scholarly journals Cholinergic Modulation of Hippocampally Mediated Attention and Perception

2020 ◽  
Author(s):  
Nicholas A. Ruiz ◽  
Monica Thieu ◽  
Mariam Aly
Keyword(s):  
Computational Models ◽  
Spatial Relations ◽  
Afferent Input ◽  
Hippocampal Damage ◽  
Cholinergic Modulation ◽  
Attention Task ◽  
Performance Improvements ◽  
The Past ◽  
Attention And Perception ◽  
Trial Participants

AbstractAttention to the relations between visual features modulates hippocampal representations. Moreover, hippocampal damage impairs discrimination of spatial relations. We explore a mechanism by which this might occur: modulation by the acetylcholine system. Acetylcholine enhances afferent input to the hippocampus and suppresses recurrent connections within it. This biases hippocampal processing toward environmental input, and should improve externally-oriented, hippocampally mediated attention and perception. We examined cholinergic modulation on an attention task that recruits the hippocampus. On each trial, participants viewed two images (rooms with paintings). On “similar room” trials, they judged whether the rooms had the same spatial layout from a different perspective. On “similar art” trials, they judged whether the paintings could have been painted by the same artist. On “identical” trials, participants simply had to detect identical paintings or rooms. We hypothesized that cholinergic modulation would improve performance on the similar room task, given past findings that hippocampal representations predicted, and hippocampal damage impaired, behavior on this task. To test this, nicotine cigarette smokers took part in two sessions: one before which they abstained from nicotine for 12 hours, and one before which they ingested nicotine in the past hour. Individual differences in expired breath carbon monoxide levels — a measure of how recently or how much someone smoked — predicted performance improvements on the similar room task. This finding provides novel support for computational models that propose that acetylcholine enhances externally oriented attentional states in the hippocampus.

scholarly journals The first 10 years of the international coordination network for standards in systems and synthetic biology (COMBINE)

2020 ◽  
Vol 17 (2-3) ◽  
Author(s):  
Dagmar Waltemath ◽  
Martin Golebiewski ◽  
Michael L Blinov ◽  
Padraig Gleeson ◽  
Henning Hermjakob ◽  
...  
Keyword(s):  
Synthetic Biology ◽  
Data Model ◽  
Computational Models ◽  
Life Sciences ◽  
The Past ◽  
Challenges And Opportunities ◽  
Stakeholder Workshop ◽  
Software Engineers ◽  
Future Work ◽  
Modeling In Biology

AbstractThis paper presents a report on outcomes of the 10th Computational Modeling in Biology Network (COMBINE) meeting that was held in Heidelberg, Germany, in July of 2019. The annual event brings together researchers, biocurators and software engineers to present recent results and discuss future work in the area of standards for systems and synthetic biology. The COMBINE initiative coordinates the development of various community standards and formats for computational models in the life sciences. Over the past 10 years, COMBINE has brought together standard communities that have further developed and harmonized their standards for better interoperability of models and data. COMBINE 2019 was co-located with a stakeholder workshop of the European EU-STANDS4PM initiative that aims at harmonized data and model standardization for in silico models in the field of personalized medicine, as well as with the FAIRDOM PALs meeting to discuss findable, accessible, interoperable and reusable (FAIR) data sharing. This report briefly describes the work discussed in invited and contributed talks as well as during breakout sessions. It also highlights recent advancements in data, model, and annotation standardization efforts. Finally, this report concludes with some challenges and opportunities that this community will face during the next 10 years.

Ore textures: problems and opportunities

1991 ◽  
Vol 55 (380) ◽  
pp. 303-315 ◽  
Author(s):  
Paul B. Barton
Keyword(s):  
Spatial Relations ◽  
Ore Deposits ◽  
Chemical Processes ◽  
Process Models ◽  
Textural Features ◽  
The Past ◽  
Geological Processes ◽  
Sequence Of Events ◽  
Definition Of ◽  
Scientific Endeavour

AbstractOver the past several decades, thinking about chemical processes in rocks had been dominated by experimental and theoretical treatments of mineral equilibrium, which is the state from which the time variable has been excluded. But, to an extent exceeding that of any of our sister sciences, we in geology are concerned with the behaviour of things as a function of time; thus equilibrium is but one of several interesting boundary conditions. Textures, (defined as the spatial relations within and among minerals and fluids, regardless of scale or origin) provide a means to sort out and identify successive states. In fact, it is the pattern of evolution of those states that enables us to deduce the processes. We may well draw the analogy with thermodynamics and kinetics, respectively:equilibrium textures and phase assemblages, via thermodynamic analysis → definition of conditions of equilibration,whereaskinetics, as displayed in disequilibrium textures → sequence of events and processes of mineralization.The interpretation of textures is one of the most difficult yet important aspects of the study of rocks and ores, and there are few areas of scientific endeavour that are more subject to misinterpretation. Although the difficulties are many, the opportunites for new understanding are also abundant. Textural interpretations have many facets: some are well established and accepted; some that are accepted may be wrong; others are recognised to be speculative and controversial; and we trust that still other textural features remain to be described and interpreted. This paper will deal principally with low-temperature, epigenetic ore deposits, and will emphasise silica and sphalerite; but extension to other materials is not unreasonable.Ore and gangue minerals react internally, or with their environment, at widely ranging rates, ranging from the almost inert pyrite, arsenopyrite, well-crystallised quartz, and tourmaline to the notoriously fickle copper/iron and copper/silver sulfides. Arrested or incomplete reactions may be identifed by textural criteria and, when appropriately quantified, can provide guides to the duration of geological processes.In recent years so much emphasis has been placed on isotopes, fluids, chemistry, and deposit and process models that the textural features have been ignored. In part this oversight occurs because we have grown accustomed to using superposition, cross-cutting, pseudomorphism, mutual intergrowths, exsolution and so on as off-the-shelf tools, to be grasped and applied without evaluation or even description. Surely science must build on previous work without constant and exhaustive reassessment, but for mineral textures a little reassessment may yield substantial benefit.

Recently-Developed Aluminium Solutions for Aerospace Applications

2006 ◽  
Vol 519-521 ◽  
pp. 1271-1278 ◽  
Author(s):  
Timothy Warner
Keyword(s):  
New Technologies ◽  
Damage Tolerance ◽  
Grain Structure ◽  
Space Applications ◽  
Metallic Structures ◽  
Performance Improvements ◽  
The Past ◽  
Aerospace Applications ◽  
Aerospace Alloys ◽  
Damage Tolerant

Two principal approaches are available to materials’ engineers to improve the overall cost-weight balance of metallic airframe structures: improving alloy performance and optimising materials’ utilisation. Although both approaches have been successful in the past, they are most effective when applied concomitantly. The Aluminium industry has a long record of improving aerospace alloys’ performance. Nevertheless, even in apparently well-explored alloy systems such as the 7xxx family, products with improved damage tolerance-strength balances have recently been developed, thanks to an improved understanding of the optimum Zn-Mg-Cu combinations for the required property balances but also to developments in casting capability. Novel dispersoids and dispersoid combinations have enabled further improvements of the performance of existing alloy families. For example, appropriate Sc and Zr additions have a significant impact on the grain structure of 2xxx alloys and thus on performance. Another high potential approach for alloy performance improvements is the optimisation of Al-Cu-Li-(Mg-Ag-Zn) alloys. These so-called “third generation Al-Li alloys” were principally developed for military and space applications; in order to meet the demands of future commercial airframes, more damage tolerant variants are being developed. AA2198 and AA2050 are used to illustrate the potential of these higher damage tolerance Al-Cu-Li alloys. However, materials performance improvements are only part of the potential developments of metallic solutions for airframes. Further gains of a similar magnitude in component weight and cost can be achieved by applying new technologies and new design solutions to metallic structures. The future of metallic airframes will depend on the concomitant application of both these approaches.

scholarly journals The language of mental images: Characterizing hippocampal contributions to imageable word use during event construction

2020 ◽  
Author(s):  
Elizabeth Race ◽  
Camille Carlisle ◽  
Ruchi Tejwani ◽  
Mieke Verfaellie
Keyword(s):  
Language Production ◽  
Long Term Memory ◽  
Hippocampal Damage ◽  
Healthy Controls ◽  
Term Memory ◽  
Word Use ◽  
The Past ◽  
Different Types ◽  
Imageable Word

AbstractAccumulating evidence suggests that the hippocampus plays a critical role in the creative and flexible use of language. For example, amnesic patients with hippocampal damage produce less coherent and cohesive verbal discourse when constructing narratives about the past, present, and future. A recent study by Hilverman and colleagues (2017) found that amnesic patients with hippocampal damage also use less imageable words during narrative construction compared to healthy controls. These results suggest that in addition to supporting language use at the discourse level, the hippocampus also influences the quality of language at the single word level. However, the generalizability of these results to different types of language production tasks and the relationship to patients’ broader impairments in episodic memory have yet to be examined. In the current study, we investigated whether amnesic patients with hippocampal damage produce less imageable words compared to healthy controls in two different types of language production tasks. In Experiment 1, participants constructed narratives about events depicted in visually presented pictures (picture narratives). In Experiment 2, participants constructed verbal narratives about remembered events from the past or simulated events in the future (past/future narratives). Across all types of narratives, patients produced words that were rated as having similar levels of imageability compared to controls. Importantly, this was the case both in patients’ picture narratives, which did not require generating details from long-term memory and were matched to controls’ with respect to narrative content, and in patients’ narratives about past/future events, which required generating details from long-term memory and which were reduced in narrative content compared to those of controls. These results reveal that the hippocampus is not necessary for the use of imageable representations at the linguistic level, and that hippocampal contributions to imageable word use are independent of hippocampal contributions to episodic memory.

scholarly journals Evolution of word meanings through metaphorical mapping: Systematicity over the past millennium.

2018 ◽  
Author(s):  
Yang Xu ◽  
Barbara Claire Malt ◽  
Mahesh Srinivasan
Keyword(s):  
Large Scale ◽  
Computational Models ◽  
Compact Set ◽  
Large Set ◽  
Word Meanings ◽  
The Past ◽  
History Of ◽  
Cognitive Principles ◽  
Metaphorical Mapping ◽  
Past Millennium

One way that languages are able to communicate a potentially infinite set of ideas through a finite lexicon is by compressing emerging meanings into words, such that over time, individual words come to express multiple, related senses of meaning. We propose that overarching communicative and cognitive pressures have created systematic directionality in how new metaphorical senses have developed from existing word senses over the history of English. Given a large set of pairs of semantic domains, we used computational models to test which domains have been more commonly the starting points (source domains) and which the ending points (target domains) of metaphorical mappings over the past millennium. We found that a compact set of variables, including externality, embodiment, and valence, explain directionality in the majority of about 5000 metaphorical mappings recorded over the past 1100 years. These results provide the first large-scale historical evidence that metaphorical mapping is systematic, and driven by measurable communicative and cognitive principles.

LATTICE STRUCTURE OPTIMIZATION WITH ORIENTATION-DEPENDENT MATERIAL PROPERTIES

2021 ◽  
pp. 1-33
Author(s):  
Conner Sharpe ◽  
Carolyn Seepersad
Keyword(s):  
Additive Manufacturing ◽  
Design Process ◽  
Material Properties ◽  
Computational Models ◽  
Lattice Structure ◽  
Lattice Structures ◽  
Performance Improvements ◽  
Structural Applications ◽  
Manufacturing Techniques ◽  
And Performance

Abstract Advances in additive manufacturing techniques have enabled the production of parts with complex internal geometries. However, the layer-based nature of additive processes often results in mechanical properties that vary based on the orientation of the feature relative to the build plane. Lattice structures have been a popular design application for additive manufacturing due to their potential uses in lightweight structural applications. Many recent works have explored the modeling, design, and fabrication challenges that arise in the multiscale setting of lattice structures. However, there remains a significant challenge in bridging the simplified computational models used in the design process and the more complex properties actually realized in fabrication. This work develops a design approach that captures orientation-dependent material properties that have been observed in metal AM processes while remaining suitable for use in an iterative design process. Exemplar problems are utilized to investigate the potential design changes and performance improvements that can be attained by taking the directional dependence of the manufacturing process into account in the design of lattice structures.

Combination of Forecasts in Data Mining

2011 ◽  
pp. 589-593
Author(s):  
Chi Kin Chan
Keyword(s):  
Data Mining ◽  
Traditional Approach ◽  
Forecast Accuracy ◽  
Performance Improvements ◽  
The Past ◽  
Aggregate Information ◽  
Forecasting Methods ◽  
Forecasting Method ◽  
Combination Of Forecasts ◽  
Single Method

The traditional approach to forecasting involves choosing the forecasting method judged most appropriate of the available methods and applying it to some specific situations. The choice of a method depends upon the characteristics of the series and the type of application. The rationale behind such an approach is the notion that a “best” method exists and can be identified. Further that the “best” method for the past will continue to be the best for the future. An alternative to the traditional approach is to aggregate information from different forecasting methods by aggregating forecasts. This eliminates the problem of having to select a single method and rely exclusively on its forecasts. Considerable literature has accumulated over the years regarding the combination of forecasts. The primary conclusion of this line of research is that combining multiple forecasts leads to increased forecast accuracy. This has been the result whether the forecasts are judgmental or statistical, econometric or extrapolation. Furthermore, in many cases one can make dramatic performance improvements by simply averaging the forecasts.

Lattice Structure Optimization With Orientation-Dependent Material Properties

2020 ◽  
Author(s):  
Conner Sharpe ◽  
Carolyn Conner Seepersad
Keyword(s):  
Additive Manufacturing ◽  
Design Process ◽  
Material Properties ◽  
Computational Models ◽  
Lattice Structure ◽  
Lattice Structures ◽  
Performance Improvements ◽  
Structural Applications ◽  
Manufacturing Techniques ◽  
And Performance

Abstract Advances in additive manufacturing techniques have enabled the production of parts with complex internal geometries. However, the layer-based nature of additive processes often results in mechanical properties that vary based on the orientation of the feature relative to the build plane. Lattice structures have been a popular design application for additive manufacturing due to their potential uses in lightweight structural applications. Many recent works have explored the modeling, design, and fabrication challenges that arise in the multiscale setting of lattice structures. However, there remains a significant challenge in bridging the simplified computational models used in the design process and the more complex properties actually realized in fabrication. This work develops a design approach that captures orientation-dependent material properties that have been observed in metal AM processes while remaining suitable for use in an iterative design process. Exemplar problems are utilized to investigate the potential design changes and performance improvements that can be attained by taking the directional dependence of the manufacturing process into account in the design of lattice structures.

Performance Improvements at the Boardman Coal Plant as a Result of Testing and Input/Loss Monitoring

2002 ◽  
Author(s):  
David A. T. Rodgers ◽  
Fred D. Lang
Keyword(s):  
Systems Approach ◽  
Heat Rate ◽  
Powder River Basin ◽  
Heating Value ◽  
Performance Improvements ◽  
The Past ◽  
Second Law Analysis ◽  
On Line ◽  
Loss Method ◽  
The Impact

This paper presents methods and practices of improving heat rate through testing and, most importantly, through heat rate monitoring. This work was preformed at Portland General Electric’s 585 MWe Boardman Coal Plant, which used two very different Powder River Basin and Utah coals ranging from 8,100 to over 12,500 Btu/lbm. Such fuel variability, common now among coal-fired units was successfully addressed by Boardman’s on-line monitoring techniques. Monitoring has evolved over the past ten years from a Controllable Parameters approach (offering disconnected guidance), to a systems approach in which fuel chemistry and heating value are determined on-line, their results serving as a bases for Second Law analysis. At Boardman on-line monitoring was implemented through Exergetic System’s Input/Loss Method. Boardman was one of the first half-dozen plants to fully implement Input/Loss. This paper teaches through discussion of eight in-plant examples. These examples discuss heat rate improvements involving both operational configurations and plant components: from determining changes in coal chemistry and composite heating value on-line; to recognizing the impact of individual rows of burners and pulverizer configurations; to air leakage identifications; to examples of hour-by-hour heat rate improvements; comparison to effluent flows; etc. All of these cases have applicability to any coal-fired unit.

scholarly journals The effect of hippocampal damage in children on recalling the past and imagining new experiences

2011 ◽  
Vol 49 (7) ◽  
pp. 1843-1850 ◽  
Author(s):  
Janine M. Cooper ◽  
Faraneh Vargha-Khadem ◽  
David G. Gadian ◽  
Eleanor A. Maguire
Keyword(s):  
Hippocampal Damage ◽  
The Past
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