significance of wall stress relaxation in the control of plant growth and found that several agents (gibberellin, light, genetic loci for dwarf stature) influence growth rate via alteration of wall relaxation. We have refined our methods for measuring wall relaxation and, moreover, have found that wall relaxation properties bear only a distance relationship to wall mechanical properties. We have garnered novel insights into the nature of cell expansion mechanisms by analyzing spontaneous fluctuations of plant growth rate in seedlings. These experiments involved the application of mathematical techniques for analyzing growth rate fluctuations and the development of new instrumentation for measuring and forcing plant growth in a controlled fashion. These studies conclude that growth rate fluctuations generated by the plant as consequence of a feedback control system. This conclusion has important implications for the nature of wall loosening processes and demands a different framework for thinking about growth control. It also implies the existence of a growth rate sensor.

  7. Nonlinear plants, factorizations and stable feedback systems

    NASA Technical Reports Server (NTRS)

    Desoer, Charles A.; Kabuli, M. Guntekin

    1987-01-01

    For nonlinear plants represented by causal maps defined over extended spaces, right factorization and normalized right-coprime factorization concepts are discussed in terms of well-posed stable feedback systems. This setup covers continuous-time, discrete-time, time-invariant or time-varying input-output maps. The nonlinear maps are factored in terms of causal bounded-input bounded-output stable maps. In factored form, all instabilities of the original map are represented by the inverse of a causal stable `denominator' map. The existence of maps with right factorizations and normalized right-coprime factorizations is shown using a well-posed stable unity-feedback system. In the case where one of the subsystems has a normalized right-coprime factorization, the stability of the feedback system is equivalent to the stability of the pseudostate map.

  8. Negative plant-soil feedbacks increase with plant abundance, and are unchanged by competition.

    PubMed

    Maron, John L; Laney Smith, Alyssa; Ortega, Yvette K; Pearson, Dean E; Callaway, Ragan M

    2016-08-01

    Plant-soil feedbacks and interspecific competition are ubiquitous interactions that strongly influence the performance of plants. Yet few studies have examined whether the strength of these interactions corresponds with the abundance of plant species in the field, or whether feedbacks and competition interact in ways that either ameliorate or exacerbate their effects in isolation. We sampled soil from two intermountain grassland communities where we also measured the relative abundance of plant species. In greenhouse experiments, we quantified the direction and magnitude of plant-soil feedbacks for 10 target species that spanned a range of abundances in the field. In soil from both sites, plant-soil feedbacks were mostly negative, with more abundant species suffering greater negative feedbacks than rare species. In contrast, the average response to competition for each species was unrelated with its abundance in the field. We also determined how competitive response varied among our target species when plants competed in live vs. sterile soil. Interspecific competition reduced plant size, but the strength of this negative effect was unchanged by plant-soil feedbacks. Finally, when plants competed interspecifically, we asked how conspecific-trained, heterospecific-trained, and sterile soil influenced the competitive responses of our target species and how this varied depending on whether target species were abundant or rare in the field. Here, we found that both abundant and rare species were not as harmed by competition when they grew in heterospecific-trained soil compared to when they grew in conspecific-cultured soil. Abundant species were also not as harmed by competition when growing in sterile vs. conspecific-trained soil, but this was not the case for rare species. Our results suggest that abundant plants accrue species-specific soil pathogens to a greater extent than rare species. Thus, negative feedbacks may be critical for preventing abundant species from

  9. Feedback system design with an uncertain plant

    NASA Technical Reports Server (NTRS)

    Milich, D.; Valavani, L.; Athans, M.

    1986-01-01

    A method is developed to design a fixed-parameter compensator for a linear, time-invariant, SISO (single-input single-output) plant model characterized by significant structured, as well as unstructured, uncertainty. The controller minimizes the H(infinity) norm of the worst-case sensitivity function over the operating band and the resulting feedback system exhibits robust stability and robust performance. It is conjectured that such a robust nonadaptive control design technique can be used on-line in an adaptive control system.

  10. Feedback system design with an uncertain plant

    NASA Technical Reports Server (NTRS)

    Milich, D.; Valavani, L.; Athans, M.

    1986-01-01

    A method is developed to design a fixed-parameter compensator for a linear, time-invariant, SISO (single-output single-output) plant model characterized by significant structured, as well as unstructured, uncertainty. The controller minimizes the H(infinity) norm of the worst-case sensitivity function over the operating band and the resulting feedback system exhibits robust stability and robust performance. It is conjectured that such a robust nonadaptive control design technique can be used on-line in an adaptive control system.

  11. Negative plant soil feedback explaining ring formation in clonal plants.

    PubMed

    Cartenì, Fabrizio; Marasco, Addolorata; Bonanomi, Giuliano; Mazzoleni, Stefano; Rietkerk, Max; Giannino, Francesco

    2012-11-21

    Ring shaped patches of clonal plants have been reported in different environments, but the mechanisms underlying such pattern formation are still poorly explained. Water depletion in the inner tussocks zone has been proposed as a possible cause, although ring patterns have been also observed in ecosystems without limiting water conditions. In this work, a spatially explicit model is presented in order to investigate the role of negative plant-soil feedback as an additional explanation for ring formation. The model describes the dynamics of the plant biomass in the presence of toxicity produced by the decomposition of accumulated litter in the soil. Our model qualitatively reproduces the emergence of ring patterns of a single clonal plant species during colonisation of a bare substrate. The model admits two homogeneous stationary solutions representing bare soil and uniform vegetation cover which depend only on the ratio between the biomass death and growth rates. Moreover, differently from other plant spatial patterns models, but in agreement with real field observations of vegetation dynamics, we demonstrated that the pattern dynamics always lead to spatially homogeneous vegetation covers without creation of stable Turing patterns. Analytical results show that ring formation is a function of two main components, the plant specific susceptibility to toxic compounds released in the soil by the accumulated litter and the decay rate of these same compounds, depending on environmental conditions. These components act at the same time and their respective intensities can give rise to the different ring structures observed in nature, ranging from slight reductions of biomass in patch centres, to the appearance of marked rings with bare inner zones, as well as the occurrence of ephemeral waves of plant cover. Our results highlight the potential role of plant-soil negative feedback depending on decomposition processes for the development of transient vegetation patterns.

  12. Operating experience feedback program at Olkiluoto NPP

    SciTech Connect

    Kosonen, Mikko

    2002-07-01

    Recent review and development of the operating experience feedback program will be described. The development of the program has been based on several reviews by outside organizations. Main conclusions from these review reports and from the self assessment of safety performance, safety problems and safety culture on the basis of the operational events made by ASSET-method will be described. An approach to gather and analyze small events - so-called near misses - will be described. The operating experience program has been divided into internal and external operating experience. ASSET-methodology and a computer program assisting the analysis are used for the internal operating experience events. Noteworthy incidents occurred during outage are analyzed also by ASSET-method. Screening and pre analysis of the external operating experience relies on co-operation with ERFATOM, an organization of Nordic utilities for the exchange of nuclear industry experience. A short presentation on the performance of the Olkiluoto units will conclude the presentation. (author)

  13. Plant-soil feedbacks from 30-year family-specific soil cultures: phylogeny, soil chemistry and plant life stage

    PubMed Central

    Mehrabi, Zia; Bell, Thomas; Lewis, Owen T

    2015-01-01

    Intraspecific negative feedback effects, where performance is reduced on soils conditioned by conspecifics, are widely documented in plant communities. However, interspecific feedbacks are less well studied, and their direction, strength, causes, and consequences are poorly understood. If more closely related species share pathogens, or have similar soil resource requirements, plants may perform better on soils conditioned by more distant phylogenetic relatives. There have been few empirical tests of this prediction across plant life stages, and none of which attempt to account for soil chemistry. Here, we test the utility of phylogeny for predicting soil feedback effects on plant survival and performance (germination, seedling survival, growth rate, biomass). We implement a full factorial experiment growing species representing five families on five plant family-specific soil sources. Our experiments exploit soils that have been cultured for over 30 years in plant family-specific beds at Oxford University Botanic Gardens. Plant responses to soil source were idiosyncratic, and species did not perform better on soils cultured by phylogenetically more distant relatives. The magnitude and sign of feedback effects could, however, be explained by differences in the chemical properties of “home” and “away” soils. Furthermore, the direction of soil chemistry-related plant-soil feedbacks was dependent on plant life stage, with the effects of soil chemistry on germination success and accumulation of biomass inversely related. Our results (1) suggest that the phylogenetic distance between plant families cannot predict plant–soil feedbacks across multiple life stages, and (2) highlight the need to consider changes in soil chemistry as an important driver of population responses. The contrasting responses at plant life stages suggest that studies focusing on brief phases in plant demography (e.g., germination success) may not give a full picture of plant

  14. Temporal variation in plant-soil feedback controls succession.

    PubMed

    Kardol, Paul; Bezemer, T Martijn; van der Putten, Wim H

    2006-09-01

    Soil abiotic and biotic factors play key roles in plant community dynamics. However, little is known about how soil biota influence vegetation changes over time. Here, we show that the effects of soil organisms may depend on both the successional development of ecosystems and on the successional position of the plants involved. In model systems of plants and soils from different successional stages, we observed negative plant-soil feedback for early-successional plant species, neutral feedback for mid-successional species, and positive feedback for late-successional species. The negative feedback of early-successional plants was independent of soil origin, while late-successional plants performed best in late- and worst in early-successional soil. Increased performance of the subordinate, late-successional plants resulted in enhanced plant community diversity. Observed feedback effects were more related to soil biota than to abiotic conditions. Our results show that temporal variations in plant-soil interactions profoundly contribute to plant community assemblage and ecosystem development.

  15. A technology using feedback to manage experience based learning.

    PubMed

    Dornan, Tim; Brown, Martin; Powley, Dan; Hopkins, Mike

    2004-12-01

    The aim was to establish how ICT could apply feedback principles to experience based learning. Based on a survey of student and staff requirements, we developed a personalized educational technology ('iSUS') that: (1) Made students clear what they should learn; (2) Helped them meet appropriate real patients; (3) Encouraged reflective feedback; (4) Calculated benchmarks from accumulated feedback; (5) Compared individual students' feedback against those benchmarks; (6) Matched clinical activities to curriculum objectives; (7) Gave feedback to teachers and course leads. Bench testing proved the system usable. During seven weeks of real time use, a whole year group of 111 students feedback on 1183 learning episodes. Five hundred and forty-one (46%) of feedback episodes were self initiated. We have successfully prototyped an application of feedback principles to experience based learning that students seem to find useful.

  16. Feedbacks and the coevolution of plants and atmospheric CO2

    PubMed Central

    Beerling, David J.; Berner, Robert A.

    2005-01-01

    The coupled evolution of land plants, CO2, and climate over the last half billion years has maintained atmospheric CO2 concentrations within finite limits, indicating the involvement of a complex network of geophysiological feedbacks. But insight into this important regulatory network is extremely limited. Here we present a systems analysis of the physiological and geochemical processes involved, identifying new positive and negative feedbacks between plants and CO2 on geological time scales. Positive feedbacks accelerated falling CO2 concentrations during the evolution and diversification of terrestrial ecosystems in the Paleozoic and enhanced rising CO2 concentrations across the Triassic–Jurassic boundary during flood basalt eruptions. The existence of positive feedbacks reveals the unexpected destabilizing influence of the biota in climate regulation that led to environmental modifications accelerating rates of terrestrial plant and animal evolution in the Paleozoic. PMID:15668402

  17. Feedbacks and the coevolution of plants and atmospheric CO2.

    PubMed

    Beerling, David J; Berner, Robert A

    2005-02-01

    The coupled evolution of land plants, CO2, and climate over the last half billion years has maintained atmospheric CO2 concentrations within finite limits, indicating the involvement of a complex network of geophysiological feedbacks. But insight into this important regulatory network is extremely limited. Here we present a systems analysis of the physiological and geochemical processes involved, identifying new positive and negative feedbacks between plants and CO2 on geological time scales. Positive feedbacks accelerated falling CO2 concentrations during the evolution and diversification of terrestrial ecosystems in the Paleozoic and enhanced rising CO2 concentrations across the Triassic-Jurassic boundary during flood basalt eruptions. The existence of positive feedbacks reveals the unexpected destabilizing influence of the biota in climate regulation that led to environmental modifications accelerating rates of terrestrial plant and animal evolution in the Paleozoic.

  18. Plant-soil feedback: testing the generality with the same grasses in serpentine and prairie soils.

    PubMed

    Casper, Brenda B; Bentivenga, Stephen P; Ji, Baoming; Doherty, Jennifer H; Edenborn, Harry M; Gustafson, Danny J

    2008-08-01

    Plants can alter soil properties in ways that feed back to affect plant performance. The extent that plant-soil feedback affects co-occurring plant species differentially will determine its impact on plant community structure. Whether feedback operates consistently across similar plant communities is little studied. Here, the same grasses from two eastern U.S. serpentine grasslands and two midwestern tallgrass prairie remnants were examined for plant-soil feedback in parallel greenhouse experiments. Native soils were homogenized and cultured (trained) for a year with each of the four grasses. Feedback was evaluated by examining biomass variation in a second generation of (tester) plants grown in the trained soils. Biomass was lower in soils trained by conspecifics compared to soils trained by heterospecifics in seven of 15 possible cases; biomass was greater in conspecific soils in one other. Sorghastrum nutans exhibited lower biomass in conspecific soils for all four grasslands, so feedback may be characteristic of this species. Three cases from the Hayden prairie site were explained by trainer species having similar effects across all tester species so the relative performance of the different species was little affected; plants were generally larger in soils trained by Andropogon gerardii and smaller in soils trained by S. nutans. Differences among sites in the incidence of feedback were independent of serpentine or prairie soils. To explore the causes of the feedback, several soil factors were measured as a function of trainer species: nutrients and pH, arbuscular mycorrhizal (AM) spore communities, root colonization by AM fungi and putative pathogens, and functional diversity in bacterial communities as indicated by carbon substrate utilization. Only variation in nutrients was consistent with any patterns of feedback, and this could explain the greater biomass in soils trained by A. gerardii at Hayden. Feedback at Nottingham (one of the serpentine sites

  19. Plant-soil feedback: Testing the generality with the same grasses in serpentine and prairie soils

    SciTech Connect

    Casper, Brenda B.; Bentivenga, Stephen P.; Ji, Baoming; Doherty, Jennifer H.; Edenborn, Harry M.; Gustafson, Danny J.

    2008-08-01

    Plants can alter soil properties in ways that feed back to affect plant performance. The extent that plant-soil feedback affects co-occurring plant species differentially will determine its impact on plant community structure. Whether feedback operates consistently across similar plant communities is little studied. Here, the same grasses from two eastern U. S. serpentine grasslands and two midwestern tallgrass prairie remnants were examined for plant-soil feedback in parallel greenhouse experiments. Native soils were homogenized and cultured (trained) for a year with each of the four grasses. Feedback was evaluated by examining biomass variation in a second generation of (tester) plants grown in the trained soils. Biomass was lower in soils trained by conspecifics compared to soils trained by heterospecifics in seven of 15 possible cases; biomass was greater in conspecific soils in one other. Sorghastrum nutans exhibited lower biomass in conspecific soils for all four grasslands, so feedback may be characteristic of this species. Three cases from the Hayden prairie site were explained by trainer species having similar effects across all tester species so the relative performance of the different species was little affected; plants were generally larger in soils trained by Andropogon gerardii and smaller in soils trained by S. nutans. Differences among sites in the incidence of feedback were independent of serpentine or prairie soils. To explore the causes of the feedback, several soil factors were measured as a function of trainer species: nutrients and pH, arbuscular mycorrhizal (AM) spore communities, root colonization by AM fungi and putative pathogens, and functional diversity in bacterial communities as indicated by carbon substrate utilization. Only variation in nutrients was consistent with any patterns of feedback, and this could explain the greater biomass in soils trained by A. gerardii at Hayden. Feedback at Nottingham (one of the serpentine sites

  20. Spatial heterogeneity of plant-soil feedback affects root interactions and interspecific competition.

    PubMed

    Hendriks, Marloes; Ravenek, Janneke M; Smit-Tiekstra, Annemiek E; van der Paauw, Jan Willem; de Caluwe, Hannie; van der Putten, Wim H; de Kroon, Hans; Mommer, Liesje

    2015-08-01

    Plant-soil feedback is receiving increasing interest as a factor influencing plant competition and species coexistence in grasslands. However, we do not know how spatial distribution of plant-soil feedback affects plant below-ground interactions. We investigated the way in which spatial heterogeneity of soil biota affects competitive interactions in grassland plant species. We performed a pairwise competition experiment combined with heterogeneous distribution of soil biota using four grassland plant species and their soil biota. Patches were applied as quadrants of 'own' and 'foreign' soils from all plant species in all pairwise combinations. To evaluate interspecific root responses, species-specific root biomass was quantified using real-time PCR. All plant species suffered negative soil feedback, but strength was species-specific, reflected by a decrease in root growth in own compared with foreign soil. Reduction in root growth in own patches by the superior plant competitor provided opportunities for inferior competitors to increase root biomass in these patches. These patterns did not cascade into above-ground effects during our experiment. We show that root distributions can be determined by spatial heterogeneity of soil biota, affecting plant below-ground competitive interactions. Thus, spatial heterogeneity of soil biota may contribute to plant species coexistence in species-rich grasslands.

  1. Plant-soil feedback: testing the generality with the same grasses in serpentine and prairie soils

    SciTech Connect

    Casper, B.B.; Bentivenga, S.P.; Ji, Baoming; Doherty, J.H.; Edenborn, H.M.; Gustafson, D.J.

    2008-08-01

    Plants can alter soil properties in ways that feed back to affect plant performance. The extent that plant–soil feedback affects co-occurring plant species differentially will determine its impact on plant community structure. Whether feedback operates consistently across similar plant communities is little studied. Here, the same grasses from two eastern U.S. serpentine grasslands and two midwestern tallgrass prairie remnants were examined for plant–soil feedback in parallel greenhouse experiments. Native soils were homogenized and cultured (trained) for a year with each of the four grasses. Feedback was evaluated by examining biomass variation in a second generation of (tester) plants grown in the trained soils. Biomass was lower in soils trained by conspecifics compared to soils trained by heterospecifics in seven of 15 possible cases; biomass was greater in conspecific soils in one other. Sorghastrum nutans exhibited lower biomass in conspecific soils for all four grasslands, so feedback may be characteristic of this species. Three cases from the Hayden prairie site were explained by trainer species having similar effects across all tester species so the relative performance of the different species was little affected; plants were generally larger in soils trained by Andropogon gerardii and smaller in soils trained by S. nutans. Differences among sites in the incidence of feedback were independent of serpentine or prairie soils. To explore the causes of the feedback, several soil factors were measured as a function of trainer species: nutrients and pH, arbuscular mycorrhizal (AM) spore communities, root colonization by AM fungi and putative pathogens, and functional diversity in bacterial communities as indicated by carbon substrate utilization. Only variation in nutrients was consistent with any patterns of feedback, and this could explain the greater biomass in soils trained by A. gerardii at Hayden. Feedback at Nottingham (one of the serpentine sites

  2. Microbial population and community dynamics on plant roots and their feedbacks on plant communities.

    PubMed

    Bever, James D; Platt, Thomas G; Morton, Elise R

    2012-01-01

    The composition of the soil microbial community can be altered dramatically due to association with individual plant species, and these effects on the microbial community can have important feedbacks on plant ecology. Negative plant-soil feedback plays primary roles in maintaining plant community diversity, whereas positive plant-soil feedback may cause community conversion. Host-specific differentiation of the microbial community results from the trade-offs associated with overcoming plant defense and the specific benefits associated with plant rewards. Accumulation of host-specific pathogens likely generates negative feedback on the plant, while changes in the density of microbial mutualists likely generate positive feedback. However, the competitive dynamics among microbes depends on the multidimensional costs of virulence and mutualism, the fine-scale spatial structure within plant roots, and active plant allocation and localized defense. Because of this, incorporating a full view of microbial dynamics is essential to explaining the dynamics of plant-soil feedbacks and therefore plant community ecology.

  3. Negative plant-soil feedback predicts tree-species relative abundance in a tropical forest.

    PubMed

    Mangan, Scott A; Schnitzer, Stefan A; Herre, Edward A; Mack, Keenan M L; Valencia, Mariana C; Sanchez, Evelyn I; Bever, James D

    2010-08-05

    The accumulation of species-specific enemies around adults is hypothesized to maintain plant diversity by limiting the recruitment of conspecific seedlings relative to heterospecific seedlings. Although previous studies in forested ecosystems have documented patterns consistent with the process of negative feedback, these studies are unable to address which classes of enemies (for example, pathogens, invertebrates, mammals) exhibit species-specific effects strong enough to generate negative feedback, and whether negative feedback at the level of the individual tree is sufficient to influence community-wide forest composition. Here we use fully reciprocal shade-house and field experiments to test whether the performance of conspecific tree seedlings (relative to heterospecific seedlings) is reduced when grown in the presence of enemies associated with adult trees. Both experiments provide strong evidence for negative plant-soil feedback mediated by soil biota. In contrast, above-ground enemies (mammals, foliar herbivores and foliar pathogens) contributed little to negative feedback observed in the field. In both experiments, we found that tree species that showed stronger negative feedback were less common as adults in the forest community, indicating that susceptibility to soil biota may determine species relative abundance in these tropical forests. Finally, our simulation models confirm that the strength of local negative feedback that we measured is sufficient to produce the observed community-wide patterns in tree-species relative abundance. Our findings indicate that plant-soil feedback is an important mechanism that can maintain species diversity and explain patterns of tree-species relative abundance in tropical forests.

  4. Constructing wetlands: measuring and modeling feedbacks of oxidation processes between plants and clay-rich material

    NASA Astrophysics Data System (ADS)

    Saaltink, Rémon; Dekker, Stefan C.; Griffioen, Jasper; Wassen, Martin J.

    2016-04-01

    Interest is growing in using soft sediment as a building material in eco-engineering projects. Wetland construction in the Dutch lake Markermeer is an example: here the option of dredging some of the clay-rich lake-bed sediment and using it to construct 10.000 ha of wetland will soon go under construction. Natural processes will be utilized during and after construction to accelerate ecosystem development. Knowing that plants can eco-engineer their environment via positive or negative biogeochemical plant-soil feedbacks, we conducted a six-month greenhouse experiment to identify the key biogeochemical processes in the mud when Phragmites australis is used as an eco-engineering species. We applied inverse biogeochemical modeling to link observed changes in pore water composition to biogeochemical processes. Two months after transplantation we observed reduced plant growth and shriveling as well as yellowing of foliage. The N:P ratios of plant tissue were low and were affected not by hampered uptake of N but by enhanced uptake of P. Plant analyses revealed high Fe concentrations in the leaves and roots. Sulfate concentrations rose drastically in our experiment due to pyrite oxidation; as reduction of sulfate will decouple Fe-P in reducing conditions, we argue that plant-induced iron toxicity hampered plant growth, forming a negative feedback loop, while simultaneously there was a positive feedback loop, as iron toxicity promotes P mobilization as a result of reduced conditions through root death, thereby stimulating plant growth and regeneration. Given these two feedback mechanisms, we propose that when building wetlands from these mud deposits Fe-tolerant species are used rather than species that thrive in N-limited conditions. The results presented in this study demonstrate the importance of studying the biogeochemical properties of the building material and the feedback mechanisms between plant and soil prior to finalizing the design of the eco-engineering project.

  5. Scale-dependent feedbacks between patch size and plant reproduction in desert grassland

    USGS Publications Warehouse

    Svejcar, Lauren N.; Bestelmeyer, Brandon T.; Duniway, Michael C.; James, Darren K.

    2015-01-01

    Theoretical models suggest that scale-dependent feedbacks between plant reproductive success and plant patch size govern transitions from highly to sparsely vegetated states in drylands, yet there is scant empirical evidence for these mechanisms. Scale-dependent feedback models suggest that an optimal patch size exists for growth and reproduction of plants and that a threshold patch organization exists below which positive feedbacks between vegetation and resources can break down, leading to critical transitions. We examined the relationship between patch size and plant reproduction using an experiment in a Chihuahuan Desert grassland. We tested the hypothesis that reproductive effort and success of a dominant grass (Bouteloua eriopoda) would vary predictably with patch size. We found that focal plants in medium-sized patches featured higher rates of grass reproductive success than when plants occupied either large patch interiors or small patches. These patterns support the existence of scale-dependent feedbacks in Chihuahuan Desert grasslands and indicate an optimal patch size for reproductive effort and success in B. eriopoda. We discuss the implications of these results for detecting ecological thresholds in desert grasslands.

  6. The organization of plant communities: negative plant-soil feedbacks and semiarid grasslands

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Estimates of species losses and evidence of positive plant diversity-productivity relationships have spurred interest in understanding the mechanism(s) regulating species coexistence and relative abundance. Plant-soil biota feedbacks appear to affect plant diversity and community structure by eithe...

  7. Plant-soil feedback and the maintenance of diversity in Mediterranean-climate shrublands.

    PubMed

    Teste, François P; Kardol, Paul; Turner, Benjamin L; Wardle, David A; Zemunik, Graham; Renton, Michael; Laliberté, Etienne

    2017-01-13

    Soil biota influence plant performance through plant-soil feedback, but it is unclear whether the strength of such feedback depends on plant traits and whether plant-soil feedback drives local plant diversity. We grew 16 co-occurring plant species with contrasting nutrient-acquisition strategies from hyperdiverse Australian shrublands and exposed them to soil biota from under their own or other plant species. Plant responses to soil biota varied according to their nutrient-acquisition strategy, including positive feedback for ectomycorrhizal plants and negative feedback for nitrogen-fixing and nonmycorrhizal plants. Simulations revealed that such strategy-dependent feedback is sufficient to maintain the high taxonomic and functional diversity characterizing these Mediterranean-climate shrublands. Our study identifies nutrient-acquisition strategy as a key trait explaining how different plant responses to soil biota promote local plant diversity.

  8. Biogeomorphic feedback between plant growth and flooding causes alternative stable states in an experimental floodplain

    NASA Astrophysics Data System (ADS)

    Wang, Chen; Wang, Qiao; Meire, Dieter; Ma, Wandong; Wu, Chuanqing; Meng, Zhen; Van de Koppel, Johan; Troch, Peter; Verhoeven, Ronny; De Mulder, Tom; Temmerman, Stijn

    2016-07-01

    It is important to understand the mechanisms of vegetation establishment on bare substrate in a disturbance-driven ecosystem because of many valuable ecosystem services. This study tested for empirical indications of local alternative stable states controlled by biogeomorphic feedbacks using flume experiments with alfalfa: (1) single flood experiments different in flood intensity and plant growth, (2) long-term evolution experiments with repeated flooding and seeding. We observed: (1) a combination of thresholds in plant growth and flooding magnitude for upgrowing seedlings to survive; (2) bimodality in vegetation biomass after floods indicating the existence of two alternative states, either densely vegetated or bare; (3) facilitation of vegetation establishment by the spatial pattern formation of channels and sand bars. In conclusion, empirical indicators were demonstrated for local alternative stable states in a disturbance-driven ecosystem associated with biogeomorphic feedbacks, which could contribute to the protection and restoration of vegetation in such ecosystems.

  9. An affinity-effect relationship for microbial communities in plant-soil feedback loops

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Plant-soil feedback involving soil microorganisms can regulate plant populations. To participate in plant-soil feedback, microorganisms must display an affinity for plant species, and they must produce consistent effects on plant growth. We tested the validity and strength of microbial affinity-effe...

  10. How Does Facial Feedback Modulate Emotional Experience?

    PubMed Central

    Davis, Joshua Ian; Senghas, Ann; Ochsner, Kevin N.

    2009-01-01

    Contracting muscles involved in facial expressions (e.g. smiling or frowning) can make emotions more intense, even when unaware one is modifying expression (e.g. Strack, Martin, & Stepper, 1988). However, it is unresolved whether and how inhibiting facial expressions might weaken emotional experience. In the present study, 142 participants watched positive and negative video clips while either inhibiting their facial expressions or not. When hypothesis awareness and effects of distraction were experimentally controlled, inhibiting facial expressions weakened some emotional experiences. These findings provide new insight into ways that inhibition of facial expression can affect emotional experience: the link is not dependent on experimental demand, lay theories about connections between expression and experience, or the distraction involved in inhibiting one’s expressions. PMID:20160935

  11. Negative plant-soil feedbacks may limit persistence of an invasive tree due to rapid accumulation of soil pathogens.

    PubMed

    Nijjer, Somereet; Rogers, William E; Siemann, Evan

    2007-10-22

    Soil organisms influence plant species coexistence and invasion potential. Plant-soil feedbacks occur when plants change soil community composition such that interactions with that soil community in turn may positively or negatively affect the performance of conspecifics. Theories predict and studies show that invasions may be promoted by stronger negative soil feedbacks for native compared with exotic species. We present a counter-example of a successful invader with strong negative soil feedbacks apparently caused by host-specific, pathogenic soil fungi. Using a feedback experiment in pots, we investigated whether the relative strength of plant-soil feedbacks experienced by a non-native woody invader, Sapium sebiferum, differed from several native tree species by examining their performance in soils collected near conspecifics ('home soils') or heterospecifics ('away soils') in the introduced range. Sapium seedlings, but no native seedlings, had lower survival and biomass in its home soils compared with soils of other species (negative feedback'). To investigate biotic agents potentially responsible for the observed negative feedbacks, we conducted two additional experiments designed to eliminate different soil taxa ('rescue experiments'). We found that soil sterilization (pot experiment ) or soil fungicide applications (pot and field experiments) restored Sapium performance in home soil thereby eliminating the negative feedbacks we observed in the original experiment. Such negative feedbacks apparently mediated by soil fungi could have important effects on persistence of this invader by limiting Sapium seedling success in Sapium dominated forests (home soils) though their weak effects in heterospecific (away) soils suggest a weak role in limiting initial establishment.

  12. French Atomic Energy Commission Decommissioning Programme and Feedback Experience - 12230

    SciTech Connect

    Guiberteau, Ph.; Nokhamzon, J.G.

    2012-07-01

    Since the French Atomic and Alternatives Energy Commission (CEA) was founded in 1945 to carry out research programmes on use of nuclear, and its application France has set up and run various types of installations: research or prototypes reactors, process study or examination laboratories, pilot installations, accelerators, nuclear power plants and processing facilities. Some of these are currently being dismantled or must be dismantled soon so that the DEN, the Nuclear Energy Division, can construct new equipment and thus have available a range of R and D facilities in line with the issues of the nuclear industry of the future. Since the 1960's and 1970's in all its centres, the CEA has acquired experience and know-how through dismantling various nuclear facilities. The dismantling techniques are nowadays operational, even if sometimes certain specific developments are necessary to reduce the cost of operations. Thanks to availability of techniques and guarantees of dismantling programme financing now from two dedicated funds, close to euro 15,000 M for the next thirty years, for current or projected dismantling operations, the CEA's Nuclear Energy Division has been able to develop, when necessary, its immediate dismantling strategy. Currently, nearly thirty facilities are being dismantled by the CEA's Nuclear Energy Division operational units with industrial partners. Thus the next decade will see completion of the dismantling and radioactive clean-up of the Grenoble site and of the facilities on the Fontenay-aux-Roses site. By 2016, the dismantling of the UP1 plant at Marcoule, the largest dismantling work in France, will be well advanced, with all the process equipment dismantled. After an overview of the French regulatory framework, the paper will describe the DD and R (Decontamination Decommissioning and Remediation) strategy, programme and feedback experience inside the CEA's Nuclear Energy Division. A special feature of dismantling operations at the CEA

  13. Intraspecific plant-soil feedback and intraspecific overyielding in Arabidopsis thaliana.

    PubMed

    Bukowski, Alexandra R; Petermann, Jana S

    2014-06-01

    Understanding the mechanisms of community coexistence and ecosystem functioning may help to counteract the current biodiversity loss and its potentially harmful consequences. In recent years, plant-soil feedback that can, for example, be caused by below-ground microorganisms has been suggested to play a role in maintaining plant coexistence and to be a potential driver of the positive relationship between plant diversity and ecosystem functioning. Most of the studies addressing these topics have focused on the species level. However, in addition to interspecific interactions, intraspecific interactions might be important for the structure of natural communities. Here, we examine intraspecific coexistence and intraspecific diversity effects using 10 natural accessions of the model species Arabidopsis thaliana (L.) Heynh. We assessed morphological intraspecific diversity by measuring several above- and below-ground traits. We performed a plant-soil feedback experiment that was based on these trait differences between the accessions in order to determine whether A. thaliana experiences feedback at intraspecific level as a result of trait differences. We also experimentally tested the diversity-productivity relationship at intraspecific level. We found strong differences in above- and below-ground traits between the A. thaliana accessions. Overall, plant-soil feedback occurred at intraspecific level. However, accessions differed in the direction and strength of this feedback: Some accessions grew better on their own soils, some on soils from other accessions. Furthermore, we found positive diversity effects within A. thaliana: Accession mixtures produced a higher total above-ground biomass than accession monocultures. Differences between accessions in their feedback response could not be explained by morphological traits. Therefore, we suggest that they might have been caused by accession-specific accumulated soil communities, by root exudates, or by accession

  14. A Study of Adaptive Relevance Feedback - UIUC TREC-2008 Relevance Feedback Experiments

    DTIC Science & Technology

    2008-11-01

    1− β)αf + βαd where if αd < αf , β = 1; otherwise β = 0. 5. EXPERIMENT RESULTS 5.1 Data Preprocessing We employ the Lemur toolkit (version 4.5) and... Lemur toolkit, we adopt the KL-Divergence retrieval model with mixture model feedback to do relevance feed- back experiments (related parameters are

  15. Undergraduate Student Responses to Feedback: Expectations and Experiences

    ERIC Educational Resources Information Center

    Small, Felicity; Attree, Kath

    2016-01-01

    This research is a qualitative exploration of first and second year university students' experiences of feedback, specifically focused on their expectations and feelings. The data (n = 46) were collected from internal and distance-learning students in their first or second year, who are of lower socio-economic status and first in family to attend.…

  16. Modelling Plant and Soil Nitrogen Feedbacks Affecting Forest Carbon Gain at High CO2

    NASA Astrophysics Data System (ADS)

    McMurtrie, R. E.; Norby, R. J.; Franklin, O.; Pepper, D. A.

    2007-12-01

    Short-term, direct effects of elevated atmospheric CO2 concentrations on plant carbon gain are relatively well understood. There is considerable uncertainty, however, about longer-term effects, which are influenced by various plant and ecosystem feedbacks. A key feedback in terrestrial ecosystems occurs through changes in plant carbon (C) allocation patterns. For instance, if high CO2 were to increase C allocation to roots, then plants may experience positive feedback through improved plant nutrition. A second type of feedback, associated with decomposition of soil-organic matter, may reduce soil-nutrient availability at high CO2. This paper will consider mechanistic models of both feedbacks. Effects of high CO2 on plant C allocation will be investigated using a simple model of forest net primary production (NPP) that incorporates the primary mechanisms of plant carbon and nitrogen (N) balance. The model called MATE (Model Any Terrestrial Ecosystem) includes an equation for annual C balance that depends on light- saturated photosynthetic rate and therefore on [CO2], and an equation for N balance incorporating an expression for N uptake as a function of root mass. The C-N model is applied to a Free Air CO2 Exchange (FACE) experiment at Oak Ridge National Laboratory (ORNL) in Tennessee, USA, where closed-canopy, monoculture stands of the deciduous hardwood sweetgum ( Liquidambar styraciflua) have been growing at [CO2] of 375 and 550 ppm for ten years. Features of this experiment are that the annual NPP response to elevated CO2 has averaged approximately 25% over seven years, but that annual fine-root production has almost doubled on average, with especially large increases in later years of the experiment (Norby et al. 2006). The model provides a simple graphical approach for analysing effects of elevated CO2 and N supply on leaf/root/wood C allocation and productivity. It simulates increases in NPP and fine-root production at the ORNL FACE site that are consistent

  17. Observations on the balance between abiotic and biotic factors in plant-morphodynamic feedbacks (Invited)

    NASA Astrophysics Data System (ADS)

    Manners, R.; Lightbody, A.; Wilcox, A. C.; Sklar, L. S.; Stella, J. C.; Kui, L.

    2013-12-01

    The strength and direction of feedbacks between riparian vegetation and fluvial processes depend on the balance between abiotic (i.e., sediment supply, transport capacity) and biotic factors (i.e., plant morphology, stem density). We present results from flume experiments that test the influence of these factors on plant-morphodynamic feedbacks. For equilibrium (balance between sediment transport and supply) and supply-limited (transport exceeds sediment supply) conditions, we evaluated the impact of plant morphology (shrubby versus characteristically single-stemmed woody seedlings), height (10 to 120 cm), and configuration (individual and patches) on bed topography, velocity fields, and sediment flux. We conducted the experiments in a 28-meter long, sand-bedded flume (60 cm wide and 71 cm deep) at the UC-Berkeley Richmond Field Station, into which plants harvested from field sites were transplanted in a manner that maintained the root structure. Under equilibrium conditions, all sizes of the individual shrubby plants induced scour around the base of the plant and increased deposition downstream. Individual single-stemmed plants, however, did not greatly alter the flow and sediment transport field (when compared to baseline conditions). When transport capacity exceeded the supply of sediment, the impact of all plants diminished, and bed scour would lead to plant dislodgement. More rapid dislodgement for the shrubby species occurred as a result of the increased drag on the plant. Our results illustrate that the morphology of shrubby plants, with multiple stems and greater near-bed frontal area (compared to the single-stem plant), not only increases the influence of the plant on the flow and sediment transport fields but also may, under certain sediment supply conditions, contribute to its own mortality via scour. The results from these experiments highlight the importance of both abiotic and biotic conditions, and the balance between them, in determining the

  18. Plant-soil feedbacks promote negative frequency dependence in the coexistence of two aridland grasses.

    PubMed

    Chung, Y Anny; Rudgers, Jennifer A

    2016-07-27

    Understanding the mechanisms of species coexistence is key to predicting patterns of species diversity. Historically, the ecological paradigm has been that species coexist by partitioning resources: as a species increases in abundance, self-limitation kicks in, because species-specific resources decline. However, determining coexistence mechanisms has been a particular puzzle for sedentary organisms with high overlap in their resource requirements, such as plants. Recent evidence suggests that plant-associated microbes could generate the stabilizing self-limitation (negative frequency dependence) that is required for species coexistence. Here, we test the key assumption that plant-microbe feedbacks cause such self-limitation. We used competition experiments and modelling to evaluate how two common groups of soil microbes (rhizospheric microbes and biological soil crusts) influenced the self-limitation of two competing desert grass species. Negative feedbacks between the dominant plant competitor and its rhizospheric microbes magnified self-limitation, whereas beneficial interactions between both plant species and biological soil crusts partly counteracted this stabilizing effect. Plant-microbe interactions have received relatively little attention as drivers of vegetation dynamics in dry land ecosystems. Our results suggest that microbial mechanisms can contribute to patterns of plant coexistence in arid grasslands.

  19. Mycorrhizal symbioses drive temperate forest population dynamics through plant-soil feedbacks

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Feedback with soil biota is a major driver of diversity within terrestrial plant communities. However, little is known about the factors regulating plant-soil feedback, which can vary from positive to negative among plant species. In a large-scale observational and experimental study involving 55 sp...

  20. Delayed feedback control experiments on some flexible structures

    NASA Astrophysics Data System (ADS)

    Cai, Guo-Ping; Chen, Long-Xiang

    2010-12-01

    In recent decades, studies on delayed system dynamics have attracted increasing attention and advances have been achieved in stability, nonlinearity, delay identification, delay elimination and application. However, most of the existing work is on the theoretical basis and little is on the experiment. This paper presents our experimental studies on delayed feedback control conducted in recent years with the focus on the discussion of a DSP-based delayed experiment system. Some phenomena in our delay experiments are discussed and a few topics of interest for further research are brought forward.

  1. Lessons learnt from evaluating full-scale ammonium feedback control in three large wastewater treatment plants.

    PubMed

    Åmand, L; Laurell, C; Stark-Fujii, K; Thunberg, A; Carlsson, B

    2014-01-01

    Three large wastewater treatment plants in Sweden participate in a project evaluating different types of ammonium feedback controllers in full-scale operation. The goal is to improve process monitoring, maintain effluent water quality and save energy. The paper presents the outcome of the long-term evaluation of controllers. Based on the experiences gained from the full-scale implementations, a discussion is provided about energy assessment for the purpose of comparing control strategies. The most important conclusions are the importance of long-term experiments and the difficulty of comparing energy consumption based on air flow rate measurements.

  2. Competition and soil resource environment alter plant-soil feedbacks for native and exotic grasses.

    PubMed

    Larios, Loralee; Suding, Katharine N

    2014-11-24

    Feedbacks between plants and soil biota are increasingly identified as key determinants of species abundance patterns within plant communities. However, our understanding of how plant-soil feedbacks (PSFs) may contribute to invasions is limited by our understanding of how feedbacks may shift in the light of other ecological processes. Here we assess how the strength of PSFs may shift as soil microbial communities change along a gradient of soil nitrogen (N) availability and how these dynamics may be further altered by the presence of a competitor. We conducted a greenhouse experiment where we grew native Stipa pulchra and exotic Avena fatua, alone and in competition, in soils inoculated with conspecific and heterospecific soil microbial communities conditioned in low, ambient and high N environments. Stipa pulchra decreased in heterospecific soil and in the presence of a competitor, while the performance of the exotic A. fatua shifted with soil microbial communities from altered N environments. Moreover, competition and soil microbial communities from the high N environment eliminated the positive PSFs of Stipa. Our results highlight the importance of examining how individual PSFs may interact in a broader community context and contribute to the establishment, spread and dominance of invaders.

  3. Positive feedback between mycorrhizal fungi and plants influences plant invasion success and resistance to invasion.

    PubMed

    Zhang, Qian; Yang, Ruyi; Tang, Jianjun; Yang, Haishui; Hu, Shuijin; Chen, Xin

    2010-08-24

    Negative or positive feedback between arbuscular mycorrhizal fungi (AMF) and host plants can contribute to plant species interactions, but how this feedback affects plant invasion or resistance to invasion is not well known. Here we tested how alterations in AMF community induced by an invasive plant species generate feedback to the invasive plant itself and affect subsequent interactions between the invasive species and its native neighbors. We first examined the effects of the invasive forb Solidago canadensis L. on AMF communities comprising five different AMF species. We then examined the effects of the altered AMF community on mutualisms formed with the native legume forb species Kummerowia striata (Thunb.) Schindl. and on the interaction between the invasive and native plants. The host preferences of the five AMF were also assessed to test whether the AMF form preferred mutualistic relations with the invasive and/or the native species. We found that S. canadensis altered AMF spore composition by increasing one AMF species (Glomus geosporum) while reducing Glomus mosseae, which is the dominant species in the field. The host preference test showed that S. canadensis had promoted the abundance of AMF species (G. geosporum) that most promoted its own growth. As a consequence, the altered AMF community enhanced the competitiveness of invasive S. canadensis at the expense of K. striata. Our results demonstrate that the invasive S. canadensis alters soil AMF community composition because of fungal-host preference. This change in the composition of the AMF community generates positive feedback to the invasive S. canadensis itself and decreases AM associations with native K. striata, thereby making the native K. striata less dominant.

  4. Remote sensing of plant trait responses to field-based plant-soil feedback using UAV-based optical sensors

    NASA Astrophysics Data System (ADS)

    van der Meij, Bob; Kooistra, Lammert; Suomalainen, Juha; Barel, Janna M.; De Deyn, Gerlinde B.

    2017-02-01

    Plant responses to biotic and abiotic legacies left in soil by preceding plants is known as plant-soil feedback (PSF). PSF is an important mechanism to explain plant community dynamics and plant performance in natural and agricultural systems. However, most PSF studies are short-term and small-scale due to practical constraints for field-scale quantification of PSF effects, yet field experiments are warranted to assess actual PSF effects under less controlled conditions. Here we used unmanned aerial vehicle (UAV)-based optical sensors to test whether PSF effects on plant traits can be quantified remotely. We established a randomized agro-ecological field experiment in which six different cover crop species and species combinations from three different plant families (Poaceae, Fabaceae, Brassicaceae) were grown. The feedback effects on plant traits were tested in oat (Avena sativa) by quantifying the cover crop legacy effects on key plant traits: height, fresh biomass, nitrogen content, and leaf chlorophyll content. Prior to destructive sampling, hyperspectral data were acquired and used for calibration and independent validation of regression models to retrieve plant traits from optical data. Subsequently, for each trait the model with highest precision and accuracy was selected. We used the hyperspectral analyses to predict the directly measured plant height (RMSE = 5.12 cm, R2 = 0.79), chlorophyll content (RMSE = 0.11 g m-2, R2 = 0.80), N-content (RMSE = 1.94 g m-2, R2 = 0.68), and fresh biomass (RMSE = 0.72 kg m-2, R2 = 0.56). Overall the PSF effects of the different cover crop treatments based on the remote sensing data matched the results based on in situ measurements. The average oat canopy was tallest and its leaf chlorophyll content highest in response to legacy of Vicia sativa monocultures (100 cm, 0.95 g m-2, respectively) and in mixture with Raphanus sativus (100 cm, 1.09 g m-2, respectively), while the lowest values (76 cm, 0.41 g m-2, respectively

  5. Scale-dependent feedbacks between patch size and plant reproduction in desert grassland

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Theoretical models suggest that scale-dependent feedbacks between plant reproductive success and plant patch size govern transitions from highly to sparsely vegetated states in drylands, yet there is scant empirical evidence for these mechanisms. Scale-dependent feedback models suggest that an optim...

  6. Experiments evaluating compliance and force feedback effect on manipulator performance

    NASA Technical Reports Server (NTRS)

    Kugath, D. A.

    1972-01-01

    The performance capability was assessed of operators performing simulated space tasks using manipulator systems which had compliance and force feedback varied. Two manipulators were used, the E-2 electromechanical man-equivalent (force, reach, etc.) master-slave system and a modified CAM 1400 hydraulic master-slave with 100 lbs force capability at reaches of 24 ft. The CAM 1400 was further modified to operate without its normal force feedback. Several experiments and simulations were performed. The first two involved the E-2 absorbing the energy of a moving mass and secondly, guiding a mass thru a maze. Thus, both work and self paced tasks were studied as servo compliance was varied. Three simulations were run with the E-2 mounted on the CAM 1400 to evaluate the concept of a dexterous manipulator as an end effector of a boom-manipulator. Finally, the CAM 1400 performed a maze test and also simulated the capture of a large mass as the servo compliance was varied and with force feedback included and removed.

  7. Wetland eco-engineering: measuring and modeling feedbacks of oxidation processes between plants and clay-rich material

    NASA Astrophysics Data System (ADS)

    Saaltink, Rémon; Dekker, Stefan C.; Griffioen, Jasper; Wassen, Martin J.

    2016-09-01

    Interest is growing in using soft sediment as a foundation in eco-engineering projects. Wetland construction in the Dutch lake Markermeer is an example: here, dredging some of the clay-rich lake-bed sediment and using it to construct wetland will soon begin. Natural processes will be utilized during and after construction to accelerate ecosystem development. Knowing that plants can eco-engineer their environment via positive or negative biogeochemical plant-soil feedbacks, we conducted a 6-month greenhouse experiment to identify the key biogeochemical processes in the mud when Phragmites australis is used as an eco-engineering species. We applied inverse biogeochemical modeling to link observed changes in pore water composition to biogeochemical processes. Two months after transplantation we observed reduced plant growth and shriveling and yellowing of foliage. The N : P ratios of the plant tissue were low, and these were affected not by hampered uptake of N but by enhanced uptake of P. Subsequent analyses revealed high Fe concentrations in the leaves and roots. Sulfate concentrations rose drastically in our experiment due to pyrite oxidation; as reduction of sulfate will decouple Fe-P in reducing conditions, we argue that plant-induced iron toxicity hampered plant growth, forming a negative feedback loop, while simultaneously there was a positive feedback loop, as iron toxicity promotes P mobilization as a result of reduced conditions through root death, thereby stimulating plant growth and regeneration. Given these two feedback mechanisms, we propose the use of Fe-tolerant species rather than species that thrive in N-limited conditions. The results presented in this study demonstrate the importance of studying the biogeochemical properties of the situated sediment and the feedback mechanisms between plant and soil prior to finalizing the design of the eco-engineering project.

  8. Plant Development and Genetics Experiment

    NASA Technical Reports Server (NTRS)

    2003-01-01

    Aboard the International Space Station (ISS), the Russian Lada greenhouse provides home to an experiment that investigates plant development and genetics. Space grown peas have dried and 'gone to seed.' The crew of the ISS will soon harvest the seeds. Eventually some will be replanted onboard the ISS, and some will be returned to Earth for further study.

  9. Exploring Occupational Therapy Students' Meaning of Feedback during Fieldwork Experiences

    ERIC Educational Resources Information Center

    Rathgeber, Karen Lynne

    2014-01-01

    Researchers have revealed that students' confidence and performance improve after they receive feedback from clinical supervisors regarding the delivery of quality patient care. Multiple studies of feedback have focused on the provision and acceptance of feedback; however, it was not known if or how students internalized feedback to promote…

  10. Conducting plant experiments in space.

    PubMed

    Kiss, John Z

    2015-01-01

    The growth and development of plants during spaceflight have important implications for both basic and applied research supported by NASA and other international space agencies. While there have been many reviews of plant space biology, the present chapter attempts to fill a gap in the literature on the actual process and methods of performing plant research in the spaceflight environment. The author has been a principal investigator on six spaceflight projects and has another two space experiments in development. These experiences include using the US Space Shuttle, the former Russian space station Mir, and the International Space Station, utilizing the Space Shuttle and Space X as launch vehicles. While there are several ways to obtain a spaceflight opportunity, this review focuses on using the NASA peer-reviewed sciences approach to get an experiment manifested for flight. Three narratives for the implementation of plant space biology experiments are considered from rapid turnaround of a few months to a project with new hardware development that lasted 6 years. The many challenges of spaceflight research include logistical and resource constraints such as crew time, power, cold stowage, and data downlinks, among others. Additional issues considered are working at NASA centers, hardware development, safety concerns, and the engineering versus science culture in space agencies. The difficulties of publishing the results from spaceflight research based on such factors as the lack of controls, limited sample size, and the indirect effects of the spaceflight environment also are summarized. Finally, lessons learned from these spaceflight experiences are discussed in the context of improvements for future space-based research projects with plants.

  11. Invasive grasses consistently create similar plant-soil feedback types in soils collected from geographically distant locations

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Invasive PSF is limited by soil type. Most, but not all, plant species exhibit negative plant soil feedback (PSF), wherein plants perform poorly in soils formerly occupied (conditioned) by conspecifics. This dynamic has led to the Plant-Soil Feedback Hypothesis of Invasion which posits that plant sp...

  12. Investigating Expectations and Experiences of Audio and Written Assignment Feedback in First-Year Undergraduate Students

    ERIC Educational Resources Information Center

    Fawcett, Hannah; Oldfield, Jeremy

    2016-01-01

    Previous research suggests that audio feedback may be an important mechanism for facilitating effective and timely assignment feedback. The present study examined expectations and experiences of audio and written feedback provided through "turnitin for iPad®" from students within the same cohort and assignment. The results showed that…

  13. Interactions between plant traits and sediment characteristics influencing species establishment and scale-dependent feedbacks in salt marsh ecosystems

    NASA Astrophysics Data System (ADS)

    Schwarz, C.; Bouma, T. J.; Zhang, L. Q.; Temmerman, S.; Ysebaert, T.; Herman, P. M. J.

    2015-12-01

    The importance of ecosystem engineering and biogeomorphic processes in shaping many aquatic and semi-aquatic landscapes is increasingly acknowledged. Ecosystem engineering and biogeomorphic landscape formation involves two critical processes: (1) species establishment, and (2) scale-dependent feedbacks, meaning that organisms improve their living conditions on a local scale but at the same time worsen them at larger scales. However, the influence of organism traits in combination with physical factors (e.g. hydrodynamics, sediments) on early establishment and successive development due to scale-dependent feedbacks is still unclear. As a model system, this was tested for salt marsh pioneer plants by conducting flume experiments: i) on the influence of species-specific traits (such as stiffness) of two contrasting dominant pioneer species (Spartina alterniflora and Scirpus mariqueter) to withstand current-induced stress during establishment; and ii) to study the impact of species-specific traits (stiffness) and physical forcing (water level, current stress) on the large-scale negative feedback at established tussocks (induced scour at tussock edges) of the two model species. The results indicate that, not only do species-specific plant traits, such as stiffness, exert a major control on species establishment thresholds, but also potentially physiologically triggered plant properties, such as adapted root morphology due to sediment properties. Moreover, the results show a clear relation between species-specific plant traits, abiotics (i.e. sediment, currents) and the magnitude of the large-scale negative scale-dependent feedback. These findings suggest that the ecosystem engineering ability, resulting from physical plant properties can be disadvantageous for plant survival through promoted dislodgement (stem stiffness increases the amount of drag experienced at the root system), underlying the importance of scale-dependent feedbacks on landscape development.

  14. The role of plant-soil feedbacks and land-use legacies in restoration of a temperate steppe in northern China

    SciTech Connect

    Jiang, Lili; Han, Xingguo; Zhang, Guangming; Kardol, Paul

    2010-11-01

    Plant soil feedbacks affect plant performance and plant community dynamics; however, little is known about their role in ecological restoration. Here, we studied plant soil feedbacks in restoration of steppe vegetation after agricultural disturbance in northern China. First, we analyzed abiotic and biotic soil properties under mono-dominant plant patches in an old-field restoration site and in a target steppe site. Second, we tested plant soil feedbacks by growing plant species from these two sites on soils from con- and heterospecific origin. Soil properties generally did not differ between the old-field site and steppe site, but there were significant differences among mono-dominant plant patches within the sites. While soil species origin (i.e., the plant species beneath which the soil was collected) affected biomass of individual plant species in the feedback experiment, species-level plant soil feedbacks were neutral . Soil site origin (old-field, steppe) significantly affected biomass of old-field and steppe species. For example, old-field species had higher biomass in old-field soils than in steppe soils, indicating a positive land-use legacy. However, soil site origin effects depended on the plant species beneath which the soils were collected. The predictive value of abiotic and biotic soil properties in explaining plant biomass differed between and within groups of old-field and steppe species. We conclude that the occurrence of positive land-use legacies for old-field species may retard successional replacement of old-field species by steppe species. However, high levels of idiosyncrasy in responses of old-field and steppe plant species to con- and heterospecific soils indicate interspecific variation in the extent to which soil legacies and plant soil feedbacks control successional species replacements in Chinese steppe ecosystems.

  15. [Feedback control mechanisms of plant cell expansion]. Progress report, [June 1989--June 1992

    SciTech Connect

    Cosgrove, D.J.

    1992-12-31

    We have generated considerable evidence for the significance of wall stress relaxation in the control of plant growth and found that several agents (gibberellin, light, genetic loci for dwarf stature) influence growth rate via alteration of wall relaxation. We have refined our methods for measuring wall relaxation and, moreover, have found that wall relaxation properties bear only a distance relationship to wall mechanical properties. We have garnered novel insights into the nature of cell expansion mechanisms by analyzing spontaneous fluctuations of plant growth rate in seedlings. These experiments involved the application of mathematical techniques for analyzing growth rate fluctuations and the development of new instrumentation for measuring and forcing plant growth in a controlled fashion. These studies conclude that growth rate fluctuations generated by the plant as consequence of a feedback control system. This conclusion has important implications for the nature of wall loosening processes and demands a different framework for thinking about growth control. It also implies the existence of a growth rate sensor.

  16. The Effects of Field Experience on Delivery of Feedback

    ERIC Educational Resources Information Center

    Ramos, Adolfo R.; Esslinger, Kerry; Pyle, Elizabeth

    2015-01-01

    The purpose of this study was to examine pre-service teachers' (PTs) ability to deliver feedback, which has been used as a process variable in identifying teacher-effectiveness and an established NASPE standard for beginning teachers. These questions guided the study: 1. Will overall feedback interactions delivered by PTs reach 45 per video? 2.…

  17. Plant feedbacks on soil respiration in a poplar plantation under elevated CO2 and nitrogen fertilization

    NASA Astrophysics Data System (ADS)

    Lagomarsino, Alessandra; Lukac, Martin; Godbold, Douglas L.; Marinari, Sara; de Angelis, Paolo

    2010-05-01

    FACE experiments offered a unique occasion to investigate plant-soil relationship in terrestrial ecosystems. Changes in plant productivity and carbon (C) allocation under elevated CO2 have the potential to alter soil processes mediated by microorganisms. Also, fertilization can strongly affect plant-soil relationships through both direct and indirect effects. A fast growing poplar plantation was treated for six consecutive years with elevated CO2 at two nitrogen (N) levels. In the frame of plant responses to these environmental factors, our intent is to investigate plant-soil relationships and their impact on soil CO2 emissions. In particular, feedbacks of root productivity on soil respiration and heterotrophic community have been assessed in the last two years of the field experiment. In the POP-EUROFACE fast growing poplar plantation, the enhancement of atmospheric CO2 concentration induced an increase of fine root biomass and productivity, and consequently rhizodeposition. Concurrently, N addition reduced total root biomass but did not affect productivity. Soil respiration was deeply impacted by elevated CO2, with increases up to 95%, independent of N availability. The increase involved both auto and rhizomicrobial components of soil respiration. Indeed, the root-rhizosphere continuum stimulated the rhizomicrobial respiration, with the prompt loss of part of the extra C fixed through photosynthesis in elevated CO2. In fact, whereas the basal soil respiration was significantly dependent on fine root standing biomass, total soil respiration and the rhizomicrobial component during the growing season were significantly dependent on fine root productivity. This mechanism was also evident in the year following the end of CO2 enrichment, when no "residual" effects of elevated CO2 on soil respiration were observed, in unfertilized soil. The relationship between root productivity and heterotrophic respiration was mediated by the pattern of labile C availability in soil

  18. Nematicide impacts on nematodes and feedbacks on plant productivity in a plant diversity gradient

    NASA Astrophysics Data System (ADS)

    Eisenhauer, Nico; Ackermann, Michael; Gass, Svenja; Klier, Matthias; Migunova, Varvara; Nitschke, Norma; Ruess, Liliane; Sabais, Alexander C. W.; Weisser, Wolfgang W.; Scheu, Stefan

    2010-09-01

    A major issue in current ecological research is the effect of biodiversity on ecosystem functioning. Although several studies reported a positive diversity - productivity relationship, the role of soil animals has been largely neglected. Nematodes are among the most widespread and important herbivores causing substantial yield losses in agriculture; however, impacts of nematodes on the diversity - productivity relationship in semi-natural plant communities have not been investigated until today. In the framework of the Jena Experiment (Thuringia, Germany) we established control and nematicide treated subplots to manipulate nematode densities on plots varying in plant species (1-16) and functional group richness (1-4). We explored the interacting effects of nematicide application and plant diversity on the main trophic groups of nematodes and on aboveground plant productivity. Nematicide application reduced the number of nematodes significantly, particularly that of plant feeders and predators. The negative impact of nematicide application on plant and bacterial feeders depended however on the diversity of the plant community. Total plant shoot biomass tended to decrease in the presence of ambient nematode densities. In detail, nematode effects varied however with plant functional group identity by reducing only the shoot biomass of herbs significantly but not that of legumes. Furthermore, the shoot biomass of grasses tended to decrease in the presence of ambient nematode densities. In contrast to total shoot biomass, nematodes decreased grass shoot biomass only in high diverse but not in low diverse plant communities. Thus, the present study for the first time highlights that nematodes likely modify the community structure und functions of semi-natural plant communities by altering the competition between plant functional groups and by attenuating the diversity - productivity relationship.

  19. Output-Feedback Model Predictive Control of a Pasteurization Pilot Plant based on an LPV model

    NASA Astrophysics Data System (ADS)

    Karimi Pour, Fatemeh; Ocampo-Martinez, Carlos; Puig, Vicenç

    2017-01-01

    This paper presents a model predictive control (MPC) of a pasteurization pilot plant based on an LPV model. Since not all the states are measured, an observer is also designed, which allows implementing an output-feedback MPC scheme. However, the model of the plant is not completely observable when augmented with the disturbance models. In order to solve this problem, the following strategies are used: (i) the whole system is decoupled into two subsystems, (ii) an inner state-feedback controller is implemented into the MPC control scheme. A real-time example based on the pasteurization pilot plant is simulated as a case study for testing the behavior of the approaches.

  20. Plant-soil feedbacks: a comparative study on the relative importance of soil feedbacks in the greenhouse versus the field.

    PubMed

    Heinze, Johannes; Sitte, M; Schindhelm, A; Wright, J; Joshi, J

    2016-06-01

    Interactions between plants and soil microorganisms influence individual plant performance and thus plant-community composition. Most studies on such plant-soil feedbacks (PSFs) have been performed under controlled greenhouse conditions, whereas no study has directly compared PSFs under greenhouse and natural field conditions. We grew three grass species that differ in local abundance in grassland communities simultaneously in the greenhouse and field on field-collected soils either previously conditioned by these species or by the general grassland community. As soils in grasslands are typically conditioned by mixes of species through the patchy and heterogeneous plant species' distributions, we additionally compared the effects of species-specific versus non-specific species conditioning on PSFs in natural and greenhouse conditions. In almost all comparisons PSFs differed between the greenhouse and field. In the greenhouse, plant growth in species-specific and non-specific soils resulted in similar effects with neutral PSFs for the most abundant species and positive PSFs for the less abundant species. In contrast, in the field all grass species tested performed best in non-specific plots, whereas species-specific PSFs were neutral for the most abundant and varied for the less abundant species. This indicates a general beneficial effect of plant diversity on PSFs in the field. Controlled greenhouse conditions might provide valuable insights on the nominal effects of soils on plants. However, the PSFs observed in greenhouse conditions may not be the determining drivers in natural plant communities where their effects may be overwhelmed by the diversity of abiotic and biotic above- and belowground interactions in the field.

  1. Enhancing International Postgraduates' Learning Experience with Online Peer Assessment and Feedback Innovation

    ERIC Educational Resources Information Center

    Chew, Esyin; Snee, Helena; Price, Trevor

    2016-01-01

    Internationalisation and assessment and feedback are one of the main research agenda in the UK higher education. The study reports the Higher Education Academy Economics Network-funded research for international students' experience with peer assessment and feedback innovation. The Vygotsky's Zone of Proximal Development (ZPD) theoretical…

  2. Bean Plants: A Growth Experience

    ERIC Educational Resources Information Center

    West, Donna

    2004-01-01

    Teaching plant growth to seventh-grade life science students has been interesting for the author because she grew up in a rural area and always had to help in the garden. She made many assumptions about what her rural and suburban students knew. One year she decided to have them grow plants to observe the roots, stems, leaves, flowers, and fruit…

  3. Feed-Back Moisture Sensor Control for the Delivery of Water to Plants Cultivated in Space

    NASA Technical Reports Server (NTRS)

    Levine, Howard G.; Prenger, Jessica J.; Rouzan, Donna T.; Spinale, April C.; Murdoch, Trevor; Burtness, Kevin A.

    2005-01-01

    The development of a spaceflight-rated Porous Tube Insert Module (PTIM) nutrient delivery tray has facilitated a series of studies evaluating various aspects of water and nutrient delivery to plants as they would be cultivated in space. We report here on our first experiment using the PTIM with a software-driven feedback moisture sensor control strategy for maintaining root zone wetness level set-points. One-day-old wheat seedlings (Tritium aestivum cv Apogee; N=15) were inserted into each of three Substrate Compartments (SCs) pre-packed with 0.25-1 . mm Profile(TradeMark) substrate and maintained at root zone relative water content levels of 70, 80 and 90%. The SCs contained a bottom-situated porous tube around which a capillary mat was wrapped. Three Porous Tubes. were planted using similar protocols (but without the substrate) and also maintained at these three moisture level set-points. Half-strength modified Hoagland's nutrient solution was used to supply water and nutrients. Results on hardware performance, water usage rates and wheat developmental differences between the different experimental treatments are presented.

  4. Developing sexual health software incorporating user feedback: a British experience.

    PubMed

    Turner, A; Singleton, N; Easterbrook, S

    1997-02-01

    This article describes an interactive prototyping model for development of four computer software modules for British youth on sexual issues. An iterative cycle of development, user review and feedback, and subsequent modification and retesting was used with approximately 150 young adults, with particular attention to presentation style, screen design, usability, relevance of material, enjoyment, and learning. The software was designed to be realistically accommodated in school settings, to be used as a reference tool by students working alone or in a group teaching situation. Feedback from youth and adults attests to the feasibility of development, implementation, and instructional usefulness. Interactive prototyping proved essential in the face of skepticism from teachers concerning young people's information needs and acceptance of a computerized educational approach.

  5. Feedback stabilization of a class of nonlinear plants using a factorization approach

    NASA Technical Reports Server (NTRS)

    Desoer, C. A.; Kabuli, M. G.

    1988-01-01

    The authors generalize the right-coprimeness definition by requiring only that the corresponding plant's pseudo-state be reconstructable by a two-input one-output stable observer. They obtain right-coprime factorizations for a class of nonlinear plants for which a two-input one-output pseudo-state observer is constructed. A feedback stabilization scheme is given using this observer.

  6. An optimal output feedback gain variation scheme for the control of plants exhibiting gross parameter changes

    NASA Technical Reports Server (NTRS)

    Moerder, Daniel D.

    1987-01-01

    A concept for optimally designing output feedback controllers for plants whose dynamics exhibit gross changes over their operating regimes was developed. This was to formulate the design problem in such a way that the implemented feedback gains vary as the output of a dynamical system whose independent variable is a scalar parameterization of the plant operating point. The results of this effort include derivation of necessary conditions for optimality for the general problem formulation, and for several simplified cases. The question of existence of a solution to the design problem was also examined, and it was shown that the class of gain variation schemes developed are capable of achieving gain variation histories which are arbitrarily close to the unconstrained gain solution for each point in the plant operating range. The theory was implemented in a feedback design algorithm, which was exercised in a numerical example. The results are applicable to the design of practical high-performance feedback controllers for plants whose dynamics vary significanly during operation. Many aerospace systems fall into this category.

  7. Plant-soil feedbacks and the reversal of desertification with climate change

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Our objective was to provide a conceptual framework for perennial grass recovery in a series of wet years, which includes both plant-soil feedbacks that increase available water to grasses and effects of precipitation on a sequence of recovery-related processes. We tested hypotheses based on this fr...

  8. The Impact of Wireless Technology Feedback on Inventory Management at a Dairy Manufacturing Plant

    ERIC Educational Resources Information Center

    Goomas, David T.

    2012-01-01

    Replacing the method of counting inventory from paper count sheets to that of wireless reliably reduced the elapsed time to complete a daily inventory of the storage cooler in a dairy manufacturing plant. The handheld computers delivered immediate prompts as well as auditory and visual feedback. Reducing the time to complete the daily inventory…

  9. Conspecific plant-soil feedbacks of temperate tree species in the southern Appalachians, USA.

    PubMed

    Reinhart, Kurt O; Johnson, Daniel; Clay, Keith

    2012-01-01

    Many tree species have seedling recruitment patterns suggesting that they are affected by non-competitive distance-dependent sources of mortality. We conducted an experiment, with landscape-level replication, to identify cases of negative distance-dependent effects and whether variation in these effects corresponded with tree recruitment patterns in the southern Appalachian Mountains region. Specifically, soil was collected from 14 sites and used as inocula in a 62 day growth chamber experiment determining whether tree seedling growth was less when interacting with soil from conspecific (like) than heterospecific (other) tree species. Tests were performed on six tree species. Three of the tree species had been previously described as having greater recruitment around conspecifics (i.e. facilitator species group) compared to the other half (i.e. inhibitor species group). We were then able to determine whether variation in negative distance-dependent effects corresponded with recruitment patterns in the field. Across the six species, none were negatively affected by soil inocula from conspecific relative to heterospecific sources. Most species (four of six) were unaffected by soil source. Two species (Prunus serotina and Tsuga canadensis) had enhanced growth in pots inoculated with soil from conspecific trees vs. heterospecifics. Species varied in their susceptibility to soil pathogens, but trends across all species revealed that species classified as inhibitors were not more negatively affected by conspecific than heterospecific soil inocula or more susceptible to pathogenic effects than facilitators. Although plant-soil biota interactions may be important for individual species and sites, it may be difficult to scale these interactions over space or levels of ecological organization. Generalizing the importance of plant-soil feedbacks or other factors across regional scales may be especially problematic for hyperdiverse temperate forests where interactions may be

  10. Conspecific Plant-Soil Feedbacks of Temperate Tree Species in the Southern Appalachians, USA

    PubMed Central

    Reinhart, Kurt O.; Johnson, Daniel; Clay, Keith

    2012-01-01

    Many tree species have seedling recruitment patterns suggesting that they are affected by non-competitive distance-dependent sources of mortality. We conducted an experiment, with landscape-level replication, to identify cases of negative distance-dependent effects and whether variation in these effects corresponded with tree recruitment patterns in the southern Appalachian Mountains region. Specifically, soil was collected from 14 sites and used as inocula in a 62 day growth chamber experiment determining whether tree seedling growth was less when interacting with soil from conspecific (like) than heterospecific (other) tree species. Tests were performed on six tree species. Three of the tree species had been previously described as having greater recruitment around conspecifics (i.e. facilitator species group) compared to the other half (i.e. inhibitor species group). We were then able to determine whether variation in negative distance-dependent effects corresponded with recruitment patterns in the field. Across the six species, none were negatively affected by soil inocula from conspecific relative to heterospecific sources. Most species (four of six) were unaffected by soil source. Two species (Prunus serotina and Tsuga canadensis) had enhanced growth in pots inoculated with soil from conspecific trees vs. heterospecifics. Species varied in their susceptibility to soil pathogens, but trends across all species revealed that species classified as inhibitors were not more negatively affected by conspecific than heterospecific soil inocula or more susceptible to pathogenic effects than facilitators. Although plant-soil biota interactions may be important for individual species and sites, it may be difficult to scale these interactions over space or levels of ecological organization. Generalizing the importance of plant-soil feedbacks or other factors across regional scales may be especially problematic for hyperdiverse temperate forests where interactions may be

  11. Adaptive behaviour and feedback processing integrate experience and instruction in reinforcement learning.

    PubMed

    Schiffer, Anne-Marike; Siletti, Kayla; Waszak, Florian; Yeung, Nick

    2017-02-01

    In any non-deterministic environment, unexpected events can indicate true changes in the world (and require behavioural adaptation) or reflect chance occurrence (and must be discounted). Adaptive behaviour requires distinguishing these possibilities. We investigated how humans achieve this by integrating high-level information from instruction and experience. In a series of EEG experiments, instructions modulated the perceived informativeness of feedback: Participants performed a novel probabilistic reinforcement learning task, receiving instructions about reliability of feedback or volatility of the environment. Importantly, our designs de-confound informativeness from surprise, which typically co-vary. Behavioural results indicate that participants used instructions to adapt their behaviour faster to changes in the environment when instructions indicated that negative feedback was more informative, even if it was simultaneously less surprising. This study is the first to show that neural markers of feedback anticipation (stimulus-preceding negativity) and of feedback processing (feedback-related negativity; FRN) reflect informativeness of unexpected feedback. Meanwhile, changes in P3 amplitude indicated imminent adjustments in behaviour. Collectively, our findings provide new evidence that high-level information interacts with experience-driven learning in a flexible manner, enabling human learners to make informed decisions about whether to persevere or explore new options, a pivotal ability in our complex environment.

  12. SOLICITING BCI USER EXPERIENCE FEEDBACK FROM PEOPLE WITH SEVERE SPEECH AND PHYSICAL IMPAIRMENTS

    PubMed Central

    Peters, Betts; Mooney, Aimee; Oken, Barry; Fried-Oken, Melanie

    2016-01-01

    Brain-computer interface (BCI) researchers have shown increasing interest in soliciting user experience (UX) feedback, but the severe speech and physical impairments (SSPI) of potential users create barriers to effective implementation with existing feedback instruments. This article describes augmentative and alternative communication (AAC)-based techniques for obtaining feedback from this population, and presents results from administration of a modified questionnaire to 12 individuals with SSPI after trials with a BCI spelling system. The proposed techniques facilitated successful questionnaire completion and provision of narrative feedback for all participants. Questionnaire administration required less than five minutes and minimal effort from participants. Results indicated that individual users may have very different reactions to the same system, and that ratings of workload and comfort provide important information not available through objective performance measures. People with SSPI are critical stakeholders in the future development of BCI, and appropriate adaptation of feedback questionnaires and administration techniques allows them to participate in shaping this assistive technology. PMID:27135037

  13. Implications of plant acclimation for future climate-carbon cycle feedbacks

    NASA Astrophysics Data System (ADS)

    Mercado, Lina; Kattge, Jens; Cox, Peter; Sitch, Stephen; Knorr, Wolfgang; Lloyd, Jon; Huntingford, Chris

    2010-05-01

    The response of land ecosystems to climate change and associated feedbacks are a key uncertainty in future climate prediction (Friedlingstein et al. 2006). However global models generally do not account for the acclimation of plant physiological processes to increased temperatures. Here we conduct a first global sensitivity study whereby we modify the Joint UK land Environment Simulator (JULES) to account for temperature acclimation of two main photosynthetic parameters, Vcmax and Jmax (Kattge and Knorr 2007) and plant respiration (Atkin and Tjoelker 2003). The model is then applied over the 21st Century within the IMOGEN framework (Huntingford et al. 2004). Model simulations will provide new and improved projections of biogeochemical cycling, forest resilience, and thus more accurate projections of climate-carbon cycle feedbacks and the future evolution of the Earth System. Friedlingstein P, Cox PM, Betts R et al. (2006) Climate-carbon cycle feedback analysis, results from the C4MIP model intercomparison. Journal of Climate, 19, 3337-3353. Kattge J and Knorr W (2007): Temperature acclimation in a biochemical model of photosynthesis: a reanalysis of data from 36 species. Plant, Cell and Environment 30, 1176-1190 Atkin O.K and Tjoelker, M. G. (2003): Thermal acclimation and the dynamic response of plant respiration to temperature. Trends in Plant Science 8 (7), 343-351 Huntingford C, et al. (2004) Using a GCM analogue model to investigate the potential for Amazonian forest dieback. Theoretical and Applied Climatology, 78, 177-185.

  14. Linear stable unity-feedback system - Necessary and sufficient conditions for stability under nonlinear plant perturbations

    NASA Technical Reports Server (NTRS)

    Desoer, C. A.; Kabuli, M. G.

    1989-01-01

    The authors consider a linear (not necessarily time-invariant) stable unity-feedback system, where the plant and the compensator have normalized right-coprime factorizations. They study two cases of nonlinear plant perturbations (additive and feedback), with four subcases resulting from: (1) allowing exogenous input to Delta P or not; 2) allowing the observation of the output of Delta P or not. The plant perturbation Delta P is not required to be stable. Using the factorization approach, the authors obtain necessary and sufficient conditions for all cases in terms of two pairs of nonlinear pseudostate maps. Simple physical considerations explain the form of these necessary and sufficient conditions. Finally, the authors obtain the characterization of all perturbations Delta P for which the perturbed system remains stable.

  15. Vegetation dynamics and plant CO2 responses as positive feedbacks in a greenhouse world

    NASA Astrophysics Data System (ADS)

    O'ishi, Ryouta; Abe-Ouchi, Ayako; Prentice, I. Colin; Sitch, Stephen

    2009-06-01

    An atmosphere-ocean-vegetation coupled model is used to quantify the biogeophysical feedback that emerges as vegetation adjusts dynamically to a quadrupling of atmospheric CO2. This feedback amplifies global warming by 13%. About half of it is due to climatically induced expansion of boreal forest into tundra, reinforced by reductions in snow and sea ice cover. The other half represents a global climatic effect of increased vegetative cover (an indirect consequence of plant physiological responses to CO2) in the semi-arid subtropics. Enhanced absorption of shortwave radiation in these regions produces a net surface warming, which the atmosphere communicates poleward. The greatest vegetation-induced warming is co-located with large, vulnerable carbon stores in the north. These lose carbon, so that in the long term, the biospheric response to CO2 and climate change becomes dominated by positive feedbacks that overwhelm the effect of CO2 fertilization on terrestrial carbon stocks.

  16. Multiple feedbacks between chloroplast and whole plant in the context of plant adaptation and acclimation to the environment

    PubMed Central

    Demmig-Adams, Barbara; Stewart, Jared J.; Adams, William W.

    2014-01-01

    This review focuses on feedback pathways that serve to match plant energy acquisition with plant energy utilization, and thereby aid in the optimization of chloroplast and whole-plant function in a given environment. First, the role of source–sink signalling in adjusting photosynthetic capacity (light harvesting, photochemistry and carbon fixation) to meet whole-plant carbohydrate demand is briefly reviewed. Contrasting overall outcomes, i.e. increased plant growth versus plant growth arrest, are described and related to respective contrasting environments that either do or do not present opportunities for plant growth. Next, new insights into chloroplast-generated oxidative signals, and their modulation by specific components of the chloroplast's photoprotective network, are reviewed with respect to their ability to block foliar phloem-loading complexes, and, thereby, affect both plant growth and plant biotic defences. Lastly, carbon export capacity is described as a newly identified tuning point that has been subjected to the evolution of differential responses in plant varieties (ecotypes) and species from different geographical origins with contrasting environmental challenges. PMID:24591724

  17. Multiple feedbacks between chloroplast and whole plant in the context of plant adaptation and acclimation to the environment.

    PubMed

    Demmig-Adams, Barbara; Stewart, Jared J; Adams, William W

    2014-04-19

    This review focuses on feedback pathways that serve to match plant energy acquisition with plant energy utilization, and thereby aid in the optimization of chloroplast and whole-plant function in a given environment. First, the role of source-sink signalling in adjusting photosynthetic capacity (light harvesting, photochemistry and carbon fixation) to meet whole-plant carbohydrate demand is briefly reviewed. Contrasting overall outcomes, i.e. increased plant growth versus plant growth arrest, are described and related to respective contrasting environments that either do or do not present opportunities for plant growth. Next, new insights into chloroplast-generated oxidative signals, and their modulation by specific components of the chloroplast's photoprotective network, are reviewed with respect to their ability to block foliar phloem-loading complexes, and, thereby, affect both plant growth and plant biotic defences. Lastly, carbon export capacity is described as a newly identified tuning point that has been subjected to the evolution of differential responses in plant varieties (ecotypes) and species from different geographical origins with contrasting environmental challenges.

  18. Developing future plant experiments for spaceflight

    NASA Technical Reports Server (NTRS)

    Dreschel, T. W.; Brown, C. S.; Hinkle, C. R.; Sager, J. C.; Knott, W. M.

    1990-01-01

    Experiments are described which were designed to support the constructing and using clinostats for studies of microgravity effects and for measuring photosynthesis and respiration in plants in clinostat experiments. Particular attention is given to the development and testing a clinostat for rotating the Space Shuttle Mid-Deck Locker Plant Growth Unit (PGU), a sealed chamber for plan growth and gas exchange measurements on a clinostat, and a porous tube plant nutrient delivery system for the PGU. Design diagrams of these items are presented together with the results of tests.

  19. Interrater reliability of quantitative ultrasound using force feedback among examiners with varied levels of experience

    PubMed Central

    Ismail, Catheeja; Monfaredi, Reza; Hernandez, Haniel J.; Pennington, Donte; Woletz, Paula; McIntosh, Valerie; Adams, Bernadette; Blackman, Marc R.

    2016-01-01

    Background. Quantitative ultrasound measures are influenced by multiple external factors including examiner scanning force. Force feedback may foster the acquisition of reliable morphometry measures under a variety of scanning conditions. The purpose of this study was to determine the reliability of force-feedback image acquisition and morphometry over a range of examiner-generated forces using a muscle tissue-mimicking ultrasound phantom. Methods. Sixty material thickness measures were acquired from a muscle tissue mimicking phantom using B-mode ultrasound scanning by six examiners with varied experience levels (i.e., experienced, intermediate, and novice). Estimates of interrater reliability and measurement error with force feedback scanning were determined for the examiners. In addition, criterion-based reliability was determined using material deformation values across a range of examiner scanning forces (1–10 Newtons) via automated and manually acquired image capture methods using force feedback. Results. All examiners demonstrated acceptable interrater reliability (intraclass correlation coefficient, ICC = .98, p < .001) for material thickness measures obtained using force feedback. Individual examiners exhibited acceptable reliability with the criterion-based reference measures (ICC > .90, p < .001), independent of their level of experience. The measurement error among all examiners was 1.5%–2.9% across all applied stress conditions. Conclusion. Manual image capture with force feedback may aid the reliability of morphometry measures across a range of examiner scanning forces, and allow for consistent performance among examiners with differing levels of experience. PMID:27366647

  20. Comparing Student Learning Experiences of In-Text Commentary and Rubric-Articulated Feedback: Strategies for Formative Assessment

    ERIC Educational Resources Information Center

    Nordrum, Lene; Evans, Katherine; Gustafsson, Magnus

    2013-01-01

    This study compares students' experiences of two types of criteria-based assessment: in-text commentary and rubric-articulated feedback, in an assessment design combining the two feedback channels. The main aim is to use students' responses to shed light on how feedback strategies for formative assessment can be optimised. Following action…

  1. An Experiment in Teaching Electronics with Integrated Feedback System.

    ERIC Educational Resources Information Center

    Markesjo, Gunnar; Graham, Peter

    Brief, motivating television programs, lectures, calculation exercises, and laboratory experiments were integrated to teach a course in applied electronics at the Royal Institute of Technology (Stockholm). The greater part of the learning work was done in the form of independent study checked by diagnostic tests. These tests proved to have an…

  2. Exploring the Reality of Using Patient Experience Data to Provide Resident Feedback: A Qualitative Study of Attending Physician Perspectives

    PubMed Central

    Campbell, Steffanie; Goltz, Heather Honoré; Njue, Sarah; Dang, Bich Ngoc

    2016-01-01

    Introduction: Little is known about the attitudes of faculty and residents toward the use of patient experience data as a tool for providing resident feedback. The purpose of this study was to explore the attitudes of teaching faculty surrounding patient experience data and how those attitudes may influence the feedback given to trainees. Methods: From July 2013 to August 2013, we conducted in-depth, face-to-face, semistructured interviews with 9 attending physicians who precept residents in internal medicine at 2 continuity clinics (75% of eligible attendings). Interviews were coded using conventional content analysis. Results: Content analysis identified six potential barriers in using patient experience survey data to provide feedback to residents: 1) perceived inability of residents to learn or to incorporate feedback, 2) punitive nature of feedback, 3) lack of training in the delivery of actionable feedback, 4) lack of timeliness in the delivery of feedback, 5) unclear benefit of patient experience survey data as a tool for providing resident feedback, and 6) lack of individualized feedback. Conclusion: Programs may want to conduct an internal review on how patient experience data is incorporated into the resident feedback process and how, if at all, their faculty are trained to provide such feedback. PMID:27400180

  3. Nine Years of XMM-Newton Pipeline: Experience and Feedback

    NASA Astrophysics Data System (ADS)

    Michel, Laurent; Motch, Christian

    2009-05-01

    The Strasbourg Astronomical Observatory is member of the Survey Science Centre (SSC) of the XMM-Newton satellite. Among other responsibilities, we provide a database access to the 2XMMi catalogue and run the part of the data processing pipeline performing the cross-correlation of EPIC sources with archival catalogs. These tasks were all developed in Strasbourg. Pipeline processing is flawlessly in operation since 1999. We describe here the work load and infrastructure setup in Strasbourg to support SSC activities. Our nine year long SSC experience could be used in the framework of the Simbol-X ground segment.

  4. Nine Years of XMM-Newton Pipeline: Experience and Feedback

    SciTech Connect

    Michel, Laurent; Motch, Christian

    2009-05-11

    The Strasbourg Astronomical Observatory is member of the Survey Science Centre (SSC) of the XMM-Newton satellite. Among other responsibilities, we provide a database access to the 2XMMi catalogue and run the part of the data processing pipeline performing the cross-correlation of EPIC sources with archival catalogs. These tasks were all developed in Strasbourg. Pipeline processing is flawlessly in operation since 1999. We describe here the work load and infrastructure setup in Strasbourg to support SSC activities. Our nine year long SSC experience could be used in the framework of the Simbol-X ground segment.

  5. A Dataset of Three Educational Technology Experiments on Differentiation, Formative Testing and Feedback

    ERIC Educational Resources Information Center

    Haelermans, Carla; Ghysels, Joris; Prince, Fernao

    2015-01-01

    This paper describes a dataset with data from three individually randomized educational technology experiments on differentiation, formative testing and feedback during one school year for a group of 8th grade students in the Netherlands, using administrative data and the online motivation questionnaire of Boekaerts. The dataset consists of pre-…

  6. Are Success and Failure Experiences Equally Motivational? An Investigation of Regulatory Focus and Feedback

    ERIC Educational Resources Information Center

    Shu, Tse-Mei; Lam, Shui-fong

    2011-01-01

    The present study extended regulatory focus theory (Idson & Higgins, 2000) to an educational setting and attempted to identify individuals with high motivation after both success and failure feedback. College students in Hong Kong (N = 180) participated in an experiment with a 2 promotion focus (high vs. low) x 2 prevention focus (high vs.…

  7. Changing Teacher Morale: An Experiment in Feedback of Identified Problems of Teachers and Principals. Final Report.

    ERIC Educational Resources Information Center

    Bentley, Ralph R.; Rempel, Averno M.

    This 2-year study attempted to determine whether feedback to teachers and principals about problems and tensions existing in their schools can be effective in changing morale for (1) teachers generally, (2) vocational teachers, (3) and nonvocational teachers. Relationships between teacher morale and such factors as age, sex, teaching experience,…

  8. Invasive plants may promote predator-mediated feedback that inhibits further invasion

    PubMed Central

    Smith, Lauren M; Schmitz, Oswald J

    2015-01-01

    Understanding the impacts of invasive species requires placing invasion within a full community context. Plant invaders are often considered in the context of herbivores that may drive invasion by avoiding invaders while consuming natives (enemy escape), or inhibit invasion by consuming invaders (biotic resistance). However, predators that attack those herbivores are rarely considered as major players in invasion. Invasive plants often promote predators, generally by providing improved habitat. Here, we show that predator-promoting invaders may initiate a negative feedback loop that inhibits invasion. By enabling top-down control of herbivores, predator-promoting invaders lose any advantage gained through enemy escape, indirectly favoring natives. In cases where palatable invaders encounter biotic resistance, predator promotion may allow an invader to persist, but not dominate. Overall, results indicate that placing invaders in a full community context may reveal reduced impacts of invaders compared to expectations based on simple plant–plant or plant–herbivore subsystems. PMID:26120430

  9. Phytotoxicity of salt and plant salt uptake: Modeling ecohydrological feedback mechanisms

    NASA Astrophysics Data System (ADS)

    Bauer-Gottwein, Peter; Rasmussen, Nikolaj F.; Feificova, Dagmar; Trapp, Stefan

    2008-04-01

    A new model of phytotoxicity of salt and plant salt uptake is presented and is coupled to an existing three-dimensional groundwater simulation model. The implementation of phytotoxicity and salt uptake relationships is based on experimental findings from willow trees grown in hydroponic solution. The data confirm an s-shaped phytotoxicity relationship as found in previous studies. Uptake data were explained assuming steady state salt concentration in plant roots, passive salt transport into the roots, and active enzymatic removal of salt from plant roots. On the one hand, transpiration strongly depends on groundwater salinity (phytotoxicity); on the other hand, transpiration significantly changes the groundwater salinity (uptake). This feedback loop generates interesting dynamic phenomena in hydrological systems that are dominated by transpiration and are influenced by significant salinity gradients. Generic simulations are performed for the Okavango island system and are shown to reproduce essential phenomena observed in nature.

  10. Dryland feedbacks to climatic change: Results from a climate manipulation experiment on the Colorado Plateau

    NASA Astrophysics Data System (ADS)

    Reed, S.; Belnap, J.; Ferrenberg, S.; Wertin, T. M.; Darrouzet-Nardi, A.; Tucker, C.; Rutherford, W. A.

    2015-12-01

    Arid and semiarid ecosystems cover ~40% of Earth's terrestrial surface and make up ~35% of the U.S., yet we know surprisingly little about how climate change will affect these widespread landscapes. Like many dryland regions, the Colorado Plateau in the southwestern U.S. is predicted to experience climate change as elevated temperature and altered timing and amount of annual precipitation. We are using a long-term (>10 yr) factorial warming and supplemental rainfall experiment on the Colorado Plateau to explore how predicted changes in climate will affect vascular plant and biological soil crust community composition, biogeochemical cycling, and energy balance (biocrusts are a surface soil community of moss, lichen, and cyanobacteria that can make up as much as 70% of the living cover in drylands). While some of the responses we have observed were expected, many of the results are surprising. For example, we documented biocrust community composition shifts in response to altered climate that were significantly faster and more dramatic than considered likely for these soil communities that typically change over decadal and centennial timescales. Further, while we continue to observe important climate change effects on carbon cycling - including reduced net photosynthesis in vascular plants, increased CO2 losses from biocrust soils during some seasons, and changes to the interactions between water and carbon cycles - we have also found marked treatment effects on the albedo and spectral signatures of dryland soils. In addition to demonstrating the effects of these treatments, the strong relationships we observed in our experiments between biota and climate provide a quantitative framework for improving our representation of dryland responses to climate change. In this talk we will cover a range of datasets that, taken together, show: (1) large climate-driven changes to dryland biogeochemical cycling may be the result of both effects on existing communities, as well

  11. Spatial heterogeneity of plant-soil feedbacks increases per capita reproductive biomass of species at an establishment disadvantage.

    PubMed

    Burns, Jean H; Brandt, Angela J; Murphy, Jennifer E; Kaczowka, Angela M; Burke, David J

    2017-04-01

    Plant-soil feedbacks have been widely implicated as a driver of plant community diversity, and the coexistence prediction generated by a negative plant-soil feedback can be tested using the mutual invasibility criterion: if two populations are able to invade one another, this result is consistent with stable coexistence. We previously showed that two co-occurring Rumex species exhibit negative pairwise plant-soil feedbacks, predicting that plant-soil feedbacks could lead to their coexistence. However, whether plants are able to reproduce when at an establishment disadvantage ("invasibility"), or what drivers in the soil might correlate with this pattern, are unknown. To address these questions, we created experimental plots with heterogeneous and homogeneous soils using field-collected conditioned soils from each of these Rumex species. We then allowed resident plants of each species to establish and added invader seeds of the congener to evaluate invasibility. Rumex congeners were mutually invasible, in that both species were able to establish and reproduce in the other's resident population. Invaders of both species had twice as much reproduction in heterogeneous compared to homogeneous soils; thus the spatial arrangement of plant-soil feedbacks may influence coexistence. Soil mixing had a non-additive effect on the soil bacterial and fungal communities, soil moisture, and phosphorous availability, suggesting that disturbance could dramatically alter soil legacy effects. Because the spatial arrangement of soil patches has coexistence implications, plant-soil feedback studies should move beyond studies of mean effects of single patch types, to consider how the spatial arrangement of patches in the field influences plant communities.

  12. Impact of Instruction and Feedback on Reflective Responses during an Ambulatory Care Advanced Pharmacy Practice Experience

    PubMed Central

    Spangler, Mikayla; Klug, Laura; Tilleman, Jennifer; Coover, Kelli

    2016-01-01

    Objective. To investigate whether instruction and feedback on reflective responses are beneficial in developing pharmacy students to become more reflective practitioners. Methods. Students on an advanced pharmacy practice experience answered weekly reflection questions and were randomly assigned to either an intervention (received instruction and feedback on reflection) or control group. The final week’s responses were de-identified and two blinded faculty members independently categorized them as reflective or nonreflective. The primary outcome measure was comparing the number of “reflective” responses in each group. Results. The responses were classified as reflective in 83.3% of students in the intervention group (n=18) compared to 37.5% of the control group (n=16). The odds that the response was categorized as reflective were 8.3 times higher in the intervention group. Conclusion. Providing instruction and feedback to students improved the likelihood that their work was reflective. PMID:27402984

  13. Tap Arduino: An Arduino microcontroller for low-latency auditory feedback in sensorimotor synchronization experiments.

    PubMed

    Schultz, Benjamin G; van Vugt, Floris T

    2016-12-01

    Timing abilities are often measured by having participants tap their finger along with a metronome and presenting tap-triggered auditory feedback. These experiments predominantly use electronic percussion pads combined with software (e.g., FTAP or Max/MSP) that records responses and delivers auditory feedback. However, these setups involve unknown latencies between tap onset and auditory feedback and can sometimes miss responses or record multiple, superfluous responses for a single tap. These issues may distort measurements of tapping performance or affect the performance of the individual. We present an alternative setup using an Arduino microcontroller that addresses these issues and delivers low-latency auditory feedback. We validated our setup by having participants (N = 6) tap on a force-sensitive resistor pad connected to the Arduino and on an electronic percussion pad with various levels of force and tempi. The Arduino delivered auditory feedback through a pulse-width modulation (PWM) pin connected to a headphone jack or a wave shield component. The Arduino's PWM (M = 0.6 ms, SD = 0.3) and wave shield (M = 2.6 ms, SD = 0.3) demonstrated significantly lower auditory feedback latencies than the percussion pad (M = 9.1 ms, SD = 2.0), FTAP (M = 14.6 ms, SD = 2.8), and Max/MSP (M = 15.8 ms, SD = 3.4). The PWM and wave shield latencies were also significantly less variable than those from FTAP and Max/MSP. The Arduino missed significantly fewer taps, and recorded fewer superfluous responses, than the percussion pad. The Arduino captured all responses, whereas at lower tapping forces, the percussion pad missed more taps. Regardless of tapping force, the Arduino outperformed the percussion pad. Overall, the Arduino is a high-precision, low-latency, portable, and affordable tool for auditory experiments.

  14. Autonomic arousal feedback and emotional experience: evidence from the spinal cord injured.

    PubMed

    Chwalisz, K; Diener, E; Gallagher, D

    1988-05-01

    We interviewed spinal-cord-injured, other handicapped, and nonhandicapped subjects to investigate the relation between the perception of autonomic arousal and experienced emotion. The three groups differed significantly on only one measure of affect intensity, with the spinal-cord-injured subjects more often reporting stronger fear in their lives now compared with the past. In addition, spinal-cord-injured subjects often described intense emotional experiences. Spinal-cord-injured subjects who differed in their level of autonomic feedback differed in intensity on several measures. Subjects with greater autonomic feedback tended to report more intense levels of negative emotions. The findings indicate that the perception of autonomic arousal may not be necessary for emotional experience. There were weak trends in our data, however, suggesting that the perception of arousal may enhance the experience of emotional intensity. The subjective well-being reports of the handicapped groups were comparable to those of nonhandicapped subjects, indicating successful coping with their disability.

  15. The Use of Video Technology for Providing Feedback to Students: Can It Enhance the Feedback Experience for Staff and Students?

    ERIC Educational Resources Information Center

    Crook, Anne; Mauchline, Alice; Maw, Stephen; Lawson, Clare; Drinkwater, Robyn; Lundqvist, Karsten; Orsmond, Paul; Gomez, Stephen; Park, Julian

    2012-01-01

    There are numerous issues surrounding the provision of assessment-related feedback in Higher Education, which in recent years have been highlighted in the National Student Survey. In this paper questionnaire data from staff and students at the University of Reading are used to confirm the main issues encountered with feedback, namely problems of…

  16. Efficient plant growth using automatic position-feedback laser light irradiation

    NASA Astrophysics Data System (ADS)

    Kakinoki, Yoshiaki; Kato, Yuya; Ogawa, Kosuke; Nakao, Akira; Okai, Zenshiro; Katsuyama, Toshio

    2013-05-01

    The plant growth based on the scanning laser beam is newly developed. Three semiconductor lasers with three primary colors, i.e., blue, green and red are used. Here, the laser scanned position is restricted only to the plant leaves, where the light illumination is needed. The feedback system based on the perspective projection is developed. The system consists of the automatic position correction from the camera image. The automatic image extraction of the leaf parts is also introduced. The electric power needed for this system is as small as 6.25% compared with the traditional white fluorescent lamp. Furthermore, experimental results show that the red-color laser light is particularly efficient for the growth of the radish sprouts.

  17. Phylogenetic conservatism in plant-soil feedback and its implications for plant abundance

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Plant interactions with macro-mutualists (e.g., seed dispersers, pollinators) and antagonists (e.g., herbivores, pathogens) often exhibit phylogenetic conservatism, but conservatism of interactions with soil microorganisms is understudied. We assembled one of the best available datasets to examine c...

  18. Exploring Early Angiosperm Fire Feedbacks using Coupled Experiments and Modelling Approaches to Estimate Cretaceous Palaeofire Behaviour

    NASA Astrophysics Data System (ADS)

    Belcher, Claire; Hudpsith, Victoria

    2016-04-01

    Using the fossil record we are typically limited to exploring linkages between palaeoecological changes and palaeofire activity by assessing the abundance of charcoals preserved in sediments. However, it is the behaviour of fires that primarily governs their ecological effects. Therefore, the ability to estimate variations in aspects of palaeofire behaviour such as palaeofire intensity and rate of spread would be of key benefit toward understanding the coupled evolutionary history of ecosystems and fire. The Cretaceous Period saw major diversification in land plants. Previously, conifers (gymnosperms) and ferns (pteridophytes) dominated Earth's ecosystems until flowering plants (angiosperms) appear in the fossil record of the Early Cretaceous (~135Ma). We have created surface fire behaviour estimates for a variety of angiosperm invasion scenarios and explored the influence of Cretaceous superambient atmospheric oxygen levels on the fire behaviour occurring in these new Cretaceous ecosystems. These estimates are then used to explore the hypothesis that the early spread of the angiosperms was promoted by the novel fire regimes that they created. In order to achieve this we tested the flammability of Mesozoic analogue fuel types in controlled laboratory experiments using an iCone calorimeter, which measured the ignitability as well as the effective heat of combustion of the fuels. We then used the BehavePlus fire behaviour modelling system to scale up our laboratory results to the ecosystem scale. Our results suggest that fire-angiosperm feedbacks may have occurred in two phases: The first phase being a result of weedy angiosperms providing an additional easily ignitable fuel that enhanced both the seasonality and frequency of surface fires. In the second phase, the addition of shrubby understory fuels likely expanded the number of ecosystems experiencing more intense surface fires, resulting in enhanced mortality and suppressed post-fire recruitment of gymnosperms

  19. Can Plant Community Turnover Mitigate Permafrost Thaw Feedbacks to the Climate System?

    NASA Astrophysics Data System (ADS)

    Hough, M.; Garnello, A.; Finnell, D.; Palace, M. W.; Rich, V. I.; Saleska, S. R.

    2014-12-01

    In many parts of the Arctic, permafrost thaw due to rising temperatures results in the conversion of dry tundra to wetland bog and fen ecosystems. Such increases in anaerobic environments may have substantial feedbacks to the rate of climate change through the increased production of CH4, a greenhouse gas an order of magnitude more potent than the CO2 respired from aerobic soils. However, the total emission rates of CH4 and CO2 alone cannot predict the magnitude of feedback to the climate system since this will also depend on the ecosystem's overall carbon balance and the source of carbon (new vs old) producing the emissions. Thus, building detailed carbon budgets is essential to understanding the potential climate feedbacks of habitat changes due to permafrost thaw. We studied above-ground plant biomass and its carbon content in order to calculate the inputs of new carbon to the soil along a permafrost thaw gradient with previously well-quantified CO2 and CH4 fluxes in northern Sweden. In order to account for within-season plant community turnover, we monitored plant percent cover over the course of a growing season in three communities: areas underlain by permafrost dominated by E. vaginatum, and E. nigrum, recently thawed sphagnum dominated areas, and more established E. angustifolium dominated fen communities. Additionally, we calculated end of season biomass and percent carbon for each species and compared our findings to previously published community composition assessments from 1972/1973 and 2000. We tied our ground-based measurements to aerial remote sensing images to extrapolate biomass and percent carbon across the mire based on community type. These results allow us to calculate total carbon inputs to the mire from new above-ground biomass. By coupling these measurements with flux rates from each habitat we will be able to assess the degree to which increased biomass production might offset the increase in CH4 released from soils as a result of plant

  20. Small motion experiments on a large flexible arm with strain feedback

    NASA Technical Reports Server (NTRS)

    Yuan, B. S.; Huggins, J. D.; Book, W. J.

    1989-01-01

    Initial experiments on state-space feedback control of a large flexible manipulator with a parallel linkage drive are described. A linear controller using joint angle and strain measurements has been designed to minimize a quadratic performance index with a prescribed stability margin. It is based on a simplified model that accounts for the constraints of the parallel linkage kinematically rather than through constraint forces. The results show substantial improvement over a simple proportional-derivative joint control.

  1. Interactions between spring temperatures and snow cover alter plant-soil nutrient feedbacks in moist acidic arctic tundra

    NASA Astrophysics Data System (ADS)

    Weintraub, M. N.; Steltzer, H.; Sullivan, P.; Darrouzet-Nardi, A.; Schimel, J.; Wallenstein, M. D.; Livensperger, C.; Segal, A. D.

    2012-12-01

    A significant spring warming trend has been observed across the arctic, resulting in higher spring temperatures and earlier snowmelt. These climate changes have the potential to alter arctic soil carbon (C) and nitrogen (N) dynamics because they can significantly influence both plant growth and decomposition during the growing season. These changes are of particular concern because arctic tundra soils contain large stores of C and may act as a significant CO2 source with warming. To determine how changes in the timing of snowmelt and higher spring temperatures affect plant growth and soil nutrient dynamics, we conducted a factorial accelerated snowmelt and warming experiment in a moist acidic tundra plant community in the Alaskan arctic. We measured changes plant phenology and growth, and soil nutrient dynamics in response to these manipulations to determine the implications of earlier snowmelt and warming. We hypothesized that accelerated snowmelt would allow plants to start growing earlier, resulting in earlier root growth and plant N uptake from these nutrient poor soils, potentially exacerbating N limitation to decomposer microorganisms and reducing their activities. Contrary to our predictions, we observed delayed and reduced root growth in response to accelerated snowmelt, without similar reductions in aboveground productivity. We also found that warming in combination with accelerated snowmelt alleviated the inhibition of root growth, suggesting that low air temperatures following snowmelt may have inhibited plant growth, as plants were unprotected from swings in air temperature without the insulating snowpack. Furthermore, we found that greater root growth was associated with elevated, not reduced, soil N availability, which was also opposite to our predictions. These results suggest that C-rich root exudates stimulate microbial N acquisition and can actually increase N availability even as roots and microbes are taking up more N. This implies that as long

  2. Optimized feedback control system modeling of resistive wall modes for burning plasmas experiments

    NASA Astrophysics Data System (ADS)

    Katsuro-Hopkins, Oksana Nikolaevna

    A numerical study of active feedback control system performance and optimization for tokamak Resistive Wall Modes (RWM) is the subject of this thesis. The ability to accurately model and predict the performance of an active MHD control systems is critical to present and future advanced confinement scenarios and fusion reactor design studies. The computer code VALEN has been designed to calculate the performance of a MHD feedback control system in an arbitrary geometry. The simulation of realistic effects in feedback systems, such as noise, time delays and filters is of particular importance. In this work realistic measurement noise analysis was added to VALEN and used to design the RWM feedback control amplifier power level for the DIII-D experiment. Modern control theory based on a state-space formulation obtained from VALEN was applied to design an Optimal Controller and Observer based on a reduced VALEN model. A quantitative low order model of the VALEN state space was derived from the high dimensional intrinsic state space structure of the VALEN using methods of a balanced realization and matched DC gain truncation. These techniques for the design of an optimal controller and optimal observer were applied to models of the DIII-D and ITER experiments and showed an order of magnitude reduction of the required control coil current and voltage in the presence of white noise as compared to a traditional, classical PID controller. This optimal controller for the ITER burning plasma experiment was robust from the no-wall pressure limit to a pressure value well above those achieved with a classical PID controller and could approach the ideal wall limit.

  3. Plant uptake of radionuclides in lysimeter experiments.

    PubMed

    Gerzabek, M H; Strebl, F; Temmel, B

    1998-01-01

    The results of seven years lysimeter experiments to determine the uptake of 60Co, 137Cs and 226Ra into agricultural crops (endive, maize, wheat, mustard, sugarbeet, potato, Faba bean, rye grass) are described. The lysimeter consists of twelve monolithic soil profiles (four soil types and three replicates) and is located in Seibersdorf/Austria, a region with a pannonian climate (pronounced differences between hot and semi-arid summers and humid winter conditions, annual mean of precipitation: 517 mm, mean annual temperature: 9.8 degrees C). Besides soil-to-plant transfer factors (TF), fluxes were calculated taking into account biomass production and growth time. Total median values of TF's (dry matter basis) for the three radionuclides decreased from 226Ra (0.068 kg kg(-1)) to 137Cs (0.043 kg kg(-1)) and 60Co (0.018 kg kg(-1)); flux values exhibited the same ranking. The varying physical and chemical properties of the four experimental soils resulted in statistically significant differences in transfer factors or fluxes between the investigated soils for 137Cs and 226Ra, but not for 60Co. Differences in transfer between plant species and plant parts are distinct, with graminaceous species showing, on average, TF values 5.8 and 15 times lower than dicotyledonous species for 137Cs and 60Co, respectively. This pattern was not found for 226Ra. It can be concluded that 137Cs transfer is heavily influenced by soil characteristics, whilst the plant-specific factors are the main source of TF variability for 60Co. The variability of 226Ra transfer originates both from soil properties and plant species behaviour.

  4. Climate effects and feedback structure determining weed population dynamics in a long-term experiment.

    PubMed

    Lima, Mauricio; Navarrete, Luis; González-Andujar, José Luis

    2012-01-01

    Pest control is one of the areas in which population dynamic theory has been successfully applied to solve practical problems. However, the links between population dynamic theory and model construction have been less emphasized in the management and control of weed populations. Most management models of weed population dynamics have emphasized the role of the endogenous process, but the role of exogenous variables such as climate have been ignored in the study of weed populations and their management. Here, we use long-term data (22 years) on two annual weed species from a locality in Central Spain to determine the importance of endogenous and exogenous processes (local and large-scale climate factors). Our modeling study determined two different feedback structures and climate effects in the two weed species analyzed. While Descurainia sophia exhibited a second-order feedback and low climate influence, Veronica hederifolia was characterized by a first-order feedback structure and important effects from temperature and rainfall. Our results strongly suggest the importance of theoretical population dynamics in understanding plant population systems. Moreover, the use of this approach, discerning between the effect of exogenous and endogenous factors, can be fundamental to applying weed management practices in agricultural systems and to controlling invasive weedy species. This is a radical change from most approaches currently used to guide weed and invasive weedy species managements.

  5. Do Those Who Benefit the Most Need it the Least? A Four-Year Experiment in Enquiry-Based Feedback

    ERIC Educational Resources Information Center

    Adcroft, Andy; Willis, Robert

    2013-01-01

    The aim of this paper is to report on an ongoing experiment in an enquiry-based approach to feedback. Over the course of four years, almost 1800 students have studied a final-year undergraduate module involving a mid-term assignment and end of module examination. Feedback on the assignment is delivered through a process which involves the…

  6. Fast plaque sizing and some applications of the technique in antibody feedback experiments.

    PubMed

    Dresser, D W

    1990-05-08

    A method has been devised to make rapid assessments of plaque size simultaneously with plaque enumeration. The method depends on an inexpensive and simple interfacing of a weighted counter to a microcomputer. Comparisons made between relative (weighted counter) and absolute (photographic) assessments of plaque size, show that the relationship is not linear. It has been shown that assay conditions must be rigidly controlled for valid size comparisons to be made. IgM and IgG PFC specific for sheep RBC, burro RBC and TNP-, in primary and secondary, active and adoptive responses, were used in these experiments. An application of the method in antibody feedback experiments is described.

  7. Plant-soil feedbacks and soil sickness: from mechanisms to application in agriculture.

    PubMed

    Huang, Li-Feng; Song, Liu-Xia; Xia, Xiao-Jian; Mao, Wei-Hua; Shi, Kai; Zhou, Yan-Hong; Yu, Jing-Quan

    2013-02-01

    Negative plant-soil feedbacks play an important role in soil sickness, which is one of the factors limiting the sustainable development of intensive agriculture. Various factors, such as the buildup of pests in the soil, disorder in physico-chemical soil properties, autotoxicity, and other unknown factors may contribute to soil sickness. A range of autotoxins have been identified, and these exhibit their allelopathic potential by influencing cell division, water and ion uptake, dark respiration, ATP synthesis, redox homeostasis, gene expression, and defense responses. Meanwhile, there are great interspecific and intraspecific differences in the uptake and accumulation of autotoxins, which contribute to the specific differences in growth in response to different autotoxins. Importantly, the autotoxins also influence soil microbes and vice versa, leading to an increased or decreased degree of soil sickness. In many cases, autotoxins may enhance soilborne diseases by predisposing the roots to infection by soilborne pathogens through a direct biochemical and physiological effect. Some approaches, such as screening for low autotoxic potential and disease-resistant genotypes, proper rotation and intercropping, proper soil and plant residue management, adoption of resistant plant species as rootstocks, introduction of beneficial microbes, physical removal of phytotoxins, and soil sterilization, are proposed. We discuss the challenges that we are facing and possible approaches to these.

  8. Design of feedback control systems for unstable plants with saturating actuators

    NASA Technical Reports Server (NTRS)

    Kapasouris, Petros; Athans, Michael; Stein, Gunter

    1988-01-01

    A new control design methodology is introduced for multi-input/multi-output systems with unstable open loop plants and saturating actuators. A control system is designed using well known linear control theory techniques and then a reference prefilter is introduced so that when the references are sufficiently small, the control system operates linearly as designated. For signals large enough to cause saturations, the control law is modified in such a way to ensure stability and to preserve, to the extent possible, the behavior of the linear control design. Key benefits of this methodology are: the modified feedback system never produces saturating control signals, integrators and/or slow dynamics in the compensator never windup, the directionaL properties of the controls are maintained, and the closed loop system has certain guaranteed stability properties. The advantages of the new design methodology are illustrated in the simulation of an approximation of the AFTI-16 (Advanced Fighter Technology Integration) aircraft multivariable longitudinal dynamics.

  9. A hydroponic system for microgravity plant experiments

    NASA Technical Reports Server (NTRS)

    Wright, B. D.; Bausch, W. C.; Knott, W. M.

    1988-01-01

    The construction of a permanently manned space station will provide the opportunity to grow plants for weeks or months in orbit for experiments or food production. With this opportunity comes the need for a method to provide plants with a continuous supply of water and nutrients in microgravity. The Capillary Effect Root Environment System (CERES) uses capillary forces to maintain control of circulating plant nutrient solution in the weightless environment of an orbiting spacecraft. The nutrient solution is maintained at a pressure slightly less than the ambient air pressure while it flows on one side of a porous membrane. The root, on the other side of the membrane, is surrounded by a thin film of nutrient solution where it contacts the moist surface of the membrane. The root is provided with water, nutrients and air simultaneously. Air bubbles in the nutrient solution are removed using a hydrophobic/hydrophilic membrane system. A model scaled to the size necessary for flight hardware to test CERES in the space shuttle was constructed.

  10. Ecogeomorphic feedbacks and flood loss of riparian tree seedlings in meandering channel experiments

    NASA Astrophysics Data System (ADS)

    Kui, Li; Stella, John C.; Lightbody, Anne; Wilcox, Andrew C.

    2014-12-01

    During floods, fluvial forces interact with riparian plants to influence evolution of river morphology and floodplain plant community development. Understanding of these interactions, however, is constrained by insufficient precision and control of drivers in field settings, and insufficient realism in laboratory studies. We completed a novel set of flume experiments using woody seedlings planted on a sandbar within an outdoor meandering stream channel. We quantified effects on local sedimentation and seedling loss to scour and burial across realistic ranges of woody plant morphologies (Populus versus Tamarix species), densities (240 plants m-2 versus 24 m-2), and sediment supply (equilibrium versus deficit). Sedimentation was higher within Tamarix patches than Populus patches, reflecting Tamarix's greater crown frontal area and lower maximum crown density. Plant dislodgement occurred rarely (1% of plants) and was induced in plants with shorter roots. Complete burial was most frequent for small Tamarix that occurred at high densities. Burial risk decreased 3% for Populus and 13% for Tamarix for every centimeter increment in stem height, and was very low for plants >50 cm tall. These results suggest that Tamarix are proportionally more vulnerable than Populus when small (<20 cm tall), but that larger plants of both species are resistant to both burial and scour. Thus, plant morphological traits and development windows must be considered in addition to physical drivers when designing process-based restoration efforts on regulated rivers such as flow releases to benefit native tree species.

  11. Using voice input and audio feedback to enhance the reality of a virtual experience

    SciTech Connect

    Miner, N.E.

    1994-04-01

    Virtual Reality (VR) is a rapidly emerging technology which allows participants to experience a virtual environment through stimulation of the participant`s senses. Intuitive and natural interactions with the virtual world help to create a realistic experience. Typically, a participant is immersed in a virtual environment through the use of a 3-D viewer. Realistic, computer-generated environment models and accurate tracking of a participant`s view are important factors for adding realism to a virtual experience. Stimulating a participant`s sense of sound and providing a natural form of communication for interacting with the virtual world are equally important. This paper discusses the advantages and importance of incorporating voice recognition and audio feedback capabilities into a virtual world experience. Various approaches and levels of complexity are discussed. Examples of the use of voice and sound are presented through the description of a research application developed in the VR laboratory at Sandia National Laboratories.

  12. First feedback with the AMMON integral experiment for the JHR calculations

    NASA Astrophysics Data System (ADS)

    Vaglio-Gaudard, C.; Leray, O.; Lemaire, M.; Colombier, A. C.; Hudelot, J. P.

    2013-03-01

    The innovative design of the next international Material Testing Reactor, the Jules Horowitz Reactor (JHR), induced the development of a new neutron and photon calculation formular HORUS3D/P&N, based on deterministic and stochastic codes and the European nuclear data library JEFF3.1.1. A new integral experiment, named the AMMON experiment, was designed in order to make the experimental validation of HORUS3D. The objectives of this experimental program are to calibrate the biases and uncertainties associated with the HORUS3D/N&P calculations for JHR safety and design calculations, but also the validation of some specific nuclear data (concerning mainly hafnium and beryllium isotopes). The experiment began in 2010 and is currently performed in the EOLE zero-power critical mock-up at CEA Cadarache. This paper deals with the first feedback of the AMMON experiments with 3D Monte Carlo TRIPOLI4©/JEFF3.1.1 calculations.

  13. Experience Sampling-Based Personalized Feedback and Positive Affect: A Randomized Controlled Trial in Depressed Patients

    PubMed Central

    Hartmann, Jessica A.; Wichers, Marieke; Menne-Lothmann, Claudia; Kramer, Ingrid; Viechtbauer, Wolfgang; Peeters, Frenk; Schruers, Koen R. J.; van Bemmel, Alex L.; Myin-Germeys, Inez; Delespaul, Philippe; van Os, Jim; Simons, Claudia J. P.

    2015-01-01

    Objectives Positive affect (PA) plays a crucial role in the development, course, and recovery of depression. Recently, we showed that a therapeutic application of the experience sampling method (ESM), consisting of feedback focusing on PA in daily life, was associated with a decrease in depressive symptoms. The present study investigated whether the experience of PA increased during the course of this intervention. Design Multicentre parallel randomized controlled trial. An electronic random sequence generator was used to allocate treatments. Settings University, two local mental health care institutions, one local hospital. Participants 102 pharmacologically treated outpatients with a DSM-IV diagnosis of major depressive disorder, randomized over three treatment arms. Intervention Six weeks of ESM self-monitoring combined with weekly PA-focused feedback sessions (experimental group); six weeks of ESM self-monitoring combined with six weekly sessions without feedback (pseudo-experimental group); or treatment as usual (control group). Main outcome The interaction between treatment allocation and time in predicting positive and negative affect (NA) was investigated in multilevel regression models. Results 102 patients were randomized (mean age 48.0, SD 10.2) of which 81 finished the entire study protocol. All 102 patients were included in the analyses. The experimental group did not show a significant larger increase in momentary PA during or shortly after the intervention compared to the pseudo-experimental or control groups (χ2 (2) =0.33, p=.846). The pseudo-experimental group showed a larger decrease in NA compared to the control group (χ2 (1) =6.29, p=.012). Conclusion PA-focused feedback did not significantly impact daily life PA during or shortly after the intervention. As the previously reported reduction in depressive symptoms associated with the feedback unveiled itself only after weeks, it is conceivable that the effects on daily life PA also evolve

  14. Experience in action: Moderating care in web-based patient feedback.

    PubMed

    Ziewitz, Malte

    2017-02-01

    What does it take to mobilise experiences of care and make them useful for improving services? This article draws on ethnographic fieldwork with a UK-based patient feedback website to develop a critical perspective on patient experience as a contingent accomplishment and a focal point for eliciting, provoking, and respecifying relations of accountability. Following a single posting from the moderation room back to the author and into the wards and offices of the hospital, I show how moderators, carers, and clinical staff respond to and act upon a seemingly stable experience. Drawing on recent work in science studies and ethnomethodology, I suggest that the work of 'capturing the patient experience' is not so much a matter of accurate reporting or incontestable opining, but an exercise in testing versions of reality through the ongoing respecification of objects, audiences, and identities. Attending to the mundane practices of moderating accounts of care highlights the work of ordering alongside technologies of evaluation - the largely invisible labour that sustains the possibility of public patient feedback in the first place.

  15. General practitioners’ and students’ experiences with feedback during a six-week clerkship in general practice: a qualitative study

    PubMed Central

    Gran, Sarah Frandsen; Brænd, Anja Maria; Lindbæk, Morten; Frich, Jan C.

    2016-01-01

    Objective Feedback may be scarce and unsystematic during students' clerkship periods. We wanted to explore general practitioners' (GPs) and medical students' experiences with giving and receiving supervision and feedback during a clerkship in general practice, with a focus on their experiences with using a structured tool (StudentPEP) to facilitate feedback and supervision. Design Qualitative study. Setting Teachers and students from a six-week clerkship in general practice for fifth year medical students were interviewed in two student and two teacher focus groups. Subjects 21 GPs and nine medical students. Results We found that GPs first supported students' development in the familiarization phase by exploring the students' expectations and competency level. When mutual trust had been established through the familiarization phase GPs encouraged students to conduct their own consultations while being available for supervision and feedback. Both students and GPs emphasized that good feedback promoting students' professional development was timely, constructive, supportive, and focused on ways to improve. Among the challenges GPs mentioned were giving feedback on behavioral issues such as body language and insensitive use of electronic devices during consultations or if the student was very insecure, passive, and reluctant to take action or lacked social or language skills. While some GPs experienced StudentPEP as time-consuming and unnecessary, others argued that the tool promoted feedback and learning through mandatory observations and structured questions. Conclusion Mutual trust builds a learning environment in which supervision and feedback may be given during students' clerkship in general practice. Structured tools may promote feedback, reflection and learning. Key PointsObserving the teacher and being supervised are essential components of Medical students' learning during general practice clerkships.Teachers and students build mutual trust in the

  16. Development of electrical feedback controlled heat pipes and the advanced thermal control flight experiment

    NASA Technical Reports Server (NTRS)

    Bienert, W. B.

    1974-01-01

    The development and characteristics of electrical feedback controlled heat pipes (FCHP) are discussed. An analytical model was produced to describe the performance of the FCHP under steady state and transient conditions. An advanced thermal control flight experiment was designed to demonstrate the performance of the thermal control component in a space environment. The thermal control equipment was evaluated on the ATS-F satellite to provide performance data for the components and to act as a thermal control system which can be used to provide temperature stability of spacecraft components in future applications.

  17. Analysis of Forcing, Response, and Feedbacks in a Paleoclimate Modeling Experiment

    SciTech Connect

    Taylor, K E; Hewitt, C D; Braconnot, P; Broccoli, A J; Doutriaux, C; Mitchell, J F B

    2001-04-11

    It is often argued that paleoclimate studies are necessary to determine whether climate models and their predictions of future climate change can be trusted. An overall measure of the sensitivity of global mean surface temperature to a given radiative perturbation is provided by the global climate sensitivity parameter. In climate model experiments, this parameter appears to be moderately independent of the cause of the perturbation [see, for example, Hansen et al. (1997) and Hewitt and Mitchell (1997)], but it may differ from one model to the next by as much as a factor of three (IPCC, 1995). Moreover, there are some scientists who claim that all models are much more sensitive than the climate system itself (Lindzen, 1997). Thus it would be valuable to determine which models (if any) are consistent with the paleoclimate record and what factors are responsible for model differences in sensitivity. In an analysis of the Paleoclimate Modeling Intercomparison Project (PMIP) simulations of the Last Glacial Maximum (LGM) of 21,000 years ago, we have calculated how the ''forcing'' and feedbacks determine the climatic response. In the PMIP context, the ice sheet distribution is prescribed and the resulting increase in planetary albedo is the most important ''forcing'' factor. Also important are radiation perturbations induced by changes in atmospheric CO{sub 2} concentration. Here we describe a new, approximate method for estimating the strength of forcing and feedback factors from commonly archived model output. We also summarize preliminary results from the PMIP experiment, which show that differences in forcing and to a lesser extent differences in feedbacks can explain differences in surface temperature response.

  18. Feedbacks Between Microenvironment and Plant Functional Type and Implications for CO2 Flux in Arctic Ecosystems

    NASA Astrophysics Data System (ADS)

    Squires, E.; Rodenheizer, H.; Natali, S.; Mann, P.

    2013-12-01

    Future climate models predict a warmer, drier Arctic, with resultant shifts in vegetative composition and implications for ecosystem carbon budgets. The impact of vegetation change, however, may depend on which plant functional groups are favored in a warming Arctic. Physiological and functional differences between plant groups influence both the local microenvironment and, on a broader scale, whole-ecosystem CO2 flux. We examined the interactions between plants and their microenvironment, and analyzed the effect of these interactions on both soil microbial communities and CO2 flux across different functional groups. Physical and biological aspects of the microenvironment differed between plant functional groups. Lichen patches were characterized by deeper thaw depths, lower soil moisture, greater thermal conductivity, and a thinner organic layer than mosses. To better understand the development of these plant-environment interactions, we conducted a reciprocal transplant experiment, switching multiple lichen and moss patches. Temporal changes in environmental parameters at these sites will demonstrate how different plants modify their environment and will help identify associated implications for soil microbial communities and CO2 flux. We measured CO2 flux and used Biolog assays to examine soil microbial communities in undisturbed patches of mosses, lichens, and shrubs. Patches of birch shrubs had more negative net ecosystem exchange, signifying a carbon sink. Soils from alder shrubs and mosses hosted more active microbial communities than soils under birch shrubs and lichens. These results suggest a strong link between environment, plant functional type, and C cycling. Understanding how this relationship differs among plant functional types is an important part of predicting ecosystem carbon budgets as Arctic vegetation composition shifts in response to climate change.

  19. Development and preliminary psychometric properties of the Care Experience Feedback Improvement Tool (CEFIT)

    PubMed Central

    Beattie, Michelle; Shepherd, Ashley; Lauder, William; Atherton, Iain; Cowie, Julie; Murphy, Douglas J

    2016-01-01

    Objective To develop a structurally valid and reliable, yet brief measure of patient experience of hospital quality of care, the Care Experience Feedback Improvement Tool (CEFIT). Also, to examine aspects of utility of CEFIT. Background Measuring quality improvement at the clinical interface has become a necessary component of healthcare measurement and improvement plans, but the effectiveness of measuring such complexity is dependent on the purpose and utility of the instrument used. Methods CEFIT was designed from a theoretical model, derived from the literature and a content validity index (CVI) procedure. A telephone population surveyed 802 eligible participants (healthcare experience within the previous 12 months) to complete CEFIT. Internal consistency reliability was tested using Cronbach's α. Principal component analysis was conducted to examine the factor structure and determine structural validity. Quality criteria were applied to judge aspects of utility. Results CVI found a statistically significant proportion of agreement between patient and practitioner experts for CEFIT construction. 802 eligible participants answered the CEFIT questions. Cronbach's α coefficient for internal consistency indicated high reliability (0.78). Interitem (question) total correlations (0.28–0.73) were used to establish the final instrument. Principal component analysis identified one factor accounting for 57.3% variance. Quality critique rated CEFIT as fair for content validity, excellent for structural validity, good for cost, poor for acceptability and good for educational impact. Conclusions CEFIT offers a brief yet structurally sound measure of patient experience of quality of care. The briefness of the 5-item instrument arguably offers high utility in practice. Further studies are needed to explore the utility of CEFIT to provide a robust basis for feedback to local clinical teams and drive quality improvement in the provision of care experience for patients

  20. Reciprocal Markov modeling of feedback mechanisms between emotion and dietary choice using experience sampling data

    PubMed Central

    Lu, Ji; Pan, Junhao; Zhang, Qiang; Dubé, Laurette; Ip, Edward H.

    2015-01-01

    With intensively collected longitudinal data, recent advances in Experience Sampling Method (ESM) benefit social science empirical research, but also pose important methodological challenges. As traditional statistical models are not generally well-equipped to analyze a system of variables that contain feedback loops, this paper proposes the utility of an extended hidden Markov model to model reciprocal relationship between momentary emotion and eating behavior. This paper revisited an ESM data set (Lu, Huet & Dube, 2011) that observed 160 participants’ food consumption and momentary emotions six times per day in 10 days. Focusing on the analyses on feedback loop between mood and meal healthiness decision, the proposed Reciprocal Markov Model (RMM) can accommodate both hidden (“general” emotional states: positive vs. negative state) and observed states (meal: healthier, same or less healthy than usual) without presuming independence between observations and smooth trajectories of mood or behavior changes. The results of RMM analyses illustrated the reciprocal chains of meal consumption and mood as well as the effect of contextual factors that moderate the interrelationship between eating and emotion. A simulation experiment that generated data consistent to the empirical study further demonstrated that the procedure is promising in terms of recovering the parameters. PMID:26717120

  1. Conjugate feedback induced suppression and generation of oscillations in the Chua circuit: experiments and simulations.

    PubMed

    Mandal, Tirtha; Singla, Tanu; Rivera, M; Parmananda, P

    2013-03-01

    We study the suppression (amplitude death) and generation of oscillations (rhythmogenesis) in the Chua circuit using a feedback term consisting of conjugate variables (conjugate feedback). When the independent Chua circuit (without feedback) is placed in the oscillatory domain, this conjugate feedback induces amplitude death in the system. On the contrary, introducing the conjugate feedback in the system exhibiting fixed point behavior results in the generation of rhythms. Furthermore, it is observed that the dynamics of the Chua circuit could be tuned efficiently by varying the strength of this feedback term. Both experimental and numerical results are presented.

  2. Operating experience feedback report: Experience with pump seals installed in reactor coolant pumps manufactured by Byron Jackson

    SciTech Connect

    Bell, L.G.; O'Reilly, P.D.

    1992-09-01

    This report examines the reactor coolant pump (RCP) seal operating experience through August 1990 at plants with Byron Jackson (B-J) RCPs. ne operating experience examined in this analysis included a review of the practice of continuing operation with a degraded seal. Plants with B-J RCPs that have had relatively good experience with their RCP seals attribute this success to a combination of different factors, including: enhanced seal QA efforts, modified/new seal designs, improved maintenance procedures and training, attention to detail, improved seal operating procedures, knowledgeable personnel involved in seal maintenance and operation, reduction in frequency of transients that stress the seals, seal handling and installation equipment designed to the appropriate precision, and maintenance of a clean seal cooling water system. As more plants have implemented corrective measures such as these, the number of B-J RCP seal failures experienced has tended to decrease. This study included a review of the practice of continued operation with a degraded seal in the case of PWR plants with Byron Jackson reactor coolant pumps. Specific factors were identified which should be addressed in order to safety manage operation of a reactor coolant pump with indications of a degrading seal.

  3. The Anticipative Value of Individual and Group Information Feedback on the Decision Process During the Simulation Experiment

    NASA Astrophysics Data System (ADS)

    Kljajić, M.; Škraba, A.; Kljajić, M.

    2004-08-01

    This paper presents the influence of individual and group feedback information introduced by the system dynamics model in a multicriteria decision process. The experiment was performed in a controlled environment. The criteria function was explicitly defined in order to increase the level of experimental control. The experiment was conducted under three experimental conditions: a1) determination of strategy on the basis of a subjective judgment of the task, a2) determination of strategy with the application of a system dynamics model without group interaction, and a3) determination of strategy with the application of a formal model with subject interaction supported by group feedback information. 147 subjects, senior university students, participated in the experiment. The hypothesis that model application and group feedback information positively influence the convergence of the decision process and contribute to higher criteria function values was confirmed.

  4. Strong species-environment feedback shapes plant community assembly along environmental gradients

    USGS Publications Warehouse

    Jiang, Jiang; DeAngelis, Donald L.

    2013-01-01

    An aim of community ecology is to understand the patterns of competing species assembly along environmental gradients. All species interact with their environments. However, theories of community assembly have seldom taken into account the effects of species that are able to engineer the environment. In this modeling study, we integrate the species' engineering trait together with processes of immigration and local dispersal into a theory of community assembly. We quantify the species' engineering trait as the degree to which it can move the local environment away from its baseline state towards the optimum state of the species (species-environment feedback). We find that, in the presence of immigration from a regional pool, strong feedback can increase local species richness; however, in the absence of continual immigration, species richness is a declining function of the strength of species-environment feedback. This shift from a negative effect of engineering strength on species richness to a positive effect, as immigration rate increases, is clearer when there is spatial heterogeneity in the form of a gradient in environmental conditions than when the environment is homogeneous or it is randomly heterogeneous. Increasing the scale over which local dispersal occurs can facilitate species richness when there is no species-environment feedback or when the feedback is weak. However, increases in the spatial scale of dispersal can reduce species richness when the species-environment feedback is strong. These results expand the theoretical basis for understanding the effects of the strength of species-environment feedback on community assembly.

  5. Strong species-environment feedback shapes plant community assembly along environmental gradients.

    PubMed

    Jiang, Jiang; Deangelis, Donald L

    2013-10-01

    An aim of community ecology is to understand the patterns of competing species assembly along environmental gradients. All species interact with their environments. However, theories of community assembly have seldom taken into account the effects of species that are able to engineer the environment. In this modeling study, we integrate the species' engineering trait together with processes of immigration and local dispersal into a theory of community assembly. We quantify the species' engineering trait as the degree to which it can move the local environment away from its baseline state towards the optimum state of the species (species-environment feedback). We find that, in the presence of immigration from a regional pool, strong feedback can increase local species richness; however, in the absence of continual immigration, species richness is a declining function of the strength of species-environment feedback. This shift from a negative effect of engineering strength on species richness to a positive effect, as immigration rate increases, is clearer when there is spatial heterogeneity in the form of a gradient in environmental conditions than when the environment is homogeneous or it is randomly heterogeneous. Increasing the scale over which local dispersal occurs can facilitate species richness when there is no species-environment feedback or when the feedback is weak. However, increases in the spatial scale of dispersal can reduce species richness when the species-environment feedback is strong. These results expand the theoretical basis for understanding the effects of the strength of species-environment feedback on community assembly.

  6. Facilitated patient experience feedback can improve nursing care: a pilot study for a phase III cluster randomised controlled trial

    PubMed Central

    2013-01-01

    Background England’s extensive NHS patient survey programme has not fulfilled government promises of widespread improvements in patients’ experiences, and media reports of poor nursing care in NHS hospitals are increasingly common. Impediments to the surveys’ impact on the quality of nursing care may include: the fact that they are not ward-specific, so nurses claim “that doesn’t happen on my ward”; nurses’ scepticism about the relevance of patient feedback to their practice; and lack of prompt communication of results. The surveys’ impact could be increased by: conducting ward-specific surveys; returning results to ward staff more quickly; including patients’ written comments in reports; and offering nurses an opportunity to discuss the feedback. Very few randomised trials have been conducted to test the effectiveness of patient feedback on quality improvement and there have been few, if any, published trials of ward-specific patient surveys. Methods Over two years, postal surveys of recent inpatients were conducted at four-monthly intervals in 18 wards in two NHS Trusts in England. Wards were randomly allocated to Basic Feedback (ward-specific printed patient survey results including patients’ written comments sent to nurses by letter); Feedback Plus (in addition to printed results, ward meetings to discuss results and plan improvements) or Control (no active feedback of survey results). Patient survey responses to questions about nursing care were used to compute wards’ average Nursing Care Scores at each interval. Nurses’ reactions to the patient feedback were recorded. Results Conducting ward-level surveys and delivering ward-specific results was feasible. Ward meetings were effective for engaging nurses and challenging scepticism and patients’ written comments stimulated interest. 4,236 (47%) patients returned questionnaires. Nursing Care Scores improved more for Feedback Plus than Basic Feedback or Control (difference between

  7. Towards an understanding of feedbacks between plant productivity, acidity and dissolved organic matter

    NASA Astrophysics Data System (ADS)

    Rowe, Ed; Tipping, Ed; Davies, Jessica; Monteith, Don; Evans, Chris

    2014-05-01

    The recent origin of much dissolved organic carbon (DOC) (Tipping et al., 2010) implies that plant productivity is a major control on DOC fluxes. However, the flocculation, sorption and release of potentially-dissolved organic matter are governed by pH, and widespread increases in DOC concentrations observed in northern temperate freshwater systems seem to be primarily related to recovery from acidification (Monteith et al., 2007). We explore the relative importance of changes in productivity and pH using a model, MADOC, that incorporates both these effects (Rowe et al., 2014). The feedback whereby DOC affects pH is included. The model uses an annual timestep and relatively simple flow-routing, yet reproduces observed changes in DOC flux and pH in experimental (Evans et al., 2012) and survey data. However, the first version of the model probably over-estimated responses of plant productivity to nitrogen (N) deposition in upland semi-natural ecosystems. There is a strong case that plant productivity is an important regulator of DOC fluxes, and theoretical reasons for suspecting widespread productivity increases in recent years due not only to N deposition but to temperature and increased atmospheric CO2 concentrations. However, evidence that productivity has increased in upland semi-natural ecosystems is sparse, and few studies have assessed the major limitations to productivity in these habitats. In systems where phosphorus (P) limitation prevails, or which are co-limited, productivity responses to anthropogenic drivers will be limited. We present a revised version of the model that incorporates P cycling and appears to represent productivity responses to atmospheric N pollution more realistically. Over the long term, relatively small fluxes of nutrient elements into and out of ecosystems can profoundly affect productivity and the accumulation of organic matter. Dissolved organic N (DON) is less easily intercepted by plants and microbes than mineral N, and DON

  8. 'Do you remember the first time?' Host plant preference in a moth is modulated by experiences during larval feeding and adult mating.

    PubMed

    Proffit, Magali; Khallaf, Mohammed A; Carrasco, David; Larsson, Mattias C; Anderson, Peter

    2015-04-01

    In insects, like in other animals, experience-based modulation of preference, a form of phenotypic plasticity, is common in heterogeneous environments. However, the role of multiple fitness-relevant experiences on insect preference remains largely unexplored. For the multivoltine polyphagous moth Spodoptera littoralis we investigated effects of larval and adult experiences on subsequent reproductive behaviours. We demonstrate, for the first time in male and female insects, that mating experience on a plant modulates plant preference in subsequent reproductive behaviours, whereas exposure to the plant alone or plant together with sex pheromone does not affect this preference. When including larval feeding experiences, we found that both larval rearing and adult mating experiences modulate host plant preference. These findings represent the first evidence that host plant preferences in polyphagous insects are determined by a combination of innate preferences modulated by sensory feedback triggered by multiple rewarding experiences throughout their lifetime.

  9. Online feedback assessments in physiology: effects on students' learning experiences and outcomes.

    PubMed

    Marden, Nicole Y; Ulman, Lesley G; Wilson, Fiona S; Velan, Gary M

    2013-06-01

    Online formative assessments have become increasingly popular; however, formal evidence supporting their educational benefits is limited. This study investigated the impact of online feedback quizzes on the learning experiences and outcomes of undergraduate students enrolled in an introductory physiology course. Four quiz models were tested, which differed in the amount of credit available, the number of attempts permitted, and whether the quizzes were invigilated or unsupervised, timed or untimed, or open or closed book. All quizzes were composed of multiple-choice questions and provided immediate individualized feedback. Summative end-of-course examination marks were analyzed with respect to performance in quizzes and were also compared with examination performance in the year before the quizzes were introduced. Online surveys were conducted to gather students' perceptions regarding the quizzes. The vast majority of students perceived online quizzes as a valuable learning tool. For all quiz models tested, there was a significant relationship between performance in quizzes and end-of-course examination scores. Importantly, students who performed poorly in quizzes were more likely to fail the examination, suggesting that formative online quizzes may be a useful tool to identify students in need of assistance. Of the four quiz models, only one quiz model was associated with a significant increase in mean examination performance. This model had the strongest formative focus, allowing multiple unsupervised and untimed attempts. This study suggests that the format of online formative assessments is critical in achieving the desired impact on student learning. Specifically, such assessments are most effective when they are low stakes.

  10. Operating experience feedback report -- turbine-generator overspeed protection systems: Commercial power reactors. Volume 11

    SciTech Connect

    Ornstein, H.L.

    1995-04-01

    This report presents the results of the US Nuclear Regulatory Commission`s Office for Analysis and Evaluation of Operational Data (AEOD) review of operating experience of main turbine-generator overspeed and overspeed protection systems. It includes an indepth examination of the turbine overspeed event which occurred on November 9, 1991, at the Salem Unit 2 Nuclear Power Plant. It also provides information concerning actions taken by other utilities and the turbine manufacturers as a result of the Salem overspeed event. AEOD`s study reviewed operating procedures and plant practices. It noted differences between turbine manufacturer designs and recommendations for operations, maintenance, and testing, and also identified significant variations in the manner that individual plants maintain and test their turbine overspeed protection systems. AEOD`s study provides insight into the shortcomings in the design, operation, maintenance, testing, and human factors associated with turbine overspeed protection systems. Operating experience indicates that the frequency of turbine overspeed events is higher than previously thought and that the bases for demonstrating compliance with NRC`s General Design Criterion (GDC) 4, Environmental and dynamic effects design bases, may be nonconservative with respect to the assumed frequency.

  11. Science Experience Unit: Plant and Animal Adaptations.

    ERIC Educational Resources Information Center

    Ferguson-Florissant School District, Ferguson, MO.

    GRADES OR AGES: No mention. Appears to be upper elementary. SUBJECT MATTER: Science units--plants and animals. ORGANIZATION AND PHYSICAL APPEARANCE: The guide is divided into 35 activities. It is mimeographed and staple-bound with a paper cover. OBJECTIVES AND ACTIVITIES: No objectives are mentioned. The activities suggested aim to recreate common…

  12. Plants and Magnetism: Experiments with Biomagnetism

    ERIC Educational Resources Information Center

    McCormack, Alan J.

    1972-01-01

    Phenomenon of effect of magnetic field on plant growth provides wide opportunities for research in classrooms. Using moderately powerful magnets, seed growth patterns can be observed in pre-germination treatment, germination period exposure and under many other conditions. Such research may enable understanding magnetotropism more clearly. (PS)

  13. A Moral Experience Feedback Loop: Modeling a System of Moral Self-Cultivation in Everyday Life

    ERIC Educational Resources Information Center

    Sherblom, Stephen A.

    2015-01-01

    This "systems thinking" model illustrates a common feedback loop by which people engage the moral world and continually reshape their moral sensibility. The model highlights seven processes that collectively form this feedback loop: beginning with (1) one's current moral sensibility which shapes processes of (2) perception, (3)…

  14. Can We Meet Their Expectations? Experiences and Perceptions of Feedback in First Year Undergraduate Students

    ERIC Educational Resources Information Center

    Robinson, Sarita; Pope, Debbie; Holyoak, Lynda

    2013-01-01

    Student ratings of satisfaction with feedback are consistently lower than other teaching and learning elements within the UK higher education sector. However, reasons for this dissatisfaction are often unclear to teaching staff, who believe their students are receiving timely, extensive and informative feedback. This study explores possible…

  15. Enhancing the Assessment Experience: Improving Student Perceptions, Engagement and Understanding Using Online Video Feedback

    ERIC Educational Resources Information Center

    West, John; Turner, Will

    2016-01-01

    Individualised video screencasts with accompanying narration were used to provide assessment feedback to a large number (n = 299) of first-year Bachelor of Education students at Edith Cowan University in Western Australia. An anonymous online survey revealed that nearly three times as many respondents (61%) preferred video feedback to written…

  16. Students' feedback of objectively structured clinical examination: a private medical college experience.

    PubMed

    Khursheed, Iram; Usman, Yaseen; Usman, Jawaid

    2007-03-01

    The aim of the study was to evaluate undergraduate students' perceptions regarding Objectively Structured Clinical Examination (OSCE) to be used as a feedback to improve the assessment technique. At the end of OSCE, students were provided with a feedback questionnaire related to OSCE to obtain their views and comments. The feedback was obtained from two consecutive batches of third year medical students and was utilized to incorporate the improvements in the process, wherever possible. A great majority of students (93% from group 'A' and 95% from group 'B') regarded OSCE as a practical and useful assessment tool in early years of medical education. In this study, students appreciated OSCE and offered constructive feedback on structure and organization of the process. However, at some stations they felt that instructions were ambiguous and time allocation was inadequate for the assigned tasks. The overall feedback was very useful and facilitated a critical review of the process.

  17. From the experience of plant innovators

    SciTech Connect

    Not Available

    1984-01-01

    Eight different innovations used in various plants to improve safety or efficiency of operations are described. These include the following : 1) an electrical signalling system to monitor the level of condensate in the primary gas-cooling devices, 2) an ignition device on each collector to prevent the occurrence of a fire on the pipes over the benzene section of the recovery house, 3) a modification in the design of the shaft that fastens the end rollers on the door cleaning devices, 4) an improved method for cleaning tank wagons to remove residues of the production of tar-treatment workshops to reduce the expenditure of manual labor, 5) a change in design of a vacuum pump, 6) use of the old frames of the Du25 valve at the Kirvoi Rog Coking Plant to prepare the sprayers to dephenolizing scrubbers, 7) coating the steel parts of the ventilation pump absorption system with a layer of glass cloth on cement consisting of liquid glass, diabase powder, and luosilicate of sodium to insure protection from corrosion by H/sub 2/SO/sub 4/ vapors, and 8) installation of a dephlegmator in recovery house no. 2 of the Kommunarsk Coking Plant. In most cases the economic advantage of the device is noted.

  18. Experience feedback committee in emergency medicine: a tool for security management

    PubMed Central

    Lecoanet, André; Sellier, Elodie; Carpentier, Françoise; Maignan, Maxime; Seigneurin, Arnaud; François, Patrice

    2014-01-01

    Objective Emergency departments are high-risk structures. The objective was to analyse the functioning of an experience feedback committee (EFC), a security management tool for the analysis of incidents in a medical department. Methods We conducted a descriptive study based on the analysis of the written documents produced by the EFC between November 2009 and May 2012. We performed a double analysis of all incident reports, meeting minutes and analysis reports. Results During the study period, there were 22 meetings attended by 15 professionals. 471 reported incidents were transmitted to the EFC. Most of them (95%) had no consequence for the patients. Only one reported incident led to the patient's death. 12 incidents were analysed thoroughly and the committee decided to set up 14 corrective actions, including eight guideline writing actions, two staff trainings, two resource materials provisions and two organisational changes. Conclusions The staff took part actively in the EFC. Following the analysis of incidents, the EFC was able to set up actions at the departmental level. Thus, an EFC seems to be an appropriate security management tool for an emergency department. PMID:23964063

  19. Controlled ecological life support system higher plant flight experiments

    NASA Technical Reports Server (NTRS)

    Tibbitts, T. W.; Wheeler, R. M.

    1984-01-01

    Requirements for spaceflight experments which involve higher plants were determined. The plants are studied for use in controlled ecological life support systems (CELSS). Two categories of research requirements are discussed: (1) the physical needs which include nutrient, water and gas exchange requirements; (2) the biological and physiological functions which affect plants in zero gravity environments. Physical problems studies are given the priority since they affect all biological experiments.

  20. Experiments with Corn To Demonstrate Plant Growth and Development.

    ERIC Educational Resources Information Center

    Haldeman, Janice H.; Gray, Margarit S.

    2000-01-01

    Explores using corn seeds to demonstrate plant growth and development. This experiment allows students to formulate hypotheses, observe and record information, and practice mathematics. Presents background information, materials, procedures, and observations. (SAH)

  1. Experience-dependent modulation of feedback integration during singing: role of the right anterior insula.

    PubMed

    Kleber, Boris; Zeitouni, Anthony G; Friberg, Anders; Zatorre, Robert J

    2013-04-03

    Somatosensation plays an important role in the motor control of vocal functions, yet its neural correlate and relation to vocal learning is not well understood. We used fMRI in 17 trained singers and 12 nonsingers to study the effects of vocal-fold anesthesia on the vocal-motor singing network as a function of singing expertise. Tasks required participants to sing musical target intervals under normal conditions and after anesthesia. At the behavioral level, anesthesia altered pitch accuracy in both groups, but singers were less affected than nonsingers, indicating an experience-dependent effect of the intervention. At the neural level, this difference was accompanied by distinct patterns of decreased activation in singers (cortical and subcortical sensory and motor areas) and nonsingers (subcortical motor areas only) respectively, suggesting that anesthesia affected the higher-level voluntary (explicit) motor and sensorimotor integration network more in experienced singers, and the lower-level (implicit) subcortical motor loops in nonsingers. The right anterior insular cortex (AIC) was identified as the principal area dissociating the effect of expertise as a function of anesthesia by three separate sources of evidence. First, it responded differently to anesthesia in singers (decreased activation) and nonsingers (increased activation). Second, functional connectivity between AIC and bilateral A1, M1, and S1 was reduced in singers but augmented in nonsingers. Third, increased BOLD activity in right AIC in singers was correlated with larger pitch deviation under anesthesia. We conclude that the right AIC and sensory-motor areas play a role in experience-dependent modulation of feedback integration for vocal motor control during singing.

  2. Evidence from numerical experiments for a feedback dynamo generating Mercury's magnetic field.

    PubMed

    Heyner, Daniel; Wicht, Johannes; Gómez-Pérez, Natalia; Schmitt, Dieter; Auster, Hans-Ulrich; Glassmeier, Karl-Heinz

    2011-12-23

    The observed weakness of Mercury's magnetic field poses a long-standing puzzle to dynamo theory. Using numerical dynamo simulations, we show that it could be explained by a negative feedback between the magnetospheric and the internal magnetic fields. Without feedback, a small internal field was amplified by the dynamo process up to Earth-like values. With feedback, the field strength saturated at a much lower level, compatible with the observations at Mercury. The classical saturation mechanism via the Lorentz force was replaced by the external field impact. The resulting surface field was dominated by uneven harmonic components. This will allow the feedback model to be distinguished from other models once a more accurate field model is constructed from MErcury Surface, Space ENvironment, GEochemistry, and Ranging (MESSENGER) and BepiColombo data.

  3. Experiences in optimizing water treatment plant performance

    SciTech Connect

    Hess, A.F.; Huntley, G.

    1996-11-01

    The South Central Connecticut Regional Water Authority (RWA) provides an average of 55 million gallons per day (mgd) to approximately 380,000 people in 12 municipalities in the Greater New Haven area of Connecticut. About 80 percent of the water is supplied from three surface water treatment plants and the other 20 percent comes from five wellfields. The surface water supply system includes 9 reservoirs with a total capacity of about 16 billion gallons. The Authority owns and controls approximately 40% of the 67 square miles of the watershed for these reservoirs. The source water quality is consistent and generally very good. A summary of average water for selected parameters which impact the treatability of the supplies is presented in Table 1.

  4. Plant Growth/Plant Phototropism - Skylab Student Experiment ED-61/62

    NASA Technical Reports Server (NTRS)

    1973-01-01

    This chart describes the Skylab student experiment ED-61, Plant Growth, and experiment ED-62, Plant Phototropism. Two similar proposals were submitted by Joel G. Wordekemper of West Point, Nebraska, and Donald W. Schlack of Downey, California. Wordekemper's experiment (ED-61) was to see how the lack of gravity would affect the growth of roots and stems of plants. Schlack's experiment (ED-62) was to study the effect of light on a seed developing in zero gravity. The growth container of the rice seeds for their experiment consisted of eight compartments arranged in two parallel rows of four. Each had two windowed surfaces to allow periodic photography of the developing seedlings. In March 1972, NASA and the National Science Teachers Association selected 25 experiment proposals for flight on Skylab. Science advisors from the Marshall Space Flight Center aided and assisted the students in developing the proposals for flight on Skylab.

  5. Enhancing water use efficiency with plant feedback irrigation control: The case for sorghum

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Grain sorghum (Sorghum bicolor Moench L.) is a well-adapted and widely grown grain crop in the U.S. Southern High Plains and other semi-arid regions. Sorghum has several advantages over corn (Zea mays L.) in this region. Sorghum planting dates are more flexible, making it easier to plant as a compan...

  6. What Type of Feedback Do Student Teachers Expect from Their School Mentors during Practicum Experience? The Case of Spanish EFL Student Teachers

    ERIC Educational Resources Information Center

    Martínez Agudo, Juan de Dios

    2016-01-01

    Mentorship represents a vital component in all teacher education programmes since mentors' feedback plays an essential role in shaping candidate teachers' professional identity. The quality of feedback provided by school mentors during the practicum experience constitutes the main focus of this study. This research paper aimed at investigating…

  7. Gamification and Smart Feedback: Experiences with a Primary School Level Math App

    ERIC Educational Resources Information Center

    Kickmeier-Rust, Michael D.; Hillemann, Eva-C.; Albert, Dietrich

    2014-01-01

    Gamification is a recent trend in the field of game-based learning that accounts for development effort, costs, and effectiveness concerns of games. Another trend in educational technology is learning analytics and formative feedback. In the context of a European project the developed a light weight tool for learning and practicing divisions named…

  8. "Tell Me What to Do" vs. "Guide Me through It": Feedback Experiences of International Doctoral Students

    ERIC Educational Resources Information Center

    Wang, Ting; Li, Linda Y.

    2011-01-01

    Despite increasing attention to the challenges of supervising international doctoral students, little research has been conducted to examine supervisory feedback practice with international students and its impact on the thesis writing process. This exploratory qualitative study seeks to fill the gap and contribute to understanding the feedback…

  9. Issues and Agency: Postgraduate Student and Tutor Experiences with Written Feedback

    ERIC Educational Resources Information Center

    Sanchez, Hugo Santiago; Dunworth, Katie

    2015-01-01

    This paper examines the issues which postgraduate students and tutors experienced as they engaged in receiving, providing and requesting feedback, as well as the strategies which they adopted as they sought resolution of these issues. The study employed a case study approach, using data obtained from semi-structured and stimulated recall…

  10. US nuclear power plant operating cost and experience summaries

    SciTech Connect

    Kohn, W.E.; Reid, R.L.; White, V.S.

    1998-02-01

    NUREG/CR-6577, U.S. Nuclear Power Plant Operating Cost and Experience Summaries, has been prepared to provide historical operating cost and experience information on U.S. commercial nuclear power plants. Cost incurred after initial construction are characterized as annual production costs, representing fuel and plant operating and maintenance expenses, and capital expenditures related to facility additions/modifications which are included in the plant capital asset base. As discussed in the report, annual data for these two cost categories were obtained from publicly available reports and must be accepted as having different degrees of accuracy and completeness. Treatment of inconclusive and incomplete data is discussed. As an aid to understanding the fluctuations in the cost histories, operating summaries for each nuclear unit are provided. The intent of these summaries is to identify important operating events; refueling, major maintenance, and other significant outages; operating milestones; and significant licensing or enforcement actions. Information used in the summaries is condensed from annual operating reports submitted by the licensees, plant histories contained in Nuclear Power Experience, trade press articles, and the Nuclear Regulatory Commission (NRC) web site (www.nrc.gov).

  11. Operating experience with a flexible cogeneration plant in Colorado

    SciTech Connect

    Wadman, B.

    1997-01-01

    Much has been written about the interesting gas turbine cogeneration Project in Fort Lupton, Colorado, U.S.A., as created and developed by the Thermo Cogeneration Partnership under the leadership of Paul Steinway, project general manager. The plant is based on five 40 MW-class gas turbine generator modules supplied by Stewart & Stevenson, who is also responsible for operation and maintenance of the plant through its operating arm, Stewart & Stevenson Operations, Inc. The plant, first placed into service in mid-1994 after only 18 months of construction, is of particular interest because it has to function with a wide degree of flexibility in load management, and it also uses one of the latest-design aeroderivative gas turbines, namely the GE LM6000. This article describes the plant design, equipment and operating experience thus far. 6 figs.

  12. Biogeochemical plant-soil microbe feedback in response to climate warming in peatlands

    NASA Astrophysics Data System (ADS)

    Bragazza, Luca; Parisod, Julien; Buttler, Alexandre; Bardgett, Richard D.

    2013-03-01

    Peatlands act as global sinks of atmospheric carbon (C) through the accumulation of organic matter, primarily made up of decay-resistant litter of peat mosses. However, climate warming has been shown to promote vascular plant growth in peatlands, especially ericaceous shrubs. A change in vegetation cover is in turn expected to modify above-ground/below-ground interactions, but the biogeochemical mechanisms involved remain unknown. Here, by selecting peatlands at different altitudes to simulate a natural gradient of soil temperature, we show that the expansion of ericaceous shrubs with warming is associated with an increase of polyphenol content in both plant litter and pore water. In turn, this retards the release of nitrogen (N) from decomposing litter, increases the amount of dissolved organic N and reduces N immobilization by soil microbes. A decrease of soil water content with increasing temperature promotes the growth of fungi, which feeds back positively on ericaceous shrubs by facilitating the symbiotic acquisition of dissolved organic N. We also observed a higher release of labile C from vascular plant roots at higher soil temperatures, which promotes the microbial investment in C-degrading enzymes. Our data suggest that climate-induced changes in plant cover can reduce the productivity of peat mosses and potentially prime the decomposition of organic matter by affecting the stoichiometry of soil enzymatic activity.

  13. Peatland plant communities under global change: negative feedback loops counteract shifts in species composition.

    PubMed

    Hedwall, Per-Ola; Brunet, Jörg; Rydin, Håkan

    2017-01-01

    Mires (bogs and fens) are nutrient-limited peatland ecosystems, the vegetation of which is especially sensitive to nitrogen deposition and climate change. The role of mires in the global carbon cycle, and the delivery of different ecosystem services can be considerably altered by changes in the vegetation, which has a strong impact on peat-formation and hydrology. Mire ecosystems are commonly open with limited canopy cover but both nitrogen deposition and increased temperatures may increase the woody vegetation component. It has been predicted that such an increase in tree cover and the associated effects on light and water regimes would cause a positive feed-back loop with respect to the ground vegetation. None of these effects, however, have so far been confirmed in large-scale spatiotemporal studies. Here we analyzed data pertaining to mire vegetation from the Swedish National Forest Inventory collected from permanent sample plots over a period of 20 yr along a latitudinal gradient covering 14°. We hypothesized that the changes would be larger in the southern parts as a result of higher nitrogen deposition and warmer climate. Our results showed an increase in woody vegetation with increases in most ericaceous dwarf-shrubs and in the basal area of trees. These changes were, in contrast to our expectations, evenly distributed over most of the latitudinal gradient. While nitrogen deposition is elevated in the south, the increase in temperatures during recent decades has been larger in the north. Hence, we suggest that different processes in the north and south have produced similar vegetation changes along the latitudinal gradient. There was, however, a sharp increase in compositional change at high deposition, indicating a threshold effect in the response. Instead of a positive feed-back loop caused by the tree layer, an increase in canopy cover reduced the changes in composition of the ground vegetation, whereas a decrease in canopy cover lead to larger changes

  14. Raccoon Mountain pumped-storage plant: Ten years operating experience

    SciTech Connect

    Adkins, F.E.

    1987-09-01

    Operational experience at the 1 530 MW Raccoon Mountain underground pumped-storage plant can be relevant to other large hydro facilities. A number of unusual features were incorporated and individual unit size was only recently overtaken elsewhere. Direct water cooling of rotor and stator winding has been successfully applied to salient pole machines. A number of problems, including difficulties with oil-filled 161 kV current transformers, and some mechanical aspects, are reported. Designed for remote supervisory control, the plant has required closer attention. Operating statistics are included.

  15. Root elongation against a constant force: experiment with a computerized feedback-controlled device

    NASA Technical Reports Server (NTRS)

    Kuzeja, P. S.; Lintilhac, P. M.; Wei, C.

    2001-01-01

    Axial force was applied to the root tip of corn (Zea mays L. cv. Merit) seedlings using a computerized, feedback-controlled mechanical device. The system's feedback capability allowed continuous control of a constant tip load, and the attached displacement transducer provided the time course of root elongation. Loads up to 7.5 g decreased the root elongation rate by 0.13 mm h-1 g-1, but loads 7.5 to 17.5 g decreased the growth rate by only 0.04 mm h-1 g-1. Loads higher than 18 g stopped root elongation completely. Measurement of the cross-sectional areas of the root tips indicated that the 18 g load had applied about 0.98 MPa of axial pressure to the root, thereby exceeding the root's ability to respond with increased turgor pressure. Recorded time-lapse images of loaded roots showed that radial thickening (swelling) occurred behind the root cap, whose cross-sectional area increased with tip load.

  16. Digital force-feedback for protein unfolding experiments using atomic force microscopy

    NASA Astrophysics Data System (ADS)

    Bippes, Christian A.; Janovjak, Harald; Kedrov, Alexej; Muller, Daniel J.

    2007-01-01

    Since its invention in the 1990s single-molecule force spectroscopy has been increasingly applied to study protein (un-)folding, cell adhesion, and ligand-receptor interactions. In most force spectroscopy studies, the cantilever of an atomic force microscope (AFM) is separated from a surface at a constant velocity, thus applying an increasing force to folded bio-molecules or bio-molecular bonds. Recently, Fernandez and co-workers introduced the so-called force-clamp technique. Single proteins were subjected to a defined constant force allowing their life times and life time distributions to be directly measured. Up to now, the force-clamping was performed by analogue PID controllers, which require complex additional hardware and might make it difficult to combine the force-feedback with other modes such as constant velocity. These points may be limiting the applicability and versatility of this technique. Here we present a simple, fast, and all-digital (software-based) PID controller that yields response times of a few milliseconds in combination with a commercial AFM. We demonstrate the performance of our feedback loop by force-clamp unfolding of single Ig27 domains of titin and the membrane proteins bacteriorhodopsin (BR) and the sodium/proton antiporter NhaA.

  17. Plant experience with temporary reverse osmosis makeup water systems

    SciTech Connect

    Polidoroff, C.

    1986-01-01

    Pacific Gas and Electric (PG and E) Company's Diablo Canyon Power Plant (DCPP), which is located on California's central coast, has access to three sources of raw water: creek water, well water, and seawater. Creek and well water are DCPP's primary sources of raw water; however, because their supply is limited, these sources are supplemented with seawater. The purpose of this paper is to discuss the temporary, rental, reverse osmosis systems used by PG and E to process DCPP's raw water into water suitable for plant makeup. This paper addresses the following issues: the selection of reverse osmosis over alternative water processing technologies; the decision to use vendor-operated temporary, rental, reverse osmosis equipment versus permanent PG and E-owned and -operated equipment; the performance of DCPP's rental reverse osmosis systems; and, the lessons learned from DCPP's reverse osmosis system rental experience that might be useful to other plants considering renting similar equipment.

  18. Warming experiments underpredict plant phenological responses to climate change.

    PubMed

    Wolkovich, E M; Cook, B I; Allen, J M; Crimmins, T M; Betancourt, J L; Travers, S E; Pau, S; Regetz, J; Davies, T J; Kraft, N J B; Ault, T R; Bolmgren, K; Mazer, S J; McCabe, G J; McGill, B J; Parmesan, C; Salamin, N; Schwartz, M D; Cleland, E E

    2012-05-02

    Warming experiments are increasingly relied on to estimate plant responses to global climate change. For experiments to provide meaningful predictions of future responses, they should reflect the empirical record of responses to temperature variability and recent warming, including advances in the timing of flowering and leafing. We compared phenology (the timing of recurring life history events) in observational studies and warming experiments spanning four continents and 1,634 plant species using a common measure of temperature sensitivity (change in days per degree Celsius). We show that warming experiments underpredict advances in the timing of flowering and leafing by 8.5-fold and 4.0-fold, respectively, compared with long-term observations. For species that were common to both study types, the experimental results did not match the observational data in sign or magnitude. The observational data also showed that species that flower earliest in the spring have the highest temperature sensitivities, but this trend was not reflected in the experimental data. These significant mismatches seem to be unrelated to the study length or to the degree of manipulated warming in experiments. The discrepancy between experiments and observations, however, could arise from complex interactions among multiple drivers in the observational data, or it could arise from remediable artefacts in the experiments that result in lower irradiance and drier soils, thus dampening the phenological responses to manipulated warming. Our results introduce uncertainty into ecosystem models that are informed solely by experiments and suggest that responses to climate change that are predicted using such models should be re-evaluated.

  19. Warming experiments underpredict plant phenological responses to climate change

    USGS Publications Warehouse

    Wolkovich, Elizabeth M.; Cook, Benjamin I.; Allen, Jenica M.; Crimmins, Theresa M.; Betancourt, Julio L.; Travers, Steven E.; Pau, Stephanie; Regetz, James; Davies, T. Jonathan; Kraft, Nathan J.B.; Ault, Toby R.; Bolmgren, Kjell; Mazer, Susan J.; McCabe, Gregory J.; McGill, Brian J.; Parmesan, Camille; Salamin, Nicolas; Schwartz, Mark D.; Cleland, Elsa E.

    2012-01-01

    Warming experiments are increasingly relied on to estimate plant responses to global climate change. For experiments to provide meaningful predictions of future responses, they should reflect the empirical record of responses to temperature variability and recent warming, including advances in the timing of flowering and leafing. We compared phenology (the timing of recurring life history events) in observational studies and warming experiments spanning four continents and 1,634 plant species using a common measure of temperature sensitivity (change in days per degree Celsius). We show that warming experiments underpredict advances in the timing of flowering and leafing by 8.5-fold and 4.0-fold, respectively, compared with long-term observations. For species that were common to both study types, the experimental results did not match the observational data in sign or magnitude. The observational data also showed that species that flower earliest in the spring have the highest temperature sensitivities, but this trend was not reflected in the experimental data. These significant mismatches seem to be unrelated to the study length or to the degree of manipulated warming in experiments. The discrepancy between experiments and observations, however, could arise from complex interactions among multiple drivers in the observational data, or it could arise from remediable artefacts in the experiments that result in lower irradiance and drier soils, thus dampening the phenological responses to manipulated warming. Our results introduce uncertainty into ecosystem models that are informed solely by experiments and suggest that responses to climate change that are predicted using such models should be re-evaluated.

  20. Warming Experiments Underpredict Plant Phenological Responses to Climate Change

    NASA Technical Reports Server (NTRS)

    Wolkovich, E. M.; Cook, B. I.; Allen, J. M.; Crimmins, T. M.; Betancourt, J. L.; Travers, S. E.; Pau, S.; Regetz, J.; Davies, T. J.; Kraft, N. J. B.; Ault, T. R.; Bolmgren, K.; Mazer, S. J.; McCabe, G. J.; McGill, B. J.; Parmesan, C.; Salamin, N.; Schwartz, M. D.; Cleland, E. E.

    2012-01-01

    Warming experiments are increasingly relied on to estimate plant responses to global climate change. For experiments to provide meaningful predictions of future responses, they should reflect the empirical record of responses to temperature variability and recent warming, including advances in the timing of flowering and leafing. We compared phenology (the timing of recurring life history events) in observational studies and warming experiments spanning four continents and 1,634 plant species using a common measure of temperature sensitivity (change in days per degree Celsius). We show that warming experiments underpredict advances in the timing of flowering and leafing by 8.5-fold and 4.0-fold, respectively, compared with long-term observations. For species that were common to both study types, the experimental results did not match the observational data in sign or magnitude. The observational data also showed that species that flower earliest in the spring have the highest temperature sensitivities, but this trend was not reflected in the experimental data. These significant mismatches seem to be unrelated to the study length or to the degree of manipulated warming in experiments. The discrepancy between experiments and observations, however, could arise from complex interactions among multiple drivers in the observational data, or it could arise from remediable artefacts in the experiments that result in lower irradiance and drier soils, thus dampening the phenological responses to manipulated warming. Our results introduce uncertainty into ecosystem models that are informed solely by experiments and suggest that responses to climate change that are predicted using such models should be re-evaluated.

  1. Developing Leaders via Experience: The Role of Developmental Challenge, Learning Orientation, and Feedback Availability

    ERIC Educational Resources Information Center

    DeRue, D. Scott; Wellman, Ned

    2009-01-01

    Prior research offers limited insight into the types of work experiences that promote leadership skill development and the ways that the person and context shape the developmental value of these experiences. In this article, the authors develop a series of hypotheses linking leadership skill development to features of the experience (developmental…

  2. Autogenic feedback training experiment: A preventative method for space motion sickness

    NASA Technical Reports Server (NTRS)

    Cowings, Patricia S.

    1993-01-01

    Space motion sickness is a disorder which produces symptoms similar to those of motion sickness on Earth. This syndrome has affected approximately 50 percent of all astronauts and cosmonauts exposed to microgravity in space, but it differs from what is commonly known as motion sickness in a number of critical ways. There is currently no ground-based method for predicting susceptibility to motion sickness in space. Antimotion sickness drugs have had limited success in preventing or counteracting symptoms in space, and frequently caused debilitating side effects. The objectives were: (1) to evaluate the effectiveness of Autogenic-Feedback Training as a countermeasure for space motion sickness; (2) to compare physiological data and in-flight symptom reports to ground-based motion sickness data; and (3) to predict susceptibility to space motion sickness based on pre-flight data of each treatment group crew member.

  3. Control of birhythmicity through conjugate self-feedback: Theory and experiment.

    PubMed

    Biswas, Debabrata; Banerjee, Tanmoy; Kurths, Jürgen

    2016-10-01

    Birhythmicity arises in several physical, biological, and chemical systems. Although many control schemes have been proposed for various forms of multistability, only a few exist for controlling birhythmicity. In this paper we investigate the control of birhythmic oscillation by introducing a self-feedback mechanism that incorporates the variable to be controlled and its canonical conjugate. Using a detailed analytical treatment, bifurcation analysis, and experimental demonstrations, we establish that the proposed technique is capable of eliminating birhythmicity and generates monorhythmic oscillation. Further, the detailed parameter space study reveals that, apart from monorhythmicity, the system shows a transition between birhythmicity and other dynamical forms of bistability. This study may have practical applications in controlling birhythmic behavior of several systems, in particular in biochemical and mechanical processes.

  4. Decoupling gain and feedback in coherent random lasers: experiments and simulations.

    PubMed

    Consoli, Antonio; López, Cefe

    2015-11-18

    We propose and demonstrate a coherent random laser in which the randomly distributed scattering centres are placed outside the active region. This architecture is implemented by enclosing a dye solution between two agglomerations of randomly positioned titanium dioxide nanoparticles. The same spectral signature, consisting of sharp spikes with random spectral positions, is detected emerging from both ensembles of titanium dioxide nanoparticles. We interpret this newly observed behaviour as due to the optical feedback given by back-scattered light from the scattering agglomerations, which also act as output couplers. A simple model is presented to simulate the observed behaviour, considering the amplitude and phase round trip conditions that must be satisfied to sustain lasing action. Numerical simulations reproduce the experimental reports, validating our simple model. The presented results suggest a new theoretical and experimental approach for studying the complex behavior of coherent random lasers and stimulate the realization of new devices based on the proposed architecture, with different active and scattering materials.

  5. Decoupling gain and feedback in coherent random lasers: experiments and simulations

    NASA Astrophysics Data System (ADS)

    Consoli, Antonio; López, Cefe

    2015-11-01

    We propose and demonstrate a coherent random laser in which the randomly distributed scattering centres are placed outside the active region. This architecture is implemented by enclosing a dye solution between two agglomerations of randomly positioned titanium dioxide nanoparticles. The same spectral signature, consisting of sharp spikes with random spectral positions, is detected emerging from both ensembles of titanium dioxide nanoparticles. We interpret this newly observed behaviour as due to the optical feedback given by back-scattered light from the scattering agglomerations, which also act as output couplers. A simple model is presented to simulate the observed behaviour, considering the amplitude and phase round trip conditions that must be satisfied to sustain lasing action. Numerical simulations reproduce the experimental reports, validating our simple model. The presented results suggest a new theoretical and experimental approach for studying the complex behavior of coherent random lasers and stimulate the realization of new devices based on the proposed architecture, with different active and scattering materials.

  6. Audio Feedback -- Better Feedback?

    ERIC Educational Resources Information Center

    Voelkel, Susanne; Mello, Luciane V.

    2014-01-01

    National Student Survey (NSS) results show that many students are dissatisfied with the amount and quality of feedback they get for their work. This study reports on two case studies in which we tried to address these issues by introducing audio feedback to one undergraduate (UG) and one postgraduate (PG) class, respectively. In case study one…

  7. Operations of a spaceflight experiment to investigate plant tropisms

    NASA Astrophysics Data System (ADS)

    Kiss, John Z.; Kumar, Prem; Millar, Katherine D. L.; Edelmann, Richard E.; Correll, Melanie J.

    2009-10-01

    Plants will be an important component in bioregenerative systems for long-term missions to the Moon and Mars. Since gravity is reduced both on the Moon and Mars, studies that identify the basic mechanisms of plant growth and development in altered gravity are required to ensure successful plant production on these space colonization missions. To address these issues, we have developed a project on the International Space Station (ISS) to study the interaction between gravitropism and phototropism in Arabidopsis thaliana. These experiments were termed TROPI (for tropisms) and were performed on the European Modular Cultivation System (EMCS) in 2006. In this paper, we provide an operational summary of TROPI and preliminary results on studies of tropistic curvature of seedlings grown in space. Seed germination in TROPI was lower compared to previous space experiments, and this was likely due to extended storage in hardware for up to 8 months. Video downlinks provided an important quality check on the automated experimental time line that also was monitored with telemetry. Good quality images of seedlings were obtained, but the use of analog video tapes resulted in delays in image processing and analysis procedures. Seedlings that germinated exhibited robust phototropic curvature. Frozen plant samples were returned on three space shuttle missions, and improvements in cold stowage and handing procedures in the second and third missions resulted in quality RNA extracted from the seedlings that was used in subsequent microarray analyses. While the TROPI experiment had technical and logistical difficulties, most of the procedures worked well due to refinement during the project.

  8. Light and Plants. A Series of Experiments Demonstrating Light Effects on Seed Germination, Plant Growth, and Plant Development.

    ERIC Educational Resources Information Center

    Downs, R. J.; And Others

    A brief summary of the effects of light on plant germination, growth and development, including photoperiodism and pigment formation, introduces 18 experiments and demonstrations which illustrate aspects of these effects. Detailed procedures for each exercise are given, the expected results outlined, and possible sources of difficulty discussed.…

  9. The Mars Plant Growth Experiment and Implications for Planetary Protection

    NASA Astrophysics Data System (ADS)

    Smith, Heather

    Plants are the ultimate and necessary solution for O2 production at a human base on Mars. Currently it is unknown if seeds can germinate on the Martian surface. The Mars Plant growth experiment (MPX) is a proposal for the first step in the development of a plant- based O2 production system by demonstrating plant germination and growth on the Martian surface. There is currently no planetary protection policy in place that covers plants on the Martian surface. We describe a planetary protection plan in compliance with NASA and COSPAR policy for a closed plant growth chamber on a Mars rover. We divide the plant growth chamber into two categories for planetary protection, the Outside: the outside of the chamber exposed to the Martian environment, and the Inside: the inside of the chamber which is sealed off from Mars atmosphere and contains the plant seeds and ancillary components for seed growth. We will treat outside surfaces of the chamber as other outside surfaces on the rover, wiped with a mixture of isopropyl alcohol and water as per Category IVb planetary protection requirements. All internal components of the MPX except the seeds and camera (including the water system, the plant growth stage and interior surface walls) will be sterilized by autoclave and subjected to sterilizing dry heat at a temperature of 125°C at an absolute humidity corresponding to a relative humidity of less than 25 percent referenced to the standard conditions of 0°C and 760 torr pressure. The seeds and internal compartments of the MPX in contact with the growth media will be assembled and tested to be free of viable microbes. MPX, once assembled, cannot survive Dry Heat Microbial Reduction. The camera with the radiation and CO2 sensors will be sealed in their own container and vented through HEPA filters. The seeds will be vernalized (microbe free) as per current Space Station methods described by Paul et al. 2001. Documentation of the lack of viable microbes on representative seeds

  10. Design of feedback control systems for stable plants with saturating actuators

    NASA Technical Reports Server (NTRS)

    Kapasouris, Petros; Athans, Michael; Stein, Gunter

    1988-01-01

    A systematic control design methodology is introduced for multi-input/multi-output stable open loop plants with multiple saturations. This new methodology is a substantial improvement over previous heuristic single-input/single-output approaches. The idea is to introduce a supervisor loop so that when the references and/or disturbances are sufficiently small, the control system operates linearly as designed. For signals large enough to cause saturations, the control law is modified in such a way as to ensure stability and to preserve, to the extent possible, the behavior of the linear control design. Key benefits of the methodology are: the modified compensator never produces saturating control signals, integrators and/or slow dynamics in the compensator never windup, the directional properties of the controls are maintained, and the closed loop system has certain guaranteed stability properties. The advantages of the new design methodology are illustrated in the simulation of an academic example and the simulation of the multivariable longitudinal control of a modified model of the F-8 aircraft.

  11. Design of feedback control systems for stable plants with saturating actuators

    NASA Technical Reports Server (NTRS)

    Kapasouris, Petros; Athans, Michael; Stein, Gunther

    1988-01-01

    A systematic control design methodology is introduced for multi-input/multi-output stable open-loop plants with multiple saturations. This new methodology is a substantial improvement over previous heuristic single-input/single-output approaches. The idea is to introduce a supervisor loop so that when the references and/or disturbances are sufficiently small, the control system operates linearly as designed. For signals large enough to cause saturations, the control law is modified in such a way as to ensure stability and to preserve, to the extent possible, the behavior of the linear control design. Key benefits of this methodology are: the modified compensator never produces saturating control signals, integrators and/or slow dynamics in the compensator never windup, the directional properties of the controls are maintained, and the closed-loop system has certain guaranteed stability properties. The advantages of the new design methodology are illustrated in the simulation of an academic example and the simulation of the multivariable longitudinal control of a modified model of the F-8 aircraft.

  12. A bHLH-Based Feedback Loop Restricts Vascular Cell Proliferation in Plants.

    PubMed

    Vera-Sirera, Francisco; De Rybel, Bert; Úrbez, Cristina; Kouklas, Evangelos; Pesquera, Marta; Álvarez-Mahecha, Juan Camilo; Minguet, Eugenio G; Tuominen, Hannele; Carbonell, Juan; Borst, Jan Willem; Weijers, Dolf; Blázquez, Miguel A

    2015-11-23

    Control of tissue dimensions in multicellular organisms requires the precise quantitative regulation of mitotic activity. In plants, where cells are immobile, tissue size is achieved through control of both cell division orientation and mitotic rate. The bHLH transcription factor heterodimer formed by target of monopteros5 (TMO5) and lonesome highway (LHW) is a central regulator of vascular width-increasing divisions. An important unanswered question is how its activity is limited to specify vascular tissue dimensions. Here we identify a regulatory network that restricts TMO5/LHW activity. We show that thermospermine synthase ACAULIS5 antagonizes TMO5/LHW activity by promoting the accumulation of SAC51-LIKE (SACL) bHLH transcription factors. SACL proteins heterodimerize with LHW-therefore likely competing with TMO5/LHW interactions-prevent activation of TMO5/LHW target genes, and suppress the over-proliferation caused by excess TMO5/LHW activity. These findings connect two thus-far disparate pathways and provide a mechanistic understanding of the quantitative control of vascular tissue growth.

  13. Healthcare professional and patient codesign and validation of a mechanism for service users to feedback patient safety experiences following a care transfer: a qualitative study

    PubMed Central

    Scott, Jason; Heavey, Emily; Waring, Justin; Jones, Diana; Dawson, Pamela

    2016-01-01

    Objective To develop and validate a mechanism for patients to provide feedback on safety experiences following a care transfer between organisations. Design Qualitative study using participatory methods (codesign workshops) and cognitive interviews. Workshop data were analysed concurrently with participants, and cognitive interviews were thematically analysed using a deductive approach based on the developed feedback mechanism. Participants Expert patients (n=5) and healthcare professionals (n=11) were recruited purposively to develop the feedback mechanism in 2 workshops. Workshop 1 explored principles underpinning safety feedback mechanisms, and workshop 2 included the practical development of the feedback mechanism. Final design and content of the feedback mechanism (a safety survey) were verified by workshop participants, and cognitive interviews (n=28) were conducted with patients. Results Workshop participants identified that safety feedback mechanisms should be patient-centred, short and concise with clear signposting on how to complete, with an option to be anonymous and balanced between positive (safe) and negative (unsafe) experiences. The agreed feedback mechanism consisted of a survey split across 3 stages of the care transfer: departure, journey and arrival. Care across organisational boundaries was recognised as being complex, with healthcare professionals acknowledging the difficulty implementing changes that impact other organisations. Cognitive interview participants agreed the content of the survey was relevant but identified barriers to completion relating to the survey formatting and understanding of a care transfer. Conclusions Participatory, codesign principles helped overcome differences in understandings of safety in the complex setting of care transfers when developing a safety survey. Practical barriers to the survey's usability and acceptability to patients were identified, resulting in a modified survey design. Further research is

  14. Decoupling gain and feedback in coherent random lasers: experiments and simulations

    PubMed Central

    Consoli, Antonio; López, Cefe

    2015-01-01

    We propose and demonstrate a coherent random laser in which the randomly distributed scattering centres are placed outside the active region. This architecture is implemented by enclosing a dye solution between two agglomerations of randomly positioned titanium dioxide nanoparticles. The same spectral signature, consisting of sharp spikes with random spectral positions, is detected emerging from both ensembles of titanium dioxide nanoparticles. We interpret this newly observed behaviour as due to the optical feedback given by back-scattered light from the scattering agglomerations, which also act as output couplers. A simple model is presented to simulate the observed behaviour, considering the amplitude and phase round trip conditions that must be satisfied to sustain lasing action. Numerical simulations reproduce the experimental reports, validating our simple model. The presented results suggest a new theoretical and experimental approach for studying the complex behavior of coherent random lasers and stimulate the realization of new devices based on the proposed architecture, with different active and scattering materials. PMID:26577668

  15. Predictable 'meta-mechanisms' emerge from feedbacks between transpiration and plant growth and cannot be simply deduced from short-term mechanisms.

    PubMed

    Tardieu, François; Parent, Boris

    2016-08-29

    Growth under water deficit is controlled by short-term mechanisms but, because of numerous feedbacks, the combination of these mechanisms over time often results in outputs that cannot be deduced from the simple inspection of individual mechanisms. It can be analysed with dynamic models in which causal relationships between variables are considered at each time-step, allowing calculation of outputs that are routed back to inputs for the next time-step and that can change the system itself. We first review physiological mechanisms involved in seven feedbacks of transpiration on plant growth, involving changes in tissue hydraulic conductance, stomatal conductance, plant architecture and underlying factors such as hormones or aquaporins. The combination of these mechanisms over time can result in non-straightforward conclusions as shown by examples of simulation outputs: 'over production of abscisic acid (ABA) can cause a lower concentration of ABA in the xylem sap ', 'decreasing root hydraulic conductance when evaporative demand is maximum can improve plant performance' and 'rapid root growth can decrease yield'. Systems of equations simulating feedbacks over numerous time-steps result in logical and reproducible emergent properties that can be viewed as 'meta-mechanisms' at plant level, which have similar roles as mechanisms at cell level.

  16. Experience from the 300 MWe CFB Demontration Plant in China

    NASA Astrophysics Data System (ADS)

    Gauvillé, P.; Semedard, J.-C.; Darling, S.

    This paper will describe the background and current status of the 300MWe CFB Demonstration Project located at the Baima Power Plant in Sichuan Province. This project was the first 300MWe class CFB in China and the first project built under the Transfer of Technology from Alstom. The plant entered commercial operation in early 2006. The fuel is a high-ash anthracite which has presented significant challenges in terms of higher-than-expected ash content and top size. While this fuel has been problematic for the adjacent suspension-fired boilers, performance in the CFB boiler has been excellent, with low carbon content in the ash, low turndown and low emissions. Key boiler performance parameters will be described along with a comparison of design and actual performance and the operational experience will be addressed. Finally, the paper will describe Alstom's process for scaling the CFB technology from 300MWe to 600MWe, and our supercritical CFB design.

  17. Relatedness is a poor predictor of negative plant–soil feedbacks

    PubMed Central

    Mehrabi, Zia; Tuck, Sean L

    2015-01-01

    Understanding the mechanisms underlying negative plant–soil feedbacks remains a critical challenge in plant ecology. If closely related species are more similar, then phylogeny could be used as a predictor for plant species interactions, simplifying our understanding of how plant–soil feedbacks structure plant communities, underlie invasive species dynamics, or reduce agricultural productivity. Here, we test the utility of phylogeny for predicting plant–soil feedbacks by undertaking a hierarchical Bayesian meta-analysis on all available pairwise plant–soil feedback experiments conducted over the last two decades, including 133 plant species in 329 pairwise interactions. We found that the sign and magnitude of plant–soil feedback effects were not explained by the phylogenetic distance separating interacting species. This result was consistent across different life forms, life cycles, provenances, and phylogenetic scales. Our analysis shows that, contrary to widespread assumption, relatedness is a poor predictor of plant–soil feedback effects. PMID:25557183

  18. Influence of student-designed experiments with fast plants on their understanding of plants and of scientific inquiry

    NASA Astrophysics Data System (ADS)

    Akey, Ann Kosek

    2000-10-01

    This dissertation investigates the influence of student designed experiments with Fast Plants in an undergraduate agroecology course on the students' conceptual understanding of plant life cycles and on their procedural understanding of scientific experimentation. It also considers students' perspectives on the value of these experiences. Data sources included semi-structured interviews with students and the instructor, a written task, course evaluations, and observations of class meetings. Students came into the course having strong practical experience with plants from their agricultural backgrounds. Students did not always connect aspects of plant biology that they studied in class, particularly respiration and photosynthesis, to plant growth requirements. The instructor was able to bridge the gap between some practical knowledge and textbook knowledge with experiences other than the Fast Plant project. Most students held an incomplete picture of plant reproduction that was complicated by differences between agricultural and scientific vocabulary. There is need for teaching approaches that help students tie together their knowledge of plants into a cohesive framework. Experiences that help students draw on their background knowledge related to plants, and which give students the opportunity to examine and discuss their ideas, may help students make more meaningful connections. The Fast Plant project, a positive experience for most students, was seen by these undergraduate students as being more helpful in learning about scientific experimentation than about plants. The process of designing and carrying out their own experiments gave students insight into experimentation, provoked their curiosity, and resulted in a sense of ownership and accomplishment.

  19. Collaborative design and use of an agency feedback form for student clinical practicum experience in community/public health nursing.

    PubMed

    Reilly, Janet Resop; Collier, Jill; Edelstein, Janice; Vandenhouten, Chris; Hovarter, Rebecca; Hansen, Judith M; Stewart, Stephanie; Turner, Mary Jo

    2012-01-01

    Evaluation of students in community and public health (C/PH) nursing clinical practica is a challenge, especially when preceptors are expected to evaluate students from different academic nursing programs. The need for a standardized student evaluation tool was identified during federally funded collaborative meetings held between C/PH academic and practice partners in Northeastern Wisconsin. This article focuses on the development and appraisal of the standardized Agency Feedback Form (AFF) for Student Practicum Experience in Community/Public Health Nursing, which was designed to meet the identified need. Four baccalaureate nursing programs implemented the AFF for 3 purposes: (1) to provide a consistent and easy evaluation form for preceptors to complete; (2) to communicate useful information about students' individual professional behaviors observed during practicum; and (3) to increase students' and preceptors' understanding of the population-based nursing interventions, using the Public Health Intervention Wheel. Future uses and implications of the AFF are also discussed.

  20. Aspects of experimental design for plant metabolomics experiments and guidelines for growth of plant material.

    PubMed

    Gibon, Yves; Rolin, Dominique

    2012-01-01

    Experiments involve the deliberate variation of one or more factors in order to provoke responses, the identification of which then provides the first step towards functional knowledge. Because environmental, biological, and/or technical noise is unavoidable, biological experiments usually need to be designed. Thus, once the major sources of experimental noise have been identified, individual samples can be grouped, randomised, and/or pooled. Like other 'omics approaches, metabolomics is characterised by the numbers of analytes largely exceeding sample number. While this unprecedented singularity in biology dramatically increases false discovery, experimental error can nevertheless be decreased in plant metabolomics experiments. For this, each step from plant cultivation to data acquisition needs to be evaluated in order to identify the major sources of error and then an appropriate design can be produced, as with any other experimental approach. The choice of technology, the time at which tissues are harvested, and the way metabolism is quenched also need to be taken into consideration, as they decide which metabolites can be studied. A further recommendation is to document data and metadata in a machine readable way. The latter should also describe every aspect of the experiment. This should provide valuable hints for future experimental design and ultimately give metabolomic data a second life. To facilitate the identification of critical steps, a list of items to be considered before embarking on time-consuming and costly metabolomic experiments is proposed.

  1. Radiobiological experiments with plant seeds aboard the biosatellite Cosmos 1887

    NASA Technical Reports Server (NTRS)

    Benton, E. V.; Anikeeva, I. D.; Akatov, Yu. A.; Vaulina, E. N.; Kostina, L. N.; Marenny, A.; Portman, A. I.; Rusin, S. V.

    1995-01-01

    The effects of spaceflight factors on the seeds of Arabidopsis thaliana and Crepis capillaris were studied. The seeds were located inside the satellite in an open space, protected with aluminum foil and also exposed without the foil cover. When the seeds were in open space without any protection, their viability was found to be suppressed; the survival rate and fertility of plants grown from these seeds were also diminished. An increase in the frequency of chromosome aberrations (CA) and in the number of multiple injuries was registered in this case. Experiments with the aluminum foil shielding showed a decrease in the suppression of the seeds' viability, but mutational changes were found to be even more increased, while the survival rate and fertility of the plants decreased. An increase in the thickness of shielding resulted in a decrease in the effects up to the level of the control, except for the effects connected with CA and fertility of the plants. Analysis of the results shows that these impairments can be ascribed to the action of single heavy charged particles (HCP). The seeds can thus be regarded as an integral biological 'dosimeter' which allows estimation of the total effects of radiation, ecological and biological factors.

  2. Radiobiological experiments with plant seeds aboard the biosatellite Cosmos 1887

    SciTech Connect

    Benton, E.V.; Anikeeva, I.D.; Akatov, Yu.A.; Vaulina, E.N.; Kostina, L.N.; Marenny, A.; Portman, A.I.; Rusin, S.V. ||

    1995-03-01

    The effects of spaceflight factors on the seeds of Arabidopsis thaliana and Crepis capillaris were studied. The seeds were located inside the satellite in an open space, protected with aluminum foil and also exposed without the foil cover. When the seeds were in open space without any protection, their viability was found to be suppressed; the survival rate and fertility of plants grown from these seeds were also diminished. An increase in the frequency of chromosome aberrations (CA) and in the number of multiple injuries was registered in this case. Experiments with the aluminum foil shielding showed a decrease in the suppression of the seeds` viability, but mutational changes were found to be even more increased, while the survival rate and fertility of the plants decreased. An increase in the thickness of shielding resulted in a decrease in the effects up to the level of the control, except for the effects connected with CA and fertility of the plants. Analysis of the results shows that these impairments can be ascribed to the action of single heavy charged particles (HCP). The seeds can thus be regarded as an integral biological `dosimeter` which allows estimation of the total effects of radiation, ecological and biological factors.

  3. Radiobiological experiments with plant seeds aboard the biosatellite Kosmos 1887.

    PubMed

    Anikeeva, I D; Akatov YuA; Vaulina, E N; Kostina, L N; Marenny, A M; Portman, A I; Rusin, S V; Benton, E V

    1990-01-01

    The effects of spaceflight factors on the seeds of Arabidopsis thaliana and Crepis capillaris were studied provided with various protective measures: the seeds were located inside the satellite and in open space, protected with aluminium foil and also exposed without the foil cover. When the seeds were in open space without any protection, their viability was found to be suppressed; the survival rate and fertility of plants grown from these seeds were also diminished. An increase in the frequency of chromosome aberrations (CA) and in the number of multiple injuries was registered in this case. Experiments with the aluminium foil shielding showed a decrease in the suppression of the seeds' viability, but mutational changes were found to be even more increased, while the survival and fertility of the plants decreased. An increase in the thickness of shielding resulted in a decrease in the effects up to the level of the control, except for the effects connected with CA and fertility of the plants. Analysis of the results shows that these impairments can be ascribed to the action of single heavy charged particles (HCP). The seeds can be thus regarded as an integral biological 'dosimeter' which allows estimation of the total effects of radiation, ecological and biological factors.

  4. Radiobiological experiments with plant seeds aboard the biosatellite Kosmos 1887

    NASA Technical Reports Server (NTRS)

    Anikeeva, I. D.; Vaulina, E. N.; Kostina, L. N.; Marenny, A. M.; Portman, A. I.; Rusin, S. V.; Benton, E. V.

    1990-01-01

    The effects of spaceflight factors on the seeds of Arabidopsis thaliana and Crepis capillaris were studied provided with various protective measures: the seeds were located inside the satellite and in open space, protected with aluminium foil and also exposed without the foil cover. When the seeds were in open space without any protection, their viability was found to be suppressed; the survival rate and fertility of plants grown from these seeds were also diminished. An increase in the frequency of chromosome aberrations (CA) and in the number of multiple injuries was registered in this case. Experiments with the aluminium foil shielding showed a decrease in the suppression of the seeds' viability, but mutational changes were found to be even more increased, while the survival and fertility of the plants decreased. An increase in the thickness of shielding resulted in a decrease in the effects up to the level of the control, except for the effects connected with CA and fertility of the plants. Analysis of the results shows that these impairments can be ascribed to the action of single heavy charged particles (HCP). The seeds can be thus regarded as an integral biological 'dosimeter' which allows estimation of the total effects of radiation, ecological and biological factors.

  5. Investigating a Nigerian XXL-Cohort Wiki-Learning Experience: Observation, Feedback and Reflection

    ERIC Educational Resources Information Center

    Aborisade, Peter

    2009-01-01

    A regular feature of the Nigerian tertiary education context is large numbers of students crammed into small classrooms or lecture theatres. This context had long begged for the creation of innovative learning spaces and adoption of engaging pedagogies. Recourse to technology support and experimenting with the WIKI as a learning tool at the…

  6. Altering Misperception of Sleep in Insomnia: Behavioral Experiment Versus Verbal Feedback

    ERIC Educational Resources Information Center

    Tang, Nicole K. Y.; Harvey, Allison G.

    2006-01-01

    Forty-eight individuals with insomnia were asked to wear an actigraph and keep a sleep diary for 2 nights. On the following day, half were shown the discrepancy between the data recorded on the actigraph and their sleep diary via a behavioral experiment, whereas the other half were told of the discrepancy verbally. Participants were then asked to…

  7. Time-delayed feedback control of coherence resonance near subcritical Hopf bifurcation: Theory versus experiment

    SciTech Connect

    Semenov, Vladimir; Feoktistov, Alexey; Vadivasova, Tatyana; Schöll, Eckehard Zakharova, Anna

    2015-03-15

    Using the model of a generalized Van der Pol oscillator in the regime of subcritical Hopf bifurcation, we investigate the influence of time delay on noise-induced oscillations. It is shown that for appropriate choices of time delay, either suppression or enhancement of coherence resonance can be achieved. Analytical calculations are combined with numerical simulations and experiments on an electronic circuit.

  8. EDF Nuclear Power Plants Operating Experience with MOX fuel

    SciTech Connect

    Thibault, Xavier

    2006-07-01

    EDF started Plutonium recycling in PWR in 1987 and progressively all the 20 reactors, licensed in using MOX fuel, have been loaded with MOX assemblies. At the origin of MOX introduction, these plants operated at full power in base load and the core management limited the irradiation time of MOX fuel assemblies to 3 annual cycles. Since 1995 all these reactors can operate in load follow mode. Since that time, a large amount of experience has been accumulated. This experience is very positive considering: - Receipt, handling, in core behaviour, pool storage and shipment of MOX fuel; - Operation of the various systems of the plant; - Environment impact; - Radioprotection; - Safety file requirements; - Availability for the grid. In order to reduce the fuel cost and to reach a better adequacy between UO{sub 2} fuel reprocessing flow and plutonium consumption, EDF had decided to improve the core management of MOX plants. This new core management call 'MOX Parity' achieves parity for MOX and UO{sub 2} assemblies in term of discharge burn-up. Compared to the current MOX assembly the Plutonium content is increased from 7,08% to 8,65% (equivalent to natural uranium enriched to respectively 3,25% and 3,7%) and the maximum MOX assembly burn-up moves from 42 to 52 GWd/t. This amount of burn-up is obtained from loading MOX assemblies for one additional annual cycle. Some, but limited, adaptations of the plant are necessary. In addition a new MOX fuel assembly has been designed to comply with the safety criteria taking into account the core management performances. These design improvements are based on the results of an important R and D program including numerous experimental tests and post-irradiated fuel examinations. In particular, envelope conditions compared to MOX Parity neutronic solicitations has been extensively investigated in order to get a full knowledge of the in reactor fuel behavior. Moreover, the operating conditions of the plant have been evaluated in many

  9. Spacelab 3 flight experiment No. 3AFT23: Autogenic-feedback training as a preventive method for space adaptation syndrome

    NASA Technical Reports Server (NTRS)

    Cowings, Patricia S.; Toscano, William B.; Kamiya, Joe; Miller, Neal E.; Sharp, Joseph C.

    1988-01-01

    Space adaptation syndrome is a motion sickness-like disorder which affects up to 50 percent of all people exposed to microgravity in space. This experiment tested a physiological conditioning procedure (Autogenic-Feedback Training, AFT) as an alternative to pharmacological management. Four astronauts participated as subjects in this experiment. Crewmembers A and B served as treatment subjects. Both received preflight training for control of heart rate, respiration rate, peripheral blood volume, and skin conductance. Crewmembers C and D served as controls (i.e., did not receive training). Crewmember A showed reliable control of his own physiological responses, and a significant increase in motion sickness tolerance after training. Crewmember B, however, demonstrated much less control and only a moderate increase in motion sickness tolerance was observed after training. The inflight symptom reports and physiological data recordings revealed that Crewmember A did not experience any severe symptom episodes during the mission, while Crewmember B reported one severe symptom episode. Both control group subjects, C and D (who took antimotion sickness medication), reported multiple symptom episodes on mission day 0. Both inflight data and crew reports indicate that AFT may be an effective countermeasure. Additional data must be obtained inflight (a total of eight treatment and eight control subjects) before final evaluation of this treatment can be made.

  10. Study to develop an inspection, maintenance, and repair plan for OTEC (Ocean Thermal Energy Conversion) modular experiment plants. Final report

    SciTech Connect

    Not Available

    1980-04-01

    The inspection, maintenance and repair (IM and R) of the Ocean Thermal Energy Conversion (OTEC) Modular Experiment Plant (Pilot Plant) have been studied in two phases: Task I and Task II. Task I phase developed IM and R identification forms, identified requirements for routine and post casualty IM and R, and categorized and outlined potential procedures to perform IM and R activities. The efforts of the Task II phase have been directed to meet the following objectives: to provide feedback to the OTEC marine systems designs to assure that such designs reflect appropriate consideration of IM and R methods and unit costs, resulting in designs with reduced life cycle costs; to include technical information concerning OTEC IM and R possibilities to NOAA/DOE; to outline a basis in which the anticipated IM and R contributions to life cycle costs can be developed for any specific OTEC plant design; to identify IM and R methods within the state-of-the-art in the offshore industry; to determine the application of potential IM and R procedures for the commercial operation of OTEC 10/40 Pilot Plant(s); and input into the US government formulation of statutory and regulatory IM and R requirements for OTEC plants.

  11. Enriching the Research Experiences for Undergraduates in Geoscience Through Student Feedback

    NASA Astrophysics Data System (ADS)

    Sears, R. F.; Bank, C. G.

    2014-12-01

    Research Experiences for Undergraduates (REU) allow students to work alongside professionals while they conduct scientific research and offer excellent opportunities to expose students to the practical components of their university education. Indeed, anecdotal evidence shows that a well-planned REU builds teamwork skills, provides a deeper understanding of the science learned in the classroom, and allows students to experience the various stages of science and thus consider wider career options. However, such evidence is difficult to measure. In this presentation we will present preliminary results from a survey of 2nd and 3rd year students who have been engaged in separate interdisciplinary projects (a geophysical survey in South Africa to assist archaeologists, and a forensic study in collaboration with the provincial police). Our before and after surveys address criteria such as students' understanding of scientific methodology, familiarity with the topic and tools for the research, expectations of the study and of themselves, and logistics of doing science. It is our hope that the student voices we present will help REU program coordinators to address limitations and establish best practices to provide the richest possible learning experience.

  12. Martian Soil Plant Growth Experiment: The Effects of Adding Nitrogen, Bacteria, and Fungi to Enhance Plant Growth

    NASA Technical Reports Server (NTRS)

    Kliman, D. M.; Cooper, J. B.; Anderson, R. C.

    2000-01-01

    Plant growth is enhanced by the presence of symbiotic soil microbes. In order to better understand how plants might prosper on Mars, we set up an experiment to test whether symbiotic microbes function to enhance plant growth in a Martian soil simulant.

  13. Waste Estimates for a Future Recycling Plant in the US Based Upon AREVA Operating Experience - 13206

    SciTech Connect

    Foare, Genevieve; Meze, Florian; Bader, Sven; McGee, Don; Murray, Paul; Prud'homme, Pascal

    2013-07-01

    Estimates of process and secondary wastes produced by a recycling plant built in the U.S., which is composed of a used nuclear fuel (UNF) reprocessing facility and a mixed oxide (MOX) fuel fabrication facility, are performed as part of a U.S. Department of Energy (DOE) sponsored study [1]. In this study, a set of common inputs, assumptions, and constraints were identified to allow for comparison of these wastes between different industrial teams. AREVA produced a model of a reprocessing facility, an associated fuel fabrication facility, and waste treatment facilities to develop the results for this study. These facilities were divided into a number of discrete functional areas for which inlet and outlet flow streams were clearly identified to allow for an accurate determination of the radionuclide balance throughout the facility and the waste streams. AREVA relied primarily on its decades of experience and feedback from its La Hague (reprocessing) and MELOX (MOX fuel fabrication) commercial operating facilities in France to support this assessment. However, to perform these estimates for a U.S. facility with different regulatory requirements and to take advantage of some technological advancements, such as in the potential treatment of off-gases, some deviations from this experience were necessary. A summary of AREVA's approach and results for the recycling of 800 metric tonnes of initial heavy metal (MTIHM) of LWR UNF per year into MOX fuel under the assumptions and constraints identified for this DOE study are presented. (authors)

  14. Operating experience feedback report: Experience with pump seals installed in reactor coolant pumps manufactured by Byron Jackson. Commercial power reactors, Volume 7

    SciTech Connect

    Bell, L.G.; O`Reilly, P.D.

    1992-09-01

    This report examines the reactor coolant pump (RCP) seal operating experience through August 1990 at plants with Byron Jackson (B-J) RCPs. ne operating experience examined in this analysis included a review of the practice of continuing operation with a degraded seal. Plants with B-J RCPs that have had relatively good experience with their RCP seals attribute this success to a combination of different factors, including: enhanced seal QA efforts, modified/new seal designs, improved maintenance procedures and training, attention to detail, improved seal operating procedures, knowledgeable personnel involved in seal maintenance and operation, reduction in frequency of transients that stress the seals, seal handling and installation equipment designed to the appropriate precision, and maintenance of a clean seal cooling water system. As more plants have implemented corrective measures such as these, the number of B-J RCP seal failures experienced has tended to decrease. This study included a review of the practice of continued operation with a degraded seal in the case of PWR plants with Byron Jackson reactor coolant pumps. Specific factors were identified which should be addressed in order to safety manage operation of a reactor coolant pump with indications of a degrading seal.

  15. Feedback & Objectives

    ERIC Educational Resources Information Center

    Butterworth, James R.

    1975-01-01

    Industrial objectives, if they are employee oriented, produce feedback, and the motivation derived from the feedback helps reduce turnover. Feedback is the power to clarify objectives, to stimulate communication, and to motivate people. (Author/MW)

  16. Predicting Sport Experience During Training: The Role of Change-Oriented Feedback in Athletes' Motivation, Self-Confidence and Needs Satisfaction Fluctuations.

    PubMed

    Carpentier, Joëlle; Mageau, Geneviève A

    2016-02-01

    Change-oriented feedback (COF) quality is predictive of between-athletes differences in their sport experience (Carpentier & Mageau, 2013). This study extends these findings by investigating how training-to-training variations in COF quality influence athletes' training experience (within-athlete differences) while controlling for the impact of promotion-oriented feedback (POF). In total, 49 athletes completed a diary after 15 consecutive training sessions to assess COF and POF received during training, as well as situational outcomes. Multivariate multilevel analyses showed that, when controlling for covariates, COF quality during a specific training session is positively linked to athletes' autonomous motivation, self-confidence and satisfaction of their psychological needs for autonomy and relatedness during the same session. In contrast, COF quantity is negatively linked to athletes' need for competence. POF quality is a significant positive predictor of athletes' self-confidence and needs for autonomy and competence. Contributions to the feedback and SDT literature, and for coaches' training, are discussed.

  17. Experience-dependent modulation of right anterior insula and sensorimotor regions as a function of noise-masked auditory feedback in singers and nonsingers.

    PubMed

    Kleber, Boris; Friberg, Anders; Zeitouni, Anthony; Zatorre, Robert

    2017-02-15

    Previous studies on vocal motor production in singing suggest that the right anterior insula (AI) plays a role in experience-dependent modulation of feedback integration. Specifically, when somatosensory input was reduced via anesthesia of the vocal fold mucosa, right AI activity was down regulated in trained singers. In the current fMRI study, we examined how masking of auditory feedback affects pitch-matching accuracy and corresponding brain activity in the same participants. We found that pitch-matching accuracy was unaffected by masking in trained singers yet declined in nonsingers. The corresponding brain region with the most differential and interesting activation pattern was the right AI, which was up regulated during masking in singers but down regulated in nonsingers. Likewise, its functional connectivity with inferior parietal, frontal, and voice-relevant sensorimotor areas was increased in singers yet decreased in nonsingers. These results indicate that singers relied more on somatosensory feedback, whereas nonsingers depended more critically on auditory feedback. When comparing auditory vs somatosensory feedback involvement, the right anterior insula emerged as the only region for correcting intended vocal output by modulating what is heard or felt as a function of singing experience. We propose the right anterior insula as a key node in the brain's singing network for the integration of signals of salience across multiple sensory and cognitive domains to guide vocal behavior.

  18. Assessing biosphere feedbacks on Earth System Processes

    NASA Astrophysics Data System (ADS)

    McElwain, Jennifer

    2016-04-01

    The evolution and ecology of plant life has been shaped by the direct and indirect influence of plate tectonics. Climatic change and environmental upheaval associated with the emplacement of large igneous provinces have triggered biosphere level ecological change, physiological modification and pulses of both extinction and origination. This talk will investigate the influence of large scale changes in atmospheric composition on plant ecophysiology at key intervals of the Phanerozoic. Furthermore, I will assess the extent to which plant ecophysiological response can in turn feedback on earth system processes such as the global hydrological cycle and biogeochemical cycling of nitrogen and carbon. Palaeo-atmosphere simulation experiments, palaeobotanical data and recent historical (last 50 years) data-model comparison will be used to address the extent to which plant physiological responses to atmospheric CO2 can modulate global climate change via biosphere level feedback.

  19. The Arabidopsis NMD Factor UPF3 Is Feedback-Regulated at Multiple Levels and Plays a Role in Plant Response to Salt Stress

    PubMed Central

    Vexler, Karina; Cymerman, Miryam A.; Berezin, Irina; Fridman, Adi; Golani, Linoy; Lasnoy, Michal; Saul, Helen; Shaul, Orit

    2016-01-01

    Nonsense-mediated mRNA decay (NMD) is a eukaryotic RNA surveillance mechanism that degrades aberrant transcripts and controls the levels of many normal mRNAs. It was shown that balanced expression of the NMD factor UPF3 is essential for the maintenance of proper NMD homeostasis in Arabidopsis. UPF3 expression is controlled by a negative feedback loop that exposes UPF3 transcript to NMD. It was shown that the long 3′ untranslated region (3′ UTR) of UPF3 exposes its transcript to NMD. Long 3′ UTRs that subject their transcripts to NMD were identified in several eukaryotic NMD factors. Interestingly, we show here that a construct that contains all the regulatory regions of the UPF3 gene except this long 3′ UTR is also feedback-regulated by NMD. This indicates that UPF3 expression is feedback-regulated at multiple levels. UPF3 is constitutively expressed in different plant tissues, and its expression is equal in leaves of plants of different ages. This finding is in agreement with the possibility that UPF3 is ubiquitously operative in the Arabidopsis NMD pathway. Expression mediated by the regulatory regions of UPF3 is significantly induced by salt stress. We found that both a deficiency and a strong excess of UPF3 expression are detrimental to plant resistance to salt stress. This indicates that UPF3 plays a role in plant response to salt stress, and that balanced expression of the UPF3 gene is essential for coping with this stress. PMID:27746786

  20. Experiment on a feedback control of nonlinear thermocapillary convection in a half-zone liquid bridge

    NASA Astrophysics Data System (ADS)

    Kudo, M.; Ueno, I.; Shiomi, J.; Amberg, G.; Kawamura, H.

    Under microgravity condition, themocapillarity dominates in material processing. In a half-zone method, two co-axial cylindrical rods hold a liquid bridge by the surface tension. By adding a temperature difference Δ T between the rods, thermocapillary flow is induced in the bridge. The convection changes from two-dimensional steady flow to three-dimensional oscillatory one at a critical Δ T in the case of medium to high Prandtl number (Pr) fluid. In our latest study (Shiomi et al., JFM, 2003), complete damping of the temperature oscillation was not achieved at highly nonlinear regions by a simple cancellation scheme. The excitation of unexpected other azimuthal wave numbers prevented the suppression of the oscillation. The present study aimed to develop a new control scheme with taking into account of spatio-temporal azimuthal temperature distribution. The target geometry was a liquid bridge of 5 mm in diameter and of a unit aspect ratio, Γ g(g= H/R=1, where H and R are the height and the radius of the bridge, respectively). At this aspect ratio, a dominant azimuthal mode was wave number of 2 when the control was absent. Silicone oil of 5 cSt (Pr = 68 at 25C) was employed as a test fluid. The flow field was visualized by suspending polystyrene sphere particles (D =17μ m). The present experiments were performed with 4 sensors located at different azimuthal positions for the evaluation of the azimuthal surface temperature distribution as well as with 2 heaters to suppress its non-uniform distribution. All sensors and heaters were located at the mid-height of the bridge. The present algorithm involved two main features; the first one was the time-dependent estimation of the azimuthal surface temperature distribution at the height of the sensors and heaters. Evaluation of the azimuthal temperature distribution enabled us to cancel the temperature oscillation by local heating effectively. The second one was the time-dependent evaluation of a frequency of the

  1. Experiment 8: Environmental Conditions in the ASTROCULTURE(trademark) Plant Chamber During the USML-2 Mission

    NASA Technical Reports Server (NTRS)

    Bula, R. J.; Zhou, Weijia; Yetka, R. A.; Draeger, N. A.

    1998-01-01

    Conducting plant research to assess the impact of microgravity on plant growth and development requires a plant chamber that has the capability to control other environmental parameters involved in plant growth and development. The environmental control in a space-based plant chamber must be equivalent to that available in such facilities used for terrestrial plant research. Additionally, plants are very sensitive to a number of atmospheric gaseous materials. Thus, the atmosphere of a plant chamber must be isolated from the space vehicle atmosphere, and the plant growth unit should have the capability to remove any such deleterious materials that may impact plant growth and development. The Wisconsin Center for Space Automation and Robotics (WCSAR), University of Wisconsin-Madison, has developed a totally enclosed controlled environment plant growth unit. The flight unit was used to support the ASTROCULTURE(TM) experiment conducted during the USML-2 mission. The experiment had two major objectives: 1) Provide further validation of the flight unit to control the experiment-defined environmental parameters in the plant chamber, and 2) support a plant experiment to assess the capability of potato plant material to produce tubers in microgravity. This paper describes the temperature, humidity, and carbon dioxide conditions of the plant chamber during the mission, from launch to landing. Another paper will present the plant response data.

  2. A Plant That Escapes from a Locked Box...and Other Growing Experiments.

    ERIC Educational Resources Information Center

    Kirkman, Will

    1979-01-01

    Seven easy-to-do experiments with plants are outlined to aid in teaching children about plants: their search for water, food, and light; a variety of rooting systems; and the effects of soil temperatures. (JMF)

  3. Feedback stabilization initiative

    SciTech Connect

    1997-06-01

    Much progress has been made in attaining high confinement regimes in magnetic confinement devices. These operating modes tend to be transient, however, due to the onset of MHD instabilities, and their stabilization is critical for improved performance at steady state. This report describes the Feedback Stabilization Initiative (FSI), a broad-based, multi-institutional effort to develop and implement methods for raising the achievable plasma betas through active MHD feedback stabilization. A key element in this proposed effort is the Feedback Stabilization Experiment (FSX), a medium-sized, national facility that would be specifically dedicated to demonstrating beta improvement in reactor relevant plasmas by using a variety of MHD feedback stabilization schemes.

  4. Spectral radiative kernel technique and the spectrally-resolved longwave feedbacks in the CMIP3 and CMIP5 experiments

    NASA Astrophysics Data System (ADS)

    Huang, Xianglei; Chen, Xiuhong; Soden, Brian; Liu, Xu

    2015-04-01

    Radiative feedback is normally discussed in terms of Watts per square meter per K, i.e., the change of broadband flux due to the change of certain climate variable in response to 1K change in global-mean surface temperature. However, the radiative feedback has an intrinsic dimension of spectrum and spectral radiative feedback can be defined in terms of Watts per square meter per K per frequency (or per wavelength). A set of all-sky and clear-sky longwave (LW) spectral radiative kernels (SRK) are constructed using a recently developed spectral flux simulator based on the PCRTM (Principal-Component-based Radiative Transfer Model). The LW spectral radiative kernels are validated against the benchmark partial radiative perturbation method. The LW broadband feedbacks derived using this SRK method are consistent with the published results using the broadband radiative kernels. The SRK is then applied to 12 GCMs in CMIP3 archives and 12 GCMs in CMIP5 archives to derive the spectrally resolved Planck, lapse rate, and LW water vapor feedbacks. The inter-model spreads of the spectral lapse-rate feedbacks among the CMIP3 models are noticeably different than those among the CMIP5 models. In contrast, the inter-model spread of spectral LW water vapor feedbacks changes little from the CMIP3 to CMIP5 simulations, when the specific humidity is used as the state variable. Spatially the far-IR band is more responsible for the changes in lapse-rate feedbacks from the CMIP3 to CMIP5 than the window band. When relative humidity (RH) is used as state variable, virtually all GCMs have little broadband RH feedbacks as shown in Held & Shell (2012). However, the RH feedbacks can be significantly non-zero over different LW spectral regions and the spectral details of such RH feedbacks vary significantly from one GCM to the other. Finally an interpretation based on a one-layer atmospheric model is presented to illustrate under what statistical circumstances the linear technique can be applied

  5. Nuclear plant operations: The U.S. experience

    SciTech Connect

    Lang, J.

    1996-12-31

    Over the past 20 years, electricity has taken on an increasingly important role in the U.S. energy mix and an increasing fraction of that electricity has been generated by nuclear power plants. However, producing electricity with nuclear energy is not an end in itself for electric utilities. Nuclear power is attractive only in so far as it is a safe and economical means of producing electricity. Safety has been and will remain a priority with the nuclear industry-it`s part of the culture. However, during the 1980`s, the economy of nuclear power was called into question. Nuclear production costs (operations, maintenance and fuel) grew at a rate greater than inflation, led by the costs of operations and maintenance. The production costs peaked in 1987 at which time several factors responding to competition from other forms of generation combined to bring them down. The decline in costs is continuing, yielding the positive experience discussed in this paper. 1 ref., 11 figs.

  6. An air transfer experiment confirms the role of volatile cues in communication between plants.

    PubMed

    Karban, Richard; Shiojiri, Kaori; Ishizaki, Satomi

    2010-09-01

    Previous studies reported that sagebrush plants near experimentally clipped neighbors experienced less herbivory than did plants near unclipped neighbors. Blocking air flow with plastic bags made this effect undetectable. However, some scientists remained skeptical about the possibility of volatile communication between plants since the existence and identity of a cue that operates in nature have never been demonstrated. We conducted an air transfer experiment that collected air from the headspace of an experimentally clipped donor plant and delivered it to the headspace of an unclipped assay plant. We found that assay plants treated with air from clipped donors were less likely to be damaged by naturally occurring herbivores in a field experiment. This simple air transfer experiment fulfills the most critical of Koch's postulates and provides more definitive evidence for volatile communication between plants. It also provides an inexpensive experimental protocol that can be used to screen plants for interplant communication in the field.

  7. Robots in PSE G's nuclear plants - experience and future projections

    SciTech Connect

    Roman, H.T. )

    1992-01-01

    Since the cleanup at Three Mile Island Unit 2 utilities have used robots, specifically teleoperated devices, to save significant human exposure, reduce plant downtime, and improve plant operations. Early work has centered on plant inspection, surveillance, and monitoring tasks, with future efforts likely to be directed toward operation and maintenance tasks. Public Service Electric Gas (PSE G) Company has been a pioneer in the application of this technology, gaining worldwide recognition for its work. PSE G's leadership role in this technology and their nationally recognized Applied Robotics Technology (ART) Facility has served as a model for the national and international utility industries. This paper very briefly explores the growth in utility robotic applications; discusses in detail PSE G's use of robotic devices; examines the role of the ART Facility in PSE G's success; and projects the potential role of robots in the power plant of the future.

  8. The Impact of Disciplinary Background and Teaching Experience on the Use of Evaluative Language in Teacher Feedback

    ERIC Educational Resources Information Center

    Hu, Guangwei; Choo, Lilin

    2016-01-01

    This study was designed to examine secondary teachers' use of evaluative language resources in their qualitative written feedback on student work and factors shaping the deployment of such resources. Drawing on appraisal theory as an analytic framework for the language of evaluation, the study analyzed 84 teachers' evaluative reports on their…

  9. Balanced bridge feedback control system

    NASA Technical Reports Server (NTRS)

    Lurie, Boris J. (Inventor)

    1990-01-01

    In a system having a driver, a motor, and a mechanical plant, a multiloop feedback control apparatus for controlling the movement and/or positioning of a mechanical plant, the control apparatus has a first local bridge feedback loop for feeding back a signal representative of a selected ratio of voltage and current at the output driver, and a second bridge feedback loop for feeding back a signal representative of a selected ratio of force and velocity at the output of the motor. The control apparatus may further include an outer loop for feeding back a signal representing the angular velocity and/or position of the mechanical plant.

  10. Stem girdling evidences a trade-off between cambial activity and sprouting and dramatically reduces plant transpiration due to feedback inhibition of photosynthesis and hormone signaling

    PubMed Central

    López, Rosana; Brossa, Ricard; Gil, Luis; Pita, Pilar

    2015-01-01

    The photosynthesis source–sink relationship in young Pinus canariensis seedlings was modified by stem girdling to investigate sprouting and cambial activity, feedback inhibition of photosynthesis, and stem and root hydraulic capacity. Removal of bark tissue showed a trade-off between sprouting and diameter growth. Above the girdle, growth was accelerated but the number of sprouts was almost negligible, whereas below the girdle the response was reversed. Girdling resulted in a sharp decrease in whole plant transpiration and root hydraulic conductance. The reduction of leaf area after girdling was strengthened by the high levels of abscisic acid found in buds which pointed to stronger bud dormancy, preventing a new needle flush. Accumulation of sugars in leaves led to a coordinated reduction in net photosynthesis (AN) and stomatal conductance (gS) in the short term, but later (gS below 0.07 mol m-2 s-1) AN decreased faster. The decrease in maximal efficiency of photosystem II (FV/FM) and the operating quantum efficiency of photosystem II (ΦPSII) in girdled plants could suggest photoprotection of leaves, as shown by the vigorous recovery of AN and ΦPSII after reconnection of the phloem. Stem girdling did not affect xylem embolism but increased stem hydraulic conductance above the girdle. This study shows that stem girdling affects not only the carbon balance, but also the water status of the plant. PMID:25972884

  11. Specifications for and preliminary design of a plant growth chamber for orbital experimental experiments

    NASA Technical Reports Server (NTRS)

    Sweet, H. C.; Simmonds, R. C.

    1976-01-01

    It was proposed that plant experiments be performed on board the space shuttle. To permit the proper execution of most tests, the craft must contain a plant growth chamber which is adequately designed to control those environmental factors which can induce changes in a plant's physiology and morphology. The various needs of, and environmental factors affecting, plants are identified. The permissilbe design, construction and performance limits for a plant-growth chamber are set, and tentative designs were prepared for units which are compatible with both the botanical requirements and the constraints imposed by the space shuttle.

  12. Ambulatory Feedback System

    NASA Technical Reports Server (NTRS)

    Finger, Herbert; Weeks, Bill

    1985-01-01

    This presentation discusses instrumentation that will be used for a specific event, which we hope will carry on to future events within the Space Shuttle program. The experiment is the Autogenic Feedback Training Experiment (AFTE) scheduled for Spacelab 3, currently scheduled to be launched in November, 1984. The objectives of the AFTE are to determine the effectiveness of autogenic feedback in preventing or reducing space adaptation syndrome (SAS), to monitor and record in-flight data from the crew, to determine if prediction criteria for SAS can be established, and, finally, to develop an ambulatory instrument package to mount the crew throughout the mission. The purpose of the Ambulatory Feedback System (AFS) is to record the responses of the subject during a provocative event in space and provide a real-time feedback display to reinforce the training.

  13. Plant Growth Experiments in Zeoponic Substrates: Applications for Advanced Life Support Systems

    NASA Technical Reports Server (NTRS)

    Ming, Douglas W.; Gruener, J. E.; Henderson, K. E.; Steinberg, S. L.; Barta, D. J.; Galindo, C.; Henninger, D. L.

    2001-01-01

    A zeoponic plant-growth system is defined as the cultivation of plants in artificial soils, which have zeolites as a major component (Allen and Ming, 1995). Zeolites are crystalline, hydrated aluminosilicate minerals that have the ability to exchange constituent cations without major change of the mineral structure. Recently, zeoponic systems developed at the National Aeronautics and Space Administration (NASA) slowly release some (Allen et at., 1995) or all of the essential plant-growth nutrients (Ming et at., 1995). These systems have NH4- and K-exchanged clinoptilolite (a natural zeolite) and either natural or synthetic apatite (a calcium phosphate mineral). For the natural apatite system, Ca and P were made available to the plant by the dissolution of apatite. Potassium and NH4-N were made available by ion-exchange reactions involving Ca(2+) from apatite dissolution and K(+) and NH4(+) on zeolitic exchange sites. In addition to NH4-N, K, Ca, and P, the synthetic apatite system also supplied Mg, S, and other micronutrients during dissolution (Figure 1). The overall objective of this research task is to develop zeoponic substrates wherein all plant growth nutrients are supplied by the plant growth medium for several growth seasons with only the addition of water. The substrate is being developed for plant growth in Advanced Life Support (ALS) testbeds (i.e., BioPLEX) and microgravity plant growth experiments. Zeoponic substrates have been used for plant growth experiments on two Space Shuttle flight experiments (STS-60; STS-63; Morrow et aI., 1995). These substrates may be ideally suited for plant growth experiments on the International Space Station and applications in ALS testbeds. However, there are several issues that need to be resolved before zeoponics will be the choice substrate for plant growth experiments in space. The objective of this paper is to provide an overview on recent research directed toward the refinement of zeoponic plant growth substrates.

  14. A plant resource and experiment management system based on the Golm Plant Database as a basic tool for omics research

    PubMed Central

    Köhl, Karin I; Basler, Georg; Lüdemann, Alexander; Selbig, Joachim; Walther, Dirk

    2008-01-01

    Background For omics experiments, detailed characterisation of experimental material with respect to its genetic features, its cultivation history and its treatment history is a requirement for analyses by bioinformatics tools and for publication needs. Furthermore, meta-analysis of several experiments in systems biology based approaches make it necessary to store this information in a standardised manner, preferentially in relational databases. In the Golm Plant Database System, we devised a data management system based on a classical Laboratory Information Management System combined with web-based user interfaces for data entry and retrieval to collect this information in an academic environment. Results The database system contains modules representing the genetic features of the germplasm, the experimental conditions and the sampling details. In the germplasm module, genetically identical lines of biological material are generated by defined workflows, starting with the import workflow, followed by further workflows like genetic modification (transformation), vegetative or sexual reproduction. The latter workflows link lines and thus create pedigrees. For experiments, plant objects are generated from plant lines and united in so-called cultures, to which the cultivation conditions are linked. Materials and methods for each cultivation step are stored in a separate ACCESS database of the plant cultivation unit. For all cultures and thus every plant object, each cultivation site and the culture's arrival time at a site are logged by a barcode-scanner based system. Thus, for each plant object, all site-related parameters, e.g. automatically logged climate data, are available. These life history data and genetic information for the plant objects are linked to analytical results by the sampling module, which links sample components to plant object identifiers. This workflow uses controlled vocabulary for organs and treatments. Unique names generated by the system

  15. Field experience & usage of the Sentinel treatment plant

    SciTech Connect

    Hiscock, K.C.

    1994-12-31

    A process of chemically induced flocculation followed by filtration through activated carbon has been shown to be very effective in removing pesticides from waste water prior to disposal or re-use. Large plants treating up to 100 m{sup 3} per day have been used in agrochemical manufacturing for the past twenty years. This system has been miniaturized to produce a batch treatment family of self-contained plants from 20 litres to 5000 litres. These plans have found their way into thirty-three countries worldwide, treating rinsate from research stations, field trial teams, research universities, farmers, horticulturists as well as ag-chem producers, packers, formulators and storers. In worldwide results, removal of active ingredients to the lowest level of detection have been consistently achieved.

  16. Decontamination and Decommissioning Experience at a Sellafield Uranium Purification Plant

    SciTech Connect

    Prosser, J.L.

    2006-07-01

    Built in the 1950's, this plant was originally designed to purify depleted uranyl nitrate solution arising from reprocessing operations at the Primary Separation and Head End Plant (Fig. 1). The facility was used for various purposes throughout its life cycle such as research, development and trial based processes. Test rigs were operated in the building from the 1970's until 1984 to support development of the process and equipment now used at Sellafield's Thermal Oxide Reprocessing Plant (THORP). The extensive decommissioning program for this facility began over 15 years ago. Many challenges have been overcome throughout this program such as decommissioning the four main process cells, which were very highly alpha contaminated. The cells contained vessels and pipeline systems that were contaminated to such levels that workers had to use pressurized suits to enter the cells. Since decommissioning at Sellafield was in its infancy, this project has trialed various decontamination/decommissioning methods and techniques in order to progress the project, and this has provided valuable learning for other decommissioning projects. The project has included characterization, decontamination, dismantling, waste handling, and is now ready for demolition during late 2005, early 2006. This will be the first major facility within the historic Separation Area at Sellafield to be demolished down to base slab level. The lessons learnt from this project will directly benefit numerous decommissioning projects as the cleanup at Sellafield continues. (authors)

  17. Feedback in Videogame-based Adaptive Training

    DTIC Science & Technology

    2011-05-01

    individuals have limited information processing capabilities. Salvati et al. (2003) identified several antecedents and consequences to feedback overload... Antecedents included feedback value and job experience while important consequences were the desire to respond to feedback, stress, and job...Morin, D. (2003). Performance feedback overload: An exploratory field study of its antecedents and consequences . Montreal, Quebec: HEC Montreal

  18. Spaceflight hardware for conducting plant growth experiments in space: the early years 1960-2000

    NASA Technical Reports Server (NTRS)

    Porterfield, D. M.; Neichitailo, G. S.; Mashinski, A. L.; Musgrave, M. E.

    2003-01-01

    The best strategy for supporting long-duration space missions is believed to be bioregenerative life support systems (BLSS). An integral part of a BLSS is a chamber supporting the growth of higher plants that would provide food, water, and atmosphere regeneration for the human crew. Such a chamber will have to be a complete plant growth system, capable of providing lighting, water, and nutrients to plants in microgravity. Other capabilities include temperature, humidity, and atmospheric gas composition controls. Many spaceflight experiments to date have utilized incomplete growth systems (typically having a hydration system but lacking lighting) to study tropic and metabolic changes in germinating seedlings and young plants. American, European, and Russian scientists have also developed a number of small complete plant growth systems for use in spaceflight research. Currently we are entering a new era of experimentation and hardware development as a result of long-term spaceflight opportunities available on the International Space Station. This is already impacting development of plant growth hardware. To take full advantage of these new opportunities and construct innovative systems, we must understand the results of past spaceflight experiments and the basic capabilities of the diverse plant growth systems that were used to conduct these experiments. The objective of this paper is to describe the most influential pieces of plant growth hardware that have been used for the purpose of conducting scientific experiments during the first 40 years of research. c2002 COSPAR. Published by Elsevier Science Ltd. All rights reserved.

  19. Spaceflight hardware for conducting plant growth experiments in space: the early years 1960-2000.

    PubMed

    Porterfield, D M; Neichitailo, G S; Mashinski, A L; Musgrave, M E

    2003-01-01

    The best strategy for supporting long-duration space missions is believed to be bioregenerative life support systems (BLSS). An integral part of a BLSS is a chamber supporting the growth of higher plants that would provide food, water, and atmosphere regeneration for the human crew. Such a chamber will have to be a complete plant growth system, capable of providing lighting, water, and nutrients to plants in microgravity. Other capabilities include temperature, humidity, and atmospheric gas composition controls. Many spaceflight experiments to date have utilized incomplete growth systems (typically having a hydration system but lacking lighting) to study tropic and metabolic changes in germinating seedlings and young plants. American, European, and Russian scientists have also developed a number of small complete plant growth systems for use in spaceflight research. Currently we are entering a new era of experimentation and hardware development as a result of long-term spaceflight opportunities available on the International Space Station. This is already impacting development of plant growth hardware. To take full advantage of these new opportunities and construct innovative systems, we must understand the results of past spaceflight experiments and the basic capabilities of the diverse plant growth systems that were used to conduct these experiments. The objective of this paper is to describe the most influential pieces of plant growth hardware that have been used for the purpose of conducting scientific experiments during the first 40 years of research.

  20. Feedback of research findings for vaccine trials: experiences from two malaria vaccine trials involving healthy children on the Kenyan Coast.

    PubMed

    Gikonyo, Caroline; Kamuya, Dorcas; Mbete, Bibi; Njuguna, Patricia; Olotu, Ally; Bejon, Philip; Marsh, Vicki; Molyneux, Sassy

    2013-04-01

    Internationally, calls for feedback of findings to be made an 'ethical imperative' or mandatory have been met with both strong support and opposition. Challenges include differences in issues by type of study and context, disentangling between aggregate and individual study results, and inadequate empirical evidence on which to draw. In this paper we present data from observations and interviews with key stakeholders involved in feeding back aggregate study findings for two Phase II malaria vaccine trials among children under the age of 5 years old on the Kenyan Coast. In our setting, feeding back of aggregate findings was an appreciated set of activities. The inclusion of individual results was important from the point of view of both participants and researchers, to reassure participants of trial safety, and to ensure that positive results were not over-interpreted and that individual level issues around blinding and control were clarified. Feedback sessions also offered an opportunity to re-evaluate and re-negotiate trial relationships and benefits, with potentially important implications for perceptions of and involvement in follow-up work for the trials and in future research. We found that feedback of findings is a complex but key step in a continuing set of social interactions between community members and research staff (particularly field staff who work at the interface with communities), and among community members themselves; a step which needs careful planning from the outset. We agree with others that individual and aggregate results need to be considered separately, and that for individual results, both the nature and value of the information, and the context, including social relationships, need to be taken into account.

  1. Strategies for effective feedback.

    PubMed

    Kritek, Patricia A

    2015-04-01

    Provision of regular feedback to trainees on clinical performance by supervising providers is increasingly recognized as an essential component of undergraduate and graduate health sciences education; however, many individuals have not been formally trained in this pedagogical skill. At the bedside or in the clinic, effective performance feedback can be accomplished by following four key steps. Begin by setting expectations that incorporate the trainee's personal goals and external objectives. Delineate how and when you will provide feedback to the learner. Next, directly observe the trainee's performance. This can be challenging while engaged on a busy clinical service, but a focus on discrete activities or interactions (e.g., family meeting, intravascular volume assessment using bedside ultrasound, or obtaining informed consent) is helpful. The third step is to plan and prioritize the feedback session. Feedback is most effective when given in a timely fashion and delivered in a safe environment. Limit the issues addressed because learners often disengage if confronted with too many deficiencies. Finally, when delivering feedback, begin by listening to the trainee's self-evaluation and then take a balanced approach. Describe in detail what the trainee does well and discuss opportunities for improvement with emphasis on specific, modifiable behaviors. The feedback loop is completed with a plan for follow-up reassessment. Through the use of these relatively simple practices, both the trainee and teacher can have a more productive learning experience.

  2. Fast feedback for linear colliders

    SciTech Connect

    Hendrickson, L.; Adolphsen, C.; Allison, S.; Gromme, T.; Grossberg, P.; Himel, T.; Krauter, K.; MacKenzie, R.; Minty, M.; Sass, R.

    1995-05-01

    A fast feedback system provides beam stabilization for the SLC. As the SLC is in some sense a prototype for future linear colliders, this system may be a prototype for future feedbacks. The SLC provides a good base of experience for feedback requirements and capabilities as well as a testing ground for performance characteristics. The feedback system controls a wide variety of machine parameters throughout the SLC and associated experiments, including regulation of beam position, angle, energy, intensity and timing parameters. The design and applications of the system are described, in addition to results of recent performance studies.

  3. Influence of land-atmosphere feedbacks on climate extreme indices in a multi-model experiment under present and future conditions (GLACE-CMIP5)

    NASA Astrophysics Data System (ADS)

    Lorenz, Ruth; Pitman, Andy; Seneviratne, Sonia

    2014-05-01

    Extreme events can be directly influenced by land surface-atmosphere interactions. It is important to investigate how extreme events might change in the future and the role these interactions play in amplifying extremes. The data from the GLACE-CMIP5 experiments (Seneviratne et al., 2013) provide a unique opportunity to examine the influence of soil moisture on extremes in transient climate simulations from a range of climate models. The extreme indices we use are defined by the Expert Team on Climate Change Detection and Indices (ETCCDI) and contain a range of indices based on daily minimum and maximum temperature as well as daily precipitation. The ETCCDI indices are available from observational datasets, reanalysis and as well as CMIP5 runs. Hence, these indices are widely used and can be compared to other sources. In this paper, we analyze the effects of land surface feedbacks on the extremes and their trends in the different global climate models. Seneviratne, S. I., et al. (2013). Impact of soil moisture-climate feedbacks on CMIP5 projections: First results from the GLACE-CMIP5 experiment. GRL, 40(19), 5212-5217. doi:10.1002/grl.50956

  4. US plant and radiation dosimetry experiments flown on the Soviet satellite Cosmos 1129

    NASA Technical Reports Server (NTRS)

    Heinrich, M. R. (Editor); Souza, K. A. (Editor)

    1981-01-01

    Experiments included: 30 young male Wistar SPF rats used for wide range physiological studies; experiments with plants, fungi, insects, and mammalian tissue cultures; radiation physics experiments; a heat convection study; a rat embryology experiment in which an attempt was made to breed 2 male and 5 female rats during the flight; and fertile quail eggs used to determine the effects of spaceflight on avian embryogenesis. Specimens for US experiments were initially prepared at the recovery site or in Moscow and transferred to US laboratories for complete analyses. An overview of the mission focusing on preflight, on orbit, and postflight activities pertinent to the fourteen US experiments aboard Cosmos 1129 is presented.

  5. Feed-back of quality control data evaluation to production experience of mixed uranium-plutonium dioxide fuels

    NASA Astrophysics Data System (ADS)

    Pelckmans, E.

    1988-04-01

    Quality Control is often defined as "The good implemented branch in the organization of the product flow, starting at the receipt of the feed materials of the products to be fabricated up to the delivery of the end products". This is a typical technical definition which is probably used for more than 50 years. A second more economically oriented definition is "Quality Control is the branch in the organization of the product flow with the aim to make this flow as cheep as possible". The latest is also the tool that is a quality support to the in real time fabrication process monitoring. Regulations of quality are widely applied to the nuclear fuel products and there has been some standardization and improvements in developing products, processes, measuring instruments and in fabrication technology. Quality Control is also adressed to the subject of quality costs and to make use of statistical methods. Quality Control data evaluation can be used as an immediate and fruitful feed-back to production. Therefore not only the quality characteristics have to be evaluated but also the fabrication process parameters have to be examined and have to be fitted to obtained results. In this paper three examples are taken at different steps of the mixed oxide fuel production: 1. The incoming acceptance controls of the plutonium dioxide powder and its feed-back to the master-blending fabrication step (Light Water Reactor and Fast Neutron Reactor fuels). 2. The atomic oxygen to metal ratio drift during intermediate storage related to the allowable time delay between fuel pellet sintering and fuel pellet loading into the cladding tubes (Fast Neutron Reactor fuels). 3. Geometrical density and thermal stability related to addition of additives, sintered scraps and sintering fabrication parameter conditions (Light Water Reactor fuels).

  6. Feedback control for counterflow thrust vectoring with a turbine engine: Experiment design and robust control design and implementation

    NASA Astrophysics Data System (ADS)

    Dores, Delfim Zambujo Das

    2005-11-01

    Engineering research over the last few years has successfully demonstrated the potential of thrust vector control using counterflow at conditions up to Mach 2. Flow configurations that include the pitch vectoring of rectangular jets and multi-axis vector control in diamond and axisymmetric nozzle geometries have been studied. Although bistable (on-off) fluid-based control has been around for some time, the present counterflow thrust vector control is unique because proportional and continuous jet response can be achieved in the absence of moving parts, while avoiding jet attachment, which renders most fluidic approaches unacceptable for aircraft and missile control applications. However, before this study, research had been limited to open-loop studies of counterflow thrust vectoring. For practical implementation it was vital that the counterflow scheme be used in conjunction with feedback control. Hence, the focus of this research was to develop and experimentally demonstrate a feedback control design methodology for counterflow thrust vectoring. This research focused on 2-D (pitch) thrust vectoring and addresses four key modeling issues. The first issue is to determine the measured variable to be commanded since the thrust vector angle is not measurable in real time. The second related issue is to determine the static mapping from the thrust vector angle to this measured variable. The third issue is to determine the dynamic relationship between the measured variable and the thrust vector angle. The fourth issue is to develop dynamic models with uncertainty characterizations. The final and main goal was the design and implementation of robust controllers that yield closed-loop systems with fast response times, and avoid overshoot in order to aid in the avoidance of attachment. These controllers should be simple and easy to implement in real applications. Hence, PID design has been chosen. Robust control design is accomplished by using ℓ1 control theory in

  7. Airborne lidar experiments at the Savannah River Plant

    NASA Technical Reports Server (NTRS)

    Krabill, William B.; Swift, Robert N.

    1985-01-01

    The results of remote sensing experiments at the Department of Energy (DOE) Savannah River Nuclear Facility utilizing the NASA Airborne Oceanographic Lidar (AOL) are presented. The flights were conducted in support of the numerous environmental monitoring requirements associated with the operation of the facility and for the purpose of furthering research and development of airborne lidar technology. Areas of application include airborne laser topographic mapping, hydrologic studies using fluorescent tracer dye, timber volume estimation, baseline characterization of wetlands, and aquatic chlorophyll and photopigment measurements. Conclusions relative to the usability of airborne lidar technology for the DOE for each of these remote sensing applications are discussed.

  8. Pan-Eurasian Experiment (PEEX): towards a holistic understanding of the feedbacks and interactions in the land-atmosphere-ocean-society continuum in the northern Eurasian region

    NASA Astrophysics Data System (ADS)

    Lappalainen, Hanna K.; Kerminen, Veli-Matti; Petäjä, Tuukka; Kurten, Theo; Baklanov, Aleksander; Shvidenko, Anatoly; Bäck, Jaana; Vihma, Timo; Alekseychik, Pavel; Andreae, Meinrat O.; Arnold, Stephen R.; Arshinov, Mikhail; Asmi, Eija; Belan, Boris; Bobylev, Leonid; Chalov, Sergey; Cheng, Yafang; Chubarova, Natalia; de Leeuw, Gerrit; Ding, Aijun; Dobrolyubov, Sergey; Dubtsov, Sergei; Dyukarev, Egor; Elansky, Nikolai; Eleftheriadis, Kostas; Esau, Igor; Filatov, Nikolay; Flint, Mikhail; Fu, Congbin; Glezer, Olga; Gliko, Aleksander; Heimann, Martin; Holtslag, Albert A. M.; Hõrrak, Urmas; Janhunen, Juha; Juhola, Sirkku; Järvi, Leena; Järvinen, Heikki; Kanukhina, Anna; Konstantinov, Pavel; Kotlyakov, Vladimir; Kieloaho, Antti-Jussi; Komarov, Alexander S.; Kujansuu, Joni; Kukkonen, Ilmo; Duplissy, Ella-Maria; Laaksonen, Ari; Laurila, Tuomas; Lihavainen, Heikki; Lisitzin, Alexander; Mahura, Alexsander; Makshtas, Alexander; Mareev, Evgeny; Mazon, Stephany; Matishov, Dmitry; Melnikov, Vladimir; Mikhailov, Eugene; Moisseev, Dmitri; Nigmatulin, Robert; Noe, Steffen M.; Ojala, Anne; Pihlatie, Mari; Popovicheva, Olga; Pumpanen, Jukka; Regerand, Tatjana; Repina, Irina; Shcherbinin, Aleksei; Shevchenko, Vladimir; Sipilä, Mikko; Skorokhod, Andrey; Spracklen, Dominick V.; Su, Hang; Subetto, Dmitry A.; Sun, Junying; Terzhevik, Arkady Y.; Timofeyev, Yuri; Troitskaya, Yuliya; Tynkkynen, Veli-Pekka; Kharuk, Viacheslav I.; Zaytseva, Nina; Zhang, Jiahua; Viisanen, Yrjö; Vesala, Timo; Hari, Pertti; Christen Hansson, Hans; Matvienko, Gennady G.; Kasimov, Nikolai S.; Guo, Huadong; Bondur, Valery; Zilitinkevich, Sergej; Kulmala, Markku

    2016-11-01

    The northern Eurasian regions and Arctic Ocean will very likely undergo substantial changes during the next decades. The Arctic-boreal natural environments play a crucial role in the global climate via albedo change, carbon sources and sinks as well as atmospheric aerosol production from biogenic volatile organic compounds. Furthermore, it is expected that global trade activities, demographic movement, and use of natural resources will be increasing in the Arctic regions. There is a need for a novel research approach, which not only identifies and tackles the relevant multi-disciplinary research questions, but also is able to make a holistic system analysis of the expected feedbacks. In this paper, we introduce the research agenda of the Pan-Eurasian Experiment (PEEX), a multi-scale, multi-disciplinary and international program started in 2012 (https://www.atm.helsinki.fi/peex/). PEEX sets a research approach by which large-scale research topics are investigated from a system perspective and which aims to fill the key gaps in our understanding of the feedbacks and interactions between the land-atmosphere-aquatic-society continuum in the northern Eurasian region. We introduce here the state of the art for the key topics in the PEEX research agenda and present the future prospects of the research, which we see relevant in this context.

  9. Morpho-molecular analysis as a prognostic model for repulsive feedback of the medicinal plant "Andrographis paniculata" to allogamy.

    PubMed

    Valdiani, Alireza; Talei, Daryush; Javanmard, Arash; Tan, Soon Guan; Kadir, Mihdzar Abdul; Maziah, Mahmood

    2014-06-01

    Andrographis paniculata Nees. (AP) is a self-pollinated medicinal herb with a wide range of pharmaceutical properties, facing a low diversity in Malaysia. Cross-pollination of AP accessions leads to considerable rates of heterosis in the agro-morphological characteristics and anticancer phytochemicals of this eminent medicinal herb. However, the poor crossability of the plant at the interpopulation or intraspecific levels is an obstacle from the evolutionary and breeding points of view as an average of 4.56% crossability was recorded for AP in this study. Hence, this research aimed to elicit the impact of parental genetic distances (GDs) on the rate of crossability of AP using seven accessions in 21 possible cross combinations. To this end, a set of 55 randomly amplified polymorphic DNA (RAPD) primers and a total of 13 agro-morphological markers were employed to test the hypothesis. Twenty-two out of the 55 RAPD primers amplified a total of 257 bands of which 107 bands were found to be polymorphic. The principal component analysis (PCA) based on the RAPD markers revealed that the studied AP accessions were distributed to three distinct groups. Furthermore, it was noticed that even a minor increase in GD between two parents can cause a decline in their crossability. Unlike, the morphological-based GDs acted neutrally to crossability. This finding suggests that, despite the low genetic diversity among the Malaysian APs, a population prescreening using RAPD markers would be useful to enhance the rate of fruit set through selecting the genetically adjacent parents.

  10. Evolutionary changes in plant tolerance against herbivory through a resurrection experiment.

    PubMed

    Bustos-Segura, C; Fornoni, J; Núñez-Farfán, J

    2014-03-01

    Both theoretical and empirical works have highlighted the difference in the evolutionary implications of host resistance and tolerance against their enemies. However, it has been difficult to show evolutionary changes in host defences in natural populations; thus, evaluating theoretical predictions of simultaneous evolution of defences remains a challenge. We studied the evolutionary changes in traits related to resistance and tolerance against herbivory in a natural plant population using seeds from two collections made in a period of 20 years. In a common garden experiment, we compared defensive traits of ancestral (1987) and descendant (2007) subpopulations of the annual plant Datura stramonium that shows genetic variation for tolerance and to which the specialist herbivore Lema daturaphila is locally adapted. We also examined the effects of different plant genotypes on the herbivore for testing the plant genetic variation in resistance. Based on the response to the contemporary herbivore populations, results revealed a nonsignificant response in plant resistance traits (herbivore consumption, foliar trichomes and tropane alkaloids), but a significant one in tolerance. The survival of herbivores in laboratory experiments depended on the plant genotype, which suggests genetic variation in plant resistance. Although we cannot identify the selective agent for the change nor exclude genetic drift, the results are consistent with the expectation that when resistance fails to control herbivory, tolerance should play a more important role in the evolution of the interaction.

  11. Plant Growth During the Greenhouse II Experiment on the MIR Orbital Station

    NASA Technical Reports Server (NTRS)

    Salisbury, F. B.; Campbell, W. F.; Carman, J. G.; Bingham, G. E.; Bubenheim, D. L.; Yendler, B.; Sytchev, V.; Levinskikh, M. A.; Ivanova, I.; Chernova, L.; Podolsky, I.

    2002-01-01

    We carried out three experiments with Super Dwarf wheat in the Bulgarian/Russian growth chamber Svet (0.1 sq m growing area) on the Space Station Mir. This paper mostly describes the first of these NASA-supported trials, began on Aug. 13, 1995. Plants were sampled five times and harvested on Nov. 9 after 90 days. Equipment failures led to low irradiance (three, then four of six lamp sets failed), instances of high temperatures (ca. 37 C), and sometimes excessive-substrate moisture. Although plants grew for the 90 days, no wheat heads were produced. Considering the low light levels, plants were surprisingly green, but of course biomass production was low. Plants were highly disoriented (low light, mirror walls?). Fixed and dried samples and the root module were returned on the US Shuttle Atlantis on Nov. 20, 1995. Samples of the substrate, a nutrient-charged zeolite called Balkanine, were taken from the root module, carefully examined for roots, weighed, dried, and reweighed. The Svet control unit and the light bank were shipped to Moscow. An experiment validation test (EVT) of plant growth and experiment procedures, carried out in Moscow, was highly successful. Equipment built in Utah to measure CO2, H2O vapor, irradiance, air and leaf (IR) temperature, O2, pressure, and substrate moisture worked well in the EVT and in space. After this manuscript was first prepared, plants were grown in Mir with a new light bank and controller for 123 days in late 1996 and 39 days in 1996/1997. Plants grew exceptionally well with higher biomass production than in any previous space experiment, but the ca. 280 wheat heads that were produced in 1996 contained no seeds. Ethylene in the cabin atmosphere was responsible.

  12. Coupled pot and lysimeter experiments assessing plant performance in microbially assisted phytoremediation.

    PubMed

    Nicoară, Andrei; Neagoe, Aurora; Stancu, Paula; de Giudici, Giovanni; Langella, Francesca; Sprocati, Anna Rosa; Iordache, Virgil; Kothe, Erika

    2014-01-01

    We performed an experiment at pot scale to assess the effect of plant growth-promoting bacteria (PGPB) on the development of five plant species grown on a tailing dam substrate. None of the species even germinated on inoculated unamended tailing material, prompting use of compost amendment. The effect of inoculation on the amended material was to increase soil respiration, and promote elements immobilisation at plant root surface. This was associated with a decrease in the concentrations of elements in the leaching water and an increase of plant biomass, statistically significant in the case of two species: Agrostis capillaris and Festuca rubra. The experiment was repeated at lysimeter scale with the species showing the best development at pot scale, A. capillaris, and the significant total biomass increase as a result of inoculation was confirmed. The patterns of element distribution in plants also changed (the concentrations of metals in the roots of A. capillaris and F. rubra significantly decreased in inoculated treatments, while phosphorus concentration significantly increased in roots of A. capillaris in inoculated treatment at lysimeter scale). Measured variables for plant oxidative stress did not change after inoculations. There were differences of A. capillaris plant-soil system response between experimental scales as a result of different substrate column structure and plant age at the sampling moment. Soil respiration was significantly larger at lysimeter scale than at pot scale. Leachate concentrations of As, Mn and Ni had significantly larger concentrations at lysimeter scale than at pot scale, while Zn concentrations were significantly smaller. Concentrations of several metals were significantly smaller in A. capillaris at lysimeter scale than at pot scale. From an applied perspective, a system A. capillaris-compost-PGPB selected from the rhizosphere of the tailing dam native plants can be an option for the phytostabilisation of tailing dams. Results

  13. Combining mesocosm and field experiments to predict invasive plant performance: a hierarchical Bayesian approach.

    PubMed

    Wilson, Chris H; Caughlin, T Trevor; Civitello, David J; Flory, S Luke

    2015-04-01

    Invasive plant fecundity underlies propagule pressure and ultimately range expansion. Predicting fecundity across large spatial scales, from regions to landscapes, is critical for understanding invasion dynamics and optimizing management. However, to accurately predict fecundity and other demographic processes, improved models that scale individual plant responses to abiotic drivers across heterogeneous environments are needed. Here we combine two experimental data sets to predict fecundity of a widespread and problematic invasive grass over large spatial scales. First, we analyzed seed production as a function of plant biomass in a small-scale mesocosm experiment with manipulated light levels. Then, in a field introduction experiment, we tracked plant performance across 21 common garden sites that differed widely in available light and other factors. We jointly analyzed these data using a Bayesian hierarchical model (BHM) framework to predict fecundity as a function of light in the field. Our analysis reveals that the invasive species is likely to produce sufficient seed to overwhelm establishment resistance, even in deeply shaded environments, and is likely seed-limited across much of its range. Finally, we extend this framework to address the general problem of how to scale up plant demographic processes and analyze the factors that control plant distribution and abundance at large scales.

  14. Experiment of monitoring thermal discharge drained from nuclear plant through airborne infrared remote sensing

    NASA Astrophysics Data System (ADS)

    Wang, Difeng; Pan, Delu; Li, Ning

    2009-07-01

    The State Development and Planning Commission has approved nuclear power projects with the total capacity of 23,000 MW. The plants will be built in Zhejiang, Jiangsu, Guangdong, Shandong, Liaoning and Fujian Province before 2020. However, along with the nuclear power policy of accelerated development in our country, the quantity of nuclear plants and machine sets increases quickly. As a result the environment influence of thermal discharge will be a problem that can't be slid over. So evaluation of the environment influence and engineering simulation must be performed before station design and construction. Further more real-time monitoring of water temperature need to be arranged after fulfillment, reflecting variety of water temperature in time and provided to related managing department. Which will help to ensure the operation of nuclear plant would not result in excess environment breakage. At the end of 2007, an airborne thermal discharge monitoring experiment has been carried out by making use of MAMS, a marine multi-spectral scanner equipped on the China Marine Surveillance Force airplane. And experimental subject was sea area near Qin Shan nuclear plant. This paper introduces the related specification and function of MAMS instrument, and decrypts design and process of the airborne remote sensing experiment. Experiment showed that applying MAMS to monitoring thermal discharge is viable. The remote sensing on a base of thermal infrared monitoring technique told us that thermal discharge of Qin Shan nuclear plant was controlled in a small scope, never breaching national water quality standard.

  15. Woody plant richness does not influence invertebrate community reassembly trajectories in a tree diversity experiment.

    PubMed

    Yeeles, Peter; Lach, Lori; Hobbs, Richard J; van Wees, Mary; Didham, Raphael K

    2017-02-01

    Understanding the relationship between plant diversity and diversity at higher trophic levels is important from both conservation and restoration perspectives. Although there is strong evidence for bottom-up maintenance of biodiversity, this is based largely on studies of simplified grassland systems. Recently, studies in the TreeDivNet global network of tree diversity experiments have begun to test whether these findings are generalizable to more complex ecosystems, such as woodlands. We monitored invertebrate community reassembly over 5 yr of experimental woodland restoration at the TreeDivNet Ridgefield site in southwest Australia, testing the effects of woody plant species richness and herb-layer manipulation on invertebrate community structure and ant species composition. From 2010 to 2014, we sampled ground-dwelling invertebrates using pitfall traps in herbicide vs. no-herbicide subplots nested within each of 10 woody plant treatments varying in richness from zero (bare controls) to eight species, which produced a total of 211, 235 invertebrates, including 98, 979 ants belonging to 74 species. In mixed model analyses, the presence of woody plants was an important driver of faunal community reassembly (relative to bare control plots), but faunal responses to woody plant treatment combinations were idiosyncratic and unrelated to woody plant richness across treatments. We also found that a herbicide-induced reduction in herbaceous plant cover and richness had a positive effect on ant richness and caused more rapid convergence of invertebrate community composition toward the composition of a woodland reference site. These findings show that woody plant richness did not have direct positive effects on the diversity and community reassembly trajectories of higher trophic levels in our woodland system. From a management perspective, this suggests that even low-diversity restoration or carbon sequestration plantings can potentially lead to faunal reassembly outcomes

  16. Electrofusion of plant cell protoplasts under microgravity--a D-2 spacelab experiment.

    PubMed

    Hoffmann, E; Schonherr, K; Johann, P; Hampp, R; von Keller, A; Voeste, D; Barth, S; Schnabl, H; Baumann, T; Eisenbeiss, M; Reinhard, E

    1995-11-01

    Plant cell protoplasts, derived from sexually incompatible plant species, have proved to be a good system for somatic hybridization by electrofusion. Under microgravity, an increase in fusion yield can be expected, especially if the parental cells differ markedly in size or specific density. On the D-2 spacelab mission flown in 1993, electrofusion experiments were performed with three different objects, i.e. tobacco as model system, Helianthus as an important crop, and Digitalis as a plant of pharmacological interest. The resulting fusion products were cultivated (along with parental cells) for 10 days under microgravity, and subsequently regenerated on ground for biochemical analysis. Results are presented on the observation of the fusion process during flight, heterofusion yields, ultrastructural investigation of fusion products immediately after fusion, and characterization of the resulting hybrids. The results are interpreted on the background of earlier microgravity-experiments on sounding rockets or parabolic flights.

  17. Plant growth during the Greenhouse II experiment on the Mir orbital station

    NASA Technical Reports Server (NTRS)

    Salisbury, F. B.; Campbell, W. F.; Carman, J. G.; Bingham, G. E.; Bubenheim, D. L.; Yendler, B.; Sytchev, V.; Levinskikh, M. A.; Ivanova, I.; Chernova, L.; Podolsky, I.

    2003-01-01

    We carried out three experiments with Super Dwarf wheat in the Bulgarian/Russian growth chamber Svet (0.1 m2 growing area) on the Space Station Mir. This paper mostly describes the first of these NASA-supported trials, began on Aug. 13, 1995. Plants were sampled five times and harvested on Nov. 9 after 90 days. Equipment failures led to low irradiance (3, then 4 of 6 lamp sets failed), instances of high temperatures (ca. 37 degrees C), and sometimes excessive substrate moisture. Although plants grew for the 90 d, no wheat heads were produced. Considering the low light levels, plants were surprisingly green, but of course biomass production was low. Plants were highly disoriented (low light, mirror walls?). Fixed and dried samples and the root module were returned on the U.S. Shuttle Atlantis on Nov. 20, 1995. Samples of the substrate, a nutrient-charged zeolite called Balkanine, were taken from the root module, carefully examined for roots, weighed, dried, and reweighed. The Svet control unit and the light bank were shipped to Moscow. An experiment validation test (EVT) of plant growth and experimental procedures, carried out in Moscow, was highly successful. Equipment built in Utah to measure CO2, H2O vapor, irradiance, air and leaf (IR) temperature, O2, pressure, and substrate moisture worked well in the EVT and in space. After this manuscript was first prepared, plants were grown in Mir with a new light bank and controller for 123 d in late 1996 and 39 days in 1996/1997. Plants grew exceptionally well with higher biomass production than in any previous space experiment, but the ca. 280 wheat heads that were produced in 1996 contained no seeds. Ethylene in the cabin atmosphere was responsible. c2002 Published by Elsevier Science Ltd on behalf of COSPAR.

  18. Plant growth during the greenhouse II experiment on the Mir orbital station

    NASA Astrophysics Data System (ADS)

    Salisbury, F. B.; Campbell, W. F.; Carman, J. G.; Bingham, G. E.; Bubenheim, D. L.; Yendler, B.; Sytchev, V.; Levinskikh, M. A.; Ivanova, I.; Chernova, L.; Podolsky, I.

    We carried out three experiments with Super Dwarf wheat in the Bulgarian/Russian growth chamber Svet (0.1 m2 growing area) on the Space Station Mir. This paper mostly describes the first of these NASA-supported trials, began on Aug. 13, 1995. Plants were sampled five times and harvested on Nov. 9 after 90 days. Equipment failures led to low irradiance (3, then 4 of 6 lamp sets failed), instances of high temperatures (ca. 37 °C), and sometimes excessive substrate moisture. Although plants grew for the 90 d, no wheat heads were produced. Considering the low light levels, plants were surprisingly green, but of course biomass production was low. Plants were highly disoriented (low light, mirror walls?). Fixed and dried samples and the root module were returned on the U.S. Shuttle Atlantis on Nov. 20, 1995. Samples of the substrate, a nutrient-charged zeolite called Balkanine, were taken from the root module, carefully examined for roots, weighed, dried, and reweighed. The Svet control unit and the light bank were shipped to Moscow. An experiment validation test (EVT) of plant growth and experimental procedures, carried out in Moscow, was highly successful. Equipment built in Utah to measure CO2, H2O vapor, irradiance, air and leaf (IR) temperature, O2, pressure, and substrate moisture worked well in the EVT and in space. After this manuscript was first prepared, plants were grown in Mir with a new light bank and controller for 123 d in late 1996 and 39 days in 1996/1997. Plants grew exceptionally well with higher biomass production than in any previous space experiment, but the ca. 280 wheat heads that were produced in 1996 contained no seeds. Ethylene in the cabin atmosphere was responsible.

  19. The negative feedback molecular mechanism which regulates excitation level in the plant photosynthetic complex LHCII: towards identification of the energy dissipative state.

    PubMed

    Zubik, Monika; Luchowski, Rafal; Puzio, Michal; Janik, Ewa; Bednarska, Joanna; Grudzinski, Wojciech; Gruszecki, Wieslaw I

    2013-03-01

    Overexcitation of the photosynthetic apparatus is potentially dangerous because it can cause oxidative damage. Photoprotection realized via the feedback de-excitation in the pigment-protein light-harvesting complex LHCII, embedded in the chloroplast lipid environment, was studied with use of the steady-state and time-resolved fluorescence spectroscopy techniques. Illumination of LHCII results in the pronounced singlet excitation quenching, demonstrated by decreased quantum yield of the chlorophyll a fluorescence and shortening of the fluorescence lifetimes. Analysis of the 77K chlorophyll a fluorescence emission spectra reveals that the light-driven excitation quenching in LHCII is associated with the intensity increase of the spectral band in the region of 700nm, relative to the principal band at 680nm. The average chlorophyll a fluorescence lifetime at 700nm changes drastically upon temperature decrease: from 1.04ns at 300K to 3.63ns at 77K. The results of the experiments lead us to conclude that: (i) the 700nm band is associated with the inter-trimer interactions which result in the formation of the chlorophyll low-energy states acting as energy traps and non-radiative dissipation centers; (ii) the Arrhenius analysis, supported by the results of the FTIR measurements, suggests that the photo-reaction can be associated with breaking of hydrogen bonds. Possible involvement of photo-isomerization of neoxanthin, reported previously (Biochim. Biophys. Acta 1807 (2011) 1237-1243) in generation of the low-energy traps in LHCII is discussed.

  20. Phenological response of tundra plants to background climate variation tested using the International Tundra Experiment.

    PubMed

    Oberbauer, S F; Elmendorf, S C; Troxler, T G; Hollister, R D; Rocha, A V; Bret-Harte, M S; Dawes, M A; Fosaa, A M; Henry, G H R; Høye, T T; Jarrad, F C; Jónsdóttir, I S; Klanderud, K; Klein, J A; Molau, U; Rixen, C; Schmidt, N M; Shaver, G R; Slider, R T; Totland, Ø; Wahren, C-H; Welker, J M

    2013-08-19

    The rapidly warming temperatures in high-latitude and alpine regions have the potential to alter the phenology of Arctic and alpine plants, affecting processes ranging from food webs to ecosystem trace gas fluxes. The International Tundra Experiment (ITEX) was initiated in 1990 to evaluate the effects of expected rapid changes in temperature on tundra plant phenology, growth and community changes using experimental warming. Here, we used the ITEX control data to test the phenological responses to background temperature variation across sites spanning latitudinal and moisture gradients. The dataset overall did not show an advance in phenology; instead, temperature variability during the years sampled and an absence of warming at some sites resulted in mixed responses. Phenological transitions of high Arctic plants clearly occurred at lower heat sum thresholds than those of low Arctic and alpine plants. However, sensitivity to temperature change was similar among plants from the different climate zones. Plants of different communities and growth forms differed for some phenological responses. Heat sums associated with flowering and greening appear to have increased over time. These results point to a complex suite of changes in plant communities and ecosystem function in high latitudes and elevations as the climate warms.

  1. Pharmacist-managed dose adjustment feedback using therapeutic drug monitoring of vancomycin was useful for patients with methicillin-resistant Staphylococcus aureus infections: a single institution experience

    PubMed Central

    Hirano, Ryuichi; Sakamoto, Yuichi; Kitazawa, Junichi; Yamamoto, Shoji; Tachibana, Naoki

    2016-01-01

    Background Vancomycin (VCM) requires dose adjustment based on therapeutic drug monitoring. At Aomori Prefectural Central Hospital, physicians carried out VCM therapeutic drug monitoring based on their experience, because pharmacists did not participate in the dose adjustment. We evaluated the impact of an Antimicrobial Stewardship Program (ASP) on attaining target VCM trough concentrations and pharmacokinetics (PK)/pharmacodynamics (PD) parameters in patients with methicillin-resistant Staphylococcus aureus (MRSA) infections. Materials and methods The ASP was introduced in April 2012. We implemented a prospective audit of prescribed VCM dosages and provided feedback based on measured VCM trough concentrations. In a retrospective pre- and postcomparison study from April 2007 to December 2011 (preimplementation) and from April 2012 to December 2014 (postimplementation), 79 patients were treated for MRSA infection with VCM, and trough concentrations were monitored (pre, n=28; post, n=51). In 65 patients (pre, n=15; post, n=50), 24-hour area under the concentration–time curve (AUC 0–24 h)/minimum inhibitory concentration (MIC) ratios were calculated. Results Pharmacist feedback, which included recommendations for changing dose or using alternative anti-MRSA antibiotics, was highly accepted during postimplementation (88%, 29/33). The number of patients with serum VCM concentrations within the therapeutic range (10–20 μg/mL) was significantly higher during postimplementation (84%, 43/51) than during preimplementation (39%, 11/28) (P<0.01). The percentage of patients who attained target PK/PD parameters (AUC 0–24 h/MIC >400) was significantly higher during postimplementation (84%, 42/50) than during preimplementation (53%, 8/15; P=0.013). There were no significant differences in nephrotoxicity or mortality rate. Conclusion Our ASP increased the percentage of patients that attained optimal VCM trough concentrations and PK/PD parameters, which contributed to the

  2. Improvements in and actual performance of the Plant Experiment Unit onboard Kibo, the Japanese experiment module on the international space station

    NASA Astrophysics Data System (ADS)

    Yano, Sachiko; Kasahara, Haruo; Masuda, Daisuke; Tanigaki, Fumiaki; Shimazu, Toru; Suzuki, Hiromi; Karahara, Ichirou; Soga, Kouichi; Hoson, Takayuki; Tayama, Ichiro; Tsuchiya, Yoshikazu; Kamisaka, Seiichiro

    2013-03-01

    In 2004, Japan Aerospace Exploration Agency developed the engineered model of the Plant Experiment Unit and the Cell Biology Experiment Facility. The Plant Experiment Unit was designed to be installed in the Cell Biology Experiment Facility and to support the seed-to-seed life cycle experiment of Arabidopsis plants in space in the project named Space Seed. Ground-based experiments to test the Plant Experiment Unit showed that the unit needed further improvement of a system to control the water content of a seedbed using an infrared moisture analyzer and that it was difficult to keep the relative humidity inside the Plant Experiment Unit between 70 and 80% because the Cell Biology Experiment Facility had neither a ventilation system nor a dehumidifying system. Therefore, excess moisture inside the Cell Biology Experiment Facility was removed with desiccant bags containing calcium chloride. Eight flight models of the Plant Experiment Unit in which dry Arabidopsis seeds were fixed to the seedbed with gum arabic were launched to the International Space Station in the space shuttle STS-128 (17A) on August 28, 2009. Plant Experiment Unit were installed in the Cell Biology Experiment Facility with desiccant boxes, and then the Space Seed experiment was started in the Japanese Experiment Module, named Kibo, which was part of the International Space Station, on September 10, 2009 by watering the seedbed and terminated 2 months later on November 11, 2009. On April 19, 2010, the Arabidopsis plants harvested in Kibo were retrieved and brought back to Earth by the space shuttle mission STS-131 (19A). The present paper describes the Space Seed experiment with particular reference to the development of the Plant Experiment Unit and its actual performance in Kibo onboard the International Space Station. Downlinked images from Kibo showed that the seeds had started germinating 3 days after the initial watering. The plants continued growing, producing rosette leaves, inflorescence

  3. Modeling climate related feedback processes

    SciTech Connect

    Elzen, M.G.J. den; Rotmans, J. )

    1993-11-01

    In order to assess their impact, the feedbacks which at present can be quantified reasonably are built into the Integrated Model to Assess the Greenhouse Effect (IMAGE). Unlike previous studies, this study describes the scenario- and time-dependent role of biogeochemical feedbacks. A number of simulation experiments are performed with IMAGE to project climate changes. Besides estimates of their absolute importance, the relative importance of individual biogeochemical feedbacks is considered by calculating the gain for each feedback process. This study focuses on feedback processes in the carbon cycle and the methane (semi-) cycle. Modeled feedbacks are then used to balance the past and present carbon budget. This results in substantially lower projections for atmospheric carbon dioxide than the Intergovernmental Panel on Climate Change (IPCC) estimates. The difference is approximately 18% from the 1990 level for the IPCC [open quotes]Business-as-Usual[close quotes] scenario. Furthermore, the IPCC's [open quotes]best guess[close quotes] value of the CO[sub 2] concentration in the year 2100 falls outside the uncertainty range estimated with our balanced modeling approach. For the IPCC [open quotes]Business-as-Usual[close quotes] scenario, the calculated total gain of the feedbacks within the carbon cycle appears to be negative, a result of the dominant role of the fertilization feedback. This study also shows that if temperature feedbacks on methane emissions from wetlands, rice paddies, and hydrates do materialize, methane concentrations might be increased by 30% by 2100. 70 refs., 17 figs., 7 tabs.

  4. The Art of Giving Online Feedback

    ERIC Educational Resources Information Center

    Leibold, Nancyruth; Schwarz, Laura Marie

    2015-01-01

    The cultivation of providing online feedback that is positive, effective, and enhances the learning experience is a valuable educator skill. Acquisition of the art of providing feedback is through education, practice, and faculty development. This article provides information about the best practices for delivering online feedback to learners. An…

  5. Culturing immobilized plant cells for the TUBUL space experiments on the DELTA and 12S Missions

    NASA Astrophysics Data System (ADS)

    Sieberer, Björn J.; Emons, Anne Mie C.; Vos, Jan W.

    2007-09-01

    For the TUBUL experiments during the DELTA mission in April 2004 and 12S mission in March/April 2006 on board the Soyuz capsule and the International Space Station we developed a method to culture and chemically fix plant suspension culture cells. The aim of the ten day experiment was to investigate the effect of microgravity on single plant cells. Fully automated experiment cassettes (Plunger Box Units) were developed by Centre for Concepts in Mechatronics (Nuenen, the Netherlands). Tobacco BY- 2 cells were immobilized in a semi- solid agarose matrix that was reinforced by a nylon mesh. This assembly allowed liquid medium refreshment, oxygen supply and chemical fixation, including a post- fixative wash. The method was optimized for post- flight analysis of cell structure, shape and size, cell division, and the microtubule cytoskeleton. The viability of cells in the agarose matrix was similar to cells grown in liquid medium under laboratory conditions, only the stationary growth phase was reached six days later.

  6. Advanced Reactor Licensing: Experience with Digital I&C Technology in Evolutionary Plants

    SciTech Connect

    Wood, RT

    2004-09-27

    This report presents the findings from a study of experience with digital instrumentation and controls (I&C) technology in evolutionary nuclear power plants. In particular, this study evaluated regulatory approaches employed by the international nuclear power community for licensing advanced l&C systems and identified lessons learned. The report (1) gives an overview of the modern l&C technologies employed at numerous evolutionary nuclear power plants, (2) identifies performance experience derived from those applications, (3) discusses regulatory processes employed and issues that have arisen, (4) captures lessons learned from performance and regulatory experience, (5) suggests anticipated issues that may arise from international near-term deployment of reactor concepts, and (6) offers conclusions and recommendations for potential activities to support advanced reactor licensing in the United States.

  7. Testing hypotheses for exotic plant success: parallel experiments in the native and introduced ranges.

    PubMed

    Williams, Jennifer L; Auge, Harald; Maron, John L

    2010-05-01

    A central question in ecology concerns how some exotic plants that occur at low densities in their native range are able to attain much higher densities where they are introduced. This question has remained unresolved in part due to a lack of experiments that assess factors that affect the population growth or abundance of plants in both ranges. We tested two hypotheses for exotic plant success: escape from specialist insect herbivores and a greater response to disturbance in the introduced range. Within three introduced populations in Montana, USA, and three native populations in Germany, we experimentally manipulated insect herbivore pressure and created small-scale disturbances to determine how these factors affect the performance of houndstongue (Cynoglossum officinale), a widespread exotic in western North America. Herbivores reduced plant size and fecundity in the native range but had little effect on plant performance in the introduced range. Small-scale experimental disturbances enhanced seedling recruitment in both ranges, but subsequent seedling survival was more positively affected by disturbance in the introduced range. We combined these experimental results with demographic data from each population to parameterize integral projection population models to assess how enemy escape and disturbance might differentially influence C. officinale in each range. Model results suggest that escape from specialist insects would lead to only slight increases in the growth rate (lambda) of introduced populations. In contrast, the larger response to disturbance in the introduced vs. native range had much greater positive effects on lambda. These results together suggest that, at least in the regions where the experiments were performed, the differences in response to small disturbances by C. officinale contribute more to higher abundance in the introduced range compared to at home. Despite the challenges of conducting experiments on a wide biogeographic scale and the

  8. The main goals of experiments with the higher plants in the project MARS - 500.

    NASA Astrophysics Data System (ADS)

    Sychev, Vladimir; Levinskikh, Margarita; Podolsky, Igor; Gushin, Vadim; Bingham, Gail; Bates, Scott

    At the present step of development of manned flight to Mars there is a current opinion that including a greenhouse in the composition of Life Support Systems (LSS) of Martian expedition would essentially improve a spacecraft habitat conditions and also would have impact to preventing of a number of possible consequences of continuous presence of human in artificial environment. Development of design objectives of future space greenhouses applicable for conditions of Martian expedition should be based, in our opinion, not only on the results of real space experiments, conducted onboard of orbital stations, but also on the results of ground-based experiments. In connection with above considerations there is a number of technological, biological and psychological experiments is planned to be conducted in the frame of MARS-500 project to resolve questions related to incorporation of higher plants in LSS of inter-planetary flights. The questions include: testing of developed elements of the greenhouse construction and methods for cultivation of vegetables under conditions of imitation of the flight of Martian expedition; selection of breeds and species of vegetables, characterized by high speed of biomass accumulation, attractive taste and appearance; investigation of growth, development and metabolism of plants under long-term continuous cultivation in manned pressurized object; comparison of the productivity of the plants as a function of utilization of different light source; determination of maximum amount of planted biomass of the plants and number of possible vegetation under conditions of long-term utilization of vegetation chamber of the greenhouse without substrate replacement; investigation of crops dietetic preferences of crew members; estimation of quality of plant biomass using seeding of the plants by microorganisms and nitrates and vitamins content as markers; development and approbation of methodical approaches to estimation of psychological factors of

  9. Plant growth responses to inorganic environmental contaminants are density-dependent: experiments with copper sulfate, barley and lettuce.

    PubMed

    Hansi, Mari; Weidenhamer, Jeffrey D; Sinkkonen, Aki

    2014-01-01

    The density-dependence of terrestrial plant-plant interactions in the presence of toxins has previously been explored using biodegradable compounds. We exposed barley and lettuce to four copper concentrations at four stand densities. We hypothesized that toxin effects would decrease and Cu uptake would increase at increasing plant densities. We analyzed toxin effects by (a) comparing plant biomasses and (b) using a recent regression model that has a separate parameter for the interaction of resource competition and toxin interference. Plant response to Cu was density-dependent in both experiments. Total Cu uptake by barley increased and the dose per plant decreased as plant density increased. This study is the first to demonstrate that plant density mediates plant response to metals in soil in a predictable way. This highlights the need to explore the mechanisms for and consequences of these effects, and to integrate the use of several plant densities into standard ecotoxicological testing.

  10. Long Term Thawing Experiments on Intact Cores of Arctic Mineral Cryosol: Implications for Greenhouse Gas Feedbacks from Global Warming

    NASA Astrophysics Data System (ADS)

    Onstott, T. C.; Stackhouse, B. T.; Lau, C. Y. M.; Whyte, L. G.; Pfiffner, S. M.; Vishnivetskaya, T. A.

    2015-12-01

    Mineral cryosols comprise >87% of Arctic tundra. Much attention has focused on high-organic carbon cryosols and how they will respond to global warming. The biogeochemical processes related to the greenhouse gas release from mineral cryosols, however, have not been fully explored. To this end, seventeen intact cores of active layer and underlying permafrost of mineral cryosol from Axel Heiberg Island, Nunavut, Canada, were subjected to 85 weeks of thawing at 4.5°C under various treatment regimes. The fluxes of CO2 and CH4 across the atmosphere-soil boundary and vertical profiles of the gas and water chemistry and the metagenomes were determined. The flux measurements were compared to those of microcosms and field measurements. The main conclusions were as follows: 1) CO2 emission rates from the intact cores do not behave in the typical fast to slow carbon pool fashion that typify microcosm experiments. The CO2 emission rates from the intact cores were much slower than those from the microcosm initially, but steadily increased with time, overtaking and then exceeding microcosm release rates after one year. 2) The increased CO2 flux from thawing permafrost could not be distinguished from that of control cores until after a full year of thawing. 3) Atmospheric CH4 oxidation was present in all intact cores regardless of whether they are water saturated or not, but after one year it had diminished to the point of being negligible. Over that same time the period the metagenomic data recorded a significant decline in the proportion of high-affinity methanotrophs. 4) Thaw slumps in the cores temporarily increased the CH4 oxidation and the CO2 emission rates. 5) The microbial community structures varied significantly by depth with methanotrophs being more abundant in above 35 cm depth than below 35 cm depth. 6) Other than the diminishment of Type II methanotrophs, the microbial community structure varied little after one week of thawing, nor even after 18 months of thaw.

  11. The influence of cooling on the advance of lava flows: insights from analogue experiments on the feedbacks between flow dynamics and thermal structure

    NASA Astrophysics Data System (ADS)

    Garel, F.; Kaminski, E.; Tait, S.; Limare, A.

    2012-12-01

    During an effusive volcanic eruption, the crisis management is mainly based on the prediction of lava flows advance and its velocity. The spreading of a lava flow, seen as a gravity current, depends on its "effective rheology" and the eruptive mass flux. These two parameters are not known a priori during an eruption and a key question is how to evaluate them in near real-time (rather than afterwards.) There is no generic macroscopic model for the rheology of an advancing lava flow, and analogue modelling is a precious tool to empirically estimate the rheology of a complex flow. We investigate through laboratory experiments the simultaneous spreading and cooling of horizontal currents fed at constant rate from a point source. The materials used are silicone oil (isoviscous), and poly-ethylene glycol (PEG) wax injected in liquid state and solidiying during its advance. In the isoviscous case, the temperature field is a passive tracer of the flow dynamics, whereas in the PEG experiments there is a feedback between the cooling of the flow and its effective rheology. We focus on the evolution of the current area and of the surface thermal structure, imaged with an infrared camera, to assess how the thermal structure can be related to the flow rate. The flow advance is continuous in the viscous case, and follows the predictions of Huppert (1982); in that case the surface temperature become steady after a transient time and the radiated heat flux is shown to be proportional to the input rate. For the PEG experiments, the spreading occurs through an alternation of stagnation and overflow phases, with a mean spreading rate decreasing as the experiment goes on. As in the case of lava flows, these experiments can exhibit a compound flow field, solid levees, thermal erosion, liquid overflows and channelization. A key observation is that the effective rheology of the solifying PEG material depends on the input flow rate, with high input rates yielding a rheology closer to the

  12. Factors Influencing Oral Corrective Feedback Provision in the Spanish Foreign Language Classroom: Investigating Instructor Native/Nonnative Speaker Status, SLA Education, & Teaching Experience

    ERIC Educational Resources Information Center

    Gurzynski-Weiss, Laura

    2010-01-01

    The role of interactional feedback has been a critical area of second language acquisition (SLA) research for decades and while findings suggest interactional feedback can facilitate SLA, the extent of its influence can vary depending on a number of factors, including the native language of those involved in communication. Although studies have…

  13. The use of heavy nitrogen in quantitative proteomics experiments in plants.

    PubMed

    Arsova, Borjana; Kierszniowska, Sylwia; Schulze, Waltraud X

    2012-02-01

    In the growing field of plant systems biology, there is an undisputed need for methods allowing accurate quantitation of proteins and metabolites. As autotrophic organisms, plants can easily metabolize different nitrogen isotopes, resulting in proteins and metabolites with distinct molecular mass that can be separated on a mass spectrometer. In comparative quantitative experiments, treated and untreated samples are differentially labeled by nitrogen isotopes and jointly processed, thereby minimizing sample-to-sample variation. In recent years, heavy nitrogen labeling has become a widely used strategy in quantitative proteomics and novel approaches have been developed for metabolite identification. Here, we present an overview of currently used experimental strategies in heavy nitrogen labeling in plants and provide background on the history and function of this quantitation technique.

  14. Experience gained with the Synroc demonstration plant at ANSTO and its relevance to plutonium immobilization

    SciTech Connect

    Jostsons, A.; Ridal, A.; Mercer, D.J.; Vance, E.R.L.

    1996-05-01

    The Synroc Demonstration Plant (SDP) was designed and constructed at Lucas Heights to demonstrate the feasibility of Synroc production on a commercial scale (10 kg/hr) with simulated Purex liquid HLW. Since commissioning of the SDP in 1987, over 6000 kg of Synroc has been fabricated with a range of feeds and waste loadings. The SDP utilises uniaxial hot-pressing to consolidate Synroc. Pressureless sintering and hot-isostatic pressing have also been studied at smaller scales. The results of this extensive process development have been incorporated in a conceptual design for a radioactive plant to condition HLW from a reprocessing plant with a capacity to treat 800 tpa of spent LWR fuel. Synroic containing TRU, including Pu, and fission products has been fabricated and characterised in a glove-box facility and hot cells, respectively. The extensive experience in processing of Synroc over the past 15 years is summarised and its relevance to immobilization of surplus plutonium is discussed.

  15. [Genetics of plant development: integrating data from different observations and experiments in databases].

    PubMed

    Omel'ianchuk, N A; Mironova, V V; Kolchanov, N A

    2009-11-01

    Genetics of plant development as a scientific discipline integrates experimental evidence from such different fields of biology as embryology, plant anatomy, molecular biology, and genetics, and studies their relationships with ontogeny. To date, traditional publication of scientific studies in form of articles is supplemented by presenting the results of extensive genome-scale experiments in genomics, transcriptomics, proteomics, and phenomics in databases. The information burst, cased both by genome-scale studies and growth in the number of publications, requires the development of general standards of annotating data from different sources for their integration and comparison. In this review, we present classification and analysis of existing databases, in which the user can find various kinds of information essential for studying developmental genetics of plants, and discuss problems of data integration both within the informational resources and among them.

  16. Plant experiments with light-emitting diode module in Svet space greenhouse

    NASA Astrophysics Data System (ADS)

    Ilieva, Iliana; Ivanova, Tania; Naydenov, Yordan; Dandolov, Ivan; Stefanov, Detelin

    2010-10-01

    Light is necessary for photosynthesis and shoot orientation in the space plant growth facilities. Light modules (LM) must provide sufficient photosynthetic photon flux for optimal efficiency of photosynthetic processes and also meet the constraints for power, volume and mass. A new LM for Svet space greenhouse using Cree® XLamp® 7090 XR light-emitting diodes (LEDs) was developed. Monochromic LEDs emitting in the red, green, and blue regions of the spectrum were used. The LED-LM contains 36 LED spots - 30 LED spots with one red, green and blue LED and 6 LED spots with three red LEDs. Digital Multiplex Control Unit controls the LED spots and can set 231 levels of light intensity thus achieving Photosynthetic Photon Flux Density (PPFD) in the range 0-400 μmol m -2 s -1 and different percentages of the red, green and blue light, depending on the experimental objectives. Two one-month experiments with plants - lettuce and radicchio were carried out at 400 μmol m -2 s -1 PPFD (high light - HL) and 220 μmol m -2 s -1 PPFD (low light - LL) and 70% red, 20% green and 10% blue light composition. To evaluate the efficiency of photosynthesis, in vivo modulated chlorophyll fluorescence was measured by Pulse Amplitude Modulation (PAM) fluorometer on leaf discs and the following parameters: effective quantum yield of Photosystem II ( ΦPSII) and non-photochemical quenching (NPQ) were calculated. Both lettuce and radicchio plants grown at LL express higher photochemical activity of Photosystem II (PSII) than HL grown plants, evaluated by ΦPSII. Accelerated rise in NPQ in both LL grown plants was observed, while steady state NPQ values were higher in LL grown lettuce plants and did not differ in LL and HL grown radicchio plants. The extent of photoinhibition process in both plants was evaluated by changes in malonedialdehyde (MDA) concentration, peroxidase (POX) activity and hydrogen peroxide (H 2O 2) content. Accumulation of high levels of MDA and increased POX activity

  17. Insect herbivory and grass competition in a calcareous grassland: results from a plant removal experiment

    NASA Astrophysics Data System (ADS)

    Corcket, Emmanuel; Callaway, Ragan M.; Michalet, Richard

    2003-07-01

    We compared the effects of herbivory by grasshoppers and neighbourhood competition on two dominant grasses, Bromus erectus and Brachypodium pinnatum, in a calcareous grassland in the French Alps. In a fully factorial design, herbivory was reduced by insecticide spraying and competition was reduced by removal of neighbouring plants. The effects of herbivory and competition were species-dependent. Bromus, a stress-tolerant species, was strongly affected by competition, but not by herbivory. In contrast, the more competitive species, Brachypodium, was negatively affected by herbivory, but only when neighbouring vegetation was removed. The greatest herbivory pressure on isolated targets of Brachypodium is likely to be due to the indirect effects of experimental gaps, i.e. more favourable microclimatic and foraging conditions for grasshoppers. This suggests that herbivory by insects may be a confounding factor in many plant removal experiments. Field experiments designed to study the combined effects of competition and herbivory should take into account the indirect effects induced by experimental gaps.

  18. U.S. Nuclear Power Plant Operating Cost and Experience Summaries

    SciTech Connect

    Reid, RL

    2003-09-18

    The ''U.S. Nuclear Power Plant Operating Cost and Experience Summaries'' (NUREG/CR-6577, Supp. 2) report has been prepared to provide historical operating cost and experience information on U.S. commercial nuclear power plants during 2000-2001. Costs incurred after initial construction are characterized as annual production costs, which represent fuel and plant operating and maintenance expenses, and capital expenditures related to facility additions/modifications, which are included in the plant capital asset base. As discussed in the report, annual data for these two cost categories were obtained from publicly available reports and must be accepted as having different degrees of accuracy and completeness. Treatment of inconclusive and incomplete data is discussed. As an aid to understanding the fluctuations in the cost histories, operations summaries for each nuclear unit are provided. The intent of these summaries is to identify important operating events; refueling, major maintenance, and other significant outages; operating milestones; and significant licensing or enforcement actions. Information used in the summaries is condensed from operating reports submitted by the licensees, the Nuclear Regulatory Commission (NRC) database for enforcement actions, and outage reports.

  19. Capacity Value of Wind Plants and Overview of U.S. Experience (Presentation)

    SciTech Connect

    Milligan, M.

    2011-08-01

    This presentation provides an overview and summary of the capacity value of wind power plants, based primarily on the U.S. experience. Resource adequacy assessment should explicitly consider risk. Effective load carrying capability (ELCC) captures each generators contribution to resource adequacy. On their own, reserve margin targets as a percent of peak can't capture risks effectively. Recommend benchmarking reliability-based approaches with others.

  20. Biocompatibility studies in preparation for a spaceflight experiment on plant tropisms (TROPI)

    NASA Astrophysics Data System (ADS)

    Kiss, John Z.; Kumar, Prem; Bowman, Robert N.; Steele, Marianne K.; Eodice, Michael T.; Correll, Melanie J.; Edelmann, Richard E.

    The interaction among tropisms is important in determining the growth form of a plant. Thus, we have developed a project to study the interaction between two key tropistic responses (i.e., gravitropism and phototropism) to be performed in microgravity on the International Space Station (ISS). Specifically, we are interested in the role of red-light-absorbing phytochrome pigments in modulating tropisms in seedlings of Arabidopsis thaliana. This project, termed TROPI for tropisms, is to be performed on the European Modular Cultivation System (EMCS), which provides an incubator with atmospheric control, lighting, and high-resolution video. The EMCS has two rotating centrifuge platforms so that our experiments can be performed at microgravity, 1g (control), and fractional g-levels. In order to optimize these spaceflight experiments, we have continued ground-based technical tests as well as basic science experiments. Since the seeds will have to be stored for several months in hardware prior to use on the ISS, we tested the effects of long-term storage of seeds in the TROPI EUE (experimental unique equipment) on germination rates and plant growth. The EUE consists of five seedling cassettes with LED lighting and a water delivery system in an Experimental Container (EC). Preliminary studies showed that there were reduced seed germination and plant growth after several months of storage in the EUE. We determined that the likely source of this biocompatibility problem was the conformal coating of electrical components of the EUE, which was required by NASA for safety reasons. In order to alleviate this problem, carbon filters were added to both the seedling cassettes and to the base of the EC. We expect that these improvements to the hardware will result in healthy plants capable of robust tropistic responses in our spaceflight experiments.

  1. Experiences concerning the service life of rubber linings applied in flue gas desulfurization plants

    SciTech Connect

    Berger, W.

    1999-11-01

    Since the beginning of the eighties scrubbers and other components in European FGD plants have been protected against corrosion using rubber lining. Extensive experience is available based on service lives of rubber lining of more than 15 years. The paper will consider the various rubber types and curing systems used. While the USA and Japan had already begun retrofitting their existing coal-fired power stations with flue gas desulfurization (FGD) plants in the seventies, Germany followed suit in the eighties as a result of the decree issued for large-scale firing plants. Concurrent with this development retrofitting has also been enhanced in other European countries like Austria and the Netherlands, later followed by Denmark, Finland and England. After the collapse of the Eastern Bloc retrofitting work has been implemented in Eastern Germany, Poland, the Czech Republic and Slovakia. Today FGD plants are being put into operation in Spain, Italy, Turkey and Greece or are on the verge of being put into service. More than 150 plants of this kind are operated by using the wet-scrubbing process with limestone or calcium hydroxide suspensions.

  2. Do exotic plants lose resistance to pathogenic soil biota from their native range? A test with Solidago gigantea.

    PubMed

    Maron, John L; Luo, Wenbo; Callaway, Ragan M; Pal, Robert W

    2015-10-01

    Native plants commonly suffer from strong negative plant-soil feedbacks. However, in their non-native ranges species often escape from these negative feedbacks, which indicates that these feedbacks are generated by at least partially specialized soil biota. If so, introduced plants might evolve the loss of resistance to pathogens in their former native range, as has been proposed for the loss of resistance to specialized herbivores. We compared the magnitude of plant-soil feedbacks experienced by native and exotic genotypes of the perennial forb, Solidago gigantea. Feedbacks were assessed in soil collected across 14 sites sampled across the western part of Solidago's native range in the US. Both native and exotic genotypes of Solidago suffered consistently negative and broadly similar plant-soil feedbacks when grown in North American soil. Although there was substantial variation among soils from different sites in the strength of feedbacks generated, the magnitude of feedbacks generated by North American genotypes of S. gigantea were strongly correlated with those produced in the same soil by European genotypes. Our results indicate that Solidago experiences strong negative soil feedbacks in native soil and that introduced genotypes of Solidago have not lost resistance to these negative effects of soil biota. Both genotypic and landscape-level effects can be important sources of variation in the strength of plant-soil feedbacks.

  3. Herbivory and Stoichiometric Feedbacks to Primary Production.

    PubMed

    Krumins, Jennifer Adams; Krumins, Valdis; Forgoston, Eric; Billings, Lora; van der Putten, Wim H

    2015-01-01

    Established theory addresses the idea that herbivory can have positive feedbacks on nutrient flow to plants. Positive feedbacks likely emerge from a greater availability of organic carbon that primes the soil by supporting nutrient turnover through consumer and especially microbially-mediated metabolism in the detrital pool. We developed an entirely novel stoichiometric model that demonstrates the mechanism of a positive feedback. In particular, we show that sloppy or partial feeding by herbivores increases detrital carbon and nitrogen allowing for greater nitrogen mineralization and nutritive feedback to plants. The model consists of differential equations coupling flows among pools of: plants, herbivores, detrital carbon and nitrogen, and inorganic nitrogen. We test the effects of different levels of herbivore grazing completion and of the stoichiometric quality (carbon to nitrogen ratio, C:N) of the host plant. Our model analyses show that partial feeding and plant C:N interact because when herbivores are sloppy and plant biomass is diverted to the detrital pool, more mineral nitrogen is available to plants because of the stoichiometric difference between the organisms in the detrital pool and the herbivore. This model helps to identify how herbivory may feedback positively on primary production, and it mechanistically connects direct and indirect feedbacks from soil to plant production.

  4. Comprehensive Assessment of Land Surface, Snow, and Soil Moisture-Climate Feedbacks by Multi-model Experiments of Land Surface Models under LS3MIP

    NASA Astrophysics Data System (ADS)

    Oki, T.; Kim, H.; Hurk, B. V. D.; Krinner, G.; Derksen, C.; Seneviratne, S. I.

    2015-12-01

    The solid and liquid water stored at the land surface has a large influence on the regional climate, its variability and its predictability, including effects on the energy and carbon cycles. Notably, snow and soil moisture affect surface radiation and flux partitioning properties, moisture storage and land surface memory. The Land surface, snow and soil moisture model inter-comparison project (LS3MIP) experiments address together the following objectives: an evaluation of the current state of land processes including surface fluxes, snow cover and soil moisture representation in CMIP6 DECK runs (LMIP-protoDECK) a multi-model estimation of the long-term terrestrial energy/water/carbon cycles, using the surface modules of CMIP6 models under observation constrained historical (land reanalysis) and projected future (impact assessment) conditions considering land use/land cover changes. (LMIP) an assessment of the role of snow and soil moisture feedbacks in the regional response to altered climate forcings, focusing on controls of climate extremes, water availability and high-latitude climate in historical and future scenario runs (LFMIP) an assessment of the contribution of land surface processes to the current and future predictability of regional temperature/precipitation patterns. (LFMIP) These LS3MIP outcomes will contribute to the improvement of climate change projections by reducing the systematic biases from the land surface component of climate models, and a better representation of feedback mechanisms related to snow and soil moisture in climate models. Further, LS3MIP will enable the assessment of probable historical changes in energy, water, and carbon cycles over land surfaces extending more than 100 years, including spatial variability and trends in global runoff, snow cover, and soil moisture that are hard to detect purely based on observations. LS3MIP will also enable the impact assessments of climate changes on hydrological regimes and available

  5. Feedback and assessment for clinical placements: achieving the right balance

    PubMed Central

    Burgess, Annette; Mellis, Craig

    2015-01-01

    During clinical placements, the provision of feedback forms an integral part of the learning process and enriches students’ learning experiences. The purpose of feedback is to improve the learner’s knowledge, skills, or behavior. Receipt of accurate feedback can help to narrow the gap between actual and desired performance. Effective and regular feedback has the potential to reinforce good practice and motivate the learner toward the desired outcome. Despite the obvious role of feedback in effective teaching and learning, a common complaint from students is that they do not receive adequate feedback. Unfortunately, skills in giving and receiving feedback are rarely taught to students or clinicians. This study aims to provide an understanding of the role of feedback within the learning process, consider consequences of inadequate or poorly given feedback, consider the barriers to the feedback process, provide practical guidelines for providing feedback, and consider the need for student and faculty development in feedback skills. PMID:26056511

  6. The feedback-related negativity is modulated by feedback probability in observational learning.

    PubMed

    Kobza, Stefan; Thoma, Patrizia; Daum, Irene; Bellebaum, Christian

    2011-12-01

    The feedback-related negativity (FRN), an event-related potentials (ERPs) component reflecting activity of the anterior cingulate cortex (ACC), has been shown to be modulated by feedback expectancy following active choices in feedback-based learning tasks. A general reduction of FRN amplitude has been described in observational feedback learning, raising the question whether FRN amplitude is modulated in a similar way in this type of learning. The present study investigated whether the FRN and the P300 - a second ERP component related to feedback processing - are modulated by feedback probability in observational learning. Thirty-two subjects participated in the experiment. They observed a virtual person choosing between two symbols and receiving positive or negative feedback. Learning about stimulus-specific feedback probabilities was assessed in active test trials without feedback. In addition, the bias to learn from positive or negative feedback and - in a subsample of 17 subjects - empathy scores were obtained. General FRN and P300 modulations by feedback probability were found across all subjects. Only for the FRN in learners, an interaction between probability and valence was observed. Larger FRN amplitudes for negative relative to positive feedback only emerged for the lowest outcome probability. The results show that feedback expectancy modulates FRN amplitude also in observational learning, suggesting a similar ACC function as in active learning. On the other hand, the modulation is only seen for very low feedback expectancy, which suggests that brain regions other than those of the reward system contribute to feedback processing in an observation setting.

  7. Changes in plant medium composition after a spaceflight experiment: Potassium levels are of special interest

    NASA Astrophysics Data System (ADS)

    Levine, Howard G.; Krikorian, A. D.

    2008-09-01

    We present results on the analysis of 100 mL medium samples extracted from sterilized foam (Smithers-Oasis, Kent OH) used to support the growth of a representative dicotyledon ( Haplopappus gracilis) and a representative monocotyledon ( Hemerocallis cv Autumn Blaze) in NASA's Plant Growth Unit (PGU) during a 5-day Space Shuttle flight and ground experiments. At recovery, the media remaining within replicate ( n = 5) foam blocks (for both the spaceflight and ground experiments) were extracted under vacuum, filtered and subjected to elemental analyses. A unique aspect of this experiment was that all plants were either aseptically-generated tissue culture propagated plantlets or aseptic seedling clones. The design of the PGU facilitated the maintenance of asepsis throughout the mission (confirmed by post-flight microbial sampling) and thus any possible impact of microorganisms on medium composition was eliminated. Concentration levels of some elements remained the same, while some decreased and others increased. There was a significant two-fold difference between the final concentrations of potassium when the Earth-based and microgravity experiments were contrasted.

  8. Facilitation and competition among invasive plants: a field experiment with alligatorweed and water hyacinth.

    PubMed

    Wundrow, Emily J; Carrillo, Juli; Gabler, Christopher A; Horn, Katherine C; Siemann, Evan

    2012-01-01

    Ecosystems that are heavily invaded by an exotic species often contain abundant populations of other invasive species. This may reflect shared responses to a common factor, but may also reflect positive interactions among these exotic species. Armand Bayou (Pasadena, TX) is one such ecosystem where multiple species of invasive aquatic plants are common. We used this system to investigate whether presence of one exotic species made subsequent invasions by other exotic species more likely, less likely, or if it had no effect. We performed an experiment in which we selectively removed exotic rooted and/or floating aquatic plant species and tracked subsequent colonization and growth of native and invasive species. This allowed us to quantify how presence or absence of one plant functional group influenced the likelihood of successful invasion by members of the other functional group. We found that presence of alligatorweed (rooted plant) decreased establishment of new water hyacinth (free-floating plant) patches but increased growth of hyacinth in established patches, with an overall net positive effect on success of water hyacinth. Water hyacinth presence had no effect on establishment of alligatorweed but decreased growth of existing alligatorweed patches, with an overall net negative effect on success of alligatorweed. Moreover, observational data showed positive correlations between hyacinth and alligatorweed with hyacinth, on average, more abundant. The negative effect of hyacinth on alligatorweed growth implies competition, not strong mutual facilitation (invasional meltdown), is occurring in this system. Removal of hyacinth may increase alligatorweed invasion through release from competition. However, removal of alligatorweed may have more complex effects on hyacinth patch dynamics because there were strong opposing effects on establishment versus growth. The mix of positive and negative interactions between floating and rooted aquatic plants may influence local

  9. Arbuscular mycorrhizae enhance metal lead uptake and growth of host plants under a sand culture experiment.

    PubMed

    Chen, Xin; Wu, Chunhua; Tang, Jianjun; Hu, Shuijin

    2005-07-01

    A sand culture experiment was conducted to investigate whether mycorrhizal colonization and mycorrhizal fungal vesicular numbers were influenced by metal lead, and whether mycorrhizae enhance host plants tolerance to metal lead. Metal lead was applied as Pb(NO3)2 in solution at three levels (0, 300 and 600 mg kg(-1) sand). Five mycorrhizal host plant species, Kummerowia striata (Thunb.) Schindl, Ixeris denticulate L., Lolium perenne L., Trifolium repens L. and Echinochloa crusgalli var. mitis were used to examine Pb-mycorrhizal interactions. The arbuscular mycorrhizal inoculum consisted of mixed spores of mycorrhizal fungal species directly isolated from orchard soil. Compared to the untreated control, both Pb concentrations reduced mycorrhizal colonization by 3.8-70.4%. Numbers of AM fungal vesicles increased by 13.2-51.5% in 300 mg Pb kg(-1) sand but decreased by 9.4-50.9% in 600 mg Pb kg(-1) sand. Mycorrhizae significantly enhanced Pb accumulation both in shoot by 10.2-85.5% and in root by 9.3-118.4%. Mycorrhizae also enhanced shoot biomass and shoot P concentration under both Pb concentrations. Root/shoot ratios of Pb concentration were higher in highly mycorrhizal plant species (K.striata, I. denticulate, and E. crusgalli var. mitis) than that in poorly mycorrhizal ones (L. perenne and T. repens,). Mycorrhizal inoculation increased the root/shoot ratio of Pb concentration of highly mycorrhizal plant species by 7.6-57.2% but did not affect the poorly mycorrhizal ones. In the treatments with 300 Pb mg kg(-1) sand, plant species with higher vesicular numbers tended to show higher root/shoot ratios of the Pb concentration. We suggest that under an elevated Pb condition, mycorrhizae could promote plant growth by increasing P uptake and mitigate Pb toxicity by sequestrating more Pb in roots.

  10. Feedback: Breakfast of Champions.

    ERIC Educational Resources Information Center

    Justman, Jeffrey J.

    Feedback is an important skill that people need to learn in life. Feedback is crucial in a public speaking class to improve speaking skills. Providing and receiving feedback is what champions feed on to be successful, thus feedback is called the "Breakfast of Champions." Feedback builds speakers' confidence. Providing in-depth feedback…

  11. Studies of Tampa Bay Region Power Plant Plumes during the Bay Region Atmospheric Chemistry Experiment (BRACE)

    NASA Astrophysics Data System (ADS)

    Watson, T. B.; Luke, W. T.; Arnold, J. R.; Gunter, L. R.

    2003-12-01

    The NOAA Air Resources Laboratory made aircraft measurements of chemical and meteorological parameters during 21 flights of the NOAA Twin Otter as part of the Bay Region Atmospheric Chemistry Experiment (BRACE). BRACE was conducted in May 2002. The aircraft flew horizontal transects upwind and downwind of the urban area on 13 of these flights to characterize the urban and power plant plumes. Vertical profiles from 60 to 3000 m MSL were made on most flights. Profiles were made over the Gulf of Mexico, Tampa Bay, and various land sites. On many flights, transects were located immediately downwind of the urban region and power plants and at successive distances farther downwind to characterize the horizontal distribution and chemical processing of the plumes as they aged. At each distance, data was collected during multiple passes at different altitudes to characterize the vertical structure. Many of the downwind passes were flown over the Gulf where sources are limited and the plumes can be observed in relative isolation. The contribution of the power plant plumes are analyzed to determine changes in the vertical and horizontal distribution of the plumes; horizontal fluxes of NOx, NOy, and ozone; production of ozone; deposition rates; and changes on successive days of regional background and concentration maxima caused by the power plant emissions.

  12. Designing microarray and RNA-Seq experiments for greater systems biology discovery in modern plant genomics.

    PubMed

    Yang, Chuanping; Wei, Hairong

    2015-02-01

    Microarray and RNA-seq experiments have become an important part of modern genomics and systems biology. Obtaining meaningful biological data from these experiments is an arduous task that demands close attention to many details. Negligence at any step can lead to gene expression data containing inadequate or composite information that is recalcitrant for pattern extraction. Therefore, it is imperative to carefully consider experimental design before launching a time-consuming and costly experiment. Contemporarily, most genomics experiments have two objectives: (1) to generate two or more groups of comparable data for identifying differentially expressed genes, gene families, biological processes, or metabolic pathways under experimental conditions; (2) to build local gene regulatory networks and identify hierarchically important regulators governing biological processes and pathways of interest. Since the first objective aims to identify the active molecular identities and the second provides a basis for understanding the underlying molecular mechanisms through inferring causality relationships mediated by treatment, an optimal experiment is to produce biologically relevant and extractable data to meet both objectives without substantially increasing the cost. This review discusses the major issues that researchers commonly face when embarking on microarray or RNA-seq experiments and summarizes important aspects of experimental design, which aim to help researchers deliberate how to generate gene expression profiles with low background noise but with more interaction to facilitate novel biological discoveries in modern plant genomics.

  13. Plant Growth and Development in the ASTROCULTURE(trademark) Space-Based Growth Unit-Ground Based Experiments

    NASA Technical Reports Server (NTRS)

    Bula, R. J.

    1997-01-01

    The ASTROCULTURE(trademark) plant growth unit flown as part on the STS-63 mission in February 1995, represented the first time plants were flown in microgravity in a enclosed controlled environment plant growth facility. In addition to control of the major environmental parameters, nutrients were provided to the plants with the ZEOPONICS system developed by NASA Johnson Space Center scientists. Two plant species were included in this space experiment, dwarf wheat (Triticum aestivum) and a unique mustard called "Wisconsin Fast Plants" (Brassica rapa). Extensive post-flight analyses have been performed on the plant material and it has been concluded that plant growth and development was normal during the period the plants were in the microgravity environment of space. However, adequate plant growth and development control data were not available for direct comparisons of plant responses to the microgravity environment with those of plants grown at 1 g. Such data would allow for a more complete interpretation of the extent that microgravity affects plant growth and development.

  14. Turbulent Dispersion of Pathogenic Spores Within and Above Plant Canopies: Field Experiments and Lagrangian Modeling

    NASA Astrophysics Data System (ADS)

    Gleicher, S.; Chamecki, M.; Isard, S.; Katul, G. G.

    2012-12-01

    Plant disease epidemics caused by pathogenic spores are a common and consequential threat to agricultural crops. In most cases, pathogenic spores are produced and released deep inside plant canopies and must be transported out of the canopy region in order to infect other fields and spread the disease. The fraction of spores that "escape" the canopy is crucial in determining how fast and far these plant diseases will spread. The goal of this work is to use a field experiment, coupled with a Lagrangian Stochastic Model (LSM), to investigate how properties of canopy turbulence impact the dispersion of spores inside the canopy and the fraction of spores that escape from the canopy. An extensive field experiment was conducted to study spore dispersion inside and outside a corn canopy. The spores were released from point sources located at various depths inside the canopy. Concentration measurements were obtained inside and above the canopy by a 3-dimensional grid of spore collectors. The experimental measurements of mean spore concentration are used to validate a LSM for spore dispersion. In the LSM, flow field statistics used to drive the particle dispersion are specified by a second-order closure model for turbulence within plant canopies. The dispersion model includes spore deposition on and rebound from canopy elements. The combination of experimental and numerical simulations is used to quantify the fraction of spores that escape the canopy. Effects of release height, friction velocity, and canopy architecture on the escape fraction of spores are explored using the LSM, and implications for disease propagation are discussed.

  15. Bone, Calcium and Spaceflight: A Living Systems Experiment Relating Animals and Plants the Effects of Calcium on Plant Growth and Development

    NASA Technical Reports Server (NTRS)

    Reiss-Bubenheim, Debra; Navarro, B. J.; Souza, Kenneth A. (Technical Monitor)

    1994-01-01

    This educational outreach activity provided students with information about ARC's role in conducting life sciences research in space. Students were introduced to the scientific method while conducting a plant experiment that was correlated to the flight animal experiment. Students made daily observations, collected data and reported on their findings. This classroom experiment providing a hands-on learning opportunity about terrestrial and space biology in which exposed the students to new fields of study for future endeavors.

  16. Plant experiments with light-emitting diode module in Svet space greenhouse

    NASA Astrophysics Data System (ADS)

    Ilieva, Iliyana; Ivanova, Tania; Naydenov, Yordan; Dandolov, Ivan; Stefanov, Detelin

    Light is necessary for photosynthesis and shoot orientation in the space plant growth facilities. Light modules (LM) must provide sufficient photosynthetic photon flux for optimal efficiency of photosynthetic processes and also meet the constraints for power, volume and mass. A new LM for SVET Space Greenhouse using Cree R XLamp R 7090 XR light-emitting diodes (LEDs) is developed. Three types of monochromic LEDs emitting in the red, green, and blue region of the spectrum are used. The new LM contains 36 LED spots - 30 LED spots with one red, green and blue LED and 6 LED spots with three red LEDs. DMX programming device controls the LED spots and can set 231 levels of light intensity thus achieving Photosynthetic Photon Flux Density (PPFD) in the range 0-400 µmol.m-2 .s-1 and different percentages of the red, green and blue light, depending on the experimental objectives. Two one-month experiments with "salad-type" plants - lettuce and chicory were carried at 400 µmol.m-2 .s-1 PPFD (high light - HL) and 220 µmol.m-2 .s-1 PPFD (low light - LL) and composition 70% red, 20% green and 10% blue light. In vivo modulated chlorophyll fluorescence was measured by a PAM fluorometer on leaf discs and the following parameters: effective quantum yield of Photosystem II (ΦP SII ) and non-photochemical quenching (NPQ) were calculated. Both lettuce and chicory plants grown at LL express higher photochemical activity of Photosystem II (PSII) than HL grown plants, evaluated by the actual PSII quantum yield, ΦP SII . The calculated steady state NPQ values did not differ significantly in lettuce and chicory. The rapid phase of the NPQ increase was accelerated in all studied LL leaves. In conclusion low light conditions ensured more effective functioning of PSII than HL when lettuce and chicory plants were grown at 70% red, 20% green and 10% blue light composition.

  17. Theta13 Neutrino Experiment at the Diablo Canyon Power Plant, LBNL Engineering Summary Report

    SciTech Connect

    Oshatz, Daryl

    2004-03-12

    This summary document describes the results of conceptual design and cost estimates performed by LBNL Engineering staff between October 10, 2003 and March 12, 2004 for the proposed {theta}{sub 13} neutrino experiment at the Diablo Canyon Power Plant (DCPP). This document focuses on the detector room design concept and mechanical engineering issues associated with the neutrino detector structures. Every effort has been made not to duplicate information contained in the last LBNL Engineering Summary Report dated October 10, 2003. Only new or updated information is included in this document.

  18. The Next Generation Nuclear Plant Graphite Creep Experiment Irradiation in the Advanced Test Reactor

    SciTech Connect

    Blaine Grover

    2010-10-01

    The United States Department of Energy’s Next Generation Nuclear Plant (NGNP) Program will be irradiating six gas reactor graphite creep experiments in the Advanced Test Reactor (ATR) located at the Idaho National Laboratory (INL). The ATR has a long history of irradiation testing in support of reactor development and the INL has been designated as the United States Department of Energy’s lead laboratory for nuclear energy development. The ATR is one of the world’s premiere test reactors for performing long term, high flux, and/or large volume irradiation test programs. These graphite irradiations are being accomplished to support development of the next generation reactors in the United States. The graphite experiments will be irradiated over the next six to eight years to support development of a graphite irradiation performance data base on the new nuclear grade graphites now available for use in high temperature gas reactors. The goals of the irradiation experiments are to obtain irradiation performance data, including irradiation creep, at different temperatures and loading conditions to support design of the Next Generation Nuclear Plant (NGNP) Very High Temperature Gas Reactor, as well as other future gas reactors. The experiments will each consist of a single capsule that will contain six stacks of graphite specimens, with half of the graphite specimens in each stack under a compressive load, while the other half of the specimens will not be subjected to a compressive load during irradiation. The six stacks will have differing compressive loads applied to the top half of each pair of specimen stacks, while a seventh stack will not have a compressive load. The specimens will be irradiated in an inert sweep gas atmosphere with on-line temperature and compressive load monitoring and control. There will also be the capability of sampling the sweep gas effluent to determine if any oxidation or off-gassing of the specimens occurs during initial start-up of

  19. Analytical and Radio-Histo-Chemical Experiments of Plants and Tissue Culture Cells Treated with Lunar and Terrestrial Materials

    NASA Technical Reports Server (NTRS)

    Halliwell, R. S.

    1973-01-01

    The nature and mechanisms of the apparent simulation of growth originally observed in plants growing in contact with lunar soil during the Apollo project quarantine are examined. Preliminary experiments employing neutron activated lunar soil indicate uptake of a few elements by plants. It was found that while the preliminary neutron activation technique allowed demonstration of uptake of minerals it presented numerous disadvantages for use in critical experiments directed at elucidating possible mechanisms of stimulation.

  20. Direct containment heating experiments in Zion Nuclear Power Plant geometry using prototypic materials

    SciTech Connect

    Binder, J.L.; McUmber, L.M.; Spencer, B.W.

    1993-12-31

    Direct Containment Heating (DCH) experiments have been completed which utilize prototypic core materials. The experiments reported on here are a continuation of the Integral Effects Testing (IET) DCH program. The experiments incorporated a 1/40 scale model of the Zion Nuclear Power Plant containment structures. The model included representations of the primary system volume, RPV lower head, cavity and instrument tunnel, and the lower containment structures. The experiments were steam driven. Iron-alumina thermite with chromium was used as a core melt stimulant in the earlier IET experiments. These earlier IET experiments at Argonne National Laboratory (ANL) and Sandia National Laboratories (SNL) provided useful data on the effect of scale on DCH phenomena; however, a significant question concerns the potential experiment distortions introduced by the use of non-prototypic iron/alumina thermite. Therefore, further testing with prototypic materials has been carried out at ANL. Three tests have been completed, DCH-U1A, U1B and U2. DCH-U1A and U1B employed an inerted containment atmosphere and are counterpart to the IET-1RR test with iron/alumina thermite. DCH-U2 employed nominally the same atmosphere composition of its counterpart iron/alumina test, IET-6. All tests, with prototypic material, have produced lower peak containment pressure rises; 45, 111 and 185 kPa in U1A, U1B and U2, compared to 150 and 250 kPa IET-1RR and 6. Hydrogen production, due to metal-steam reactions, was 33% larger in U1B and U2 compared to IET-1RR and IET-6. The pressurization efficiency was consistently lower for the corium tests compared to the IET tests.

  1. Experience-based modulation of behavioural responses to plant volatiles and other sensory cues in insect herbivores.

    PubMed

    Anderson, P; Anton, S

    2014-08-01

    Plant volatiles are important cues for many herbivorous insects when choosing a suitable host plant and finding a mating partner. An appropriate behavioural response to sensory cues from plants and other insects is crucial for survival and fitness. As the natural environment can show both large spatial and temporal variability, herbivores may need to show behavioural plasticity to the available cues. By using earlier experiences, insects can adapt to local variation of resources. Experience is well known to affect sensory-guided behaviour in parasitoids and social insects, but there is also increasing evidence that it influences host plant choice and the probability of finding a mating partner in herbivorous insects. In this review, we will focus upon behavioural changes in holometabolous insect herbivores during host plant choice and localization of mating partners, modulated by experience to sensory cues. The experience can be acquired during both the larval and the adult stage and can influence later responses to plant volatiles and other sensory cues not only within the developmental stage but also after metamorphosis. Furthermore, we will address the neurophysiological mechanisms underlying the experience-dependent behavioural adaptations and discuss ecological and evolutionary aspects of insect behavioural plasticity based upon experience.

  2. Design of Plant Gas Exchange Experiments in a Variable Pressure Growth Chamber

    NASA Technical Reports Server (NTRS)

    Corey, Kenneth A.

    1996-01-01

    Sustainable human presence in extreme environments such as lunar and martian bases will require bioregenerative components to human life support systems where plants are used for generation of oxygen, food, and water. Reduced atmospheric pressures will be used to minimize mass and engineering requirements. Few studies have assessed the metabolic and developmental responses of plants to reduced pressure and varied oxygen atmospheres. The first tests of hypobaric pressures on plant gas exchange and biomass production at the Johnson Space Center will be initiated in January 1996 in the Variable Pressure Growth Chamber (VPGC), a large, closed plant growth chamber rated for 10.2 psi. Experiments were designed and protocols detailed for two complete growouts each of lettuce and wheat to generate a general database for human life support requirements and to answer questions about plant growth processes in reduced pressure and varied oxygen environments. The central objective of crop growth studies in the VPGC is to determine the influence of reduced pressure and reduced oxygen on the rates of photosynthesis, dark respiration, evapotranspiration and biomass production of lettuce and wheat. Due to the constraint of one experimental unit, internal controls, called pressure transients, will be used to evaluate rates of CO2 uptake, O2 evolution, and H2O generation. Pressure transients will give interpretive power to the results of repeated growouts at both reduced and ambient pressures. Other experiments involve the generation of response functions to partial pressures of O2 and CO2 and to light intensity. Protocol for determining and calculating rates of gas exchange have been detailed. In order to build these databases and implement the necessary treatment combinations in short time periods, specific requirements for gas injections and removals have been defined. A set of system capability checks will include determination of leakage rates conducted prior to the actual crop

  3. Negative plant–soil feedbacks may limit persistence of an invasive tree due to rapid accumulation of soil pathogens

    PubMed Central

    Nijjer, Somereet; Rogers, William E; Siemann, Evan

    2007-01-01

    Soil organisms influence plant species coexistence and invasion potential. Plant–soil feedbacks occur when plants change soil community composition such that interactions with that soil community in turn may positively or negatively affect the performance of conspecifics. Theories predict and studies show that invasions may be promoted by stronger negative soil feedbacks for native compared with exotic species. We present a counter-example of a successful invader with strong negative soil feedbacks apparently caused by host-specific, pathogenic soil fungi. Using a feedback experiment in pots, we investigated whether the relative strength of plant–soil feedbacks experienced by a non-native woody invader, Sapium sebiferum, differed from several native tree species by examining their performance in soils collected near conspecifics (‘home soils’) or heterospecifics (‘away soils’) in the introduced range. Sapium seedlings, but no native seedlings, had lower survival and biomass in its home soils compared with soils of other species (‘negative feedback’). To investigate biotic agents potentially responsible for the observed negative feedbacks, we conducted two additional experiments designed to eliminate different soil taxa (‘rescue experiments’). We found that soil sterilization (pot experiment) or soil fungicide applications (pot and field experiments) restored Sapium performance in home soil thereby eliminating the negative feedbacks we observed in the original experiment. Such negative feedbacks apparently mediated by soil fungi could have important effects on persistence of this invader by limiting Sapium seedling success in Sapium dominated forests (home soils) though their weak effects in heterospecific (away) soils suggest a weak role in limiting initial establishment. PMID:17711837

  4. Thermal de-acclimation: how permanent are leaf phenotypes when cold-acclimated plants experience warming?

    PubMed

    Gorsuch, Peter A; Pandey, Subedar; Atkin, Owen K

    2010-07-01

    We quantified a broad range of Arabidopsis thaliana (Col-0) leaf phenotypes for initially warm-grown (25/20 degrees C day/night) plants that were exposed to cold (5 degrees C) for periods of a few hours to 45 d before being transferred back to the warm, where leaves were allowed to mature. This allowed us to address the following questions: (1) For how long do warm-grown plants have to experience cold before developing leaves become irreversibly cold acclimated? (2) To what extent is the de-acclimation process associated with changes in leaf anatomy and physiology? We show that leaves that experience cold for extended periods during early development exhibit little plasticity in either photosynthesis or respiration, and they do not revert to a warm-associated carbohydrate profile. The eventual expansion rate in the warm was inversely related to the duration of previous cold treatment. Moreover, cold exposure of immature/developing leaves for as little as 5 d resulted in irreversible changes in the morphology of leaves that subsequently matured in the warm, with 15 d cold being sufficient for a permanent alteration of leaf anatomy. Collectively, these results highlight the impact of transitory cold during early leaf development in determining the eventual phenotype of leaves that mature in the warm.

  5. Soil fertility increases with plant species diversity in a long-term biodiversity experiment.

    PubMed

    Dybzinski, Ray; Fargione, Joseph E; Zak, Donald R; Fornara, Dario; Tilman, David

    2008-11-01

    Most explanations for the positive effect of plant species diversity on productivity have focused on the efficiency of resource use, implicitly assuming that resource supply is constant. To test this assumption, we grew seedlings of Echinacea purpurea in soil collected beneath 10-year-old, experimental plant communities containing one, two, four, eight, or 16 native grassland species. The results of this greenhouse bioassay challenge the assumption of constant resource supply; we found that bioassay seedlings grown in soil collected from experimental communities containing 16 plant species produced 70% more biomass than seedlings grown in soil collected beneath monocultures. This increase was likely attributable to greater soil N availability, which had increased in higher diversity communities over the 10-year-duration of the experiment. In a distinction akin to the selection/complementarity partition commonly made in studies of diversity and productivity, we further determined whether the additive effects of functional groups or the interactive effects of functional groups explained the increase in fertility with diversity. The increase in bioassay seedling biomass with diversity was largely explained by a concomitant increase in N-fixer, C4 grass, forb, and C3 grass biomass with diversity, suggesting that the additive effects of these four functional groups at higher diversity contributed to enhance N availability and retention. Nevertheless, diversity still explained a significant amount of the residual variation in bioassay seedling biomass after functional group biomass was included in a multiple regression, suggesting that interactions also increased fertility in diverse communities. Our results suggest a mechanism, the fertility effect, by which increased plant species diversity may increase community productivity over time by increasing the supply of nutrients via both greater inputs and greater retention.

  6. Perceptual Learning Solely Induced by Feedback

    PubMed Central

    Choi, Hoon; Watanabe, Takeo

    2012-01-01

    Although feedback is considered to be an important factor in perceptual learning (PL), its role is normally considered limited to facilitation, rather than direct inducement, of PL. Recent studies, however, have suggested feedback to be more actively involved in the inducement of PL. The current study demonstrates an even more significant role for feedback in PL: feedback can evoke PL of a feature without any bottom-up processing of that feature. We use a “fake feedback” method, in which the feedback is related to an arbitrarily chosen feature, rather than actual performance. We find evidence of PL with this fake feedback method both when the learned feature is absent from the visual stimulus (Experiment 1) and when it conflicts with the visual stimulus (Experiment 2). We call this “feedback-based PL,” in contrast with the classical “exposure-based PL.” We find that feedback-based PL and exposure-based PL can occur independently of each other even while occurring in the same paradigm. These results suggest that feedback not only facilitates PL that is evoked by bottom-up information, but that it can directly induce PL, where such feedback-based PL occurs independently of exposure-based PL. PMID:22269189

  7. Increasing Dopamine Levels in the Brain Improves Feedback-Based Procedural Learning in Healthy Participants: An Artificial-Grammar-Learning Experiment

    ERIC Educational Resources Information Center

    de Vries, Meinou H.; Ulte, Catrin; Zwitserlood, Pienie; Szymanski, Barbara; Knecht, Stefan

    2010-01-01

    Recently, an increasing number of studies have suggested a role for the basal ganglia and related dopamine inputs in procedural learning, specifically when learning occurs through trial-by-trial feedback (Shohamy, Myers, Kalanithi, & Gluck. (2008). "Basal ganglia and dopamine contributions to probabilistic category learning." "Neuroscience and…

  8. Studies Of Positive-Position-Feedback Control

    NASA Technical Reports Server (NTRS)

    Fanson, James L.; Caughey, Thomas K.

    1992-01-01

    Report discusses theoretical and experimental studies of positive-position-feedback control for suppressing vibrations in large flexible structures. Positive-position-feedback control involves placement of actuators and sensors on structure; control voltages applied to actuators in response to outputs of sensors processed via compensator algorithm. Experiments demonstrate feasibility of suppressing vibrations by positive position feedback, and spillover of vibrational energy into uncontrolled modes has stabilizing effect if control gain sufficiently small.

  9. Effects of the Extraterrestrial Environment on Plants: Recommendations for Future Space Experiments for the MELiSSA Higher Plant Compartment

    PubMed Central

    Wolff, Silje A.; Coelho, Liz H.; Karoliussen, Irene; Jost, Ann-Iren Kittang

    2014-01-01

    Due to logistical challenges, long-term human space exploration missions require a life support system capable of regenerating all the essentials for survival. Higher plants can be utilized to provide a continuous supply of fresh food, atmosphere revitalization, and clean water for humans. Plants can adapt to extreme environments on Earth, and model plants have been shown to grow and develop through a full life cycle in microgravity. However, more knowledge about the long term effects of the extraterrestrial environment on plant growth and development is necessary. The European Space Agency (ESA) has developed the Micro-Ecological Life Support System Alternative (MELiSSA) program to develop a closed regenerative life support system, based on micro-organisms and higher plant processes, with continuous recycling of resources. In this context, a literature review to analyze the impact of the space environments on higher plants, with focus on gravity levels, magnetic fields and radiation, has been performed. This communication presents a roadmap giving directions for future scientific activities within space plant cultivation. The roadmap aims to identify the research activities required before higher plants can be included in regenerative life support systems in space. PMID:25370192

  10. Effects of the Extraterrestrial Environment on Plants: Recommendations for Future Space Experiments for the MELiSSA Higher Plant Compartment.

    PubMed

    Wolff, Silje A; Coelho, Liz H; Karoliussen, Irene; Jost, Ann-Iren Kittang

    2014-05-05

    Due to logistical challenges, long-term human space exploration missions require a life support system capable of regenerating all the essentials for survival. Higher plants can be utilized to provide a continuous supply of fresh food, atmosphere revitalization, and clean water for humans. Plants can adapt to extreme environments on Earth, and model plants have been shown to grow and develop through a full life cycle in microgravity. However, more knowledge about the long term effects of the extraterrestrial environment on plant growth and development is necessary. The European Space Agency (ESA) has developed the Micro-Ecological Life Support System Alternative (MELiSSA) program to develop a closed regenerative life support system, based on micro-organisms and higher plant processes, with continuous recycling of resources. In this context, a literature review to analyze the impact of the space environments on higher plants, with focus on gravity levels, magnetic fields and radiation, has been performed. This communication presents a roadmap giving directions for future scientific activities within space plant cultivation. The roadmap aims to identify the research activities required before higher plants can be included in regenerative life support systems in space.

  11. Student Engagement with Feedback

    ERIC Educational Resources Information Center

    Scott, Jon; Shields, Cathy; Gardner, James; Hancock, Alysoun; Nutt, Alex

    2011-01-01

    This report considers Biological Sciences students' perceptions of feedback, compared with those of the University as a whole, this includes what forms of feedback were considered most useful and how feedback used. Compared with data from previous studies, Biological Sciences students gave much greater recognition to oral feedback, placing it on a…

  12. Large CFB power plant design and operating experience: Texas-New Mexico Power Company 150 MWe (net) CFB power plant

    SciTech Connect

    Riley, K.; Cleve, K.; Tanca, M.

    1995-12-31

    The first unit of the TNP One CFB power plant was successfully put on line by Texas-New Mexico Power Company (TNP) in Robertson County, Texas, US in 1990. Unit 2 came on line one year later. This grassroots plant fires Texas lignite. The two identical CFB units were each designed for 150 MWe net electrical generation. The units have operated at 155 MWe net for extended periods of time without modifications. The boilers have additional capacity but are limited by the balance of plant. The TNP One plant was awarded the Power Plant of the Year Award by Power magazine in 1991 advancing CFB technology in large generating facilities. The plant was designed for maximum fuel flexibility with guaranteed full load operation on either Texas lignite, western coal or natural gas. The plant has fired the following fuels, to date: lignite (base fuel), natural gas (0--100% with lignite), delayed petroleum coke (0--100% with lignite), plant generated waste oils (small amounts), oil filter fluff (small amounts) and a waste product of pelletized reflective tape. Future testing is planned to test burn shredded tires. While firing all fuels, the plant could attain full load and meet all environmentally permitted emissions without any boiler modifications or compromises in boiler efficiency. This high flexibility of the plant can be attributed to the two large fluidized bed heat exchangers (FBHEs) for steam temperature and combustor temperature control. The facility is a mine mouth operation burning the local Texas lignite. The delayed petroleum cokes fired originated from various supply sources from the Texas/Louisiana area.

  13. Experiments to investigate direct containment heating phenomena with scaled models of the Surry Nuclear Power Plant

    SciTech Connect

    Blanchat, T.K.; Allen, M.D.; Pilch, M.M.; Nichols, R.T.

    1994-06-01

    The Containment Technology Test Facility (CTTF) and the Surtsey Test Facility at Sandia National Laboratories are used to perform scaled experiments that simulate High Pressure Melt Ejection accidents in a nuclear power plant (NPP). These experiments are designed to investigate the effects of direct containment heating (DCH) phenomena on the containment load. High-temperature, chemically reactive melt (thermite) is ejected by high-pressure steam into a scale model of a reactor cavity. Debris is entrained by the steam blowdown into a containment model where specific phenomena, such as the effect of subcompartment structures, prototypic air/steam/hydrogen atmospheres, and hydrogen generation and combustion, can be studied. Four Integral Effects Tests (IETs) have been performed with scale models of the Surry NPP to investigate DCH phenomena. The 1/61{sup th} scale Integral Effects Tests (IET-9, IET-10, and IET-11) were conducted in CTRF, which is a 1/6{sup th} scale model of the Surry reactor containment building (RCB). The 1/10{sup th} scale IET test (IET-12) was performed in the Surtsey vessel, which had been configured as a 1/10{sup th} scale Surry RCB. Scale models were constructed in each of the facilities of the Surry structures, including the reactor pressure vessel, reactor support skirt, control rod drive missile shield, biological shield wall, cavity, instrument tunnel, residual heat removal platform and heat exchangers, seal table room and seal table, operating deck, and crane wall. This report describes these experiments and gives the results.

  14. Haptic gas pedal feedback.

    PubMed

    Mulder, M; Mulder, M; van Paassen, M M; Abbink, D A

    2008-11-01

    Active driver support systems either automate a control task or present warnings to drivers when their safety is seriously degraded. In a novel approach, utilising neither automation nor discrete warnings, a haptic gas pedal (accelerator) interface was developed that continuously presents car-following support information, keeping the driver in the loop. This interface was tested in a fixed-base driving simulator. Twenty-one drivers between the ages of 24 and 30 years participated in a driving experiment to investigate the effects of haptic gas pedal feedback on car-following behaviour. Results of the experiment indicate that when haptic feedback was presented to the drivers, some improvement in car-following performance was achieved, while control activity decreased. Further research is needed to investigate the effectiveness of the system in more varied driving conditions. Haptics is an under-used modality in the application of human support interfaces, which usually draw on vision or hearing. This study demonstrates how haptics can be used to create an effective driver support interface.

  15. Feedback traps for virtual potentials

    NASA Astrophysics Data System (ADS)

    Gavrilov, Momčilo; Bechhoefer, John

    2017-03-01

    Feedback traps are tools for trapping and manipulating single charged objects, such as molecules in solution. An alternative to optical tweezers and other single-molecule techniques, they use feedback to counteract the Brownian motion of a molecule of interest. The trap first acquires information about a molecule's position and then applies an electric feedback force to move the molecule. Since electric forces are stronger than optical forces at small scales, feedback traps are the best way to trap single molecules without `touching' them (e.g. by putting them in a small box or attaching them to a tether). Feedback traps can do more than trap molecules: they can also subject a target object to forces that are calculated to be the gradient of a desired potential function U(x). If the feedback loop is fast enough, it creates a virtual potential whose dynamics will be very close to those of a particle in an actual potential U(x). But because the dynamics are entirely a result of the feedback loop-absent the feedback, there is only an object diffusing in a fluid-we are free to specify and then manipulate in time an arbitrary potential U(x,t). Here, we review recent applications of feedback traps to studies on the fundamental connections between information and thermodynamics, a topic where feedback plays an even more fundamental role. We discuss how recursive maximum-likelihood techniques allow continuous calibration, to compensate for drifts in experiments that last for days. We consider ways to estimate work and heat, using them to measure fluctuating energies to a precision of ±0.03 kT over these long experiments. Finally, we compare work and heat measurements of the costs of information erasure, the Landauer limit of kT ln 2 per bit of information erased. We argue that, when you want to know the average heat transferred to a bath in a long protocol, you should measure instead the average work and then infer the heat using the first law of thermodynamics. This

  16. On the use of plant emitted volatile organic compounds for atmospheric chemistry simulation experiments

    NASA Astrophysics Data System (ADS)

    Kiendler-Scharr, A.; Hohaus, T.; Yu, Z.; Tillmann, R.; Kuhn, U.; Andres, S.; Kaminski, M.; Wegener, R.; Novelli, A.; Fuchs, H.; Wahner, A.

    2015-12-01

    Biogenic volatile organic compounds (BVOC) contribute to about 90% of the emitted VOC globally with isoprene being one of the most abundant BVOC (Guenther 2002). Intensive efforts in studying and understanding the impact of BVOC on atmospheric chemistry were undertaken in the recent years. However many uncertainties remain, e.g. field studies have shown that in wooded areas measured OH reactivity can often not be explained by measured BVOC and their oxidation products (e.g. Noelscher et al. 2012). This discrepancy may be explained by either a lack of understanding of BVOC sources or insufficient understanding of BVOC oxidation mechanisms. Plants emit a complex VOC mixture containing likely many compounds which have not yet been measured or identified (Goldstein and Galbally 2007). A lack of understanding BVOC sources limits bottom-up estimates of secondary products of BVOC oxidation such as SOA. Similarly, the widespread oversimplification of atmospheric chemistry in simulation experiments, using single compound or simple BVOC mixtures to study atmospheric chemistry processes limit our ability to assess air quality and climate impacts of BVOC. We will present applications of the new extension PLUS (PLant chamber Unit for Simulation) to our atmosphere simulation chamber SAPHIR. PLUS is used to produce representative BVOC mixtures from direct plant emissions. We will report on the performance and characterization of the newly developed chamber. As an exemplary application, trees typical of a Boreal forest environment were used to compare OH reactivity as directly measured by LIF to the OH reactivity calculated from BVOC measured by GC-MS and PTRMS. The comparison was performed for both, primary emissions of trees without any influence of oxidizing agents and using different oxidation schemes. For the monoterpene emitters investigated here, we show that discrepancies between measured and calculated total OH reactivity increase with increasing degree of oxidation

  17. [Growth and development of plants in a row of generations under the conditions of space flight (experiment Greenhouse-5)

    NASA Technical Reports Server (NTRS)

    Levinskikh, M. A.; Sychev, V. N.; Derendiaeva, T. A.; Signalova, O. B.; Podol'skii, I. G.; Avdeev, S. V.; Bingheim, G. E.; Campbell, W. F. (Principal Investigator)

    2001-01-01

    Results of the experiment aimed at harvesting a second space generation of wheat var. Apogee in Mir greenhouse Svet (experiment GREENHOUSE-5) are presented. In space flight, germination rate of space seeds from the first crop made up 89% against 100% of the ground seeds. The full biological ripeness was observed in 20 plants grown from the ground seeds and one plant grown from the space seeds following 80- to 90-d vegetation. The plant of the second space generation was morphologically different neither from the species in the first space crop nor from the ground controls. To study the biological characteristics of Apogee seeds gathered in the first and second crops in spaceflight experiment GREENHOUSE-5, the seeds were planted on their return to the laboratory. Morphometric analysis showed that they were essentially similar to the controls. Hence, the space experiments in Mir greenhouse Svet performed during 1998-1999 gave proof that plants cultivated in microgravity can pass the ontogenetic cycle more than once. However, initial results of the investigations into growth and development of plants through several generations are still in-sufficient to speak of possible delayed effects of the spaceflight factors (microgravity, multicomponent radiation, harmful trace contaminants etc.).

  18. Experiments to investigate direct containment heating phenomena with scaled models of the Calvert Cliffs Nuclear Power Plant

    SciTech Connect

    Blanchat, T.K.; Pilch, M.M.; Allen, M.D.

    1997-02-01

    The Surtsey Test Facility is used to perform scaled experiments simulating High Pressure Melt Ejection accidents in a nuclear power plant (NPP). The experiments investigate the effects of direct containment heating (DCH) on the containment load. The results from Zion and Surry experiments can be extrapolated to other Westinghouse plants, but predicted containment loads cannot be generalized to all Combustion Engineering (CE) plants. Five CE plants have melt dispersal flow paths which circumvent the main mitigation of containment compartmentalization in most Westinghouse PWRs. Calvert Cliff-like plant geometries and the impact of codispersed water were addressed as part of the DCH issue resolution. Integral effects tests were performed with a scale model of the Calvert Cliffs NPP inside the Surtsey test vessel. The experiments investigated the effects of codispersal of water, steam, and molten core stimulant materials on DCH loads under prototypic accident conditions and plant configurations. The results indicated that large amounts of coejected water reduced the DCH load by a small amount. Large amounts of debris were dispersed from the cavity to the upper dome (via the annular gap). 22 refs., 84 figs., 30 tabs.

  19. ARADISH - Development of a Standardized Plant Growth Chamber for Experiments in Gravitational Biology Using Ground Based Facilities

    NASA Astrophysics Data System (ADS)

    Schüler, Oliver; Krause, Lars; Görög, Mark; Hauslage, Jens; Kesseler, Leona; Böhmer, Maik; Hemmersbach, Ruth

    2016-06-01

    Plant development strongly relies on environmental conditions. Growth of plants in Biological Life Support Systems (BLSS), which are a necessity to allow human survival during long-term space exploration missions, poses a particular problem for plant growth, as in addition to the traditional environmental factors, microgravity (or reduced gravity such as on Moon or Mars) and limited gas exchange hamper plant growth. Studying the effects of reduced gravity on plants requires real or simulated microgravity experiments under highly standardized conditions, in order to avoid the influence of other environmental factors. Analysis of a large number of biological replicates, which is necessary for the detection of subtle phenotypical differences, can so far only be achieved in Ground Based Facilities (GBF). Besides different experimental conditions, the usage of a variety of different plant growth chambers was a major factor that led to a lack of reproducibility and comparability in previous studies. We have developed a flexible and customizable plant growth chamber, called ARAbidopsis DISH (ARADISH), which allows plant growth from seed to seedling, being realized in a hydroponic system or on Agar. By developing a special holder, the ARADISH can be used for experiments with Arabidopsis thaliana or a plant with a similar habitus on common GBF hardware, including 2D clinostats and Random Positioning Machines (RPM). The ARADISH growth chamber has a controlled illumination system of red and blue light emitting diodes (LED), which allows the user to apply defined light conditions. As a proof of concept we tested a prototype in a proteomic experiment in which plants were exposed to simulated microgravity or a 90° stimulus. We optimized the design and performed viability tests after several days of growth in the hardware that underline the utility of ARADISH in microgravity research.

  20. Dosimetry experiences and lessons learned for radiation dose assessment in Korean nuclear power plants.

    PubMed

    Choi, Jong Rak; Kim, Hee Geun; Kong, Tae Young; Son, Jung Kwon

    2013-07-01

    Since the first Korean nuclear power plant (NPP), Kori 1, commenced operation in 1978, a total of 21 NPPs had been put into operation in Korea by the end of 2011. Radiation doses of NPP workers have been periodically evaluated and controlled within the prescribed dose limit. Radiation dose assessment is carried out monthly by reading personal dosemeters for external radiation exposure, which have traceability in compliance with strict technical guidelines. In the case of the internal radiation exposure, workers who have access to the possible area of polluted air are also evaluated for their internal dose after maintenance task. In this article, the overall situation and experience for the assessment and distribution of radiation doses in Korean NPPs is described.

  1. Engaging Feedback: Meaning, Identity and Power

    ERIC Educational Resources Information Center

    Sutton, Paul; Gill, Wendy

    2010-01-01

    This paper uses a methodology that synthesises an Academic Literacies approach and Critical Discourse Analysis to explore student experiences of feedback on written assessments in two higher education institutions. The qualitative analysis of student interviews is oriented around three topics: (1) the socially situated meaning of feedback; (2)…

  2. Feedback in Clinical Education, Part I: Characteristics of Feedback Provided by Approved Clinical Instructors

    PubMed Central

    Nottingham, Sara; Henning, Jolene

    2014-01-01

    Context Providing students with feedback is an important component of athletic training clinical education; however, little information is known about the feedback that Approved Clinical Instructors (ACIs; now known as preceptors) currently provide to athletic training students (ATSs). Objective To characterize the feedback provided by ACIs to ATSs during clinical education experiences. Design Qualitative study. Setting One National Collegiate Athletic Association Division I athletic training facility and 1 outpatient rehabilitation clinic that were clinical sites for 1 entry-level master's degree program accredited by the Commission on Accreditation of Athletic Training Education. Patients or Other Participants A total of 4 ACIs with various experience levels and 4 second-year ATSs. Data Collection and Analysis Extensive field observations were audio recorded, transcribed, and integrated with field notes for analysis. The constant comparative approach of open, axial, and selective coding was used to inductively analyze data and develop codes and categories. Member checking, triangulation, and peer debriefing were used to promote trustworthiness of the study. Results The ACIs gave 88 feedback statements in 45 hours and 10 minutes of observation. Characteristics of feedback categories included purpose, timing, specificity, content, form, and privacy. Conclusions Feedback that ACIs provided included several components that made each feedback exchange unique. The ACIs in our study provided feedback that is supported by the literature, suggesting that ACIs are using current recommendations for providing feedback. Feedback needs to be investigated across multiple athletic training education programs to gain more understanding of certain areas of feedback, including frequency, privacy, and form. PMID:24143902

  3. [Growth and development of plants in a sequence of generations under the conditions of space flight (experiment Greenhouse-3)

    NASA Technical Reports Server (NTRS)

    Levinskikh, M. A.; Sychev, V. N.; Signalova, O. B.; Derendiaeva, T. A.; Podol'skii, I. G.; Masgreiv, M. E.; Bingheim, G. E.; Musgrave, M. E. (Principal Investigator); Campbell, W. F. (Principal Investigator)

    2001-01-01

    The purpose was to study characteristic features of growth and development of several plant generations in space flight in experiment GREENHOUSE-3 as a part of the Russian-US space research program MIR/NASA in 1997. The experiment consisted of cultivation of Brassica rapa L. in board greenhouse Svet. Two vegetative cycles were fully completed and the third vegetation was terminated on day 13 on the phase of budding. The total duration of the space experiment was 122 days, i.e. same as in the ground controls. In the experiment with Brassica rapa L. viable seeds produced by the first crop were planted in space flight and yielded next crop. Crops raised from the ground and space seeds were found to differ in height and number of buds. Both parameters were lowered in the plants grown from the space seeds. The prime course for smaller size and reduced organogenic potential of plantTs reproductive system seems to be a less content of nutrients in seeds that had matured in the space flight. Experiment GREENHOUSE-3 demonstrated principle feasibility of plant reproduction in space greenhouse from seeds developed in microgravity.

  4. The νGeN experiment at the Kalinin Nuclear Power Plant

    NASA Astrophysics Data System (ADS)

    Belov, V.; Brudanin, V.; Egorov, V.; Filosofov, D.; Fomina, M.; Gurov, Yu.; Korotkova, L.; Lubashevskiy, A.; Medvedev, D.; Pritula, R.; Rozova, I.; Rozov, S.; Sandukovsky, V.; Timkin, V.; Yakushev, E.; Yurkowski, J.; Zhitnikov, I.

    2015-12-01

    The ν GeN is new experiment at the Kalinin Nuclear Power Plant (KNPP) for detection of coherent Neutrino-Ge Nucleus elastic scattering. Recent neutrino and Dark Matter search experiments have revolutionized the detection of rear events, and rear events with low energies, in particular. Experiments have achieved sensitivities on the level of several events per hundred kg of detector material per day with energy thresholds from few hundred eV. This opens up a new unique possibility for experimental detection of neutrino-nucleus coherent scattering that has been considered to be impossible so far. The νGeN project uses low threshold high-purity Ge-detectors (HPGe) developed by JINR (Dubna, Russia) in collaboration with BSI (Baltic Scientific Instruments, Riga, Latvia) for creation of a setup designated for first observation of neutrino coherent scattering on Ge. As a powerful neutrino source the experiment will use electron antineutrinos from one of the power-generating units (reactor unit #3) of the KNPP. The coherent neutrino scattering will be observed using a differential method that compares 1) the spectra measured at the reactor operation and shut-down periods; 2) the spectra measured at different distances from the reactor core during the reactor operation. For a setup placed at a 10 m distance from the center of reactor core and with an energy threshold of 350 eV up to tens of events corresponding to neutrino coherent scattering on Ge are expected to be detected per day in the constructed setup with four HPGe low-energy-threshold detectors (~ 400 grams each). The setup sensitivity will be even more increased by using new detectors with total mass up to 5 kg.

  5. Results from simulated remote-handled transuranic waste experiments at the Waste Isolation Pilot Plant (WIPP)

    SciTech Connect

    Molecke, M A

    1992-01-01

    Multi-year, simulated remote-handled transuranic waste (RH TRU, nonradioactive) experiments are being conducted underground in the Waste Isolation Pilot-Plant (WIPP) facility. These experiments involve the near-reference (thermal and geometrical) testing of eight full size RH TRU test containers emplaced into horizontal, unlined rock salt boreholes. Half of the test emplacements are partially filled with bentonite/silica-sand backfill material. All test containers were electrically heated at about 115 W/each for three years, then raised to about 300 W/each for the remaining time. Each test borehole was instrumented with a selection of remote-reading thermocouples, pressure gages, borehole vertical-closure gages, and vertical and horizontal borehole-diameter closure gages. Each test emplacements was also periodically opened for visual inspections of brine intrusions and any interactions with waste package materials, materials sampling, manual closure measurements, and observations of borehole changes. Effects of heat on borehole closure rates and near-field materials (metals, backfill, rock salt, and intruding brine) interactions were closely monitored as a function of time. This paper summarizes results for the first five years of in situ test operation with supporting instrumentation and laboratory data and interpretations. Some details of RH TRU waste package materials, designs, and assorted underground test observations are also discussed. Based on the results, the tested RH TRU waste packages, materials, and emplacement geometry in unlined salt boreholes appear to be quite adequate for initial WIPP repository-phase operations.

  6. Large-area experiment on uptake of metals by twelve plants growing in soils contaminated with multiple metals.

    PubMed

    Lai, Hung-Yu; Juang, Kai-Wei; Chen, Zueng-Sang

    2010-01-01

    A site in central Taiwan with an area of 1.3 ha and contaminated with Cr, Cu, Ni, and Zn was selected to examine the feasibility of phytoextraction. Based on the results of a preexperiment at this site, a total of approximately 20,000 plants of 12 species were selected from plants of 33 tested species to be used in a large-area phytoextraction experiment at this site. A comparison with the initial metal concentration of 12 plant species before planting demonstrated that most species accumulated significant amounts of Cr, Cu, Ni, and Zn in their shoots after growing in this contaminated site for 31 d. Among the 12 plant species, the following accumulated higher concentrations of metals in their shoots; Garden canna and Garden verbena (45-60 mg Cr kg(-1)), Chinese ixora and Kalanchoe (30 mg Cu kg(-1)), Rainbow pink and Sunflower (30 mg Ni kg(-1)), French marigold and Sunflower (300-470 mg Zn kg(-1)). The roots of the plants of most of the 12 plant species can accumulate higher concentrations of metals than the shoots and extending the growth period promotes accumulation in the shoots. Large-area experiments demonstrated that phytoextraction is a feasible method to enable metal-contaminated soil in central Taiwan to be reused.

  7. Results from simulated contact-handled transuranic waste experiments at the Waste Isolation Pilot Plant

    SciTech Connect

    Molecke, M.A.; Sorensen, N.R.; Krumhansl, J.L.

    1993-12-31

    We conducted in situ experiments with nonradioactive, contact-handled transuranic (CH TRU) waste drums at the Waste Isolation Pilot Plant (WIPP) facility for about four years. We performed these tests in two rooms in rock salt, at WIPP, with drums surrounded by crushed salt or 70 wt % salt/30 wt % bentonite clay backfills, or partially submerged in a NaCl brine pool. Air and brine temperatures were maintained at {approximately}40C. These full-scale (210-L drum) experiments provided in situ data on: backfill material moisture-sorption and physical properties in the presence of brine; waste container corrosion adequacy; and, migration of chemical tracers (nonradioactive actinide and fission product simulants) in the near-field vicinity, all as a function of time. Individual drums, backfill, and brine samples were removed periodically for laboratory evaluations. Waste container testing in the presence of brine and brine-moistened backfill materials served as a severe overtest of long-term conditions that could be anticipated in an actual salt waste repository. We also obtained relevant operational-test emplacement and retrieval experience. All test results are intended to support both the acceptance of actual TRU wastes at the WIPP and performance assessment data needs. We provide an overview and technical data summary focusing on the WIPP CH TRU envirorunental overtests involving 174 waste drums in the presence of backfill materials and the brine pool, with posttest laboratory materials analyses of backfill sorbed-moisture content, CH TRU drum corrosion, tracer migration, and associated test observations.

  8. Waste Isolation Pilot Plant simulated RH TRU waste experiments: Data and interpretation pilot

    SciTech Connect

    Molecke, M.A.; Argueello, G.J.; Beraun, R.

    1993-04-01

    The simulated, i.e., nonradioactive remote-handled transuranic waste (RH TRU) experiments being conducted underground in the Waste Isolation Pilot Plant (WIPP) were emplaced in mid-1986 and have been in heated test operation since 9/23/86. These experiments involve the in situ, waste package performance testing of eight full-size, reference RH TRU containers emplaced in horizontal, unlined test holes in the rock salt ribs (walls) of WIPP Room T. All of the test containers have internal electrical heaters; four of the test emplacements were filled with bentonite and silica sand backfill materials. We designed test conditions to be ``near-reference`` with respect to anticipated thermal outputs of RH TRU canisters and their geometrical spacing or layout in WIPP repository rooms, with RH TRU waste reference conditions current as of the start date of this test program. We also conducted some thermal overtest evaluations. This paper provides a: detailed test overview; comprehensive data update for the first 5 years of test operations; summary of experiment observations; initial data interpretations; and, several status; experimental objectives -- how these tests support WIPP TRU waste acceptance, performance assessment studies, underground operations, and the overall WIPP mission; and, in situ performance evaluations of RH TRU waste package materials plus design details and options. We provide instrument data and results for in situ waste container and borehole temperatures, pressures exerted on test containers through the backfill materials, and vertical and horizontal borehole-closure measurements and rates. The effects of heat on borehole closure, fracturing, and near-field materials (metals, backfills, rock salt, and intruding brine) interactions were closely monitored and are summarized, as are assorted test observations. Predictive 3-dimensional thermal and structural modeling studies of borehole and room closures and temperature fields were also performed.

  9. Operating boundaries of full-scale advanced water reuse treatment plants: many lessons learned from pilot plant experience.

    PubMed

    Bele, C; Kumar, Y; Walker, T; Poussade, Y; Zavlanos, V

    2010-01-01

    Three Advanced Water Treatment Plants (AWTP) have recently been built in South East Queensland as part of the Western Corridor Recycled Water Project (WCRWP) producing Purified Recycled Water from secondary treated waste water for the purpose of indirect potable reuse. At Luggage Point, a demonstration plant was primarily operated by the design team for design verification. The investigation program was then extended so that the operating team could investigate possible process optimisation, and operation flexibility. Extending the demonstration plant investigation program enabled monitoring of the long term performance of the microfiltration and reverse osmosis membranes, which did not appear to foul even after more than a year of operation. The investigation primarily identified several ways to optimise the process. It highlighted areas of risk for treated water quality, such as total nitrogen. Ample and rapid swings of salinity from 850 to 3,000 mg/l-TDS were predicted to affect the RO process day-to-day operation and monitoring. Most of the setpoints used for monitoring under HACCP were determined during the pilot plant trials.

  10. Improved feedback shift register

    NASA Technical Reports Server (NTRS)

    Perlman, M.

    1972-01-01

    Design of feedback shift register with three tap feedback decoding scheme is described. Application for obtaining sequence synchronization patterns is examined. Operation of the circuitry is described and drawings of the systems are included.

  11. Effects of environmental change on plant species density: Comparing predictions with experiments

    USGS Publications Warehouse

    Gough, L.; Grace, J.B.

    1999-01-01

    Ideally, general ecological relationships may be used to predict responses of natural communities to environmental change, but few attempts have been made to determine the reliability of predictions based on descriptive data. Using a previously published structural equation model (SEM) of descriptive data from a coastal marsh landscape, we compared these predictions against observed changes in plant species density resulting from field experiments (manipulations of soil fertility, flooding, salinity, and mammalian herbivory) in two areas within the same marsh. In general, observed experimental responses were fairly consistent with predictions. The largest discrepancy occurred when sods were transplanted from high- to low-salinity sites and herbivores selectively consumed a particularly palatable plant species in the transplanted sods. Individual plot responses to some treatments were predicted more accurately than others. Individual fertilized plot responses were not consistent with predictions (P > 0.05), nor were fenced plots (herbivore exclosures; R2 = 0.15) compared to unfenced plots (R2 = 0.53). For the remaining treatments, predictions reasonably matched responses (R2 = 0.63). We constructed an SEM for the experimental data; it explained 60% of the variance in species density and showed that fencing and fertilization led to decreases in species density that were not predicted from treatment effects on community biomass or observed disturbance levels. These treatments may have affected the ratio of live to dead biomass, and competitive exclusion likely decreased species density in fenced and fertilized plots. We conclude that experimental validation is required to determine the predictive value of comparative relationships derived from descriptive data.

  12. Plant diversity effects on soil microbial functions and enzymes are stronger than warming in a grassland experiment.

    PubMed

    Steinauer, Katja; Tilman, David; Wragg, Peter D; Cesarz, Simone; Cowles, Jane M; Pritsch, Karin; Reich, Peter B; Weisser, Wolfgang W; Eisenhauer, Nico

    2015-01-01

    Anthropogenic changes in biodiversity and atmospheric temperature significantly influence ecosystem processes. However, little is known about potential interactive effects of plant diversity and warming on essential ecosystem properties, such as soil microbial functions and element cycling. We studied the effects of orthogonal manipulations of plant diversity (one, four, and 16 species) and warming (ambient, +1.5 degrees C, and +3 degrees C) on soil microbial biomass, respiration, growth after nutrient additions, and activities of extracellular enzymes in 2011 and 2012 in the BAC (biodiversity and climate) perennial grassland experiment site at Cedar Creek, Minnesota, USA. Focal enzymes are involved in essential biogeochemical processes of the carbon, nitrogen, and phosphorus cycles. Soil microbial biomass and some enzyme activities involved in the C and N cycle increased significantly with increasing plant diversity in both years. In addition, 16-species mixtures buffered warming induced reductions in topsoil water content. We found no interactive effects of plant diversity and warming on soil microbial biomass and growth rates. However, the activity of several enzymes (1,4-beta-glucosidase, 1,4-beta-N-acetylglucosaminidase, phosphatase, peroxidase) depended on interactions between plant diversity and warming with elevated activities of enzymes involved in the C, N, and P cycles at both high plant diversity and high warming levels. Increasing plant diversity consistently decreased microbial biomass-specific enzyme activities and altered soil microbial growth responses to nutrient additions, indicating that plant diversity changed nutrient limitations and/or microbial community composition. In contrast to our expectations, higher plant diversity only buffered temperature effects on soil water content, but not on microbial functions. Temperature effects on some soil enzymes were greatest at high plant diversity. In total, our results suggest that the fundamental

  13. Changes in operational procedures to improve spaceflight experiments in plant biology in the European Modular Cultivation System

    NASA Astrophysics Data System (ADS)

    Kiss, John Z.; Aanes, Gjert; Schiefloe, Mona; Coelho, Liz H. F.; Millar, Katherine D. L.; Edelmann, Richard E.

    2014-03-01

    The microgravity environment aboard orbiting spacecraft has provided a unique laboratory to explore topics in basic plant biology as well as applied research on the use of plants in bioregenerative life support systems. Our group has utilized the European Modular Cultivation System (EMCS) aboard the International Space Station (ISS) to study plant growth, development, tropisms, and gene expression in a series of spaceflight experiments. The most current project performed on the ISS was termed Seedling Growth-1 (SG-1) which builds on the previous TROPI (for tropisms) experiments performed in 2006 and 2010. Major technical and operational changes in SG-1 (launched in March 2013) compared to the TROPI experiments include: (1) improvements in lighting conditions within the EMCS to optimize the environment for phototropism studies, (2) the use of infrared illumination to provide high-quality images of the seedlings, (3) modifications in procedures used in flight to improve the focus and overall quality of the images, and (4) changes in the atmospheric conditions in the EMCS incubator. In SG-1, a novel red-light-based phototropism in roots and hypocotyls of seedlings that was noted in TROPI was confirmed and now can be more precisely characterized based on the improvements in procedures. The lessons learned from sequential experiments in the TROPI hardware provide insights to other researchers developing space experiments in plant biology.

  14. How to Do It. Plant Eco-Physiology: Experiments on Crassulacean Acid Metabolism, Using Minimal Equipment.

    ERIC Educational Resources Information Center

    Friend, Douglas J. C.

    1990-01-01

    Features of Crassulacean Acid Metabolism plants are presented. Investigations of a complex eco-physiological plant adaptation to the problems of growth in an arid environment are discussed. Materials and procedures for these investigations are described. (CW)

  15. Developing Sustainable Feedback Practices

    ERIC Educational Resources Information Center

    Carless, David; Salter, Diane; Yang, Min; Lam, Joy

    2011-01-01

    Feedback is central to the development of student learning, but within the constraints of modularized learning in higher education it is increasingly difficult to handle effectively. This article makes a case for sustainable feedback as a contribution to the reconceptualization of feedback processes. The data derive from the Student Assessment and…

  16. The Mythology of Feedback

    ERIC Educational Resources Information Center

    Adcroft, Andy

    2011-01-01

    Much of the general education and discipline-specific literature on feedback suggests that it is a central and important element of student learning. This paper examines feedback from a social process perspective and suggests that feedback is best understood through an analysis of the interactions between academics and students. The paper argues…

  17. Passage Feedback with IRIS.

    ERIC Educational Resources Information Center

    Yang, Kiduk; Maglaughlin, Kelly L.; Newby, Gregory B.

    2001-01-01

    Compares a user-defined passage feedback system to a document feedback system for information retrieval, based on TREC (Text Retrieval Conference) guidelines. Highlights include a description of IRIS, an interactive retrieval system; text processing; ranking; term weights; feedback models, including the adaptive linear model; and suggestions for…

  18. Preventing Feedback Fizzle

    ERIC Educational Resources Information Center

    Brookhart, Susan M.

    2012-01-01

    Feedback is certainly about saying or writing helpful, learning-focused comments. But that is only part of it. What happens beforehand? What happens afterward? Feedback that is helpful and learning-focused fits into a context. Before a teacher gives feedback, students need to know the learning target so they have a purpose for using the feedback…

  19. Mysterious Mycorrhizae? A Field Trip & Classroom Experiment to Demystify the Symbioses Formed between Plants & Fungi

    ERIC Educational Resources Information Center

    Johnson, Nancy C.; Chaudhary, V. Bala; Hoeksema, Jason D.; Moore, John C.; Pringle, Anne; Umbanhowar, James A.; Wilson, Gail W. T.

    2009-01-01

    Biology curricula cover fungi in units on bacteria, protists, and primitive plants, but fungi are more closely related to animals than to bacteria or plants. Like animals, fungi are heterotrophs and cannot create their own food; but, like plants, fungi have cell walls, and are for the most part immobile. Most species of fungi have a filamentous…

  20. The Personal Dimension in Teaching: Why Students Value Feedback

    ERIC Educational Resources Information Center

    Rowe, Anna

    2011-01-01

    Purpose: Feedback is a central element of the learning experience yet, until recently, few studies have focused directly on what students think about feedback. This paper seeks to address this issue. Design/methodology/approach: Data collected as part of a larger study investigating reasons for consistently low ratings of feedback across the…

  1. Effects of Differential Feedback on Students' Examination Performance

    ERIC Educational Resources Information Center

    Lipnevich, Anastasiya A.; Smith, Jeffrey K.

    2009-01-01

    The effects of feedback on performance and factors associated with it were examined in a large introductory psychology course. The experiment involved college students (N = 464) working on an essay examination under 3 conditions: no feedback, detailed feedback that was perceived by participants to be provided by the course instructor, and detailed…

  2. Circumnutation and its dependence on the gravity response in rice, morning glory and pea plants: verification by spaceflight experiments

    NASA Astrophysics Data System (ADS)

    Takahashi, Hideyuki; Kobayashi, Akie; Fujii, Nobuharu; Yano, Sachiko; Shimazu, Toru; Kim, Hyejeong; Tomita, Yuuta; Miyazawa, Yutaka

    Plant organs display helical growth movement known as circumnutation. This movement helps plant organs find suitable environmental cues. The amplitude, period and shape of the circumnutation differ depending on plant species or organs. Although the mechanism for circumnutation is unclear, it has long been argued whether circumnutation is involved with gravitropic response. Previously, we showed that shoots of weeping morning glory (we1 and we2) are impaired in not only the differentiation of endodermis (gravisensing cells) and gravitropic response, but also winding and circumnutation (Kitazawa et al., PNAS 102: 18742-18747, 2005). Here, we report a reduced circumnutation in the shoots of rice and the roots of pea mutants defective in gravitropic response. Coleoptiles of clinorotated rice seedlings and decapped roots of pea seedlings also showed a reduction of their circumnutational movement. These results suggest that circumnutation is tightly related with gravitropic response. In the proposed spaceflight experiments, “Plant Rotation”, we will verify the hypothesis that circumnutation requires gravity response, by using microgravity environment in KIBO module of the International Space Station. We will grow rice and morning glory plants under both muG and 1G conditions on orbit and monitor their growth by a camera. The downlinked images will be analyzed for the measurements of plant growth and nutational movements. This experiment will enable us to answer the question whether circumnutation depends on gravity response or not.

  3. How do soil texture, plant community composition and earthworms affected the infiltration rate in a grassland plant diversity experiment depending on season?

    NASA Astrophysics Data System (ADS)

    Fischer, Christine; Britta, Merkel; Nico, Eisenhauer; Christiane, Roscher; Sabine, Attinger; Stefan, Scheu; Anke, Hildebrandt

    2013-04-01

    Background and aims: In this study we analyzed the influences of plant community characteristics, soil texture and earthworm presence on infiltration rates on a managed grassland plant diversity experiment assessing the role of biotic and abiotic factors on soil hydrology. Methods: We measured infiltration using a hood infiltrometer in subplots with ambient and reduced earthworm density (earthworm extraction) nested in plots of different plant species richness (1, 4, and 16), plant functional group number and composition (1 to 4; legumes, grasses, small herbs, tall herbs) in early summer (June) and autumn (September, October) 2011. Results: The presence of certain plant functional groups such as grasses and legumes influenced infiltration rates and this effect enhanced during the growing season. Infiltration was significantly higher in plots containing legumes than in plots without, and it was significantly lower in the presence of grasses than in their absence. In early summer, earthworm presence and biomass increased the infiltration rates, independently of plant species richness. In October, plant species richness only affected infiltration rates in reduced earthworm plots. At the end of the growing season earthworm populations were negatively influenced by grasses and positively by legumes. In September, infiltration rates were positive related to the proportion of finer grains. The correlation disappears when removing all plots containing legumes from the sample. For all measurements the infiltration rates decreases from early summer to autumn at the matric potentials at pressure zero and -0.02 m, but not for smaller macropores at matric potentials -0.04 and -0.06m. Conclusions: Considering infiltration rates as ecosystem function, this function will largely depend on the ecosystem composition and season, not on biodiversity per se. Our results indicate that biotic factors are of overriding influence for shaping infiltration rates mainly for larger macropores

  4. Survey of Field Programmable Gate Array Design Guides and Experience Relevant to Nuclear Power Plant Applications

    SciTech Connect

    Bobrek, Miljko; Bouldin, Don; Holcomb, David Eugene; Killough, Stephen M; Smith, Stephen Fulton; Ward, Christina D

    2007-09-01

    From a safety perspective, it is difficult to assess the correctness of FPGA devices without extensive documentation, tools, and review procedures. NUREG/CR-6463, "Review Guidelines on Software Languages for Use in Nuclear Power Plant Safety Systems," provides guidance to the Nuclear Regulatory Commission (NRC) on auditing of programs for safety systems written in ten high-level languages. A uniform framework for the formulation and discussion of language-specific programming guidelines was employed. Comparable guidelines based on a similar framework are needed for FPGA-based systems. The first task involves evaluation of regulatory experience gained by other countries and other agencies, and those captured in existing standards, to identify regulatory approaches that can be adopted by NRC. If existing regulations do not provide a sufficient regulatory basis for adopting relevant regulatory approaches that are uncovered, ORNL will identify the gaps. Information for this report was obtained through publicly available sources such as published papers and presentations. No proprietary information is represented.

  5. Lorentz Force Flowmeter for Liquid Aluminum: Laboratory Experiments and Plant Tests

    NASA Astrophysics Data System (ADS)

    Kolesnikov, Yurii; Karcher, Christian; Thess, André

    2011-06-01

    This article aims to demonstrate that molten metal flow at a high temperature can be measured effectively in a contactless manner by using external direct current magnetic fields. The device applied in the present work is termed Lorentz force flowmeter (LFF) and is based on exposing the flow to a magnet system and measuring the drag force acting on it. Two series of measurements are reported. In the first series, we perform a model experiment in the laboratory using the eutectic alloy GaInSn, which is liquid at room temperature. The second series of measurements is devoted to two plant tests on flow measurement of a liquid aluminum alloy. In both tests, the force acting on the magnet system is measured that is equal to the Lorentz force acting on the flow. To generalize our results, we also derive the scaling law that relates the force acting on a localized magnet system to the flow rate of a fluid with arbitrary electrical conductivity. This law shows that LFF, if properly designed, has a wide range of potential applications in ferrous and nonferrous metallurgy.

  6. [Choice of plant light status for space greenhouse: results of ground-based experience].

    PubMed

    Berkovich, Iu A

    2000-01-01

    To decide on the light status of plants in space greenhouse, a theoretical study was undertaken to correlate specific productivity of space greenhouse with illumination characteristics including vertical PAR flux density (I), photoperiod (tau), and crop leaf index (L). It was demonstrated that in pace with I the daily productivity per a volume unit tended to monotonously approach maximum at I = Ip, whereas the greenhouse energy efficiency ME peaked at I = IE, IK < IE < IP, where IK is a compensation point of the light curve of crop photosynthesis. Proposed are compromise criteria to optimize illumination as a maximum of linear combination of MV and ME and coefficients which account for the cost of a space station volume unit and a unit of board power supply, and as maximum of product Q = MV.ME. Experimental results serve as the basis for a technique for determination of the best, by the Q criterion, light status parameters for three types of space greenhouses: research growth chamber for synchronous cultivation of leaf mustard, wheat growth chamber with fixed crop density, and green conveyer for cultivation of Brassica pekinensis (Lour Rupor). For the last mentioned Q effective I and tau values differed with the conveyer step. The technique allows design of ground-based experiments aimed at determination of the most effective light status of space-grown crops.

  7. Computational techniques for elucidating plant-pathogen interactions from large-scale experiments on fungi and oomycetes.

    PubMed

    Soderlund, Carol

    2009-11-01

    Eukaryotic plant pathogens are responsible for the destruction of billions of dollars worth of crops each year. With large-scale genomics of both pathogens and hosts and the corresponding computational analysis, biologists are now able to gain knowledge about many pathogenic and defense genes concurrently. To study the interactions between these two organism groups, it is necessary to design experiments to elucidate the genes being expressed during the invasion of the pathogen into the host. For the most part, this does not require new software development, though it does require the use of existing software in novel ways. This article provides a broad overview of several key and illustrative experiments and the corresponding computational analyses, outlining the knowledge gained in each. It goes on to describe databases for plant-pathogen data and important initiatives such as Plant-Associated Microbe Gene Ontology. It discusses how various emerging approaches will increase the power of computers in host-pathogen interaction studies.

  8. Protoplast isolation and plant regeneration of guava (Psidium guajava L.) using experiments in mixture-amount design

    Technology Transfer Automated Retrieval System (TEKTRAN)

    A protocol was established for plant regeneration from leaf protoplasts of guava (Psidium guajava L.) using mixture-amount (concentration) experiments. A protoplast yield of 3.7 × 106 (viability > 90 percent) was obtained when 1 g leaf strips were digested in a solution of approximately 0.75 M osmot...

  9. Enhancing Hispanic Minority Undergraduates' Botany Laboratory Experiences: Implementation of an Inquiry-Based Plant Tissue Culture Module Exercise

    ERIC Educational Resources Information Center

    Siritunga, Dimuth; Navas, Vivian; Diffoot, Nanette

    2012-01-01

    Early involvement of students in hands-on research experiences are known to demystify research and promote the pursuit of careers in science. But in large enrollment departments such opportunities for undergraduates to participate in research are rare. To counteract such lack of opportunities, inquiry-based laboratory module in plant tissue…

  10. Feedbacks underlie the resilience of salt marshes and rapid reversal of consumer-driven die-off.

    PubMed

    Altieri, Andrew H; Bertness, Mark D; Coverdale, Tyler C; Axelman, Eric E; Herrmann, Nicholas C; Szathmary, P Lauren

    2013-07-01

    Understanding ecosystem resilience to human impacts is critical for conservation and restoration. The large-scale die-off of New England salt marshes was triggered by overfishing and resulted from decades of runaway crab grazing. In 2009, however, cordgrass began to recover, decreasing die-off -40% by 2010. We used surveys and experiments to test whether plant-substrate feedbacks underlie marsh resilience. Initially, grazer-generated die-off swept through the cordgrass, creating exposed, stressful peat banks that inhibited plant growth. This desertification cycle broke when banks eroded and peat transitioned into mud with fewer herbivores, less grazing, and lower physical stress. Cordgrass reestablished in these areas through a feedback where it engineered a recovery zone by further ameliorating physical stresses and facilitating additional revegetation. Our results reveal that feedbacks can play a critical role in rapid, reversible ecosystem shifts associated with human impacts, and that the interplay of facilitative and consumer interactions should be incorporated into resilience theory.

  11. Indirect human impacts turn off reciprocal feedbacks and decrease ecosystem resilience.

    PubMed

    Bertness, Mark D; Brisson, Caitlin P; Crotty, Sinead M

    2015-05-01

    Creek bank salt marsh die-off is a conservation problem in New England, driven by predator depletion, which releases herbivores from consumer control. Many marshes, however, have begun to recover from die-off. We examined the hypothesis that the loss of the foundation species Spartina alterniflora has decreased facilitator populations, weakening reciprocal positive plant/animal feedbacks, resilience, and slowing recovery. Field surveys and experiments revealed that loss of Spartina leads to decreased biodiversity, and increased mortality and decreased growth of the ribbed mussel Geukensia demissa, a key facilitator of Spartina. Experimental addition of Geukensia facilitators to creek banks accelerated Spartina recovery, showing that their loss limits recovery and the reciprocal feedbacks that drive community resilience. Reciprocal positive feedbacks involving foundation species, often lost to human impacts, may be a common, but generally overlooked mechanism of ecosystem resilience, making their reestablishment a valuable restoration tool.

  12. Square-wave switching in vertical-cavity surface-emitting lasers with polarization-rotated optical feedback: Experiments and simulations

    NASA Astrophysics Data System (ADS)

    Sukow, David W.; Gilfillan, Taylor; Pope, Brenton; Torre, Maria S.; Gavrielides, Athanasios; Masoller, Cristina

    2012-09-01

    We study experimentally the dynamics of vertical-cavity surface-emitting lasers (VCSELs) with polarization-rotated (PR) optical feedback, such that the natural lasing polarization of a VCSEL is rotated by 90 deg and then is reinjected into the laser. We observe noisy, square-wave-like polarization switchings with periodicity slightly longer than twice the delay time, which degrade to (or alternate with) bursts of irregular oscillations. We present results of simulations that are in good agreement with the observations. The simulations demonstrate that close to threshold the regular switching is very sensitive to noise, while well above threshold is less affected by the noise strength. The frequency splitting between the two polarizations plays a key role in the switching regularity, and we identify wide parameter regions where deterministic and robust switching can be observed.

  13. Partial Compensation for Altered Auditory Feedback: A Tradeoff with Somatosensory Feedback?

    ERIC Educational Resources Information Center

    Katseff, Shira; Houde, John; Johnson, Keith

    2012-01-01

    Talkers are known to compensate only partially for experimentally-induced changes to their auditory feedback. In a typical experiment, talkers might hear their F1 feedback shifted higher (so that /[epsilon]/ sounds like /[ash]/, for example), and compensate by lowering F1 in their subsequent speech by about a quarter of that distance. Here, we…

  14. Enhancing the Impact of Formative Feedback on Student Learning through an Online Feedback System

    ERIC Educational Resources Information Center

    Hatziapostolou, Thanos; Paraskakis, Iraklis

    2010-01-01

    Formative feedback is instrumental in the learning experience of a student. It can be effective in promoting learning if it is timely, personal, manageable, motivational, and in direct relation with assessment criteria. Despite its importance, however, research suggests that students are discouraged from engaging in the feedback process primarily…

  15. Accounting Students' Feedback on Feedback in Australian Universities: They're Less than Impressed

    ERIC Educational Resources Information Center

    Watty, Kim; de Lange, Paul; Carr, Rodney; O'Connell, Brendan; Howieson, Bryan; Jacobsen, Ben

    2013-01-01

    Undergraduate accounting students in Australian universities are dissatisfied with the feedback that they currently receive. Recent evidence from the Course Experience Questionnaire (CEQ, a national survey of Australian university graduates) suggests that the accounting discipline ranks poorly on assessment feedback when compared to other…

  16. Global desertification: Drivers and feedbacks

    NASA Astrophysics Data System (ADS)

    D'Odorico, Paolo; Bhattachan, Abinash; Davis, Kyle F.; Ravi, Sujith; Runyan, Christiane W.

    2013-01-01

    Desertification is a change in soil properties, vegetation or climate, which results in a persistent loss of ecosystem services that are fundamental to sustaining life. Desertification affects large dryland areas around the world and is a major cause of stress in human societies. Here we review recent research on the drivers, feedbacks, and impacts of desertification. A multidisciplinary approach to understanding the drivers and feedbacks of global desertification is motivated by our increasing need to improve global food production and to sustainably manage ecosystems in the context of climate change. Classic desertification theories look at this process as a transition between stable states in bistable ecosystem dynamics. Climate change (i.e., aridification) and land use dynamics are the major drivers of an ecosystem shift to a “desertified” (or “degraded”) state. This shift is typically sustained by positive feedbacks, which stabilize the system in the new state. Desertification feedbacks may involve land degradation processes (e.g., nutrient loss or salinization), changes in rainfall regime resulting from land-atmosphere interactions (e.g., precipitation recycling, dust emissions), or changes in plant community composition (e.g., shrub encroachment, decrease in vegetation cover). We analyze each of these feedback mechanisms and discuss their possible enhancement by interactions with socio-economic drivers. Large scale effects of desertification include the emigration of “environmental refugees” displaced from degraded areas, climatic changes, and the alteration of global biogeochemical cycles resulting from the emission and long-range transport of fine mineral dust. Recent research has identified some possible early warning signs of desertification, which can be used as indicators of resilience loss and imminent shift to desert-like conditions. We conclude with a brief discussion on some desertification control strategies implemented in different

  17. The Mailbox Computer System for the IAEA verification experiment on HEU downlending at the Portsmouth Gaseous Diffusion Plant

    SciTech Connect

    Aronson, A.L.; Gordon, D.M.

    2000-07-31

    IN APRIL 1996, THE UNITED STATES (US) ADDED THE PORTSMOUTH GASEOUS DIFFUSION PLANT TO THE LIST OF FACILITIES ELIGIBLE FOR THE APPLICATION OF INTERNATIONAL ATOMIC ENERGY AGENCY (IAEA) SAFEGUARDS. AT THAT TIME, THE US PROPOSED THAT THE IAEA CARRY OUT A ''VERIFICATION EXPERIMENT'' AT THE PLANT WITH RESPECT TO DOOWNBLENDING OF ABOUT 13 METRIC TONS OF HIGHLY ENRICHED URANIUM (HEU) IN THE FORM OF URANIUM HEXAFLUROIDE (UF6). DURING THE PERIOD DECEMBER 1997 THROUGH JULY 1998, THE IAEA CARRIED OUT THE REQUESTED VERIFICATION EXPERIMENT. THE VERIFICATION APPROACH USED FOR THIS EXPERIMENT INCLUDED, AMONG OTHER MEASURES, THE ENTRY OF PROCESS-OPERATIONAL DATA BY THE FACILITY OPERATOR ON A NEAR-REAL-TIME BASIS INTO A ''MAILBOX'' COMPUTER LOCATED WITHIN A TAMPER-INDICATING ENCLOSURE SEALED BY THE IAEA.

  18. [Plant genetic engineering in Monsanto company: from the first laboratory experiments to worldwide practical use].

    PubMed

    Konov, A L; Velchev, M; Parcel, D

    2005-01-01

    The history of modern biotechnology of agricultural plants is briefly considered in the article. Methods of genetic transformation and regeneration of transgenic plants as well as the mechanisms of resistance of genetically modified plants to herbicides and pests are discussed. By the example of genetically modified varieties and hybrids there are shown the ways of solving the problem of weeds and pests. The questions of biosafety legislation in different countries are considered.

  19. "Afterlife experiment": use of MALDI-MS and SIMS imaging for the study of the nitrogen cycle within plants.

    PubMed

    Seaman, Callie; Flinders, Bryn; Eijkel, Gert; Heeren, Ron M A; Bricklebank, Neil; Clench, Malcolm R

    2014-10-21

    As part of a project to demonstrate the science of decay, a series of mass spectrometry imaging experiments were performed. The aim was to demonstrate that decay and decomposition are only part of the story and to show pictorially that atoms and molecules from dead plants and animals are incorporated into new life. Radish plants (Raphanus sativus) were grown hydroponically using a nutrient system containing (15)N KNO3 (98% labeled) as the only source of nitrogen. Plants were cropped and left to ferment in water for 2 weeks to create a radish "tea", which was used as a source of nitrogen for radish grown in a second hydroponics experiment. After 5 weeks of growth, the radish plants were harvested and cryosectioned, and sections were imaged by positive-ion MALDI and SIMS mass spectrometry imaging. The presence of labeled species in the plants grown using (15)N KNO3 as nutrient and those grown from the radish "tea" was readily discernible. The uptake of (15)N into a number of identifiable metabolites has been studied by MALDI-MS and SIMS imaging.

  20. Bone, Calcium and Spaceflight: A Living Systems Experiment Relating Animals and Plants the Effects of Calcium on Plant Growth and Development

    NASA Technical Reports Server (NTRS)

    Reiss-Bubenheim, D.; Navarro, B.J.; Morey-Holton, E.; Dalton, Bonnie P. (Technical Monitor)

    1994-01-01

    This NASA-sponsored educational outreach activity provided local students with information about Ames Research Center's (ARC) role in conducting life sciences research in space. Students were introduced to the scientific method while conducting a plant experiment that correlated with the Spacelab Life Sciences-2 (SLS-2) flight animal experiment of Dr. Emily Morey-Holton entitled "Bone, Calcium and Spaceflight". Students made daily observations, collected data and reported on their findings. Students also had the opportunity to witness the STS-58 landing at Edwards Air Force Base in southern California and attended a briefing given by the Payload Commander, Dr. Rhea Seddon at ARC last month. This classroom experiment providing a hands-on learning opportunity about terrestrial and space biology and, hopefully, introduced the students to new fields of study for future endeavors.

  1. Bacterial disease management: challenges, experience, innovation and future prospects: Challenges in Bacterial Molecular Plant Pathology.

    PubMed

    Sundin, George W; Castiblanco, Luisa F; Yuan, Xiaochen; Zeng, Quan; Yang, Ching-Hong

    2016-12-01

    Plant diseases caused by bacterial pathogens place major constraints on crop production and cause significant annual losses on a global scale. The attainment of consistent effective management of these diseases can be extremely difficult, and management potential is often affected by grower reliance on highly disease-susceptible cultivars because of consumer preferences, and by environmental conditions favouring pathogen development. New and emerging bacterial disease problems (e.g. zebra chip of potato) and established problems in new geographical regions (e.g. bacterial canker of kiwifruit in New Zealand) grab the headlines, but the list of bacterial disease problems with few effective management options is long. The ever-increasing global human population requires the continued stable production of a safe food supply with greater yields because of the shrinking areas of arable land. One major facet in the maintenance of the sustainability of crop production systems with predictable yields involves the identification and deployment of sustainable disease management solutions for bacterial diseases. In addition, the identification of novel management tactics has also come to the fore because of the increasing evolution of resistance to existing bactericides. A number of central research foci, involving basic research to identify critical pathogen targets for control, novel methodologies and methods of delivery, are emerging that will provide a strong basis for bacterial disease management into the future. Near-term solutions are desperately needed. Are there replacement materials for existing bactericides that can provide effective disease management under field conditions? Experience should inform the future. With prior knowledge of bactericide resistance issues evolving in pathogens, how will this affect the deployment of newer compounds and biological controls? Knowledge is critical. A comprehensive understanding of bacterial pathosystems is required to not

  2. Assessment of RELAP5/MOD2 against a natural circulation experiment in Nuclear Power Plant Borssele. International Agreement Report

    SciTech Connect

    Winters, L.

    1993-07-01

    As part of the ICAP (International Code Assessment and Applications Program) agreement between ECN (Netherlands Energy Research Foundation) and USNRC, ECN has performed a number of assessment calculations for the thermohydraulic system analysis code RELAP5/MOD2/36.05. This document describes the assessment of this computer program versus a natural circulation experiment as conducted at the Borssele Nuclear Power Plant. The results of this comparison show that the code RELAP5/MOD2 predicts well the natural circulation behaviour of Nuclear Power Plant Borssele.

  3. Development of the Plant Growth Facility for Use in the Shuttle Middeck and Test Units for Ground-Based Experiments

    NASA Technical Reports Server (NTRS)

    Chapman, David K.; Wells, H. William

    1996-01-01

    The plant growth facility (PGF), currently under development as a Space Shuttle middeck facility for the support of research on higher plants in microgravity, is presented. The PGF provides controlled fluorescent lighting and the active control of temperature, relative humidity and CO2 concentration. These parameters are designed to be centrally controlled by a dedicated microprocessor. The status of the experiment can be displayed for onboard analysis, and will be automatically archived for post-flight analysis. The facility is designed to operate for 15 days and will provide air filtration to remove ethylene and trace organics with replaceable potassium permanganate filters. Similar ground units will be available for pre-flight experimentation.

  4. Female butterflies adapt and allocate their progeny to the host-plant quality of their own larval experience.

    PubMed

    Cahenzli, Fabian; Wenk, Barbara A; Erhardt, Andreas

    2015-07-01

    Recent studies with diverse taxa have shown that parents can utilize their experience of the environment to adapt their offspring's phenotype to the same environmental conditions. Thus, offspring would then perform best under environmental conditions experienced by their parents due to transgenerational phenotypic plasticity. Such an effect has been dubbed transgenerational acclimatization. However, evidence that parents can subsequently ensure the appropriate environmental conditions in order that offspring benefit from transgenerational acclimatization has never been demonstrated. We reared Pieris rapae larvae in the parental generation on high-nitrogen and low-nitrogen host plants, and reared the offspring (F1) of both treatments again on high- and low-nitrogen plants. Furthermore, we tested if females prefer to oviposit on high- or low-nitrogen host plants in two-way choice tests. We here show not only that females adapt their offspring's phenotype to the host-plant quality that they themselves experienced, but that females also mainly oviposit on the host quality to which they adapt their offspring. Moreover, effects of larval host plant on oviposition preference of females increased across two generations in F1-females acclimatized to low-nitrogen host plants, showing an adaptive host shift from one generation to the next. These findings may have profound implications for host-race formation and sympatric speciation.

  5. Near-term lander experiments for growing plants on Mars: requirements for information on chemical and physical properties of Mars regolith.

    PubMed

    Schuerger, Andrew C; Ming, Douglas W; Newsom, Horton E; Ferl, Robert J; McKay, Christopher P

    2002-01-01

    In order to support humans for long-duration missions to Mars, bioregenerative Advanced Life Support (ALS) systems have been proposed that would use higher plants as the primary candidates for photosynthesis. Hydroponic technologies have been suggested as the primary method of plant production in ALS systems, but the use of Mars regolith as a plant growth medium may have several advantages over hydroponic systems. The advantages for using Mars regolith include the likely bioavailability of plant-essential ions, mechanical support for plants, and easy access of the material once on the surface. We propose that plant biology experiments must be included in near-term Mars lander missions in order to begin defining the optimum approach for growing plants on Mars. Second, we discuss a range of soil chemistry and soil physics tests that must be conducted prior to, or in concert with, a plant biology experiment in order to properly interpret the results of plant growth studies in Mars regolith. The recommended chemical tests include measurements on soil pH, electrical conductivity and soluble salts, redox potential, bioavailability of essential plant nutrients, and bioavailability of phytotoxic elements. In addition, a future plant growth experiment should include procedures for determining the buffering and leaching requirements of Mars regolith prior to planting. Soil physical tests useful for plant biology studies in Mars regolith include bulk density, particle size distribution, porosity, water retention, and hydraulic conductivity.

  6. Near-term lander experiments for growing plants on Mars: requirements for information on chemical and physical properties of Mars regolith

    NASA Technical Reports Server (NTRS)

    Schuerger, Andrew C.; Ming, Douglas W.; Newsom, Horton E.; Ferl, Robert J.; McKay, Christopher P.

    2002-01-01

    In order to support humans for long-duration missions to Mars, bioregenerative Advanced Life Support (ALS) systems have been proposed that would use higher plants as the primary candidates for photosynthesis. Hydroponic technologies have been suggested as the primary method of plant production in ALS systems, but the use of Mars regolith as a plant growth medium may have several advantages over hydroponic systems. The advantages for using Mars regolith include the likely bioavailability of plant-essential ions, mechanical support for plants, and easy access of the material once on the surface. We propose that plant biology experiments must be included in near-term Mars lander missions in order to begin defining the optimum approach for growing plants on Mars. Second, we discuss a range of soil chemistry and soil physics tests that must be conducted prior to, or in concert with, a plant biology experiment in order to properly interpret the results of plant growth studies in Mars regolith. The recommended chemical tests include measurements on soil pH, electrical conductivity and soluble salts, redox potential, bioavailability of essential plant nutrients, and bioavailability of phytotoxic elements. In addition, a future plant growth experiment should include procedures for determining the buffering and leaching requirements of Mars regolith prior to planting. Soil physical tests useful for plant biology studies in Mars regolith include bulk density, particle size distribution, porosity, water retention, and hydraulic conductivity.

  7. Feedback linearization for control of air breathing engines

    NASA Technical Reports Server (NTRS)

    Phillips, Stephen; Mattern, Duane

    1991-01-01

    The method of feedback linearization for control of the nonlinear nozzle and compressor components of an air breathing engine is presented. This method overcomes the need for a large number of scheduling variables and operating points to accurately model highly nonlinear plants. Feedback linearization also results in linear closed loop system performance simplifying subsequent control design. Feedback linearization is used for the nonlinear partial engine model and performance is verified through simulation.

  8. Pseudo-Haptic Feedback in Teleoperation.

    PubMed

    Neupert, Carsten; Matich, Sebastian; Scherping, Nick; Kupnik, Mario; Werthschutzky, Roland; Hatzfeld, Christian

    2016-01-01

    In this paper, we develop possible realizations of pseudo-haptic feedback in teleoperation systems based on existing works for pseudo-haptic feedback in virtual reality and the intended applications. We derive four potential factors affecting the performance of haptic feedback (calculation operator, maximum displacement, offset force, and scaling factor), which are analyzed in three compliance identification experiments. First, we analyze the principle usability of pseudo-haptic feedback by comparing information transfer measures for teleoperation and direct interaction. Pseudo-haptic interaction yields well above-chance performance, while direct interaction performs almost perfectly. In order to optimize pseudo-haptic feedback, in the second study we perform a full-factorial experimental design with 36 subjects performing 6,480 trials with 36 different treatments. Information transfer ranges from 0.68 bit to 1.72 bit in a task with a theoretical maximum of 2.6 bit, with a predominant effect of the calculation operator and a minor effect of the maximum displacement. In a third study, short- and long-term learning effects are analyzed. Learning effects regarding the performance of pseudo-haptic feedback cannot be observed for single-day experiments. Tests over 10 days show a maximum increase in information transfer of 0.8 bit. The results show the feasibility of pseudo-haptic feedback for teleoperation and can be used as design basis for task-specific systems.

  9. Facial Feedback Mechanisms in Autistic Spectrum Disorders

    PubMed Central

    van den Heuvel, Claudia; Smeets, Raymond C.

    2008-01-01

    Facial feedback mechanisms of adolescents with Autistic Spectrum Disorders (ASD) were investigated utilizing three studies. Facial expressions, which became activated via automatic (Studies 1 and 2) or intentional (Study 2) mimicry, or via holding a pen between the teeth (Study 3), influenced corresponding emotions for controls, while individuals with ASD remained emotionally unaffected. Thus, individuals with ASD do not experience feedback from activated facial expressions as controls do. This facial feedback-impairment enhances our understanding of the social and emotional lives of individuals with ASD. PMID:18293075

  10. Feedback Requirements for SASE-FELs

    SciTech Connect

    Loos, Henrik; /SLAC

    2012-07-06

    The operation of a Self Amplified Spontaneous Emission (SASE) Free Electron Lasers (FEL) at soft and hard X-ray wavelengths driven by a high brightness electron beam imposes strong requirements on the stability of the accelerator and feedback systems are necessary to both guarantee saturation of the SASE process as well as a stable photon beam for user experiments. Diagnostics for the relevant transverse and longitudinal beam parameters are presented and various examples of feedback systems for bunches with low repetition rate as well as systems for intra bunch train feedbacks are discussed.

  11. Middle-Eastern plant communities tolerate 9 years of drought in a multi-site climate manipulation experiment.

    PubMed

    Tielbörger, Katja; Bilton, Mark C; Metz, Johannes; Kigel, Jaime; Holzapfel, Claus; Lebrija-Trejos, Edwin; Konsens, Irit; Parag, Hadas A; Sternberg, Marcelo

    2014-10-06

    For evaluating climate change impacts on biodiversity, extensive experiments are urgently needed to complement popular non-mechanistic models which map future ecosystem properties onto their current climatic niche. Here, we experimentally test the main prediction of these models by means of a novel multi-site approach. We implement rainfall manipulations--irrigation and drought--to dryland plant communities situated along a steep climatic gradient in a global biodiversity hotspot containing many wild progenitors of crops. Despite the large extent of our study, spanning nine plant generations and many species, very few differences between treatments were observed in the vegetation response variables: biomass, species composition, species richness and density. The lack of a clear drought effect challenges studies classifying dryland ecosystems as most vulnerable to global change. We attribute this resistance to the tremendous temporal and spatial heterogeneity under which the plants have evolved, concluding that this should be accounted for when predicting future biodiversity change.

  12. Does mycorrhizal inoculation benefit plant survival, plant development and small-scale soil fixation? Results from a perennial eco-engineering field experiment in the Swiss Alps.

    NASA Astrophysics Data System (ADS)

    Bast, Alexander; Grimm, Maria; Graf, Frank; Baumhauer, Roland; Gärtner, Holger

    2015-04-01

    In mountain environments superficial slope failures on coarse grained, vegetation-free slopes are common processes and entail a certain risk for humans and socio-economic structures. Eco-engineering measures can be applied to mitigate slope instabilities. In this regard, limited plant survival and growth can be supported by mycorrhizal inoculation, which was successfully tested in laboratory studies. However, related studies on a field scale are lacking. Furthermore, mycorrhizae are known to enhance soil aggregation, which is linked to soil physics such as shear strength, and hence it is a useful indicator for near-surface soil/slope stability. The overall objective of our contribution was to test whether mycorrhizal inoculation can be used to promote eco-engineering measures in steep alpine environments based on a five-year field experiment. We hypothesized that mycorrhizal inoculation (i) enhances soil aggregation, (ii) stimulate plant survival and fine root development, (iii) effects plant performance, (iv) the stimulated root development in turn influences aggregate stability, and (v) that climatic variations play a major role in fine-root development. We established mycorrhizal and non-mycorrhizal treated eco-engineered research plots (hedge layers mainly consisting of Alnus spp. and Salix spp.) on a field experimental scale. The experimental site is in the eastern Swiss Alps at an erosion-prone slope where many environmental conditions can be seen as homogeneous. Soil aggregation, fine root development and plant survival was quantified at the end of four growing seasons (2010, '11, '12, '14). Additionally, growth properties of Alnus spp. and Salix spp. were measured and their biomass estimated. Meteorological conditions, soil temperature and soil water content were recorded. (i) The introduced eco-engineering measures enhanced aggregate stability significantly. In contrast to published greenhouse and laboratory studies, mycorrhizal inoculation delayed soil

  13. The effect of injury on whole-plant senescence: an experiment with two root-sprouting Barbarea species

    PubMed Central

    Martínková, Jana; Šmilauer, Petr; Mihulka, Stanislav; Latzel, Vít; Klimešová, Jitka

    2016-01-01

    Background and Aims Senescence is the process of losing fitness when growing old, and is shaped by the trade-off between maintenance and reproduction that makes reproduction more unsure and maintenance more costly with age. In repeatedly reproducing plants, reductions in growth and fertility are signs of senescence. Disturbance, however, provides an opportunity to reset the ageing clock and consequently potentially ameliorate senescence. Methods To test the effects of disturbance on traits closely related to fitness and thus to senescence, a long-term garden experiment was established with two short-lived perennial congeners, Barbarea vulgaris and Barbarea stricta, that differ in their ability to resprout after injury. In the experiment, five damage treatments were applied to plants in four different phenophases. Key Results It was found that damage to the plant body significantly prolonged life span in B. vulgaris but decreased whole-life seed production in both species. High concentration of seed production in one growing season characterized short life spans. Both more severe damage and a more advanced phenological phase at the time of damage caused reproduction to be spread over more than one growing season and equalized per-season seed production. In terms of seed quality, average weight of a single seed decreased and seed germination rate increased with age regardless of damage. Conclusions Although disturbance is able to reset the ageing clock of plants, it is so harmful to plant fitness that resprouting serves, at best, only to alleviate slightly the signs of senescence. Thus, in terms of whole-life seed production, injured plants were not more successful than uninjured ones in the two studied species. Indeed, in these species, injury only slightly postponed or decelerated senescence and did not cause effective rejuvenation. PMID:26975314

  14. Goal regulation across time: the effects of feedback and affect.

    PubMed

    Ilies, Remus; Judge, Timothy A

    2005-05-01

    This research focused on the processes individuals use to regulate their goals across time. Two studies examined goal regulation following task performance with 6 samples of participants in a series of 8-trial task performance experiments. The experiments involved: (a) 3 task types, (b) 2 goal types, and (c) actual or manipulated performance feedback referring to the focal participant's own performance or to the participant's performance compared with others' performance. Applying multilevel methods, the authors examined (a) how performance feedback influences subsequent goals within individuals across both negative and positive performance feedback ranges, and (b) the mediating role of affect in explaining the relationship between feedback and subsequent goal setting. Results showed that participants adjusted their goals downwardly following negative feedback and created positive goal-performance discrepancies by raising their goals following positive feedback. In each sample, affect mediated substantial proportions of the feedback-goals relationship within individuals.

  15. Nursing Students' Perceptions of Anecdotal Notes as Formative Feedback.

    PubMed

    Quance, Margaret Ann

    2016-08-24

    Anecdotal notes are a method of providing formative feedback to nursing students following clinical experiences. The extant literature on anecdotal notes is written only from the educator perspective, focusing on rationale for and methods of production, rather than on evaluation of effectiveness. A retrospective descriptive study was carried out with a cohort of 283 third year baccalaureate nursing students to explore their perceptions of anecdotal notes as effective formative feedback. The majority of students valued verbal as well as anecdotal note feedback. They preferred to receive feedback before the next learning experience. Students found the quality of feedback varied by instructor. The anecdotal note process was found to meet identified formative feedback requirements as well as the nursing program's requirement for transparency of evaluation and due process. It is necessary to provide professional development to clinical nurse educators to assist them develop high quality formative feedback using anecdotal notes.

  16. How to implement a quality program in a coking plant. The AHMSA experience

    SciTech Connect

    Reyes M, M.A.; Perez, J.L.; Garza, C. de la; Morales, M.

    1995-12-01

    AHMSA (Altos Hornos de Mexico) is the largest integrated Steel Plant in Mexico, with its 3.1 MMMT of Liquid Steel production program for 1995. AHMSA operates two coke plants which began operations in 1955 and 1976. Total coke monthly production capacity amounts to as much as 106,000 Metric Tons (MT). The coke plants working philosophy was discussed and established in 1986 as part of the Quality Improvement Program, where its ultimate goal is to give the best possible coke quality to its main client--the blast furnaces. With this goal in mind, a planned joint effort with their own coal mines was initiated. This paper deals with the implementation process of the Quality Program, and the results of this commitment at the coal mines, coke plants and blast furnaces. The coke quality improvement is shown since 1985 to 1994, as well as the impact on the blast furnace operation.

  17. Decline in exotic tree density facilitates increased plant diversity: the experience from Melaleuca quinquenervia invaded wetlands

    Technology Transfer Automated Retrieval System (TEKTRAN)

    The Australian tree Melaleuca quinquenervia (melaleuca) formed dense monocultural forests several decades after invading Florida and the Caribbean islands. These dominant forests have displaced native vegetation in sensitive wetland systems. We hypothesized that native plant diversity would increa...

  18. No evidence for local adaptation in an invasive alien plant: field and greenhouse experiments tracing a colonization sequence

    PubMed Central

    Pahl, Anna T.; Kollmann, Johannes; Mayer, Andreas; Haider, Sylvia

    2013-01-01

    Background and Aims Local adaptation enables plant species to persist under different environmental conditions. Evolutionary change can occur rapidly in invasive annual species and has been shown to lead to local adaptation. However, the patterns and mechanisms of local adaptation in invasive species along colonization sequences are not yet understood. Thus, in this study the alien annual Impatiens glandulifera was used to investigate local adaptation to distinct habitats that have been consecutively invaded in central Europe. Methods A reciprocal transplant experiment was performed using 15 populations from alluvial deciduous forests, fallow meadows and coniferous upland forests, and a greenhouse experiment was performed in which plants from these habitats were grown under treatments reflecting the main habitat differentiators (shade, soil acidity, competition). Key Results Biomass production, specific leaf area, plant height and relative growth rate differed between habitats in the field experiment and between treatments in the greenhouse, but not between seed origins. Overall, there was no indication of local adaptation in either experiment. Conclusions Since I. glandulifera is a successful invader in many habitats without showing local adaptation, it is suggested that the species is coping with environmental variation by means of high phenotypic plasticity. The species seems to follow a ‘jack-and-master’ strategy, i.e. it is able to maintain high fitness under a wide range of environmental conditions, but performs particularly well in favourable habitats. Therefore, the proposed colonization sequence is likely to be based primarily on changes in propagule pressure. It is concluded that invasive alien plants can become dominant in distinct habitats without local adaptation. PMID:24214934

  19. Evaluation of aquatic plants for removing polar microcontaminants: a microcosm experiment.

    PubMed

    Matamoros, Víctor; Nguyen, Loc Xuan; Arias, Carlos A; Salvadó, Victòria; Brix, Hans

    2012-08-01

    Microcosm wetland systems (5 L containers) planted with Salvinia molesta, Lemna minor, Ceratophyllum demersum, and Elodea canadensis were investigated for the removal of diclofenac, triclosan, naproxen, ibuprofen, caffeine, clofibric acid and MCPA. After 38 days of incubation, 40-99% of triclosan, diclofenac, and naproxen were removed from the planted and unplanted reactors. In covered control reactors no removal was observed. Caffeine and ibuprofen were removed from 40% to 80% in planted reactors whereas removals in control reactors were much lower (2-30%). Removal of clofibric acid and MCPA were negligible in both planted and unplanted reactors. The findings suggested that triclosan, diclofenac, and naproxen were removed predominantly by photodegradation, whereas caffeine and naproxen were removed by biodegradation and/or plant uptake. Pseudo-first-order removal rate constants estimated from nonlinear regressions of time series concentration data were used to describe the contaminant removals. Removal rate constants ranged from 0.003 to 0.299 d(-1), with half-lives from 2 to 248 days. The formation of two major degradation products from ibuprofen, carboxy-ibuprofen and hydroxy-ibuprofen, and a photodegradation product from diclofenac, 1-(8-Chlorocarbazolyl)acetic acid, were followed as a function of time. This study emphasizes that plants contribute to the elimination capacity of microcontaminants in wetlands systems through biodegradation and uptake processes.

  20. Can plants grow on Mars and the moon: a growth experiment on Mars and moon soil simulants.

    PubMed

    Wamelink, G W Wieger; Frissel, Joep Y; Krijnen, Wilfred H J; Verwoert, M Rinie; Goedhart, Paul W

    2014-01-01

    When humans will settle on the moon or Mars they will have to eat there. Food may be flown in. An alternative could be to cultivate plants at the site itself, preferably in native soils. We report on the first large-scale controlled experiment to investigate the possibility of growing plants in Mars and moon soil simulants. The results show that plants are able to germinate and grow on both Martian and moon soil simulant for a period of 50 days without any addition of nutrients. Growth and flowering on Mars regolith simulant was much better than on moon regolith simulant and even slightly better than on our control nutrient poor river soil. Reflexed stonecrop (a wild plant); the crops tomato, wheat, and cress; and the green manure species field mustard performed particularly well. The latter three flowered, and cress and field mustard also produced seeds. Our results show that in principle it is possible to grow crops and other plant species in Martian and Lunar soil simulants. However, many questions remain about the simulants' water carrying capacity and other physical characteristics and also whether the simulants are representative of the real soils.

  1. Can Plants Grow on Mars and the Moon: A Growth Experiment on Mars and Moon Soil Simulants

    PubMed Central

    Wamelink, G. W. Wieger; Frissel, Joep Y.; Krijnen, Wilfred H. J.; Verwoert, M. Rinie; Goedhart, Paul W.

    2014-01-01

    When humans will settle on the moon or Mars they will have to eat there. Food may be flown in. An alternative could be to cultivate plants at the site itself, preferably in native soils. We report on the first large-scale controlled experiment to investigate the possibility of growing plants in Mars and moon soil simulants. The results show that plants are able to germinate and grow on both Martian and moon soil simulant for a period of 50 days without any addition of nutrients. Growth and flowering on Mars regolith simulant was much better than on moon regolith simulant and even slightly better than on our control nutrient poor river soil. Reflexed stonecrop (a wild plant); the crops tomato, wheat, and cress; and the green manure species field mustard performed particularly well. The latter three flowered, and cress and field mustard also produced seeds. Our results show that in principle it is possible to grow crops and other plant species in Martian and Lunar soil simulants. However, many questions remain about the simulants' water carrying capacity and other physical characteristics and also whether the simulants are representative of the real soils. PMID:25162657

  2. Does leaf photosynthesis adapt to CO2-enriched environments? An experiment on plants originating from three natural CO2 springs.

    PubMed

    Onoda, Yusuke; Hirose, Tadaki; Hikosaka, Kouki

    2009-01-01

    Atmospheric CO2 elevation may act as a selective agent, which consequently may alter plant traits in the future. We investigated the adaptation to high CO2 using transplant experiments with plants originating from natural CO2 springs and from respective control sites. We tested three hypotheses for adaptation to high-CO2 conditions: a higher photosynthetic nitrogen use efficiency (PNUE); a higher photosynthetic water use efficiency (WUE); and a higher capacity for carbohydrate transport from leaves. Although elevated growth CO2 enhanced both PNUE and WUE, there was no genotypic improvement in PNUE. However, some spring plants had a higher WUE, as a result of a significant reduction in stomatal conductance, and also a lower starch concentration. Higher natural variation (assessed by the coefficient of variation) within populations in WUE and starch concentration, compared with PNUE, might be responsible for the observed population differentiation. These results support the concept that atmospheric CO2 elevation can act as a selective agent on some plant traits in natural plant communities. Reduced stomatal conductance and reduced starch accumulation are highlighted for possible adaptation to high CO2.

  3. Plant Uptake of Organic Pollutants from Soil: A Critical Review ofBioconcentration Estimates Based on Modelsand Experiments

    SciTech Connect

    McKone, Thomas E.; Maddalena, Randy L.

    2007-01-01

    The role of terrestrial vegetation in transferring chemicals from soil and air into specific plant tissues (stems, leaves, roots, etc.) is still not well characterized. We provide here a critical review of plant-to-soil bioconcentration ratio (BCR) estimates based on models and experimental data. This review includes the conceptual and theoretical formulations of the bioconcentration ratio, constructing and calibrating empirical and mathematical algorithms to describe this ratio and the experimental data used to quantify BCRs and calibrate the model performance. We first evaluate the theoretical basis for the BCR concept and BCR models and consider how lack of knowledge and data limits reliability and consistency of BCR estimates. We next consider alternate modeling strategies for BCR. A key focus of this evaluation is the relative contributions to overall uncertainty from model uncertainty versus variability in the experimental data used to develop and test the models. As a case study, we consider a single chemical, hexahydro-1,3,5-trinitro-1,3,5-triazine (RDX), and focus on variability of bioconcentration measurements obtained from 81 experiments with different plant species, different plant tissues, different experimental conditions, and different methods for reporting concentrations in the soil and plant tissues. We use these observations to evaluate both the magnitude of experimental variability in plant bioconcentration and compare this to model uncertainty. Among these 81 measurements, the variation of the plant/soil BCR has a geometric standard deviation (GSD) of 3.5 and a coefficient of variability (CV-ratio of arithmetic standard deviation to mean) of 1.7. These variations are significant but low relative to model uncertainties--which have an estimated GSD of 10 with a corresponding CV of 14.

  4. Assessment of the antioxidant potential of selected plant extracts--in vitro and in vivo experiments on pork.

    PubMed

    Lahucky, Rudolf; Nuernberg, Karin; Kovac, Lubomir; Bucko, Ondrej; Nuernberg, Gerd

    2010-08-01

    The antioxidant potential of selected plant extracts was assessed in vitro and in vivo experiments on pork. In the in vitro experiment, the anti-oxidative capacity of ethanol-water extract of Melissa officinalis (MW), ethanol-propylene-glycol extracts of M. officinalis (MP), Origanum vulgaris (O) and Salvia officinalis (S) at different dilutions was analysed. Furthermore a 2% essential oil concentrate was added to Origanum (OSi) and Salvia (SSi). In the two in vivo experiments in total 104 Slovak White Meaty pigs were fed with plant extracts (MW and O) at different doses with/without additional vitamin E. In the in vitro experiment Melissa (MW) showed a higher antioxidant potential compared to Origanum and Salvia assessed by TEAC assay. Addition of essential oil to Origanum improved substantially the anti-oxidative capacity. In the in vivo experiment the highest muscle anti-oxidative effect was obtained by feeding 60 ml Origanum. Small improvement in muscle antioxidant potential was observed by feeding Melissa or Origanum in combination with vitamin E. By feeding 10 ml Melissa, Origanum or Salvia the meat quality parameters such as pH(1) and pH(24), drip loss and shear force was not affected. After 5 days storage of meat the redness value was positively affected.

  5. "Feedback" For Instructioal Television.

    ERIC Educational Resources Information Center

    Schramm, Wilbur

    A number of different methods have been used by instructional television (ITV) projects to obtain audience feedback, and some of these are now being used in the ITV system in El Salvador. We know that pretesting programs on a representative sample can bring considerable gains in learning. Another feedback source can be a classroom of pupils in the…

  6. Convolution feedback systems.

    NASA Technical Reports Server (NTRS)

    Desoer, C. A.; Callier, F. M.

    1972-01-01

    Linear time-invariant feedback systems with multiple inputs and multiple outputs are examined. It is demonstrated that no loss of generality takes place considering the feedback to be unity. Necessary and sufficient conditions are derived for the closed-loop impulse response to be stable in a prescribed sense.

  7. Designing Genetic Feedback Controllers.

    PubMed

    Harris, Andreas W K; Dolan, James A; Kelly, Ciarán L; Anderson, James; Papachristodoulou, Antonis

    2015-08-01

    By incorporating feedback around systems we wish to manipulate, it is possible to improve their performance and robustness properties to meet pre-specified design objectives. For decades control engineers have been successfully implementing feedback controllers for complex mechanical and electrical systems such as aircraft and sports cars. Natural biological systems use feedback extensively for regulation and adaptation but apart from the most basic designs, there is no systematic framework for designing feedback controllers in Synthetic Biology. In this paper we describe how classical approaches from linear control theory can be used to close the loop. This includes the design of genetic circuits using feedback control and the presentation of a biological phase lag controller.

  8. The Experience of Implementing an Interprofessional First Year Course for Undergraduate Health Science Students: The Value of Acting on Student Feedback

    ERIC Educational Resources Information Center

    Surjan, Yolanda; Chiarelli, Pauline; Dempsey, Shane; Lyall, David; O'Toole, Gjyn; Snodgrass, Suzanne; Tessier, John

    2010-01-01

    This paper reports on the experiences gathered as a result of the foundation, implementation and on-going development of an interprofessional course for undergraduate health science students in The School of Health Sciences (SHS) at The University of Newcastle. The purpose of the course was to provide commencing students (n=600) with a…

  9. Feedback from the Coal-Face: How the Lived Experience of Women Casual Academics Can Inform Human Resources and Academic Development Policy and Practice

    ERIC Educational Resources Information Center

    Crimmins, Gail

    2017-01-01

    Casual academics form the backbone of learning and teaching practice in higher education in many developed countries and in many respects can be considered the norm around which academic policy and practice might be formed. Yet a narrative inquiry into the lived experience of women casual academics within Australian universities reveals that…

  10. Large-scale production of pharmaceutical proteins in plant cell culture-the Protalix experience.

    PubMed

    Tekoah, Yoram; Shulman, Avidor; Kizhner, Tali; Ruderfer, Ilya; Fux, Liat; Nataf, Yakir; Bartfeld, Daniel; Ariel, Tami; Gingis-Velitski, Svetlana; Hanania, Uri; Shaaltiel, Yoseph

    2015-10-01

    Protalix Biotherapeutics develops recombinant human proteins and produces them in plant cell culture. Taliglucerase alfa has been the first biotherapeutic expressed in plant cells to be approved by regulatory authorities around the world. Other therapeutic proteins are being developed and are currently at various stages of the pipeline. This review summarizes the major milestones reached by Protalix Biotherapeutics to enable the development of these biotherapeutics, including platform establishment, cell line selection, manufacturing process and good manufacturing practice principles to consider for the process. Examples of the various products currently being developed are also presented.

  11. Field experiments with transformed plants reveal the sense of floral scents.

    PubMed

    Kessler, Danny; Gase, Klaus; Baldwin, Ian T

    2008-08-29

    Plants use many means to attract pollinators, including visual cues and odor. We investigated how nonpigment floral chemistry influences nectar removal, floral visitation, florivory, rates of outcrossing, and fitness through both male and female functions. We blocked expression of biosynthetic genes of the dominant floral attractant [benzyl acetone (Nachal1)] and nectar repellent [nicotine (Napmt1/2)] in all combinations in the native tobacco Nicotiana attenuata and measured their effects on plants in their native habitat. Both repellent and attractant were required to maximize capsule production and seed siring in emasculated flowers and flower visitation by native pollinators, whereas nicotine reduced florivory and nectar robbing.

  12. Experience during the commissioning of the Swiss Leibstadt nuclear power plant

    SciTech Connect

    Diener, W.

    1988-01-01

    Leibstadt the first 1000 MW class BWR plant in Switzerland was subject to a comprehensive range of tests. The unit included some newly designed equipment on which special tests were made. The progress of the commissioning was subjected to safety authority permits, issued stepwise upon successful conclusion of previous checks. The zone within which the reactor could operate without instabilities was established, and the proper functioning of safety systems consequent upon the introduction of fault conditions was demonstrated. The test results confirmed the values expected and the plant's efficiency and output figures were better than guaranteed. The fulfillment of the commissioning program has, in part, contributed to Leibstadt's first class early commercial performance.

  13. Reclamation and agricultural reuse of wastewater: the experience of the Cagliari sewage treatment plant (Sardinia, Italy).

    PubMed

    Botti, P; Virdis, A; Solinas, G; Buscarinu, P; Ferralis, M; Marras, G; Spanu, P; Vacca, S

    2009-01-01

    In Sardinia, as in many other Mediterranean regions, recurrent droughts and climate change have dramatically reduced available water resources. As a result of this critical situation, in 1995 the Italian Government declared a state of emergency and drew up a program for financial support by the State and local authorities with the aim of reducing this serious deficit. One of the actions focused on reclaiming and reusing the effluent from the sewage treatment plant of Cagliari. This article reports on the multidisciplinary preliminary study performed by the Ente Acque della Sardegna (ENAS) to evaluate the suitability of reusing Is Arenas effluent for irrigation and on the operation of the tertiary treatment plant.

  14. Experience with Jacobs wind-driven electric generating plant, 1931 - 1957

    NASA Technical Reports Server (NTRS)

    Jacobs, M. L.

    1973-01-01

    Engineering, construction, performance, electric output, and different uses of the wind electric 2500- to 3000-watt plant are outlined. After several years of testing different types of windmills, the three blade aeroplane type of propeller was found to be far superior in power output. By means of a flyball governor operated, variable pitch speed control, the maximum speed of the propeller was accurately and easily controlled, to prevent excessive speeds in high winds and storms. The three blade propeller was found to be necessary to prevent excessive vibration whenever the shift of the wind direction required the plant to change its facing direction on the tower.

  15. Modifications of Morphometrical and Physiological Parameters of Pepper Plants Grown on Artificial Nutrient Medium for Experiments in Spaceflight

    NASA Astrophysics Data System (ADS)

    Nechitailo, Galina S.

    2016-07-01

    MODIFICATIONS OF MORPHOMETRICAL AND PHYSIOLOGICAL PARAMETERS OF PEPPER PLANTS GROWN ON ARTIFICIAL NUTRIENT MEDIUM FOR EXPERIMENTS IN SPACEFLIGHT Lui Min*, Zhao Hui*, Chen Yu*, Lu Jinying*, Li Huasheng*, Sun Qiao*, Nechitajlo G.S.**, Glushchenko N.N.*** *Shenzhou Space Biotechnology Group, China Academy of Space Technology (CAST), **Emanuel Institute of Biochemical Physics of Russian Academy of Sciences (IBCP RAS) mail: spacemal@mail.ru ***V.L. Talrose Institute for Energy Problems of Chemical Physics of Russian Academy of Science (INEPCP RAS) mail: nnglu@ mail.ru In circumstances of space flights, long residence of the staff at space stations and space settlements an optimal engineering system of the life-support allowing to solve a number of technical and psychological problems for successful work and a life of cosmonauts, researchers, etc. is important and prime. In this respect it is necessary to consider growing plants on board of spacecraft as one of the units in a life-support system. It is feasible due to modern development of biotechnologies in growing plants allowing us to receive materials with new improved properties. Thus, a composition and ratio of components of nutrient medium can considerably influence on plants properties. We have developed the nutrient medium in which essential metals such as iron, zinc, copper were added in an electroneutral state in the form of nanoparticles instead of sulfates or other salts of the same metals. Such replacement is appropriate through unique nanoparticles properties: metal nanoparticles are less toxic than their corresponding ionic forms; nanoparticles produce a prolonged effect, serving as a depot for elements in an organism; nanoparticles introduced in biotic doses stimulate the metabolic processes of the organism; nanoparticles effect is multifunctional. Pepper strain LJ-king was used for growing on a nutrient medium with ferrous, zinc, copper nanoparticles in different concentrations. Pepper plants grown on

  16. The impact of three recent coal-fired power plant closings on Pittsburgh air quality: A natural experiment.

    PubMed

    Russell, Marie C; Belle, Jessica H; Liu, Yang

    2017-01-01

    Relative to the rest of the United States, the region of southwestern Pennsylvania, including metropolitan Pittsburgh, experiences high ambient concentrations of fine particulate matter (PM2.5), which is known to be associated with adverse respiratory and cardiovascular health impacts. This study evaluates whether the closing of three coal-fired power plants within the southwestern Pennsylvania region resulted in a significant decrease in PM2.5 concentration. Both PM2.5 data obtained from EPA ground stations in the study region and aerosol optical depth (AOD) data retrieved from the Moderate Resolution Imaging Spectroradiometer (MODIS) instruments onboard the Terra and Aqua satellites were used to investigate regional air quality from January 2011 through December 2014. The impact of the plant closings on PM2.5 concentration and AOD was evaluated using a series of generalized additive models. The model results show that monthly fuel consumption of the Elrama plant, which closed in October of 2012, and monthly fuel consumption of both the Mitchell and Hatfield's Ferry plants, which closed in October of 2013, were significant predictors of both PM2.5 concentration and AOD at EPA ground stations in the study region, after controlling for multiple meteorological factors and long-term, region-wide air quality improvements. The model's power to predict PM2.5 concentration increased from an adjusted R(2) of 0.61 to 0.68 after excluding data from ground stations with higher uncertainty due to recent increases in unconventional natural gas extraction activities. After preliminary analyses of mean PM2.5 concentration and AOD showed a downward trend following each power plant shutdown, results from a series of generalized additive models confirmed that the activity of the three plants that closed, measured by monthly fuel consumption, was highly significant in predicting both AOD and PM2.5 at 12 EPA ground stations; further research on PM2.5 emissions from unconventional

  17. Succession change of microorganisms on plant waste decomposition in simulation modelling field experiment

    NASA Astrophysics Data System (ADS)

    Vinogradova, Julia; Perminova, Evgenia; Khabibullina, Fluza; Kovaleva, Vera; Lapteva, Elena

    2016-04-01

    Plant waste decomposition processes are closely associated with living activity of soil microbiota in aboveground ecosystems. Functional activity of microorganisms and soil invertebrates determines plant material transformation rate whereby changes in plant material chemical composition during destruction - succession change of soil biota. The purpose of the work was revealing the mechanism of microorganisms succession change during plant waste decomposition in middle-taiga green-moss spruce forests and coniferous-deciduous secondary stands formed after earlier cut bilberry spruce forests. The study materials were undisturbed bilberry spruce forest (Sample Plot 1 - SP1) and coniferous-deciduous secondary stands which were formed after tree cutting activities of 2001-2002 (SP2) and 1969 and 1970 (SP3). Plant material decomposition intensity was determined in microcosms isolated into kapron bags with cell size of 1 mm. At SP1 and SP2, test material was living mosses and at SP3 - fallen birch and aspen leaves. Every test material was exposed for 2 years. Destruction rate was calculated as a weight loss for a particular time period. Composition of micromycetes which participated in plant material decomposition was assessed by the method of inoculation of soil extract to Getchinson's medium and acidified Czapek's medium (pH=4.5). Microbe number and biomass was analyzed by the method of luminescent microscopy. Chemical analysis of plant material was done in the certified Ecoanalytical Laboratory of the Institute of Biology Komi SC UrD RAS. Finally, plant material destruction intensity was similar for study plots and comprised 40-44 % weight loss for 2 years. The strongest differences in plant material decomposition rate between undisturbed spruce forests and secondary after-cut stands were observed at first stages of destruction process. In the first exposition year, mineralizing processes were most active in undisturbed spruce forest. Decomposition rate in cuts at that

  18. Experiments on rehabilitation of radioactive metallic waste (RMW) of reactor stainless steels of Siberian chemical plant

    NASA Astrophysics Data System (ADS)

    Kolpakov, G. N.; Zakusilov, V. V.; Demyanenko, N. V.; Mishin, A. S.

    2016-06-01

    Stainless steel pipes, used to cool a reactor plant, have a high cost, and after taking a reactor out of service they must be buried together with other radioactive waste. Therefore, the relevant problem is the rinse of pipes from contamination, followed by returning to operation.

  19. Student Attitudes toward Nuclear Power Plants: A Classroom Experiment in the Field of Environmental Psychology.

    ERIC Educational Resources Information Center

    Spada, Hans; And Others

    1977-01-01

    As part of a senior high school physics unit on nuclear power, changes in student attitudes toward nuclear power plants and problems of energy supply were analyzed. Tests included a situational test, semantic differentials, knowledge or achievement, and a final questionnaire. The results are discussed. (CTM)

  20. Combining phenotypic data from ordinal rating scales in multiple plant experiments

    Technology Transfer Automated Retrieval System (TEKTRAN)

    The explosion of genomic data is revolutionizing plant breeding and genetics research, but in most applications good phenotypic data are crucial for making efficient use of genomic data. While new technologies have considerably improved accuracy and throughput of genotyping, relative slowness of met...

  1. Burning reveals cryptic plant diversity and promotes coexistence in a California prairie restoration experiment

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Grassland and prairie restoration projects in California often result in long-term establishment of only a few native plant species, even when they begin with a diverse seed palette. A likely explanation for the disappearance of certain native species over time is that they are excluded through comp...

  2. An overview of organically bound tritium experiments in plants following a short atmospheric HTO exposure.

    PubMed

    Galeriu, D; Melintescu, A; Strack, S; Atarashi-Andoh, M; Kim, S B

    2013-04-01

    The need for a less conservative, but reliable risk assessment of accidental tritium releases is emphasized in the present debate on the nuclear energy future. The development of a standard conceptual model for accidental tritium releases must be based on the process level analysis and the appropriate experimental database. Tritium transfer from atmosphere to plants and the subsequent conversion into organically bound tritium (OBT) strongly depends on the plant characteristics, seasons, and meteorological conditions, which have a large variability. The present study presents an overview of the relevant experimental data for the short term exposure, including the unpublished information, also. Plenty of experimental data is provided for wheat, rice, and soybean and some for potato, bean, cherry tomato, radish, cabbage, and tangerine as well. Tritiated water (HTO) uptake by plants during the daytime and nighttime has an important role in further OBT synthesis. OBT formation in crops depends on the development stage, length, and condition of exposure. OBT translocation to the edible plant parts differs between the crops analyzed. OBT formation during the nighttime is comparable with that during the daytime. The present study is a preliminary step for the development of a robust model of crop contamination after an HTO accidental release.

  3. Design of Biomass Gasification and Combined Heat and Power Plant Based on Laboratory Experiments

    NASA Astrophysics Data System (ADS)

    Haydary, Juma; Jelemenský, Ľudovít

    Three types of wooden biomass were characterized by calorimetric measurements, proximate and elemental analysis, thermogravimetry, kinetics of thermal decomposition and gas composition. Using the Aspen steady state simulation, a plant with the processing capacity of 18 ton/h of biomass was modelled based on the experimental data obtained under laboratory conditions. The gasification process has been modelled in two steps. The first step of the model describes the thermal decomposition of the biomass based on a kinetic model and in the second step, the equilibrium composition of syngas is calculated by the Gibbs free energy of the expected components. The computer model of the plant besides the reactor model includes also a simulation of other plant facilities such as: feed drying employing the energy from the process, ash and tar separation, gas-steam cycle, and hot water production heat exchangers. The effect of the steam to air ratio on the conversion, syngas composition, and reactor temperature was analyzed. Employment of oxygen and air for partial combustion was compared. The designed computer model using all Aspen simulation facilities can be applied to study different aspects of biomass gasification in a Combined Heat and Power plant.

  4. Possibilities of restration in eutophic shallow lakes and ponds by artificial plants: A scenario of lake shore restration based on field experiments for water quality improvement using artificial plants.

    NASA Astrophysics Data System (ADS)

    Oishi, Tetsuya; Onoda, Yukio; Kayaba, Yuichi

    Submerged plants have an important role of lake environments. However, autonomous growth of them is difficult in entropic shallow lakes and ponds because of loss of light condition or disturbance of bottom sediment. We should pursue the improvement of water quality to restore lake shores. The purpose of this paper was to examin the influence of water quality using filed experiments in the pond which is our facility and to propose how to conduct lake rastrations using artificail plants. As a result of experiments, we have shown that artificial plants may increase transparency better than submerged plants, and decreace phytoplankton by increasing of zooplankton and encourag ing growth of it. It is suggested that artificial plants should be used as first step in restration of submerged plants because it can encourage increace of transparcy at bottom areas and may be able to germinate soil seeds.

  5. Designer labels for plant metabolism: statistical design of isotope labeling experiments for improved quantification of flux in complex plant metabolic networks.

    PubMed

    Nargund, Shilpa; Sriram, Ganesh

    2013-01-27

    Metabolic fluxes are powerful indicators of cell physiology and can be estimated by isotope-assisted metabolic flux analysis (MFA). The complexity of the compartmented metabolic networks of plants has constrained the application of isotope-assisted MFA to them, principally because of poor identifiability of fluxes from the measured isotope labeling patterns. However, flux identifiability can be significantly improved by a priori design of isotope labeling experiments (ILEs). This computational design involves evaluating the effect of different isotope label and isotopomer measurement combinations on flux identifiability, and thereby identifying optimal labels and measurements toward evaluating the fluxes of interest with the highest confidence. This article reports ILE designs for two major, compartmented plant metabolic pathways - the pentose phosphate pathway (PPP) and γ-aminobutyric acid (GABA) shunt. Together, these pathways represent common motifs in plant metabolism including duplication of pathways in different subcellular compartments, reversible reactions and cyclic carbon flow. To compare various ILE designs, we employed statistical A- and D-optimality criteria. Our computations showed that 1,2-(13)C Glc is a powerful and robust label for the plant PPPs, given currently popular isotopomer measurement techniques (single quadrupole mass spectrometry [MS] and 2-D nuclear magnetic resonance [NMR]). Further analysis revealed that this label can estimate several PPP fluxes better than the popular label 1-(13)C Glc. Furthermore, the concurrent measurement of the isotopomers of hexose and pentose moieties synthesized exclusively in the cytosol or the plastid compartments (measurable through intracellular glucose or sucrose, starch, RNA ribose and histidine) considerably improves the identifiability of PPP fluxes in the individual compartments. Additionally, MS-derived isotopomer measurements outperform NMR-derived measurements in identifying PPP fluxes. The

  6. Do alpine plants facilitate each other’s pollination? Experiments at a small spatial scale

    NASA Astrophysics Data System (ADS)

    Sieber, Yasemin; Holderegger, Rolf; Waser, Nickolas M.; Thomas, Vera F. D.; Braun, Sabine; Erhardt, Andreas; Reyer, Heinz-Ulrich; Wirth, Lea R.

    2011-07-01

    Short growing seasons, low temperatures, and frequent strong wind classify high mountains as adverse environments, in which pollinator abundance and activity are reduced. In such environments, plants growing in dense stands comprising several species and thus exhibiting larger and more diverse flower displays may profit by attracting more visits from scarce alpine pollinators than do plants that grow alone or in patches only composed of conspecifics. To study whether aggregation of plants increases (facilitation) or decreases (competition) the attraction of pollinators, we measured the rate and numbers with which insects entered experimental plots in the Swiss Alps, and their behaviour at flowers in plots that they entered. The plots contained individuals of the blue-flowering cushion plant Eritrichium nanum, either alone or mixed with white- to yellowish-flowering Saxifraga species. Pollinators were generally rare: in 55% of 236 observation periods, no pollinators were observed. Over 95% of the pollinators were Diptera. The average probability of observing any insect at all was higher in plots that contained some Saxifraga flowers, including mixed plots, than in those containing only E. nanum flowers. However, although insects tended to choose Saxifraga as the first flower visited in mixed plots, in all other regards their visitation of Saxifraga and E. nanum flowers in such plots was statistically indistinguishable. We also detected no effect of floral neighbourhood on the frequencies of potentially geitonogamous visits or of transitions among individual plants of the same or different species. Thus, our study suggests that the presence of Saxifraga may facilitate visitation to E. nanum at larger spatial scales, but gives no evidence for either competition or facilitation at small scales within floral neighbourhoods.

  7. Learning from both sides: Experiences and opportunities in the investigation of Australian aboriginal medicinal plants.

    PubMed

    Simpson, Bradley S; Claudie, David J; Smith, Nicholas M; McKinnon, Ross A; Semple, Susan J

    2013-01-01

    With one of the oldest surviving cultures in the world, Australian Aboriginal people have developed immense knowledge about the diverse Australian flora. Western scientific investigation of some Australian Aboriginal medicinal plants has demonstrated interesting pharmacological activities and chemistry, however the majority of these species have not yet been extensively examined. We argue that research that is locally initiated and driven by Indigenous traditional owners in collaboration with Western scientists has significant potential to develop new plant-based products. Locally driven medicinal plants research in which traditional owners work as researchers in collaboration with University-based colleagues in the investigation of medicines rather than "stakeholders" or "informants" is one model that may be used in characterising plants with the potential to be developed into sustainable plant-based medicinal products with commercial value. Our team has taken this approach in research located both on traditional homelands and in the laboratory. Research being conducted by the University of South Australia and Chuulangun Aboriginal Corporation has led to patent filing for protection of intellectual property associated with novel compounds and extracts with the potential for development through cosmetic, complementary medicine and pharmaceutical routes. Ongoing research is examining the commercial developmental pathways and requirements for product development in these spaces. This review will address the opportunities that might exist for working in partnership with Australian Indigenous communities, some of the scientific knowledge which has been generated so far from our work together and the lessons learnt since the inception of the collaboration between the Chuulangun Aboriginal Corporation and scientists from the University of South Australia.

  8. Global Feedback Simulator

    SciTech Connect

    Carlos Serrano, Lawrence Doolittle

    2015-10-29

    GFS is a simulation engine that is used for the characterization of Accelerator performance parameters based on the machine layout, configuration and noise sources. It combines extensively tested Feedback models with a longitudinal phase space tracking simulator along with the interaction between the two via beam-based feedback using a computationally efficient simulation engine. The models include beam instrumentation, considerations on loop delays for in both the R and beam-based feedback loops, as well as the ability to inject noise (both correlated and uncorrelated) at different points of the machine including a full characterization of the electron gun performance parameters.

  9. On Gaussian feedback capacity

    NASA Technical Reports Server (NTRS)

    Dembo, Amir

    1989-01-01

    Pinsker and Ebert (1970) proved that in channels with additive Gaussian noise, feedback at most doubles the capacity. Cover and Pombra (1989) proved that feedback at most adds half a bit per transmission. Following their approach, the author proves that in the limit as signal power approaches either zero (very low SNR) or infinity (very high SNR), feedback does not increase the finite block-length capacity (which for nonstationary Gaussian channels replaces the standard notion of capacity that may not exist). Tighter upper bounds on the capacity are obtained in the process. Specializing these results to stationary channels, the author recovers some of the bounds recently obtained by Ozarow.

  10. Stratospheric water vapor feedback.

    PubMed

    Dessler, A E; Schoeberl, M R; Wang, T; Davis, S M; Rosenlof, K H

    2013-11-05

    We show here that stratospheric water vapor variations play an important role in the evolution of our climate. This comes from analysis of observations showing that stratospheric water vapor increases with tropospheric temperature, implying the existence of a stratospheric water vapor feedback. We estimate the strength of this feedback in a chemistry-climate model to be +0.3 W/(m(2)⋅K), which would be a significant contributor to the overall climate sensitivity. One-third of this feedback comes from increases in water vapor entering the stratosphere through the tropical tropopause layer, with the rest coming from increases in water vapor entering through the extratropical tropopause.

  11. Design of the Next Generation Nuclear Plant Graphite Creep Experiments for Irradiation in the Advanced Test Reactor

    SciTech Connect

    S. Blaine Grover

    2009-05-01

    The United States Department of Energy’s Next Generation Nuclear Plant (NGNP) Program will be irradiating six gas reactor graphite creep experiments in the Advanced Test Reactor (ATR) located at the Idaho National Laboratory (INL). The ATR has a long history of irradiation testing in support of reactor development and the INL has been designated as the new United States Department of Energy’s lead laboratory for nuclear energy development. The ATR is one of the world’s premiere test reactors for performing long term, high flux, and/or large volume irradiation test programs. These graphite irradiations are being accomplished to support development of the next generation reactors in the United States. The graphite experiments will be irradiated over the next six to eight years to support development of a graphite irradiation performance data base on the new nuclear grade graphites now available for use in high temperature gas reactors. The goals of the irradiation experiments are to obtain irradiation performance data at different temperatures and loading conditions to support design of the Next Generation Nuclear Plant Very High Temperature Gas Reactor, as well as other future gas reactors. The experiments will each consist of a single capsule that will contain seven separate stacks of graphite specimens. Six of the specimen stacks will have half of their graphite specimens under a compressive load, while the other half of the specimens will not be subjected to a compressive load during irradiation. The six stacks will be organized into pairs with a different compressive load being applied to the top half of each pair of specimen stacks. The seventh stack will not have a compressive load on the graphite specimens during irradiation. The specimens will be irradiated in an inert sweep gas atmosphere with on-line temperature and compressive load monitoring and control. There will also be the capability of sampling the sweep gas effluent to determine if any

  12. Feedback valence affects auditory perceptual learning independently of feedback probability.

    PubMed

    Amitay, Sygal; Moore, David R; Molloy, Katharine; Halliday, Lorna F

    2015-01-01

    Previous studies have suggested that negative feedback is more effective in driving learning than positive feedback. We investigated the effect on learning of providing varying amounts of negative and positive feedback while listeners attempted to discriminate between three identical tones; an impossible task that nevertheless produces robust learning. Four feedback conditions were compared during training: 90% positive feedback or 10% negative feedback informed the participants that they were doing equally well, while 10% positive or 90% negative feedback informed them they were doing equally badly. In all conditions the feedback was random in relation to the listeners' responses (because the task was to discriminate three identical tones), yet both the valence (negative vs. positive) and the probability of feedback (10% vs. 90%) affected learning. Feedback that informed listeners they were doing badly resulted in better post-training performance than feedback that informed them they were doing well, independent of valence. In addition, positive feedback during training resulted in better post-training performance than negative feedback, but only positive feedback indicating listeners were doing badly on the task resulted in learning. As we have previously speculated, feedback that better reflected the difficulty of the task was more effective in driving learning than feedback that suggested performance was better than it should have been given perceived task difficulty. But contrary to expectations, positive feedback was more effective than negative feedback in driving learning. Feedback thus had two separable effects on learning: feedback valence affected motivation on a subjectively difficult task, and learning occurred only when feedback probability reflected the subjective difficulty. To optimize learning, training programs need to take into consideration both feedback valence and probability.

  13. Decreasing fuel-oil consumption through feedback and social commendation.

    PubMed

    Seaver, W B; Patterson, A H

    1976-01-01

    The energy crisis of the winter of 1973-74 led to severe shortages of fuel oil for home heating and a government request for voluntary conservation by the oil consumer. This experiment tested two methods of facilitating fuel-oil conservation. Home fuel-oil consumers were randomly assigned to one of three experimental groups: feedback of information on rate of oil use, feedback plus commendation for reduced consumption, or a no-treatment control. The consumption rate for the feedback plus commendation group was significantly lower than that of either the informational feedback group or the control group. The informational feedback group did not differ from the control group. The results suggest that feedback alone may not result in oil conservation, but that feedback combined with commendation can produce socially significant savings.

  14. Representational momentum is not (totally) impervious to error feedback.

    PubMed

    Ruppel, Susan E; Fleming, Carmen N; Hubbard, Timothy L

    2009-03-01

    The influence of feedback on representational momentum for the final location of a moving target was examined in 3 experiments. The presence of binary feedback (correct, error) during practise trials or during larger blocks of experimental trials did not reduce representational momentum, nor did the presence of more informative feedback specifying the direction of error (error-in front of, error-behind) during larger blocks of experimental trials reduce representational momentum. Effects on representational momentum of whether feedback was consistently provided were inconsistent. Even though feedback did not reduce representational momentum per se, feedback did influence the probability of a same response for different probe positions. Implications of the data for R. A. Finke and J. J. Freyd's (1985; J. J. Freyd, 1987) claim that representational momentum is impervious to error feedback, and possible roles of perceptual learning in representational momentum, are discussed.

  15. Experiment, monitoring, and gradient methods used to infer climate change effects on plant communities yield consistent patterns.

    PubMed

    Elmendorf, Sarah C; Henry, Gregory H R; Hollister, Robert D; Fosaa, Anna Maria; Gould, William A; Hermanutz, Luise; Hofgaard, Annika; Jónsdóttir, Ingibjörg S; Jónsdóttir, Ingibjörg I; Jorgenson, Janet C; Lévesque, Esther; Magnusson, Borgþór; Molau, Ulf; Myers-Smith, Isla H; Oberbauer, Steven F; Rixen, Christian; Tweedie, Craig E; Walker, Marilyn D; Walker, Marilyn

    2015-01-13

    Inference about future climate change impacts typically relies on one of three approaches: manipulative experiments, historical comparisons (broadly defined to include monitoring the response to ambient climate fluctuations using repeat sampling of plots, dendroecology, and paleoecology techniques), and space-for-time substitutions derived from sampling along environmental gradients. Potential limitations of all three approaches are recognized. Here we address the congruence among these three main approaches by comparing the degree to which tundra plant community composition changes (i) in response to in situ experimental warming, (ii) with interannual variability in summer temperature within sites, and (iii) over spatial gradients in summer temperature. We analyzed changes in plant community composition from repeat sampling (85 plant communities in 28 regions) and experimental warming studies (28 experiments in 14 regions) throughout arctic and alpine North America and Europe. Increases in the relative abundance of species with a warmer thermal niche were observed in response to warmer summer temperatures using all three methods; however, effect sizes were greater over broad-scale spatial gradients relative to either temporal variability in summer temperature within a site or summer temperature increases induced by experimental warming. The effect sizes for change over time within a site and with experimental warming were nearly identical. These results support the view that inferences based on space-for-time substitution overestimate the magnitude of responses to contemporary climate warming, because spatial gradients reflect long-term processes. In contrast, in situ experimental warming and monitoring approaches yield consistent estimates of the magnitude of response of plant communities to climate warming.

  16. Experiment, monitoring, and gradient methods used to infer climate change effects on plant communities yield consistent patterns

    PubMed Central

    Elmendorf, Sarah C.; Henry, Gregory H. R.; Hollister, Robert D.; Fosaa, Anna Maria; Gould, William A.; Hermanutz, Luise; Hofgaard, Annika; Jónsdóttir, Ingibjörg S.; Jorgenson, Janet C.; Lévesque, Esther; Magnusson, Borgþór; Molau, Ulf; Myers-Smith, Isla H.; Oberbauer, Steven F.; Rixen, Christian; Tweedie, Craig E.; Walker, Marilyn D.

    2015-01-01

    Inference about future climate change impacts typically relies on one of three approaches: manipulative experiments, historical comparisons (broadly defined to include monitoring the response to ambient climate fluctuations using repeat sampling of plots, dendroecology, and paleoecology techniques), and space-for-time substitutions derived from sampling along environmental gradients. Potential limitations of all three approaches are recognized. Here we address the congruence among these three main approaches by comparing the degree to which tundra plant community composition changes (i) in response to in situ experimental warming, (ii) with interannual variability in summer temperature within sites, and (iii) over spatial gradients in summer temperature. We analyzed changes in plant community composition from repeat sampling (85 plant communities in 28 regions) and experimental warming studies (28 experiments in 14 regions) throughout arctic and alpine North America and Europe. Increases in the relative abundance of species with a warmer thermal niche were observed in response to warmer summer temperatures using all three methods; however, effect sizes were greater over broad-scale spatial gradients relative to either temporal variability in summer temperature within a site or summer temperature increases induced by experimental warming. The effect sizes for change over time within a site and with experimental warming were nearly identical. These results support the view that inferences based on space-for-time substitution overestimate the magnitude of responses to contemporary climate warming, because spatial gradients reflect long-term processes. In contrast, in situ experimental warming and monitoring approaches yield consistent estimates of the magnitude of response of plant communities to climate warming. PMID:25548195

  17. Long-term regional shifts in plant community composition are largely explained by local deer impact experiments.

    PubMed

    Frerker, Katie; Sabo, Autumn; Waller, Donald

    2014-01-01

    The fact that herbivores and predators exert top-down effects to alter community composition and dynamics at lower trophic levels is no longer controversial, yet we still lack evidence of the full nature, extent, and longer-term effects of these impacts. Here, we use results from a set of replicated experiments on the local impacts of white-tailed deer to evaluate the extent to which such impacts could account for half-century shifts in forest plant communities across the upper Midwest, USA. We measured species' responses to deer at four sites using 10-20 year-old deer exclosures. Among common species, eight were more abundant outside the exclosures, seven were commoner inside, and 16 had similar abundances in- and outside. Deer herbivory greatly increased the abundance of ferns and graminoids and doubled the abundance of exotic plants. In contrast, deer greatly reduced tree regeneration, shrub cover (100-200 fold in two species), plant height, plant reproduction, and the abundance of forbs. None of 36 focal species increased in reproduction or grew taller in the presence of deer, contrary to expectations. We compared these results to data on 50-year regional shifts in species abundances across 62 sites. The effects of herbivory by white-tailed deer accurately account for many of the long-term regional shifts observed in species' abundances (R2 = 0.41). These results support the conjecture that deer impacts have driven many of the regional shifts in forest understory cover and composition observed in recent decades. Our ability to link results from shorter-term, local experiments to regional long-term studies of ecological change strengthens the inferences we can draw from both approaches.

  18. Improving planting stock quality: The humboldt experience. Forest Service general technical report (Final)

    SciTech Connect

    Jenkinson, J.L.; Nelson, J.A.; Huddleston, M.E.

    1993-05-01

    A seedling testing program was developed to improve the survival and growth potential of planting stock produced in the USDA Forest Service Humboldt Nursery, situated on the Pacific Coast in northern California. Coastal and inland seed sources of Douglas-fir and eight other conifers in the Pacific Slope forests of western Oregon and northern California were assessed in both nursery and field studies. Seedling top and root growth capacities were evaluated just after lifting and after cold storage, and stored seedlings were tested for suvival and growth on cleared planting sites in the seed zones of origin. Safe lifting and cold storage schedules were defined, and seedling cultural regimes were formulated to produce successful 1-0, 1-1, and 2-0 stock types. Testing deomonstrated the critical elements of reforestation and proved that rapid establishment is attainable on diverse sites. Accomplishments of the Humboldt program recommended similar programs for other forest nurseries and their service regions.

  19. The photovoltaic-powered water desalination plant 'SORO' design, start up, operating experience

    NASA Astrophysics Data System (ADS)

    Neuhaeusser, G.; Mohn, J.; Petersen, G.

    Design features, operational parameters, and test results of a year of operation of the SORO prototype photovoltaic (PV) reverse osmosis salt water desalinization plant are described. Chemicals are added to the salt water to control the pH, prevent formation of compounds which could plug the flow system, and kill bacteria and slime which might grow in the solution. The water is pressurized and forced into contact with membranes which separate the fresh water from the brackish or sea water. The flow rate in the project was 180 l/h, with the main electrical energy load being the high pressure pump and the well pump. Batteries are charged before current is switched to power the desalinization system. The plant yielded 1.50 cu of fresh water/day and is concluded to be a viable design for scale-up to larger production figures, besides being economically competitive with solar desalinization installations where the salt content is 2000 ppm.

  20. 76 FR 73738 - Solicitation of Feedback on the Effectiveness of the Reactor Oversight Process

    Federal Register 2010, 2011, 2012, 2013, 2014

    2011-11-29

    ... COMMISSION Solicitation of Feedback on the Effectiveness of the Reactor Oversight Process AGENCY: Nuclear....gov . The Federal Register notice Soliciting Feedback on the Implementation of the Reactor Oversight... licensed commercial nuclear power plant, issuing Federal Register notices to solicit feedback on the...

  1. Experience from start-ups of the first ANITA Mox plants.

    PubMed

    Christensson, M; Ekström, S; Andersson Chan, A; Le Vaillant, E; Lemaire, R

    2013-01-01

    ANITA™ Mox is a new one-stage deammonification Moving-Bed Biofilm Reactor (MBBR) developed for partial nitrification to nitrite and autotrophic N-removal from N-rich effluents. This deammonification process offers many advantages such as dramatically reduced oxygen requirements, no chemical oxygen demand requirement, lower sludge production, no pre-treatment or requirement of chemicals and thereby being an energy and cost efficient nitrogen removal process. An innovative seeding strategy, the 'BioFarm concept', has been developed in order to decrease the start-up time of new ANITA Mox installations. New ANITA Mox installations are started with typically 3-15% of the added carriers being from the 'BioFarm', with already established anammox biofilm, the rest being new carriers. The first ANITA Mox plant, started up in 2010 at Sjölunda wastewater treatment plant (WWTP) in Malmö, Sweden, proved this seeding concept, reaching an ammonium removal rate of 1.2 kgN/m³ d and approximately 90% ammonia removal within 4 months from start-up. This first ANITA Mox plant is also the BioFarm used for forthcoming installations. Typical features of this first installation were low energy consumption, 1.5 kW/NH4-N-removed, low N₂O emissions, <1% of the reduced nitrogen and a very stable and robust process towards variations in loads and process conditions. The second ANITA Mox plant, started up at Sundets WWTP in Växjö, Sweden, reached full capacity with more than 90% ammonia removal within 2 months from start-up. By applying a nitrogen loading strategy to the reactor that matches the capacity of the seeding carriers, more than 80% nitrogen removal could be obtained throughout the start-up period.

  2. Neijiang Power Plant -- Experiences with the largest CFB boiler in China

    SciTech Connect

    Ye Shenshou; Hotta, A.

    1997-12-31

    The 100 MWe Neijiang Thermal Power Plant owned by Sichuan Electric Power Administration (SEPA) started operation in June 1996. The power plant is equipped with Foster Wheeler CFB Boiler, which is designed to produce 114 kg/s of superheated steam at 98 bar pressure and 540 C temperature. The local Sichuan anthracite coal, which is burned in the boiler, features high ash and high sulphur content and has been difficult to burn in some PC or stoker fired boilers. The new CFB boiler has proven to be very suitable for this coal and large turn-down ratio and good load following capability have been achieved. The Neijiang CFB boiler has demonstrated that the stringent emission levels could be easily achieved with good overall economy. The construction of the project, which was done in a tight schedule jointly with Foster Wheeler and SEPA in close and excellent cooperation, is described in this paper in addition to some technical details of the power plant. Also the observations made during the commissioning as well as the performance data are presented.

  3. Receiving right/wrong feedback: consequences for learning.

    PubMed

    Fazio, Lisa K; Huelser, Barbie J; Johnson, Aaron; Marsh, Elizabeth J

    2010-04-01

    Prior work suggests that receiving feedback that one's response was correct or incorrect (right/wrong feedback) does not help learners, as compared to not receiving any feedback at all (Pashler, Cepeda, Wixted, & Rohrer, 2005). In three experiments we examined the generality of this conclusion. Right/wrong feedback did not aid error correction, regardless of whether participants learned facts embedded in prose (Experiment 1) or translations of foreign vocabulary (Experiment 2). While right/wrong feedback did not improve the overall retention of correct answers (Experiments 1 and 2), it facilitated retention of low-confidence correct answers (Experiment 3). Reviewing the original materials was very useful to learners, but this benefit was similar after receiving either right/wrong feedback or no feedback (Experiments 1 and 2). Overall, right/wrong feedback conveys some information to the learner, but is not nearly as useful as being told the correct answer or having the chance to review the to-be-learned materials.

  4. "Bath salts" and "plant food" products: the experience of one regional US poison center.

    PubMed

    Murphy, Christine M; Dulaney, Anna R; Beuhler, Michael C; Kacinko, Sherri

    2013-03-01

    Abuse of psychogenic substances sold as "bath salts" and "plant food" has escalated in recent years in the United States (USA). Previous reports suggest regional differences in the primary active β-keto phenylalkylamines found in these products and the corresponding signs and symptoms reported after exposure. Currently, there are only limited studies describing the clinical effects associated with reported "bath salts" exposure in the USA. This study describes the clinical effects associated with "bath salt" and "plant food" exposures as reported to the poison center serving the state of North Carolina (Carolinas Poison Center). We performed a retrospective review of the Carolinas Poison Center database for all cases of reported human exposure to "bath salt" and "plant food" products from 2010 to 2011 with specific attention to clinical effects and routes of exposure. Additionally, we reviewed therapies used, trended the volume of exposure cases reported over the study period, and evaluated the distribution of calls within state counties using descriptive statistics. Carolinas Poison Center received 485 total calls and 409 reported exposure calls regarding "bath salt" or "plant food" products between January of 2010 and December of 2011. The peak of reported exposures occurred in May of 2011. Clinical effects commonly reported in the exposure cases generated from these calls included tachycardia (53.3 %, n = 218), agitated/irritable (50.4 %, n = 206), hallucination/delusions (26.7 %, n = 109), and hypertension (25.2 %, n = 103). In addition to intravenous fluids, common therapies included benzodiazepines (46.0 %, n = 188), sedation (13.4 %, n = 55), alkalinization (3.90 %, n = 16), antihistamine (4.16 %, n = 17), and intubation (3.67 %, n = 15). Haloperidol was the antipsychotic agent used most often to treat agitation (n = 40). Serious complications associated with reported exposure to "bath salt" and "plant food" products

  5. Control of force through feedback in small driven systems

    NASA Astrophysics Data System (ADS)

    Dieterich, E.; Camunas-Soler, J.; Ribezzi-Crivellari, M.; Seifert, U.; Ritort, F.

    2016-07-01

    Controlling a time-dependent force applied to single molecules or colloidal particles is crucial for many types of experiments. Since in optical tweezers the primary controlled variable is the position of the trap, imposing a target force requires an active feedback process. We analyze this feedback process for the paradigmatic case of a nonequilibrium steady state generated by a dichotomous force protocol, first theoretically for a colloidal particle in a harmonic trap and then with both simulations and experiments for a long DNA hairpin. For the first setup, we find there is an optimal feedback gain separating monotonic from oscillatory response, whereas a too strong feedback leads to an instability. For the DNA molecule, reaching the target force requires substantial feedback gain since weak feedback cannot overcome the tendency to relax towards the equilibrium force.

  6. Control of force through feedback in small driven systems.

    PubMed

    Dieterich, E; Camunas-Soler, J; Ribezzi-Crivellari, M; Seifert, U; Ritort, F

    2016-07-01

    Controlling a time-dependent force applied to single molecules or colloidal particles is crucial for many types of experiments. Since in optical tweezers the primary controlled variable is the position of the trap, imposing a target force requires an active feedback process. We analyze this feedback process for the paradigmatic case of a nonequilibrium steady state generated by a dichotomous force protocol, first theoretically for a colloidal particle in a harmonic trap and then with both simulations and experiments for a long DNA hairpin. For the first setup, we find there is an optimal feedback gain separating monotonic from oscillatory response, whereas a too strong feedback leads to an instability. For the DNA molecule, reaching the target force requires substantial feedback gain since weak feedback cannot overcome the tendency to relax towards the equilibrium force.

  7. Experience with technical diagnostics of generator shroud rings at thermal plants

    NASA Astrophysics Data System (ADS)

    Dubov, A. A.

    2009-02-01

    Experience with the application of the method of magnetic memory of metal while controlling the state of the generator shroud rings for in-time recognition of damage that develops in the zones of stress concentration is considered.

  8. Analysis of failure and maintenance experiences of motor operated valves in a Finnish nuclear power plant

    NASA Astrophysics Data System (ADS)

    Simola, Kaisa; Laakso, Kari

    1992-01-01

    Eight years of operating experiences of 104 motor operated closing valves in different safety systems in nuclear power units were analyzed in a systematic way. The qualitative methods used were Failure Mode and Effect Analysis (FMEA) and Maintenance Effects and Criticality Analysis (MECA). These reliability engineering methods are commonly used in the design stage of equipment. The successful application of these methods for analysis and utilization of operating experiences was demonstrated.

  9. Feedback: How Does It Function?

    ERIC Educational Resources Information Center

    Bardwell, Rebecca

    1981-01-01

    A study of feedback delay, expectation, and development was conducted in grades four, six, and eight, to assess whether feedback on a school related learning task serves an informational or reinforcing function. Results indicate that feedback serves an informational function and delayed feedback facilitates retention, contrary to reinforcement…

  10. Seven Keys to Effective Feedback

    ERIC Educational Resources Information Center

    Wiggins, Grant

    2012-01-01

    The term "feedback" is often used to describe all kinds of comments made after the fact, including advice, praise, and evaluation. But none of these are feedback, strictly speaking. Basically, feedback is information about how one is doing in his or her efforts to reach a goal. Whether feedback is just there to be grasped or is provided by another…

  11. Teaching Tips: Plant Tissue Testing.

    ERIC Educational Resources Information Center

    Osborne, Ed

    1991-01-01

    Plant tissue testing can be done to monitor plant nutrition levels during the growing season and diagnose nutrient deficiency problems. They can provide feedback on crop conditions and fertility needs. (Author)

  12. Feedback: Now with Physics

    NASA Astrophysics Data System (ADS)

    Hopkins, Philip F.; Quataert, Eliot; Faucher-Giguere, Claude-Andre; Keres, Dusan; Wetzel, Andrew R.; Murray, Norman W.

    2017-01-01

    The most fundamental unsolved problems in galaxy formation revolve around "feedback" from massive stars and black holes. In the last few years, a new generation of theoretical models have emerged which combine new numerical methods and physics in an attempt to realistically model the diverse physics of the interstellar medium, star formation, and feedback from super-massive black holes and massive stars (winds, jets, SNe, and radiation). These mechanisms lead to 'self-regulated' galaxy and star formation, in which global correlations such as the Schmidt-Kennicutt law, the inefficiency of star formation, and the stellar mass function -- emerge naturally. Within galaxies, feedback regulates the structure of the interstellar medium, and many observed properties of the ISM, star formation, and galaxies can be understood as a fundamental consequence of super-sonic turbulence in a rapidly cooling, self-gravitating medium. But feedback also produces galactic super-winds that can dramatically alter the cosmological evolution of galaxies, change the nature of dark matter cores and ‘cusps’, and re-structure the circum-galactic and inter-galactic medium. These winds depend non-linearly on multiple feedback mechanisms in a way that explains why they have been so difficult to model in previous "sub-grid" approaches. This resolves long-standing problems in understanding even apparently "simple" galaxy properties like the mass-metallicity relation. Finally, I'll discuss where feedback fails, and where either additional, exotic physics, or new, previously-dismissed feedback mechanisms, may be needed to explain observations.

  13. Calibrated feedback for laser diodes

    SciTech Connect

    Howard, P.G.

    1986-04-22

    A method is described of calibrating the feedback output from the feedback light detector of the laser diode of an optical disk drive of a laser light pen which consists of mounting a first and a second resistor in a laser light pen; connecting the first resistor between the feedback light detector and ground; connecting the second resistor between the feedback light detector and a feedback output; operating the laser diode to produce a predetermined light power output; adjusting the resistance of the first resistor to produce a predetermined voltage at the feedback output; and adjusting the resistance of the second resistor to produce a predetermined impedance at the feedback output.

  14. Remote feedback stabilization of tokamak instabilities

    SciTech Connect

    Sen, A.K. )

    1994-05-01

    A novel remote suppressor consisting of an injected ion beam has been used for the stabilization of plasma instabilities. A collisionless curvature-driven trapped-particle instability, an [bold E][times][bold B] flute mode and an ion temperature gradient (ITG) instability have been successfully suppressed down to noise levels using this scheme. Furthermore, the first experimental demonstration of a multimode feedback stabilization with a single sensor--suppressor pair has been achieved. Two modes (an [bold E][times][bold B] flute and an ITG mode) were simultaneously stabilized with a simple state-feedback-type method where more state'' information was generated from a single-sensor Langmuir probe by appropriate signal processing. The above experiments may be considered as paradigms for controlling several important tokamak instabilities. First, feedback suppression of edge fluctuations in a tokamak with a suitable form of insulated segmented poloidal limiter sections used as Langmuir-probe-like suppressors is proposed. Other feedback control schemes are proposed for the suppression of electrostatic core fluctuations via appropriately phased ion density input from a modulated neutral beam. Most importantly, a scheme to control major disruptions in tokamaks via feedback suppression of kink (and possibly) tearing modes is discussed. This may be accomplished by using a modulated neutral beam suppressor in a feedback loop, which will supply a momentum input of appropriate phase and amplitude. Simple theoretical models predict modest levels of beam energy, current, and power.

  15. Using experiments and demographic models to assess rare plant vulnerability to utlity-scale solar energy development

    NASA Astrophysics Data System (ADS)

    Moore, K. A.

    2015-12-01

    Pressing challenges for the implementation of solar energy are the effects of construction and operation on protected animal and plant species. Siting and mitigation of solar energy often requires understanding of basic biology and distributions of rare species that are unknown. How can we rapidly collect the information necessary on species- and site-specific population dynamics to effectively design mitigation and conservation measures? We have developed an integrated approach to assessing the vulnerability of a suite of representative rare plant species in the region. We implemented a prioritized series of demographic and experimental studies over the past four years to identify the types of species, populations, and life stages most vulnerable to impact or prone to conservation efforts. We have found substantial variation in vegetative and sexual reproduction between study populations for several rare plants, including between populations that vary in putative impact by development and/or effects of experimental solar arrays. For a subset of species, we designed population viability analysis and applied them to identify sensitive vital rates and compare quasi-extinction probabilities under different climate and impact scenarios. By utilizing practical experiments to test for the effects of real or simulated impacts, we found differences in vital rates between natural and disturbed populations adjacent to and within solar installations. We draw conclusions from our work to guide the analysis of benefits, permitting, and design of utility-scale solar energy facilities.

  16. Plant-Stress Measurements Using Laser-Induced Fluorescence Excitation: Poland Experiment

    SciTech Connect

    Gene Capelle; Steve Jones

    1999-05-01

    Bechtel Nevada's Special Technologies Laboratory (STL) has been involved in remote sensing for many years, and in April 1995 STL began to study the use of active remote sensing for detecting plant stress. This work was motivated by the need to detect subsurface contamination, with the supposition that this could be accomplished by remote measurement of optical signatures from the overgrowing vegetation. The project has been a cooperative DOE/Disney effort, in which basic optical signature measurements (primarily fluorescence) were done at the Disney greenhouse facilities at Epcot Center in Florida, using instrumentation developed by STL on DOE funding. The primary instrument is a LIFI system, which had originally been developed for detection of surface uranium contamination at DOE sites. To deal specifically with the plant stress measurements, a LIFS system was built that utilizes the same laser, but captures the complete fluorescence spectrum from blue to red wavelengths. This system had continued to evolve, and the version in existence in September 1997 was sent to Poland, accompanied by two people from STL, for the purpose of making the measurements described in this report.

  17. Energetic metabolism response in algae and higher plant species from simulation experiments with the clinostat

    NASA Astrophysics Data System (ADS)

    Vasilenko, A.; Popova, A. F.

    Adenylate state is acknowledged to be among the most convenient approaches in the study of physiological changes in plant cells under simulation of altered gravity condition with the clinostat. Adenylate levels and the ATP/ADP ratio in cytoplasmic and mitochondrial extracts of cultivated cells of Haplopappus gracilis and algae cells of Chlorella vulgaris under initial stages of the fast-rotating and slow-rotating clinorotation, as well as the long-term clinorotation, have been investigated. For analysis of ATP and ADP levels in the plant cells under the clinorotation, we applied a high-sensitive bioluminescence method using the luciferase and piruvate kinase enzyme systems. It has been shown that the adenylate ratio is already increased during at the start of clinorotation with the different speed of rotation in the biological material tested. The considerable changes in mitochondrial ultrastructure of Chlorella cells, as well as the rising ATP level and dropping of the ATP/ADP ratio appear after long-duration clinorotation if compared to control material. It is probably connected with the distinctions in ATP-synthetase functioning in mitochondria of the cells under the clinorotation conditions.

  18. Preceptor Development: Providing Effective Feedback, Part 2

    PubMed Central

    Wilkinson, Samaneh T.; Phillips, Holly

    2014-01-01

    Abstract An integral part of providing effective feedback to pharmacy residents occurs during the evaluation process. Residency evaluation involves measuring and documenting performance as it relates to standardized residency outcomes, goals, and learning objectives. Evaluations may be formative or summative and include the preceptor’s evaluation of the resident’s performance, the resident’s self-assessments, and the resident’s evaluation of the preceptor and learning experience. Evaluations are more structured than feedback, and they involve documentation of the verbal feedback that was provided throughout the learning experience. This article will focus on the preceptor’s role in providing effective resident evaluations based on specific learning activities. PMID:24958969

  19. Results of Lasagna process field experiment at the Paducah Gaseous Diffusion Plant

    SciTech Connect

    Athmer, C.J.; Ho, S.V.

    1995-12-31

    The Lasagna process is being developed to remediate clayey soils in-situ. Lasagna is a combination of electrokinetics and in-situ treatment taking place in installed treatment zones. The zones are formed in either horizontal or vertical orientation using modified existing geoengineering processes. A Lasagna field experiment combining electroosmosis with carbon adsorption in the vertical orientation has been conducted at a TCE contaminated DOE site in Paducah, KY. Carbon adsorption was chosen for this first field test so that a material balance could confirm the movement of TCE from the clay to the treatment zones. The results of this experiment are presented in this paper.

  20. The influence of visual feedback and prior knowledge about feedback on vertical aiming strategies.

    PubMed

    Elliott, Digby; Dutoy, Chris; Andrew, Matthew; Burkitt, James J; Grierson, Lawrence E M; Lyons, James L; Hayes, Spencer J; Bennett, Simon J

    2014-01-01

    Two experiments were conducted to examine time and energy optimization strategies for movements made with and against gravity. In Experiment 1, the authors manipulated concurrent visual feedback, and knowledge about feedback. When vision was eliminated upon movement initiation, participants exhibited greater undershooting, both with their primary submovement and their final endpoint, than when vision was available. When aiming downward, participants were more likely to terminate their aiming following the primary submovement or complete a lower amplitude corrective submovement. This strategy reduced the frequency of energy-consuming corrections against gravity. In Experiment 2, the authors eliminated vision of the hand and the target at the end of the movement. This procedure was expected to have its greatest impact under no-vision conditions where no visual feedback was available for subsequent planning. As anticipated, direction and concurrent visual feedback had a profound impact on endpoint bias. Participants exhibited pronounced undershooting when aiming downward and without vision. Differences in undershooting between vision and no vision were greater under blocked feedback conditions. When performers were uncertain about the impending feedback, they planned their movements for the worst-case scenario. Thus movement planning considers the variability in execution, and avoids outcomes that require time and energy to correct.

  1. Soil-plant-biochar interactions and effects on soil C and N cycling in a wheat greenhouse pot experiment.

    NASA Astrophysics Data System (ADS)

    Michie, E.; Panzacchi, P.; Davies, C. A.; Toet, S.; Ineson, P.

    2012-04-01

    Biochar is carbon rich material, able to modify soil qualities and increase soil carbon sequestration. We investigated the benefits, interactions and mechanisms observed when adding biochar (from Miscanthus feedstock) to soil. In a greenhouse experiment with wheat grown in pots under simulated natural conditions, biochars pyrolysed at 360° C and 450° C were applied at 10, 25, and 50 tha-1, with or without nitrogen (urea). These pots were subjected to different water regimes (400 and 800 mm per year) according to a randomised block design. Growth rate, grain yield and total biomass will be related to the biochar production temperature and application rate. The effect of biochar on water availability and C and N cycling will be tested by direct measurements of CO2, CH4 and N2O fluxes from soil using closed dynamic and static chamber methods. Different natural 13C abundance in biochar (Δ13C≈-13) and soil organic matter (SOM; (Δ13C ≈-27) will be used to calculate the relative contribution of biochar to total soil respiration and the potential priming effect of the biochar on SOM. In addition a labelling experiment with 13CO2 will be used to trace C from the atmosphere through the plant, revealing how biochar affects C allocation in plant biomass, rhizodeposition and root respiration. Preliminary results will be presented.

  2. Variable force and visual feedback effects on teleoperator man/machine performance

    NASA Technical Reports Server (NTRS)

    Massimino, Michael J.; Sheridan, Thomas B.

    1989-01-01

    An experimental study was conducted to determine the effects of various forms of visual and force feedback on human performance for several telemanipulation tasks. Experiments were conducted with varying frame rates and subtended visual angles, with and without force feedback.

  3. Global climate feedbacks

    SciTech Connect

    Manowitz, B.

    1990-10-01

    The important physical, chemical, and biological events that affect global climate change occur on a mesoscale -- requiring high spatial resolution for their analysis. The Department of Energy has formulated two major initiatives under the US Global Change Program: ARM (Atmospheric Radiation Measurements), and CHAMMP (Computer Hardware Advanced Mathematics and Model Physics). ARM is designed to use ground and air-craft based observations to document profiles of atmospheric composition, clouds, and radiative fluxes. With research and models of important physical processes, ARM will delineate the relationships between trace gases, aerosol and cloud structure, and radiative transfer in the atmosphere, and will improve the parameterization of global circulation models. The present GCMs do not model important feedbacks, including those from clouds, oceans, and land processes. The purpose of this workshop is to identify such potential feedbacks, to evaluate the uncertainties in the feedback processes (and, if possible, to parameterize the feedback processes so that they can be treated in a GCM), and to recommend research programs that will reduce the uncertainties in important feedback processes. Individual reports are processed separately for the data bases.

  4. Rethinking niche evolution: experiments with natural communities of Protozoa in pitcher plants.

    PubMed

    Miller, Thomas E; Moran, Emma R; terHorst, Casey P

    2014-08-01

    Classic niche theory predicts that competing species will evolve to use different resources and interact less, whereas recent niche-converge ideas predict that species evolve to use similar resources and interact more. Most data supporting niche evolution are based on observations of contemporary niche use, whereas experimental support is quite sparse. We followed the evolution of four species of Protozoa during succession in the water-filled leaves of the pitcher plant, Sarracenia purpurea, and found that evolution in multispecies systems follows a surprising pattern. Over several hundred generations, weak competitors evolved to be stronger, while strong competitors evolved to become weaker, which does not conform to expectations of either niche divergence or convergence. Evolution in this system appears to occur in response to characteristics of a suite of several competitors in the community, rather than pairwise interactions. Ecologists may need to rethink the roles of competition and evolution in structuring communities.

  5. Plant species as indicators of geochemical anomalies: Experiences on Ilex aquifolium (holly)

    NASA Astrophysics Data System (ADS)

    Cellini Legittimo, P.; Ducceschi, L.; Martini, M.

    1995-03-01

    The distribution of Zn, Cd, Pb, and Cu, in plants growing in mineralized and sterile areas of Tuscany has been studied to verify if and to what extent metalaccumulating species represent evidence of geochemical anomalies in soils. Samples of leaves and twigs from trees were collected, and analyzed by means of differential pulse anodic stripping voltammetry (DPASV). Hollies, brambles, and Holm oaks in particular were considered in the mineralized area of Bottino, and the special aptitude of hollies in concentrating Cd with respect to the other metals has been verified. Cadmium has been previously recognized as a pathfinder for zinc ore bodies; the results of this investigation appear to point out the relevance of holly as a bioindicator of geochemical zinc anomalies. Lower metal concentration characterizes the same species from other mineralized and sterile zones, with the exception of the urbanized area of Florence, where relatively higher Zn concentrations in hollies appear to be due to atmospheric pollution.

  6. Operating experience with a 250 kW el molten carbonate fuel cell (MCFC) power plant

    NASA Astrophysics Data System (ADS)

    Bischoff, Manfred; Huppmann, Gerhard

    The MTU MCFC program is carried out by a European consortium comprising the German companies MTU Friedrichshafen GmbH, Ruhrgas AG and RWE Energie AG as well as the Danish company Energi E2 S/A. MTU acts as consortium leader. The company shares a license and technology exchange agreement with Fuel Cell Energy Inc., Danbury, CT, USA (formerly Energy Research Corp., ERC). The program was started in 1990 and covers a period of about 10 years. The highlights of this program to date are: Considerable improvements regarding component stability have been demonstrated on laboratory scale. Manufacturing technology has been developed to a point which enables the consortium to fabricate the porous components on a 250 cm 2 scale. Several large area stacks with 5000-7660 cm 2 cell area and a power range of 3-10 kW have been tested at the facilities in Munich (Germany) and Kyndby (Denmark). These stacks have been supplied by FCE. As far as the system design is concerned it was soon realized that conventional systems do not hold the promise for competitive power plants. A system analysis led to the conclusion that a new innovative design approach is required. As a result the "Hot Module" system was developed by the consortium. A Hot Module combines all the components of a MCFC system operating at the similar temperatures and pressures into a common thermally insulated vessel. In August 1997 the consortium started its first full size Hot Module MCFC test plant at the facilities of Ruhrgas AG in Dorsten, Germany. The stack was assembled in Munich using 292 cell packages purchased from FCE. The plant is based on the consortium's unique and proprietary "Hot Module" concept. It operates on pipeline natural gas and was grid connected on 16 August 1997. After a total of 1500 h of operation, the plant was intentionally shut down in a controlled manner in April 1998 for post-test analysis. The Hot Module system concept has demonstrated its functionality. The safety concept has been

  7. STABILIZED FEEDBACK AMPLIFIER

    DOEpatents

    Fishbine, H.L.; Sewell, C. Jr.

    1957-08-01

    Negative feedback amplifiers, and particularly a negative feedback circuit which is economical on amode power consumption, are described. Basically, the disclosed circuit comprises two tetrode tubes where the output of the first tube is capacitamce coupled to the grid of the second tube, which in turn has its plate coupled to the cathode of the first tube to form a degenerative feedback circuit. Operating potential for screen of the second tube is supplied by connecting the cathode resistor of the first tube to the screen, while the screen is by-passed to the cathode of its tube for the amplified frequencies. Also, the amplifier incorporates a circuit to stabilize the transconductance of the tubes by making the grid potential of each tube interdependent on anode currents of both lubes by voltage divider circuitry.

  8. Stratospheric water vapor feedback

    PubMed Central

    Dessler, A. E.; Schoeberl, M. R.; Wang, T.; Davis, S. M.; Rosenlof, K. H.

    2013-01-01

    We show here that stratospheric water vapor variations play an important role in the evolution of our climate. This comes from analysis of observations showing that stratospheric water vapor increases with tropospheric temperature, implying the existence of a stratospheric water vapor feedback. We estimate the strength of this feedback in a chemistry–climate model to be +0.3 W/(m2⋅K), which would be a significant contributor to the overall climate sensitivity. One-third of this feedback comes from increases in water vapor entering the stratosphere through the tropical tropopause layer, with the rest coming from increases in water vapor entering through the extratropical tropopause. PMID:24082126

  9. Assessing the vegetation canopy influences on wind flow using wind tunnel experiments with artificial plants

    NASA Astrophysics Data System (ADS)

    Hong, Youngjoo; Kim, Dongyeob; Im, Sangjun

    2016-04-01

    Wind erosion causes serious problems and considerable threat in most regions of the world. Vegetation on the ground has an important role in controlling wind erosion by covering soil surface and absorbing wind momentum. A set of wind tunnel experiments was performed to quantitatively examine the effect of canopy structure on wind movement. Artificial plastic vegetations with different porosity and canopy shape were introduced as the model canopy. Normalized roughness length ( Z 0/ H) and shear velocity ratio ( R) were analyzed as a function of roughness density ( λ). Experiments showed that Z 0/ H increases and R decreases as λ reaches a maximum value, λ max, while the values of Z 0/ H and R showed little change with λ value beyond as λ max.

  10. Importance of temperature control for HEFLEX, a biological experiment for Spacelab 1. [plant gravitational physiology study

    NASA Technical Reports Server (NTRS)

    Chapman, D. K.; Brown, A. H.

    1979-01-01

    The importance of temperature control to HEFLEX, a Spacelab experiment designed to measure kinetic properties of Helianthis nutation in a low-g environment, is discussed. It is argued that the development of the HEFLEX experiment has been severely hampered by the inadequate control of ambient air temperature provided by the spacecraft module design. A worst case calculation shows that delivery of only 69% of the maximum yield of useful data from the HEFLEX system is guaranteed; significant data losses from inadequate temperature control are expected. The magnitude of the expected data losses indicates that the cost reductions associated with imprecise temperature controls may prove to be a false economy in the long term.

  11. Improvements in the re-flight of spaceflight experiments on plant tropisms

    NASA Astrophysics Data System (ADS)

    Kiss, John Z.; Millar, Katherine D. L.; Kumar, Prem; Edelmann, Richard E.; Correll, Melanie J.

    2011-02-01

    In order to effectively study phototropism, the directed growth in response to light, we performed a series of experiments in microgravity to better understand light response without the “complications” of a 1-g stimulus. These experiments were named TROPI (for tropisms) and were performed on the European Modular Cultivation System (EMCS), a laboratory facility on the International Space Station (ISS). TROPI-1 was performed in 2006, and while it was a successful experiment, there were a number of technical difficulties. We had the opportunity to perform TROPI-2 in 2010 and were able to optimize experimental conditions as well as to extend the studies of phototropism to fractional gravity created by the EMCS centrifuge. This paper focuses on how the technical improvements in TROPI-2 allowed for a better experiment with increased scientific return. Major modifications in TROPI-2 compared to TROPI-1 included the use of spaceflight hardware that was off-gassed for a longer period and reduced seed storage (less than 2 months) in hardware. These changes resulted in increased seed germination and more vigorous growth of seedlings. While phototropism in response to red illumination was observed in hypocotyls of seedlings grown in microgravity during TROPI-1, there was a greater magnitude of red-light-based phototropic curvature in TROPI-2. Direct downlinking of digital images from the ISS in TROPI-2, rather than the use of analog tapes in TROPI-1, resulted in better quality images and simplified data analyses. In TROPI-2, improved cryo-procedures and the use of the GLACIER freezer during transport of samples back to Earth maintained the low temperature necessary to obtain good-quality RNA required for use in gene profiling studies.

  12. The lapse-rate feedback leads to polar temperature amplification.

    NASA Astrophysics Data System (ADS)

    Grand Graversen, Rune; Langen, Peter; Mauritsen, Thorsten

    2014-05-01

    The atmospheric temperature will change in response to a radiative forcing of the climate system, but the temperature change may not be constant with height in the atmosphere. The dependence of the temperature change on hight gives rise to the lapse-rate feedback. In a warmer climate, the saturated mixing ratio of water vapour increases more at lower than at upper levels in the troposphere. Therefore due to enhanced latent heat release, the atmosphere tends to warm more in the upper than in the lower troposphere in regions where strong convection is present, such as at tropical latitudes. This results in enhanced radiation back to space, and in a more efficient cooling of the Earth system. This is contributing to a negative lapse-rate feedback. The opposite situation prevails at the high latitudes where stable stratification conditions in the lower troposphere result in a larger warming of the surface-near atmosphere than of the upper troposphere. This is contributing to a positive lapse-rate feedback. Hence the lapse-rate feedback is assumed to be negative at low, and positive at high latitudes. Here we explore the lapse-rate feedback and its effect on the climate system using a slab-ocean climate model, the Community Climate System Model version 4. By locking the temperature change throughout the troposphere to that at the surface in calls to the radiation code, the lapse-rate feedback is suppressed on-line in the model. Doubling-of-CO2 experiments where the lapse-rate feedback is suppressed are compared with experiments where it is retained. In a similar way the surface-albedo feedback is suppressed by keeping the surface albedo fixed in the entire model system. On the basis of model versions where either one or both of the feedbacks are suppressed, we are able to separate the effect of the surface-albedo and lapse-rate feedback. For instance we can estimate the contribution to the polar temperature amplification due to each of the feedbacks. The results show

  13. Climate forcings and feedbacks

    NASA Technical Reports Server (NTRS)

    Hansen, James

    1993-01-01

    Global temperature has increased significantly during the past century. Understanding the causes of observed global temperature change is impossible in the absence of adequate monitoring of changes in global climate forcings and radiative feedbacks. Climate forcings are changes imposed on the planet's energy balance, such as change of incoming sunlight or a human-induced change of surface properties due to deforestation. Radiative feedbacks are radiative changes induced by climate change, such as alteration of cloud properties or the extent of sea ice. Monitoring of global climate forcings and feedbacks, if sufficiently precise and long-term, can provide a very strong constraint on interpretation of observed temperature change. Such monitoring is essential to eliminate uncertainties about the relative importance of various climate change mechanisms including tropospheric sulfate aerosols from burning of coal and oil smoke from slash and burn agriculture, changes of solar irradiance changes of several greenhouse gases, and many other mechanisms. The considerable variability of observed temperature, together with evidence that a substantial portion of this variability is unforced indicates that observations of climate forcings and feedbacks must be continued for decades. Since the climate system responds to the time integral of the forcing, a further requirement is that the observations be carried out continuously. However, precise observations of forcings and feedbacks will also be able to provide valuable conclusions on shorter time scales. For example, knowledge of the climate forcing by increasing CFC's relative to the forcing by changing ozone is important to policymakers, as is information on the forcing by CO2 relative to the forcing by sulfate aerosols. It will also be possible to obtain valuable tests of climate models on short time scales, if there is precise monitoring of all forcings and feedbacks during and after events such as a large volcanic eruption

  14. Sex Differences, Positive Feedback and Intrinsic Motivation.

    ERIC Educational Resources Information Center

    Deci, Edward L.; And Others

    The paper presents two experiments which test the "change in feelings of competence and self-determination" proposition of cognitive evaluation theory. This proposition states that when a person receives feedback about his performance on an intrinsically motivated activity this information will affect his sense of competence and…

  15. Learning Intercultural Communication Skills with Virtual Humans: Feedback and Fidelity

    ERIC Educational Resources Information Center

    Lane, H. Chad; Hays, Matthew Jensen; Core, Mark G.; Auerbach, Daniel

    2013-01-01

    In the context of practicing intercultural communication skills, we investigated the role of fidelity in a game-based, virtual learning environment as well as the role of feedback delivered by an intelligent tutoring system. In 2 experiments, we compared variations on the game interface, use of the tutoring system, and the form of the feedback.…

  16. Video-Based Feedback on Student Assessment: Scarily Personal

    ERIC Educational Resources Information Center

    Henderson, Michael; Phillips, Michael

    2015-01-01

    Assessment feedback is an important part of students' learning experiences; however, text-based feedback has limitations. This article proposes an alternative in the form of individualised video recordings of the lecturer discussing each assignment. This research reports on 126 undergraduate and postgraduate students' reactions to 5-minute videos…

  17. From "Plodder" to "Creative": Feedback in Teacher Education

    ERIC Educational Resources Information Center

    Kurtoglu-Hooton, Nur

    2016-01-01

    This article discusses the case study of four student teachers, examining the ways in which a particular kind of feedback--namely, confirmatory feedback--can act as a catalyst for some of the learning and potential change student teachers in a teaching practice group may experience on an initial teacher education programme. It illustrates how one…

  18. Questioning and Feedback in Athletic Training Clinical Education

    ERIC Educational Resources Information Center

    Barnum, Mary G.; Guyer, M. Susan; Levy, Linda S.; Willeford, K. Sean; Sexton, Patrick; Gardner, Greg; Fincher, A. Louise

    2009-01-01

    The purpose of this article is to provide clinical instructors with information and ideas on how to utilize questioning and feedback during clinical experiences. Definitions, purpose, and examples of different questioning skills are provided. Corrective and directive feedback methods are defined with purposes and examples provided of each.…

  19. Advice and Feedback: Elements of Practice for Problem Solving.

    ERIC Educational Resources Information Center

    Phye, Gary D.; Sanders, Cheryl E.

    1994-01-01

    The roles of advice and feedback in the facilitation of online processing during acquisition and subsequent impact on memory-based processing during a delayed problem-solving task were studied in 2 experiments with 123 college students. Results indicate that corrective feedback improves online processing during training. (SLD)

  20. Smart feedback loops

    NASA Astrophysics Data System (ADS)

    Chepurnov, A. S.; Gribov, I. V.; Gudkov, K. A.; Shumakov, A. V.; Shvedunov, V. I.

    1994-12-01

    It is necessary to find the golden mean in allocating the processing resources of a computer control system. Traditionally, feedback loops operate at the lower levels to ensure safe and stable operation of the accelerator. At present we use analogue and digital feedback loops. Some systems, such as the RF, require more complex algorithms. A possible way of providing these, using digital signal processors is described. The results of tests with the Race-Track Microtron Linac are given and the sources of the main internal and external disturbances have been analysed.

  1. Selfing for the design of genomic selection experiments in biparental plant populations.

    PubMed

    McClosky, Benjamin; LaCombe, Jason; Tanksley, Steven D

    2013-11-01

    Self-fertilization (selfing) is commonly used for population development in plant breeding, and it is well established that selfing increases genetic variance between lines, thus increasing response to phenotypic selection. Furthermore, numerous studies have explored how selfing can be deployed to maximal benefit in the context of traditional plant breeding programs (Cornish in Heredity 65:201-211,1990a, Heredity 65:213-220,1990b; Liu et al. in Theor Appl Genet 109:370-376, 2004; Pooni and Jinks in Heredity 54:255-260, 1985). However, the impact of selfing on response to genomic selection has not been explored. In the current study we examined how selfing impacts the two key aspects of genomic selection-GEBV prediction (training) and selection response. We reach the following conclusions: (1) On average, selfing increases genomic selection gains by more than 70 %. (2) The gains in genomic selection response attributable to selfing hold over a wide range population sizes (100-500), heritabilities (0.2-0.8), and selection intensities (0.01-0.1). However, the benefits of selfing are dramatically reduced as the number of QTLs drops below 20. (3) The major cause of the improved response to genomic selection with selfing is through an increase in the occurrence of superior genotypes and not through improved GEBV predictions. While performance of the training population improves with selfing (especially with low heritability and small population sizes), the magnitude of these improvements is relatively small compared with improvements observed in the selection population. To illustrate the value of these insights, we propose a practical genomic selection scheme that substantially shortens the number of generations required to fully capture the benefits of selfing. Specifically, we provide simulation evidence that indicates the proposed scheme matches or exceeds the selection gains observed in advanced populations (i.e. F 8 and doubled haploid) across a broad range of

  2. Towards positive feedbacks between vegetation and tropospheric O3

    NASA Astrophysics Data System (ADS)

    VanLoocke, A. D.; Bernacchi, C. J.; Ainsworth, E. A.; Betzelberger, A. M.

    2011-12-01

    C during the midday for the highest O3 treatment. These results suggest the potential for a positive feedback on O3 through vegetation-induced alterations in atmospheric conditions, in particular, higher temperature favor the formation of O3 and lower humidity slows the destruction of O3. The results of this experiment are a first step in assessing the potential for positive vegetation-O3 feedback because they can only be directly applied to soybean. However, similarities in the responses of other C3 plants to elevated O3 suggest that the observed responses may apply to a wide range of species. Integrating these responses in land-atmosphere modeling studies are needed to quantify how canopy-scale fluxes might translate to positive feedbacks on [O3] in the troposphere.

  3. Self-control of feedback during motor learning: accounting for the absolute amount of feedback using a yoked group with self-control over feedback.

    PubMed

    Hansen, Steve; Pfeiffer, Jacob; Patterson, Jae Todd

    2011-01-01

    A traditional control group yoked to a group that self-controls their reception of feedback receives feedback in the same relative and absolute manner. This traditional control group typically does not learn the task as well as the self-control group. Although the groups are matched for the amount of feedback they receive, the information is provided on trials in which the individual may not request feedback if he or she were provided the opportunity. Similarly, individuals may not receive feedback on trials for which it would be a beneficial learning experience. Subsequently, the mismatch between the provision of feedback and the potential learning opportunity leads to a decrement in retention. The present study was designed to examine motor learning for a yoked group with the same absolute amount of feedback, but who could self-control when they received feedback. Increased mental processing of error detection and correction was expected for the participants in the yoked self-control group because of their choice to employ a limited resource in the form of a decreasing amount of feedback opportunities. Participants in the yoked with self-control group committed fewer errors than the self-control group in retention and the traditional yoked group in both the retention and time transfer blocks. The results suggest that the yoked with self-control group was able to produce efficient learning effects and can be a viable control group for further motor learning studies.

  4. FURTHER EXPERIMENTS ON THE ABSORPTION OF IONS BY PLANTS, INCLUDING OBSERVATIONS ON THE EFFECT OF LIGHT

    PubMed Central

    Hoagland, D. R.; Davis, A. R.

    1923-01-01

    1. The conditions of illumination were found to exert a very significant influence on absorption of ions from dilute solution by Nitella. These conditions were also found to influence the penetration of Br and NO3 into the cell sap. 2. It is concluded that absorption of ions by plants from dilute solutions involves energy exchanges, with light as the ultimate source of the energy. It is suggested that the absorption is intimately related to growth and metabolism. 3. One ion may affect the removal from solution or penetration into the cell sap of another ion present in the same solution, even in solutions of extremely low concentration. It is probable that all three types of relations may exist—anion to anion, cation to cation, and anion to cation. 4. The sulfate and phosphate ions exerted far less influence on the absorption of nitrate than did chlorine and bromine ions. It is suggested as a possibility that sulfate does not penetrate readily to those surfaces at which chlorine, bromine, nitrate, and other ions may become effective. PMID:19872049

  5. Soil matrix tracer contamination and canopy recycling did not impair ¹³CO₂ plant-soil pulse labelling experiments.

    PubMed

    Barthel, Matthias; Sturm, Patrick; Knohl, Alexander

    2011-09-01

    When conducting (13)CO(2) plant-soil pulse labelling experiments, tracer material might cause unwanted side effects which potentially affect δ(13)C measurements of soil respiration (δ(13)C(SR)) and the subsequent data interpretation. First, when the soil matrix is not isolated from the atmosphere, contamination of the soil matrix with tracer material occurs leading to a physical back-diffusion from soil pores. Second, when using canopy chambers continuously, (13)CO(2) is permanently re-introduced into the atmosphere due to leaf respiration which then aids re-assimilation of tracer material by the canopy. Accordingly, two climate chamber experiments on European beech saplings (Fagus sylvatica L.) were conducted to evaluate the influence of soil matrix (13)CO(2) contamination and canopy recycling on soil (13)CO(2) efflux during (13)CO(2) plant-soil pulse labelling experiments. For this purpose, a combined soil/canopy chamber system was developed which separates soil and canopy compartments in order to (a) prevent diffusion of (13)C tracer into the soil chamber during a (13)CO(2) canopy pulse labelling and (b) study stable isotope processes in soil and canopy individually and independently. In combination with laser spectrometry measuring CO(2) isotopologue mixing ratios at a rate of 1 Hz, we were able to measure δ(13)C in canopy and soil at very high temporal resolution. For the soil matrix contamination experiment, (13)CO(2) was applied to bare soil, canopy only or, simultaneously, to soil and canopy of the beech trees. The obtained δ(13)C(SR) fluxes from the different treatments were then compared with respect to label re-appearance, first peak time and magnitude. By determining the δ(13)C(SR) decay of physical (13)CO(2) back-diffusion from bare soils (contamination), it was possible to separate biological and physical components in δ(13)C(SR) of a combined flux of both. A second pulse labelling experiment, with chambers permanently enclosing the canopy

  6. Plant selection and soil legacy enhance long-term biodiversity effects.

    PubMed

    Zuppinger-Dingley, Debra; Flynn, Dan F B; De Deyn, Gerlinde B; Petermann, Jana S; Schmid, Bernhard

    2016-04-01

    Plant-plant and plant-soil interactions can help maintain plant diversity and ecosystem functions. Changes in these interactions may underlie experimentally observed increases in biodiversity effects over time via the selection of genotypes adapted to low or high plant diversity. Little is known, however, about such community-history effects and particularly the role of plant-soil interactions in this process. Soil-legacy effects may occur if co-evolved interactions with soil communities either positively or negatively modify plant biodiversity effects. We tested how plant selection and soil legacy influence biodiversity effects on productivity, and whether such effects increase the resistance of the communities to invasion by weeds. We used two plant selection treatments: parental plants growing in monoculture or in mixture over 8 yr in a grassland biodiversity experiment in the field, which we term monoculture types and mixture types. The two soil-legacy treatments used in this study were neutral soil inoculated with live or sterilized soil inocula collected from the same plots in the biodiversity experiment. For each of the four factorial combinations, seedlings of eight species were grown in monocultures or four-species mixtures in pots in an experimental garden over 15 weeks. Soil legacy (live inoculum) strongly increased biodiversity complementarity effects for communities of mixture types, and to a significantly weaker extent for communities of monoculture types. This may be attributed to negative plant-soil feedbacks suffered by mixture types in monocultures, whereas monoculture types had positive plant-soil feedbacks, in both monocultures and mixtures. Monocultures of mixture types were most strongly invaded by weeds, presumably due to increased pathogen susceptibility, reduced biomass, and altered plant-soil interactions of mixture types. These results show that biodiversity effects in experimental grassland communities can be modified by the evolution of

  7. Social Media and Peer Feedback: What Do Students Really Think about Using Wiki and Facebook as Platforms for Peer Feedback?

    ERIC Educational Resources Information Center

    Demirbilek, Muhammet

    2015-01-01

    Web 2.0 tools are becoming increasingly pervasive in higher education, and as a result, there is increasing interest in the use of online feedback activities. This study investigated students' actual experiences and perceptions using social media, Wiki and Facebook, tools to provide peer feedback on students' instructional material projects and to…

  8. The Next Generation Nuclear Plant/Advanced Gas Reactor Fuel Irradiation Experiments in the Advanced Test Reactor

    SciTech Connect

    S. Blaine Grover

    2009-09-01

    The United States Department of Energy’s Next Generation Nuclear Plant (NGNP) Program will be irradiating eight separate low enriched uranium (LEU) tri-isotopic (TRISO) particle fuel (in compact form) experiments in the Advanced Test Reactor (ATR) located at the Idaho National Laboratory (INL). The ATR has a long history of irradiation testing in support of reactor development and the INL has been designated as the new United States Department of Energy’s lead laboratory for nuclear energy development. The ATR is one of the world’s premiere test reactors for performing long term, high flux, and/or large volume irradiation test programs. These irradiations and fuel development are being accomplished to support development of the next generation reactors in the United States, and will be irradiated over the next ten years to demonstrate and qualify new particle fuel for use in high temperature gas reactors. The goals of the irradiation experiments are to provide irradiation performance data to support fuel process development, to qualify fuel for normal operating conditions, to support development and validation of fuel performance and fission product transport models and codes, and to provide irradiated fuel and materials for post irradiation examination (PIE) and safety testing. The experiments, which will each consist of at least six separate capsules, will be irradiated in an inert sweep gas atmosphere with individual on-line temperature monitoring and control of each capsule. The sweep gas will also have on-line fission product monitoring on its effluent to track performance of the fuel in each individual capsule during irradiation. The first experiment (designated AGR-1) started irradiation in December 2006, and the second experiment (AGR-2) is currently in the design phase. The design of test trains, as well as the support systems and fission product monitoring system that will monitor and control the experiment during irradiation will be discussed. In

  9. School Formative Feedback Systems

    ERIC Educational Resources Information Center

    Halverson, Richard

    2010-01-01

    Data-driven instructional improvement relies on developing coherent systems that allow school staff to generate, interpret, and act upon quality formative information on students and school programs. This article offers a formative feedback system model that captures how school leaders and teachers structure artifacts and practices to create…

  10. Feedback in Information Retrieval.

    ERIC Educational Resources Information Center

    Spink, Amanda; Losee, Robert M.

    1996-01-01

    As Information Retrieval (IR) has evolved, it has become a highly interactive process, rooted in cognitive and situational contexts. Consequently the traditional cybernetic-based IR model does not suffice for interactive IR or the human approach to IR. Reviews different views of feedback in IR and their relationship to cybernetic and social…

  11. Signatures of AGN feedback

    NASA Astrophysics Data System (ADS)

    Wylezalek, Dominika; Zakamska, Nadia L.; MaNGA-GMOS Team

    2017-01-01

    Feedback from actively accreting SMBHs (Active Galactic Nuclei, AGN) is now widely considered to be the main driver in regulating the growth of massive galaxies. Observational proof for this scenario has, however, been hard to come by. Many attempts at finding a conclusive observational proof that AGN may be able to quench star formation and regulate the host galaxies' growth have shown that this problem is highly complex.I will present results from several projects that focus on understanding the power, reach and impact of feedback processes exerted by AGN. I will describe recent efforts in our group of relating feedback signatures to the specific star formation rate in their host galaxies, where our results are consistent with the AGN having a `negative' impact through feedback on the galaxies' star formation history (Wylezalek+2016a,b). Furthermore, I will show that powerful AGN-driven winds can be easily hidden and not be apparent in the integrated spectrum of the galaxy. This implies that large IFU surveys, such as the SDSS-IV MaNGA survey, might uncover many previously unknown AGN and outflows that are potentially very relevant for understanding the role of AGN in galaxy evolution (Wylezalek+2016c)!

  12. Polarization feedback laser stabilization

    DOEpatents

    Esherick, Peter; Owyoung, Adelbert

    1988-01-01

    A system for locking two Nd:YAG laser oscillators includes an optical path for feeding the output of one laser into the other with different polarizations. Elliptical polarization is incorporated into the optical path so that the change in polarization that occurs when the frequencies coincide may be detected to provide a feedback signal to control one laser relative to the other.

  13. Review of Assessment Feedback

    ERIC Educational Resources Information Center

    Li, Jinrui; De Luca, Rosemary

    2014-01-01

    This article reviews 37 empirical studies, selected from 363 articles and 20 journals, on assessment feedback published between 2000 and 2011. The reviewed articles, many of which came out of studies in the UK and Australia, reflect the most current issues and developments in the area of assessing disciplinary writing. The article aims to outline…

  14. Exploring Students' Concepts of Feedback as Articulated in Large-Scale Surveys: A Useful Proxy and Some Encouraging Nuances

    ERIC Educational Resources Information Center

    Carver, Mark

    2016-01-01

    Surveys asking Higher Education students about feedback tend to find similar results: feedback should be prompt, specific, understandable and regular. Efforts to improve the feedback experience therefore emphasises that feedback be more frequent, detailed and turnaround times reduced. However, indications that students misunderstand key phrases in…

  15. Global negative vegetation feedback to climate warming responses of leaf litter decomposition rates in cold biomes.

    PubMed

    Cornelissen, Johannes H C; van Bodegom, Peter M; Aerts, Rien; Callaghan, Terry V; van Logtestijn, Richard S P; Alatalo, Juha; Chapin, F Stuart; Gerdol, Renato; Gudmundsson, Jon; Gwynn-Jones, Dylan; Hartley, Anne E; Hik, David S; Hofgaard, Annika; Jónsdóttir, Ingibjörg S; Karlsson, Staffan; Klein, Julia A; Laundre, Jim; Magnusson, Borgthor; Michelsen, Anders; Molau, Ulf; Onipchenko, Vladimir G; Quested, Helen M; Sandvik, Sylvi M; Schmidt, Inger K; Shaver, Gus R; Solheim, Bjørn; Soudzilovskaia, Nadejda A; Stenström, Anna; Tolvanen, Anne; Totland, Ørjan; Wada, Naoya; Welker, Jeffrey M; Zhao, Xinquan

    2007-07-01

    Whether climate change will turn cold biomes from large long-term carbon sinks into sources is hotly debated because of the great potential for ecosystem-mediated feedbacks to global climate. Critical are the direction, magnitude and generality of climate responses of plant litter decomposition. Here, we present the first quantitative analysis of the major climate-change-related drivers of litter decomposition rates in cold northern biomes worldwide. Leaf litters collected from the predominant species in 33 global change manipulation experiments in circum-arctic-alpine ecosystems were incubated simultaneously in two contrasting arctic life zones. We demonstrate that longer-term, large-scale changes to leaf litter decomposition will be driven primarily by both direct warming effects and concomitant shifts in plant growth form composition, with a much smaller role for changes in litter quality within species. Specifically, the ongoing warming-induced expansion of shrubs with recalcitrant leaf litter across cold biomes would constitute a negative feedback to global warming. Depending on the strength of other (previously reported) positive feedbacks of shrub expansion on soil carbon turnover, this may partly counteract direct warming enhancement of litter decomposition.

  16. Competition and soil resource environment alter plant–soil feedbacks for native and exotic grasses

    PubMed Central

    Larios, Loralee; Suding, Katharine N.

    2015-01-01

    Feedbacks between plants and soil biota are increasingly identified as key determinants of species abundance patterns within plant communities. However, our understanding of how plant–soil feedbacks (PSFs) may contribute to invasions is limited by our understanding of how feedbacks may shift in the light of other ecological processes. Here we assess how the strength of PSFs may shift as soil microbial communities change along a gradient of soil nitrogen (N) availability and how these dynamics may be further altered by the presence of a competitor. We conducted a greenhouse experiment where we grew native Stipa pulchra and exotic Avena fatua, alone and in competition, in soils inoculated with conspecific and heterospecific soil microbial communities conditioned in low, ambient and high N environments. Stipa pulchra decreased in heterospecific soil and in the presence of a competitor, while the performance of the exotic A. fatua shifted with soil microbial communities from altered N environments. Moreover, competition and soil microbial communities from the high N environment eliminated the positive PSFs of Stipa. Our results highlight the importance of examining how individual PSFs may interact in a broader community context and contribute to the establishment, spread and dominance of invaders. PMID:25425557

  17. The impact of parametrized convection on cloud feedback.

    PubMed

    Webb, Mark J; Lock, Adrian P; Bretherton, Christopher S; Bony, Sandrine; Cole, Jason N S; Idelkadi, Abderrahmane; Kang, Sarah M; Koshiro, Tsuyoshi; Kawai, Hideaki; Ogura, Tomoo; Roehrig, Romain; Shin, Yechul; Mauritsen, Thorsten; Sherwood, Steven C; Vial, Jessica; Watanabe, Masahiro; Woelfle, Matthew D; Zhao, Ming

    2015-11-13

    We investigate the sensitivity of cloud feedbacks to the use of convective parametrizations by repeating the CMIP5/CFMIP-2 AMIP/AMIP + 4K uniform sea surface temperature perturbation experiments with 10 climate models which have had their convective parametrizations turned off. Previous studies have suggested that differences between parametrized convection schemes are a leading source of inter-model spread in cloud feedbacks. We find however that 'ConvOff' models with convection switched off have a similar overall range of cloud feedbacks compared with the standard configurations. Furthermore, applying a simple bias correction method to allow for differences in present-day global cloud radiative effects substantially reduces the differences between the cloud feedbacks with and without parametrized convection in the individual models. We conclude that, while parametrized convection influences the strength of the cloud feedbacks substantially in some models, other processes must also contribute substantially to the overall inter-model spread. The positive shortwave cloud feedbacks seen in the models in subtropical regimes associated with shallow clouds are still present in the ConvOff experiments. Inter-model spread in shortwave cloud feedback increases slightly in regimes associated with trade cumulus in the ConvOff experiments but is quite similar in the most stable subtropical regimes associated with stratocumulus clouds. Inter-model spread in longwave cloud feedbacks in strongly precipitating regions of the tropics is substantially reduced in the ConvOff experiments however, indicating a considerable local contribution from differences in the details of convective parametrizations. In both standard and ConvOff experiments, models with less mid-level cloud and less moist static energy near the top of the boundary layer tend to have more positive tropical cloud feedbacks. The role of non-convective processes in contributing to inter-model spread in cloud feedback

  18. The impact of parametrized convection on cloud feedback

    PubMed Central

    Webb, Mark J.; Lock, Adrian P.; Bretherton, Christopher S.; Bony, Sandrine; Cole, Jason N. S.; Idelkadi, Abderrahmane; Kang, Sarah M.; Koshiro, Tsuyoshi; Kawai, Hideaki; Ogura, Tomoo; Roehrig, Romain; Shin, Yechul; Mauritsen, Thorsten; Sherwood, Steven C.; Vial, Jessica; Watanabe, Masahiro; Woelfle, Matthew D.; Zhao, Ming

    2015-01-01

    We investigate the sensitivity of cloud feedbacks to the use of convective parametrizations by repeating the CMIP5/CFMIP-2 AMIP/AMIP + 4K uniform sea surface temperature perturbation experiments with 10 climate models which have had their convective parametrizations turned off. Previous studies have suggested that differences between parametrized convection schemes are a leading source of inter-model spread in cloud feedbacks. We find however that ‘ConvOff’ models with convection switched off have a similar overall range of cloud feedbacks compared with the standard configurations. Furthermore, applying a simple bias correction method to allow for differences in present-day global cloud radiative effects substantially reduces the differences between the cloud feedbacks with and without parametrized convection in the individual models. We conclude that, while parametrized convection influences the strength of the cloud feedbacks substantially in some models, other processes must also contribute substantially to the overall inter-model spread. The positive shortwave cloud feedbacks seen in the models in subtropical regimes associated with shallow clouds are still present in the ConvOff experiments. Inter-model spread in shortwave cloud feedback increases slightly in regimes associated with trade cumulus in the ConvOff experiments but is quite similar in the most stable subtropical regimes associated with stratocumulus clouds. Inter-model spread in longwave cloud feedbacks in strongly precipitating regions of the tropics is substantially reduced in the ConvOff experiments however, indicating a considerable local contribution from differences in the details of convective parametrizations. In both standard and ConvOff experiments, models with less mid-level cloud and less moist static energy near the top of the boundary layer tend to have more positive tropical cloud feedbacks. The role of non-convective processes in contributing to inter-model spread in cloud

  19. Greenhouse (III): Gas-Exchange and Seed-to-Seed Experiments on the Russian Space Station MIR and Earth-grown, Ethylene-Treated Wheat Plants

    NASA Technical Reports Server (NTRS)

    Campbell, William F.; Bingham, Gail; Carman, John; Bubenheim, David; Levinskikh, Margarita; Sytchev, Vladimir N.; Podolsky, Igor B.; Chernova, Lola; Nefodova, Yelena

    2001-01-01

    The Mir Space Station provided an outstanding opportunity to study long-term plant responses when exposed to a microgravity environment. Furthermore, if plants can be grown to maturity in a microgravity environment, they might be used in future bioregenerative life-support systems (BLSS). The primary objective of the Greenhouse experiment onboard Mir was to grow Super Dwarf and Apogee wheat through complete life cycles in microgravity; i.e., from seed-to-seed-to-seed. Additional objectives were to study chemical, biochemical, and structural changes in plant tissues as well as photosynthesis, respiration, and transpiration (evaporation of water from plants). Another major objective was to evaluate the suitability clothe facilities on Mir for advanced research with plants. The Greenhouse experiment was conducted in the Russian/Bulgarian plant growth chamber, the Svet, to which the United States added instrumentation systems to monitor changes in CO2 and water vapor caused by the plants (with four infrared gas analyzers monitoring air entering and leaving two small plastic chambers). In addition, the US instrumentation also monitored O2; air, leaf (IR), cabin pressure; photon flux; and substrate temperature and substrate moisture (16 probes in the root module). Facility modifications were first performed during the summer of 1995 during Mir 19, which began after STS-72 left Mir. Plant development was monitored by daily observations and some photographs.

  20. The reproducibility of liquid chromatography separation technology and its potential impact on large scale plant metabolomics experiments.

    PubMed

    Arens, Nadja; Döll, Stefanie; Mock, Hans-Peter

    2015-06-01

    Unraveling the constituents of biological samples using HPLC is a central core technology in metabolomics experiments. Consistency in retention time across many samples is a critical criterion for judging the quality of a data set, which must be met before further analysis are possible. Here, the performance of two ultra high-performance liquid chromatography (UHPLC) systems has been compared using an established separation protocol optimized for phenylpropanoids, a class of secondary compounds found in plants displaying intermediate polarity. The two systems differed markedly with respect to their reproducibility and pressure stability. The standard deviation of the retention time of representative peaks differs up to 30-folds between the systems. Adjustments made to the gradient profiles succeeded in equalizing their level of performance. However, the modifications made to the separation protocol reduced the quality of the separation, particularly of the more rapidly eluting components, and lengthened the run time.

  1. Engineering development of a digital replacement protection system at an operating US PWR nuclear power plant: Installation and operational experiences

    SciTech Connect

    Miller, M.H.

    1995-04-01

    The existing Reactor Protection Systems (RPSs) at most US PWRs are systems which reflect 25 to 30 year-old designs, components and manufacturing techniques. Technological improvements, especially in relation to modern digital systems, offer improvements in functionality, performance, and reliability, as well as reductions in maintenance and operational burden. The Nuclear power industry and the US nuclear regulators are poised to move forward with the issues that have slowed the transition to modern digital replacements for nuclear power plant safety systems. The electric utility industry is now more than ever being driven by cost versus benefit decisions. Properly designed, engineered, and installed digital systems can provide adequate cost-benefit and allow continued nuclear generated electricity. This paper describes various issues and areas related to an ongoing RPS replacement demonstration project which are pertinant for a typical US nuclear plant to consider cost-effective replacement of an aging analog RPS with a modern digital RPS. The following subject areas relative to the Oconee Nuclear Station ISAT{trademark} Demonstrator project are discussed: Operator Interface Development; Equipment Qualification; Validation and Verification of Software; Factory Testing; Field Changes and Verification Testing; Utility Operational, Engineering and Maintenance; Experiences with Demonstration System; and Ability to operate in parallel with the existing Analog RPS.

  2. Hexachlorobenzene dechlorination as affected by organic fertilizer and urea applications in two rice planted paddy soils in a pot experiment.

    PubMed

    Liu, C Y; Jiang, X; Yang, X L; Song, Y

    2010-01-15

    Reductive dechlorination is a crucial pathway for HCB degradation, the applications of organic materials and nitrogen can alter microbial activity and redox potential of soils, thus probably influence HCB dechlorination. To evaluate hexachlorobenzene (HCB) dechlorination as affected by organic fertilizer (OF) and urea applications in planted paddy soils, a pot experiment was conducted in two types of soils, Hydragric Acrisols (Ac) and Gleyi-Stagnic Anthrosols (An). After 18 weeks of experiment, HCB residues decreased by 28.2-37.5% of the initial amounts in Ac, and 42.1-70.9% in An. The amounts of HCB metabolites showed that dechlorination rates in An were higher than in Ac, which was mainly attributed to the higher pH and dissolved organic carbon (DOC) content of An. Both in Ac and An, the additions of 1% and 2% OF had negative effect on HCB dechlorination, which was probably because excessive nitrogen in OF decreased degraders' activity and the degradation of organic carbon in OF accepted electrons. The application of 0.03% urea could enhance HCB dechlorination rates slightly, while 0.06% urea accelerated HCB dechlorination significantly both in Ac and An. It could be assumed that urea served as an electron donor and stimulated degraders to dechlorinate HCB. In addition, the methanogenic bacteria were involved in dechlorination process, and reductive dechlorination in planted paddy soil might be impeded for the aerenchyma and O(2) supply into the rhizosphere. Results indicated that soil types, rice root system, methanogenic bacteria, OF and urea applications all had great effects on dechlorination process.

  3. Design and Sampling Plan Optimization for RT-qPCR Experiments in Plants: A Case Study in Blueberry.

    PubMed

    Die, Jose V; Roman, Belen; Flores, Fernando; Rowland, Lisa J

    2016-01-01

    The qPCR assay has become a routine technology in plant biotechnology and agricultural research. It is unlikely to be technically improved, but there are still challenges which center around minimizing the variability in results and transparency when reporting technical data in support of the conclusions of a study. There are a number of aspects of the pre- and post-assay workflow that contribute to variability of results. Here, through the study of the introduction of error in qPCR measurements at different stages of the workflow, we describe the most important causes of technical variability in a case study using blueberry. In this study, we found that the stage for which increasing the number of replicates would be the most beneficial depends on the tissue used. For example, we would recommend the use of more RT replicates when working with leaf tissue, while the use of more sampling (RNA extraction) replicates would be recommended when working with stems or fruits to obtain the most optimal results. The use of more qPCR replicates provides the least benefit as it is the most reproducible step. By knowing the distribution of error over an entire experiment and the costs at each step, we have developed a script to identify the optimal sampling plan within the limits of a given budget. These findings should help plant scientists improve the design of qPCR experiments and refine their laboratory practices in order to conduct qPCR assays in a more reliable-manner to produce more consistent and reproducible data.

  4. Crystal accumulation in the Hanford Waste Treatment Plant high level waste melter: Summary of FY2016 experiements

    SciTech Connect

    Fox, K.; Fowley, M.; Miller, D.

    2016-12-01

    Five experiments were completed with the full-scale, room temperature Hanford Waste Treatment and Immobilization Plant (WTP) high-level waste (HLW) melter riser test system to observe particle flow and settling in support of a crystal tolerant approach to melter operation. A prototypic pour rate was maintained based on the volumetric flow rate. Accumulation of particles was observed at the bottom of the riser and along the bottom of the throat after each experiment. Measurements of the accumulated layer thicknesses showed that the settled particles at the bottom of the riser did not vary in thickness during pouring cycles or idle periods. Some of the settled particles at the bottom of the throat were re-suspended during subsequent pouring cycles, and settled back to approximately the same thickness after each idle period. The cause of the consistency of the accumulated layer thicknesses is not year clear, but was hypothesized to be related to particle flow back to the feed tank. Additional experiments reinforced the observation of particle flow along a considerable portion of the throat during idle periods. Limitations of the system are noted in this report and may be addressed via future modifications. Follow-on experiments will be designed to evaluate the impact of pouring rate on particle re-suspension, the influence of feed tank agitation on particle accumulation, and the effect of changes in air lance positioning on the accumulation and re-suspension of particles at the bottom of the riser. A method for sampling the accumulated particles will be developed to support particle size distribution analyses. Thicker accumulated layers will be intentionally formed via direct addition of particles to select areas of the system to better understand the ability to continue pouring and re-suspend particles. Results from the room temperature system will be correlated with observations and data from the Research Scale Melter (RSM) at Pacific Northwest National Laboratory

  5. The role of auditory feedback in vocal learning and maintenance

    PubMed Central

    Tschida, Katherine; Mooney, Richard

    2011-01-01

    Auditory experience is critical for the acquisition and maintenance of learned vocalizations in both humans and songbirds. Despite the central role of auditory feedback in vocal learning and maintenance, where and how auditory feedback affects neural circuits important to vocal control remain poorly understood. Recent studies of singing birds have uncovered neural mechanisms by which feedback perturbations affect vocal plasticity and also have identified feedback-sensitive neurons at or near sites of auditory and vocal motor interaction. Additionally, recent studies in marmosets have underscored that even in the absence of vocal learning, vocalization remains flexible in the face of changing acoustical environments, pointing to rapid interactions between auditory and vocal motor systems. Finally, recent studies show that a juvenile songbird’s initial auditory experience of a song model has long-lasting effects on sensorimotor neurons important to vocalization, shedding light on how auditory memories and feedback interact to guide vocal learning. PMID:22137567

  6. Design/build/mockup of the Waste Isolation Pilot Plant gas generation experiment glovebox

    SciTech Connect

    Rosenberg, K.E.; Benjamin, W.W.; Knight, C.J.; Michelbacher, J.A.

    1996-10-01

    A glovebox was designed, fabricated, and mocked-up for the WIPP Gas Generation Experiments (GGE) being conducted at ANL-W. GGE will determine the gas generation rates from materials in contact handled transuranic waste at likely long term repository temperature and pressure conditions. Since the customer`s schedule did not permit time for performing R&D of the support systems, designing the glovebox, and fabricating the glovebox in a serial fashion, a parallel approach was undertaken. As R&D of the sampling system and other support systems was initiated, a specification was written concurrently for contracting a manufacturer to design and build the glovebox and support equipment. The contractor understood that the R&D being performed at ANL-W would add additional functional requirements to the glovebox design. Initially, the contractor had sufficient information to design the glovebox shell. Once the shell design was approved, ANL-W built a full scale mockup of the shell out of plywood and metal framing; support systems were mocked up and resultant information was forwarded to the glovebox contractor to incorporate into the design. This approach resulted in a glovebox being delivered to ANL-W on schedule and within budget.

  7. Certifying the Waste Isolation Pilot Plant: Lessons Learned from the WIPP Experience

    SciTech Connect

    Anderson, D.R.; Chu, Margaret S.Y.; Froehlich, Gary K.; Howard, Bryan A.; Howarth, Susan M.; Larson, Kurt W.; Pickering, Susan Y.; Swift, Peter N.

    1999-07-13

    In May 1998, the US Environmental Protection Agency (EPA) certified the US Department of Energy's (DOE) Waste Isolation Pilot Plant (WIPP) as being in compliance with applicable long-term regulations governing the permanent disposal of spent nuclear fuel, high-level, and transuranic radioactive wastes. The WIPP is the first deep geologic repository in the US to have successfully demonstrated regulatory compliance with long-term radioactive waste disposal requirements. The first disposal of TRU waste at WIPP occurred on March 26, 1999. Many of the lessons learned during the WIPP Project's transition from site characterization and experimental research to the preparation of a successful application may be of general interest to other repository programs. During a four-year period (1992 to 1996), the WIPP team [including the DOE Carlsbad Area Office (CAO), the science advisor to CAO, Sandia National Laboratories (SNL), and the management and operating contractor of the WIPP site, Westinghouse Electric Corporation (WID)] met its aggressive schedule for submitting the application without compromising the integrity of the scientific basis for the long-term safety of the repository. Strong leadership of the CAO-SNL-WID team was essential. Within SNL, a mature and robust performance assessment (PA) allowed prioritization of remaining scientific activities with respect to their impact on regulatory compliance. Early and frequent dialog with EPA staff expedited the review process after the application was submitted. Questions that faced SNL are familiar to geoscientists working in site evaluation projects. What data should be gathered during site characterization? How can we know when data are sufficient? How can we know when our understanding of the disposal system is sufficient to support our conceptual models? What constitutes adequate ''validation'' of conceptual models for processes that act over geologic time? How should we use peer review and expert judgment? Other

  8. How to Give Professional Feedback

    ERIC Educational Resources Information Center

    Brookhart, Susan M.; Moss, Connie M.

    2015-01-01

    Professional learning "should be a joy," the authors write, "not an affliction." Feedback experts Brookhart and Moss show how professional feedback can best motivate educators to learn. Professional conversations should be dialogs between the teacher and the principal, and feedback should feed teacher professional learning…

  9. Feedback: Part of a System

    ERIC Educational Resources Information Center

    Wiliam, Dylan

    2012-01-01

    Just as a thermostat adjusts room temperature, effective feedback helps maintain a supportive environment for learning. Because of the many factors affecting how recipients respond to feedback, research offers no simple prescription for making feedback work effectively. What works in one classroom for one teacher will not work for another teacher.…

  10. Deriving Implementation Strategies for Outcome Monitoring Feedback from Theory, Research and Practice.

    PubMed

    de Jong, Kim

    2016-05-01

    Outcome monitoring feedback is a promising intervention to enhance outcomes of clinical practice. However, effective implementation can be tough and research suggests that feedback is not equally effective under all circumstances. In this article, feedback theory, research and experience from clinical practice is used to provide implementation strategies. Factors that moderate the effectiveness of outcome monitoring feedback, including feedback, recipient and organization characteristics are discussed. It is important to pay attention to implementation processes, such as providing sufficient training for clinicians, in order for feedback to be capable of enhancing outcomes.

  11. [Disaster nursing: one nurse's role and experience during the Fukushima Power Plant disaster following the Great East Japan Earthquake].

    PubMed

    Kamei, Yukari; Lee, Shao-Huai

    2012-06-01

    The Richter-scale 9.0 earthquake that struck Northeast Japan on March 11th, 2011 caused a tsunami that damaged the Fukushima No. 1 Power Plant and released enormous amounts of radiation into the environment. Many area residents were evacuated to several protected fallout shelters. Prior to the tsunami, Fukashima had around 505,760 residents over 65 years of age, comprising 24.9% of the city's pre-tsunami population of Fukushima (City of Fukushima, 2011). The high proportion of elderly contributed to difficulties encountered in evacuating and caring for Fukushima citizens in the immediate aftermath of the disaster. The first author participated in disaster relief efforts in two fallout shelters in Fukushima. This article was written to share her post-disaster care experience and learned knowledge with medical care professionals in Taiwan and other high earthquake risk areas. The article also offers guidelines on appropriate medical personnel response and behavior with regard to disaster response. We hope this experience-sharing offers positive suggestions for the future and facilitates improved disaster-care education in East Asia and enhanced international cooperation on disaster rescue.

  12. DISTRIBUTED AMPLIFIER INCORPORATING FEEDBACK

    DOEpatents

    Bell, P.R. Jr.

    1958-10-21

    An improved distributed amplifier system employing feedback for stabilization is presented. In accordance with the disclosed invention, a signal to be amplified is applled to one end of a suitable terminated grid transmission line. At intervals along the transmission line, the signal is fed to stable, resistance-capacitance coupled amplifiers incorporating feedback loops therein. The output current from each amplifier is passed through an additional tube to minimize the electrostatic capacitance between the tube elements of the last stage of the amplifier, and fed to appropriate points on an output transmission line, similar to the grid line, but terminated at the opposite (input) end. The output taken from the unterminated end of the plate transmission line is proportional to the input voltage impressed upon the grid line.

  13. Regenerative feedback resonant circuit

    DOEpatents

    Jones, A. Mark; Kelly, James F.; McCloy, John S.; McMakin, Douglas L.

    2014-09-02

    A regenerative feedback resonant circuit for measuring a transient response in a loop is disclosed. The circuit includes an amplifier for generating a signal in the loop. The circuit further includes a resonator having a resonant cavity and a material located within the cavity. The signal sent into the resonator produces a resonant frequency. A variation of the resonant frequency due to perturbations in electromagnetic properties of the material is measured.

  14. Polarization feedback laser stabilization

    DOEpatents

    Esherick, P.; Owyoung, A.

    1987-09-28

    A system for locking two Nd:YAG laser oscillators includes an optical path for feeding the output of one laser into the other with different polarizations. Elliptical polarization is incorporated into the optical path so that the change in polarization that occurs when the frequencies coincide may be detected to provide a feedback signal to control one laser relative to the other. 4 figs.

  15. When Feedback Harms and Collaboration Helps in Computer Simulation Environments: An Expertise Reversal Effect

    ERIC Educational Resources Information Center

    Nihalani, Priya K.; Mayrath, Michael; Robinson, Daniel H.

    2011-01-01

    We investigated the effects of feedback and collaboration on undergraduates' transfer performance when using a computer networking training simulation. In Experiment 1, 65 computer science "novices" worked through an instructional protocol individually (control), individually with feedback, or collaboratively with feedback. Unexpectedly,…

  16. The Value and Effectiveness of Feedback in Improving Students' Learning and Professionalizing Teaching in Higher Education

    ERIC Educational Resources Information Center

    Ahea, Md. Mamoon-Al-Bashir; Ahea, Md. Rezaul Kabir; Rahman, Ismat

    2016-01-01

    There is a great importance of feedback in improving learning experience for the students. This has also significant effect in professionalizing teaching in the higher education level. However, feedback is considered as a difficult issue in this arena. Most of the lecturers are still continuing with the tradition form of feedback. This form of…

  17. Feedback Complexity and Practice: Response Pattern Analysis in Retention and Transfer.

    ERIC Educational Resources Information Center

    Phye, Gary D.; Bender, Timothy

    1989-01-01

    Feedback effectiveness and efficiency were studied using 120 college students practicing 40 difficult vocabulary items in 4 experiments. The significant impact of immediate feedback was seen in immediate and delayed posttests. Conditional probability of feedback as a corrective function is discussed via a limited model of general working memory.…

  18. Developmental remodeling of corticocortical feedback circuits in ferret visual cortex.

    PubMed

    Khalil, Reem; Levitt, Jonathan B

    2014-10-01

    Visual cortical areas in the mammalian brain are linked through a system of interareal feedforward and feedback connections, which presumably underlie different visual functions. We characterized the refinement of feedback projections to primary visual cortex (V1) from multiple sources in juvenile ferrets ranging in age from 4-10 weeks postnatal. We studied whether the refinement of different aspects of feedback circuitry from multiple visual cortical areas proceeds at a similar rate in all areas. We injected the neuronal tracer cholera toxin B (CTb) into V1 and mapped the areal and laminar distribution of retrogradely labeled cells in extrastriate cortex. Around the time of eye opening at 4 weeks postnatal, the retinotopic arrangement of feedback appears essentially adult-like; however, suprasylvian cortex supplies the greatest proportion of feedback, whereas area 18 supplies the greatest proportion in the adult. The density of feedback cells and the ratio of supragranular/infragranular feedback contribution declined in this period at a similar rate in all cortical areas. We also found significant feedback to V1 from layer IV of all extrastriate areas. The regularity of cell spacing, the proportion of feedback arising from layer IV, and the tangential extent of feedback in each area all remained essentially unchanged during this period, except for the infragranular feedback source in area 18, which expanded. Thus, while much of the basic pattern of cortical feedback to V1 is present before eye opening, there is major synchronous reorganization after eye opening, suggesting a crucial role for visual experience in this remodeling process.

  19. Feedback on Feedback: Eliciting Learners' Responses to Written Feedback through Student-Generated Screencasts

    ERIC Educational Resources Information Center

    Fernández-Toro, María; Furnborough, Concha

    2014-01-01

    Despite the potential benefits of assignment feedback, learners often fail to use it effectively. This study examines the ways in which adult distance learners engage with written feedback on one of their assignments. Participants were 10 undergraduates studying Spanish at the Open University, UK. Their responses to feedback were elicited by means…

  20. Disturbance-free phase-shifting laser diode interferometer using adaptive feedback control

    SciTech Connect

    Suzuki, Takamasa; Takahashi, Tsutomu; Sasaki, Osami

    2009-10-10

    A feedback-control-equipped phase-shifting laser diode interferometer that eliminates external disturbance is proposed. The feedback loop is stabilized by adaptive control of the polarity of the interference signal. Conventional phase-shifting interferometry can be used with the feedback control, resulting in simplified signal processing and accurate measurement. Several experiments confirm the stability of the feedback control with a measurement repeatability of 1.8 nm.

  1. Landform-water-vegetation feedbacks regulate ecosystem stability and restoration potential in semiarid landscapes

    NASA Astrophysics Data System (ADS)

    Moreno de las Heras, Mariano; Saco, Patricia; Merino Martin, Luis; Espigares, Tiscar; Nicolau, Jose Manuel

    2016-04-01

    Plant production and vegetation dynamics in drylands are shaped by landform patterns, and largely depends on favorable surface redistribution of runoff and sediments. Similarly, the organization of vegetation in these systems controls runoff generation and erosion, and strongly influences the spatial redistribution of water and soil resources. Landform-water-vegetation feedbacks may have, therefore, a key role determining the stability and restoration potential of arid and semiarid ecosystems. We present a synthesis of field, remotely-sensed and modelling studies on landform-soil-vegetation patterns in semiarid rangelands of Australia and reclaimed coal-mining slopes of Mediterranean-dry Spain. Our results indicate that the organization and stability of vegetation patterns strongly depends on feedbacks with coevolving landforms. Exploration of banded woodlands in central Australia reveals that disturbances (e.g. grazing, wildfires) can impact landform-water-vegetation feedbacks, altering the way water is spatially redistributed and used by vegetation, which results in non-linear reductions of ecosystem function. Successful experiences on the restoration of these systems suggest that the spatial management of runoff and sediments is decisive to rehabilitate vegetation patchiness and landscape function. The study of vegetation-water-landform feedbacks in Mediterranean-dry reclaimed mining slopes of Spain offers additional indications on the restoration of drylands, particularly on the effects of rill and gully erosion on the stability of restored vegetation. The development of rill and gully networks provides very efficient drainage networks for the routing of runoff and sediments that drastically reduce the availability of water and soil resources for plant production, ultimately causing degradation of vegetation and restoration failure. This work is supported by a Beatriu de Pinós fellowship co-funded by the European Commission and the Generalitat de Catalunya

  2. An Anatomy of Feedback: A Phenomenographic Investigation of Undergraduate Students' Conceptions of Feedback

    ERIC Educational Resources Information Center

    McLean, Angela J.; Bond, Carol H.; Nicholson, Helen D.

    2015-01-01

    The aim of this research was to investigate how undergraduate students conceptualise feedback, and compare this with research into conceptions of teaching and learning related phenomena in higher education. Using a phenomenographic approach, 28 physiotherapy students in New Zealand were interviewed about their experiences. Data analysis resulted…

  3. Graduate Students' Self-Reported Perspectives regarding Peer Feedback and Feedback from Writing Consultants

    ERIC Educational Resources Information Center

    Chen, Cheryl Wei-yu

    2010-01-01

    This study reported how ten Taiwanese Master's students perceived their experiences of receiving feedback given by their peers and writing consultants to revise a shortened version of their thesis proposals. Collected over the course of one semester, data included students' writing portfolios and interviews with them. Analysis of the data revealed…

  4. Cognitive Apprenticeship in Computer-Mediated Feedback: Creating a Classroom Environment to Increase Feedback and Learning

    ERIC Educational Resources Information Center

    Boling, Erica C.; Beatty, Jeanine

    2010-01-01

    This qualitative case study of 1 teacher and 10 students in an Advanced Placement English class explores the role of computer-mediated feedback in the creation of a classroom learning environment that was supported through hybrid learning experiences. Data sources included classroom observations, online conversations, interviews with 10 high…

  5. Experimental warming reveals positive feedbacks to climate change in the Eurasian Steppe.

    PubMed

    Zhang, Ximei; Johnston, Eric R; Li, Linghao; Konstantinidis, Konstantinos T; Han, Xingguo

    2017-04-01

    Identifying soil microbial feedbacks to increasing temperatures and moisture alterations is critical for predicting how terrestrial ecosystems will respond to climate change. We performed a 5-year field experiment manipulating warming, watering and their combination in a semiarid temperate steppe in northern China. Warming stimulated the abundance of genes responsible for degrading recalcitrant soil organic matter (SOM) and reduced SOM content by 13%. Watering, and warming plus watering also increased the abundance of recalcitrant SOM catabolism pathways, but concurrently promoted plant growth and increased labile SOM content, which somewhat offset SOM loss. The treatments also increased microbial biomass, community complexity and metabolic potential for nitrogen and sulfur assimilation. Both microbial and plant community composition shifted with the treatment conditions, and the sample-to-sample compositional variations of the two communities (pairwise β-diversity distances) were significantly correlated. In particular, microbial community composition was substantially correlated with the dominant plant species (~0.54 Spearman correlation coefficient), much more than with measured soil indices, affirming a tight coupling between both biological communities. Collectively, our study revealed the direction and underlying mechanisms of microbial feedbacks to warming and suggested that semiarid regions of northern steppes could act as a net carbon source under increased temperatures, unless precipitation increases concurrently.

  6. Design, development and installation of 100kW utility and grid connected solar PV power plants for rural applications -- An Indian experience

    SciTech Connect

    Narayanan, M.R.; Gupta, D.V.; Gupta, R.C.; Gupta, R.S.

    1994-12-31

    Two 100 kW Solar Photovoltaic Power Plants have been installed in the State of Uttar Pradesh (UP), India, by Central Electronics Limited (CEL) for the Non-Conventional Energy Development Agency (NEDA) of UP. In the absence of prior experience on such large capacity Solar PV Power Plants, an experimental pilot PV power plant of 25 KW capacity was installed in CEL to gain hands-on experience and the lessons learnt were made use of while installing the two power plants. This paper briefly describes the features of the two power plants, the developmental approach adopted based on Building Block Philosophy with 25 kW System as the basic unit with the attendant advantages. It includes the indigenous design and development effort made for grid connected operation and most importantly the special design features incorporated to ensure a very high degree of safety and protection so necessary in the rural areas with predominantly non-literate users. The paper concludes with some important lessons learnt from both the technical and logistics point of view for guiding installation of similar such plants in the remote rural areas in India and other developing countries in the future.

  7. Orbit stability and feedback control in synchrotron radiation rings

    SciTech Connect

    Yu, L.H.

    1989-01-01

    Stability of the electron orbit is essential for the utilization of a low emittance storage ring as a high brightness radiation source. We discuss the development of the measurement and feedback control of the closed orbit, with emphasis on the activities as the National Synchrotron Light Source of BNL. We discuss the performance of the beam position detectors in use and under development: the PUE rf detector, split ion chamber detector, photo-emission detector, solid state detector, and the graphite detector. Depending on the specific experiments, different beamlines require different tolerances on the orbit motion. Corresponding to these different requirements, we discuss two approaches to closed orbit feedback: the global and local feedback systems. Then we describe a new scheme for the real time global feedback by implementing a feedback system based upon a harmonic analysis of both the orbit movements and the correction magnetic fields. 14 refs., 6 figs., 2 tabs.

  8. Shifts in plant respiration and carbon use efficiency at a large-scale drought experiment in the eastern Amazon.

    PubMed

    Metcalfe, D B; Meir, P; Aragão, L E O C; Lobo-do-Vale, R; Galbraith, D; Fisher, R A; Chaves, M M; Maroco, J P; da Costa, A C L; de Almeida, S S; Braga, A P; Gonçalves, P H L; de Athaydes, J; da Costa, M; Portela, T T B; de Oliveira, A A R; Malhi, Y; Williams, M

    2010-08-01

    *The effects of drought on the Amazon rainforest are potentially large but remain poorly understood. Here, carbon (C) cycling after 5 yr of a large-scale through-fall exclusion (TFE) experiment excluding about 50% of incident rainfall from an eastern Amazon rainforest was compared with a nearby control plot. *Principal C stocks and fluxes were intensively measured in 2005. Additional minor components were either quantified in later site measurements or derived from the available literature. *Total ecosystem respiration (R(eco)) and total plant C expenditure (PCE, the sum of net primary productivity (NPP) and autotrophic respiration (R(auto))), were elevated on the TFE plot relative to the control. The increase in PCE and R(eco) was mainly caused by a rise in R(auto) from foliage and roots. Heterotrophic respiration did not differ substantially between plots. NPP was 2.4 +/- 1.4 t C ha(-1) yr(-1) lower on the TFE than the control. Ecosystem carbon use efficiency, the proportion of PCE invested in NPP, was lower in the TFE plot (0.24 +/- 0.04) than in the control (0.32 +/- 0.04). *Drought caused by the TFE treatment appeared to drive fundamental shifts in ecosystem C cycling with potentially important consequences for long-term forest C storage.

  9. A natural experiment on plant acclimation: lifetime stomatal frequency response of an individual tree to annual atmospheric CO2 increase.

    PubMed

    Wagner, F; Below, R; Klerk, P D; Dilcher, D L; Joosten, H; Kürschner, W M; Visscher, H

    1996-10-15

    Carbon dioxide (CO2) has been increasing in atmospheric concentration since the Industrial Revolution. A decreasing number of stomata on leaves of land plants still provides the only morphological evidence that this man-made increase has already affected the biosphere. The current rate of CO2 responsiveness in individual long-lived species cannot be accurately determined from field studies or by controlled-environment experiments. However, the required long-term data sets can be obtained from continuous records of buried leaves from living trees in wetland ecosystems. Fine-resolution analysis of the lifetime leaf record of an individual birch (Betula pendula) indicates a gradual reduction of stomatal frequency as a phenotypic acclimation to CO2 increase. During the past four decades, CO2 increments of 1 part per million by volume resulted in a stomatal density decline of approximately 0.6%. It may be hypothesized that this plastic stomatal frequency response of deciduous tree species has evolved in conjunction with the overall Cenozoic reduction of atmospheric CO2 concentrations.

  10. Analyzing Feedback Control Systems

    NASA Technical Reports Server (NTRS)

    Bauer, Frank H.; Downing, John P.

    1987-01-01

    Interactive controls analysis (INCA) program developed to provide user-friendly environment for design and analysis of linear control systems, primarily feedback control. Designed for use with both small- and large-order systems. Using interactive-graphics capability, INCA user quickly plots root locus, frequency response, or time response of either continuous-time system or sampled-data system. Configuration and parameters easily changed, allowing user to design compensation networks and perform sensitivity analyses in very convenient manner. Written in Pascal and FORTRAN.

  11. Precipitation-Regulated Feedback

    NASA Astrophysics Data System (ADS)

    Voit, Mark

    2016-07-01

    Star formation in the central galaxies of galaxy clusters appears to be fueled by precipitation of cold clouds out of hot circumgalactic gas via thermal instability. I will present both observational and theoretical support for the precipitation mode in large galaxies and discuss how it can be implemented in cosmological simulations of galaxy evolution. Galaxy cluster cores are unique laboratories for studying the astrophysics of thermal instability and may be teaching us valuable lessons about how feedback works in galaxies spanning the entire mass spectrum.

  12. Managing Residential Electricity Demand Through Provision of Better Feedback

    NASA Astrophysics Data System (ADS)

    Collins, Myles

    -time pricing program. I found that load-shifting can cause GHG emissions to increase or decrease depending on region and season and in no discernable pattern. Therefore, feedback may be more useful and comprehensible to households in the form of total GHG emissions attributable to electricity usage instead of the emission rate of the marginal power plant. Finally, this dissertation explores ways to maximize the effect of feedback by evaluating which appliances may be best suited for appliance-specific feedback. Due to the energy use and behavioral factors associated with each appliance, the most promising appliances were those that heat water for taps, showers, hot tubs, and waterbeds.

  13. The decrease in the population of Gluconacetobacter diazotrophicus in sugarcane after nitrogen fertilization is related to plant physiology in split root experiments.

    PubMed

    Rodríguez-Andrade, Osvaldo; Fuentes-Ramírez, Luis E; Morales-García, Yolanda E; Molina-Romero, Dalia; Bustillos-Cristales, María R; Martínez-Contreras, Rebeca D; Muñoz-Rojas, Jesús

    2015-01-01

    It has been established that a decrease in the population of Gluconacetobacter diazotrophicus associated with sugarcane occurs after nitrogen fertilization. This fact could be due to a direct influence of NH(4)NO(3) on bacterial cells or to changes in plant physiology after fertilizer addition, affecting bacterial establishment. In this work, we observed that survival of G. diazotrophicus was directly influenced when 44.8mM of NH(4)NO(3) (640mgN/plant) was used for in vitro experiments. Furthermore, micropropagated sugarcane plantlets were inoculated with G. diazotrophicus and used for split root experiments, in which both ends of the system were fertilized with a basal level of NH(4)NO(3) (0.35mM; 10mgN/plant). Twenty days post inoculation (dpi) one half of the plants were fertilized with a high dose of NH(4)NO(3) (6.3mM; 180 mgN/plant) on one end of the system. This nitrogen level was lower than that directly affecting G. diazotrophicus cells; however, it caused a decrease in the bacterial population in comparison with control plants fertilized with basal nitrogen levels. The decrease in the population of G. diazotrophicus was higher in pots fertilized with a basal nitrogen level when compared with the corresponding end supplied with high levels of NH4NO3 (100dpi; 80 days post fertilization) of the same plant system. These observations suggest that the high nitrogen level added to the plants induce systemic physiological changes that affect the establishment of G. diazotrophicus.

  14. Development of negative feedback during successive growth cycles of black cherry.

    PubMed Central

    Packer, Alissa; Clay, Keith

    2004-01-01

    Negative feedback between plant and soil microbial communities can be a key determinant of vegetation structure and dynamics. Previous research has shown that negative feedback between black cherry (Prunus serotina) and soil pathogens is strongly distance dependent. Here, we investigate the temporal dynamics of negative feedback. To examine short-term changes, we planted successive cycles of seedlings in the same soil. We found that seedling mortality increased steadily with growth cycle when sterile background soil was inoculated with living field soil but not in controls inoculated with sterilized field soil. To examine long-term changes, we quantified negative feedback across successive growth cycles in soil inoculated with living field soil from a mature forest system (more than 70 years old) versus a younger successional site (ca. 25 years old). In both cases negative feedback developed similarly. Our results suggest that negative feedback can develop very quickly in forest systems, at the spatial scale of a single seedling. PMID:15058444

  15. Delaying feedback by three seconds benefits retention of face-name pairs: the role of active anticipatory processing.

    PubMed

    Carpenter, Shana K; Vul, Edward

    2011-10-01

    In three experiments, we used face-name learning to examine the puzzling feedback delay benefit--the tendency for feedback to be more effective when it is delayed rather than presented immediately. In Experiment 1, we found that feedback presented after a 3-s blank screen was more effective than feedback presented immediately, even after controlling for the exposure time to the material. In Experiment 2, we replicated the benefit of a feedback delay even when participants were given extra time to view the feedback or to try to retrieve the answer, indicating that this benefit is specific to a delay before feedback. Finally, in Experiment 3, we showed that the 3-s delay is beneficial only if it involves a blank screen, not if the delay is filled with an unrelated distracter task. These results suggest that the feedback delay benefit in this paradigm could arise from an active anticipatory process that occurs during the delay.

  16. Torque feedback transmission

    SciTech Connect

    Whalen, B.L.

    1987-01-20

    This patent describes an infinitely variable transmission of inline configuration for interconnecting a primer mover with a load for clutch free operation in a range of speed including hydraulic neutral comprising: a. planetary gear train means having a ring gear, planetary gears supported by a planetary gear carrier, and a sun gear, the sun gear being connected mechanically to the load, output shaft means for joining the sun gear to the load; b. variable torque feedback means comprising (i) a variable displacement hydraulic motor whose rotor shaft is in line with the output shaft means and drivingly connected to the prime mover and the planetary gear carrier during the full range of operation of the transmission, and (ii) a fixed displacement hydraulic pump connected hydraulically to the motor, the rotor shaft of the pump being connected mechanically to the ring gear and being axially displaced from the output shaft means; c. means for adjusting the displacement volume within the hydraulic motor for controlling the torque feedback in the transmission to provide infinitely variable coupling between the prime mover and the load over the full range of the transmission including hydraulic neutral; d. a speed reducer between the primer mover and the motor rotor shaft and a speed multiplier between the sun gear and the load; and e. mechanical transmission assembly means between the speed multiplier and the load in line with the motor rotor shaft and the output shaft means for providing selection of drive, reverse, park, and neutral.

  17. Feedback in clinical medical education.

    PubMed

    Ende, J

    1983-08-12

    In the setting of clinical medical education, feedback refers to information describing students' or house officers' performance in a given activity that is intended to guide their future performance in that same or in a related activity. It is a key step in the acquisition of clinical skills, yet feedback is often omitted or handled improperly in clinical training. This can result in important untoward consequences, some of which may extend beyond the training period. Once the nature of the feedback process is appreciated, however, especially the distinction between feedback and evaluation and the importance of focusing on the trainees' observable behaviors rather than on the trainees themselves, the educational benefit of feedback can be realized. This article presents guidelines for offering feedback that have been set forth in the literature of business administration, psychology, and education, adapted here for use by teachers and students of clinical medicine.

  18. Balance of plant for SOFC experiences with the planning, engineering, construction and testing of a 10 kW planar SOFC pilot plant

    SciTech Connect

    Klov, K.; Sundal, P.; Monsen, T.; Vik, A.

    1996-12-31

    The Statoil Solide Oxide Fuel Cell Research Program was started in January 1991. Some results from this Program were presented to the 1994 Fuel Cell Seminar in San Diego. The final technical milestone for the program was to design, engineer, construct and test a 10 kW pilot plant. From the very beginning, the importance of coordination and integration in the development of components, subsystems and systems, combined with basic research on cell and stack performance, were established as the