Journal articles on the topic 'Evidence accumulation modelling'
To see the other types of publications on this topic, follow the link: Evidence accumulation modelling.
Create a spot-on reference in APA, MLA, Chicago, Harvard, and other styles
Consult the top 50 journal articles for your research on the topic 'Evidence accumulation modelling.'
Next to every source in the list of references, there is an 'Add to bibliography' button. Press on it, and we will generate automatically the bibliographic reference to the chosen work in the citation style you need: APA, MLA, Harvard, Chicago, Vancouver, etc.
You can also download the full text of the academic publication as pdf and read online its abstract whenever available in the metadata.
Browse journal articles on a wide variety of disciplines and organise your bibliography correctly.
1
Karamched, Bhargav, Simon Stolarczyk, Zachary P. Kilpatrick, and Krešimir Josić. "Bayesian Evidence Accumulation on Social Networks." SIAM Journal on Applied Dynamical Systems 19, no. 3 (January 2020): 1884–919. http://dx.doi.org/10.1137/19m1283793.
Full text
2
Tipples, Jason, Michael Lupton, and David George. "Speeding up Time: Hierarchical Bayesian Drift Diffusion Modelling Evidence for Accelerating Temporal Accumulation." Timing & Time Perception 9, no. 4 (April 13, 2021): 393–416. http://dx.doi.org/10.1163/22134468-bja10030.
Full textAbstract:
Abstract Time perception is malleable ‒ it can be made to speed up and slow down by various experimental manipulations including the presentation of a sequence of auditory clicks and also angry facial expressions. Recent evidence supports the idea that auditory click trains increase accumulation of evidence across time. Here, we test this idea for both angry expressions and auditory clicks by modelling response times (and choice responses) using Bayesian Hierarchical Drift Diffusion Modelling. Two separate groups of participants (Experiment 1; n = 29; Experiment 2; n = 38) judged the duration of angry and neutral facial expressions preceded by either a 3-s sequence of auditory clicks or silence. In both experiments, standard psychophysical analyses showed that both clicks and angry expressions lengthened the perception of time. The original finding came from the analyses of the Drift Diffusion Modelling parameter that represents the speed of information accumulation ‒ the drift rate parameter. Drift rates grew in magnitude with the duration of the face and moreover this effect was larger when the faces were either preceded by clicks or appeared angry ‒ evidence for accelerating temporal accumulation. This novel insight would not have been possible from traditional psychophysical analyses and therefore, the results highlight the potential value of Bayesian Hierarchical Drift Diffusion Modelling as a tool for understanding how we perceive time.
3
Tipples, Jason. "Rapid temporal accumulation in spider fear: Evidence from hierarchical drift diffusion modelling." Emotion 15, no. 6 (2015): 742–51. http://dx.doi.org/10.1037/emo0000079.
Full text
4
Abbott, M. B., J. Larsen, and Jianhua Tao. "Modelling circulations in depth-integrated flows Part 1: The accumulation of the evidence." Journal of Hydraulic Research 23, no. 4 (August 1985): 309–26. http://dx.doi.org/10.1080/00221688509499342.
Full text
5
Xiao, Xuewei, Honghan Chen, Chunquan Li, Xiuyan Liu, Zecheng Wang, and Hua Jiang. "Fluid Inclusion Evidence for Oil Charge and Cracking in the Cambrian Longwangmiao Dolomite Reservoirs of the Central Sichuan Basin, China." Geofluids 2022 (April 15, 2022): 1–18. http://dx.doi.org/10.1155/2022/3019100.
Full textAbstract:
The Cambrian Longwangmiao gas reservoirs in the Moxi area of the Sichuan Basin have a complex associated gas accumulation history. Based on core and thin section examination, fluid inclusion analyses and 1-D burial-thermal modelling, the diagenetic evolution and hydrocarbon accumulation processes in the Longwangmiao Formation have been reconstructed. Various diagenetic events were identified, making up a complete pore fill sequence as follows: solid bitumen/dolomite→ nonfluorescent solid bitumen → dolomite → quartz/yellow fluorescent oily bitumen → residual hole. Analyses of oil inclusions and bitumen-bearing inclusions are key to the understanding of the hydrocarbon accumulation processes. The Th values of the aqueous inclusions that are contemporaneous with hydrocarbon inclusions range from 74.3 to 214.3°C. In conjunction with burial-thermal history modelling results, the results indicate that there were two stages of oil charge and three stages of natural gas accumulation in the Longwangmiao carbonate reservoirs. The two stages of oil charge occurred in the Late Silurian and Middle Triassic, respectively. Three gas accumulation events occurred in the Middle to Late Triassic, Middle Jurassic to Early Cretaceous, and Late Cretaceous, respectively.
6
Davidson, Jacob D., and Ahmed El Hady. "Foraging as an evidence accumulation process." PLOS Computational Biology 15, no. 7 (July 24, 2019): e1007060. http://dx.doi.org/10.1371/journal.pcbi.1007060.
Full text
7
Markkula, Gustav, Zeynep Uludağ, Richard McGilchrist Wilkie, and Jac Billington. "Accumulation of continuously time-varying sensory evidence constrains neural and behavioral responses in human collision threat detection." PLOS Computational Biology 17, no. 7 (July 15, 2021): e1009096. http://dx.doi.org/10.1371/journal.pcbi.1009096.
Full textAbstract:
Evidence accumulation models provide a dominant account of human decision-making, and have been particularly successful at explaining behavioral and neural data in laboratory paradigms using abstract, stationary stimuli. It has been proposed, but with limited in-depth investigation so far, that similar decision-making mechanisms are involved in tasks of a more embodied nature, such as movement and locomotion, by directly accumulating externally measurable sensory quantities of which the precise, typically continuously time-varying, magnitudes are important for successful behavior. Here, we leverage collision threat detection as a task which is ecologically relevant in this sense, but which can also be rigorously observed and modelled in a laboratory setting. Conventionally, it is assumed that humans are limited in this task by a perceptual threshold on the optical expansion rate–the visual looming–of the obstacle. Using concurrent recordings of EEG and behavioral responses, we disprove this conventional assumption, and instead provide strong evidence that humans detect collision threats by accumulating the continuously time-varying visual looming signal. Generalizing existing accumulator model assumptions from stationary to time-varying sensory evidence, we show that our model accounts for previously unexplained empirical observations and full distributions of detection response. We replicate a pre-response centroparietal positivity (CPP) in scalp potentials, which has previously been found to correlate with accumulated decision evidence. In contrast with these existing findings, we show that our model is capable of predicting the onset of the CPP signature rather than its buildup, suggesting that neural evidence accumulation is implemented differently, possibly in distinct brain regions, in collision detection compared to previously studied paradigms.
8
Gesiarz, Filip, Donal Cahill, and Tali Sharot. "Evidence accumulation is biased by motivation: A computational account." PLOS Computational Biology 15, no. 6 (June 27, 2019): e1007089. http://dx.doi.org/10.1371/journal.pcbi.1007089.
Full text
9
Perea, Manuel, Ana Marcet, Marta Vergara-Martínez, and Pablo Gomez. "On the limits of familiarity accounts in lexical decision: The case of repetition effects." Quarterly Journal of Experimental Psychology 73, no. 3 (September 25, 2019): 375–83. http://dx.doi.org/10.1177/1747021819878385.
Full textAbstract:
Recent modelling accounts of the lexical decision task have suggested that the reading system performs evidence accumulation to carry out some functions. Evidence accumulation models have been very successful in accounting for effects in the lexical decision task, including the dissociation of repetition effects for words and nonwords (facilitative for words but inhibitory for nonwords). The familiarity of a repeated item triggers its recognition, which facilitates ‘word’ responses but hampers nonword rejection. However, reports of facilitative repetition effects for nonwords with several repetitions in short blocks challenge this hypothesis and favour models based on episodic retrieval. To shed light on the nature of the repetition effects for nonwords in lexical decision, we conducted four experiments to examine the impact of extra-lexical source of information—we induced the use of episodic retrieval traces via instructions and list composition. When the initial block was long, the repetition effect for nonwords was inhibitory, regardless of the instructions and list composition. However, the inhibitory effect was dramatically reduced when the initial block included two presentations of the stimuli and it was even facilitatory when the initial block was short. This composite pattern suggests that evidence accumulation models of lexical decision should take into account all sources of evidence—including episodic retrieval—during the process of lexical decision.
10
John, Amber, Sarah-Naomi James, Urvisha Patel, Jennifer Rusted, Marcus Richards, and Darya Gaysina. "Longitudinal associations of affective symptoms with mid-life cognitive function: evidence from a British birth cohort." British Journal of Psychiatry 215, no. 5 (March 21, 2019): 675–82. http://dx.doi.org/10.1192/bjp.2019.24.
Full textAbstract:
BackgroundAffective disorders are associated with poorer cognition in older adults; however, whether this association can already be observed in mid-life remains unclear.AimsTo investigate the effects of affective symptoms over a period of 30 years on mid-life cognitive function. First, we explored whether timing (sensitive period) or persistence (accumulation) of affective symptoms predicted cognitive function. Second, we tested how different longitudinal trajectories of affective symptoms were associated with cognitive function.MethodThe study used data from the National Child Development Study. Memory, verbal fluency, information processing speed and accuracy were measured at age 50. Affective symptoms were measured at ages 23, 33, 42 and 50 and used to derive longitudinal trajectories. A structured modelling approach compared a set of nested models in order to test accumulation versus sensitive period hypotheses. Linear regressions and structural equation modelling were used to test for longitudinal associations of affective symptoms with cognitive function.ResultsAccumulation of affective symptoms was found to be the best fit for the data, with persistent affective symptoms being associated with poorer immediate memory (b = −0.07, s.e. = 0.03, P = 0.01), delayed memory (b = −0.13, s.e. = 0.04, P < 0.001) and information processing accuracy (b = 0.18, s.e. = 0.08, P = 0.03), but not with information processing speed (b = 3.15, s.e. = 1.89, P = 0.10). Longitudinal trajectories of repeated affective symptoms were associated with poorer memory, verbal fluency and information processing accuracy.ConclusionsPersistent affective symptoms can affect cognitive function in mid-life. Effective management of affective disorders to prevent recurrence may reduce risk of poor cognitive outcomes and promote healthy cognitive ageing.Declaration of interestNone.
11
Hoh, Choon-Yee, and Ralf Cord-Ruwisch. "Experimental evidence for the need of thermodynamic considerations in modelling of anaerobic environmental bioprocesses." Water Science and Technology 36, no. 10 (November 1, 1997): 109–15. http://dx.doi.org/10.2166/wst.1997.0370.
Full textAbstract:
For modeling of biological processes that operate close to the dynamic equilibrium (eg. anaerobic processes), it is critical to prevent the prediction of positive reaction rates when the reaction has already reached dynamic equilibrium. Traditional Michaelis-Menten based models were found to violate the laws of thermodynamics as they predicted positive reaction rates for reactions that were endergonic due to high endproduct concentrations. The inclusion of empirical “product inhibition factors” as suggested by previous work could not prevent this problem. This paper compares the predictions of the Michaelis-Menten Model (with and without product inhibition factors) and the Equilibrium Based Model (which has a thermodynamic term introduced into its rate equation) with experimental results of reactions in anaerobic bacterial environments. In contrast to the Michaelis-Menten based models that used traditional inhibition factors, the Equilibrium Based Model correctly predicted the nature and the degree of inhibition due to endproduct accumulation. Moreover, this model also correctly predicted when reaction rates must be zero due to the free energy change of the conversion reaction being zero. With these added advantages, the Equilibrium Based Model thus seemed to provide a scientifically correct and more realistic basis for a variety of models that describe anaerobic biosystems.
12
Bronfman, Zohar Z., Noam Brezis, Rani Moran, Konstantinos Tsetsos, Tobias Donner, and Marius Usher. "Decisions reduce sensitivity to subsequent information." Proceedings of the Royal Society B: Biological Sciences 282, no. 1810 (July 7, 2015): 20150228. http://dx.doi.org/10.1098/rspb.2015.0228.
Full textAbstract:
Behavioural studies over half a century indicate that making categorical choices alters beliefs about the state of the world. People seem biased to confirm previous choices, and to suppress contradicting information. These choice-dependent biases imply a fundamental bound of human rationality. However, it remains unclear whether these effects extend to lower level decisions, and only little is known about the computational mechanisms underlying them. Building on the framework of sequential-sampling models of decision-making, we developed novel psychophysical protocols that enable us to dissect quantitatively how choices affect the way decision-makers accumulate additional noisy evidence. We find robust choice-induced biases in the accumulation of abstract numerical (experiment 1) and low-level perceptual (experiment 2) evidence. These biases deteriorate estimations of the mean value of the numerical sequence (experiment 1) and reduce the likelihood to revise decisions (experiment 2). Computational modelling reveals that choices trigger a reduction of sensitivity to subsequent evidence via multiplicative gain modulation, rather than shifting the decision variable towards the chosen alternative in an additive fashion. Our results thus show that categorical choices alter the evidence accumulation mechanism itself, rather than just its outcome, rendering the decision-maker less sensitive to new information.
13
Hausmann, Daniel, and Damian Läge. "Sequential evidence accumulation in decision making: The individual desired level of confidence can explain the extent of information acquisition." Judgment and Decision Making 3, no. 3 (March 2008): 229–43. http://dx.doi.org/10.1017/s1930297500002436.
Full textAbstract:
AbstractJudgments and decisions under uncertainty are frequently linked to a prior sequential search for relevant information. In such cases, the subject has to decide when to stop the search for information. Evidence accumulation models from social and cognitive psychology assume an active and sequential information search until enough evidence has been accumulated to pass a decision threshold. In line with such theories, we conceptualize the evidence threshold as the “desired level of confidence” (DLC) of a person. This model is tested against a fixed stopping rule (one-reason decision making) and against the class of multi-attribute information integrating models. A series of experiments using an information board for horse race betting demonstrates an advantage of the proposed model by measuring the individual DLC of each subject and confirming its correctness in two separate stages. In addition to a better understanding of the stopping rule (within the narrow framework of simple heuristics), the results indicate that individual aspiration levels might be a relevant factor when modelling decision making by task analysis of statistical environments.
14
Orhon, D., N. Artan, and Y. Cimşit. "The Concept of Soluble Residual Product Formation in the Modelling of Activated Sludge." Water Science and Technology 21, no. 4-5 (April 1, 1989): 339–50. http://dx.doi.org/10.2166/wst.1989.0236.
Full textAbstract:
The soluble effluent COD of a well operated activated sludge plant is likely to be composed almost entirely of organic matter generated by microbial activity. There is evidence to show that a significant portion of this soluble organic matter is non-degradable and may be due to similar microbial mechanisms. A model for the formation of these soluble residual products, (SRP), is propose'd, relating the SRP formation to the hydrolysis of non-viable cellular materials in the reactor. The set of equations describing the model are successfully calibrated and verified for a set of representative experimental data derived from Sequencing Batch Reactors. The model is found to explain and predict COD accumulation at the end of each cycle of these activated sludge systems.
15
Nguyen, Quynh-Anh, John Rinzel, and Rodica Curtu. "Buildup and bistability in auditory streaming as an evidence accumulation process with saturation." PLOS Computational Biology 16, no. 8 (August 27, 2020): e1008152. http://dx.doi.org/10.1371/journal.pcbi.1008152.
Full text
16
Buzzard, Sammie, Daniel Feltham, and Daniela Flocco. "Modelling the fate of surface melt on the Larsen C Ice Shelf." Cryosphere 12, no. 11 (November 19, 2018): 3565–75. http://dx.doi.org/10.5194/tc-12-3565-2018.
Full textAbstract:
Abstract. Surface melt lakes lower the albedo of ice shelves, leading to additional surface melting. This can substantially alter the surface energy balance and internal temperature and density profiles of the ice shelf. Evidence suggests that melt lakes also played a pivotal role in the sudden collapse of the Larsen B Ice Shelf in 2002. Here a recently developed, high-physical-fidelity model accounting for the development cycle of melt lakes is applied to the Larsen C Ice Shelf, Antarctica's most northern ice shelf and one where melt lakes have been observed. We simulate current conditions on the ice shelf using weather station and reanalysis data and investigate the impacts of potential future increases in precipitation and air temperature on melt lake formation, for which concurrent increases lead to an increase in lake depth. Finally, we assess the viability in future crevasse propagation through the ice shelf due to surface meltwater accumulation.
17
Pirrone, Angelo, James A. R. Marshall, and Tom Stafford. "A drift diffusion model account of the semantic congruity effect in a classification paradigm." Journal of Numerical Cognition 3, no. 1 (July 21, 2017): 77–96. http://dx.doi.org/10.5964/jnc.v3i1.79.
Full textAbstract:
The semantic congruity effect refers to the facilitation of judgements (i) when the direction of the comparison of two items coincides with the relative position of the items along the dimension comparison or (ii) when the relative size of a standard and a target stimulus coincides. For example, people are faster in judging 'which is bigger?' for two large items, than judging 'which is smaller?' for two large items (selection paradigm). Also, people are faster in judging a target stimulus as smaller when compared to a small standard, than when compared to a large standard, and vice versa (classification paradigm). We use the Drift Diffusion Model (DDM) to explain the time course of a semantic congruity effect in a classification paradigm. Formal modelling of semantic congruity allows the time course of the decision process to be described, using an established model of decision making. Moreover, although there have been attempts to explain the semantic congruity effect within evidence accumulation models, two possible accounts for the congruity effect have been proposed but their specific predictions have not been compared directly, using a model that could quantitatively account for both; a shift in the starting point of evidence accumulation or a change in the rate at which evidence is accumulated. With our computational investigation we provide evidence for the latter, while controlling for other possible explanations such as a variation in non-decision time or boundary separation, that have not been taken into account in the explanation of this phenomenon.
18
Cezard, Genevieve, Calum Thomas McHale, Frank Sullivan, Juliana Kuster Filipe Bowles, and Katherine Keenan. "Studying trajectories of multimorbidity: a systematic scoping review of longitudinal approaches and evidence." BMJ Open 11, no. 11 (November 2021): e048485. http://dx.doi.org/10.1136/bmjopen-2020-048485.
Full textAbstract:
ObjectivesMultimorbidity—the co-occurrence of at least two chronic diseases in an individual—is an important public health challenge in ageing societies. The vast majority of multimorbidity research takes a cross-sectional approach, but longitudinal approaches to understanding multimorbidity are an emerging research area, being encouraged by multiple funders. To support development in this research area, the aim of this study is to scope the methodological approaches and substantive findings of studies that have investigated longitudinal multimorbidity trajectories.DesignWe conducted a systematic search for relevant studies in four online databases (Medline, Scopus, Web of Science and Embase) in May 2020 using predefined search terms and inclusion and exclusion criteria. The search was complemented by searching reference lists of relevant papers. From the selected studies, we systematically extracted data on study methodology and findings and summarised them in a narrative synthesis.ResultsWe identified 35 studies investigating multimorbidity longitudinally, all published in the last decade, and predominantly in high-income countries from the Global North. Longitudinal approaches employed included constructing change variables, multilevel regression analysis (eg, growth curve modelling), longitudinal group-based methodologies (eg, latent class modelling), analysing disease transitions and visualisation techniques. Commonly identified risk factors for multimorbidity onset and progression were older age, higher socioeconomic and area-level deprivation, overweight and poorer health behaviours.ConclusionThe nascent research area employs a diverse range of longitudinal approaches that characterise accumulation and disease combinations and to a lesser extent disease sequencing and progression. Gaps include understanding the long-term, life course determinants of different multimorbidity trajectories, and doing so across diverse populations, including those from low-income and middle-income countries. This can provide a detailed picture of morbidity development, with important implications from a clinical and intervention perspective.
19
Xie, Shuyun, Ning Huang, Jun Deng, Songle Wu, Mingguo Zhan, Emmanuel John M. Carranza, Yuepeng Zhang, and Fanxing Meng. "Quantitative prediction of prospectivity for Pb–Zn deposits in Guangxi (China) by back-propagation neural network and fuzzy weights-of-evidence modelling." Geochemistry: Exploration, Environment, Analysis 22, no. 2 (January 25, 2022): geochem2021–085. http://dx.doi.org/10.1144/geochem2021-085.
Full textAbstract:
One significant geochemical data processing aim is to delineate anomalies associated with mineral deposits. In areas with strong surface weathering, the accumulation centres of surface geochemical anomalies are often not completely matched with locations of mineral deposits. This affects anomaly interpretation and mineral prospectivity prediction. In order to solve this challenging problem, quantitative prediction of mineral prospectivity based on multi-information fusion techniques has been one of the research hotspots in the field of data analysis in recent years. This study first summarized the geological background and metallogenic control factors of each tectonic unit in Guangxi, and then analysed the relationship between Pb–Zn deposits and Pb–Zn geochemical anomalies from 60 767 geochemical stream sediment samples. Based on the re-classified geochemical element contents, gravity, aeromagnetic data and fault, magmatic rock, magmatic rock and fault intersection buffer data as input layers, together with 302 Pb–Zn ore occurrences selected as training data sets, quantitative prediction of prospectivity for Pb–Zn ore deposits in the study area was carried out using back-propagation neural network and fuzzy weights-of-evidence methods. It was found that the Pb–Zn mineral prospectivity prediction areas based on multi-information fusion techniques can eliminate effectively the influence of secondary accumulation of elements during weathering of carbonate rocks on the recognition of deposit-associated stream sediment geochemical anomalies, and identify effectively the mineral resources closely related to rock mass and structure distribution. These analyses reveal the metallogenic regularity of Pb–Zn deposits from the perspective of data mining based on machine learning and geographical information system multi-information fusion for delineation of prospective metallogenic target areas. The purpose here was to provide new ideas for reducing the effects of secondary weathering of extensive carbonate rocks in Guangxi, and in other regions with similar landscapes, on mineral prospectivity prediction.Thematic collection: This article is part of the Applications of innovations in geochemical data analysis collection available at: https://www.lyellcollection.org/cc/applications-of-innovations-in-geochemical-data-analysis
20
Payne, A. J., and D. J. Baldwin. "Thermomechanical modelling of the Scandinavian ice sheet: implications for ice-stream formation." Annals of Glaciology 28 (1999): 83–89. http://dx.doi.org/10.3189/172756499781821733.
Full textAbstract:
AbstractThis work attempts to explain the fan-like landform assemblages observed in satellite images of the area covered by the former Scandinavian ice sheet (SIS). These assemblages have been interpreted as evidence of large ice streams within the SIS. If this interpretation is correct, then it calls into doubt current theories on the formation of ice streams. These theories regard soft sediment and topographic troughs as being the key determinants of ice-stream location. Neither can be used to explain the existence of ice streams on the flat, hard-rock area of the Baltic Shield. Initial results from a three-dimensional, thermomechanical ice-sheet model indicate that interactions between ice flow, form and temperature can create patterns similar to those mentioned above. The model uses a realistic, 20 km resolution gridded topography and a simple parameterization of accumulation and ablation. It produces patterns of maximum ice-sheet extent, which are similar to those reconstructed from the area’s glacial geomorphology. Flow in the maximum, equilibrium ice sheet is dominated by wedges of warm, low-viscosity, fast-flowing ice. These are separated by areas of cold, slow-flowing ice. This patterning appears to develop spontaneously as the modelled ice sheet grows.
21
Golla, Sandeep SV, Sander CJ Verfaillie, Ronald Boellaard, Sofie M. Adriaanse, Marissa D. Zwan, Robert C. Schuit, Tessa Timmers, et al. "Quantification of [18F]florbetapir: A test–retest tracer kinetic modelling study." Journal of Cerebral Blood Flow & Metabolism 39, no. 11 (June 13, 2018): 2172–80. http://dx.doi.org/10.1177/0271678x18783628.
Full textAbstract:
Accumulation of amyloid beta can be visualized using [18F]florbetapir positron emission tomography. The aim of this study was to identify the optimal model for quantifying [18F]florbetapir uptake and to assess test–retest reliability of corresponding outcome measures. Eight Alzheimer’s disease patients (age: 67 ± 6 years, Mini-Mental State Examination (MMSE): 23 ± 3) and eight controls (age: 63 ± 4 years, MMSE: 30 ± 0) were included. Ninety-minute dynamic positron emission tomography scans, together with arterial blood sampling, were acquired immediately following a bolus injection of 294 ± 32 MBq [18F]florbetapir. Several plasma input models and the simplified reference tissue model (SRTM) were evaluated. The Akaike information criterion was used to identify the preferred kinetic model. Compared to controls, Alzheimer’s disease patients had lower MMSE scores and evidence for cortical Aβ pathology. A reversible two-tissue compartment model with fitted blood volume fraction (2T4k_VB) was the preferred model for describing [18F]florbetapir kinetics. SRTM-derived non-displaceable binding potential (BPND) correlated well (r2 = 0.83, slope = 0.86) with plasma input-derived distribution volume ratio. Test–retest reliability for plasma input-derived distribution volume ratio, SRTM-derived BPND and SUVr(50–70) were r = 0.88, r = 0.91 and r = 0.86, respectively. In vivo kinetics of [18F]florbetapir could best be described by a reversible two-tissue compartmental model and [18F]florbetapir BPND can be reliably estimated using an SRTM.
22
Mason, R. M., J. K. Martin, P. N. Smith, and B. D. Turland. "Comparison of a post-closure transient criticality model with the Oklo natural reactors." Mineralogical Magazine 76, no. 8 (December 2012): 3145–53. http://dx.doi.org/10.1180/minmag.2012.076.8.28.
Full textAbstract:
AbstractIn support of the disposal system safety case for a geological disposal facility (GDF) there is a requirement to consider 'what-if' hypothetical scenarios for post-closure nuclear criticality. Although all such scenarios are considered very unlikely, one 'what-if' scenario is the mobilization of fissile material from a number of waste packages and its slow accumulation within the GDF or the immediate surroundings. Should sufficient fissile material accumulate a quasi-steady-state (QSS) transient criticality event could result. A computer model has been developed to understand the evolution and consequences of such an event.Since a postulated QSS criticality could persist for many millennia, building confidence in the modelling approach is difficult. However, the Oklo natural reactors in Africa operated for similar durations around two billion years ago, providing a natural analogue for comparison. This paper describes the modelling approach, its application to hypothetical criticality events for a GDF, and how the model can be compared to Oklo. The model results are found to be in agreement with the observational evidence from Oklo, building confidence in the use of the QSS model to simulate postulated post-closure criticality events in GDFs.
23
Pirrone, Angelo, Andreagiovanni Reina, and Fernand Gobet. "Input-dependent noise can explain magnitude-sensitivity in optimal value-based decision-making." Judgment and Decision Making 16, no. 5 (September 2021): 1221–33. http://dx.doi.org/10.1017/s1930297500008408.
Full textAbstract:
AbstractRecent work has derived the optimal policy for two-alternative value-based decisions, in which decision-makers compare the subjective expected reward of two alternatives. Under specific task assumptions — such as linear utility, linear cost of time and constant processing noise — the optimal policy is implemented by a diffusion process in which parallel decision thresholds collapse over time as a function of prior knowledge about average reward across trials. This policy predicts that the decision dynamics of each trial are dominated by the difference in value between alternatives and are insensitive to the magnitude of the alternatives (i.e., their summed values). This prediction clashes with empirical evidence showing magnitude-sensitivity even in the case of equal alternatives, and with ecologically plausible accounts of decision making. Previous work has shown that relaxing assumptions about linear utility or linear time cost can give rise to optimal magnitude-sensitive policies. Here we question the assumption of constant processing noise, in favour of input-dependent noise. The neurally plausible assumption of input-dependent noise during evidence accumulation has received strong support from previous experimental and modelling work. We show that including input-dependent noise in the evidence accumulation process results in a magnitude-sensitive optimal policy for value-based decision-making, even in the case of a linear utility function and a linear cost of time, for both single (i.e., isolated) choices and sequences of choices in which decision-makers maximise reward rate. Compared to explanations that rely on non-linear utility functions and/or non-linear cost of time, our proposed account of magnitude-sensitive optimal decision-making provides a parsimonious explanation that bridges the gap between various task assumptions and between various types of decision making.
24
Overton, G. "Hygrothermal performance of New Zealand wall constructions — meeting the durability requirements of the New Zealand Building Code." Canadian Journal of Civil Engineering 46, no. 11 (November 2019): 1063–73. http://dx.doi.org/10.1139/cjce-2018-0589.
Full textAbstract:
The New Zealand Building Code (NZBC) is performance based. From a durability perspective, compliance requires a practitioner to demonstrate that materials will remain functional for the minimum periods specified. The NZBC also states that buildings must be constructed to avoid the likelihood of fungal growth or the accumulation of contaminants on linings and other building elements. Currently, there is no recognised method for practitioners to use to demonstrate that a wall system can meet this requirement for the required design life. In this paper, we consider how hygrothermal modelling, in conjunction with the VTT mould index, may be used to form the basis of such a method. In the past, there has been a discrepancy between predicted failures and field evidence, but the VTT mould index appears to correlate much better with the successful in-service history of typical New Zealand construction.
25
Elder, J. D., P. C. Stangeby, E. A. Unterberg, T. Abrams, J. A. Boedo, D. Donovan, A. G. McLean, D. L. Rudakov, W. R. Wampler, and J. G. Watkins. "Evidence of near-SOL tungsten accumulation using a far-SOL collector probe array and OEDGE modelling in the DIII-D metal rings L-mode discharges." Nuclear Materials and Energy 19 (May 2019): 287–94. http://dx.doi.org/10.1016/j.nme.2019.03.007.
Full text
26
Well, Reinhard, Martin Maier, Dominika Lewicka-Szczebak, Jan-Reent Köster, and Nicolas Ruoss. "Underestimation of denitrification rates from field application of the <sup>15</sup>N gas flux method and its correction by gas diffusion modelling." Biogeosciences 16, no. 10 (May 29, 2019): 2233–46. http://dx.doi.org/10.5194/bg-16-2233-2019.
Full textAbstract:
Abstract. Common methods for measuring soil denitrification in situ include monitoring the accumulation of 15N-labelled N2 and N2O evolved from 15N-labelled soil nitrate pool in closed chambers that are placed on the soil surface. Gas diffusion is considered to be the main transport process in the soil. Because accumulation of gases within the chamber decreases concentration gradients between soil and the chamber over time, the surface efflux of gases decreases as well, and gas production rates are underestimated if calculated from chamber concentrations without consideration of this mechanism. Moreover, concentration gradients to the non-labelled subsoil exist, inevitably causing downward diffusion of 15N-labelled denitrification products. A numerical 3-D model for simulating gas diffusion in soil was used in order to determine the significance of this source of error. Results show that subsoil diffusion of 15N-labelled N2 and N2O – and thus potential underestimation of denitrification derived from chamber fluxes – increases with chamber deployment time as well as with increasing soil gas diffusivity. Simulations based on the range of typical soil gas diffusivities of unsaturated soils showed that the fraction of N2 and N2O evolved from 15N-labelled NO3- that is not emitted at the soil surface during 1 h chamber closing is always significant, with values up to >50 % of total production. This is due to accumulation in the pore space of the 15N-labelled soil and diffusive flux to the unlabelled subsoil. Empirical coefficients to calculate denitrification from surface fluxes were derived by modelling multiple scenarios with varying soil water content. Modelling several theoretical experimental set-ups showed that the fraction of produced gases that are retained in soil can be lowered by lowering the depth of 15N labelling and/or increasing the length of the confining cylinder. Field experiments with arable silt loam soil for measuring denitrification with the 15N gas flux method were conducted to obtain direct evidence for the incomplete surface emission of gaseous denitrification products. We compared surface fluxes of 15N2 and 15N2O from 15N-labelled micro-plots confined by cylinders using the closed-chamber method with cylinders open or closed at the bottom, finding 37 % higher surface fluxes with the bottom closed. Modelling fluxes of this experiment confirmed this effect, however with a higher increase in surface flux of 89 %. From our model and experimental results we conclude that field surface fluxes of 15N-labelled N2 and N2O severely underestimate denitrification rates if calculated from chamber accumulation only. The extent of this underestimation increases with closure time. Underestimation also occurs during laboratory incubations in closed systems due to pore space accumulation of 15N-labelled N2 and N2O. Due to this bias in past denitrification measurements, denitrification in soils might be more relevant than assumed to date. Corrected denitrification rates can be obtained by estimating subsurface flux and storage with our model. The observed deviation between experimental and modelled subsurface flux revealed the need for refined model evaluation, which must include assessment of the spatial variability in diffusivity and production and the spatial dimension of the chamber.
27
Creanza, Nicole, Oren Kolodny, and Marcus W. Feldman. "Greater than the sum of its parts? Modelling population contact and interaction of cultural repertoires." Journal of The Royal Society Interface 14, no. 130 (May 2017): 20170171. http://dx.doi.org/10.1098/rsif.2017.0171.
Full textAbstract:
Evidence for interactions between populations plays a prominent role in the reconstruction of historical and prehistoric human dynamics; these interactions are usually interpreted to reflect cultural practices or demographic processes. The sharp increase in long-distance transportation of lithic material between the Middle and Upper Palaeolithic, for example, is seen as a manifestation of the cultural revolution that defined the transition between these epochs. Here, we propose that population interaction is not only a reflection of cultural change but also a potential driver of it. We explore the possible effects of inter-population migration on cultural evolution when migrating individuals possess core technological knowledge from their original population. Using a computational framework of cultural evolution that incorporates realistic aspects of human innovation processes, we show that migration can lead to a range of outcomes, including punctuated but transient increases in cultural complexity, an increase of cultural complexity to an elevated steady state and the emergence of a positive feedback loop that drives ongoing acceleration in cultural accumulation. Our findings suggest that population contact may have played a crucial role in the evolution of hominin cultures and propose explanations for observations of Palaeolithic cultural change whose interpretations have been hotly debated.
28
Rollwage, Max, and Stephen M. Fleming. "Confirmation bias is adaptive when coupled with efficient metacognition." Philosophical Transactions of the Royal Society B: Biological Sciences 376, no. 1822 (February 22, 2021): 20200131. http://dx.doi.org/10.1098/rstb.2020.0131.
Full textAbstract:
Biases in the consideration of evidence can reduce the chances of consensus between people with different viewpoints. While such altered information processing typically leads to detrimental performance in laboratory tasks, the ubiquitous nature of confirmation bias makes it unlikely that selective information processing is universally harmful. Here, we suggest that confirmation bias is adaptive to the extent that agents have good metacognition, allowing them to downweight contradictory information when correct but still able to seek new information when they realize they are wrong. Using simulation-based modelling, we explore how the adaptiveness of holding a confirmation bias depends on such metacognitive insight. We find that the behavioural consequences of selective information processing are systematically affected by agents' introspective abilities. Strikingly, we find that selective information processing can even improve decision-making when compared with unbiased evidence accumulation, as long as it is accompanied by good metacognition. These results further suggest that interventions which boost people's metacognition might be efficient in alleviating the negative effects of selective information processing on issues such as political polarization. This article is part of the theme issue ‘The political brain: neurocognitive and computational mechanisms’.
29
Davies, R. I., E. Hicks, M. Schartmann, R. Genzel, L. J. Tacconi, H. Engel, A. Burkert, et al. "The Impact of Nuclear Star Formation on Gas Inflow to AGN." Proceedings of the International Astronomical Union 5, S267 (August 2009): 283–89. http://dx.doi.org/10.1017/s1743921310006496.
Full textAbstract:
AbstractOur adaptive optics observations of nearby AGN at spatial resolutions as small as 0.″085 show strong evidence for recent, but no longer active, nuclear star formation. We begin by describing observations that highlight two contrasting methods by which gas can flow into the central tens of parsecs. Gas accumulation in this region will inevitably lead to a starburst, and we discuss the evidence for such events. We then turn to the impact of stellar evolution on the further inflow of gas by combining a phenomenological approach with analytical modelling and hydrodynamic simulations. These complementary perspectives paint a picture in which all the processes are ultimately regulated by the mass accretion rate into the central hundred parsecs, and the ensuing starburst that occurs there. The resulting supernovae delay accretion by generating a starburst wind, which leaves behind a clumpy interstellar medium. This provides an ideal environment for slower stellar outflows to accrete inwards and form a dense turbulent disk on scales of a few parsecs. Such a scenario may resolve the discrepancy between the larger scale structure seen with adaptive optics and the small-scale structure seen with VLTI.
30
Huybrechts, Philippe, and Stephen T’ Siobbel. "Thermomechanical modelling of Northern Hemisphere ice sheets with a two-level mass-balance parameterization." Annals of Glaciology 21 (1995): 111–16. http://dx.doi.org/10.3189/s0260305500015688.
Full textAbstract:
A three-dimensional time-dependent thermomechanical ice-sheet model was used together with a two-level (snow-accumulation/runoff) mass-balance model to investigate the Quaternary ice sheets of the Northern Hemisphere. The model freely generates the ice-sheet geometry in response to specified changes in surface temperature and mass balance, and includes bedrock adjustment, basal sliding and a full temperature calculation within the ice. The mass-balance parameterization makes a distinction between snowfall and melting. Yearly snowfall rates depend on the present precipitation distribution, and are varied proportionally to changes in surface temperature and the moisture content of the air. The ablation model is based on the positive-degree-day method, and distinguishes between ice and snow melting. This paper discusses steady-slate characteristics, conditions for growth and retreat, and response time-scales of ice sheets as a function of a prescribed lowering of summer temperature. Most notably, the modelled extents of the Eurasian ice sheet for a summer temperature lowering of 6–7 K and of the Laurentide ice sheet for a cooling of 9–10 K are in reasonable agreement with most reconstructions based on geological evidence, except for the presence of a large ice sheet stretching from Alaska across the Bering Strait to most of eastern Siberia. In addition, wet basal conditions turned out to be always confined to the margin, whereas central areas in these reconstructions remained always cold-based. This is of relevance for processes involving reduced basal traction.
31
Huybrechts, Philippe, and Stephen T’ Siobbel. "Thermomechanical modelling of Northern Hemisphere ice sheets with a two-level mass-balance parameterization." Annals of Glaciology 21 (1995): 111–16. http://dx.doi.org/10.1017/s0260305500015688.
Full textAbstract:
A three-dimensional time-dependent thermomechanical ice-sheet model was used together with a two-level (snow-accumulation/runoff) mass-balance model to investigate the Quaternary ice sheets of the Northern Hemisphere. The model freely generates the ice-sheet geometry in response to specified changes in surface temperature and mass balance, and includes bedrock adjustment, basal sliding and a full temperature calculation within the ice. The mass-balance parameterization makes a distinction between snowfall and melting. Yearly snowfall rates depend on the present precipitation distribution, and are varied proportionally to changes in surface temperature and the moisture content of the air. The ablation model is based on the positive-degree-day method, and distinguishes between ice and snow melting. This paper discusses steady-slate characteristics, conditions for growth and retreat, and response time-scales of ice sheets as a function of a prescribed lowering of summer temperature. Most notably, the modelled extents of the Eurasian ice sheet for a summer temperature lowering of 6–7 K and of the Laurentide ice sheet for a cooling of 9–10 K are in reasonable agreement with most reconstructions based on geological evidence, except for the presence of a large ice sheet stretching from Alaska across the Bering Strait to most of eastern Siberia. In addition, wet basal conditions turned out to be always confined to the margin, whereas central areas in these reconstructions remained always cold-based. This is of relevance for processes involving reduced basal traction.
32
Pfister, C., and R. Brázdil. "Social vulnerability to climate in the "Little Ice Age"?: an example from Central Europe in the early 1770s." Climate of the Past Discussions 2, no. 2 (April 7, 2006): 123–55. http://dx.doi.org/10.5194/cpd-2-123-2006.
Full textAbstract:
Abstract. The paper is oriented on social vulnerability to climate in Switzerland and in the Czech Lands during the early 1770s. Documentary sources of climate related to man-made archives are discussed. Methods of temperature and precipitation reconstruction based on this evidence as well as climate impact analyses are presented. Modelling of Little Ice Age-type Impacts (LIATIMP) is applied to highlight climate impacts during the period 1750–1800 in the Swiss Plateau and in the Czech Lands. LIATIMP are defined as adverse climate situations affecting grain production, mainly in terms of rainy autumns, cold springs and rainy harvest-periods. The most adverse weather patterns according to this model occurred from 1769 to 1771 causing two, in the case of the Czech Lands even three successive harvest failures. The paper addresses the social and economic consequences of this accumulation of climatic stress and explores how the authorities and the victims dealt with this situation.
33
Guo, Liwei, John C. Vardakis, Toni Lassila, Micaela Mitolo, Nishant Ravikumar, Dean Chou, Matthias Lange, et al. "Subject-specific multi-poroelastic model for exploring the risk factors associated with the early stages of Alzheimer's disease." Interface Focus 8, no. 1 (December 15, 2017): 20170019. http://dx.doi.org/10.1098/rsfs.2017.0019.
Full textAbstract:
There is emerging evidence suggesting that Alzheimer's disease is a vascular disorder, caused by impaired cerebral perfusion, which may be promoted by cardiovascular risk factors that are strongly influenced by lifestyle. In order to develop an understanding of the exact nature of such a hypothesis, a biomechanical understanding of the influence of lifestyle factors is pursued. An extended poroelastic model of perfused parenchymal tissue coupled with separate workflows concerning subject-specific meshes, permeability tensor maps and cerebral blood flow variability is used. The subject-specific datasets used in the modelling of this paper were collected as part of prospective data collection. Two cases were simulated involving male, non-smokers (control and mild cognitive impairment (MCI) case) during two states of activity (high and low). Results showed a marginally reduced clearance of cerebrospinal fluid (CSF)/interstitial fluid (ISF), elevated parenchymal tissue displacement and CSF/ISF accumulation and drainage in the MCI case. The peak perfusion remained at 8 mm s −1 between the two cases.
34
Pfister, C., and R. Brázdil. "Social vulnerability to climate in the "Little Ice Age": an example from Central Europe in the early 1770s." Climate of the Past 2, no. 2 (October 9, 2006): 115–29. http://dx.doi.org/10.5194/cp-2-115-2006.
Full textAbstract:
Abstract. The paper is oriented on social vulnerability to climate in Switzerland and in the Czech Lands during the early 1770s. Documentary sources of climate related to man-made archives are discussed. Methods of temperature and precipitation reconstruction based on this evidence as well as climate impact analyses are presented. Modelling of Little Ice Age-type Impacts (LIATIMP) is applied to highlight climate impacts during the period 1750–1800 in the Swiss Plateau and in the Czech Lands. LIATIMP are defined as adverse climate situations affecting agricultural production, mainly in terms of rainy autumns, cold springs and rainy harvest-periods. The most adverse weather patterns according to this model occurred from 1769 to 1771 causing two, in the case of the Czech Lands even three successive harvest failures. The paper addresses the social and economic consequences of this accumulation of climatic stress and explores how the authorities and the victims dealt with this situation.
35
d'Acremont, Mathieu, Eleonora Fornari, and Peter Bossaerts. "Activity in Inferior Parietal and Medial Prefrontal Cortex Signals the Accumulation of Evidence in a Probability Learning Task." PLoS Computational Biology 9, no. 1 (January 31, 2013): e1002895. http://dx.doi.org/10.1371/journal.pcbi.1002895.
Full text
36
Hernández-Almeida, I., F. J. Sierro, I. Cacho, and J. A. Flores. "Subsurface North Atlantic warming as a trigger of rapid cooling events: evidence from the early Pleistocene (MIS 31–19)." Climate of the Past 11, no. 4 (April 21, 2015): 687–96. http://dx.doi.org/10.5194/cp-11-687-2015.
Full textAbstract:
Abstract. Subsurface water column dynamics in the subpolar North Atlantic were reconstructed in order to improve the understanding of the cause of abrupt ice-rafted detritus (IRD) events during cold periods of the early Pleistocene. We used paired Mg / Ca and δ18O measurements of Neogloboquadrina pachyderma (sinistral – sin.), deep-dwelling planktonic foraminifera, to estimate the subsurface temperatures and seawater δ18O from a sediment core from Gardar Drift, in the subpolar North Atlantic. Carbon isotopes of benthic and planktonic foraminifera from the same site provide information about the ventilation and water column nutrient gradient. Mg / Ca-based temperatures and seawater δ18O suggest increased subsurface temperatures and salinities during ice-rafting, likely due to northward subsurface transport of subtropical waters during periods of weaker Atlantic Meridional Overturning Circulation (AMOC). Planktonic carbon isotopes support this suggestion, showing coincident increased subsurface ventilation during deposition of IRD. Subsurface accumulation of warm waters would have resulted in basal warming and break-up of ice-shelves, leading to massive iceberg discharges in the North Atlantic. The release of heat stored at the subsurface to the atmosphere would have helped to restart the AMOC. This mechanism is in agreement with modelling and proxy studies that observe a subsurface warming in the North Atlantic in response to AMOC slowdown during Marine Isotope Stage (MIS) 3.
37
JUDD, KEVIN. "GALTON'S QUINCUNX: RANDOM WALK OR CHAOS?" International Journal of Bifurcation and Chaos 17, no. 12 (December 2007): 4463–69. http://dx.doi.org/10.1142/s0218127407020129.
Full textAbstract:
In 1873 Francis Galton had constructed a simple mechanical device where a ball is dropped vertically through a harrow of pins that deflect the ball sideways as it falls. Galton called the device a quincunx, although today it is usually referred to as a Galton board. Statisticians often employ (conceptually, if not physically) the quincunx to illustrate random walks and the central limit theorem. In particular, how a Binomial or Gaussian distribution results from the accumulation of independent random events, that is, the collisions in the case of the quincunx. But how valid is the assumption of "independent random events" made by Galton and countless subsequent statisticians? This paper presents evidence that this assumption is almost certainly not valid and that the quincunx has the richer, more predictable qualities of a low-dimensional deterministic dynamical system. To put this observation into a wider context, the result illustrates that statistical modeling assumptions can obscure more informative dynamics. When such dynamical models are employed they will yield better predictions and forecasts.
38
Humeniuk, Halyna B., Volodymyr O. Khomenchuk, Nataliia M. Harmatiy, and Iryna B. Chen. "Complex Assessment and Forecasting of Chemical Pollution of Small Rivers by Economic and Mathematical Modelling Methods." Journal of Geology, Geography and Geoecology 30, no. 3 (October 5, 2021): 460–69. http://dx.doi.org/10.15421/112142.
Full textAbstract:
The purpose of this work is to determine the hydrochemical parameters of the water of the river Seret and the features of the accumulation of heavy metals by bivalve molluscs Unio pictorum L. to predict the chemical contamination of the reservoir in the near future. Water samples for the study were taken in spring (April) and summer (July) from the Seret River at two points: above and below Ternopil. It is established that the chemical composition of the water of the river Seret is formed under the influence of a number of factors, but seasonal and anthropogenic factors play a dominant role. In the spring season, a number of hydrochemical indicators (pH, water hardness, concentration of ΝΟ 2-, ΝН4+, Сl- ions and metals) have lower values than in the summer. In addition, there is an increase in the amount of organic matter, ammonium cations, nitrite ions, chloride ions, phosphate ions and a decrease in oxygen concentration below Ternopil, especially in the summer season. This is evidence that the Seret River is under significant anthropogenic impact. An increase in the concentration of metals (Mn, Cu and Pb) in summer below Ternopil was revealed, which may be due to the discharge of insufficiently treated wastewater. The series of metal concentrations in the water of the Seret River looks as follows Mn → Zn → Pb → Cd → Cu, and the series of accumulation of metals in the tissues of molluscs Unio pictorum L. has the form Zn → Mn → Cu → Pb → Cd. On the basis of bioaccumulation coefficients of heavy metals by molluscs, a prediction of the situation on their content in water for the short term based on the theory of Markov chains was made. This theory allows us to make forecasts of a factor, taking into account the possibility of accidental influences on the environment, and to investigate the highest probability of finding a factor in a certain numerical parameter. The possibility of using economic and mathematical modelling tools and statistical methods based on correlation-regression analysis using modern Matlab information systems to identify correlations between chemical indicators of water quality and biological molluscs for modelling the environmental situation of the river Seret and assessing the contribution of the studied indicators in pollution of small rivers is shown.
39
Florineth, Duri. "Surface geometry of the Last Glacial Maximum (LGM) in the southeastern Swiss Alps (Graubünden) and its paleoclimatological significance." E&G Quaternary Science Journal 48, no. 1 (January 1, 1998): 23–37. http://dx.doi.org/10.3285/eg.48.1.03.
Full textAbstract:
Abstract. Using detailed field evidence provided by trimlines on former nunataks, erratic boulders and the orientations of glacial striae, the surface geometry in the accumulation area during the Last Glacial Maximum was reconstructed for the area of SE Switzerland and adjacent Italy. Collectively, the trends of trimline elevations, flowlines deduced from glacial striae and bedrock morphology along the longitudinal valleys and their tributaries indicate that the former accumulation area consisted of an ice dome with the ice divide located over the area enclosed by Schlarignia, Cinuos-chel, Livigno and Piz Bernina. It attained a minimum altitude of approximately 3000 m. Modelling the topography of the ice surface using a Geographical Information System (GIS) is consistent with these results. The paleoclimatological signal included in this surface geometry was used to draw conclusions about the main atmospheric paleocireulation patterns and to outline the principal precipitation areas for the Alps during the last glaciation. It followed from this that ice build-up was principally related to dominating precipitation by southerly circulation (foehn). The prevaleance of foehn circulation most likely reflects a southward shift of the North Atlantic polar atmospheric front and of the accompanied storm track due to the advancing margin of sea ice. There exists good agreement between these assumptions and (a) results of global circulation models for the time of the LGM; (b) estimations of basal shear stress values and flow velocities for Ice Age glaciers; and (c) interpretations of paleowind indicators.
40
White, Robert S. "Mantle temperature and lithospheric thinning beneath the Midcontinent rift system: evidence from magmatism and subsidence." Canadian Journal of Earth Sciences 34, no. 4 (April 1, 1997): 464–75. http://dx.doi.org/10.1139/e17-038.
Full textAbstract:
The tectono-magmatic history of the Midcontinent rift system can be explained by the presence of a mantle plume bringing elevated-temperature mantle beneath the rift system at about 1110 Ma. Huge volumes of extrusive and intrusive igneous rocks were generated as abnormally hot mantle decompressed beneath the lithospheric rift. Geochemical and isotopic data from the Keweenawan volcanics show that the earliest melts were derived from small-degree melting of primitive plume mantle, coupled with enriched metasomatic melts derived from the continental lithosphere. As rifting progressed, the main bulk of the volcanics was generated primarily from the plume mantle, with the melting starting at depths of about 120 km and extending to as shallow as the base of the stretched lithosphère at 45 km depth. Elevated mantle temperatures of 1500–1560 °C, approximately 150–200 °C above normal, are inferred from the rare earth element concentrations in the volcanic rocks. Further constraints on the mantle temperature come from combined subsidence and melt-generation modelling. I assume that rifting occurred in two main periods, during 1110–1105 and 1100–1094 Ma, with a reduced rate of stretching and greatly decreased melt production during the intervening period, 1105–1100 Ma. At the centre of the rift, production of more than 15 km of volcanic rocks close to, or above, sea level was followed by the accumulation of up to 8 km of mainly coarse terrigenous sediments in the postrift subsidence phase. This can be explained by lithospheric thinning by a factor of approximately 6 above mantle with a potential temperature of about 1550 °C. Subsequently, the mantle cooled to a normal potential temperature of 1350 °C as the plume thermal anomaly died away.
41
Walke, R. C., M. C. Thorne, J. T. Smith, and R. Kowe. "Representation of estuarine, coastal and marine biosphere systems within post-closure performance assessments supporting geological disposal of higher activity radioactive wastes in the UK." Mineralogical Magazine 79, no. 6 (November 2015): 1467–74. http://dx.doi.org/10.1180/minmag.2015.6.21.
Full textAbstract:
AbstractRadioactive Waste Management Limited (RWM) is tasked with implementing geological disposal of the United Kingdom's (UK) higher activity radioactive wastes. This paper describes how RWM's biosphere modelling capability has been extended from a solely terrestrial model to allow potential contaminant releases to estuarine, coastal and marine systems around the UK to be represented. The new models aim to strike a balance between being as simple as can be justified, erring on the side of conservative estimates of potential doses, while also representing the features and processes required to reflect and distinguish UK coastal systems. Sediment dynamics (including meandering of estuaries and sediment accumulation) are explicitly represented in a simplified form that captures the accumulation and remobilization of radionuclides. Long-term transitions between biosphere systems (such as from a salt marsh to a terrestrial system) are outside the scope of the study. The models and supporting data draw on information about the UK that is representative of present-day conditions and represent potential exposures arising from both occupational and recreational habits.?Generic calculations demonstrate that potential doses to humans arising from releases to estuarine, coastal and marine systems are typically more than two orders of magnitude lower than those for equivalent releases to terrestrial systems via well water and groundwater discharge to soil. The extended capability (i) ensures that RWM is able to undertake assessments for potential coastal site contexts, if and when required, and (ii) provides RWM with quantitative evidence to support the principal focus on terrestrial releases ( particularly for more generic assessments).
42
Beerling, D. J., F. I. Woodward, M. R. Lomas, M. A. Wills, W. P. Quick, and P. J. Valdes. "The influence of Carboniferous palaeoatmospheres on plant function: an experimental and modelling assessment." Philosophical Transactions of the Royal Society of London. Series B: Biological Sciences 353, no. 1365 (January 29, 1998): 131–40. http://dx.doi.org/10.1098/rstb.1998.0196.
Full textAbstract:
Geochemical models of atmospheric evolution predict that during the late Carboniferous, ca . 300 Ma, atmospheric oxygen and carbon dioxide concentrations were 35% and 0.03%, respectively. Both gases compete with each other for ribulose–1,5–bisphosphate carboxylase/oxygenase–the primary C–fixing enzyme in C 3 land plants: and the absolute concentrations and the ratio of the two in the atmosphere have the potential to strongly influence land–plant function. The Carboniferous therefore represents an era of potentially strong feedback between atmospheric composition and plant function. We assessed some implications of this ratio of atmospheric gases on plant function using experimental and modelling approaches. After six weeks growth at 35% O 2 and 0.03% carbon dioxide, no photosynthetic acclimation was observed in the woody species Betula pubescens and Hedera helix relative to those plants grown at 21% O 2 . Leaf photosynthetic rates were 29% lower in the high O 2 environment compared to the controls. A global–scale analysis of the impact of the late Carboniferous climate and atmospheric composition on vegetation function was determined by driving a process–based vegetation–biogeochemistry model with a Carboniferous global palaeoclimate simulated by the Universities Global Atmospheric Modelling Programme General Circulation Model. Global patterns of net primary productivity, leaf area index and soil carbon concentration for the equilibrium model solutions showed generally low values everywhere, compared with the present day, except for a central band in the northern land mass extension of Gondwana, where high values were predicted. The areas of high soil carbon accumulation closely match the known distribution of late Carboniferous coals. Sensitivity analysis with the model indicated that the increase in O 2 concentration from 21% to 35% reduced global net primary productivity by 18.7% or by 6.3 GtC yr –1 . Further work is required to collate and map at the global scale the distribution of vegetation types, and evidence for wildfires, for the late Carboniferous to test our predictions.
43
Zmigrod, Leor, Ian W. Eisenberg, Patrick G. Bissett, Trevor W. Robbins, and Russell A. Poldrack. "The cognitive and perceptual correlates of ideological attitudes: a data-driven approach." Philosophical Transactions of the Royal Society B: Biological Sciences 376, no. 1822 (February 22, 2021): 20200424. http://dx.doi.org/10.1098/rstb.2020.0424.
Full textAbstract:
Although human existence is enveloped by ideologies, remarkably little is understood about the relationships between ideological attitudes and psychological traits. Even less is known about how cognitive dispositions—individual differences in how information is perceived and processed— sculpt individuals' ideological worldviews, proclivities for extremist beliefs and resistance (or receptivity) to evidence. Using an unprecedented number of cognitive tasks ( n = 37) and personality surveys ( n = 22), along with data-driven analyses including drift-diffusion and Bayesian modelling, we uncovered the specific psychological signatures of political, nationalistic, religious and dogmatic beliefs. Cognitive and personality assessments consistently outperformed demographic predictors in accounting for individual differences in ideological preferences by 4 to 15-fold. Furthermore, data-driven analyses revealed that individuals’ ideological attitudes mirrored their cognitive decision-making strategies. Conservatism and nationalism were related to greater caution in perceptual decision-making tasks and to reduced strategic information processing, while dogmatism was associated with slower evidence accumulation and impulsive tendencies. Religiosity was implicated in heightened agreeableness and risk perception. Extreme pro-group attitudes, including violence endorsement against outgroups, were linked to poorer working memory, slower perceptual strategies, and tendencies towards impulsivity and sensation-seeking—reflecting overlaps with the psychological profiles of conservatism and dogmatism. Cognitive and personality signatures were also generated for ideologies such as authoritarianism, system justification, social dominance orientation, patriotism and receptivity to evidence or alternative viewpoints; elucidating their underpinnings and highlighting avenues for future research. Together these findings suggest that ideological worldviews may be reflective of low-level perceptual and cognitive functions. This article is part of the theme issue ‘The political brain: neurocognitive and computational mechanisms’.
44
Besada, Pedro, María Gallardo-Gómez, Tania Pérez-Márquez, Lucía Patiño-Álvarez, Sergio Pantano, Carlos Silva-López, Carmen Terán, et al. "The New Pharmacological Chaperones PBXs Increase α-Galactosidase A Activity in Fabry Disease Cellular Models." Biomolecules 11, no. 12 (December 10, 2021): 1856. http://dx.doi.org/10.3390/biom11121856.
Full textAbstract:
Fabry disease is an X-linked multisystemic disorder caused by the impairment of lysosomal α-Galactosidase A, which leads to the progressive accumulation of glycosphingolipids and to defective lysosomal metabolism. Currently, Fabry disease is treated by enzyme replacement therapy or the orally administrated pharmacological chaperone Migalastat. Both therapeutic strategies present limitations, since enzyme replacement therapy has shown low half-life and bioavailability, while Migalastat is only approved for patients with specific mutations. The aim of this work was to assess the efficacy of PBX galactose analogues to stabilize α-Galactosidase A and therefore evaluate their potential use in Fabry patients with mutations that are not amenable to the treatment with Migalastat. We demonstrated that PBX compounds are safe and effective concerning stabilization of α-Galactosidase A in relevant cellular models of the disease, as assessed by enzymatic activity measurements, molecular modelling, and cell viability assays. This experimental evidence suggests that PBX compounds are promising candidates for the treatment of Fabry disease caused by mutations which affect the folding of α-Galactosidase A, even for GLA variants that are not amenable to the treatment with Migalastat.
45
Abd Alhadi, Saleh, Rosmila Senik, Jalila Johari, Ridzwana Mohd Said, and Hairul Suhaimi Nahar. "Multiple directorships and earnings quality: Does investor protection matter?" Journal of Asia Business Studies 15, no. 4 (June 16, 2021): 605–24. http://dx.doi.org/10.1108/jabs-08-2019-0254.
Full textAbstract:
Purpose This study aims to investigate whether higher earnings quality is related to the existence of multiple directorships among corporate boards and whether this relationship varies with the quality of investor protection. Design/methodology/approach This paper used a dynamic panel data modelling on the sample of 2,090 firm-year observations over the period from 2007 to 2016 in Malaysia. The generalized method of moments estimators were used to deal with endogeneity and other econometric problems. Findings This study finds that the accumulation of several outside directorships is negatively associated with the firm's earnings quality, as measured by the magnitude of discretionary accruals. More importantly, the findings provide evidence that multiple directors are more efficient in improving earnings quality in healthy investor protection environment. Practical implications The appointment of directors should be based on market-based and not on a relationship (i.e. financial and industry professionals). Originality/value The results highlight the importance of interaction between internal and external governance mechanisms to improve the firm's financial performance, investment and market efficiency. High-quality investor protection and law enforcement are significant for enhancing the monitoring role of multiple directorships in improving earnings quality.
46
Huss, Matthias, and Andreas Bauder. "20th-century climate change inferred from four long-term point observations of seasonal mass balance." Annals of Glaciology 50, no. 50 (2009): 207–14. http://dx.doi.org/10.3189/172756409787769645.
Full textAbstract:
AbstractFour long-term time series of seasonal mass-balance observations, all starting in 1914, have been compiled for two stakes on Claridenfirn and one stake on Grosser Aletschgletscher and Silvrettagletscher, Switzerland. These data represent the longest records of mass balance worldwide. A mass-balance model based on the temperature-index approach is used to correct field data for varying observation dates and data gaps and to separate accumulation and ablation. The homogenized continuous 93 year time series cover most of the 20th century and enable us to investigate temporal, regional and altitudinal variability in mass balance and changes in the climatic forcing on glaciers. A high-altitude site shows summer balance trends opposite to those at three stakes located near the equilibrium line. Since 1975, melt rates have increased by 10%(10 a)−1 periods of enhanced climatic forcing are detected: 1943–53 and 1987–2007. The energy consumed for melt was higher in the 1940s despite lower air temperatures compared to the years since 1987. We find evidence for a change in the glacier surface heat budget, which has important implications for the long-term stability of degree-day factors in empirical temperature-index modelling.
47
Mahood, Gail A., and Paula C. Cornejo. "Evidence for ascent of differentiated liquids in a silicic magma chamber found in a granitic pluton." Earth and Environmental Science Transactions of the Royal Society of Edinburgh 83, no. 1-2 (1992): 63–69. http://dx.doi.org/10.1017/s0263593300007756.
Full textAbstract:
ABSTRACTFluid dynamic modelling of crystallising calc-alkalic magma bodies has predicted that differentiated liquids will ascend as boundary layers and that accumulation of these buoyant liquids near chamber roofs will result in compositionally stratified magma chambers. This paper reports physical features in La Gloria Pluton that can be interpreted as trapped ascending differentiated liquids. Leucogranitic layers decimetres thick, which are locally stratified, are trapped beneath overhanging wall contacts. The same felsic magmas were also preserved where they were injected into the wall rocks as dykes and as large sill complexes. These rocks do not represent differentiated magmas produced by crystallisation along the exposed walls because the felsic layers occur at the wall rock contact, not inboard of it. Rather, we speculate that evolved felsic liquids are generated by crystallisation all across the deep levels of chambers and that initial melt segregation occurs by flowage of melt into tension fractures. Melt bodies so formed may be large enough to have significant ascent velocities as diapirs and/or dykes. The other way in which the leucogranite occurrence is at variance with the convective fractionation model is that the ascending liquids did not feed a highly differentiated cap to the chamber, as the composition at the roof, although the most felsic in this vertically and concentrically zoned pluton, is considerably more mafic than the trapped leucogranitic liquids. This suggests that these evolved liquids were usually mixed back into the main body of the chamber. Backmixing may be general in continental-margin calc-alkalic magmatic systems, which, in contrast to those in intracontinental settings, rarely produce volcanic rocks more silicic than rhyodacite. That the highly differentiated liquids are preserved at all at La Gloria is a result of the unusual stepped nature of the contact and the entirely passive mode of emplacement of the pluton, which, in contrast to ballooning in place, does not result in wall zones being “scoured”.
48
Cavaleiro, Catarina, Antje H. L. Voelker, Heather Stoll, Karl-Heinz Baumann, and Michal Kucera. "Coccolithophore productivity at the western Iberian Margin during the Middle Pleistocene (310–455 ka) – evidence from coccolith Sr∕Ca data." Climate of the Past 16, no. 6 (November 3, 2020): 2017–37. http://dx.doi.org/10.5194/cp-16-2017-2020.
Full textAbstract:
Abstract. Coccolithophores contribute significantly to marine primary productivity and play a unique role in ocean biogeochemistry by using carbon for photosynthesis (soft-tissue pump) and for calcification (carbonate counter pump). Despite the importance of including coccolithophores in Earth system models to allow better predictions of the climate system's responses to planetary change, the reconstruction of coccolithophore productivity mostly relied on proxies dependent on accumulation and sedimentation rates and preservation conditions. In this study we used an independent proxy, based on the coccolith fraction (CF) Sr∕Ca ratio, to reconstruct coccolithophore productivity. We studied the marine sediment core MD03-2699 from the western Iberian margin (IbM), concentrating on glacial–interglacial cycles of Marine Isotopic Stage (MIS) 12 to MIS 9. We found that IbM coccolithophore productivity was controlled by changes in the oceanographic conditions, such as in sea surface temperature (SST) and nutrient availability, and by competition with other phytoplankton groups. Long-term coccolithophore productivity was primarily affected by variations in the dominant surface water mass. Polar and subpolar surface waters during glacial substages were associated with decreased coccolithophore productivity, with the strongest productivity minima concomitant with Heinrich-type events (HtEs). Subtropical, nutrient-poorer waters, increased terrigenous input, and moderate to strong upwelling during the deglaciation and early MIS11 are hypothesized to have attributed a competitive advantage to diatoms to the detriment of coccolithophores, resulting in intermediate coccolithophore productivity levels. During the progression towards full glacial conditions an increasing presence of nutrient-richer waters, related to the growing influence of transitional surface waters and/or intensified upwelling, probably stimulated coccolithophore productivity to maxima following the rapid depletion of silica by diatoms. We present conceptual models of the carbon and carbonate cycle components for the IbM in different time slices that might serve as a basis for further investigation and modelling experiments.
49
Hoai, D. T., P. Tuan-Anh, P. T. Nhung, P. Darriulat, P. N. Diep, N. T. Phuong, and T. T. Thai. "Revealing new features of the millimetre emission of the circumbinary envelope of Mira Ceti." Monthly Notices of the Royal Astronomical Society 495, no. 1 (May 4, 2020): 943–61. http://dx.doi.org/10.1093/mnras/staa1173.
Full textAbstract:
ABSTRACT We study the morpho-kinematics of the circumbinary envelope of Mira Ceti between ∼100 and ∼350 au from the stars using ALMA observations of the SiO (ν = 0, J= 5−4) and CO (ν = 0, J = 3−2) emissions with the aim of presenting an accurate and reliable picture of what cannot be ignored when modelling the dynamics at stake. A critical study of the uncertainties attached to imaging is presented. The line emissions are shown to be composed of a few separated fragments. They are described in detail and plausible interpretations of their genesis are discussed. Evidence for a focusing effect of the Mira A wind by Mira B over the past century is presented; it accounts for only a small fraction of the overall observed emission but its accumulation over several orbital periods may have produced an enhancement of CO emission in the orbital plane of Mira B. We identify a south-western outflow and give arguments for the anti-correlation observed between CO and SiO emissions being the result of a recent mass ejection accompanied by a shock wave. We discuss the failure of simple scenarios that have been proposed earlier to explain some of the observed features and comment on the apparent lack of continuity between the present observations and those obtained in the close environment of the stars. Evidence is obtained for the presence of large Doppler velocity components near the line of sight aiming to the star, possibly revealing the presence of important turbulence at ∼5–10 au away from Mira A.
50
Johnston, Georgina C. A., Benjamin J. Ahern, Chiara Palmieri, and Alex C. Young. "Imaging and Gross Pathological Appearance of Changes in the Parasagittal Grooves of Thoroughbred Racehorses." Animals 11, no. 12 (November 24, 2021): 3366. http://dx.doi.org/10.3390/ani11123366.
Full textAbstract:
(1) Background: Parasagittal groove (PSG) changes are often present on advanced imaging of racing Thoroughbred fetlocks and have been suggested to indicate increased fracture risk. Currently, there is limited evidence differentiating the imaging appearance of prodromal changes in horses at risk of fracture from horses with normal adaptive modelling in response to galloping. This study aims to investigate imaging and gross PSG findings in racing Thoroughbreds and the comparative utility of different imaging modalities to detect PSG changes. (2) Methods: Cadaver limbs were collected from twenty deceased racing/training Thoroughbreds. All fetlocks of each horse were examined with radiography, low-field magnetic resonance imaging (MRI), computed tomography (CT), contrast arthrography and gross pathology. (3) Results: Horses with fetlock fracture were more likely to have lateromedial PSG sclerosis asymmetry and/or lateral PSG lysis. PSG lysis was not readily detected using MRI. PSG subchondral bone defects were difficult to differentiate from cartilage defects on MRI and were not associated with fractures. The clinical relevance of PSG STIR hyperintensity remains unclear. Overall, radiography was poor for detecting PSG changes. (4) Conclusions: Some PSG changes in Thoroughbred racehorses are common; however, certain findings are more prevalent in horses with fractures, possibly indicating microdamage accumulation. Bilateral advanced imaging is recommended in racehorses with suspected fetlock pathology.