Science.gov

Sample records for plants feedback experience

  1. 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

  2. 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. PMID:26209047

  3. [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.

  4. Evaluating plant-soil feedback together with competition in a serpentine grassland.

    PubMed

    Casper, Brenda B; Castelli, Jeffrey P

    2007-05-01

    Plants can alter biotic and abiotic soil characteristics in ways that feedback to change the performance of that same plant species relative to co-occurring plants. Most evidence for this plant-soil feedback comes from greenhouse studies of potted plants, and consequently, little is known about the importance of feedback in relation to other biological processes known to structure plant communities, such as plant-plant competition. In a field experiment with three C4 grasses, negative feedback was expressed through reduced survival and shoot biomass when seedlings were planted within existing clumps of conspecifics compared with clumps of heterospecifics. However, the combined effects of feedback and competition were species-specific. Only Andropogon gerardii exhibited feedback when competition with the clumps was allowed. For Sorghastrum nutans, strong interspecific competition eliminated the feedback expressed in the absence of competition, and Schizachyrium scoparium showed no feedback at all. That arbuscular mycorrhizal (AM) fungi may play a role in the feedback was indicated by higher AM root colonization with conspecific plant neighbours. We suggest that feedback and competition should not be viewed as entirely separate processes and that their importance in structuring plant communities cannot be judged in isolation from each other. PMID:17498138

  5. 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.

  6. [Experience feedback committees (CREX) and beyond…].

    PubMed

    Pourel, N; Meyrieux-Croset, C; Isambert, A

    2015-10-01

    Since the late 2,000 years, under the incentive of the French agencies ANAP (previously MEAH) and HAS and following the decision DC-0103 of the ASN, experience feedback committees (known as 'Comité de retour d'expérience or Crex' in French) have widely been implemented within radiation oncology departments in France. Based on the declaration of error/near misses (precursor events) occurring during medical care to patients, an intuitive method of systematic analysis of these events is basically the aim of such committees (such as the Orion method(©) derived from the air transportation industry). Our article aims at summarizing the paths and pitfalls attached to this methodology, emphasizing what could be the next step, beyond the 'Crex' committees, in the long march to know how to secure care to patients within a radiotherapy medical team. PMID:26344436

  7. 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

  8. Experiences with audio feedback in a veterinary curriculum.

    PubMed

    Rhind, Susan M; Pettigrew, Graham W; Spiller, Jo; Pearson, Geoff T

    2013-01-01

    On a national scale in the United Kingdom, student surveys have served to highlight areas within higher education that are not achieving high student satisfaction. Of particular concern to the veterinary and medical disciplines are the persistently poor levels of student satisfaction with academic feedback compared to students in other subjects. In this study we describe experiences with audio feedback trials in a veterinary curriculum. Students received audio feedback on either an in-course laboratory practical report or on an in-course multiple-choice test. Shortly after receiving their feedback, students were surveyed using an electronic questionnaire. In both courses, more students strongly agreed that audio feedback was helpful compared to either text-based (course A) or whole-class (course B) feedback. When asked to reflect on the helpfulness of various types of feedback they had received, audio feedback was rated less helpful than individual discussion with a member of staff (course A and course B), more helpful than peer discussion or automated feedback (course A and course B), and more helpful than written comments or whole-class review sessions (course B). From a faculty perspective, in course A, use of audio feedback was more efficient than handwritten feedback. In course B, the additional time commitment required was approximately 5 hours. Major themes in the qualitative data included the personal and individual nature of the feedback, quantity of feedback, improvement in students' insight into the process of marking, and the capacity of audio feedback to encourage and motivate. PMID:23470242

  9. Operating nuclear plant feedback to ASME and French codes

    SciTech Connect

    Journet, J.; O`Donnell, W.J.

    1996-12-01

    The French have an advantage in nuclear plant operating experience feedback due to the highly centralized nature of their nuclear industry. There is only one utility in charge of design as well as operations (EDF) and only one reactor vendor (Framatome). The ASME Code has played a key role in resolving technical issues in the design and operation of nuclear plants since the inception of nuclear power. The committee structure of the Code brings an ideal combination of senior technical people with both broad and specialized experience to bear on complex how safe is safe enough technical issues. The authors now see an even greater role for the ASME Code in a proposed new regulatory era for the US nuclear industry. The current legalistic confrontational regulatory era has been quite destructive. There now appears to be a real opportunity to begin a new era of technical consensus as the primary means for resolving safety issues. This change can quickly be brought about by having the industry take operating plant problems and regulatory technical issues directly to the ASME Code for timely resolution. Surprisingly, there is no institution in the US nuclear industry with such a mandate. In fact, the industry is organized to feedback through the Nuclear Regulatory Commission issues which could be far better resolved through the ASME Code. Major regulatory benefits can be achieved by closing this loop and providing systematic interaction with the ASME Code. The essential elements of a new regulatory era and ideas for organizing US institutional industry responsibilities, taken from the French experience, are described in this paper.

  10. 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

  11. 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

  12. Linkages of plant-soil feedbacks and underlying invasion mechanisms.

    PubMed

    Inderjit; Cahill, James F

    2015-01-01

    Soil microbial communities and processes have repeatedly been shown to impact plant community assembly and population growth. Soil-driven effects may be particularly pronounced with the introduction of plants to non-native ranges, as introduced plants are not typically accompanied by transference of local soil communities. Here we describe how the mechanisms by which soil community processes influence plant growth overlap with several known and well-described mechanisms of plant invasion. Critically, a given soil community process may either facilitate or limit invasion, depending upon local conditions and the specific mechanisms of soil processes involved. Additionally, as soil communities typically consist of species with short generation times, the net consequences of plant-soil feedbacks for invasion trajectories are likely to change over time, as ecological and evolutionary adjustments occur. Here we provide an overview of the ecological linkages of plant-soil feedbacks and underlying mechanisms of invasion. PMID:25784668

  13. 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. PMID:25871977

  14. 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

  15. Microbial Population and Community Dynamics on Plant Roots and Their Feedbacks on Plant Communities

    PubMed Central

    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. PMID:22726216

  16. 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.

  17. 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.

  18. Understanding Arts and Humanities Students' Experiences of Assessment and Feedback

    ERIC Educational Resources Information Center

    Adams, Joelle; McNab, Nicole

    2013-01-01

    This article examines how undergraduate students on arts and humanities courses experience assessment and feedback. The research uses a detailed audit, a specially devised questionnaire (the Assessment Experience Questionnaire), and student focus group data, and the article examines results from 19 programmes, comparing those from "arts and…

  19. 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...

  20. 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

  1. 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.

  2. 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

  3. Effects of root decomposition on plant-soil feedback of early- and mid-successional plant species.

    PubMed

    Zhang, Naili; Van der Putten, Wim H; Veen, G F Ciska

    2016-10-01

    Plant-soil feedback (PSF) is an important driver of plant community dynamics. Many studies have emphasized the role of pathogens and symbiotic mutualists in PSFs; however, less is known about the contribution of decomposing litter, especially that of roots. We conducted a PSF experiment, where soils were conditioned by living early- and mid-successional grasses and forbs with and without decomposing roots of conspecific species (conditioning phase). These soils were used to test growth responses of conspecific and heterospecific plant species (feedback phase). The addition of the roots of conspecifics decreased the biomass of both early- and mid-successional plant species in the conditioning phase. In the feedback phase, root addition had positive effects on the biomass of early-successional species and neutral effects on mid-successional species, except when mid-successional grasses were grown in soils conditioned by conspecifics, where effects were negative. Biomass of early- and mid-successional forbs was generally reduced in soils conditioned by conspecifics. We conclude that root decomposition may increase short-term negative PSF effects, but that the effects can become neutral to positive over time, thereby counteracting negative components of PSF. This implies that root decomposition is a key element of PSF and needs to be included in future studies. PMID:27214646

  4. 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. PMID:27466448

  5. Understanding Classroom Feedback Practices: A Study of New Zealand Student Experiences, Perceptions, and Emotional Responses

    ERIC Educational Resources Information Center

    Harris, Lois R.; Brown, Gavin T.; Harnett, Jennifer A.

    2014-01-01

    While feedback is a key factor for improving student learning, little is known about how students understand and experience feedback within the classroom. This study analysed 193 New Zealand primary and secondary students' survey responses alongside drawings of their understandings and experiences of feedback to examine how they experience,…

  6. Plant-soil feedback in East-African savanna trees.

    PubMed

    Rutten, Gemma; Prati, Daniel; Hemp, Andreas; Fischer, Markus

    2016-02-01

    Research in savannas has focused on tree-grass interactions, whereas tree species coexistence received little attention. A leading hypothesis to explain tree coexistence is the Janzen-Connell model, which proposes an accumulation of host-specific enemies, e.g., soil organisms. While it has been shown in several non-savanna case studies that seedlings dispersed away from the mother perform better than seedlings that stay close (home-away effect), few studies tested whether foreign seedling species can replace own seedlings under conspecific adults (replacement effect). Some studies additionally tested for negative effects of conspecific biota (conspecific effect) to demonstrate the accumulation of enemies. We tested these effects by reciprocally growing seedlings of four tree species on soil collected beneath adults of all species, with and without applying a soil sterilization treatment. We found negative home-away effects suggesting that dispersal is advantageous and negative replacement effects suggesting species replacement under adults. While negative conspecific effects indicate accumulated enemies, positive heterospecific effects indicate an accumulation of mutualists rather than enemies for some species. We suggest that plant-soil feedbacks may well contribute to tree coexistence in savannas due to both negative conspecific and positive heterospecific feedbacks. PMID:27145605

  7. 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.

  8. 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…

  9. Positive Feedback between Mycorrhizal Fungi and Plants Influences Plant Invasion Success and Resistance to Invasion

    PubMed Central

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

    2010-01-01

    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. PMID:20808770

  10. 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...

  11. Local beam position feedback experiments on the ESRF storage ring

    SciTech Connect

    Chung, Y.; Kahana, E.; Kirchman, J.

    1995-06-01

    This paper describes the results of local beam position feedback experiments conducted on the ESRF storage ring using digital signal processing (DSP) under the trilateral agreement of collaboration among ESRF, APS, and SPring-8. Two rf beam position monitors (BPMS) in the, upstream and downstream of the insertion device (ID) and two x-ray BPMs in the sixth cell were used to monitor the electron beam and the x-ray beam emitted from the ID, respectively. The local bump coefficients were obtained using the technique of singular value decomposition (SVD) on the global response matrix for the bump magnets and all the available BPMs outside the local bump. The local response matrix was then obtained between the two three-magnet bumps and the position monitors. The data sampling frequency was 4 kHz and a proportional, integral, and derivative (PID) controller was used. The result indicates the closed-loop feedback bandwidth close to 100 Hz and clear attenuation ({approx} {minus}40 dB) of the 7-Hz beam motion due to girder vibration resonance. Comparison of the results using the rf BPMs and x-ray BPMs will be also discussed.

  12. Operational experience feedback in the World Association of Nuclear Operators (WANO).

    PubMed

    Revuelta, Ramon

    2004-07-26

    Operators in high-risk industries need to be learning organisations, learning from themselves and from the others. This presentation will describe how the nuclear industry is dealing in an integrated manner with the feedback of operating experience (OE), both internal and external, to increase the safety and reliability of power plants; it will describe how it; investigates events, reports events and analyses trends, shares information to prevent recurrence, performs corrective action and training, performs assessments to verify effectiveness. The plants have achieved great improvements in performance overall, and to improve further, the industry is evolving. Instead of just learning from past events (reactive) it is now focusing on lower level indications of problems (precursors) through low level events reporting, trending and analysis. A hallmark of the industry is its desire to be self-critical. Emphasis is placed on improving the bottom quartile performing plants. PMID:15231349

  13. Climate Model Tests Of Anthropogenic Influence On Greenhouse-Induced Climate Change: The Role Of Plant Physiology Feedbacks

    NASA Astrophysics Data System (ADS)

    Philippon, G.; Vavrus, S.; Kutzbach, J. E.; Ruddiman, W. F.

    2008-12-01

    We use the NCAR's Community Climate System Model (CCSM3) forced by greenhouse gas concentrations that are lower than nominal pre-industrial (~1750 AD) levels and instead based on natural levels that were reached in similar stages of previous interglaciations. The aim is to test the plant physiology feedback from the vegetation model with the coupled atmosphere-slab ocean configuration at a moderate resolution (T42). According to previous modeling work allowing interactive vegetation but no physiology feedback, the response of this model to lowered greenhouse gases is a global cooling of about 3 K and an expansion of arctic snow area, resulting from an arctic desert expansion and a decrease mainly of boreal trees and also tundra. We focus on the comparison of two experiments with both the vegetation feedbacks (interactive vegetation) but one with no plant physiology feedback (NOANTHRO_VEG) and the other with plant physiology feedback (PHYSIO). The physiology feedback produces an even cooler northern hemisphere high latitude climate, about -0.5 K on average. But the land winter temperature difference can reach 2 K near the northern pole. Furthermore, the physiology feedback amplifies the decrease of boreal tree cover in high latitudes and the tundra area in many places except on the southern limit (South-west and south-east Russia and south-east Canada), where the tundra is increasing. Viewed from the perspective of explaining the unusual late-Holocene increases of CO2 that occurred prior to the Industrial Revolution, these simulated changes in the vegetation support the hypothesis that early agriculture played a role in initiating anomalous warming that thwarted incipient glaciation beginning several thousand years ago. In this work, we will show the impact of the vegetation feedback and the physiology effect on the climate.

  14. Feedbacks of the plant physiology in a coupled climate model under a "hypothical" cooler climate during the Holocene

    NASA Astrophysics Data System (ADS)

    Philippon, G.; Vavrus, S.; Kutzbach, J. E.; Ruddiman, W. F.

    2009-04-01

    We use the NCAR's Community Climate System Model (CCSM3) forced by greenhouse gas concentrations that are lower than nominal pre-industrial (~1750 AD) levels and instead based on natural levels that were reached in similar stages of previous interglaciations. The aim is to test the plant physiology feedback from the vegetation model with the coupled atmosphere-slab ocean configuration at a moderate resolution (T42). According to previous modeling work allowing interactive vegetation but no physiology feedback, the response of this model to lowered greenhouse gases is a global cooling of about 3 K and an expansion of arctic snow area, resulting from an arctic desert expansion and a decrease mainly of boreal trees and also tundra. We focus on the comparison of two experiments with both the vegetation feedbacks (interactive vegetation) but one with no plant physiology feedback (NOANTHRO_VEG) and the other with plant physiology feedback (NOANTHRO_VEG_PHYSIO). The physiology feedback produces an even cooler northern hemisphere high latitude climate, about -0.5 K on average. But the land winter temperature difference can reach 2 K near the northern pole. Furthermore, the physiology feedback amplifies the decrease of boreal tree cover in high latitudes and the tundra area in many places except on the southern limit (South-west and south-east Russia and south-east Canada), where the tundra is increasing. In some tropical forest regions, the physiology effect interacts with the recycling and affects the evaporation, the evapo-transpitation locally. Viewed from the perspective of explaining the unusual late-Holocene increases of CO2 that occurred prior to the Industrial Revolution, these simulated changes in the vegetation support the hypothesis that early agriculture played a role in initiating anomalous warming that thwarted incipient glaciation beginning several thousand years ago. In this work, we will show the impact of the vegetation feedback and the physiology effect

  15. Assessment and Feedback: Institutional Experiences of Student Feedback, 1996 to 2007

    ERIC Educational Resources Information Center

    Williams, James; Kane, David

    2009-01-01

    Attention has recently focused on sectoral concern with assessment and feedback as a result of the National Student Survey. Government, the higher education agencies and the NUS have called for urgent action to address this concern. Existing data from institutional student feedback surveys, using the Student Satisfaction Approach, some dating back…

  16. 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…

  17. Local dominance of exotic plants declines with residence time: a role for plant–soil feedback?

    PubMed Central

    Speek, Tanja A.A.; Schaminée, Joop H.J.; Stam, Jeltje M.; Lotz, Lambertus A.P.; Ozinga, Wim A.; van der Putten, Wim H.

    2015-01-01

    Recent studies have shown that introduced exotic plant species may be released from their native soil-borne pathogens, but that they become exposed to increased soil pathogen activity in the new range when time since introduction increases. Other studies have shown that introduced exotic plant species become less dominant when time since introduction increases, and that plant abundance may be controlled by soil-borne pathogens; however, no study yet has tested whether these soil effects might explain the decline in dominance of exotic plant species following their initial invasiveness. Here we determine plant–soil feedback of 20 plant species that have been introduced into The Netherlands. We tested the hypotheses that (i) exotic plant species with a longer residence time have a more negative soil feedback and (ii) greater local dominance of the introduced exotic plant species correlates with less negative, or more positive, plant–soil feedback. Although the local dominance of exotic plant species decreased with time since introduction, there was no relationship of local dominance with plant–soil feedback. Plant–soil feedback also did not become more negative with increasing time since introduction. We discuss why our results may deviate from some earlier published studies and why plant–soil feedback may not in all cases, or not in all comparisons, explain patterns of local dominance of introduced exotic plant species. PMID:25770013

  18. The soil microbial community predicts the importance of plant traits in plant-soil feedback.

    PubMed

    Ke, Po-Ju; Miki, Takeshi; Ding, Tzung-Su

    2015-04-01

    Reciprocal interaction between plant and soil (plant-soil feedback, PSF) can determine plant community structure. Understanding which traits control interspecific variation of PSF strength is crucial for plant ecology. Studies have highlighted either plant-mediated nutrient cycling (litter-mediated PSF) or plant-microbe interaction (microbial-mediated PSF) as important PSF mechanisms, each attributing PSF variation to different traits. However, this separation neglects the complex indirect interactions between the two mechanisms. We developed a model coupling litter- and microbial-mediated PSFs to identify the relative importance of traits in controlling PSF strength, and its dependency on the composition of root-associated microbes (i.e. pathogens and/or mycorrhizal fungi). Results showed that although plant carbon: nitrogen (C : N) ratio and microbial nutrient acquisition traits were consistently important, the importance of litter decomposability varied. Litter decomposability was not a major PSF determinant when pathogens are present. However, its importance increased with the relative abundance of mycorrhizal fungi as nutrient released from the mycorrhizal-enhanced litter production to the nutrient-depleted soils result in synergistic increase of soil nutrient and mycorrhizal abundance. Data compiled from empirical studies also supported our predictions. We propose that the importance of litter decomposability depends on the composition of root-associated microbes. Our results provide new perspectives in plant invasion and trait-based ecology. PMID:25521190

  19. The Metabolic Plant Feedback Hypothesis: How Plant Secondary Metabolites Nonspecifically Impact Human Health.

    PubMed

    Gertsch, Jürg

    2016-07-01

    Humans can ingest gram amounts of plant secondary metabolites daily through diet. Many of these phytochemicals are bioactive beyond our current understanding because they act through weak negative biological feedback mechanisms, undetectable in vitro. Homeostatic-type assessments shed light on the evolutionary implications of the human diet from plants, giving rise to the metabolic plant feedback hypothesis. The hypothesis states that ancient diets rich in carbohydrates coincide with bulk dietary phytochemicals that act as nonspecific inhibitors of metabolic and inflammatory processes. Consequently, food-derived phytochemicals are likely to be equally effective as herbal medicines for these indications. In addition to the ubiquitous flavonoids, terpenoids, and fatty acids in the diet, the likely impact of chronic chlorophyll ingestion on human health is discussed, and data on its modulation of blood glucose levels are presented. A major deduction of this hypothesis is that starchy diets lacking plant secondary metabolites are associated with multimorbidity (lifestyle diseases) including obesity, type 2 diabetes, and cardiovascular disease. It is proposed that the intake of leafy vegetables, spices, and herbal remedies rich in phytochemicals matches the transition and genetic adaptation to early agriculture, playing a compensatory role in the mismatch of old genes and new diets. PMID:27286339

  20. Negative feedback within a mutualism: host-specific growth of mycorrhizal fungi reduces plant benefit.

    PubMed Central

    Bever, James D

    2002-01-01

    A basic tenet of ecology is that negative feedback on abundance plays an important part in the coexistence of species within guilds. Mutualistic interactions generate positive feedbacks on abundance and therefore are not thought to contribute to the maintenance of diversity. Here, I report evidence of negative feedback on plant growth through changes in the composition of their mutualistic fungal symbionts, arbuscular mycorrhizal (AM) fungi. Negative feedback results from asymmetries in the delivery of benefit between plant and AM fungal species in which the AM fungus that grows best with the plant Plantago lanceolata is a poor growth promoter for Plantago. Growth of Plantago is, instead, best promoted by the AM fungal species that accumulate with a second plant species, Panicum sphaerocarpon. The resulting community dynamic leads to a decline in mutualistic benefit received by Plantago, and can contribute to the coexistence of these two competing plant species. PMID:12573075

  1. 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.

  2. 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. PMID:25981781

  3. 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...

  4. 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.…

  5. 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.

  6. 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.

  7. [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.

  8. 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.

  9. 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…

  10. 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. PMID:26922335

  11. Simulation and design of feedback control on resistive wall modes in Keda Torus eXperiment

    SciTech Connect

    Li, Chenguang; Liu, Wandong; Li, Hong

    2014-12-15

    The feedback control of resistive wall modes (RWMs) in Keda Torus eXperiment (KTX) (Liu et al., Plasma Phys. Controlled Fusion 56, 094009 (2014)) is investigated by simulation. A linear model is built to describe the growth of the unstable modes in the absence of feedback and the resulting mode suppression due to feedback, given the typical reversed field pinch plasma equilibrium. The layout of KTX with two shell structures (the vacuum vessel and the stabilizing shell) is taken into account. The feedback performance is explored both in the scheme of “clean mode control” (Zanca et al., Nucl. Fusion 47, 1425 (2007)) and “raw mode control.” The discrete time control model with specific characteristic times will mimic the real feedback control action and lead to the favored control cycle. Moreover, the conceptual design of feedback control system is also presented, targeting on both RWMs and tearing modes.

  12. A Comparison of Climate Feedback Strength between CO2 Doubling and LGM Experiments

    NASA Astrophysics Data System (ADS)

    Yoshimori, M.; Yokohata, T.; Abe-Ouchi, A.

    2008-12-01

    Studies of past climate potentially provide a constraint on the uncertainty of climate sensitivity, but previous studies warn against a simple scaling to the future. The climate sensitivity is determined by various feedback processes and they may vary with climate states and forcings. In this study, we investigate similarities and differences of feedbacks for a CO2 doubling, a last glacial maximum (LGM), and LGM greenhouse gas (GHG) forcing experiments, using an atmospheric general circulation model coupled to a slab ocean model. After computing the radiative forcing, the individual feedback strengths: water vapor, lapse rate, albedo, and cloud feedbacks, are evaluated explicitly. For this particular model, the difference in the climate sensitivity among experiments is attributed to the shortwave cloud feedback in which there is a tendency that it becomes weaker or even negative in the cooling experiments. No significant difference is found in the water vapor feedback between warming and cooling experiments by GHGs despite the nonlinear dependence of the Clausius-Clapeyron relation on temperature. The weaker water vapor feedback in the LGM experiment due to a relatively weaker tropical forcing is compensated by the stronger lapse rate feedback due to a relatively stronger extratropical forcing. A hypothesis is proposed which explains the asymmetric cloud response between warming and cooling experiments associated with a displacement of the region of mixed- phase clouds. The difference in the total feedback strength between experiments is, however, relatively small compared to the current intermodel spread, and does not necessarily preclude the use of LGM climate as a future constraint.

  13. Senior medical student perceived ability and experience in giving peer feedback in formative long case examinations

    PubMed Central

    2013-01-01

    Background Learning to provide feedback on a peer’s performance in formative clinical assessments can be a valuable way of enriching the students’ own learning experience. Students are often reluctant to provide honest, critical feedback to their peers. Nevertheless, it is an area of practice that is important to develop as students report feeling ill prepared in feedback techniques when entering the medical workforce. We sought to investigate students’ perceptions of their ability to provide feedback to their peers using the positive critique method, and their perceived benefits and challenges during the experience. Methods Over a two year period (2011 to 2012), senior medical students assessed and gave feedback to their peers alongside academic examiners during formative long case clinical examinations. Rating scales, open ended questions and focus group discussions were used to evaluate student perceptions. Results Of the 94 participants, 89/94 (95%) completed the questionnaire, and 39/94 (41%) participated in focus groups. Students found the positive critique method provided a useful framework. Some students raised concerns about the accuracy of their feedback, and felt that further training was required. A substantial number of respondents (42%) did not report feeling confident providing negative feedback to their peers, and qualitative analysis indicated concerns around potential impacts on social relationships. Despite these concerns, the majority (90%) of respondents found the exercise useful, identifying several benefits, including development in the understanding of knowledge content; development of professionalism skills, and increased responsibility. Conclusion Students identified several challenging aspects to providing feedback to their peers. While the experience of giving feedback to peers was perceived by students to provide a valuable learning experience, further training in this area may help to improve the learning experience for students

  14. 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.

  15. 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.

  16. 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…

  17. 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...

  18. Competition increases sensitivity of wheat (Triticum aestivum) to biotic plant-soil feedback.

    PubMed

    Hol, W H Gera; de Boer, Wietse; ten Hooven, Freddy; van der Putten, Wim H

    2013-01-01

    Plant-soil feedback (PSF) and plant competition play an important role in structuring vegetation composition, but their interaction remains unclear. Recent studies suggest that competing plants could dilute pathogenic effects, whereas the standing view is that competition may increase the sensitivity of the focal plant to PSF. In agro-ecosystems each of these two options would yield contrasting outcomes: reduced versus enhanced effects of weeds on crop biomass production. To test the effect of competition on sensitivity to PSF, we grew Triticum aestivum (Common wheat) with and without competition from a weed community composed of Vicia villosa, Chenopodium album and Myosotis arvensis. Plants were grown in sterilized soil, with or without living field inoculum from 4 farms in the UK. In the conditioning phase, field inocula had both positive and negative effects on T. aestivum shoot biomass, depending on farm. In the feedback phase the differences between shoot biomass in T. aestivum monoculture on non-inoculated and inoculated soils had mostly disappeared. However, T. aestivum plants growing in mixtures in the feedback phase were larger on non-inoculated soil than on inoculated soil. Hence, T. aestivum was more sensitive to competition when the field soil biota was present. This was supported by the statistically significant negative correlation between shoot biomass of weeds and T. aestivum, which was absent on sterilized soil. In conclusion, competition in cereal crop-weed systems appears to increase cereal crop sensitivity to soil biota. PMID:23776610

  19. Assessee and assessor experiences of significant events in psychological assessment feedback.

    PubMed

    Ward, Robin M

    2008-07-01

    Although a growing body of scholarly work explores the unique utility and therapeutic uses of psychological assessment, less work has focused specifically on feedback, with few studies that have explored empirically the underlying processes that may describe the role of feedback in a successful assessment. The purpose of this project was to add to the discourse on this topic by engaging in an empirical study exploring assessee and assessor experiences of significant events in psychological assessment feedback. The methodology is qualitative and modeled after significant events research in the study of psychotherapy process. I analyze the accounts of 6 assessment clients and 6 assessment clinicians regarding key events in their experience of feedback. PMID:18584440

  20. 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…

  1. 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

  2. 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.

  3. 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.

  4. Effects of Feedback on Job Attitudes and Work Behavior: A Field Experiment. Technical Report No. 6.

    ERIC Educational Resources Information Center

    Koch, James L.

    A study examined the effects of feedback on the job attitudes and behavior of female sewing machine operators. The control group design involved all 165 piecework operators at the experimental site (a garment factory in a large southwestern city) and a random sample of 54 operators selected from a sister plant of the same manufacturer 10 miles…

  5. Plant reproductive traits mediate tritrophic feedback effects within an obligate brood-site pollination mutualism.

    PubMed

    Krishnan, Anusha; Ghara, Mahua; Kasinathan, Srinivasan; Pramanik, Gautam Kumar; Revadi, Santosh; Borges, Renee M

    2015-11-01

    Plants, herbivores and parasitoids affect each other directly and indirectly; however, feedback effects mediated by host plant traits have rarely been demonstrated in these tritrophic interactions. Brood-site pollination mutualisms (e.g. those involving figs and fig wasps) represent specialised tritrophic communities where the progeny of mutualistic pollinators and of non-mutualistic gallers (both herbivores) together with that of their parasitoids develop within enclosed inflorescences called syconia (hence termed brood-sites or microcosms). Plant reproductive phenology (which affects temporal brood-site availability) and inflorescence size (representing brood-site size) are plant traits that could affect reproductive resources, and hence relationships between trees, pollinators and non-pollinating wasps. Analysing wasp and seed contents of syconia, we examined direct, indirect, trophic and non-trophic relationships within the interaction web of the fig-fig wasp community of Ficus racemosa in the context of brood site size and availability. We demonstrate that in addition to direct resource competition and predator-prey (host-parasitoid) interactions, these communities display exploitative or apparent competition and trait-mediated indirect interactions. Inflorescence size and plant reproductive phenology impacted plant-herbivore and plant-parasitoid associations. These plant traits also influenced herbivore-herbivore and herbivore-parasitoid relationships via indirect effects. Most importantly, we found a reciprocal effect between within-tree reproductive asynchrony and fig wasp progeny abundances per syconium that drives a positive feedback cycle within the system. The impact of a multitrophic feedback cycle within a community built around a mutualistic core highlights the need for a holistic view of plant-herbivore-parasitoid interactions in the community ecology of mutualisms. PMID:26160003

  6. 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…

  7. Nitrogen regulation of the climate-carbon feedback: evidence from a long-term global change experiment.

    PubMed

    Niu, Shuli; Sherry, Rebecca A; Zhou, Xuhui; Wan, Shiqiang; Luo, Yiqi

    2010-11-01

    Modeling studies have shown that nitrogen (N) strongly regulates ecosystem responses and feedback to climate warming. However, it remains unclear what mechanisms underlie N regulation of ecosystem-climate interactions. To examine N regulation of ecosystem feedback to climate change, we have conducted a warming and clipping experiment since November 1999 in a tallgrass prairie of the Great Plains, USA. Infrared heaters were used to elevate soil temperature by an average of 1.96 degrees C at a depth of 2.5 cm from 2000 to 2008. Yearly biomass clipping mimicked hay or biofuel feedstock harvest. We measured carbon (C) and N concentrations, estimated their content and C:N ratio in plant, root, litter, and soil pools. Warming significantly stimulated C storage in aboveground plant, root, and litter pools by 17%, 38%, and 29%, respectively, averaged over the nine years (all P < 0.05) but did not change soil C content or N content in any pool. Plant C:N ratio and nitrogen use efficiency increased in the warmed plots compared to the control plots, resulting primarily from increased dominance of C4 plants in the community. Clipping significantly decreased C and N storage in plant and litter pools (all P < 0.05) but did not have interactive effects with warming on either C or N pools over the nine years. Our results suggest that increased ecosystem nitrogen use efficiency via a shift in species composition toward C4 dominance rather than plant N uptake is a key mechanism underlying warming stimulation of plant biomass growth. PMID:21141187

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

    PubMed

    Smith, Lauren M; Schmitz, Oswald J

    2015-06-01

    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. 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

  10. 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

  11. 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. PMID:24591724

  12. 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.

  13. Persistence of soil organic matter as an ecosystem property: implications for experiments, feedbacks, and modeling

    NASA Astrophysics Data System (ADS)

    Schmidt, M. W.; Torn, M. S.

    2012-12-01

    Globally, soil organic matter (SOM) contains more than three times as much carbon as either the atmosphere or terrestrial vegetation. Yet it remains largely unknown why some SOM persists for millennia whereas other SOM decomposes readily—and this limits our ability to predict how soils will respond to land use or climate change. Recent analytical and experimental advances have demonstrated that molecular structure alone does not control SOM stability: in fact, environmental and biological controls predominate. Here we summarize recent understanding and propose ways to include this understanding in a new generation of experiments and soil carbon models, thereby improving predictions of the SOM response to global warming. Numerical models of soil carbon cycling are used to attribute carbon sources and sinks, predict climate-ecosystem feedbacks, and evaluate biofuel and sequestration strategies. Current ecosystem models rest heavily on the concept of recalcitrance and most models partition plant input into pools of different turnover time solely on the basis of plant tissue chemistry. However, recent research enabled by isotopic, spectroscopic, and molecular marker tools finds little evidence that recalcitrance or selective preservation determine the long residence time of SOM. Without the assumption that recalcitrance or molecular structure control decomposition rates, the framework of these models is no longer justified. Some improvements can be made easily; in other areas, research is needed to translate recent findings into new parameters, for example, to predict the effect of organo-mineral interactions and soil depth on decomposition rates. In this presentation, we will describe a new view of soil carbon cycling that is consistent with the new generation of observations, discuss suggested improvements to soil carbon models, and explore the implications for the vulnerability of soil organic carbon.

  14. 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. low) x…

  15. 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-…

  16. Inhibitory and toxic effects of extracellular self-DNA in litter: a mechanism for negative plant-soil feedbacks?

    PubMed

    Mazzoleni, Stefano; Bonanomi, Giuliano; Incerti, Guido; Chiusano, Maria Luisa; Termolino, Pasquale; Mingo, Antonio; Senatore, Mauro; Giannino, Francesco; Cartenì, Fabrizio; Rietkerk, Max; Lanzotti, Virginia

    2015-02-01

    Plant-soil negative feedback (NF) is recognized as an important factor affecting plant communities. The objectives of this work were to assess the effects of litter phytotoxicity and autotoxicity on root proliferation, and to test the hypothesis that DNA is a driver of litter autotoxicity and plant-soil NF. The inhibitory effect of decomposed litter was studied in different bioassays. Litter biochemical changes were evaluated with nuclear magnetic resonance (NMR) spectroscopy. DNA accumulation in litter and soil was measured and DNA toxicity was assessed in laboratory experiments. Undecomposed litter caused nonspecific inhibition of root growth, while autotoxicity was produced by aged litter. The addition of activated carbon (AC) removed phytotoxicity, but was ineffective against autotoxicity. Phytotoxicity was related to known labile allelopathic compounds. Restricted (13) C NMR signals related to nucleic acids were the only ones negatively correlated with root growth on conspecific substrates. DNA accumulation was observed in both litter decomposition and soil history experiments. Extracted total DNA showed evident species-specific toxicity. Results indicate a general occurrence of litter autotoxicity related to the exposure to fragmented self-DNA. The evidence also suggests the involvement of accumulated extracellular DNA in plant-soil NF. Further studies are needed to further investigate this unexpected function of extracellular DNA at the ecosystem level and related cellular and molecular mechanisms. PMID:25354164

  17. 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.

  18. 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

  19. Effect of vegetation-water table feedbacks on the stability and resilience of plant ecosystems

    NASA Astrophysics Data System (ADS)

    Ridolfi, Luca; D'Odorico, Paolo; Laio, Francesco

    2006-01-01

    The interaction of vegetation with the groundwater is one of the key mechanisms affecting the dynamics of wetland plant ecosystems. The main feature of these interactions is the feedback between the downward shift of the water table caused by riparian vegetation and the emergence of soil aeration conditions favorable to plant establishment, growth, and survival. We develop a conceptual framework to explain how vegetation-water table feedbacks may lead to the emergence of multiple stable states in the dynamics of wetland forests and riparian ecosystems. This framework is used to investigate the sensitivity of these ecosystems to vegetation disturbances and changes in water table depth. As a result of these feedbacks, such ecosystems are prone to catastrophic shifts to an unvegetated state. Because of their competitive advantage, water-tolerant and shallow-rooted species can replace the original vegetation, contributing to the occurrence of vegetation succession in riparian zones and to the existence of alternative vegetation states between areas with shallow and deep water tables.

  20. A data glove with tactile feedback for FMRI of virtual reality experiments.

    PubMed

    Ku, Jeonghun; Mraz, Richard; Baker, Nicole; Zakzanis, Konstantine K; Lee, Jang Han; Kim, In Y; Kim, Sun I; Graham, Simon J

    2003-10-01

    Virtual reality (VR) technology is increasingly recognized as a useful tool for the assessment and rehabilitation of neurologic and psychiatric disorders. The hope that VR can accurately mimic real-life events is also of great interest in basic neuroscience, to identify the brain activity that underlies complex behavior by combining VR with techniques such as functional magnetic resonance imaging (fMRI). Toward these applications, in this study we designed and validated an fMRI-compatible data glove with a built-in vibratory stimulus device for tactile feedback during VR experiments. A simple VR-fMRI experiment was performed at 3.0 Tesla on four young healthy adults involving touching a virtual object with and without tactile feedback. The usefulness of the data glove was subsequently assessed using a series of questionnaires, behavioral performance, and the resulting activation images. Questionnaire scores indicated positive opinions with respect to the data glove, the tactile feedback, and the experimental paradigm. All subjects felt comfortable in the scanner during the VR experiment and were able to perform all aspects of the tasks successfully and with reasonable accuracy. In addition, activation maps showed the anticipated modulations in motor, somatosensory, and parietal cortex. These results support that tactile feedback enhances the realism of virtual hand-object interactions, and that the tactile data glove is suitable for use in other VR-fMRI research applications (e.g., VR physical therapy for stroke recovery). PMID:14583125

  1. The experience of agency in sequence production with altered auditory feedback.

    PubMed

    Couchman, Justin J; Beasley, Robertson; Pfordresher, Peter Q

    2012-03-01

    When speaking or producing music, people rely in part on auditory feedback - the sounds associated with the performed action. Three experiments investigated the degree to which alterations of auditory feedback (AAF) during music performances influence the experience of agency (i.e., the sense that your actions led to auditory events) and the possible link between agency and the disruptive effect of AAF on production. Participants performed short novel melodies from memory on a keyboard. Auditory feedback during performances was manipulated with respect to its pitch contents and/or its synchrony with actions. Participants rated their experience of agency after each trial. In all experiments, AAF reduced judgments of agency across conditions. Performance was most disrupted (measured by error rates and slowing) when AAF led to an ambiguous experience of agency, suggesting that there may be some causal relationship between agency and disruption. However, analyses revealed that these two effects were probably independent. A control experiment verified that performers can make veridical judgments of agency. PMID:22056210

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

    PubMed

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

    2016-06-25

    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

  3. 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

  4. 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…

  5. Soil moisture feedbacks on convection triggers: the role of soil-plant hydrodynamics

    NASA Astrophysics Data System (ADS)

    Siqueira, M.; Katul, G.; Porporato, A.

    2008-12-01

    The linkages between soil moisture dynamics and convection triggers, defined here as the first crossing between the boundary layer height and lifting condensation level, are complicated by a large number of interacting processes occurring over a wide range of space and time scales. To progress on this problem, a soil-plant hydrodynamics model was coupled to a simplified ABL budget to explore the feedback of soil moisture on convection triggers. Using a simplified homogenization technique, the soil-plant hydraulics formulation solves the intrinsically 3-D soil water movement equations by two 1-D coupled Richards' equations. The model is able to account mechanistically for features such as root water uptake, root water redistribution, and mid-day stomatal closure, all known to affect diurnal cycles of surface fluxes and consequently ABL growth. The ABL model considered the convective boundary layer as a slab with a discontinuity at the inversion layer. The coupled model was parameterized using the wealth of data already collected for a maturing Loblolly pine plantation situated in the Southeastern United States. Previous studies, which made use of surface flux measurements to drive an ABL model, have postulate that a negative feedback was possible, which could award the ecosystem with some degree of self-regulation of its water status. According to model simulations, this negative feedback is unlikely. However, drastic changes in external water sources to the ABL are needed for triggering convection when soil moisture is depleted. The apparent negative feedback originated from a decoupling between the water vapor sources needed to produce convection triggers and surface water vapor fluxes.

  6. 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.

  7. Synthesis of feedback systems with large plant ignorance for prescribed time domain tolerances

    NASA Technical Reports Server (NTRS)

    Horowitz, I. M.; Sidi, M.

    1971-01-01

    There is given a minimum-phase plant transfer function, with prescribed bounds on its parameter values. The plant is imbedded in a two-degree-of freedom feedback system, which is to be designed such that the system time response to a deterministic input lies within specified boundaries. Subject to the above, the design should be such as to minimize the effect of sensor noise at the input to the plant. This report presents a design procedure for this purpose, based on frequency response concepts. The time-domain tolerances are translated into equivalent frequency response tolerances. The latter lead to bounds on the loop transmission function in the form of continuous curves on the Nichols chart. The properties of the loop transmission function which satisfy these bounds with minimum effect of sensor noise, are derived.

  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. Topic maps for archiving space plant experiments

    NASA Astrophysics Data System (ADS)

    Brinckmann, Enno; Karoliussen, Irene; Hauan, Tore Martin; Fossum, Knut R.

    The increasing amount of data collected during Space flight experiments, especially on the ISS, requires a new approach for data archiving. The "ULISSE" project, funded by the European Commission, combines the knowledge of the User Support Operation Centers (USOCs) of the ISS and their industrial partners to build up a database for the integration and dissemination of Space experiments. For plant experiments in Space, the N-USOC in Trondheim (Norway) is responsible to collect and implement the needs of scientists working in the field of plant biology for this bio-informatics tool. Each experiment can be found in a topic map providing interfaces to other experiments or other topics. Topic maps describe among others the ex-periment environment in orbit or on ground, experimental methods, hardware and software, biological processes, and experimental results. Each of these topics needs to be identified by an unambiguous definition, usually a link to a database like a thesaurus or an ontology. A survey was done to see in which of the common ontology databases suitable definitions of the topic names of the N-USOC Topic Map could be found. Thus, the draft N-USOC Topic Map could be linked almost completely to Web based definitions. This will allow embedding Space plant biology experiments into public data management systems. Credits: European Commission (FP7/2007-2013, grant agreement n218815).

  10. 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

  11. 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.

  12. Pinch technology experience in plant retrofits

    SciTech Connect

    Kumana, J.D.; Spriggs, H.D.; Ashton, G.

    1987-01-01

    Pinch technology has been applied to retrofit of many plants employing a wide variety of technologies, including continuous and batch processes, and those involving solids processing. This paper reports the authors recent experience in identifying energy savings opportunities in an oil refinery, an ethylene plant, and a corn wet milling plant. The key findings are that: Pinch technology can be successfully applied to retrofits as well as new plant designs; the correct design for retrofits is not the same as that for new designs; pinch technology gives good results even in ''difficult'' processes employing the less common unit operations; and some commonly accepted practices (specifically in solids drying) are fundamentally wrong; multiple-effect drying based on a countercurrent humidity profile offers significant potential for energy savings.

  13. 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.

  14. An Investigation of the Nature of Feedback Given to Pre-Service English Teachers during Their Practice Teaching Experience

    ERIC Educational Resources Information Center

    Akcan, Sumru; Tatar, Sibel

    2010-01-01

    This study seeks to understand how university supervisors and cooperating teachers approach giving feedback during the practice teaching experience to pre-service English language teachers and the nature of feedback they give through post-lesson conferences and written evaluations. The data for the study come from field notes of classroom…

  15. Climate Effects and Feedback Structure Determining Weed Population Dynamics in a Long-Term Experiment

    PubMed Central

    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. PMID:22272362

  16. 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...

  17. Hydrogeochemical zonation in intertidal salt marsh sediments: evidence of positive plant-soil feedback?

    NASA Astrophysics Data System (ADS)

    Moffett, K. B.; Dittmar, J.; Seyfferth, A.; Fendorf, S.; Gorelick, S.

    2012-12-01

    Surface and subsurface environments are linked by the biogeochemical activity in near-surface sediment and by the hydrological fluxes that mobilize its reagents and products. A particularly dynamic and interesting setting to study near-surface hydrogeochemistry is the intertidal zone. Here, the very strong tidal hydraulic forcing is often thought to dominate water and solute transport. However, we demonstrated the importance of two additional subsurface drivers: groundwater flow and plant root water uptake. A high-resolution, coupled surface water-groundwater model of an intertidal salt marsh in San Francisco Bay, CA showed that these three drivers vary over different spatial scales: tidal flooding varies over 10's of meters; groundwater flow varies over meters, particularly within channel banks; and plant root water uptake varies in 3D at the sub-meter scale. Expanding on this third driver, we investigated whether the spatial variations in soil-water-plant hydraulic interactions that occur due to vegetation zonation also cause distinct geochemical zonation in salt marsh sediment pore waters. The existence of such geochemical zonation was verified and mapped by detailed field observations of the chemical composition of sediments, pore waters, surface waters, and vegetation. The field data and the coupled hydrologic model were then further analyzed to evaluate potential causal mechanisms for the geochemical zonation, including testing the hypothesis that the vegetation affects pore water geochemistry via a positive feedback beneficial to itself. If further supported by future studies, this geochemical feedback may complement known physical ecosystem engineering mechanisms to help stabilize and organize intertidal wetlands.

  18. 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.

  19. 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.

  20. 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.

  1. 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

  2. Optimal feedback control successfully explains changes in neural modulations during experiments with brain-machine interfaces

    PubMed Central

    Benyamini, Miri; Zacksenhouse, Miriam

    2015-01-01

    Recent experiments with brain-machine-interfaces (BMIs) indicate that the extent of neural modulations increased abruptly upon starting to operate the interface, and especially after the monkey stopped moving its hand. In contrast, neural modulations that are correlated with the kinematics of the movement remained relatively unchanged. Here we demonstrate that similar changes are produced by simulated neurons that encode the relevant signals generated by an optimal feedback controller during simulated BMI experiments. The optimal feedback controller relies on state estimation that integrates both visual and proprioceptive feedback with prior estimations from an internal model. The processing required for optimal state estimation and control were conducted in the state-space, and neural recording was simulated by modeling two populations of neurons that encode either only the estimated state or also the control signal. Spike counts were generated as realizations of doubly stochastic Poisson processes with linear tuning curves. The model successfully reconstructs the main features of the kinematics and neural activity during regular reaching movements. Most importantly, the activity of the simulated neurons successfully reproduces the observed changes in neural modulations upon switching to brain control. Further theoretical analysis and simulations indicate that increasing the process noise during normal reaching movement results in similar changes in neural modulations. Thus, we conclude that the observed changes in neural modulations during BMI experiments can be attributed to increasing process noise associated with the imperfect BMI filter, and, more directly, to the resulting increase in the variance of the encoded signals associated with state estimation and the required control signal. PMID:26042002

  3. 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.

  4. 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.

  5. 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.

  6. Synthesis of a non-linear feedback system with significant plant-ignorance for prescribed time-domain tolerances

    NASA Technical Reports Server (NTRS)

    Krishnan, K. R.; Horowitz, I. M.

    1973-01-01

    The problem considered is the design of a feedback system containing a linear, time invariant, minimum phase plant, whose parameters are known only within given bounds, such that the time response of the system remains within specified limits. A quasi-optimal design, for given design constraints, is one which minimizes the effect of white sensor noise on the input to the plant. An investigation was conducted on the use of the non linear device known as the Clegg integrator in the design of such a system. The describing function of the Clegg integrator has the same magnitude characteristic, apart from a scale factor, as the linear integrator, but has 52 deg less phase-lag, at all frequencies, than the linear integrator; thus, when used in a feedback system, it provides a larger stability margin than the linear integrator. This property allows the nonlinear feedback system to be designed so that the sensor noise is attenuated more than in the linear design.

  7. 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

  8. 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

  9. Reciprocal Markov Modeling of Feedback Mechanisms Between Emotion and Dietary Choice Using Experience-Sampling Data.

    PubMed

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

    2015-01-01

    With intensively collected longitudinal data, recent advances in the 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 the 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 6 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 with the empirical study further demonstrated that the procedure is promising in terms of recovering the parameters. PMID:26717120

  10. Feedback from plant species change amplifies CO2 enhancement of grassland productivity

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Dynamic global vegetation models simulate feedbacks of vegetation change on ecosystem processes, but direct, experimental evidence for feedbacks that result from atmospheric CO2 enrichment is rare. We hypothesized that feedbacks from species change would amplify the initial CO2 stimulation of above...

  11. [Quality assurance in heart surgery: 8 years experience with a "feedback-control" system in Heidelberg].

    PubMed

    Vahl, C F; Meinzer, P; Thomas, G; Osswald, B R; Hagl, S

    1996-12-01

    An important aspect of quality assurance in cardiac surgery covers the epidemiological analysis of patient data. After an 8 year period of clinical experience with quality assurance, we summarize and evaluate current concepts and actual experiences regarding a special type of database application and organisation ("feedback-control-system") for quality assurance. It had been developed to meet and solve the problems related to the data acquisition process, that are typically present in the clinical routine of quality assurance. In 1988 the "feedback-control-system" was designed and implemented in the Department of Cardiac Surgery at Heidelberg University. Since then it had been continuously improved and adapted to satisfy current needs in cardiac surgery. More than 1500 items are now recorded routinely per patient. At present, detailed information of more than 10,000 patients is available for the specific methods of analysis in the field of quality assurance. The basic concept included 1. the integration of the data acquisition in the daily clinical routine, 2. the evaluation and improvement of collected data material by means of "output-functions", that require previously recorded reliable data (that is automatically computer generated operation reports, letters, statistics, accounting etc.), and 3. to ensure that the medical and non-medical staff members participate in the advantages and the responsibilities of the data-base system for quality assurance. Analyses of perioperative risks and results, early discovery of trends, identification of special subpopulations receiving special types of treatment in cardiac surgery etc. have now become a regularly performed tool in clinical routine. This includes the availability of "problem profiles", "trend analysis", the use of simple concluding statistics as well as the calculation of multivariable models. This internal quality assurance is completed by "multicentric" comparisons with further hospitals already using the

  12. 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.

  13. A hydroponic system for microgravity plant experiments.

    PubMed

    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. PMID:11539001

  14. 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. PMID:23728137

  15. Experts by experience; the views of service user educators providing feedback on medical students' work based assessments.

    PubMed

    Muir, Delia; Laxton, Julie Clare

    2012-02-01

    Assessment tools were designed to provide health and social care students with multi-sourced, interprofessional feedback in practice. This includes feedback from service users. Third year medical students at the University of Leeds were given accesses to 4 assessment tools whilst in practice. Completed assessments were then sent to the university where service users and carers worked with university tutors to give further feedback and comment on the overall development of students. Three service users then took part in a focus group and one provided written feedback. Four key themes were identified from the focus group: • Preparation and support • The design of the tools • The process of using the tools in practice • Feedback. We found that the project provided both challenges and rewards for all involved. The service user educators involved were able to bring a different and valuable perspective to formative feedback. The combination of their personal and professional experiences, along with the preparation they had received, helped bridge the gap between service users in practice and university based tutors. The findings from this study went on to inform a review of the assessment tools and revised versions are now being used. PMID:21955778

  16. Programmable DSP-Based Multi-Bunch Feedback - Operating Experience from Six Installations

    SciTech Connect

    Fox, John D

    2000-05-15

    A longitudinal instability control system, originally developed for the PEP-II, DAPHNE and ALS machines has in the last two years been commissioned for use at the PLS and BESSY-II light sources. All of the installations are running identical hardware and use a common software distribution package. This common structure is beneficial in sharing expertise among the labs, and allows rapid commissioning of each new installation based on well-understood diagnostic and operational techniques. While the installations share the common instability control system, there are significant differences in machine dynamics between the various colliders and light sources. These differences require careful specification of the feedback algorithm and system configuration at each installation to achieve good instability control and useful operational margins. This paper highlights some of the operational experience at each installation, using measurements from each facility to illustrate the challenges unique to each machine. The authors experience on the opportunities and headaches of sharing development and operational expertise among labs on three continents is also offered.

  17. 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.

  18. 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.

  19. 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…

  20. 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…

  1. 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)…

  2. 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

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

    PubMed Central

    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. PMID:24324863

  4. '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. PMID:25735877

  5. Optical-feedback cavity-enhanced absorption spectroscopy in a linear cavity: model and experiments

    NASA Astrophysics Data System (ADS)

    Manfred, Katherine M.; Ciaffoni, Luca; Ritchie, Grant A. D.

    2015-08-01

    Optical-feedback cavity-enhanced absorption spectroscopy is a highly sensitive trace gas sensing technique that relies on feedback from a resonant intracavity field to successively lock the laser to the cavity as the wavelength is scanned across a molecular absorption with a comb of resonant frequencies. V-shaped optical cavities have been favoured in the past in order to avoid additional feedback fields from non-resonant reflections that potentially suppress the locking to the resonant cavity frequency. A model of the laser-cavity coupling demonstrates, however, that the laser can stably lock to a resonant linear cavity, within certain constraints on the relative intensity of the two feedback sources. By mode mismatching the field into the linear cavity, we have shown that it is theoretically and practically possible to spatially filter out the unwanted non-resonant component in order for the resonant field to dominate the feedback competition at the laser. A 5.3 cw quantum cascade laser scanning across a absorption feature demonstrated stable locking to achieve a minimum detectable absorption coefficient of for 1-s averaging. Detailed investigations of feedback effects on the laser output verified the validity of our theoretical models.

  6. Shortwave feedbacks and El Nino-Southern Oscillation: Forced ocean coupled ocean-atmosphere experiments

    NASA Technical Reports Server (NTRS)

    Waliser, Duane E.; Blanke, Bruno; Neelin, J. David; Gautier, C.

    1994-01-01

    Changes in tropical sea surface temperature (SST) can produce changes in cloudiness that modify incoming solar shortwave (SW) radiation, which in turn affects SST. The effects of this negative feedback on Pacific interannual variability are examined in forced ocean model and hybrid coupled ocean-atmosphere model simulations. Two empirical schemes are used to model the large-scale, low-frequency response of surface SW to SST anomalies. The first scheme attempts to account for the nonlocal nature of the atmospheric response to SST based patterns of covariability analyzed through singular value decomposition. In the observations the primary coupled mode of variability is composed of a SW anomaly in the central Pacific that covaries with anomalous SST in the eastern Pacific. This is applied in the model as a nonlocal feedback. The second scheme examines the effects of a purely local feedback with a spatially varying coefficient of magnitude chosen similar to the first scheme. In almost all cases the second scheme behaved similarly to the first, presumably because the correlation scale of SST is large enough for El Nino-Southern Oscillation (ENSO) dynamics that there is little sensitivity to the local approximation in the SW feedback. In simulations forced by time series of observed wind stress the SW feedback induced very minor SST damping. Results for a simpified heat budget analysis showed that while the SW feedback increased the local heat flux damping on SST, it also induced a mean shallowing of the mixed layer. The resulting changes in both the local mean vertical temperature gradient and the zonal velocity response to the wind stress acted to oppose the local heat flux damping effects. When the observed SW anomalies were applied to forced simulations, the simulated SST anomalies were modified as expected, and agreement with observed SST improved. In coupled simulations the SW feedbacks had greater impact than in the case of specified stress. The main effects were

  7. Experiments on plants grown in space. Status and prospects

    NASA Technical Reports Server (NTRS)

    Halstead, T. W.; Dutcher, F. R.

    1984-01-01

    Space flight provides a unique capability to gravitational research by providing an environment in which gravity can be manipulated below the Earth norm of 1 to a state comparable to weightlessness. Although space experiments with seeds and plants have been conducted for almost 25 years, we are only now entering an era that promises the capability of routinely conducting controlled plant experiments in space. Results from experiments with higher plants and seeds flown thus far in both manned and unmanned spacecraft from both the USA and USSR are briefly summarized. An overview of the current status of space biology experimentation as it relates to plants is presented and present and future opportunities to conduct plant experiments under space flight conditions are discussed.

  8. Atmosphere control for plant growth flight experiments

    NASA Technical Reports Server (NTRS)

    Powell, Ferolyn T.; Sudar, Martin; Timm, Marc; Yost, Bruce

    1989-01-01

    An atmosphere exchange system (AES) has been designed to provide a conditioned atmosphere supply to plant specimens in flight without incurring the large weight and volume associated with bottled gases. The paper examines the atmosphere filter cartridge (AFC) designed to remove trace organic atmosphere contaminants from the Space Shuttle cabin and to condition the cabin atmosphere prior to exposure to plant specimens. The AES and AFC are described and illustrated. The AFC design requirements are discussed and results are presented from tests on the performance of the AFC. Also, consideration is given to the potential applications of the AFC and future design concepts for atmosphere control.

  9. 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)

  10. 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…

  11. 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…

  12. 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.

  13. 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…

  14. Student Voice: Using Qualitative Feedback from Students to Enhance Their University Experience

    ERIC Educational Resources Information Center

    Grebennikov, Leonid; Shah, Mahsood

    2013-01-01

    Many performance indicators in Australian higher education are based on the quantitative data from student feedback surveys, while the qualitative data usually generated by these surveys receive relatively limited attention. This paper argues that these data, if collected and analysed in a systematic way, can be used as an effective and robust…

  15. Feedback on Individual Academic Presentations: Exploring Finnish University Students' Experiences and Preferences

    ERIC Educational Resources Information Center

    Károly, Adrienn

    2015-01-01

    With an increasing emphasis on measuring the outcomes of learning in higher education, assessment is gaining an ever more prominent role in curriculum design and development as well as in instructional practices. In formative assessment, feedback is regarded as a powerful pedagogical tool driving student engagement and deep learning. The efficacy…

  16. "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…

  17. Both Movement-End and Task-End Are Critical for Error Feedback in Visuomotor Adaptation: A Behavioral Experiment

    PubMed Central

    Ishikawa, Takumi; Sakaguchi, Yutaka

    2013-01-01

    An important issue in motor learning/adaptation research is how the brain accepts the error information necessary for maintaining and improving task performance in a changing environment. The present study focuses on the effect of timing of error feedback. Previous research has demonstrated that adaptation to displacement of the visual field by prisms in a manual reaching task is significantly slowed by delayed visual feedback of the endpoint, suggesting that error feedback is most effective when given at the end of a movement. To further elucidate the brain mechanism by which error information is accepted in visuomotor adaptation, we tested whether error acceptance is linked to the end of a given task or to the end of an executed movement. We conducted a behavioral experiment using a virtual shooting task in which subjects controlled their wrist movements to meet a target with a cursor as accurately as possible. We manipulated the timing of visual feedback of the impact position so that it occurred either ahead of or behind the true time of impact. In another condition, the impact timing was explicitly indicated by an additional cue. The magnitude of the aftereffect significantly varied depending on the timing of feedback (p < 0.05, Friedman's Test). Interestingly, two distinct peaks of aftereffect were observed around movement-end and around task-end, irrespective of the existence of the timing cue. However, the peak around task-end was sharper when the timing cue was given. Our results demonstrate that the brain efficiently accepts error information at both movement-end and task-end, suggesting that two different learning mechanisms may underlie visuomotor transformation. PMID:23393602

  18. Impact of Web Searching and Social Feedback on Consumer Decision Making: A Prospective Online Experiment

    PubMed Central

    Lau, Annie YS

    2008-01-01

    Background The World Wide Web has increasingly become an important source of information in health care consumer decision making. However, little is known about whether searching online resources actually improves consumers’ understanding of health issues. Objectives The aim was to study whether searching on the World Wide Web improves consumers’ accuracy in answering health questions and whether consumers’ understanding of health issues is subject to further change under social feedback. Methods This was a pre/post prospective online study. A convenience sample of 227 undergraduate students was recruited from the population of the University of New South Wales. Subjects used a search engine that retrieved online documents from PubMed, MedlinePlus, and HealthInsite and answered a set of six questions (before and after use of the search engine) designed for health care consumers. They were then presented with feedback consisting of a summary of the post-search answers provided by previous subjects for the same questions and were asked to answer the questions again. Results There was an improvement in the percentage of correct answers after searching (pre-search 61.2% vs post-search 82.0%, P <.001) and after feedback with other subjects’ answers (pre-feedback 82.0% vs post-feedback 85.3%, P =.051).The proportion of subjects with highly confident correct answers (ie, confident or very confident) and the proportion with highly confident incorrect answers significantly increased after searching (correct pre-search 61.6% vs correct post-search 95.5%, P <.001; incorrect pre-search 55.3% vs incorrect post-search 82.0%, P <.001). Subjects who were not as confident in their post-search answers were 28.5% more likely than those who were confident or very confident to change their answer after feedback with other subjects’ post-search answers (χ 2 1= 66.65, P <.001). Conclusions Searching across quality health information sources on the Web can improve consumers

  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. 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...

  2. 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.

  3. The inducible CAM plants in putative lunar lander experiments

    NASA Astrophysics Data System (ADS)

    Burlak, Olexii; Zaetz, Iryna; Soldatkin, Olexii; Rogutskyy, Ivan; Danilchenko, Boris; Mikheev, Olexander; de Vera, Jean-Pierre; Vidmachenko, Anatolii; Foing, Bernard H.; Kozyrovska, Natalia

    Precursory lunar lander experiments on growing plants in locker-based chambers will increase our understanding of effect of lunar conditions on plant physiology. The inducible CAM (Cras-sulacean Acid Metabolism)-plants are reasonable model for a study of relationships between environmental challenges and changes in plant/bacteria gene expression. In inducible CAM-plants the enzymatic machinery for the environmentally activated CAM switches on from a C3-to a full-CAM mode of photosynthesis in response to any stresses (Winter et al., 2008). In our study, Kalanchoe spp. are shown to be promising candidates for putative lunar experiments as resistant to irradiation and desiccation, especially after inoculation with a bacterial consortium (Boorlak et al., 2010). Within frames of the experiment we expect to get information about the functional activity of CAM-plants, in particular, its organogenesis, photosystem, the circadian regulation of plant metabolism on the base of data gaining with instrumental indications from expression of the reporter genes fused to any genes involved in vital functions of the plant (Kozyrovska et al., 2009). References 1. Winter K., Garcia M., Holtum J. (2008) J. Exp. Bot. 59(7):1829-1840 2. Bourlak O., Lar O., Rogutskyy I., Mikheev A., Zaets I., Chervatyuk N., de Vera J.-P., Danilchenko A.B. Foing B.H., zyrovska N. (2010) Space Sci. Technol. 3. Kozyrovska N.O., Vidmachenko A.P., Foing B.H. et al. Exploration/call/estec/ESA. 2009.

  4. Surgeon’s experiences of receiving peer benchmarked feedback using patient-reported outcome measures: a qualitative study

    PubMed Central

    2014-01-01

    Background The use of patient-reported outcome measures (PROMs) to provide healthcare professionals with peer benchmarked feedback is growing. However, there is little evidence on the opinions of professionals on the value of this information in practice. The purpose of this research is to explore surgeon’s experiences of receiving peer benchmarked PROMs feedback and to examine whether this information led to changes in their practice. Methods This qualitative research employed a Framework approach. Semi-structured interviews were undertaken with surgeons who received peer benchmarked PROMs feedback. The participants included eleven consultant orthopaedic surgeons in the Republic of Ireland. Results Five themes were identified: conceptual, methodological, practical, attitudinal, and impact. A typology was developed based on the attitudinal and impact themes from which three distinct groups emerged. ‘Advocates’ had positive attitudes towards PROMs and confirmed that the information promoted a self-reflective process. ‘Converts’ were uncertain about the value of PROMs, which reduced their inclination to use the data. ‘Sceptics’ had negative attitudes towards PROMs and claimed that the information had no impact on their behaviour. The conceptual, methodological and practical factors were linked to the typology. Conclusion Surgeons had mixed opinions on the value of peer benchmarked PROMs data. Many appreciated the feedback as it reassured them that their practice was similar to their peers. However, PROMs information alone was considered insufficient to help identify opportunities for quality improvements. The reasons for the observed reluctance of participants to embrace PROMs can be categorised into conceptual, methodological, and practical factors. Policy makers and researchers need to increase professionals’ awareness of the numerous purposes and benefits of using PROMs, challenge the current methods to measure performance using PROMs, and reduce

  5. Operating experience, economics and wind plant optimization

    SciTech Connect

    Poulsen, E.V.

    1995-09-01

    The Vestas group has installed more than 4,500 wind turbines (640 MW) world-wide. Experience from this development contradicts several myths about the costs of producing wind energy. The paper will document that it Vestas wind projects: (1) wind turbine availability does not decrease with age; (2) service and maintenance costs do not increase with age; (3) that initial investment costs have decreased dramatically over the last ten years. The relative importance of different project costs are discussed, and sensitivity analysis is performed to illustrate that O and M costs, wind turbine availability, and financing parameters significantly influence the cost of energy production. New Vestas turbine models are introduced, including V42-600 kW and V60-1500 kW turbines.

  6. 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.

  7. 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.

  8. 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…

  9. Chromaticity Feedback at RHIC

    SciTech Connect

    Marusic, A.; Minty, M.; Tepikian, S.

    2010-05-23

    Chromaticity feedback during the ramp to high beam energies has been demonstrated in the Relativistic Heavy Ion Collider (RHIC). In this report we review the feedback design and measurement technique. Commissioning experiences including interaction with existing tune and coupling feedback are presented together with supporting experimental data.

  10. 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.

  11. Loop Analysis of Causal Feedback in Epidemiology: An Illustration Relating To Urban Neighborhoods and Resident Depressive Experiences

    PubMed Central

    2008-01-01

    The causal feedback implied by urban neighborhood conditions that shape human health experiences, that in turn shape neighborhood conditions through a complex causal web, raises a challenge for traditional epidemiological causal analyses. This article introduces the loop analysis method, and builds off of a core loop model linking neighborhood property vacancy rate, resident depressive symptoms, rate of neighborhood death, and rate of neighborhood exit in a feedback network. I justify and apply loop analysis to the specific example of depressive symptoms and abandoned urban residential property to show how inquiries into the behavior of causal systems can answer different kinds of hypotheses, and thereby compliment those of causal modeling using statistical models. Neighborhood physical conditions that are only indirectly influenced by depressive symptoms may nevertheless manifest in the mental health experiences of their residents; conversely, neighborhood physical conditions may be a significant mental health risk for the population of neighborhood residents. I find that participatory greenspace programs are likely to produce adaptive responses in depressive symptoms and different neighborhood conditions, which are different in character to non-participatory greenspace interventions. PMID:17706851

  12. 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.

  13. 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.

  14. Combined cycle electric power plant with coordinated plural feedback turbine control

    SciTech Connect

    Kiscaden, R.W.; Martz, L.F.; Uram, R.

    1980-01-22

    A combined cycle electric power plant includes gas and steam turbines and a steam generator for recovering the heat in the exhaust gases exited from the gas turbine and for using the recovered heat to produce and supply steam to the steam turbine. The steam generator includes a superheater tube through which a fluid, E.G. Water, is directed to be additionally heated into superheated steam by the exhaust gas turbine gases. An afterburner further heats the exhaust gas turbine gases passed to the superheater tube. The temperature of the gas turbine exhaust gases is sensed for varying the fuel flow to the afterburner by a fuel valve, whereby the temperatures of the gas turbine exhaust gases and therefore of the superheated steam, are controlled. A plant load demand error signal is utilized for correcting a coordinated gas turbine load reference and for trimming a feedforward afterburner control signal derived from the sensed gas turbine exhaust temperatures.

  15. 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).

  16. Representing plants as rigid cylinders in experiments and models

    NASA Astrophysics Data System (ADS)

    Vargas-Luna, Andrés; Crosato, Alessandra; Calvani, Giulio; Uijttewaal, Wim S. J.

    2016-07-01

    Simulating the morphological adaptation of water systems often requires including the effects of plants on water and sediment dynamics. Physical and numerical models need representing vegetation in a schematic easily-quantifiable way despite the variety of sizes, shapes and flexibility of real plants. Common approaches represent plants as rigid cylinders, but the ability of these schematizations to reproduce the effects of vegetation on morphodynamic processes has never been analyzed systematically. This work focuses on the consequences of representing plants as rigid cylinders in laboratory tests and numerical simulations. New experiments show that the flow resistance decreases for increasing element Reynolds numbers for both plants and rigid cylinders. Cylinders on river banks can qualitatively reproduce vegetation effects on channel width and bank-related processes. A comparative review of numerical simulations shows that Baptist's method that sums the contribution of bed shear stress and vegetation drag, underestimates bed erosion within sparse vegetation in real rivers and overestimates the mean flow velocity in laboratory experiments. This is due to assuming uniform flow among plants and to an overestimation of the role of the submergence ratio.

  17. ENTEROVIRUSES IN SLUDGE: MULTIYEAR EXPERIENCE WITH FOUR WASTEWATER TREATMENT PLANTS

    EPA Science Inventory

    The authors describe their experience with the isolation of viruses from four treatment plants located in different geographic areas. Over a period of 3 years, 297 enteroviruses were isolated from 307 sludge samples. The highest frequency of viral isolation (92%), including multi...

  18. Operating experience feedback report: Assessment of spent fuel cooling. Volume 12

    SciTech Connect

    Ibarra, J.G.; Jones, W.R.; Lanik, G.F.; Ornstein, H.L.; Pullani, S.V.

    1997-02-01

    This report documents the results of an independent assessment by a team from the Office of Analysis and Evaluation of Operational Data of spent-fuel-pool (SFP) cooling in operating nuclear power plants. The team assessed the likelihood and consequences of an extended loss of SFP cooling and suggested corrective actions, based on their findings.

  19. 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

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

    Technology Transfer Automated Retrieval System (TEKTRAN)

    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-dependence effects and whether variation in these e...

  1. 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

  2. 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.

  3. 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. PMID:26609958

  4. 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.

  5. Experience with organic Rankine cycles in heat recovery power plants

    SciTech Connect

    Bronicki, L.Y.; Elovic, A.; Rettger, P.

    1996-11-01

    Over the last 30 years, organic Rankine cycles (ORC) have been increasingly employed to produce power from various heat sources when other alternatives were either technically not feasible or economical. These power plants have logged a total of over 100 million turbine hours of experience demonstrating the maturity and field proven technology of the ORC cycle. The cycle is well adapted to low to moderate temperature heat sources such as waste heat from industrial plants and is widely used to recover energy from geothermal resources. The above cycle technology is well established and applicable to heat recovery of medium size gas turbines and offers significant advantages over conventional steam bottoming cycles.

  6. Plant-soil feedbacks and the partial recovery of soil spatial patterns on abandoned well pads in a sagebrush shrubland.

    PubMed

    Minnick, Tamera J; Alward, Richard D

    2015-01-01

    Shrub-dominated arid and semiarid ecosystems are characterized by spatail patterns in vegetation and bare ground (e.g., resource islands). Modern oil and gas well pad construction entails complete removal of vegetation and upper soil layers, followed by replacement of soils and attempts at revegetation; historically, many pads were merely abandoned. Feedbacks between soil and vegetation are required for the recovery of ecosystem functions in these catastrophically disturbed systems. We measured soil organic carbon (SOC), employing a spatially explicit sampling protocol, on two sites in undisturbed big sagebrush communities and a chronosequence of eight recovering well pads. Sites in undisturbed communities exhibited significant spatial autocorrelation of SOC at the plot level that was absent from all of the well pad sites. Incorporating shrub presence as a covariate revealed three additional cases of SOC spatial autocorrelation on well pads. These results, along with SOC patterns between and- under plants, suggest resource island development. These findings support the hypothesis that species identity as well as functional group need to be taken into account in restoration. Restoration of ecosystem functions, including those associated with resistance and resilience to disturbance, may be enhanced when characteristic soil heterogeneity and vegetation spatial patterns recover. PMID:26255353

  7. 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…

  8. 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.

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

    PubMed

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

    2015-03-01

    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. PMID:25833433

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

    NASA Astrophysics Data System (ADS)

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

    2015-03-01

    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.

  11. 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…

  12. 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.

  13. 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.

  14. 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.

  15. 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.

  16. 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.

  17. 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.

  18. 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

  19. 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.…

  20. 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.

  1. Enteroviruses in sludge: multiyear experience with four wastewater treatment plants.

    PubMed Central

    Hamparian, V V; Ottolenghi, A C; Hughes, J H

    1985-01-01

    We describe our experience with the isolation of viruses from four treatment plants located in different geographic areas. Over a period of 3 years, 297 enteroviruses were isolated from 307 sludge samples. The highest frequency of viral isolation (92%), including multiple isolates from single samples, was obtained from a treatment plant serving the smallest population. Excluding the polioviruses, 22 different enterovirus serotypes were isolated. The methods used to isolate the viruses were relatively simple and included an elution procedure in which beef extract was used and a disinfection step. No concentration procedure was used. Of three cell culture systems used, the RD line of human rhabdomyosarcoma cells was by far the most useful for the isolation of echoviruses; BGM and HeLa cells were particularly useful for the isolation of group B coxsackieviruses. A seasonal effect on viral isolation rates from sludge was observed. PMID:2996422

  2. 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.

  3. 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.

  4. 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.

  5. 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. PMID:11537516

  6. 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.

  7. 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.

  8. Applying the results of probablistic safety analysis of nuclear power plants: a survey of experience

    SciTech Connect

    Andrews, W.B.; Herttrich, M.; Koeberlein, K.; Schwager

    1985-01-01

    To date, discussions of the many different types of potential applications of PRA/PSA results and insights to safety-decision-making have been mainly theoretical. Various safety goals have been proposed as decision criteria. However, the discussion on the role of PRA/PSA and Safety Goals in safety-decision-making, especially in licensing, is controversial. A Working Group of the OECD Nuclear Energy Agency is completing a compilation and evaluation of real examples of past and present practical experience with the application of probabilistic methods in reactor safety decision-making, with the idea of developing a common understanding in this area. More than fifty different cases where PRA has influenced decision-making have been surveyed. These include, for example, regulatory changes, fixing of licensing requirements, plant specific modifications of design of operation, prioritization of safety issues and emergency planning. This feedback of experience - both positive and negative - with PRA/PSA applications is considered to provide guidance on how probabilistic approaches can be introduced into current safety practices, and on desirable future developments in probabilistic methods and specific PSA/PRA studies. Generic insights from the survey are given.

  9. 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)

  10. Feedback Is a Two-Way Street

    ERIC Educational Resources Information Center

    Tovani, Cris

    2012-01-01

    In this article, the author shares her experience that illustrates that the feedback students give is just as important as the feedback they get. For her, the idea that students giving her feedback was more powerful than her giving them feedback sounded too good to be true. If she could come up with a system to regularly collect feedback that did…

  11. Simulation model for the closed plant experiment facility of CEEF.

    PubMed

    Abe, Koichi; Ishikawa, Yoshio; Kibe, Seishiro; Nitta, Keiji

    2005-01-01

    The Closed Ecology Experiment Facilities (CEEF) is a testbed for Controlled Ecological Life Support Systems (CELSS) investigations. CEEF including the physico-chemical material regenerative system has been constructed for the experiments of material circulation among plants, breeding animals and crew of CEEF. Because CEEF is a complex system, an appropriate schedule for the operation must be prepared in advance. The CEEF behavioral Prediction System, CPS, that will help to confirm the operation schedule, is under development. CPS will simulate CEEFs behavior with data (conditions of equipments, quantity of materials in tanks, etc.) of CEEF and an operation schedule that will be made by the operation team everyday, before the schedule will be carried out. The result of the simulation will show whether the operation schedule is appropriate or not. In order to realize CPS, models of the simulation program that is installed in CPS must mirror the real facilities of CEEF. For the first step of development, a flexible algorithm of the simulation program was investigated. The next step was development of a replicate simulation model of the material circulation system for the Closed Plant Experiment Facility (CPEF) that is a part of CEEF. All the parts of a real material circulation system for CPEF are connected together and work as a complex mechanism. In the simulation model, the system was separated into 38 units according to its operational segmentation. In order to develop each model for its corresponding unit, specifications for the model were fixed based on the specifications of the real part. These models were put into a simulation model for the system. PMID:16175692

  12. Simulation model for the closed plant experiment facility of CEEF

    NASA Astrophysics Data System (ADS)

    Abe, Koichi; Ishikawa, Yoshio; Kibe, Seishiro; Nitta, Keiji

    The Closed Ecology Experiment Facilities (CEEF) is a testbed for Controlled Ecological Life Support Systems (CELSS) investigations. CEEF including the physico-chemical material regenerative system has been constructed for the experiments of material circulation among plants, breeding animals and crew of CEEF. Because CEEF is a complex system, an appropriate schedule for the operation must be prepared in advance. The CEEF behavioral Prediction System, CPS, that will help to confirm the operation schedule, is under development. CPS will simulate CEEFs behavior with data (conditions of equipments, quantity of materials in tanks, etc.) of CEEF and an operation schedule that will be made by the operation team everyday, before the schedule will be carried out. The result of the simulation will show whether the operation schedule is appropriate or not. In order to realize CPS, models of the simulation program that is installed in CPS must mirror the real facilities of CEEF. For the first step of development, a flexible algorithm of the simulation program was investigated. The next step was development of a replicate simulation model of the material circulation system for the Closed Plant Experiment Facility (CPEF) that is a part of CEEF. All the parts of a real material circulation system for CPEF are connected together and work as a complex mechanism. In the simulation model, the system was separated into 38 units according to its operational segmentation. In order to develop each model for its corresponding unit, specifications for the model were fixed based on the specifications of the real part. These models were put into a simulation model for the system.

  13. 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.

  14. Sodium conversion experiments in the Inert Carrier Process demonstration plant

    SciTech Connect

    Keneshea, F.J.; Hobart, S.A.; Kelly, M.T.; Pohl, C.S.; Riley, D.

    1983-01-01

    The purpose of the sodium treatment studies reported here was to evaluate the use of the Inert Carrier Process (ICP) for converting sodium metal to a stable disposal form. The ICP demonstration plant consists of a closed loop of silicone oil that is circulated through a reservoir called a disperser. Solid sodium particles were fed to the disperser and kept suspended in the silicone oil carrier by turbulence. The sodium did not react with the silicone oil carrier. The dispersion of sodium in silicone oil was fed to an in-line mixer (''jet'' mixer) where it was mixed with a reactant. Water was used as the reactant in most of the tests, generating sodium hydroxide and hydrogen as the initial products. Analysis of the final solid product from the reaction indicated that the sodium hydroxide initial product interacted with the silicone oil. Complete reaction of the sodium in the demonstration plant required at least a 6/1 molar ratio of water to sodium. Good separation of the product solution was difficult because of the small difference in density between the aqueous product phase and the organic carrier phase. Emulsification of the silicone oil-aqueous solution was minimized by applying heat to the separator. Foaming of the silicone oil in the separator occurred, aggravated by the evolution of hydrogen from the sodium conversion reaction. Bench-scale tests were conducted to analyze and resolve several problems encountered in the plant experiments, such as incomplete reaction in the jet mixer, poor separation of the product from the silicone oil, formation of an oil aqueous solution emulsion in the separator, and oil foaming in the separator. Solidification tests were carried out to immobilize the sodium conversion product by mixing it with various binders. The most satisfactory binder was EPON 828, an epoxy resin.

  15. Utilization of operating experience to prevent piping failures at steam plants

    SciTech Connect

    Adams, T.S.; Dietrich, E.B.

    1999-11-01

    The key to preventing flow-accelerated corrosion (FAC) induced piping failures in steam plants is the development and implementation of a methodical program for assessing plant susceptibility to FAC and managing the effects of FAC. One of the key elements of an effective FAC program is the accurate and comprehensive utilization of plant-specific and industry-wide operating experience. Operating experience should be used to develop the program to identify specific areas for inspection or replacement, and to maintain an effective program. This paper discusses the utilization of operating experience in FAC programs at nuclear power plants, fossil plants and other steam plants.

  16. 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.

  17. 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…

  18. A conceptual model for facilitating learning from physics tasks using visual cueing and outcome feedback: Theory and experiments

    NASA Astrophysics Data System (ADS)

    Agra, Elise Stacey Garasi

    This dissertation investigates the effects of visual cueing and outcome feedback on students' performance, confidence, and visual attention as they solve conceptual physics problems that contain diagrams. The research investigation had two parts. In the first part of the study, participants solved four sets of conceptual physics problems that contain diagrams; each set contained an initial problem, four isomorphic training problems, a near transfer problem (with a slightly different surface feature as the training problems), and a far transfer problem (with considerably different surface feature as the training problems). Participants in the cued conditions saw visual cues overlaid on the training problem diagrams, while those in the feedback conditions were told if their responses were correct or incorrect. In the second part of the study, the same students solved the near and far transfer problems from the first study two weeks later. We found that the combination of visual cueing and outcome feedback improved performance on the near transfer and delayed near transfer problems compared to the initial problem, with no significant difference between them. Thus, the combination of visual cueing and outcome feedback can promote immediate learning and retention. For students who demonstrated immediate learning and retention on the near and far transfer problems, visual cues improved the automaticity of extracting relevant information from the transfer and delayed transfer problem diagrams, while outcome feedback helped automatize the extraction of problem-relevant information on the delayed far transfer problem diagram only. We also showed that students' reported confidence in solving a problem is positively related to their correctness on the problem, and their visual attention to the relevant information on the problem diagram. The most interesting thing was how changes in confidence occurred due to outcome feedback, which were also related to changes in accuracy

  19. 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)

  20. 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.

  1. 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.

  2. 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

  3. 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.

  4. 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.

  5. EXPERIENCE WITH CHLORINE DIOXIDE AT DENVER'S REUSE PLANT

    EPA Science Inventory

    Researchers at Denver's reuse demonstration plant found that the effectiveness of chlorine dioxide treatment is critically dependent on the performance of the generator. Because high chlorine dioxide yields can be obtained even when excessive concentrations of undesirable by-prod...

  6. Operating experience at the Shamokin Culm burning steam generation plant

    SciTech Connect

    Bender, P.A.; Laukaitis, J.F.; Lockman, H.W.; Samela, D.; Smith, W.G.; Tsoumpas, G.

    1983-06-01

    After 9200 hours of operation it can be concluded that low grade anthracite culm refuse fuel can be properly combusted in a fluidized-bed boiler. The Shamokin Culm Burning Steam Generation Plant has demonstrated environmental compliance while operating over a wide range of operational variables. As changes in equipment and materials are implemented and other fuels are combusted, it is expected that a further demonstration of the Plant's capabilities will be realized.

  7. 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

  8. Plant virology and next generation sequencing: experiences with a Potyvirus.

    PubMed

    Kehoe, Monica A; Coutts, Brenda A; Buirchell, Bevan J; Jones, Roger A C

    2014-01-01

    Next generation sequencing is quickly emerging as the go-to tool for plant virologists when sequencing whole virus genomes, and undertaking plant metagenomic studies for new virus discoveries. This study aims to compare the genomic and biological properties of Bean yellow mosaic virus (BYMV) (genus Potyvirus), isolates from Lupinus angustifolius plants with black pod syndrome (BPS), systemic necrosis or non-necrotic symptoms, and from two other plant species. When one Clover yellow vein virus (ClYVV) (genus Potyvirus) and 22 BYMV isolates were sequenced on the Illumina HiSeq2000, one new ClYVV and 23 new BYMV sequences were obtained. When the 23 new BYMV genomes were compared with 17 other BYMV genomes available on Genbank, phylogenetic analysis provided strong support for existence of nine phylogenetic groupings. Biological studies involving seven isolates of BYMV and one of ClYVV gave no symptoms or reactions that could be used to distinguish BYMV isolates from L. angustifolius plants with black pod syndrome from other isolates. Here, we propose that the current system of nomenclature based on biological properties be replaced by numbered groups (I-IX). This is because use of whole genomes revealed that the previous phylogenetic grouping system based on partial sequences of virus genomes and original isolation hosts was unsustainable. This study also demonstrated that, where next generation sequencing is used to obtain complete plant virus genomes, consideration needs to be given to issues regarding sample preparation, adequate levels of coverage across a genome and methods of assembly. It also provided important lessons that will be helpful to other plant virologists using next generation sequencing in the future. PMID:25102175

  9. Plant Virology and Next Generation Sequencing: Experiences with a Potyvirus

    PubMed Central

    Kehoe, Monica A.; Coutts, Brenda A.; Buirchell, Bevan J.; Jones, Roger A. C.

    2014-01-01

    Next generation sequencing is quickly emerging as the go-to tool for plant virologists when sequencing whole virus genomes, and undertaking plant metagenomic studies for new virus discoveries. This study aims to compare the genomic and biological properties of Bean yellow mosaic virus (BYMV) (genus Potyvirus), isolates from Lupinus angustifolius plants with black pod syndrome (BPS), systemic necrosis or non-necrotic symptoms, and from two other plant species. When one Clover yellow vein virus (ClYVV) (genus Potyvirus) and 22 BYMV isolates were sequenced on the Illumina HiSeq2000, one new ClYVV and 23 new BYMV sequences were obtained. When the 23 new BYMV genomes were compared with 17 other BYMV genomes available on Genbank, phylogenetic analysis provided strong support for existence of nine phylogenetic groupings. Biological studies involving seven isolates of BYMV and one of ClYVV gave no symptoms or reactions that could be used to distinguish BYMV isolates from L. angustifolius plants with black pod syndrome from other isolates. Here, we propose that the current system of nomenclature based on biological properties be replaced by numbered groups (I–IX). This is because use of whole genomes revealed that the previous phylogenetic grouping system based on partial sequences of virus genomes and original isolation hosts was unsustainable. This study also demonstrated that, where next generation sequencing is used to obtain complete plant virus genomes, consideration needs to be given to issues regarding sample preparation, adequate levels of coverage across a genome and methods of assembly. It also provided important lessons that will be helpful to other plant virologists using next generation sequencing in the future. PMID:25102175

  10. 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

  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. 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.

  13. Operating experience feedback report: Reliability of safety-related steam turbine-driven standby pumps. Commercial power reactors, Volume 10

    SciTech Connect

    Boardman, J.R.

    1994-10-01

    This report documents a detailed analysis of failure initiators, causes and design features for steam turbine assemblies (turbines with their related components, such as governors and valves) which are used as drivers for standby pumps in the auxiliary feedwater systems of US commercial pressurized water reactor plants, and in the high pressure coolant injection and reactor core isolation cooling systems of US commercial boiling water reactor plants. These standby pumps provide a redundant source of water to remove reactor core heat as specified in individual plant safety analysis reports. The period of review for this report was from January 1974 through December 1990 for licensee event reports (LERS) and January 1985 through December 1990 for Nuclear Plant Reliability Data System (NPRDS) failure data. This study confirmed the continuing validity of conclusions of earlier studies by the US Nuclear Regulatory Commission and by the US nuclear industry that the most significant factors in failures of turbine-driven standby pumps have been the failures of the turbine-drivers and their controls. Inadequate maintenance and the use of inappropriate vendor technical information were identified as significant factors which caused recurring failures.

  14. Coress feedback

    PubMed Central

    2012-01-01

    This issue of CORESS feedback highlights yet again the importance of checking medications before administration and of adequate handover. Documentation of important medical data including drug allergies, as failed to happen in the case described below, is vital. We are grateful to the clinicians who have provided the material for these reports. The online reporting form is on our website (www.coress.org.uk), which also includes all previous feedback reports. Published contributions will be acknowledged by a ‘Certificate of Contribution’, which may be included in the contributor’s record of continuing professional development.

  15. ABCDEFG IS - the principle of constructive feedback.

    PubMed

    Bhattarai, M

    2007-01-01

    Feedback is an integral part of any learning experience. Constructive feedback is a powerful instrument and facilitates the learner's professional and personal development. "ABCDEFG IS", a mnemonic for the principles of constructive feedback, stands for Amount of the information, Benefit of the trainees, Change behaviour, Descriptive language, Environment, Focused, Group check, Interpretation check, and Sharing information. The eight important steps of feedback are: Ensure prior information, Collect data, Make appropriate meeting arrangement, Begin by encouraging self assessment by the trainee, Highlight areas where the trainee is doing well, Give feedback, Handle reaction maintaining the dignity and Plan actions. Communication and reflection also share many of the principles and steps of constructive feedback and giving regular feedback, thus, helps to improve communication and reflection. The feedback provider would be able to provide genuine feedback by following the appropriate steps and principles of constructive feedback and realize how important and rewarding its role is in teaching learning activities. PMID:18274573

  16. 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

  17. 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)

  18. ``From seed-to-seed'' experiment with wheat plants under space-flight conditions

    NASA Astrophysics Data System (ADS)

    Mashinsky, A.; Ivanova, I.; Derendyaeva, T.; Nechitailo, G.; Salisbury, F.

    1994-11-01

    An important goal with plant experiments in microgravity is to achieve a complete life cycle, the ``seed-to-seed experiment''. Some Soviet attempts to reach this goal are described, notably an experiment with the tiny mustard, Arabidopsis thaliana, in the Phyton 3 device on Salyut 7. Normal seeds were produced although yields were reduced and development was delayed. Several other experiments have shown abnormalities in plants grown in space. In recent work, plants of wheat (Triticum aestivum) were studied on the ground and then in a preliminary experiment in space. Biometric indices of vegetative space plants were 2 to 2.5 times lower than those of controls, levels of chlorophyll a and b were reduced (no change in the ratio of the two pigments), carotenoids were reduced, there was a serious imbalance in major minerals, and membrane lipids were reduced (no obvious change in lipid patterns). Following the preliminary studies, an attempt was made with the Svetoblock-M growth unit to grow a super-dwarf wheat cultivar through a life cycle. The experiment lasted 167 d on Mir. Growth halted from about day 40 to day 100, when new shoots appeared. Three heads had appeared in the boot (surrounded by leaves) when plants were returned to earth. One head was sterile, but 28 seeds matured on earth, and most of these have since produced normal plants and seeds. In principle, a seed-to-seed experiment with wheat should be successful in microgravity.

  19. Non-linear feedbacks between climate change, hydrologic partitioning, plant available water, and carbon cycling in montane forests

    NASA Astrophysics Data System (ADS)

    Brooks, P. D.; Litvak, M. E.; Harpold, A. A.; Molotch, N. P.; McIntosh, J. C.; Troch, P. A.; Zapata, X.

    2011-12-01

    Changes in both temperature and the amount and timing of precipitation have the potential to profoundly impact water balance in mountain ecosystems. Although changes in the amount of precipitation and potential evapotranspiration are widely considered in climate change scenarios, less attention has been given to how changes in climate or land cover may affect hydrologic partitioning and plant available water. The focus of this presentation is on how spatial transitions in ecosystem structure and temporal transitions in climate affect the fraction of precipitation potentially available to vegetation. In most temperate mountain environments winter snows are a significant fraction of annual precipitation and understanding the partitioning of snow and snow melt is critical for predicting both ecosystem water availability and stream flow under future climate scenarios. Spatial variability in net snow water input is a function of the interaction of snowfall, wind, and solar radiation with topography and vegetation structure. Integrated over larger scales these interactions may result in between 0% and 40% sublimation of winter snowfall before melt, effectively excluding this water from growing season water balance. Once melt begins, variability in the partitioning of snowmelt is driven by the rate of melt, and somewhat less intuitively, by the timing of snow accumulation the previous fall. Early accumulating snowpacks insulate soils and minimize soil frost increasing infiltration of melt the following spring. In contrast, later snowfall results in colder soils, more soil frost, reduced infiltration, increased runoff during melt, and reduced plant available water during the following growing season. This change in hydrologic partitioning, mediated by the timing of snowpack accumulation, results in lower evapotranspiration (ET) and net ecosystem exchange (NEE) the following spring. These findings suggest that abiotic controls on the partitioning of precipitation may

  20. 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.

  1. Experience report on coating concrete containment structures in a maintenance environment in power plants

    SciTech Connect

    Poncio, S.; Hall, D.

    1997-12-01

    Work experiences for coatings and lining applications in power plants are used to provide guidelines and recommendations for future projects. It should be emphasized that some of the work experiences are applicable to other industries, but the scope of this paper is primarily for maintenance concrete coating for immersion service in power plants. Also the importance of preplanning and scheduling of the concrete coating project is discussed.

  2. Assessment of LWR piping design loading based on plant operating experience

    SciTech Connect

    Svensson, P. O.

    1980-08-01

    The objective of this study has been to: (1) identify current Light Water Reactor (LWR) piping design load parameters, (2) identify significant actual LWR piping loads from plant operating experience, (3) perform a comparison of these two sets of data and determine the significance of any differences, and (4) make an evaluation of the load representation in current LWR piping design practice, in view of plant operating experience with respect to piping behavior and response to loading.

  3. Early experience with individual plant evaluations at Davis-Besse

    SciTech Connect

    Darby, J.L.; Deng, S.F.; Flaherty, M.D.

    1989-01-01

    A level 1 probability risk assessment (PRA), including internal floods, is being completed for Toledo Edison's Davis-Besse plant. This effort will be finished by December 1989. A combination of in-house and contractor support has been used in this study. Contractor support focused on transfer of methodology and review of results, while in-house support focused on applications of the methodology. The PRA will form the basis for performing an individual plant examination (IPE) at Davis-Besse. The goals of the IPE must be clearly established before the program is instituted. If the IPE results are to be used for more than meeting the minimum U.S. Nuclear Regulatory Commission requirements, then the complexity of the program increases. For example, use of the IPE results to support changes to technical specifications or emergency operation procedures mandates a more sophisticated approach. Toledo Edison is evaluating how to extend the level 1 PRA to fulfill IPE requirements. Containment analysis is less familiar to in-house staff than is analysis of core cooling systems; contractor support will be required to understand the methods to analyze containment performance and to properly consider uncertainties. An ultimate containment failure analysis is a prerequisite for completing the IPE. Also, the containment analysis must be integrated with, not merely appended to, the core damage analysis.

  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. US plant and radiation dosimetry experiments flown on the soviet satellite COSMOS 1129. Final report

    SciTech Connect

    Heinrich, M.R.; Souza, K.A.

    1981-05-01

    Experiments included: 30 young male Wistar SPF rats used for wide range physiological studies Kosmos Satellites 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.

  6. Feeding Experience of Bemisia tabaci (Hemiptera: Aleyrodidae) Affects Their Performance on Different Host Plants

    PubMed Central

    Shah, M. Mostafizur Rahman; Liu, Tong-Xian

    2013-01-01

    The sweetpotato whitefly, Bemisia tabaci biotype B is extremely polyphagous with >600 species of host plants. We hypothesized that previous experience of the whitefly on a given host plant affects their host selection and performance on the plants without previous experience. We investigated the host selection for feeding and oviposition of adults and development and survival of immatures of three host-plant-experienced populations of B. tabaci, namely Bemisia-eggplant, Bemisia-tomato and Bemisia-cucumber, on their experienced host plant and each of the three other plant species (eggplant, tomato, cucumber and pepper) without previous experience. We found that the influence of previous experience of the whiteflies varied among the populations. All populations refused pepper for feeding and oviposition, whereas the Bemisia-cucumber and the Bemisia-eggplant strongly preferred cucumber. Bemisia-tomato did not show strong preference to any of the three host palnts. Development time from egg to adult eclosion varied among the populations, being shortest on eggplant, longest on pepper, and intermediate on tomato and cucumber except for the Bemisia-cucumber developed similarly on tomato and pepper. The survivorship from egg to adult eclosion of all populations was highest on eggplant (80-98%), lowest on pepper (0-20%), and intermediate on tomato and cucumber. In conclusion, the effects of previous experience of whiteflies on host selection for feeding and oviposition, development, and survivorship varied depending on host plants, and host plants play a stronger role than previous experience. Preference of feeding and oviposition by adults may not accurately reflect host suitability of immatures. These results provided important information for understanding whitefly population dynamics and dispersal among different crop systems. PMID:24146985

  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. Airborne lidar experiments at the Savannah River Plant, June 1985

    SciTech Connect

    Krabill, W.B.; Swift, R.N.

    1987-09-01

    Results are presented from a series of studies conducted at the Department of Energy (DOE) Savannah River Plant (SRP) with the NASA Airborne Oceanographic Lidar (AOL). These studies included a topographic survey of a {approximately}1000 acre lake basin (presently designated L Lake) which had been excavated for use as a cooling pond for L Reactor; a study of the movement of discharged cooling water in Pond C and the warm arm of Par Pond using Rhodamine WT dye as a tag; initial baseline studies of the vegetation cover of the Steel Creek corridor (through which the outflow of L Lake is carried to the Savannah River); and a demonstration of potential forestry applications of the AOL. These investigations were conducted over a 3-day period in June 1985. The AOL is an advanced airborne laser system capable of making temporal or time history measurements of laser backscatter (bathymetry mode) or spectral measurements of laser induced fluorescence from waterborne constituents (fluorosensing mode). The AOL is flown together with auxiliary instruments and camera systems on board a four engine P-3A aircraft. Recent modifications to the AOL allow in-flight changes between the two basic operational modes of the instrument which permitted the topographic study to be conducted on the same flights as the fluorescent dye study. The L Lake topographic survey represents a state-of-the-art demonstration of airborne laser surveying capability.

  9. 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…

  10. Design and Validation of Optimized Feedforward with Robust Feedback Control of a Nuclear Reactor

    SciTech Connect

    Shaffer, Roman; He Weidong; Edwards, Robert M.

    2004-08-15

    Design applications for robust feedback and optimized feedforward control, with confirming results from experiments conducted on the Pennsylvania State University TRIGA reactor, are presented. The combination of feedforward and feedback control techniques complement each other in that robust control offers guaranteed closed-loop stability in the presence of uncertainties, and optimized feedforward offers an approach to achieving performance that is sometimes limited by overly conservative robust feedback control. The design approach taken in this work combines these techniques by first designing robust feedback control. Alternative methods for specifying a low-order linear model and uncertainty specifications, while seeking as much performance as possible, are discussed and evaluated. To achieve desired performance characteristics, the optimized feedforward control is then computed by using the nominal nonlinear plant model that incorporates the robust feedback control.

  11. CORESS feedback

    PubMed Central

    2012-01-01

    This edition of CORESS feedback reinforces the very basic principles of obtaining and using an accurate history and examination to make an appropriate diagnosis in the face of equivocal or uninformative investigations and failing equipment. Case 126 illustrates once again the potential deleterious consequences of failing to check a drug correctly prior to administration. We are grateful to the clinicians who have provided the material for these reports. The online reporting form is on our website (www.coress.org.uk), which also includes all previous feedback reports. Published contributions will be acknowledged by a ‘Certificate of Contribution’, which may be included in the contributor’s record of continuing professional development. CORESS relies heavily on the expertise of the specialty members of the Advisory Board in the preparation of feedback reports and dissemination of safety information related to surgical practice. The organisation is grateful to the following members of the Advisory Board and Board of Directors who have contributed to published reports in 2010 and 2011: Board of Directors: Viscount Bridgeman, Mr Chris Chilton, Mr Martin Else, Professor Nicholas Gair, Mr Adam Lewis CVO, Miss Clare Marx, Mr Andrew May, Lord Bernard Ribeiro, Mr Frank Smith, Mr Peter Tait, Mr Denis Wilkins. Advisory Board: Ms E Baird, Mr Daryl I Baker, Mr Ken Catchpole, Dr Lauren Morgan, Mr Stephen Clark, Mr Robert Davies, Mr Mark Deakin, Ms D Eastwood, Mr Barry Ferris, Mr Mark Fordham, Mr Paul J Gibbs, Mr Grey Giddins, Mr Robert Greatorex, Mr Mervyn Griffiths, Mr John Hammond, Mr William Harkness, Mr M Hemadri, Mr Richard Holdsworth, Miss Claire Hopkins, Professor Zygmunt Krukowski, Mr N Mamode, Mr Ian Martin, Surgeon Commander Mark Midwinter, Mr J Richard Novell, Professor Gerald O’Sullivan, Dr Gerard Panting, Mr Mike Pittam, Dr Mike Powers QC, Ms Patricia Scott, Professor Alastair Thompson, Dr J P van Besouw, Mr Mark Vipond, Mr David Webster, Mr Michael Wyatt.

  12. Neural correlates of feedback processing in toddlers.

    PubMed

    Meyer, Marlene; Bekkering, Harold; Janssen, Denise J C; de Bruijn, Ellen R A; Hunnius, Sabine

    2014-07-01

    External feedback provides essential information for successful learning. Feedback is especially important for learning in early childhood, as toddlers strongly rely on external signals to determine the consequences of their actions. In adults, many electrophysiological studies have elucidated feedback processes using a neural marker called the feedback-related negativity (FRN). The neural generator of the FRN is assumed to be the ACC, located in medial frontal cortex. As frontal brain regions are the latest to mature during brain development, it is unclear when in early childhood a functional feedback system develops. Is feedback differentiated on a neural level in toddlers and in how far is neural feedback processing related to children's behavioral adjustment? In an EEG experiment, we addressed these questions by measuring the brain activity and behavioral performance of 2.5-year-old toddlers while they played a feedback-guided game on a touchscreen. Electrophysiological results show differential brain activity for feedback with a more negative deflection for incorrect than correct outcomes, resembling the adult FRN. This provides the first neural evidence for feedback processing in toddlers. Notably, FRN amplitudes were predictive of adaptive behavior: the stronger the differential brain activity for feedback, the better the toddlers' adaptive performance during the game. Thus, already in early childhood toddlers' feedback-guided performance directly relates to the functionality of their neural feedback processing. Implications for early feedback-based learning as well as structural and functional brain development are discussed. PMID:24392905

  13. 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

  14. Limitation on the use of the horizontal clinostat as a gravity compensator. [in plant geotropism experiments

    NASA Technical Reports Server (NTRS)

    Brown, A. H.; Dahl, A. O.; Chapman, D. K.

    1976-01-01

    If the horizontal clinostat effectively compensates for the influence of the gravity vector on the rotating plant, it should make the plant unresponsive to whatever chronic acceleration may be applied transverse to the axis of clinostat rotation. This was tested by centrifuging plants while they were growing on clinostats. For a number of morphological endpoints of development the results depended on the magnitude of the applied g-force. Therefore, gravity compensation by the clinostat was incomplete. This conclusion is in agreement with results of satellite experiments which are reviewed.

  15. Effects of mammalian herbivore declines on plant communities: observations and experiments in an African savanna.

    PubMed

    Young, Hillary S; McCauley, Douglas J; Helgen, Kristofer M; Goheen, Jacob R; Otárola-Castillo, Erik; Palmer, Todd M; Pringle, Robert M; Young, Truman P; Dirzo, Rodolfo

    2013-07-01

    1. Herbivores influence the structure and composition of terrestrial plant communities. However, responses of plant communities to herbivory are variable and depend on environmental conditions, herbivore identity and herbivore abundance. As anthropogenic impacts continue to drive large declines in wild herbivores, understanding the context dependence of herbivore impacts on plant communities becomes increasingly important. 2. Exclosure experiments are frequently used to assess how ecosystems reorganize in the face of large wild herbivore defaunation. Yet in many landscapes, declines in large wildlife are often accompanied by other anthropogenic activities, especially land conversion to livestock production. In such cases, exclosure experiments may not reflect typical outcomes of human-driven extirpations of wild herbivores. 3. Here, we examine how plant community responses to changes in the identity and abundance of large herbivores interact with abiotic factors (rainfall and soil properties). We also explore how effects of wild herbivores on plant communities differ between large-scale herbivore exclosures and landscape sites where anthropogenic activity has caused wildlife declines, often accompanied by livestock increases. 4. Abiotic context modulated the responses of plant communities to herbivore declines with stronger effect sizes in lower-productivity environments. Also, shifts in plant community structure, composition and species richness following wildlife declines differed considerably between exclosure experiments and landscape sites in which wild herbivores had declined and were often replaced by livestock. Plant communities in low wildlife landscape sites were distinct in both composition and physical structure from both exclosure and control sites in experiments. The power of environmental (soil and rainfall) gradients in influencing plant response to herbivores was also greatly dampened or absent in the landscape sites. One likely explanation for

  16. Effects of mammalian herbivore declines on plant communities: observations and experiments in an African savanna

    PubMed Central

    Young, Hillary S; McCauley, Douglas J; Helgen, Kristofer M; Goheen, Jacob R; Otárola-Castillo, Erik; Palmer, Todd M; Pringle, Robert M; Young, Truman P; Dirzo, Rodolfo

    2013-01-01

    1. Herbivores influence the structure and composition of terrestrial plant communities. However, responses of plant communities to herbivory are variable and depend on environmental conditions, herbivore identity and herbivore abundance. As anthropogenic impacts continue to drive large declines in wild herbivores, understanding the context dependence of herbivore impacts on plant communities becomes increasingly important. 2. Exclosure experiments are frequently used to assess how ecosystems reorganize in the face of large wild herbivore defaunation. Yet in many landscapes, declines in large wildlife are often accompanied by other anthropogenic activities, especially land conversion to livestock production. In such cases, exclosure experiments may not reflect typical outcomes of human-driven extirpations of wild herbivores. 3. Here, we examine how plant community responses to changes in the identity and abundance of large herbivores interact with abiotic factors (rainfall and soil properties). We also explore how effects of wild herbivores on plant communities differ between large-scale herbivore exclosures and landscape sites where anthropogenic activity has caused wildlife declines, often accompanied by livestock increases. 4. Abiotic context modulated the responses of plant communities to herbivore declines with stronger effect sizes in lower-productivity environments. Also, shifts in plant community structure, composition and species richness following wildlife declines differed considerably between exclosure experiments and landscape sites in which wild herbivores had declined and were often replaced by livestock. Plant communities in low wildlife landscape sites were distinct in both composition and physical structure from both exclosure and control sites in experiments. The power of environmental (soil and rainfall) gradients in influencing plant response to herbivores was also greatly dampened or absent in the landscape sites. One likely explanation for

  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.

    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.

  18. 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

  19. 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

  20. 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.

  1. 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. PMID:26098841

  2. Herbivory and Stoichiometric Feedbacks to Primary Production

    PubMed Central

    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. PMID:26098841

  3. Operating and maintenance experiences at the Shamokin clum-burning boiler plant

    SciTech Connect

    Richards, H.W.; Laukaitis, J.F.; Fisher, B.L.; Gmeindl, F.D.; Lockman, H.

    1983-01-01

    A general overview of operating and maintenance experience at the Shamokin plant illustrates the feasibility of using anthracite refuse (culm) and fluidized-bed technology. Successful burning of the low-grade fuel took place over a range of operating conditions. The article describes a series of performance tests and the major maintenance items. 2 references, 7 figures.

  4. Evaluation of experiments involving the study of plant orientation and growth under different gravitational conditions.

    PubMed

    Merkys, A J; Laurinavicius, R S; Svegzdiene, D V; Rakleviciene, D P; Jarosius, A V; Rupainiene, O J

    1989-01-01

    The manifestation of gravitropic reaction in plants has been considered from the phylogenetic point of view. A chart has been suggested according to which it is supposed that the first indications of the ability to identify the direction of the gravitational vector were inherent in the most ancient eukaryotes, which gave rise to green, brown, yellow-green, golden and diatomaceous algae as well as fungi. The experiments on the role of gravity in plant ontogenesis are being continued. The sum total of the data obtained in a number of experiments in space shows that under these conditions a structurally modified but normally functioning gravireceptive apparatus is formed. The data confirming the modification, under changed gravity, of the processes of integral and cellullar growth of the axial organs of seedlings as well as of the anatomo-morphological structure and developmental rates of plants during their prolonged growth in space are presented. It is assumed that this fact testifies to the presence of systems interacting with gravity during plant ontogenesis. At the same time the necessity for further experiments in order to differentiate an immediate biological effect of gravity from the ones conditioned by it indirectly due to the changes in the behavior of liquids and gases is pointed out. The methodological aspects of biological experiments in space as the main source of reliable information on the biological role of gravity are discussed. PMID:11537336

  5. 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.

  6. 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.

  7. Chemical feedbacks in climate sensitivity studies

    NASA Astrophysics Data System (ADS)

    Dietmüller, Simone; Ponater, Michael; Sausen, Robert

    2013-04-01

    Interactively coupled climate chemistry models extend the number of feedback mechanisms in climate change simulations by allowing a variation of several radiatively actice chemical tracers that are prescribed in conventional climate models. Different perturbation experiments including chemical feedbacks were performed using the chemistry-climate model system EMAC coupled to the mixed layer ocean model MLO. The influence of the chemical feedbacks O3, CH4 and N2O on climate response and climate sensitivity is quantified for a series of CO2-perturbation simulations: Equilibrium climate sensitivity is dampened, if chemical feedbacks are included. In case of a CO2 doubling simulation chemical feedbacks decrease climate sensitivity by -3.6% and in case of a 4*CO2 simulation by -8.1%. Analysis of the chemical feedbacks reveals, that the negative feedback of ozone, mainly the feedback of stratospheric ozone, is responsible for this dampening. The radiative feedbacks of CH4 and N2O are negligible, mainly because the model system does not allow interactive emission feedbacks at the Earth's surface for these gases. The feedback of physical parameters is significantly modified by the presence of chemical feedbacks. In case of the CO2-perturbation experiments the negative stratospheric ozone feedback is accompanied by a negative stratospheric H2O feedback change of the same order of magnitude. So the dampening effect of the direct O3 radiative feedback is enhanced. A non-linearity in the damping is found with increasing CO2 concentrations. Reasons are the nonlinear feedbacks of ozone, temperature, and stratospheric water vapor. Additional 6*CO2 simulations with and without chemical feedbacks included show, that the presence of chemic feedbacks helps to prevent a runaway greenhouse effect, as the O3 distribution can react to the upward shift of the tropopause. Also experiments driven by anthropogenic NOx- and CO-emissions were performed, where chemically active trace gases act

  8. 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

  9. Feedback in Action--The Mechanism of the Iris.

    ERIC Educational Resources Information Center

    Pingnet, B.; And Others

    1988-01-01

    Describes two demonstration experiments. Outlines a demonstration of the general principle of positive and negative feedback and the influence of time delays in feedback circuits. Elucidates the principle of negative feedback with a model of the iris of the eye. Emphasizes the importance of feedback in biological systems. (CW)

  10. Learning from Feedback: Spacing and the Delay-Retention Effect

    ERIC Educational Resources Information Center

    Smith, Troy A.; Kimball, Daniel R.

    2010-01-01

    Most modern research on the effects of feedback during learning has assumed that feedback is an error correction mechanism. Recent studies of feedback-timing effects have suggested that feedback might also strengthen initially correct responses. In an experiment involving cued recall of trivia facts, we directly tested several theories of…