scholarly journals Revisiting high-order Taylor methods for astrodynamics and celestial mechanics

2021 ◽  
Author(s):  
Francesco Biscani ◽  
Dario Izzo
Keyword(s):  
Celestial Mechanics ◽  
General Purpose ◽  
Symplectic Integrators ◽  
Conservation Of Energy ◽  
Domain Specific ◽  
Numerical Tests ◽  
The Earth ◽  
Taylor Methods ◽  
Speed And Accuracy

Abstract We present heyoka, a new, modern and general-purpose implementation of Taylor’s integration method for the numerical solution of ordinary differential equations. Detailed numerical tests focused on difficult high-precision gravitational problems in astrodynamics and celestial mechanics show how our general-purpose integrator is competitive with and often superior to state-of-the-art specialised symplectic and non-symplectic integrators in both speed and accuracy. In particular, we show how Taylor methods are capable of satisfying Brouwer’s law for the conservation of energy in long-term integrations of planetary systems over billions of dynamical timescales. We also show how close encounters are modelled accurately during simulations of the formation of the Kirkwood gaps and of Apophis’ 2029 close encounter with the Earth (where heyoka surpasses the speed and accuracy of domain-specific methods). heyoka can be used from both C++ and Python, and it is publicly available as an open-source project.

Symplectic integrators for long-term integrations in celestial mechanics

1991 ◽  
Vol 52 (3) ◽  
pp. 221-240 ◽  
Author(s):  
Brett Gladman ◽  
Martin Duncan ◽  
Jeff Candy
Keyword(s):  
Celestial Mechanics ◽  
Symplectic Integrators

Comparison of Auditory, Language, Memory, and Attention Abilities in Children With and Without Listening Difficulties

2020 ◽  
Vol 29 (4) ◽  
pp. 710-727
Author(s):  
Beula M. Magimairaj ◽  
Naveen K. Nagaraj ◽  
Alexander V. Sergeev ◽  
Natalie J. Benafield
Keyword(s):  
Auditory Processing ◽  
Short Term Memory ◽  
Group Differences ◽  
Long Term Memory ◽  
Short Term ◽  
Significant Group ◽  
Term Memory ◽  
Memory And Attention ◽  
Speed And Accuracy

Objectives School-age children with and without parent-reported listening difficulties (LiD) were compared on auditory processing, language, memory, and attention abilities. The objective was to extend what is known so far in the literature about children with LiD by using multiple measures and selective novel measures across the above areas. Design Twenty-six children who were reported by their parents as having LiD and 26 age-matched typically developing children completed clinical tests of auditory processing and multiple measures of language, attention, and memory. All children had normal-range pure-tone hearing thresholds bilaterally. Group differences were examined. Results In addition to significantly poorer speech-perception-in-noise scores, children with LiD had reduced speed and accuracy of word retrieval from long-term memory, poorer short-term memory, sentence recall, and inferencing ability. Statistically significant group differences were of moderate effect size; however, standard test scores of children with LiD were not clinically poor. No statistically significant group differences were observed in attention, working memory capacity, vocabulary, and nonverbal IQ. Conclusions Mild signal-to-noise ratio loss, as reflected by the group mean of children with LiD, supported the children's functional listening problems. In addition, children's relative weakness in select areas of language performance, short-term memory, and long-term memory lexical retrieval speed and accuracy added to previous research on evidence-based areas that need to be evaluated in children with LiD who almost always have heterogenous profiles. Importantly, the functional difficulties faced by children with LiD in relation to their test results indicated, to some extent, that commonly used assessments may not be adequately capturing the children's listening challenges. Supplemental Material https://doi.org/10.23641/asha.12808607

scholarly journals Long Term Memory Outcome of Repetitive, Low-Level Dietary Exposure to Domoic Acid in Native Americans

2021 ◽  
Vol 18 (8) ◽  
pp. 3955
Author(s):  
Lynn M. Grattan ◽  
Laura Kaddis ◽  
J. Kate Tracy ◽  
John Glenn Morris
Keyword(s):  
Native Americans ◽  
Domoic Acid ◽  
Dietary Exposure ◽  
Long Term Memory ◽  
Shellfish Poisoning ◽  
Amnesic Shellfish Poisoning ◽  
The Pacific ◽  
Small Decline ◽  
Speed And Accuracy

Domoic acid (DA) is a marine-based neurotoxin that, if ingested via tainted shellfish, is associated with Amnesic Shellfish Poisoning (ASP). These acute effects of elevated DA exposure in humans have been well described. In contrast, the long-term impacts of lower level, repetitive, presumably safe doses of DA (less than 20 ppm) are minimally known. Since Native Americans (NA) residing in coastal communities of the Pacific NW United States are particularly vulnerable to DA exposure, this study focuses on the long-term, 8-year memory outcome associated with their repeated dietary consumption of the neurotoxin. Measures of razor clam consumption, memory, clerical speed and accuracy, and depression were administered over eight years to 500 randomly selected adult NA men and women ages 18–64. Data were analyzed using GEE analyses taking into consideration the year of study, demographic factors, and instrumentation in examining the association between dietary exposure and outcomes. Findings indicated a significant but small decline in total recall memory within the context of otherwise stable clerical speed and accuracy and depression scores. There is reason to believe that a continuum of memory difficulties may be associated with DA exposure, rather than a unitary ASP syndrome.

Cities Created by Modernity: A Fengshui Perspective

2015 ◽  
Vol 42 (5) ◽  
pp. 477-499
Author(s):  
Michael John Paton
Keyword(s):  
Hong Kong ◽  
Traditional Knowledge ◽  
East Coast ◽  
Chinese Art ◽  
Empirical Knowledge ◽  
Term Survival ◽  
Long Term Survival ◽  
The Earth ◽  
Human Habitation

The 2011 tsunami had a devastating effect on the east coast of Japan. Particularly poignant were the century-old markers on hillsides warning against building anywhere below. Nevertheless, such wisdom from traditional knowledge was disregarded because of the perceived invulnerability of the modern. This paper attempts to garner such traditional empirical knowledge regarding the siting of towns and cities by considering the Chinese art/science of fengshui (wind and water) or dili (principles of the earth), the original purpose of which was to site human habitation in the most favourable places for long term survival. This knowledge is then used to consider the placement of cities created by modernity, those founded on and flourishing through the advent of globalisation, such as Hong Kong, Shanghai, St Petersburg, and Sydney.

Late Accretion and the Origin of Water on Terrestrial Planets in the Solar System

2021 ◽  
Author(s):  
Cédric Gillmann ◽  
Gregor Golabek ◽  
Sean Raymond ◽  
Paul Tackley ◽  
Maria Schonbachler ◽  
...  
Keyword(s):  
Solar System ◽  
Long Term Evolution ◽  
Terrestrial Planets ◽  
Evolutionary Pathway ◽  
Giant Impact ◽  
The Earth ◽  
Term Evolution ◽  
Surface Liquid ◽  
Venus Atmosphere

<p>Terrestrial planets in the Solar system generally lack surface liquid water. Earth is at odd with this observation and with the idea of the giant Moon-forming impact that should have vaporized any pre-existing water, leaving behind a dry Earth. Given the evidence available, this means that either water was brought back later or the giant impact could not vaporize all the water.</p><p>We have looked at Venus for answers. Indeed, it is an example of an active planet that may have followed a radically different evolutionary pathway despite the similar mechanisms at work and probably comparable initial conditions. However, due to the lack of present-day plate tectonics, volatile recycling, and any surface liquid oceans, the evolution of Venus has likely been more straightforward than that of the Earth, making it easier to understand and model over its long term evolution.</p><p>Here, we investigate the long-term evolution of Venus using self-consistent numerical models of global thermochemical mantle convection coupled with both an atmospheric evolution model and a late accretion N-body delivery model. We test implications of wet and dry late accretion compositions, using present-day Venus atmosphere measurements. Atmospheric losses are only able to remove a limited amount of water over the history of the planet. We show that late accretion of wet material exceeds this sink. CO<sub>2</sub> and N<sub>2</sub> contributions serve as additional constraints.</p><p>Water-rich asteroids colliding with Venus and releasing their water as vapor cannot explain the composition of Venus atmosphere as we measure it today. It means that the asteroidal material that came to Venus, and thus to Earth, after the giant impact must have been dry (enstatite chondrites), therefore preventing the replenishment of the Earth in water. Because water can obviously be found on our planet today, it means that the water we are now enjoying on Earth has been there since its formation, likely buried deep in the Earth so it could survive the giant impact. This in turn suggests that suggests that planets likely formed with their near-full budget in water, and slowly lost it with time.</p>

scholarly journals Geosystemics and Earthquakes

2018 ◽  
Author(s):  
Angelo De Santis ◽  
Gianfranco Cianchini ◽  
Rita Di Giovambattista ◽  
Cristoforo Abbattista ◽  
Lucilla Alfonsi ◽  
...  
Keyword(s):  
Dynamical System ◽  
Solid Earth ◽  
Case Studies ◽  
Central Italy ◽  
Point Of View ◽  
Earth System ◽  
Complex Dynamical System ◽  
The Earth ◽  
Earth’S Interior

Abstract. Geosystemics (De Santis 2009, 2014) studies the Earth system as a whole focusing on the possible coupling among the Earth layers (the so called geo-layers), and using universal tools to integrate different methods that can be applied to multi-parameter data, often taken on different platforms. Its main objective is to understand the particular phenomenon of interest from a holistic point of view. In this paper we will deal with earthquakes, considered as a long term chain of processes involving, not only the interaction between different components of the Earth’s interior, but also the coupling of the solid earth with the above neutral and ionized atmosphere, and finally culminating with the main rupture along the fault of concern (De Santis et al., 2015a). Some case studies (particular emphasis is given to recent central Italy earthquakes) will be discussed in the frame of the geosystemic approach for better understanding the physics of the underlying complex dynamical system.

Fast and high-precision calculation of earth return mutual impedance between conductors over a multilayered soil

2018 ◽  
Vol 37 (3) ◽  
pp. 1214-1227 ◽  
Author(s):  
Junjie Ma
Keyword(s):  
Quadrature Rule ◽  
Content Type ◽  
Mutual Impedance ◽  
Numerical Tests ◽  
Sommerfeld Integral ◽  
The Earth ◽  
Finite Integral ◽  
Infinite Integral ◽  
Improper Integrals ◽  
Differential Matrix

Purpose Solutions for the earth return mutual impedance play an important role in analyzing couplings of multi-conductor systems. Generally, the mutual impedance is approximated by Pollaczek integrals. The purpose of this paper is devising fast algorithms for calculation of this kind of improper integrals and its applications. Design/methodology/approach According to singular points, the Pollaczek integral is divided into two parts: the finite integral and the infinite integral. The finite part is computed by combining an efficient Levin method, which is implemented with a Chebyshev differential matrix. By transforming the integration path, the tail integral is calculated with help of a transformed Clenshaw–Curtis quadrature rule. Findings Numerical tests show that this new method is robust to high oscillation and nearly singularities. Thus, it is suitable for evaluating Pollaczek integrals. Furthermore, compared with existing method, the presented algorithm gives high-order approaches for the earth return mutual impedance between conductors over a multilayered soil with wide ranges of parameters. Originality/value An efficient truncation strategy is proposed to accelerate numerical calculation of Pollaczek integral. Compared with existing algorithms, this method is easier to be applied to computation of similar improper integrals, such as Sommerfeld integral.

scholarly journals Resisting Everything except Temptation: Evidence and an Explanation for Domain–specific Impulsivity

2012 ◽  
Vol 26 (3) ◽  
pp. 318-334 ◽  
Author(s):  
Eli Tsukayama ◽  
Angela Lee Duckworth ◽  
Betty Kim
Keyword(s):  
Interpersonal Relationships ◽  
Control Strategies ◽  
Self Control ◽  
Self Report ◽  
Special Interest Groups ◽  
Target Domain ◽  
Domain Specific ◽  
Impulsive Behaviour ◽  
Report Measure

We propose a model of impulsivity that predicts both domain–general and domain–specific variance in behaviours that produce short–term gratification at the expense of long–term goals and standards. Specifically, we posit that domain–general impulsivity is explained by domain–general self–control strategies and resources, whereas domain–specific impulsivity is explained by how tempting individuals find various impulsive behaviours, and to a lesser extent, in perceptions of their long–term harm. Using a novel self–report measure, factor analyses produced six (non–exhaustive) domains of impulsive behaviour (Studies 1–2): work, interpersonal relationships, drugs, food, exercise and finances. Domain–general self–control explained 40% of the variance in domain–general impulsive behaviour between individuals, reffect = .71. Domain–specific temptation ( reffect = .83) and perceived harm ( reffect = −.26) explained 40% and 2% of the unique within–individual variance in impulsive behaviour, respectively (59% together). In Study 3, we recruited individuals in special interest groups (e.g. procrastinators) to confirm that individuals who are especially tempted by behaviours in their target domain are not likely to be more tempted in non–target domains. Copyright © 2011 John Wiley & Sons, Ltd.

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