scholarly journals An N-body approach to modeling debris and ejecta off small bodies: Implementation and application

2021 ◽  
Author(s):  
Jennifer N Larson ◽  
G Sarid
Keyword(s):  
Spatial Scales ◽  
Solar Radiation Pressure ◽  
Particle Interactions ◽  
Comprehensive Understanding ◽  
Variable Size ◽  
Low Gravity ◽  
Small Bodies ◽  
New Approach ◽  
Small Asteroid ◽  
Cloud Evolution

Abstract We introduce here our new approach to modeling particle cloud evolution off surface of small bodies (asteroids and comets), following the evolution of ejected particles requires dealing with various time and spatial scales, in an efficient, accurate and modular way. In order to improve computational efficiency and accuracy of such calculations, we created an N-body modeling package as an extension to the increasingly popular orbital dynamics N-body integrator Rebound. Our code is currently a stand-alone variant of the Rebound code and is aimed at advancing a comprehensive understanding of individual particle trajectories, external forcing, and interactions, at the scale which is otherwise overlooked by other modeling approaches. The package we developed – Rebound Ejecta Dynamics (RED) – is a Python-based implementation with no additional dependencies. It incorporates several major mechanisms that affect the evolution of particles in low-gravity environments and enables a more straightforward simulation of combined effects. We include variable size and velocity distributions, solar radiation pressure, ellipsoidal gravitational potential, binary or triple asteroid systems, and particle-particle interactions. In this paper, we present a sample of the RED package capabilities. These are applied to a small asteroid binary system (characterized following the Didymos/Dimorphos system, which is the target for NASA’s Double Asteroid Redirection Test mission).

Coercive Persuasion As a Specific Type of Violence in Criminal Law

2020 ◽  
Vol 1 (1) ◽  
pp. 61-72
Author(s):  
Carlos Bardavío Antón
Keyword(s):  
Criminal Law ◽  
Comparative Law ◽  
Third Parties ◽  
Physical Injury ◽  
Comprehensive Understanding ◽  
Legal Doctrine ◽  
New Approach ◽  
Freedom Of Will ◽  
Definition Of ◽  
Regulatory Problems

The field of cults, and that of destructive or coercive cults in particular, has received little attention from the perspective of criminal law doctrine. Supporters of such groups often claim to be victims of a violation related to freedom of will. In this article, I consider various methodologies and manipulation techniques used by such groups and suggest that comparative law, criminal definitions, and regulatory problems provide the basis for a more comprehensive understanding of criminal phenomenology that includes these concerns: the loss of freedom through coercive persuasion, and thus being the victim of a crime, or through becoming an instrument for the commission of crimes ordered by third parties. Research shows that the conventional definition of crime against freedom of will and physical injury is inadequate. I posit that a new approach to legal doctrine and criminal classification is required to fight against new crime phenomenology. I propose a criminal classification aimed at considering coercive persuasion as a crime, and a definition for the criminalization of certain organizations that engage in willful misconduct or reckless conduct.

scholarly journals Simulating natural carbon sequestration in the Southern Ocean: on uncertainties associated with eddy parameterizations and iron deposition

2017 ◽  
Vol 14 (6) ◽  
pp. 1561-1576 ◽  
Author(s):  
Heiner Dietze ◽  
Julia Getzlaff ◽  
Ulrike Löptien
Keyword(s):  
Carbon Sequestration ◽  
Southern Ocean ◽  
Ocean Circulation ◽  
Spatial Scales ◽  
Carbon Uptake ◽  
Comprehensive Understanding ◽  
Biogeochemical Models ◽  
Anthropogenic Carbon ◽  
Natural Carbon ◽  
Oceanic Carbon

Abstract. The Southern Ocean is a major sink for anthropogenic carbon. Yet, there is no quantitative consensus about how this sink will change when surface winds increase (as they are anticipated to do). Among the tools employed to quantify carbon uptake are global coupled ocean-circulation–biogeochemical models. Because of computational limitations these models still fail to resolve potentially important spatial scales. Instead, processes on these scales are parameterized. There is concern that deficiencies in these so-called eddy parameterizations might imprint incorrect sensitivities of projected oceanic carbon uptake. Here, we compare natural carbon uptake in the Southern Ocean simulated with contemporary eddy parameterizations. We find that very differing parameterizations yield surprisingly similar oceanic carbon in response to strengthening winds. In contrast, we find (in an additional simulation) that the carbon uptake does differ substantially when the supply of bioavailable iron is altered within its envelope of uncertainty. We conclude that a more comprehensive understanding of bioavailable iron dynamics will substantially reduce the uncertainty of model-based projections of oceanic carbon uptake.

scholarly journals A new uncertainty estimation approach with multiple datasets and implementation for various precipitation products

2020 ◽  
Vol 24 (4) ◽  
pp. 2061-2081 ◽  
Author(s):  
Xudong Zhou ◽  
Jan Polcher ◽  
Tao Yang ◽  
Ching-Sheng Huang
Keyword(s):  
Spatial Heterogeneity ◽  
Spatial Scales ◽  
Three Dimensional ◽  
Variance Partitioning ◽  
Uncertainty Estimation ◽  
The Other ◽  
New Approach ◽  
Multiple Datasets ◽  
Uncertainty Estimates ◽  
Spatiotemporal Scales

Abstract. Ensemble estimates based on multiple datasets are frequently applied once many datasets are available for the same climatic variable. An uncertainty estimate based on the difference between the ensemble datasets is always provided along with the ensemble mean estimate to show to what extent the ensemble members are consistent with each other. However, one fundamental flaw of classic uncertainty estimates is that only the uncertainty in one dimension (either the temporal variability or the spatial heterogeneity) can be considered, whereas the variation along the other dimension is dismissed due to limitations in algorithms for classic uncertainty estimates, resulting in an incomplete assessment of the uncertainties. This study introduces a three-dimensional variance partitioning approach and proposes a new uncertainty estimation (Ue) that includes the data uncertainties in both spatiotemporal scales. The new approach avoids pre-averaging in either of the spatiotemporal dimensions and, as a result, the Ue estimate is around 20 % higher than the classic uncertainty metrics. The deviation of Ue from the classic metrics is apparent for regions with strong spatial heterogeneity and where the variations significantly differ in temporal and spatial scales. This shows that classic metrics underestimate the uncertainty through averaging, which means a loss of information in the variations across spatiotemporal scales. Decomposing the formula for Ue shows that Ue has integrated four different variations across the ensemble dataset members, while only two of the components are represented in the classic uncertainty estimates. This analysis of the decomposition explains the correlation as well as the differences between the newly proposed Ue and the two classic uncertainty metrics. The new approach is implemented and analysed with multiple precipitation products of different types (e.g. gauge-based products, merged products and GCMs) which contain different sources of uncertainties with different magnitudes. Ue of the gauge-based precipitation products is the smallest, while Ue of the other products is generally larger because other uncertainty sources are included and the constraints of the observations are not as strong as in gauge-based products. This new three-dimensional approach is flexible in its structure and particularly suitable for a comprehensive assessment of multiple datasets over large regions within any given period.

scholarly journals Multidimensional Iterative Filtering: a new approach for investigating plasma turbulence in numerical simulations

2020 ◽  
Vol 86 (5) ◽  
Author(s):  
Emanuele Papini ◽  
Antonio Cicone ◽  
Mirko Piersanti ◽  
Luca Franci ◽  
Petr Hellinger ◽  
...  
Keyword(s):  
Numerical Simulations ◽  
Complex Dynamics ◽  
Spatial Scales ◽  
Plasma Turbulence ◽  
Astrophysical Plasmas ◽  
Plasma Dynamics ◽  
New Approach ◽  
Particle In Cell ◽  
Multidimensional Signals ◽  
Iterative Filtering

Turbulent space and astrophysical plasmas exhibit a complex dynamics, which involves nonlinear coupling across different temporal and spatial scales. There is growing evidence that impulsive events, such as magnetic reconnection instabilities, lead to a spatially localized enhancement of energy dissipation, thus speeding up the energy transfer at small scales. Capturing such a diverse dynamics is challenging. Here, we employ the Multidimensional Iterative Filtering (MIF) method, a novel technique for the analysis of non-stationary multidimensional signals. Unlike other traditional methods (e.g. based on Fourier or wavelet decomposition), MIF does not require any previous assumption on the functional form of the signal to be identified. Using MIF, we carry out a multiscale analysis of Hall-magnetohydrodynamic (HMHD) and hybrid particle-in-cell (HPIC) numerical simulations of decaying plasma turbulence. The results assess the ability of MIF to spatially identify and separate the different scales (the MHD inertial range, the sub-ion kinetic and the dissipation scales) of the plasma dynamics. Furthermore, MIF decomposition allows localized current structures to be detected and their contribution to the statistical and spectral properties of turbulence to be characterized. Overall, MIF arises as a very promising technique for the study of turbulent plasma environments.

The latent roots of certain Markov chains arising in genetics: A new approach, II. Further haploid models

1975 ◽  
Vol 7 (02) ◽  
pp. 264-282 ◽  
Author(s):  
C. Cannings
Keyword(s):  
Markov Chain ◽  
Markov Chains ◽  
Reproductive Structure ◽  
Variable Size ◽  
New Approach ◽  
Age Structured ◽  
Drift Models ◽  
Latent Roots

The method developed for the treatment of the classical drift models of Wright and Moran, and their generalizations, in Cannings (1974) are extended to more complex haploid models. The possibility of subdivision of the population, as for migration models and age-structured models, is incorporated. Models with variable size or reproductive structure determined by another Markov chain are analysed.

scholarly journals Transient and localized processes in the magnetotail: a review

2008 ◽  
Vol 26 (4) ◽  
pp. 955-1006 ◽  
Author(s):  
A. S. Sharma ◽  
R. Nakamura ◽  
A. Runov ◽  
E. E. Grigorenko ◽  
H. Hasegawa ◽  
...  
Keyword(s):  
Magnetic Reconnection ◽  
Current Sheet ◽  
Spatial Scales ◽  
Theoretical Models ◽  
Particle Interactions ◽  
Transient Field ◽  
Theoretical Frameworks ◽  
Flux Ropes ◽  
Night Side ◽  
Bursty Bulk Flows

Abstract. Many phenomena in the Earth's magnetotail have characteristic temporal scales of several minutes and spatial scales of a few Earth radii (RE). Examples of such transient and localized mesoscale phenomena are bursty bulk flows, beamlets, energy dispersed ion beams, flux ropes, traveling compression regions, night-side flux transfer events, and rapid flappings of the current sheet. Although most of these observations are linked to specific interpretations or theoretical models they are inter-related and can be the different aspects of a physical process or origin. Recognizing the inter-connected nature of the different transient and localized phenomena in the magnetotail, this paper reviews their observations by highlighting their important characteristics, with emphasis on the new results from Cluster multipoint observations. The multi-point Cluster measurements have provided, for the first time, the ability to distinguish between temporal and spatial variations, and to resolve spatial structures. Some examples of the new results are: flux ropes with widths of 0.3 RE, transient field aligned currents associated with bursty bulk flows and connected to the Hall current at the magnetic reconnection, flappings of the magnetotail current sheet with time scales of 100 s–10 min and thickness of few thousand km, and particle energization including velocity and time dispersed ion structures with the latter having durations of 1–3 min. The current theories of these transient and localized processes are based largely on magnetic reconnection, although the important role of the interchange and other plasma modes are now well recognized. On the kinetic scale, the energization of particles takes place near the magnetic X-point by non-adiabatic processes and wave-particle interactions. The theory, modeling and simulations of the plasma and field signatures are reviewed and the links among the different observational concepts and the theoretical frameworks are discussed. The mesoscale processes in the magnetotail and the strong coupling among them are crucial in developing a comprehensive understanding of the multiscale phenomena of the magnetosphere.

scholarly journals Simulating natural carbon sequestration in the Southern Ocean: on uncertainties associated with eddy parameterizations and iron deposition

2016 ◽  
Author(s):  
Heiner Dietze ◽  
Julia Getzlaff ◽  
Ulrike Löptien
Keyword(s):  
Carbon Sequestration ◽  
Southern Ocean ◽  
Ocean Circulation ◽  
Spatial Scales ◽  
Carbon Uptake ◽  
Comprehensive Understanding ◽  
Biogeochemical Models ◽  
Anthropogenic Carbon ◽  
Natural Carbon ◽  
Oceanic Carbon

Abstract. The Southern Ocean is a major sink for anthropogenic carbon. Yet, there is no quantitative consensus about how this sink will change when surface winds increase (as they are anticipated to do). Among the tools employed to quantify carbon uptake are global coupled ocean-circulation biogeochemical models. Because of computational limitations these models still fail to resolve potentially-important spatial scales. Instead, processes on these scales are parameterized. There is concern that deficiencies in these so-called eddy-parameterizations might imprint wrong sensitivities of projected oceanic carbon uptake. Here, we compare natural carbon uptake in the Southern Ocean simulated with contemporary eddy-parameterizations. We find that very differing parameterizations yield surprisingly similar oceanic carbon in response to strengthening winds. In contrast, we find (in an additional simulation) that the carbon uptake does differ substantially when the supply of bioavailable iron is altered within its envelope of uncertainty. We conclude that a more comprehensive understanding of bioavailable iron dynamics will substantially reduce the uncertainty of model-based projections of oceanic carbon uptake.

scholarly journals Quantitative and temporal measurement of dynamic autophagy rates

2021 ◽  
Author(s):  
Nitin Sai Beesabathuni ◽  
Priya S. Shah
Keyword(s):  
Steady State ◽  
Temporal Resolution ◽  
Recovery Time ◽  
Cellular Response ◽  
High Sensitivity ◽  
Limited Information ◽  
Comprehensive Understanding ◽  
Autophagy Flux ◽  
New Approach ◽  
Temporal Measurement

AbstractAutophagy is a multistep degradative process that is essential for maintaining cellular homeostasis. Systematically quantifying flux through this pathway is critical for gaining fundamental insights and effectively modulating this process that is dysregulated during many diseases. Established methods to quantify flux use steady state measurements, which provide limited information about the perturbation and the cellular response. We present a theoretical and experimental framework to measure autophagic steps in the form of rates under non-steady state conditions. We use this approach to measure temporal responses to rapamycin and wortmannin treatments, two commonly used autophagy modulators. We quantified changes in autophagy rates in as little as 10 minutes, which can establish direct mechanisms for autophagy perturbation before feedback begins. We identified concentration-dependent effects of rapamycin on the initial and temporal progression of autophagy rates. We also found variable recovery time from wortmannin’s inhibition of autophagy, which is further accelerated by rapamycin. In summary, this new approach enables the quantification of autophagy flux with high sensitivity and temporal resolution and facilitates a comprehensive understanding of this process.

scholarly journals Predictor species: Improving assessments of rare species occurrence by modelling environmental co-responses

2019 ◽  
Author(s):  
Peter R. Thompson ◽  
William F. Fagan ◽  
Phillip P.A. Staniczenko
Keyword(s):  
Rare Species ◽  
Spatial Scales ◽  
Single Species ◽  
Conservation Strategy ◽  
Individual Species ◽  
Calibration Data ◽  
Distribution Models ◽  
New Approach ◽  
Effective Conservation ◽  
Better Than

ABSTRACTDesigning an effective conservation strategy requires understanding where rare species are located. Although species distribution models are primarily used to identify patterns at large spatial scales, their general methodology is relevant for predicting the occurrence of individual species at specific locations. Here we present a new approach that uses Bayesian networks to improve predictions by modelling environmental co-responses among species. For species from a European peat bog community, our approach consistently performs better than single-species models, and better than conventional multi-species models for rare species when calibration data are limited. Furthermore, we identify a group of “predictor species” that are relatively common, insensitive to the presence of other species, and can be used to improve occurrence predictions of rare species. Predictor species are distinct from other categories of conservation surrogates such as umbrella or indicator species, which motivates focused data collection of predictor species to enhance conservation practices.

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