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Dixit T, Chen KC, Stoddard MC, Mahadevan L, Town CP, Spottiswoode CN. Repeatable randomness, invariant properties, and the design of biological signatures of identity. Evolution 2023; 77:2224-2233. [PMID: 37482374 DOI: 10.1093/evolut/qpad134] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/08/2022] [Revised: 05/22/2023] [Accepted: 07/21/2023] [Indexed: 07/25/2023]
Abstract
What makes a perfect signature? Optimal signatures should be consistent within individuals and distinctive between individuals. In defense against avian brood parasitism, some host species have evolved "signatures" of identity on their eggs, comprising interindividual variation in color and pattern. Tawny-flanked prinia (Prinia subflava) egg signatures facilitate recognition and rejection of parasitic cuckoo finch (Anomalospiza imberbis) eggs. Here, we show that consistency and distinctiveness of patterns are negatively correlated in prinia eggs, perhaps because non-random, repeatable pattern generation mechanisms increase consistency but limit distinctiveness. We hypothesize that pattern properties which are repeatable within individuals but random between individuals ("invariant properties") allow hosts to circumvent this trade-off. To find invariant properties, we develop a method to quantify entire egg phenotypes from images taken from different perspectives. We find that marking scale (a fine-grained measure of size), but not marking orientation or position, is an invariant property in prinias. Hosts should therefore use differences in marking scale in egg recognition, but instead field experiments show that these differences do not predict rejection of conspecific eggs by prinias. Overall, we show that invariant properties allow consistency and distinctiveness to coexist, yet receiver behavior is not optimally tuned to make use of this information.
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Affiliation(s)
- Tanmay Dixit
- Department of Zoology, University of Cambridge, Cambridge, United Kingdom
- DST-NRF Centre of Excellence at the FitzPatrick Institute of African Ornithology, University of Cape Town, Rondebosch, Cape Town, South Africa
| | - Kuan-Chi Chen
- Computer Laboratory, University of Cambridge, Cambridge, United Kingdom
| | - Mary Caswell Stoddard
- Department of Ecology and Evolutionary Biology, Princeton University, Princeton, NJ, United States
| | - Lakshminarayanan Mahadevan
- School of Engineering and Applied Sciences, Harvard University, Cambridge, MA, United States
- Department of Physics, Harvard University, Cambridge, MA, United States
- Department of Organismic and Evolutionary Biology, Harvard University, Cambridge, MA, United States
| | | | - Claire N Spottiswoode
- Department of Zoology, University of Cambridge, Cambridge, United Kingdom
- DST-NRF Centre of Excellence at the FitzPatrick Institute of African Ornithology, University of Cape Town, Rondebosch, Cape Town, South Africa
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2
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Franklin O, Fransson P, Hofhansl F, Jansen S, Joshi J. Optimal balancing of xylem efficiency and safety explains plant vulnerability to drought. Ecol Lett 2023; 26:1485-1496. [PMID: 37330625 DOI: 10.1111/ele.14270] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/14/2022] [Revised: 05/05/2023] [Accepted: 05/05/2023] [Indexed: 06/19/2023]
Abstract
In vast areas of the world, forests and vegetation are water limited and plant survival depends on the ability to avoid catastrophic hydraulic failure. Therefore, it is remarkable that plants take hydraulic risks by operating at water potentials (ψ) that induce partial failure of the water conduits (xylem). Here we present an eco-evolutionary optimality principle for xylem conduit design that explains this phenomenon based on the hypothesis that conductive efficiency and safety are optimally co-adapted to the environment. The model explains the relationship between the tolerance to negative water potential (ψ50 ) and the environmentally dependent minimum ψ (ψmin ) across a large number of species, and along the xylem pathway within individuals of two species studied. The wider hydraulic safety margin in gymnosperms compared to angiosperms can be explained as an adaptation to a higher susceptibility to accumulation of embolism. The model provides a novel optimality-based perspective on the relationship between xylem safety and efficiency.
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Affiliation(s)
- Oskar Franklin
- International Institute for Applied Systems Analysis, Laxenburg, Austria
- Department of Forest Ecology and Management, Swedish University of Agricultural Sciences, Umeå, Sweden
| | - Peter Fransson
- Department of Forest Ecology and Management, Swedish University of Agricultural Sciences, Umeå, Sweden
- Interdisciplinary Center for Scientific Computing, Heidelberg University, Heidelberg, Germany
| | - Florian Hofhansl
- International Institute for Applied Systems Analysis, Laxenburg, Austria
| | | | - Jaideep Joshi
- International Institute for Applied Systems Analysis, Laxenburg, Austria
- Institute of Geography, University of Bern, Bern, Switzerland
- Oeschger Centre for Climate Change Research, University of Bern, Bern, Switzerland
- Complexity Science and Evolution Unit, Okinawa Institute of Science and Technology Graduate University, Okinawa, Japan
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3
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Kumar S, Tao Q, Lamarca AP, Tamura K. Computational Reproducibility of Molecular Phylogenies. Mol Biol Evol 2023; 40:msad165. [PMID: 37467477 PMCID: PMC10370456 DOI: 10.1093/molbev/msad165] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/09/2022] [Revised: 07/11/2023] [Accepted: 07/12/2023] [Indexed: 07/21/2023] Open
Abstract
Repeated runs of the same program can generate different molecular phylogenies from identical data sets under the same analytical conditions. This lack of reproducibility of inferred phylogenies casts a long shadow on downstream research employing these phylogenies in areas such as comparative genomics, systematics, and functional biology. We have assessed the relative accuracies and log-likelihoods of alternative phylogenies generated for computer-simulated and empirical data sets. Our findings indicate that these alternative phylogenies reconstruct evolutionary relationships with comparable accuracy. They also have similar log-likelihoods that are not inferior to the log-likelihoods of the true tree. We determined that the direct relationship between irreproducibility and inaccuracy is due to their common dependence on the amount of phylogenetic information in the data. While computational reproducibility can be enhanced through more extensive heuristic searches for the maximum likelihood tree, this does not lead to higher accuracy. We conclude that computational irreproducibility plays a minor role in molecular phylogenetics.
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Affiliation(s)
- Sudhir Kumar
- Institute for Genomics and Evolutionary Medicine, Temple University, Philadelphia, PA, USA
- Department of Biology, Temple University, Philadelphia, PA, USA
| | - Qiqing Tao
- Institute for Genomics and Evolutionary Medicine, Temple University, Philadelphia, PA, USA
- Department of Biology, Temple University, Philadelphia, PA, USA
| | - Alessandra P Lamarca
- Institute for Genomics and Evolutionary Medicine, Temple University, Philadelphia, PA, USA
- Department of Biology, Temple University, Philadelphia, PA, USA
- Department of Genetics, Federal University of Rio de Janeiro, Rio de Janeiro, Brazil
| | - Koichiro Tamura
- Research Center for Genomics and Bioinformatics, Tokyo Metropolitan University, Hachioji, Tokyo, Japan
- Department of Biological Sciences, Tokyo Metropolitan University, Hachioji, Tokyo, Japan
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4
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Buckley TN, Frehner EH, Bailey BN. Kinetic factors of physiology and the dynamic light environment influence the economic landscape of short-term hydraulic risk. New Phytol 2023; 238:529-548. [PMID: 36650668 DOI: 10.1111/nph.18739] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/29/2022] [Accepted: 01/10/2023] [Indexed: 06/17/2023]
Abstract
Optimality-based models of stomatal conductance unify biophysical and evolutionary constraints and can improve predictions of land-atmosphere carbon and water exchange. Recent models incorporate hydraulic constraints by penalizing excessive stomatal opening in relation to hydraulic damage caused by low water potentials. We used simulation models to test whether penalties based solely on vulnerability curves adequately represent the optimality hypothesis, given that they exclude the effects of kinetic factors on stomatal behavior and integrated carbon balance. To quantify the effects of nonsteady-state phenomena on the landscape of short-term hydraulic risk, we simulated diurnal dynamics of leaf physiology for 10 000 patches of leaf in a canopy and used a ray-tracing model, Helios, to simulate realistic variation in sunfleck dynamics. Our simulations demonstrated that kinetic parameters of leaf physiology and sunfleck properties influence the economic landscape of short-term hydraulic risk, as characterized by the effect of stomatal strategy (gauged by the water potential causing a 50% hydraulic penalty) on both aggregated carbon gain and the aggregated carbon cost of short-term hydraulic risk. Hydraulic penalties in optimization models should be generalized to allow their parameters to account for kinetic factors, in addition to parameters of hydraulic vulnerability.
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Affiliation(s)
- Thomas N Buckley
- Department of Plant Sciences, University of California, Davis, Davis, CA, 95616, USA
| | - Ethan H Frehner
- Department of Plant Sciences, University of California, Davis, Davis, CA, 95616, USA
| | - Brian N Bailey
- Department of Plant Sciences, University of California, Davis, Davis, CA, 95616, USA
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Tsetsos K. Unlocking a new dimension in the speed-accuracy trade-off. Trends Cogn Sci 2023; 27:510-511. [PMID: 36959078 DOI: 10.1016/j.tics.2023.03.005] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/13/2023] [Accepted: 03/14/2023] [Indexed: 03/25/2023]
Abstract
Why do we sometimes spend too much time on seemingly impossible-to-solve tasks instead of just moving on? Masís et al. provide a new perspective on the speed-accuracy trade-off (SAT), showing that, although prolonging deliberation looks suboptimal in the short run, it is a long-term investment that helps organisms reach proficient performance more rapidly.
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Affiliation(s)
- Konstantinos Tsetsos
- School of Psychological Science, University of Bristol, Bristol, UK; Department of Neurophysiology and Pathophysiology, University Medical Center Hamburg-Eppendorf, Hamburg, Germany.
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6
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Zhou H, Akçay E, Helliker B. Optimal coordination and reorganization of photosynthetic properties in C 4 grasses. Plant Cell Environ 2023; 46:796-811. [PMID: 36478594 DOI: 10.1111/pce.14506] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/22/2022] [Revised: 11/29/2022] [Accepted: 12/03/2022] [Indexed: 06/17/2023]
Abstract
Each of >20 independent evolutions of C4 photosynthesis in grasses required reorganization of the Calvin-Benson-cycle (CB-cycle) within the leaf, along with coordination of C4 -cycle enzymes with the CB-cycle to maximize CO2 assimilation. Considering the vast amount of time over which C4 evolved, we hypothesized (i) trait divergences exist within and across lineages with both C4 and closely related C3 grasses, (ii) trends in traits after C4 evolution yield the optimization of C4 through time, and (iii) the presence/absence of trends in coordination between the CB-cycle and C4 -cycle provides information on the strength of selection. To address these hypotheses, we used a combination of optimality modelling, physiological measurements and phylogenetic-comparative-analysis. Photosynthesis was optimized after the evolution of C4 causing diversification in maximal assimilation, electron transport, Rubisco carboxylation, phosphoenolpyruvate carboxylase and chlorophyll within C4 lineages. Both theory and measurements indicated a higher light-reaction to CB-cycle ratio (Jatpmax /Vcmax ) in C4 than C3 . There were no evolutionary trends with photosynthetic coordination between the CB-cycle, light reactions and the C4 -cycle, suggesting strong initial selection for coordination. The coordination of CB-C4 -cycles (Vpmax /Vcmax ) was optimal for CO2 of 200 ppm, not to current conditions. Our model indicated that a higher than optimal Vpmax /Vcmax affects assimilation minimally, thus lessening recent selection to decrease Vpmax /Vcmax .
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Affiliation(s)
- Haoran Zhou
- School of Earth System Science, Institute of Surface-Earth System Science, Tianjin University, Tianjin, China
- School of the Environment, Yale University, New Haven, Connecticut, USA
| | - Erol Akçay
- Department of Biology, University of Pennsylvania, Philadelphia, Pennsylvania, USA
| | - Brent Helliker
- Department of Biology, University of Pennsylvania, Philadelphia, Pennsylvania, USA
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7
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Furmanchuk A, Rydland KJ, Hsia RY, Mackersie R, Shi M, Hauser MW, Kho A, Bilimoria KY, Stey AM. Geographic Disparities in Re-triage Destinations Among Seriously Injured Californians. Ann Surg Open 2023; 4:e270. [PMID: 37456577 PMCID: PMC10348777 DOI: 10.1097/as9.0000000000000270] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 03/19/2023] Open
Abstract
Objective To quantify geographic disparities in sub-optimal re-triage of seriously injured patients in California. Summary of Background Data Re-triage is the emergent transfer of seriously injured patients from the emergency departments of non-trauma and low-level trauma centers to, ideally, high-level trauma centers. Some patients are re-triaged to a second non-trauma or low-level trauma center (sub-optimal) instead of a high-level trauma center (optimal). Methods This was a retrospective observational cohort study of seriously injured patients, defined by an Injury Severity Score > 15, re-triaged in California (2009-2018). Re-triages within one day of presentation to the sending center were considered. The sub-optimal re-triage rate was quantified at the state, regional trauma coordinating committees (RTCC), local emergency medical service agencies, and sending center level. A generalized linear mixed-effects regression quantified the association of sub-optimality with the RTCC of the sending center. Geospatial analyses demonstrated geographic variations in sub-optimal re-triage rates and calculated alternative re-triage destinations. Results There were 8,882 re-triages of seriously injured patients and 2,680 (30.2 %) were sub-optimal. Sub-optimally re-triaged patients had 1.5 higher odds of transfer to a third short-term acute care hospital and 1.25 increased odds of re-admission within 60 days from discharge. The sub-optimal re-triage rates increased from 29.3 % in 2009 to 38.6 % in 2018. 56.0 % of non-trauma and low-level trauma centers had at least one sub-optimal re-triage. The Southwest RTCC accounted for the largest proportion (39.8 %) of all sub-optimal re-triages in California. Conclusion High population density geographic areas experienced higher sub-optimal re-triage rates.
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Affiliation(s)
- Al’ona Furmanchuk
- Northwestern University Feinberg School of Medicine, Division of General Internal Medicine and Geriatrics, Chicago, IL
- Center for Health Information Partnerships (CHiP), Institute for Public Health and Medicine, Northwestern University Feinberg School of Medicine, Chicago, IL, USA, Chicago, IL
| | | | - Renee Y. Hsia
- University of California San Francisco, Department of Emergency Medicine, San Francisco, CA
- Philip R. Lee Institute for Health Policy Studies, University of California San Francisco, San Francisco, CA
| | - Robert Mackersie
- University of California San Francisco, Department of Surgery, San Francisco, CA
| | - Meilynn Shi
- Northwestern University Feinberg School of Medicine, Division of General Internal Medicine and Geriatrics, Chicago, IL
| | | | - Abel Kho
- Northwestern University Feinberg School of Medicine, Division of General Internal Medicine and Geriatrics, Chicago, IL
- Center for Health Information Partnerships (CHiP), Institute for Public Health and Medicine, Northwestern University Feinberg School of Medicine, Chicago, IL, USA, Chicago, IL
| | - Karl Y. Bilimoria
- Northwestern University Feinberg School of Medicine, Department of Surgery, Chicago, IL
| | - Anne M. Stey
- Northwestern University Feinberg School of Medicine, Department of Surgery, Chicago, IL
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8
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Dubbert M, Couvreur V, Kübert A, Werner C. Plant water uptake modelling: added value of cross-disciplinary approaches. Plant Biol (Stuttg) 2023; 25:32-42. [PMID: 36245305 DOI: 10.1111/plb.13478] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/28/2022] [Accepted: 10/10/2022] [Indexed: 06/16/2023]
Abstract
In recent years, research interest in plant water uptake strategies has rapidly increased in many disciplines, such as hydrology, plant ecology and ecophysiology. Quantitative modelling approaches to estimate plant water uptake and spatiotemporal dynamics have significantly advanced through different disciplines across scales. Despite this progress, major limitations, for example, predicting plant water uptake under drought or drought impact at large scales, remain. These are less attributed to limitations in process understanding, but rather to a lack of implementation of cross-disciplinary insights into plant water uptake model structure. The main goal of this review is to highlight how the four dominant model approaches, that is, Feddes approach, hydrodynamic approach, optimality and statistical approaches, can be and have been used to create interdisciplinary hybrid models enabling a holistic system understanding that, among other things, embeds plant water uptake plasticity into a broader conceptual view of soil-plant feedbacks of water, nutrient and carbon cycling, or reflects observed drought responses of plant-soil feedbacks and their dynamics under, that is, drought. Specifically, we provide examples of how integration of Bayesian and hydrodynamic approaches might overcome challenges in interpreting plant water uptake related to different travel and residence times of different plant water sources or trade-offs between root system optimization to forage for water and nutrients during different seasons and phenological stages.
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Affiliation(s)
- M Dubbert
- Isotope Biogeochemistry and Gasfluxes, Leibniz Institute of Agricultural Landscape Research (ZALF), Müncheberg, Germany
- Ecosystem Physiology, University of Freiburg, Freiburg, Germany
| | - V Couvreur
- Earth and Life Institute, Université catholique de Louvain, Louvain-la-Neuve, Belgium
| | - A Kübert
- Ecosystem Physiology, University of Freiburg, Freiburg, Germany
- Institute for Atmospheric and Earth System Research (INAR), University of Helsinki, Helsinki, Finland
| | - C Werner
- Ecosystem Physiology, University of Freiburg, Freiburg, Germany
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9
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Mononen T, Kuosmanen T, Cairns J, Mustonen V. Understanding cellular growth strategies via optimal control. J R Soc Interface 2023; 20:20220744. [PMID: 36596459 PMCID: PMC9810423 DOI: 10.1098/rsif.2022.0744] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/05/2023] Open
Abstract
Evolutionary prediction and control are increasingly interesting research topics that are expanding to new areas of application. Unravelling and anticipating successful adaptations to different selection pressures becomes crucial when steering rapidly evolving cancer or microbial populations towards a chosen target. Here we introduce and apply a rich theoretical framework of optimal control to understand adaptive use of traits, which in turn allows eco-evolutionarily informed population control. Using adaptive metabolism and microbial experimental evolution as a case study, we show how demographic stochasticity alone can lead to lag time evolution, which appears as an emergent property in our model. We further show that the cycle length used in serial transfer experiments has practical importance as it may cause unintentional selection for specific growth strategies and lag times. Finally, we show how frequency-dependent selection can be incorporated to the state-dependent optimal control framework allowing the modelling of complex eco-evolutionary dynamics. Our study demonstrates the utility of optimal control theory in elucidating organismal adaptations and the intrinsic decision making of cellular communities with high adaptive potential.
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Affiliation(s)
- Tommi Mononen
- Department of Computer Science, Organismal and Evolutionary Biology Research Programme, University of Helsinki, Helsinki 00014, Finland
| | - Teemu Kuosmanen
- Department of Computer Science, Organismal and Evolutionary Biology Research Programme, University of Helsinki, Helsinki 00014, Finland
| | - Johannes Cairns
- Department of Computer Science, Organismal and Evolutionary Biology Research Programme, University of Helsinki, Helsinki 00014, Finland
| | - Ville Mustonen
- Department of Computer Science, Organismal and Evolutionary Biology Research Programme, University of Helsinki, Helsinki 00014, Finland,Institute of Biotechnology, University of Helsinki, Helsinki 00014, Finland
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10
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Singh HP, Bhatia SK, Bahri Y, Jain R. Optimal control strategies to combat COVID-19 transmission: A mathematical model with incubation time delay. Results in Control and Optimization 2022; 9. [PMCID: PMC9552531 DOI: 10.1016/j.rico.2022.100176] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
The coronavirus disease 2019, started spreading around December 2019, still persists in the population all across the globe. Though different countries have been able to cope with the disease to some extent and vaccination for the same has been developed, it cannot be ignored that the disease is still not on the verge of completely eradicating, which in turn creates a need for having deeper insights of the disease in order to understand it well and hence be able to work towards its eradication. Meanwhile, using mitigation strategies like non-pharmaceutical interventions can help in controlling the disease. In this work, our aim is to study the dynamics of COVID-19 using compartmental approach by applying various analytical methods. We obtain formula for important tools like R0 and establish the stability of disease-free equilibrium point for R0<1. Further, based on R0, we discuss the stability and existence of the endemic equilibrium point. We incorporate various control strategies possible and using optimal control theory, study their expected positive impacts on the spread of the disease. Later, using a biologically feasible set of parameters, we numerically analyse the model. We even study the trend of the outbreak in China, for over 120 days, where the active cases rise up to a peak and then the curve flattens.
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Affiliation(s)
| | | | | | - Riya Jain
- AIAS, Amity University, Noida, India
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11
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McDonald KA, Cusumano JP, Hieronymi A, Rubenson J. Humans trade off whole-body energy cost to avoid overburdening muscles while walking. Proc Biol Sci 2022; 289:20221189. [PMID: 36285498 PMCID: PMC9597406 DOI: 10.1098/rspb.2022.1189] [Citation(s) in RCA: 7] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/21/2022] [Accepted: 09/29/2022] [Indexed: 07/22/2023] Open
Abstract
Metabolic cost minimization is thought to underscore the neural control of locomotion. Yet, avoiding high muscle activation, a cause of fatigue, often outperforms energy minimization in computational predictions of human gait. Discerning the relative importance of these criteria in human walking has proved elusive, in part, because they have not been empirically decoupled. Here, we explicitly decouple whole-body metabolic cost and 'fatigue-like' muscle activation costs (estimated from electromyography) by pitting them against one another using two distinct gait tasks. When experiencing these competing costs, participants (n = 10) chose the task that avoided overburdening muscles (fatigue avoidance) at the expense of higher metabolic power (p < 0.05). Muscle volume-normalized activation more closely models energy use and was also minimized by the participants' decision (p < 0.05), demonstrating that muscle activation was, at best, an inaccurate signal for metabolic energy. Energy minimization was only observed when there was no adverse effect on muscle activation costs. By decoupling whole-body metabolic and muscle activation costs, we provide among the first empirical evidence of humans embracing non-energetic optimality in favour of a clearly defined neuromuscular objective. This finding indicates that local muscle fatigue and effort may well be key factors dictating human walking behaviour and its evolution.
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Affiliation(s)
- Kirsty A. McDonald
- School of Health Sciences, University of New South Wales, Sydney, New South Wales 2052, Australia
- School of Human Sciences, The University of Western Australia, Crawley, Perth, Western Australia 6009, Australia
- Biomechanics Laboratory, Department of Kinesiology, The Pennsylvania State University, University Park, PA 16802, USA
| | - Joseph P. Cusumano
- Department of Engineering Science and Mechanics, The Pennsylvania State University, University Park, PA 16802, USA
| | - Andrew Hieronymi
- School of Visual Arts, The Pennsylvania State University, University Park, PA 16802, USA
| | - Jonas Rubenson
- School of Human Sciences, The University of Western Australia, Crawley, Perth, Western Australia 6009, Australia
- Biomechanics Laboratory, Department of Kinesiology, The Pennsylvania State University, University Park, PA 16802, USA
- Integrative and Biomedical Physiology, Huck Institutes of the Life Sciences, The Pennsylvania State University, University Park, PA 16802, USA
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12
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Herzog B, Schnee S. Exploring a Dualism of Human Rationality: Experimental Study of a Cheating Contest Game. Int J Environ Res Public Health 2022; 19:7675. [PMID: 35805334 PMCID: PMC9265569 DOI: 10.3390/ijerph19137675] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 04/23/2022] [Revised: 06/15/2022] [Accepted: 06/20/2022] [Indexed: 01/25/2023]
Abstract
Rational behavior is a standard assumption in science. Indeed, rationality is required for environmental action towards net-zero emissions or public health interventions during the SARS-CoV-2 pandemic. Yet, little is known about the elements of rationality. This paper explores a dualism of rationality comprised of optimality and consistency. By designing a new guessing game, we experimentally uncover and disentangle two building blocks of human rationality: the notions of optimality and consistency. We find evidence that rationality is largely associated to optimality and weakly to consistency. Remarkably, under uncertainty, rationality gradually shifts to a heuristic notion. Our findings provide insights to better understand human decision making.
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Affiliation(s)
- Bodo Herzog
- Economics Department, ESB Business School, Reutlingen University, 72762 Reutlingen, Germany;
- Reutlingen Research Institute (RRI), 72762 Reutlingen, Germany
- Institute of Finance and Economics (IFE), Reutlingen University, 72762 Reutlingen, Germany
| | - Stefanie Schnee
- Economics Department, ESB Business School, Reutlingen University, 72762 Reutlingen, Germany;
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13
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Abstract
Integration to boundary is an optimal decision algorithm that accumulates evidence until the posterior reaches a decision boundary, resulting in the fastest decisions for a target accuracy. Here, we demonstrated that this advantage incurs a cost in metacognitive accuracy (confidence), generating a cognition/metacognition trade-off. Using computational modeling, we found that integration to a fixed boundary results in less variability in evidence integration and thus reduces metacognitive accuracy, compared with a collapsing-boundary or a random-timer strategy. We examined how decision strategy affects metacognitive accuracy in three cross-domain experiments, in which 102 university students completed a free-response session (evidence terminated by the participant's response) and an interrogation session (fixed number of evidence samples controlled by the experimenter). In both sessions, participants observed a sequence of evidence and reported their choice and confidence. As predicted, the interrogation protocol (preventing integration to boundary) enhanced metacognitive accuracy. We also found that in the free-response sessions, participants integrated evidence to a collapsing boundary-a strategy that achieves an efficient compromise between optimizing choice and metacognitive accuracy.
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Affiliation(s)
| | - Moshe Glickman
- Department of Experimental Psychology, University College London.,Max Planck UCL Centre for Computational Psychiatry and Ageing Research, London, United Kingdom
| | - Stephen M Fleming
- Department of Experimental Psychology, University College London.,Max Planck UCL Centre for Computational Psychiatry and Ageing Research, London, United Kingdom.,Wellcome Centre for Human Neuroimaging, University College London
| | - Marius Usher
- School of Psychological Sciences, Tel Aviv University
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14
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Komsta Ł, Wicha-Komsta K, Kocki T. Being Uncertain in Chromatographic Calibration-Some Unobvious Details in Experimental Design. Molecules 2021; 26:7035. [PMID: 34834127 DOI: 10.3390/molecules26227035] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/10/2021] [Revised: 11/15/2021] [Accepted: 11/19/2021] [Indexed: 12/02/2022] Open
Abstract
This is an introductory tutorial and review about the uncertainty problem in chromatographic calibration. It emphasizes some unobvious, but important details influencing errors in the calibration curve estimation, uncertainty in prediction, as well as the connections and dependences between them, all from various perspectives of uncertainty measurement. Nonuniform D-optimal designs coming from Fedorov theorem are computed and presented. As an example, all possible designs of 24 calibration samples (3–8, 4–6, 6–4, 8–3 and 12–2, both uniform and D-optimal) are compared in context of many optimality criteria. It can be concluded that there are only two independent (orthogonal, but slightly complex) trends in optimality of these designs. The conclusions are important, as the uniform designs with many concentrations are not the best choices, contrary to some intuitive perception. Nonuniform designs are visibly better alternative in most calibration cases.
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15
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Galbraith E, Convertino M. The Eco-Evo Mandala: Simplifying Bacterioplankton Complexity into Ecohealth Signatures. Entropy (Basel) 2021; 23:1471. [PMID: 34828169 PMCID: PMC8625105 DOI: 10.3390/e23111471] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 08/30/2021] [Revised: 10/30/2021] [Accepted: 11/05/2021] [Indexed: 12/24/2022]
Abstract
The microbiome emits informative signals of biological organization and environmental pressure that aid ecosystem monitoring and prediction. Are the many signals reducible to a habitat-specific portfolio that characterizes ecosystem health? Does an optimally structured microbiome imply a resilient microbiome? To answer these questions, we applied our novel Eco-Evo Mandala to bacterioplankton data from four habitats within the Great Barrier Reef, to explore how patterns in community structure, function and genetics signal habitat-specific organization and departures from theoretical optimality. The Mandala revealed communities departing from optimality in habitat-specific ways, mostly along structural and functional traits related to bacterioplankton abundance and interaction distributions (reflected by ϵ and λ as power law and exponential distribution parameters), which are not linearly associated with each other. River and reef communities were similar in their relatively low abundance and interaction disorganization (low ϵ and λ) due to their protective structured habitats. On the contrary, lagoon and estuarine inshore reefs appeared the most disorganized due to the ocean temperature and biogeochemical stress. Phylogenetic distances (D) were minimally informative in characterizing bacterioplankton organization. However, dominant populations, such as Proteobacteria, Bacteroidetes, and Cyanobacteria, were largely responsible for community patterns, being generalists with a large functional gene repertoire (high D) that increases resilience. The relative balance of these populations was found to be habitat-specific and likely related to systemic environmental stress. The position on the Mandala along the three fundamental traits, as well as fluctuations in this ecological state, conveys information about the microbiome's health (and likely ecosystem health considering bacteria-based multitrophic dependencies) as divergence from the expected relative optimality. The Eco-Evo Mandala emphasizes how habitat and the microbiome's interaction network topology are first- and second-order factors for ecosystem health evaluation over taxonomic species richness. Unhealthy microbiome communities and unbalanced microbes are identified not by macroecological indicators but by mapping their impact on the collective proportion and distribution of interactions, which regulates the microbiome's ecosystem function.
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Affiliation(s)
- Elroy Galbraith
- Graduate School of Information Science and Technology, Hokkaido University, Sapporo 060-0814, Japan
| | - Matteo Convertino
- bluEco Lab, Institute of Environment and Ecology, Tsinghua Shenzhen International Graduate School, Tsinghua University, Shenzhen 518055, China;
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16
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Pirrone A, Reina A, Stafford T, Marshall JAR, Gobet F. Magnitude-sensitivity: rethinking decision-making. Trends Cogn Sci 2021; 26:66-80. [PMID: 34750080 DOI: 10.1016/j.tics.2021.10.006] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/14/2021] [Revised: 10/05/2021] [Accepted: 10/05/2021] [Indexed: 11/25/2022]
Abstract
Magnitude-sensitivity refers to the result that performance in decision-making, across domains and organisms, is affected by the total value of the possible alternatives. This simple result offers a window into fundamental issues in decision-making and has led to a reconsideration of ecological decision-making, prominent computational models of decision-making, and optimal decision-making. Moreover, magnitude-sensitivity has inspired the design of new robotic systems that exploit natural solutions and apply optimal decision-making policies. In this article, we review the key theoretical and empirical results about magnitude-sensitivity and highlight the importance that this phenomenon has for the understanding of decision-making. Furthermore, we discuss open questions and ideas for future research.
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Affiliation(s)
- Angelo Pirrone
- Centre for Philosophy of Natural and Social Science, London School of Economics and Political Science, London, UK.
| | - Andreagiovanni Reina
- Institute for Interdisciplinary Studies on Artificial Intelligence (IRIDIA), Université Libre de Bruxelles, Brussels, Belgium
| | - Tom Stafford
- Department of Psychology, University of Sheffield, Sheffield, UK
| | | | - Fernand Gobet
- Centre for Philosophy of Natural and Social Science, London School of Economics and Political Science, London, UK
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17
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Xu H, Wang H, Prentice IC, Harrison SP, Wright IJ. Coordination of plant hydraulic and photosynthetic traits: confronting optimality theory with field measurements. New Phytol 2021; 232:1286-1296. [PMID: 34324717 PMCID: PMC9291854 DOI: 10.1111/nph.17656] [Citation(s) in RCA: 12] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/22/2021] [Accepted: 07/26/2021] [Indexed: 05/13/2023]
Abstract
Close coupling between water loss and carbon dioxide uptake requires coordination of plant hydraulics and photosynthesis. However, there is still limited information on the quantitative relationships between hydraulic and photosynthetic traits. We propose a basis for these relationships based on optimality theory, and test its predictions by analysis of measurements on 107 species from 11 sites, distributed along a nearly 3000-m elevation gradient. Hydraulic and leaf economic traits were less plastic, and more closely associated with phylogeny, than photosynthetic traits. The two sets of traits were linked by the sapwood to leaf area ratio (Huber value, vH ). The observed coordination between vH and sapwood hydraulic conductivity (KS ) and photosynthetic capacity (Vcmax ) conformed to the proposed quantitative theory. Substantial hydraulic diversity was related to the trade-off between KS and vH . Leaf drought tolerance (inferred from turgor loss point, -Ψtlp ) increased with wood density, but the trade-off between hydraulic efficiency (KS ) and -Ψtlp was weak. Plant trait effects on vH were dominated by variation in KS , while effects of environment were dominated by variation in temperature. This research unifies hydraulics, photosynthesis and the leaf economics spectrum in a common theoretical framework, and suggests a route towards the integration of photosynthesis and hydraulics in land-surface models.
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Affiliation(s)
- Huiying Xu
- Ministry of Education Key Laboratory for Earth System ModelingDepartment of Earth System ScienceTsinghua UniversityBeijing100084China
- Joint Center for Global Change Studies (JCGCS)Beijing100875China
| | - Han Wang
- Ministry of Education Key Laboratory for Earth System ModelingDepartment of Earth System ScienceTsinghua UniversityBeijing100084China
- Joint Center for Global Change Studies (JCGCS)Beijing100875China
| | - I. Colin Prentice
- Ministry of Education Key Laboratory for Earth System ModelingDepartment of Earth System ScienceTsinghua UniversityBeijing100084China
- Department of Life SciencesGeorgina Mace Centre for the Living PlanetImperial College LondonSilwood Park Campus, Buckhurst RoadAscotSL5 7PYUK
- Department of Biological SciencesMacquarie UniversityNorth RydeNSW2109Australia
| | - Sandy P. Harrison
- Ministry of Education Key Laboratory for Earth System ModelingDepartment of Earth System ScienceTsinghua UniversityBeijing100084China
- School of Archaeology, Geography and Environmental Sciences (SAGES)University of ReadingReadingRG6 6AHUK
| | - Ian J. Wright
- Department of Biological SciencesMacquarie UniversityNorth RydeNSW2109Australia
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18
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Abstract
The systematic variation of diameters in branched networks has tantalized biologists since the discovery of da Vinci's rule for trees. Da Vinci's rule can be formulated as a power law with exponent two: The square of the mother branch's diameter is equal to the sum of the squares of those of the daughters. Power laws, with different exponents, have been proposed for branching in circulatory systems (Murray's law with exponent 3) and in neurons (Rall's law with exponent 3/2). The laws have been derived theoretically, based on optimality arguments, but, for the most part, have not been tested rigorously. Using superresolution methods to measure the diameters of dendrites in highly branched Drosophila class IV sensory neurons, we have found that these types of power laws do not hold. In their place, we have discovered a different diameter-scaling law: The cross-sectional area is proportional to the number of dendrite tips supported by the branch plus a constant, corresponding to a minimum diameter of the terminal dendrites. The area proportionality accords with a requirement for microtubules to transport materials and nutrients for dendrite tip growth. The minimum diameter may be set by the force, on the order of a few piconewtons, required to bend membrane into the highly curved surfaces of terminal dendrites. Because the observed scaling differs from Rall's law, we propose that cell biological constraints, such as intracellular transport and protrusive forces generated by the cytoskeleton, are important in determining the branched morphology of these cells.
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Affiliation(s)
- Maijia Liao
- Department of Molecular Biophysics and Biochemistry, Yale University, New Haven, CT 06520
| | - Xin Liang
- Tsinghua-Peking Joint Center for Life Sciences, School of Life Sciences, Tsinghua University, 100084 Beijing, China
| | - Jonathon Howard
- Department of Molecular Biophysics and Biochemistry, Yale University, New Haven, CT 06520;
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Capozzoli A, Curcio C, Liseno A. On the Optimal Field Sensing in Near-Field Characterization. Sensors (Basel) 2021; 21:s21134460. [PMID: 34209975 PMCID: PMC8271742 DOI: 10.3390/s21134460] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 03/19/2021] [Revised: 06/16/2021] [Accepted: 06/25/2021] [Indexed: 11/16/2022]
Abstract
We deal with the problem of characterizing a source or scatterer from electromagnetic radiated or scattered field measurements. The problem refers to the amplitude and phase measurements which has applications also to interferometric approaches at optical frequencies. From low frequencies (microwaves) to high frequencies or optics, application examples are near-field/far-field transformations, object restoration from measurements within a pupil, near-field THz imaging, optical coherence tomography and ptychography. When analyzing the transmitting-sensing system, we can define "optimal virtual" sensors by using the Singular Value Decomposition (SVD) approach which has been, since long time, recognized as the "optimal" tool to manage linear algebraic problems. The problem however emerges of discretizing the relevant singular functions, thus defining the field sampling. To this end, we have recently developed an approach based on the Singular Value Optimization (SVO) technique. To make the "virtual" sensors physically realizable, in this paper, two approaches are considered: casting the "virtual" field sensors into arrays reaching the same performance of the "virtual" ones; operating a segmentation of the receiver. Concerning the array case, two ways are followed: synthesize the array by a generalized Gaussian quadrature discretizing the linear reception functionals and use elementary sensors according to SVO. We show that SVO is "optimal" in the sense that it leads to the use of elementary, non-uniformly located field sensors having the same performance of the "virtual" sensors and that generalized Gaussian quadrature has essentially the same performance.
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20
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Contreras J, Ceberio M, Kreinovich V. Why Dilated Convolutional Neural Networks: A Proof of Their Optimality. Entropy (Basel) 2021; 23:e23060767. [PMID: 34207129 PMCID: PMC8233773 DOI: 10.3390/e23060767] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 04/18/2021] [Revised: 06/14/2021] [Accepted: 06/14/2021] [Indexed: 11/16/2022]
Abstract
One of the most effective image processing techniques is the use of convolutional neural networks that use convolutional layers. In each such layer, the value of the layer’s output signal at each point is a combination of the layer’s input signals corresponding to several neighboring points. To improve the accuracy, researchers have developed a version of this technique, in which only data from some of the neighboring points is processed. It turns out that the most efficient case—called dilated convolution—is when we select the neighboring points whose differences in both coordinates are divisible by some constant ℓ. In this paper, we explain this empirical efficiency by proving that for all reasonable optimality criteria, dilated convolution is indeed better than possible alternatives.
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Potkay A, Trugman AT, Wang Y, Venturas MD, Anderegg WRL, Mattos CRC, Fan Y. Coupled whole-tree optimality and xylem hydraulics explain dynamic biomass partitioning. New Phytol 2021; 230:2226-2245. [PMID: 33521942 DOI: 10.1111/nph.17242] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/23/2020] [Accepted: 01/25/2021] [Indexed: 06/12/2023]
Abstract
Trees partition biomass in response to resource limitation and physiological activity. It is presumed that these strategies evolved to optimize some measure of fitness. If the optimization criterion can be specified, then allometry can be modeled from first principles without prescribed parameterization. We present the Tree Hydraulics and Optimal Resource Partitioning (THORP) model, which optimizes allometry by estimating allocation fractions to organs as proportional to their ratio of marginal gain to marginal cost, where gain is net canopy photosynthesis rate, and costs are senescence rates. Root total biomass and profile shape are predicted simultaneously by a unified optimization. Optimal partitioning is solved by a numerically efficient analytical solution. THORP's predictions agree with reported tree biomass partitioning in response to size, water limitations, elevated CO2 and pruning. Roots were sensitive to soil moisture profiles and grew down to the groundwater table when present. Groundwater buffered against water stress regardless of meteorology, stabilizing allometry and root profiles as deep as c. 30 m. Much of plant allometry can be explained by hydraulic considerations. However, nutrient limitations cannot be fully ignored. Rooting mass and profiles were synchronized with hydrological conditions and groundwater even at considerable depths, illustrating that the below ground shapes whole-tree allometry.
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Affiliation(s)
- Aaron Potkay
- Department of Earth and Planetary Sciences, Rutgers University, New Brunswick, NJ, 08854, USA
| | - Anna T Trugman
- Department of Geography, University of California, Santa Barbara, Santa Barbara, CA, 93106, USA
| | - Yujie Wang
- School of Biological Sciences, University of Utah, Salt Lake City, UT, 84112, USA
- Division of Geological and Planetary Sciences, California Institute of Technology, Pasadena, CA, 91125, USA
| | - Martin D Venturas
- School of Biological Sciences, University of Utah, Salt Lake City, UT, 84112, USA
| | - William R L Anderegg
- School of Biological Sciences, University of Utah, Salt Lake City, UT, 84112, USA
| | - Caio R C Mattos
- Department of Earth and Planetary Sciences, Rutgers University, New Brunswick, NJ, 08854, USA
| | - Ying Fan
- Department of Earth and Planetary Sciences, Rutgers University, New Brunswick, NJ, 08854, USA
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22
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Buckley TN. Optimal carbon partitioning helps reconcile the apparent divergence between optimal and observed canopy profiles of photosynthetic capacity. New Phytol 2021; 230:2246-2260. [PMID: 33454975 DOI: 10.1111/nph.17199] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/31/2020] [Accepted: 01/07/2021] [Indexed: 06/12/2023]
Abstract
Photosynthetic capacity per unit irradiance is greater, and the marginal carbon revenue of water (∂A/∂E) is smaller, in shaded leaves than sunlit leaves, apparently contradicting optimization theory. I tested the hypothesis that these patterns arise from optimal carbon partitioning subject to biophysical constraints on leaf water potential. In a whole plant model with two canopy modules, I adjusted carbon partitioning, nitrogen partitioning and leaf water potential to maximize carbon profit or canopy photosynthesis, and recorded how gas exchange parameters compared between shaded and sunlit modules in the optimum. The model predicted that photosynthetic capacity per unit irradiance should be larger, and ∂A/∂E smaller, in shaded modules compared to sunlit modules. This was attributable partly to radiation-driven differences in evaporative demand, and partly to differences in hydraulic conductance arising from the need to balance marginal returns on stem carbon investment between modules. The model verified, however, that invariance in the marginal carbon revenue of N (∂A/∂N) is in fact optimal. The Cowan-Farquhar optimality solution (invariance of ∂A/∂E) does not apply to spatial variation within a canopy. The resulting variation in carbon-water economy explains differences in capacity per unit irradiance, reconciling optimization theory with observations.
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Affiliation(s)
- Thomas N Buckley
- Department of Plant Sciences, University of California, Davis, One Shields Ave, Davis, CA, 95616, USA
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23
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Abstract
Traditional accumulation-to-bound decision-making models assume that all choice options are processed with equal attention. In real life decisions, however, humans alternate their visual fixation between individual items to efficiently gather relevant information (Yang et al., 2016). These fixations also causally affect one's choices, biasing them toward the longer-fixated item (Krajbich et al., 2010). We derive a normative decision-making model in which attention enhances the reliability of information, consistent with neurophysiological findings (Cohen and Maunsell, 2009). Furthermore, our model actively controls fixation changes to optimize information gathering. We show that the optimal model reproduces fixation-related choice biases seen in humans and provides a Bayesian computational rationale for this phenomenon. This insight led to additional predictions that we could confirm in human data. Finally, by varying the relative cognitive advantage conferred by attention, we show that decision performance is benefited by a balanced spread of resources between the attended and unattended items.
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Affiliation(s)
- Anthony I Jang
- Department of Neurobiology, Harvard Medical SchoolBostonUnited States
| | - Ravi Sharma
- Division of Biostatistics and Bioinformatics, Department of Family Medicine and Public Health, UC San Diego School of MedicineLa JollaUnited States
| | - Jan Drugowitsch
- Department of Neurobiology, Harvard Medical SchoolBostonUnited States
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24
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Mayer-Bacon C, Agboha N, Muscalli M, Freeland S. Evolution as a Guide to Designing xeno Amino Acid Alphabets. Int J Mol Sci 2021; 22:ijms22062787. [PMID: 33801827 PMCID: PMC8000707 DOI: 10.3390/ijms22062787] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/12/2021] [Revised: 03/01/2021] [Accepted: 03/05/2021] [Indexed: 02/02/2023] Open
Abstract
Here, we summarize a line of remarkably simple, theoretical research to better understand the chemical logic by which life’s standard alphabet of 20 genetically encoded amino acids evolved. The connection to the theme of this Special Issue, “Protein Structure Analysis and Prediction with Statistical Scoring Functions”, emerges from the ways in which current bioinformatics currently lacks empirical science when it comes to xenoproteins composed largely or entirely of amino acids from beyond the standard genetic code. Our intent is to present new perspectives on existing data from two different frontiers in order to suggest fresh ways in which their findings complement one another. These frontiers are origins/astrobiology research into the emergence of the standard amino acid alphabet, and empirical xenoprotein synthesis.
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Affiliation(s)
- Christopher Mayer-Bacon
- Department of Biological Sciences, University of Maryland, Baltimore County, Baltimore, MD 21250, USA; (C.M.-B.); (N.A.)
| | - Neyiasuo Agboha
- Department of Biological Sciences, University of Maryland, Baltimore County, Baltimore, MD 21250, USA; (C.M.-B.); (N.A.)
| | - Mickey Muscalli
- Individualized Study Program, University of Maryland, Baltimore County, Baltimore, MD 21250, USA;
| | - Stephen Freeland
- Department of Biological Sciences, University of Maryland, Baltimore County, Baltimore, MD 21250, USA; (C.M.-B.); (N.A.)
- Individualized Study Program, University of Maryland, Baltimore County, Baltimore, MD 21250, USA;
- Correspondence:
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25
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Kang JG, Lim DW, Choi YS, Jang WJ, Jung JW. Improved RRT-Connect Algorithm Based on Triangular Inequality for Robot Path Planning. Sensors (Basel) 2021; 21:E333. [PMID: 33419005 DOI: 10.3390/s21020333] [Citation(s) in RCA: 18] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 11/18/2020] [Revised: 12/28/2020] [Accepted: 12/30/2020] [Indexed: 12/01/2022]
Abstract
This paper proposed a triangular inequality-based rewiring method for the rapidly exploring random tree (RRT)-Connect robot path-planning algorithm that guarantees the planning time compared to the RRT algorithm, to bring it closer to the optimum. To check the proposed algorithm’s performance, this paper compared the RRT and RRT-Connect algorithms in various environments through simulation. From these experimental results, the proposed algorithm shows both quicker planning time and shorter path length than the RRT algorithm and shorter path length than the RRT-Connect algorithm with a similar number of samples and planning time.
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26
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Lavergne A, Sandoval D, Hare VJ, Graven H, Prentice IC. Impacts of soil water stress on the acclimated stomatal limitation of photosynthesis: Insights from stable carbon isotope data. Glob Chang Biol 2020; 26:7158-7172. [PMID: 32970907 DOI: 10.1111/gcb.15364] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/11/2020] [Accepted: 09/15/2020] [Indexed: 05/08/2023]
Abstract
Atmospheric aridity and drought both influence physiological function in plant leaves, but their relative contributions to changes in the ratio of leaf internal to ambient partial pressure of CO2 (χ) - an index of adjustments in both stomatal conductance and photosynthetic rate to environmental conditions - are difficult to disentangle. Many stomatal models predicting χ include the influence of only one of these drivers. In particular, the least-cost optimality hypothesis considers the effect of atmospheric demand for water on χ but does not predict how soils with reduced water further influence χ, potentially leading to an overestimation of χ under dry conditions. Here, we use a large network of stable carbon isotope measurements in C3 woody plants to examine the acclimated response of χ to soil water stress. We estimate the ratio of cost factors for carboxylation and transpiration (β) expected from the theory to explain the variance in the data, and investigate the responses of β (and thus χ) to soil water content and suction across seed plant groups, leaf phenological types and regions. Overall, β decreases linearly with soil drying, implying that the cost of water transport along the soil-plant-atmosphere continuum increases as water available in the soil decreases. However, despite contrasting hydraulic strategies, the stomatal responses of angiosperms and gymnosperms to soil water tend to converge, consistent with the optimality theory. The prediction of β as a simple, empirical function of soil water significantly improves χ predictions by up to 6.3 ± 2.3% (mean ± SD of adjusted-R2 ) over 1980-2018 and results in a reduction of around 2% of mean χ values across the globe. Our results highlight the importance of soil water status on stomatal functions and plant water-use efficiency, and suggest the implementation of trait-based hydraulic functions into the model to account for soil water stress.
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Affiliation(s)
- Aliénor Lavergne
- Carbon Cycle Research Group, Space and Atmospheric Physics, Department of Physics, Imperial College London, London, UK
| | - David Sandoval
- Department of Life Sciences, Imperial College London, Ascot, UK
| | - Vincent J Hare
- Carbon Cycle Research Group, Space and Atmospheric Physics, Department of Physics, Imperial College London, London, UK
- Stable Light Isotope Laboratory, University of Cape Town, Cape Town, South Africa
| | - Heather Graven
- Carbon Cycle Research Group, Space and Atmospheric Physics, Department of Physics, Imperial College London, London, UK
- Grantham Institute - Climate Change and the Environment, Imperial College London, London, UK
| | - Iain Colin Prentice
- Department of Life Sciences, Imperial College London, Ascot, UK
- Grantham Institute - Climate Change and the Environment, Imperial College London, London, UK
- Department of Biological Sciences, Macquarie University, North Ryde, NSW, Australia
- Department of Earth System Science, Tsinghua University, Beijing, China
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27
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Salter WT, Merchant A, Trethowan RM, Richards RA, Buckley TN. Wide variation in the suboptimal distribution of photosynthetic capacity in relation to light across genotypes of wheat. AoB Plants 2020; 12:plaa039. [PMID: 32968474 PMCID: PMC7494244 DOI: 10.1093/aobpla/plaa039] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/19/2020] [Accepted: 08/05/2020] [Indexed: 05/22/2023]
Abstract
Suboptimal distribution of photosynthetic capacity in relation to light among leaves reduces potential whole-canopy photosynthesis. We quantified the degree of suboptimality in 160 genotypes of wheat by directly measuring photosynthetic capacity and daily irradiance in flag and penultimate leaves. Capacity per unit daily irradiance was systematically lower in flag than penultimate leaves in most genotypes, but the ratio (γ) of capacity per unit irradiance between flag and penultimate leaves varied widely across genotypes, from less than 0.5 to over 1.2. Variation in γ was most strongly associated with differences in photosynthetic capacity in penultimate leaves, rather than with flag leaf photosynthesis or canopy light penetration. Preliminary genome-wide association analysis identified nine strong marker-trait associations with this trait, which should be validated in future work in other environments and/or materials. Our modelling suggests canopy photosynthesis could be increased by up to 5 % under sunny conditions by harnessing this variation through selective breeding for increased γ.
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Affiliation(s)
- William T Salter
- School of Life and Environmental Sciences, Sydney Institute of Agriculture, The University of Sydney, Brownlow Hill, NSW, Australia
| | - Andrew Merchant
- School of Life and Environmental Sciences, Sydney Institute of Agriculture, The University of Sydney, Brownlow Hill, NSW, Australia
| | - Richard M Trethowan
- School of Life and Environmental Sciences, Sydney Institute of Agriculture, The University of Sydney, Brownlow Hill, NSW, Australia
| | | | - Thomas N Buckley
- Department of Plant Sciences, University of California, Davis, Davis, CA, USA
- Corresponding author’s e-mail address:
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Abstract
Count responses with grouping and right censoring have long been used in surveys to study a variety of behaviors, status, and attitudes. Yet grouping or right-censoring decisions of count responses still rely on arbitrary choices made by researchers. We develop a new method for evaluating grouping and right-censoring decisions of count responses from a (semisupervised) machine-learning perspective. This article uses Poisson multinomial mixture models to conceptualize the data-generating process of count responses with grouping and right censoring and demonstrates the link between grouping-scheme choices and asymptotic distributions of the Poisson mixture. To search for the optimal grouping scheme maximizing objective functions of the Fisher information (matrix), an innovative three-step M algorithm is then proposed to process infinitely many grouping schemes based on Bayesian A-, D-, and E-optimalities. A new R package is developed to implement this algorithm and evaluate grouping schemes of count responses. Results show that an optimal grouping scheme not only leads to a more efficient sampling design but also outperforms a nonoptimal one even if the latter has more groups.
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Affiliation(s)
- Qiang Fu
- Department of Sociology, The University of British Columbia, Vancouver, British Columbia, Canada, V6 T 1Z1
| | - Xin Guo
- Department of Applied Mathematics, The Hong Kong Polytechnic University, Hong Kong
| | - Kenneth C. Land
- John Franklin Crowell Professor Emeritus, Department of Sociology, Social Science Research Institute, Duke University, Durham, NC, USA
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29
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Boyce WP, Lindsay A, Zgonnikov A, Rañó I, Wong-Lin K. Optimality and Limitations of Audio-Visual Integration for Cognitive Systems. Front Robot AI 2020; 7:94. [PMID: 33501261 PMCID: PMC7805627 DOI: 10.3389/frobt.2020.00094] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/01/2019] [Accepted: 06/09/2020] [Indexed: 11/13/2022] Open
Abstract
Multimodal integration is an important process in perceptual decision-making. In humans, this process has often been shown to be statistically optimal, or near optimal: sensory information is combined in a fashion that minimizes the average error in perceptual representation of stimuli. However, sometimes there are costs that come with the optimization, manifesting as illusory percepts. We review audio-visual facilitations and illusions that are products of multisensory integration, and the computational models that account for these phenomena. In particular, the same optimal computational model can lead to illusory percepts, and we suggest that more studies should be needed to detect and mitigate these illusions, as artifacts in artificial cognitive systems. We provide cautionary considerations when designing artificial cognitive systems with the view of avoiding such artifacts. Finally, we suggest avenues of research toward solutions to potential pitfalls in system design. We conclude that detailed understanding of multisensory integration and the mechanisms behind audio-visual illusions can benefit the design of artificial cognitive systems.
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Affiliation(s)
- William Paul Boyce
- Intelligent Systems Research Centre, Ulster University, Magee Campus, Derry Londonderry, Northern Ireland, United Kingdom
| | - Anthony Lindsay
- Intelligent Systems Research Centre, Ulster University, Magee Campus, Derry Londonderry, Northern Ireland, United Kingdom
| | - Arkady Zgonnikov
- AiTech, Delft University of Technology, Delft, Netherlands
- Department of Cognitive Robotics, Faculty of Mechanical, Maritime, and Materials Engineering, Delft University of Technology, Delft, Netherlands
| | - Iñaki Rañó
- Intelligent Systems Research Centre, Ulster University, Magee Campus, Derry Londonderry, Northern Ireland, United Kingdom
| | - KongFatt Wong-Lin
- Intelligent Systems Research Centre, Ulster University, Magee Campus, Derry Londonderry, Northern Ireland, United Kingdom
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30
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Hooshyar M, Anand S, Porporato A. Variational analysis of landscape elevation and drainage networks. Proc Math Phys Eng Sci 2020; 476:20190775. [PMID: 32831601 PMCID: PMC7426051 DOI: 10.1098/rspa.2019.0775] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/11/2019] [Accepted: 05/22/2020] [Indexed: 11/12/2022] Open
Abstract
Landscapes evolve towards surfaces with complex networks of channels and ridges in response to climatic and tectonic forcing. Here, we analyse variational principles giving rise to minimalist models of landscape evolution as a system of partial differential equations that capture the essential dynamics of sediment and water balances. Our results show that in the absence of diffusive soil transport the steady-state surface extremizes the average domain elevation. Depending on the exponent m of the specific drainage area in the erosion term, the critical surfaces are either minima (0 < m < 1) or maxima (m > 1), with m = 1 corresponding to a saddle point. We establish a connection between landscape evolution models and optimal channel networks and elucidate the role of diffusion in the governing variational principles.
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Affiliation(s)
- Milad Hooshyar
- Princeton Environmental Institute and Princeton Institute for International and Regional Studies, Princeton University, Princeton, NJ, USA
| | - Shashank Anand
- Department of Civil and Environmental Engineering, Princeton University, Princeton, NJ, USA
| | - Amilcare Porporato
- Princeton Environmental Institute and Department of Civil and Environmental Engineering, Princeton University, Princeton, NJ, USA
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31
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Luyckx F, Spitzer B, Blangero A, Tsetsos K, Summerfield C. Selective Integration during Sequential Sampling in Posterior Neural Signals. Cereb Cortex 2020; 30:4454-4464. [PMID: 32147695 DOI: 10.1093/cercor/bhaa039] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/06/2019] [Revised: 01/13/2020] [Accepted: 01/30/2020] [Indexed: 11/14/2022] Open
Abstract
Decisions are typically made after integrating information about multiple attributes of alternatives in a choice set. Where observers are obliged to consider attributes in turn, a computational framework known as "selective integration" can capture salient biases in human choices. The model proposes that successive attributes compete for processing resources and integration is biased towards the alternative with the locally preferred attribute. Quantitative analysis shows that this model, although it discards choice-relevant information, is optimal when the observers' decisions are corrupted by noise that occurs beyond the sensory stage. Here, we used electroencephalography (EEG) to test a neural prediction of the model: that locally preferred attributes should be encoded with higher gain in neural signals over the posterior cortex. Over two sessions, human observers judged which of the two simultaneous streams of bars had the higher (or lower) average height. The selective integration model fits the data better than a rival model without bias. Single-trial analysis showed that neural signals contralateral to the preferred attribute covaried more steeply with the decision information conferred by locally preferred attributes. These findings provide neural evidence in support of selective integration, complementing existing behavioral work.
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Affiliation(s)
- Fabrice Luyckx
- Department of Experimental Psychology, University of Oxford, Oxford OX2 6GG, UK
| | - Bernhard Spitzer
- Department of Experimental Psychology, University of Oxford, Oxford OX2 6GG, UK.,Center for Adaptive Rationality, Max Planck Institute for Human Development, Berlin 14195, Germany
| | - Annabelle Blangero
- Department of Experimental Psychology, University of Oxford, Oxford OX2 6GG, UK
| | - Konstantinos Tsetsos
- Department of Neurophysiology and Pathophysiology, University Medical Center Hamburg-Eppendorf, Hamburg 20246, Germany
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32
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Manzone JX, Taravati S, Neyedli HF, Welsh TN. Choices in a key press decision-making task are more optimal after gaining both aiming and reward experience. Q J Exp Psychol (Hove) 2020; 73:2197-2216. [PMID: 32567514 DOI: 10.1177/1747021820940620] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
Abstract
When presented with two different target-penalty configurations of similar maximum expected gain (MEG), participants prefer aiming to configurations with more advantageous spatial, rather than more advantageous gain parameters-perhaps due to the motor system's inherent prioritisation of spatial information during movements with high accuracy demands such as aiming. To test this hypothesis, participants in the present studies chose between target-penalty configurations via key presses to reduce the importance of spatial parameters of the response and performance-related feedback. Configurations varied in spatial (target-penalty region overlap) and gain parameters (negative penalty values) and could have similar or different MEG. Choices were made without prior aiming experience (Experiment 1), after aiming experience provided information of movement variability (Experiment 2), or after aiming experience provided information of movement variability and outcome feedback (Experiment 3). Overall, configurations with advantageous spatial or gain parameters were chosen equally (Both-Similar condition) in all experiments. However, average behaviour at the group level was not reflective of the behaviour of most individual participants with three subgroups emerging: those with a value preference, distance preference, or no preference. In Experiments 1 and 2, these individual differences cannot be explained by MEG differences between configurations or participants' movement variability, but these variables predicted choice behaviour in Experiment 3. Further in the Both-Different condition, participants only selected the larger MEG configuration at a level above chance when both variability and outcome information were given prior to the key press task (Experiment 3). In sum, the data indicate that prioritisation of spatial information did not emerge at the group level when performing key presses and more optimal behaviour emerged when information regarding movement variability and outcome feedback were given.
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Affiliation(s)
- Joseph X Manzone
- Faculty of Kinesiology and Physical Education, Centre for Motor Control, University of Toronto, Toronto, Ontario, Canada
| | - Saba Taravati
- Faculty of Kinesiology and Physical Education, Centre for Motor Control, University of Toronto, Toronto, Ontario, Canada
| | - Heather F Neyedli
- Department of Kinesiology, School of Health and Human Performance, Dalhousie University, Halifax, Nova Scotia, Canada.,Department of Psychology and Neuroscience, Dalhousie University, Halifax, Nova Scotia, Canada
| | - Timothy N Welsh
- Faculty of Kinesiology and Physical Education, Centre for Motor Control, University of Toronto, Toronto, Ontario, Canada
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33
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Peng Y, Bloomfield KJ, Prentice IC. A theory of plant function helps to explain leaf-trait and productivity responses to elevation. New Phytol 2020; 226:1274-1284. [PMID: 31971253 DOI: 10.1111/nph.16447] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/22/2019] [Accepted: 01/13/2020] [Indexed: 06/10/2023]
Abstract
Several publications have examined leaf-trait and carbon-cycling shifts along an Amazon-Andes transect spanning 3.5 km in elevation and 16°C in mean annual temperature. Photosynthetic capacity was previously shown to increase as temperature declines with increasing elevation, counteracting enzyme-kinetic effects. Primary production declines, nonetheless, due to decreasing light availability. We aimed to predict leaf-trait and production gradients from first principles, using published data to test an emerging theory whereby photosynthetic traits and primary production depend on optimal acclimation and/or adaptation to environment. We re-analysed published data for 210 species at 25 sites, fitting linear relationships to elevation for both predicted and observed photosynthetic traits and primary production. Declining leaf-internal/ambient CO2 ratio (χ) and increasing carboxylation (Vcmax ) and electron-transport (Jmax ) capacities with increasing elevation were predicted. Increases in leaf nitrogen content with elevation were explained by increasing Vcmax and leaf mass-per-area. Leaf and soil phosphorus covaried, but after controlling for elevation, no nutrient metric accounted for any additional variance in photosynthetic traits. Primary production was predicted to decline with elevation. This analysis unifies leaf and ecosystem observations in a common theoretical framework. The insensitivity of primary production to temperature is shown to emerge as a consequence of the optimisation of photosynthetic traits.
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Affiliation(s)
- Yunke Peng
- Masters Programme in Ecosystems and Environmental Change, Department of Life Sciences, Imperial College London, Silwood Park Campus, Buckhurst Road, Ascot, SL5 7PY, UK
- AXA Chair Programme in Biosphere and Climate Impacts, Department of Life Sciences, Imperial College London, Silwood Park Campus, Buckhurst Road, Ascot, SL5 7PY, UK
| | - Keith J Bloomfield
- AXA Chair Programme in Biosphere and Climate Impacts, Department of Life Sciences, Imperial College London, Silwood Park Campus, Buckhurst Road, Ascot, SL5 7PY, UK
| | - Iain Colin Prentice
- AXA Chair Programme in Biosphere and Climate Impacts, Department of Life Sciences, Imperial College London, Silwood Park Campus, Buckhurst Road, Ascot, SL5 7PY, UK
- Department of Biological Sciences, Macquarie University, North Ryde, NSW, 2109, Australia
- Department of Earth System Science, Tsinghua University, Beijing, 100084, China
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34
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Rajagopalan A, Assisi C. Effect of Circuit Structure on Odor Representation in the Insect Olfactory System. eNeuro 2020; 7:ENEURO. [PMID: 32345734 DOI: 10.1523/ENEURO.0130-19.2020] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/04/2019] [Revised: 02/10/2020] [Accepted: 02/23/2020] [Indexed: 11/30/2022] Open
Abstract
In neuroscience, the structure of a circuit has often been used to intuit function—an inversion of Louis Kahn’s famous dictum, “Form follows function” (Kristan and Katz, 2006). However, different brain networks may use different network architectures to solve the same problem. The olfactory circuits of two insects, the locust, Schistocerca americana, and the fruit fly, Drosophila melanogaster, serve the same function—to identify and discriminate odors. The neural circuitry that achieves this shows marked structural differences. Projection neurons (PNs) in the antennal lobe innervate Kenyon cells (KCs) of the mushroom body. In locust, each KC receives inputs from ∼50% of PNs, a scheme that maximizes the difference between inputs to any two of ∼50,000 KCs. In contrast, in Drosophila, this number is only 5% and appears suboptimal. Using a computational model of the olfactory system, we show that the activity of KCs is sufficiently high-dimensional that it can separate similar odors regardless of the divergence of PN–KC connections. However, when temporal patterning encodes odor attributes, dense connectivity outperforms sparse connections. Increased separability comes at the cost of reliability. The disadvantage of sparse connectivity can be mitigated by incorporating other aspects of circuit architecture seen in Drosophila. Our simulations predict that Drosophila and locust circuits lie at different ends of a continuum where the Drosophila gives up on the ability to resolve similar odors to generalize across varying environments, while the locust separates odor representations but risks misclassifying noisy variants of the same odor.
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35
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Wang H, Atkin OK, Keenan TF, Smith NG, Wright IJ, Bloomfield KJ, Kattge J, Reich PB, Prentice IC. Acclimation of leaf respiration consistent with optimal photosynthetic capacity. Glob Chang Biol 2020; 26:2573-2583. [PMID: 32091184 DOI: 10.1111/gcb.14980] [Citation(s) in RCA: 42] [Impact Index Per Article: 10.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/25/2019] [Accepted: 12/03/2019] [Indexed: 06/10/2023]
Abstract
Plant respiration is an important contributor to the proposed positive global carbon-cycle feedback to climate change. However, as a major component, leaf mitochondrial ('dark') respiration (Rd ) differs among species adapted to contrasting environments and is known to acclimate to sustained changes in temperature. No accepted theory explains these phenomena or predicts its magnitude. Here we propose that the acclimation of Rd follows an optimal behaviour related to the need to maintain long-term average photosynthetic capacity (Vcmax ) so that available environmental resources can be most efficiently used for photosynthesis. To test this hypothesis, we extend photosynthetic co-ordination theory to predict the acclimation of Rd to growth temperature via a link to Vcmax , and compare predictions to a global set of measurements from 112 sites spanning all terrestrial biomes. This extended co-ordination theory predicts that field-measured Rd and Vcmax accessed at growth temperature (Rd,tg and Vcmax,tg ) should increase by 3.7% and 5.5% per degree increase in growth temperature. These acclimated responses to growth temperature are less steep than the corresponding instantaneous responses, which increase 8.1% and 9.9% per degree of measurement temperature for Rd and Vcmax respectively. Data-fitted responses proof indistinguishable from the values predicted by our theory, and smaller than the instantaneous responses. Theory and data are also shown to agree that the basal rates of both Rd and Vcmax assessed at 25°C (Rd,25 and Vcmax,25 ) decline by ~4.4% per degree increase in growth temperature. These results provide a parsimonious general theory for Rd acclimation to temperature that is simpler-and potentially more reliable-than the plant functional type-based leaf respiration schemes currently employed in most ecosystem and land-surface models.
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Affiliation(s)
- Han Wang
- Ministry of Education Key Laboratory for Earth System Modelling, Department of Earth System Science, Tsinghua University, Beijing, China
- Joint Centre for Global Change Studies, Tsinghua University, Beijing, China
| | - Owen K Atkin
- Division of Plant Sciences, Research School of Biology, The Australian National University, Canberra, ACT, Australia
- Australian Research Council Centre of Excellence in Plant Energy Biology, Research School of Biology, The Australian National University, Canberra, ACT, Australia
| | - Trevor F Keenan
- Department of Environmental Science, Policy and Management, UC Berkeley, Berkeley, CA, USA
- Climate and Ecosystem Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, CA, USA
| | - Nicholas G Smith
- Department of Biological Sciences, Texas Tech University, Lubbock, TX, USA
| | - Ian J Wright
- Department of Biological Sciences, Macquarie University, Sydney, NSW, Australia
| | | | - Jens Kattge
- Max Planck Institute for Biogeochemistry, Jena, Germany
- German Centre for Integrative Biodiversity Research Halle-Jena-Leipzig, Leipzig, Germany
| | - Peter B Reich
- Department of Forest Resources, University of Minnesota, St. Paul, MN, USA
- Hawkesbury Institute for the Environment, Western Sydney University, Penrith, NSW, Australia
| | - I Colin Prentice
- Ministry of Education Key Laboratory for Earth System Modelling, Department of Earth System Science, Tsinghua University, Beijing, China
- Department of Biological Sciences, Macquarie University, Sydney, NSW, Australia
- AXA Chair of Biosphere and Climate Impacts, Department of Life Sciences, Imperial College London, Ascot, UK
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36
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Lavergne A, Voelker S, Csank A, Graven H, de Boer HJ, Daux V, Robertson I, Dorado-Liñán I, Martínez-Sancho E, Battipaglia G, Bloomfield KJ, Still CJ, Meinzer FC, Dawson TE, Julio Camarero J, Clisby R, Fang Y, Menzel A, Keen RM, Roden JS, Prentice IC. Historical changes in the stomatal limitation of photosynthesis: empirical support for an optimality principle. New Phytol 2020; 225:2484-2497. [PMID: 31696932 DOI: 10.1111/nph.16314] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/12/2019] [Accepted: 10/31/2019] [Indexed: 05/08/2023]
Abstract
The ratio of leaf internal (ci ) to ambient (ca ) partial pressure of CO2 , defined here as χ, is an index of adjustments in both leaf stomatal conductance and photosynthetic rate to environmental conditions. Measurements and proxies of this ratio can be used to constrain vegetation model uncertainties for predicting terrestrial carbon uptake and water use. We test a theory based on the least-cost optimality hypothesis for modelling historical changes in χ over the 1951-2014 period, across different tree species and environmental conditions, as reconstructed from stable carbon isotopic measurements across a global network of 103 absolutely dated tree-ring chronologies. The theory predicts optimal χ as a function of air temperature, vapour pressure deficit, ca and atmospheric pressure. The theoretical model predicts 39% of the variance in χ values across sites and years, but underestimates the intersite variability in the reconstructed χ trends, resulting in only 8% of the variance in χ trends across years explained by the model. Overall, our results support theoretical predictions that variations in χ are tightly regulated by the four environmental drivers. They also suggest that explicitly accounting for the effects of plant-available soil water and other site-specific characteristics might improve the predictions.
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Affiliation(s)
- Aliénor Lavergne
- Department of Life Sciences, Imperial College London, Silwood Park Campus, Buckhurst Road, Ascot, SL5 7PY, UK
- Department of Physics, Imperial College London, Exhibition Road, London, SW7 2AZ, UK
| | - Steve Voelker
- Department of Environmental and Forest Biology, SUNY College of Environmental Science and Forestry, Syracuse, NY, 13210, USA
| | - Adam Csank
- Department of Geography, University of Nevada-Reno, 1664 N. Virginia St, Reno, NV, 89557, USA
| | - Heather Graven
- Department of Physics, Imperial College London, Exhibition Road, London, SW7 2AZ, UK
- Grantham Institute - Climate Change and the Environment, Imperial College London, Exhibition Road, London, SW7 2AZ, UK
| | - Hugo J de Boer
- Department of Environmental Sciences, Utrecht University, 3584 CB, Utrecht, the Netherlands
| | - Valérie Daux
- Laboratoire des Sciences du Climat et de l'Environnement, CEA-CNRS-UVSQ, 91191, Gif-sur-Yvette, France
| | - Iain Robertson
- Department of Geography, Swansea University, Swansea, SA2 8PP, UK
| | - Isabel Dorado-Liñán
- Forest Genetics and Ecophysiology Research Group, Technical University of Madrid, Madrid, 28040, Spain
| | - Elisabet Martínez-Sancho
- Swiss Federal Institute for Forest, Snow and Landscape Research WSL, Zürcherstrasse 111, Birmensdorf, 8903, Switzerland
| | - Giovanna Battipaglia
- Department of Environmental, Biological and Pharmaceutical Sciences and Technologies, University of Campania "L. Vanvitelli", Via Vivaldi, 81100, Caserta, Italy
| | - Keith J Bloomfield
- Department of Life Sciences, Imperial College London, Silwood Park Campus, Buckhurst Road, Ascot, SL5 7PY, UK
| | - Christopher J Still
- Department of Forest Ecosystems & Society, Oregon State University, Corvallis, OR, 97331-5704, USA
| | - Frederick C Meinzer
- USDA Forest Service, Pacific Northwest Research Station, Corvallis, OR, 97331-8550, USA
| | - Todd E Dawson
- Department of Integrative Biology, University of California - Berkeley, Berkeley, CA, 94720-3200, USA
| | - J Julio Camarero
- Instituto Pirenaico de Ecología (IPE-CSIC), E-50192, Zaragoza, Spain
| | - Rory Clisby
- Department of Geography, Swansea University, Swansea, SA2 8PP, UK
| | - Yunting Fang
- Institute of Applied Ecology, Chinese Academy of Sciences, Shenyang, 110016, China
| | - Annette Menzel
- Ecoclimatology, Department of Ecology and Ecosystem Management, Technical University of Munich, 85354, Freising, Germany
| | - Rachel M Keen
- Division of Biology, Kansas State University, Manhattan, KS, 66506, USA
| | - John S Roden
- Department of Biology, Southern Oregon University, Ashland, OR, 97520, USA
| | - I Colin Prentice
- Department of Life Sciences, Imperial College London, Silwood Park Campus, Buckhurst Road, Ascot, SL5 7PY, UK
- Grantham Institute - Climate Change and the Environment, Imperial College London, Exhibition Road, London, SW7 2AZ, UK
- Department of Biological Sciences, Macquarie University, North Ryde, NSW, 2109, Australia
- Department of Earth System Science, Tsinghua University, Beijing, 100084, China
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37
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Pappas I, Craig MM, Menon DK, Stamatakis EA. Structural optimality and neurogenetic expression mediate functional dynamics in the human brain. Hum Brain Mapp 2020; 41:2229-2243. [PMID: 32027077 PMCID: PMC7267953 DOI: 10.1002/hbm.24942] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/13/2019] [Revised: 01/24/2020] [Accepted: 01/27/2020] [Indexed: 12/17/2022] Open
Abstract
The human brain exhibits a rich functional repertoire in terms of complex functional connectivity patterns during rest and tasks. However, how this is developed upon a fixed structural anatomy remains poorly understood. Here we investigated the hypothesis that resting state functional connectivity and the manner in which it changes during tasks related to a set of underlying structural connections that promote optimal communication in the brain. We used a game‐theoretic model to identify such optimal connections in the structural connectome of 50 healthy individuals and subsequently used the optimal structural connections to predict resting‐state functional connectivity with high accuracy. In contrast, we found that nonoptimal connections accurately predicted functional connectivity during a working memory task. We further found that this balance between optimal and nonoptimal connections between brain regions was associated with a specific gene expression linked to neurotransmission. This multimodal evidence shows for the first time that structure–function relationships in the human brain are related to how brain networks navigate information along different white matter connections as well as the brain's underlying genetic profile.
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Affiliation(s)
- Ioannis Pappas
- Division of Anaesthesia, Department of Medicine, School of Clinical Medicine, University of Cambridge, Cambridge, UK.,Wolfson Brain Imaging Centre, Department of Clinical Neurosciences, School of Clinical Medicine, University of Cambridge, Cambridge, UK.,Helen Wills Neuroscience Institute, University of California - Berkeley, Berkeley, CA
| | - Michael M Craig
- Division of Anaesthesia, Department of Medicine, School of Clinical Medicine, University of Cambridge, Cambridge, UK.,Wolfson Brain Imaging Centre, Department of Clinical Neurosciences, School of Clinical Medicine, University of Cambridge, Cambridge, UK
| | - David K Menon
- Division of Anaesthesia, Department of Medicine, School of Clinical Medicine, University of Cambridge, Cambridge, UK.,Wolfson Brain Imaging Centre, Department of Clinical Neurosciences, School of Clinical Medicine, University of Cambridge, Cambridge, UK
| | - Emmanuel A Stamatakis
- Division of Anaesthesia, Department of Medicine, School of Clinical Medicine, University of Cambridge, Cambridge, UK.,Wolfson Brain Imaging Centre, Department of Clinical Neurosciences, School of Clinical Medicine, University of Cambridge, Cambridge, UK
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Abstract
Diffusion decision models (DDMs) are immensely successful models for decision making under uncertainty and time pressure. In the context of perceptual decision making, these models typically start with two input units, organized in a neuron-antineuron pair. In contrast, in the brain, sensory inputs are encoded through the activity of large neuronal populations. Moreover, while DDMs are wired by hand, the nervous system must learn the weights of the network through trial and error. There is currently no normative theory of learning in DDMs and therefore no theory of how decision makers could learn to make optimal decisions in this context. Here, we derive such a rule for learning a near-optimal linear combination of DDM inputs based on trial-by-trial feedback. The rule is Bayesian in the sense that it learns not only the mean of the weights but also the uncertainty around this mean in the form of a covariance matrix. In this rule, the rate of learning is proportional (respectively, inversely proportional) to confidence for incorrect (respectively, correct) decisions. Furthermore, we show that, in volatile environments, the rule predicts a bias toward repeating the same choice after correct decisions, with a bias strength that is modulated by the previous choice's difficulty. Finally, we extend our learning rule to cases for which one of the choices is more likely a priori, which provides insights into how such biases modulate the mechanisms leading to optimal decisions in diffusion models.
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Affiliation(s)
- Jan Drugowitsch
- Department of Neurobiology, Harvard Medical School, Boston, MA 02115;
| | - André G Mendonça
- Champalimaud Research, Champalimaud Centre for the Unknown, 1400-038 Lisbon, Portugal
| | - Zachary F Mainen
- Champalimaud Research, Champalimaud Centre for the Unknown, 1400-038 Lisbon, Portugal
| | - Alexandre Pouget
- Department of Basic Neuroscience, University of Geneva, CH-1211 Geneva, Switzerland
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39
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Bidari S, Peleg O, Kilpatrick ZP. Social inhibition maintains adaptivity and consensus of honeybees foraging in dynamic environments. R Soc Open Sci 2019; 6:191681. [PMID: 31903216 PMCID: PMC6936270 DOI: 10.1098/rsos.191681] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 09/24/2019] [Accepted: 11/13/2019] [Indexed: 06/10/2023]
Abstract
To effectively forage in natural environments, organisms must adapt to changes in the quality and yield of food sources across multiple timescales. Individuals foraging in groups act based on both their private observations and the opinions of their neighbours. How do these information sources interact in changing environments? We address this problem in the context of honeybee colonies whose inhibitory social interactions promote adaptivity and consensus needed for effective foraging. Individual and social interactions within a mathematical model of collective decisions shape the nutrition yield of a group foraging from feeders with temporally switching quality. Social interactions improve foraging from a single feeder if temporal switching is fast or feeder quality is low. When the colony chooses from multiple feeders, the most beneficial form of social interaction is direct switching, whereby bees flip the opinion of nest-mates foraging at lower-yielding feeders. Model linearization shows that effective social interactions increase the fraction of the colony at the correct feeder (consensus) and the rate at which bees reach that feeder (adaptivity). Our mathematical framework allows us to compare a suite of social inhibition mechanisms, suggesting experimental protocols for revealing effective colony foraging strategies in dynamic environments.
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Affiliation(s)
- Subekshya Bidari
- Department of Applied Mathematics, University of Colorado, Boulder, CO 80309, USA
| | - Orit Peleg
- Department of Computer Science, University of Colorado, Boulder, CO 80309, USA
- BioFrontiers Institute, University of Colorado, Boulder, CO 80309, USA
- Santa Fe Institute, Santa Fe, NM 87501, USA
| | - Zachary P. Kilpatrick
- Department of Applied Mathematics, University of Colorado, Boulder, CO 80309, USA
- Department of Physiology and Biophysics, University of Colorado School of Medicine, Aurora, CO 80045, USA
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40
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Korem Kohanim Y, Levi D, Jona G, Towbin BD, Bren A, Alon U. A Bacterial Growth Law out of Steady State. Cell Rep 2019; 23:2891-2900. [PMID: 29874577 DOI: 10.1016/j.celrep.2018.05.007] [Citation(s) in RCA: 39] [Impact Index Per Article: 7.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/02/2017] [Revised: 02/21/2018] [Accepted: 05/01/2018] [Indexed: 11/28/2022] Open
Abstract
Bacterial growth follows simple laws in constant conditions. However, bacteria in nature often face fluctuating environments. We therefore ask whether there are growth laws that apply to changing environments. We derive a law for upshifts using an optimal resource-allocation model: the post-shift growth rate equals the geometrical mean of the pre-shift growth rate and the growth rate on saturating carbon. We test this using chemostat and batch culture experiments, as well as previous data from several species. The increase in growth rate after an upshift indicates that ribosomes have spare capacity (SC). We demonstrate theoretically that SC has the cost of slow steady-state growth but is beneficial after an upshift because it prevents large overshoots in intracellular metabolites and allows rapid response to change. We also provide predictions for downshifts. The present study quantifies the optimal degree of SC, which rises the slower the growth rate, and suggests that SC can be precisely regulated.
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Affiliation(s)
- Yael Korem Kohanim
- Department of Molecular Cell Biology, Weizmann Institute of Science, Rehovot 7610001, Israel
| | - Dikla Levi
- Department of Life Sciences Core Facilities, Weizmann Institute of Science, Rehovot 7610001, Israel
| | - Ghil Jona
- Department of Life Sciences Core Facilities, Weizmann Institute of Science, Rehovot 7610001, Israel
| | - Benjamin D Towbin
- Friedrich Miescher Institute for Biomedical Research, Maulbeerstrasse 66, 4058 Basel, Switzerland
| | - Anat Bren
- Department of Molecular Cell Biology, Weizmann Institute of Science, Rehovot 7610001, Israel
| | - Uri Alon
- Department of Molecular Cell Biology, Weizmann Institute of Science, Rehovot 7610001, Israel.
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41
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Abstract
Survival and fertility are the two most basic components of fitness, and they drive the evolution of a life cycle. A trade-off between them is usually present: when survival increases, fertility decreases-and vice versa. Here we show that at an evolutionary optimum, the generation time is a measure of the strength of the trade-off between overall survival and overall fertility in a life cycle. Our result both helps to explain the known fact that the generation time describes the speed of living in the slow-fast continuum of life cycles and may have implications for the extrapolation from model organisms of longevity to humans.
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42
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Herrmann HA, Schwartz JM, Johnson GN. Metabolic acclimation-a key to enhancing photosynthesis in changing environments? J Exp Bot 2019; 70:3043-3056. [PMID: 30997505 DOI: 10.1093/jxb/erz157] [Citation(s) in RCA: 22] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/17/2018] [Accepted: 03/21/2019] [Indexed: 05/18/2023]
Abstract
Plants adjust their photosynthetic capacity in response to their environment in a way that optimizes their yield and fitness. There is growing evidence that this acclimation is a response to changes in the leaf metabolome, but the extent to which these are linked and how this is optimized remain poorly understood. Using as an example the metabolic perturbations occurring in response to cold, we define the different stages required for acclimation, discuss the evidence for a metabolic temperature sensor, and suggest further work towards designing climate-smart crops. In particular, we discuss how constraint-based and kinetic metabolic modelling approaches can be used to generate targeted hypotheses about relevant pathways, and argue that a stronger integration of experimental and in silico studies will help us to understand the tightly regulated interplay of carbon partitioning and resource allocation required for photosynthetic acclimation to different environmental conditions.
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Affiliation(s)
- Helena A Herrmann
- School of Earth and Environmental Sciences, Faculty of Science and Engineering, University of Manchester, Manchester, UK
- Division of Evolution & Genomic Sciences, Faculty of Biology, Medicine and Health, University of Manchester, Manchester, UK
| | - Jean-Marc Schwartz
- Division of Evolution & Genomic Sciences, Faculty of Biology, Medicine and Health, University of Manchester, Manchester, UK
| | - Giles N Johnson
- School of Earth and Environmental Sciences, Faculty of Science and Engineering, University of Manchester, Manchester, UK
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Ahmed N, Rafaqat M, Ishfaq K, Ur Rehman A, Hassan A, Umer U, Ragab AE, Al-Zabidi A. Comparison of Laser Milling Performance against Difficult-To-Cut Alloys: Parametric Significance, Modeling and Optimization for Targeted Material Removal. Materials (Basel) 2019; 12:E1674. [PMID: 31126030 DOI: 10.3390/ma12101674] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 03/28/2019] [Revised: 04/16/2019] [Accepted: 05/20/2019] [Indexed: 12/02/2022]
Abstract
During laser milling, the objective is not always to maximize the material removal rate (MRR). Milling of new material with targeted MRR is challenging without prior knowledge and established sets of laser parameters. The laser milling performance has been evaluated for three important aerospace alloys, i.e., titanium alloy, nickel alloy and aluminum alloy using the response surface method experimental plan (54 experiments for each alloy). Parametric effects of five important laser parameters, statistical analysis (main effects, interaction effects, strength and direction of effects), mathematical modeling and optimality search is conducted for the said alloys. Under the non-optimized laser parameters, the actual MRR significantly varies from the targeted MRR. Variation in the aluminum alloy is at the top as compared to the other two alloys. Among other significant terms, three terms have the largest effect on MRR in the case of TiA, two terms in the case of NiA, and five terms in the case of AlA. Under the optimized sets of laser parameters, the actual material removal highly close to the desired level (100%) can be achieved with minimum variation in all the three alloys. Mathematical models proposed here have the capability to well predict material removal prior to the actual machining of Ti6Al4V, Inconel 718 and AA 2024.
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Chan JY, Bonser SP, Powell JR, Cornwell WK. When to cut your losses: Dispersal allocation in an asexual filamentous fungus in response to competition. Ecol Evol 2019; 9:4129-4137. [PMID: 31015993 PMCID: PMC6467841 DOI: 10.1002/ece3.5041] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/06/2018] [Revised: 01/17/2019] [Accepted: 02/01/2019] [Indexed: 11/12/2022] Open
Abstract
Fungal communities often form on ephemeral substrates and dispersal is critical for the persistence of fungi among the islands that form these metacommunities. Within each substrate, competition for space and resources is vital for the local persistence of fungi. The capacity to detect and respond by dispersal away from unfavorable conditions may confer higher fitness in fungi. Informed dispersal theory posits that organisms are predicted to detect information about their surroundings which may trigger a dispersal response. As such, we expect that fungi will increase allocation to dispersal in the presence of a strong competitor.In a laboratory setting, we tested how competition with other filamentous fungi affected the development of conidial pycnidiomata (asexual fruiting bodies) in Phacidium lacerum over 10 days. Phacidium lacerum was not observed to produce more asexual fruiting bodies or produce them earlier when experiencing interspecific competition with other filamentous fungi. However, we found that a trade-off existed between growth rate and allocation to dispersal. We also observed a defensive response to specific interspecific competitors in the form of hyphal melanization of the colony which may have an impact on the growth rate and dispersal trade-off.Our results suggest that P. lacerum have the capacity to detect and respond to competitors by changing their allocation to dispersal and growth. However, allocation to defence may come at a cost to growth and dispersal. Thus, it is likely that optimal life history allocation in fungi constrained to ephemeral resources will depend on the competitive strength of neighbors surrounding them.
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Affiliation(s)
- Justin Y. Chan
- Evolution and Ecology Research Centre, School of Biological, Earth and Environmental SciencesUniversity of New South WalesSydneyNSWAustralia
| | - Stephen P. Bonser
- Evolution and Ecology Research Centre, School of Biological, Earth and Environmental SciencesUniversity of New South WalesSydneyNSWAustralia
| | - Jeff R. Powell
- Hawkesbury Institute for the EnvironmentWestern Sydney UniversityPenrithNSWAustralia
| | - William K. Cornwell
- Evolution and Ecology Research Centre, School of Biological, Earth and Environmental SciencesUniversity of New South WalesSydneyNSWAustralia
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Abstract
Among the different procedures that model gambling behavior in non-human animals, the "suboptimal choice procedure" has been extensively employed for analyzing the impact of environmental cues on choice behavior. It has been repeatedly demonstrated that pigeons prefer an alternative that infrequently presents a stimulus that signals a larger amount of reinforcement, than another alternative that always presents a stimulus associated with a smaller amount of reinforcement, even though the net rate of reinforcement is lower in the former. In the present study, we tested rats in the magnitude version of the suboptimal choice procedure. Eight rats were given a choice between two alternatives: a) one in which a stimulus predicting the delivery of ten pellets was presented with probability (p) = 0.2 and a stimulus predicting zero pellets was presented with p = 0.8, and b) one in which either of two stimuli predicted the delivery of three pellets with p = 1.0. Contrary to the consistent and robust suboptimal behavior of pigeons, rats preferred the optimal alternative. This effect occurred despite the high index of discrimination of the stimuli associated with the different outcomes shown by the rats. The relevance of this result to the development of animal models of gambling behavior is discussed.
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Affiliation(s)
- Vladimir Orduña
- Facultad de Psicología, Universidad Nacional Autónoma de México, México D.F., 04510, Mexico.
| | - Rodrigo Alba
- Facultad de Psicología, Universidad Nacional Autónoma de México, México D.F., 04510, Mexico
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Petkova MD, Tkačik G, Bialek W, Wieschaus EF, Gregor T. Optimal Decoding of Cellular Identities in a Genetic Network. Cell 2019; 176:844-855.e15. [PMID: 30712870 DOI: 10.1016/j.cell.2019.01.007] [Citation(s) in RCA: 83] [Impact Index Per Article: 16.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/22/2018] [Revised: 11/04/2018] [Accepted: 01/02/2019] [Indexed: 11/24/2022]
Abstract
In developing organisms, spatially prescribed cell identities are thought to be determined by the expression levels of multiple genes. Quantitative tests of this idea, however, require a theoretical framework capable of exposing the rules and precision of cell specification over developmental time. We use the gap gene network in the early fly embryo as an example to show how expression levels of the four gap genes can be jointly decoded into an optimal specification of position with 1% accuracy. The decoder correctly predicts, with no free parameters, the dynamics of pair-rule expression patterns at different developmental time points and in various mutant backgrounds. Precise cellular identities are thus available at the earliest stages of development, contrasting the prevailing view of positional information being slowly refined across successive layers of the patterning network. Our results suggest that developmental enhancers closely approximate a mathematically optimal decoding strategy.
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Affiliation(s)
- Mariela D Petkova
- Joseph Henry Laboratories of Physics and the Lewis-Sigler Institute for Integrative Genomics, Princeton University, Princeton, NJ 08544, USA; Program in Biophysics, Harvard University, Cambridge, MA 02138, USA
| | - Gašper Tkačik
- Institute of Science and Technology Austria, Am Campus 1, 3400 Klosterneuburg, Austria
| | - William Bialek
- Joseph Henry Laboratories of Physics and the Lewis-Sigler Institute for Integrative Genomics, Princeton University, Princeton, NJ 08544, USA
| | - Eric F Wieschaus
- Department of Molecular Biology and Howard Hughes Medical Institute, Princeton University, Princeton, NJ 08544, USA
| | - Thomas Gregor
- Joseph Henry Laboratories of Physics and the Lewis-Sigler Institute for Integrative Genomics, Princeton University, Princeton, NJ 08544, USA; Department of Developmental and Stem Cell Biology, UMR3738, Institut Pasteur, 75015 Paris, France.
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Abstract
Human perceptual decisions are often described as optimal. Critics of this view have argued that claims of optimality are overly flexible and lack explanatory power. Meanwhile, advocates for optimality have countered that such criticisms single out a few selected papers. To elucidate the issue of optimality in perceptual decision making, we review the extensive literature on suboptimal performance in perceptual tasks. We discuss eight different classes of suboptimal perceptual decisions, including improper placement, maintenance, and adjustment of perceptual criteria; inadequate tradeoff between speed and accuracy; inappropriate confidence ratings; misweightings in cue combination; and findings related to various perceptual illusions and biases. In addition, we discuss conceptual shortcomings of a focus on optimality, such as definitional difficulties and the limited value of optimality claims in and of themselves. We therefore advocate that the field drop its emphasis on whether observed behavior is optimal and instead concentrate on building and testing detailed observer models that explain behavior across a wide range of tasks. To facilitate this transition, we compile the proposed hypotheses regarding the origins of suboptimal perceptual decisions reviewed here. We argue that verifying, rejecting, and expanding these explanations for suboptimal behavior - rather than assessing optimality per se - should be among the major goals of the science of perceptual decision making.
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Affiliation(s)
- Dobromir Rahnev
- School of Psychology, Georgia Institute of Technology, Atlanta, GA 30332.
| | - Rachel N Denison
- Department of Psychology and Center for Neural Science, New York University, New York, NY 10003.
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Abstract
Human perceptual inference has been fruitfully characterized as a normative Bayesian process in which sensory evidence and priors are multiplicatively combined to form posteriors from which sensory estimates can be optimally read out. We tested whether this basic Bayesian framework could explain human subjects' behavior in two estimation tasks in which we varied the strength of sensory evidence (motion coherence or contrast) and priors (set of directions or orientations). We found that despite excellent agreement of estimates mean and variability with a Basic Bayesian observer model, the estimate distributions were bimodal with unpredicted modes near the prior and the likelihood. We developed a model that switched between prior and sensory evidence rather than integrating the two, which better explained the data than the Basic and several other Bayesian observers. Our data suggest that humans can approximate Bayesian optimality with a switching heuristic that forgoes multiplicative combination of priors and likelihoods.
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Affiliation(s)
- Steeve Laquitaine
- Department of Psychology, Stanford University, Stanford, CA 94305, USA; Laboratory for Human Systems Neuroscience, RIKEN Brain Science Institute, Wako-shi, Saitama 351-0198, Japan
| | - Justin L Gardner
- Department of Psychology, Stanford University, Stanford, CA 94305, USA; Laboratory for Human Systems Neuroscience, RIKEN Brain Science Institute, Wako-shi, Saitama 351-0198, Japan.
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Tsank Y, Eckstein MP. Domain Specificity of Oculomotor Learning after Changes in Sensory Processing. J Neurosci 2017; 37:11469-84. [PMID: 29054879 DOI: 10.1523/JNEUROSCI.1208-17.2017] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/26/2017] [Revised: 08/28/2017] [Accepted: 09/26/2017] [Indexed: 11/21/2022] Open
Abstract
Humans visually process the world with varying spatial resolution and can program their eye movements optimally to maximize information acquisition for a variety of everyday tasks. Diseases such as macular degeneration can change visual sensory processing, introducing central vision loss (a scotoma). However, humans can learn to direct a new preferred retinal location to regions of interest for simple visual tasks. Whether such learned compensatory saccades are optimal and generalize to more complex tasks, which require integrating information across a large area of the visual field, is not well understood. Here, we explore the possible effects of central vision loss on the optimal saccades during a face identification task, using a gaze-contingent simulated scotoma. We show that a new foveated ideal observer with a central scotoma correctly predicts that the human optimal point of fixation to identify faces shifts from just below the eyes to one that is at the tip of the nose and another at the top of the forehead. However, even after 5000 trials, humans of both sexes surprisingly do not change their initial fixations to adapt to the new optimal fixation points to faces. In contrast, saccades do change for tasks such as object following and to a lesser extent during search. Our findings argue against a central brain motor-compensatory mechanism that generalizes across tasks. They instead suggest task specificity in the learning of oculomotor plans in response to changes in front-end sensory processing and the possibility of separate domain-specific representations of learned oculomotor plans in the brain.SIGNIFICANCE STATEMENT The mechanism by which humans adapt eye movements in response to central vision loss is still not well understood and carries importance for gaining a fundamental understanding of brain plasticity. We show that although humans adapt their eye movements for simpler tasks such as object following and search, these adaptations do not generalize to more complex tasks such as face identification. We provide the first computational model to predict where humans with central vision loss should direct their eye movements in face identification tasks, which could become a critical tool in making patient-specific recommendations. Based on these results, we suggest a novel theory for oculomotor learning: a distributed representation of learned eye-movement plans represented in domain-specific areas of the brain.
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Hermus M, Boesveld I, van der Pal-de Bruin K, Wiegers T. Development of the Optimality Index-NL2015, an Instrument to Measure Outcomes of Maternity Care. J Midwifery Womens Health 2017; 62:580-588. [PMID: 28950442 DOI: 10.1111/jmwh.12650] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/15/2016] [Revised: 04/20/2017] [Accepted: 05/09/2017] [Indexed: 11/28/2022]
Abstract
INTRODUCTION An optimality index is a composite tool to measure maximum outcome with minimal intervention. It focuses on optimality instead of on normality and is useful in comparing differences in processes and perinatal outcomes for women at low risk of complications. The latest Dutch version dates from 2 decades ago, and international versions of the optimality index are not directly applicable to the Dutch maternity system. Most data for perinatal research in the Netherlands are derived from a national perinatal database: the Netherlands Perinatal Registry. The aim of this study was to develop a new Dutch version of the optimality index (OI-NL2015) that could be calculated from data derived from this national perinatal database and to assess the reliability of these data for use in the index. METHODS Potential items were collected by a thorough comparison of earlier (inter)national optimality indexes and the current data collection of the national database. All items were reviewed by 2 experts in maternity care and assessed for importance, relevance for the Dutch maternity care system, and feasibility to retrieve information on these items. For each item a criterion for optimality was formulated based on evidence-based or consensus-based effectiveness of care in pregnancy and childbirth. All selected items were scored on potential problems, with reliability by 20 randomly selected community midwives. The level of agreement was calculated comparing these 2 data sets, which included data of the same women. RESULTS The final OI-NL2015 consists of 31 items in 3 different components: 22 intrapartum, 7 neonatal, and 2 postpartum. Of the 7 items that were examined because of expected potential problems with reliability, in 6 items a level of 90% agreement was found. DISCUSSION An optimality index is not a standard measurement instrument but must be validated and adapted to local circumstances and available data.
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