WorldWideScience

Sample records for top down bottom

  1. Top-Down Beta Enhances Bottom-Up Gamma.

    Science.gov (United States)

    Richter, Craig G; Thompson, William H; Bosman, Conrado A; Fries, Pascal

    2017-07-12

    Several recent studies have demonstrated that the bottom-up signaling of a visual stimulus is subserved by interareal gamma-band synchronization, whereas top-down influences are mediated by alpha-beta band synchronization. These processes may implement top-down control of stimulus processing if top-down and bottom-up mediating rhythms are coupled via cross-frequency interaction. To test this possibility, we investigated Granger-causal influences among awake macaque primary visual area V1, higher visual area V4, and parietal control area 7a during attentional task performance. Top-down 7a-to-V1 beta-band influences enhanced visually driven V1-to-V4 gamma-band influences. This enhancement was spatially specific and largest when beta-band activity preceded gamma-band activity by ∼0.1 s, suggesting a causal effect of top-down processes on bottom-up processes. We propose that this cross-frequency interaction mechanistically subserves the attentional control of stimulus selection. SIGNIFICANCE STATEMENT Contemporary research indicates that the alpha-beta frequency band underlies top-down control, whereas the gamma-band mediates bottom-up stimulus processing. This arrangement inspires an attractive hypothesis, which posits that top-down beta-band influences directly modulate bottom-up gamma band influences via cross-frequency interaction. We evaluate this hypothesis determining that beta-band top-down influences from parietal area 7a to visual area V1 are correlated with bottom-up gamma frequency influences from V1 to area V4, in a spatially specific manner, and that this correlation is maximal when top-down activity precedes bottom-up activity. These results show that for top-down processes such as spatial attention, elevated top-down beta-band influences directly enhance feedforward stimulus-induced gamma-band processing, leading to enhancement of the selected stimulus. Copyright © 2017 Richter, Thompson et al.

  2. The Interplay of Top-Down and Bottom-Up

    DEFF Research Database (Denmark)

    Winkler, Till; Brown, Carol V.; Ozturk, Pinar

    2014-01-01

    The exchange of patient health information across different organizations involved in healthcare delivery has potential benefits for a wide range of stakeholders. However, many governments in Europe and in the U.S. have, despite both top-down and bottom-up initiatives, experienced major barriers...... in achieving sustainable models for implementing health information exchange (HIE) throughout their healthcare systems. In the case of the U.S., three years after stimulus funding allocated as part of the 2009 HITECH Act, the extent to which government funding will be needed to sustain health information...... organizations (HIOs) that facilitate HIE across regional stakeholders remains an unanswered question. This research investigates the impacts of top-down and bottom-up initiatives on the evolutionary paths of HIOs in two contingent states in the U.S. (New Jersey and New York) which had different starting...

  3. Combining bottom-up and top-down

    International Nuclear Information System (INIS)

    Boehringer, Christoph; Rutherford, Thomas F.

    2008-01-01

    We motivate the formulation of market equilibrium as a mixed complementarity problem which explicitly represents weak inequalities and complementarity between decision variables and equilibrium conditions. The complementarity format permits an energy-economy model to combine technological detail of a bottom-up energy system with a second-best characterization of the over-all economy. Our primary objective is pedagogic. We first lay out the complementarity features of economic equilibrium and demonstrate how we can integrate bottom-up activity analysis into a top-down representation of the broader economy. We then provide a stylized numerical example of an integrated model - within both static and dynamic settings. Finally, we present illustrative applications to three themes figuring prominently on the energy policy agenda of many industrialized countries: nuclear phase-out, green quotas, and environmental tax reforms

  4. Combining bottom-up and top-down

    Energy Technology Data Exchange (ETDEWEB)

    Boehringer, Christoph [Department of Economics, University of Oldenburg, Oldenburg (Germany); Centre for European Economic Research (ZEW), Mannheim (Germany); Rutherford, Thomas F. [Ann Arbor, Michigan (United States)

    2008-03-15

    We motivate the formulation of market equilibrium as a mixed complementarity problem which explicitly represents weak inequalities and complementarity between decision variables and equilibrium conditions. The complementarity format permits an energy-economy model to combine technological detail of a bottom-up energy system with a second-best characterization of the over-all economy. Our primary objective is pedagogic. We first lay out the complementarity features of economic equilibrium and demonstrate how we can integrate bottom-up activity analysis into a top-down representation of the broader economy. We then provide a stylized numerical example of an integrated model - within both static and dynamic settings. Finally, we present illustrative applications to three themes figuring prominently on the energy policy agenda of many industrialized countries: nuclear phase-out, green quotas, and environmental tax reforms. (author)

  5. Combining Top-down and Bottom-up Accountability: Evidence from a Bribery Experiment.

    OpenAIRE

    Danila Serra

    2008-01-01

    Monitoring corruption typically relies on top-down interventions aimed at increasing the probability of external controls and the severity of punishment. An alternative approach to fighting corruption is to induce bottom-up pressure for reform. Recent studies have shown that both top-down and bottom-up mechanisms are rarely able to keep service providers accountable. This paper investigates the effectiveness of an accountability system that combines bottom-up monitoring and top-down auditing ...

  6. Flipped Top-Down is Systematic Bottom-Up

    NARCIS (Netherlands)

    Zaytsev, V.; Sturm, A.; Clark, T.

    2016-01-01

    The paper presents an experience report in course design for a versatile group of computer science students where their needs were surfaced and met by the combination of strict top-down exposure to course material and the flipped classroom model of lecturing.

  7. Bottom-up vs. top-down effects on terrestrial insect herbivores: a meta-analysis.

    Science.gov (United States)

    Vidal, Mayra C; Murphy, Shannon M

    2018-01-01

    Primary consumers are under strong selection from resource ('bottom-up') and consumer ('top-down') controls, but the relative importance of these selective forces is unknown. We performed a meta-analysis to compare the strength of top-down and bottom-up forces on consumer fitness, considering multiple predictors that can modulate these effects: diet breadth, feeding guild, habitat/environment, type of bottom-up effects, type of top-down effects and how consumer fitness effects are measured. We focused our analyses on the most diverse group of primary consumers, herbivorous insects, and found that in general top-down forces were stronger than bottom-up forces. Notably, chewing, sucking and gall-making herbivores were more affected by top-down than bottom-up forces, top-down forces were stronger than bottom-up in both natural and controlled (cultivated) environments, and parasitoids and predators had equally strong top-down effects on insect herbivores. Future studies should broaden the scope of focal consumers, particularly in understudied terrestrial systems, guilds, taxonomic groups and top-down controls (e.g. pathogens), and test for more complex indirect community interactions. Our results demonstrate the surprising strength of forces exerted by natural enemies on herbivorous insects, and thus the necessity of using a tri-trophic approach when studying insect-plant interactions. © 2017 John Wiley & Sons Ltd/CNRS.

  8. Mapping practices of project management – merging top-down and bottom-up perspectives

    DEFF Research Database (Denmark)

    Thuesen, Christian

    2015-01-01

    This paper presents a new methodology for studying different accounts of project management practices based on network mapping and analysis. Drawing upon network mapping and visualization as an analytical strategy top-down and bottom-up accounts of project management practice are analysed...... and compared. The analysis initially reveals a substantial difference between the top-down and bottom-up accounts of practice. Furthermore it identifies a soft side of project management that is central in the bottom-up account but absent from the top-down. Finally, the study shows that network mapping...

  9. Bottom-up and top-down emotion generation: implications for emotion regulation

    Science.gov (United States)

    Misra, Supriya; Prasad, Aditya K.; Pereira, Sean C.; Gross, James J.

    2012-01-01

    Emotion regulation plays a crucial role in adaptive functioning and mounting evidence suggests that some emotion regulation strategies are often more effective than others. However, little attention has been paid to the different ways emotions can be generated: from the ‘bottom-up’ (in response to inherently emotional perceptual properties of the stimulus) or ‘top-down’ (in response to cognitive evaluations). Based on a process priming principle, we hypothesized that mode of emotion generation would interact with subsequent emotion regulation. Specifically, we predicted that top-down emotions would be more successfully regulated by a top-down regulation strategy than bottom-up emotions. To test this hypothesis, we induced bottom-up and top-down emotions, and asked participants to decrease the negative impact of these emotions using cognitive reappraisal. We observed the predicted interaction between generation and regulation in two measures of emotional responding. As measured by self-reported affect, cognitive reappraisal was more successful on top-down generated emotions than bottom-up generated emotions. Neurally, reappraisal of bottom-up generated emotions resulted in a paradoxical increase of amygdala activity. This interaction between mode of emotion generation and subsequent regulation should be taken into account when comparing of the efficacy of different types of emotion regulation, as well as when reappraisal is used to treat different types of clinical disorders. PMID:21296865

  10. Integrated Assessment of Energy Policies: A Decomposition of Top-Down and Bottom-Up

    Energy Technology Data Exchange (ETDEWEB)

    Boehringer, Christoph (Univ. of Oldenburg (Germany)); Rutherford, Thomas F. (ETH Zuerich (Switzerland))

    2008-01-15

    The formulation of market equilibrium problems as mixed complementarity problems (MCP) permits integration of bottom-up programming models of the energy system into top-down general equilibrium models of the overall economy. Yet, in practise the MCP approach loses analytical tractability of income effects, when the energy system includes upper and lowrbounds on many decision variables . We therefore advocate the use of complementarity methods to solve only the top-down economic equilibrium model and employ quadratic programming to solve the underlying bottom-up energy supply model. A simple iterative procedure reconciles the equilibrium prices and quantities between both models.

  11. Comparison between bottom-up and top-down approaches in the estimation of measurement uncertainty.

    Science.gov (United States)

    Lee, Jun Hyung; Choi, Jee-Hye; Youn, Jae Saeng; Cha, Young Joo; Song, Woonheung; Park, Ae Ja

    2015-06-01

    Measurement uncertainty is a metrological concept to quantify the variability of measurement results. There are two approaches to estimate measurement uncertainty. In this study, we sought to provide practical and detailed examples of the two approaches and compare the bottom-up and top-down approaches to estimating measurement uncertainty. We estimated measurement uncertainty of the concentration of glucose according to CLSI EP29-A guideline. Two different approaches were used. First, we performed a bottom-up approach. We identified the sources of uncertainty and made an uncertainty budget and assessed the measurement functions. We determined the uncertainties of each element and combined them. Second, we performed a top-down approach using internal quality control (IQC) data for 6 months. Then, we estimated and corrected systematic bias using certified reference material of glucose (NIST SRM 965b). The expanded uncertainties at the low glucose concentration (5.57 mmol/L) by the bottom-up approach and top-down approaches were ±0.18 mmol/L and ±0.17 mmol/L, respectively (all k=2). Those at the high glucose concentration (12.77 mmol/L) by the bottom-up and top-down approaches were ±0.34 mmol/L and ±0.36 mmol/L, respectively (all k=2). We presented practical and detailed examples for estimating measurement uncertainty by the two approaches. The uncertainties by the bottom-up approach were quite similar to those by the top-down approach. Thus, we demonstrated that the two approaches were approximately equivalent and interchangeable and concluded that clinical laboratories could determine measurement uncertainty by the simpler top-down approach.

  12. Top-down (Prior Knowledge) and Bottom-up (Perceptual Modality) Influences on Spontaneous Interpersonal Synchronization.

    Science.gov (United States)

    Gipson, Christina L; Gorman, Jamie C; Hessler, Eric E

    2016-04-01

    Coordination with others is such a fundamental part of human activity that it can happen unintentionally. This unintentional coordination can manifest as synchronization and is observed in physical and human systems alike. We investigated the role of top-down influences (prior knowledge of the perceptual modality their partner is using) and bottom-up factors (perceptual modality combination) on spontaneous interpersonal synchronization. We examine this phenomena with respect to two different theoretical perspectives that differently emphasize top-down and bottom-up factors in interpersonal synchronization: joint-action/shared cognition theories and ecological-interactive theories. In an empirical study twelve dyads performed a finger oscillation task while attending to each other's movements through either visual, auditory, or visual and auditory perceptual modalities. Half of the participants were given prior knowledge of their partner's perceptual capabilities for coordinating across these different perceptual modality combinations. We found that the effect of top-down influence depends on the perceptual modality combination between two individuals. When people used the same perceptual modalities, top-down influence resulted in less synchronization and when people used different perceptual modalities, top-down influence resulted in more synchronization. Furthermore, persistence in the change in behavior as a result of having perceptual information about each other ('social memory') was stronger when this top-down influence was present.

  13. Comparing Top-Down with Bottom-Up Approaches: Teaching Data Modeling

    Science.gov (United States)

    Kung, Hsiang-Jui; Kung, LeeAnn; Gardiner, Adrian

    2013-01-01

    Conceptual database design is a difficult task for novice database designers, such as students, and is also therefore particularly challenging for database educators to teach. In the teaching of database design, two general approaches are frequently emphasized: top-down and bottom-up. In this paper, we present an empirical comparison of students'…

  14. Bottom-up and Top-down: An alternate classification of LD authoring approaches

    NARCIS (Netherlands)

    Sodhi, Tim; Miao, Yongwu; Brouns, Francis; Koper, Rob

    2007-01-01

    Sodhi, T., Miao, Y., Brouns, F., & Koper, E. J. R. (2007). Bottom-up and Top-down: An alternate classification of LD authoring approaches. Paper presented at the TENCompetence Open Workshop on Current research on IMS Learning Design and Lifelong Competence Development Infrastructures. June, 21-22,

  15. Bottom-up and top-down effects on plant communities

    DEFF Research Database (Denmark)

    Souza, Lara; Zelikova, Tamara Jane; Sanders, Nate

    2016-01-01

    -down) and soil nitrogen (bottom-up) were manipulated over six years in an existing old-field community. We tracked plant α and β diversity - within plot richness and among plot biodiversity- and aboveground net primary productivity (ANPP) over the course of the experiment. We found that bottom-up factors...... affected ANPP while top-down factors influenced plant community structure. Across years, while N reduction lowered ANPP by 10%, N reduction did not alter ANPP relative to control plots. Further, N reduction lowered ANPP by 20% relative to N addition plots. On the other hand, the reduction of insect...... community composition via shifts in plant dominance....

  16. Top-down and bottom-up definitions of human failure events in human reliability analysis

    International Nuclear Information System (INIS)

    Boring, Ronald Laurids

    2014-01-01

    In the probabilistic risk assessments (PRAs) used in the nuclear industry, human failure events (HFEs) are determined as a subset of hardware failures, namely those hardware failures that could be triggered by human action or inaction. This approach is top-down, starting with hardware faults and deducing human contributions to those faults. Elsewhere, more traditionally human factors driven approaches would tend to look at opportunities for human errors first in a task analysis and then identify which of those errors is risk significant. The intersection of top-down and bottom-up approaches to defining HFEs has not been carefully studied. Ideally, both approaches should arrive at the same set of HFEs. This question is crucial, however, as human reliability analysis (HRA) methods are generalized to new domains like oil and gas. The HFEs used in nuclear PRAs tend to be top-down - defined as a subset of the PRA - whereas the HFEs used in petroleum quantitative risk assessments (QRAs) often tend to be bottom-up - derived from a task analysis conducted by human factors experts. The marriage of these approaches is necessary in order to ensure that HRA methods developed for top-down HFEs are also sufficient for bottom-up applications.

  17. Relative importance of plant-mediated bottom-up and top-down forces on herbivore abundance on Brassica oleracea

    NARCIS (Netherlands)

    Kos, M.; Broekgaarden, C.; Kabouw, P.; Oude Lenferink, K.; Poelman, E.H.; Vet, L.E.M.; Dicke, M.; Loon, van J.J.A.

    2011-01-01

    1. Arthropod communities are structured by complex interactions between bottom-up (resource-based) and top-down (natural enemy-based) forces. Their relative importance in shaping arthropod communities, however, continues to be under debate. Bottom-up and top-down forces can be affected by

  18. The generation of myricetin-nicotinamide nanococrystals by top down and bottom up technologies.

    Science.gov (United States)

    Liu, Mingyu; Hong, Chao; Li, Guowen; Ma, Ping; Xie, Yan

    2016-09-30

    Myricetin-nicotinamide (MYR-NIC) nanococrystal preparation methods were developed and optimized using both top down and bottom up approaches. The grinding (top down) method successfully achieved nanococrystals, but there were some micrometer range particles and aggregation. The key consideration of the grinding technology was to control the milling time to determine a balance between the particle size and distribution. In contrast, a modified bottom up approach based on a solution method in conjunction with sonochemistry resulted in a uniform MYR-NIC nanococrystal that was confirmed by powder x-ray diffraction, scanning electron microscopy, dynamic light scattering, and differential scanning calorimeter, and the particle dissolution rate and amount were significantly greater than that of MYR-NIC cocrystal. Notably, this was a simple method without the addition of any non-solvent. We anticipate our findings will provide some guidance for future nanococrystal preparation as well as its application in both chemical and pharmaceutical area.

  19. Mechanisms of knowledge flows in bottom-up and top-down cluster initiatives

    Directory of Open Access Journals (Sweden)

    Wojciech Dyba

    2016-01-01

    Full Text Available Knowledge flows are widely believed to be a phenomenon of clusters, and inducing them is one of the chief objectives in establishing and promoting cluster initiatives (CI. However, not many studies discuss how these flows and their effects may differ depending on the mode of CI creation and on the role of public authorities in this process. The main aim of this article is to compare mechanisms of knowledge flows in bottom-up and top-down cluster initiatives. The results of an empirical research involving two case studies in western Poland, obtained through the use of Social Network Analysis (SNA, allowed stating that in bottom-up cluster initiatives firms which were innovation leaders played a prime role in disseminating technological and business knowledge, while in the top-down initiatives the most important were representatives of universities and research centres as well as formal coordinators of cooperation. Policy implications stemming from these results were identified.

  20. Learning affects top down and bottom up modulation of eye movements in decision making

    DEFF Research Database (Denmark)

    Orquin, Jacob Lund; Bagger, Martin; Mueller Loose, Simone

    2013-01-01

    Repeated decision making is subject to changes over time such as decreases in decision time and information use and increases in decision accuracy. We show that a traditional strategy selection view of decision making cannot account for these temporal dynamics without relaxing main assumptions...... about what defines a decision strategy. As an alternative view we suggest that temporal dynamics in decision making are driven by attentional and perceptual processes and that this view has been expressed in the information reduction hypothesis. We test the information reduction hypothesis by integrating...... it in a broader framework of top down and bottom up processes and derive the predictions that repeated decisions increase top down control of attention capture which in turn leads to a reduction in bottom up attention capture. To test our hypotheses we conducted a repeated discrete choice experiment with three...

  1. A balance of bottom-up and top-down in linking climate policies

    Science.gov (United States)

    Green, Jessica F.; Sterner, Thomas; Wagner, Gernot

    2014-12-01

    Top-down climate negotiations embodied by the Kyoto Protocol have all but stalled, chiefly because of disagreements over targets and objections to financial transfers. To avoid those problems, many have shifted their focus to linkage of bottom-up climate policies such as regional carbon markets. This approach is appealing, but we identify four obstacles to successful linkage: different levels of ambition; competing domestic policy objectives; objections to financial transfers; and the difficulty of close regulatory coordination. Even with a more decentralized approach, overcoming the 'global warming gridlock' of the intergovernmental negotiations will require close international coordination. We demonstrate how a balance of bottom-up and top-down elements can create a path toward an effective global climate architecture.

  2. Top down and bottom up selection drives variations in frequency and form of a visual signal

    OpenAIRE

    Yeh, Chien-Wei; Blamires, Sean J.; Liao, Chen-Pan; Tso, I.-Min

    2015-01-01

    The frequency and form of visual signals can be shaped by selection from predators, prey or both. When a signal simultaneously attracts predators and prey, selection may favour a strategy that minimizes risks while attracting prey. Accordingly, varying the frequency and form of the silken decorations added to their web may be a way that Argiope spiders minimize predation while attracting prey. Nonetheless, the role of extraneous factors renders the influences of top down and bottom up selecti...

  3. Dissociable effects of top-down and bottom-up attention during episodic encoding

    Science.gov (United States)

    Uncapher, Melina R.; Hutchinson, J. Benjamin; Wagner, Anthony D.

    2011-01-01

    It is well established that the formation of memories for life’s experiences—episodic memory—is influenced by how we attend to those experiences, yet the neural mechanisms by which attention shapes episodic encoding are still unclear. We investigated how top-down and bottom-up attention contribute to memory encoding of visual objects in humans by manipulating both types of attention during functional magnetic resonance imaging (fMRI) of episodic memory formation. We show that dorsal parietal cortex—specifically, intraparietal sulcus (IPS)—was engaged during top-down attention and was also recruited during the successful formation of episodic memories. By contrast, bottom-up attention engaged ventral parietal cortex—specifically, temporoparietal junction (TPJ)—and was also more active during encoding failure. Functional connectivity analyses revealed further dissociations in how top-down and bottom-up attention influenced encoding: while both IPS and TPJ influenced activity in perceptual cortices thought to represent the information being encoded (fusiform/lateral occipital cortex), they each exerted opposite effects on memory encoding. Specifically, during a preparatory period preceding stimulus presentation, a stronger drive from IPS was associated with a higher likelihood that the subsequently attended stimulus would be encoded. By contrast, during stimulus processing, stronger connectivity with TPJ was associated with a lower likelihood the stimulus would be successfully encoded. These findings suggest that during encoding of visual objects into episodic memory, top-down and bottom-up attention can have opposite influences on perceptual areas that subserve visual object representation, suggesting that one manner in which attention modulates memory is by altering the perceptual processing of to-be-encoded stimuli. PMID:21880922

  4. An integrated top-down and bottom-up strategy for characterization protein isoforms and modifications

    Energy Technology Data Exchange (ETDEWEB)

    Wu, Si; Tolic, Nikola; Tian, Zhixin; Robinson, Errol W.; Pasa-Tolic, Ljiljana

    2011-04-15

    Bottom-up and top-down strategies are two commonly used methods for mass spectrometry (MS) based protein identification; each method has its own advantages and disadvantages. In this chapter, we describe an integrated top-down and bottom-up approach facilitated by concurrent liquid chromatography-mass spectrometry (LC-MS) analysis and fraction collection for comprehensive high-throughput intact protein profiling. The approach employs a high resolution reversed phase (RP) LC separation coupled with LC eluent fraction collection and concurrent on-line MS with a high field (12 Tesla) Fourier-transform ion cyclotron resonance (FTICR) mass spectrometer. Protein elusion profiles and tentative modified protein identification are made using detected intact protein mass in conjunction with bottom-up protein identifications from the enzymatic digestion and analysis of corresponding LC fractions. Specific proteins of biological interest are incorporated into a target ion list for subsequent off-line gas-phase fragmentation that uses an aliquot of the original collected LC fraction, an aliquot of which was also used for bottom-up analysis.

  5. Top-down versus bottom-up processing of influence diagrams in probabilistic analysis

    International Nuclear Information System (INIS)

    Timmerman, R.D.; Burns, T.J.; Dodds, H.L. Jr.

    1986-01-01

    Recent work by Phillips and Selby has shown that influence diagram methodology can be a useful analytical tool in reactor safety studies. In some instances an influence diagram can be used as a graphical representation of probabilistic dependence within a system or event sequence. Under these circumstances, Bayesian statistics is employed to transform the relationships depicted in the influence diagram into the correct expression for a desired marginal probability (e.g. the top node). Top-down and bottom-up algorithms have emerged as the dominant methods for quantifying influence diagrams. The purpose of this paper is to demonstrate a potential error in employing the bottom-up algorithm when dealing with interdependencies

  6. Top-down versus bottom-up processing of influence diagrams in probabilistic analysis

    International Nuclear Information System (INIS)

    Timmerman, R.D.; Burns, T.J.; Dodds, H.L. Jr.

    1984-01-01

    Recent work by Phillips et al., and Selby et al., has shown that influence diagram methodology can be a useful analytical tool in reactor safety studies. An influence diagram is a graphical representation of probabilistic dependence within a system or event sequence. Bayesian statistics are employed to transform the relationships depicted in the influence diagram into the correct expression for a desired marginal probability (e.g. the top event). As with fault trees, top-down and bottom-up algorithms have emerged as the dominant methods for quantifying influence diagrams. Purpose of this paper is to demonstrate a potential error in employing the bottom-up algorithm when dealing with interdependencies. In addition, the computing efficiency of both methods is discussed

  7. Preferential effect of isoflurane on top-down vs. bottom-up pathways in sensory cortex.

    Science.gov (United States)

    Raz, Aeyal; Grady, Sean M; Krause, Bryan M; Uhlrich, Daniel J; Manning, Karen A; Banks, Matthew I

    2014-01-01

    The mechanism of loss of consciousness (LOC) under anesthesia is unknown. Because consciousness depends on activity in the cortico-thalamic network, anesthetic actions on this network are likely critical for LOC. Competing theories stress the importance of anesthetic actions on bottom-up "core" thalamo-cortical (TC) vs. top-down cortico-cortical (CC) and matrix TC connections. We tested these models using laminar recordings in rat auditory cortex in vivo and murine brain slices. We selectively activated bottom-up vs. top-down afferent pathways using sensory stimuli in vivo and electrical stimulation in brain slices, and compared effects of isoflurane on responses evoked via the two pathways. Auditory stimuli in vivo and core TC afferent stimulation in brain slices evoked short latency current sinks in middle layers, consistent with activation of core TC afferents. By contrast, visual stimuli in vivo and stimulation of CC and matrix TC afferents in brain slices evoked responses mainly in superficial and deep layers, consistent with projection patterns of top-down afferents that carry visual information to auditory cortex. Responses to auditory stimuli in vivo and core TC afferents in brain slices were significantly less affected by isoflurane compared to responses triggered by visual stimuli in vivo and CC/matrix TC afferents in slices. At a just-hypnotic dose in vivo, auditory responses were enhanced by isoflurane, whereas visual responses were dramatically reduced. At a comparable concentration in slices, isoflurane suppressed both core TC and CC/matrix TC responses, but the effect on the latter responses was far greater than on core TC responses, indicating that at least part of the differential effects observed in vivo were due to local actions of isoflurane in auditory cortex. These data support a model in which disruption of top-down connectivity contributes to anesthesia-induced LOC, and have implications for understanding the neural basis of consciousness.

  8. Top-down or bottom-up modelling. An application to CO2 abatement

    International Nuclear Information System (INIS)

    Laroui, F.; Van Leeuwen, M.J.

    1995-06-01

    In four articles a comparison is made of bottom-up, or engineers'' models, and top-down models, which comprise macro-econometric models, computable general equilibrium models and also models in the system dynamics tradition. In the first article the history of economic modelling is outlined. In the second article the multi-sector macro-economic Computable General Equilibrium model for the Netherlands is described. It can be used to study the long-term effects of fiscal policy measures on economic and environmental indicators, in particular the effects on the level of CO2-emissions. The aim of article 3 is to describe the structure of the electricity supply industry in the UK and how it can be represented in a bottom-up sub-model within a more general E3 sectoral model of the UK economy. The objective of the last paper (4) is mainly a methodological discussion about integrating top-down and bottom-up models which can be used to assess CO2 abatement policies impacts on economic activity

  9. Agricultural ammonia emissions in China: reconciling bottom-up and top-down estimates

    Directory of Open Access Journals (Sweden)

    L. Zhang

    2018-01-01

    Full Text Available Current estimates of agricultural ammonia (NH3 emissions in China differ by more than a factor of 2, hindering our understanding of their environmental consequences. Here we apply both bottom-up statistical and top-down inversion methods to quantify NH3 emissions from agriculture in China for the year 2008. We first assimilate satellite observations of NH3 column concentration from the Tropospheric Emission Spectrometer (TES using the GEOS-Chem adjoint model to optimize Chinese anthropogenic NH3 emissions at the 1∕2°  ×  2∕3° horizontal resolution for March–October 2008. Optimized emissions show a strong summer peak, with emissions about 50 % higher in summer than spring and fall, which is underestimated in current bottom-up NH3 emission estimates. To reconcile the latter with the top-down results, we revisit the processes of agricultural NH3 emissions and develop an improved bottom-up inventory of Chinese NH3 emissions from fertilizer application and livestock waste at the 1∕2°  ×  2∕3° resolution. Our bottom-up emission inventory includes more detailed information on crop-specific fertilizer application practices and better accounts for meteorological modulation of NH3 emission factors in China. We find that annual anthropogenic NH3 emissions are 11.7 Tg for 2008, with 5.05 Tg from fertilizer application and 5.31 Tg from livestock waste. The two sources together account for 88 % of total anthropogenic NH3 emissions in China. Our bottom-up emission estimates also show a distinct seasonality peaking in summer, consistent with top-down results from the satellite-based inversion. Further evaluations using surface network measurements show that the model driven by our bottom-up emissions reproduces the observed spatial and seasonal variations of NH3 gas concentrations and ammonium (NH4+ wet deposition fluxes over China well, providing additional credibility to the improvements we have made to our

  10. Integrating Top-down and Bottom-up Cybersecurity Guidance using XML.

    Science.gov (United States)

    Lubell, Joshua

    2016-08-01

    This paper describes a markup-based approach for synthesizing disparate information sources and discusses a software implementation of the approach. The implementation makes it easier for people to use two complementary, but differently structured, guidance specifications together: the (top-down) Cybersecurity Framework and the (bottom-up) National Institute of Standards and Technology Special Publication 800-53 security control catalog. An example scenario demonstrates how the software implementation can help a security professional select the appropriate safeguards for restricting unauthorized access to an Industrial Control System. The implementation and example show the benefits of this approach and suggest its potential application to disciplines other than cybersecurity.

  11. Integrating Top-down and Bottom-up Cybersecurity Guidance using XML

    Science.gov (United States)

    Lubell, Joshua

    2016-01-01

    This paper describes a markup-based approach for synthesizing disparate information sources and discusses a software implementation of the approach. The implementation makes it easier for people to use two complementary, but differently structured, guidance specifications together: the (top-down) Cybersecurity Framework and the (bottom-up) National Institute of Standards and Technology Special Publication 800-53 security control catalog. An example scenario demonstrates how the software implementation can help a security professional select the appropriate safeguards for restricting unauthorized access to an Industrial Control System. The implementation and example show the benefits of this approach and suggest its potential application to disciplines other than cybersecurity. PMID:27795810

  12. Unsupervised tattoo segmentation combining bottom-up and top-down cues

    Science.gov (United States)

    Allen, Josef D.; Zhao, Nan; Yuan, Jiangbo; Liu, Xiuwen

    2011-06-01

    Tattoo segmentation is challenging due to the complexity and large variance in tattoo structures. We have developed a segmentation algorithm for finding tattoos in an image. Our basic idea is split-merge: split each tattoo image into clusters through a bottom-up process, learn to merge the clusters containing skin and then distinguish tattoo from the other skin via top-down prior in the image itself. Tattoo segmentation with unknown number of clusters is transferred to a figureground segmentation. We have applied our segmentation algorithm on a tattoo dataset and the results have shown that our tattoo segmentation system is efficient and suitable for further tattoo classification and retrieval purpose.

  13. Public engagement as a field of tension between bottom-up and top-down strategies

    DEFF Research Database (Denmark)

    Horsbøl, Anders; Lassen, Inger

    2012-01-01

    In the ongoing debate about climate change, public engagement is given increasing prominence as a possible solution to a general lack of citizen participation in climate change mitigation efforts. Recent years have seen a surge in public engagement initiatives in many countries in the Western world....... These initiatives often have to deal with dilemmas between participatory aspects and other considerations such as planning efficiency, dilemmas that potentially bring about tension between bottom-up and top-down strategies. Literature on climate change issues has addressed the failure of public response, which has...... knowledge and information about climate change has not significantly changed people’s behaviour towards higher involvement....

  14. A top-down bottom-up modeling approach to climate change policy analysis

    International Nuclear Information System (INIS)

    Tuladhar, Sugandha D.; Yuan, Mei; Bernstein, Paul; Montgomery, W. David; Smith, Anne

    2009-01-01

    This paper analyzes macroeconomic impacts of U.S. climate change policies for three different emissions pathways using a top-down bottom-up integrated model. The integrated model couples a technology-rich, bottom-up model of the U.S. electricity sector with a fully dynamic, forward-looking general equilibrium model of the U.S. economy. Our model provides a unique and consistent modeling framework for climate change analysis. Because of the model's detail and flexibility, we use it to examine additional scenarios to analyze many of the major uncertainties surrounding the implementation and impact of climate change policies - the role of command-and-control measures, loss in flexibility mechanisms such as banking, limits on low-emitting technology, and availability of offsets. The results consistently demonstrate that those policies that combine market-oriented abatement incentives with full flexibility are the most cost-effective. (author)

  15. Sustainability and Uncertainty: Bottom-Up and Top-Down Approaches

    Directory of Open Access Journals (Sweden)

    K. Klint Jensen

    2010-04-01

    Full Text Available The widely used concept of sustainability is seldom precisely defined, and its clarification involves making up one’s mind about a range of difficult questions. One line of research (bottom-up takes sustaining a system over time as its starting point and then infers prescriptions from this requirement. Another line (top-down takes an economical interpretation of the Brundtland Commission’s suggestion that the present generation’s needsatisfaction should not compromise the need-satisfaction of future generations as its starting point. It then measures sustainability at the level of society and infers prescriptions from this requirement. These two approaches may conflict, and in this conflict the top-down approach has the upper hand, ethically speaking. However, the implicit goal in the top-down approach of justice between generations needs to be refined in several dimensions. But even given a clarified ethical goal, disagreements can arise. At present we do not know what substitutions will be possible in the future. This uncertainty clearly affects the prescriptions that follow from the measure of sustainability. Consequently, decisions about how to make future agriculture sustainable are decisions under uncertainty. There might be different judgments on likelihoods; but even given some set of probabilities, there might be disagreement on the right level of precaution in face of the uncertainty.

  16. Top down and bottom up selection drives variations in frequency and form of a visual signal.

    Science.gov (United States)

    Yeh, Chien-Wei; Blamires, Sean J; Liao, Chen-Pan; Tso, I-Min

    2015-03-30

    The frequency and form of visual signals can be shaped by selection from predators, prey or both. When a signal simultaneously attracts predators and prey selection may favour a strategy that minimizes risks while attracting prey. Accordingly, varying the frequency and form of the silken decorations added to their web may be a way that Argiope spiders minimize predation while attracting prey. Nonetheless, the role of extraneous factors renders the influences of top down and bottom up selection on decoration frequency and form variation difficult to discern. Here we used dummy spiders and decorations to simulate four possible strategies that the spider Argiope aemula may choose and measured the prey and predator attraction consequences for each in the field. The strategy of decorating at a high frequency with a variable form attracted the most prey, while that of decorating at a high frequency with a fixed form attracted the most predators. These results suggest that mitigating the cost of attracting predators while maintaining prey attraction drives the use of variation in decoration form by many Argiope spp. when decorating frequently. Our study highlights the importance of considering top-down and bottom up selection pressure when devising evolutionary ecology experiments.

  17. Comparing effectiveness of top-down and bottom-up strategies in containing influenza.

    Directory of Open Access Journals (Sweden)

    Achla Marathe

    Full Text Available This research compares the performance of bottom-up, self-motivated behavioral interventions with top-down interventions targeted at controlling an "Influenza-like-illness". Both types of interventions use a variant of the ring strategy. In the first case, when the fraction of a person's direct contacts who are diagnosed exceeds a threshold, that person decides to seek prophylaxis, e.g. vaccine or antivirals; in the second case, we consider two intervention protocols, denoted Block and School: when a fraction of people who are diagnosed in a Census Block (resp., School exceeds the threshold, prophylax the entire Block (resp., School. Results show that the bottom-up strategy outperforms the top-down strategies under our parameter settings. Even in situations where the Block strategy reduces the overall attack rate well, it incurs a much higher cost. These findings lend credence to the notion that if people used antivirals effectively, making them available quickly on demand to private citizens could be a very effective way to control an outbreak.

  18. Automatic Polyp Detection via A Novel Unified Bottom-up and Top-down Saliency Approach.

    Science.gov (United States)

    Yuan, Yixuan; Li, Dengwang; Meng, Max Q-H

    2017-07-31

    In this paper, we propose a novel automatic computer-aided method to detect polyps for colonoscopy videos. To find the perceptually and semantically meaningful salient polyp regions, we first segment images into multilevel superpixels. Each level corresponds to different sizes of superpixels. Rather than adopting hand-designed features to describe these superpixels in images, we employ sparse autoencoder (SAE) to learn discriminative features in an unsupervised way. Then a novel unified bottom-up and top-down saliency method is proposed to detect polyps. In the first stage, we propose a weak bottom-up (WBU) saliency map by fusing the contrast based saliency and object-center based saliency together. The contrast based saliency map highlights image parts that show different appearances compared with surrounding areas while the object-center based saliency map emphasizes the center of the salient object. In the second stage, a strong classifier with Multiple Kernel Boosting (MKB) is learned to calculate the strong top-down (STD) saliency map based on samples directly from the obtained multi-level WBU saliency maps. We finally integrate these two stage saliency maps from all levels together to highlight polyps. Experiment results achieve 0.818 recall for saliency calculation, validating the effectiveness of our method. Extensive experiments on public polyp datasets demonstrate that the proposed saliency algorithm performs favorably against state-of-the-art saliency methods to detect polyps.

  19. Top-down instead of bottom-up estimates of uncertainty in INAA results?

    International Nuclear Information System (INIS)

    Bode, P.; De Nadai Fernandes, E.A.

    2005-01-01

    The initial publication of the ISO Guide to the Expression of Uncertainty in Measurement (GUM) and many related documents has resulted in a worldwide awareness of the importance of a realistic estimate of the value reported after the +/- sign. The evaluation of uncertainty in measurement, as introduced by the GUM, is derived from the principles applied in physical measurements. Many testing laboratories have already experienced large problems in applying these principles in e.g. (bio)chemical measurements, resulting in time-consuming evaluations and costly additional experiments. Other, more pragmatic and less costly approaches have been proposed to obtain a realistic estimate of the range in which the true value of the measurement may be found with a certain degree of probability. One of these approaches, the 'top-down method', is based on the standard deviation in the results of intercomparison data. This approach is much easier for tests for which it is either difficult to establish a full measurement equation, or if e.g. matrix-matching reference materials are absent. It has been demonstrated that the GUM 'bottom-up' approach of evaluating uncertainty in measurement can easily be applied in instrumental neutron activation analysis (INAA) as all significant sources of uncertainty can be evaluated. INAA is therefore a valuable technique to test the validity of the top-down approach. In this contribution, examples of the top-down evaluation of uncertainty in INAA derived from participation in intercomparison rounds and proficiency testing schemes will be presented. The results will be compared with the bottom-up evaluation of uncertainty, and ease of applicability, validity and usefullness of both approaches will be discussed.

  20. Evaluations of carbon fluxes estimated by top-down and bottom-up approaches

    Science.gov (United States)

    Murakami, K.; Sasai, T.; Kato, S.; Hiraki, K.; Maksyutov, S. S.; Yokota, T.; Nasahara, K.; Matsunaga, T.

    2013-12-01

    There are two types of estimating carbon fluxes using satellite observation data, and these are referred to as top-down and bottom-up approaches. Many uncertainties are however still remain in these carbon flux estimations, because the true values of carbon flux are still unclear and estimations vary according to the type of the model (e.g. a transport model, a process based model) and input data. The CO2 fluxes in these approaches are estimated by using different satellite data such as the distribution of CO2 concentration in the top-down approach and the land cover information (e.g. leaf area, surface temperature) in the bottom-up approach. The satellite-based CO2 flux estimations with reduced uncertainty can be used efficiently for identifications of large emission area and carbon stocks of forest area. In this study, we evaluated the carbon flux estimates from two approaches by comparing with each other. The Greenhouse gases Observing SATellite (GOSAT) has been observing atmospheric CO2 concentrations since 2009. GOSAT L4A data product is the monthly CO2 flux estimations for 64 sub-continental regions and is estimated by using GOSAT FTS SWIR L2 XCO2 data and atmospheric tracer transport model. We used GOSAT L4A CO2 flux as top-down approach estimations and net ecosystem productions (NEP) estimated by the diagnostic type biosphere model BEAMS as bottom-up approach estimations. BEAMS NEP is only natural land CO2 flux, so we used GOSAT L4A CO2 flux after subtraction of anthropogenic CO2 emissions and oceanic CO2 flux. We compared with two approach in temperate north-east Asia region. This region is covered by grassland and crop land (about 60 %), forest (about 20 %) and bare ground (about 20 %). The temporal variation for one year period was indicated similar trends between two approaches. Furthermore we show the comparison of CO2 flux estimations in other sub-continental regions.

  1. Integrating the bottom-up and top-down approach to energy economy modelling. The case of Denmark

    DEFF Research Database (Denmark)

    Klinge Jacobsen, Henrik

    1998-01-01

    This paper presents results from an integration project covering Danish models based on bottom-up and top-down approaches to energy]economy modelling. The purpose of the project was to identify theoretical and methodological problems for integrating existing models for Denmark and to implement...... an integration of the models. The integration was established through a number of links between energy bottom-up modules and a macroeconomic model. In this integrated model it is possible to analyse both top-down instruments, such as taxes along with bottom-up instruments, such as regulation of technology...

  2. Top-down versus bottom-up processing of influence diagrams in probabilistic analysis

    International Nuclear Information System (INIS)

    Timmerman, R.D.; Burns, T.J.; Dodds, H.L. Jr.

    1986-01-01

    Recent work by Phillips et al and Selby et al has shown that influence diagram methodology can be a useful analytical tool in reactor safety studies. In some instances, an influence diagram can be used as a graphical representation of probabilistic dependence within a system or event sequence. Under these circumstances, Bayesian statistics is employed to transform the relationships depicted in the influence diagram into the correct expression for a desired marginal probability (e.g., the top node). In the references cited above, the authors demonstrated the usefulness of influence diagrams for assessing the reliability of operator performance during pressurized thermal shock transients. In addition, the use of influence diagrams identified the critical variables that had the greatest impact on operator reliability for a particular scenario (e.g., control room design, procedures, etc.). Top-down and bottom-up algorithms have emerged as the dominant methods for quantifying influence diagrams. The purpose of this paper is to demonstrate a potential error in employing the bottom-up algorithm when dealing with interdependencies

  3. Manufacturing at Nanoscale: Top-Down, Bottom-up and System Engineering

    International Nuclear Information System (INIS)

    Zhang Xiang; Sun Cheng; Fang, Nicholas

    2004-01-01

    The current nano-technology revolution is facing several major challenges: to manufacture nanodevices below 20 nm, to fabricate three-dimensional complex nano-structures, and to heterogeneously integrate multiple functionalities. To tackle these grand challenges, the Center for Scalable and Integrated NAno-Manufacturing (SINAM), a NSF Nanoscale Science and Engineering Center, set its goal to establish a new manufacturing paradigm that integrates an array of new nano-manufacturing technologies, including the plasmonic imaging lithography and ultramolding imprint lithography aiming toward critical resolution of 1-10 nm and the hybrid top-down and bottom-up technologies to achieve massively parallel integration of heterogeneous nanoscale components into higher-order structures and devices. Furthermore, SINAM will develop system engineering strategies to scale-up the nano-manufacturing technologies. SINAMs integrated research and education platform will shed light to a broad range of potential applications in computing, telecommunication, photonics, biotechnology, health care, and national security

  4. Mesoporous ZSM-5 Zeolites in Acid Catalysis: Top-Down vs. Bottom-Up Approach

    Directory of Open Access Journals (Sweden)

    Pit Losch

    2017-07-01

    Full Text Available A top-down desilication of Al-rich ZSM-5 zeolites and a bottom-up mesopores creating method were evaluated in this study. Three liquid–solid and one gas–solid heterogeneously-catalysed reactions were chosen to establish relationships between zeolites textural properties and their catalytic behavior in acid-catalysed model reactions that are influenced by shape selectivity: Diels-Alder cyclization between isoprene and methylacrylate, Methanol-to-Olefins (MTO reaction, chlorination of iodobenzene with trichloroisocyanuric acid (TCCA, and Friedel-Crafts acylation of anisole by carboxylic acids with differing sizes. It is found amongst others that no optimal mesoporosity for all the different reactions can be easily obtained, but depending on the chosen application, a specific treatment has to be set to achieve high activity/selectivity and stability.

  5. The Ideological Divide Concerning Climate Change Opinion: Integrating Top-Down and Bottom-Up Approaches

    Directory of Open Access Journals (Sweden)

    Jennifer eJacquet

    2014-12-01

    Full Text Available The United States wields disproportionate global influence in terms of carbon dioxide emissions and international climate policy. This renders it an especially important context in which to examine the interplay among social, psychological, and political factors in shaping attitudes and behaviors about climate change. In this article, we review the emerging literature addressing the liberal-conservative divide in the U.S. with respect to thought, communication, and action concerning climate change. Because of its theoretical and practical significance, we focus on the motivational basis for skepticism and inaction on the part of some, including top-down institutional forces, such as corporate strategy, and bottom-up psychological factors, such as ego, group, and system justification. Although more research is needed to elucidate fully the social, cognitive, and motivational bases of environmental attitudes and behavior, a great deal has been learned in just a few years by focusing on specific ideological factors in addition to general psychological principles.

  6. Unsupervised Tattoo Segmentation Combining Bottom-Up and Top-Down Cues

    Energy Technology Data Exchange (ETDEWEB)

    Allen, Josef D [ORNL

    2011-01-01

    Tattoo segmentation is challenging due to the complexity and large variance in tattoo structures. We have developed a segmentation algorithm for nding tattoos in an image. Our basic idea is split-merge: split each tattoo image into clusters through a bottom-up process, learn to merge the clusters containing skin and then distinguish tattoo from the other skin via top-down prior in the image itself. Tattoo segmentation with unknown number of clusters is transferred to a gure-ground segmentation. We have applied our segmentation algorithm on a tattoo dataset and the results have shown that our tattoo segmentation system is e cient and suitable for further tattoo classi cation and retrieval purpose.

  7. Implementing collaborative improvement - top-down, bottom-up or both?

    DEFF Research Database (Denmark)

    Kaltoft, Rasmus; Boer, Harry; Caniato, Federico

    2007-01-01

    , the study identifies three different implementation approaches. The bottom-up learning-by-doing approach starts at a practical level, with simple improvement activities, and aims at gradually developing a wide range of CoI knowledge, skills and initiatives. The top-down directive approach starts...... with aligning the partners' CoI objectives and an assessment of their collaboration and CoI maturity in order to provide a common platform before actually starting improvement activities. The laissez-faire approach builds on shared goals/vision, meetings on equal terms and joint work, in a non-directive and non......-facilitated way, though. The article demonstrates how and why the different approaches have different effects on the development of collaborative improvement....

  8. Bottom-up and Top-down Input Augment the Variability of Cortical Neurons

    Science.gov (United States)

    Nassi, Jonathan J.; Kreiman, Gabriel; Born, Richard T.

    2016-01-01

    SUMMARY Neurons in the cerebral cortex respond inconsistently to a repeated sensory stimulus, yet they underlie our stable sensory experiences. Although the nature of this variability is unknown, its ubiquity has encouraged the general view that each cell produces random spike patterns that noisily represent its response rate. In contrast, here we show that reversibly inactivating distant sources of either bottom-up or top-down input to cortical visual areas in the alert primate reduces both the spike train irregularity and the trial-to-trial variability of single neurons. A simple model in which a fraction of the pre-synaptic input is silenced can reproduce this reduction in variability, provided that there exist temporal correlations primarily within, but not between, excitatory and inhibitory input pools. A large component of the variability of cortical neurons may therefore arise from synchronous input produced by signals arriving from multiple sources. PMID:27427459

  9. Two Paths to Transforming Markets through Public Sector EnergyEfficiency: Bottom Up versus Top Down

    Energy Technology Data Exchange (ETDEWEB)

    Van Wie McGrory, Laura; Coleman, Philip; Fridley, David; Harris,Jeffrey; Villasenor Franco, Edgar

    2006-05-10

    The evolution of government purchasing initiatives in Mexicoand China, part of the PEPS (Promoting an Energy-efficient Public Sector)program, demonstrates the need for flexibility in designingenergy-efficiency strategies in the public sector. Several years ofpursuing a top-down (federally led) strategy in Mexico produced fewresults, and it was not until the program was restructured in 2004 tofocus on municipal-level purchasing that the program gained momentum.Today, a new partnership with the Mexican federal government is leadingto an intergovernmental initiative with strong support at the federallevel. By contrast, the PEPS purchasing initiative in China wassuccessfully initiated and led at the central government level withstrategic support from international experts. The very different successtrajectories in these two countries provide valuable lessons fordesigning country-specific public sector energy-efficiency initiatives.Enabling conditions for any successful public sector purchasinginitiative include the existence of mandatory energy-efficiencyperformance standards, an effective energy-efficiency endorsementlabeling program, an immediate need for energy conservation, a simplepilot phase (focusing on a limited number of strategically chosenproducts), and specialized technical assistance. Top-down purchasingprograms are likely to be more successful where there is high-levelpolitical endorsement and a national procurement law in place, supportedby a network of trained purchasers. Bottom-up (municipally led)purchasing programs require that municipalities have the authority to settheir own purchasing policies, and also benefit from existing networks ofcities, supported by motivated municipal leaders and trained purchasingofficials.

  10. The changing Chinese SEA indicator guidelines: Top-down or bottom-up?

    International Nuclear Information System (INIS)

    Gao, Jingjing; Christensen, Per; Kørnøv, Lone

    2014-01-01

    In the last decades, China has introduced a set of indicators to guide the Strategic Environmental Assessment (SEA) practice. The most recent indicator system proposed in 2009 is based on sector-specific guidelines and it found its justification in past negative experiences with more general guidelines (from 2003), which were mostly inspired by, or copied from, international experiences. Based on interviews with practitioners, researchers and administrators, we map and analyse the change in the national guidelines. This analysis is based on a description of the indicators that makes it possible to discern different aggregation levels of indicators and then trace the changes occurring under two sets of guidelines. The analysis also reveals the reasons and rationales behind the changes found in the guidelines. This analysis is inspired by implementation theory and a description of some of the more general trends in the development of SEA and other environmental policies in a recent Chinese context. Beside a more top-down, intentional approach specifying indicators for different sectors based on Chinese experiences from the preceding years, another significant change, following the new guidelines, is a more bottom-up approach which gives more discretion to practitioners. This entails a call for practitioners to make decisions on indicators, which involves an interpretation of the ones present in sector guidance. Highlights: • Focusing on the new Chinese national SEA guidelines proposed in 2009 • Mapping and analysing the most recent change in the indicator system • Revealing the reasons and rationales behind the changes found in the new guidelines • A top-down intention specifying indicators for different sectors • A bottom-up effect in giving discretion and interpretation of using indicators

  11. Diversity has stronger top-down than bottom-up effects on decomposition.

    Science.gov (United States)

    Srivastava, Diane S; Cardinale, Bradley J; Downing, Amy L; Duffy, J Emmett; Jouseau, Claire; Sankaran, Mahesh; Wright, Justin P

    2009-04-01

    The flow of energy and nutrients between trophic levels is affected by both the trophic structure of food webs and the diversity of species within trophic levels. However, the combined effects of trophic structure and diversity on trophic transfer remain largely unknown. Here we ask whether changes in consumer diversity have the same effect as changes in resource diversity on rates of resource consumption. We address this question by focusing on consumer-resource dynamics for the ecologically important process of decomposition. This study compares the top-down effect of consumer (detritivore) diversity on the consumption of dead organic matter (decomposition) with the bottom-up effect of resource (detrital) diversity, based on a compilation of 90 observations reported in 28 studies. We did not detect effects of either detrital or consumer diversity on measures of detrital standing stock, and effects on consumer standing stock were equivocal. However, our meta-analysis indicates that reductions in detritivore diversity result in significant reductions in the rate of decomposition. Detrital diversity has both positive and negative effects on decomposition, with no overall trend. This difference between top-down and bottom-up effects of diversity is robust to different effect size metrics and could not be explained by differences in experimental systems or designs between detritivore and detrital manipulations. Our finding that resource diversity has no net effect on consumption in "brown" (detritus-consumer) food webs contrasts with previous findings from "green" (plant-herbivore) food webs and suggests that effects of plant diversity on consumption may fundamentally change after plant death.

  12. The changing Chinese SEA indicator guidelines: Top-down or bottom-up?

    Energy Technology Data Exchange (ETDEWEB)

    Gao, Jingjing, E-mail: Jingjing@plan.aau.dk; Christensen, Per; Kørnøv, Lone

    2014-01-15

    In the last decades, China has introduced a set of indicators to guide the Strategic Environmental Assessment (SEA) practice. The most recent indicator system proposed in 2009 is based on sector-specific guidelines and it found its justification in past negative experiences with more general guidelines (from 2003), which were mostly inspired by, or copied from, international experiences. Based on interviews with practitioners, researchers and administrators, we map and analyse the change in the national guidelines. This analysis is based on a description of the indicators that makes it possible to discern different aggregation levels of indicators and then trace the changes occurring under two sets of guidelines. The analysis also reveals the reasons and rationales behind the changes found in the guidelines. This analysis is inspired by implementation theory and a description of some of the more general trends in the development of SEA and other environmental policies in a recent Chinese context. Beside a more top-down, intentional approach specifying indicators for different sectors based on Chinese experiences from the preceding years, another significant change, following the new guidelines, is a more bottom-up approach which gives more discretion to practitioners. This entails a call for practitioners to make decisions on indicators, which involves an interpretation of the ones present in sector guidance. Highlights: • Focusing on the new Chinese national SEA guidelines proposed in 2009 • Mapping and analysing the most recent change in the indicator system • Revealing the reasons and rationales behind the changes found in the new guidelines • A top-down intention specifying indicators for different sectors • A bottom-up effect in giving discretion and interpretation of using indicators.

  13. The case for refining bottom-up methane emission inventories using top-down measurements

    Science.gov (United States)

    Kelly, Bryce F. J.; Iverach, Charlotte P.; Ginty, Elisa; Bashir, Safdar; Lowry, Dave; Fisher, Rebecca E.; France, James L.; Nisbet, Euan G.

    2017-04-01

    Bottom-up global methane emission estimates are important for guiding policy development and mitigation strategies. Such inventories enable rapid and consistent proportioning of emissions by industrial sectors and land use at various scales from city to country to global. There has been limited use of top-down measurements to guide refining emission inventories. Here we compare the EDGAR gridmap data version 4.2 with over 5000 km of daytime ground level mobile atmospheric methane surveys in eastern Australia. The landscapes and industries surveyed include: urban environments, dryland farming, intensive livestock farming (both beef and lamb), irrigation agriculture, open cut and underground coal mining, and coal seam gas production. Daytime mobile methane surveys over a 2-year period show that at the landscape scale there is a high level of repeatability for the mole fraction of methane measured in the ground level atmosphere. Such consistency in the mole fraction of methane indicates that these data can be used as a proxy for flux. A scatter plot of the EDGAR emission gridmap Log[ton substance / 0.1 degree x 0.1 degree / year] versus the median mole fraction of methane / 0.1 degree x 0.1 degree in the ground level atmosphere highlights that the extent of elevated methane emissions associated with coal mining in the Hunter coalfields, which covers an area of 56 km by 24 km, has been under-represented in the EDGAR input data. Our results also show that methane emissions from country towns (population poor information on the extent of urban gas leaks. Given the uncertainties associated with the base land use and industry data for each country, we generalise the Australian observations to the global inventory with caution. The extensive comparison of top-down measurements versus the EDGAR version 4.2 methane gridmaps highlights the need for adjustments to the base resource data and/or the emission factors applied for coal mining, especially emissions from underground

  14. Merging Bottom-Up with Top-Down: Continuous Lamellar Networks and Block Copolymer Lithography

    Science.gov (United States)

    Campbell, Ian Patrick

    Block copolymer lithography is an emerging nanopatterning technology with capabilities that may complement and eventually replace those provided by existing optical lithography techniques. This bottom-up process relies on the parallel self-assembly of macromolecules composed of covalently linked, chemically distinct blocks to generate periodic nanostructures. Among the myriad potential morphologies, lamellar structures formed by diblock copolymers with symmetric volume fractions have attracted the most interest as a patterning tool. When confined to thin films and directed to assemble with interfaces perpendicular to the substrate, two-dimensional domains are formed between the free surface and the substrate, and selective removal of a single block creates a nanostructured polymeric template. The substrate exposed between the polymeric features can subsequently be modified through standard top-down microfabrication processes to generate novel nanostructured materials. Despite tremendous progress in our understanding of block copolymer self-assembly, continuous two-dimensional materials have not yet been fabricated via this robust technique, which may enable nanostructured material combinations that cannot be fabricated through bottom-up methods. This thesis aims to study the effects of block copolymer composition and processing on the lamellar network morphology of polystyrene-block-poly(methyl methacrylate) (PS-b-PMMA) and utilize this knowledge to fabricate continuous two-dimensional materials through top-down methods. First, block copolymer composition was varied through homopolymer blending to explore the physical phenomena surrounding lamellar network continuity. After establishing a framework for tuning the continuity, the effects of various processing parameters were explored to engineer the network connectivity via defect annihilation processes. Precisely controlling the connectivity and continuity of lamellar networks through defect engineering and

  15. A combined bottom-up/top-down approach to prepare a sterile injectable nanosuspension.

    Science.gov (United States)

    Hu, Xi; Chen, Xi; Zhang, Ling; Lin, Xia; Zhang, Yu; Tang, Xing; Wang, Yanjiao

    2014-09-10

    To prepare a uniform nanosuspension of strongly hydrophobic riboflavin laurate (RFL) allowing sterile filtration, physical modification (bottom-up) was combined with high-pressure homogenization (top-down) method. Unlike other bottom-up approaches, physical modification with surfactants (TPGS and PL-100) by lyophilization controlled crystallization and compensated for the poor wettability of RFL. On one hand, crystal growth and aggregation during freezing was restricted by a stabilizer-layer adsorbed on the drug surface by hydrophobic interaction. On the other hand, subsequent crystallization of drug in the sublimation process was limited to the interstitial spaces between solvent crystals. After lyophilization, modified drug with a smaller particle size and better wettability was obtained. When adding surfactant solution, water molecules passed between the hydrophilic groups of surface active molecules and activated the polymer chains allowing them to stretch into water. The coarse suspension was crushed into a nanosuspension (MP=162 nm) by high-pressure homogenization. For long term stability, lyophilization was applied again to solidify the nanosuspension (sorbitol as cryoprotectant). A slight crystal growth to about 600 nm was obtained to allow slow release for a sustained effect after muscular administration. Moreover, no paw-licking responses and very slight muscular inflammation demonstrated the excellent biocompatibility of this long-acting RFL injection. Copyright © 2014 Elsevier B.V. All rights reserved.

  16. Dynamic formulation of a top-down and bottom-up merging energy policy model

    International Nuclear Information System (INIS)

    Frei, Christoph W.; Haldi, P.-A.; Sarlos, G.Gerard

    2003-01-01

    The impact of energy policy measures is not restricted to the energy system and should therefore be analysed within an economy-wide framework, while keeping the essential details of the energy sector. The aim of this paper is to present new developments in the field of the consistent evaluation of indicators for the sustainability assessment of energy policy measures. Starting from the static concept of Boehringer (Energy Econ. 20 (1998) 233), this paper shows how the complementarity format can be used in computable general equilibrium (CGE) modelling for a dynamic formulation of bottom-up and top-down approach merging models. While a hybrid approach increases the credibility of CGE models in energy policy analysis by replacing the energy sector generic functional forms with a bottom-up activity analysis based on specific technologies, the endogenous formulation of investment decisions makes an explicit description of evolving specific capital stocks and technology mixes possible. Both features are essential when assessing effects of policy measures that may be affected by structural change--which is typically the case in the long-term assessment of energy policy measures

  17. Painful faces-induced attentional blink modulated by top-down and bottom-up mechanisms

    Directory of Open Access Journals (Sweden)

    Chun eZheng

    2015-06-01

    Full Text Available Pain-related stimuli can capture attention in an automatic (bottom-up or intentional (top-down fashion. Previous studies have examined attentional capture by pain-related information using spatial attention paradigms that involve mainly a bottom-up mechanism. In the current study, we investigated the pain information–induced attentional blink (AB using a rapid serial visual presentation (RSVP task, and compared the effects of task-irrelevant and task-relevant pain distractors. Relationships between accuracy of target identification and individual traits (i.e., empathy and catastrophizing thinking about pain were also examined. The results demonstrated that task-relevant painful faces had a significant pain information–induced AB effect, whereas task-irrelevant faces a near-significant trend of this effect, supporting the notion that pain-related stimuli can influence the temporal dynamics of attention. Furthermore, we found a significant negative correlation between response accuracy and pain catastrophizing score in task-relevant trials. These findings suggest that active scanning of environmental information related to pain produces greater deficits in cognition than does unintentional attention toward pain, which may represent the different ways in which healthy individuals and patients with chronic pain process pain-relevant information. These results may provide insight into the understanding of maladaptive attentional processing in patients with chronic pain.

  18. The Early Anthropogenic Hypothesis: Top-Down and Bottom-up Evidence

    Science.gov (United States)

    Ruddiman, W. F.

    2014-12-01

    Two complementary lines of evidence support the early anthropogenic hypothesis. Top-down evidence comes from comparing Holocene greenhouse-gas trends with those during equivalent intervals of previous interglaciations. The increases in CO2 and CH4 during the late Holocene are anomalous compared to the decreasing trends in a stacked average of previous interglaciations, thereby supporting an anthropogenic origin. During interglacial stage 19, the closest Holocene insolation analog, CO2 fell to 245 ppm by the time equivalent to the present, in contrast to the observed pre-industrial rise to 280-285 ppm. The 245-ppm level measured in stage 19 falls at the top of the natural range predicted by the original anthropogenic hypothesis of Ruddiman (2003). Bottom-up evidence comes from a growing list of archeological and other compilations showing major early anthropogenic transformations of Earth's surface. Key examples include: efforts by Dorian Fuller and colleagues mapping the spread of irrigated rice agriculture across southern Asia and its effects on CH4 emissions prior to the industrial era; an additional effort by Fuller showing the spread of methane-emitting domesticated livestock across Asia and Africa (coincident with the spread of fertile crescent livestock across Europe); historical compilations by Jed Kaplan and colleagues documenting very high early per-capita forest clearance in Europe, thus underpinning simulations of extensive pre-industrial clearance and large CO2 emissions; and wide-ranging studies by Erle Ellis and colleagues of early anthropogenic land transformations in China and elsewhere.

  19. The Comparative Effect of Top-down Processing and Bottom-up Processing through TBLT on Extrovert and Introvert EFL

    Directory of Open Access Journals (Sweden)

    Pezhman Nourzad Haradasht

    2013-09-01

    Full Text Available This research seeks to examine the effect of two models of reading comprehension, namely top-down and bottom-up processing, on the reading comprehension of extrovert and introvert EFL learners’ reading comprehension. To do this, 120 learners out of a total number of 170 intermediate learners being educated at Iran Mehr English Language School were selected all taking a PET (Preliminary English Test first for homogenization prior to the study. They also answered the Eysenck Personality Inventory (EPI which in turn categorized them into two subgroups within each reading models consisting of introverts and extroverts. All in all, there were four subgroups: 30 introverts and 30 extroverts undergoing the top-down processing treatment, and 30 introverts and 30 extroverts experiencing the bottom-up processing treatment. The aforementioned PET was administered as the post test of the study after each group was exposed to the treatment for 18 sessions in six weeks. After the instructions finished, the mean scores of all four groups on this post test were computed and a two-way ANOVA was run to test all the four hypotheses raise in this study. the results showed that while learners generally benefitted more from the bottom-up processing setting compared  to the top-down processing one, the extrovert group was better off receiving top-down instruction. Furthermore, introverts outperformed extroverts in bottom-up group; yet between the two personalities subgroups in the top-down setting no difference was seen. A predictable pattern of benefitting from teaching procedures could not be drawn for introverts as in both top-down and bottom-up settings, they benefitted more than extroverts.

  20. NEMO. Netherlands Energy demand MOdel. A top-down model based on bottom-up information

    International Nuclear Information System (INIS)

    Koopmans, C.C.; Te Velde, D.W.; Groot, W.; Hendriks, J.H.A.

    1999-06-01

    The title model links energy use to other production factors, (physical) production, energy prices, technological trends and government policies. It uses a 'putty-semiputty' vintage production structure, in which new investments, adaptations to existing capital goods (retrofit) and 'good-housekeeping' are discerned. Price elasticities are relatively large in the long term and small in the short term. Most predictions of energy use are based on either econometric models or on 'bottom-up information', i.e. disaggregated lists of technical possibilities for and costs of saving energy. Typically, one predicts more energy-efficiency improvements using bottom-up information than using econometric ('top-down') models. We bridged this so-called 'energy-efficiency gap' by designing our macro/meso model NEMO in such a way that we can use bottom-up (micro) information to estimate most model parameters. In our view, reflected in NEMO, the energy-efficiency gap arises for two reasons. The first is that firms and households use a fairly high discount rate of 15% when evaluating the profitability of energy-efficiency improvements. The second is that our bottom-up information ('ICARUS') for most economic sectors does not (as NEMO does) take account of the fact that implementation of new, energy-efficient technology in capital stock takes place only gradually. Parameter estimates for 19 sectors point at a long-term technological energy efficiency improvement trend in Netherlands final energy use of 0.8% per year. The long-term price elasticity is estimated to be 0.29. These values are comparable to other studies based on time series data. Simulations of the effects of the oil price shocks in the seventies and the subsequent fall of oil prices show that the NEMO's price elasticities are consistent with historical data. However, the present pace at which new technologies become available (reflected in NEMO) appears to be lower than in the seventies and eighties. This suggests that it

  1. Effects of pollutants on bottom-up and top-down processes in insect-plant interactions

    International Nuclear Information System (INIS)

    Butler, Casey D.; Trumble, John T.

    2008-01-01

    Bottom-up (host plant quality) and top-down (natural enemies) forces both influence the fitness and population dynamics of herbivores. However, the impact of pollutants acting on these forces has not been examined, which prompted us to review the literature to test hypotheses regarding this area of research. A comprehensive literature search found 126 references which examined fitness components and population dynamics of 203 insect herbivores. One hundred and fifty-three of the 203 herbivores (75.4%) had fitness impacted due to bottom-up factors in polluted environments. In contrast, only 20 of the 203 (9.9%) had fitness significantly impacted due to top-down factors in polluted environments. The paucity of results for top-down factors impacting fitness does not necessarily mean that top-down factors are less important, but rather that fewer studies include natural enemies. We provide a synthesis of available data by pollution type and herbivore guild, and suggest future research to address this issue. - Pollutants can affect insect herbivores through bottom-up and, possibly, top-down processes

  2. Top-down and bottom-up approaches for cost estimating new reactor designs

    International Nuclear Information System (INIS)

    Berbey, P.; Gautier, G.M.; Duflo, D.; Rouyer, J.L.

    2007-01-01

    For several years, Generation-4 designs will be 'pre-conceptual' for the less mature concepts and 'preliminary' for the more mature concepts. In this situation, appropriate data for some of the plant systems may be lacking to develop a bottom-up cost estimate. Therefore, a more global approach, the Top-Down Approach (TDA), is needed to help the designers and decision makers in comparing design options. It utilizes more or less simple models for cost estimating the different parts of a design. TDA cost estimating effort applies to a whole functional element whose cost is approached by similar estimations coming from existing data, ratios and models, for a given range of variation of parameters. Modeling is used when direct analogy is not possible. There are two types of models, global and specific ones. Global models are applied to cost modules related to Code Of Account. Exponential formulae such as Ci = Ai + (Bi x Pi n ) are used when there are cost data for comparable modules in nuclear or other industries. Specific cost models are developed for major specific components of the plant: - process equipment such as reactor vessel, steam generators or large heat exchangers. - buildings, with formulae estimating the construction cost from base cost of m3 of building volume. - systems, when unit costs, cost ratios and models are used, depending on the level of detail of the design. Bottom Up Approach (BUA), which is based on unit prices coming from similar equipment or from manufacturer consulting, is very valuable and gives better cost estimations than TDA when it can be applied, that is at a rather late stage of the design. Both approaches are complementary when some parts of the design are detailed enough to be estimated by BUA, and when BUA results are used to check TDA results and to improve TDA models. This methodology is applied to the HTR (High Temperature Reactor) concept and to an advanced PWR design

  3. Metabolic Network Discovery by Top-Down and Bottom-Up Approaches and Paths for Reconciliation

    Energy Technology Data Exchange (ETDEWEB)

    Çakır, Tunahan, E-mail: tcakir@gyte.edu.tr [Computational Systems Biology Group, Department of Bioengineering, Gebze Technical University (formerly known as Gebze Institute of Technology), Gebze (Turkey); Khatibipour, Mohammad Jafar [Computational Systems Biology Group, Department of Bioengineering, Gebze Technical University (formerly known as Gebze Institute of Technology), Gebze (Turkey); Department of Chemical Engineering, Gebze Technical University (formerly known as Gebze Institute of Technology), Gebze (Turkey)

    2014-12-03

    The primary focus in the network-centric analysis of cellular metabolism by systems biology approaches is to identify the active metabolic network for the condition of interest. Two major approaches are available for the discovery of the condition-specific metabolic networks. One approach starts from genome-scale metabolic networks, which cover all possible reactions known to occur in the related organism in a condition-independent manner, and applies methods such as the optimization-based Flux-Balance Analysis to elucidate the active network. The other approach starts from the condition-specific metabolome data, and processes the data with statistical or optimization-based methods to extract information content of the data such that the active network is inferred. These approaches, termed bottom-up and top-down, respectively, are currently employed independently. However, considering that both approaches have the same goal, they can both benefit from each other paving the way for the novel integrative analysis methods of metabolome data- and flux-analysis approaches in the post-genomic era. This study reviews the strengths of constraint-based analysis and network inference methods reported in the metabolic systems biology field; then elaborates on the potential paths to reconcile the two approaches to shed better light on how the metabolism functions.

  4. Metabolic Network Discovery by Top-Down and Bottom-Up Approaches and Paths for Reconciliation

    International Nuclear Information System (INIS)

    Çakır, Tunahan; Khatibipour, Mohammad Jafar

    2014-01-01

    The primary focus in the network-centric analysis of cellular metabolism by systems biology approaches is to identify the active metabolic network for the condition of interest. Two major approaches are available for the discovery of the condition-specific metabolic networks. One approach starts from genome-scale metabolic networks, which cover all possible reactions known to occur in the related organism in a condition-independent manner, and applies methods such as the optimization-based Flux-Balance Analysis to elucidate the active network. The other approach starts from the condition-specific metabolome data, and processes the data with statistical or optimization-based methods to extract information content of the data such that the active network is inferred. These approaches, termed bottom-up and top-down, respectively, are currently employed independently. However, considering that both approaches have the same goal, they can both benefit from each other paving the way for the novel integrative analysis methods of metabolome data- and flux-analysis approaches in the post-genomic era. This study reviews the strengths of constraint-based analysis and network inference methods reported in the metabolic systems biology field; then elaborates on the potential paths to reconcile the two approaches to shed better light on how the metabolism functions.

  5. The Interaction of Top-Down and Bottom-Up Statistics in the Resolution of Syntactic Category Ambiguity

    Science.gov (United States)

    Gibson, Edward

    2006-01-01

    This paper investigates how people resolve syntactic category ambiguities when comprehending sentences. It is proposed that people combine: (a) context-dependent syntactic expectations (top-down statistical information) and (b) context-independent lexical-category frequencies of words (bottom-up statistical information) in order to resolve…

  6. Assessing the Gap Between Top-down and Bottom-up Measured Methane Emissions in Indianapolis, IN.

    Science.gov (United States)

    Prasad, K.; Lamb, B. K.; Cambaliza, M. O. L.; Shepson, P. B.; Stirm, B. H.; Salmon, O. E.; Lavoie, T. N.; Lauvaux, T.; Ferrara, T.; Howard, T.; Edburg, S. L.; Whetstone, J. R.

    2014-12-01

    Releases of methane (CH4) from the natural gas supply chain in the United States account for approximately 30% of the total US CH4 emissions. However, there continues to be large questions regarding the accuracy of current emission inventories for methane emissions from natural gas usage. In this paper, we describe results from top-down and bottom-up measurements of methane emissions from the large isolated city of Indianapolis. The top-down results are based on aircraft mass balance and tower based inverse modeling methods, while the bottom-up results are based on direct component sampling at metering and regulating stations, surface enclosure measurements of surveyed pipeline leaks, and tracer/modeling methods for other urban sources. Mobile mapping of methane urban concentrations was also used to identify significant sources and to show an urban-wide low level enhancement of methane levels. The residual difference between top-down and bottom-up measured emissions is large and cannot be fully explained in terms of the uncertainties in top-down and bottom-up emission measurements and estimates. Thus, the residual appears to be, at least partly, attributed to a significant wide-spread diffusive source. Analyses are included to estimate the size and nature of this diffusive source.

  7. The landscape of fear: The missing link to understand top-down and bottom-up controls of prey abundance?

    Science.gov (United States)

    Identifying factors that may be responsible for affecting and possibly regulating the size of animal populations is a cornerstone in understanding population ecology. The main factors that are thought to influence population size are either resources (bottom-up), predation, (top-down), or interspec...

  8. Reconciling Top-Down and Bottom-Up Estimates of Oil and Gas Methane Emissions in the Barnett Shale

    Science.gov (United States)

    Hamburg, S.

    2015-12-01

    Top-down approaches that use aircraft, tower, or satellite-based measurements of well-mixed air to quantify regional methane emissions have typically estimated higher emissions from the natural gas supply chain when compared to bottom-up inventories. A coordinated research campaign in October 2013 used simultaneous top-down and bottom-up approaches to quantify total and fossil methane emissions in the Barnett Shale region of Texas. Research teams have published individual results including aircraft mass-balance estimates of regional emissions and a bottom-up, 25-county region spatially-resolved inventory. This work synthesizes data from the campaign to directly compare top-down and bottom-up estimates. A new analytical approach uses statistical estimators to integrate facility emission rate distributions from unbiased and targeted high emission site datasets, which more rigorously incorporates the fat-tail of skewed distributions to estimate regional emissions of well pads, compressor stations, and processing plants. The updated spatially-resolved inventory was used to estimate total and fossil methane emissions from spatial domains that match seven individual aircraft mass balance flights. Source apportionment of top-down emissions between fossil and biogenic methane was corroborated with two independent analyses of methane and ethane ratios. Reconciling top-down and bottom-up estimates of fossil methane emissions leads to more accurate assessment of natural gas supply chain emission rates and the relative contribution of high emission sites. These results increase our confidence in our understanding of the climate impacts of natural gas relative to more carbon-intensive fossil fuels and the potential effectiveness of mitigation strategies.

  9. Top-down or bottom-up: Contrasting perspectives on psychiatric diagnoses

    Directory of Open Access Journals (Sweden)

    Willem MA Verhoeven

    2008-09-01

    Full Text Available Willem MA Verhoeven1,2, Siegfried Tuinier1, Ineke van der Burgt31Vincent van Gogh Institute for Psychiatry, Venray, The Netherlands; 2Department of Psychiatry, Erasmus University Medical Centre, Rotterdam, The Netherlands; 3Department of Human Genetics, Radboud University Medical Centre, Nijmegen, The NetherlandsAbstract: Clinical psychiatry is confronted with the expanding knowledge of medical genetics. Most of the research into the genetic underpinnings of major mental disorders as described in the categorical taxonomies, however, did reveal linkage with a variety of chromosomes. This heterogeneity of results is most probably due to the assumption that the nosological categories as used in these studies are disease entities with clear boundaries. If the reverse way of looking, the so-called bottom-up approach, is applied, it becomes clear that genetic abnormalities are in most cases not associated with a single psychiatric disorder but with a certain probability to develop a variety of aspecific psychiatric symptoms. The adequacy of the categorical taxonomy, the so-called top-down approach, seems to be inversely related to the amount of empirical etiological data. This is illustrated by four rather prevalent genetic syndromes, fragile X syndrome, Prader-Willi syndrome, 22q11 deletion syndrome, and Noonan syndrome, as well as by some cases with rare chromosomal abnormalities. From these examples, it becomes clear that psychotic symptoms as well as mood, anxiety, and autistic features can be found in a great variety of different genetic syndromes. A psychiatric phenotype exists, but comprises, apart from the chance to present several psychiatric symptoms, all elements from developmental, neurocognitive, and physical characteristics.Keywords: genetic disorders, psychiatric symptoms, phenotype, mental disorders

  10. Pharmacy-based statewide naloxone distribution: A novel "top-down, bottom-up" approach.

    Science.gov (United States)

    Morton, Kate J; Harrand, Brianna; Floyd, Carly Cloud; Schaefer, Craig; Acosta, Julie; Logan, Bridget Claire; Clark, Karen

    To highlight New Mexico's multifaceted approach to widespread pharmacy naloxone distribution and to share the interventions as a tool for improving pharmacy-based naloxone practices in other states. New Mexico had the second highest drug overdose death rate in 2014 of which 53% were related to prescription opioids. Opioid overdose death is preventable through the use of naloxone, a safe and effective medication that reverses the effects of prescription opioids and heroin. Pharmacists can play an important role in providing naloxone to individuals who use prescription opioids. Not applicable. Not applicable. A multifaceted approach was utilized in New Mexico from the top down with legislative passage of provisions for a statewide standing order and New Mexico Department of Health support for pharmacy-based naloxone delivery. A bottom up approach was also initiated with the development and implementation of a training program for pharmacists and pharmacy technicians. Naloxone Medicaid claims were used to illustrate statewide distribution and utilization of the pharmacist statewide standing order for naloxone. Percent of pharmacies dispensing naloxone in each county were calculated. Trained pharmacy staff completed a program evaluation form. Questions about quality of instruction and ability of trainer to meet stated objectives were rated on a Likert scale. There were 808 naloxone Medicaid claims from 100 outpatient pharmacies during the first half of 2016, a 9-fold increase over 2014. The "A Dose of R x eality" training program evaluation indicated that participants felt the training was free from bias and met all stated objectives (4 out of 4 on Likert scale). A multi-pronged approach coupling state and community collaboration was successful in overcoming barriers and challenges associated with pharmacy naloxone distribution and ensured its success as an effective avenue for naloxone acquisition in urban and rural communities. Copyright © 2017 American Pharmacists

  11. Linking electricity prices and costs in bottom-up top-down coupling under changing market environments

    OpenAIRE

    Maire, Sophie

    2016-01-01

    Electricity market liberalization is altering pricing mechanisms in wholesale electricity markets, which will affect the effectiveness of climate and energy policies. Models used to simulate such policies must be responsive to pricing rules. We show how this can be done and simulate a tightening of climate and energy policies. We use a soft-coupled framework composed of a top-down dynamic computable general equilibrium model and a bottom-up dynamic electricity supply model. The first simulate...

  12. Benchmarking energy scenarios for China: perspectives from top-down, economic and bottom-up, technical modelling

    DEFF Research Database (Denmark)

    This study uses a soft-linking methodology to harmonise two complex global top-down and bottom-up models with a regional China focus. The baseline follows the GDP and demographic trends of the Shared Socio-economic Pathways (SSP2) scenario, down-scaled for China, while the carbon tax scenario fol......-specific modelling results further. These new sub-regional China features can now be used for a more detailed analysis of China's regional developments in a global context....

  13. Grain size engineering of bcc refractory metals: Top-down and bottom-up-Application to tungsten

    International Nuclear Information System (INIS)

    Kecskes, L.J.; Cho, K.C.; Dowding, R.J.; Schuster, B.E.; Valiev, R.Z.; Wei, Q.

    2007-01-01

    We have used two general methodologies for the production of ultrafine grained (UFG) and nanocrystalline (NC) tungsten (W) metal samples: top-down and bottom-up. In the first, Equal channel angular extrusion (ECAE), coupled with warm rolling has been used to fabricate UFG W, and high pressure torsion (HPT) was used to fabricate NC W. We demonstrate an abrupt shift in the deformation mechanism, particularly under dynamic compressive loading, in UFG and NC W. This novel deformation mechanism, a dramatic transition from a uniform deformation mode to that of localized shearing, is shared by other UFG and NC body-centerd cubic (BCC) metals. We have also conducted a series of bottom-up experiments to consolidate powdered UFG W precursors into solid bodies. The bottom-up approach relies on rapid, high-temperature consolidation, specifically designed for UFG and NC W powders. The mechanical property results from the top-down UFG and NC W were used as minimum property benchmarks to guide and design the experimental protocols and parameters for use in the bottom-up procedures. Preliminary results, showing rapid grain growth during the consolidation cycle, did not achieve full density in the W samples. Further development of high-purity W nanopowders and appropriate grain-growth inhibitors (e.g., Zener pinning) will be required to successfully produce bulk-sized UFG and NC W samples

  14. Experience with a top-down versus bottom-up nuclear engineering educational paradigm

    International Nuclear Information System (INIS)

    Harms, A.A.

    1991-01-01

    Nuclear engineering courses are generally taught from a top-down pedagogical perspective; i.e., one begins with a body of knowledge drawn from advanced nuclear science, engineering, and experience and from this distills a selected part to match the intellectual capacity of the class. This pedagogical approach has evidently been most effect at the graduate level of instruction as evidenced by the ready entry of masters and doctoral students into the professions. A schematic depiction of this approach is suggested and is extended to the undergraduate level of nuclear engineering education

  15. Controlled synthesis of organic single-crystalline nanowires via the synergy approach of the bottom-up/top-down processes.

    Science.gov (United States)

    Zhuo, Ming-Peng; Zhang, Ye-Xin; Li, Zhi-Zhou; Shi, Ying-Li; Wang, Xue-Dong; Liao, Liang-Sheng

    2018-03-15

    The controlled fabrication of organic single-crystalline nanowires (OSCNWs) with a uniform diameter in the nanoscale via the bottom-up approach, which is just based on weak intermolecular interaction, is a great challenge. Herein, we utilize the synergy approach of the bottom-up and the top-down processes to fabricate OSCNWs with diameters of 120 ± 10 nm through stepwise evolution processes. Specifically, the evolution processes vary from the self-assembled organic micro-rods with a quadrangular pyramid-like end-structure bounded with {111}s and {11-1}s crystal planes to the "top-down" synthesized organic micro-rods with the flat cross-sectional {002}s plane, to the organic micro-tubes with a wall thickness of ∼115 nm, and finally to the organic nanowires. Notably, the anisotropic etching process caused by the protic solvent molecules (such as ethanol) is crucial for the evolution of the morphology throughout the whole top-down process. Therefore, our demonstration opens a new avenue for the controlled-fabrication of organic nanowires, and also contributes to the development of nanowire-based organic optoelectronics such as organic nanowire lasers.

  16. Bottom-up and top-down attentional contributions to the size congruity effect.

    Science.gov (United States)

    Sobel, Kenith V; Puri, Amrita M; Faulkenberry, Thomas J

    2016-07-01

    The size congruity effect refers to the interaction between the numerical and physical (i.e., font) sizes of digits in a numerical (or physical) magnitude selection task. Although various accounts of the size congruity effect have attributed this interaction to either an early representational stage or a late decision stage, only Risko, Maloney, and Fugelsang (Attention, Perception, & Psychophysics, 75, 1137-1147, 2013) have asserted a central role for attention. In the present study, we used a visual search paradigm to further study the role of attention in the size congruity effect. In Experiments 1 and 2, we showed that manipulating top-down attention (via the task instructions) had a significant impact on the size congruity effect. The interaction between numerical and physical size was larger for numerical size comparison (Exp. 1) than for physical size comparison (Exp. 2). In the remaining experiments, we boosted the feature salience by using a unique target color (Exp. 3) or by increasing the display density by using three-digit numerals (Exps. 4 and 5). As expected, a color singleton target abolished the size congruity effect. Searching for three-digit targets based on numerical size (Exp. 4) resulted in a large size congruity effect, but search based on physical size (Exp. 5) abolished the effect. Our results reveal a substantial role for top-down attention in the size congruity effect, which we interpreted as support for a shared-decision account.

  17. A fusion of top-down and bottom-up modeling techniques to constrain regional scale carbon budgets

    Science.gov (United States)

    Goeckede, M.; Turner, D. P.; Michalak, A. M.; Vickers, D.; Law, B. E.

    2009-12-01

    The effort to constrain regional scale carbon budgets benefits from assimilating as many high quality data sources as possible in order to reduce uncertainties. Two of the most common approaches used in this field, bottom-up and top-down techniques, both have their strengths and weaknesses, and partly build on very different sources of information to train, drive, and validate the models. Within the context of the ORCA2 project, we follow both bottom-up and top-down modeling strategies with the ultimate objective of reconciling their surface flux estimates. The ORCA2 top-down component builds on a coupled WRF-STILT transport module that resolves the footprint function of a CO2 concentration measurement in high temporal and spatial resolution. Datasets involved in the current setup comprise GDAS meteorology, remote sensing products, VULCAN fossil fuel inventories, boundary conditions from CarbonTracker, and high-accuracy time series of atmospheric CO2 concentrations. Surface fluxes of CO2 are normally provided through a simple diagnostic model which is optimized against atmospheric observations. For the present study, we replaced the simple model with fluxes generated by an advanced bottom-up process model, Biome-BGC, which uses state-of-the-art algorithms to resolve plant-physiological processes, and 'grow' a biosphere based on biogeochemical conditions and climate history. This approach provides a more realistic description of biomass and nutrient pools than is the case for the simple model. The process model ingests various remote sensing data sources as well as high-resolution reanalysis meteorology, and can be trained against biometric inventories and eddy-covariance data. Linking the bottom-up flux fields to the atmospheric CO2 concentrations through the transport module allows evaluating the spatial representativeness of the BGC flux fields, and in that way assimilates more of the available information than either of the individual modeling techniques alone

  18. Simple rules describe bottom-up and top-down control in food webs with alternative energy pathways.

    Science.gov (United States)

    Wollrab, Sabine; Diehl, Sebastian; De Roos, André M

    2012-09-01

    Many human influences on the world's ecosystems have their largest direct impacts at either the top or the bottom of the food web. To predict their ecosystem-wide consequences we must understand how these impacts propagate. A long-standing, but so far elusive, problem in this endeavour is how to reduce food web complexity to a mathematically tractable, but empirically relevant system. Simplification to main energy channels linking primary producers to top consumers has been recently advocated. Following this approach, we propose a general framework for the analysis of bottom-up and top-down forcing of ecosystems by reducing food webs to two energy pathways originating from a limiting resource shared by competing guilds of primary producers (e.g. edible vs. defended plants). Exploring dynamical models of such webs we find that their equilibrium responses to nutrient enrichment and top consumer harvesting are determined by only two easily measurable topological properties: the lengths of the component food chains (odd-odd, odd-even, or even-even) and presence vs. absence of a generalist top consumer reconnecting the two pathways (yielding looped vs. branched webs). Many results generalise to other looped or branched web structures and the model can be easily adapted to include a detrital pathway. © 2012 Blackwell Publishing Ltd/CNRS.

  19. Sponge communities on Caribbean coral reefs are structured by factors that are top-down, not bottom-up.

    Science.gov (United States)

    Pawlik, Joseph R; Loh, Tse-Lynn; McMurray, Steven E; Finelli, Christopher M

    2013-01-01

    Caribbean coral reefs have been transformed in the past few decades with the demise of reef-building corals, and sponges are now the dominant habitat-forming organisms on most reefs. Competing hypotheses propose that sponge communities are controlled primarily by predatory fishes (top-down) or by the availability of picoplankton to suspension-feeding sponges (bottom-up). We tested these hypotheses on Conch Reef, off Key Largo, Florida, by placing sponges inside and outside predator-excluding cages at sites with less and more planktonic food availability (15 m vs. 30 m depth). There was no evidence of a bottom-up effect on the growth of any of 5 sponge species, and 2 of 5 species grew more when caged at the shallow site with lower food abundance. There was, however, a strong effect of predation by fishes on sponge species that lacked chemical defenses. Sponges with chemical defenses grew slower than undefended species, demonstrating a resource trade-off between growth and the production of secondary metabolites. Surveys of the benthic community on Conch Reef similarly did not support a bottom-up effect, with higher sponge cover at the shallower depth. We conclude that the structure of sponge communities on Caribbean coral reefs is primarily top-down, and predict that removal of sponge predators by overfishing will shift communities toward faster-growing, undefended species that better compete for space with threatened reef-building corals.

  20. Sponge communities on Caribbean coral reefs are structured by factors that are top-down, not bottom-up.

    Directory of Open Access Journals (Sweden)

    Joseph R Pawlik

    Full Text Available Caribbean coral reefs have been transformed in the past few decades with the demise of reef-building corals, and sponges are now the dominant habitat-forming organisms on most reefs. Competing hypotheses propose that sponge communities are controlled primarily by predatory fishes (top-down or by the availability of picoplankton to suspension-feeding sponges (bottom-up. We tested these hypotheses on Conch Reef, off Key Largo, Florida, by placing sponges inside and outside predator-excluding cages at sites with less and more planktonic food availability (15 m vs. 30 m depth. There was no evidence of a bottom-up effect on the growth of any of 5 sponge species, and 2 of 5 species grew more when caged at the shallow site with lower food abundance. There was, however, a strong effect of predation by fishes on sponge species that lacked chemical defenses. Sponges with chemical defenses grew slower than undefended species, demonstrating a resource trade-off between growth and the production of secondary metabolites. Surveys of the benthic community on Conch Reef similarly did not support a bottom-up effect, with higher sponge cover at the shallower depth. We conclude that the structure of sponge communities on Caribbean coral reefs is primarily top-down, and predict that removal of sponge predators by overfishing will shift communities toward faster-growing, undefended species that better compete for space with threatened reef-building corals.

  1. Comparison of the top-down and bottom-up approach to fabricate nanowire-based Silicon/Germanium heterostructures

    International Nuclear Information System (INIS)

    Wolfsteller, A.; Geyer, N.; Nguyen-Duc, T.-K.; Das Kanungo, P.; Zakharov, N.D.; Reiche, M.; Erfurth, W.; Blumtritt, H.; Werner, P.; Goesele, U.

    2010-01-01

    Silicon nanowires (NWs) and vertical nanowire-based Si/Ge heterostructures are expected to be building blocks for future devices, e.g. field-effect transistors or thermoelectric elements. In principle two approaches can be applied to synthesise these NWs: the 'bottom-up' and the 'top-down' approach. The most common method for the former is the vapour-liquid-solid (VLS) mechanism which can also be applied to grow NWs by molecular beam epitaxy (MBE). Although MBE allows a precise growth control under highly reproducible conditions, the general nature of the growth process via a eutectic droplet prevents the synthesis of heterostructures with sharp interfaces and high Ge concentrations. We compare the VLS NW growth with two different top-down methods: The first is a combination of colloidal lithography and metal-assisted wet chemical etching, which is an inexpensive and fast method and results in large arrays of homogenous Si NWs with adjustable diameters down to 50 nm. The second top-down method combines the growth of Si/Ge superlattices by MBE with electron beam lithography and reactive ion etching. Again, large and homogeneous arrays of NWs were created, this time with a diameter of 40 nm and the Si/Ge superlattice inside.

  2. Temperature regulation of marine heterotrophic prokaryotes increases latitudinally as a breach between bottom-up and top-down controls

    KAUST Repository

    Moran, Xose Anxelu G.

    2017-04-19

    Planktonic heterotrophic prokaryotes make up the largest living biomass and process most organic matter in the ocean. Determining when and where the biomass and activity of heterotrophic prokaryotes are controlled by resource availability (bottom-up), predation and viral lysis (top-down) or temperature will help in future carbon cycling predictions. We conducted an extensive survey across subtropical and tropical waters of the Atlantic, Indian and Pacific Oceans during the Malaspina 2010 Global Circumnavigation Expedition and assessed indices for these three types of controls at 109 stations (mostly from the surface to 4000 m depth). Temperature control was approached by the apparent activation energy in eV (ranging from 0.46 to 3.41), bottom-up control by the slope of the log-log relationship between biomass and production rate (ranging from -0.12 to 1.09) and top-down control by an index that considers the relative abundances of heterotrophic nanoflagellates and viruses (ranging from 0.82 to 4.83). We conclude that temperature becomes dominant (i.e. activation energy >1.5 eV) within a narrow window of intermediate values of bottom-up (0.3-0.6) and top-down 0.8-1.2) controls. A pervasive latitudinal pattern of decreasing temperature regulation towards the Equator, regardless of the oceanic basin, suggests that the impact of global warming on marine microbes and their biogeochemical function will be more intense at higher latitudes. Our analysis predicts that 1°C ocean warming will result in increased biomass of heterotrophic prokaryoplankton only in waters with <26°C of mean annual surface temperature. This article is protected by copyright. All rights reserved.

  3. Salient region detection by fusing bottom-up and top-down features extracted from a single image.

    Science.gov (United States)

    Tian, Huawei; Fang, Yuming; Zhao, Yao; Lin, Weisi; Ni, Rongrong; Zhu, Zhenfeng

    2014-10-01

    Recently, some global contrast-based salient region detection models have been proposed based on only the low-level feature of color. It is necessary to consider both color and orientation features to overcome their limitations, and thus improve the performance of salient region detection for images with low-contrast in color and high-contrast in orientation. In addition, the existing fusion methods for different feature maps, like the simple averaging method and the selective method, are not effective sufficiently. To overcome these limitations of existing salient region detection models, we propose a novel salient region model based on the bottom-up and top-down mechanisms: the color contrast and orientation contrast are adopted to calculate the bottom-up feature maps, while the top-down cue of depth-from-focus from the same single image is used to guide the generation of final salient regions, since depth-from-focus reflects the photographer's preference and knowledge of the task. A more general and effective fusion method is designed to combine the bottom-up feature maps. According to the degree-of-scattering and eccentricities of feature maps, the proposed fusion method can assign adaptive weights to different feature maps to reflect the confidence level of each feature map. The depth-from-focus of the image as a significant top-down feature for visual attention in the image is used to guide the salient regions during the fusion process; with its aid, the proposed fusion method can filter out the background and highlight salient regions for the image. Experimental results show that the proposed model outperforms the state-of-the-art models on three public available data sets.

  4. Incentives for Collaborative Governance: Top-Down and Bottom-Up Initiatives in the Swedish Mountain Region

    Directory of Open Access Journals (Sweden)

    Katarina Eckerberg

    2015-08-01

    Full Text Available Governance collaborations between public and private partners are increasingly used to promote sustainable mountain development, yet information is limited on their nature and precise extent. This article analyzes collaboration on environment and natural resource management in Swedish mountain communities to critically assess the kinds of issues these efforts address, how they evolve, who leads them, and what functional patterns they exhibit based on Margerum's (2008 typology of action, organizational, and policy collaboration. Based on official documents, interviews, and the records of 245 collaborative projects, we explore the role of the state, how perceptions of policy failure may inspire collaboration, and the opportunities that European Union funds have created. Bottom-up collaborations, most of which are relatively recent, usually have an action and sometimes an organizational function. Top-down collaborations, however, are usually organizational or policy oriented. Our findings suggest that top-down and bottom-up collaborations are complementary in situations with considerable conflict over time and where public policies have partly failed, such as for nature protection and reindeer grazing. In less contested areas, such as rural development, improving tracks and access, recreation, and fishing, there is more bottom-up, action-oriented collaboration. State support, especially in the form of funding, is central to explaining the emergence of bottom-up action collaboration. Our findings show that the state both initiates and coordinates policy networks and retains a great deal of power over the nature and functioning of collaborative governance. A practical consequence is that there is great overlap—aggravated by sectorized approaches—that creates a heavy workload for some regional partners.

  5. Bottom-up nutrient and top-down fish impacts on insect-mediated mercury flux from aquatic ecosystems.

    Science.gov (United States)

    Jones, Taylor A; Chumchal, Matthew M; Drenner, Ray W; Timmins, Gabrielle N; Nowlin, Weston H

    2013-03-01

    Methyl mercury (MeHg) is one of the most hazardous contaminants in the environment, adversely affecting the health of wildlife and humans. Recent studies have demonstrated that aquatic insects biotransport MeHg and other contaminants to terrestrial consumers, but the factors that regulate the flux of MeHg out of aquatic ecosystems via emergent insects have not been studied. The authors used experimental mesocosms to test the hypothesis that insect emergence and the associated flux of MeHg from aquatic to terrestrial ecosystems is affected by both bottom-up nutrient effects and top-down fish consumer effects. In the present study, nutrient addition led to an increase in MeHg flux primarily by enhancing the biomass of emerging insects whose tissues were contaminated with MeHg, whereas fish decreased MeHg flux primarily by reducing the biomass of emerging insects. Furthermore, the authors found that these factors are interdependent such that the effects of nutrients are more pronounced when fish are absent, and the effects of fish are more pronounced when nutrient concentrations are high. The present study is the first to demonstrate that the flux of MeHg from aquatic to terrestrial ecosystems is strongly enhanced by bottom-up nutrient effects and diminished by top-down consumer effects. Copyright © 2012 SETAC.

  6. Venom Proteomics of Indonesian King Cobra, Ophiophagus hannah: Integrating Top-Down and Bottom-Up Approaches.

    Science.gov (United States)

    Petras, Daniel; Heiss, Paul; Süssmuth, Roderich D; Calvete, Juan J

    2015-06-05

    We report on the first application of top-down mass spectrometry in snake venomics. De novo sequence tags generated by, and ProSight Lite supported analysis of, combined collisional based dissotiations (CID and HCD) recorded in a hybrid LTQ Orbitrap instrument in data-dependent mode identified a number of proteins from different toxin families, namely, 11 three-finger toxins (7-7.9 kDa), a Kunitz-type inhibitor (6.3 kDa), ohanin (11.9 kDa), a novel phospholipase A2 molecule (13.8 kDa), and the cysteine-rich secretory protein (CRISP) ophanin (25 kDa) from Indonesian king cobra venom. Complementary bottom-up MS/MS analyses contributed to the completion of a locus-resolved venom phenotypic map for Ophiophagus hannah, the world's longest venomous snake and a species of medical concern across its wide distribution range in forests from India to Southeast Asia. Its venom composition, comprising 32-35 proteins/peptides from 10 protein families, is dominated by α-neurotoxins and convincingly explains the main neurotoxic effects of human envenoming caused by king cobra bite. The integration of efficient chromatographic separation of the venom's components and locus-resolved toxin identification through top-down and bottom-up MS/MS-based species-specific database searching and de novo sequencing holds promise that the future will be bright for the field of venom research.

  7. Orchestrated structure evolution: accelerating direct-write nanomanufacturing by combining top-down patterning with bottom-up growth

    Energy Technology Data Exchange (ETDEWEB)

    Kitayaporn, Sathana; Baneyx, Francois; Schwartz, Daniel T [Department of Chemical Engineering, University of Washington, Seattle, WA 98195-1750 (United States); Hoo, Ji Hao; Boehringer, Karl F, E-mail: dts@uw.edu [Department of Electrical Engineering, University of Washington, Seattle, WA 98195-1750 (United States)

    2010-05-14

    Direct-write nanomanufacturing with scanning beams and probes is flexible and can produce high quality products, but it is normally slow and expensive to raster point-by-point over a pattern. We demonstrate the use of an accelerated direct-write nanomanufacturing method called 'orchestrated structure evolution' (OSE), where a direct-write tool patterns a small number of growth 'seeds' that subsequently grow into the final thin film pattern. Through control of seed size and spacing, it is possible to vary the ratio of 'top-down' to 'bottom-up' character of the patterning processes, ranging from conventional top-down raster patterning to nearly pure bottom-up space-filling via seed growth. Electron beam lithography (EBL) and copper electrodeposition were used to demonstrate trade-offs between process time and product quality over nano- to microlength scales. OSE can reduce process times for high-cost EBL patterning by orders of magnitude, at the expense of longer (but inexpensive) copper electrodeposition processing times. We quantify the degradation of pattern quality that accompanies fast OSE patterning by measuring deviations from the desired patterned area and perimeter. We also show that the density of OSE-induced grain boundaries depends upon the seed separation and size. As the seed size is reduced, the uniformity of an OSE film becomes more dependent on details of seed nucleation processes than normally seen for conventionally patterned films.

  8. Bottom-up and top-down human impacts interact to affect a protected coastal Chilean marsh.

    Science.gov (United States)

    Fariña, José M; He, Qiang; Silliman, Brian R; Bertness, Mark D

    2016-03-01

    Many ecosystems, even in protected areas, experience multiple anthropogenic impacts. While anthropogenic modification of bottom-up (e.g., eutrophication) and top-down (e.g., livestock grazing) forcing often co-occurs, whether these factors counteract or have additive or synergistic effects on ecosystems is poorly understood. In a Chilean bio-reserve, we examined the interactive impacts of eutrophication and illegal livestock grazing on plant growth with a 4-yr fertilization by cattle exclusion experiment. Cattle grazing generally decreased plant biomass, but had synergistic, additive, and antagonistic interactions with fertilization in the low, middle, and high marsh zones, respectively. In the low marsh, fertilization increased plant biomass by 112%, cattle grazing decreased it by 96%, and together they decreased plant biomass by 77%. In the middle marsh, fertilization increased plant biomass by 47%, cattle grazing decreased it by 37%, and together they did not affect plant biomass. In the high marsh, fertilization and cattle grazing decreased plant biomass by 81% and 92%, respectively, but together they increased plant biomass by 42%. These interactions were also found to be species specific. Different responses of plants to fertilization and cattle grazing were likely responsible for these variable interactions. Thus, common bottom-up and top-down human impacts can interact in different ways to affect communities even within a single ecosystem. Incorporating this knowledge into conservation actions will improve ecosystem management in a time when ecosystems are increasingly challenged by multiple interacting human impacts.

  9. Top-down and bottom-up aspects of active search in a real-world environment.

    Science.gov (United States)

    Foulsham, Tom; Chapman, Craig; Nasiopoulos, Eleni; Kingstone, Alan

    2014-03-01

    Visual search has been studied intensively in the labouratory, but lab search often differs from search in the real world in many respects. Here, we used a mobile eye tracker to record the gaze of participants engaged in a realistic, active search task. Participants were asked to walk into a mailroom and locate a target mailbox among many similar mailboxes. This procedure allowed control of bottom-up cues (by making the target mailbox more salient; Experiment 1) and top-down instructions (by informing participants about the cue; Experiment 2). The bottom-up salience of the target had no effect on the overall time taken to search for the target, although the salient target was more likely to be fixated and found once it was within the central visual field. Top-down knowledge of target appearance had a larger effect, reducing the need for multiple head and body movements, and meaning that the target was fixated earlier and from further away. Although there remains much to be discovered in complex real-world search, this study demonstrates that principles from visual search in the labouratory influence gaze in natural behaviour, and provides a bridge between these labouratory studies and research examining vision in natural tasks.

  10. Approaches in studying the pharmacology of Chinese Medicine formulas: bottom-up, top-down-and meeting in the middle.

    Science.gov (United States)

    Huang, Tao; Zhong, Linda L D; Lin, Chen-Yuan; Zhao, Ling; Ning, Zi-Wan; Hu, Dong-Dong; Zhang, Man; Tian, Ke; Cheng, Chung-Wah; Bian, Zhao-Xiang

    2018-01-01

    Investigating the pharmacology is key to the modernization of Chinese Medicine (CM) formulas. However, identifying which are the active compound(s) of CM formulas, which biological entities they target, and through which signaling pathway(s) they act to modify disease symptoms, are still difficult tasks for researchers, even when equipped with an arsenal of advanced modern technologies. Multiple approaches, including network pharmacology, pharmaco-genomics, -proteomics, and -metabolomics, have been developed to study the pharmacology of CM formulas. They fall into two general categories in terms of how they tackle a problem: bottom-up and top-down. In this article, we compared these two different approaches in several dimensions by using the case of MaZiRenWan (MZRW, also known as Hemp Seed Pill), a CM herbal formula for functional constipation. Multiple hypotheses are easy to be proposed in the bottom-up approach (e.g. network pharmacology); but these hypotheses are usually false positives and hard to be tested. In contrast, it is hard to suggest hypotheses in the top-down approach (e.g. pharmacometabolomics); however, once a hypothesis is proposed, it is much easier to be tested. Merging of these two approaches could results in a powerful approach, which could be the new paradigm for the pharmacological study of CM formulas.

  11. Assessing Top-Down and Bottom-Up Contributions to Auditory Stream Segregation and Integration With Polyphonic Music

    Directory of Open Access Journals (Sweden)

    Niels R. Disbergen

    2018-03-01

    Full Text Available Polyphonic music listening well exemplifies processes typically involved in daily auditory scene analysis situations, relying on an interactive interplay between bottom-up and top-down processes. Most studies investigating scene analysis have used elementary auditory scenes, however real-world scene analysis is far more complex. In particular, music, contrary to most other natural auditory scenes, can be perceived by either integrating or, under attentive control, segregating sound streams, often carried by different instruments. One of the prominent bottom-up cues contributing to multi-instrument music perception is their timbre difference. In this work, we introduce and validate a novel paradigm designed to investigate, within naturalistic musical auditory scenes, attentive modulation as well as its interaction with bottom-up processes. Two psychophysical experiments are described, employing custom-composed two-voice polyphonic music pieces within a framework implementing a behavioral performance metric to validate listener instructions requiring either integration or segregation of scene elements. In Experiment 1, the listeners' locus of attention was switched between individual instruments or the aggregate (i.e., both instruments together, via a task requiring the detection of temporal modulations (i.e., triplets incorporated within or across instruments. Subjects responded post-stimulus whether triplets were present in the to-be-attended instrument(s. Experiment 2 introduced the bottom-up manipulation by adding a three-level morphing of instrument timbre distance to the attentional framework. The task was designed to be used within neuroimaging paradigms; Experiment 2 was additionally validated behaviorally in the functional Magnetic Resonance Imaging (fMRI environment. Experiment 1 subjects (N = 29, non-musicians completed the task at high levels of accuracy, showing no group differences between any experimental conditions. Nineteen

  12. Assessing Top-Down and Bottom-Up Contributions to Auditory Stream Segregation and Integration With Polyphonic Music.

    Science.gov (United States)

    Disbergen, Niels R; Valente, Giancarlo; Formisano, Elia; Zatorre, Robert J

    2018-01-01

    Polyphonic music listening well exemplifies processes typically involved in daily auditory scene analysis situations, relying on an interactive interplay between bottom-up and top-down processes. Most studies investigating scene analysis have used elementary auditory scenes, however real-world scene analysis is far more complex. In particular, music, contrary to most other natural auditory scenes, can be perceived by either integrating or, under attentive control, segregating sound streams, often carried by different instruments. One of the prominent bottom-up cues contributing to multi-instrument music perception is their timbre difference. In this work, we introduce and validate a novel paradigm designed to investigate, within naturalistic musical auditory scenes, attentive modulation as well as its interaction with bottom-up processes. Two psychophysical experiments are described, employing custom-composed two-voice polyphonic music pieces within a framework implementing a behavioral performance metric to validate listener instructions requiring either integration or segregation of scene elements. In Experiment 1, the listeners' locus of attention was switched between individual instruments or the aggregate (i.e., both instruments together), via a task requiring the detection of temporal modulations (i.e., triplets) incorporated within or across instruments. Subjects responded post-stimulus whether triplets were present in the to-be-attended instrument(s). Experiment 2 introduced the bottom-up manipulation by adding a three-level morphing of instrument timbre distance to the attentional framework. The task was designed to be used within neuroimaging paradigms; Experiment 2 was additionally validated behaviorally in the functional Magnetic Resonance Imaging (fMRI) environment. Experiment 1 subjects ( N = 29, non-musicians) completed the task at high levels of accuracy, showing no group differences between any experimental conditions. Nineteen listeners also

  13. An integrated top-down and bottom-up proteomic approach to characterize the antigen-binding fragment of antibodies.

    Science.gov (United States)

    Dekker, Lennard; Wu, Si; Vanduijn, Martijn; Tolić, Nikolai; Stingl, Christoph; Zhao, Rui; Luider, Theo; Paša-Tolić, Ljiljana

    2014-05-01

    We have previously shown that different individuals exposed to the same antigen produce antibodies with identical mutations in their complementarity determining regions (CDR), suggesting that CDR tryptic peptides can serve as biomarkers for disease diagnosis and prognosis. Complete Fabs derived from disease specific antibodies have even higher potential; they could potentially be used for disease treatment and are required to identify the antigens toward which the antibodies are directed. However, complete Fab sequence characterization via LC-MS analysis of tryptic peptides (i.e. bottom-up) has proven to be impractical for mixtures of antibodies. To tackle this challenge, we have developed an integrated bottom-up and top-down MS approach, employing 2D chromatography coupled with Fourier transform mass spectrometry (FTMS), and applied this approach for full characterization of the variable parts of two pharmaceutical monoclonal antibodies with sensitivity comparable to the bottom-up standard. These efforts represent an essential step toward the identification of disease specific antibodies in patient samples with potentially significant clinical impact. © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  14. Closing the gap? Top-down versus bottom-up projections of China's regional energy use and CO2 emissions

    DEFF Research Database (Denmark)

    Dai, Hancheng; Mischke, Peggy; Xie, Xuxuan

    2016-01-01

    . The study finds that it is beneficial to soft-link complex global models under harmonized assumptions. Although this study fails to "close the gap" between the two models completely, the experiences and insights shared here will be beneficial for researchers and policy makers that are drawing conclusions......As the world's largest CO2 emitter, China is a prominent case study for scenario analysis. This study uses two newly developed global top-down and bottom-up models with a regional China focus to compare China's future energy and CO2 emission pathways toward 2050. By harmonizing the economic...... and demographic trends as well as a carbon tax pathway, we explore how both models respond to these identical exogenous inputs. Then a soft-linking methodology is applied to "narrow the gap" between the results computed by these models. We find for example that without soft-linking, China's baseline CO2 emissions...

  15. Costs of CO2 abatement in Egypt using both bottom-up and top-down approaches

    International Nuclear Information System (INIS)

    El Mahgary, Y.; Ibrahim, A.-F.; Shama, M.A.-F.

    1994-01-01

    Within the frame of UNEP's project on the Methodologies of Determining the Costs of Abatement of GHG emissions, a case study on Egypt was undertaken by the Technical Research Centre of Finland (VTT) in cooperation with the Egyptian Environment Affairs Authority (EEAA), together with an expert team from different Egyptian organizations. Both bottom-up and top-down approaches were used. Several measures/technologies, including energy conservation, fuel switching, use of renewable energy and material replacement, were considered to decrease CO 2 emissions. It was found that most of the measures were cost-effective, as a considerable potential for energy conservation exists in Egypt. The impact of energy conservation measures on the economy of the country was found to be positive using a macroeconomic model. (author)

  16. Sensitivity quantification of airport concrete pavement stress responses associated with top-down and bottom-up cracking

    Directory of Open Access Journals (Sweden)

    Adel Rezaei-Tarahomi

    2017-09-01

    Full Text Available The Federal Aviation Administration’s (FAA’s rigid pavement design standard employs the NIKE3D-FAA software to compute critical pavement responses of concrete airport pavement structures. NIKE3D-FAA is a modification of the original NIKE3D three-dimensional finite element analysis program developed by the Lawrence Livermore National Laboratory (LLNL of the U.S. Department of Energy, and is currently used in the FAA’s FAARFIELD program. This study evaluated the sensitivity of NIKE3D-FAA rigid pavement responses with respect to top-down and bottom-up cracking. The analysis was conducted by positioning a Boeing 777-300ER (B777-300ERaircraft at different locations (interior, corner, and edge of slab as baseline while varying other NIKE3D-FAA inputs, including rigid pavement geometric features, mechanical properties of paving and foundation materials, equivalent temperature gradient and thermal coefficient of Portland Cement Concrete (PCC layers. Several sensitivity charts were developed by examining the sensitivity of critical pavement responses to each input variation. Sensitivity evaluations were performed using a normalized sensitivity index (NSI as the quantitative metric. Using such sensitivity evaluation, the most significant NIKE3D-FAA input parameters for generating an effective synthetic database that will lower computational cost for future modeling developments were identified. Keywords: Sensitivity analysis, Airfield concrete pavement, Finite element analysis, Top down cracking

  17. Bottom-up photonic crystal approach with top-down defect and heterostructure fine-tuning.

    Science.gov (United States)

    Ding, Tao; Song, Kai; Clays, Koen; Tung, Chen-Ho

    2010-03-16

    We combine the most efficient (chemical) approach toward three-dimensional photonic crystals with the most convenient (physical) technique for creating non-close-packed crystalline structures. Self-assembly of colloidal particles in artificial opals is followed by a carefully tuned plasma etching treatment. By covering the resulting top layer of more open structure with original dense opal, embedded defect layers and heterostructures can be conveniently designed for advanced photonic band gap and band edge engineering.

  18. Density- and trait-mediated top-down effects modify bottom-up control of a highly endemic tropical aquatic food web

    Science.gov (United States)

    C. M. Dalton; A. Mokiao-Lee; T. S. Sakihara; M. G. Weber; C. A. Roco; Z. Han; B. Dudley; R. A. MacKenzie; N. G. Hairston Jr.

    2013-01-01

    Benthic invertebrates mediate bottom–up and top–down influences in aquatic food webs, and changes in the abundance or traits of invertebrates can alter the strength of top–down effects. Studies assessing the role of invertebrate abundance and behavior as controls on food web structure are rare at the whole ecosystem scale. Here we use a comparative approach to...

  19. Directed self-assembly of nanorod networks: bringing the top down to the bottom up

    International Nuclear Information System (INIS)

    Einsle, Joshua F; Scheunert, Gunther; Murphy, Antony; Pollard, Robert; Bowman, Robert M; McPhillips, John; Zayats, Anatoly V

    2012-01-01

    Self-assembled electrodeposited nanorod materials have been shown to offer an exciting landscape for a wide array of research ranging from nanophotonics through to biosensing and magnetics. However, until now, the scope for site-specific preparation of the nanorods on wafers has been limited to local area definition. Further there is little or no lateral control of nanorod height. In this work we present a scalable method for controlling the growth of the nanorods in the vertical direction as well as their lateral position. A focused ion beam pre-patterns the Au cathode layer prior to the creation of the anodized aluminium oxide (AAO) template on top. When the pre-patterning is of the same dimension as the pore spacing of the AAO template, lines of single nanorods are successfully grown. Further, for sub-200 nm wide features, a relationship between the nanorod height and distance from the non-patterned cathode can be seen to follow a quadratic growth rate obeying Faraday’s law of electrodeposition. This facilitates lateral control of nanorod height combined with localized growth of the nanorods. (paper)

  20. Directed self-assembly of nanorod networks: bringing the top down to the bottom up.

    Science.gov (United States)

    Einsle, Joshua F; Scheunert, Gunther; Murphy, Antony; McPhillips, John; Zayats, Anatoly V; Pollard, Robert; Bowman, Robert M

    2012-12-21

    Self-assembled electrodeposited nanorod materials have been shown to offer an exciting landscape for a wide array of research ranging from nanophotonics through to biosensing and magnetics. However, until now, the scope for site-specific preparation of the nanorods on wafers has been limited to local area definition. Further there is little or no lateral control of nanorod height. In this work we present a scalable method for controlling the growth of the nanorods in the vertical direction as well as their lateral position. A focused ion beam pre-patterns the Au cathode layer prior to the creation of the anodized aluminium oxide (AAO) template on top. When the pre-patterning is of the same dimension as the pore spacing of the AAO template, lines of single nanorods are successfully grown. Further, for sub-200 nm wide features, a relationship between the nanorod height and distance from the non-patterned cathode can be seen to follow a quadratic growth rate obeying Faraday's law of electrodeposition. This facilitates lateral control of nanorod height combined with localized growth of the nanorods.

  1. Trophic cascades of bottom-up and top-down forcing on nutrients and plankton in the Kattegat, evaluated by modelling

    DEFF Research Database (Denmark)

    Petersen, Marcell Elo; Maar, Marie; Larsen, Janus

    2017-01-01

    The aim of the study was to investigate the relative importance of bottom-up and top-down forcing on trophic cascades in the pelagic food-web and the implications for water quality indicators (summer phytoplankton biomass and winter nutrients) in relation to management. The 3D ecological model....... On annual basis, the system was more bottom-up than top-down controlled. Microzooplankton was found to play an important role in the pelagic food web as mediator of nutrient and energy fluxes. This study demonstrated that the best scenario for improved water quality was a combined reduction in nutrient...

  2. Merging bottom-up and top-down precipitation products using a stochastic error model

    Science.gov (United States)

    Maggioni, Viviana; Massari, Christian; Brocca, Luca; Ciabatta, Luca

    2017-04-01

    Accurate quantitative precipitation estimation is of great importance for water resources management, agricultural planning, and forecasting and monitoring of natural hazards such as flash floods and landslides. In situ observations are limited around the Earth, especially in remote areas (e.g., complex terrain, dense vegetation), but currently available satellite precipitation products are able to provide global precipitation estimates with an accuracy that depends upon many factors (e.g., type of storms, temporal sampling, season etc…). Recently, Brocca et al. (2014) have proposed an alternative approach (i.e., SM2RAIN) that allows to estimate rainfall from space by using satellite soil moisture observations. In contrast with classical satellite precipitation products which sense the cloud properties to retrieve the instantaneous precipitation, this new bottom-up approach makes use of two consecutive soil moisture measurements for obtaining an estimate of the fallen precipitation within the interval between two satellite passes. As a result, the nature of the measurement is different and complementary to the one of classical precipitation products and could provide a different valid perspective to improve current satellite rainfall estimates via appropriate integration between the products (i.e., SM2RAIN plus a classical satellite rainfall product). However, whether SM2RAIN is able or not to improve the performance of any state-of-the-art satellite rainfall product is much dependent upon an adequate quantification and characterization of the relative errors of the products. In this study, the stochastic rainfall error model SREM2D (Hossain et al. 2006) is used for characterizing the retrieval error of both SM2RAIN and a state-of-the-art satellite precipitation product (i.e., 3B42RT). The error characterization serves for an optimal integration between SM2RAIN and 3B42RT for enhancing the capability of the resulting integrated product (i.e. SM2RAIN+3B42RT) in

  3. Bottom-up meets top-down: tailored raspberry-like Fe3O4-Pt nanocrystal superlattices.

    Science.gov (United States)

    Qiu, Fen; Vervuurt, René H J; Verheijen, Marcel A; Zaia, Edmond W; Creel, Erin B; Kim, Youngsang; Urban, Jeffrey J; Bol, Ageeth A

    2018-03-29

    Supported catalysts are widely used in industry and can be optimized by tuning the composition, chemical structure, and interface of the nanoparticle catalyst and oxide support. Here we firstly combine a bottom up colloidal synthesis method with a top down atomic layer deposition (ALD) process to achieve a raspberry-like Pt-decorated Fe3O4 (Fe3O4-Pt) nanoparticle superlattices. This nanocomposite ensures the precision of the catalyst/support interface, improving the catalytic efficiency of the Fe3O4-Pt nanocomposite system. The morphology of the hybrid nanocomposites resulting from different cycles of ALD was monitored by scanning transmission electron microscopy, giving insight into the nucleation and growth mechanism of the ALD process. X-ray photoelectron spectroscopy studies confirm the anticipated electron transfer from Fe3O4 to Pt through the nanocomposite interface. Photocurrent measurement further suggests that Fe3O4 superlattices with controlled decoration of Pt have substantial promise for energy-efficient photoelectrocatalytic oxygen evolution reaction. This work opens a new avenue for designing supported catalyst architectures via precisely controlled decoration of single component superlattices with noble metals.

  4. Bioenergy decision-making of farms in Northern Finland. Combining the bottom-up and top-down perspectives

    International Nuclear Information System (INIS)

    Snaekin, Juha-Pekka; Muilu, Toivo; Pesola, Tuomo

    2010-01-01

    Finnish farmers' role as energy producers is small compared to their role as energy resource owners. Since climate and energy policy in Finland continues favoring large-scale energy visions, additional investment support for agriculture will stay modest. To utilize fully the energy potential in farms, we analyze the farmers' decision-making environment. First, we present an overview of the Finnish energy policy and economy and their effect on farms (the top-down perspective). Then we analyze the drivers behind the bioenergy decisions of farms in general and in the Oulu region, located in Northern Finland (the bottom-up perspective). There is weak policy coherence between national and regional energy efforts. Strong pressure is placed on farmers to improve their business and marketing knowledge, innovation and financial abilities, education level, and networking skills. In the Oulu region, bioenergy forerunners can be divided in three different groups - investors, entrepreneurs and hobbyists - that have different levels of commitment to their energy businesses. This further stresses the importance of getting quality business services from numerous service providers. (author)

  5. Bottom-up control of consumers leads to top-down indirect facilitation of invasive annual herbs in semiarid Chile.

    Science.gov (United States)

    Madrigal, Jaime; Kelt, Douglas A; Meserve, Peter L; Gutierrez, Julio R; Squeo, Francisco A

    2011-02-01

    The abundance of exotic plants is thought to be limited by competition with resident species (including plants and generalist herbivores). In contrast, observations in semiarid Chile suggest that a native generalist rodent, the degu (Octodon degus), may be facilitating the expansion of exotic annual plants. We tested this hypothesis with a 20-year data set from a World Biosphere Reserve in mediterranean Chile. In this semiarid environment, rainfall varies annually and dramatically influences cover by both native and exotic annual plants; degu population density affects the composition and cover of exotic and native annual plants. In low-rainfall years, cover of both native and exotic herbs is extremely low. Higher levels of precipitation result in proportional increases in cover of all annual plants (exotic and native species), leading in turn to increases in degu population densities, at which point they impact native herbs in proportion to their greater cover, indirectly favoring the expansion of exotic plants. We propose that bottom-up control of consumers at our site results in top-down indirect facilitation of invasive annual herbs, and that this pattern may be general to other semiarid ecosystems.

  6. Beyond Defining the Smart City. Meeting Top-Down and Bottom-Up Approaches in the Middle

    Directory of Open Access Journals (Sweden)

    Jonas Breuer

    2014-05-01

    Full Text Available This paper aims to better frame the discussion and the various, divergent operationalisations and interpretations of the Smart City concept. We start by explicating top-down approaches to the Smart City, followed by what purely bottom-up initiatives can look like. We provide a clear overview of stakeholders’ different viewpoints on the city of tomorrow. Particularly the consequences and potential impacts of these differing interpretations and approaches should be of specific interest to researchers, policy makers, city administrations, private actors and anyone involved and concerned with life in cities. Therefore the goal of this article is not so much answering the question of what the Smart City is, but rather what the concept can mean for different stakeholders as well as the consequences of their interpretation. We do this by assembling an eclectic overview, bringing together definitions, examples and operationalisations from academia, policy and industry as well as identifying major trends and approaches to realizing the Smart City. We add to the debate by proposing a different approach that starts from the collective, collaboration and context when researching Smart City initiatives.

  7. Integration of bottom-up and top-down models for the energy system. A practical case for Denmark

    International Nuclear Information System (INIS)

    Jacobsen, H.; Morthorst, P.E.; Nielsen, L.; Stephensen, P.

    1996-07-01

    The main objective of the project was to integrate the Danish macro economic model ADAM with elements from the energy simulation model BRUS, developed at Risoe. The project has been carried out by Risoe National Laboratory with assistance from the Ministry of Finance. A theoretical part focuses on the differences between top-down and bottom-up modelling of the energy-economy interaction. A combined hybrid model seems a relevant alternative to the two traditional approaches. The hybrid model developed is called Hybris and includes models for: supply of electricity and heat, household demand for electricity, and household demand for heat. These three models interact in a iterative procedure with the macro economic model ADAM through a number of links. A reference case as well as a number of scenarios illustrating the capabilities of the model has been set up.Hybris is a simulation model which is capable of analyzing combined CO 2 reduction initiatives as regulation of the energy supply system and a CO 2 tax in an integrated and consistent way. (au) 32 tabs., 98 ills., 55 refs

  8. 2D FT-ICR MS of Calmodulin: A Top-Down and Bottom-Up Approach.

    Science.gov (United States)

    Floris, Federico; van Agthoven, Maria; Chiron, Lionel; Soulby, Andrew J; Wootton, Christopher A; Lam, Yuko P Y; Barrow, Mark P; Delsuc, Marc-André; O'Connor, Peter B

    2016-09-01

    Two-dimensional Fourier transform ion cyclotron resonance mass spectrometry (2D FT-ICR MS) allows data-independent fragmentation of all ions in a sample and correlation of fragment ions to their precursors through the modulation of precursor ion cyclotron radii prior to fragmentation. Previous results show that implementation of 2D FT-ICR MS with infrared multi-photon dissociation (IRMPD) and electron capture dissociation (ECD) has turned this method into a useful analytical tool. In this work, IRMPD tandem mass spectrometry of calmodulin (CaM) has been performed both in one-dimensional and two-dimensional FT-ICR MS using a top-down and bottom-up approach. 2D IRMPD FT-ICR MS is used to achieve extensive inter-residue bond cleavage and assignment for CaM, using its unique features for fragment identification in a less time- and sample-consuming experiment than doing the same thing using sequential MS/MS experiments. Graphical Abstract ᅟ.

  9. Single, aligned carbon nanotubes in 3D nanoscale architectures enabled by top-down and bottom-up manufacturable processes

    International Nuclear Information System (INIS)

    Kaul, Anupama B; Megerian, Krikor G; Von Allmen, Paul; Baron, Richard L

    2009-01-01

    We have developed manufacturable approaches for forming single, vertically aligned carbon nanotubes, where the tubes are centered precisely, and placed within a few hundred nm of 1-1.5 μm deep trenches. These wafer-scale approaches were enabled by using chemically amplified resists and high density, low pressure plasma etching techniques to form the 3D nanoscale architectures. The tube growth was performed using dc plasma-enhanced chemical vapor deposition (PECVD), and the materials used in the pre-fabricated 3D architectures were chemically and structurally compatible with the high temperature (700 deg. C) PECVD synthesis of our tubes, in an ammonia and acetylene ambient. Such scalable, high throughput top-down fabrication processes, when integrated with the bottom-up tube synthesis techniques, should accelerate the development of plasma grown tubes for a wide variety of applications in electronics, such as nanoelectromechanical systems, interconnects, field emitters and sensors. Tube characteristics were also engineered to some extent, by adjusting the Ni catalyst thickness, as well as the pressure and plasma power during growth.

  10. Top-Down-Assisted Bottom-Up Method for Homologous Protein Sequencing: Hemoglobin from 33 Bird Species

    Science.gov (United States)

    Song, Yang; Laskay, Ünige A.; Vilcins, Inger-Marie E.; Barbour, Alan G.; Wysocki, Vicki H.

    2015-11-01

    Ticks are vectors for disease transmission because they are indiscriminant in their feeding on multiple vertebrate hosts, transmitting pathogens between their hosts. Identifying the hosts on which ticks have fed is important for disease prevention and intervention. We have previously shown that hemoglobin (Hb) remnants from a host on which a tick fed can be used to reveal the host's identity. For the present research, blood was collected from 33 bird species that are common in the U.S. as hosts for ticks but that have unknown Hb sequences. A top-down-assisted bottom-up mass spectrometry approach with a customized searching database, based on variability in known bird hemoglobin sequences, has been devised to facilitate fast and complete sequencing of hemoglobin from birds with unknown sequences. These hemoglobin sequences will be added to a hemoglobin database and used for tick host identification. The general approach has the potential to sequence any set of homologous proteins completely in a rapid manner.

  11. Energy-environment policy modeling of endogenous technological change with personal vehicles. Combining top-down and bottom-up methods

    International Nuclear Information System (INIS)

    Jaccard, Mark; Murphy, Rose; Rivers, Nic

    2004-01-01

    The transportation sector offers substantial potential for greenhouse gas (GHG) emission abatement, but widely divergent cost estimates complicate policy making; energy-economy policy modelers apply top-down and bottom-up cost definitions and different assumptions about future technologies and the preferences of firms and households. Our hybrid energy-economy policy model is technology-rich, like a bottom-up model, but has empirically estimated behavioral parameters for risk and technology preferences, like a top-down model. Unlike typical top-down models, however, it simulates technological change endogenously with functions that relate the financial costs of technologies to cumulative production and adjust technology preferences as market shares change. We apply it to the choice of personal vehicles to indicate, first, the effect on cost estimates of divergent cost definitions and, second, the possible response to policies that require a minimum market share for low emission vehicles

  12. How interactions between top-down and bottom-up controls on carbon cycling affect fluxes within and from lakes

    Science.gov (United States)

    Sadro, S.; Piovia-Scott, J.; Nelson, C.; Sickman, J. O.; Knapp, R.

    2017-12-01

    While the role of inland waters in global carbon cycling has grown clearer in recent decades, the extent to which top-down and bottom-up mechanisms interact to regulate dynamics at the catchment scale is not well understood. The degree to which lakes process, export, or store terrestrial carbon is influenced by hydrological variability, variation in the magnitude of terrestrial organic matter (t-OM) entering a system, the efficiency with which such material is metabolized by bacterioplankton, the extent to which it is incorporated into secondary consumer biomass, and by the effects of food-web structure, such as the presence or absence of top predators. However, how these processes interact to mediate carbon fluxes between terrestrial, aquatic, and atmospheric reservoirs remains unclear. We develop a conceptual model that explores how interactions among these factors ultimately affects carbon dynamics using data from lakes located in the Sierra Nevada mountains of California. The Sierra are an excellent system for studies of carbon cycling because elevation-induced landscape gradients in soil development and vegetation cover provide large natural variation in terrestrial inputs to lakes, while variation in confounding factors such as lake morphometry or trophic state is comparatively small. Dissolved organic carbon concentrations increase 100 fold in lakes spanning the alpine to montane elevation gradient found in the Sierra, and fluorescence characteristics reflect an increasingly terrestrial signature with decreasing elevation. Bacterioplankton make up a large proportion of total ecosystem metabolism in these systems, and their metabolic efficiency is tightly coupled to the composition of dissolved organic matter. Stable isotope food web data (δ13C, Δ14C, and δ2H) and measurements of pCO2 from lakes indicate the magnitude of allochthony, rates if carbon cycling, and ecosystem heterotrophy all increase with the increasingly terrestrial signature of dissolved

  13. Bottom-up effects on top-down regulation of a floating aquatic plant by two weevil species: the context-specific nature of biological control

    Science.gov (United States)

    1. Plant nutrition (bottom-up effects) impacts a plant’s ability to sustain herbivory (top-down effects) and affects phytophagous insect fecundity. These factors potentially confound efficacy predictions for biological control projects. We investigated the relative importance of these two forces wi...

  14. The changing contribution of top-down and bottom-up limitation of mesopredators during 220 years of land use and climate change

    NARCIS (Netherlands)

    Pasanen-Mortensen, Marianne; Elmhagen, Bodil; Lindén, Harto; Bergström, Roger; Wallgren, Märtha; van der Velde, Ype; Cousins, Sara A.O.

    2017-01-01

    Apex predators may buffer bottom-up driven ecosystem change, as top-down suppression may dampen herbivore and mesopredator responses to increased resource availability. However, theory suggests that for this buffering capacity to be realized, the equilibrium abundance of apex predators must

  15. Bottom-up effects on biomass versus top-down effects on identity: a multiple-lake fish community manipulation experiment

    NARCIS (Netherlands)

    Lemmens, P.; Declerck, S.A.J.; Tuytens, K.; Vanderstukken, M.; De Meester, L.

    2018-01-01

    The extent to which ecosystems are regulated by top-down relative to bottom-up control has been a dominant paradigm in ecology for many decades. For lakes, it has been shown that predation by fish is an important determinant of variation in zooplankton and phytoplankton community characteristics.

  16. Disentangling the Role of Cortico-Basal Ganglia Loops in Top-Down and Bottom-Up Visual Attention: An Investigation of Attention Deficits in Parkinson Disease.

    Science.gov (United States)

    Tommasi, Giorgio; Fiorio, Mirta; Yelnik, Jérôme; Krack, Paul; Sala, Francesca; Schmitt, Emmanuelle; Fraix, Valérie; Bertolasi, Laura; Le Bas, Jean-François; Ricciardi, Giuseppe Kenneth; Fiaschi, Antonio; Theeuwes, Jan; Pollak, Pierre; Chelazzi, Leonardo

    2015-06-01

    It is solidly established that top-down (goal-driven) and bottom-up (stimulus-driven) attention mechanisms depend on distributed cortical networks, including prefrontal and frontoparietal regions. On the other hand, it is less clear whether the BG also contribute to one or the other of these mechanisms, or to both. The current study was principally undertaken to clarify this issue. Parkinson disease (PD), a neurodegenerative disorder primarily affecting the BG, has proven to be an effective model for investigating the contribution of the BG to different brain functions; therefore, we set out to investigate deficits of top-down and bottom-up attention in a selected cohort of PD patients. With this objective in mind, we compared the performance on three computerized tasks of two groups of 12 parkinsonian patients (assessed without any treatment), one otherwise pharmacologically treated and the other also surgically treated, with that of a group of controls. The main behavioral tool for our study was an attentional capture task, which enabled us to tap the competition between top-down and bottom-up mechanisms of visual attention. This task was suitably combined with a choice RT and a simple RT task to isolate any specific deficit of attention from deficits in motor response selection and initiation. In the two groups of patients, we found an equivalent increase of attentional capture but also comparable delays in target selection in the absence of any salient distractor (reflecting impaired top-down mechanisms) and movement initiation compared with controls. In contrast, motor response selection processes appeared to be prolonged only in the operated patients. Our results confirm that the BG are involved in both motor and cognitive domains. Specifically, damage to the BG, as it occurs in PD, leads to a distinct deficit of top-down control of visual attention, and this can account, albeit indirectly, for the enhancement of attentional capture, reflecting weakened

  17. Multifaceted roles for low-frequency oscillations in bottom-up and top-down processing during navigation and memory.

    Science.gov (United States)

    Ekstrom, Arne D; Watrous, Andrew J

    2014-01-15

    A prominent and replicated finding is the correlation between running speed and increases in low-frequency oscillatory activity in the hippocampal local field potential. A more recent finding concerns low-frequency oscillations that increase in coherence between the hippocampus and neocortical brain areas such as prefrontal cortex during memory-related behaviors (i.e., remembering the correct location to visit). In this review, we tie together movement-related and memory-related low-frequency oscillations in the rodent with similar findings in humans. We argue that although movement-related low-frequency oscillations, in particular, may have slightly different characteristics in humans than rodents, placing important constraints on our thinking about this issue, both phenomena have similar functional foundations. We review four prominent theoretical models that provide partially conflicting accounts of movement-related low-frequency oscillations. We attempt to tie together these theoretical proposals, and existing data in rodents and humans, with memory-related low-frequency oscillations. We propose that movement-related low-frequency oscillations and memory-related low-frequency oscillatory activity, both of which show significant coherence with oscillations in other brain regions, represent different facets of "spectral fingerprints," or different resonant frequencies within the same brain networks underlying different cognitive processes. Together, movement-related and memory-related low-frequency oscillatory coupling may be linked by their distinct contributions to bottom-up, sensorimotor driven processing and top-down, controlled processing characterizing aspects of memory encoding and retrieval. Copyright © 2013. Published by Elsevier Inc.

  18. Regime shift from phytoplankton to macrophyte dominance in a large river: Top-down versus bottom-up effects

    Energy Technology Data Exchange (ETDEWEB)

    Ibanez, Carles, E-mail: carles.ibanez@irta.cat [IRTA Aquatic Ecosystems, Carretera Poble Nou, Km 5.5, 43540 St. Carles de la Rapita, Catalonia (Spain); Alcaraz, Carles; Caiola, Nuno; Rovira, Albert; Trobajo, Rosa [IRTA Aquatic Ecosystems, Carretera Poble Nou, Km 5.5, 43540 St. Carles de la Rapita, Catalonia (Spain); Alonso, Miguel [United Research Services S.L., Urgell 143, 08036 Barcelona, Catalonia (Spain); Duran, Concha [Confederacion Hidrografica del Ebro, Sagasta 24-26, 50071 Zaragoza, Aragon (Spain); Jimenez, Pere J. [Grup Natura Freixe, Major 56, 43750 Flix, Catalonia (Spain); Munne, Antoni [Agencia Catalana de l' Aigua, Provenca 204-208, 08036 Barcelona, Catalonia (Spain); Prat, Narcis [Departament d' Ecologia, Universitat de Barcelona, Diagonal 645, 08028 Barcelona Catalonia (Spain)

    2012-02-01

    The lower Ebro River (Catalonia, Spain) has recently undergone a regime shift from a phytoplankton-dominated to a macrophyte-dominated system. This shift is well known in shallow lakes but apparently it has never been documented in rivers. Two initial hypotheses to explain the collapse of the phytoplankton were considered: a) the diminution of nutrients (bottom-up); b) the filtering effect due to the colonization of the zebra mussel (top-down). Data on water quality, hydrology and biological communities (phytoplankton, macrophytes and zebra mussel) was obtained both from existing data sets and new surveys. Results clearly indicate that the decrease in phosphorus is the main cause of a dramatic decrease in chlorophyll and large increase in water transparency, triggering the subsequent colonization of macrophytes in the river bed. A Generalized Linear Model analysis showed that the decrease in dissolved phosphorus had a relative importance 14 times higher than the increase in zebra mussel density to explain the variation of total chlorophyll. We suggest that the described changes in the lower Ebro River can be considered a novel ecosystem shift. This shift is triggering remarkable changes in the biological communities beyond the decrease of phytoplankton and the proliferation of macrophytes, such as massive colonization of Simulidae (black fly) and other changes in the benthic invertebrate communities that are currently investigated. - Highlights: Black-Right-Pointing-Pointer We show a regime shift in a large river from phytoplankton to macrophyte dominance. Black-Right-Pointing-Pointer Two main hypotheses are considered: nutrient decrease and zebra mussel grazing. Black-Right-Pointing-Pointer Phosphorus depletion is found to be the main cause of the phytoplankton decline. Black-Right-Pointing-Pointer We conclude that oligotrophication triggered the colonization of macrophytes. Black-Right-Pointing-Pointer This new regime shift in a river is similar to that described

  19. Wave disturbance overwhelms top-down and bottom-up control of primary production in California kelp forests.

    Science.gov (United States)

    Reed, Daniel C; Rassweiler, Andrew; Carr, Mark H; Cavanaugh, Kyle C; Malone, Daniel P; Siegel, David A

    2011-11-01

    We took advantage of regional differences in environmental forcing and consumer abundance to examine the relative importance of nutrient availability (bottom-up), grazing pressure (top-down), and storm waves (disturbance) in determining the standing biomass and net primary production (NPP) of the giant kelp Macrocystis pyrifera in central and southern California. Using a nine-year data set collected from 17 sites we show that, despite high densities of sea urchin grazers and prolonged periods of low nutrient availability in southern California, NPP by giant kelp was twice that of central California where nutrient concentrations were consistently high and sea urchins were nearly absent due to predation by sea otters. Waves associated with winter storms were consistently higher in central California, and the loss of kelp biomass to winter wave disturbance was on average twice that of southern California. These observations suggest that the more intense wave disturbance in central California limited NPP by giant kelp under otherwise favorable conditions. Regional patterns of interannual variation in NPP were similar to those of wave disturbance in that year-to-year variation in disturbance and NPP were both greater in southern California. Our findings provide strong evidence that regional differences in wave disturbance overwhelmed those of nutrient supply and grazing intensity to determine NPP by giant kelp. The important role of disturbance in controlling NPP revealed by our study is likely not unique to giant kelp forests, as vegetation dynamics in many systems are dominated by post-disturbance succession with climax communities being relatively uncommon. The effects of disturbance frequency may be easier to detect in giant kelp because it is fast growing and relatively short lived, with cycles of disturbance and recovery occurring on time scales of years. Much longer data sets (decades to centuries) will likely be needed to properly evaluate the role of

  20. River food webs: an integrative approach to bottom-up flow webs, top-down impact webs, and trophic position.

    Science.gov (United States)

    Benke, Arthur C

    2018-03-31

    The majority of food web studies are based on connectivity, top-down impacts, bottom-up flows, or trophic position (TP), and ecologists have argued for decades which is best. Rarely have any two been considered simultaneously. The present study uses a procedure that integrates the last three approaches based on taxon-specific secondary production and gut analyses. Ingestion flows are quantified to create a flow web and the same data are used to quantify TP for all taxa. An individual predator's impacts also are estimated using the ratio of its ingestion (I) of each prey to prey production (P) to create an I/P web. This procedure was applied to 41 invertebrate taxa inhabiting submerged woody habitat in a southeastern U.S. river. A complex flow web starting with five basal food resources had 462 flows >1 mg·m -2 ·yr -1 , providing far more information than a connectivity web. Total flows from basal resources to primary consumers/omnivores were dominated by allochthonous amorphous detritus and ranged from 1 to >50,000 mg·m -2 ·yr -1 . Most predator-prey flows were much lower (1,000  mg·m -2 ·yr -1 . The I/P web showed that 83% of individual predator impacts were weak (90%). Quantitative estimates of TP ranged from 2 to 3.7, contrasting sharply with seven integer-based trophic levels based on longest feeding chain. Traditional omnivores (TP = 2.4-2.9) played an important role by consuming more prey and exerting higher impacts on primary consumers than strict predators (TP ≥ 3). This study illustrates how simultaneous quantification of flow pathways, predator impacts, and TP together provide an integrated characterization of natural food webs. © 2018 by the Ecological Society of America.

  1. Regime shift from phytoplankton to macrophyte dominance in a large river: Top-down versus bottom-up effects

    International Nuclear Information System (INIS)

    Ibáñez, Carles; Alcaraz, Carles; Caiola, Nuno; Rovira, Albert; Trobajo, Rosa; Alonso, Miguel; Duran, Concha; Jiménez, Pere J.; Munné, Antoni; Prat, Narcís

    2012-01-01

    The lower Ebro River (Catalonia, Spain) has recently undergone a regime shift from a phytoplankton-dominated to a macrophyte-dominated system. This shift is well known in shallow lakes but apparently it has never been documented in rivers. Two initial hypotheses to explain the collapse of the phytoplankton were considered: a) the diminution of nutrients (bottom-up); b) the filtering effect due to the colonization of the zebra mussel (top-down). Data on water quality, hydrology and biological communities (phytoplankton, macrophytes and zebra mussel) was obtained both from existing data sets and new surveys. Results clearly indicate that the decrease in phosphorus is the main cause of a dramatic decrease in chlorophyll and large increase in water transparency, triggering the subsequent colonization of macrophytes in the river bed. A Generalized Linear Model analysis showed that the decrease in dissolved phosphorus had a relative importance 14 times higher than the increase in zebra mussel density to explain the variation of total chlorophyll. We suggest that the described changes in the lower Ebro River can be considered a novel ecosystem shift. This shift is triggering remarkable changes in the biological communities beyond the decrease of phytoplankton and the proliferation of macrophytes, such as massive colonization of Simulidae (black fly) and other changes in the benthic invertebrate communities that are currently investigated. - Highlights: ► We show a regime shift in a large river from phytoplankton to macrophyte dominance. ► Two main hypotheses are considered: nutrient decrease and zebra mussel grazing. ► Phosphorus depletion is found to be the main cause of the phytoplankton decline. ► We conclude that oligotrophication triggered the colonization of macrophytes. ► This new regime shift in a river is similar to that described in shallow lakes.

  2. Independent effects of bottom-up temporal expectancy and top-down spatial attention. An audiovisual study using rhythmic cueing.

    Directory of Open Access Journals (Sweden)

    Alexander eJones

    2015-01-01

    Full Text Available Selective attention to a spatial location has shown enhance perception and facilitate behaviour for events at attended locations. However, selection relies not only on where but also when an event occurs. Recently, interest has turned to how intrinsic neural oscillations in the brain entrain to rhythms in our environment, and, stimuli appearing in or out of synch with a rhythm have shown to modulate perception and performance. Temporal expectations created by rhythms and spatial attention are two processes which have independently shown to affect stimulus processing but it remains largely unknown how, and if, they interact. In four separate tasks, this study investigated the effects of voluntary spatial attention and bottom-up temporal expectations created by rhythms in both unimodal and crossmodal conditions. In each task the participant used an informative cue, either colour or pitch, to direct their covert spatial attention to the left or right, and respond as quickly as possible to a target. The lateralized target (visual or auditory was then presented at the attended or unattended side. Importantly, although not task relevant, the cue was a rhythm of either flashes or beeps. The target was presented in or out of sync (early or late with the rhythmic cue. The results showed participants were faster responding to spatially attended compared to unattended targets in all tasks. Moreover, there was an effect of rhythmic cueing upon response times in both unimodal and crossmodal conditions. Responses were faster to targets presented in sync with the rhythm compared to when they appeared too early in both crossmodal tasks. That is, rhythmic stimuli in one modality influenced the temporal expectancy in the other modality, suggesting temporal expectancies created by rhythms are crossmodal. Interestingly, there was no interaction between top-down spatial attention and rhythmic cueing in any task suggesting these two processes largely influenced

  3. Top-down and bottom-up lipidomic analysis of rabbit lipoproteins under different metabolic conditions using flow field-flow fractionation, nanoflow liquid chromatography and mass spectrometry.

    Science.gov (United States)

    Byeon, Seul Kee; Kim, Jin Yong; Lee, Ju Yong; Chung, Bong Chul; Seo, Hong Seog; Moon, Myeong Hee

    2015-07-31

    This study demonstrated the performances of top-down and bottom-up approaches in lipidomic analysis of lipoproteins from rabbits raised under different metabolic conditions: healthy controls, carrageenan-induced inflammation, dehydration, high cholesterol (HC) diet, and highest cholesterol diet with inflammation (HCI). In the bottom-up approach, the high density lipoproteins (HDL) and the low density lipoproteins (LDL) were size-sorted and collected on a semi-preparative scale using a multiplexed hollow fiber flow field-flow fractionation (MxHF5), followed by nanoflow liquid chromatography-ESI-MS/MS (nLC-ESI-MS/MS) analysis of the lipids extracted from each lipoprotein fraction. In the top-down method, size-fractionated lipoproteins were directly infused to MS for quantitative analysis of targeted lipids using chip-type asymmetrical flow field-flow fractionation-electrospray ionization-tandem mass spectrometry (cAF4-ESI-MS/MS) in selected reaction monitoring (SRM) mode. The comprehensive bottom-up analysis yielded 122 and 104 lipids from HDL and LDL, respectively. Rabbits within the HC and HCI groups had lipid patterns that contrasted most substantially from those of controls, suggesting that HC diet significantly alters the lipid composition of lipoproteins. Among the identified lipids, 20 lipid species that exhibited large differences (>10-fold) were selected as targets for the top-down quantitative analysis in order to compare the results with those from the bottom-up method. Statistical comparison of the results from the two methods revealed that the results were not significantly different for most of the selected species, except for those species with only small differences in concentration between groups. The current study demonstrated that top-down lipid analysis using cAF4-ESI-MS/MS is a powerful high-speed analytical platform for targeted lipidomic analysis that does not require the extraction of lipids from blood samples. Copyright © 2015 Elsevier B

  4. Bottom and top physics

    International Nuclear Information System (INIS)

    Foley, K.J.; Fridman, A.; Gilman, F.J.; Herten, G.; Hinchliffe, I.; Jawahery, A.; Sanda, A.; Schmidt, M.P.; Schubert, K.R.

    1987-09-01

    The production of bottom quarks at the SSC and the formalism and phenomenology of observing CP violation in B meson decays is discussed. The production of a heavy t quark which decays into a real W boson, and what we might learn from its decays is examined

  5. Bottom and top physics

    International Nuclear Information System (INIS)

    Foley, K.J.; Gilman, F.J.; Herten, G.; Hinchliffe, I.; Jawahery, A.; Sanda, A.; Schmidt, M.P.; Schubert, K.R.; Fridman, A.

    1988-01-01

    The production of heavy quark flavors occurs primarily by the strong interactions and offers another arena in which to test QCD and to probe gluon distributions at very small values of x. Such quarks can also be produced as decay products of possible new, yet undiscovered particles, e.g., Higgs bosons, and therefore are a necessary key to reconstructing such particles. The decay products of heavy quarks, especially from their semileptonic decays, can themselves form a background to other new physics processes. The production of bottom quarks at the SSC and the formalism and phenomenology of observing CP violation in B meson decays is discussed. The production of a heavy t quark which decays into a real W boson, and what might be learned from its decays is examined

  6. Abundance and size structure of planktonic protist communities in a Neotropical floodplain: effects of top-down and bottom-up controls

    Directory of Open Access Journals (Sweden)

    Bianca Ramos de Meira

    2017-12-01

    Full Text Available Abstract: Aim: We aimed to assess the influence of bottom-up and top-down control mechanisms on the abundance and size structure of protist communities (heterotrophic flagellates and ciliates. We formulated the following hypothesis: bottom-up control mechanisms, related to the availability of resources in the environment, are responsible for structuring the abundance of these communities, whereas top-down control mechanisms, related to predation effects, determine the size pattern of these organisms. Methods Samples for planktonic organisms were taken in 20 shallow lakes belonging to the upper Paraná River floodplain. We evaluated linear regression models to select the best model which predicts the patterns observed according to Akaike Information Criterion. Results The best models selected to explain the abundance of heterotrophic flagellates included negative relations with picophytoplankton abundance and positive with rotifers abundance, while for their size structure, negative relationships were found with heterotrophic bacteria, ciliates and rotifers biovolumes. In relation to the ciliates, their abundances were positively related to the rotifers and picophytoplankton abundances and negatively with the heterotrophic bacteria abundance. On the other hand, for the size structure, the best models selected strong negative relations with the microcrustaceans biovolumes, in addition to relations with the different fractions of the phytoplankton. Conclusion For both flagellates and ciliates, their abundance is being mainly regulated by a bottom up control mechanism, whereas for the size structure the results showed that both food resources and predators were important, indicating that bottom-up and top-down mechanisms act simultaneously in determining the size of these microorganisms.

  7. Top-down and bottom-up influences on the left ventral occipito-temporal cortex during visual word recognition: an analysis of effective connectivity.

    Science.gov (United States)

    Schurz, Matthias; Kronbichler, Martin; Crone, Julia; Richlan, Fabio; Klackl, Johannes; Wimmer, Heinz

    2014-04-01

    The functional role of the left ventral occipito-temporal cortex (vOT) in visual word processing has been studied extensively. A prominent observation is higher activation for unfamiliar but pronounceable letter strings compared to regular words in this region. Some functional accounts have interpreted this finding as driven by top-down influences (e.g., Dehaene and Cohen [2011]: Trends Cogn Sci 15:254-262; Price and Devlin [2011]: Trends Cogn Sci 15:246-253), while others have suggested a difference in bottom-up processing (e.g., Glezer et al. [2009]: Neuron 62:199-204; Kronbichler et al. [2007]: J Cogn Neurosci 19:1584-1594). We used dynamic causal modeling for fMRI data to test bottom-up and top-down influences on the left vOT during visual processing of regular words and unfamiliar letter strings. Regular words (e.g., taxi) and unfamiliar letter strings of pseudohomophones (e.g., taksi) were presented in the context of a phonological lexical decision task (i.e., "Does the item sound like a word?"). We found no differences in top-down signaling, but a strong increase in bottom-up signaling from the occipital cortex to the left vOT for pseudohomophones compared to words. This finding can be linked to functional accounts which assume that the left vOT contains neurons tuned to complex orthographic features such as morphemes or words [e.g., Dehaene and Cohen [2011]: Trends Cogn Sci 15:254-262; Kronbichler et al. [2007]: J Cogn Neurosci 19:1584-1594]: For words, bottom-up signals converge onto a matching orthographic representation in the left vOT. For pseudohomophones, the propagated signals do not converge, but (partially) activate multiple orthographic word representations, reflected in increased effective connectivity. Copyright © 2013 Wiley Periodicals, Inc.

  8. Integrated Bottom-Up and Top-Down Liquid Chromatography-Mass Spectrometry for Characterization of Recombinant Human Growth Hormone Degradation Products.

    Science.gov (United States)

    Wang, Yu Annie; Wu, Di; Auclair, Jared R; Salisbury, Joseph P; Sarin, Richa; Tang, Yang; Mozdzierz, Nicholas J; Shah, Kartik; Zhang, Anna Fan; Wu, Shiaw-Lin; Agar, Jeffery N; Love, J Christopher; Love, Kerry R; Hancock, William S

    2017-12-05

    With the advent of biosimilars to the U.S. market, it is important to have better analytical tools to ensure product quality from batch to batch. In addition, the recent popularity of using a continuous process for production of biopharmaceuticals, the traditional bottom-up method, alone for product characterization and quality analysis is no longer sufficient. Bottom-up method requires large amounts of material for analysis and is labor-intensive and time-consuming. Additionally, in this analysis, digestion of the protein with enzymes such as trypsin could induce artifacts and modifications which would increase the complexity of the analysis. On the other hand, a top-down method requires a minimum amount of sample and allows for analysis of the intact protein mass and sequence generated from fragmentation within the instrument. However, fragmentation usually occurs at the N-terminal and C-terminal ends of the protein with less internal fragmentation. Herein, we combine the use of the complementary techniques, a top-down and bottom-up method, for the characterization of human growth hormone degradation products. Notably, our approach required small amounts of sample, which is a requirement due to the sample constraints of small scale manufacturing. Using this approach, we were able to characterize various protein variants, including post-translational modifications such as oxidation and deamidation, residual leader sequence, and proteolytic cleavage. Thus, we were able to highlight the complementarity of top-down and bottom-up approaches, which achieved the characterization of a wide range of product variants in samples of human growth hormone secreted from Pichia pastoris.

  9. Modeling eye movements in visual agnosia with a saliency map approach: bottom-up guidance or top-down strategy?

    Science.gov (United States)

    Foulsham, Tom; Barton, Jason J S; Kingstone, Alan; Dewhurst, Richard; Underwood, Geoffrey

    2011-08-01

    Two recent papers (Foulsham, Barton, Kingstone, Dewhurst, & Underwood, 2009; Mannan, Kennard, & Husain, 2009) report that neuropsychological patients with a profound object recognition problem (visual agnosic subjects) show differences from healthy observers in the way their eye movements are controlled when looking at images. The interpretation of these papers is that eye movements can be modeled as the selection of points on a saliency map, and that agnosic subjects show an increased reliance on visual saliency, i.e., brightness and contrast in low-level stimulus features. Here we review this approach and present new data from our own experiments with an agnosic patient that quantifies the relationship between saliency and fixation location. In addition, we consider whether the perceptual difficulties of individual patients might be modeled by selectively weighting the different features involved in a saliency map. Our data indicate that saliency is not always a good predictor of fixation in agnosia: even for our agnosic subject, as for normal observers, the saliency-fixation relationship varied as a function of the task. This means that top-down processes still have a significant effect on the earliest stages of scanning in the setting of visual agnosia, indicating severe limitations for the saliency map model. Top-down, active strategies-which are the hallmark of our human visual system-play a vital role in eye movement control, whether we know what we are looking at or not. Copyright © 2011 Elsevier Ltd. All rights reserved.

  10. The synthesis of bottom-up and top-down approaches to climate policy modeling: Electric power technologies and the cost of limiting US CO2 emissions

    International Nuclear Information System (INIS)

    Wing, Ian Sue

    2006-01-01

    In the US, the bulk of CO 2 abatement induced by carbon taxes comes from electric power. This paper incorporates technology detail into the electricity sector of a computable general equilibrium model of the US economy to characterize electric power's technological margins of adjustment to carbon taxes and to elucidate their general equilibrium effects. Compared to the top-down production function representation of the electricity sector, the technology-rich hybrid specification produces less abatement at a higher welfare cost, suggesting that bottom-up models do not necessarily generate lower costs of abatement than top-down models. This result is shown to be sensitive to the elasticity with which technologies' generating capacities adjust to relative prices

  11. Top-down or bottom-up? Assessing crevassing directions on surging glaciers and developments for physically testing glacier crevassing models.

    Science.gov (United States)

    Rea, B.; Evans, D. J. A.; Benn, D. I.; Brennan, A. J.

    2012-04-01

    Networks of crevasse squeeze ridges (CSRs) preserved on the forelands of many surging glaciers attest to extensive full-depth crevassing. Full-depth connections have been inferred from turbid water up-welling in crevasses and the formation of concertina eskers however, it has not been clearly established if the crevasses formed from the top-down or the bottom-up. A Linear Elastic Fracture Mechanics (LEFM) approach is used to determine the likely propagation direction for Mode I crevasses on seven surging glaciers. Results indicate that, the high extensional surface strain rates are insufficient to promote top-down full-depth crevasses but have sufficient magnitude to penetrate to depths of 4-12 m, explaining the extensive surface breakup accompanying glacier surges. Top-down, full-depth crevassing is only possible when water depth approaches 97% of the crevasse depth. However, the provision of sufficient meltwater is problematic due to the aforementioned extensive shallow surface crevassing. Full-depth, bottom-up crevassing can occur provided basal water pressures are in excess of 80-90% of flotation which is the default for surging and on occasion water pressures may even become artesian. Therefore CSRs, found across many surging glacier forelands and ice margins most likely result from the infilling of basal crevasses formed, for the most part, by bottom-up hydrofracturing. Despite the importance of crevassing for meltwater routing and calving dynamics physically testing numerical crevassing models remains problematic due to technological limitations, changing stress regimes and difficulties associated with working in crevasse zones on glaciers. Mapping of CSR spacing and matching to surface crevasse patterns can facilitate quantitative comparison between the LEFM model and observed basal crevasses provided ice dynamics are known. However, assessing full-depth top-down crevasse propagation is much harder to monitor in the field and no geomorphological record is

  12. Age-Related Inter-region EEG Coupling Changes during the Control of Bottom-up and Top-down Attention

    Directory of Open Access Journals (Sweden)

    Ling eLi

    2015-12-01

    Full Text Available We investigated age-related changes in electroencephalographic (EEG coupling of theta-, alpha-, and beta-frequency bands during bottom-up and top-down attention. Arrays were presented with either automatic pop-out (bottom-up or effortful search (top-down behavior to younger and older participants. The phase-locking value (PLV was used to estimate coupling strength between scalp recordings. Behavioral performance decreased with age, with a greater age-related decline in accuracy for the search than for the pop-out condition. Aging was associated with a declined coupling strength of theta and alpha frequency bands, with a greater age-related decline in whole-brain coupling values for the search than for the pop-out condition. Specifically, prefronto-frontal coupling in theta- and alpha-bands, fronto-parietal and parieto-occipital couplings in beta-band for younger group showed a right hemispheric dominance, which was reduced with aging to compensate for the inhibitory dysfunction. While pop-out target detection was mainly associated with greater parieto-occipital beta-coupling strength compared to search condition regardless of aging. Furthermore, prefronto-frontal coupling in theta-, alpha- and beta-bands, and parieto-occipital coupling in beta-band functioned as predictors of behavior for both groups. Taken together these findings provide evidence that prefronto-frontal coupling of theta-, alpha-, and beta-bands may serve as a possible basis of aging during visual attention, while parieto-occipital coupling in beta-band could serve for a bottom-up function and be vulnerable to top-down attention control for younger and older groups.

  13. Using Top-down and Bottom-up Costing Approaches in LMICs: The Case for Using Both to Assess the Incremental Costs of New Technologies at Scale.

    Science.gov (United States)

    Cunnama, Lucy; Sinanovic, Edina; Ramma, Lebogang; Foster, Nicola; Berrie, Leigh; Stevens, Wendy; Molapo, Sebaka; Marokane, Puleng; McCarthy, Kerrigan; Churchyard, Gavin; Vassall, Anna

    2016-02-01

    Estimating the incremental costs of scaling-up novel technologies in low-income and middle-income countries is a methodologically challenging and substantial empirical undertaking, in the absence of routine cost data collection. We demonstrate a best practice pragmatic approach to estimate the incremental costs of new technologies in low-income and middle-income countries, using the example of costing the scale-up of Xpert Mycobacterium tuberculosis (MTB)/resistance to riframpicin (RIF) in South Africa. We estimate costs, by applying two distinct approaches of bottom-up and top-down costing, together with an assessment of processes and capacity. The unit costs measured using the different methods of bottom-up and top-down costing, respectively, are $US16.9 and $US33.5 for Xpert MTB/RIF, and $US6.3 and $US8.5 for microscopy. The incremental cost of Xpert MTB/RIF is estimated to be between $US14.7 and $US17.7. While the average cost of Xpert MTB/RIF was higher than previous studies using standard methods, the incremental cost of Xpert MTB/RIF was found to be lower. Costs estimates are highly dependent on the method used, so an approach, which clearly identifies resource-use data collected from a bottom-up or top-down perspective, together with capacity measurement, is recommended as a pragmatic approach to capture true incremental cost where routine cost data are scarce. © 2016 The Authors. Health Economics published by John Wiley & Sons Ltd.

  14. Influence of top-down and bottom-up manipulations on the R-BT065 subcluster of Betaproteobacteria, an abundant group in bacterioplankton of a freshwater reservoir

    Czech Academy of Sciences Publication Activity Database

    Šimek, Karel; Horňák, Karel; Jezbera, Jan; Mašín, Michal; Nedoma, Jiří; Gasol, J. M. .; Schauer, M.

    2005-01-01

    Roč. 71, č. 5 (2005), s. 2381-2390 ISSN 0099-2240 R&D Projects: GA ČR(CZ) GA206/05/0007; GA ČR(CZ) GA206/02/0003 Grant - others:CSIC(ES) DGICYT REN2001-2120/MAR; EU(XE) EVK3-CT-2002-00078; Austrian Science Foundation(AT) P15655 Institutional research plan: CEZ:AV0Z60170517 Keywords : reservoir * top-down and bottom-up control * microbial food webs * bacterivory * bacterial community composition Subject RIV: EE - Microbiology, Virology Impact factor: 3.818, year: 2005

  15. Can bottom-up processes of attention be a source of 'interference' in situations where top-down control of attention is crucial?

    Science.gov (United States)

    Nikolla, Dritan; Edgar, Graham; Catherwood, Dianne; Matthews, Tristan

    2018-02-01

    In this study, we investigate whether emotionally engaged bottom-up processes of attention can be a source of 'interference' in situations where top-down control of attention is necessary. Participants were asked to monitor and report on a video of a war scenario showing a developing battle in two conditions: emotionally positive and emotionally negative. Half of the participants (n = 15) were exposed to task-irrelevant pictures of positive emotional valence embedded within the scenario; the other half were exposed to task-irrelevant pictures of negative emotional valence. Sensitivity and Bias scores were calculated using signal detection theory. Overall, task accuracy scores were dependent upon the valence; negative pictures had an adverse effect on performance, whereas positive pictures improved performance. We concluded that negative emotional pictures interfered with top-down control of attention by attracting competing bottom-up processes of attention. We found the opposite effect for positive emotional stimuli. © 2017 The British Psychological Society.

  16. Top-Down and Bottom-Up Approaches in Engineering 1 T Phase Molybdenum Disulfide (MoS2 ): Towards Highly Catalytically Active Materials.

    Science.gov (United States)

    Chua, Chun Kiang; Loo, Adeline Huiling; Pumera, Martin

    2016-09-26

    The metallic 1 T phase of MoS2 has been widely identified to be responsible for the improved performances of MoS2 in applications including hydrogen evolution reactions and electrochemical supercapacitors. To this aim, various synthetic methods have been reported to obtain 1 T phase-rich MoS2 . Here, the aim is to evaluate the efficiencies of the bottom-up (hydrothermal reaction) and top-down (chemical exfoliation) approaches in producing 1 T phase MoS2 . It is established in this study that the 1 T phase MoS2 produced through the bottom-up approach contains a high proportion of 1 T phase and demonstrates excellent electrochemical and electrical properties. Its performance in the hydrogen evolution reaction and electrochemical supercapacitors also surpassed that of 1 T phase MoS2 produced through a top-down approach. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  17. Top-down and bottom-up characterization of nitrated birch pollen allergen Bet v 1a with CZE hyphenated to an Orbitrap mass spectrometer.

    Science.gov (United States)

    Gusenkov, Sergey; Stutz, Hanno

    2018-02-01

    Tyrosine (Tyr) residues of the major pollen allergen of birch Betula verrucosa, Bet v 1a, were nitrated by peroxynitrite. This modification enhances the allergenicity. Modified tyrosines were identified by analyzing intact allergen variants in combination with top-down and bottom-up approaches. Therefore, a laboratory-built sheath-liquid assisted ESI interface was applied for hyphenation of CE to an Orbitrap mass spectrometer to localize individual nitration sites. The major focus was on identification of primary nitration sites. The top-down approach unambiguously identified Tyr 5 as the most prominent modification site. Fragments from the allergen core and the C-terminal part carried up to three potential nitration sites, respectively. Thus, a bottom-up approach with tryptic digest was used as a complementary strategy which allowed for the unambiguous localization of nitration sites within the respective peptides. Nitration propensity for individual Tyr residues was addressed by comparison of MS signals of nitrated peptides relative to all cognates of homolog primary sequence. Combined data identified surface exposed Tyr 5 and Tyr 66 as major nitration sites followed by less accessible Tyr 158 whereas Tyr 81, 83 and 150 possess a lower nitration tendency and are apparently modified in variants with higher nitration levels. © 2018 The Authors. Electrophoresis published by Wiley-VCH Verlag GmbH & Co. KGaA.

  18. Top-Down and Bottom-Up Identification of Proteins by Liquid Extraction Surface Analysis Mass Spectrometry of Healthy and Diseased Human Liver Tissue

    Science.gov (United States)

    Sarsby, Joscelyn; Martin, Nicholas J.; Lalor, Patricia F.; Bunch, Josephine; Cooper, Helen J.

    2014-09-01

    Liquid extraction surface analysis mass spectrometry (LESA MS) has the potential to become a useful tool in the spatially-resolved profiling of proteins in substrates. Here, the approach has been applied to the analysis of thin tissue sections from human liver. The aim was to determine whether LESA MS was a suitable approach for the detection of protein biomarkers of nonalcoholic liver disease (nonalcoholic steatohepatitis, NASH), with a view to the eventual development of LESA MS for imaging NASH pathology. Two approaches were considered. In the first, endogenous proteins were extracted from liver tissue sections by LESA, subjected to automated trypsin digestion, and the resulting peptide mixture was analyzed by liquid chromatography tandem mass spectrometry (LC-MS/MS) (bottom-up approach). In the second (top-down approach), endogenous proteins were extracted by LESA, and analyzed intact. Selected protein ions were subjected to collision-induced dissociation (CID) and/or electron transfer dissociation (ETD) mass spectrometry. The bottom-up approach resulted in the identification of over 500 proteins; however identification of key protein biomarkers, liver fatty acid binding protein (FABP1), and its variant (Thr→Ala, position 94), was unreliable and irreproducible. Top-down LESA MS analysis of healthy and diseased liver tissue revealed peaks corresponding to multiple (~15-25) proteins. MS/MS of four of these proteins identified them as FABP1, its variant, α-hemoglobin, and 10 kDa heat shock protein. The reliable identification of FABP1 and its variant by top-down LESA MS suggests that the approach may be suitable for imaging NASH pathology in sections from liver biopsies.

  19. Bottom-up and Top-down Approaches to Explore Sodium Dodecyl Sulfate and Soluplus on the Crystallization Inhibition and Dissolution of Felodipine Extrudates.

    Science.gov (United States)

    Chen, Jiali; Chen, Yuqi; Huang, Wencong; Wang, Hanning; Du, Yang; Xiong, Subin

    2018-05-05

    The objectives of this study were to explore sodium dodecyl sulfate (SDS) and Soluplus on the crystallization inhibition and dissolution of felodipine (FLDP) extrudates by bottom-up and top-down approaches. FLDP extrudates with Soluplus and/or SDS were prepared by hot melt extrusion (HME), and characterized by PLM, DSC and FT-IR. Results indicated that Soluplus inhibited FLDP crystallization and the whole amorphous solid dispersions (ASDs) were binary FLDP-Soluplus (1:3) and ternary FLDP-Soluplus-SDS(1:2:0.15∼0.3 and 1:3:0.2∼0.4) extrudates. Internal SDS (5%-10%) decreased Tgs of FLDP-Soluplus-SDS ternary ASDs without presenting molecular interactions with FLDP or Soluplus. The enhanced dissolution rate of binary or ternary Soluplus-rich ASDs in the non-sink condition of 0.05%SDS was achieved. Bottom-up approach indicated that Soluplus was a much stronger crystal inhibitor to the supersaturated FLDP in solutions than SDS. Top-down approach demonstrated that SDS enhanced the dissolution of Soluplus-rich ASDs via wettability and complexation with Soluplus to accelerate the medium uptake and erosion kinetics of extrudates, but induced FLDP recrystallization and resulted in incomplete dissolution of FLDP-rich extrudates. In conclusion, top-down approach is a promising strategy to explore the mechanisms of ASDs' dissolution, and small amount of SDS enhances the dissolution rate of polymer-rich ASDs in the non-sink condition. Copyright © 2018. Published by Elsevier Inc.

  20. Analysis of top-down and bottom-up North American CO2 and CH4 emissions estimates in the second State of the Carbon Cycle Report

    Science.gov (United States)

    Miller, J. B.; Jacobson, A. R.; Bruhwiler, L.; Michalak, A.; Hayes, D. J.; Vargas, R.

    2017-12-01

    In just ten years since publication of the original State of the Carbon Cycle Report in 2007, global CO2 concentrations have risen by more than 22 ppm to 405 ppm. This represents 18% of the increase over preindustrial levels of 280 ppm. This increase is being driven unequivocally by fossil fuel combustion with North American emissions comprising roughly 20% of the global total over the past decade. At the global scale, we know by comparing well-known fossil fuel inventories and rates of atmospheric CO2 increase that about half of all emissions are absorbed at Earth's surface. For North America, however, we can not apply a simple mass balance to determine sources and sinks. Instead, contributions from ecosystems must be estimated using top-down and bottom-up methods. SOCCR-2 estimates North American net CO2 uptake from ecosystems using bottom-up (inventory) methods as 577 +/- 433 TgC/yr and 634 +/- 288 TgC/yr from top-down atmospheric inversions. Although the global terrestrial carbon sink is not precisely known, these values represent possibly 30% of the global values. As with net sink estimates reported in SOCCR, these new top-down and bottom-up estimates are statistically consistent with one another. However, the uncertainties on each of these estimates are now substantially smaller, giving us more confidence about where the truth lies. Atmospheric inversions also yield estimates of interannual variations (IAV) in CO2 and CH4 fluxes. Our syntheses suggest that IAV of ecosystem CO2 fluxes is of order 100 TgC/yr, mainly originating in the conterminous US, with lower variability in boreal and arctic regions. Moreover, this variability is much larger than for inventory-based fluxes reported by the US to the UNFCCC. Unlike CO2, bottom-up CH4 emissions are larger than those derived from large-scale atmospheric data, with the continental discrepancy resulting primarily from differences in arctic and boreal regions. In addition to the current state of the science, we

  1. Temperature regulation of marine heterotrophic prokaryotes increases latitudinally as a breach between bottom-up and top-down controls

    KAUST Repository

    Moran, Xose Anxelu G.; Gasol, Josep M.; Pernice, Massimo C.; Mangot, Jean-Franç ois; Massana, Ramon; Lara, Elena; Vaqué , Dolors; Duarte, Carlos M.

    2017-01-01

    Planktonic heterotrophic prokaryotes make up the largest living biomass and process most organic matter in the ocean. Determining when and where the biomass and activity of heterotrophic prokaryotes are controlled by resource availability (bottom

  2. A two-step combination of top-down and bottom-up fire emission estimates at regional and global scales: strengths and main uncertainties

    Science.gov (United States)

    Sofiev, Mikhail; Soares, Joana; Kouznetsov, Rostislav; Vira, Julius; Prank, Marje

    2016-04-01

    Top-down emission estimation via inverse dispersion modelling is used for various problems, where bottom-up approaches are difficult or highly uncertain. One of such areas is the estimation of emission from wild-land fires. In combination with dispersion modelling, satellite and/or in-situ observations can, in principle, be used to efficiently constrain the emission values. This is the main strength of the approach: the a-priori values of the emission factors (based on laboratory studies) are refined for real-life situations using the inverse-modelling technique. However, the approach also has major uncertainties, which are illustrated here with a few examples of the Integrated System for wild-land Fires (IS4FIRES). IS4FIRES generates the smoke emission and injection profile from MODIS and SEVIRI active-fire radiative energy observations. The emission calculation includes two steps: (i) initial top-down calibration of emission factors via inverse dispersion problem solution that is made once using training dataset from the past, (ii) application of the obtained emission coefficients to individual-fire radiative energy observations, thus leading to bottom-up emission compilation. For such a procedure, the major classes of uncertainties include: (i) imperfect information on fires, (ii) simplifications in the fire description, (iii) inaccuracies in the smoke observations and modelling, (iv) inaccuracies of the inverse problem solution. Using examples of the fire seasons 2010 in Russia, 2012 in Eurasia, 2007 in Australia, etc, it is pointed out that the top-down system calibration performed for a limited number of comparatively moderate cases (often the best-observed ones) may lead to errors in application to extreme events. For instance, the total emission of 2010 Russian fires is likely to be over-estimated by up to 50% if the calibration is based on the season 2006 and fire description is simplified. Longer calibration period and more sophisticated parameterization

  3. The synthesis of bottom-up and top-down approaches to climate policy modeling: Electric power technology detail in a social accounting framework

    International Nuclear Information System (INIS)

    Sue Wing, Ian

    2008-01-01

    ''Hybrid'' climate policy simulations have sought to bridge the gap between ''bottom-up'' engineering and ''top-down'' macroeconomic models by integrating the former's energy technology detail into the latter's macroeconomic framework. Construction of hybrid models is complicated by the need to numerically calibrate them to multiple, incommensurate sources of economic and engineering data. I develop a solution to this problem following Howitt's [Howitt, R.E., 1995. Positive Mathematical Programming, American Journal of Agricultural Economics 77: 329-342] positive mathematical programming approach. Using data for the U.S., I illustrate how the inputs to the electricity sector in a social accounting matrix may be allocated among discrete types of generation so as to be consistent with both technologies' input shares from engineering cost estimates, and the zero profit and market clearance conditions of the sector's macroeconomic production structure. (author)

  4. Identifying the computational requirements of an integrated top-down-bottom-up model for overt visual attention within an active vision system.

    Directory of Open Access Journals (Sweden)

    Sebastian McBride

    Full Text Available Computational visual attention systems have been constructed in order for robots and other devices to detect and locate regions of interest in their visual world. Such systems often attempt to take account of what is known of the human visual system and employ concepts, such as 'active vision', to gain various perceived advantages. However, despite the potential for gaining insights from such experiments, the computational requirements for visual attention processing are often not clearly presented from a biological perspective. This was the primary objective of this study, attained through two specific phases of investigation: 1 conceptual modeling of a top-down-bottom-up framework through critical analysis of the psychophysical and neurophysiological literature, 2 implementation and validation of the model into robotic hardware (as a representative of an active vision system. Seven computational requirements were identified: 1 transformation of retinotopic to egocentric mappings, 2 spatial memory for the purposes of medium-term inhibition of return, 3 synchronization of 'where' and 'what' information from the two visual streams, 4 convergence of top-down and bottom-up information to a centralized point of information processing, 5 a threshold function to elicit saccade action, 6 a function to represent task relevance as a ratio of excitation and inhibition, and 7 derivation of excitation and inhibition values from object-associated feature classes. The model provides further insight into the nature of data representation and transfer between brain regions associated with the vertebrate 'active' visual attention system. In particular, the model lends strong support to the functional role of the lateral intraparietal region of the brain as a primary area of information consolidation that directs putative action through the use of a 'priority map'.

  5. "Disorganized in time": impact of bottom-up and top-down negative emotion generation on memory formation among healthy and traumatized adolescents.

    Science.gov (United States)

    Guillery-Girard, Bérengère; Clochon, Patrice; Giffard, Bénédicte; Viard, Armelle; Egler, Pierre-Jean; Baleyte, Jean-Marc; Eustache, Francis; Dayan, Jacques

    2013-09-01

    "Travelling in time," a central feature of episodic memory is severely affected among individuals with Post Traumatic Stress Disorder (PTSD) with two opposite effects: vivid traumatic memories are unorganized in temporality (bottom-up processes), non-traumatic personal memories tend to lack spatio-temporal details and false recognitions occur more frequently that in the general population (top-down processes). To test the effect of these two types of processes (i.e. bottom-up and top-down) on emotional memory, we conducted two studies in healthy and traumatized adolescents, a period of life in which vulnerability to emotion is particularly high. Using negative and neutral images selected from the international affective picture system (IAPS), stimuli were divided into perceptual images (emotion generated by perceptual details) and conceptual images (emotion generated by the general meaning of the material). Both categories of stimuli were then used, along with neutral pictures, in a memory task with two phases (encoding and recognition). In both populations, we reported a differential effect of the emotional material on encoding and recognition. Negative perceptual scenes induced an attentional capture effect during encoding and enhanced the recollective distinctiveness. Conversely, the encoding of conceptual scenes was similar to neutral ones, but the conceptual relatedness induced false memories at retrieval. However, among individuals with PTSD, two subgroups of patients were identified. The first subgroup processed the scenes faster than controls, except for the perceptual scenes, and obtained similar performances to controls in the recognition task. The second subgroup group desmonstrated an attentional deficit in the encoding task with no benefit from the distinctiveness associated with negative perceptual scenes on memory performances. These findings provide a new perspective on how negative emotional information may have opposite influences on memory in

  6. Top-down and bottom-up attention-to-memory: mapping functional connectivity in two distinct networks that underlie cued and uncued recognition memory.

    Science.gov (United States)

    Burianová, Hana; Ciaramelli, Elisa; Grady, Cheryl L; Moscovitch, Morris

    2012-11-15

    The objective of this study was to examine the functional connectivity of brain regions active during cued and uncued recognition memory to test the idea that distinct networks would underlie these memory processes, as predicted by the attention-to-memory (AtoM) hypothesis. The AtoM hypothesis suggests that dorsal parietal cortex (DPC) allocates effortful top-down attention to memory retrieval during cued retrieval, whereas ventral parietal cortex (VPC) mediates spontaneous bottom-up capture of attention by memory during uncued retrieval. To identify networks associated with these two processes, we conducted a functional connectivity analysis of a left DPC and a left VPC region, both identified by a previous analysis of task-related regional activations. We hypothesized that the two parietal regions would be functionally connected with distinct neural networks, reflecting their engagement in the differential mnemonic processes. We found two spatially dissociated networks that overlapped only in the precuneus. During cued trials, DPC was functionally connected with dorsal attention areas, including the superior parietal lobules, right precuneus, and premotor cortex, as well as relevant memory areas, such as the left hippocampus and the middle frontal gyri. During uncued trials, VPC was functionally connected with ventral attention areas, including the supramarginal gyrus, cuneus, and right fusiform gyrus, as well as the parahippocampal gyrus. In addition, activity in the DPC network was associated with faster response times for cued retrieval. This is the first study to show a dissociation of the functional connectivity of posterior parietal regions during episodic memory retrieval, characterized by a top-down AtoM network involving DPC and a bottom-up AtoM network involving VPC. Copyright © 2012 Elsevier Inc. All rights reserved.

  7. Visual scanning and recognition of Chinese, Caucasian, and racially ambiguous faces: contributions from bottom-up facial physiognomic information and top-down knowledge of racial categories.

    Science.gov (United States)

    Wang, Qiandong; Xiao, Naiqi G; Quinn, Paul C; Hu, Chao S; Qian, Miao; Fu, Genyue; Lee, Kang

    2015-02-01

    Recent studies have shown that participants use different eye movement strategies when scanning own- and other-race faces. However, it is unclear (1) whether this effect is related to face recognition performance, and (2) to what extent this effect is influenced by top-down or bottom-up facial information. In the present study, Chinese participants performed a face recognition task with Chinese, Caucasian, and racially ambiguous faces. For the racially ambiguous faces, we led participants to believe that they were viewing either own-race Chinese faces or other-race Caucasian faces. Results showed that (1) Chinese participants scanned the nose of the true Chinese faces more than that of the true Caucasian faces, whereas they scanned the eyes of the Caucasian faces more than those of the Chinese faces; (2) they scanned the eyes, nose, and mouth equally for the ambiguous faces in the Chinese condition compared with those in the Caucasian condition; (3) when recognizing the true Chinese target faces, but not the true target Caucasian faces, the greater the fixation proportion on the nose, the faster the participants correctly recognized these faces. The same was true when racially ambiguous face stimuli were thought to be Chinese faces. These results provide the first evidence to show that (1) visual scanning patterns of faces are related to own-race face recognition response time, and (2) it is bottom-up facial physiognomic information that mainly contributes to face scanning. However, top-down knowledge of racial categories can influence the relationship between face scanning patterns and recognition response time. Copyright © 2014 Elsevier Ltd. All rights reserved.

  8. Identifying the computational requirements of an integrated top-down-bottom-up model for overt visual attention within an active vision system.

    Science.gov (United States)

    McBride, Sebastian; Huelse, Martin; Lee, Mark

    2013-01-01

    Computational visual attention systems have been constructed in order for robots and other devices to detect and locate regions of interest in their visual world. Such systems often attempt to take account of what is known of the human visual system and employ concepts, such as 'active vision', to gain various perceived advantages. However, despite the potential for gaining insights from such experiments, the computational requirements for visual attention processing are often not clearly presented from a biological perspective. This was the primary objective of this study, attained through two specific phases of investigation: 1) conceptual modeling of a top-down-bottom-up framework through critical analysis of the psychophysical and neurophysiological literature, 2) implementation and validation of the model into robotic hardware (as a representative of an active vision system). Seven computational requirements were identified: 1) transformation of retinotopic to egocentric mappings, 2) spatial memory for the purposes of medium-term inhibition of return, 3) synchronization of 'where' and 'what' information from the two visual streams, 4) convergence of top-down and bottom-up information to a centralized point of information processing, 5) a threshold function to elicit saccade action, 6) a function to represent task relevance as a ratio of excitation and inhibition, and 7) derivation of excitation and inhibition values from object-associated feature classes. The model provides further insight into the nature of data representation and transfer between brain regions associated with the vertebrate 'active' visual attention system. In particular, the model lends strong support to the functional role of the lateral intraparietal region of the brain as a primary area of information consolidation that directs putative action through the use of a 'priority map'.

  9. Visual scanning and recognition of Chinese, Caucasian, and racially ambiguous faces: Contributions from bottom-up facial physiognomic information and top-down knowledge of racial categories

    Science.gov (United States)

    Wang, Qiandong; Xiao, Naiqi G.; Quinn, Paul C.; Hu, Chao S.; Qian, Miao; Fu, Genyue; Lee, Kang

    2014-01-01

    Recent studies have shown that participants use different eye movement strategies when scanning own- and other-race faces. However, it is unclear (1) whether this effect is related to face recognition performance, and (2) to what extent this effect is influenced by top-down or bottom-up facial information. In the present study, Chinese participants performed a face recognition task with Chinese faces, Caucasian faces, and racially ambiguous morphed face stimuli. For the racially ambiguous faces, we led participants to believe that they were viewing either own-race Chinese faces or other-race Caucasian faces. Results showed that (1) Chinese participants scanned the nose of the true Chinese faces more than that of the true Caucasian faces, whereas they scanned the eyes of the Caucasian faces more than those of the Chinese faces; (2) they scanned the eyes, nose, and mouth equally for the ambiguous faces in the Chinese condition compared with those in the Caucasian condition; (3) when recognizing the true Chinese target faces, but not the true target Caucasian faces, the greater the fixation proportion on the nose, the faster the participants correctly recognized these faces. The same was true when racially ambiguous face stimuli were thought to be Chinese faces. These results provide the first evidence to show that (1) visual scanning patterns of faces are related to own-race face recognition response time, and (2) it is bottom-up facial physiognomic information of racial categories that mainly contributes to face scanning. However, top-down knowledge of racial categories can influence the relationship between face scanning patterns and recognition response time. PMID:25497461

  10. How to measure top-down vs. bottom-up effects: A new population metric and its calibration on Daphnia

    NARCIS (Netherlands)

    Polishchuk, L.; Vijverberg, J.; Voronov, D.A.; Mooij, W.M.

    2013-01-01

    Research on the role of top–down (predation) and bottom–up (food) effects in food webs has led to the understanding that the variability of these effects in space and time is a fundamental feature of natural systems. Consequently, our measurement tools must allow us to evaluate the effects from a

  11. A comparison of top-down and bottom-up approaches to benthic habitat mapping to inform offshore wind energy development

    Science.gov (United States)

    LaFrance, Monique; King, John W.; Oakley, Bryan A.; Pratt, Sheldon

    2014-07-01

    Recent interest in offshore renewable energy within the United States has amplified the need for marine spatial planning to direct management strategies and address competing user demands. To assist this effort in Rhode Island, benthic habitat classification maps were developed for two sites in offshore waters being considered for wind turbine installation. Maps characterizing and representing the distribution and extent of benthic habitats are valuable tools for improving understanding of ecosystem patterns and processes, and promoting scientifically-sound management decisions. This project presented the opportunity to conduct a comparison of the methodologies and resulting map outputs of two classification approaches, “top-down” and “bottom-up” in the two study areas. This comparison was undertaken to improve understanding of mapping methodologies and their applicability, including the bottom-up approach in offshore environments where data density tends to be lower, as well as to provide case studies for scientists and managers to consider for their own areas of interest. Such case studies can offer guidance for future work for assessing methodologies and translating them to other areas. The traditional top-down mapping approach identifies biological community patterns based on communities occurring within geologically defined habitat map units, under the concept that geologic environments contain distinct biological assemblages. Alternatively, the bottom-up approach aims to establish habitat map units centered on biological similarity and then uses statistics to identify relationships with associated environmental parameters and determine habitat boundaries. When applied to the two study areas, both mapping approaches produced habitat classes with distinct macrofaunal assemblages and each established statistically strong and significant biotic-abiotic relationships with geologic features, sediment characteristics, water depth, and/or habitat

  12. An expanded framework to define and measure shared decision-making in dialogue: A 'top-down' and 'bottom-up' approach.

    Science.gov (United States)

    Callon, Wynne; Beach, Mary Catherine; Links, Anne R; Wasserman, Carly; Boss, Emily F

    2018-03-11

    We aimed to develop a comprehensive, descriptive framework to measure shared decision making (SDM) in clinical encounters. We combined a top-down (theoretical) approach with a bottom-up approach based on audio-recorded dialogue to identify all communication processes related to decision making. We coded 55 pediatric otolaryngology visits using the framework and report interrater reliability. We identified 14 clinician behaviors and 5 patient behaviors that have not been previously described, and developed a new SDM framework that is descriptive (what does happen) rather than normative (what should happen). Through the bottom-up approach we identified three broad domains not present in other SDM frameworks: socioemotional support, understandability of clinician dialogue, and recommendation-giving. We also specify the ways in which decision-making roles are assumed implicitly rather than discussed explicitly. Interrater reliability was >75% for 92% of the coded behaviors. This SDM framework allows for a more expansive understanding and analysis of how decision making takes place in clinical encounters, including new domains and behaviors not present in existing measures. We hope that this new framework will bring attention to a broader conception of SDM and allow researchers to further explore the new domains and behaviors identified. Copyright © 2018. Published by Elsevier B.V.

  13. HCFC-142b emissions in China: An inventory for 2000 to 2050 basing on bottom-up and top-down methods

    Science.gov (United States)

    Han, Jiarui; Li, Li; Su, Shenshen; Hu, Jianxin; Wu, Jing; Wu, Yusheng; Fang, Xuekun

    2014-05-01

    1-Chloro-1,1-difluoroethane (HCFC-142b) is both ozone depleting substance included in the Montreal Protocol on Substances that Deplete the Ozone Layer (Montreal Protocol) and potent greenhouse gas with high global warming potential. As one of the major HCFC-142b consumption and production countries in the world, China's control action will contribute to both mitigating climate change and protecting ozone layer. Estimating China's HCFC-142b emission is a crucial step for understanding its emission status, drawing up phasing-out plan and evaluating mitigation effect. Both the bottom-up and top-down method were adopted in this research to estimate HCFC-142b emissions from China. Results basing on different methods were compared to test the effectiveness of two methods and validate inventory's reliability. Firstly, a national bottom-up emission inventory of HCFC-142b for China during 2000-2012 was established based on the 2006 IPCC Guidelines for National Greenhouse Gas Inventories and the Montreal Protocol, showing that in contrast to the downward trend revealed by existing results, HCFC-142b emissions kept increasing from 0.1 kt/yr in 2000 to the peak of 14.4 kt/yr in 2012. Meanwhile a top-down emission estimation was also developed using interspecies correlation method. By correlating atmospheric mixing ratio data of HCFC-142b and reference substance HCFC-22 sampled from four representative cities (Beijing, Hangzhou, Lanzhou and Guangzhou, for northern, eastern, western and southern China, respectively), China's HCFC-142b emission in 2012 was calculated. It was 16.24(13.90-18.58) kt, equivalent to 1.06 kt ODP and 37 Tg CO2-eq, taking up 9.78% (ODP) of total HCFCs emission in China or 30.5% of global HCFC-142b emission. This result was 12.7% higher than that in bottom-up inventory. Possible explanations were discussed. The consistency of two results lend credit to methods effectiveness and results reliability. Finally, future HCFC-142b emission was projected to 2050

  14. Top-down and bottom-up: Front to back. Comment on "Move me, astonish me... delight my eyes and brain: The Vienna Integrated Model of top-down and bottom-up processes in Art Perception (VIMAP) and corresponding affective, evaluative, and neurophysiological correlates" by Matthew Pelowski et al.

    Science.gov (United States)

    Nadal, Marcos; Skov, Martin

    2017-07-01

    The model presented here [1] is the latest in an evolving series of psychological models aimed at explaining the experience of art, first proposed by Leder and colleagues [2]. The aim of this new version is to ;explicitly connect early bottom-up, artwork-derived processing sequence and outputs to top-down, viewer-derived contribution to the processing sequence; [1, p. 5f & 6]. The ;meeting; of these two processing sequences, the authors contend, is crucial to the understanding of people's responses to art [sections 3.6ff & 4], and therefore the new model's principal motivation.

  15. Top-down expectancy versus bottom-up guidance in search for known color-form conjunctions.

    Science.gov (United States)

    Anderson, Giles M; Humphreys, Glyn W

    2015-11-01

    We assessed the effects of pairing a target object with its familiar color on eye movements in visual search, under conditions where the familiar color could or could not be predicted. In Experiment 1 participants searched for a yellow- or purple-colored corn target amongst aubergine distractors, half of which were yellow and half purple. Search was more efficient when the color of the target was familiar and early eye movements more likely to be directed to targets carrying a familiar color than an unfamiliar color. Experiment 2 introduced cues which predicted the target color at 80 % validity. Cue validity did not affect whether early fixations were to the target. Invalid cues, however, disrupted search efficiency for targets in an unfamiliar color whilst there was little cost to search efficiency for targets in their familiar color. These results generalized across items with different colors (Experiment 3). The data are consistent with early processes in selection being automatically modulated in a bottom-up manner to targets in their familiar color, even when expectancies are set for other colors.

  16. Top-down and bottom-up aerosol-cloud closure: towards understanding sources of uncertainty in deriving cloud shortwave radiative flux

    Science.gov (United States)

    Sanchez, Kevin J.; Roberts, Gregory C.; Calmer, Radiance; Nicoll, Keri; Hashimshoni, Eyal; Rosenfeld, Daniel; Ovadnevaite, Jurgita; Preissler, Jana; Ceburnis, Darius; O'Dowd, Colin; Russell, Lynn M.

    2017-08-01

    Top-down and bottom-up aerosol-cloud shortwave radiative flux closures were conducted at the Mace Head Atmospheric Research Station in Galway, Ireland, in August 2015. This study is part of the BACCHUS (Impact of Biogenic versus Anthropogenic emissions on Clouds and Climate: towards a Holistic UnderStanding) European collaborative project, with the goal of understanding key processes affecting aerosol-cloud shortwave radiative flux closures to improve future climate predictions and develop sustainable policies for Europe. Instrument platforms include ground-based unmanned aerial vehicles (UAVs)1 and satellite measurements of aerosols, clouds and meteorological variables. The ground-based and airborne measurements of aerosol size distributions and cloud condensation nuclei (CCN) concentration were used to initiate a 1-D microphysical aerosol-cloud parcel model (ACPM). UAVs were equipped for a specific science mission, with an optical particle counter for aerosol distribution profiles, a cloud sensor to measure cloud extinction or a five-hole probe for 3-D wind vectors. UAV cloud measurements are rare and have only become possible in recent years through the miniaturization of instrumentation. These are the first UAV measurements at Mace Head. ACPM simulations are compared to in situ cloud extinction measurements from UAVs to quantify closure in terms of cloud shortwave radiative flux. Two out of seven cases exhibit sub-adiabatic vertical temperature profiles within the cloud, which suggests that entrainment processes affect cloud microphysical properties and lead to an overestimate of simulated cloud shortwave radiative flux. Including an entrainment parameterization and explicitly calculating the entrainment fraction in the ACPM simulations both improved cloud-top radiative closure. Entrainment reduced the difference between simulated and observation-derived cloud-top shortwave radiative flux (δRF) by between 25 and 60 W m-2. After accounting for entrainment

  17. Top-down and Bottom-up aerosol-cloud-closure: towards understanding sources of unvertainty in deriving cloud radiative flux

    Science.gov (United States)

    Sanchez, K.; Roberts, G.; Calmer, R.; Nicoll, K.; Hashimshoni, E.; Rosenfeld, D.; Ovadnevaite, J.; Preissler, J.; Ceburnis, D.; O'Dowd, C. D. D.; Russell, L. M.

    2017-12-01

    Top-down and bottom-up aerosol-cloud shortwave radiative flux closures were conducted at the Mace Head atmospheric research station in Galway, Ireland in August 2015. Instrument platforms include ground-based, unmanned aerial vehicles (UAV), and satellite measurements of aerosols, clouds and meteorological variables. The ground-based and airborne measurements of aerosol size distributions and cloud condensation nuclei (CCN) concentration were used to initiate a 1D microphysical aerosol-cloud parcel model (ACPM). UAVs were equipped for a specific science mission, with an optical particle counter for aerosol distribution profiles, a cloud sensor to measure cloud extinction, or a 5-hole probe for 3D wind vectors. These are the first UAV measurements at Mace Head. ACPM simulations are compared to in-situ cloud extinction measurements from UAVs to quantify closure in terms of cloud shortwave radiative flux. Two out of seven cases exhibit sub-adiabatic vertical temperature profiles within the cloud, which suggests that entrainment processes affect cloud microphysical properties and lead to an overestimate of simulated cloud shortwave radiative flux. Including an entrainment parameterization and explicitly calculating the entrainment fraction in the ACPM simulations both improved cloud-top radiative closure. Entrainment reduced the difference between simulated and observation-derived cloud-top shortwave radiative flux (δRF) by between 25 W m-2 and 60 W m-2. After accounting for entrainment, satellite-derived cloud droplet number concentrations (CDNC) were within 30% of simulated CDNC. In cases with a well-mixed boundary layer, δRF is no greater than 20 W m-2 after accounting for cloud-top entrainment, and up to 50 W m-2 when entrainment is not taken into account. In cases with a decoupled boundary layer, cloud microphysical properties are inconsistent with ground-based aerosol measurements, as expected, and δRF is as high as 88 W m-2, even high (> 30 W m-2) after

  18. From War to Tolerance? Bottom-up and Top-down Approaches to (Rebuilding Interethnic Ties in the Areas of the Former Yugoslavia

    Directory of Open Access Journals (Sweden)

    Boris Banovac

    2014-01-01

    Full Text Available In recent history the Balkans passed through periods of conflict and violence typical of many post-imperial nation-states that are unable to establish lateral links with their neighbors without or outside the central (imperial connection. In a way, these states imitated historical path of imperial conquests. In this regard, ethnic conflicts that escalated into wars of the former Yugoslavia can be taken as examples of an erratic transformation of post-imperial into modern nation-states that are eager to build up democracy at home and develop peaceful coexistence with others in international environment. Nevertheless, not all multiethnic areas were caught up in violence (e.g. instances of “peace enclaves” in multiethnic areas in Croatia, Bosnia and Heregovina and in Kosovo. Through such examples, which will be illustrated with results of empirical research, we recognize potentials for building tolerance from below. On the other hand, in most other places peace was a follow up of post-conflict processes. In these cases, local potentials of ethnic tolerance were rather weak. The paper provides some examples illustrating regional differences in this regard within Croatia. Actually, the whole process of normalization of ethnic relations in peaceful terms is far from being linear and is hardly going smoothly. Some parts of national elites foster distance and antagonism against the ”others”. On the other hand, especially following EU accession of Croatia, nationalistic rhetoric significantly receded on the level of the official politics. The question is then whether the impact of policies in institutional sphere, both national and international, i.e. top-down approach, is decisive in shaping inter-ethnic relations. The conclusion is that the institutional, top-down arrangements of peace and tolerance cannot be sustainable without concomitant bottom-up processes on micro level, which theoretically corresponds to a “conformant policy” against

  19. Linking top-down and bottom-up approaches for assessing the vulnerability of a 100 % renewable energy system in Northern-Italy

    Science.gov (United States)

    Borga, Marco; Francois, Baptiste; Hingray, Benoit; Zoccatelli, Davide; Creutin, Jean-Dominique; brown, Casey

    2016-04-01

    Due to their variable and un-controllable features, integration of Variable Renewable Energies (e.g. solar-power, wind-power and hydropower, denoted as VRE) into the electricity network implies higher production variability and increased risk of not meeting demand. Two approaches are commonly used for assessing this risk and especially its evolution in a global change context (i.e. climate and societal changes); top-down and bottom-up approaches. The general idea of a top-down approach is to drive analysis of global change or of some key aspects of global change on their systems (e.g., the effects of the COP 21, of the deployment of Smart Grids, or of climate change) with chains of loosely linked simulation models within a predictive framework. The bottom-up approach aims to improve understanding of the dependencies between the vulnerability of regional systems and large-scale phenomenon from knowledge gained through detailed exploration of the response to change of the system of interest, which may reveal vulnerability thresholds, tipping points as well as potential opportunities. Brown et al. (2012) defined an analytical framework to merge these two approaches. The objective is to build, a set of Climate Response Functions (CRFs) putting in perspective i) indicators of desired states ("success") and undesired states ("failure") of a system as defined in collaboration with stakeholders 2) exhaustive exploration of the effects of uncertain forcings and imperfect system understanding on the response of the system itself to a plausible set of possible changes, implemented a with multi-dimensionally consistent "stress test" algorithm, and 3) a set "ex post" hydroclimatic and socioeconomic scenarios that provide insight into the differential effectiveness of alternative policies and serve as entry points for the provision of climate information to inform policy evaluation and choice. We adapted this approach for analyzing a 100 % renewable energy system within a region

  20. Effects of bottom-up and top-down intervention principles in emergent literacy in children at risk of developmental dyslexia: a longitudinal study.

    Science.gov (United States)

    Helland, Turid; Tjus, Tomas; Hovden, Marit; Ofte, Sonja; Heimann, Mikael

    2011-01-01

    This longitudinal study focused on the effects of two different principles of intervention in children at risk of developing dyslexia from 5 to 8 years old. The children were selected on the basis of a background questionnaire given to parents and preschool teachers, with cognitive and functional magnetic resonance imaging results substantiating group differences in neuropsychological processes associated with phonology, orthography, and phoneme-grapheme correspondence (i.e., alphabetic principle). The two principles of intervention were bottom-up (BU), "from sound to meaning", and top-down (TD), "from meaning to sound." Thus, four subgroups were established: risk/BU, risk/TD, control/BU, and control/TD. Computer-based training took place for 2 months every spring, and cognitive assessments were performed each fall of the project period. Measures of preliteracy skills for reading and spelling were phonological awareness, working memory, verbal learning, and letter knowledge. Literacy skills were assessed by word reading and spelling. At project end the control group scored significantly above age norm, whereas the risk group scored within the norm. In the at-risk group, training based on the BU principle had the strongest effects on phonological awareness and working memory scores, whereas training based on the TD principle had the strongest effects on verbal learning, letter knowledge, and literacy scores. It was concluded that appropriate, specific, data-based intervention starting in preschool can mitigate literacy impairment and that interventions should contain BU training for preliteracy skills and TD training for literacy training.

  1. Middle-Out Approaches to Reform of University Teaching and Learning: Champions striding between the top-down and bottom-up approaches

    Directory of Open Access Journals (Sweden)

    Rick Cummings

    2005-03-01

    Full Text Available In recent years, Australian universities have been driven by a diversity of external forces, including funding cuts, massification of higher education, and changing student demographics, to reform their relationship with students and improve teaching and learning, particularly for those studying off-campus or part-time. Many universities have responded to these forces either through formal strategic plans developed top-down by executive staff or through organic developments arising from staff in a bottom-up approach. By contrast, much of Murdoch University’s response has been led by a small number of staff who have middle management responsibilities and who have championed the reform of key university functions, largely in spite of current policy or accepted practice. This paper argues that the ‘middle-out’ strategy has both a basis in change management theory and practice, and a number of strengths, including low risk, low cost, and high sustainability. Three linked examples of middle-out change management in teaching and learning at Murdoch University are described and the outcomes analyzed to demonstrate the benefits and pitfalls of this approach.

  2. Gender effect in human brain responses to bottom-up and top-down attention using the EEG 3D-Vector Field Tomography.

    Science.gov (United States)

    Kosmidou, Vasiliki E; Adam, Aikaterini; Papadaniil, Chrysa D; Tsolaki, Magda; Hadjileontiadis, Leontios J; Kompatsiaris, Ioannis

    2015-01-01

    The effect of gender in rapidly allocating attention to objects, features or locations, as reflected in brain activity, is examined in this study. A visual-attention task, consisting of bottom-up (visual pop-out) and top-down (visual search) conditions during stimuli of four triangles, i.e., a target and three distractors, was engaged. In pop-out condition, both color and orientation of the distractors differed from target, while in search condition they differed only in orientation. During the task, high-density EEG (256 channels) data were recorded and analyzed by means of behavioral, event-related potentials, i.e., the P300 component and brain source localization analysis using 3D-Vector Field Tomography (3D-VFT). Twenty subjects (half female; 32±4.7 years old) participated in the experiments, performing 60 trials for each condition. Behavioral analysis revealed that both female and male outperformed in the pop-out condition compared to the search one, with respect to accuracy and reaction time, whereas no gender-related statistical significant differences were found. Nevertheless, in the search condition, higher P300 amplitudes were detected for females compared to males (p left inferior frontal and superior temporal gyri, whereas in males it was found in the right inferior frontal and superior temporal gyri. Overall, the experimental results show that visual attention depends on contributions from different brain lateralization linked to gender, posing important implications in studying developmental disorders, characterized by gender differences.

  3. Combined top-down and bottom-up climate change impact assessment for the hydrological system in the Vu Gia- Thu Bon River Basin.

    Science.gov (United States)

    Tra, Tran Van; Thinh, Nguyen Xuan; Greiving, Stefan

    2018-07-15

    Vu Gia- Thu Bon (VGTB) River Basin, located in the Central Coastal zone of Viet Nam currently faces water shortage. Climate change is expected to exacerbate the challenge. Therefore, there is a need to study the impacts of climate change on water shortage in the river basin. The study adopts a combined top-down and bottom-up climate change impact assessment to address the impacts of climate change on water shortage in the VGTB River Basin. A MIKE BASIN water balance model for the river basin was established to simulate the response of the hydrological system. Simulations were performed through parametrically varying temperature and precipitation to determine the vulnerability space of water shortage. General Circulation Models (GCMs) were then utilized to provide climate projections for the river basin. The output from GCMs was then mapped onto the vulnerability space determined earlier. In total, 9 out of 55 water demand nodes in the simulation are expected to face problematic conditions as future climate changes. Copyright © 2018 Elsevier B.V. All rights reserved.

  4. Evolutionary Steps in the Emergence of Life Deduced from the Bottom-Up Approach and GADV Hypothesis (Top-Down Approach).

    Science.gov (United States)

    Ikehara, Kenji

    2016-01-26

    It is no doubt quite difficult to solve the riddle of the origin of life. So, firstly, I would like to point out the kinds of obstacles there are in solving this riddle and how we should tackle these difficult problems, reviewing the studies that have been conducted so far. After that, I will propose that the consecutive evolutionary steps in a timeline can be rationally deduced by using a common event as a juncture, which is obtained by two counter-directional approaches: one is the bottom-up approach through which many researchers have studied the origin of life, and the other is the top-down approach, through which I established the [GADV]-protein world hypothesis or GADV hypothesis on the origin of life starting from a study on the formation of entirely new genes in extant microorganisms. Last, I will describe the probable evolutionary process from the formation of Earth to the emergence of life, which was deduced by using a common event-the establishment of the first genetic code encoding [GADV]-amino acids-as a juncture for the results obtained from the two approaches.

  5. Evolutionary Steps in the Emergence of Life Deduced from the Bottom-Up Approach and GADV Hypothesis (Top-Down Approach

    Directory of Open Access Journals (Sweden)

    Kenji Ikehara

    2016-01-01

    Full Text Available It is no doubt quite difficult to solve the riddle of the origin of life. So, firstly, I would like to point out the kinds of obstacles there are in solving this riddle and how we should tackle these difficult problems, reviewing the studies that have been conducted so far. After that, I will propose that the consecutive evolutionary steps in a timeline can be rationally deduced by using a common event as a juncture, which is obtained by two counter-directional approaches: one is the bottom-up approach through which many researchers have studied the origin of life, and the other is the top-down approach, through which I established the [GADV]-protein world hypothesis or GADV hypothesis on the origin of life starting from a study on the formation of entirely new genes in extant microorganisms. Last, I will describe the probable evolutionary process from the formation of Earth to the emergence of life, which was deduced by using a common event—the establishment of the first genetic code encoding [GADV]-amino acids—as a juncture for the results obtained from the two approaches.

  6. Ultra rapidly dissolving repaglinide nanosized crystals prepared via bottom-up and top-down approach: influence of food on pharmacokinetics behavior.

    Science.gov (United States)

    Gadadare, Rahul; Mandpe, Leenata; Pokharkar, Varsha

    2015-08-01

    The present work was undertaken with the objectives of improving the dissolution velocity, related oral bioavailability, and minimizing the fasted/fed state variability of repaglinide, a poorly water-soluble anti-diabetic active by exploring the principles of nanotechnology. Nanocrystal formulations were prepared by both top-down and bottom-up approaches. These approaches were compared in light of their ability to provide the formulation stability in terms of particle size. Soluplus® was used as a stabilizer and Kolliphor™ E-TPGS was used as an oral absorption enhancer. In vitro dissolution profiles were investigated in distilled water, fasted and fed state simulated gastric fluid, and compared with the pure repaglinide. In vivo pharmacokinetics was performed in both the fasted and fed state using Wistar rats. Oral hypoglycemic activity was also assessed in streptozotocin-induced diabetic rats. Nanocrystals TD-A and TD-B showed 19.86 and 25.67-fold increase in saturation solubility, respectively, when compared with pure repaglinide. Almost 10 (TD-A) and 15 (TD-B)-fold enhancement in the oral bioavailability of nanocrystals was observed regardless of the fasted/fed state compared to pure repaglinide. Nanocrystal formulations also demonstrated significant (p < 0.001) hypoglycemic activity with faster onset (less than 30 min) and prolonged duration (up to 8 h) compared to pure repaglinide (after 60 min; up to 4 h, respectively).

  7. Top-down impact through a bottom-up mechanism: the effect of limpet grazing on growth, productivity and carbon allocation of Zostera marina L. (eelgrass).

    Science.gov (United States)

    Zimmerman, Richard C; Kohrs, Donald G; Alberte, Randall S

    1996-09-01

    The unusual appearance of a commensal eelgrass limpet [Tectura depicta (Berry)] from southern California at high density (up to 10 shoot -1 ) has coincided with the catastrophic decline of a subtidal Zostera marina L. meadow in Monterey Bay, California. Some commensal limpets graze the chloroplast-rich epidermis of eelgrass leaves, but were not known to affect seagrass growth or productivity. We evaluated the effect on eelgrass productivity of grazing by limpets maintained at natural densities (8±2 shoot -1 ) in a natural light mesocosm for 45 days. Growth rates, carbon reserves, root proliferation and net photosynthesis of grazed plants were 50-80% below those of ungrazed plants, but biomass-specific respiration was unaffected. The daily period of irradiance-saturated photosynthesis (H sat ) needed to maintain positive carbon balance in grazed plants approached 13.5 h, compared with 5-6 h for ungrazed plants. The amount of carbon allocated to roots of ungrazed plants was 800% higher than for grazed plants. By grazing the chlorophyll-rich epidermis, T. depicta induced carbon limitation in eelgrass growing in an other-wise light-replete environment. Continued northward movement of T. depicta, may have significant impacts on eelgrass production and population dynamics in the northeast Pacific, even thought this limpet consumes very little plant biomass. This interaction is a dramatic example of top-down control (grazing/predation) of eelgrass productivity and survival operating via a bottom-up mechanism (photosynthesis limitation).

  8. Climate change, pink salmon, and the nexus between bottom-up and top-down forcing in the subarctic Pacific Ocean and Bering Sea.

    Science.gov (United States)

    Springer, Alan M; van Vliet, Gus B

    2014-05-06

    Climate change in the last century was associated with spectacular growth of many wild Pacific salmon stocks in the North Pacific Ocean and Bering Sea, apparently through bottom-up forcing linking meteorology to ocean physics, water temperature, and plankton production. One species in particular, pink salmon, became so numerous by the 1990s that they began to dominate other species of salmon for prey resources and to exert top-down control in the open ocean ecosystem. Information from long-term monitoring of seabirds in the Aleutian Islands and Bering Sea reveals that the sphere of influence of pink salmon is much larger than previously known. Seabirds, pink salmon, other species of salmon, and by extension other higher-order predators, are tightly linked ecologically and must be included in international management and conservation policies for sustaining all species that compete for common, finite resource pools. These data further emphasize that the unique 2-y cycle in abundance of pink salmon drives interannual shifts between two alternate states of a complex marine ecosystem.

  9. Dissociated roles of the inferior frontal gyrus and superior temporal sulcus in audiovisual processing: top-down and bottom-up mismatch detection.

    Science.gov (United States)

    Uno, Takeshi; Kawai, Kensuke; Sakai, Katsuyuki; Wakebe, Toshihiro; Ibaraki, Takuya; Kunii, Naoto; Matsuo, Takeshi; Saito, Nobuhito

    2015-01-01

    Visual inputs can distort auditory perception, and accurate auditory processing requires the ability to detect and ignore visual input that is simultaneous and incongruent with auditory information. However, the neural basis of this auditory selection from audiovisual information is unknown, whereas integration process of audiovisual inputs is intensively researched. Here, we tested the hypothesis that the inferior frontal gyrus (IFG) and superior temporal sulcus (STS) are involved in top-down and bottom-up processing, respectively, of target auditory information from audiovisual inputs. We recorded high gamma activity (HGA), which is associated with neuronal firing in local brain regions, using electrocorticography while patients with epilepsy judged the syllable spoken by a voice while looking at a voice-congruent or -incongruent lip movement from the speaker. The STS exhibited stronger HGA if the patient was presented with information of large audiovisual incongruence than of small incongruence, especially if the auditory information was correctly identified. On the other hand, the IFG exhibited stronger HGA in trials with small audiovisual incongruence when patients correctly perceived the auditory information than when patients incorrectly perceived the auditory information due to the mismatched visual information. These results indicate that the IFG and STS have dissociated roles in selective auditory processing, and suggest that the neural basis of selective auditory processing changes dynamically in accordance with the degree of incongruity between auditory and visual information.

  10. Top-down/bottom-up description of electricity sector for Switzerland using the GEM-E3 computable general equilibrium model

    International Nuclear Information System (INIS)

    Krakowski, R. A.

    2006-06-01

    Participation of the Paul Scherrer Institute (PSI) in the advancement and extension of the multi-region, Computable General Equilibrium (CGE) model GEM-E3 (CES/KUL, 2002) focused primarily on two top-level facets: a) extension of the model database and model calibration, particularly as related to the second component of this study, which is; b) advancement of the dynamics of innovation and investment, primarily through the incorporation of Exogenous Technical Learning (ETL) into he Bottom-Up (BU, technology-based) part of the dynamic upgrade; this latter activity also included the completion of the dynamic coupling of the BU description of the electricity sector with the 'Top-Down' (TD, econometric) description of the economy inherent to the GEM-E3 CGE model. The results of this two- component study are described in two parts that have been combined in this single summary report: Part I describes the methodology and gives illustrative results from the BUTD integration, as well as describing the approach to and giving preliminary results from incorporating an ETL description into the BU component of the overall model; Part II reports on the calibration component of task in terms of: a) formulating a BU technology database for Switzerland based on previous work; incorporation of that database into the GEM-E3 model; and calibrating the BU database with the TD database embodied in the (Swiss) Social Accounting Matrix (SAM). The BUTD coupling along with the ETL incorporation described in Part I represent the major effort embodied in this investigation, but this effort could not be completed without the calibration preamble reported herein as Part II. A brief summary of the scope of each of these key study components is given. (author)

  11. Top-down/bottom-up description of electricity sector for Switzerland using the GEM-E3 computable general equilibrium model

    Energy Technology Data Exchange (ETDEWEB)

    Krakowski, R. A

    2006-06-15

    Participation of the Paul Scherrer Institute (PSI) in the advancement and extension of the multi-region, Computable General Equilibrium (CGE) model GEM-E3 (CES/KUL, 2002) focused primarily on two top-level facets: a) extension of the model database and model calibration, particularly as related to the second component of this study, which is; b) advancement of the dynamics of innovation and investment, primarily through the incorporation of Exogenous Technical Learning (ETL) into he Bottom-Up (BU, technology-based) part of the dynamic upgrade; this latter activity also included the completion of the dynamic coupling of the BU description of the electricity sector with the 'Top-Down' (TD, econometric) description of the economy inherent to the GEM-E3 CGE model. The results of this two- component study are described in two parts that have been combined in this single summary report: Part I describes the methodology and gives illustrative results from the BUTD integration, as well as describing the approach to and giving preliminary results from incorporating an ETL description into the BU component of the overall model; Part II reports on the calibration component of task in terms of: a) formulating a BU technology database for Switzerland based on previous work; incorporation of that database into the GEM-E3 model; and calibrating the BU database with the TD database embodied in the (Swiss) Social Accounting Matrix (SAM). The BUTD coupling along with the ETL incorporation described in Part I represent the major effort embodied in this investigation, but this effort could not be completed without the calibration preamble reported herein as Part II. A brief summary of the scope of each of these key study components is given. (author)

  12. The protection pyramid approach : A contribution to the protection of internally displaced persons by combining bottom up coping mechanisms and top down protection strategies into a partnership approach to protection

    NARCIS (Netherlands)

    Janssen, Laura

    2017-01-01

    In het huidige debat over de bescherming van Intern Ontheemde Mensen (IDPs) spelen twee groepen actoren een rol. Enerzijds de ontheemden zelf (Bottom Up actoren genoemd), anderzijds de Staat, niet-Statelijke actoren en andere hulpverleners (Top Down actoren). Van oudsher wordt er meer aandacht

  13. Top-down and bottom-up aerosol–cloud closure: towards understanding sources of uncertainty in deriving cloud shortwave radiative flux

    Directory of Open Access Journals (Sweden)

    K. J. Sanchez

    2017-08-01

    Full Text Available Top-down and bottom-up aerosol–cloud shortwave radiative flux closures were conducted at the Mace Head Atmospheric Research Station in Galway, Ireland, in August 2015. This study is part of the BACCHUS (Impact of Biogenic versus Anthropogenic emissions on Clouds and Climate: towards a Holistic UnderStanding European collaborative project, with the goal of understanding key processes affecting aerosol–cloud shortwave radiative flux closures to improve future climate predictions and develop sustainable policies for Europe. Instrument platforms include ground-based unmanned aerial vehicles (UAVs1 and satellite measurements of aerosols, clouds and meteorological variables. The ground-based and airborne measurements of aerosol size distributions and cloud condensation nuclei (CCN concentration were used to initiate a 1-D microphysical aerosol–cloud parcel model (ACPM. UAVs were equipped for a specific science mission, with an optical particle counter for aerosol distribution profiles, a cloud sensor to measure cloud extinction or a five-hole probe for 3-D wind vectors. UAV cloud measurements are rare and have only become possible in recent years through the miniaturization of instrumentation. These are the first UAV measurements at Mace Head. ACPM simulations are compared to in situ cloud extinction measurements from UAVs to quantify closure in terms of cloud shortwave radiative flux. Two out of seven cases exhibit sub-adiabatic vertical temperature profiles within the cloud, which suggests that entrainment processes affect cloud microphysical properties and lead to an overestimate of simulated cloud shortwave radiative flux. Including an entrainment parameterization and explicitly calculating the entrainment fraction in the ACPM simulations both improved cloud-top radiative closure. Entrainment reduced the difference between simulated and observation-derived cloud-top shortwave radiative flux (δRF by between 25 and 60 W m−2. After

  14. The control of automatic imitation based on bottom-up and top-down cues to animacy: insights from brain and behavior.

    Science.gov (United States)

    Klapper, André; Ramsey, Richard; Wigboldus, Daniël; Cross, Emily S

    2014-11-01

    Humans automatically imitate other people's actions during social interactions, building rapport and social closeness in the process. Although the behavioral consequences and neural correlates of imitation have been studied extensively, little is known about the neural mechanisms that control imitative tendencies. For example, the degree to which an agent is perceived as human-like influences automatic imitation, but it is not known how perception of animacy influences brain circuits that control imitation. In the current fMRI study, we examined how the perception and belief of animacy influence the control of automatic imitation. Using an imitation-inhibition paradigm that involves suppressing the tendency to imitate an observed action, we manipulated both bottom-up (visual input) and top-down (belief) cues to animacy. Results show divergent patterns of behavioral and neural responses. Behavioral analyses show that automatic imitation is equivalent when one or both cues to animacy are present but reduces when both are absent. By contrast, right TPJ showed sensitivity to the presence of both animacy cues. Thus, we demonstrate that right TPJ is biologically tuned to control imitative tendencies when the observed agent both looks like and is believed to be human. The results suggest that right TPJ may be involved in a specialized capacity to control automatic imitation of human agents, rather than a universal process of conflict management, which would be more consistent with generalist theories of imitative control. Evidence for specialized neural circuitry that "controls" imitation offers new insight into developmental disorders that involve atypical processing of social information, such as autism spectrum disorders.

  15. Top-down model estimates, bottom-up inventories, and future projections of global natural and anthropogenic emissions of nitrous oxide

    Science.gov (United States)

    Davidson, E. A.; Kanter, D.

    2013-12-01

    Nitrous oxide (N2O) is the third most abundantly emitted greenhouse gas and the largest remaining emitted ozone depleting substance. It is a product of nitrifying and denitrifying bacteria in soils, sediments and water bodies. Humans began to disrupt the N cycle in the preindustrial era as they expanded agricultural land, used fire for land clearing and management, and cultivated leguminous crops that carry out biological N fixation. This disruption accelerated after the industrial revolution, especially as the use of synthetic N fertilizers became common after 1950. Here we present findings from a new United Nations Environment Programme report, in which we constrain estimates of the anthropogenic and natural emissions of N2O and consider scenarios for future emissions. Inventory-based estimates of natural emissions from terrestrial, marine and atmospheric sources range from 10 to 12 Tg N2O-N/yr. Similar values can be derived for global N2O emissions that were predominantly natural before the industrial revolution. While there was inter-decadal variability, there was little or no consistent trend in atmospheric N2O concentrations between 1730 and 1850, allowing us to assume near steady state. Assuming an atmospheric lifetime of 120 years, the 'top-down' estimate of pre-industrial emissions of 11 Tg N2O-N/yr is consistent with the bottom-up inventories for natural emissions, although the former includes some modest pre-industrial anthropogenic effects (probably business-as-usual scenarios over the period 2013-2050 is ~102 Tg N2O-N; equivalent to ~48 Gt CO2e or ~2730 kt ozone depleting potential. The impact of growing demand for biofuels is highly uncertain, ranging from trivial to the most significant N2O source to date, depending on the types of plants, their nutrient management, the amount of land used for their cultivation, and the fates of their waste products.

  16. Understanding microelectronics a top-down approach

    CERN Document Server

    Maloberti, Franco

    2011-01-01

    The microelectronics evolution has given rise to many modern benefits but has also changed design methods and attitudes to learning. Technology advancements shifted focus from simple circuits to complex systems with major attention to high-level descriptions. The design methods moved from a bottom-up to a top-down approach. For today's students, the most beneficial approach to learning is this top-down method that demonstrates a global view of electronics before going into specifics. Franco Maloberti uses this approach to explain the fundamentals of electronics, such as processing functions,

  17. Bottom-up and top-down triggers of diversification: A new look at the evolutionary ecology of scavenging amphipods in the deep sea

    Science.gov (United States)

    Havermans, Charlotte; Smetacek, Victor

    2018-05-01

    The initial, anthropocentric view of the deep ocean was that of a hostile environment inhabited by organisms rendered lethargic by constant high pressure, low temperature and sparse food supply, hence evolving slowly. This conceptual framework of a spatially and temporally homogeneous, connected, strongly bottom-up controlled habitat implied a strong constraint on, or poor incentive for, speciation. Hence, the discovery in the late 1960s of high species diversity of abyssal benthic invertebrates came as a surprise. Since then, the slow-motion view of deep-sea ecology and evolution has speeded up and diversified in the light of increasing evidence accumulating from in situ visual observations complemented by molecular and other tools. The emerging picture is that of a much livelier, highly diversified and more complex deep-sea fauna than previously assumed. In this review we examine the consequences of the incoming information for developing a broader view of evolutionary ecology in the deep sea, and for scavenging amphipods in particular. We revisit the food supply to the deep-sea floor and hypothesize that the dead bodies of animals, ranging from zooplankton to large fish are likely to be a more important source of food than their friable faeces. Camera observations of baited traps indicate that amphipod carrion-feeders arrive within hours at the bait which continues to draw new individuals for days to months later, presumably by scent trails in tidal currents. We explore the different stages of food acquisition upon which natural selection may have acted, from detection to ingestion, and discuss the possibility of a broader range of food acquisition strategies, including predation and specializations. Although currently neglected in deep-sea ecology, top-down factors are likely to play a more important role in the evolution of deep-sea organisms. Predation on amphipods at baits by bathyal and abyssal fishes, and large predatory crustaceans in the hadal zone, is

  18. Reconciling Basin-Scale Top-Down and Bottom-Up Methane Emission Measurements for Onshore Oil and Gas Development: Cooperative Research and Development Final Report, CRADA Number CRD-14-572

    Energy Technology Data Exchange (ETDEWEB)

    Heath, Garvin A. [National Renewable Energy Lab. (NREL), Golden, CO (United States)

    2017-12-04

    The overall objective of the Research Partnership to Secure Energy for America (RPSEA)-funded research project is to develop independent estimates of methane emissions using top-down and bottom-up measurement approaches and then to compare the estimates, including consideration of uncertainty. Such approaches will be applied at two scales: basin and facility. At facility scale, multiple methods will be used to measure methane emissions of the whole facility (controlled dual tracer and single tracer releases, aircraft-based mass balance and Gaussian back-trajectory), which are considered top-down approaches. The bottom-up approach will sum emissions from identified point sources measured using appropriate source-level measurement techniques (e.g., high-flow meters). At basin scale, the top-down estimate will come from boundary layer airborne measurements upwind and downwind of the basin, using a regional mass balance model plus approaches to separate atmospheric methane emissions attributed to the oil and gas sector. The bottom-up estimate will result from statistical modeling (also known as scaling up) of measurements made at selected facilities, with gaps filled through measurements and other estimates based on other studies. The relative comparison of the bottom-up and top-down estimates made at both scales will help improve understanding of the accuracy of the tested measurement and modeling approaches. The subject of this CRADA is NREL's contribution to the overall project. This project resulted from winning a competitive solicitation no. RPSEA RFP2012UN001, proposal no. 12122-95, which is the basis for the overall project. This Joint Work Statement (JWS) details the contributions of NREL and Colorado School of Mines (CSM) in performance of the CRADA effort.

  19. Perceptual learning: top to bottom.

    Science.gov (United States)

    Amitay, Sygal; Zhang, Yu-Xuan; Jones, Pete R; Moore, David R

    2014-06-01

    Perceptual learning has traditionally been portrayed as a bottom-up phenomenon that improves encoding or decoding of the trained stimulus. Cognitive skills such as attention and memory are thought to drive, guide and modulate learning but are, with notable exceptions, not generally considered to undergo changes themselves as a result of training with simple perceptual tasks. Moreover, shifts in threshold are interpreted as shifts in perceptual sensitivity, with no consideration for non-sensory factors (such as response bias) that may contribute to these changes. Accumulating evidence from our own research and others shows that perceptual learning is a conglomeration of effects, with training-induced changes ranging from the lowest (noise reduction in the phase locking of auditory signals) to the highest (working memory capacity) level of processing, and includes contributions from non-sensory factors that affect decision making even on a "simple" auditory task such as frequency discrimination. We discuss our emerging view of learning as a process that increases the signal-to-noise ratio associated with perceptual tasks by tackling noise sources and inefficiencies that cause performance bottlenecks, and present some implications for training populations other than young, smart, attentive and highly-motivated college students. Crown Copyright © 2013. Published by Elsevier Ltd. All rights reserved.

  20. Transcriptomics-guided bottom-up and top-down venomics of neonate and adult specimens of the arboreal rear-fanged Brown Treesnake, Boiga irregularis, from Guam.

    Science.gov (United States)

    Pla, Davinia; Petras, Daniel; Saviola, Anthony J; Modahl, Cassandra M; Sanz, Libia; Pérez, Alicia; Juárez, Elena; Frietze, Seth; Dorrestein, Pieter C; Mackessy, Stephen P; Calvete, Juan J

    2018-03-01

    neonate and adult B. irregularis from Guam, further highlighting evolutionary trends in venom composition among rear-fanged venomous snakes. The Brown Treesnake (Boiga irregularis) has caused extensive ecological and economic damage to the island of Guam where it has become a classic example of the negative impacts of invasive species. In the current study, we report the first combined transcriptomic and proteomic analysis of B. irregularis venom of Guam origin. The transcriptome of an adult snake contained toxin sequences belonging to 18 protein families, with three-finger toxin (3FTx) isoforms being the most abundant and representing 94% of all venom protein transcript reads. Our bottom-up and top-down venomic analyses confirmed that 3FTxs are the major components of B. irregularis venom, and a comparative analysis of neonate and adult venoms demonstrate a clear ontogenetic shift in toxin abundance, likely driven by dietary variation between the two age classes. Second-generation antivenomics and Western blot analysis using purified anti-Brown Treesnake rabbit serum IgGs (anti-BTS IgGs) showed strong immunoreactivity toward B. irregularis venom. Interestingly, our anti-BTS IgGs did not cross-react with 3FTxs found in several other rear-fanged snake venoms, or against 3FTxs in the venom of the elapid Ophiophagus hannah, indicating that epitopes in these 3FTx molecules are quite distinct. Copyright © 2017 Elsevier B.V. All rights reserved.

  1. Exploring the underlying structure of mental disorders: cross-diagnostic differences and similarities from a network perspective using both a top-down and a bottom-up approach.

    Science.gov (United States)

    Wigman, J T W; van Os, J; Borsboom, D; Wardenaar, K J; Epskamp, S; Klippel, A; Viechtbauer, W; Myin-Germeys, I; Wichers, M

    2015-08-01

    It has been suggested that the structure of psychopathology is best described as a complex network of components that interact in dynamic ways. The goal of the present paper was to examine the concept of psychopathology from a network perspective, combining complementary top-down and bottom-up approaches using momentary assessment techniques. A pooled Experience Sampling Method (ESM) dataset of three groups (individuals with a diagnosis of depression, psychotic disorder or no diagnosis) was used (pooled N = 599). The top-down approach explored the network structure of mental states across different diagnostic categories. For this purpose, networks of five momentary mental states ('cheerful', 'content', 'down', 'insecure' and 'suspicious') were compared between the three groups. The complementary bottom-up approach used principal component analysis to explore whether empirically derived network structures yield meaningful higher order clusters. Individuals with a clinical diagnosis had more strongly connected moment-to-moment network structures, especially the depressed group. This group also showed more interconnections specifically between positive and negative mental states than the psychotic group. In the bottom-up approach, all possible connections between mental states were clustered into seven main components that together captured the main characteristics of the network dynamics. Our combination of (i) comparing network structure of mental states across three diagnostically different groups and (ii) searching for trans-diagnostic network components across all pooled individuals showed that these two approaches yield different, complementary perspectives in the field of psychopathology. The network paradigm therefore may be useful to map transdiagnostic processes.

  2. Top Down proteomics: Facts and perspectives

    Energy Technology Data Exchange (ETDEWEB)

    Catherman, Adam D.; Skinner, Owen S.; Kelleher, Neil L., E-mail: n-kelleher@northwestern.edu

    2014-03-21

    Highlights: • Top Down versus Bottom Up proteomics analysis. • Separations methods for Top Down proteomics. • Developments in mass spectrometry instrumentation and fragmentation. • Native mass spectrometry. - Abstract: The rise of the “Top Down” method in the field of mass spectrometry-based proteomics has ushered in a new age of promise and challenge for the characterization and identification of proteins. Injecting intact proteins into the mass spectrometer allows for better characterization of post-translational modifications and avoids several of the serious “inference” problems associated with peptide-based proteomics. However, successful implementation of a Top Down approach to endogenous or other biologically relevant samples often requires the use of one or more forms of separation prior to mass spectrometric analysis, which have only begun to mature for whole protein MS. Recent advances in instrumentation have been used in conjunction with new ion fragmentation using photons and electrons that allow for better (and often complete) protein characterization on cases simply not tractable even just a few years ago. Finally, the use of native electrospray mass spectrometry has shown great promise for the identification and characterization of whole protein complexes in the 100 kDa to 1 MDa regime, with prospects for complete compositional analysis for endogenous protein assemblies a viable goal over the coming few years.

  3. Top Down proteomics: Facts and perspectives

    International Nuclear Information System (INIS)

    Catherman, Adam D.; Skinner, Owen S.; Kelleher, Neil L.

    2014-01-01

    Highlights: • Top Down versus Bottom Up proteomics analysis. • Separations methods for Top Down proteomics. • Developments in mass spectrometry instrumentation and fragmentation. • Native mass spectrometry. - Abstract: The rise of the “Top Down” method in the field of mass spectrometry-based proteomics has ushered in a new age of promise and challenge for the characterization and identification of proteins. Injecting intact proteins into the mass spectrometer allows for better characterization of post-translational modifications and avoids several of the serious “inference” problems associated with peptide-based proteomics. However, successful implementation of a Top Down approach to endogenous or other biologically relevant samples often requires the use of one or more forms of separation prior to mass spectrometric analysis, which have only begun to mature for whole protein MS. Recent advances in instrumentation have been used in conjunction with new ion fragmentation using photons and electrons that allow for better (and often complete) protein characterization on cases simply not tractable even just a few years ago. Finally, the use of native electrospray mass spectrometry has shown great promise for the identification and characterization of whole protein complexes in the 100 kDa to 1 MDa regime, with prospects for complete compositional analysis for endogenous protein assemblies a viable goal over the coming few years

  4. Toward consistency between trends in bottom-up CO2 emissions and top-down atmospheric measurements in the Los Angeles megacity

    Directory of Open Access Journals (Sweden)

    S. Newman

    2016-03-01

    Full Text Available Large urban emissions of greenhouse gases result in large atmospheric enhancements relative to background that are easily measured. Using CO2 mole fractions and Δ14C and δ13C values of CO2 in the Los Angeles megacity observed in inland Pasadena (2006–2013 and coastal Palos Verdes peninsula (autumn 2009–2013, we have determined time series for CO2 contributions from fossil fuel combustion (Cff for both sites and broken those down into contributions from petroleum and/or gasoline and natural gas burning for Pasadena. We find a 10 % reduction in Pasadena Cff during the Great Recession of 2008–2010, which is consistent with the bottom-up inventory determined by the California Air Resources Board. The isotopic variations and total atmospheric CO2 from our observations are used to infer seasonality of natural gas and petroleum combustion. The trend of CO2 contributions to the atmosphere from natural gas combustion is out of phase with the seasonal cycle of total natural gas combustion seasonal patterns in bottom-up inventories but is consistent with the seasonality of natural gas usage by the area's electricity generating power plants. For petroleum, the inferred seasonality of CO2 contributions from burning petroleum is delayed by several months relative to usage indicated by statewide gasoline taxes. Using the high-resolution Hestia-LA data product to compare Cff from parts of the basin sampled by winds at different times of year, we find that variations in observed fossil fuel CO2 reflect seasonal variations in wind direction. The seasonality of the local CO2 excess from fossil fuel combustion along the coast, on Palos Verdes peninsula, is higher in autumn and winter than spring and summer, almost completely out of phase with that from Pasadena, also because of the annual variations of winds in the region. Variations in fossil fuel CO2 signals are consistent with sampling the bottom-up Hestia-LA fossil CO2 emissions product for sub

  5. Improved Understanding of Microbial Iron and Sulfate Reduction Through a Combination of Bottom-up and Top-down Functional Proteomics Assays

    Energy Technology Data Exchange (ETDEWEB)

    Richardson, Ruth [Cornell Univ., Ithaca, NY (United States)

    2016-02-28

    Our overall goal was to improve the understanding of microbial iron and sulfate reduction by evaluating a diverse iron and sulfate reducing organisms utilizing a multi-omics approach combining “top-down” and “bottom-up” omics methodologies. We initiated one of the first combined comparative genomics, shotgun proteomics, RTqPCR, and heterologous expression studies in pursuit of our project objectives. Within the first year of this project, we created a new bioinformatics tool for ortholog identification (“SPOCS”). SPOCS is described in our publication, Curtis et al., 2013. Using this tool we were able to identify conserved orthologous groups across diverse iron and sulfate reducing microorganisms from Firmicutes, gamma-proteobacteria and delta-proteobacteria. For six iron and sulfate reducers we also performed shotgun proteomics (“bottom-up” proteomics including accurate mass and time (AMT) tag and iTRAQ approaches). Cultures include Gram (-) and Gram (+) microbes. Gram (-) were: Geobacter sulfureducens (grown on iron citrate and fumarate), Geobacter bemidjiensis (grown on iron citrate and fumarate), Shewanella oneidiensis (grown on iron citrate and fumarate) and Anaeromyxobacter dehalogenans (grown on iron citrate and fumarate). Although all cultures grew on insoluble iron, the iron precipitates interfered with protein extraction and analysis; which remains a major challenge for researchers in disparate study systems. Among the Gram (-) organisms studied, Anaeromyxobacter dehalogenans remains the most poorly characterized. Yet, it is arguably the most versatile organisms we studied. In this work we have used comparative proteomics to hypothesize which two of the dozens of predicted c-type cytochromes within Anaeromyxobacter dehalogenans may be directly involved in soluble iron reduction. Unfortunately, heterologous expression of these Anaeromyxobacter dehalogenans ctype cytochromes led to poor protein production and/or formation of inclusion bodies

  6. Top-down cellular pyramids

    Energy Technology Data Exchange (ETDEWEB)

    Wu, A Y; Rosenfeld, A

    1983-10-01

    A cellular pyramid is an exponentially tapering stack of arrays of processors (cells), where each cell is connected to its neighbors (siblings) on its own level, to a parent on the level above, and to its children on the level below. It is shown that in some situations, if information flows top-down only, from fathers to sons, then a cellular pyramid may be no faster than a one-level cellular array; but it may be possible to use simpler cells in the pyramid case. 23 references.

  7. The top-down reflooding model in the Cathare code

    International Nuclear Information System (INIS)

    Bartak, J.; Bestion, D.; Haapalehto, T.

    1993-01-01

    A top-down reflooding model was developed for the French best-estimate thermalhydraulic code CATHARE. The paper presents the current state of development of this model. Based on a literature survey and on compatibility considerations with respect to the existing CATHARE bottom reflooding package, a falling film top-down reflooding model was developed and implemented into CATHARE version 1.3E. Following a brief review of previous work, the paper describes the most important features of the model. The model was validated with the WINFRITH single tube top-down reflooding experiment and with the REWET - II simultaneous bottom and top-down reflooding experiment in rod bundle geometry. The results demonstrate the ability of the new package to describe the falling film rewetting phenomena and the main parametric trends both in a simple analytical experimental setup and in a much more complex rod bundle reflooding experiment. (authors). 9 figs., 28 refs

  8. A review of bottom-up vs. top-down control of sponges on Caribbean fore-reefs: what’s old, what’s new, and future directions

    Directory of Open Access Journals (Sweden)

    Joseph R. Pawlik

    2018-01-01

    Full Text Available Interest in the ecology of sponges on coral reefs has grown in recent years with mounting evidence that sponges are becoming dominant members of reef communities, particularly in the Caribbean. New estimates of water column processing by sponge pumping activities combined with discoveries related to carbon and nutrient cycling have led to novel hypotheses about the role of sponges in reef ecosystem function. Among these developments, a debate has emerged about the relative effects of bottom-up (food availability and top-down (predation control on the community of sponges on Caribbean fore-reefs. In this review, we evaluate the impact of the latest findings on the debate, as well as provide new insights based on older citations. Recent studies that employed different research methods have demonstrated that dissolved organic carbon (DOC and detritus are the principal sources of food for a growing list of sponge species, challenging the idea that the relative availability of living picoplankton is the sole proxy for sponge growth or abundance. New reports have confirmed earlier findings that reef macroalgae release labile DOC available for sponge nutrition. Evidence for top-down control of sponge community structure by fish predation is further supported by gut content studies and historical population estimates of hawksbill turtles, which likely had a much greater impact on relative sponge abundances on Caribbean reefs of the past. Implicit to investigations designed to address the bottom-up vs. top-down debate are appropriate studies of Caribbean fore-reef environments, where benthic communities are relatively homogeneous and terrestrial influences and abiotic effects are minimized. One recent study designed to test both aspects of the debate did so using experiments conducted entirely in shallow lagoonal habitats dominated by mangroves and seagrass beds. The top-down results from this study are reinterpreted as supporting past research

  9. Bridging the Gap between the Nanometer-Scale Bottom-Up and Micrometer-Scale Top-Down Approaches for Site-Defined InP/InAs Nanowires.

    Science.gov (United States)

    Zhang, Guoqiang; Rainville, Christophe; Salmon, Adrian; Takiguchi, Masato; Tateno, Kouta; Gotoh, Hideki

    2015-11-24

    This work presents a method that bridges the gap between the nanometer-scale bottom-up and micrometer-scale top-down approaches for site-defined nanostructures, which has long been a significant challenge for applications that require low-cost and high-throughput manufacturing processes. We realized the bridging by controlling the seed indium nanoparticle position through a self-assembly process. Site-defined InP nanowires were then grown from the indium-nanoparticle array in the vapor-liquid-solid mode through a "seed and grow" process. The nanometer-scale indium particles do not always occupy the same locations within the micrometer-scale open window of an InP exposed substrate due to the scale difference. We developed a technique for aligning the nanometer-scale indium particles on the same side of the micrometer-scale window by structuring the surface of a misoriented InP (111)B substrate. Finally, we demonstrated that the developed method can be used to grow a uniform InP/InAs axial-heterostructure nanowire array. The ability to form a heterostructure nanowire array with this method makes it possible to tune the emission wavelength over a wide range by employing the quantum confinement effect and thus expand the application of this technology to optoelectronic devices. Successfully pairing a controllable bottom-up growth technique with a top-down substrate preparation technique greatly improves the potential for the mass-production and widespread adoption of this technology.

  10. What Drives Farmers to Make Top-Down or Bottom-Up Adaptation to Climate Change and Fluctuations? A Comparative Study on 3 Cases of Apple Farming in Japan and South Africa

    Science.gov (United States)

    Fujisawa, Mariko; Kobayashi, Kazuhiko; Johnston, Peter; New, Mark

    2015-01-01

    Agriculture is one of the most vulnerable sectors to climate change. Farmers have been exposed to multiple stressors including climate change, and they have managed to adapt to those risks. The adaptation actions undertaken by farmers and their decision making are, however, only poorly understood. By studying adaptation practices undertaken by apple farmers in three regions: Nagano and Kazuno in Japan and Elgin in South Africa, we categorize the adaptation actions into two types: farmer initiated bottom-up adaptation and institution led top-down adaptation. We found that the driver which differentiates the type of adaptation likely adopted was strongly related to the farmers’ characteristics, particularly their dependence on the institutions, e.g. the farmers’ cooperative, in selling their products. The farmers who rely on the farmers’ cooperative for their sales are likely to adopt the institution-led adaptation, whereas the farmers who have established their own sales channels tend to start innovative actions by bottom-up. We further argue that even though the two types have contrasting features, the combinations of the both types of adaptations could lead to more successful adaptation particularly in agriculture. This study also emphasizes that more farm-level studies for various crops and regions are warranted to provide substantial feedbacks to adaptation policy. PMID:25822534

  11. What drives farmers to make top-down or bottom-up adaptation to climate change and fluctuations? A comparative study on 3 cases of apple farming in Japan and South Africa.

    Directory of Open Access Journals (Sweden)

    Mariko Fujisawa

    Full Text Available Agriculture is one of the most vulnerable sectors to climate change. Farmers have been exposed to multiple stressors including climate change, and they have managed to adapt to those risks. The adaptation actions undertaken by farmers and their decision making are, however, only poorly understood. By studying adaptation practices undertaken by apple farmers in three regions: Nagano and Kazuno in Japan and Elgin in South Africa, we categorize the adaptation actions into two types: farmer initiated bottom-up adaptation and institution led top-down adaptation. We found that the driver which differentiates the type of adaptation likely adopted was strongly related to the farmers' characteristics, particularly their dependence on the institutions, e.g. the farmers' cooperative, in selling their products. The farmers who rely on the farmers' cooperative for their sales are likely to adopt the institution-led adaptation, whereas the farmers who have established their own sales channels tend to start innovative actions by bottom-up. We further argue that even though the two types have contrasting features, the combinations of the both types of adaptations could lead to more successful adaptation particularly in agriculture. This study also emphasizes that more farm-level studies for various crops and regions are warranted to provide substantial feedbacks to adaptation policy.

  12. When top-down becomes bottom up: behaviour of hyperdense howler monkeys (Alouatta seniculus) trapped on a 0.6 ha island.

    Science.gov (United States)

    Orihuela, Gabriela; Terborgh, John; Ceballos, Natalia; Glander, Kenneth

    2014-01-01

    Predators are a ubiquitous presence in most natural environments. Opportunities to contrast the behaviour of a species in the presence and absence of predators are thus rare. Here we report on the behaviour of howler monkey groups living under radically different conditions on two land-bridge islands in Lago Guri, Venezuela. One group of 6 adults inhabited a 190-ha island (Danto) where they were exposed to multiple potential predators. This group, the control, occupied a home range of 23 ha and contested access to food resources with neighbouring groups in typical fashion. The second group, containing 6 adults, was isolated on a remote, predator-free 0.6 ha islet (Iguana) offering limited food resources. Howlers living on the large island moved, fed and rested in a coherent group, frequently engaged in affiliative activities, rarely displayed agonistic behaviour and maintained intergroup spacing through howling. In contrast, the howlers on Iguana showed repulsion, as individuals spent most of their time spaced widely around the perimeter of the island. Iguana howlers rarely engaged in affiliative behaviour, often chased or fought with one another and were not observed to howl. These behaviors are interpreted as adjustments to the unrelenting deprivation associated with bottom-up limitation in a predator-free environment.

  13. Fabricación de electrodos para control de transporte y alineamiento a micro y nanoescalas usando técnicas bottom-up y top-down

    Directory of Open Access Journals (Sweden)

    Darwin Rodríguez

    2014-12-01

    Full Text Available El continuo avance de aplicaciones en dispositivos de autoensamble, posicionamiento, sensores, actuadores, y que permitan controladamente la manipulación de micro y nanoestructuras, han generado amplio interés en el desarrollo de metodologías que permitan optimizar la fabricación de dispositivos para el control y manipulación a micro y nanoescalas. Este proyecto explora técnicas de fabricación de electrodos con el fin de encontrar una técnica óptima y reproducible. Se compara el rendimiento de cada técnica y se describen protocolos de limpieza y seguridad. Se diseñan e implementan tres geometrías para movilizar y posicionar micro y nanopartículas de hierro en una solución de aceite natural. Finalmente se generan campos eléctricos a partir de electroforesis, con el fin de encontrar la curva que describe el desplazamiento de las partículas con respecto al potencial aplicado. Estos resultados generan gran impacto en los actuales esfuerzos de fabricación bottom-up (controlando con campos la ubicación y la movilidad en dispositivos electrónicos. El hecho de fabricar geometría planar con electrodos genera la posibilidad de que se pueda integrar movimiento de partículas a los circuitos integrados que se fabrican en la actualidad.

  14. When top-down becomes bottom up: behaviour of hyperdense howler monkeys (Alouatta seniculus trapped on a 0.6 ha island.

    Directory of Open Access Journals (Sweden)

    Gabriela Orihuela

    Full Text Available Predators are a ubiquitous presence in most natural environments. Opportunities to contrast the behaviour of a species in the presence and absence of predators are thus rare. Here we report on the behaviour of howler monkey groups living under radically different conditions on two land-bridge islands in Lago Guri, Venezuela. One group of 6 adults inhabited a 190-ha island (Danto where they were exposed to multiple potential predators. This group, the control, occupied a home range of 23 ha and contested access to food resources with neighbouring groups in typical fashion. The second group, containing 6 adults, was isolated on a remote, predator-free 0.6 ha islet (Iguana offering limited food resources. Howlers living on the large island moved, fed and rested in a coherent group, frequently engaged in affiliative activities, rarely displayed agonistic behaviour and maintained intergroup spacing through howling. In contrast, the howlers on Iguana showed repulsion, as individuals spent most of their time spaced widely around the perimeter of the island. Iguana howlers rarely engaged in affiliative behaviour, often chased or fought with one another and were not observed to howl. These behaviors are interpreted as adjustments to the unrelenting deprivation associated with bottom-up limitation in a predator-free environment.

  15. Top down vision or bottom up demand?

    African Journals Online (AJOL)

    Town and Regional Planning. Journal Home · ABOUT THIS JOURNAL · Advanced Search · Current Issue · Archives · Journal Home > Vol 56 (2010) >. Log in or Register to get access to full text downloads.

  16. A top-down / bottom-up approach for multi-actors and multi-criteria assessment of mining projects for sustainable development. Application on Arlit Uranium mines (Niger)

    International Nuclear Information System (INIS)

    Chamaret, A.

    2007-06-01

    This thesis aims to appraise the relevance of using an hybrid top-down / bottom-up approach to evaluate mining projects in the perspective of sustainable development. With the advent of corporate social responsibility and sustainable development concepts, new social expectations have appeared towards companies that go beyond a sole requirement of profit earning capacity. If companies do not answer to these expectations, they risk to lose their social legitimacy. Traditionally associated with social, environmental, economical and political impacts and risks, mining activity is particularly concerned by these new issues. Whereas mineral resources needs have never been so high, mining companies are now expected to limit their negative effects and to take into account their different audiences' expectations in order to define, together, the terms of their social license to operate. Considering the diversity of issues, scales, actors and contexts, the challenge is real and necessitates tools to better understand issues and to structure dialogues. Based on the Uranium mines of Arlit (Niger) case study, this work shows that associating participatory approaches to structuration tools and literature propositions, appears as an efficient formula to better organize issues diversity and to build a structured dialogue between mining companies and their stakeholders. First Part aims to present the theoretical, institutional and sectorial contexts of the thesis. Second Part exposes work and results of the evaluation carried out in Niger. And, Third Part, shows the conclusions that can be derived from this work and presents a proposal for an evaluation framework, potentially applicable to other mining sites. (author)

  17. Top down electroweak dipole operators

    Science.gov (United States)

    Fuyuto, Kaori; Ramsey-Musolf, Michael

    2018-06-01

    We derive present constraints on, and prospective sensitivity to, the electric dipole moment (EDM) of the top quark (dt) implied by searches for the EDMs of the electron and nucleons. Above the electroweak scale v, the dt arises from two gauge invariant operators generated at a scale Λ ≫ v that also mix with the light fermion EDMs under renormalization group evolution at two-loop order. Bounds on the EDMs of first generation fermion systems thus imply bounds on |dt |. Working in the leading log-squared approximation, we find that the present upper bound on |dt | is 10-19 e cm for Λ = 1 TeV, except in regions of finely tuned cancellations that allow for |dt | to be up to fifty times larger. Future de and dn probes may yield an order of magnitude increase in dt sensitivity, while inclusion of a prospective proton EDM search may lead to an additional increase in reach.

  18. A top-down / bottom-up approach for multi-actors and multi-criteria assessment of mining projects for sustainable development. Application on Arlit Uranium mines (Niger); Une demarche Top-Down / Bottom-Up pour l'evaluation en termes multicriteres et multi-acteurs des projets miniers dans l'optique du developpement durable. Application sur les mines d'Uranium d'Arlit (Niger)

    Energy Technology Data Exchange (ETDEWEB)

    Chamaret, A

    2007-06-15

    This thesis aims to appraise the relevance of using an hybrid top-down / bottom-up approach to evaluate mining projects in the perspective of sustainable development. With the advent of corporate social responsibility and sustainable development concepts, new social expectations have appeared towards companies that go beyond a sole requirement of profit earning capacity. If companies do not answer to these expectations, they risk to lose their social legitimacy. Traditionally associated with social, environmental, economical and political impacts and risks, mining activity is particularly concerned by these new issues. Whereas mineral resources needs have never been so high, mining companies are now expected to limit their negative effects and to take into account their different audiences' expectations in order to define, together, the terms of their social license to operate. Considering the diversity of issues, scales, actors and contexts, the challenge is real and necessitates tools to better understand issues and to structure dialogues. Based on the Uranium mines of Arlit (Niger) case study, this work shows that associating participatory approaches to structuration tools and literature propositions, appears as an efficient formula to better organize issues diversity and to build a structured dialogue between mining companies and their stakeholders. First Part aims to present the theoretical, institutional and sectorial contexts of the thesis. Second Part exposes work and results of the evaluation carried out in Niger. And, Third Part, shows the conclusions that can be derived from this work and presents a proposal for an evaluation framework, potentially applicable to other mining sites. (author)

  19. A New Approach to Programming Language Education for Beginners with Top-Down Learning

    Directory of Open Access Journals (Sweden)

    Daisuke Saito

    2013-12-01

    Full Text Available There are two basic approaches in learning new programming language: a bottom-up approach and a top-down approach. It has been said that if a learner has already acquired one language, the top-down approach is more efficient to learn another while, for a person who has absolutely no knowledge of any programming languages; the bottom-up approach is preferable. The major problem of the bottom-up approach is that it requires longer period to acquire the language. For quicker learning, this paper applies a top-down approach for a beginners who has not yet acquired any programming languages.

  20. Integrating top-down and bottom-up approaches to design a cost-effective and equitable programme of measures for adaptation of a river basin to global change

    Science.gov (United States)

    Girard, Corentin; Rinaudo, Jean-Daniel; Pulido-Velazquez, Manuel

    2016-04-01

    Adaptation to the multiple facets of global change challenges the conventional means of sustainably planning and managing water resources at the river basin scale. Numerous demand or supply management options are available, from which adaptation measures need to be selected in a context of high uncertainty of future conditions. Given the interdependency of water users, agreements need to be found at the local level to implement the most effective adaptation measures. Therefore, this work develops an approach combining economics and water resources engineering to select a cost-effective programme of adaptation measures in the context of climate change uncertainty, and to define an equitable allocation of the cost of the adaptation plan between the stakeholders involved. A framework is developed to integrate inputs from the two main approaches commonly used to plan for adaptation. The first, referred to as "top-down", consists of a modelling chain going from global greenhouse gases emission scenarios to local hydrological models used to assess the impact of climate change on water resources. Conversely, the second approach, called "bottom-up", starts from assessing vulnerability at the local level to then identify adaptation measures used to face an uncertain future. The methodological framework presented in this contribution relies on a combination of these two approaches to support the selection of adaptation measures at the local level. Outcomes from these two approaches are integrated to select a cost-effective combination of adaptation measures through a least-cost optimization model developed at the river basin scale. The performances of a programme of measures are assessed under different climate projections to identify cost-effective and least-regret adaptation measures. The issue of allocating the cost of the adaptation plan is considered through two complementary perspectives. The outcome of a negotiation process between the stakeholders is modelled through

  1. Move me, astonish me… delight my eyes and brain: The Vienna Integrated Model of top-down and bottom-up processes in Art Perception (VIMAP) and corresponding affective, evaluative, and neurophysiological correlates.

    Science.gov (United States)

    Pelowski, Matthew; Markey, Patrick S; Forster, Michael; Gerger, Gernot; Leder, Helmut

    2017-07-01

    This paper has a rather audacious purpose: to present a comprehensive theory explaining, and further providing hypotheses for the empirical study of, the multiple ways by which people respond to art. Despite common agreement that interaction with art can be based on a compelling, and occasionally profound, psychological experience, the nature of these interactions is still under debate. We propose a model, The Vienna Integrated Model of Art Perception (VIMAP), with the goal of resolving the multifarious processes that can occur when we perceive and interact with visual art. Specifically, we focus on the need to integrate bottom-up, artwork-derived processes, which have formed the bulk of previous theoretical and empirical assessments, with top-down mechanisms which can describe how individuals adapt or change within their processing experience, and thus how individuals may come to particularly moving, disturbing, transformative, as well as mundane, results. This is achieved by combining several recent lines of theoretical research into a new integrated approach built around three processing checks, which we argue can be used to systematically delineate the possible outcomes in art experience. We also connect our model's processing stages to specific hypotheses for emotional, evaluative, and physiological factors, and address main topics in psychological aesthetics including provocative reactions-chills, awe, thrills, sublime-and difference between "aesthetic" and "everyday" emotional response. Finally, we take the needed step of connecting stages to functional regions in the brain, as well as broader core networks that may coincide with the proposed cognitive checks, and which taken together can serve as a basis for future empirical and theoretical art research. Copyright © 2017 Elsevier B.V. All rights reserved.

  2. Move me, astonish me… delight my eyes and brain: The Vienna Integrated Model of top-down and bottom-up processes in Art Perception (VIMAP) and corresponding affective, evaluative, and neurophysiological correlates

    Science.gov (United States)

    Pelowski, Matthew; Markey, Patrick S.; Forster, Michael; Gerger, Gernot; Leder, Helmut

    2017-07-01

    This paper has a rather audacious purpose: to present a comprehensive theory explaining, and further providing hypotheses for the empirical study of, the multiple ways by which people respond to art. Despite common agreement that interaction with art can be based on a compelling, and occasionally profound, psychological experience, the nature of these interactions is still under debate. We propose a model, The Vienna Integrated Model of Art Perception (VIMAP), with the goal of resolving the multifarious processes that can occur when we perceive and interact with visual art. Specifically, we focus on the need to integrate bottom-up, artwork-derived processes, which have formed the bulk of previous theoretical and empirical assessments, with top-down mechanisms which can describe how individuals adapt or change within their processing experience, and thus how individuals may come to particularly moving, disturbing, transformative, as well as mundane, results. This is achieved by combining several recent lines of theoretical research into a new integrated approach built around three processing checks, which we argue can be used to systematically delineate the possible outcomes in art experience. We also connect our model's processing stages to specific hypotheses for emotional, evaluative, and physiological factors, and address main topics in psychological aesthetics including provocative reactions-chills, awe, thrills, sublime-and difference between ;aesthetic; and ;everyday; emotional response. Finally, we take the needed step of connecting stages to functional regions in the brain, as well as broader core networks that may coincide with the proposed cognitive checks, and which taken together can serve as a basis for future empirical and theoretical art research.

  3. A top-down / bottom-up approach for multi-actors and multi-criteria assessment of mining projects for sustainable development. Application on Arlit Uranium mines (Niger); Une demarche Top-Down / Bottom-Up pour l'evaluation en termes multicriteres et multi-acteurs des projets miniers dans l'optique du developpement durable. Application sur les mines d'Uranium d'Arlit (Niger)

    Energy Technology Data Exchange (ETDEWEB)

    Chamaret, A

    2007-06-15

    This thesis aims to appraise the relevance of using an hybrid top-down / bottom-up approach to evaluate mining projects in the perspective of sustainable development. With the advent of corporate social responsibility and sustainable development concepts, new social expectations have appeared towards companies that go beyond a sole requirement of profit earning capacity. If companies do not answer to these expectations, they risk to lose their social legitimacy. Traditionally associated with social, environmental, economical and political impacts and risks, mining activity is particularly concerned by these new issues. Whereas mineral resources needs have never been so high, mining companies are now expected to limit their negative effects and to take into account their different audiences' expectations in order to define, together, the terms of their social license to operate. Considering the diversity of issues, scales, actors and contexts, the challenge is real and necessitates tools to better understand issues and to structure dialogues. Based on the Uranium mines of Arlit (Niger) case study, this work shows that associating participatory approaches to structuration tools and literature propositions, appears as an efficient formula to better organize issues diversity and to build a structured dialogue between mining companies and their stakeholders. First Part aims to present the theoretical, institutional and sectorial contexts of the thesis. Second Part exposes work and results of the evaluation carried out in Niger. And, Third Part, shows the conclusions that can be derived from this work and presents a proposal for an evaluation framework, potentially applicable to other mining sites. (author)

  4. Top-down modulation, emotion, and hallucination

    NARCIS (Netherlands)

    Aleman, A; Kahn, RS

    2002-01-01

    We argue that the pivotal role assigned by Northoff to the principle of top-down modulation in catatonia might successfully be applied to other symptoms of schizophrenia, for example, hallucinations. Second, we propose that Northoffs account would benefit from a more comprehensive analysis of the

  5. Computer networking a top-down approach

    CERN Document Server

    Kurose, James

    2017-01-01

    Unique among computer networking texts, the Seventh Edition of the popular Computer Networking: A Top Down Approach builds on the author’s long tradition of teaching this complex subject through a layered approach in a “top-down manner.” The text works its way from the application layer down toward the physical layer, motivating readers by exposing them to important concepts early in their study of networking. Focusing on the Internet and the fundamentally important issues of networking, this text provides an excellent foundation for readers interested in computer science and electrical engineering, without requiring extensive knowledge of programming or mathematics. The Seventh Edition has been updated to reflect the most important and exciting recent advances in networking.

  6. Populating the Landscape: a top down approach

    CERN Document Server

    Hawking, Stephen William; Hertog, Thomas

    2006-01-01

    We put forward a framework for cosmology that combines the string landscape with no boundary initial conditions. In this framework, amplitudes for alternative histories for the universe are calculated with final boundary conditions only. This leads to a top down approach to cosmology, in which the histories of the universe depend on the precise question asked. We study the observational consequences of no boundary initial conditions on the landscape, and outline a scheme to test the theory. This is illustrated in a simple model landscape that admits several alternative inflationary histories for the universe. Only a few of the possible vacua in the landscape will be populated. We also discuss in what respect the top down approach differs from other approaches to cosmology in the string landscape, like eternal inflation.

  7. Entanglement entropy in top-down models

    Energy Technology Data Exchange (ETDEWEB)

    Jones, Peter A.R.; Taylor, Marika [Mathematical Sciences and STAG Research Centre, University of Southampton,Highfield, Southampton, SO17 1BJ (United Kingdom)

    2016-08-26

    We explore holographic entanglement entropy in ten-dimensional supergravity solutions. It has been proposed that entanglement entropy can be computed in such top-down models using minimal surfaces which asymptotically wrap the compact part of the geometry. We show explicitly in a wide range of examples that the holographic entanglement entropy thus computed agrees with the entanglement entropy computed using the Ryu-Takayanagi formula from the lower-dimensional Einstein metric obtained from reduction over the compact space. Our examples include not only consistent truncations but also cases in which no consistent truncation exists and Kaluza-Klein holography is used to identify the lower-dimensional Einstein metric. We then give a general proof, based on the Lewkowycz-Maldacena approach, of the top-down entanglement entropy formula.

  8. Entanglement entropy in top-down models

    International Nuclear Information System (INIS)

    Jones, Peter A.R.; Taylor, Marika

    2016-01-01

    We explore holographic entanglement entropy in ten-dimensional supergravity solutions. It has been proposed that entanglement entropy can be computed in such top-down models using minimal surfaces which asymptotically wrap the compact part of the geometry. We show explicitly in a wide range of examples that the holographic entanglement entropy thus computed agrees with the entanglement entropy computed using the Ryu-Takayanagi formula from the lower-dimensional Einstein metric obtained from reduction over the compact space. Our examples include not only consistent truncations but also cases in which no consistent truncation exists and Kaluza-Klein holography is used to identify the lower-dimensional Einstein metric. We then give a general proof, based on the Lewkowycz-Maldacena approach, of the top-down entanglement entropy formula.

  9. Search for scalar top and scalar bottom quarks at LEP

    CERN Document Server

    Abbiendi, G.; Akesson, P.F.; Alexander, G.; Allison, John; Amaral, P.; Anagnostou, G.; Anderson, K.J.; Arcelli, S.; Asai, S.; Axen, D.; Azuelos, G.; Bailey, I.; Barberio, E.; Barlow, R.J.; Batley, R.J.; Bechtle, P.; Behnke, T.; Bell, Kenneth Watson; Bell, P.J.; Bella, G.; Bellerive, A.; Benelli, G.; Bethke, S.; Biebel, O.; Bloodworth, I.J.; Boeriu, O.; Bock, P.; Bonacorsi, D.; Boutemeur, M.; Braibant, S.; Brigliadori, L.; Brown, Robert M.; Buesser, K.; Burckhart, H.J.; Campana, S.; Carnegie, R.K.; Caron, B.; Carter, A.A.; Carter, J.R.; Chang, C.Y.; Charlton, David G.; Csilling, A.; Cuffiani, M.; Dado, S.; Dallavalle, G.Marco; Dallison, S.; De Roeck, A.; De Wolf, E.A.; Desch, K.; Dienes, B.; Donkers, M.; Dubbert, J.; Duchovni, E.; Duckeck, G.; Duerdoth, I.P.; Elfgren, E.; Etzion, E.; Fabbri, F.; Feld, L.; Ferrari, P.; Fiedler, F.; Fleck, I.; Ford, M.; Frey, A.; Furtjes, A.; Gagnon, P.; Gary, John William; Gaycken, G.; Geich-Gimbel, C.; Giacomelli, G.; Giacomelli, P.; Giunta, Marina; Goldberg, J.; Gross, E.; Grunhaus, J.; Gruwe, M.; Gunther, P.O.; Gupta, A.; Hajdu, C.; Hamann, M.; Hanson, G.G.; Harder, K.; Harel, A.; Harin-Dirac, M.; Hauschild, M.; Hauschildt, J.; Hawkes, C.M.; Hawkings, R.; Hemingway, R.J.; Hensel, C.; Herten, G.; Heuer, R.D.; Hill, J.C.; Hoffman, Kara Dion; Homer, R.J.; Horvath, D.; Howard, R.; Huntemeyer, P.; Igo-Kemenes, P.; Ishii, K.; Jeremie, H.; Jovanovic, P.; Junk, T.R.; Kanaya, N.; Kanzaki, J.; Karapetian, G.; Karlen, D.; Kartvelishvili, V.; Kawagoe, K.; Kawamoto, T.; Keeler, R.K.; Kellogg, R.G.; Kennedy, B.W.; Kim, D.H.; Klein, K.; Klier, A.; Kluth, S.; Kobayashi, T.; Kobel, M.; Komamiya, S.; Kormos, Laura L.; Kowalewski, Robert V.; Kramer, T.; Kress, T.; Krieger, P.; von Krogh, J.; Krop, D.; Kruger, K.; Kupper, M.; Lafferty, G.D.; Landsman, H.; Lanske, D.; Layter, J.G.; Leins, A.; Lellouch, D.; Letts, J.; Levinson, L.; Lillich, J.; Lloyd, S.L.; Loebinger, F.K.; Lu, J.; Ludwig, J.; Macpherson, A.; Mader, W.; Marcellini, S.; Marchant, T.E.; Martin, A.J.; Martin, J.P.; Masetti, G.; Mashimo, T.; Mattig, Peter; McDonald, W.J.; McKenna, J.; McMahon, T.J.; McPherson, R.A.; Meijers, F.; Mendez-Lorenzo, P.; Menges, W.; Merritt, F.S.; Mes, H.; Michelini, A.; Mihara, S.; Mikenberg, G.; Miller, D.J.; Moed, S.; Mohr, W.; Mori, T.; Mutter, A.; Nagai, K.; Nakamura, I.; Neal, H.A.; Nisius, R.; O'Neale, S.W.; Oh, A.; Okpara, A.; Oreglia, M.J.; Orito, S.; Pahl, C.; Pasztor, G.; Pater, J.R.; Patrick, G.N.; Pilcher, J.E.; Pinfold, J.; Plane, David E.; Poli, B.; Polok, J.; Pooth, O.; Przybycien, M.; Quadt, A.; Rabbertz, K.; Rembser, C.; Renkel, P.; Rick, H.; Roney, J.M.; Rosati, S.; Rozen, Y.; Runge, K.; Sachs, K.; Saeki, T.; Sahr, O.; Sarkisyan, E.K.G.; Schaile, A.D.; Schaile, O.; Scharff-Hansen, P.; Schieck, J.; Schoerner-Sadenius, Thomas; Schroder, Matthias; Schumacher, M.; Schwick, C.; Scott, W.G.; Seuster, R.; Shears, T.G.; Shen, B.C.; Shepherd-Themistocleous, C.H.; Sherwood, P.; Siroli, G.; Skuja, A.; Smith, A.M.; Sobie, R.; Soldner-Rembold, S.; Spagnolo, S.; Spano, F.; Stahl, A.; Stephens, K.; Strom, David M.; Strohmer, R.; Tarem, S.; Tasevsky, M.; Taylor, R.J.; Teuscher, R.; Thomson, M.A.; Torrence, E.; Toya, D.; Tran, P.; Trefzger, T.; Tricoli, A.; Trocsanyi, Z.; Tsur, E.; Turner-Watson, M.F.; Ueda, I.; Ujvari, B.; Vachon, B.; Vollmer, C.F.; Vannerem, P.; Verzocchi, M.; Voss, H.; Vossebeld, J.; Waller, D.; Ward, C.P.; Ward, D.R.; Watkins, P.M.; Watson, A.T.; Watson, N.K.; Wells, P.S.; Wengler, T.; Wermes, N.; Wetterling, D.; Wilson, G.W.; Wilson, J.A.; Wolf, G.; Wyatt, T.R.; Yamashita, S.; Zer-Zion, D.; Zivkovic, Lidija

    2002-01-01

    Searches for a scalar top quark and a scalar bottom quark have been performed using a data sample of 438 pb-1 at centre-of-mass energies of sqrt(s) = 192 - 209 GeV collected with the OPAL detector at LEP. No evidence for a signal was found. The 95% confidence level lower limit on the scalar top quark mass is 97.6 GeV if the mixing angle between the supersymmetric partners of the left- and right-handed states of the top quark is zero. When the scalar top quark decouples from the Z0 boson, the lower limit is 95.7 GeV. These limits were obtained assuming that the scalar top quark decays into a charm quark and the lightest neutralino, and that the mass difference between the scalar top quark and the lightest neutralino is larger than 10 GeV. The complementary decay mode of the scalar top quark decaying into a bottom quark, a charged lepton and a scalar neutrino has also been studied. The lower limit on the scalar top quark mass is 93.0 GeV for this decay mode, if the mass difference between the scalar top quark a...

  10. Identification of ultramodified proteins using top-down spectra

    Energy Technology Data Exchange (ETDEWEB)

    Liu, Xiaowen; Hengel, Shawna M.; Wu, Si; Tolic, Nikola; Pasa-Tolic, Ljiljana; Pevzner, Pavel A.

    2013-04-10

    Post-translational modifications (PTMs) play an important role in various biological processes through changing protein structure and function. Some ultramodified proteins (like histones) have multiple PTMs forming PTM patterns that define the functionality of a protein. While bottom-up mass spectrometry (MS) has been successful in identifying individual PTMs within short peptides, it is unable to identify PTM patterns spread along entire proteins in a coordinated fashion. In contrast, top-down MS analyzes intact proteins and reveals PTM patterns along the entire proteins. However, while recent advances in instrumentation have made top-down MS accessible to many laboratories, most computational tools for top-down MS focus on proteins with few PTMs and are unable to identify complex PTM patterns. We propose a new algorithm, MS-Align-E, that identifies both expected and unexpected PTMs in ultramodified proteins. We demonstrate that MS-Align-E identifies many protein forms of histone H4 and benchmark it against the currently accepted software tools.

  11. Identification of Ultramodified Proteins Using Top-Down Mass Spectra

    Energy Technology Data Exchange (ETDEWEB)

    Liu, Xiaowen; Hengel, Shawna M.; Wu, Si; Tolic, Nikola; Pasa-Tolic, Ljiljana; Pevzner, Pavel A.

    2013-11-05

    Post-translational modifications (PTMs) play an important role in various biological processes through changing protein structure and function. Some ultramodified proteins (like histones) have multiple PTMs forming PTM patterns that define the functionality of a protein. While bottom-up mass spectrometry (MS) has been successful in identifying individual PTMs within short peptides, it is unable to identify PTM patterns spread along entire proteins in a coordinated fashion. In contrast, top-down MS analyzes intact proteins and reveals PTM patterns along the entire proteins. However, while recent advances in instrumentation have made top-down MS accessible to many laboratories, most computational tools for top-down MS focus on proteins with few PTMs and are unable to identify complex PTM patterns. We propose a new algorithm, MS-Align-E, that identifies both expected and unexpected PTMs in ultramodified proteins. We demonstrate that MS-Align-E identifies many protein forms of histone H4 and benchmark it against the currently accepted software tools.

  12. Radiative corrections to top and bottom production at collider energies

    International Nuclear Information System (INIS)

    Dawson, S.

    1988-10-01

    We discuss the results of a full calculation of the QCD O(α 8 /sup s/) radiative corrections to the differential cross section for the production of a heavy quark pair. Numerical results are presented for bottom and top production in p/bar p/ collisions at /square root/s = 1.8 TeV. 2 refs., 2 figs

  13. Investigation of Top/Bottom electrode and Diffusion Barrier Layer for PZT Thick Film MEMS Sensors

    DEFF Research Database (Denmark)

    Hindrichsen, Christian Carstensen; Pedersen, Thomas; Thomsen, Erik Vilain

    2008-01-01

    Top and bottom electrodes for screen printed piezoelectric lead zirconate titanate, Pb(ZrxTi1 - x)O3 (PZT) thick film are investigated with respect to future MEMS devices. Down to 100 nm thick E-beam evaporated Al and Pt films are patterned as top electrodes on the PZT using a lift-off process...... with a line width down to 3 μ m. A 700 nm thick ZrO2 layer as insolating diffusion barrier layer is found to be insufficient as barrier layer for PZT on a silicon substrate sintered at 850°C. EDX shows diffusion of Si into the PZT layer....

  14. Bottom-hadron production through top quark decay

    Energy Technology Data Exchange (ETDEWEB)

    Moosavi Nejad, Seyed Mohammad

    2009-06-15

    In this thesis we apply perturbative QCD to make precise predictions for some observables in high-energy processes involving bottom-quark. Our first application is a prediction for the energy spectrum of b-flavored hadrons in top quark decay. For that purpose we calculate at NLO the OCD corrections for bottom fragmentation in top decay. The b-quark in the top quark decay is considered once as a massless and once as a massive particle in our calculations. The difference between the differential width calculated in both cases can give us the perturbative fragmentation function of the b-quark. After that using the obtained differential widths and applying ZM-VFNS and GM-VFNS, we make some predictions for the spectrum of B-hadrons produced in top quark decay. The comparison of both approaches shows that the mass effect of the b-quark in the top quark decay is negligible. We also investigate the mass effect of B-hadron in the energy distribution obtained in the previous calculations and we show that this increases the value of the differential width when the energy taken away by the produced parton in top decay is small. Our second application is to obtain the helicity contributions of the W{sup +}-boson in the energy distribution of b-flavored hadrons in top quark decay. For this reason we study the angular decay distribution for the cascade decay of the top-quark (t{yields} b+W{sup +}({yields}e{sup +}+{nu}{sub e})). Using ZM-VFNS we make predictions for the NLO contributions of the longitudinal, the transverse-minus and the transverse-plus helicity of the W{sup +}-boson in the energy distribution of B-hadron. (orig.)

  15. Learning dynamics by theoretical tools of game theory. Comment on "Move me, astonish me...delight my eyes and brain: The Vienna Integrated Model of top-down and bottom-up processes in Art Perception (VIMAP) and corresponding affective, evaluative, and neurophysiological correlates" by M. Pelowski et al.

    Science.gov (United States)

    Burini, Diletta; De Lillo, Silvana

    2017-07-01

    The VIMAP model presented in the survey [5] aims at analyzing the processes that can occur in the human perception in the front of an artwork. Such a model combines the bottom-up (artwork derived) processes with the top-down mechanisms which describe how individuals adapt or change their own art processing experience. The cognitive flow consists of seven stages connected to five outcomes, which account for all the main ways of responding to art. Moreover this model can also identify the specific regions of the brain that are posited to be main centers of the processes that may coincide with the proposed cognitive checks.

  16. Ugliness as the fourth wall-breaker. Comment on "Move me, astonish me... delight my eyes and brain: The Vienna Integrated Model of top-down and bottom-up processes in Art Perception (VIMAP) and corresponding affective, evaluative, and neurophysiological correlates" by Matthew Pelowski et al.

    Science.gov (United States)

    Ishizu, Tomohiro; Sakamoto, Yasuhiro

    2017-07-01

    In this extensive and valuable theoretical article, Pelowski et al. propose a psychological architecture in art appreciation by introducing the concepts of early/bottom-up and relatively late/top-down stages. The former is dictated as automatic processing on perceptual features of visual images, while the latter comprises cognitive and evaluative processes where modulations from acquired knowledge and memories come into play with recurrent loops to form final experiences, as well as brain areas/networks which possibly have a role in each processing component [9].

  17. Developing Multi-Level Institutions from Top-Down Ancestors

    Directory of Open Access Journals (Sweden)

    Martha Dowsley

    2007-11-01

    Full Text Available The academic literature contains numerous examples of the failures of both top-down and bottom-up common pool resource management frameworks. Many authors agree that management regimes instead need to utilize a multi-level governance approach to meet diverse objectives in management. However, many currently operating systems do not have that history. This paper explores the conversion of ancestral top-down regimes to complex systems involving multiple scales, levels and objectives through the management of the polar bear (Ursus maritimus in its five range countries. The less successful polar bear management systems continue to struggle with the challenges of developing institutions with the capacity to learn and change, addressing multiple objectives while recognizing the conservation backbone to management, and matching the institutional scale with biophysical, economic and social scales. The comparatively successful institutions incorporate these features, but reveal on-going problems with vertical links that are partially dealt with through the creation of links to other groups.

  18. Afterimages are biased by top-down information.

    Science.gov (United States)

    Utz, Sandra; Carbon, Claus-Christian

    2015-01-01

    The afterimage illusion refers to a complementary colored image continuing to appear in the observer's vision after the exposure to the original image has ceased. It is assumed to be a phenomenon of the primary visual pathway, caused by overstimulation of photoreceptors of the retina. The aim of the present study was to investigate the nature of afterimage perceptions; mainly whether it is a mere physical, that is, low-level effect or whether it can be modulated by top-down processes, that is, high-level processes. Participants were first exposed to five either strongly female or male faces (Experiment 1), objects highly associated with female or male gender (Experiment 2) or female versus male names (Experiment 3), followed by a negativated image of a gender-neutral face which had to be fixated for 20s to elicit an afterimage. Participants had to rate their afterimages according to sexual dimorphism, showing that the afterimage of the gender-neutral face was perceived as significantly more female in the female priming condition compared with the male priming condition, independently of the priming quality (faces, objects, and names). Our results documented, in addition to previously presumed bottom-up mechanisms, a prominent influence of top-down processing on the perception of afterimages via priming mechanisms (female primes led to more female afterimage perception). © The Author(s) 2015.

  19. Investigation of Top/bottom Electrode and Diffusion Barrier Layer for PZT thick film MEMS Sensors

    DEFF Research Database (Denmark)

    Pedersen, Thomas; Hindrichsen, Christian Carstensen; Lou-Møller, R.

    2007-01-01

    In this work screen printed piezoelectric Ferroperm PZ26 lead zirconate titanate (PZT) thick film is used for two MEMS devices. A test structure is used to investigate several aspects regarding bottom and top electrodes. 450 nm ZrO2 thin film is found to be an insufficient diffusion barrier layer...... for thick film PZT sintered at 850degC. E-beam evaporated Al and Pt is patterned on PZT with a lift-off process with a line width down to 3 mum. The roughness of the PZT is found to have a strong influence on the conductance of the top electrode....

  20. Depression-biased reverse plasticity rule is required for stable learning at top-down connections.

    Directory of Open Access Journals (Sweden)

    Kendra S Burbank

    Full Text Available Top-down synapses are ubiquitous throughout neocortex and play a central role in cognition, yet little is known about their development and specificity. During sensory experience, lower neocortical areas are activated before higher ones, causing top-down synapses to experience a preponderance of post-synaptic activity preceding pre-synaptic activity. This timing pattern is the opposite of that experienced by bottom-up synapses, which suggests that different versions of spike-timing dependent synaptic plasticity (STDP rules may be required at top-down synapses. We consider a two-layer neural network model and investigate which STDP rules can lead to a distribution of top-down synaptic weights that is stable, diverse and avoids strong loops. We introduce a temporally reversed rule (rSTDP where top-down synapses are potentiated if post-synaptic activity precedes pre-synaptic activity. Combining analytical work and integrate-and-fire simulations, we show that only depression-biased rSTDP (and not classical STDP produces stable and diverse top-down weights. The conclusions did not change upon addition of homeostatic mechanisms, multiplicative STDP rules or weak external input to the top neurons. Our prediction for rSTDP at top-down synapses, which are distally located, is supported by recent neurophysiological evidence showing the existence of temporally reversed STDP in synapses that are distal to the post-synaptic cell body.

  1. Depression-Biased Reverse Plasticity Rule Is Required for Stable Learning at Top-Down Connections

    Science.gov (United States)

    Burbank, Kendra S.; Kreiman, Gabriel

    2012-01-01

    Top-down synapses are ubiquitous throughout neocortex and play a central role in cognition, yet little is known about their development and specificity. During sensory experience, lower neocortical areas are activated before higher ones, causing top-down synapses to experience a preponderance of post-synaptic activity preceding pre-synaptic activity. This timing pattern is the opposite of that experienced by bottom-up synapses, which suggests that different versions of spike-timing dependent synaptic plasticity (STDP) rules may be required at top-down synapses. We consider a two-layer neural network model and investigate which STDP rules can lead to a distribution of top-down synaptic weights that is stable, diverse and avoids strong loops. We introduce a temporally reversed rule (rSTDP) where top-down synapses are potentiated if post-synaptic activity precedes pre-synaptic activity. Combining analytical work and integrate-and-fire simulations, we show that only depression-biased rSTDP (and not classical STDP) produces stable and diverse top-down weights. The conclusions did not change upon addition of homeostatic mechanisms, multiplicative STDP rules or weak external input to the top neurons. Our prediction for rSTDP at top-down synapses, which are distally located, is supported by recent neurophysiological evidence showing the existence of temporally reversed STDP in synapses that are distal to the post-synaptic cell body. PMID:22396630

  2. Recognition and Construction of Top, Bottom, and Versatile Orientations in Gay/Bisexual Men.

    Science.gov (United States)

    Moskowitz, David A; Roloff, Michael E

    2017-01-01

    Research on gay and bisexual men's sexual position self-label (i.e., being a top, bottom, or versatile during anal sex) has revealed only independent snapshots of its development by focusing primarily on the influence of penis size. Moreover, the basic chronology of development of the sexual position self-label has barely been addressed. In response, we implemented a survey of 282 gay and bisexual men that measured demographics (including height and penis size), age of sexual recognitions, sexual position self-label, and attitudinal constructs suggested by previous literature as important (e.g., pleasure, control, anxieties, and gender typicality). Results suggested that men's sexual position self-label was learned over a 15-year timespan. Ages of first same-sex genital manipulation and first anal sex experiences were related to age at first self-labeling. With respect to predictors of labels, a multivariate path model was created. The model did not support the direct importance of penis size, but identified indirect paths that linked penis size to top/bottom identification (e.g., smaller penis sizes leading to topping-anxieties and thus, a bottom label). Finding bottoming to be pleasurable and the importance of sexual control dynamics were the only two direct predictors. The path model substantiated the reliance both bottoms and tops show towards seeking (or not seeking among tops) gender typical, sexually dominant partners. It also supported previous evidence regarding race; specifically, while race may activate differences in sexual behavioral dynamics, it is not a great predictor of the sexual position self-label. This study shows that sexual position self-labeling has enormous complexity and cannot be reduced down to penis size.

  3. Early Top-Down Influences on Bistable Perception Revealed by Event-Related Potentials

    Science.gov (United States)

    Pitts, Michael A.; Gavin, William J.; Nerger, Janice L.

    2008-01-01

    A longstanding debate exists in the literature concerning bottom-up vs. top-down influences on bistable perception. Recently, a technique has been developed to measure early changes in brain activity (via ERPs) related to perceptual reversals (Kornmeier & Bach, 2004). An ERP component, the reversal negativity (RN) has been identified, and is…

  4. Anterior Cingulate Cortex Input to the Claustrum Is Required for Top-Down Action Control

    Directory of Open Access Journals (Sweden)

    Michael G. White

    2018-01-01

    Full Text Available Summary: Cognitive abilities, such as volitional attention, operate under top-down, executive frontal cortical control of hierarchically lower structures. The circuit mechanisms underlying this process are unresolved. The claustrum possesses interconnectivity with many cortical areas and, thus, is hypothesized to orchestrate the cortical mantle for top-down control. Whether the claustrum receives top-down input and how this input may be processed by the claustrum have yet to be formally tested, however. We reveal that a rich anterior cingulate cortex (ACC input to the claustrum encodes a preparatory top-down information signal on a five-choice response assay that is necessary for optimal task performance. We further show that ACC input monosynaptically targets claustrum inhibitory interneurons and spiny glutamatergic projection neurons, the latter of which amplify ACC input in a manner that is powerfully constrained by claustrum inhibitory microcircuitry. These results demonstrate ACC input to the claustrum is critical for top-down control guiding action. : White et al. show that anterior cingulate cortex (ACC input to the claustrum encodes a top-down preparatory signal on a 5-choice response assay that is critical for task performance. Claustrum microcircuitry amplifies top-down ACC input in a frequency-dependent manner for eventual propagation to the cortex for cognitive control of action. Keywords: 5CSRTT, optogenetics, fiber photometry, microcircuit, attention, bottom-up, sensory cortices, motor cortices

  5. Top-Down Influence in Young Children's Linguistic Ambiguity Resolution

    Science.gov (United States)

    Rabagliati, Hugh; Pylkkanen, Liina; Marcus, Gary F.

    2013-01-01

    Language is rife with ambiguity. Do children and adults meet this challenge in similar ways? Recent work suggests that while adults resolve syntactic ambiguities by integrating a variety of cues, children are less sensitive to top-down evidence. We test whether this top-down insensitivity is specific to syntax or a general feature of children's…

  6. The forgotten artist: Why to consider intentions and interaction in a model of aesthetic experience. Comment on "Move me, astonish me... delight my eyes and brain: The Vienna Integrated Model of top-down and bottom-up processes in Art Perception (VIMAP) and corresponding affective, evaluative, and neurophysiological correlates" by Matthew Pelowski et al.

    Science.gov (United States)

    Brattico, Elvira; Brattico, Pauli; Vuust, Peter

    2017-07-01

    In their target article published in this journal issue, Pelowski et al. [1] address the question of how humans experience, and respond to, visual art. They propose a multi-layered model of the representations and processes involved in assessing visual art objects that, furthermore, involves both bottom-up and top-down elements. Their model provides predictions for seven different outcomes of human aesthetic experience, based on few distinct features (schema congruence, self-relevance, and coping necessity), and connects the underlying processing stages to ;specific correlates of the brain; (a similar attempt was previously done for music by [2-4]). In doing this, the model aims to account for the (often profound) experience of an individual viewer in front of an art object.

  7. On viewer motivation, unit of analysis, and the VIMAP. Comment on "Move me, astonish me ... delight my eyes and brain: The Vienna Integrated Model of top-down and bottom-up processes in Art Perception (VIMAP) and corresponding affective, evaluative, and neurophysiological correlates" by Matthew Pelowski et al.

    Science.gov (United States)

    Tinio, Pablo P. L.

    2017-07-01

    The Vienna Integrated Model of Art Perception (VIMAP; [5]) is the most comprehensive model of the art experience today. The model incorporates bottom-up and top-down cognitive processes and accounts for different outcomes of the art experience, such as aesthetic evaluations, emotions, and physiological and neurological responses to art. In their presentation of the model, Pelowski et al. also present hypotheses that are amenable to empirical testing. These features make the VIMAP an ambitious model that attempts to explain how meaningful, complex, and profound aspects of the art experience come about, which is a significant extension of previous models of the art experience (e.g., [1-3,10]), and which gives the VIMAP good explanatory power.

  8. Top-bottom doublet in the sphaleron background

    CERN Document Server

    Moreno, J M; Quirós, Mariano

    1995-01-01

    We consider the top-bottom doublet in the background of the sphaleron for the realistic case of large non-degeneracy of fermion masses, in particular m_b=5 GeV and m_t=175 GeV. We propose an axially symmetric (r,\\theta)-dependent ansatz for fermion fields and investigate the effects of the non-degeneracy on them. The exact solution is described, with an error less than 0.01\\%, by a set of ten radial functions. We also propose an approximate solution, in the m_b/m_t\\rightarrow 0 limit, with an error {\\cal O}(m_b/m_t). We have found that the effects of non-degeneracy provide a \\theta-dependence typically \\sim 10\\%.

  9. Informed-Proteomics: open-source software package for top-down proteomics

    Energy Technology Data Exchange (ETDEWEB)

    Park, Jungkap; Piehowski, Paul D.; Wilkins, Christopher; Zhou, Mowei; Mendoza, Joshua; Fujimoto, Grant M.; Gibbons, Bryson C.; Shaw, Jared B.; Shen, Yufeng; Shukla, Anil K.; Moore, Ronald J.; Liu, Tao; Petyuk, Vladislav A.; Tolić, Nikola; Paša-Tolić, Ljiljana; Smith, Richard D.; Payne, Samuel H.; Kim, Sangtae

    2017-08-07

    Top-down proteomics involves the analysis of intact proteins. This approach is very attractive as it allows for analyzing proteins in their endogenous form without proteolysis, preserving valuable information about post-translation modifications, isoforms, proteolytic processing or their combinations collectively called proteoforms. Moreover, the quality of the top-down LC-MS/MS datasets is rapidly increasing due to advances in the liquid chromatography and mass spectrometry instrumentation and sample processing protocols. However, the top-down mass spectra are substantially more complex compare to the more conventional bottom-up data. To take full advantage of the increasing quality of the top-down LC-MS/MS datasets there is an urgent need to develop algorithms and software tools for confident proteoform identification and quantification. In this study we present a new open source software suite for top-down proteomics analysis consisting of an LC-MS feature finding algorithm, a database search algorithm, and an interactive results viewer. The presented tool along with several other popular tools were evaluated using human-in-mouse xenograft luminal and basal breast tumor samples that are known to have significant differences in protein abundance based on bottom-up analysis.

  10. Face processing pattern under top-down perception: a functional MRI study

    Science.gov (United States)

    Li, Jun; Liang, Jimin; Tian, Jie; Liu, Jiangang; Zhao, Jizheng; Zhang, Hui; Shi, Guangming

    2009-02-01

    Although top-down perceptual process plays an important role in face processing, its neural substrate is still puzzling because the top-down stream is extracted difficultly from the activation pattern associated with contamination caused by bottom-up face perception input. In the present study, a novel paradigm of instructing participants to detect faces from pure noise images is employed, which could efficiently eliminate the interference of bottom-up face perception in topdown face processing. Analyzing the map of functional connectivity with right FFA analyzed by conventional Pearson's correlation, a possible face processing pattern induced by top-down perception can be obtained. Apart from the brain areas of bilateral fusiform gyrus (FG), left inferior occipital gyrus (IOG) and left superior temporal sulcus (STS), which are consistent with a core system in the distributed cortical network for face perception, activation induced by top-down face processing is also found in these regions that include the anterior cingulate gyrus (ACC), right oribitofrontal cortex (OFC), left precuneus, right parahippocampal cortex, left dorsolateral prefrontal cortex (DLPFC), right frontal pole, bilateral premotor cortex, left inferior parietal cortex and bilateral thalamus. The results indicate that making-decision, attention, episodic memory retrieving and contextual associative processing network cooperate with general face processing regions to process face information under top-down perception.

  11. Semi top-down method combined with earth-bank, an effective method for basement construction.

    Science.gov (United States)

    Tuan, B. Q.; Tam, Ng M.

    2018-04-01

    Choosing an appropriate method of deep excavation not only plays a decisive role in technical success, but also in economics of the construction project. Presently, we mainly base on to key methods: “Bottom-up” and “Top-down” construction method. Right now, this paper presents an another method of construction that is “Semi Top-down method combining with earth-bank” in order to take the advantages and limit the weakness of the above methods. The Bottom-up method was improved by using the earth-bank to stabilize retaining walls instead of the bracing steel struts. The Top-down method was improved by using the open cut method for the half of the earthwork quantities.

  12. Does Top-Down Feedback Modulate the Encoding of Orthographic Representations During Visual-Word Recognition?

    Science.gov (United States)

    Perea, Manuel; Marcet, Ana; Vergara-Martínez, Marta

    2016-09-01

    In masked priming lexical decision experiments, there is a matched-case identity advantage for nonwords, but not for words (e.g., ERTAR-ERTAR words when top-down feedback is minimized. We employed a task that taps prelexical orthographic processes: the masked prime same-different task. For "same" trials, results showed faster response times for targets when preceded by a briefly presented matched-case identity prime than when preceded by a mismatched-case identity prime. Importantly, this advantage was similar in magnitude for nonwords and words. This finding constrains the interplay of bottom-up versus top-down mechanisms in models of visual-word identification.

  13. Top-down knowledge modulates onset capture in a feedforward manner.

    Science.gov (United States)

    Becker, Stefanie I; Lewis, Amanda J; Axtens, Jenna E

    2017-04-01

    How do we select behaviourally important information from cluttered visual environments? Previous research has shown that both top-down, goal-driven factors and bottom-up, stimulus-driven factors determine which stimuli are selected. However, it is still debated when top-down processes modulate visual selection. According to a feedforward account, top-down processes modulate visual processing even before the appearance of any stimuli, whereas others claim that top-down processes modulate visual selection only at a late stage, via feedback processing. In line with such a dual stage account, some studies found that eye movements to an irrelevant onset distractor are not modulated by its similarity to the target stimulus, especially when eye movements are launched early (within 150-ms post stimulus onset). However, in these studies the target transiently changed colour due to a colour after-effect that occurred during premasking, and the time course analyses were incomplete. The present study tested the feedforward account against the dual stage account in two eye tracking experiments, with and without colour after-effects (Exp. 1), as well when the target colour varied randomly and observers were informed of the target colour with a word cue (Exp. 2). The results showed that top-down processes modulated the earliest eye movements to the onset distractors (feedforward account of top-down modulation.

  14. Top-Down Approach for the Social Capital Development

    OpenAIRE

    Shah, Syed Akhter Hussain; Shah, Tari shah; Ahmed, Eatzaz

    2011-01-01

    This study provides the compatibility of top-down approach of the collectivist society with the algebraic representation of social capital matrix [22], which establishes algebraic based model having capability of interpreting the state intervention in building social capital. The study also suggests a policy framework for the developing economic strategies and effective planing at government level regarding social capital development in perspective of top-down approach.

  15. Top-down approach to biological therapy of Crohn's disease.

    Science.gov (United States)

    Hirschmann, Simon; Neurath, Markus F

    2017-03-01

    Crohn's disease (CD) is a chronic, immune-mediated condition with a potentially disabling and destructive course. Despite growing data on when to use a therapeutic 'top-down' strategy, clinical management of this complex disorder is still challenging. Currently, the discussion of 'top-down' strategy in CD mostly includes biological therapy alone or in combination. Areas covered: This article is based on a review of existing literature regarding the use of biological therapy in a 'top-down' approach for the treatment of Crohn's disease. The authors reviewed all the major databases including MEDLINE as well as DDW and ECCO abstracts, respectively. Expert opinion: A 'top-down' therapeutic approach in Crohn's disease is strongly supported by existing data in patients with several risk factors for a severe course of disease. Moreover, there is an increasing amount of published data recommending a more individualised therapeutic strategy to identify candidates for 'top-down' treatment, based on enhanced diagnostics using biomarkers. Emerging therapeutic approaches besides existing therapy concepts using biologicals may possibly redefine the 'top-down' therapeutic strategy for Crohn's disease in the future.

  16. Search for signatures with top, bottom, tau and exotics

    CERN Document Server

    Andrea Favareto; Luigi Longo

    2016-01-01

    The Standard Model (SM) of particle physics is a sensational success, especially since the discov- ery of the 125 GeV Higgs boson. However, there are still several open questions that the Standard Model doesnâ??t address, like the nature of dark matter and dark energy, the matter-antimatter asym- metry, the neutrino oscillations, the inconsistency with the general relativity and the hierarchy problem. Theories Beyond the Standard Model (BSM), such as Supersymmetry, Little and Com- posite Higgs, Extra-Dimensions, Extended Gauge models, Technicolor, Left-Right symmetric models, and many other BSM scenarios are trying to answer these questions. In these proceed- ings we present the most recent results for searches Beyond the Standard Model at the LHC by the ATLAS and CMS experiments, focusing on signatures with top, bottom, tau and exotics. The data are found to be consistent with the Standard Model. The non-observation of a signal permits to set limits at the 95pct confidence level on the production cross sect...

  17. Higgs, Top, and Bottom Mass Predictions in Finite Unified Theories

    CERN Document Server

    Heinemeyer, Sven; Zoupanos, George

    2014-01-01

    All-loop Finite Unified Theories (FUTs) are N = 1 supersymmetric Grand Unified Theories (GUTs) based on the principle of reduction of couplings, which have a remarkable predictive power. The reduction of couplings implies the existence of renormalization group invariant relations among them, which guarantee the vanishing of the beta functions at all orders in perturbation theory in particular N = 1 GUTs. In the soft breaking sector these relations imply the existence of a sum rule among the soft scalar masses. The confrontation of the predictions of a SU(5) FUT model with the top and bottom quark masses and other low-energy experimental constraints leads to a prediction of the light Higgs-boson mass in the rangeMh ∼ 121−126 GeV, in remarkable agreement with the discovery of the Higgs boson with a mass around ∼ 125.7 GeV. Also a relatively heavy spectrum with coloured supersymmetric particles above ∼ 1.5 TeV is predicted, consistent with the non-observation of those particles at the LHC.

  18. Biodiversity mediates top-down control in eelgrass ecosystems: a global comparative-experimental approach.

    Science.gov (United States)

    Duffy, J Emmett; Reynolds, Pamela L; Boström, Christoffer; Coyer, James A; Cusson, Mathieu; Donadi, Serena; Douglass, James G; Eklöf, Johan S; Engelen, Aschwin H; Eriksson, Britas Klemens; Fredriksen, Stein; Gamfeldt, Lars; Gustafsson, Camilla; Hoarau, Galice; Hori, Masakazu; Hovel, Kevin; Iken, Katrin; Lefcheck, Jonathan S; Moksnes, Per-Olav; Nakaoka, Masahiro; O'Connor, Mary I; Olsen, Jeanine L; Richardson, J Paul; Ruesink, Jennifer L; Sotka, Erik E; Thormar, Jonas; Whalen, Matthew A; Stachowicz, John J

    2015-07-01

    Nutrient pollution and reduced grazing each can stimulate algal blooms as shown by numerous experiments. But because experiments rarely incorporate natural variation in environmental factors and biodiversity, conditions determining the relative strength of bottom-up and top-down forcing remain unresolved. We factorially added nutrients and reduced grazing at 15 sites across the range of the marine foundation species eelgrass (Zostera marina) to quantify how top-down and bottom-up control interact with natural gradients in biodiversity and environmental forcing. Experiments confirmed modest top-down control of algae, whereas fertilisation had no general effect. Unexpectedly, grazer and algal biomass were better predicted by cross-site variation in grazer and eelgrass diversity than by global environmental gradients. Moreover, these large-scale patterns corresponded strikingly with prior small-scale experiments. Our results link global and local evidence that biodiversity and top-down control strongly influence functioning of threatened seagrass ecosystems, and suggest that biodiversity is comparably important to global change stressors. © 2015 John Wiley & Sons Ltd/CNRS.

  19. The Primary Visual Cortex Is Differentially Modulated by Stimulus-Driven and Top-Down Attention

    Science.gov (United States)

    Bekisz, Marek; Bogdan, Wojciech; Ghazaryan, Anaida; Waleszczyk, Wioletta J.; Kublik, Ewa; Wróbel, Andrzej

    2016-01-01

    Selective attention can be focused either volitionally, by top-down signals derived from task demands, or automatically, by bottom-up signals from salient stimuli. Because the brain mechanisms that underlie these two attention processes are poorly understood, we recorded local field potentials (LFPs) from primary visual cortical areas of cats as they performed stimulus-driven and anticipatory discrimination tasks. Consistent with our previous observations, in both tasks, we found enhanced beta activity, which we have postulated may serve as an attention carrier. We characterized the functional organization of task-related beta activity by (i) cortical responses (EPs) evoked by electrical stimulation of the optic chiasm and (ii) intracortical LFP correlations. During the anticipatory task, peripheral stimulation that was preceded by high-amplitude beta oscillations evoked large-amplitude EPs compared with EPs that followed low-amplitude beta. In contrast, during the stimulus-driven task, cortical EPs preceded by high-amplitude beta oscillations were, on average, smaller than those preceded by low-amplitude beta. Analysis of the correlations between the different recording sites revealed that beta activation maps were heterogeneous during the bottom-up task and homogeneous for the top-down task. We conclude that bottom-up attention activates cortical visual areas in a mosaic-like pattern, whereas top-down attentional modulation results in spatially homogeneous excitation. PMID:26730705

  20. Sleep deprivation selectively disrupts top-down adaptation to cognitive conflict in the Stroop test.

    Science.gov (United States)

    Gevers, Wim; Deliens, Gaetane; Hoffmann, Sophie; Notebaert, Wim; Peigneux, Philippe

    2015-12-01

    Sleep deprivation is known to exert detrimental effects on various cognitive domains, including attention, vigilance and working memory. Seemingly at odds with these findings, prior studies repeatedly failed to evidence an impact of prior sleep deprivation on cognitive interference in the Stroop test, a hallmark paradigm in the study of cognitive control abilities. The present study investigated further the effect of sleep deprivation on cognitive control using an adapted version of the Stroop test that allows to segregate top-down (attentional reconfiguration on incongruent items) and bottom-up (facilitated processing after repetitions in responses and/or features of stimuli) components of performance. Participants underwent a regular night of sleep or a night of total sleep deprivation before cognitive testing. Results disclosed that sleep deprivation selectively impairs top-down adaptation mechanisms: cognitive control no longer increased upon detection of response conflict at the preceding trial. In parallel, bottom-up abilities were found unaffected by sleep deprivation: beneficial effects of stimulus and response repetitions persisted. Changes in vigilance states due to sleep deprivation selectively impact on cognitive control in the Stroop test by affecting top-down, but not bottom-up, mechanisms that guide adaptive behaviours. © 2015 European Sleep Research Society.

  1. Top-down population regulation of a top predator: lions in the Ngorongoro Crater.

    Science.gov (United States)

    Kissui, Bernard M; Packer, Craig

    2004-09-07

    Efforts to determine whether bottom-up or top-down processes regulate populations have been hampered by difficulties in accurately estimating the population's carrying capacity and in directly measuring food intake rate, the impacts of interspecific competition and exposure to natural enemies. We report on 40 years of data on the lion population in Ngorongoro Crater, Tanzania, which showed strong evidence of density-dependent regulation at 100-120 individuals but has remained below 60 individuals for the past decade despite consistently high prey abundance. The lions enjoy a higher per capita food-intake rate and higher cub recruitment at low population density, and interspecific competition has not increased in recent years. These animals have suffered from a number of severe disease outbreaks over the past 40 years, but, whereas the population recovered exponentially from a severe epizootic in 1963, three outbreaks between 1994 and 2001 have occurred in such rapid succession that the population has been unable to return to the carrying capacity. The Crater population may have become unusually vulnerable to infectious disease in recent years owing to its close proximity to a growing human population and a history of close inbreeding. The Crater lions may therefore provide important insights into the future of many endangered populations.

  2. Impact of top-down control during mental fatigue

    NARCIS (Netherlands)

    Lorist, Monicque M.

    2008-01-01

    The influence of mental fatigue, as induced by time on task, on top-down control involved in planning goal-directed behavior and conflict resolution was examined, using an S1-S2 paradigm. S2 stimuli consisted of compatible and incompatible stimuli, placing dissimilar demands on automatic and

  3. Piezoresistive effect in top-down fabricated silicon nanowires

    DEFF Research Database (Denmark)

    Reck, Kasper; Richter, Jacob; Hansen, Ole

    2008-01-01

    We have designed and fabricated silicon test chips to investigate the piezoresistive properties of both crystalline and polycrystalline nanowires using a top-down approach, in order to comply with conventional fabrication techniques. The test chip consists of 5 silicon nanowires and a reference...

  4. Top-down influences of written text on perceived clarity of degraded speech.

    Science.gov (United States)

    Sohoglu, Ediz; Peelle, Jonathan E; Carlyon, Robert P; Davis, Matthew H

    2014-02-01

    An unresolved question is how the reported clarity of degraded speech is enhanced when listeners have prior knowledge of speech content. One account of this phenomenon proposes top-down modulation of early acoustic processing by higher-level linguistic knowledge. Alternative, strictly bottom-up accounts argue that acoustic information and higher-level knowledge are combined at a late decision stage without modulating early acoustic processing. Here we tested top-down and bottom-up accounts using written text to manipulate listeners' knowledge of speech content. The effect of written text on the reported clarity of noise-vocoded speech was most pronounced when text was presented before (rather than after) speech (Experiment 1). Fine-grained manipulation of the onset asynchrony between text and speech revealed that this effect declined when text was presented more than 120 ms after speech onset (Experiment 2). Finally, the influence of written text was found to arise from phonological (rather than lexical) correspondence between text and speech (Experiment 3). These results suggest that prior knowledge effects are time-limited by the duration of auditory echoic memory for degraded speech, consistent with top-down modulation of early acoustic processing by linguistic knowledge. PsycINFO Database Record (c) 2014 APA, all rights reserved.

  5. Top Down Proteomics Reveals Mature Proteoforms Expressed in Subcellular Fractions of the Echinococcus granulosus Preadult Stage.

    Science.gov (United States)

    Lorenzatto, Karina R; Kim, Kyunggon; Ntai, Ioanna; Paludo, Gabriela P; Camargo de Lima, Jeferson; Thomas, Paul M; Kelleher, Neil L; Ferreira, Henrique B

    2015-11-06

    Echinococcus granulosus is the causative agent of cystic hydatid disease, a neglected zoonosis responsible for high morbidity and mortality. Several molecular mechanisms underlying parasite biology remain poorly understood. Here, E. granulosus subcellular fractions were analyzed by top down and bottom up proteomics for protein identification and characterization of co-translational and post-translational modifications (CTMs and PTMs, respectively). Nuclear and cytosolic extracts of E. granulosus protoscoleces were fractionated by 10% GELFrEE and proteins under 30 kDa were analyzed by LC-MS/MS. By top down analysis, 186 proteins and 207 proteoforms were identified, of which 122 and 52 proteoforms were exclusively detected in nuclear and cytosolic fractions, respectively. CTMs were evident as 71% of the proteoforms had methionine excised and 47% were N-terminal acetylated. In addition, in silico internal acetylation prediction coupled with top down MS allowed the characterization of 9 proteins differentially acetylated, including histones. Bottom up analysis increased the overall number of identified proteins in nuclear and cytosolic fractions to 154 and 112, respectively. Overall, our results provided the first description of the low mass proteome of E. granulosus subcellular fractions and highlighted proteoforms with CTMs and PTMS whose characterization may lead to another level of understanding about molecular mechanisms controlling parasitic flatworm biology.

  6. Top-down proteomics for the analysis of proteolytic events - Methods, applications and perspectives.

    Science.gov (United States)

    Tholey, Andreas; Becker, Alexander

    2017-11-01

    Mass spectrometry based proteomics is an indispensable tool for almost all research areas relevant for the understanding of proteolytic processing, ranging from the identification of substrates, products and cleavage sites up to the analysis of structural features influencing protease activity. The majority of methods for these studies are based on bottom-up proteomics performing analysis at peptide level. As this approach is characterized by a number of pitfalls, e.g. loss of molecular information, there is an ongoing effort to establish top-down proteomics, performing separation and MS analysis both at intact protein level. We briefly introduce major approaches of bottom-up proteomics used in the field of protease research and highlight the shortcomings of these methods. We then discuss the present state-of-the-art of top-down proteomics. Together with the discussion of known challenges we show the potential of this approach and present a number of successful applications of top-down proteomics in protease research. This article is part of a Special Issue entitled: Proteolysis as a Regulatory Event in Pathophysiology edited by Stefan Rose-John. Copyright © 2017 Elsevier B.V. All rights reserved.

  7. Decoding of top-down cognitive processing for SSVEP-controlled BMI

    Science.gov (United States)

    Min, Byoung-Kyong; Dähne, Sven; Ahn, Min-Hee; Noh, Yung-Kyun; Müller, Klaus-Robert

    2016-11-01

    We present a fast and accurate non-invasive brain-machine interface (BMI) based on demodulating steady-state visual evoked potentials (SSVEPs) in electroencephalography (EEG). Our study reports an SSVEP-BMI that, for the first time, decodes primarily based on top-down and not bottom-up visual information processing. The experimental setup presents a grid-shaped flickering line array that the participants observe while intentionally attending to a subset of flickering lines representing the shape of a letter. While the flickering pixels stimulate the participant’s visual cortex uniformly with equal probability, the participant’s intention groups the strokes and thus perceives a ‘letter Gestalt’. We observed decoding accuracy of 35.81% (up to 65.83%) with a regularized linear discriminant analysis; on average 2.05-fold, and up to 3.77-fold greater than chance levels in multi-class classification. Compared to the EEG signals, an electrooculogram (EOG) did not significantly contribute to decoding accuracies. Further analysis reveals that the top-down SSVEP paradigm shows the most focalised activation pattern around occipital visual areas; Granger causality analysis consistently revealed prefrontal top-down control over early visual processing. Taken together, the present paradigm provides the first neurophysiological evidence for the top-down SSVEP BMI paradigm, which potentially enables multi-class intentional control of EEG-BMIs without using gaze-shifting.

  8. Top-Down Cognitive and Linguistic Influences on the Suppression of Spontaneous Otoacoustic Emissions

    Directory of Open Access Journals (Sweden)

    Viorica Marian

    2018-06-01

    Full Text Available Auditory sensation is often thought of as a bottom-up process, yet the brain exerts top-down control to affect how and what we hear. We report the discovery that the magnitude of top-down influence varies across individuals as a result of differences in linguistic background and executive function. Participants were 32 normal-hearing individuals (23 female varying in language background (11 English monolinguals, 10 Korean-English late bilinguals, and 11 Korean-English early bilinguals, as well as cognitive abilities (working memory, cognitive control. To assess efferent control over inner ear function, participants were presented with speech-sounds (e.g., /ba/, /pa/ in one ear while spontaneous otoacoustic emissions (SOAEs were measured in the contralateral ear. SOAEs are associated with the amplification of sound in the cochlea, and can be used as an index of top-down efferent activity. Individuals with bilingual experience and those with better cognitive control experienced larger reductions in the amplitude of SOAEs in response to speech stimuli, likely as a result of greater efferent suppression of amplification in the cochlea. This suppression may aid in the critical task of speech perception by minimizing the disruptive effects of noise. In contrast, individuals with better working memory exert less control over the cochlea, possibly due to a greater capacity to process complex stimuli at later stages. These findings demonstrate that even peripheral mechanics of auditory perception are shaped by top-down cognitive and linguistic influences.

  9. The distributed neural system for top-down letter processing: an fMRI study

    Science.gov (United States)

    Liu, Jiangang; Feng, Lu; Li, Ling; Tian, Jie

    2011-03-01

    This fMRI study used Psychophysiological interaction (PPI) to investigate top-down letter processing with an illusory letter detection task. After an initial training that became increasingly difficult, participant was instructed to detect a letter from pure noise images where there was actually no letter. Such experimental paradigm allowed for isolating top-down components of letter processing and minimizing the influence of bottom-up perceptual input. A distributed cortical network of top-down letter processing was identified by analyzing the functional connectivity patterns of letter-preferential area (LA) within the left fusiform gyrus. Such network extends from the visual cortex to high level cognitive cortexes, including the left middle frontal gyrus, left medial frontal gyrus, left superior parietal gyrus, bilateral precuneus, and left inferior occipital gyrus. These findings suggest that top-down letter processing contains not only regions for processing of letter phonology and appearance, but also those involved in internal information generation and maintenance, and attention and memory processing.

  10. ORGANIZATIONAL COMMUNICATION FROM THE TOP DOWN TO S.C. ARTEGO S.A.

    Directory of Open Access Journals (Sweden)

    DORU CÎRNU

    2016-06-01

    Full Text Available Vertical communication within the organization is twofold: top down and bottom up. The communication from the top down starts from the top management and continuous vertical hierarchy downward until the execution personnel from the base. This type of organizational communication aims to inform, advise, to guide, to train and evaluate subordinates, and to provide all necessary information on the objectives and organizational policies. Often, managers are overly optimistic about the clarity and complete vertical communication. In fact, they are usually managers who frequently recorded failures in the communication of important information or adequate training of subordinates. Starting from previous research more laboriou, among which we mention the GLOBE Study of American Professor Robert House or one conducted in our country (the study Comoros team coordinated by Professor Constantin Rosca, we did a study of smaller scale (at company level the vertical communication and efficiency of communication modalities of this type of managerial act. In this regard, a research performed at S. C. ARTEGO S.A. watched and how communication is done from top to bottom line information and training of personnel. The research, based on a questionnaire, which preserves the anonymity of respondents had interesting results, we stood to attention and present them in what follows. It was surprising to find that certain legal limits for working climat, especially causes of stress are almost unknown, even if some subjects gave positive answers to questions of this nature.

  11. Bottom line on the top people--by Speakman.

    Science.gov (United States)

    Hyde, A

    1979-07-13

    The Speakman review, that long-awaited probe into top posts in the NHS, is about to burst upon an impatient world. Alison Hyde has been taking a look at its contents. Speakman proposes 24 steps in appraising top jobs. He has some good tidings for area administrators and not so good tidings for works officers: the first are what he considers the supremos of the service and the second he places a poor third in the area ratings.

  12. Technology for assembling and welding of top and bottom nozzles in fuel assembly

    International Nuclear Information System (INIS)

    Xia Chenglie; Wan Longfu

    1989-10-01

    The construction character, technology and sequence of assembling and welding, assembling jig used for preventing from deformation, and acceptance test of welding technology for top and bottom nozzles are presented

  13. A top-down approach to fabrication of high quality vertical heterostructure nanowire arrays.

    Science.gov (United States)

    Wang, Hua; Sun, Minghua; Ding, Kang; Hill, Martin T; Ning, Cun-Zheng

    2011-04-13

    We demonstrate a novel top-down approach for fabricating nanowires with unprecedented complexity and optical quality by taking advantage of a nanoscale self-masking effect. We realized vertical arrays of nanowires of 20-40 nm in diameter with 16 segments of complex longitudinal InGaAsP/InP structures. The unprecedented high quality of etched wires is evidenced by the narrowest photoluminescence linewidth ever produced in similar wavelengths, indistinguishable from that of the corresponding wafer. This top-down, mask-free, large scale approach is compatible with the established device fabrication processes and could serve as an important alternative to the bottom-up approach, significantly expanding ranges and varieties of applications of nanowire technology.

  14. COMPARISON OF TOP AND BOTTOM LOADING OF A DEXTRAN GRADIENT FOR RAT PANCREATIC-ISLET PURIFICATION

    NARCIS (Netherlands)

    FRITSCHY, WM; VANSUYLICHEM, PTR; WOLTERS, GHJ; VANSCHILFGAARDE, R

    Rat pancreatic islet yields obtained with dextran gradient purification were compared after suspending the digest into either the top or the bottom layer of the gradient. A 5-layer discontinuous gradient was used, which consisted of 16 ml 31% dextran as bottom layer, overlayered with 25%, 23%, 20%

  15. 'Top-down' BACT analysis - Recommended approach and recent determinations

    International Nuclear Information System (INIS)

    Cochran, J.R.; Fagan, M.E.

    1991-01-01

    New EPA requirements for 'top-down' best available control technology (BACT) analyses have resulted in determinations that require more stringent control technologies. Accordingly, these permit decisions include nitrogen oxide (NO x ), sulfur dioxide, and particulate emission limits significantly lower than applicable New Source Performance Standards. However, with careful consideration of acceptable site-specific impacts, obtaining a reasonable BACT determination is still possible. This paper presents a step-by-step approach for conducting a top-down BACT analysis, and summarizes important considerations that will lead to a more effective BACT analysis. In addition, recent permit decisions regarding NO x emission rate and control technology requirements for combined cycle combustion turbine and coal fueled power plants are summarized and examined to ascertain the basis for decisions. Guidance from this paper will help applicants in preparing an accurate and comprehensive BACT analysis for their proposed projects

  16. Populating the landscape: A top-down approach

    International Nuclear Information System (INIS)

    Hawking, S.W.; Hertog, Thomas

    2006-01-01

    We put forward a framework for cosmology that combines the string landscape with no boundary initial conditions. In this framework, amplitudes for alternative histories for the universe are calculated with final boundary conditions only. This leads to a top-down approach to cosmology, in which the histories of the universe depend on the precise question asked. We study the observational consequences of no boundary initial conditions on the landscape, and outline a scheme to test the theory. This is illustrated in a simple model landscape that admits several alternative inflationary histories for the universe. Only a few of the possible vacua in the landscape will be populated. We also discuss in what respect the top-down approach differs from other approaches to cosmology in the string landscape, like eternal inflation

  17. Adding Gestalt to the picture. Comment on "Move me, astonish me…" delight my eyes and brain: The Vienna Integrated Model of top-down and bottom-up processes in Art Perception (VIMAP) and corresponding affective, evaluative, and neurophysiological correlates; by Matthew Pelowski et al.

    Science.gov (United States)

    Wagemans, Johan

    2017-07-01

    Matthew Pelowski and his colleagues from the Helmut Leder lab [17] have made a remarkable contribution to the field of art perception by reviewing the extensive and varied literature (+300 references) on all the factors involved, from a coherent, synthetic perspective-The Vienna Integrated Model of top-down and bottom-up processes in Art Perception (VIMAP). VIMAP builds on earlier attempts from the same group to provide a comprehensive theoretical framework, but it is much wider in scope and richer in the number of levels and topics covered under its umbrella. It is particularly strong in its discussion of the different psychological processes that lead to a wide range of possible responses to art-from mundane, superficial reactions to more profound responses characterized as moving, disturbing, and transformative. By including physiological, emotional, and evaluative factors, the model is able to address truly unique, even intimate responses to art such as awe, chills, thrills, and the experience of the sublime. The unique way in which this rich set of possible responses to art is achieved is through a series of five mandatory consecutive processing steps (each with their own typical duration), followed by two conditional additional steps (which take more time). Three processing checks along this cascade lead to three more or less spontaneous outcomes (<60 sec) and two more time-consuming ones (see their Fig. 1 for an excellent overview). I have no doubt that VIMAP will inspire a whole generation of scientists investigating perception and appreciation of art, testing specific hypotheses derived from this framework for decades to come.

  18. Experimental evidence for enhanced top-down control of freshwater macrophytes with nutrient enrichment.

    Science.gov (United States)

    Bakker, Elisabeth S; Nolet, Bart A

    2014-11-01

    The abundance of primary producers is controlled by bottom-up and top-down forces. Despite the fact that there is consensus that the abundance of freshwater macrophytes is strongly influenced by the availability of resources for plant growth, the importance of top-down control by vertebrate consumers is debated, because field studies yield contrasting results. We hypothesized that these bottom-up and top-down forces may interact, and that consumer impact on macrophyte abundance depends on the nutrient status of the water body. To test this hypothesis, experimental ponds with submerged vegetation containing a mixture of species were subjected to a fertilization treatment and we introduced consumers (mallard ducks, for 8 days) on half of the ponds in a full factorial design. Over the whole 66-day experiment fertilized ponds became dominated by Elodea nuttallii and ponds without extra nutrients by Chara globularis. Nutrient addition significantly increased plant N and P concentrations. There was a strong interactive effect of duck presence and pond nutrient status: macrophyte biomass was reduced (by 50%) after the presence of the ducks on fertilized ponds, but not in the unfertilized ponds. We conclude that nutrient availability interacts with top-down control of submerged vegetation. This may be explained by higher plant palatability at higher nutrient levels, either by a higher plant nutrient concentration or by a shift towards dominance of more palatable plant species, resulting in higher consumer pressure. Including nutrient availability may offer a framework to explain part of the contrasting field observations of consumer control of macrophyte abundance.

  19. Top-down cascades in lakes and oceans: Different perspectives but same story?

    KAUST Repository

    Hessen, Dag Olav

    2014-05-16

    While top-down cascades from fish to phytoplankton have been a core topic in limnology for the past four decades, it has attracted far less interest in marine ecology. This is partly for historical reasons, since lake studies have been motivated by the ability to regulate algal blooms induced by cultural eutrophication, while marine studies have been more oriented towards fish yield and thus bottom-up processes. Also freshwaters are closed ecosystems with lower diversity and complexity, making models and predictions on trophic levels and interactions comparatively simpler. Here, we compare some key properties of freshwater and marine top-down cascades and argue that despite some striking differences, the large number of freshwater studies may pose valuable insights also for marine systems. Moreover, we argue that there is an urgent need for more focus on top-down cascades in marine systems that address how top predators or fishing may propagate through the food web and impact autotrophic biomass, production, C-sequestration and thus ultimately the global carbon cycle and climate. © 2014 The Author. Published by Oxford University Press. All rights reserved.

  20. Infrared fixed points and fixed lines in the top-bottom-tau sector in supersymmetric grand unification

    International Nuclear Information System (INIS)

    Schrempp, B.

    1994-10-01

    The two loop 'top-down' renormalization group flow for the top, bottom and tau Yukawa couplings, from μ=M GUT ≅O(10 16 GeV) to μ≅m t , is explored in the framework of supersymmetric grand unification; reproduction of the physical bottom and tau masses is required. Instead of following the recent trend of implementing exact Yukawa coupling unification i) a search for infrared (IR) fixed lines and fixed points in the m t pole -tan β plane is performed and ii) the extent to which these imply approximate Yukawa unification is determined. In the m t pole -tan β plane two IR fixed lines, intersecting in an IR fixed point, are located. The more attractive fixed line has a branch of almost constant top mass, m t pole ≅168≅180 GeV (close to the experimental value), for the large interval 2.5 GUT approximately. The less attractive fixed line as well as the fixed point at m t pole ≅170 GeV, tan β≅55 implement approximate top-bottom Yukawa unification at all scales μ. The renormalization group flow is attracted towards the IR fixed point by way of the more attractive IR fixed line. The fixed point and lines are distinct from the much quoted effective IR fixed point m t pole ≅O(200 GeV) sin β. (orig.)

  1. Top-Down Enterprise Application Integration with Reference Models

    Directory of Open Access Journals (Sweden)

    Willem-Jan van den Heuvel

    2000-11-01

    Full Text Available For Enterprise Resource Planning (ERP systems such as SAP R/3 or IBM SanFrancisco, the tailoring of reference models for customizing the ERP systems to specific organizational contexts is an established approach. In this paper, we present a methodology that uses such reference models as a starting point for a top-down integration of enterprise applications. The re-engineered models of legacy systems are individually linked via cross-mapping specifications to the forward-engineered reference model's specification. The actual linking of reference and legacy models is done with a methodology for connecting (new business objects with (old legacy systems.

  2. Piezoresistance of top-down suspended Si nanowires

    International Nuclear Information System (INIS)

    Koumela, A; Mercier, D; Dupre, C; Jourdan, G; Marcoux, C; Ollier, E; Duraffourg, L; Purcell, S T

    2011-01-01

    Measurements of the gauge factor of suspended, top-down silicon nanowires are presented. The nanowires are fabricated with a CMOS compatible process and with doping concentrations ranging from 2 x 10 20 down to 5 x 10 17 cm -3 . The extracted gauge factors are compared with results on identical non-suspended nanowires and with state-of-the-art results. An increase of the gauge factor after suspension is demonstrated. For the low doped nanowires a value of 235 is measured. Particular attention was paid throughout the experiments to distinguishing real resistance change due to strain modulation from resistance fluctuations due to charge trapping. Furthermore, a numerical model correlating surface charge density with the gauge factor is presented. Comparison of the simulations with experimental measurements shows the validity of this approach. These results contribute to a deeper understanding of the piezoresistive effect in Si nanowires.

  3. Top-down control of arousal and sleep: Fundamentals and clinical implications.

    Science.gov (United States)

    Krone, Lukas; Frase, Lukas; Piosczyk, Hannah; Selhausen, Peter; Zittel, Sulamith; Jahn, Friederike; Kuhn, Marion; Feige, Bernd; Mainberger, Florian; Klöppel, Stefan; Riemann, Dieter; Spiegelhalder, Kai; Baglioni, Chiara; Sterr, Annette; Nissen, Christoph

    2017-02-01

    Mammalian sleep emerges from attenuated activity in the ascending reticular arousal system (ARAS), the main arousal network of the brain. This system originates in the brainstem and activates the thalamus and cortex during wakefulness via a well-characterized 'bottom-up' pathway. Recent studies propose that a less investigated cortico-thalamic 'top-down' pathway also regulates sleep. The present work integrates the current evidence on sleep regulation with a focus on the 'top-down' pathway and explores the potential to translate this information into clinically relevant interventions. Specifically, we elaborate the concept that arousal and sleep continuity in humans can be modulated by non-invasive brain stimulation (NIBS) techniques that increase or decrease cortical excitability. Based on preclinical studies, the modulatory effects of the stimulation are thought to extend to subcortical arousal networks. Further exploration of the 'top-down' regulation of sleep and its modulation through non-invasive brain stimulation techniques may contribute to the development of novel treatments for clinical conditions of disrupted arousal and sleep, which are among the major health problems worldwide. Copyright © 2016 Elsevier Ltd. All rights reserved.

  4. Functional overlap of top-down emotion regulation and generation: an fMRI study identifying common neural substrates between cognitive reappraisal and cognitively generated emotions.

    Science.gov (United States)

    Otto, Benjamin; Misra, Supriya; Prasad, Aditya; McRae, Kateri

    2014-09-01

    One factor that influences the success of emotion regulation is the manner in which the regulated emotion was generated. Recent research has suggested that reappraisal, a top-down emotion regulation strategy, is more effective in decreasing self-reported negative affect when emotions were generated from the top-down, versus the bottom-up. On the basis of a process overlap framework, we hypothesized that the neural regions active during reappraisal would overlap more with emotions that were generated from the top-down, rather than from the bottom-up. In addition, we hypothesized that increased neural overlap between reappraisal and the history effects of top-down emotion generation would be associated with increased reappraisal success. The results of several analyses suggested that reappraisal and emotions that were generated from the top-down share a core network of prefrontal, temporal, and cingulate regions. This overlap is specific; no such overlap was observed between reappraisal and emotions that were generated in a bottom-up fashion. This network consists of regions previously implicated in linguistic processing, cognitive control, and self-relevant appraisals, which are processes thought to be crucial to both reappraisal and top-down emotion generation. Furthermore, individuals with high reappraisal success demonstrated greater neural overlap between reappraisal and the history of top-down emotion generation than did those with low reappraisal success. The overlap of these key regions, reflecting overlapping processes, provides an initial insight into the mechanism by which generation history may facilitate emotion regulation.

  5. Top-down contextual knowledge guides visual attention in infancy.

    Science.gov (United States)

    Tummeltshammer, Kristen; Amso, Dima

    2017-10-26

    The visual context in which an object or face resides can provide useful top-down information for guiding attention orienting, object recognition, and visual search. Although infants have demonstrated sensitivity to covariation in spatial arrays, it is presently unclear whether they can use rapidly acquired contextual knowledge to guide attention during visual search. In this eye-tracking experiment, 6- and 10-month-old infants searched for a target face hidden among colorful distracter shapes. Targets appeared in Old or New visual contexts, depending on whether the visual search arrays (defined by the spatial configuration, shape and color of component items in the search display) were repeated or newly generated throughout the experiment. Targets in Old contexts appeared in the same location within the same configuration, such that context covaried with target location. Both 6- and 10-month-olds successfully distinguished between Old and New contexts, exhibiting faster search times, fewer looks at distracters, and more anticipation of targets when contexts repeated. This initial demonstration of contextual cueing effects in infants indicates that they can use top-down information to facilitate orienting during memory-guided visual search. © 2017 John Wiley & Sons Ltd.

  6. Top-Down Control of Diesel-Degrading Prokaryotic Communities.

    Science.gov (United States)

    Sauret, Caroline; Böttjer, Daniela; Talarmin, Agathe; Guigue, Catherine; Conan, Pascal; Pujo-Pay, Mireille; Ghiglione, Jean-François

    2015-08-01

    Biostimulation through the addition of inorganic nutrients has been the most widely practiced bioremediation strategy in oil-polluted marine waters. However, little attention has so far been paid to the microbial food web and the impact of top-down control that directly or indirectly influences the success of the bioremediation. We designed a mesocosm experiment using pre-filtered (diesel fuel. Prokaryotes, HNF and VLP abundances showed a predator-prey succession, with a co-development of HNF and VLP. In the polluted system, we observed a stronger impact of viral lysis on prokaryotic abundances than in the control. Analysis of the diversity revealed that a bloom of Vibrio sp. occurred in the polluted mesocosm. That bloom was rapidly followed by a less abundant and more even community of predation-resistant bacteria, including known hydrocarbon degraders such as Oleispira spp. and Methylophaga spp. and opportunistic bacteria such as Percisivirga spp., Roseobacter spp. and Phaeobacter spp. The shift in prokaryotic dominance in response to viral lysis provided clear evidence of the 'killing the winner' model. Nevertheless, despite clear effects on prokaryotic abundance, activity and diversity, the diesel degradation was not impacted by top-down control. The present study investigates for the first time the functioning of a complex microbial network (including VLP) using a nutrient-based biostimulation strategy and highlights some key processes useful for tailoring bioremediation.

  7. Top-down attention based on object representation and incremental memory for knowledge building and inference.

    Science.gov (United States)

    Kim, Bumhwi; Ban, Sang-Woo; Lee, Minho

    2013-10-01

    Humans can efficiently perceive arbitrary visual objects based on an incremental learning mechanism with selective attention. This paper proposes a new task specific top-down attention model to locate a target object based on its form and color representation along with a bottom-up saliency based on relativity of primitive visual features and some memory modules. In the proposed model top-down bias signals corresponding to the target form and color features are generated, which draw the preferential attention to the desired object by the proposed selective attention model in concomitance with the bottom-up saliency process. The object form and color representation and memory modules have an incremental learning mechanism together with a proper object feature representation scheme. The proposed model includes a Growing Fuzzy Topology Adaptive Resonance Theory (GFTART) network which plays two important roles in object color and form biased attention; one is to incrementally learn and memorize color and form features of various objects, and the other is to generate a top-down bias signal to localize a target object by focusing on the candidate local areas. Moreover, the GFTART network can be utilized for knowledge inference which enables the perception of new unknown objects on the basis of the object form and color features stored in the memory during training. Experimental results show that the proposed model is successful in focusing on the specified target objects, in addition to the incremental representation and memorization of various objects in natural scenes. In addition, the proposed model properly infers new unknown objects based on the form and color features of previously trained objects. Copyright © 2013 Elsevier Ltd. All rights reserved.

  8. Top-Down Influences on Local Networks: Basic Theory with Experimental Implications

    Directory of Open Access Journals (Sweden)

    Ramesh eSrinivasan

    2013-04-01

    Full Text Available The response of a population of sensory neurons to an external stimulus depends not only on the receptive field properties of the neurons, but also the level of arousal and attention or goal-oriented cognitive biases that guide information processing. These top-down effects on the sensory neurons bias the output of the neurons and affect behavioral outcomes such as stimulus detection, discrimination, and response time. In any physiological study, neural dynamics are observed in a specific brain state; the background state partly determines neuronal excitability. Experimental studies in humans and animal models have also demonstrated that slow oscillations (typically in the alpha or theta bands modulate the fast oscillations (gamma band associated with local networks of neurons. Cross-frequency interaction is of interest as a mechanism for top-down or bottom-up interactions between systems at different spatial scales. We develop a generic model of top-down influences on local networks appropriate for comparison with EEG. EEG provides excellent temporal resolution to investigate neuronal oscillations but is space-averaged on the cm scale. Thus, appropriate EEG models are developed in terms of population synaptic activity. We used the Wilson-Cowan population model to investigate fast (gamma band oscillations generated by a local network of excitatory and inhibitory neurons. We modified the Wilson-Cowan equations to make them more physiologically realistic by explicitly incorporating background state variables into the model. We found that the population response is strongly influenced by the background state. We apply the model to reproduce the modulation of gamma rhythms by theta rhythms as has been observed in animal models and human ECoG and EEG studies. The concept of a dynamic background state presented here using the Wilson-Cowan model can be readily applied to incorporate top-down modulation in more detailed models of specific sensory

  9. Pressure drop performance evaluation for test assemblies with the newly developed top and bottom nozzles

    International Nuclear Information System (INIS)

    Lee, S. K.; Park, N. K.; Su, J. M.; Kim, H. K.; Lee, J. N.; Kim, K. T.

    2003-01-01

    To perform the hydraulic test for the newly developed top and bottom nozzles, two kinds of test assemblies were manufactured i. e. one is the test assembly which has the newly developed top and bottom nozzles and the other is Guardian test assembly which is commercially in mass production now. The test results show that the test assembly with one top nozzle and two bottom nozzles has a greater pressure loss coefficient than Guardian test assembly by 60.9% and 90.4% at the bottom nozzle location. This cause is due to the debris filtering plate for bottom nozzle to improve a filtering efficiency aginst foreign material. In the region of mid grid and top nozzle, there is no difference in pressure loss coefficient between the test assemblies since the componet features in these regions are very similar or same each other. The loss coefficients are 14.2% and 21.9% for model A and B respectively in the scale of test assembly, and the value would be within the 10% in the scale of real fuel assembly. As a result of hydraulic performance evaluation, model A is superior to model B

  10. Transport of mass goods on the top run and bottom run of belt conveyors

    Energy Technology Data Exchange (ETDEWEB)

    Zimmermann, D

    1977-06-01

    For combined coal winning from the collieries 'General Blumenthal' and 'Ewald Fortsetzung' a large belt conveyor plant was taken into operation which is able to transport 1360 tons/h in the top run and 300 tons/h of dirt in the bottom run. The different types of coal are transported separately in intermittent operation with the aid of bunker systems connected to the front and rear of the belt conveyor. Persons can be transported in the top run as well as in the bottom run.

  11. Conflict-Triggered Top-Down Control: Default Mode, Last Resort, or No Such Thing?

    Science.gov (United States)

    Bugg, Julie M.

    2014-01-01

    The conflict monitoring account posits that globally high levels of conflict trigger engagement of top-down control; however, recent findings point to the mercurial nature of top-down control in high conflict contexts. The current study examined the potential moderating effect of associative learning on conflict-triggered top-down control…

  12. Radiation Safety Culture in the UK Medical Sector: A Top to Bottom Strategy.

    Science.gov (United States)

    Chapple, Claire-Louise; Bradley, Andy; Murray, Maria; Orr, Phil; Reay, Jill; Riley, Peter; Rogers, Andy; Sandhu, Navneet; Thurston, Jim

    2017-04-01

    UK professional bodies have established a number of sectorial working parties to provide guidance on the improvement of radiation safety (RS) culture in the workplace. The medical sector provides unique challenges in this regard, and the remit of the medical group was to review the current state of RS culture and to develop a framework for improvement. The review of current RS culture was based on measurable indicators, including data from regulatory inspections, personal monitoring data and incident data. An online survey to capture the RS-related views and experience of hospital staff at all levels was carried out, and the responses provided a wealth of information on RS awareness and implementation across the country. The framework for improving RS culture includes both 'top-down' initiatives to engage management and regulators, and 'bottom-up' initiatives relating to engagement and training of different staff groups. A 'Ten-point Assessment' on what constitutes a good approach to medical RS culture has been proposed, which provides a tool for management to assess RS culture in the workplace and has potential use in regulatory inspections in the UK. © The Author 2016. Published by Oxford University Press. All rights reserved. For Permissions, please email: journals.permissions@oup.com.

  13. Radiation safety culture in the UK medical sector: a top to bottom strategy

    International Nuclear Information System (INIS)

    Chapple, Claire-Louise; Bradley, Andy; Murray, Maria; Orr, Phil; Reay, Jill; Riley, Peter; Rogers, Andy; Sandhu, Navneet; Thurston, Jim

    2017-01-01

    UK professional bodies have established a number of sectorial working parties to provide guidance on the improvement of radiation safety (RS) culture in the workplace. The medical sector provides unique challenges in this regard, and the remit of the medical group was to review the current state of RS culture and to develop a framework for improvement. The review of current RS culture was based on measurable indicators, including data from regulatory inspections, personal monitoring data and incident data. An online survey to capture the RS-related views and experience of hospital staff at all levels was carried out, and the responses provided a wealth of information on RS awareness and implementation across the country. The framework for improving RS culture includes both 'top-down' initiatives to engage management and regulators, and 'bottom-up' initiatives relating to engagement and training of different staff groups. A 'Ten-point Assessment' on what constitutes a good approach to medical RS culture has been proposed, which provides a tool for management to assess RS culture in the workplace and has potential use in regulatory inspections in the UK. (authors)

  14. Architecture of top down, parallel pattern recognition system TOPS and its application to the MR head images

    International Nuclear Information System (INIS)

    Matsunoshita, Jun-ichi; Akamatsu, Shigeo; Yamamoto, Shinji.

    1993-01-01

    This paper describes about the system architecture of a new image recognition system TOPS (top-down parallel pattern recognition system), and its application to the automatic extraction of brain organs (cerebrum, cerebellum, brain stem) from 3D-MRI images. Main concepts of TOPS are as follows: (1) TOPS is the top-down type recognition system, which allows parallel models in each level of hierarchy structure. (2) TOPS allows parallel image processing algorithms for one purpose (for example, for extraction of one special organ). This results in multiple candidates for one purpose, and judgment to get unique solution for it will be made at upper level of hierarchy structure. (author)

  15. The Ups and Downs of Repeated Cleavage and Internal Fragment Production in Top-Down Proteomics

    Science.gov (United States)

    Lyon, Yana A.; Riggs, Dylan; Fornelli, Luca; Compton, Philip D.; Julian, Ryan R.

    2018-01-01

    Analysis of whole proteins by mass spectrometry, or top-down proteomics, has several advantages over methods relying on proteolysis. For example, proteoforms can be unambiguously identified and examined. However, from a gas-phase ion-chemistry perspective, proteins are enormous molecules that present novel challenges relative to peptide analysis. Herein, the statistics of cleaving the peptide backbone multiple times are examined to evaluate the inherent propensity for generating internal versus terminal ions. The raw statistics reveal an inherent bias favoring production of terminal ions, which holds true regardless of protein size. Importantly, even if the full suite of internal ions is generated by statistical dissociation, terminal ions are predicted to account for at least 50% of the total ion current, regardless of protein size, if there are three backbone dissociations or fewer. Top-down analysis should therefore be a viable approach for examining proteins of significant size. Comparison of the purely statistical analysis with actual top-down data derived from ultraviolet photodissociation (UVPD) and higher-energy collisional dissociation (HCD) reveals that terminal ions account for much of the total ion current in both experiments. Terminal ion production is more favored in UVPD relative to HCD, which is likely due to differences in the mechanisms controlling fragmentation. Importantly, internal ions are not found to dominate from either the theoretical or experimental point of view. [Figure not available: see fulltext.

  16. Top-Down Historical Phonology of Rote-Meto

    Directory of Open Access Journals (Sweden)

    Owen Edwards

    2018-05-01

    Full Text Available This paper examines the historical phonology of the Rote-Meto languages through a top-down perspective. It describes the sound changes which have taken place between Proto-Malayo-Polynesian and the present-day languages. This reveals a number of shared innovations between Meto and the languages of west Rote, as well as changes shared by the other languages of Rote. Thus, a West Rote-Meto subgroup is identified, as well as a Nuclear Rote subgroup. Within Austronesian, there are phonological innovations shared between Rote-Meto and a number of languages of Timor and surrounding islands. This provides evidence for a Timor-Wetar-Babar subgroup, though this group does not include all languages of Timor.

  17. Factors That Modulate Neurogenesis: A Top-Down Approach.

    Science.gov (United States)

    LaDage, Lara D

    2016-08-24

    Although hippocampal neurogenesis in the adult brain has been conserved across the vertebrate lineage, laboratory studies have primarily examined this phenomenon in rodent models. This approach has been successful in elucidating important factors and mechanisms that can modulate rates of hippocampal neurogenesis, including hormones, environmental complexity, learning and memory, motor stimulation, and stress. However, recent studies have found that neurobiological research on neurogenesis in rodents may not easily translate to, or explain, neurogenesis patterns in nonrodent systems, particularly in species examined in the field. This review examines some of the evolutionary and ecological variables that may also modulate neurogenesis patterns. This 'top-down' and more naturalistic approach, which incorporates ecology and natural history, particularly of nonmodel species, may allow for a more comprehensive understanding of the functional significance of neurogenesis. © 2016 S. Karger AG, Basel.

  18. Congruency effects in the remote distractor paradigm: evidence for top-down modulation.

    Science.gov (United States)

    Born, Sabine; Kerzel, Dirk

    2009-08-10

    In three experiments, we examined effects of target-distractor similarity in the remote distractor effect (RDE). Observers made saccades to peripheral targets that were either gray or green. Foveal or peripheral distractors were presented at the same time. The distractors could either share the target's defining property (congruent) or be different from the target (incongruent). Congruent distractors slowed down saccadic reaction times more than incongruent distractors. The increase of the RDE with target-distractor congruency depended on task demands. The more participants had to rely on the target property to locate the target, the larger the congruency effect. We conclude that the RDE can be modulated in a top-down manner. Alternative explanations such as persisting memory traces for the target property or differences in stimulus arrangement were considered but discarded. Our claim is in line with models of saccade generation which assume that the structures underlying the RDE (e.g. the superior colliculus) receive bottom-up as well as top-down information.

  19. Searches for scalar top and scalar bottom quarks at LEP2

    CERN Document Server

    Barate, R; Décamp, D; Ghez, P; Goy, C; Lees, J P; Lucotte, A; Minard, M N; Nief, J Y; Pietrzyk, B; Casado, M P; Chmeissani, M; Comas, P; Crespo, J M; Delfino, M C; Fernández, E; Fernández-Bosman, M; Garrido, L; Juste, A; Martínez, M; Merino, G; Miquel, R; Mir, L M; Padilla, C; Park, I C; Pascual, A; Perlas, J A; Riu, I; Sánchez, F; Teubert, F; Colaleo, A; Creanza, D; De Palma, M; Gelao, G; Iaselli, Giuseppe; Maggi, G; Maggi, M; Marinelli, N; Nuzzo, S; Ranieri, A; Raso, G; Ruggieri, F; Selvaggi, G; Silvestris, L; Tempesta, P; Tricomi, A; Zito, G; Huang, X; Lin, J; Ouyang, Q; Wang, T; Xie, Y; Xu, R; Xue, S; Zhang, J; Zhang, L; Zhao, W; Abbaneo, D; Alemany, R; Bazarko, A O; Becker, U; Bright-Thomas, P G; Cattaneo, M; Cerutti, F; Dissertori, G; Drevermann, H; Forty, Roger W; Frank, M; Hagelberg, R; Hansen, J B; Harvey, J; Janot, P; Jost, B; Kneringer, E; Knobloch, J; Lehraus, Ivan; Mato, P; Minten, Adolf G; Moneta, L; Pacheco, A; Pusztaszeri, J F; Ranjard, F; Rizzo, G; Rolandi, Luigi; Rousseau, D; Schlatter, W D; Schmitt, M; Schneider, O; Tejessy, W; Tomalin, I R; Wachsmuth, H W; Wagner, A; Ajaltouni, Ziad J; Barrès, A; Boyer, C; Falvard, A; Ferdi, C; Gay, P; Guicheney, C; Henrard, P; Jousset, J; Michel, B; Monteil, S; Montret, J C; Pallin, D; Perret, P; Podlyski, F; Proriol, J; Rosnet, P; Rossignol, J M; Fearnley, Tom; Hansen, J D; Hansen, J R; Hansen, P H; Nilsson, B S; Rensch, B; Wäänänen, A; Daskalakis, G; Kyriakis, A; Markou, C; Simopoulou, Errietta; Vayaki, Anna; Blondel, A; Brient, J C; Machefert, F P; Rougé, A; Rumpf, M; Valassi, Andrea; Videau, H L; Focardi, E; Parrini, G; Zachariadou, K; Cavanaugh, R J; Corden, M; Georgiopoulos, C H; Hühn, T; Jaffe, D E; Antonelli, A; Bencivenni, G; Bologna, G; Bossi, F; Campana, P; Capon, G; Casper, David William; Chiarella, V; Felici, G; Laurelli, P; Mannocchi, G; Murtas, F; Murtas, G P; Passalacqua, L; Pepé-Altarelli, M; Curtis, L; Dorris, S J; Halley, A W; Knowles, I G; Lynch, J G; O'Shea, V; Raine, C; Scarr, J M; Smith, K; Teixeira-Dias, P; Thompson, A S; Thomson, E; Thomson, F; Turnbull, R M; Buchmüller, O L; Dhamotharan, S; Geweniger, C; Graefe, G; Hanke, P; Hansper, G; Hepp, V; Kluge, E E; Putzer, A; Sommer, J; Tittel, K; Werner, S; Wunsch, M; Beuselinck, R; Binnie, David M; Cameron, W; Dornan, Peter J; Girone, M; Goodsir, S M; Martin, E B; Morawitz, P; Moutoussi, A; Nash, J; Sedgbeer, J K; Spagnolo, P; Stacey, A M; Williams, M D; Ghete, V M; Girtler, P; Kuhn, D; Rudolph, G; Betteridge, A P; Bowdery, C K; Colrain, P; Crawford, G; Finch, A J; Foster, F; Hughes, G; Jones, R W L; Sloan, Terence; Whelan, E P; Williams, M I; Hoffmann, C; Jakobs, K; Kleinknecht, K; Quast, G; Renk, B; Rohne, E; Sander, H G; Van Gemmeren, P; Zeitnitz, C; Aubert, Jean-Jacques; Benchouk, C; Bonissent, A; Bujosa, G; Carr, J; Coyle, P; Diaconu, C A; Ealet, A; Fouchez, D; Konstantinidis, N P; Leroy, O; Motsch, F; Payre, P; Talby, M; Sadouki, A; Thulasidas, M; Tilquin, A; Trabelsi, K; Aleppo, M; Antonelli, M; Ragusa, F; Berlich, R; Blum, Walter; Büscher, V; Dietl, H; Ganis, G; Gotzhein, C; Kroha, H; Lütjens, G; Lutz, Gerhard; Männer, W; Moser, H G; Richter, R H; Rosado-Schlosser, A; Schael, S; Settles, Ronald; Seywerd, H C J; Saint-Denis, R; Stenzel, H; Wiedenmann, W; Wolf, G; Boucrot, J; Callot, O; Chen, S; Cordier, A; Davier, M; Duflot, L; Grivaz, J F; Heusse, P; Höcker, A; Jacholkowska, A; Jacquet, M; Kim, D W; Le Diberder, F R; Lefrançois, J; Lutz, A M; Nikolic, I A; Schune, M H; Serin, L; Simion, S; Tournefier, E; Veillet, J J; Videau, I; Zerwas, D; Azzurri, P; Bagliesi, G; Bettarini, S; Bozzi, C; Calderini, G; Ciulli, V; Dell'Orso, R; Fantechi, R; Ferrante, I; Giassi, A; Gregorio, A; Ligabue, F; Lusiani, A; Marrocchesi, P S; Messineo, A; Palla, Fabrizio; Sanguinetti, G; Sciabà, A; Sguazzoni, G; Steinberger, Jack; Tenchini, Roberto; Vannini, C; Venturi, A; Verdini, P G; Blair, G A; Bryant, L M; Chambers, J T; Gao, Y; Green, M G; Medcalf, T; Perrodo, P; Strong, J A; Von Wimmersperg-Töller, J H; Botterill, David R; Clifft, R W; Edgecock, T R; Haywood, S; Maley, P; Norton, P R; Thompson, J C; Wright, A E; Bloch-Devaux, B; Colas, P; Fabbro, B; Kozanecki, Witold; Lançon, E; Lemaire, M C; Locci, E; Pérez, P; Rander, J; Renardy, J F; Rosowsky, A; Roussarie, A; Schuller, J P; Schwindling, J; Trabelsi, A; Vallage, B; Black, S N; Dann, J H; Kim, H Y; Litke, A M; McNeil, M A; Taylor, G; Booth, C N; Boswell, R; Brew, C A J; Cartwright, S L; Combley, F; Kelly, M S; Lehto, M H; Newton, W M; Reeve, J; Thompson, L F; Affholderbach, K; Böhrer, A; Brandt, S; Cowan, G D; Foss, J; Grupen, Claus; Lutters, G; Saraiva, P; Smolik, L; Stephan, F; Apollonio, M; Bosisio, L; Della Marina, R; Giannini, G; Gobbo, B; Musolino, G; Pütz, J; Rothberg, J E; Wasserbaech, S R; Williams, R W; Armstrong, S R; Charles, E; Elmer, P; Ferguson, D P S; González, S; Greening, T C; Hayes, O J; Hu, H; Jin, S; McNamara, P A; Nachtman, J M; Nielsen, J; Orejudos, W; Pan, Y B; Saadi, Y; Scott, I J; Walsh, J; Wu Sau Lan; Wu, X; Yamartino, J M; Zobernig, G

    1997-01-01

    Searches for scalar top and bottom quarks have been performed with data collected by the ALEPH detector at LEP. The data sample consists of 21.7 pb^-1 taken at sqrt{s} = 161, 170, and 172~GeV and 5.7 pb^-1 taken at sqrt{s} = 130 and 136~GeV. No evidence for scalar top quarks or scalar bottom quarks was found in the channels stop --> c chi, stop --> b l snu, and sbottom --> b chi. For the channel stop --> c chi a limit of 67 GeV/c^2 has been set on the scalar top quark mass, independent of the mixing angle between the supersymmetric partners of the left and right-handed states of the top quark. This limit assumes a mass difference between the stop and the chi of at least 10 GeV/c^2. For the channel stop --> b l snu the mixing-angle independent scalar top limit is 70 GeV/c^2, assuming a mass difference between the stop and the snu of at least 10 GeV/c^2. For the channel sbottom --> b chi, a limit of 73 GeV/c^2 has been set on the mass of the supersymmetric partner of the left-handed state of the bottom quark. T...

  20. Searches for scalar top and scalar bottom quarks at LEP2

    Science.gov (United States)

    ALEPH Collaboration; Barate, R.; Buskulic, D.; Decamp, D.; Ghez, P.; Goy, C.; Lees, J.-P.; Lucotte, A.; Minard, M.-N.; Nief, J.-Y.; Pietrzyk, B.; Casado, M. P.; Chmeissani, M.; Comas, P.; Crespo, J. M.; Delfino, M.; Fernandez, E.; Fernandez-Bosman, M.; Garrido, Ll.; Juste, A.; Martinez, M.; Merino, G.; Miquel, R.; Mir, Ll. M.; Padilla, C.; Park, I. C.; Pascual, A.; Perlas, J. A.; Riu, I.; Sanchez, F.; Teubert, F.; Colaleo, A.; Creanza, D.; de Palma, M.; Gelao, G.; Iaselli, G.; Maggi, G.; Maggi, M.; Marinelli, N.; Nuzzo, S.; Ranieri, A.; Raso, G.; Ruggieri, F.; Selvaggi, G.; Silvestris, L.; Tempesta, P.; Tricomi, A.; Zito, G.; Huang, X.; Lin, J.; Ouyang, Q.; Wang, T.; Xie, Y.; Xu, R.; Xue, S.; Zhang, J.; Zhang, L.; Zhao, W.; Abbaneo, D.; Alemany, R.; Bazarko, A. O.; Becker, U.; Bright-Thomas, P.; Cattaneo, M.; Cerutti, F.; Dissertori, G.; Drevermann, H.; Forty, R. W.; Frank, M.; Hagelberg, R.; Hansen, J. B.; Harvey, J.; Janot, P.; Jost, B.; Kneringer, E.; Knobloch, J.; Lehraus, I.; Mato, P.; Minten, A.; Moneta, L.; Pacheco, A.; Pusztaszeri, J.-F.; Ranjard, F.; Rizzo, G.; Rolandi, L.; Rousseau, D.; Schlatter, D.; Schmitt, M.; Schneider, O.; Tejessy, W.; Tomalin, I. R.; Wachsmuth, H.; Wagner, A.; Ajaltouni, Z.; Barrès, A.; Boyer, C.; Falvard, A.; Ferdi, C.; Gay, P.; Guicheney, C.; Henrard, P.; Jousset, J.; Michel, B.; Monteil, S.; Montret, J.-C.; Pallin, D.; Perret, P.; Podlyski, F.; Proriol, J.; Rosnet, P.; Rossignol, J.-M.; Fearnley, T.; Hansen, J. D.; Hansen, J. R.; Hansen, P. H.; Nilsson, B. S.; Rensch, B.; Wäänänen, A.; Daskalakis, G.; Kyriakis, A.; Markou, C.; Simopoulou, E.; Vayaki, A.; Blondel, A.; Brient, J. C.; Machefert, F.; Rougé, A.; Rumpf, M.; Valassi, A.; Videau, H.; Focardi, E.; Parrini, G.; Zachariadou, K.; Cavanaugh, R.; Corden, M.; Georgiopoulos, C.; Huehn, T.; Jaffe, D. E.; Antonelli, A.; Bencivenni, G.; Bologna, G.; Bossi, F.; Campana, P.; Capon, G.; Casper, D.; Chiarella, V.; Felici, G.; Laurelli, P.; Mannocchi, G.; Murtas, F.; Murtas, G. P.; Passalacqua, L.; Pepe-Altarelli, M.; Curtis, L.; Dorris, S. J.; Halley, A. W.; Knowles, I. G.; Lynch, J. G.; O'Shea, V.; Raine, C.; Scarr, J. M.; Smith, K.; Teixeira-Dias, P.; Thompson, A. S.; Thomson, E.; Thomson, F.; Turnbull, R. M.; Buchmüller, O.; Dhamotharan, S.; Geweniger, C.; Graefe, G.; Hanke, P.; Hansper, G.; Hepp, V.; Kluge, E. E.; Putzer, A.; Sommer, J.; Tittel, K.; Werner, S.; Wunsch, M.; Beuselinck, R.; Binnie, D. M.; Cameron, W.; Dornan, P. J.; Girone, M.; Goodsir, S.; Martin, E. B.; Morawitz, P.; Moutoussi, A.; Nash, J.; Sedgbeer, J. K.; Spagnolo, P.; Stacey, A. M.; Williams, M. D.; Ghete, V. M.; Girtler, P.; Kuhn, D.; Rudolph, G.; Betteridge, A. P.; Bowdery, C. K.; Colrain, P.; Crawford, G.; Finch, A. J.; Foster, F.; Hughes, G.; Jones, R. W. L.; Sloan, T.; Whelan, E. P.; Williams, M. I.; Hoffmann, C.; Jakobs, K.; Kleinknecht, K.; Quast, G.; Renk, B.; Rohne, E.; Sander, H.-G.; van Gemmeren, P.; Zeitnitz, C.; Aubert, J. J.; Benchouk, C.; Bonissent, A.; Bujosa, G.; Carr, J.; Coyle, P.; Diaconu, C.; Ealet, A.; Fouchez, D.; Konstantinidis, N.; Leroy, O.; Motsch, F.; Payre, P.; Talby, M.; Sadouki, A.; Thulasidas, M.; Tilquin, A.; Trabelsi, K.; Aleppo, M.; Antonelli, M.; Ragusa, F.; Berlich, R.; Blum, W.; Büscher, V.; Dietl, H.; Ganis, G.; Gotzhein, C.; Kroha, H.; Lütjens, G.; Lutz, G.; Männer, W.; Moser, H.-G.; Richter, R.; Rosado-Schlosser, A.; Schael, S.; Settles, R.; Seywerd, H.; St. Denis, R.; Stenzel, H.; Wiedenmann, W.; Wolf, G.; Boucrot, J.; Callot, O.; Chen, S.; Cordier, A.; Davier, M.; Duflot, L.; Grivaz, J.-F.; Heusse, Ph.; Höcker, A.; Jacholkowska, A.; Jacquet, M.; Kim, D. W.; Le Diberder, F.; Lefrançois, J.; Lutz, A.-M.; Nikolic, I.; Schune, M.-H.; Serin, L.; Simion, S.; Tournefier, E.; Veillet, J.-J.; Videau, I.; Zerwas, D.; Azzurri, P.; Bagliesi, G.; Bettarini, S.; Bozzi, C.; Calderini, G.; Ciulli, V.; dell'Orso, R.; Fantechi, R.; Ferrante, I.; Giassi, A.; Gregorio, A.; Ligabue, F.; Lusiani, A.; Marrocchesi, P. S.; Messineo, A.; Palla, F.; Sanguinetti, G.; Sciabà, A.; Sguazzoni, G.; Steinberger, J.; Tenchini, R.; Vannini, C.; Venturi, A.; Verdini, P. G.; Blair, G. A.; Bryant, L. M.; Chambers, J. T.; Gao, Y.; Green, M. G.; Medcalf, T.; Perrodo, P.; Strong, J. A.; von Wimmersperg-Toeller, J. H.; Botterill, D. R.; Clifft, R. W.; Edgecock, T. R.; Haywood, S.; Maley, P.; Norton, P. R.; Thompson, J. C.; Wright, A. E.; Bloch-Devaux, B.; Colas, P.; Fabbro, B.; Kozanecki, W.; Lançon, E.; Lemaire, M. C.; Locci, E.; Perez, P.; Rander, J.; Renardy, J.-F.; Rosowsky, A.; Roussarie, A.; Schuller, J.-P.; Schwindling, J.; Trabelsi, A.; Vallage, B.; Black, S. N.; Dann, J. H.; Kim, H. Y.; Litke, A. M.; McNeil, M. A.; Taylor, G.; Booth, C. N.; Boswell, R.; Brew, C. A. J.; Cartwright, S.; Combley, F.; Kelly, M. S.; Lehto, M.; Newton, W. M.; Reeve, J.; Thompson, L. F.; Affholderbach, K.; Böhrer, A.; Brandt, S.; Cowan, G.; Foss, J.; Grupen, C.; Lutters, G.; Saraiva, P.; Smolik, L.; Stephan, F.; Apollonio, M.; Bosisio, L.; della Marina, R.; Giannini, G.; Gobbo, B.; Musolino, G.; Putz, J.; Rothberg, J.; Wasserbaech, S.; Williams, R. W.; Armstrong, S. R.; Charles, E.; Elmer, P.; Ferguson, D. P. S.; González, S.; Greening, T. C.; Hayes, O. J.; Hu, H.; Jin, S.; McNamara, P. A., III; Nachtman, J. M.; Nielsen, J.; Orejudos, W.; Pan, Y. B.; Saadi, Y.; Scott, I. J.; Walsh, J.; Wu, Sau Lan; Wu, X.; Yamartino, J. M.; Zobernig, G.

    1997-11-01

    Searches for scalar top and bottom quarks have been performed with data collected by the ALEPH detector at LEP. The data sample consists of 21.7 pb-1 taken at sqrt(s) = 161, 170, and 172 GeV and 5.7 pb-1 taken at sqrt(s) = 130 and 136 GeV. No evidence for scalar top quarks or scalar bottom quarks was found in the channels t~-->cχ, t~-->blν~, and b~-->bχ. For the channel t~-->cχ a limit of 67 GeV/c2has been set on the scalar top quark mass, independent of the mixing angle between the supersymmetric partners of the left and right-handed states of the top quark. This limit assumes a mass difference between the t~ and the χ of at least 10 GeV/c2. For the channel t~-->blν~ the mixing-angle independent scalar top limit is 70 GeV/c2, assuming a mass difference between the t~ and the ν~ of at least 10 GeV/c2. For the channel b~-->bχ, a limit of 73 GeV/c2has been set on the mass of the supersymmetric partner of the left-handed state of the bottom quark. This limit is valid if the mass difference between the b~ and the χ is at least 10 GeV/c2.

  1. Core-debris quenching-heat-transfer rates under top- and bottom-reflood conditions

    International Nuclear Information System (INIS)

    Ginsberg, T.; Tutu, N.; Klages, J.; Schwarz, C.E.; Sanborn, Y.

    1983-02-01

    This paper presents recent experimental data for the quench-heat-transfer characteristics of superheated packed beds of spheres which were cooled, in separate experiments, by top- and bottom-flooding modes. Experiments were carried out with beds of 3-mm steel spheres of 330-mm height. The initial bed temperature was 810 K. The observed heat-transfer rates are strongly dependent on the mode of water injection. The results suggest that top-flood bed quench heat transfer is limited by the rate at which water can penetrate the bed under two-phase countercurrent-flow conditions. With bottom-reflood the heat-transfer rate is an order-of-magnitude greater than under top-flood conditions and appears to be limited by particle-to-fluid film boiling heat transfer

  2. Microbial quality of bagged baby spinach and romaine lettuce: effects of top versus bottom sampling.

    Science.gov (United States)

    Kase, Julie A; Borenstein, Stacey; Blodgett, Robert J; Feng, Peter C H

    2012-01-01

    Contamination with Escherichia coli O157:H7 and Salmonella have called into question the safety and microbial quality of bagged ready-to-eat leafy greens. This study expands on previous findings that these goods have high total bacteria counts (TBC) and coliform counts, variation in counts among different lots, that Escherichia coli is present, and disparities in counts when bags are top or bottom sampled. Nearly 100 bags of baby spinach and hearts of romaine lettuce from a single brand were subjected to both top and bottom sampling. Product was blended, and a portion serially diluted and plated to obtain TBC. Total coliform and E. coli levels were estimated by the most-probable-number (MPN) technique with ColiComplete discs. Top-sampled TBC from bags of baby spinach (48 bags, 13 different lots) ranged from 3.9 to 8.1 log CFU/g and bottom-sampled TBC ranged from 4.0 to 8.2 log CFU/g, with 52% of the bags (or 39% of the lots) producing TBC higher in bottom samples. For hearts of romaine (47 bags from 19 different lots), top-sampled bags had TBC ranging from 2.4 to 7.0 log, and bottom-sampled bags had TBC from 3.3 to 7.3 log, with 64% of the bags (or 63% of the lots) showing higher TBC in bottom samples. However, we are unable to reject the hypothesis that the top and bottom samples from either commodity contain the same TBC (P ≥ 0.08). No E. coli was detected and total coliform bacteria counts were, with few exceptions, ≥210 MPN/g, irrespective of TBC. In general, lots with the most number of days before the printed "use-by" date had lower TBC. However, the R(2) values for either baby spinach (0.4085) or hearts of romaine (0.2946) suggest that age might not be a very good predictor of higher TBC. TBC varied widely between lots and even more so within same-lot samples, as indicated by the sum of squares results. This finding, along with higher TBC in bottom samples, suggests further consideration when a microbiological sampling scheme of bagged produce is

  3. Searches for supersymmetric partners of the bottom and top quarks with the ATLAS detector

    CERN Document Server

    Dafinca, Alexandru

    "Supersymmetry is a promising candidate theory that could solve the hierarchy problem and explain the dark matter density in the Universe. The ATLAS experiment at the Large Hadron Collider is sensitive to a variety of such supersymmetric models. This thesis reports on a search for pair production of the supersymmetric scalar partners of bottom and top quarks in 20.1 fb$^{-1}$ of $pp$ collisions at a centre-of-mass energy of 8 TeV using the ATLAS experiment. The study focuses on final states with large missing transverse momentum, no electrons or muons and two jets identified as originating from a $b$-quark. This final state can be produced in a $R$-parity conserving minimal supersymmetric scenario, assuming that the scalar bottom decays exclusively to a bottom quark and a neutralino and the scalar top decays to a bottom quark and a chargino, with a small mass difference with the neutralino. As no signal is observed above the Standard Model expectation, competitive exclusion limits are set on scalar bottom and...

  4. Mild performic acid oxidation enhances chromatographic and top down mass spectrometric analyses of histones.

    Science.gov (United States)

    Pesavento, James J; Garcia, Benjamin A; Streeky, James A; Kelleher, Neil L; Mizzen, Craig A

    2007-09-01

    Recent developments in top down mass spectrometry have enabled closely related histone variants and their modified forms to be identified and quantitated with unprecedented precision, facilitating efforts to better understand how histones contribute to the epigenetic regulation of gene transcription and other nuclear processes. It is therefore crucial that intact MS profiles accurately reflect the levels of variants and modified forms present in a given cell type or cell state for the full benefit of such efforts to be realized. Here we show that partial oxidation of Met and Cys residues in histone samples prepared by conventional methods, together with oxidation that can accrue during storage or during chip-based automated nanoflow electrospray ionization, confounds MS analysis by altering the intact MS profile as well as hindering posttranslational modification localization after MS/MS. We also describe an optimized performic acid oxidation procedure that circumvents these problems without catalyzing additional oxidations or altering the levels of posttranslational modifications common in histones. MS and MS/MS of HeLa cell core histones confirmed that Met and Cys were the only residues oxidized and that complete oxidation restored true intact abundance ratios and significantly enhanced MS/MS data quality. This allowed for the unequivocal detection, at the intact molecule level, of novel combinatorially modified forms of H4 that would have been missed otherwise. Oxidation also enhanced the separation of human core histones by reverse phase chromatography and decreased the levels of salt-adducted forms observed in ESI-FTMS. This method represents a simple and easily automated means for enhancing the accuracy and sensitivity of top down analyses of combinatorially modified forms of histones that may also be of benefit for top down or bottom up analyses of other proteins.

  5. Development Policy in Thailand: From Top-down to Grass Roots.

    Science.gov (United States)

    Kelly, Matthew; Yutthaphonphinit, Phattaraphon; Seubsman, Sam-Ang; Sleigh, Adrian

    2012-11-01

    Top-down industrial development strategies initially dominated the developing world after the second World War but were eventually found to produce inequitable economic growth. For a decade or more, governments and international development agencies have embraced the idea of participatory grass roots development as a potential solution. Here we review Thailand's experience with development strategies and we examine the current focus on participatory approaches. Thai government planning agencies have adopted "people centred development" and a "sufficiency economy", particularly emphasised since the disruptions caused by the 1997 Asian financial crisis. They aim to address the inequitable sharing of the benefits of decades of rapid growth that was particularly unfair for the rural poor. Thai policies aim to decentralise power to the local level, allowing civil society and Non-Governmental Organisations (NGOs) more of a voice in national decision making and promoting sustainable farming practices aimed at enriching rural communities. An example of this change in Thai government policy is the Community Worker Accreditation Scheme which is aiming to develop human resources at the local level by training community based leaders and supporting networks of community organisations. This enables autonomous local development projects led by trained and accredited individuals and groups. The political tensions notable in Thailand at present are part of this modern transition driven by conflicting models of top-down (industrial) development and the bottom-up (participatory) development ideals described above. Once resolved, Thailand will have few obstacles to moving to a new economic level.

  6. A top-down perspective on dopamine, motivation and memory.

    Science.gov (United States)

    Phillips, Anthony G; Vacca, Giada; Ahn, Soyon

    2008-08-01

    Dopamine (DA) activity, in the form of increased neural firing or enhanced release of transmitter from nerve terminals and varicosities, is linked to a number of important psychological processes including: movement; hedonic reactions to positive reward; provision of an error detection signal during the acquisition of new learning; response to novel stimuli; provision of reinforcement signals essential for acquisition of new action patterns; and incentive motivation. This review focuses primarily on our research linking dynamic changes in DA efflux on the timescale of minutes, with incentive motivation, as revealed by brain dialysis experiments in behaving animals. Recent experiments on sensory-specific satiety and successive positive and negative contrast are discussed along with the distinction between preparatory behaviors that precede contact with biologically significant stimuli and subsequent consummatory behaviors. The relationship between DA efflux in the medial prefrontal cortex (mPFC) and foraging for food based on working memory is also discussed in support of the conjecture that DA may serve as a link between motivation and memory functions. Evidence in support of 'top-down' regulation of dopaminergic activity in the mesocorticolimbic DA pathways is reviewed briefly to introduce a mechanism by which activation of ascending DA projections in this manner might optimize dopaminergic modulation of executive function within regions such as the mPFC. Collectively, these processes could ensure coordination between cognitive processes that assess current opportunities and the motivational systems that select and engage patterns of approach behavior that bring organisms into contact with the essentials for survival.

  7. Stability of Polymer Ultrathin Films (Top-Down Approach.

    Science.gov (United States)

    Bal, Jayanta Kumar; Beuvier, Thomas; Unni, Aparna Beena; Chavez Panduro, Elvia Anabela; Vignaud, Guillaume; Delorme, Nicolas; Chebil, Mohamed Souheib; Grohens, Yves; Gibaud, Alain

    2015-08-25

    In polymer physics, the dewetting of spin-coated polystyrene ultrathin films on silicon remains mysterious. By adopting a simple top-down method based on good solvent rinsing, we are able to prepare flat polystyrene films with a controlled thickness ranging from 1.3 to 7.0 nm. Their stability was scrutinized after a classical annealing procedure above the glass transition temperature. Films were found to be stable on oxide-free silicon irrespective of film thickness, while they were unstable (2.9 nm) on 2 nm oxide-covered silicon substrates. The Lifshitz-van der Waals intermolecular theory that predicts the domains of stability as a function of the film thickness and of the substrate nature is now fully reconciled with our experimental observations. We surmise that this reconciliation is due to the good solvent rinsing procedure that removes the residual stress and/or the density variation of the polystyrene films inhibiting thermodynamically the dewetting on oxide-free silicon.

  8. Top-down workforce demand extrapolation based on an EC energy road-map scenario

    International Nuclear Information System (INIS)

    Roelofs, F.; Von Estorff, U.

    2014-01-01

    The EHRO-N team of JRC-IET provides the EC with essential data related to supply and demand for nuclear experts based on bottom-up information from the nuclear industry. The current paper deals with an alternative approach to derive figures for the demand side information of the nuclear workforce. Complementary to the bottom-up approach, a top-down modelling approach extrapolation of an EC Energy road-map nuclear energy demand scenario is followed here in addition to the survey information. In this top-down modelling approach, the number of nuclear power plants that are in operation and under construction is derived as a function of time from 2010 up to 2050 assuming that the current reactor park will be replaced by generic third generation reactors of 1400 MWe or 1000 MWe. Depending on the size of new build reactors, the analysis shows the number of new reactors required to fulfil the demand for nuclear energy. Based on workforce models for operation and construction of nuclear power plants, the model allows an extrapolation of these respective work-forces. Using the nuclear skills pyramid, the total workforce employed at a plant is broken down in a nuclear (experts), nuclearized, and nuclear aware workforce. With retirement profiles for nuclear power plants derived from the bottom-up EHRO-N survey, the replacement of the current workforce is taken into account. The peak of the new workforce (partly replacing the retiring workforce and additionally keeping up with the growing total workforce demand) for nuclear experts and nuclearized employees is to be expected at the end of the considered period (2050). However, the peak workforce for nuclear aware employees is to be expected around 2020. When comparing to historical data for the nuclear capacity being installed at the same time in Europe, it is clear that the expected future capacity to be installed at the same time in Europe is significantly lower (factor of 2) than in the early 1980's. However, it should

  9. The Earnings Ladder. Who's at the Bottom? Who's at the Top? Statistical Brief.

    Science.gov (United States)

    Bureau of the Census (DOC), Washington, DC. Economics and Statistics Administration.

    Data collected by the March Current Population Survey were used to identify which groups of year-round, full-time civilian workers aged 16 and older were most likely to be at the top and bottom of the earnings ladder. Women, young workers, less-educated individuals, and Hispanics were most likely to earn less than $13,091 (1992 constant dollars),…

  10. Top-Down Budgeting—An Instrument to Strengthen Budget Management

    OpenAIRE

    Gösta Ljungman

    2009-01-01

    This paper examines the rationale for a top-down approach to budget preparation and approval, and discusses some factors that have to be considered when reorienting the budget process along these lines. The paper argues that the sequence in which budgetary decisions are taken matters, and that a strong top-down approach strengthens fiscal discipline and improves policy prioritization and coordination. Top-down budgeting also alters the division of roles and responsibilities between the centra...

  11. Effect of adhesive properties of buffy coat on the quality of blood components produced with Top & Top and Top & Bottom bags.

    Science.gov (United States)

    Cerelli, Eugenio; Nocera, Martina; Di Bartolomeo, Erminia; Panzani, Paola; Baricchi, Roberto

    2015-04-01

    The Transfusion Medicine Unit of Reggio Emilia currently collects whole blood using conventional quadruple Fresenius Top & Top bags. In this study, new Fresenius Top & Bottom bags were assessed and compared to the routine method with regards to product quality and operational requirements. Twenty-one whole blood units were collected with both the new and the traditional bags, and then separated. Quality control data were evaluated and compared in order to estimate yield and quality of final blood components obtained with the two systems. We collected other bags, not included in the ordinary quality control programme, for comparison of platelet concentrates produced by pools of buffy coat. Compared to the traditional system, the whole blood units processed with Top & Bottom bags yielded larger plasma volumes (+5.7%) and a similar amount of concentrated red blood cells, but with a much lower contamination of lymphocytes (-61.5%) and platelets (-86.6%). Consequently, the pooled platelets contained less plasma (-26.3%) and were significantly richer in platelets (+17.9%). This study investigated the effect of centrifugation on the adhesiveness of the buffy coat to the bag used for whole blood collection. We analysed the mechanism by which this undesirable phenomenon affects the quality of packed red blood cells in two types of bags. We also documented the incomparability of measurements on platelet concentrates performed with different principles of cell counting: this vexing problem has important implications for biomedical research and for the establishment of universal product standards. Our results support the conclusion that the Top & Bottom bags produce components of higher quality than our usual system, while having equal operational efficiency. Use of the new bags could result in an important quality improvement in blood components manufacturing.

  12. Separation of top and bottom surface conduction in Bi2Te3 thin films

    International Nuclear Information System (INIS)

    Yu Xinxin; He Liang; Lang Murong; Jiang Wanjun; Kou Xufeng; Tang Jianshi; Huang Guan; Wang, Kang L; Xiu Faxian; Liao Zhiming; Zou Jin; Wang Yong; Zhang Peng

    2013-01-01

    Quantum spin Hall (QSH) systems are insulating in the bulk with gapless edges or surfaces that are topologically protected and immune to nonmagnetic impurities or geometric perturbations. Although the QSH effect has been realized in the HgTe/CdTe system, it has not been accomplished in normal 3D topological insulators. In this work, we demonstrate a separation of two surface conductions (top/bottom) in epitaxially grown Bi 2 Te 3 thin films through gate dependent Shubnikov–de Haas (SdH) oscillations. By sweeping the gate voltage, only the Fermi level of the top surface is tuned while that of the bottom surface remains unchanged due to strong electric field screening effects arising from the high dielectric constant of Bi 2 Te 3 . In addition, the bulk conduction can be modulated from n- to p-type with a varying gate bias. Our results on the surface control hence pave a way for the realization of QSH effect in topological insulators which requires a selective control of spin transports on the top/bottom surfaces. (paper)

  13. Conflict-Triggered Top-Down Control: Default Mode, Last Resort, or No Such Thing?

    Science.gov (United States)

    Bugg, Julie M.

    2014-01-01

    The conflict monitoring account posits that globally high levels of conflict trigger engagement of top-down control; however, recent findings point to the mercurial nature of top-down control in high conflict contexts. The current study examined the potential moderating effect of associative learning on conflict-triggered top-down control engagement by testing the Associations as Antagonists to Top-Down Control (AATC) hypothesis. In 4 experiments, list-wide proportion congruence was manipulated, and conflict-triggered top-down control engagement was examined by comparing interference for 50% congruent items across mostly congruent (low conflict) and mostly incongruent (high conflict) lists. Despite the fact that global levels of conflict were varied identically across experiments, evidence of conflict-triggered top-down control engagement was selective to those experiments in which responses could not be predicted on the majority of trials via simple associative learning, consistent with the AATC hypothesis. In a fifth experiment, older adults showed no evidence of top-down control engagement under conditions in which young adults did, a finding that refined the interpretation of the patterns observed in the prior experiments. Collectively, these findings suggest that top-down control engagement in high conflict contexts is neither the default mode nor an unused (or non-existent) strategy. Top-down control is best characterized as a last resort that is engaged when reliance on one’s environment, and in particular associative responding, is unproductive for achieving task goals. PMID:24274385

  14. Characterizing the effects of feature salience and top-down attention in the early visual system.

    Science.gov (United States)

    Poltoratski, Sonia; Ling, Sam; McCormack, Devin; Tong, Frank

    2017-07-01

    The visual system employs a sophisticated balance of attentional mechanisms: salient stimuli are prioritized for visual processing, yet observers can also ignore such stimuli when their goals require directing attention elsewhere. A powerful determinant of visual salience is local feature contrast: if a local region differs from its immediate surround along one or more feature dimensions, it will appear more salient. We used high-resolution functional MRI (fMRI) at 7T to characterize the modulatory effects of bottom-up salience and top-down voluntary attention within multiple sites along the early visual pathway, including visual areas V1-V4 and the lateral geniculate nucleus (LGN). Observers viewed arrays of spatially distributed gratings, where one of the gratings immediately to the left or right of fixation differed from all other items in orientation or motion direction, making it salient. To investigate the effects of directed attention, observers were cued to attend to the grating to the left or right of fixation, which was either salient or nonsalient. Results revealed reliable additive effects of top-down attention and stimulus-driven salience throughout visual areas V1-hV4. In comparison, the LGN exhibited significant attentional enhancement but was not reliably modulated by orientation- or motion-defined salience. Our findings indicate that top-down effects of spatial attention can influence visual processing at the earliest possible site along the visual pathway, including the LGN, whereas the processing of orientation- and motion-driven salience primarily involves feature-selective interactions that take place in early cortical visual areas. NEW & NOTEWORTHY While spatial attention allows for specific, goal-driven enhancement of stimuli, salient items outside of the current focus of attention must also be prioritized. We used 7T fMRI to compare salience and spatial attentional enhancement along the early visual hierarchy. We report additive effects of

  15. The Relationship between Response Time and the Strength of Top-Down Attentional Control: An ERP Study

    Directory of Open Access Journals (Sweden)

    Judith Schomaker

    2009-12-01

    Full Text Available A recent ERP study using a spatial cueing paradigm found that the physiological indices accompanying the orienting, shifting and allocation processes of attention, and the performance on the task in terms of speed and accuracy of responding on the other hand covaried (Talsma, Mulckhuyse, Slagter, & Theeuwes, 2007.  However, the stimuli used in the former study possibly allowed for bottom-up capture of attention. Therefore the results could not unequivocally be attributed to a top-down attentional process. The present study is a follow-up of the Talsma et al. (2007  study and the stimuli design used in this study controlled for possible bottom-up effects. As a result, participants needed to spatially allocate attention in a top-down way. Indeed, in this study an Event-related Potential (ERP component associated with the top-down allocation of attention was found; the N2-posterior-contralateral (N2pc.  N2pc amplitudes were bigger in the fastest versus the slowest trials for the validly and non-informatively cued targets at posterior scalp sites. The present study replicated the Talsma et al. (2007 findings that the target-evoked N1 components were larger for the faster trials in the validly and non-informatively cued trials.

  16. Salivary Cystatins: Exploring New Post-Translational Modifications and Polymorphisms by Top-Down High-Resolution Mass Spectrometry.

    Science.gov (United States)

    Manconi, Barbara; Liori, Barbara; Cabras, Tiziana; Vincenzoni, Federica; Iavarone, Federica; Castagnola, Massimo; Messana, Irene; Olianas, Alessandra

    2017-11-03

    Cystatins are a complex family of cysteine peptidase inhibitors. In the present study, various proteoforms of cystatin A, cystatin B, cystatin S, cystatin SN, and cystatin SA were detected in the acid-soluble fraction of human saliva and characterized by a top-down HPLC-ESI-MS approach. Proteoforms of cystatin D were also detected and characterized by an integrated top-down and bottom-up strategy. The proteoforms derive from coding sequence polymorphisms and post-translational modifications, in particular, phosphorylation, N-terminal processing, and oxidation. This study increases the current knowledge of salivary cystatin proteoforms and provides the basis to evaluate possible qualitative/quantitative variations of these proteoforms in different pathological states and reveal new potential salivary biomarkers of disease. Data are available via ProteomeXchange with identifier PXD007170.

  17. Transferring Codified Knowledge: Socio-Technical versus Top-Down Approaches

    Science.gov (United States)

    Guzman, Gustavo; Trivelato, Luiz F.

    2008-01-01

    Purpose: This paper aims to analyse and evaluate the transfer process of codified knowledge (CK) performed under two different approaches: the "socio-technical" and the "top-down". It is argued that the socio-technical approach supports the transfer of CK better than the top-down approach. Design/methodology/approach: Case study methodology was…

  18. Establishing a campylobacter-free pig population through a top-down approach

    NARCIS (Netherlands)

    Weijtens, M.J.B.M.; Urlings, H.A.P.; Plas, J. van der

    2000-01-01

    Fattening pigs are often infected with campylobacter. To eliminate campylobacter from the pig population, a top-down approach, involving the breeding and reproduction farms, seems appropriate. In order to investigate the effectiveness of a top-down approach, sows' faeces from the following farms

  19. Changing physician perspectives on complementary and alternative medicine: the need for a top-down approach

    Directory of Open Access Journals (Sweden)

    MacKinnon TS

    2017-09-01

    Full Text Available Thomas S MacKinnon,1 Norbert F Banhidy,1 Daniel R Tuite21School of Medicine, Imperial College London, London, 2Faculty of Medicine, Brighton and Sussex Medical School, Brighton, UKWe read with great interest the article by Patel et al1 discussing the changing perspectives towards complementary and alternative medicine (CAM, and an impetus for additional physician knowledge of the strengths and drawbacks of CAM. These findings are indeed relevant in the UK, with an estimated 41.1% one-year prevalence of CAM use, responsible for an annual out-of-pocket expenditure of £1.6 billion.2 We agree that improved training and education in medical school and residencies – which can be thought of as a “bottom-up” approach – are fundamental in preparing the health care system for improved integration of CAM. However, we also suggest that “top-down” changes are required to optimize patient care.Authors' reply Sejal J Patel,1 Kathi J Kemper,2 Joseph P Kitzmiller31College of Public Health, The Ohio State University, 2Center for Integrative Health and Wellness, The Ohio State Wexner University Medical Center, 3Department of Biological Chemistry and Pharmacology, College of Medicine, The Ohio State University, Columbus, OH, USAWe agree the letter is worthy of publication but have a little to add: a top-down approach (as suggested and described by the authors of the letter certainly complements the bottom-up approach (described in our article.1View the original paper by Patel et al.

  20. Search for gluino-mediated bottom- and top-squark production in pp collisions at 8 TeV

    CERN Document Server

    CMS Collaboration

    2013-01-01

    The results are interpreted in the context of simplified models of new physics processes in which gluino pair production is followed by the decay of each gluino to an undetected particle and either two bottom quarks or two top qua...

  1. Top-down modulation of visual processing and knowledge after 250 ms supports object constancy of category decisions.

    Science.gov (United States)

    Schendan, Haline E; Ganis, Giorgio

    2015-01-01

    People categorize objects more slowly when visual input is highly impoverished instead of optimal. While bottom-up models may explain a decision with optimal input, perceptual hypothesis testing (PHT) theories implicate top-down processes with impoverished input. Brain mechanisms and the time course of PHT are largely unknown. This event-related potential study used a neuroimaging paradigm that implicated prefrontal cortex in top-down modulation of occipitotemporal cortex. Subjects categorized more impoverished and less impoverished real and pseudo objects. PHT theories predict larger impoverishment effects for real than pseudo objects because top-down processes modulate knowledge only for real objects, but different PHT variants predict different timing. Consistent with parietal-prefrontal PHT variants, around 250 ms, the earliest impoverished real object interaction started on an N3 complex, which reflects interactive cortical activity for object cognition. N3 impoverishment effects localized to both prefrontal and occipitotemporal cortex for real objects only. The N3 also showed knowledge effects by 230 ms that localized to occipitotemporal cortex. Later effects reflected (a) word meaning in temporal cortex during the N400, (b) internal evaluation of prior decision and memory processes and secondary higher-order memory involving anterotemporal parts of a default mode network during posterior positivity (P600), and (c) response related activity in posterior cingulate during an anterior slow wave (SW) after 700 ms. Finally, response activity in supplementary motor area during a posterior SW after 900 ms showed impoverishment effects that correlated with RTs. Convergent evidence from studies of vision, memory, and mental imagery which reflects purely top-down inputs, indicates that the N3 reflects the critical top-down processes of PHT. A hybrid multiple-state interactive, PHT and decision theory best explains the visual constancy of object cognition.

  2. Top-down modulation of visual processing and knowledge after 250 ms supports object constancy of category decisions

    Directory of Open Access Journals (Sweden)

    Haline E. Schendan

    2015-09-01

    Full Text Available People categorize objects slowly when visual input is highly impoverished instead of optimal. While bottom-up models may explain a decision with optimal input, perceptual hypothesis testing (PHT theories implicate top-down processes with impoverished input. Brain mechanisms and the time course of PHT are largely unknown. This event-related potential study used a neuroimaging paradigm that implicated prefrontal cortex in top-down modulation of occipitotemporal cortex. Subjects categorized more impoverished and less impoverished real and pseudo objects. PHT theories predict larger impoverishment effects for real than pseudo objects because top-down processes modulate knowledge only for real objects, but different PHT variants predict different timing. Consistent with parietal-prefrontal PHT variants, around 250 ms, the earliest impoverished real object interaction started on an N3 complex, which reflects interactive cortical activity for object cognition. N3 impoverishment effects localized to both prefrontal and occipitotemporal cortex for real objects only. The N3 also showed knowledge effects by 230 ms that localized to occipitotemporal cortex. Later effects reflected (a word meaning in temporal cortex during the N400, (b internal evaluation of prior decision and memory processes and secondary higher-order memory involving anterotemporal parts of a default mode network during posterior positivity (P600, and (c response related activity in posterior cingulate during an anterior slow wave (SW after 700 ms. Finally, response activity in supplementary motor area during a posterior SW after 900 ms showed impoverishment effects that correlated with RTs. Convergent evidence from studies of vision, memory, and mental imagery which reflects purely top-down inputs, indicates that the N3 reflects the critical top-down processes of PHT. A hybrid multiple-state interactive, PHT and decision theory best explains the visual constancy of object cognition.

  3. A neural mechanism of dynamic gating of task-relevant information by top-down influence in primary visual cortex.

    Science.gov (United States)

    Kamiyama, Akikazu; Fujita, Kazuhisa; Kashimori, Yoshiki

    2016-12-01

    Visual recognition involves bidirectional information flow, which consists of bottom-up information coding from retina and top-down information coding from higher visual areas. Recent studies have demonstrated the involvement of early visual areas such as primary visual area (V1) in recognition and memory formation. V1 neurons are not passive transformers of sensory inputs but work as adaptive processor, changing their function according to behavioral context. Top-down signals affect tuning property of V1 neurons and contribute to the gating of sensory information relevant to behavior. However, little is known about the neuronal mechanism underlying the gating of task-relevant information in V1. To address this issue, we focus on task-dependent tuning modulations of V1 neurons in two tasks of perceptual learning. We develop a model of the V1, which receives feedforward input from lateral geniculate nucleus and top-down input from a higher visual area. We show here that the change in a balance between excitation and inhibition in V1 connectivity is necessary for gating task-relevant information in V1. The balance change well accounts for the modulations of tuning characteristic and temporal properties of V1 neuronal responses. We also show that the balance change of V1 connectivity is shaped by top-down signals with temporal correlations reflecting the perceptual strategies of the two tasks. We propose a learning mechanism by which synaptic balance is modulated. To conclude, top-down signal changes the synaptic balance between excitation and inhibition in V1 connectivity, enabling early visual area such as V1 to gate context-dependent information under multiple task performances. Copyright © 2016 Elsevier Ireland Ltd. All rights reserved.

  4. Top-down Estimates of Greenhouse Gas Intensities and Emissions for Individual Oil Sands Facilities in Alberta Canada

    Science.gov (United States)

    Liggio, J.; Li, S. M.; Staebler, R. M.; Hayden, K. L.; Mittermeier, R. L.; McLaren, R.; Baray, S.; Darlington, A.; Worthy, D.; O'Brien, J.

    2017-12-01

    The oil sands (OS) region of Alberta contributes approximately 10% to Canada's overall anthropogenic greenhouse gas (GHG) emissions. Such emissions have traditionally been estimated through "bottom-up" methods which seek to account for all individual sources of GHGs within a given facility. However, it is recognized that bottom-up approaches for complex industrial facilities can be subject to uncertainties associated with incomplete or inaccurate emission factor and/or activity data. In order to quantify air pollutant emissions from oil sands activities an aircraft-based measurement campaign was performed in the summer of 2013. The aircraft measurements could also be used to quantify GHG emissions for comparison to the bottom up emissions estimates. Utilizing specific flight patterns, together with an emissions estimation algorithm and measurements of CO2 and methane, a "top-down" estimate of GHG intensities for several large surface mining operations was obtained. The results demonstrate that there is a wide variation in emissions intensities (≈80 - 220 kg CO2/barrel oil) across OS facilities, which in some cases agree with calculated intensities, and in other cases are larger than that estimated using industry reported GHG emission and oil production data. When translated to annual GHG emissions, the "top-down" approach results in a CO2 emission of approximately 41 Mega Tonnes (MT) CO2/year for the 4 OS facilities investigated, in contrast to the ≈26 MT CO2/year reported by industry. The results presented here highlight the importance of using "top-down" approaches as a complimentary method in evaluating GHG emissions from large industrial sources.

  5. The 26th International Physics Olympiad: On top down under!

    Science.gov (United States)

    1996-01-01

    As they opened the plane door on arrival at Canberra it was like stepping inside a freezer. I had escaped from the heatwave in Britain to experience winter in Australia. I have not found anyone who believes that there was really frost! The Australian welcome did its best to combat the cold, however, and Professor Rod Jury had soon introduced our guides and got us settled in on the campus of Canberra University. The British team of five students, selected through the British Physics Olympiad, were: Alan Bain of Birkenhead School, Chris Blake of King Edward VI School, Southampton, Richard Davies of Dulwich College, Tom Down of Embley Park School, Romsey and Chris Webb of Royal Grammar School, Worcester. The two Leaders of the party were Cyril Isenberg of the University of Kent and Guy Bagnall of Harrow School. Chris Robson of St Bee's School and myself from Stoke on Trent Sixth form College were interested Observers and Guy's wife, Jenny, completed the party. For the old hands there were many friendships stretching back years to renew, and with 51 countries this year many new ones to be made. Â Photo Figure 1. Photograph taken by C Robson of the British Physics Team immediately after the Awards Ceremony in Canberra in July 1995. From left to right: Chris Webb, Richard Davies, Tom Down, Alan Bain and Chris Blake. In addition to the confusion caused by the Sun being in the North and the Moon appearing to lie on its back, we had to get used to the flocks of chattering parrots browsing on the lawns and the kangaroos on campus! Everyone was presented with a boomerang and there were several sessions introducing the art of throwing them, even in the dark! The Opening Ceremony was colourful and a good mix of ceremony and fun with the Aboriginal entertainment and the Flame of Science to be lit. This was followed by my first examiners' meeting. Once the questions have been introduced no one is allowed to leave the group until ten hours later when the students are in bed! The

  6. Top, Bottom, and Versatile Anal Sex Roles in Same-Sex Male Relationships: Implications for Relationship and Sexual Satisfaction.

    Science.gov (United States)

    Moskowitz, David A; Garcia, Christopher P

    2018-06-01

    Across much of the gay and bisexual male research on sexual position self-label (i.e., calling oneself a top, bottom, or versatile), there exist two commonalities: (1) studies tend to focus almost entirely on individual, relationally single androphilic men; (2) studies rarely account for relationships and relationship dynamics. In response, we explored the role of self-label over sexual and relationship satisfaction among gay and bisexual partnered men. Specifically, we looked at whether adopted sexual position identities were consonant or dissonant (i.e., matching or mismatching) with enacted behavior in relationships and how that impacted men's attitudes toward different relational attributes. Through an online survey, we sampled 169 men in same-sex relationships, asking them questions about their ideal penetrative role identities and their reality penetrative roles with their partner. We then asked them to rate their relationship on 10 sexual and interpersonal attributes. Multiple regression modeling suggested ideal-reality penetrative role dissonance was predictive of sexual dissatisfaction among tops who bottomed in their relationships and, to a lesser extent, bottoms who topped. In contrast, penetrative role dissonance was predictive of relationship satisfaction among tops who bottomed in their relationship, but not bottoms who topped. We conclude that a potential reason for this paradox among tops who bottom may be sexual altruism. That is, men may be satisfied with other aspects within their relationships, understand their partner's anal sex preferences, and accommodate that position in response to their initial relationship satisfaction.

  7. Top-down estimates of benzene and toluene emissions in the Pearl River Delta and Hong Kong, China

    OpenAIRE

    Fang, Xuekun; Shao, Min; Stohl, Andreas; Zhang, Qiang; Zheng, Junyu; Guo, Hai; Wang, Chen; Wang, Ming; Ou, Jiamin; Thompson, Rona L.; Prinn, Ronald G.

    2016-01-01

    Benzene (C6H6) and toluene (C7H8) are toxic to humans and the environment. They are also important precursors of ground-level ozone and secondary organic aerosols and contribute substantially to severe air pollution in urban areas in China. Discrepancies exist between different bottom-up inventories for benzene and toluene emissions in the Pearl River Delta (PRD) and Hong Kong (HK), which are emission hot spots in China. This study provides top-down estimates of benzene and ...

  8. Top-down estimates of benzene and toluene emissions in Pearl River Delta and Hong Kong, China

    OpenAIRE

    X. Fang; M. Shao; A. Stohl; Q. Zhang; J. Zheng; H. Guo; C. Wang; M. Wang; J. Ou; R. L. Thompson; R. G. Prinn

    2015-01-01

    Benzene (C6H6) and toluene (C7H8) are toxic to humans and the environment. They are also important precursors of ground-level ozone and secondary organic aerosols and contribute substantially to severe air pollution in urban areas in China. Discrepancies exist between different bottom-up inventories for benzene and toluene emissions in Pearl River Delta (PRD) and Hong Kong (HK), which are emission hot spots in China. This study provides top-down estimates of benzene and tolu...

  9. Top-down Approach for the Direct Synthesis, Patterning, and Operation of Artificial Micromuscles on Flexible Substrates.

    Science.gov (United States)

    Maziz, Ali; Plesse, Cédric; Soyer, Caroline; Cattan, Eric; Vidal, Frédéric

    2016-01-27

    Recent progress in the field of microsystems on flexible substrates raises the need for alternatives to the stiffness of classical actuation technologies. This paper reports a top-down process to microfabricate soft conducting polymer actuators on substrates on which they ultimately operate. The bending microactuators were fabricated by sequentially stacking layers using a layer polymerization by layer polymerization of conducting polymer electrodes and a solid polymer electrolyte. Standalone microbeams thinner than 10 μm were fabricated on SU-8 substrates associated with a bottom gold electrical contact. The operation of microactuators was demonstrated in air and at low voltage (±4 V).

  10. Performances of photodiode detectors for top and bottom counting detectors of ISS-CREAM experiment

    Energy Technology Data Exchange (ETDEWEB)

    Hyun, H.J. [Kyungpook National University, Daegu 702-701 (Korea, Republic of); Anderson, T. [Pennsylvania State University, University Park, PA 16802 (United States); Angelaszek, D. [University of Maryland, College Park, MD 20740 (United States); Baek, S.J. [Sungkyunkwan University, Suwon 440-746 (Korea, Republic of); Copley, M. [University of Maryland, College Park, MD 20740 (United States); Coutu, S. [Pennsylvania State University, University Park, PA 16802 (United States); Han, J.H.; Huh, H.G. [University of Maryland, College Park, MD 20740 (United States); Hwang, Y.S. [Kyungpook National University, Daegu 702-701 (Korea, Republic of); Im, S. [Pennsylvania State University, University Park, PA 16802 (United States); Jeon, H.B.; Kah, D.H.; Kang, K.H.; Kim, H.J. [Kyungpook National University, Daegu 702-701 (Korea, Republic of); Kim, K.C.; Kwashnak, K. [University of Maryland, College Park, MD 20740 (United States); Lee, J. [Sungkyunkwan University, Suwon 440-746 (Korea, Republic of); Lee, M.H. [University of Maryland, College Park, MD 20740 (United States); Link, J.T. [NASA GSFC, Greenbelt, MD 20771 (United States); CRESST(USRA), Columbia, MD 21044 (United States); Lutz, L. [University of Maryland, College Park, MD 20740 (United States); and others

    2015-07-01

    The Cosmic Ray Energetics and Mass (CREAM) experiment at the International Space Station (ISS) aims to elucidate the source and acceleration mechanisms of high-energy cosmic rays by measuring the energy spectra from protons to iron. The instrument is planned for launch in 2015 at the ISS, and it comprises a silicon charge detector, a carbon target, top and bottom counting detectors, a calorimeter, and a boronated scintillator detector. The top and bottom counting detectors are developed for separating the electrons from the protons, and each of them comprises a plastic scintillator and a 20×20 silicon photodiode array. Each photodiode is 2.3 cm×2.3 cm in size and exhibits good electrical characteristics. The leakage current is measured to be less than 20 nA/cm{sup 2} at an operating voltage. The signal-to-noise ratio is measured to be better than 70 using commercial electronics, and the radiation hardness is tested using a proton beam. A signal from the photodiode is amplified by VLSI (very-large-scale integration) charge amp/hold circuits, the VA-TA viking chip. Environmental tests are performed using whole assembled photodiode detectors of a flight version. Herein, we present the characteristics of the developed photodiode along with the results of the environmental tests.

  11. Search for resonances decaying to top and bottom quarks with the CDF experiment

    Energy Technology Data Exchange (ETDEWEB)

    Aaltonen, Timo Antero [Univ. of Helsinki, Helsinki (Finland). et al.

    2015-08-03

    We report on a search for charged massive resonances decaying to top (t) and bottom (b) quarks in the full data set of proton-antiproton collisions at a center-of-mass energy of √s = 1.96 TeV collected by the CDF II detector at the Tevatron, corresponding to an integrated luminosity of 9.5 fb–1. No significant excess above the standard model background prediction is observed. We set 95% Bayesian credibility mass-dependent upper limits on the heavy charged-particle production cross section times branching ratio to tb. Using a standard model extension with a W' → tb and left-right-symmetric couplings as a benchmark model, we constrain the W' mass and couplings in the 300–900 GeV/c2 range. As a result, the limits presented here are the most stringent for a charged resonance with mass in the range 300–600 GeV/c2 decaying to top and bottom quarks.

  12. Search for Resonances Decaying to Top and Bottom Quarks with the CDF Experiment.

    Science.gov (United States)

    Aaltonen, T; Amerio, S; Amidei, D; Anastassov, A; Annovi, A; Antos, J; Anzà, F; Apollinari, G; Appel, J A; Arisawa, T; Artikov, A; Asaadi, J; Ashmanskas, W; Auerbach, B; Aurisano, A; Azfar, F; Badgett, W; Bae, T; Barbaro-Galtieri, A; Barnes, V E; Barnett, B A; Barria, P; Bartos, P; Bauce, M; Bedeschi, F; Behari, S; Bellettini, G; Bellinger, J; Benjamin, D; Beretvas, A; Bhatti, A; Bianchi, L; Bland, K R; Blumenfeld, B; Bocci, A; Bodek, A; Bortoletto, D; Boudreau, J; Boveia, A; Brigliadori, L; Bromberg, C; Brucken, E; Budagov, J; Budd, H S; Burkett, K; Busetto, G; Bussey, P; Butti, P; Buzatu, A; Calamba, A; Camarda, S; Campanelli, M; Canelli, F; Carls, B; Carlsmith, D; Carosi, R; Carrillo, S; Casal, B; Casarsa, M; Castro, A; Catastini, P; Cauz, D; Cavaliere, V; Cerri, A; Cerrito, L; Chen, Y C; Chertok, M; Chiarelli, G; Chlachidze, G; Cho, K; Chokheli, D; Clark, A; Clarke, C; Convery, M E; Conway, J; Corbo, M; Cordelli, M; Cox, C A; Cox, D J; Cremonesi, M; Cruz, D; Cuevas, J; Culbertson, R; d'Ascenzo, N; Datta, M; de Barbaro, P; Demortier, L; Deninno, M; D'Errico, M; Devoto, F; Di Canto, A; Di Ruzza, B; Dittmann, J R; Donati, S; D'Onofrio, M; Dorigo, M; Driutti, A; Ebina, K; Edgar, R; Elagin, A; Erbacher, R; Errede, S; Esham, B; Farrington, S; Fernández Ramos, J P; Field, R; Flanagan, G; Forrest, R; Franklin, M; Freeman, J C; Frisch, H; Funakoshi, Y; Galloni, C; Garfinkel, A F; Garosi, P; Gerberich, H; Gerchtein, E; Giagu, S; Giakoumopoulou, V; Gibson, K; Ginsburg, C M; Giokaris, N; Giromini, P; Glagolev, V; Glenzinski, D; Gold, M; Goldin, D; Golossanov, A; Gomez, G; Gomez-Ceballos, G; Goncharov, M; González López, O; Gorelov, I; Goshaw, A T; Goulianos, K; Gramellini, E; Grosso-Pilcher, C; Group, R C; Guimaraes da Costa, J; Hahn, S R; Han, J Y; Happacher, F; Hara, K; Hare, M; Harr, R F; Harrington-Taber, T; Hatakeyama, K; Hays, C; Heinrich, J; Herndon, M; Hocker, A; Hong, Z; Hopkins, W; Hou, S; Hughes, R E; Husemann, U; Hussein, M; Huston, J; Introzzi, G; Iori, M; Ivanov, A; James, E; Jang, D; Jayatilaka, B; Jeon, E J; Jindariani, S; Jones, M; Joo, K K; Jun, S Y; Junk, T R; Kambeitz, M; Kamon, T; Karchin, P E; Kasmi, A; Kato, Y; Ketchum, W; Keung, J; Kilminster, B; Kim, D H; Kim, H S; Kim, J E; Kim, M J; Kim, S H; Kim, S B; Kim, Y J; Kim, Y K; Kimura, N; Kirby, M; Knoepfel, K; Kondo, K; Kong, D J; Konigsberg, J; Kotwal, A V; Kreps, M; Kroll, J; Kruse, M; Kuhr, T; Kurata, M; Laasanen, A T; Lammel, S; Lancaster, M; Lannon, K; Latino, G; Lee, H S; Lee, J S; Leo, S; Leone, S; Lewis, J D; Limosani, A; Lipeles, E; Lister, A; Liu, H; Liu, Q; Liu, T; Lockwitz, S; Loginov, A; Lucchesi, D; Lucà, A; Lueck, J; Lujan, P; Lukens, P; Lungu, G; Lys, J; Lysak, R; Madrak, R; Maestro, P; Malik, S; Manca, G; Manousakis-Katsikakis, A; Marchese, L; Margaroli, F; Marino, P; Matera, K; Mattson, M E; Mazzacane, A; Mazzanti, P; McNulty, R; Mehta, A; Mehtala, P; Mesropian, C; Miao, T; Mietlicki, D; Mitra, A; Miyake, H; Moed, S; Moggi, N; Moon, C S; Moore, R; Morello, M J; Mukherjee, A; Muller, Th; Murat, P; Mussini, M; Nachtman, J; Nagai, Y; Naganoma, J; Nakano, I; Napier, A; Nett, J; Neu, C; Nigmanov, T; Nodulman, L; Noh, S Y; Norniella, O; Oakes, L; Oh, S H; Oh, Y D; Oksuzian, I; Okusawa, T; Orava, R; Ortolan, L; Pagliarone, C; Palencia, E; Palni, P; Papadimitriou, V; Parker, W; Pauletta, G; Paulini, M; Paus, C; Phillips, T J; Piacentino, G; Pianori, E; Pilot, J; Pitts, K; Plager, C; Pondrom, L; Poprocki, S; Potamianos, K; Pranko, A; Prokoshin, F; Ptohos, F; Punzi, G; Redondo Fernández, I; Renton, P; Rescigno, M; Rimondi, F; Ristori, L; Robson, A; Rodriguez, T; Rolli, S; Ronzani, M; Roser, R; Rosner, J L; Ruffini, F; Ruiz, A; Russ, J; Rusu, V; Sakumoto, W K; Sakurai, Y; Santi, L; Sato, K; Saveliev, V; Savoy-Navarro, A; Schlabach, P; Schmidt, E E; Schwarz, T; Scodellaro, L; Scuri, F; Seidel, S; Seiya, Y; Semenov, A; Sforza, F; Shalhout, S Z; Shears, T; Shepard, P F; Shimojima, M; Shochet, M; Shreyber-Tecker, I; Simonenko, A; Sliwa, K; Smith, J R; Snider, F D; Song, H; Sorin, V; St Denis, R; Stancari, M; Stentz, D; Strologas, J; Sudo, Y; Sukhanov, A; Suslov, I; Takemasa, K; Takeuchi, Y; Tang, J; Tecchio, M; Teng, P K; Thom, J; Thomson, E; Thukral, V; Toback, D; Tokar, S; Tollefson, K; Tomura, T; Tonelli, D; Torre, S; Torretta, D; Totaro, P; Trovato, M; Ukegawa, F; Uozumi, S; Vázquez, F; Velev, G; Vellidis, C; Vernieri, C; Vidal, M; Vilar, R; Vizán, J; Vogel, M; Volpi, G; Wagner, P; Wallny, R; Wang, S M; Waters, D; Wester, W C; Whiteson, D; Wicklund, A B; Wilbur, S; Williams, H H; Wilson, J S; Wilson, P; Winer, B L; Wittich, P; Wolbers, S; Wolfe, H; Wright, T; Wu, X; Wu, Z; Yamamoto, K; Yamato, D; Yang, T; Yang, U K; Yang, Y C; Yao, W-M; Yeh, G P; Yi, K; Yoh, J; Yorita, K; Yoshida, T; Yu, G B; Yu, I; Zanetti, A M; Zeng, Y; Zhou, C; Zucchelli, S

    2015-08-07

    We report on a search for charged massive resonances decaying to top (t) and bottom (b) quarks in the full data set of proton-antiproton collisions at a center-of-mass energy of √[s]=1.96  TeV collected by the CDF II detector at the Tevatron, corresponding to an integrated luminosity of 9.5  fb(-1). No significant excess above the standard model background prediction is observed. We set 95% Bayesian credibility mass-dependent upper limits on the heavy charged-particle production cross section times branching ratio to tb. Using a standard model extension with a W'→tb and left-right-symmetric couplings as a benchmark model, we constrain the W' mass and couplings in the 300-900  GeV/c(2) range. The limits presented here are the most stringent for a charged resonance with mass in the range 300-600  GeV/c(2) decaying to top and bottom quarks.

  13. Performances of photodiode detectors for top and bottom counting detectors of ISS-CREAM experiment

    International Nuclear Information System (INIS)

    Hyun, H.J.; Anderson, T.; Angelaszek, D.; Baek, S.J.; Copley, M.; Coutu, S.; Han, J.H.; Huh, H.G.; Hwang, Y.S.; Im, S.; Jeon, H.B.; Kah, D.H.; Kang, K.H.; Kim, H.J.; Kim, K.C.; Kwashnak, K.; Lee, J.; Lee, M.H.; Link, J.T.; Lutz, L.

    2015-01-01

    The Cosmic Ray Energetics and Mass (CREAM) experiment at the International Space Station (ISS) aims to elucidate the source and acceleration mechanisms of high-energy cosmic rays by measuring the energy spectra from protons to iron. The instrument is planned for launch in 2015 at the ISS, and it comprises a silicon charge detector, a carbon target, top and bottom counting detectors, a calorimeter, and a boronated scintillator detector. The top and bottom counting detectors are developed for separating the electrons from the protons, and each of them comprises a plastic scintillator and a 20×20 silicon photodiode array. Each photodiode is 2.3 cm×2.3 cm in size and exhibits good electrical characteristics. The leakage current is measured to be less than 20 nA/cm 2 at an operating voltage. The signal-to-noise ratio is measured to be better than 70 using commercial electronics, and the radiation hardness is tested using a proton beam. A signal from the photodiode is amplified by VLSI (very-large-scale integration) charge amp/hold circuits, the VA-TA viking chip. Environmental tests are performed using whole assembled photodiode detectors of a flight version. Herein, we present the characteristics of the developed photodiode along with the results of the environmental tests

  14. Some Unintended Consequences of "Top Down" Organization Development

    Science.gov (United States)

    White, Bernard J.; Ramsey, V. Jean

    1978-01-01

    An organizational development consultant is expected to perform a thorough and unbiased diagnosis of the organization's functioning. This is an account of a case study of the effect of top management influence on the consultant's awareness and definition of problems. (Author/MLF)

  15. Validity of the top-down approach of inverse dynamics analysis in fast and large rotational trunk movements.

    Science.gov (United States)

    Iino, Yoichi; Kojima, Takeji

    2012-08-01

    This study investigated the validity of the top-down approach of inverse dynamics analysis in fast and large rotational movements of the trunk about three orthogonal axes of the pelvis for nine male collegiate students. The maximum angles of the upper trunk relative to the pelvis were approximately 47°, 49°, 32°, and 55° for lateral bending, flexion, extension, and axial rotation, respectively, with maximum angular velocities of 209°/s, 201°/s, 145°/s, and 288°/s, respectively. The pelvic moments about the axes during the movements were determined using the top-down and bottom-up approaches of inverse dynamics and compared between the two approaches. Three body segment inertial parameter sets were estimated using anthropometric data sets (Ae et al., Biomechanism 11, 1992; De Leva, J Biomech, 1996; Dumas et al., J Biomech, 2007). The root-mean-square errors of the moments and the absolute errors of the peaks of the moments were generally smaller than 10 N·m. The results suggest that the pelvic moment in motions involving fast and large trunk movements can be determined with a certain level of validity using the top-down approach in which the trunk is modeled as two or three rigid-link segments.

  16. Task-related modulation of anterior theta and posterior alpha EEG reflects top-down preparation

    Directory of Open Access Journals (Sweden)

    Park Hae-Jeong

    2010-06-01

    Full Text Available Abstract Background Prestimulus EEG alpha activity in humans has been considered to reflect ongoing top-down preparation for the performance of subsequent tasks. Since theta oscillations may be related to poststimulus top-down processing, we investigated whether prestimulus EEG theta activity also reflects top-down cognitive preparation for a stimulus. Results We recorded EEG data from 15 healthy controls performing a color and shape discrimination task, and used the wavelet transformation to investigate the time course and power of oscillatory activity in the signals. We observed a relationship between both anterior theta and posterior alpha power in the prestimulus period and the type of subsequent task. Conclusions Since task-differences were reflected in both theta and alpha activities prior to stimulus onset, both prestimulus theta (particularly around the anterior region and prestimulus alpha (particularly around the posterior region activities may reflect prestimulus top-down preparation for the performance of subsequent tasks.

  17. Search for Scalar Top and Scalar Bottom Quarks at $\\sqrt{s}$ = 189 GeV at LEP

    CERN Document Server

    Abbiendi, G.; Alexander, G.; Allison, John; Altekamp, N.; Anderson, K.J.; Anderson, S.; Arcelli, S.; Asai, S.; Ashby, S.F.; Axen, D.; Azuelos, G.; Ball, A.H.; Barberio, E.; Barlow, Roger J.; Batley, J.R.; Baumann, S.; Bechtluft, J.; Behnke, T.; Bell, Kenneth Watson; Bella, G.; Bellerive, A.; Bentvelsen, S.; Bethke, S.; Betts, S.; Biebel, O.; Biguzzi, A.; Blobel, V.; Bloodworth, I.J.; Bock, P.; Bohme, J.; Bonacorsi, D.; Boutemeur, M.; Braibant, S.; Bright-Thomas, P.; Brigliadori, L.; Brown, Robert M.; Burckhart, H.J.; Capiluppi, P.; Carnegie, R.K.; Carter, A.A.; Carter, J.R.; Chang, C.Y.; Charlton, David G.; Chrisman, D.; Ciocca, C.; Clarke, P.E.L.; Clay, E.; Cohen, I.; Conboy, J.E.; Cooke, O.C.; Couyoumtzelis, C.; Coxe, R.L.; Cuffiani, M.; Dado, S.; Dallavalle, G.Marco; Davis, R.; De Jong, S.; de Roeck, A.; Dervan, P.; Desch, K.; Dienes, B.; Dixit, M.S.; Dubbert, J.; Duchovni, E.; Duckeck, G.; Duerdoth, I.P.; Estabrooks, P.G.; Etzion, E.; Fabbri, F.; Fanfani, A.; Fanti, M.; Faust, A.A.; Fiedler, F.; Fierro, M.; Fleck, I.; Folman, R.; Frey, A.; Furtjes, A.; Futyan, D.I.; Gagnon, P.; Gary, J.W.; Gascon, J.; Gascon-Shotkin, S.M.; Gaycken, G.; Geich-Gimbel, C.; Giacomelli, G.; Giacomelli, P.; Gibson, V.; Gibson, W.R.; Gingrich, D.M.; Glenzinski, D.; Goldberg, J.; Gorn, W.; Grandi, C.; Graham, K.; Gross, E.; Grunhaus, J.; Gruwe, M.; Hanson, G.G.; Hansroul, M.; Hapke, M.; Harder, K.; Harel, A.; Hargrove, C.K.; Hauschild, M.; Hawkes, C.M.; Hawkings, R.; Hemingway, R.J.; Herndon, M.; Herten, G.; Heuer, R.D.; Hildreth, M.D.; Hill, J.C.; Hobson, P.R.; Hoch, M.; Hocker, James Andrew; Hoffman, Kara Dion; Homer, R.J.; Honma, A.K.; Horvath, D.; Hossain, K.R.; Howard, R.; Huntemeyer, P.; Igo-Kemenes, P.; Imrie, D.C.; Ishii, K.; Jacob, F.R.; Jawahery, A.; Jeremie, H.; Jimack, M.; Jones, C.R.; Jovanovic, P.; Junk, T.R.; Kanzaki, J.; Karlen, D.; Kartvelishvili, V.; Kawagoe, K.; Kawamoto, T.; Kayal, P.I.; Keeler, R.K.; Kellogg, R.G.; Kennedy, B.W.; Kim, D.H.; Klier, A.; Kobayashi, T.; Kobel, M.; Kokott, T.P.; Kolrep, M.; Komamiya, S.; Kowalewski, Robert V.; Kress, T.; Krieger, P.; von Krogh, J.; Kuhl, T.; Kyberd, P.; Lafferty, G.D.; Landsman, H.; Lanske, D.; Lauber, J.; Lautenschlager, S.R.; Lawson, I.; Layter, J.G.; Lee, A.M.; Lellouch, D.; Letts, J.; Levinson, L.; Liebisch, R.; List, B.; Littlewood, C.; Lloyd, A.W.; Lloyd, S.L.; Loebinger, F.K.; Long, G.D.; Losty, M.J.; Lu, J.; Ludwig, J.; Lui, D.; Macchiolo, A.; Macpherson, A.; Mader, W.; Mannelli, M.; Marcellini, S.; Markopoulos, C.; Martin, A.J.; Martin, J.P.; Martinez, G.; Mashimo, T.; Mattig, Peter; McDonald, W.John; McKenna, J.; Mckigney, E.A.; McMahon, T.J.; McPherson, R.A.; Meijers, F.; Menke, S.; Merritt, F.S.; Mes, H.; Meyer, J.; Michelini, A.; Mihara, S.; Mikenberg, G.; Miller, D.J.; Mir, R.; Mohr, W.; Montanari, A.; Mori, T.; Nagai, K.; Nakamura, I.; Neal, H.A.; Nisius, R.; O'Neale, S.W.; Oakham, F.G.; Odorici, F.; Ogren, H.O.; Oreglia, M.J.; Orito, S.; Palinkas, J.; Pasztor, G.; Pater, J.R.; Patrick, G.N.; Patt, J.; Perez-Ochoa, R.; Petzold, S.; Pfeifenschneider, P.; Pilcher, J.E.; Pinfold, J.; Plane, David E.; Poffenberger, P.; Poli, B.; Polok, J.; Przybycien, M.; Rembser, C.; Rick, H.; Robertson, S.; Robins, S.A.; Rodning, N.; Roney, J.M.; Rosati, S.; Roscoe, K.; Rossi, A.M.; Rozen, Y.; Runge, K.; Runolfsson, O.; Rust, D.R.; Sachs, K.; Saeki, T.; Sahr, O.; Sang, W.M.; Sarkisian, E.K.G.; Sbarra, C.; Schaile, A.D.; Schaile, O.; Scharff-Hansen, P.; Schieck, J.; Schmitt, S.; Schoning, A.; Schroder, Matthias; Schumacher, M.; Schwick, C.; Scott, W.G.; Seuster, R.; Shears, T.G.; Shen, B.C.; Shepherd-Themistocleous, C.H.; Sherwood, P.; Siroli, G.P.; Sittler, A.; Skuja, A.; Smith, A.M.; Snow, G.A.; Sobie, R.; Soldner-Rembold, S.; Spagnolo, S.; Sproston, M.; Stahl, A.; Stephens, K.; Steuerer, J.; Stoll, K.; Strom, David M.; Strohmer, R.; Surrow, B.; Talbot, S.D.; Taras, P.; Tarem, S.; Teuscher, R.; Thiergen, M.; Thomas, J.; Thomson, M.A.; Torrence, E.; Towers, S.; Trigger, I.; Trocsanyi, Z.; Tsur, E.; Turcot, A.S.; Turner-Watson, M.F.; Ueda, I.; Van Kooten, Rick J.; Vannerem, P.; Verzocchi, M.; Voss, H.; Wackerle, F.; Wagner, A.; Ward, C.P.; Ward, D.R.; Watkins, P.M.; Watson, A.T.; Watson, N.K.; Wells, P.S.; Wermes, N.; White, J.S.; Wilson, G.W.; Wilson, J.A.; Wyatt, T.R.; Yamashita, S.; Yekutieli, G.; Zacek, V.; Zer-Zion, D.

    1999-01-01

    Searches for a scalar top quark and a scalar bottom quark have been performed using a data sample of 182 pb-1 at a centre-of-mass energy of 189 GeV collected with the OPAL detector at LEP. No evidence for a signal was found. The 95% confidence level lower limit on the scalar top quark mass is 90.3 GeV if the mixing angle between the supersymmetric partners of the left- and right-handed states of the top quark is zero. In the worst case, when the scalar top quark decouples from the Z boson, the lower limit is 87.2 GeV. These limits were obtained assuming that the scalar top quark decays into a charm quark and the lightest neutralino, and that the mass difference between the scalar top quark and the lightest neutralino is larger than 10 GeV. The complementary decay mode of the scalar top quark decaying into a bottom quark, a charged lepton and a scalar neutrino has also been studied. From a search for the scalar bottom quark, a mass limit of 88.6 GeV was obtained if the mass difference between the scalar bottom...

  18. A top-down manner-based DCNN architecture for semantic image segmentation.

    Directory of Open Access Journals (Sweden)

    Kai Qiao

    Full Text Available Given their powerful feature representation for recognition, deep convolutional neural networks (DCNNs have been driving rapid advances in high-level computer vision tasks. However, their performance in semantic image segmentation is still not satisfactory. Based on the analysis of visual mechanism, we conclude that DCNNs in a bottom-up manner are not enough, because semantic image segmentation task requires not only recognition but also visual attention capability. In the study, superpixels containing visual attention information are introduced in a top-down manner, and an extensible architecture is proposed to improve the segmentation results of current DCNN-based methods. We employ the current state-of-the-art fully convolutional network (FCN and FCN with conditional random field (DeepLab-CRF as baselines to validate our architecture. Experimental results of the PASCAL VOC segmentation task qualitatively show that coarse edges and error segmentation results are well improved. We also quantitatively obtain about 2%-3% intersection over union (IOU accuracy improvement on the PASCAL VOC 2011 and 2012 test sets.

  19. A Generalizable Top-Down Nanostructuring Method of Bulk Oxides: Sequential Oxygen-Nitrogen Exchange Reaction.

    Science.gov (United States)

    Lee, Lanlee; Kang, Byungwuk; Han, Suyoung; Kim, Hee-Eun; Lee, Moo Dong; Bang, Jin Ho

    2018-05-27

    A thermal reaction route that induces grain fracture instead of grain growth is devised and developed as a top-down approach to prepare nanostructured oxides from bulk solids. This novel synthesis approach, referred to as the sequential oxygen-nitrogen exchange (SONE) reaction, exploits the reversible anion exchange between oxygen and nitrogen in oxides that is driven by a simple two-step thermal treatment in ammonia and air. Internal stress developed by significant structural rearrangement via the formation of (oxy)nitride and the creation of oxygen vacancies and their subsequent combination into nanopores transforms bulk solid oxides into nanostructured oxides. The SONE reaction can be applicable to most transition metal oxides, and when utilized in a lithium-ion battery, the produced nanostructured materials are superior to their bulk counterparts and even comparable to those produced by conventional bottom-up approaches. Given its simplicity and scalability, this synthesis method could open a new avenue to the development of high-performance nanostructured electrode materials that can meet the industrial demand of cost-effectiveness for mass production. © 2018 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  20. Spongy Gels by a Top-Down Approach from Polymer Fibrous Sponges.

    Science.gov (United States)

    Jiang, Shaohua; Duan, Gaigai; Kuhn, Ute; Mörl, Michaela; Altstädt, Volker; Yarin, Alexander L; Greiner, Andreas

    2017-03-13

    Ultralight cellular sponges offer a unique set of properties. We show here that solvent uptake by these sponges results in new gel-like materials, which we term spongy gels. The appearance of the spongy gels is very similar to classic organogels. Usually, organogels are formed by a bottom-up process. In contrast, the spongy gels are formed by a top-down approach that offers numerous advantages for the design of their properties, reproducibility, and stability. The sponges themselves represent the scaffold of a gel that could be filled with a solvent, and thereby form a mechanically stable gel-like material. The spongy gels are independent of a time-consuming or otherwise demanding in situ scaffold formation. As solvent evaporation from gels is a concern for various applications, we also studied solvent evaporation of wetting and non-wetting liquids dispersed in the sponge. © 2017 The Authors. Published by Wiley-VCH Verlag GmbH & Co. KGaA.

  1. What does distractibility in ADHD reveal about mechanisms for top-down attentional control?

    OpenAIRE

    Friedman-Hill, Stacia R.; Wagman, Meryl R.; Gex, Saskia E.; Pine, Daniel S.; Leibenluft, Ellen; Ungerleider, Leslie G.

    2010-01-01

    In this study, we attempted to clarify whether distractibility in ADHD might arise from increased sensory-driven interference or from inefficient top-down control. We employed an attentional filtering paradigm in which discrimination difficulty and distractor salience (amount of image “graying”) were parametrically manipulated. Increased discrimination difficulty should add to the load of top-down processes, whereas increased distractor salience should produce stronger sensory interference. W...

  2. Numerical study of swirling flow in a cylinder with rotating top and bottom

    DEFF Research Database (Denmark)

    Shen, Wen Zhong; Sørensen, Jens Nørkær; Michelsen, Jess

    2006-01-01

    (xi=Omega(bottom)/Omega(top)). Earlier linear stability analysis (LSA) using the Galerkin spectral method by Gelfgat [Phys. Fluids, 8, 2614 (1996)] revealed that the curve of the critical Reynolds number behaves like an "S" around xi=0.54 in the co-rotation branch and around xi=-0.63 in the counter...... that the S shape does exist. The S shape of the stability diagram predicted by LSA is thus confirmed by a finite-volume based Navier-Stokes solver. The additional computations at aspect ratio lambda=2 show that the curve of critical Reynolds number has a wider S shape in the co-rotating branch for xi about 0.7...

  3. A top-crossover-to-bottom addressed segmented annular array using piezoelectric micromachined ultrasonic transducers

    Science.gov (United States)

    Jung, Joontaek; Lee, Wonjun; Kang, Woojin; Hong, Hyeryung; Yuen Song, Hi; Oh, Inn-yeal; Park, Chul Soon; Choi, Hongsoo

    2015-11-01

    We design and fabricate segmented annular arrays (SAAs) using piezoelectric micromachined ultrasonic transducers (pMUTs) to demonstrate the feasibility of acoustic focusing of ultrasound. The fabricated SAAs have 25 concentric top-electrode signal lines and eight bottom-electrodes for grounding to enable electronic steering of selectively grouped ultrasonic transducers from 2393 pMUT elements. Each element in the array is connected by top-crossover-to-bottom metal bridges, which reduce the parasitic capacitance. Circular-shaped pMUT elements, 120 μm in diameter, are fabricated using 1 μm-thick sol-gel lead zirconate titanate on a silicon wafer. To utilize the high-density pMUT array, a deep reactive ion etching process is used for anisotropic silicon etching to realize the transducer membranes. The resonant frequency and effective coupling coefficient of the elements, measured with an impedance analyzer, yields 1.517 MHz and 1.29%, respectively, in air. The SAAs using pMUTs are packaged on a printed circuit board and coated with parylene C for acoustic intensity measurements in water. The ultrasound generated by each segmented array is focused on a selected point in space. When a 5 Vpp, 1.5 MHz square wave is applied, the maximum spatial peak temporal average intensity ({{I}\\text{spta}} ) is found to be 79 mW cm-2 5 mm from the SAAs’ surface without beamforming. The beam widths (-3 dB) of ultrasonic radiation patterns in the elevation and azimuth directions are recorded as 3 and 3.4 mm, respectively. The results successfully show the feasibility of focusing ultrasound on a small area with SAAs using pMUTs.

  4. Reappraisal of dark matter co-annihilating with a top or bottom partner

    Science.gov (United States)

    Keung, Wai-Yee; Low, Ian; Zhang, Yue

    2017-07-01

    We revisit the calculation of the relic density of dark matter particles co-annihilating with a top or bottom partner by properly including the QCD bound-states (onia) effects of the colored partners as well as the relevant electroweak processes, which become important in the low-mass region. We carefully set up the complete framework that incorporates the relevant contributions and investigate their effects on the cosmologically preferred mass spectrum, which turn out to be comparable in size to those coming from the Sommerfeld enhancement. We apply the calculation to three scenarios: bino-stop and bino-sbottom co-annihilations in supersymmetry and a vector dark matter co-annihilating with a fermionic top partner. In addition, we confront our analysis of the relic abundance with recent direct detection experiments and collider searches at the LHC, which have important implications in the bino-stop and bino-sbottom scenarios. In particular, in the bino-stop case, recent LHC limits have excluded regions of parameter space with a direct detection rate that is above the neutrino floor.

  5. Auditory top-down control and affective theory of mind in schizophrenia with and without hallucinations.

    Science.gov (United States)

    Rominger, Christian; Bleier, Angelika; Fitz, Werner; Marksteiner, Josef; Fink, Andreas; Papousek, Ilona; Weiss, Elisabeth M

    2016-07-01

    Social cognitive impairments may represent a core feature of schizophrenia and above all are a strong predictor of positive psychotic symptoms. Previous studies could show that reduced inhibitory top-down control contributes to deficits in theory of mind abilities and is involved in the genesis of hallucinations. The current study aimed to investigate the relationship between auditory inhibition, affective theory of mind and the experience of hallucinations in patients with schizophrenia. In the present study, 20 in-patients with schizophrenia and 20 healthy controls completed a social cognition task (the Reading the Mind in the Eyes Test) and an inhibitory top-down Dichotic Listening Test. Schizophrenia patients with greater severity of hallucinations showed impaired affective theory of mind as well as impaired inhibitory top-down control. More dysfunctional top-down inhibition was associated with poorer affective theory of mind performance, and seemed to mediate the association between impairment to affective theory of mind and severity of hallucinations. The findings support the idea of impaired theory of mind as a trait marker of schizophrenia. In addition, dysfunctional top-down inhibition may give rise to hallucinations and may further impair affective theory of mind skills in schizophrenia. Copyright © 2016 Elsevier B.V. All rights reserved.

  6. Quantitative Analysis of Human Salivary Gland-Derived Intact Proteome Using Top-Down Mass Spectrometry

    Energy Technology Data Exchange (ETDEWEB)

    Wu, Si; Brown, Joseph N.; Tolic, Nikola; Meng, Da; Liu, Xiaowen; Zhang, Haizhen; Zhao, Rui; Moore, Ronald J.; Pevzner, Pavel A.; Smith, Richard D.; Pasa-Tolic, Ljiljana

    2014-05-31

    There are several notable challenges inherent to fully characterizing the entirety of the human saliva proteome using bottom-up approaches, including polymorphic isoforms, post-translational modifications, unique splice variants, deletions, and truncations. To address these challenges, we have developed a top-down based liquid chromatography-mass spectrometry (LC-MS) approach, which cataloged 20 major human salivary proteins with a total of 83 proteoforms, containing a broad range of post-translational modifications. Among these proteins, several previously reported disease biomarker proteins were identified at the intact protein level, such as beta-2 microglobulin (B2M). In addition, intact glycosylated proteoforms of several saliva proteins were also characterized, including intact N-glycosylated protein prolactin inducible protein (PIP) and O-glycosylated acidic protein rich protein (aPRP). These characterized proteoforms constitute an intact saliva proteoform database, which was used for quantitative comparison of intact salivary proteoforms among six healthy individuals. Human parotid (PS) and submandibular/sublingual gland (SMSL) secretion samples (2 μg of protein each) from six healthy individuals were compared using RPLC coupled with the 12T FTICR mass spectrometer. Significantly different protein and PTM patterns were resolved with high reproducibility between PS and SMSL glands. The results from this study provide further insight into the potential mechanisms of PTM pathways in oral glandular secretion, expanding our knowledge of this complex yet easily accessible fluid. Intact protein LC-MS approach presented herein can potentially be applied for rapid and accurate identification of biomarkers from only a few microliters of human glandular saliva.

  7. Status of the Top and Bottom Counting Detectors for the ISS-CREAM Experiment

    Science.gov (United States)

    Park, J. M.; ISS-CREAM Collaboration

    2017-11-01

    It is important to measure the cosmic ray spectra to study the origin, acceleration and propagation mechanisms of high-energy cosmic rays. A payload of the Cosmic Ray Energetics And Mass experiment is scheduled to be launched in 2017 to the International Space Station for measuring cosmic ray elemental spectra at energies beyond the reach of balloon instruments. Top Counting Detector and Bottom Counting Detector (T/BCD) as a two-dimensional detector are to separate electrons from protons for electron/gamma-ray physics. The T/BCD each consists of a plastic scintillator read out by 20 by 20 photodiodes and is placed before and after the Calorimeter, respectively. Energy and hit information of the T/BCD can distinguish shower profiles of electrons and protons, which show narrower and shorter showers from electrons at a given energy. The T/BCD performance has been studied with the Silicon Charge Detector and the calorimeter by using a GEANT3 + FLUKA 3.21 simulation package. By comparing the number of hits and shower width distributions between electrons and protons, we have studied optimal parameters for the e/p separation.

  8. ''Top-down'' versus ''side-on'' viewing of the inductively coupled plasma

    International Nuclear Information System (INIS)

    Faires, L.M.; Bieniewski, T.M.; Apel, C.T.; Niemczyk, T.M.

    1985-01-01

    The inductively coupled plasma is viewed by a ''top-down'' optical configuration, and the analytical performance is compared to conventional ''side-on'' viewing in terms of sensitivity, detection limits, linear dynamical range, self-reversal effects, and multielement performance. This comparison is made for a selection of eleven atom and ion lines of eight elements. The results of this study indicate distinct advantages in ''top-down'' viewing including improved sensitivity, lower detection limits, better signal-to-background ratios, and better compromise viewing position for multielement analysis. An exception to these advantages is increased self-absorption effects observed for the alkali elements

  9. Profiling Changes in Histone Post-translational Modifications by Top-Down Mass Spectrometry

    Energy Technology Data Exchange (ETDEWEB)

    Zhou, Mowei; Wu, Si; Stenoien, David L.; Zhang, Zhaorui; Connolly, Lanelle; Freitag, Michael; Pasa-Tolic, Ljiljana

    2016-11-11

    Top-down mass spectrometry is a valuable tool for charactering post-translational modifications on histones for understanding of gene control and expression. In this protocol, we describe a top-down workflow using liquid chromatography coupled to mass spectrometry for fast global profiling of changes in histone proteoforms between a wild-type and a mutant of a fungal species. The proteoforms exhibiting different abundances can be subjected to further targeted studies by other mass spectrometric or biochemical assays. This method can be generally adapted for preliminary screening for changes in histone modifications between samples such as wild-type vs. mutant, and control vs. disease.

  10. Top-down control of visual perception: attention in natural vision.

    Science.gov (United States)

    Rolls, Edmund T

    2008-01-01

    Top-down perceptual influences can bias (or pre-empt) perception. In natural scenes, the receptive fields of neurons in the inferior temporal visual cortex (IT) shrink to become close to the size of objects. This facilitates the read-out of information from the ventral visual system, because the information is primarily about the object at the fovea. Top-down attentional influences are much less evident in natural scenes than when objects are shown against blank backgrounds, though are still present. It is suggested that the reduced receptive-field size in natural scenes, and the effects of top-down attention contribute to change blindness. The receptive fields of IT neurons in complex scenes, though including the fovea, are frequently asymmetric around the fovea, and it is proposed that this is the solution the IT uses to represent multiple objects and their relative spatial positions in a scene. Networks that implement probabilistic decision-making are described, and it is suggested that, when in perceptual systems they take decisions (or 'test hypotheses'), they influence lower-level networks to bias visual perception. Finally, it is shown that similar processes extend to systems involved in the processing of emotion-provoking sensory stimuli, in that word-level cognitive states provide top-down biasing that reaches as far down as the orbitofrontal cortex, where, at the first stage of affective representations, olfactory, taste, flavour, and touch processing is biased (or pre-empted) in humans.

  11. Imaging 'top-down' mobilization of visual information: a case study in a posterior split-brain patient.

    Science.gov (United States)

    Naccache, Lionel; Sportiche, Sarah; Strauss, Mélanie; El Karoui, Imen; Sitt, Jacobo; Cohen, Laurent

    2014-01-01

    During visual perception, automatic bottom-up and controlled top-down processes occur simultaneously and interact in a complex way, making them difficult to isolate and characterize. In rare neurological conditions, such a dissociation can be achieved more easily. In the present work, we studied a patient (AC) with a posterior lesion of the corpus callosum (CC), using a combination of behavioural, structural MRI and high-density scalp EEG measures. Given the complete disruption of the posterior half of the CC, we speculated that inter-hemispheric transfer of visual information was only possible through top-down mobilization across the preserved anterior segment of the CC. We designed a matching-to-sample visual task during which this patient was randomly presented with two successive numerical targets (T1 and T2) flashed with either a short or a long stimulus-onset asynchrony (SOA), each presented within one visual hemifield (HF). Intra-hemispheric processing of visual stimuli was essentially preserved. In sharp contrast, patient's performance was massively impaired during inter-HFs trials with a short-SOA, confirming the lack of fast inter-hemispheric transfer. Crucially, patient AC spontaneously improved his performance in inter-HFs trials with a long-SOA. This behavioral improvement was correlated with a mid-frontal ERP effect occurring during the T1-T2 interval, concomitant with an increase of functional connectivity of this region with distant areas including occipital regions. These results put to light a slow, non-automatic, and frontally mediated route of inter-hemispheric transfer dependent on top-down control. © 2013 Published by Elsevier Ltd.

  12. Top-down constraints on methane and non-methane hydrocarbon emissions in the US Four Corners

    Science.gov (United States)

    Petron, G.; Miller, B. R.; Vaughn, B. H.; Kofler, J.; Mielke-Maday, I.; Sherwood, O.; Schwietzke, S.; Conley, S.; Sweeney, C.; Dlugokencky, E. J.; White, A. B.; Tans, P. P.; Schnell, R. C.

    2017-12-01

    A NASA and NOAA supported field campaign took place in the US Four Corners in April 2015 to further investigate a regional "methane hotspot" detected from space. The Four Corners region is home to the fossil fuel rich San Juan Basin, which extends between SE Colorado and NE New Mexico. The area has been extracting coal, oil and natural gas for decades. Degassing from the Fruitland coal outcrop on the Colorado side has also been reported. Instrumented aircraft, vans and ground based wind profilers were deployed for the campaign with the goal to quantify and attribute methane and non-methane hydrocarbon emissions in the region. A new comprehensive analysis of the campaign data sets will be presented and top-down emission estimates for methane and ozone precursors will be compared with available bottom-up estimates.

  13. Evaluation of the FEERv1.0 Global Top-Down Biomass Burning Emissions Inventory over Africa

    Science.gov (United States)

    Ellison, L.; Ichoku, C. M.

    2014-12-01

    With the advent of the Fire Energetics and Emissions Research (FEER) global top-down biomass burning emissions product from NASA Goddard Space Flight Center, a subsequent effort is going on to analyze and evaluate some of the main (particulate and gaseous) constituents of this emissions inventory against other inventories of biomass burning emissions over the African continent. There is consistent and continual burning during the dry season in NSSA of many small slash-and-burn fires that, though may be relatively small fires individually, collectively contribute 20-25% of the global total carbon emissions from biomass burning. As a top-down method of estimating biomass-burning emissions, FEERv1.0 is able to yield higher and more realistic emissions than previously obtainable using bottom-up methods. Results of such comparisons performed in detail over Africa will be discussed in this presentation. This effort is carried out in conjunction with a NASA-funded interdisciplinary research project investigating the effects of biomass burning on the regional climate system in Northern Sub-Saharan Africa (NSSA). Essentially, that project aims to determine how fires may have affected the severe droughts that plagued the NSSA region in recent history. Therefore, it is imperative that the biomass burning emissions input data over Africa be as accurate as possible in order to obtain a confident understanding of their interactions and feedbacks with the hydrological cycle in NSSA.

  14. Top-down Fabrication and Enhanced Active Area Electronic Characteristics of Amorphous Oxide Nanoribbons for Flexible Electronics.

    Science.gov (United States)

    Jang, Hyun-June; Joong Lee, Ki; Jo, Kwang-Won; Katz, Howard E; Cho, Won-Ju; Shin, Yong-Beom

    2017-07-18

    Inorganic amorphous oxide semiconductor (AOS) materials such as amorphous InGaZnO (a-IGZO) possess mechanical flexibility and outstanding electrical properties, and have generated great interest for use in flexible and transparent electronic devices. In the past, however, AOS devices required higher activation energies, and hence higher processing temperatures, than organic ones to neutralize defects. It is well known that one-dimensional nanowires tend to have better carrier mobility and mechanical strength along with fewer defects than the corresponding two-dimensional films, but until now it has been difficult, costly, and impractical to fabricate such nanowires in proper alignments by either "bottom-up" growth techniques or by "top-down" e-beam lithography. Here we show a top-down, cost-effective, and scalable approach for the fabrication of parallel, laterally oriented AOS nanoribbons based on lift-off and nano-imprinting. High mobility (132 cm 2 /Vs), electrical stability, and transparency are obtained in a-IGZO nanoribbons, compared to the planar films of the same a-IGZO semiconductor.

  15. The Machinery Of Climate Anti-Science, Its Efforts Against Education, Top To Bottom

    Science.gov (United States)

    Mashey, J. R.

    2014-12-01

    "There's always one every year" a fine local science teacher said after once again being hassled by a vocal parent for teaching appropriate climate science in school. How does that happen? The machinery of climate anti-science starts from the top with funders working through a maze of money paths, think tanks and front groups, employing spokespeople who can be portrayed as experts. While much of the money flows are still dark, some have been exposed over the last few years, and the effects finally filter down to the state and local levels of education. Among others, the Heartland Institute has a long history of trying to inject anti-science into K-12 and college education, having sent books, DVDs or brochures to teachers or school boards, as well as monthly newsletters to state legislators. Such are aimed at the top of the state or local organizations that affect education. For a vocal subset of the citizenry, a constant flow of misinformation from books, blogs, newsletters and some newspapers and magazines stirs action such as writing letters to editors, complaining to schools, calling on pseudo-experts and demanding equal time for pseudoscience. As the teacher said, it only takes one person to cause trouble at the local level. After a brief review of the overall machinery, this focuses on examples of anti-education tactics seen already, with some brief advice for climate scientists and educators who need to understand the machinery that supports such tactics. Some earlier history is included in http://www.desmogblog.com/2012/10/23/fakery-2-more-funny-finances-free-tax, but other attempts have surfaced in last few years, including state-wide efforts to reject Common Core Educational standard to avoid teaching climate science. Fortunately, school boards sometimes respond quite well, including one just recently in Pennsylvania.

  16. Mapping Proteoforms and Protein Complexes From King Cobra Venom Using Both Denaturing and Native Top-down Proteomics.

    Science.gov (United States)

    Melani, Rafael D; Skinner, Owen S; Fornelli, Luca; Domont, Gilberto B; Compton, Philip D; Kelleher, Neil L

    2016-07-01

    Characterizing whole proteins by top-down proteomics avoids a step of inference encountered in the dominant bottom-up methodology when peptides are assembled computationally into proteins for identification. The direct interrogation of whole proteins and protein complexes from the venom of Ophiophagus hannah (king cobra) provides a sharply clarified view of toxin sequence variation, transit peptide cleavage sites and post-translational modifications (PTMs) likely critical for venom lethality. A tube-gel format for electrophoresis (called GELFrEE) and solution isoelectric focusing were used for protein fractionation prior to LC-MS/MS analysis resulting in 131 protein identifications (18 more than bottom-up) and a total of 184 proteoforms characterized from 14 protein toxin families. Operating both GELFrEE and mass spectrometry to preserve non-covalent interactions generated detailed information about two of the largest venom glycoprotein complexes: the homodimeric l-amino acid oxidase (∼130 kDa) and the multichain toxin cobra venom factor (∼147 kDa). The l-amino acid oxidase complex exhibited two clusters of multiproteoform complexes corresponding to the presence of 5 or 6 N-glycans moieties, each consistent with a distribution of N-acetyl hexosamines. Employing top-down proteomics in both native and denaturing modes provides unprecedented characterization of venom proteoforms and their complexes. A precise molecular inventory of venom proteins will propel the study of snake toxin variation and the targeted development of new antivenoms or other biotherapeutics. © 2016 by The American Society for Biochemistry and Molecular Biology, Inc.

  17. A Top Down Strategy To Enhance Information Technologies into Israeli Higher Education.

    Science.gov (United States)

    Guri-Rosenblit, Sara

    2002-01-01

    The integration of information technologies (IT) into Israeli higher education through a top-down strategy has created systemic change. The use of IT in Israeli universities varies in terms of access-outreach, teaching-learning processes, study materials production, data and information retrieval, administrative functions, the creation of…

  18. Top-down design and verification methodology for analog mixed-signal integrated circuits

    NARCIS (Netherlands)

    Beviz, P.

    2016-01-01

    The current report contains the introduction of a novel Top-Down Design and Verification methodology for AMS integrated circuits. With the introduction of new design and verification flow, more reliable and efficient development of AMS ICs is possible. The assignment incorporated the research on the

  19. Efficacy of top-down approaches to post-conflict social coexistence ...

    African Journals Online (AJOL)

    This paper provides an assessment of the work done by the Organ on National Healing, Reconciliation and Integration (ONHRI) in post- 2008 Zimbabwe. ONHRI was employed by the Zimbabwean government (precisely as Government of National Unity) to ensure national healing and integration. The efficacy of top-down ...

  20. Functional dissociations in top-down control dependent neural repetition priming.

    NARCIS (Netherlands)

    Klaver, P.; Schnaidt, M.; Fell, J.; Ruhlmann, J.; Elger, C.E.; Fernandez, G.S.E.

    2007-01-01

    Little is known about the neural mechanisms underlying top-down control of repetition priming. Here, we use functional brain imaging to investigate these mechanisms. Study and repetition tasks used a natural/man-made forced choice task. In the study phase subjects were required to respond to either

  1. Phenomenology without conscious access is a form of consciousness without top-down attention

    OpenAIRE

    Koch, Christof; Tsuchiya, Naotsugu

    2007-01-01

    We agree with Block's basic hypothesis postulating the existence of phenomenal consciousness without cognitive access. We explain such states in terms of consciousness without top-down, endogenous attention and speculate that their correlates may be a coalition of neurons that are consigned to the back of cortex, without access to working memory and planning in frontal cortex.

  2. Top-down cascades in lakes and oceans: Different perspectives but same story?

    KAUST Repository

    Hessen, Dag Olav; Kaartvedt, Stein

    2014-01-01

    While top-down cascades from fish to phytoplankton have been a core topic in limnology for the past four decades, it has attracted far less interest in marine ecology. This is partly for historical reasons, since lake studies have been motivated

  3. Introducing Electronic Textbooks as Daily-Use Technology in Schools: A Top-Down Adoption Process

    Science.gov (United States)

    Chiu, Thomas K. F.

    2017-01-01

    This study took frequency of use and the adoption process into account to define the participants and external variables of the research model. School electronic textbooks are a daily-use technology and they are adopted in a compulsory, top-down way. Their introduction can evoke feelings of anxiety among teachers because of a possible increase in…

  4. A top-down approach to fabrication of high quality vertical heterostructure nanowire arrays

    NARCIS (Netherlands)

    Wang, Hua; Sun, Minghua; Ding, K.; Hill, M.T.; Ning, C.Z.

    2011-01-01

    We demonstrate a novel top-down approach for fabricating nanowires with unprecedented complexity and optical quality by taking advantage of a nanoscale self-masking effect. We realized vertical arrays of nanowires of 20-40 nm in diameter with 16 segments of complex longitudinal InGaAsP/InP

  5. A Top-Down Approach to Construct Execution Views of a Large Software-Intensive System

    NARCIS (Netherlands)

    Callo Arias, T.B.; America, P.H.M.; Avgeriou, P.

    2011-01-01

    This paper presents a top-down approach to construct execution views of a large and complex software intensive system. Execution viewsdescribe what the software does at runtime and how it does it. The presented approach represents a reverse architecting solution that follows a set of pre-defined

  6. MOD/R : A knowledge assisted approach towards top-down only CMOS VLSI design

    NARCIS (Netherlands)

    Spaanenburg, L.; Beunder, M.; Beune, F.A.; Gerez, Sabih H.; Holstein, B.; Luchtmeyer, R.C.C.; Smit, Jaap; van der Werf, A.; Willems, H.

    1985-01-01

    MOD/R models all views on the design space in relations. This is achieved by eliminating the package constraints, as are apparent in PCB oriented hardware description languages. Assisted by knowledge engineering it allows for a top-down, mostly hierarchical decomposition, virtually eliminating the

  7. Dietary self-control influences top-down guidance of attention to food cues

    NARCIS (Netherlands)

    Higgs, S.; Dolmans, D.; Humphreys, G.W.; Rutters, F.

    2015-01-01

    Motivational objects attract attention due to their rewarding properties, but less is known about the role that top-down cognitive processes play in the attention paid to motivationally relevant objects and how this is affected by relevant behavioural traits. Here we assess how thinking about food

  8. VLSI top-down design based on the separation of hierarchies

    NARCIS (Netherlands)

    Spaanenburg, L.; Broekema, A.; Leenstra, J.; Huys, C.

    1986-01-01

    Despite the presence of structure, interactions between the three views on VLSI design still lead to lengthy iterations. By separating the hierarchies for the respective views, the interactions are reduced. This separated hierarchy allows top-down design with functional abstractions as exemplified

  9. The Role of Top-down Attention in the Cocktail Party: Revisiting Cherry's Experiment after Sixty Years

    DEFF Research Database (Denmark)

    Marchegiani, Letizia; Karadogan, Seliz; Andersen, Taja

    2011-01-01

    We investigate the role of top-down task drive attention in the cocktail party problem. In a recently proposed computational model of top-down attention it is possible to simulate the cocktail party problem and make predictions about sensitivity to confounders under different levels of attention....... Based on such simulations we expect that under strong top-down attention pattern recognition is improved as the model can compensate for noise and confounders. We next investigate the role of temporal and spectral overlaps and speech intelligibility in humans, and how the presence of a task influences...... computational top-down attention model....

  10. Non-destructive Inspection of Top-Down Construction Joints of Column in SRC Structure using Ultrasonic Method

    International Nuclear Information System (INIS)

    Park, Seok Kyun; Baek, Un Chan; Lee, Han Bum; Kim, Myoung Mo

    2000-01-01

    The joint treatment of concrete is one of the technical problems in top down construction method. Joints created with the top down construction result in serious weakness from the aspects of both structural and water-barrier function. Ultrasonic method was used for the inspection of top down construction joints of a various column in SRC structure in this study. The advantages and limitations of this method for non-destructive inspection in top down construction joints are investigated. As a result, it has been verified that the semi-direct measurement method is more effective than the other methods for detecting the voids of construction joints using ultrasonic method

  11. Top-Down Modulation of Auditory-Motor Integration during Speech Production: The Role of Working Memory.

    Science.gov (United States)

    Guo, Zhiqiang; Wu, Xiuqin; Li, Weifeng; Jones, Jeffery A; Yan, Nan; Sheft, Stanley; Liu, Peng; Liu, Hanjun

    2017-10-25

    Although working memory (WM) is considered as an emergent property of the speech perception and production systems, the role of WM in sensorimotor integration during speech processing is largely unknown. We conducted two event-related potential experiments with female and male young adults to investigate the contribution of WM to the neurobehavioural processing of altered auditory feedback during vocal production. A delayed match-to-sample task that required participants to indicate whether the pitch feedback perturbations they heard during vocalizations in test and sample sequences matched, elicited significantly larger vocal compensations, larger N1 responses in the left middle and superior temporal gyrus, and smaller P2 responses in the left middle and superior temporal gyrus, inferior parietal lobule, somatosensory cortex, right inferior frontal gyrus, and insula compared with a control task that did not require memory retention of the sequence of pitch perturbations. On the other hand, participants who underwent extensive auditory WM training produced suppressed vocal compensations that were correlated with improved auditory WM capacity, and enhanced P2 responses in the left middle frontal gyrus, inferior parietal lobule, right inferior frontal gyrus, and insula that were predicted by pretraining auditory WM capacity. These findings indicate that WM can enhance the perception of voice auditory feedback errors while inhibiting compensatory vocal behavior to prevent voice control from being excessively influenced by auditory feedback. This study provides the first evidence that auditory-motor integration for voice control can be modulated by top-down influences arising from WM, rather than modulated exclusively by bottom-up and automatic processes. SIGNIFICANCE STATEMENT One outstanding question that remains unsolved in speech motor control is how the mismatch between predicted and actual voice auditory feedback is detected and corrected. The present study

  12. Up-, down-, strange-, charm-, and bottom-quark masses from four-flavor lattice QCD

    Energy Technology Data Exchange (ETDEWEB)

    Bazavov, A.; Bernard, C.; Brambilla, N.; Brown, N.; DeTar, C.; El-Khadra, A. X.; Gámiz, E.; Gottlieb, Steven; Heller, U. M.; Komijani, J.; Kronfeld, A. S.; Laiho, J.; Mackenzie, P. B.; Neil, E. T.; Simone, J. N.; Sugar, R. L.; Toussaint, D.; Vairo, A.; Van de Water, R. S.

    2018-02-12

    We calculate the up-, down-, strange-, charm-, and bottom-quark masses using the MILC highly improved staggered-quark ensembles with four flavors of dynamical quarks. We use ensembles at six lattice spacings ranging from $a\\approx0.15~$fm to $0.03~$fm and with both physical and unphysical values of the two light and the strange sea-quark masses. We use a new method based on heavy-quark effective theory (HQET) to extract quark masses from heavy-light pseudoscalar meson masses. Combining our analysis with our separate determination of ratios of light-quark masses we present masses of the up, down, strange, charm, and bottom quarks. Our results for the $\\overline{\\text{MS}}$-renormalized masses are $m_u(2~\\text{GeV}) = 2.118(38)~$MeV, $m_d(2~\\text{GeV}) = 4.690(54)~$MeV, $m_s(2~\\text{GeV}) = 92.52(69)~$MeV, $m_c(3~\\text{GeV}) = 984.3(5.6)~$MeV, and $m_c(m_c) = 1273(10)~$MeV, with four active flavors; and $m_b(m_b) = 4197(14)~$MeV with five active flavors. We also obtain ratios of quark masses $m_c/m_s = 11.784(22)$, $m_b/m_s = 53.93(12)$, and $m_b/m_c = 4.577(8)$. The result for $m_c$ matches the precision of the most precise calculation to date, and the other masses and all quoted ratios are the most precise to date. Moreover, these results are the first with a perturbative accuracy of $\\alpha_s^4$. As byproducts of our method, we obtain the matrix elements of HQET operators with dimension 4 and 5: $\\overline{\\Lambda}_\\text{MRS}=552(30)~$MeV in the minimal renormalon-subtracted (MRS) scheme, $\\mu_\\pi^2 = 0.06(22)~\\text{GeV}^2$, and $\\mu_G^2(m_b)=0.38(2)~\\text{GeV}^2$. The MRS scheme [Phys. Rev. D97, 034503 (2018), arXiv:1712.04983 [hep-ph

  13. Searches for Top and Bottom Squarks in pp Collisions at √s = 8 TeV

    Directory of Open Access Journals (Sweden)

    Hooberman Benjamin

    2013-05-01

    Full Text Available Supersymmetry is a popular extension to the standard model, which may solve the hierarchy problem without fine-tuning if it introduces top and bottom squarks with masses not larger than several hundred GeV. This note describes three searches for the direct pair production of these particles, based on a sample of pp collisions data corresponding to approximately 10 fb−1 collected by the Compact Muon Solenoid detector at the LHC, at a center-of-mass energy √s = 8 TeV. The searches are performed in the single lepton final state focusing on events with large transverse mass, the same-sign dilepton final state, and the all-hadronic final state using the αT quantity. No evidence for the production of top or bottom squarks is observed. The results are used to place stringent constraints on the masses of these particles.

  14. 3D virtual human rapid modeling method based on top-down modeling mechanism

    Directory of Open Access Journals (Sweden)

    LI Taotao

    2017-01-01

    Full Text Available Aiming to satisfy the vast custom-made character demand of 3D virtual human and the rapid modeling in the field of 3D virtual reality, a new virtual human top-down rapid modeling method is put for-ward in this paper based on the systematic analysis of the current situation and shortage of the virtual hu-man modeling technology. After the top-level realization of virtual human hierarchical structure frame de-sign, modular expression of the virtual human and parameter design for each module is achieved gradu-al-level downwards. While the relationship of connectors and mapping restraints among different modules is established, the definition of the size and texture parameter is also completed. Standardized process is meanwhile produced to support and adapt the virtual human top-down rapid modeling practice operation. Finally, the modeling application, which takes a Chinese captain character as an example, is carried out to validate the virtual human rapid modeling method based on top-down modeling mechanism. The result demonstrates high modelling efficiency and provides one new concept for 3D virtual human geometric mod-eling and texture modeling.

  15. Energetic conditions promoting top-down control of prey by predators.

    Directory of Open Access Journals (Sweden)

    Kristin N Marshall

    Full Text Available Humans remove large amounts of biomass from natural ecosystems, and large bodied high trophic level animals are especially sensitive and vulnerable to exploitation. The effects of removing top-predators on food webs are often difficult to predict because of limited information on species interaction strengths. Here we used a three species predator-prey model to explore relationships between energetic properties of trophodynamic linkages and interaction strengths to provide heuristic rules that indicate observable energetic conditions that are most likely to lead to stable and strong top-down control of prey by predator species. We found that strong top-down interaction strengths resulted from low levels of energy flow from prey to predators. Strong interactions are more stable when they are a consequence of low per capita predation and when predators are subsidized by recruitment. Diet composition also affects stability, but the relationship depends on the form of the functional response. Our results imply that for generalist satiating predators, strong top-down control on prey is most likely for prey items that occupy a small portion of the diet and when density dependent recruitment is moderately high.

  16. Crustal inheritance and arc magmatism: Magnetotelluric constraints from the Washington Cascades on top-down control

    Science.gov (United States)

    Bedrosian, P.; Peacock, J.; Bowles-martinez, E.; Schultz, A.; Hill, G.

    2017-12-01

    Worldwide, arc volcanism occurs along relatively narrow magmatic arcs, the locations of which are considered to mark the onset of dehydration reactions within the subducting slab. This `bottom-up' approach, in which the location of arc volcanism reflects where fluids and melt are generated, explains first-order differences in trench-to-arc distance and is consistent with known variations in the thermal structure and geometry of subducting slabs. At a finer scale, arc segmentation, magmatic gaps, and anomalous forearc and backarc magmatism are also frequently interpreted in terms of variations in slab geometry, composition, or thermal structure.The role of inherited crustal structure in controlling faulting and deformation is well documented; less well examined is the role of crustal structure in controlling magmatism. While the source distribution of melt and subduction fluids is critical to determining the location of arc magmatism, we argue that crustal structure provides `top-down' control on patterns or seismicity and deformation as well as the channeling and ascent of arc magmas. We present evidence within the Washington Cascades based upon correlation between a new three-dimensional resistivity model, potential-field data, seismicity, and Quaternary volcanism. We image a mid-Tertiary batholith, intruded within an Eocene crustal suture zone, and extending throughout much of the crustal column. This and neighboring plutons are interpreted to channel crustal fluids and melt along their margins within steeply dipping zones of marine to transitional metasedimentary rock. Mount St. Helens is interpreted to be fed by fluids and melt generated further east at greater slab depths, migrating laterally (underplating?) beneath the Spirit Lake batholith, and ascending through metasedimentary rocks within the brittle crust. At a regional scale, we argue that this concealed suture zone controls present-day deformation and seismicity as well as the distribution of forearc

  17. On the matching of top-down knowledge with sensory input in the perception of ambiguous speech

    Directory of Open Access Journals (Sweden)

    Hannemann R

    2010-06-01

    Full Text Available Abstract Background How does the brain repair obliterated speech and cope with acoustically ambivalent situations? A widely discussed possibility is to use top-down information for solving the ambiguity problem. In the case of speech, this may lead to a match of bottom-up sensory input with lexical expectations resulting in resonant states which are reflected in the induced gamma-band activity (GBA. Methods In the present EEG study, we compared the subject's pre-attentive GBA responses to obliterated speech segments presented after a series of correct words. The words were a minimal pair in German and differed with respect to the degree of specificity of segmental phonological information. Results The induced GBA was larger when the expected lexical information was phonologically fully specified compared to the underspecified condition. Thus, the degree of specificity of phonological information in the mental lexicon correlates with the intensity of the matching process of bottom-up sensory input with lexical information. Conclusions These results together with those of a behavioural control experiment support the notion of multi-level mechanisms involved in the repair of deficient speech. The delineated alignment of pre-existing knowledge with sensory input is in accordance with recent ideas about the role of internal forward models in speech perception.

  18. Top-down estimates of benzene and toluene emissions in the Pearl River Delta and Hong Kong, China

    Directory of Open Access Journals (Sweden)

    X. Fang

    2016-03-01

    Full Text Available Benzene (C6H6 and toluene (C7H8 are toxic to humans and the environment. They are also important precursors of ground-level ozone and secondary organic aerosols and contribute substantially to severe air pollution in urban areas in China. Discrepancies exist between different bottom-up inventories for benzene and toluene emissions in the Pearl River Delta (PRD and Hong Kong (HK, which are emission hot spots in China. This study provides top-down estimates of benzene and toluene emissions in the PRD and HK using atmospheric measurement data from a rural site in the area, Heshan, an atmospheric transport model, and an inverse modeling method. The model simulations captured the measured mixing ratios during most pollution episodes. For the PRD and HK, the benzene emissions estimated in this study for 2010 were 44 (12–75 and 5 (2–7 Gg yr−1 for the PRD and HK, respectively, and the toluene emissions were 131 (44–218 and 6 (2–9 Gg yr−1, respectively. Temporal and spatial differences between the inversion estimate and four different bottom-up emission estimates are discussed, and it is proposed that more observations at different sites are urgently needed to better constrain benzene and toluene (and other air pollutant emissions in the PRD and HK in the future.

  19. Top-down estimates of benzene and toluene emissions in the Pearl River Delta and Hong Kong, China

    Science.gov (United States)

    Fang, Xuekun; Shao, Min; Stohl, Andreas; Zhang, Qiang; Zheng, Junyu; Guo, Hai; Wang, Chen; Wang, Ming; Ou, Jiamin; Thompson, Rona L.; Prinn, Ronald G.

    2016-03-01

    Benzene (C6H6) and toluene (C7H8) are toxic to humans and the environment. They are also important precursors of ground-level ozone and secondary organic aerosols and contribute substantially to severe air pollution in urban areas in China. Discrepancies exist between different bottom-up inventories for benzene and toluene emissions in the Pearl River Delta (PRD) and Hong Kong (HK), which are emission hot spots in China. This study provides top-down estimates of benzene and toluene emissions in the PRD and HK using atmospheric measurement data from a rural site in the area, Heshan, an atmospheric transport model, and an inverse modeling method. The model simulations captured the measured mixing ratios during most pollution episodes. For the PRD and HK, the benzene emissions estimated in this study for 2010 were 44 (12-75) and 5 (2-7) Gg yr-1 for the PRD and HK, respectively, and the toluene emissions were 131 (44-218) and 6 (2-9) Gg yr-1, respectively. Temporal and spatial differences between the inversion estimate and four different bottom-up emission estimates are discussed, and it is proposed that more observations at different sites are urgently needed to better constrain benzene and toluene (and other air pollutant) emissions in the PRD and HK in the future.

  20. Current-Voltage Characteristics of the Metal / Organic Semiconductor / Metal Structures: Top and Bottom Contact Configuration Case

    Directory of Open Access Journals (Sweden)

    Šarūnas MEŠKINIS

    2013-03-01

    Full Text Available In present study five synthesized organic semiconductor compounds have been used for fabrication of the planar metal / organic semiconductor / metal structures. Both top electrode and bottom electrode configurations were used. Current-voltage (I-V characteristics of the samples were investigated. Effect of the hysteresis of the I-V characteristics was observed for all the investigated samples. However, strength of the hysteresis was dependent on the organic semiconductor used. Study of I-V characteristics of the top contact Al/AT-RB-1/Al structures revealed, that in (0 – 500 V voltages range average current of the samples measured in air is only slightly higher than current measured in nitrogen ambient. Deposition of the ultra-thin diamond like carbon interlayer resulted in both decrease of the hysteresis of I-V characteristics of top contact Al/AT-RB-1/Al samples. However, decreased current and decreased slope of the I-V characteristics of the samples with diamond like carbon interlayer was observed as well. I-V characteristic hysteresis effect was less pronounced in the case of the bottom contact metal/organic semiconductor/metal samples. I-V characteristics of the bottom contact samples were dependent on electrode metal used.DOI: http://dx.doi.org/10.5755/j01.ms.19.1.3816

  1. Enhanced stimulated emission in ZnO thin films using microdisk top-down structuring

    Energy Technology Data Exchange (ETDEWEB)

    Nomenyo, K.; Kostcheev, S.; Lérondel, G. [Laboratoire de Nanotechnologie et d' Instrumentation Optique, Institut Charles Delaunay, CNRS UMR 6281, Université de Technologie de Troyes, 12 rue Marie Curie, CS 42060, 10004 Troyes Cedex (France); Gadallah, A.-S. [Laboratoire de Nanotechnologie et d' Instrumentation Optique, Institut Charles Delaunay, CNRS UMR 6281, Université de Technologie de Troyes, 12 rue Marie Curie, CS 42060, 10004 Troyes Cedex (France); Department of Laser Sciences and Interactions, National Institute of Laser Enhanced Sciences, Cairo University, Giza (Egypt); Rogers, D. J. [Nanovation, 8, route de Chevreuse, 78117 Châteaufort (France)

    2014-05-05

    Microdisks were fabricated in zinc oxide (ZnO) thin films using a top-down approach combining electron beam lithography and reactive ion etching. These microdisk structured thin films exhibit a stimulated surface emission between 3 and 7 times higher than that from a reference film depending on the excitation power density. Emission peak narrowing, reduction in lasing threshold and blue-shifting of the emission wavelength were observed along with enhancement in the emitted intensity. Results indicate that this enhancement is due to an increase in the internal quantum efficiency combined with an amplification of the stimulated emission. An analysis in terms of waveguiding is presented in order to explain these effects. These results demonstrate that very significant gains in emission can be obtained through conventional microstructuration without the need for more onerous top-down nanostructuration techniques.

  2. Identification of hemoglobin variants by top-down mass spectrometry using selected diagnostic product ions.

    Science.gov (United States)

    Coelho Graça, Didia; Hartmer, Ralf; Jabs, Wolfgang; Beris, Photis; Clerici, Lorella; Stoermer, Carsten; Samii, Kaveh; Hochstrasser, Denis; Tsybin, Yury O; Scherl, Alexander; Lescuyer, Pierre

    2015-04-01

    Hemoglobin disorder diagnosis is a complex procedure combining several analytical steps. Due to the lack of specificity of the currently used protein analysis methods, the identification of uncommon hemoglobin variants (proteoforms) can become a hard task to accomplish. The aim of this work was to develop a mass spectrometry-based approach to quickly identify mutated protein sequences within globin chain variants. To reach this goal, a top-down electron transfer dissociation mass spectrometry method was developed for hemoglobin β chain analysis. A diagnostic product ion list was established with a color code strategy allowing to quickly and specifically localize a mutation in the hemoglobin β chain sequence. The method was applied to the analysis of rare hemoglobin β chain variants and an (A)γ-β fusion protein. The results showed that the developed data analysis process allows fast and reliable interpretation of top-down electron transfer dissociation mass spectra by nonexpert users in the clinical area.

  3. Warming increases the top-down effects and metabolism of a subtidal herbivore

    Directory of Open Access Journals (Sweden)

    Lindsey A. Carr

    2013-07-01

    Full Text Available Ecological theory and experiments indicate that warming can increase the relative strength of top-down effects via alterations to metabolic rates in several different systems, thereby resulting in decreased plant biomass at higher temperatures. However, the general influence of increased environmental temperature on top-down effects is not well understood in systems where organisms experience relatively large variation in temperature. Rapid ocean temperature changes are pervasive throughout the Galápagos Islands due to upwelling and downwelling of internal waves, ENSO events and seasonality. We measured the effect of large, but not uncommon, water temperature variation on the metabolism and grazing rate of a common subtidal herbivore and on photosynthesis of their algal prey in the Galápagos Islands in July 2012. We found that green urchin consumption and metabolism were greater at the higher temperature treatment (28°C, resulting in significantly less algal biomass. Our result that warming increased green urchin metabolic rates, even in a highly dynamic system, provides further support for a mechanistic link between environmental temperature and feeding rates. And further, our findings suggest individual response to temperature results in changes in top-down effects. And if this response is maintained over longer-time scales of days to weeks, this could translate to alterations of larger-scale ecological patterns, such as primary producer community composition and structure.

  4. A top-down design methodology and its implementation for VCSEL-based optical links design

    Science.gov (United States)

    Li, Jiguang; Cao, Mingcui; Cai, Zilong

    2005-01-01

    In order to find the optimal design for a given specification of an optical communication link, an integrated simulation of electronic, optoelectronic, and optical components of a complete system is required. It is very important to be able to simulate at both system level and detailed model level. This kind of model is feasible due to the high potential of Verilog-AMS language. In this paper, we propose an effective top-down design methodology and employ it in the development of a complete VCSEL-based optical links simulation. The principle of top-down methodology is that the development would proceed from the system to device level. To design a hierarchical model for VCSEL based optical links, the design framework is organized in three levels of hierarchy. The models are developed, and implemented in Verilog-AMS. Therefore, the model parameters are fitted to measured data. A sample transient simulation demonstrates the functioning of our implementation. Suggestions for future directions in top-down methodology used for optoelectronic systems technology are also presented.

  5. A Top Down Strategy to Enhance Information Technologies into Israeli Higher Education

    Directory of Open Access Journals (Sweden)

    Sarah Guri-Rosenblit

    2002-01-01

    Full Text Available This article examines the integration of the new information technologies (IT into Israeli higher education, and most particularly its research universities through a top-down strategy, initiated by the Israeli Council for Higher Education since the end of 1999. This top-down strategy has created a systemic change that will affect the many layers of university activities rather than in a random, sporadic manner undertaken by enthusiastic individuals. This article discusses the built-in contradictions and dilemmas in the process of adapting distance teaching methods by conventional universities in Israel (as well as in other higher education systems. It examines the merits of a top-down strategy aimed to implement the IT through a macro-level, systemic approach, and analyses the differential uses of the IT in Israeli higher education institutions, relating to variables of: access-outreach; teaching-learning processes; study materials production; data and information retrieval; administrative functions; the creation of researchers' communities; inter-institutional collaboration; and associated costs. The article concludes with some suggestions for effective implementation of the IT in different types of higher education institutions in a comprehensive and systematic manner, that will take into account their academic ethos and organizational infrastructure, and cater to the unique needs and characteristics of their relevant constituencies.

  6. How to inhibit a distractor location? Statistical learning versus active, top-down suppression.

    Science.gov (United States)

    Wang, Benchi; Theeuwes, Jan

    2018-05-01

    Recently, Wang and Theeuwes (Journal of Experimental Psychology: Human Perception and Performance, 44(1), 13-17, 2018a) demonstrated the role of lingering selection biases in an additional singleton search task in which the distractor singleton appeared much more often in one location than in all other locations. For this location, there was less capture and selection efficiency was reduced. It was argued that statistical learning induces plasticity within the spatial priority map such that particular locations that are high likely to contain a distractor are suppressed relative to all other locations. The current study replicated these findings regarding statistical learning (Experiment 1) and investigated whether similar effects can be obtained by cueing the distractor location in a top-down way on a trial-by-trial basis. The results show that top-down cueing of the distractor location with long (1,500 ms; Experiment 2) and short stimulus-onset symmetries (SOAs) (600 ms; Experiment 3) does not result in suppression: The amount of capture nor the efficiency of selection was affected by the cue. If anything, we found an attentional benefit (instead of the suppression) for the short SOA. We argue that through statistical learning, weights within the attentional priority map are changed such that one location containing a salient distractor is suppressed relative to all other locations. Our cueing experiments show that this effect cannot be accomplished by active, top-down suppression. Consequences for recent theories of distractor suppression are discussed.

  7. Top-down attention affects sequential regularity representation in the human visual system.

    Science.gov (United States)

    Kimura, Motohiro; Widmann, Andreas; Schröger, Erich

    2010-08-01

    Recent neuroscience studies using visual mismatch negativity (visual MMN), an event-related brain potential (ERP) index of memory-mismatch processes in the visual sensory system, have shown that although sequential regularities embedded in successive visual stimuli can be automatically represented in the visual sensory system, an existence of sequential regularity itself does not guarantee that the sequential regularity will be automatically represented. In the present study, we investigated the effects of top-down attention on sequential regularity representation in the visual sensory system. Our results showed that a sequential regularity (SSSSD) embedded in a modified oddball sequence where infrequent deviant (D) and frequent standard stimuli (S) differing in luminance were regularly presented (SSSSDSSSSDSSSSD...) was represented in the visual sensory system only when participants attended the sequential regularity in luminance, but not when participants ignored the stimuli or simply attended the dimension of luminance per se. This suggests that top-down attention affects sequential regularity representation in the visual sensory system and that top-down attention is a prerequisite for particular sequential regularities to be represented. Copyright 2010 Elsevier B.V. All rights reserved.

  8. Propulsion integration of hypersonic air-breathing vehicles utilizing a top-down design methodology

    Science.gov (United States)

    Kirkpatrick, Brad Kenneth

    In recent years, a focus of aerospace engineering design has been the development of advanced design methodologies and frameworks to account for increasingly complex and integrated vehicles. Techniques such as parametric modeling, global vehicle analyses, and interdisciplinary data sharing have been employed in an attempt to improve the design process. The purpose of this study is to introduce a new approach to integrated vehicle design known as the top-down design methodology. In the top-down design methodology, the main idea is to relate design changes on the vehicle system and sub-system level to a set of over-arching performance and customer requirements. Rather than focusing on the performance of an individual system, the system is analyzed in terms of the net effect it has on the overall vehicle and other vehicle systems. This detailed level of analysis can only be accomplished through the use of high fidelity computational tools such as Computational Fluid Dynamics (CFD) or Finite Element Analysis (FEA). The utility of the top-down design methodology is investigated through its application to the conceptual and preliminary design of a long-range hypersonic air-breathing vehicle for a hypothetical next generation hypersonic vehicle (NHRV) program. System-level design is demonstrated through the development of the nozzle section of the propulsion system. From this demonstration of the methodology, conclusions are made about the benefits, drawbacks, and cost of using the methodology.

  9. Application of Tandem Two-Dimensional Mass Spectrometry for Top-Down Deep Sequencing of Calmodulin.

    Science.gov (United States)

    Floris, Federico; Chiron, Lionel; Lynch, Alice M; Barrow, Mark P; Delsuc, Marc-André; O'Connor, Peter B

    2018-06-04

    Two-dimensional mass spectrometry (2DMS) involves simultaneous acquisition of the fragmentation patterns of all the analytes in a mixture by correlating their precursor and fragment ions by modulating precursor ions systematically through a fragmentation zone. Tandem two-dimensional mass spectrometry (MS/2DMS) unites the ultra-high accuracy of Fourier transform ion cyclotron resonance (FT-ICR) MS/MS and the simultaneous data-independent fragmentation of 2DMS to achieve extensive inter-residue fragmentation of entire proteins. 2DMS was recently developed for top-down proteomics (TDP), and applied to the analysis of calmodulin (CaM), reporting a cleavage coverage of about ~23% using infrared multiphoton dissociation (IRMPD) as fragmentation technique. The goal of this work is to expand the utility of top-down protein analysis using MS/2DMS in order to extend the cleavage coverage in top-down proteomics further into the interior regions of the protein. In this case, using MS/2DMS, the cleavage coverage of CaM increased from ~23% to ~42%. Graphical Abstract Two-dimensional mass spectrometry, when applied to primary fragment ions from the source, allows deep-sequencing of the protein calmodulin.

  10. Interactive effects of trait and state affect on top-down control of attention.

    Science.gov (United States)

    Hur, Juyoen; Miller, Gregory A; McDavitt, Jenika R B; Spielberg, Jeffrey M; Crocker, Laura D; Infantolino, Zachary P; Towers, David N; Warren, Stacie L; Heller, Wendy

    2015-08-01

    Few studies have investigated how attentional control is affected by transient affective states while taking individual differences in affective traits into consideration. In this study, participants completed a color-word Stroop task immediately after undergoing a positive, neutral or negative affective context manipulation (ACM). Behavioral performance was unaffected by any ACM considered in isolation. For individuals high in trait negative affect (NA), performance was impaired by the negative but not the positive or neutral ACM. Neuroimaging results indicate that activity in primarily top-down control regions of the brain (inferior frontal gyrus and dorsal anterior cingulate cortex) was suppressed in the presence of emotional arousal (both negative and positive ACMs). This effect appears to have been exacerbated or offset by co-occurring activity in other top-down control regions (parietal) and emotion processing regions (orbitofrontal cortex, amygdala and nucleus accumbens) as a function of the valence of state affect (positive or negative) and trait affect (trait NA or trait PA). Neuroimaging results are consistent with behavioral findings. In combination, they indicate both additive and interactive influences of trait and state affect on top-down control of attention. © The Author (2015). Published by Oxford University Press. For Permissions, please email: journals.permissions@oup.com.

  11. Top-Down Hydrogen-Deuterium Exchange Analysis of Protein Structures Using Ultraviolet Photodissociation.

    Science.gov (United States)

    Brodie, Nicholas I; Huguet, Romain; Zhang, Terry; Viner, Rosa; Zabrouskov, Vlad; Pan, Jingxi; Petrotchenko, Evgeniy V; Borchers, Christoph H

    2018-03-06

    Top-down hydrogen-deuterium exchange (HDX) analysis using electron capture or transfer dissociation Fourier transform mass spectrometry (FTMS) is a powerful method for the analysis of secondary structure of proteins in solution. The resolution of the method is a function of the degree of fragmentation of backbone bonds in the proteins. While fragmentation is usually extensive near the N- and C-termini, electron capture (ECD) or electron transfer dissociation (ETD) fragmentation methods sometimes lack good coverage of certain regions of the protein, most often in the middle of the sequence. Ultraviolet photodissociation (UVPD) is a recently developed fast-fragmentation technique, which provides extensive backbone fragmentation that can be complementary in sequence coverage to the aforementioned electron-based fragmentation techniques. Here, we explore the application of electrospray ionization (ESI)-UVPD FTMS on an Orbitrap Fusion Lumos Tribrid mass spectrometer to top-down HDX analysis of proteins. We have incorporated UVPD-specific fragment-ion types and fragment-ion mixtures into our isotopic envelope fitting software (HDX Match) for the top-down HDX analysis. We have shown that UVPD data is complementary to ETD, thus improving the overall resolution when used as a combined approach.

  12. Residential electricity consumption in Portugal: Findings from top-down and bottom-up models

    International Nuclear Information System (INIS)

    Wiesmann, Daniel; Lima Azevedo, Ines; Ferrao, Paulo; Fernandez, John E.

    2011-01-01

    An econometric study of the Portuguese residential electricity consumption is presented, with a focus on the influence of dwelling characteristics on consumption. The relationship between the dwelling and household characteristics on per capita residential electricity consumption is estimated at two different scales, involving two distinct databases: the first includes data at the municipality level for 2001, the second is the most recent Portuguese consumer expenditure survey that was collected in 2005 and 2006. The results of the analysis at both scales are consistent and indicate that household and dwelling characteristics have a significant influence on residential electricity consumption. Our results show that in Portugal the direct effect of income on electricity consumption is low and becomes smaller when more relevant control variables are included in the analysis. Future demand of electricity in Portugal will be significantly influenced by trends in socioeconomic factors as well as changes in the building stock. These trends should be taken in consideration in the formulation of policy measures to reduce electricity consumption. - Research highlights: → Econometric study of per capita residential electricity consumption in Portugal. → Comparing models at two levels of aggregation: by municipality and by household. → Using proxies for the dwelling characteristics on the municipality level. → Results from both scales are consistent. → Income elasticity is low and the influence of dwelling characteristics is significant.

  13. Top-down versus bottom-up theories of subjective well-being

    NARCIS (Netherlands)

    B. Headey; R. Veenhoven (Ruut); A.J. Wearing

    1991-01-01

    textabstractThis paper addresses issues of causal direction in research on subjective well being (SWB). Previous researchers have generally assumed that such variables as domain satisfactions, social support, life events, and levels of expectation and aspiration are causes of SWB. Critics have

  14. Top-Down and Bottom-Up Approach for Model-Based Testing of Product Lines

    Directory of Open Access Journals (Sweden)

    Stephan Weißleder

    2013-03-01

    Full Text Available Systems tend to become more and more complex. This has a direct impact on system engineering processes. Two of the most important phases in these processes are requirements engineering and quality assurance. Two significant complexity drivers located in these phases are the growing number of product variants that have to be integrated into the requirements engineering and the ever growing effort for manual test design. There are modeling techniques to deal with both complexity drivers like, e.g., feature modeling and model-based test design. Their combination, however, has been seldom the focus of investigation. In this paper, we present two approaches to combine feature modeling and model-based testing as an efficient quality assurance technique for product lines. We present the corresponding difficulties and approaches to overcome them. All explanations are supported by an example of an online shop product line.

  15. Integrated bottom up and top down approach to optimization of the extrusion process

    NARCIS (Netherlands)

    Vaneker, Thomas H.J.; Koenis, P.T.G.; van Ouwerkerk, Gijs; van Ouwerkerk, Gijs; Nilsen, K.E.; van Houten, Frederikus J.A.M.

    2008-01-01

    Boal BV and the University of Twente participate in research projects focused on improvement of die design methods for aluminum extrusion dies. Within this research empirical knowledge is combined with insights gained from numerical process simulations. Design rules for improvements to the geometry

  16. Bottom-up, top-down? Connecting software architecture design with use

    DEFF Research Database (Denmark)

    Büscher, Monika; Christensen, Michael; Hansen, Klaus Marius

    2009-01-01

    Participatory design has traditinally focused on the design of technology applications or the co-realisation of a more holostic socio-technical bricolage of new and existing technologies and pratices. 'Infrastructural' design issues like software architectures, programming languages, communicatio...

  17. Residential electricity consumption in Portugal: Findings from top-down and bottom-up models

    Energy Technology Data Exchange (ETDEWEB)

    Wiesmann, Daniel, E-mail: daniel.wiesmann@ist.utl.p [Instituto Superior Tecnico, Technical University of Lisbon, Avenida Rovisco Pais 1, 1049-001 Lisbon (Portugal); Lima Azevedo, Ines [Department of Engineering and Public Policy, Carnegie Mellon University, 5000 Forbes Avenue, Pittsburgh, PA 15213 (United States); Ferrao, Paulo [Instituto Superior Tecnico, Technical University of Lisbon, Avenida Rovisco Pais 1, 1049-001 Lisbon (Portugal); Fernandez, John E. [Department of Architecture, Massachusetts Institute of Technology, 77 Massachusetts Avenue, Cambridge, MA 02139 (United States)

    2011-05-15

    An econometric study of the Portuguese residential electricity consumption is presented, with a focus on the influence of dwelling characteristics on consumption. The relationship between the dwelling and household characteristics on per capita residential electricity consumption is estimated at two different scales, involving two distinct databases: the first includes data at the municipality level for 2001, the second is the most recent Portuguese consumer expenditure survey that was collected in 2005 and 2006. The results of the analysis at both scales are consistent and indicate that household and dwelling characteristics have a significant influence on residential electricity consumption. Our results show that in Portugal the direct effect of income on electricity consumption is low and becomes smaller when more relevant control variables are included in the analysis. Future demand of electricity in Portugal will be significantly influenced by trends in socioeconomic factors as well as changes in the building stock. These trends should be taken in consideration in the formulation of policy measures to reduce electricity consumption. - Research highlights: {yields} Econometric study of per capita residential electricity consumption in Portugal. {yields} Comparing models at two levels of aggregation: by municipality and by household. {yields} Using proxies for the dwelling characteristics on the municipality level. {yields} Results from both scales are consistent. {yields} Income elasticity is low and the influence of dwelling characteristics is significant.

  18. Bottom up and Top Down: Making IT a Key Part of the Campus Sustainability Effort

    Science.gov (United States)

    Cromwell, Dennis; Hanks, Kristin; Engel, Sarah

    2009-01-01

    Information technology (IT) is regarded globally as a voracious consumer of energy. According to a 2007 research paper issued by the United Kingdom's Global Action Plan, IT accounts for 10 percent of the electrical usage in the U.K. In the United States, Stanford University estimates that IT accounts for 15 percent of its overall electrical use.…

  19. Implementing collaborative improvement, top-down, bottom-up, or both?

    NARCIS (Netherlands)

    Kaltoft, Rasmus; Boer, H.; Boer, Harm; Caniato, Federico; Gertsen, Frank; Middel, H.G.A.; Steendahl Nielsen, Jacob

    2004-01-01

    The research presented in this paper was aimed at increasing the current understanding of the process of developing collaborative improvement in Extended Manufacturing Enterprises (EME). Based on action research and action learning of three EMEs involving a total of thirteen companies from five

  20. Advances in top-down and bottom-up approaches to video-based camera tracking

    OpenAIRE

    Marimón Sanjuán, David

    2007-01-01

    Video-based camera tracking consists in trailing the three dimensional pose followed by a mobile camera using video as sole input. In order to estimate the pose of a camera with respect to a real scene, one or more three dimensional references are needed. Examples of such references are landmarks with known geometric shape, or objects for which a model is generated beforehand. By comparing what is seen by a camera with what is geometrically known from reality, it is possible to recover the po...

  1. Advances in top-down and bottom-up approaches to video-based camera tracking

    OpenAIRE

    Marimón Sanjuán, David; Ebrahimi, Touradj

    2008-01-01

    Video-based camera tracking consists in trailing the three dimensional pose followed by a mobile camera using video as sole input. In order to estimate the pose of a camera with respect to a real scene, one or more three dimensional references are needed. Examples of such references are landmarks with known geometric shape, or objects for which a model is generated beforehand. By comparing what is seen by a camera with what is geometrically known from reality, it is possible to recover the po...

  2. Integration of top-down and bottom-up information for audio organization and retrieval

    DEFF Research Database (Denmark)

    Jensen, Bjørn Sand

    The increasing availability of digital audio and music calls for methods and systems to analyse and organize these digital objects. This thesis investigates three elements related to such systems focusing on the ability to represent and elicit the user's view on the multimedia object and the system...... output. The aim is to provide organization and processing, which aligns with the understanding and needs of the users. Audio and music is often characterized by the large amount of heterogenous information. The rst aspect investigated is the integration of such multi-variate and multi-modal information...... (indirect scaling). Inference is performed by analytical and simulation based methods, including the Laplace approximation and expectation propagation. In order to minimize the cost of the often expensive and lengthly experimentation, sequential experiment design or active learning is supported. The setup...

  3. Learning affects top down and bottom up modulation of eye movements in decision making

    OpenAIRE

    Jacob L. Orquin; Martin P. Bagger; Simone Mueller Loose

    2013-01-01

    Repeated decision making is subject to changes over time such as decreases in decision time and information use and increases in decision accuracy. We show that a traditional strategy selection view of decision making cannot account for these temporal dynamics without relaxing main assumptions about what defines a decision strategy. As an alternative view we suggest that temporal dynamics in decision making are driven by attentional and perceptual processes and that this view has been express...

  4. Understanding Coastal Carbon Cycling by Linking Top-Down and Bottom-Up Approaches

    Science.gov (United States)

    Barr, Jordan G.; Troxler, Tiffany G.; Najjar, Raymond G.

    2014-09-01

    The coastal zone, despite occupying a small fraction of the Earth's surface area, is an important component of the global carbon (C) cycle. Coastal wetlands, including mangrove forests, tidal marshes, and seagrass meadows, compose a domain of large reservoirs of biomass and soil C [Fourqurean et al., 2012; Donato et al., 2011; Pendleton et al., 2012; Regnier et al., 2013; Bauer et al., 2013]. These wetlands and their associated C reservoirs (2 to 25 petagrams C; best estimate of 7 petagrams C [Pendleton et al., 2012]) provide numerous ecosystem services and serve as key links between land and ocean.

  5. Top-down control of invertebrates by Ninespine Stickleback in Arctic ponds

    Science.gov (United States)

    Laske, Sarah M.; Rosenberger, Amanda E.; Kane, William J.; Wipfli, Mark S.; Zimmerman, Christian E.

    2017-01-01

    Despite their widespread presence in northern-latitude ecosystems, the ecological role of Ninespine Stickleback Pungitius pungitius is not well understood. Ninespine Stickleback can occupy both top and intermediate trophic levels in freshwater ecosystems, so their role in food webs as a predator on invertebrates and as a forage fish for upper level consumers probably is substantial. We introduced Ninespine Sticklebacks to fishless ponds to elucidate their potential effects as a predator on invertebrate communities in Arctic lentic freshwaters. We hypothesized that Ninespine Stickleback would affect freshwater invertebrate communities in a top-down manner. We predicted that the addition of Ninespine Sticklebacks to fishless ponds would: 1) reduce invertebrate taxonomic richness, 2) decrease overall invertebrate abundance, 3) reduce invertebrate biomass, and 4) decrease average invertebrate body size. We tested our hypothesis at 2 locations by adding Ninespine Stickleback to isolated ponds and compared invertebrate communities over time between fish-addition and fishless control ponds. Ninespine Sticklebacks exerted strong top-down pressure on invertebrate communities mainly by changing invertebrate taxonomic richness and biomass and, to a lesser extent, abundance and average invertebrate size. Our results supported the hypothesis that Ninespine Stickleback may help shape lentic food webs in the Arctic.

  6. Review of the patents of Top and Bottom End Piece and fuel materials issued by overseas fuel vendors

    International Nuclear Information System (INIS)

    Yoon, Kyung Ho; Song, Kee Nam; Kim Hyung Kyu; Kang, Heung Seok; Bang, Je Geon.

    1997-06-01

    In order to develop new type nuclear fuel which can be loaded in the domestic PWRs without serious design changes, it is very important to understand the developing status of fuel components being conducted by overseas fuel vendors prior to commence the full-scale campaign. In this report, patents recorded in US patent lists have been inquired to understand the object, the background and the peculiarity of the invented components for top/bottom end piece and fuel materials. In addition, the important things which must be considered in development of new type fuel were described. (author). 18 tabs., 63 figs., 24 refs

  7. Recent results on top, bottom and exotic physics at the Tevatron

    International Nuclear Information System (INIS)

    Shaw, N.M.

    1993-08-01

    A summary of results from the recently concluded 1991--1993 Tevatron run is presented. Selected topics from b physics and exotic particle searches from the CDF and D0 collaborations are reviewed. Preliminary results from the CDF top search, using 12pb -1 from the 1992--1993 run, are given. In particular, the lepton + b-tag and dilepton analyses are discussed. Preliminary results from the CDF dilepton analysis places a lower limit on the top quark mass of 108GeV/c 2 at the 95% C.L

  8. Spallation Neutron Source Availability Top-Down Apportionment Using Characteristic Factors and Expert Opinion

    International Nuclear Information System (INIS)

    Haire, M.J.; Schryver, J.C.

    1999-01-01

    Apportionment is the assignment of top-level requirements to lower tier elements of the overall facility. A method for apportioning overall facility availability requirements among systems and subsystems is presented. Characteristics that influence equipment reliability and maintainability are discussed. Experts, using engineering judgment, scored each characteristic for each system whose availability design goal is to be established. The Analytic Hierarchy Process (AHP) method is used to produce a set of weighted rankings for each characteristic for each alternative system. A mathematical model is derived which incorporates these weighting factors. The method imposes higher availability requirements on those systems in which an incremental increase in availability is easier to achieve, and lower availability requirements where greater availability is more difficult and costly. An example is given of applying this top-down apportionment methodology to the Spallation Neutron Source (SNS) facility

  9. Encouraging top-down attention in visual search:A developmental perspective.

    Science.gov (United States)

    Lookadoo, Regan; Yang, Yingying; Merrill, Edward C

    2017-10-01

    Four experiments are reported in which 60 younger children (7-8 years old), 60 older children (10-11 years old), and 60 young adults (18-25 years old) performed a conjunctive visual search task (15 per group in each experiment). The number of distractors of each feature type was unbalanced across displays to evaluate participants' ability to restrict search to the smaller subset of features. The use of top-down attention processes to restrict search was encouraged by providing external aids for identifying and maintaining attention on the smaller set. In Experiment 1, no external assistance was provided. In Experiment 2, precues and instructions were provided to focus attention on that subset. In Experiment 3, trials in which the smaller subset was represented by the same feature were presented in alternating blocks to eliminate the need to switch attention between features from trial to trial. In Experiment 4, consecutive blocks of the same subset features were presented in the first or second half of the experiment, providing additional consistency. All groups benefited from external support of top-down attention, although the pattern of improvement varied across experiments. The younger children benefited most from precues and instruction, using the subset search strategy when instructed. Furthermore, younger children benefited from blocking trials only when blocks of the same features did not alternate. Older participants benefited from the blocking of trials in both Experiments 3 and 4, but not from precues and instructions. Hence, our results revealed both malleability and limits of children's top-down control of attention.

  10. Top-down modulation on perceptual decision with balanced inhibition through feedforward and feedback inhibitory neurons.

    Directory of Open Access Journals (Sweden)

    Cheng-Te Wang

    Full Text Available Recent physiological studies have shown that neurons in various regions of the central nervous systems continuously receive noisy excitatory and inhibitory synaptic inputs in a balanced and covaried fashion. While this balanced synaptic input (BSI is typically described in terms of maintaining the stability of neural circuits, a number of experimental and theoretical studies have suggested that BSI plays a proactive role in brain functions such as top-down modulation for executive control. Two issues have remained unclear in this picture. First, given the noisy nature of neuronal activities in neural circuits, how do the modulatory effects change if the top-down control implements BSI with different ratios between inhibition and excitation? Second, how is a top-down BSI realized via only excitatory long-range projections in the neocortex? To address the first issue, we systematically tested how the inhibition/excitation ratio affects the accuracy and reaction times of a spiking neural circuit model of perceptual decision. We defined an energy function to characterize the network dynamics, and found that different ratios modulate the energy function of the circuit differently and form two distinct functional modes. To address the second issue, we tested BSI with long-distance projection to inhibitory neurons that are either feedforward or feedback, depending on whether these inhibitory neurons do or do not receive inputs from local excitatory cells, respectively. We found that BSI occurs in both cases. Furthermore, when relying on feedback inhibitory neurons, through the recurrent interactions inside the circuit, BSI dynamically and automatically speeds up the decision by gradually reducing its inhibitory component in the course of a trial when a decision process takes too long.

  11. Top-down modulation on perceptual decision with balanced inhibition through feedforward and feedback inhibitory neurons.

    Science.gov (United States)

    Wang, Cheng-Te; Lee, Chung-Ting; Wang, Xiao-Jing; Lo, Chung-Chuan

    2013-01-01

    Recent physiological studies have shown that neurons in various regions of the central nervous systems continuously receive noisy excitatory and inhibitory synaptic inputs in a balanced and covaried fashion. While this balanced synaptic input (BSI) is typically described in terms of maintaining the stability of neural circuits, a number of experimental and theoretical studies have suggested that BSI plays a proactive role in brain functions such as top-down modulation for executive control. Two issues have remained unclear in this picture. First, given the noisy nature of neuronal activities in neural circuits, how do the modulatory effects change if the top-down control implements BSI with different ratios between inhibition and excitation? Second, how is a top-down BSI realized via only excitatory long-range projections in the neocortex? To address the first issue, we systematically tested how the inhibition/excitation ratio affects the accuracy and reaction times of a spiking neural circuit model of perceptual decision. We defined an energy function to characterize the network dynamics, and found that different ratios modulate the energy function of the circuit differently and form two distinct functional modes. To address the second issue, we tested BSI with long-distance projection to inhibitory neurons that are either feedforward or feedback, depending on whether these inhibitory neurons do or do not receive inputs from local excitatory cells, respectively. We found that BSI occurs in both cases. Furthermore, when relying on feedback inhibitory neurons, through the recurrent interactions inside the circuit, BSI dynamically and automatically speeds up the decision by gradually reducing its inhibitory component in the course of a trial when a decision process takes too long.

  12. Top-down modulation of human early visual cortex after stimulus offset supports successful postcued report.

    Science.gov (United States)

    Sergent, Claire; Ruff, Christian C; Barbot, Antoine; Driver, Jon; Rees, Geraint

    2011-08-01

    Modulations of sensory processing in early visual areas are thought to play an important role in conscious perception. To date, most empirical studies focused on effects occurring before or during visual presentation. By contrast, several emerging theories postulate that sensory processing and conscious visual perception may also crucially depend on late top-down influences, potentially arising after a visual display. To provide a direct test of this, we performed an fMRI study using a postcued report procedure. The ability to report a target at a specific spatial location in a visual display can be enhanced behaviorally by symbolic auditory postcues presented shortly after that display. Here we showed that such auditory postcues can enhance target-specific signals in early human visual cortex (V1 and V2). For postcues presented 200 msec after stimulus termination, this target-specific enhancement in visual cortex was specifically associated with correct conscious report. The strength of this modulation predicted individual levels of performance in behavior. By contrast, although later postcues presented 1000 msec after stimulus termination had some impact on activity in early visual cortex, this modulation no longer related to conscious report. These results demonstrate that within a critical time window of a few hundred milliseconds after a visual stimulus has disappeared, successful conscious report of that stimulus still relates to the strength of top-down modulation in early visual cortex. We suggest that, within this critical time window, sensory representation of a visual stimulus is still under construction and so can still be flexibly influenced by top-down modulatory processes.

  13. Network model of top-down influences on local gain and contextual interactions in visual cortex.

    Science.gov (United States)

    Piëch, Valentin; Li, Wu; Reeke, George N; Gilbert, Charles D

    2013-10-22

    The visual system uses continuity as a cue for grouping oriented line segments that define object boundaries in complex visual scenes. Many studies support the idea that long-range intrinsic horizontal connections in early visual cortex contribute to this grouping. Top-down influences in primary visual cortex (V1) play an important role in the processes of contour integration and perceptual saliency, with contour-related responses being task dependent. This suggests an interaction between recurrent inputs to V1 and intrinsic connections within V1 that enables V1 neurons to respond differently under different conditions. We created a network model that simulates parametrically the control of local gain by hypothetical top-down modification of local recurrence. These local gain changes, as a consequence of network dynamics in our model, enable modulation of contextual interactions in a task-dependent manner. Our model displays contour-related facilitation of neuronal responses and differential foreground vs. background responses over the neuronal ensemble, accounting for the perceptual pop-out of salient contours. It quantitatively reproduces the results of single-unit recording experiments in V1, highlighting salient contours and replicating the time course of contextual influences. We show by means of phase-plane analysis that the model operates stably even in the presence of large inputs. Our model shows how a simple form of top-down modulation of the effective connectivity of intrinsic cortical connections among biophysically realistic neurons can account for some of the response changes seen in perceptual learning and task switching.

  14. Perceptual learning to reduce sensory eye dominance beyond the focus of top-down visual attention.

    Science.gov (United States)

    Xu, Jingping P; He, Zijiang J; Ooi, Teng Leng

    2012-05-15

    Perceptual learning is an important means for the brain to maintain its agility in a dynamic environment. Top-down focal attention, which selects task-relevant stimuli against competing ones in the background, is known to control and select what is learned in adults. Still unknown, is whether the adult brain is able to learn highly visible information beyond the focus of top-down attention. If it is, we should be able to reveal a purely stimulus-driven perceptual learning occurring in functions that are largely determined by the early cortical level, where top-down attention modulation is weak. Such an automatic, stimulus-driven learning mechanism is commonly assumed to operate only in the juvenile brain. We performed perceptual training to reduce sensory eye dominance (SED), a function that taps on the eye-of-origin information represented in the early visual cortex. Two retinal locations were simultaneously stimulated with suprathreshold, dichoptic orthogonal gratings. At each location, monocular cueing triggered perception of the grating images of the weak eye and suppression of the strong eye. Observers attended only to one location and performed orientation discrimination of the gratings seen by the weak eye, while ignoring the highly visible gratings at the second, unattended, location. We found SED was not only reduced at the attended location, but also at the unattended location. Furthermore, other untrained visual functions mediated by higher cortical levels improved. An automatic, stimulus-driven learning mechanism causes synaptic alterations in the early cortical level, with a far-reaching impact on the later cortical levels. Copyright © 2011 Elsevier Ltd. All rights reserved.

  15. Rapid evolution leads to differential population dynamics and top-down control in resurrected Daphnia populations.

    Science.gov (United States)

    Goitom, Eyerusalem; Kilsdonk, Laurens J; Brans, Kristien; Jansen, Mieke; Lemmens, Pieter; De Meester, Luc

    2018-01-01

    There is growing evidence of rapid genetic adaptation of natural populations to environmental change, opening the perspective that evolutionary trait change may subsequently impact ecological processes such as population dynamics, community composition, and ecosystem functioning. To study such eco-evolutionary feedbacks in natural populations, however, requires samples across time. Here, we capitalize on a resurrection ecology study that documented rapid and adaptive evolution in a natural population of the water flea Daphnia magna in response to strong changes in predation pressure by fish, and carry out a follow-up mesocosm experiment to test whether the observed genetic changes influence population dynamics and top-down control of phytoplankton. We inoculated populations of the water flea D. magna derived from three time periods of the same natural population known to have genetically adapted to changes in predation pressure in replicate mesocosms and monitored both Daphnia population densities and phytoplankton biomass in the presence and absence of fish. Our results revealed differences in population dynamics and top-down control of algae between mesocosms harboring populations from the time period before, during, and after a peak in fish predation pressure caused by human fish stocking. The differences, however, deviated from our a priori expectations. An S-map approach on time series revealed that the interactions between adults and juveniles strongly impacted the dynamics of populations and their top-down control on algae in the mesocosms, and that the strength of these interactions was modulated by rapid evolution as it occurred in nature. Our study provides an example of an evolutionary response that fundamentally alters the processes structuring population dynamics and impacts ecosystem features.

  16. How can physics underlie the mind? top-down causation in the human context

    CERN Document Server

    Ellis, George

    2016-01-01

    Physics underlies all complexity, including our own existence: how is this possible? How can our own lives emerge from interactions of electrons, protons, and neutrons? This book considers the interaction of physical and non-physical causation in complex systems such as living beings, and in particular in the human brain, relating this to the emergence of higher levels of complexity with real causal powers. In particular it explores the idea of top-down causation, which is the key effect allowing the emergence of true complexity and also enables the causal efficacy of non-physical entities, including the value of money, social conventions, and ethical choices.

  17. Gauging the ungauged basin: a top-down approach in a large semiarid watershed in China

    Directory of Open Access Journals (Sweden)

    F. K. Barthold

    2008-06-01

    Full Text Available A major research challenge in ungauged basins is to quickly assess the dominant hydrological processes of watersheds. In this paper we present a top-down approach from first field reconnaissance to perceptual model development, model conceptualization, evaluation, rejection and eventually, to a more substantial field campaign to build upon the initial modeling. This approach led us from an initial state where very little was known about catchment behavior towards a more complete view of catchment hydrological processes, including the preliminary identification of water sources and an assessment of the effectiveness of our sampling design.

  18. Study on Top-Down Estimation Method of Software Project Planning

    Institute of Scientific and Technical Information of China (English)

    ZHANG Jun-guang; L(U) Ting-jie; ZHAO Yu-mei

    2006-01-01

    This paper studies a new software project planning method under some actual project data in order to make software project plans more effective. From the perspective of system theory, our new method regards a software project plan as an associative unit for study. During a top-down estimation of a software project, Program Evaluation and Review Technique (PERT) method and analogy method are combined to estimate its size, then effort estimation and specific schedules are obtained according to distributions of the phase effort. This allows a set of practical and feasible planning methods to be constructed. Actual data indicate that this set of methods can lead to effective software project planning.

  19. What to measure next to improve decision making? On top-down task driven feature saliency

    DEFF Research Database (Denmark)

    Hansen, Lars Kai; Karadogan, Seliz; Marchegiani, Letizia

    2011-01-01

    Top-down attention is modeled as decision making based on incomplete information. We consider decisions made in a sequential measurement situation where initially only an incomplete input feature vector is available, however, where we are given the possibility to acquire additional input values...... among the missing features. The procecure thus poses the question what to do next? We take an information theoretical approach implemented for generality in a generative mixture model. The framework allows us reduce the decision about what to measure next in a classification problem to the estimation...

  20. Supervisor Localization: A Top-Down Approach to Distributed Control of Discrete-Event Systems

    International Nuclear Information System (INIS)

    Cai, K.; Wonham, W. M.

    2009-01-01

    A purely distributed control paradigm is proposed for discrete-event systems (DES). In contrast to control by one or more external supervisors, distributed control aims to design built-in strategies for individual agents. First a distributed optimal nonblocking control problem is formulated. To solve it, a top-down localization procedure is developed which systematically decomposes an external supervisor into local controllers while preserving optimality and nonblockingness. An efficient localization algorithm is provided to carry out the computation, and an automated guided vehicles (AGV) example presented for illustration. Finally, the 'easiest' and 'hardest' boundary cases of localization are discussed.

  1. Top down arsenic uncertainty measurement in water and sediments from Guarapiranga dam (Brazil)

    Science.gov (United States)

    Faustino, M. G.; Lange, C. N.; Monteiro, L. R.; Furusawa, H. A.; Marques, J. R.; Stellato, T. B.; Soares, S. M. V.; da Silva, T. B. S. C.; da Silva, D. B.; Cotrim, M. E. B.; Pires, M. A. F.

    2018-03-01

    Total arsenic measurements assessment regarding legal threshold demands more than average and standard deviation approach. In this way, analytical measurement uncertainty evaluation was conducted in order to comply with legal requirements and to allow the balance of arsenic in both water and sediment compartments. A top-down approach for measurement uncertainties was applied to evaluate arsenic concentrations in water and sediments from Guarapiranga dam (São Paulo, Brazil). Laboratory quality control and arsenic interlaboratory tests data were used in this approach to estimate the uncertainties associated with the methodology.

  2. Top-down approach for nanophase reconstruction in bulk heterojunction solar cells.

    Science.gov (United States)

    Kong, Jaemin; Hwang, In-Wook; Lee, Kwanghee

    2014-09-01

    "Top-Down" nanophase reconstruction via a post-additive soaking process is first presented with various BHJ binary composites. By simply rinsing as-cast BHJ films with a solvent mixture containing a few traces of a nanophase-control reagent such as 1,8-diiodooctane, oversized fullerene-rich clusters (>100 nm in dia-meter) in the BHJ film are instataneously disassembled and entirely reorganized into finely intermixed donor/acceptor nanophases (ca. 10 nm) with a 3D compositional homogeneity, without surface segregation. © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  3. PTSD symptom severity is associated with increased recruitment of top-down attentional control in a trauma-exposed sample

    OpenAIRE

    White, Stuart F.; Costanzo, Michelle E.; Blair, James R.; Roy, Michael J.

    2015-01-01

    Background: Recent neuroimaging work suggests that increased amygdala responses to emotional stimuli and dysfunction within regions mediating top down attentional control (dorsomedial frontal, lateral frontal and parietal cortices) may be associated with the emergence of anxiety disorders, including posttraumatic stress disorder (PTSD). This report examines amygdala responsiveness to emotional stimuli and the recruitment of top down attention systems as a function of task demands in a populat...

  4. Scaling up from the grassroots and the top down: The impacts of multi-level governance on community forestry in Durango, Mexico

    Directory of Open Access Journals (Sweden)

    Gustavo A García-López

    2013-08-01

    Full Text Available This paper analyzes the local-level impacts of cross-scale linkages in Mexican community forestry by evaluating the operation of four inter-community forest associations (FAs. Based on one year of fieldwork in Durango, Mexico, the paper focuses on two inter-related issues: (1 the services that each association provides to their member communities and how they impact forest management and the development of communities’ forestry enterprises, and (2 the differences in services and impacts between top-down and bottom-up FAs. The findings show that FAs, as a form of cross-scale linkage, can be crucial for the provision of services, goods and infrastructure related to the protection and enhancement of community forests, the economic development of community enterprises, and the political representation of these communities. At the same time, the study finds important differences between top-down and bottom-up FAs, while pointing to some of the disadvantages of each type of linkage.

  5. What are the fluxes of greenhouse gases from the greater Los Angeles area as inferred from top-down remote sensing studies?

    Science.gov (United States)

    Hedelius, J.; Wennberg, P. O.; Wunch, D.; Roehl, C. M.; Podolske, J. R.; Hillyard, P.; Iraci, L. T.

    2017-12-01

    Greenhouse gas (GHG) emissions from California's South Coast Air Basin (SoCAB) have been studied extensively using a variety of tower, aircraft, remote sensing, emission inventory, and modeling studies. It is impractical to survey GHG fluxes from all urban areas and hot-spots to the extent the SoCAB has been studied, but it can serve as a test location for scaling methods globally. We use a combination of remote sensing measurements from ground (Total Carbon Column Observing Network, TCCON) and space-based (Observing Carbon Observatory-2, OCO-2) sensors in an inversion to obtain the carbon dioxide flux from the SoCAB. We also perform a variety of sensitivity tests to see how the inversion performs using different model parameterizations. Fluxes do not significantly depend on the mixed layer depth, but are sensitive to the model surface layers (top-down than bottom-up fluxes highlight the need for additional work on both approaches. Higher top-down fluxes could arise from sampling bias, model bias, or may show bottom-up values underestimate sources. Lessons learned here may help in scaling up inversions to hundreds of urban systems using space-based observations.

  6. The Impact of Top-Down Prediction on Emotional Face Processing in Social Anxiety

    Directory of Open Access Journals (Sweden)

    Guangming Ran

    2017-07-01

    Full Text Available There is evidence that people with social anxiety show abnormal processing of emotional faces. To investigate the impact of top-down prediction on emotional face processing in social anxiety, brain responses of participants with high and low social anxiety (LSA were recorded, while they performed a variation of the emotional task, using high temporal resolution event-related potential techniques. Behaviorally, we reported an effect of prediction with higher accuracy for predictable than unpredictable faces. Furthermore, we found that participants with high social anxiety (HSA, but not with LSA, recognized angry faces more accurately than happy faces. For the P100 and P200 components, HSA participants showed enhanced brain activity for angry faces compared to happy faces, suggesting a hypervigilance to angry faces. Importantly, HSA participants exhibited larger N170 amplitudes in the right hemisphere electrodes than LSA participants when they observed unpredictable angry faces, but not when the angry faces were predictable. This probably reflects the top-down prediction improving the deficiency at building a holistic face representation in HSA participants.

  7. Investigating emotional top down modulation of ambiguous faces by single pulse TMS on early visual cortices

    Directory of Open Access Journals (Sweden)

    Zachary Adam Yaple

    2016-06-01

    Full Text Available Top-down processing is a mechanism in which memory, context and expectation are used to perceive stimuli. For this study we investigated how emotion content, induced by music mood, influences perception of happy and sad emoticons. Using single pulse TMS we stimulated right occipital face area (rOFA, primary visual cortex (V1 and vertex while subjects performed a face-detection task and listened to happy and sad music. At baseline, incongruent audio-visual pairings decreased performance, demonstrating dependence of emotion while perceiving ambiguous faces. However, performance of face identification decreased during rOFA stimulation regardless of emotional content. No effects were found between Cz and V1 stimulation. These results suggest that while rOFA is important for processing faces regardless of emotion, V1 stimulation had no effect. Our findings suggest that early visual cortex activity may not integrate emotional auditory information with visual information during emotion top-down modulation of faces.

  8. Dietary self-control influences top-down guidance of attention to food cues.

    Science.gov (United States)

    Higgs, Suzanne; Dolmans, Dirk; Humphreys, Glyn W; Rutters, Femke

    2015-01-01

    Motivational objects attract attention due to their rewarding properties, but less is known about the role that top-down cognitive processes play in the attention paid to motivationally relevant objects and how this is affected by relevant behavioral traits. Here we assess how thinking about food affects attentional guidance to food items and how this is modulated by traits relating to dietary self-control. Participants completed two tasks in which they were presented with an initial cue (food or non-food) to either hold in working memory (memory task) or to merely attend to (priming task). Holding food items in working memory strongly affected attention when the memorized cue re-appeared in the search display. Tendency towards disinhibited eating was associated with greater attention to food versus non-food pictures in both the priming and working memory tasks, consistent with greater attention to food cues per se. Successful dieters, defined as those high in dietary restraint and low in tendency to disinhibition, showed reduced attention to food when holding food-related information in working memory. These data suggest a strong top-down effect of thinking about food on attention to food items and indicate that the suppression of food items in working memory could be a marker of dieting success.

  9. Top-down modulation in human visual cortex predicts the stability of a perceptual illusion

    Science.gov (United States)

    Meindertsma, Thomas; Hillebrand, Arjan; van Dijk, Bob W.; Lamme, Victor A. F.; Donner, Tobias H.

    2014-01-01

    Conscious perception sometimes fluctuates strongly, even when the sensory input is constant. For example, in motion-induced blindness (MIB), a salient visual target surrounded by a moving pattern suddenly disappears from perception, only to reappear after some variable time. Whereas such changes of perception result from fluctuations of neural activity, mounting evidence suggests that the perceptual changes, in turn, may also cause modulations of activity in several brain areas, including visual cortex. In this study, we asked whether these latter modulations might affect the subsequent dynamics of perception. We used magnetoencephalography (MEG) to measure modulations in cortical population activity during MIB. We observed a transient, retinotopically widespread modulation of beta (12–30 Hz)-frequency power over visual cortex that was closely linked to the time of subjects' behavioral report of the target disappearance. This beta modulation was a top-down signal, decoupled from both the physical stimulus properties and the motor response but contingent on the behavioral relevance of the perceptual change. Critically, the modulation amplitude predicted the duration of the subsequent target disappearance. We propose that the transformation of the perceptual change into a report triggers a top-down mechanism that stabilizes the newly selected perceptual interpretation. PMID:25411458

  10. Comprehensive analysis of tropomyosin isoforms in skeletal muscles by top-down proteomics.

    Science.gov (United States)

    Jin, Yutong; Peng, Ying; Lin, Ziqing; Chen, Yi-Chen; Wei, Liming; Hacker, Timothy A; Larsson, Lars; Ge, Ying

    2016-04-01

    Mammalian skeletal muscles are heterogeneous in nature and are capable of performing various functions. Tropomyosin (Tpm) is a major component of the thin filament in skeletal muscles and plays an important role in controlling muscle contraction and relaxation. Tpm is known to consist of multiple isoforms resulting from different encoding genes and alternative splicing, along with post-translational modifications. However, a systematic characterization of Tpm isoforms in skeletal muscles is still lacking. Therefore, we employed top-down mass spectrometry (MS) to identify and characterize Tpm isoforms present in different skeletal muscles from multiple species, including swine, rat, and human. Our study revealed that Tpm1.1 and Tpm2.2 are the two major Tpm isoforms in swine and rat skeletal muscles, whereas Tpm1.1, Tpm2.2, and Tpm3.12 are present in human skeletal muscles. Tandem MS was utilized to identify the sequences of the major Tpm isoforms. Furthermore, quantitative analysis revealed muscle-type specific differences in the abundance of un-modified and modified Tpm isoforms in rat and human skeletal muscles. This study represents the first systematic investigation of Tpm isoforms in skeletal muscles, which not only demonstrates the capabilities of top-down MS for the comprehensive characterization of skeletal myofilament proteins but also provides the basis for further studies on these Tpm isoforms in muscle-related diseases.

  11. Chronic alcohol exposure disrupts top-down control over basal ganglia action selection to produce habits.

    Science.gov (United States)

    Renteria, Rafael; Baltz, Emily T; Gremel, Christina M

    2018-01-15

    Addiction involves a predominance of habitual control mediated through action selection processes in dorsal striatum. Research has largely focused on neural mechanisms mediating a proposed progression from ventral to dorsal lateral striatal control in addiction. However, over reliance on habit striatal processes may also arise from reduced cortical input to striatum, thereby disrupting executive control over action selection. Here, we identify novel mechanisms through which chronic intermittent ethanol exposure and withdrawal (CIE) disrupts top-down control over goal-directed action selection processes to produce habits. We find CIE results in decreased excitability of orbital frontal cortex (OFC) excitatory circuits supporting goal-directed control, and, strikingly, selectively reduces OFC output to the direct output pathway in dorsal medial striatum. Increasing the activity of OFC circuits restores goal-directed control in CIE-exposed mice. Our findings show habitual control in alcohol dependence can arise through disrupted communication between top-down, goal-directed processes onto basal ganglia pathways controlling action selection.

  12. Top-down beta rhythms support selective attention via interlaminar interaction: a model.

    Directory of Open Access Journals (Sweden)

    Jung H Lee

    Full Text Available Cortical rhythms have been thought to play crucial roles in our cognitive abilities. Rhythmic activity in the beta frequency band, around 20 Hz, has been reported in recent studies that focused on neural correlates of attention, indicating that top-down beta rhythms, generated in higher cognitive areas and delivered to earlier sensory areas, can support attentional gain modulation. To elucidate functional roles of beta rhythms and underlying mechanisms, we built a computational model of sensory cortical areas. Our simulation results show that top-down beta rhythms can activate ascending synaptic projections from L5 to L4 and L2/3, responsible for biased competition in superficial layers. In the simulation, slow-inhibitory interneurons are shown to resonate to the 20 Hz input and modulate the activity in superficial layers in an attention-related manner. The predicted critical roles of these cells in attentional gain provide a potential mechanism by which cholinergic drive can support selective attention.

  13. Enhanced visual awareness for morality and pajamas? Perception vs. memory in 'top-down' effects.

    Science.gov (United States)

    Firestone, Chaz; Scholl, Brian J

    2015-03-01

    A raft of prominent findings has revived the notion that higher-level cognitive factors such as desire, meaning, and moral relevance can directly affect what we see. For example, under conditions of brief presentation, morally relevant words reportedly "pop out" and are easier to identify than morally irrelevant words. Though such results purport to show that perception itself is sensitive to such factors, much of this research instead demonstrates effects on visual recognition--which necessarily involves not only visual processing per se, but also memory retrieval. Here we report three experiments which suggest that many alleged top-down effects of this sort are actually effects on 'back-end' memory rather than 'front-end' perception. In particular, the same methods used to demonstrate popout effects for supposedly privileged stimuli (such as morality-related words, e.g. "punishment" and "victim") also yield popout effects for unmotivated, superficial categories (such as fashion-related words, e.g. "pajamas" and "stiletto"). We conclude that such effects reduce to well-known memory processes (in this case, semantic priming) that do not involve morality, and have no implications for debates about whether higher-level factors influence perception. These case studies illustrate how it is critical to distinguish perception from memory in alleged 'top-down' effects. Copyright © 2014 Elsevier B.V. All rights reserved.

  14. Playing shooter and driving videogames improves top-down guidance in visual search.

    Science.gov (United States)

    Wu, Sijing; Spence, Ian

    2013-05-01

    Playing action videogames is known to improve visual spatial attention and related skills. Here, we showed that playing action videogames also improves classic visual search, as well as the ability to locate targets in a dual search that mimics certain aspects of an action videogame. In Experiment 1A, first-person shooter (FPS) videogame players were faster than nonplayers in both feature search and conjunction search, and in Experiment 1B, they were faster and more accurate in a peripheral search and identification task while simultaneously performing a central search. In Experiment 2, we showed that 10 h of play could improve the performance of nonplayers on each of these tasks. Three different genres of videogames were used for training: two action games and a 3-D puzzle game. Participants who played an action game (either an FPS or a driving game) achieved greater gains on all search tasks than did those who trained using the puzzle game. Feature searches were faster after playing an action videogame, suggesting that players developed a better target template to guide search in a top-down manner. The results of the dual search suggest that, in addition to enhancing the ability to divide attention, playing an action game improves the top-down guidance of attention to possible target locations. The results have practical implications for the development of training tools to improve perceptual and cognitive skills.

  15. Depression and anxious apprehension distinguish frontocingulate cortical activity during top-down attentional control.

    Science.gov (United States)

    Silton, Rebecca Levin; Heller, Wendy; Engels, Anna S; Towers, David N; Spielberg, Jeffrey M; Edgar, J Christopher; Sass, Sarah M; Stewart, Jennifer L; Sutton, Bradley P; Banich, Marie T; Miller, Gregory A

    2011-05-01

    A network consisting of left dorsolateral prefrontal cortex (LDLPFC) and dorsal anterior cingulate cortex (dACC) has been implicated in top-down attentional control. Few studies have systematically investigated how this network is altered in psychopathology, despite evidence that depression and anxiety are associated with attentional control impairments. Functional MRI and dense-array event-related brain potential (ERP) data were collected in separate sessions from 100 participants during a color-word Stroop task. Functional MRI results guided ERP source modeling to characterize the time course of activity in LDLPFC (300-440 ms) and dACC (520-680 ms). At low levels of depression, LDLPFC activity was indirectly related to Stroop interference and only via dACC activity. In contrast, at high levels of depression, dACC did not play an intervening role, and increased LDLPFC activity was directly related to decreased Stroop interference. Specific to high levels of anxious apprehension, higher dACC activity was related to more Stroop interference. Results indicate that depression and anxious apprehension modulate temporally and functionally distinct aspects of the frontocingulate network involved in top-down attention control.

  16. A Routine 'Top-Down' Approach to Analysis of the Human Serum Proteome.

    Science.gov (United States)

    D'Silva, Arlene M; Hyett, Jon A; Coorssen, Jens R

    2017-06-06

    Serum provides a rich source of potential biomarker proteoforms. One of the major obstacles in analysing serum proteomes is detecting lower abundance proteins owing to the presence of hyper-abundant species (e.g., serum albumin and immunoglobulins). Although depletion methods have been used to address this, these can lead to the concomitant removal of non-targeted protein species, and thus raise issues of specificity, reproducibility, and the capacity for meaningful quantitative analyses. Altering the native stoichiometry of the proteome components may thus yield a more complex series of issues than dealing directly with the inherent complexity of the sample. Hence, here we targeted method refinements so as to ensure optimum resolution of serum proteomes via a top down two-dimensional gel electrophoresis (2DE) approach that enables the routine assessment of proteoforms and is fully compatible with subsequent mass spectrometric analyses. Testing included various fractionation and non-fractionation approaches. The data show that resolving 500 µg protein on 17 cm 3-10 non-linear immobilised pH gradient strips in the first dimension followed by second dimension resolution on 7-20% gradient gels with a combination of lithium dodecyl sulfate (LDS) and sodium dodecyl sulfate (SDS) detergents markedly improves the resolution and detection of proteoforms in serum. In addition, well established third dimension electrophoretic separations in combination with deep imaging further contributed to the best available resolution, detection, and thus quantitative top-down analysis of serum proteomes.

  17. Dietary self-control influences top-down guidance of attention to food cues

    Directory of Open Access Journals (Sweden)

    Suzanne eHiggs

    2015-04-01

    Full Text Available Motivational objects attract attention due to their rewarding properties, but less is known about the role that top-down cognitive processes play in the attention paid to motivationally relevant objects and how this is affected by relevant behaviour traits. Here we assess how thinking about food affects attentional guidance to food items and how this is modulated by traits relating to dietary self-control. Participants completed two tasks in which they were presented with an initial cue (food or non-food to either hold in working memory (memory task or to merely attend to (priming task. Holding food items in working memory strongly affected attention when the memorized cue re-appeared in the search display. Tendency towards disinhibited eating was associated with greater attention to food versus non-food pictures in both the priming and working memory tasks, consistent with greater attention to food cues per se. Successful dieters, defined as those high in dietary restraint and low in tendency to disinhibition, showed reduced attention to food when holding food-related information in working memory. These data suggest a strong top-down effect of thinking about food on attention to food items and indicate that the suppression of food items in working memory could be a marker of dieting success.

  18. Neurophysiological bases of exponential sensory decay and top-down memory retrieval: a model.

    Science.gov (United States)

    Zylberberg, Ariel; Dehaene, Stanislas; Mindlin, Gabriel B; Sigman, Mariano

    2009-01-01

    Behavioral observations suggest that multiple sensory elements can be maintained for a short time, forming a perceptual buffer which fades after a few hundred milliseconds. Only a subset of this perceptual buffer can be accessed under top-down control and broadcasted to working memory and consciousness. In turn, single-cell studies in awake-behaving monkeys have identified two distinct waves of response to a sensory stimulus: a first transient response largely determined by stimulus properties and a second wave dependent on behavioral relevance, context and learning. Here we propose a simple biophysical scheme which bridges these observations and establishes concrete predictions for neurophsyiological experiments in which the temporal interval between stimulus presentation and top-down allocation is controlled experimentally. Inspired in single-cell observations, the model involves a first transient response and a second stage of amplification and retrieval, which are implemented biophysically by distinct operational modes of the same circuit, regulated by external currents. We explicitly investigated the neuronal dynamics, the memory trace of a presented stimulus and the probability of correct retrieval, when these two stages were bracketed by a temporal gap. The model predicts correctly the dependence of performance with response times in interference experiments suggesting that sensory buffering does not require a specific dedicated mechanism and establishing a direct link between biophysical manipulations and behavioral observations leading to concrete predictions.

  19. Neurophysiological bases of exponential sensory decay and top-down memory retrieval: a model

    Directory of Open Access Journals (Sweden)

    Ariel Zylberberg

    2009-03-01

    Full Text Available Behavioral observations suggest that multiple sensory elements can be maintained for a short time, forming a perceptual buffer which fades after a few hundred milliseconds. Only a subset of this perceptual buffer can be accessed under top-down control and broadcasted to working memory and consciousness. In turn, single-cell studies in awake-behaving monkeys have identified two distinct waves of response to a sensory stimulus: a first transient response largely determined by stimulus properties and a second wave dependent on behavioral relevance, context and learning. Here we propose a simple biophysical scheme which bridges these observations and establishes concrete predictions for neurophsyiological experiments in which the temporal interval between stimulus presentation and top-down allocation is controlled experimentally. Inspired in single-cell observations, the model involves a first transient response and a second stage of amplification and retrieval, which are implemented biophysically by distinct operational modes of the same circuit, regulated by external currents. We explicitly investigated the neuronal dynamics, the memory trace of a presented stimulus and the probability of correct retrieval, when these two stages were bracketed by a temporal gap. The model predicts correctly the dependence of performance with response times in interference experiments suggesting that sensory buffering does not require a specific dedicated mechanism and establishing a direct link between biophysical manipulations and behavioral observations leading to concrete predictions.

  20. Electrochemistry-assisted top-down characterization of disulfide-containing proteins.

    Science.gov (United States)

    Zhang, Yun; Cui, Weidong; Zhang, Hao; Dewald, Howard D; Chen, Hao

    2012-04-17

    Covalent disulfide bond linkage in a protein represents an important challenge for mass spectrometry (MS)-based top-down protein structure analysis as it reduces the backbone cleavage efficiency for MS/MS dissociation. This study presents a strategy for solving this critical issue via integrating electrochemistry (EC) online with a top-down MS approach. In this approach, proteins undergo electrolytic reduction in an electrochemical cell to break disulfide bonds and then undergo online ionization into gaseous ions for analysis by electron-capture dissociation (ECD) and collision-induced dissociation (CID). The electrochemical reduction of proteins allows one to remove disulfide bond constraints and also leads to increased charge numbers of the resulting protein ions. As a result, sequence coverage was significantly enhanced, as exemplified by β-lactoglobulin A (24 vs 75 backbone cleavages before and after electrolytic reduction, respectively) and lysozyme (5 vs 66 backbone cleavages before and after electrolytic reduction, respectively). This methodology is fast and does not need chemical reductants, which would have an important impact in high-throughput proteomics research.

  1. Top-down proteomics reveals a unique protein S-thiolation switch in Salmonella Typimurium in response to infection-like conditions

    Energy Technology Data Exchange (ETDEWEB)

    Ansong, Charles; Wu, Si; Meng, Da; Liu, Xiaowen; Brewer, Heather M.; Kaiser, Brooke LD; Nakayasu, Ernesto S.; Cort, John R.; Pevzner, Pavel A.; Smith, Richard D.; Heffron, Fred; Adkins, Joshua N.; Pasa-Tolic, Ljiljana

    2013-06-18

    Characterization of the mature protein complement in cells is crucial for a better understanding of cellular processes on a systems-wide scale. Bottom-up proteomic approaches often lead to loss of critical information about an endogenous protein’s actual state due to post translational modifications (PTMs) and other processes. Top-down approaches that involve analysis of the intact protein can address this concern but present significant analytical challenges related to the separation quality needed, measurement sensitivity, and speed that result in low throughput and limited coverage. Here we used single-dimension ultra high pressure liquid chromatography mass spectrometry to investigate the comprehensive ‘intact’ proteome of the Gram negative bacterial pathogen Salmonella Typhimurium. Top-down proteomics analysis revealed 563 unique proteins including 1665 proteoforms generated by PTMs, representing the largest microbial top-down dataset reported to date. Our analysis not only confirmed several previously recognized aspects of Salmonella biology and bacterial PTMs in general, but also revealed several novel biological insights. Of particular interest was differential utilization of the protein S-thiolation forms S-glutathionylation and S-cysteinylation in response to infection-like conditions versus basal conditions, which was corroborated by changes in corresponding biosynthetic pathways. This differential utilization highlights underlying metabolic mechanisms that modulate changes in cellular signaling, and represents to our knowledge the first report of S-cysteinylation in Gram negative bacteria. The demonstrated utility of our simple proteome-wide intact protein level measurement strategy for gaining biological insight should promote broader adoption and applications of top-down proteomics approaches.

  2. Predators with multiple ontogenetic niche shifts have limited potential for population growth and top-down control of their prey

    NARCIS (Netherlands)

    van Leeuwen, A.; Huss, M.; Gårdmark, A.; Casini, M.; Vitale, F.; Hjelm, J.; Persson, L.; de Roos, A.M.

    2013-01-01

    Catastrophic collapses of top predators have revealed trophic cascades and community structuring by top-down control. When populations fail to recover after a collapse, this may indicate alternative stable states in the system. Overfishing has caused several of the most compelling cases of these

  3. Flavour physics beyond the standard model in top and bottom quarks

    International Nuclear Information System (INIS)

    Stamou, Emmanuel

    2013-01-01

    The Large Hadron Collider is currently exploring dynamics at high energies where we expect physics beyond the standard model to emerge as an answer to at least some of the questions the standard model cannot address. We consider the low-energy flavour signatures of a model with a dynamical explanation of quark masses and mixings, construct a model with new strong interactions that account for the anomalously large measurement of an asymmetry in top antitop production at Tevatron, and compute next-to-leading-order electroweak corrections to the recently observed rare decay B s →μ + μ - .

  4. Prey vulnerability limits top-down control and alters reciprocal feedbacks in a subsidized model food web.

    Directory of Open Access Journals (Sweden)

    William I Atlas

    Full Text Available Resource subsidies increase the productivity of recipient food webs and can affect ecosystem dynamics. Subsidies of prey often support elevated predator biomass which may intensify top-down control and reduce the flow of reciprocal subsidies into adjacent ecosystems. However, top-down control in subsidized food webs may be limited if primary consumers posses morphological or behavioral traits that limit vulnerability to predation. In forested streams, terrestrial prey support high predator biomass creating the potential for strong top-down control, however armored primary consumers often dominate the invertebrate assemblage. Using empirically based simulation models, we tested the response of stream food webs to variations in subsidy magnitude, prey vulnerability, and the presence of two top predators. While terrestrial prey inputs increased predator biomass (+12%, the presence of armored primary consumers inhibited top-down control, and diverted most aquatic energy (∼75% into the riparian forest through aquatic insect emergence. Food webs without armored invertebrates experienced strong trophic cascades, resulting in higher algal (∼50% and detrital (∼1600% biomass, and reduced insect emergence (-90%. These results suggest prey vulnerability can mediate food web responses to subsidies, and that top-down control can be arrested even when predator-invulnerable consumers are uncommon (20% regardless of the level of subsidy.

  5. 'Top, bottom, versatile': narratives of sexual practices in gay relationships in the Cape Metropole, South Africa.

    Science.gov (United States)

    Henderson, Neil John

    2017-07-13

    Sexual practices among gay and other men who have sex with men are evolving in South Africa and heteronormative stereotypes are being contested. This paper draws from a larger qualitative study on how men construct a gay identity and negotiate their relationships within contemporary South African contexts, following constitutional and legal changes, in this respect. A feminist, social constructionist approach was used to collect and analyse data from in-depth interviews with 15 self-identified gay men, aged 20 to 46 years, drawn from a university in the larger Cape Metropole, South Africa. Interviews were audio-recorded, transcribed verbatim and analysed using thematic and narrative analysis. 'Bottoms' revealed being powerful in receptive sex. Other men deconstructed the binaries of masculine/feminine and resisted heteronormativity by engaging in fluid constructions in their relationships, whereby participants 'switched' or 'flipped' or did not recognise stereotypical roles when practising sex. There may be value in making these flexible and reciprocal sexual practices better known about and promoted as non-normative African models of sexual practice.

  6. A seismic performance and cost comparison of top and bottom supported liquid metal reactor vessels

    International Nuclear Information System (INIS)

    Carlson, T.M.; Kiciman, O.K.; Petrozelli, J.F.

    1989-01-01

    It is the premise of this paper that the revision of a pool LMR from a TSRV configuration to a specific bottom supported reactor vessel (BSRV) configuration can resolve the above TSRV disadvantages related to load path length and diversity, thereby improving seismic performance and simultaneously reducing RV block costs by reducing weights. This paper demonstrates this premise by comparing a reference TSRV block with a specific BSRV block design. Recent capital cost estimates ($/kWe) for U.S. liquid metal reactor (LMR) plant designs reveal that the balance of plant costs could be reduced below that of the balance of plant costs for a comparable light water reactor plant. However, in regions of high seismicity, non-seismically isolated LMR nuclear steam supply system weights are costs per kWe are two to three times the weights and costs of light water reactor nuclear steam supply systems. While all portions of the LMR nuclear steam supply system require examination for potential cost reductions, the focus of this paper is the reactor vessel (RV) block for a large pool plant

  7. Top-Down Control of Visual Alpha Oscillations: Sources of Control Signals and Their Mechanisms of Action

    Science.gov (United States)

    Wang, Chao; Rajagovindan, Rajasimhan; Han, Sahng-Min; Ding, Mingzhou

    2016-01-01

    Alpha oscillations (8–12 Hz) are thought to inversely correlate with cortical excitability. Goal-oriented modulation of alpha has been studied extensively. In visual spatial attention, alpha over the region of visual cortex corresponding to the attended location decreases, signifying increased excitability to facilitate the processing of impending stimuli. In contrast, in retention of verbal working memory, alpha over visual cortex increases, signifying decreased excitability to gate out stimulus input to protect the information held online from sensory interference. According to the prevailing model, this goal-oriented biasing of sensory cortex is effected by top-down control signals from frontal and parietal cortices. The present study tests and substantiates this hypothesis by (a) identifying the signals that mediate the top-down biasing influence, (b) examining whether the cortical areas issuing these signals are task-specific or task-independent, and (c) establishing the possible mechanism of the biasing action. High-density human EEG data were recorded in two experimental paradigms: a trial-by-trial cued visual spatial attention task and a modified Sternberg working memory task. Applying Granger causality to both sensor-level and source-level data we report the following findings. In covert visual spatial attention, the regions exerting top-down control over visual activity are lateralized to the right hemisphere, with the dipoles located at the right frontal eye field (FEF) and the right inferior frontal gyrus (IFG) being the main sources of top-down influences. During retention of verbal working memory, the regions exerting top-down control over visual activity are lateralized to the left hemisphere, with the dipoles located at the left middle frontal gyrus (MFG) being the main source of top-down influences. In both experiments, top-down influences are mediated by alpha oscillations, and the biasing effect is likely achieved via an inhibition

  8. Selective Area Sublimation: A Simple Top-down Route for GaN-Based Nanowire Fabrication.

    Science.gov (United States)

    Damilano, B; Vézian, S; Brault, J; Alloing, B; Massies, J

    2016-03-09

    Post-growth in situ partial SiNx masking of GaN-based epitaxial layers grown in a molecular beam epitaxy reactor is used to get GaN selective area sublimation (SAS) by high temperature annealing. Using this top-down approach, nanowires (NWs) with nanometer scale diameter are obtained from GaN and InxGa1-xN/GaN quantum well epitaxial structures. After GaN regrowth on InxGa1-xN/GaN NWs resulting from SAS, InxGa1-xN quantum disks (QDisks) with nanometer sizes in the three dimensions are formed. Low temperature microphotoluminescence experiments demonstrate QDisk multilines photon emission around 3 eV with individual line widths of 1-2 meV.

  9. Supervisor localization a top-down approach to distributed control of discrete-event systems

    CERN Document Server

    Cai, Kai

    2016-01-01

    This monograph presents a systematic top-down approach to distributed control synthesis of discrete-event systems (DES). The approach is called supervisor localization; its essence is the allocation of external supervisory control action to individual component agents as their internal control strategies. The procedure is: first synthesize a monolithic supervisor, to achieve globally optimal and nonblocking controlled behavior, then decompose the monolithic supervisor into local controllers, one for each agent. The collective behavior of the resulting local controllers is identical to that achieved by the monolithic supervisor. The basic localization theory is first presented in the Ramadge–Wonham language-based supervisory control framework, then demonstrated with distributed control examples of multi-robot formations, manufacturing systems, and distributed algorithms. An architectural approach is adopted to apply localization to large-scale DES; this yields a heterarchical localization procedure, which is...

  10. Manipulation of strain state in silicon nanoribbons by top-down approach

    Energy Technology Data Exchange (ETDEWEB)

    Mu, Zhiqiang; Zhang, Miao; Xue, Zhongying; Sun, Gaodi; Guo, Qinglei; Chen, Da; Di, Zengfeng, E-mail: zfdi@mail.sim.ac.cn; Wang, Xi [State Key Laboratory of Functional Materials for Informatics, Shanghai Institute of Microsystem and Information Technology, Chinese Academy of Sciences, Shanghai 200050 (China); Huang, Gaoshan; Mei, Yongfeng [Department of Materials Science, Fudan University, Shanghai 200433 (China); Chu, Paul K. [Department of Physics and Materials Science, City University of Hong Kong, Tat Chee Avenue, Kowloon, Hong Kong (China)

    2015-04-27

    Tensile strain is often utilized to enhance the electron mobility and luminescent characteristics of semiconductors. A top-down approach in conjunction with roll-up technology is adopted to produce high tensile strain in Si nanoribbons by patterning and releasing of the bridge-like structures. The tensile strain can be altered between uniaxial state and biaxial state by adjusting the dimensions of the patterns and can be varied controllably up to 3.2% and 0.9% for the uniaxial- and biaxial-strained Si nanoribbons, respectively. Three-dimensional finite element analysis is performed to investigate the mechanism of strain generation during patterning and releasing of the structure. Since the process mainly depends on the geometrical factors, the technique can be readily extended to other types of mechanical, electrical, and optical membranes.

  11. Top-down approach from satellite to terrestrial rover application for environmental monitoring of landfills.

    Science.gov (United States)

    Manzo, C; Mei, A; Zampetti, E; Bassani, C; Paciucci, L; Manetti, P

    2017-04-15

    This paper describes a methodology to perform chemical analyses in landfill areas by integrating multisource geomatic data. We used a top-down approach to identify Environmental Point of Interest (EPI) based on very high-resolution satellite data (Pleiades and WorldView 2) and on in situ thermal and photogrammetric surveys. Change detection techniques and geostatistical analysis supported the chemical survey, undertaken using an accumulation chamber and an RIIA, an unmanned ground vehicle developed by CNR IIA, equipped with a multiparameter sensor platform for environmental monitoring. Such an approach improves site characterization, identifying the key environmental points of interest where it is necessary to perform detailed chemical analyses. Copyright © 2017 Elsevier B.V. All rights reserved.

  12. A top-down approach to crystal engineering of a racemic Δ2-isoxazoline.

    Science.gov (United States)

    Lombardo, Giuseppe M; Rescifina, Antonio; Chiacchio, Ugo; Bacchi, Alessia; Punzo, Francesco

    2014-02-01

    The crystal structure of racemic dimethyl (4RS,5RS)-3-(4-nitrophenyl)-4,5-dihydroisoxazole-4,5-dicarboxylate, C13H12N2O7, has been determined by single-crystal X-ray diffraction. By analysing the degree of growth of the morphologically important crystal faces, a ranking of the most relevant non-covalent interactions determining the crystal structure can be inferred. The morphological information is considered with an approach opposite to the conventional one: instead of searching inside the structure for the potential key interactions and using them to calculate the crystal habit, the observed crystal morphology is used to define the preferential lines of growth of the crystal, and then this information is interpreted by means of density functional theory (DFT) calculations. Comparison with the X-ray structure confirms the validity of the strategy, thus suggesting this top-down approach to be a useful tool for crystal engineering.

  13. A top-down approach for the prediction of hardness and toughness of hierarchical materials

    International Nuclear Information System (INIS)

    Carpinteri, Alberto; Paggi, Marco

    2009-01-01

    Many natural and man-made materials exhibit structure over more than one length scale. In this paper, we deal with hierarchical grained composite materials that have recently been designed to achieve superior hardness and toughness as compared to their traditional counterparts. Their nested structure, where meso-grains are recursively composed of smaller and smaller micro-grains at the different scales with a fractal-like topology, is herein studied from a hierarchical perspective. Considering a top-down approach, i.e. from the largest to the smallest scale, we propose a recursive micromechanical model coupled with a generalized fractal mixture rule for the prediction of hardness and toughness of a grained material with n hierarchical levels. A relationship between hardness and toughness is also derived and the analytical predictions are compared with experimental data.

  14. Spatial inter-comparison of Top-down emission inventories in European urban areas

    Science.gov (United States)

    Trombetti, Marco; Thunis, Philippe; Bessagnet, Bertrand; Clappier, Alain; Couvidat, Florian; Guevara, Marc; Kuenen, Jeroen; López-Aparicio, Susana

    2018-01-01

    This paper presents an inter-comparison of the main Top-down emission inventories currently used for air quality modelling studies at the European level. The comparison is developed for eleven European cities and compares the distribution of emissions of NOx, SO2, VOC and PPM2.5 from the road transport, residential combustion and industry sectors. The analysis shows that substantial differences in terms of total emissions, sectorial emission shares and spatial distribution exist between the datasets. The possible reasons in terms of downscaling approaches and choice of spatial proxies are analysed and recommendations are provided for each inventory in order to work towards the harmonisation of spatial downscaling and proxy calibration, in particular for policy purposes. The proposed methodology may be useful for the development of consistent and harmonised European-wide inventories with the aim of reducing the uncertainties in air quality modelling activities.

  15. Analgesia induced by self-initiated electrotactile sensation is mediated by top-down modulations.

    Science.gov (United States)

    Zhao, Ke; Tang, Zhengyu; Wang, Huiquan; Guo, Yifei; Peng, Weiwei; Hu, Li

    2017-06-01

    It is well known that sensory perception can be attenuated when sensory stimuli are controlled by self-initiated actions. This phenomenon is explained by the consistency between forward models of anticipated action effects and actual sensory feedback. Specifically, the brain state related to the binding between motor processing and sensory perception would have inhibitory function by gating sensory information via top-down control. Since the brain state could casually influence the perception of subsequent stimuli of different sensory modalities, we hypothesize that pain evoked by nociceptive stimuli following the self-initiated tactile stimulation would be attenuated as compared to that following externally determined tactile stimulation. Here, we compared psychophysical and neurophysiological responses to identical nociceptive-specific laser stimuli in two different conditions: self-initiated tactile sensation condition (STS) and nonself-initiated tactile sensation condition (N-STS). We observed that pain intensity and unpleasantness, as well as laser-evoked brain responses, were significantly reduced in the STS condition compared to the N-STS condition. In addition, magnitudes of alpha and beta oscillations prior to laser onset were significantly larger in the STS condition than in the N-STS condition. These results confirmed that pain perception and pain-related brain responses were attenuated when the tactile stimulation was initiated by subjects' voluntary actions, and exploited neural oscillations reflecting the binding between motor processing and sensory feedback. Thus, our study elaborated the understanding of underlying neural mechanisms related to top-down modulations of the analgesic effect induced by self-initiated tactile sensation, which provided theoretical basis to improve the analgesic effect in various clinical applications. © 2017 Society for Psychophysiological Research.

  16. Comprehensive Characterization of Swine Cardiac Troponin T Proteoforms by Top-Down Mass Spectrometry

    Science.gov (United States)

    Lin, Ziqing; Guo, Fang; Gregorich, Zachery R.; Sun, Ruixiang; Zhang, Han; Hu, Yang; Shanmuganayagam, Dhanansayan; Ge, Ying

    2018-04-01

    Cardiac troponin T (cTnT) regulates the Ca2+-mediated interaction between myosin thick filaments and actin thin filaments during cardiac contraction and relaxation. cTnT is released into the blood following injury, and increased serum levels of the protein are used clinically as a biomarker for myocardial infarction. Moreover, mutations in cTnT are causative in a number of familial cardiomyopathies. With the increasing use of large animal (swine) model to recapitulate human diseases, it is essential to characterize species-dependent protein sequence variants, alternative RNA splicing, and post-translational modifications (PTMs), but challenges remain due to the incomplete database and lack of validation of the predicted splicing isoforms. Herein, we integrated top-down mass spectrometry (MS) with online liquid chromatography (LC) and immunoaffinity purification to comprehensively characterize miniature swine cTnT proteoforms, including those arising from alternative RNA splicing and PTMs. A total of seven alternative splicing isoforms of cTnT were identified by LC/MS from swine left ventricular tissue, with each isoform containing un-phosphorylated and mono-phosphorylated proteoforms. The phosphorylation site was localized to Ser1 for the mono-phosphorylated proteoforms of cTnT1, 3, 4, and 6 by online MS/MS combining collisionally activated dissociation (CAD) and electron transfer dissociation (ETD). Offline MS/MS on Fourier-transform ion cyclotron resonance (FT-ICR) mass spectrometer with CAD and electron capture dissociation (ECD) was then utilized to achieve deep sequencing of mono-phosphorylated cTnT1 (35.2 kDa) with a high sequence coverage of 87%. Taken together, this study demonstrated the unique advantage of top-down MS in the comprehensive characterization of protein alternative splicing isoforms together with PTMs. [Figure not available: see fulltext.

  17. Top Down Tandem Mass Spectrometric Analysis of a Chemically Modified Rough-Type Lipopolysaccharide Vaccine Candidate

    Science.gov (United States)

    Oyler, Benjamin L.; Khan, Mohd M.; Smith, Donald F.; Harberts, Erin M.; Kilgour, David P. A.; Ernst, Robert K.; Cross, Alan S.; Goodlett, David R.

    2018-02-01

    Recent advances in lipopolysaccharide (LPS) biology have led to its use in drug discovery pipelines, including vaccine and vaccine adjuvant discovery. Desirable characteristics for LPS vaccine candidates include both the ability to produce a specific antibody titer in patients and a minimal host inflammatory response directed by the innate immune system. However, in-depth chemical characterization of most LPS extracts has not been performed; hence, biological activities of these extracts are unpredictable. Additionally, the most widely adopted workflow for LPS structure elucidation includes nonspecific chemical decomposition steps before analyses, making structures inferred and not necessarily biologically relevant. In this work, several different mass spectrometry workflows that have not been previously explored were employed to show proof-of-principle for top down LPS primary structure elucidation, specifically for a rough-type mutant (J5) E. coli-derived LPS component of a vaccine candidate. First, ion mobility filtered precursor ions were subjected to collision induced dissociation (CID) to define differences in native J5 LPS v. chemically detoxified J5 LPS (dLPS). Next, ultra-high mass resolving power, accurate mass spectrometry was employed for unequivocal precursor and product ion empirical formulae generation. Finally, MS3 analyses in an ion trap instrument showed that previous knowledge about dissociation of LPS components can be used to reconstruct and sequence LPS in a top down fashion. A structural rationale is also explained for differential inflammatory dose-response curves, in vitro, when HEK-Blue hTLR4 cells were administered increasing concentrations of native J5 LPS v. dLPS, which will be useful in future drug discovery efforts. [Figure not available: see fulltext.

  18. Top down modulation of attention to food cues via working memory.

    Science.gov (United States)

    Higgs, Suzanne; Rutters, Femke; Thomas, Jason M; Naish, Katherine; Humphreys, Glyn W

    2012-08-01

    Attentional biases towards food cues may be linked to the development of obesity. The present study investigated the mechanisms underlying attentional biases to food cues by assessing the role of top down influences, such as working memory (WM). We assessed whether attention in normal-weight, sated participants was drawn to food items specifically when that food item was held in WM. Twenty-three participants (15 f/8 m, age 23.4±5 year, BMI 23.5±4 kg/m(2)) took part in a laboratory based study assessing reaction times to food and non-food stimuli. Participants were presented with an initial cue stimulus to either hold in WM or to merely attend to, and then searched for the target (a circle) in a two-item display. On valid trials the target was flanked by a picture matching the cue, on neutral trials the display did not contain a picture matching the cue, and on invalid trials the distractor (a square) was flanked by a picture matching the cue. Cues were food, cars or stationery items. We observed that, relative to the effects with non-food stimuli, food items in WM strongly affected attention when the memorised cue re-appeared in the search display. In particular there was an enhanced response on valid trials, when the re-appearance of the memorised cue coincided with the search target. There were no effects of cue category on attentional guidance when the cues were merely attended to but not held in WM. These data point towards food having a strong effect on top-down guidance of search from working memory, and suggest a mechanism whereby individuals who are preoccupied with thoughts of food, for example obese individuals, show facilitated detection of food cues in the environment. Copyright © 2012 Elsevier Ltd. All rights reserved.

  19. Different top-down approaches to estimate measurement uncertainty of whole blood tacrolimus mass concentration values.

    Science.gov (United States)

    Rigo-Bonnin, Raül; Blanco-Font, Aurora; Canalias, Francesca

    2018-05-08

    Values of mass concentration of tacrolimus in whole blood are commonly used by the clinicians for monitoring the status of a transplant patient and for checking whether the administered dose of tacrolimus is effective. So, clinical laboratories must provide results as accurately as possible. Measurement uncertainty can allow ensuring reliability of these results. The aim of this study was to estimate measurement uncertainty of whole blood mass concentration tacrolimus values obtained by UHPLC-MS/MS using two top-down approaches: the single laboratory validation approach and the proficiency testing approach. For the single laboratory validation approach, we estimated the uncertainties associated to the intermediate imprecision (using long-term internal quality control data) and the bias (utilizing a certified reference material). Next, we combined them together with the uncertainties related to the calibrators-assigned values to obtain a combined uncertainty for, finally, to calculate the expanded uncertainty. For the proficiency testing approach, the uncertainty was estimated in a similar way that the single laboratory validation approach but considering data from internal and external quality control schemes to estimate the uncertainty related to the bias. The estimated expanded uncertainty for single laboratory validation, proficiency testing using internal and external quality control schemes were 11.8%, 13.2%, and 13.0%, respectively. After performing the two top-down approaches, we observed that their uncertainty results were quite similar. This fact would confirm that either two approaches could be used to estimate the measurement uncertainty of whole blood mass concentration tacrolimus values in clinical laboratories. Copyright © 2018 The Canadian Society of Clinical Chemists. Published by Elsevier Inc. All rights reserved.

  20. Top-down approach in protein RDC data analysis: de novo estimation of the alignment tensor

    International Nuclear Information System (INIS)

    Chen Kang; Tjandra, Nico

    2007-01-01

    In solution NMR spectroscopy the residual dipolar coupling (RDC) is invaluable in improving both the precision and accuracy of NMR structures during their structural refinement. The RDC also provides a potential to determine protein structure de novo. These procedures are only effective when an accurate estimate of the alignment tensor has already been made. Here we present a top-down approach, starting from the secondary structure elements and finishing at the residue level, for RDC data analysis in order to obtain a better estimate of the alignment tensor. Using only the RDCs from N-H bonds of residues in α-helices and CA-CO bonds in β-strands, we are able to determine the offset and the approximate amplitude of the RDC modulation-curve for each secondary structure element, which are subsequently used as targets for global minimization. The alignment order parameters and the orientation of the major principal axis of individual helix or strand, with respect to the alignment frame, can be determined in each of the eight quadrants of a sphere. The following minimization against RDC of all residues within the helix or strand segment can be carried out with fixed alignment order parameters to improve the accuracy of the orientation. For a helical protein Bax, the three components A xx , A yy and A zz , of the alignment order can be determined with this method in average to within 2.3% deviation from the values calculated with the available atomic coordinates. Similarly for β-sheet protein Ubiquitin they agree in average to within 8.5%. The larger discrepancy in β-strand parameters comes from both the diversity of the β-sheet structure and the lower precision of CA-CO RDCs. This top-down approach is a robust method for alignment tensor estimation and also holds a promise for providing a protein topological fold using limited sets of RDCs

  1. Towards a routine application of Top-Down approaches for label-free discovery workflows.

    Science.gov (United States)

    Schmit, Pierre-Olivier; Vialaret, Jerome; Wessels, Hans J C T; van Gool, Alain J; Lehmann, Sylvain; Gabelle, Audrey; Wood, Jason; Bern, Marshall; Paape, Rainer; Suckau, Detlev; Kruppa, Gary; Hirtz, Christophe

    2018-03-20

    Thanks to proteomics investigations, our vision of the role of different protein isoforms in the pathophysiology of diseases has largely evolved. The idea that protein biomarkers like tau, amyloid peptides, ApoE, cystatin, or neurogranin are represented in body fluids as single species is obviously over-simplified, as most proteins are present in different isoforms and subjected to numerous processing and post-translational modifications. Measuring the intact mass of proteins by MS has the advantage to provide information on the presence and relative amount of the different proteoforms. Such Top-Down approaches typically require a high degree of sample pre-fractionation to allow the MS system to deliver optimal performance in terms of dynamic range, mass accuracy and resolution. In clinical studies, however, the requirements for pre-analytical robustness and sample size large enough for statistical power restrict the routine use of a high degree of sample pre-fractionation. In this study, we have investigated the capacities of current-generation Ultra-High Resolution Q-Tof systems to deal with high complexity intact protein samples and have evaluated the approach on a cohort of patients suffering from neurodegenerative disease. Statistical analysis has shown that several proteoforms can be used to distinguish Alzheimer disease patients from patients suffering from other neurodegenerative disease. Top-down approaches have an extremely high biological relevance, especially when it comes to biomarker discovery, but the necessary pre-fractionation constraints are not easily compatible with the robustness requirements and the size of clinical sample cohorts. We have demonstrated that intact protein profiling studies could be run on UHR-Q-ToF with limited pre-fractionation. The proteoforms that have been identified as candidate biomarkers in the-proof-of concept study are derived from proteins known to play a role in the pathophysiology process of Alzheimer disease

  2. Hemispheric lateralization in top-down attention during spatial relation processing: a Granger causal model approach.

    Science.gov (United States)

    Falasca, N W; D'Ascenzo, S; Di Domenico, A; Onofrj, M; Tommasi, L; Laeng, B; Franciotti, R

    2015-04-01

    Magnetoencephalography was recorded during a matching-to-sample plus cueing paradigm, in which participants judged the occurrence of changes in either categorical (CAT) or coordinate (COO) spatial relations. Previously, parietal and frontal lobes were identified as key areas in processing spatial relations and it was shown that each hemisphere was differently involved and modulated by the scope of the attention window (e.g. a large and small cue). In this study, Granger analysis highlighted the patterns of causality among involved brain areas--the direction of information transfer ran from the frontal to the visual cortex in the right hemisphere, whereas it ran in the opposite direction in the left side. Thus, the right frontal area seems to exert top-down influence, supporting the idea that, in this task, top-down signals are selectively related to the right side. Additionally, for CAT change preceded by a small cue, the right frontal gyrus was not involved in the information transfer, indicating a selective specialization of the left hemisphere for this condition. The present findings strengthen the conclusion of the presence of a remarkable hemispheric specialization for spatial relation processing and illustrate the complex interactions between the lateralized parts of the neural network. Moreover, they illustrate how focusing attention over large or small regions of the visual field engages these lateralized networks differently, particularly in the frontal regions of each hemisphere, consistent with the theory that spatial relation judgements require a fronto-parietal network in the left hemisphere for categorical relations and on the right hemisphere for coordinate spatial processing. © 2015 Federation of European Neuroscience Societies and John Wiley & Sons Ltd.

  3. Characterization of the Vibrio cholerae extracellular matrix: a top-down solid-state NMR approach.

    Science.gov (United States)

    Reichhardt, Courtney; Fong, Jiunn C N; Yildiz, Fitnat; Cegelski, Lynette

    2015-01-01

    Bacterial biofilms are communities of bacterial cells surrounded by a self-secreted extracellular matrix. Biofilm formation by Vibrio cholerae, the human pathogen responsible for cholera, contributes to its environmental survival and infectivity. Important genetic and molecular requirements have been identified for V. cholerae biofilm formation, yet a compositional accounting of these parts in the intact biofilm or extracellular matrix has not been described. As insoluble and non-crystalline assemblies, determinations of biofilm composition pose a challenge to conventional biochemical and biophysical analyses. The V. cholerae extracellular matrix composition is particularly complex with several proteins, complex polysaccharides, and other biomolecules having been identified as matrix parts. We developed a new top-down solid-state NMR approach to spectroscopically assign and quantify the carbon pools of the intact V. cholerae extracellular matrix using ¹³C CPMAS and ¹³C{(¹⁵N}, ¹⁵N{³¹P}, and ¹³C{³¹P}REDOR. General sugar, lipid, and amino acid pools were first profiled and then further annotated and quantified as specific carbon types, including carbonyls, amides, glycyl carbons, and anomerics. In addition, ¹⁵N profiling revealed a large amine pool relative to amide contributions, reflecting the prevalence of molecular modifications with free amine groups. Our top-down approach could be implemented immediately to examine the extracellular matrix from mutant strains that might alter polysaccharide production or lipid release beyond the cell surface; or to monitor changes that may accompany environmental variations and stressors such as altered nutrient composition, oxidative stress or antibiotics. More generally, our analysis has demonstrated that solid-state NMR is a valuable tool to characterize complex biofilm systems. Copyright © 2014. Published by Elsevier B.V.

  4. Observability of Higgs produced with top quarks and decaying to bottom quarks

    International Nuclear Information System (INIS)

    Benedetti, D; Cucciarelli, S; Hill, C; Incandela, J; Koay, S A; Riccardi, C; Santocchia, A; Schmidt, A; Weiser, C

    2007-01-01

    The decay, H → b-barb, is dominant for a Standard Model Higgs boson in the mass range just above the exclusion limit of 114.4 GeV/c 2 reported by the LEP experiments. Unfortunately, an overwhelming abundance of bb-bar events arising from more mundane sources, together with the lack of precision inherent in the reconstruction of the Higgs mass, renders this decay mode a priori undetectable in the case of direct Higgs production at the LHC. It is therefore of no small interest to investigate whether H → b-barb can be observed in those cases where the Higgs is produced in association with other massive particles. In this note, the results of a study of Higgs bosons produced in association with top quarks and decaying via H → b-bar b presented. The study was performed as realistically as possible by employing a full and detailed Monte Carlo simulation of the CMS detector followed by the application of trigger and reconstruction algorithms that were developed for use with real data. Important systematic effects resulting from such sources as the uncertainties in the jet energy scale and the estimated rates for correctly tagging b jets or mistagging non-b jets have been taken into account. The impact of large theoretical uncertainties in the cross sections for tt-bar plus N jets processes due to an absence of next-to-leading order calculations is also considered. (research note from collaboration)

  5. Nuclear fuel assembly top nozzle with improved arrangement of hold-down leaf spring assemblies

    International Nuclear Information System (INIS)

    De Mario, E.E.; Lawson, C.N.

    1991-01-01

    This patent describes a top nozzle for use in a fuel assembly having guide thimbles for mounting the top nozzle. It comprises: a lower adapter plate having a periphery bounding an interior thereof mountable to the guide thimbles: guide structures attached to and extending along the periphery of the adapter plate and upwardly therefrom; an upper hold-down plate mounted to the guide structures for slidable movement relative thereto such that the upper plate can move toward and away from the interior of the lower plate within the space bounded by the guide structures as the upper plate slidably moves along the guide structures; and leaf spring assemblies interposed between and engaged with the lower and upper plates so as to yieldably support the upper plate in spaced relation above the lower plate and bias the upper plate for movement away from the lower plate; the leaf spring assemblies being provided in a non-peripheral arrangement relative to the periphery of the lower plate in which the assemblies cross the interior of the lower plate in a diagonal fashion between adjacent ones of the guide structures

  6. Comprehensive Analysis of Low-Molecular-Weight Human Plasma Proteome Using Top-Down Mass Spectrometry.

    Science.gov (United States)

    Cheon, Dong Huey; Nam, Eun Ji; Park, Kyu Hyung; Woo, Se Joon; Lee, Hye Jin; Kim, Hee Cheol; Yang, Eun Gyeong; Lee, Cheolju; Lee, Ji Eun

    2016-01-04

    While human plasma serves as a great source for disease diagnosis, low-molecular-weight (LMW) proteome (mass spectrometry to analyze the LMW proteoforms present in four types of human plasma samples pooled from three healthy controls (HCs) without immunoaffinity depletion and with depletion of the top two, six, and seven high-abundance proteins. The LMW proteoforms were first fractionated based on molecular weight using gel-eluted liquid fraction entrapment electrophoresis (GELFrEE). Then, the GELFrEE fractions containing up to 30 kDa were subjected to nanocapillary-LC-MS/MS, and the high-resolution MS and MS/MS data were processed using ProSightPC 3.0. As a result, a total of 442 LMW proteins and cleaved products, including those with post-translational modifications and single amino acid variations, were identified. From additional comparative analysis of plasma samples without immunoaffinity depletion between HCs and colorectal cancer (CRC) patients via top-down approach, tens of LMW proteoforms, including platelet factor 4, were found to show >1.5-fold changes between the plasma samples of HCs and CRC patients, and six of the LMW proteins were verified by Western blot analysis.

  7. Breaking down IT silos: a "connected" way to improve customer experience and the bottom line.

    Science.gov (United States)

    Hallowell, Bruce; Turisco, Frances

    2009-03-01

    Hospitals can provide customer service like Amazon.com without purchasing new technology. Making technology interactive requires sharing patient data across applications and enhancing existing IT with decision support. Breaking down technology silos between hospital and outpatient care provider systems significantly improves efficiency, lowers costs, and speeds care delivery.

  8. Goal-directed control with cortical units that are gated by both top-down feedback and oscillatory coherence

    Science.gov (United States)

    Kerr, Robert R.; Grayden, David B.; Thomas, Doreen A.; Gilson, Matthieu; Burkitt, Anthony N.

    2014-01-01

    The brain is able to flexibly select behaviors that adapt to both its environment and its present goals. This cognitive control is understood to occur within the hierarchy of the cortex and relies strongly on the prefrontal and premotor cortices, which sit at the top of this hierarchy. Pyramidal neurons, the principal neurons in the cortex, have been observed to exhibit much stronger responses when they receive inputs at their soma/basal dendrites that are coincident with inputs at their apical dendrites. This corresponds to inputs from both lower-order regions (feedforward) and higher-order regions (feedback), respectively. In addition to this, coherence between oscillations, such as gamma oscillations, in different neuronal groups has been proposed to modulate and route communication in the brain. In this paper, we develop a simple, but novel, neural mass model in which cortical units (or ensembles) exhibit gamma oscillations when they receive coherent oscillatory inputs from both feedforward and feedback connections. By forming these units into circuits that can perform logic operations, we identify the different ways in which operations can be initiated and manipulated by top-down feedback. We demonstrate that more sophisticated and flexible top-down control is possible when the gain of units is modulated by not only top-down feedback but by coherence between the activities of the oscillating units. With these types of units, it is possible to not only add units to, or remove units from, a higher-level unit's logic operation using top-down feedback, but also to modify the type of role that a unit plays in the operation. Finally, we explore how different network properties affect top-down control and processing in large networks. Based on this, we make predictions about the likely connectivities between certain brain regions that have been experimentally observed to be involved in goal-directed behavior and top-down attention. PMID:25152715

  9. Goal-directed control with cortical units that are gated by both top-down feedback and oscillatory coherence

    Directory of Open Access Journals (Sweden)

    Robert R. Kerr

    2014-08-01

    Full Text Available The brain is able to flexibly select behaviors that adapt to both its environment and its present goals. This cognitive control is understood to occur within the hierarchy of the cortex and relies strongly on the prefrontal and premotor cortices, which sit at the top of this hierarchy. Pyramidal neurons, the principal neurons in the cortex, have been observed to exhibit much stronger responses when they receive inputs at their soma/basal dendrites that are coincident with inputs at their apical dendrites. This corresponds to inputs from both lower-order regions (feedforward and higher-order regions (feedback, respectively. In addition to this, coherence between oscillations, such as gamma oscillations, in different neuronal groups has been proposed to modulate and route communication in the brain. In this paper, we develop a simple, but novel, neural mass model in which cortical units (or ensembles exhibit gamma oscillations when they receive coherent oscillatory inputs from both feedforward and feedback connections. By forming these units into circuits that can perform logic operations, we identify the different ways in which operations can be initiated and manipulated by top-down feedback. We demonstrate that more sophisticated and flexible top-down control is possible when the gain of units is modulated by not only top-down feedback but by coherence between the activities of the oscillating units. With these types of units, it is possible to not only add units to, or remove units from, a higher-level unit's logic operation using top-down feedback, but also to modify the type of role that a unit plays in the operation. Finally, we explore how different network properties affect top-down control and processing in large networks. Based on this, we make predictions about the likely connectivities between certain brain regions that have been experimentally observed to be involved in goal-directed behavior and top-down attention.

  10. Male and female meadow voles Microtus pennsylvanicus respond differently to scent marks from the top- middle-, and bottom-scent donors of an over-mark

    Directory of Open Access Journals (Sweden)

    Michael H. FERKIN, Nicholas J. HOBBS, Benjamin D. FERKIN, Adam C.FERKIN, Daniel A. FERKIN

    2011-08-01

    Full Text Available Previous studies have shown that individuals responded preferentially to the mark of the top-scent donor relative to that of the bottom-scent donor of an over-mark. However, terrestrial mammals are likely to encounter over-marks consisting of the scent marks of more than two same-sex conspecifics in the intersections of runways, near the nests of sexually receptive female conspecifics, and inside and along the borders of the territories of conspecifics. We determined how meadow voles, Microtus pennsylvanicus, respond to the marks of the top-, middle-, and bottom-scent donors of an over-mark. We tested the hypothesis that voles exposed to an over-mark will respond preferentially to the scent marks that were deposited more recently, the scent marks that were on top or near the top of the over-mark, compared to the scent marks that were deposited earlier or near the bottom of the over-mark. Voles spent more time investigating the mark of the top-scent donor than that of the either the middle- or bottom-scent donor. However, males but not female voles spent more time investigating the middle-scent mark than the bottom-scent mark. We also tested the hypothesis that voles evaluate and respond to over-marks differently from single scent marks. Voles spent more time investigating the marks of the top-, middle-, and bottom-scent donors compared to scent marks that were not part of the over-mark. Voles can distinguish among the overlapping scent marks of three scent donors and sex differences exist in the values they appear to attach to each of these scent marks [Current Zoology 57 (4: 441–448, 2011].

  11. Top-down constraints on global N2O emissions at optimal resolution: application of a new dimension reduction technique

    Science.gov (United States)

    Wells, Kelley C.; Millet, Dylan B.; Bousserez, Nicolas; Henze, Daven K.; Griffis, Timothy J.; Chaliyakunnel, Sreelekha; Dlugokencky, Edward J.; Saikawa, Eri; Xiang, Gao; Prinn, Ronald G.; O'Doherty, Simon; Young, Dickon; Weiss, Ray F.; Dutton, Geoff S.; Elkins, James W.; Krummel, Paul B.; Langenfelds, Ray; Steele, L. Paul

    2018-01-01

    We present top-down constraints on global monthly N2O emissions for 2011 from a multi-inversion approach and an ensemble of surface observations. The inversions employ the GEOS-Chem adjoint and an array of aggregation strategies to test how well current observations can constrain the spatial distribution of global N2O emissions. The strategies include (1) a standard 4D-Var inversion at native model resolution (4° × 5°), (2) an inversion for six continental and three ocean regions, and (3) a fast 4D-Var inversion based on a novel dimension reduction technique employing randomized singular value decomposition (SVD). The optimized global flux ranges from 15.9 Tg N yr-1 (SVD-based inversion) to 17.5-17.7 Tg N yr-1 (continental-scale, standard 4D-Var inversions), with the former better capturing the extratropical N2O background measured during the HIAPER Pole-to-Pole Observations (HIPPO) airborne campaigns. We find that the tropics provide a greater contribution to the global N2O flux than is predicted by the prior bottom-up inventories, likely due to underestimated agricultural and oceanic emissions. We infer an overestimate of natural soil emissions in the extratropics and find that predicted emissions are seasonally biased in northern midlatitudes. Here, optimized fluxes exhibit a springtime peak consistent with the timing of spring fertilizer and manure application, soil thawing, and elevated soil moisture. Finally, the inversions reveal a major emission underestimate in the US Corn Belt in the bottom-up inventory used here. We extensively test the impact of initial conditions on the analysis and recommend formally optimizing the initial N2O distribution to avoid biasing the inferred fluxes. We find that the SVD-based approach provides a powerful framework for deriving emission information from N2O observations: by defining the optimal resolution of the solution based on the information content of the inversion, it provides spatial information that is lost when

  12. Reflood completion report: Volume 1. A phenomenological thermal-hydraulic model of hot rod bundles experiencing simultaneous bottom and top quenching and an optimization methodology for closure development

    International Nuclear Information System (INIS)

    Nelson, R.A. Jr.; Pimentel, D.A.; Jolly-Woodruff, S.; Spore, J.

    1998-04-01

    In this report, a phenomenological model of simultaneous bottom-up and top-down quenching is developed and discussed. The model was implemented in the TRAC-PF1/MOD2 computer code. Two sets of closure relationships were compared within the study, the Absolute set and the Conditional set. The Absolute set of correlations is frequently viewed as the pure set because the correlations is frequently viewed as the pure set because the correlations utilize their original coefficients as suggested by the developer. The Conditional set is a modified set of correlations with changes to the correlation coefficient only. Results for these two sets indicate quite similar results. This report also summarizes initial results of an effort to investigate nonlinear optimization techniques applied to the closure model development. Results suggest that such techniques can provide advantages for future model development work, but that extensive expertise is required to utilize such techniques (i.e., the model developer must fully understand both the physics of the process being represented and the computational techniques being employed). The computer may then be used to improve the correlation of computational results with experiments

  13. A GENERALIZED NON-LINEAR METHOD FOR DISTORTION CORRECTION AND TOP-DOWN VIEW CONVERSION OF FISH EYE IMAGES

    Directory of Open Access Journals (Sweden)

    Vivek Singh Bawa

    2017-06-01

    Full Text Available Advanced driver assistance systems (ADAS have been developed to automate and modify vehicles for safety and better driving experience. Among all computer vision modules in ADAS, 360-degree surround view generation of immediate surroundings of the vehicle is very important, due to application in on-road traffic assistance, parking assistance etc. This paper presents a novel algorithm for fast and computationally efficient transformation of input fisheye images into required top down view. This paper also presents a generalized framework for generating top down view of images captured by cameras with fish-eye lenses mounted on vehicles, irrespective of pitch or tilt angle. The proposed approach comprises of two major steps, viz. correcting the fish-eye lens images to rectilinear images, and generating top-view perspective of the corrected images. The images captured by the fish-eye lens possess barrel distortion, for which a nonlinear and non-iterative method is used. Thereafter, homography is used to obtain top-down view of corrected images. This paper also targets to develop surroundings of the vehicle for wider distortion less field of view and camera perspective independent top down view, with minimum computation cost which is essential due to limited computation power on vehicles.

  14. Assessing a Top-Down Modeling Approach for Seasonal Scale Snow Sensitivity

    Science.gov (United States)

    Luce, C. H.; Lute, A.

    2017-12-01

    Mechanistic snow models are commonly applied to assess changes to snowpacks in a warming climate. Such assessments involve a number of assumptions about details of weather at daily to sub-seasonal time scales. Models of season-scale behavior can provide contrast for evaluating behavior at time scales more in concordance with climate warming projections. Such top-down models, however, involve a degree of empiricism, with attendant caveats about the potential of a changing climate to affect calibrated relationships. We estimated the sensitivity of snowpacks from 497 Snowpack Telemetry (SNOTEL) stations in the western U.S. based on differences in climate between stations (spatial analog). We examined the sensitivity of April 1 snow water equivalent (SWE) and mean snow residence time (SRT) to variations in Nov-Mar precipitation and average Nov-Mar temperature using multivariate local-fit regressions. We tested the modeling approach using a leave-one-out cross-validation as well as targeted two-fold non-random cross-validations contrasting, for example, warm vs. cold years, dry vs. wet years, and north vs. south stations. Nash-Sutcliffe Efficiency (NSE) values for the validations were strong for April 1 SWE, ranging from 0.71 to 0.90, and still reasonable, but weaker, for SRT, in the range of 0.64 to 0.81. From these ranges, we exclude validations where the training data do not represent the range of target data. A likely reason for differences in validation between the two metrics is that the SWE model reflects the influence of conservation of mass while using temperature as an indicator of the season-scale energy balance; in contrast, SRT depends more strongly on the energy balance aspects of the problem. Model forms with lower numbers of parameters generally validated better than more complex model forms, with the caveat that pseudoreplication could encourage selection of more complex models when validation contrasts were weak. Overall, the split sample validations

  15. Covariance specification and estimation to improve top-down Green House Gas emission estimates

    Science.gov (United States)

    Ghosh, S.; Lopez-Coto, I.; Prasad, K.; Whetstone, J. R.

    2015-12-01

    The National Institute of Standards and Technology (NIST) operates the North-East Corridor (NEC) project and the Indianapolis Flux Experiment (INFLUX) in order to develop measurement methods to quantify sources of Greenhouse Gas (GHG) emissions as well as their uncertainties in urban domains using a top down inversion method. Top down inversion updates prior knowledge using observations in a Bayesian way. One primary consideration in a Bayesian inversion framework is the covariance structure of (1) the emission prior residuals and (2) the observation residuals (i.e. the difference between observations and model predicted observations). These covariance matrices are respectively referred to as the prior covariance matrix and the model-data mismatch covariance matrix. It is known that the choice of these covariances can have large effect on estimates. The main objective of this work is to determine the impact of different covariance models on inversion estimates and their associated uncertainties in urban domains. We use a pseudo-data Bayesian inversion framework using footprints (i.e. sensitivities of tower measurements of GHGs to surface emissions) and emission priors (based on Hestia project to quantify fossil-fuel emissions) to estimate posterior emissions using different covariance schemes. The posterior emission estimates and uncertainties are compared to the hypothetical truth. We find that, if we correctly specify spatial variability and spatio-temporal variability in prior and model-data mismatch covariances respectively, then we can compute more accurate posterior estimates. We discuss few covariance models to introduce space-time interacting mismatches along with estimation of the involved parameters. We then compare several candidate prior spatial covariance models from the Matern covariance class and estimate their parameters with specified mismatches. We find that best-fitted prior covariances are not always best in recovering the truth. To achieve

  16. Top-down Estimates of Isoprene Emissions in Australia Inferred from OMI Satellite Data.

    Science.gov (United States)

    Greenslade, J.; Fisher, J. A.; Surl, L.; Palmer, P. I.

    2017-12-01

    Australia is a global hotspot for biogenic isoprene emission factors predicted by process-based models such as the Model of Emissions of Gases and Aerosols from Nature (MEGAN). It is also prone to increasingly frequent temperature extremes that can drive episodically high emissions. Estimates of biogenic isoprene emissions from Australia are poorly constrained, with the frequently used MEGAN model overestimating emissions by a factor of 4-6 in some areas. Evaluating MEGAN and other models in Australia is difficult due to sparse measurements of emissions and their ensuing chemical products. In this talk, we will describe efforts to better quantify Australian isoprene emissions using top-down estimates based on formaldehyde (HCHO) observations from the OMI satellite instrument, combined with modelled isoprene to HCHO yields obtained from the GEOS-Chem chemical transport model. The OMI-based estimates are evaluated using in situ observations from field campaigns conducted in southeast Australia. We also investigate the impact on the inferred emission of horizontal resolution used for the yield calculations, particularly in regions on the boundary between low- and high-NOx chemistry. The prevalence of fire smoke plumes roughly halves the available satellite dataset over Australia for much of the year; however, seasonal averages remain robust. Preliminary results show that the top-down isoprene emissions are lower than MEGAN estimates by up to 90% in summer. The overestimates are greatest along the eastern coast, including areas surrounding Australia's major population centres in Sydney, Melbourne, and Brisbane. The coarse horizontal resolution of the model significantly affects the emissions estimates, as many biogenic emitting regions lie along narrow coastal stretches. Our results confirm previous findings that the MEGAN biogenic emission model is poorly calibrated for the Australian environment and suggests that chemical transport models driven by MEGAN are likely

  17. Bottom up

    International Nuclear Information System (INIS)

    Ockenden, James

    1999-01-01

    This article presents an overview of the electric supply industries in Eastern Europe. The development of more competitive and efficient plant in Poland and work on emissions control ahead of EU membership; the Czech's complicated tariff system; Hungary's promised 8% return on investment in their electricity supply industry and its tariff problems; Bulgaria and Ukraine's desperate need for investment to build alternative plants to their aging nuclear plants; and demand outstripping supply in Romania are among the topics considered.. The viscous circle of poor service and low utility income is considered, and the top-down approach for breaking the cycle by improving plant efficiency, and the bottom up approach of improving plant income as practiced by Moldavia are explained. (UK)

  18. Critical appraisal of the top-down approach for vesicoureteral reflux

    Directory of Open Access Journals (Sweden)

    Ahmed Abdelhalim

    2017-06-01

    Full Text Available Vesicoureteral reflux (VUR has been linked to recurrent urinary tract infections (UTIs, renal scarring, hypertension, renal insufficiency and end-stage kidney disease. Different imaging strategies have been proposed to approach children presenting with UTI to sort out patients with significant VUR while minimizing patient morbidity, radiation exposure and financial burden. None of these imaging strategies is universally accepted. The “top-down approach” (TDA aims at restricting the number of voiding cystourethrograms (VCUGs and its associated morbidity while identifying patients with clinically-significant reflux. In this approach, children presenting with febrile UTIs are acutely investigated with dimercapto-succinic acid (DMSA renal scans to identify patients with renal parenchymal inflammation. Those with evidence of renal affection are offered VCUG and late DMSA scan to identify VUR and permanent renal scarring, respectively. Although TDA could identify clinically-significant VUR with high sensitivity, it is not without limitations. The approach segregates patients based on the presence of DMSA cortical lesions omitting the morbidity and the economic burden of UTI. Additionally, some of DMSA lesions are attributed to congenital dysplasia and unrelated to UTI. Ionizing radiation exposure, financial costs, limited availability of DMSA scans in the acute setting, variability in interpreting the results and low yield of actionable findings on DMSA scans are some other limitations. In this review, we tried to address the drawbacks of the TDA and reinforce the value of patient-centered approach for VUR.

  19. Modeling the Effects of Perceptual Load: Saliency, Competitive Interactions, and Top-Down Biases.

    Science.gov (United States)

    Neokleous, Kleanthis; Shimi, Andria; Avraamides, Marios N

    2016-01-01

    A computational model of visual selective attention has been implemented to account for experimental findings on the Perceptual Load Theory (PLT) of attention. The model was designed based on existing neurophysiological findings on attentional processes with the objective to offer an explicit and biologically plausible formulation of PLT. Simulation results verified that the proposed model is capable of capturing the basic pattern of results that support the PLT as well as findings that are considered contradictory to the theory. Importantly, the model is able to reproduce the behavioral results from a dilution experiment, providing thus a way to reconcile PLT with the competing Dilution account. Overall, the model presents a novel account for explaining PLT effects on the basis of the low-level competitive interactions among neurons that represent visual input and the top-down signals that modulate neural activity. The implications of the model concerning the debate on the locus of selective attention as well as the origins of distractor interference in visual displays of varying load are discussed.

  20. Modeling the effects of perceptual load: saliency, competitive interactions, and top-down biases.

    Directory of Open Access Journals (Sweden)

    Kleanthis eNeokleous

    2016-01-01

    Full Text Available A computational model of visual selective attention has been implemented to account for experimental findings on the Perceptual Load Theory (PLT of attention. The model was designed based on existing neurophysiological findings on attentional processes with the objective to offer an explicit and biologically plausible formulation of PLT. Simulation results verified that the proposed model is capable of capturing the basic pattern of results that support the Perceptual Load Theory as well as findings that are considered contradictory to the theory. Importantly, the model is able to reproduce the behavioral results from a dilution experiment, providing thus a way to reconcile PLT with the competing Dilution account. Overall, the model presents a novel account for explaining PLT effects on the basis of the low-level competitive interactions among neurons that represent visual input and the top-down signals that modulate neural activity. The implications of the model concerning the debate on the locus of selective attention as well as the origins of distractor interference in visual displays of varying load are discussed.

  1. Pupil dilation reveals top-down attentional load during spatial monitoring.

    Science.gov (United States)

    Lisi, Matteo; Bonato, Mario; Zorzi, Marco

    2015-12-01

    It has long been known that the diameter of human pupil enlarges with increasing effort during the execution of a task. This has been observed not only for purely mechanical effort but also for mental effort, as for example the computation of arithmetic problems with different levels of difficulty. Here we show that pupil dilation reflects changes in visuospatial awareness induced by attentional load during multi-tasking. In the single-task condition, participants had to report the position of lateralized, briefly presented, masked visual targets ("right", "left", or "both" sides). In the multitasking conditions, participants also performed additional tasks, either visual or auditory, to increase the attentional load. Sensory stimulation was kept constant across all conditions to rule out the influence of low-level factors. Results show that event-related pupil dilation strikingly increased with task demands, mirroring a concurrent decrease in visuospatial awareness. Importantly, pupil dilation significantly differed between two dual-task conditions that required to process the same number of stimuli but yielded differed levels of accuracy (difficulty). In contrast, pupil dilation did not differ between two conditions which were equally challenging but differed both in the modality of the dual task (auditory vs. visual) and in the number of stimuli to be attended. We conclude that pupil dilation genuinely reflects the top-down allocation of supramodal attentional resources. Copyright © 2015 Elsevier B.V. All rights reserved.

  2. Laboratory Formation of Fullerenes from PAHs: Top-down Interstellar Chemistry

    Science.gov (United States)

    Zhen, Junfeng; Castellanos, Pablo; Paardekooper, Daniel M.; Linnartz, Harold; Tielens, Alexander G. G. M.

    2014-12-01

    Interstellar molecules are thought to build up in the shielded environment of molecular clouds or in the envelope of evolved stars. This follows many sequential reaction steps of atoms and simple molecules in the gas phase and/or on (icy) grain surfaces. However, these chemical routes are highly inefficient for larger species in the tenuous environment of space as many steps are involved and, indeed, models fail to explain the observed high abundances. This is definitely the case for the C60 fullerene, recently identified as one of the most complex molecules in the interstellar medium. Observations have shown that, in some photodissociation regions, its abundance increases close to strong UV-sources. In this Letter we report laboratory findings in which C60 formation can be explained by characterizing the photochemical evolution of large polycyclic aromatic hydrocarbons (PAHs). Sequential H losses lead to fully dehydrogenated PAHs and subsequent losses of C2 units convert graphene into cages. Our results present for the first time experimental evidence that PAHs in excess of 60 C-atoms efficiently photo-isomerize to buckminsterfullerene, C60. These laboratory studies also attest to the importance of top-down synthesis routes for chemical complexity in space.

  3. Hybrid Donor-Dot Devices made using Top-down Ion Implantation for Quantum Computing

    Science.gov (United States)

    Bielejec, Edward; Bishop, Nathan; Carroll, Malcolm

    2012-02-01

    We present progress towards fabricating hybrid donor -- quantum dots (QD) for quantum computing. These devices will exploit the long coherence time of the donor system and the surface state manipulation associated with a QD. Fabrication requires detection of single ions implanted with 10's of nanometer precision. We show in this talk, 100% detection efficiency for single ions using a single ion Geiger mode avalanche (SIGMA) detector integrated into a Si MOS QD process flow. The NanoImplanter (nI) a focused ion beam system is used for precision top-down placement of the implanted ion. This machine has a 10 nm resolution combined with a mass velocity filter, allowing for the use of multi-species liquid metal ion sources (LMIS) to implant P and Sb ions, and a fast blanking and chopping system for single ion implants. The combination of the nI and integration of the SIGMA with the MOS QD process flow establishes a path to fabricate hybrid single donor-dot devices. Sandia National Laboratories is a multi-program laboratory managed and operated by Sandia Corporation, a wholly owned subsidiary of Lockheed Martin Corporation, for the U.S. Department of Energy's National Nuclear Security Administration under contract DE-AC04-94AL85000.

  4. Node Query Preservation for Deterministic Linear Top-Down Tree Transducers

    Directory of Open Access Journals (Sweden)

    Kazuki Miyahara

    2013-11-01

    Full Text Available This paper discusses the decidability of node query preservation problems for XML document transformations. We assume a transformation given by a deterministic linear top-down data tree transducer (abbreviated as DLT^V and an n-ary query based on runs of a tree automaton. We say that a DLT^V Tr strongly preserves a query Q if there is a query Q' such that for every document t, the answer set of Q' for Tr(t is equal to the answer set of Q for t. Also we say that Tr weakly preserves Q if there is a query Q' such that for every t_d in the range of Tr, the answer set of Q' for t_d is equal to the union of the answer set of Q for t such that t_d = Tr(t. We show that the weak preservation problem is coNP-complete and the strong preservation problem is in 2-EXPTIME.

  5. Deep imaging: how much of the proteome does current top-down technology already resolve?

    Directory of Open Access Journals (Sweden)

    Elise P Wright

    Full Text Available Effective proteome analyses are based on interplay between resolution and detection. It had been claimed that resolution was the main factor limiting the use of two-dimensional gel electrophoresis. Improved protein detection now indicates that this is unlikely to be the case. Using a highly refined protocol, the rat brain proteome was extracted, resolved, and detected. In order to overcome the stain saturation threshold, high abundance protein species were excised from the gel following standard imaging. Gels were then imaged again using longer exposure times, enabling detection of lower abundance, less intensely stained protein species. This resulted in a significant enhancement in the detection of resolved proteins, and a slightly modified digestion protocol enabled effective identification by standard mass spectrometric methods. The data indicate that the resolution required for comprehensive proteome analyses is already available, can assess multiple samples in parallel, and preserve critical information concerning post-translational modifications. Further optimization of staining and detection methods promises additional improvements to this economical, widely accessible and effective top-down approach to proteome analysis.

  6. LABORATORY FORMATION OF FULLERENES FROM PAHS: TOP-DOWN INTERSTELLAR CHEMISTRY

    International Nuclear Information System (INIS)

    Zhen, Junfeng; Castellanos, Pablo; Tielens, Alexander G. G. M.; Paardekooper, Daniel M.; Linnartz, Harold

    2014-01-01

    Interstellar molecules are thought to build up in the shielded environment of molecular clouds or in the envelope of evolved stars. This follows many sequential reaction steps of atoms and simple molecules in the gas phase and/or on (icy) grain surfaces. However, these chemical routes are highly inefficient for larger species in the tenuous environment of space as many steps are involved and, indeed, models fail to explain the observed high abundances. This is definitely the case for the C 60 fullerene, recently identified as one of the most complex molecules in the interstellar medium. Observations have shown that, in some photodissociation regions, its abundance increases close to strong UV-sources. In this Letter we report laboratory findings in which C 60 formation can be explained by characterizing the photochemical evolution of large polycyclic aromatic hydrocarbons (PAHs). Sequential H losses lead to fully dehydrogenated PAHs and subsequent losses of C 2 units convert graphene into cages. Our results present for the first time experimental evidence that PAHs in excess of 60 C-atoms efficiently photo-isomerize to buckminsterfullerene, C 60 . These laboratory studies also attest to the importance of top-down synthesis routes for chemical complexity in space

  7. Musical experience shapes top-down auditory mechanisms: evidence from masking and auditory attention performance.

    Science.gov (United States)

    Strait, Dana L; Kraus, Nina; Parbery-Clark, Alexandra; Ashley, Richard

    2010-03-01

    A growing body of research suggests that cognitive functions, such as attention and memory, drive perception by tuning sensory mechanisms to relevant acoustic features. Long-term musical experience also modulates lower-level auditory function, although the mechanisms by which this occurs remain uncertain. In order to tease apart the mechanisms that drive perceptual enhancements in musicians, we posed the question: do well-developed cognitive abilities fine-tune auditory perception in a top-down fashion? We administered a standardized battery of perceptual and cognitive tests to adult musicians and non-musicians, including tasks either more or less susceptible to cognitive control (e.g., backward versus simultaneous masking) and more or less dependent on auditory or visual processing (e.g., auditory versus visual attention). Outcomes indicate lower perceptual thresholds in musicians specifically for auditory tasks that relate with cognitive abilities, such as backward masking and auditory attention. These enhancements were observed in the absence of group differences for the simultaneous masking and visual attention tasks. Our results suggest that long-term musical practice strengthens cognitive functions and that these functions benefit auditory skills. Musical training bolsters higher-level mechanisms that, when impaired, relate to language and literacy deficits. Thus, musical training may serve to lessen the impact of these deficits by strengthening the corticofugal system for hearing. 2009 Elsevier B.V. All rights reserved.

  8. Accumulation of evidence during sequential decision making: the importance of top-down factors.

    Science.gov (United States)

    de Lange, Floris P; Jensen, Ole; Dehaene, Stanislas

    2010-01-13

    In the last decade, great progress has been made in characterizing the accumulation of neural information during simple unitary perceptual decisions. However, much less is known about how sequentially presented evidence is integrated over time for successful decision making. The aim of this study was to study the mechanisms of sequential decision making in humans. In a magnetoencephalography (MEG) study, we presented healthy volunteers with sequences of centrally presented arrows. Sequence length varied between one and five arrows, and the accumulated directions of the arrows informed the subject about which hand to use for a button press at the end of the sequence (e.g., LRLRR should result in a right-hand press). Mathematical modeling suggested that nonlinear accumulation was the rational strategy for performing this task in the presence of no or little noise, whereas quasilinear accumulation was optimal in the presence of substantial noise. MEG recordings showed a correlate of evidence integration over parietal and central cortex that was inversely related to the amount of accumulated evidence (i.e., when more evidence was accumulated, neural activity for new stimuli was attenuated). This modulation of activity likely reflects a top-down influence on sensory processing, effectively constraining the influence of sensory information on the decision variable over time. The results indicate that, when making decisions on the basis of sequential information, the human nervous system integrates evidence in a nonlinear manner, using the amount of previously accumulated information to constrain the accumulation of additional evidence.

  9. The Temporal Pole Top-Down Modulates the Ventral Visual Stream During Social Cognition.

    Science.gov (United States)

    Pehrs, Corinna; Zaki, Jamil; Schlochtermeier, Lorna H; Jacobs, Arthur M; Kuchinke, Lars; Koelsch, Stefan

    2017-01-01

    The temporal pole (TP) has been associated with diverse functions of social cognition and emotion processing. Although the underlying mechanism remains elusive, one possibility is that TP acts as domain-general hub integrating socioemotional information. To test this, 26 participants were presented with 60 empathy-evoking film clips during fMRI scanning. The film clips were preceded by a linguistic sad or neutral context and half of the clips were accompanied by sad music. In line with its hypothesized role, TP was involved in the processing of sad context and furthermore tracked participants' empathic concern. To examine the neuromodulatory impact of TP, we applied nonlinear dynamic causal modeling to a multisensory integration network from previous work consisting of superior temporal gyrus (STG), fusiform gyrus (FG), and amygdala, which was extended by an additional node in the TP. Bayesian model comparison revealed a gating of STG and TP on fusiform-amygdalar coupling and an increase of TP to FG connectivity during the integration of contextual information. Moreover, these backward projections were strengthened by emotional music. The findings indicate that during social cognition, TP integrates information from different modalities and top-down modulates lower-level perceptual areas in the ventral visual stream as a function of integration demands. © The Author 2015. Published by Oxford University Press. All rights reserved. For Permissions, please e-mail: journals.permissions@oup.com.

  10. Critical appraisal of the top-down approach for vesicoureteral reflux.

    Science.gov (United States)

    Abdelhalim, Ahmed; Khoury, Antoine E

    2017-06-01

    Vesicoureteral reflux (VUR) has been linked to recurrent urinary tract infections (UTIs), renal scarring, hypertension, renal insufficiency and end-stage kidney disease. Different imaging strategies have been proposed to approach children presenting with UTI to sort out patients with significant VUR while minimizing patient morbidity, radiation exposure and financial burden. None of these imaging strategies is universally accepted. The"top-down approach" (TDA) aims at restricting the number of voiding cystourethrograms (VCUGs) and its associated morbidity while identifying patients with clinically-significant reflux. In this approach, children presenting with febrile UTIs are acutely investigated with dimercapto-succinic acid (DMSA) renal scans to identify patients with renal parenchymal inflammation. Those with evidence of renal affection are offered VCUG and late DMSA scan to identify VUR and permanent renal scarring, respectively. Although TDA could identify clinically-significant VUR with high sensitivity, it is not without limitations. The approach segregates patients based on the presence of DMSA cortical lesions omitting the morbidity and the economic burden of UTI. Additionally, some of DMSA lesions are attributed to congenital dysplasia and unrelated to UTI. Ionizing radiation exposure, financial costs, limited availability of DMSA scans in the acute setting, variability in interpreting the results and low yield of actionable findings on DMSA scans are some other limitations. In this review, we tried to address the drawbacks of the TDA and reinforce the value of patient-centered approach for VUR.

  11. Top-down Estimates of Biomass Burning Emissions of Black Carbon in the Western United States

    Science.gov (United States)

    Mao, Y.; Li, Q.; Randerson, J. T.; CHEN, D.; Zhang, L.; Liou, K.

    2012-12-01

    We apply a Bayesian linear inversion to derive top-down estimates of biomass burning emissions of black carbon (BC) in the western United States (WUS) for May-November 2006 by inverting surface BC concentrations from the IMPROVE network using the GEOS-Chem chemical transport model. Model simulations are conducted at both 2°×2.5° (globally) and 0.5°×0.667° (nested over North America) horizontal resolutions. We first improve the spatial distributions and seasonal and interannual variations of the BC emissions from the Global Fire Emissions Database (GFEDv2) using MODIS 8-day active fire counts from 2005-2007. The GFEDv2 emissions in N. America are adjusted for three zones: boreal N. America, temperate N. America, and Mexico plus Central America. The resulting emissions are then used as a priori for the inversion. The a posteriori emissions are 2-5 times higher than the a priori in California and the Rockies. Model surface BC concentrations using the a posteriori estimate provide better agreement with IMPROVE observations (~50% increase in the Taylor skill score), including improved ability to capture the observed variability especially during June-September. However, model surface BC concentrations are still biased low by ~30%. Comparisons with the Fire Locating and Modeling of Burning Emissions (FLAMBE) are included.

  12. Culture from the Bottom Up

    Science.gov (United States)

    Atkinson, Dwight; Sohn, Jija

    2013-01-01

    The culture concept has been severely criticized for its top-down nature in TESOL, leading arguably to its falling out of favor in the field. But what of the fact that people do "live culturally" (Ingold, 1994)? This article describes a case study of culture from the bottom up--culture as understood and enacted by its individual users.…

  13. From Bottom to Top: Identification to Precision Measurement of 3rd-Generation Quarks with the ATLAS Detector

    CERN Document Server

    AUTHOR|(INSPIRE)INSPIRE-00335926

    The 3rd-generation quarks, bottom ($b$) and top ($t$), are recent additions to the Standard Model of particle physics, and precise characterization of their properties have important implications to searching for new physics phenomena. This thesis presents two analyses which use 4.6 fb$^{-1}$ of $pp$ collision data at $\\sqrt{s} = 7$ TeV collected by the ATLAS detector at the Large Hadron Collider (LHC) to measure their properties. The first is an analysis which measures our ability to identify jets originating from $b$ quarks with machine-learning algorithms applied to simulated and real data, so the result in simulation can be corrected to match that in data. This measurement has implications for our ability to identify processes with b quarks in their final state; $t$ quarks decay to a $b$ quark and a weak vector boson $W$ more than 99% of the time. The second analysis presented measures properties of the $t \\rightarrow Wb$ decay channel associated with phenomena not predicted by the Standard Model, through...

  14. Top-down models in biology: explanation and control of complex living systems above the molecular level.

    Science.gov (United States)

    Pezzulo, Giovanni; Levin, Michael

    2016-11-01

    It is widely assumed in developmental biology and bioengineering that optimal understanding and control of complex living systems follows from models of molecular events. The success of reductionism has overshadowed attempts at top-down models and control policies in biological systems. However, other fields, including physics, engineering and neuroscience, have successfully used the explanations and models at higher levels of organization, including least-action principles in physics and control-theoretic models in computational neuroscience. Exploiting the dynamic regulation of pattern formation in embryogenesis and regeneration requires new approaches to understand how cells cooperate towards large-scale anatomical goal states. Here, we argue that top-down models of pattern homeostasis serve as proof of principle for extending the current paradigm beyond emergence and molecule-level rules. We define top-down control in a biological context, discuss the examples of how cognitive neuroscience and physics exploit these strategies, and illustrate areas in which they may offer significant advantages as complements to the mainstream paradigm. By targeting system controls at multiple levels of organization and demystifying goal-directed (cybernetic) processes, top-down strategies represent a roadmap for using the deep insights of other fields for transformative advances in regenerative medicine and systems bioengineering. © 2016 The Author(s).

  15. Dynamic ErbB4 Activity in Hippocampal-Prefrontal Synchrony and Top-Down Attention in Rodents.

    Science.gov (United States)

    Tan, Zhibing; Robinson, Heath L; Yin, Dong-Min; Liu, Yu; Liu, Fang; Wang, Hongsheng; Lin, Thiri W; Xing, Guanglin; Gan, Lin; Xiong, Wen-Cheng; Mei, Lin

    2018-04-18

    Top-down attention is crucial for meaningful behaviors and impaired in various mental disorders. However, its underpinning regulatory mechanisms are poorly understood. We demonstrate that the hippocampal-prefrontal synchrony associates with levels of top-down attention. Both attention and synchrony are reduced in mutant mice of ErbB4, a receptor of neuregulin-1. We used chemical genetic and optogenetic approaches to inactivate ErbB4 kinase and ErbB4+ interneurons, respectively, both of which reduce gamma-aminobutyric acid (GABA) activity. Such inhibitions in the hippocampus impair both hippocampal-prefrontal synchrony and top-down attention, whereas those in the prefrontal cortex alter attention, but not synchrony. These observations identify a role of ErbB4-dependent GABA activity in the hippocampus in synchronizing the hippocampal-prefrontal pathway and demonstrate that acute, dynamic ErbB4 signaling is required to command top-down attention. Because both neuregulin-1 and ErbB4 are susceptibility genes of schizophrenia and major depression, our study contributes to a better understanding of these disorders. VIDEO ABSTRACT. Copyright © 2018 Elsevier Inc. All rights reserved.

  16. The Effect of Non-Visual Working Memory Load on Top-Down Modulation of Visual Processing

    Science.gov (United States)

    Rissman, Jesse; Gazzaley, Adam; D'Esposito, Mark

    2009-01-01

    While a core function of the working memory (WM) system is the active maintenance of behaviorally relevant sensory representations, it is also critical that distracting stimuli are appropriately ignored. We used functional magnetic resonance imaging to examine the role of domain-general WM resources in the top-down attentional modulation of…

  17. Attention, working memory, and phenomenal experience of WM content: memory levels determined by different types of top-down modulation.

    Science.gov (United States)

    Jacob, Jane; Jacobs, Christianne; Silvanto, Juha

    2015-01-01

    What is the role of top-down attentional modulation in consciously accessing working memory (WM) content? In influential WM models, information can exist in different states, determined by allocation of attention; placing the original memory representation in the center of focused attention gives rise to conscious access. Here we discuss various lines of evidence indicating that such attentional modulation is not sufficient for memory content to be phenomenally experienced. We propose that, in addition to attentional modulation of the memory representation, another type of top-down modulation is required: suppression of all incoming visual information, via inhibition of early visual cortex. In this view, there are three distinct memory levels, as a function of the top-down control associated with them: (1) Nonattended, nonconscious associated with no attentional modulation; (2) attended, phenomenally nonconscious memory, associated with attentional enhancement of the actual memory trace; (3) attended, phenomenally conscious memory content, associated with enhancement of the memory trace and top-down suppression of all incoming visual input.

  18. Post-socialist agricultural cooperatives in Russia : A case study of top-down cooperatives in the Belgorod region

    NARCIS (Netherlands)

    A. Kurakin (Alexander); O. Visser (Oane)

    2017-01-01

    markdownabstractThrough a study of agricultural service cooperatives in Russia’s Belgorod region, this article addresses two gaps in the literature: _first_, the dearth of empirical studies on cooperatives in post-socialist Russia; _second_, the lack of attention to top-down cooperatives in

  19. Sodium-cutting: a new top-down approach to cut open nanostructures on nonplanar surfaces on a large scale.

    Science.gov (United States)

    Chen, Wei; Deng, Da

    2014-11-11

    We report a new, low-cost and simple top-down approach, "sodium-cutting", to cut and open nanostructures deposited on a nonplanar surface on a large scale. The feasibility of sodium-cutting was demonstrated with the successfully cutting open of ∼100% carbon nanospheres into nanobowls on a large scale from Sn@C nanospheres for the first time.

  20. Abrupt onsets capture attention independent of top-down control settings 11: Additivity is no evidence for filtering

    NARCIS (Netherlands)

    Schreij, D.; Theeuwes, J.; Olivers, C.N.L.

    2010-01-01

    Is attentional capture contingent on top-down control settings or involuntarily driven by salient stimuli? Supporting the stimulus-driven attentional capture view, Schreij, Owens, and Theeuwes (2008) found that an onset distractor caused a response delay, in spite of participants' having adopted an

  1. A mass graph-based approach for the identification of modified proteoforms using top-down tandem mass spectra.

    Science.gov (United States)

    Kou, Qiang; Wu, Si; Tolic, Nikola; Paša-Tolic, Ljiljana; Liu, Yunlong; Liu, Xiaowen

    2017-05-01

    Although proteomics has rapidly developed in the past decade, researchers are still in the early stage of exploring the world of complex proteoforms, which are protein products with various primary structure alterations resulting from gene mutations, alternative splicing, post-translational modifications, and other biological processes. Proteoform identification is essential to mapping proteoforms to their biological functions as well as discovering novel proteoforms and new protein functions. Top-down mass spectrometry is the method of choice for identifying complex proteoforms because it provides a 'bird's eye view' of intact proteoforms. The combinatorial explosion of various alterations on a protein may result in billions of possible proteoforms, making proteoform identification a challenging computational problem. We propose a new data structure, called the mass graph, for efficient representation of proteoforms and design mass graph alignment algorithms. We developed TopMG, a mass graph-based software tool for proteoform identification by top-down mass spectrometry. Experiments on top-down mass spectrometry datasets showed that TopMG outperformed existing methods in identifying complex proteoforms. http://proteomics.informatics.iupui.edu/software/topmg/. xwliu@iupui.edu. Supplementary data are available at Bioinformatics online. © The Author 2016. Published by Oxford University Press. All rights reserved. For Permissions, please e-mail: journals.permissions@oup.com

  2. Proton and photon absorbed-dose conversion coefficients for embryo and foetus from top-down irradiation geometry

    International Nuclear Information System (INIS)

    Chen, J.

    2007-01-01

    Absorbed-dose conversion coefficients are calculated for the embryo of 8 weeks and the foetus of 3, 6 or 9 months when the mother's body is exposed to protons and photons from top-down (TOP) direction. It provides data sets in addition to other standard irradiation geometries published previously. The TOP-irradiation geometry is considered here, because high-energy particles are often peaked from the TOP direction onboard aircraft. The results show that absorbed-doses from high-energy particles could be underestimated significantly if isotropic (ISO) irradiation geometry is assumed. For protons of 100 GeV, absorbed-doses from TOP irradiation are ∼2.3-2.9 times higher than the doses from ISO irradiation for different foetal ages. For 10 GeV photons, foetal doses from TOP irradiation are ∼6.8-12 times higher than the doses from ISO irradiation. The coefficients from TOP-irradiation geometry are given in wide energy ranges, from 100 MeV to 100 GeV for protons and from 50 V to 10 GeV for photons. They can, therefore, be used in various applications whenever exposure from the TOP-irradiation direction is concerned. (authors)

  3. Rehabilitation of gait after stroke: a review towards a top-down approach

    Science.gov (United States)

    2011-01-01

    This document provides a review of the techniques and therapies used in gait rehabilitation after stroke. It also examines the possible benefits of including assistive robotic devices and brain-computer interfaces in this field, according to a top-down approach, in which rehabilitation is driven by neural plasticity. The methods reviewed comprise classical gait rehabilitation techniques (neurophysiological and motor learning approaches), functional electrical stimulation (FES), robotic devices, and brain-computer interfaces (BCI). From the analysis of these approaches, we can draw the following conclusions. Regarding classical rehabilitation techniques, there is insufficient evidence to state that a particular approach is more effective in promoting gait recovery than other. Combination of different rehabilitation strategies seems to be more effective than over-ground gait training alone. Robotic devices need further research to show their suitability for walking training and their effects on over-ground gait. The use of FES combined with different walking retraining strategies has shown to result in improvements in hemiplegic gait. Reports on non-invasive BCIs for stroke recovery are limited to the rehabilitation of upper limbs; however, some works suggest that there might be a common mechanism which influences upper and lower limb recovery simultaneously, independently of the limb chosen for the rehabilitation therapy. Functional near infrared spectroscopy (fNIRS) enables researchers to detect signals from specific regions of the cortex during performance of motor activities for the development of future BCIs. Future research would make possible to analyze the impact of rehabilitation on brain plasticity, in order to adapt treatment resources to meet the needs of each patient and to optimize the recovery process. PMID:22165907

  4. Temperature effects on seaweed-sustaining top-down control vary with season.

    Science.gov (United States)

    Werner, Franziska J; Graiff, Angelika; Matthiessen, Birte

    2016-03-01

    Rising seawater temperature and CO2 concentrations (ocean acidification) represent two of the most influential factors impacting marine ecosystems in the face of global climate change. In ecological climate change research, full-factorial experiments performed across seasons in multispecies, cross-trophic-level settings are essential as they permit a more realistic estimation of direct and indirect effects as well as the relative importance of the effects of both major environmental stressors on ecosystems. In benthic mesocosm experiments, we tested the responses of coastal Baltic Sea Fucus vesiculosus communities to elevated seawater temperature and CO2 concentrations across four seasons of one year. While increasing [CO2] levels had only minor effects, warming had strong and persistent effects on grazers, and the resulting effects on the Fucus community were found to be season dependent. In late summer, a temperature-driven collapse of grazers caused a cascading effect from the consumers to the foundation species, resulting in overgrowth of Fucus thalli by epiphytes. In fall/winter (outside the growing season of epiphytes), intensified grazing under warming resulted in a significant reduction in Fucus biomass. Thus, we were able to confirm the prediction that future increases in water temperatures will influence marine food-web processes by altering top-down control, but we were also able to show that specific consequences for food-web structure depend on the season. Since F. vesiculosus is the dominant habitat-forming brown algal system in the Baltic Sea, its potential decline under global warming implies a loss of key functions and services such as provision of nutrient storage, substrate, food, shelter, and nursery grounds for a diverse community of marine invertebrates and fish in Baltic Sea coastal waters.

  5. Training set optimization and classifier performance in a top-down diabetic retinopathy screening system

    Science.gov (United States)

    Wigdahl, J.; Agurto, C.; Murray, V.; Barriga, S.; Soliz, P.

    2013-03-01

    Diabetic retinopathy (DR) affects more than 4.4 million Americans age 40 and over. Automatic screening for DR has shown to be an efficient and cost-effective way to lower the burden on the healthcare system, by triaging diabetic patients and ensuring timely care for those presenting with DR. Several supervised algorithms have been developed to detect pathologies related to DR, but little work has been done in determining the size of the training set that optimizes an algorithm's performance. In this paper we analyze the effect of the training sample size on the performance of a top-down DR screening algorithm for different types of statistical classifiers. Results are based on partial least squares (PLS), support vector machines (SVM), k-nearest neighbor (kNN), and Naïve Bayes classifiers. Our dataset consisted of digital retinal images collected from a total of 745 cases (595 controls, 150 with DR). We varied the number of normal controls in the training set, while keeping the number of DR samples constant, and repeated the procedure 10 times using randomized training sets to avoid bias. Results show increasing performance in terms of area under the ROC curve (AUC) when the number of DR subjects in the training set increased, with similar trends for each of the classifiers. Of these, PLS and k-NN had the highest average AUC. Lower standard deviation and a flattening of the AUC curve gives evidence that there is a limit to the learning ability of the classifiers and an optimal number of cases to train on.

  6. Rehabilitation of gait after stroke: a review towards a top-down approach

    Directory of Open Access Journals (Sweden)

    Belda-Lois Juan-Manuel

    2011-12-01

    Full Text Available Abstract This document provides a review of the techniques and therapies used in gait rehabilitation after stroke. It also examines the possible benefits of including assistive robotic devices and brain-computer interfaces in this field, according to a top-down approach, in which rehabilitation is driven by neural plasticity. The methods reviewed comprise classical gait rehabilitation techniques (neurophysiological and motor learning approaches, functional electrical stimulation (FES, robotic devices, and brain-computer interfaces (BCI. From the analysis of these approaches, we can draw the following conclusions. Regarding classical rehabilitation techniques, there is insufficient evidence to state that a particular approach is more effective in promoting gait recovery than other. Combination of different rehabil