Journal articles: 'N-body integration'

1

Dehnen, Walter. "Towards time symmetric N-body integration." Monthly Notices of the Royal Astronomical Society 472, no. 1 (August 2, 2017): 1226–38. http://dx.doi.org/10.1093/mnras/stx1944.

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AARSETH, S. "NBODY2: A direct N-body integration code." New Astronomy 6, no. 5 (August 2001): 277–91. http://dx.doi.org/10.1016/s1384-1076(01)00060-4.

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Aarseth, Sverre J. "Direct N-Body Calculations." Symposium - International Astronomical Union 113 (1985): 251–59. http://dx.doi.org/10.1017/s0074180900147424.

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The main principles for direct integration of large point-mass systems are outlined. Most particles are advanced by the Ahmad-Cohen neighbour scheme, using fourth-order force polynomials and individual time-steps. Close encounters and persistent binaries are handled by two-body regularization, whereas extreme triple and quadruple configurations are treated as unperturbed systems by special regularization techniques. As an illustration of these methods, we discuss some recent results of an isolated system containing 1000 particles of unequal mass, with special emphasis on the post-collapse phase.

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Hardy, David J., Daniel I. Okunbor, and Robert D. Skeel. "Symplectic variable step size integration for N-body problems." Applied Numerical Mathematics 29, no. 1 (January 1999): 19–30. http://dx.doi.org/10.1016/s0168-9274(98)00031-2.

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Mikkola, Seppo, and Sverre J. Aarseth. "An efficient integration method for binaries in N-body simulations." New Astronomy 3, no. 5 (July 1998): 309–20. http://dx.doi.org/10.1016/s1384-1076(98)00018-9.

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Daverio, David, Yves Dirian, and Ermis Mitsou. "General relativistic cosmological N-body simulations. Part I. Time integration." Journal of Cosmology and Astroparticle Physics 2019, no. 10 (October 28, 2019): 065. http://dx.doi.org/10.1088/1475-7516/2019/10/065.

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Kearns, Melissa J., William H. Warren, Andrew P. Duchon, and Michael J. Tarr. "Path Integration from Optic Flow and Body Senses in a Homing Task." Perception 31, no. 3 (March 2002): 349–74. http://dx.doi.org/10.1068/p3311.

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We examined the roles of information from optic flow and body senses (eg vestibular and proprioceptive information) for path integration, using a triangle completion task in a virtual environment. In two experiments, the contribution of optic flow was isolated by using a joystick control. Five circular arenas were used for testing: (B) both floor and wall texture; (F) floor texture only, reducing information for rotation; (W) wall texture only, reducing information for translation; (N) a no texture control condition; and (P) an array of posts. The results indicate that humans can use optic flow for path integration and are differentially influenced by rotational and translational flow. In a third experiment, participants actively walked in arenas B, F, and N, so body senses were also available. Performance shifted from a pattern of underturning to overturning and exhibited decreased variability, similar responses with and without optic flow, and no attrition. The results indicate that path integration can be performed by integrating optic flow, but when information from body senses is available it appears to dominate.

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Miller, R. H. "Dimensionality of Stable and Unstable Directions in the Gravitational N—Body Problem." International Astronomical Union Colloquium 172 (1999): 139–47. http://dx.doi.org/10.1017/s0252921100072493.

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AbstractThe gravitational n—body problem is chaotic. Phase trajectories that start very near each other separate rapidly. The rate looks exponential over long times. At any instant, trajectories separated in certain directions move apart rapidly (unstable directions), while those separated in other directions stay about the same (stable directions). Unstable directions lie along eigenvectors that correspond to positive eigenvalues of the matrix of force gradients. The number of positive eigenvalues of that matrix gives the dimensionality of stable regions. This number has been studied numerically in a series of 100—body integrations. It continues to change as long as the integration continues because the matrix changes extremely rapidly. On average, there are about 1.2n unstable directions out of 3n. Issues of dimensionality arise when the tools of ergodic studies are brought to bear on the problem of trajectory separation. A method of estimating the rate of trajectory separation based on matrix descriptions is presented in this note. Severe approximations are required.

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Pal, A., and A. Suli. "Solving linearized equations of the N-body problem using the Lie-integration method." Monthly Notices of the Royal Astronomical Society 381, no. 4 (November 11, 2007): 1515–26. http://dx.doi.org/10.1111/j.1365-2966.2007.12248.x.

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Vlachos, D. S., and T. E. Simos. "Partitioned Linear Multistep Method for Long Term Integration of the N-Body Problem." Applied Numerical Analysis & Computational Mathematics 1, no. 2 (December 2004): 540–46. http://dx.doi.org/10.1002/anac.200410017.

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Chambers, J. E. "A Symplectic Integration Scheme that allows Close Encounters between Massive Bodies." International Astronomical Union Colloquium 172 (1999): 449–50. http://dx.doi.org/10.1017/s0252921100073115.

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Mixed-variable symplectic integrators provide a fast, moderately accurate way to study the long-term evolution of a wide variety of N-body systems (Wisdom & Holman 1991). They are especially suited to planetary and satellite systems, in which a central body contains most of the mass. However, in their original form, they become inaccurate whenever two bodies approach one another closely. Here, I will show how to overcome this difficulty using a hybrid integrator that combines symplectic and conventional algorithms.A symplectic integrator works by splitting the Hamiltonian, H, for an N-body system, into two or more parts H = H0 + H1 + …, where є i = Hi/H0 ≪ 1 for i = 1, 2 …. An integration step consists of several substeps, each of which advances the system due to the effect of one part of the Hamiltonian only. The error incurred over the whole step is ∼ є τn1, where τ is the timestep, n is the order of the integrator, and є is the largest of єi.

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Giersz, M., and R. Spurzem. "A comparison of direct N-body integration with anisotropic gaseous models of star clusters." Monthly Notices of the Royal Astronomical Society 269, no. 2 (July 15, 1994): 241–56. http://dx.doi.org/10.1093/mnras/269.2.241.

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Graham, E., G. Jelenić, and M. A. Crisfield. "A note on the equivalence of two recent time-integration schemes for N-body problems." Communications in Numerical Methods in Engineering 18, no. 9 (June 7, 2002): 615–20. http://dx.doi.org/10.1002/cnm.520.

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Brodbeck, Felix C., Katharina G. Kugler, Josef A. Fischer, Joerg Heinze, and Dorothee Fischer. "Group-level integrative complexity: Enhancing differentiation and integration in group decision-making." Group Processes & Intergroup Relations 24, no. 1 (January 29, 2020): 125–44. http://dx.doi.org/10.1177/1368430219892698.

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Decision-making in organizations is often complex and involves groups, which have access to the pool of perspectives and knowledge their members hold individually. However, groups frequently fail to use their full decision-making potential. The concept of integrative complexity (IC) captures how complex decision-making profits from the differentiation and integration of diverse perspectives and knowledge. In a laboratory experiment with 4 conditions ( N = 12 groups of 4 students per condition), we found that group dissent enhanced differentiation and a stepwise recapitulation of the group discussion enhanced integration, thereby raising group-level IC. Dissent groups who performed a stepwise recapitulation reached the highest levels of group IC compared to ordinary dissent groups, consent groups, and individuals working alone. They also exceeded their own best member and achieved an equal level of IC to that of the best members of nominal groups. The study contributes to the body of research identifying factors that support groups in exploiting their potential and reaching more informed decisions and judgments.

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Rantala, Antti, Pauli Pihajoki, Matias Mannerkoski, Peter H. Johansson, and Thorsten Naab. "mstar – a fast parallelized algorithmically regularized integrator with minimum spanning tree coordinates." Monthly Notices of the Royal Astronomical Society 492, no. 3 (January 15, 2020): 4131–48. http://dx.doi.org/10.1093/mnras/staa084.

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ABSTRACT We present the novel algorithmically regularized integration method mstar for high-accuracy (|ΔE/E| ≳ 10−14) integrations of N-body systems using minimum spanning tree coordinates. The twofold parallelization of the $\mathcal {O}(N_\mathrm{part}^2)$ force loops and the substep divisions of the extrapolation method allow for a parallel scaling up to NCPU = 0.2 × Npart. The efficient parallel scaling of mstar makes the accurate integration of much larger particle numbers possible compared to the traditional algorithmic regularization chain (ar-chain) methods, e.g. Npart = 5000 particles on 400 CPUs for 1 Gyr in a few weeks of wall-clock time. We present applications of mstar on few particle systems, studying the Kozai mechanism and N-body systems like star clusters with up to Npart = 104 particles. Combined with a tree or fast multipole-based integrator, the high performance of mstar removes a major computational bottleneck in simulations with regularized subsystems. It will enable the next-generation galactic-scale simulations with up to 109 stellar particles (e.g. $m_\star = 100 \, \mathrm{M}_\odot$ for an $M_\star = 10^{11} \, \mathrm{M}_\odot$ galaxy), including accurate collisional dynamics in the vicinity of nuclear supermassive black holes.

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Tamayo, Daniel, Hanno Rein, Pengshuai Shi, and David M. Hernandez. "REBOUNDx: a library for adding conservative and dissipative forces to otherwise symplectic N-body integrations." Monthly Notices of the Royal Astronomical Society 491, no. 2 (October 18, 2019): 2885–901. http://dx.doi.org/10.1093/mnras/stz2870.

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ABSTRACT Symplectic methods, in particular the Wisdom–Holman map, have revolutionized our ability to model the long-term, conservative dynamics of planetary systems. However, many astrophysically important effects are dissipative. The consequences of incorporating such forces into otherwise symplectic schemes are not always clear. We show that moving to a general framework of non-commutative operators (dissipative or not) clarifies many of these questions, and that several important properties of symplectic schemes carry over to the general case. In particular, we show that explicit splitting schemes generically exploit symmetries in the applied external forces, which often strongly suppress integration errors. Furthermore, we demonstrate that so-called ‘symplectic correctors’ (which reduce energy errors by orders of magnitude at fixed computational cost) apply equally well to weakly dissipative systems and can thus be more generally thought of as ‘weak splitting correctors’. Finally, we show that previously advocated approaches of incorporating additional forces into symplectic methods work well for dissipative forces, but give qualitatively wrong answers for conservative but velocity-dependent forces like post-Newtonian corrections. We release REBOUNDx, an open-source C library for incorporating additional effects into REBOUNDN-body integrations, together with a convenient python wrapper. All effects are machine independent and we provide a binary format that interfaces with the SimulationArchive class in REBOUND to enable the sharing and reproducibility of results. Users can add effects from a list of pre-implemented astrophysical forces, or contribute new ones.

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Crucianelli, Laura, Yannis Paloyelis, Lucia Ricciardi, Paul M. Jenkinson, and Aikaterini Fotopoulou. "Embodied Precision: Intranasal Oxytocin Modulates Multisensory Integration." Journal of Cognitive Neuroscience 31, no. 4 (April 2019): 592–606. http://dx.doi.org/10.1162/jocn_a_01366.

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Multisensory integration processes are fundamental to our sense of self as embodied beings. Bodily illusions, such as the rubber hand illusion (RHI) and the size–weight illusion (SWI), allow us to investigate how the brain resolves conflicting multisensory evidence during perceptual inference in relation to different facets of body representation. In the RHI, synchronous tactile stimulation of a participant's hidden hand and a visible rubber hand creates illusory body ownership; in the SWI, the perceived size of the body can modulate the estimated weight of external objects. According to Bayesian models, such illusions arise as an attempt to explain the causes of multisensory perception and may reflect the attenuation of somatosensory precision, which is required to resolve perceptual hypotheses about conflicting multisensory input. Recent hypotheses propose that the precision of sensorimotor representations is determined by modulators of synaptic gain, like dopamine, acetylcholine, and oxytocin. However, these neuromodulatory hypotheses have not been tested in the context of embodied multisensory integration. The present, double-blind, placebo-controlled, crossover study ( n = 41 healthy volunteers) aimed to investigate the effect of intranasal oxytocin (IN-OT) on multisensory integration processes, tested by means of the RHI and the SWI. Results showed that IN-OT enhanced the subjective feeling of ownership in the RHI, only when synchronous tactile stimulation was involved. Furthermore, IN-OT increased an embodied version of the SWI (quantified as estimation error during a weight estimation task). These findings suggest that oxytocin might modulate processes of visuotactile multisensory integration by increasing the precision of top–down signals against bottom–up sensory input.

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Rantala, Antti, Thorsten Naab, and Volker Springel. "frost: a momentum-conserving CUDA implementation of a hierarchical fourth-order forward symplectic integrator." Monthly Notices of the Royal Astronomical Society 502, no. 4 (January 11, 2021): 5546–62. http://dx.doi.org/10.1093/mnras/stab057.

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ABSTRACT We present a novel hierarchical formulation of the fourth-order forward symplectic integrator and its numerical implementation in the GPU-accelerated direct-summation N-body code frost. The new integrator is especially suitable for simulations with a large dynamical range due to its hierarchical nature. The strictly positive integrator sub-steps in a fourth-order symplectic integrator are made possible by computing an additional gradient term in addition to the Newtonian accelerations. All force calculations and kick operations are synchronous so the integration algorithm is manifestly momentum-conserving. We also employ a time-step symmetrization procedure to approximately restore the time-reversibility with adaptive individual time-steps. We demonstrate in a series of binary, few-body and million-body simulations that frost conserves energy to a level of |ΔE/E| ∼ 10−10 while errors in linear and angular momentum are practically negligible. For typical star cluster simulations, we find that frost scales well up to $N_\mathrm{GPU}^\mathrm{max}\sim 4\times N/10^5$ GPUs, making direct-summation N-body simulations beyond N = 106 particles possible on systems with several hundred and more GPUs. Due to the nature of hierarchical integration, the inclusion of a Kepler solver or a regularized integrator with post-Newtonian corrections for close encounters and binaries in the code is straightforward.

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Hussain, Naireen, and Daniel Tamayo. "Fundamental limits from chaos on instability time predictions in compact planetary systems." Monthly Notices of the Royal Astronomical Society 491, no. 4 (December 17, 2019): 5258–67. http://dx.doi.org/10.1093/mnras/stz3402.

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ABSTRACT Instabilities in compact planetary systems are generically driven by chaotic dynamics. This implies that an instability time measured through direct N-body integration is not exact, but rather represents a single draw from a distribution of equally valid chaotic trajectories. In order to characterize the ‘errors’ on reported instability times from direct N-body integrations, we investigate the shape and parameters of the instability time distributions (ITDs) for ensembles of shadow trajectories that are initially perturbed from one another near machine precision. We find that in the limit where instability times are long compared to the Lyapunov (chaotic) time-scale, ITDs approach remarkably similar lognormal distributions with standard deviations ≈0.43 ± 0.16 dex, despite the instability times varying across our sample from 104 to 108 orbits. We find excellent agreement between these predictions, derived from ≈450 closely packed configurations of three planets, and a much wider validation set of $\approx 10\, 000$ integrations, as well as on $\approx 20\, 000$ previously published integrations of tightly packed five-planet systems, and a seven-planet resonant chain based on TRAPPIST-1, despite their instability time-scales extending beyond our analysed time-scale. We also test the boundary of applicability of our results on dynamically excited versions of our Solar system. These distributions define the fundamental limit imposed by chaos on the predictability of instability times in such planetary systems. It provides a quantitative estimate of the instrinsic error on an N-body instability time imprinted by chaos, approximately a factor of 3 in either direction.

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Casertano, Stefano. "A Statistical Treatment of Low-N Systems." Symposium - International Astronomical Union 113 (1985): 305–8. http://dx.doi.org/10.1017/s0074180900147485.

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The long-term evolution of N-body systems with high N (>104) cannot yet be studied by direct integration of the equations of motion. Instead, the study of systems with smaller N can give insight into the higher N limit in two ways. First, we can measure the dependence on N of all quantities of interest for a range of N-values, and extrapolate the results to higher N. Second, even a very high-N system will eventually undergo core collapse, at which point the central dynamics will be dominated by a subset of stars with small N (10–100).

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Ferrari, Guilherme Gonçalves. "A Family of Hierarchical Symplectic Maps for N-body Simulations with Post-Newtonian Corrections." International Journal of Modern Physics: Conference Series 45 (January 2017): 1760021. http://dx.doi.org/10.1142/s2010194517600217.

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Symplectic maps are well known for preserving the phase-space volume in Hamiltonian dynamics and are particularly suited for problems that require long integration times, such as the [Formula: see text]-body problem. However, when combined with a varying time-step scheme, they end up losing its symplecticity and become numerically inefficient. We address this problem by using a recursive Hamiltonian splitting based on the time-symmetric value of the individual time-steps required by the particles in the system. We present a family of 48 quasi-symplectic maps with different orders of convergence (2nd-, 4th- & 6th-order) and three time-stepping schemes: i) 16 using constant time-steps, ii) 16 using shared adaptive time-steps, and iii) 16 using hierarchical (individual) time-steps. All maps include post-Newtonian corrections up to order 3.5PN. We describe the method and present some details of the implementation.

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Bretagnon, P. "Construction of a planetary solution with the help of an n-body program and analytical complements." Symposium - International Astronomical Union 114 (1986): 69. http://dx.doi.org/10.1017/s0074180900148004.

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Up to now we have been dealing with the construction of entirely analytical planetary theories such as VS0P82 (Bretagnon, 1982) and T0P82 (Simon, 1983). These theories take into account the whole of the newtonian perturbations of nine point masses: the Sun, the Earth-Moon barycenter, the planets Mercury, Venus, Mars, Jupiter, Saturn, Uranus and Neptune. They also take into account perturbations due to some minor planets, to the action of the Moon and the relativistic effects. The perturbations of these last three types are in a very simple way under analytical form but they considerably increase the computations when introduced in the numerical integration programs.

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23

Yadav, Sachin, Kian Hua Tan, Annie Kumar, Kian Hui Goh, Gengchiau Liang, Soon-Fatt Yoon, Xiao Gong, and Yee-Chia Yeo. "Monolithic Integration of InAs Quantum-Well n-MOSFETs and Ultrathin Body Ge p-MOSFETs on a Si Substrate." IEEE Transactions on Electron Devices 64, no. 2 (February 2017): 353–60. http://dx.doi.org/10.1109/ted.2016.2637382.

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Asri, Mochamad, Dhairya Malhotra, Jiajun Wang, George Biros, Lizy K. John, and Andreas Gerstlauer. "Hardware Accelerator Integration Tradeoffs for High-Performance Computing: A Case Study of GEMM Acceleration in N-Body Methods." IEEE Transactions on Parallel and Distributed Systems 32, no. 8 (August 1, 2021): 2035–48. http://dx.doi.org/10.1109/tpds.2021.3056045.

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Alvarez-Ramírez, Martha, Joaquín Delgado, and Claudio Vidal. "Global Regularization of a Restricted Four-Body Problem." International Journal of Bifurcation and Chaos 24, no. 07 (July 2014): 1450092. http://dx.doi.org/10.1142/s0218127414500928.

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In the n-body problem, a collision singularity occurs when the position of two or more bodies coincide. By understanding the dynamics of collision motion in the regularized setting, a better understanding of the dynamics of near-collision motion is achieved. In this paper, we show that any double collision of the planar equilateral restricted four-body problem can be regularized by using a Birkhoff-type transformation. This transformation has the important property to provide a simultaneous regularization of three singularities due to binary collision. We present some ejection–collision orbits after the regularization of the restricted four-body problem (RFBP) with equal masses, which were obtained by numerical integration.

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Garrison, Lehman H., Daniel J. Eisenstein, and Philip A. Pinto. "A high-fidelity realization of the Euclid code comparison N-body simulation with Abacus." Monthly Notices of the Royal Astronomical Society 485, no. 3 (March 7, 2019): 3370–77. http://dx.doi.org/10.1093/mnras/stz634.

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Abstract We present a high-fidelity realization of the cosmological N-body simulation from the Schneider et al. code comparison project. The simulation was performed with our AbacusN-body code, which offers high-force accuracy, high performance, and minimal particle integration errors. The simulation consists of 20483 particles in a $500\ h^{-1}\, \mathrm{Mpc}$ box for a particle mass of $1.2\times 10^9\ h^{-1}\, \mathrm{M}_\odot$ with $10\ h^{-1}\, \mathrm{kpc}$ spline softening. Abacus executed 1052 global time-steps to z = 0 in 107 h on one dual-Xeon, dual-GPU node, for a mean rate of 23 million particles per second per step. We find Abacus is in good agreement with Ramses and Pkdgrav3 and less so with Gadget3. We validate our choice of time-step by halving the step size and find sub-percent differences in the power spectrum and 2PCF at nearly all measured scales, with ${\lt }0.3{{\ \rm per\ cent}}$ errors at $k\lt 10\ \mathrm{Mpc}^{-1}\, h$. On large scales, Abacus reproduces linear theory better than 0.01 per cent. Simulation snapshots are available at http://nbody.rc.fas.harvard.edu/public/S2016.

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Tindell, R. H. "Computational Fluid Dynamic Applications for Jet Propulsion System Integration." Journal of Engineering for Gas Turbines and Power 113, no. 1 (January 1, 1991): 40–50. http://dx.doi.org/10.1115/1.2906529.

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The impact of computational fluid dynamics (CFD) methods on the development of advanced aerospace vehicles is growing stronger year by year. Design engineers are now becoming familiar with CFD tools and are developing productive methods and techniques for their applications. This paper presents and discusses applications of CFD methods used at Grumman to design and predict the performance of propulsion system elements such as inlets and nozzles. The paper demonstrates techniques for applying various CFD codes and shows several interesting and unique results. A novel application of a supersonic Euler analysis of an inlet approach flow field, to clarify a wind tunnel-to-flight data conflict, is presented. In another example, calculations and measurements of low-speed inlet performance at angle of attack are compared. This is highlighted by employing a simplistic and low-cost computational model. More complex inlet flow phenomena at high angles of attack, calculated using an approach that combines a panel method with a Navier-Stokes (N-S) code, is also reviewed. The inlet fluid mechanics picture is rounded out by describing an N-S calculation and a comparison with test data of an offset diffuser having massively separated flow on one wall. Finally, the propulsion integration picture is completed by a discussion of the results of nozzle-afterbody calculations, using both a complete aircraft simulation in a N-S code, and a more economical calculation using an equivalent body of revolution technique.

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Arnold, M. "A recursive multibody formalism for systems with small mass and inertia terms." Mechanical Sciences 4, no. 1 (May 17, 2013): 221–31. http://dx.doi.org/10.5194/ms-4-221-2013.

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Abstract. Complex multibody system models that contain bodies with small mass or nearly singular inertia tensor may suffer from high frequency solution components that deteriorate the solver efficiency in time integration. Singular perturbation theory suggests to neglect these small mass and inertia terms to allow a more efficient computation of the smooth solution components. In the present paper, a recursive multibody formalism is developed to evaluate the equations of motion for a tree structured N body system with O(N) complexity even if isolated bodies have a rank-deficient body mass matrix. The approach is illustrated by some academic test problems in 2-D.

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Nitadori, Keigo, Junichiro Makino, and Piet Hut. "Performance tuning of N-body codes on modern microprocessors: I. Direct integration with a hermite scheme on x86_64 architecture." New Astronomy 12, no. 3 (December 2006): 169–81. http://dx.doi.org/10.1016/j.newast.2006.07.007.

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Luginbuehl, Edith, Damaris Ryter, Judith Schranz-Zumkehr, Michael Oberholzer, Stefan Kunz, and Thomas Seebeck. "The N Terminus of Phosphodiesterase TbrPDEB1 of Trypanosoma brucei Contains the Signal for Integration into the Flagellar Skeleton." Eukaryotic Cell 9, no. 10 (August 6, 2010): 1466–75. http://dx.doi.org/10.1128/ec.00112-10.

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ABSTRACT The precise subcellular localization of the components of the cyclic AMP (cAMP) signaling pathways is a crucial aspect of eukaryotic intracellular signaling. In the human pathogen Trypanosoma brucei, the strict control of cAMP levels by cAMP-specific phosphodiesterases is essential for parasite survival, both in cell culture and in the infected host. Among the five cyclic nucleotide phosphodiesterases identified in this organism, two closely related isoenzymes, T. brucei PDEB1 (TbrPDEB1) (PDEB1) and TbrPDEB2 (PDEB2) are predominantly responsible for the maintenance of cAMP levels. Despite their close sequence similarity, they are distinctly localized in the cell. PDEB1 is mostly located in the flagellum, where it forms an integral part of the flagellar skeleton. PDEB2 is mainly located in the cell body, and only a minor part of the protein localizes to the flagellum. The current study, using transfection of procyclic trypanosomes with green fluorescent protein (GFP) reporters, demonstrates that the N termini of the two enzymes are essential for determining their final subcellular localization. The first 70 amino acids of PDEB1 are sufficient to specifically direct a GFP reporter to the flagellum and to lead to its detergent-resistant integration into the flagellar skeleton. In contrast, the analogous region of PDEB2 causes the GFP reporter to reside predominantly in the cell body. Mutagenesis of selected residues in the N-terminal region of PDEB2 demonstrated that single amino acid changes are sufficient to redirect the reporter from a cell body location to stable integration into the flagellar skeleton.

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Jeraj, Damian, Lisa Musculus, and Babett H. Lobinger. "BODY IMAGE AND MENTAL REPRESENTATION IN TABLE TENNIS PLAYERS WHO DO VERSUS DO NOT USE A PROSTHESIS." Problems of Psychology in the 21st Century 11, no. 1 (December 25, 2017): 22–30. http://dx.doi.org/10.33225/ppc/17.11.22.

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The prosthesis that athletes use should take over the function of the missing limb. Playing table tennis without constraints is one exemplary goal. The question arose whether table tennis players who used a prosthesis and players who did not show similar body image values and mental representation of movements. Five matched pairs of active table tennis players (n = 10) completed a body image questionnaire. Additionally, the mental representation of a forehand table tennis serve was assessed. Results revealed no significant differences between the two groups of athletes on mental representations. Furthermore, the integration of the prosthesis into the body image was considered satisfying by four out of the five athletes with prosthesis, the use of a prosthesis did not appear to affect athletes’ body image. Based on the research results it can be recommended that in technical and mental training sessions, one methodological approach be used for all athletes, regardless of whether they use a prosthesis. Finally, it is suggested to foster the integration of athletes who use a prosthesis into the established leagues in which athletes compete who do not use prosthesis. Key words: functional body image, mental structure, SDA-M, athletes with disabilities.

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Meiron, Yohai, Jeremy J. Webb, Jongsuk Hong, Peter Berczik, Rainer Spurzem, and Raymond G. Carlberg. "Mass-loss from massive globular clusters in tidal fields." Monthly Notices of the Royal Astronomical Society 503, no. 2 (March 8, 2021): 3000–3009. http://dx.doi.org/10.1093/mnras/stab649.

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ABSTRACT Massive globular clusters lose stars via internal and external processes. Internal processes include mainly two-body relaxation, while external processes include interactions with the Galactic tidal field. We perform a suite of N-body simulations of such massive clusters using three different direct-summation N-body codes, exploring different Galactic orbits and particle numbers. By inspecting the rate at which a star’s energy changes as it becomes energetically unbound from the cluster, we can neatly identify two populations we call kicks and sweeps that escape through two-body encounters internal to the cluster and the external tidal field, respectively. We find that for a typical halo globular cluster on a moderately eccentric orbit, sweeps are far more common than kicks but the total mass-loss rate is so low that these clusters can survive for tens of Hubble times. The different N-body codes give largely consistent results, but we find that numerical artefacts may arise in relation to the time-step parameter of the Hermite integration scheme, namely that the value required for convergent results is sensitive to the number of particles.

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Karn, Tanya, and Michael E. Cinelli. "The effect of galvanic vestibular stimulation on path trajectory during a path integration task." Quarterly Journal of Experimental Psychology 72, no. 6 (September 17, 2018): 1550–60. http://dx.doi.org/10.1177/1747021818798824.

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The purpose of this study was to determine the effects of galvanic vestibular stimulation (GVS) on path trajectory and body rotation during a triangle completion task. Participants ( N = 17, female, 18-30 years) completed the triangle completion task in virtual reality using two different size triangles. GVS was delivered at three times each participant’s threshold in either the left or right direction prior to the final leg of the triangle and continued until the participant reached their final position. Whole body kinematics were collected using an NDI Optotrak motion tracking system. Results revealed a significant main effect of GVS on arrival error such that no GVS (NGVS) had significantly smaller arrival errors than when GVS was administered. There was also a significant main effect of GVS on angular error such that NGVS had significantly smaller error than GVSaway and GVStowards. There was no significant difference between GVS trials in path variability during the final leg on route to the final position. These results demonstrate that vestibular perturbation reduced the accuracy of the triangle completion task, affecting path trajectory and body position during a path integration task in the absence of visual cues.

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Altman, Claire E., Jennifer Van Hook, and Jonathan Gonzalez. "Becoming Overweight without Gaining a Pound: Weight Evaluations and the Social Integration of Mexicans in the United States." International Migration Review 51, no. 1 (March 2017): 3–36. http://dx.doi.org/10.1111/imre.12220.

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Mexican women gain weight with increasing duration in the United States. In the United States, body dissatisfaction tends to be associated with depression, disordered eating, and incongruent weight evaluations, particularly among white women and women of higher socioeconomic status. However, it remains unclear how being overweight and obesity are interpreted by Mexican women. Using comparable data of women aged 20–64 from both Mexico (the 2006 Encuesta Nacional de Salud y Nutricion; N = 17,012) and the United States (the 1999–2009 National Health and Nutrition Examination Surveys; N = 8,487), we compare weight status evaluations among Mexican nationals, Mexican immigrants, US-born Mexicans, US-born non-Hispanic whites, and US-born non-Hispanic blacks. Logistic regression analyses, which control for demographic and socioeconomic variables and measured body mass index and adjust for the likelihood of migration for Mexican nationals, indicate that the tendency to self-evaluate as overweight among Mexicans converges with levels among non-Hispanic whites and diverges from blacks over time in the United States. Overall, the results suggest a US integration process in which Mexican-American women's less critical self-evaluations originate in Mexico but fade with time in the United States as they gradually adopt US white norms for thinner body sizes. These results are discussed in light of prior research about social comparison and negative health assimilation.

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Löckmann, Ulf, and Holger Baumgardt. "Tracing Intermediate-Mass Black Holes in the Galactic Centre." Proceedings of the International Astronomical Union 3, S246 (September 2007): 367–68. http://dx.doi.org/10.1017/s1743921308015974.

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AbstractWe have developed a new method for post-Newtonian, high-precision integration of stellar systems containing a super-massive black hole (SMBH), splitting the forces on a particle between a dominant central force and perturbations. We used this method to perform fully collisional N-body simulations of inspiralling intermediate-mass black holes (IMBHs) in the centre of the Milky Way.

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Post, Brady, Tom Buchmueller, and Andrew M. Ryan. "Vertical Integration of Hospitals and Physicians: Economic Theory and Empirical Evidence on Spending and Quality." Medical Care Research and Review 75, no. 4 (August 29, 2017): 399–433. http://dx.doi.org/10.1177/1077558717727834.

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Hospital–physician vertical integration is on the rise. While increased efficiencies may be possible, emerging research raises concerns about anticompetitive behavior, spending increases, and uncertain effects on quality. In this review, we bring together several of the key theories of vertical integration that exist in the neoclassical and institutional economics literatures and apply these theories to the hospital–physician relationship. We also conduct a literature review of the effects of vertical integration on prices, spending, and quality in the growing body of evidence ( n = 15) to evaluate which of these frameworks have the strongest empirical support. We find some support for vertical foreclosure as a framework for explaining the observed results. We suggest a conceptual model and identify directions for future research. Based on our analysis, we conclude that vertical integration poses a threat to the affordability of health services and merits special attention from policymakers and antitrust authorities.

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Moldovan, Avigail, Yedael Y. Waldman, Nadav Brandes, and Michal Linial. "Body Mass Index and Birth Weight Improve Polygenic Risk Score for Type 2 Diabetes." Journal of Personalized Medicine 11, no. 6 (June 21, 2021): 582. http://dx.doi.org/10.3390/jpm11060582.

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One of the major challenges in the post-genomic era is elucidating the genetic basis of human diseases. In recent years, studies have shown that polygenic risk scores (PRS), based on aggregated information from millions of variants across the human genome, can estimate individual risk for common diseases. In practice, the current medical practice still predominantly relies on physiological and clinical indicators to assess personal disease risk. For example, caregivers mark individuals with high body mass index (BMI) as having an increased risk to develop type 2 diabetes (T2D). An important question is whether combining PRS with clinical metrics can increase the power of disease prediction in particular from early life. In this work we examined this question, focusing on T2D. We present here a sex-specific integrated approach that combines PRS with additional measurements and age to define a new risk score. We show that such approach combining adult BMI and PRS achieves considerably better prediction than each of the measures on unrelated Caucasians in the UK Biobank (UKB, n = 290,584). Likewise, integrating PRS with self-reports on birth weight (n = 172,239) and comparative body size at age ten (n = 287,203) also substantially enhance prediction as compared to each of its components. While the integration of PRS with BMI achieved better results as compared to the other measurements, the latter are early-life measurements that can be integrated already at childhood, to allow preemptive intervention for those at high risk to develop T2D. Our integrated approach can be easily generalized to other diseases, with the relevant early-life measurements.

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Allen, Susan, and Jackie Casey. "Developmental coordination disorders and sensory processing and integration: Incidence, associations and co-morbidities." British Journal of Occupational Therapy 80, no. 9 (June 14, 2017): 549–57. http://dx.doi.org/10.1177/0308022617709183.

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Introduction Children with developmental coordination disorder or sensory processing and integration difficulties face challenges to participation in daily living. To date there has been no exploration of the co-occurrence of developmental coordination disorders and sensory processing and integration difficulties. Method Records of children meeting Diagnostic and Statistical Manual – V criteria for developmental coordination disorder ( n = 93) age 5 to 12 years were examined. Data on motor skills (Movement Assessment Battery for Children – 2) and sensory processing and integration (Sensory Processing Measure) were interrogated. Results Of the total sample, 88% exhibited some or definite differences in sensory processing and integration. No apparent relationship was observed between motor coordination and sensory processing and integration. The full sample showed high rates of some difficulties in social participation, hearing, body awareness, balance and motion, and planning and ideation. Further, children with co-morbid autistic spectrum disorder showed high rates of difficulties with touch and vision. Conclusion Most, but not all, children with developmental coordination disorder presented with some difficulties in sensory processing and integration that impacted on their participation in everyday activities. Sensory processing and integration difficulties differed significantly between those with and without co-morbid autistic spectrum disorder.

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Bartram, Peter, and Alexander Wittig. "Terrestrial exoplanet simulator: an error optimal planetary system integrator that permits close encounters." Monthly Notices of the Royal Astronomical Society 504, no. 1 (March 27, 2021): 678–91. http://dx.doi.org/10.1093/mnras/stab896.

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ABSTRACT We present Terrestrial Exoplanet Simulator (tes), a new n-body integration code for the accurate and rapid propagation of planetary systems in the presence of close encounters. tes builds upon the classic Encke method and integrates only the perturbations to Keplerian trajectories to reduce both the error and runtime of simulations. Variable step size is used throughout to enable close encounters to be precisely handled. A suite of numerical improvements is presented that together make tes optimal in terms of energy error. Lower runtimes are found in the majority of test problems considered when compared to direct integration using ias15. tes is freely available.

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Gdowski, Greg T., and Robert A. McCrea. "Integration of Vestibular and Head Movement Signals in the Vestibular Nuclei During Whole-Body Rotation." Journal of Neurophysiology 82, no. 1 (July 1, 1999): 436–49. http://dx.doi.org/10.1152/jn.1999.82.1.436.

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Single-unit recordings were obtained from 107 horizontal semicircular canal-related central vestibular neurons in three alert squirrel monkeys during passive sinusoidal whole-body rotation (WBR) while the head was free to move in the yaw plane (2.3 Hz, 20°/s). Most of the units were identified as secondary vestibular neurons by electrical stimulation of the ipsilateral vestibular nerve (61/80 tested). Both non–eye-movement ( n = 52) and eye-movement–related ( n = 55) units were studied. Unit responses recorded when the head was free to move were compared with responses recorded when the head was restrained from moving. WBR in the absence of a visual target evoked a compensatory vestibulocollic reflex (VCR) that effectively reduced the head velocity in space by an average of 33 ± 14%. In 73 units, the compensatory head movements were sufficiently large to permit the effect of the VCR on vestibular signal processing to be assessed quantitatively. The VCR affected the rotational responses of different vestibular neurons in different ways. Approximately one-half of the units (34/73, 47%) had responses that decreased as head velocity decreased. However, the responses of many other units (24/73) showed little change. These cells had signals that were better correlated with trunk velocity than with head velocity. The remaining units had responses that were significantly larger (15/73, 21%) when the VCR produced a decrease in head velocity. Eye-movement–related units tended to have rotational responses that were correlated with head velocity. On the other hand, non–eye-movement units tended to have rotational responses that were better correlated with trunk velocity. We conclude that sensory vestibular signals are transformed from head-in-space coordinates to trunk-in-space coordinates on many secondary vestibular neurons in the vestibular nuclei by the addition of inputs related to head rotation on the trunk. This coordinate transformation is presumably important for controlling postural reflexes and constructing a central percept of body orientation and movement in space.

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Sánchez, Mariana B., Gonzalo C. de Elía, and Juan José Downes. "Tidal and general relativistic effects in rocky planet formation at the substellar mass limit using N-body simulations." Astronomy & Astrophysics 637 (May 2020): A78. http://dx.doi.org/10.1051/0004-6361/201937317.

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Context. Recent observational results show that very low mass stars and brown dwarfs are able to host close-in rocky planets. Low-mass stars are the most abundant stars in the Galaxy, and the formation efficiency of their planetary systems is relevant in the computation of a global probability of finding Earth-like planets inside habitable zones. Tidal forces and relativistic effects are relevant in the latest dynamical evolution of planets around low-mass stars, and their effect on the planetary formation efficiency still needs to be addressed. Aims. Our goal is to evaluate the impact of tidal forces and relativistic effects on the formation of rocky planets around a star close to the substellar mass limit in terms of the resulting planetary architectures and its distribution according to the corresponding evolving habitable zone. Methods. We performed a set of N-body simulations spanning the first 100 Myr of the evolution of two systems composed of 224 embryos with a total mass 0.25 M⊕ and 74 embryos with a total mass 3 M⊕ around a central object of 0.08 M⊙. For these two scenarios we compared the planetary architectures that result from simulations that are purely gravitational with those from simulations that include the early contraction and spin-up of the central object, the distortions and dissipation tidal terms, and general relativistic effects. Results. We found that including these effects allows the formation and survival of a close-in (r < 0.07 au) population of rocky planets with masses in the range 0.001 < m∕M⊕ < 0.02 in all the simulations of the less massive scenario, and a close-in population with masses m ~ 0.35 M⊕ in just a few of the simulations of the more massive scenario. The surviving close-in bodies suffered more collisions during the integration time of the simulations. These collisions play an important role in their final masses. However, all of these bodies conserved their initial amount of water in mass throughout the integration time. Conclusions. The incorporation of tidal and general relativistic effects allows the formation of an in situ close-in population located in the habitable zone of the system. This means that both effects are relevant during the formation of rocky planets and their early evolution around stars close to the substellar mass limit, in particular when low-mass planetary embryos are involved.

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Zhang, A., A. Leow, L. Zhan, J. GadElkarim, T. Moody, S. Khalsa, M. Strober, and J. D. Feusner. "Brain connectome modularity in weight-restored anorexia nervosa and body dysmorphic disorder." Psychological Medicine 46, no. 13 (July 19, 2016): 2785–97. http://dx.doi.org/10.1017/s0033291716001458.

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BackgroundAnorexia nervosa (AN) and body dysmorphic disorder (BDD) frequently co-occur, and have several overlapping phenomenological features. Little is known about their shared neurobiology. The aim of the study was to compare modular organization of brain structural connectivity.MethodWe acquired diffusion-weighted magnetic resonance imaging data on unmedicated individuals with BDD (n = 29), weight-restored AN (n = 24) and healthy controls (HC) (n = 31). We constructed connectivity matrices using whole-brain white matter tractography, and compared modular structures across groups.ResultsAN showed abnormal modularity involving frontal, basal ganglia and posterior cingulate nodes. There was a trend in BDD for similar abnormalities, but no significant differences compared with AN. In AN, poor insight correlated with longer path length in right caudal anterior cingulate and right posterior cingulate.ConclusionsAbnormal network organization patterns in AN, partially shared with BDD, may have implications for understanding integration between reward and habit/ritual formation, as well as conflict monitoring/error detection.

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Hamers, Adrian S. "Secular dynamics of hierarchical multiple systems composed of nested binaries, with an arbitrary number of bodies and arbitrary hierarchical structure – III. Suborbital effects: hybrid integration techniques and orbit-averaging corrections." Monthly Notices of the Royal Astronomical Society 494, no. 4 (April 22, 2020): 5492–506. http://dx.doi.org/10.1093/mnras/staa1084.

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ABSTRACT The secularmultiple code, presented in two previous papers of this series, integrates the long-term dynamical evolution of multiple systems with any number of bodies and hierarchical structure, provided that the system is composed of nested binaries. In the formalism underlying secularmultiple, we previously averaged over all orbits in the system. This approximation significantly speeds up numerical integration of the equations of motion, making large population synthesis studies possible. However, the orbit averaging approximation can break down when the secular evolution time-scale of the system is comparable to or shorter than any of the orbital periods in the system. Here, we present an update to secularmultiple in which we incorporate hybrid integration techniques, and orbit-averaging corrections. With this update, the user can specify which orbits should be integrated directly (without averaging), or assuming averaged orbits. For orbits that are integrated directly, we implemented two integration techniques, one which is based on the regularized Kustaanheimo–Stiefel equations of motion in element form. We also implemented analytical orbit-averaging corrections for pairwise interactions to quadrupole order. The updates presented here provide more flexibility for integrating the long-term dynamical evolution of hierarchical multiple systems. By effectively combining direct integration and orbit averaging the long-term evolution can be accurately computed, but with significantly lower computational cost compared to existing direct N-body codes. We give a number of examples in which the new features are beneficial. Our updated code, which is written in c++ supplemented with a user-friendly interface in python, is freely available.

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Salameh-Matar, Abeer, Naser Basal, and Naomi Weintraub. "Relationship between body functions and Arabic handwriting performance at different acquisition stages." Canadian Journal of Occupational Therapy 85, no. 5 (December 2018): 418–27. http://dx.doi.org/10.1177/0008417419826114.

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Background. The written languages and handwriting acquisition stages place different demands on the writer. Therefore, the relationship between body functions and handwriting performance may vary in different languages and acquisition stages; yet these demands have not been studied in the Arabic language. Purpose. We examined the relationship between linguistic, visual-motor integration (VMI), and motor coordination (MC) functions and Arabic handwriting at two handwriting acquisition stages. Method. This study used a cross-sectional and correlative design. Second- ( n = 54) and fourth-grade ( n = 59) students performed tasks examining reading, handwriting automaticity, VMI, MC, and copying a text. Findings. Handwriting automaticity significantly explained the variance in handwriting speed in both grades, in addition to the VMI in second grade and the MC in fourth grade. Enhanced performance in the VMI increased the likelihood of having good legibility in second but not in fourth grade. Implications. Similar to other languages, the body functions related to Arabic handwriting vary at the different acquisition stages. Handwriting evaluation should be adjusted to students’ acquisition stage.

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Wilkinson, Althea, and Tim de Zeeuw. "Integrals of Motion in an Elliptical Galaxy Model." Symposium - International Astronomical Union 127 (1987): 485–86. http://dx.doi.org/10.1017/s0074180900185869.

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The structure of a galaxy model is described completely by its phase–space distribution function f. By Jeans' Theorem f can be written as a function of the integrals of motion admitted by the potential of the model. Various independent combinations of the integrals may be used as arguments of f; in many cases the action integrals are to be preferred. For a general N–body model, these can be obtained by numerical integration and subsequent spectral decomposition of each orbit (Binney and Spergel 1984).

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Fujii, Michiko S., Takayuki R. Saitoh, Long Wang, and Yutaka Hirai. "SIRIUS project. II. A new tree-direct hybrid code for smoothed particle hydrodynamics/N-body simulations of star clusters." Publications of the Astronomical Society of Japan 73, no. 4 (May 18, 2021): 1057–73. http://dx.doi.org/10.1093/pasj/psab037.

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Abstract Star clusters form via clustering star formation inside molecular clouds. In order to understand the dynamical evolution of star clusters in their early phase, in which they are still embedded in their surrounding gas, we need accurate integration of individual stellar orbits without gravitational softening in the systems including both gas and stars, as well as modeling of individual stars with a realistic mass function. We develop a new tree-direct hybrid smoothed particle hydrodynamics/N-body code, ASURA$+$BRIDGE, in which stars are integrated using a direct N-body scheme or PeTar, a particle–particle particle-tree scheme code, without gravitational softening. In ASURA$+$BRIDGE, stars are assumed to have masses randomly drawn from a given initial mass function. With this code, we perform star cluster formation simulations starting from molecular clouds without gravitational softening. We find that artificial dense cores in star cluster centers due to the softening disappear when we do not use softening. We further demonstrate that star clusters are built up via mergers of smaller clumps. The star clusters formed in our simulations include some dynamically formed binaries with minimum semi-major axes of a few au, and the binary fraction is higher for more massive stars.

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Wang, Y., E. Athanassoula, and S. Mao. "Basis function expansions for galactic dynamics: Spherical versus cylindrical coordinates." Astronomy & Astrophysics 639 (July 2020): A38. http://dx.doi.org/10.1051/0004-6361/202038225.

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Aims. The orbital structure of galaxies is strongly influenced by the accuracy of the force calculation during orbit integration. We explore the accuracy of force calculations for two expansion methods and determine which one is preferable for orbit integration. Methods. We specifically compare two methods, one was introduced by Hernquist & Ostriker (HO), which uses a spherical coordinate system and was built specifically for the Hernquist model, and the other by Vasiliev & Athanassoula (CylSP) has a cylindrical coordinate system. Our comparisons include the Dehnen profile, its triaxial extension (of which the Hernquist profile is a special case) and a multicomponent system including a bar and disk density distributions for both analytical models and N-body realizations. Results. For the generalized Dehnen density, the CylSP method is more accurate than the HO method for nearly all inner power-law indices and shapes at all radii. For N-body realizations of the Dehnen model, or snapshots of an N-body simulation, the CylSP method is more accurate than the HO method in the central region for the oblate, prolate, and triaxial Hernquist profiles if the particle number is more than 5 × 105. For snapshots of the Hernquist models with spherical shape, the HO method is preferred. For the Ferrers bar model, the force from the CylSP method is more accurate than the HO method. The CPU time required for the initialization of the HO method is significantly shorter than that for the CylSP method, while the HO method costs subsequently much more CPU time than the CylSP method if the input corresponds to particle positions. From surface of section analyses, we find that the HO method creates more chaotic orbits than the CylSP method in the bar model. This could be understood to be due to a spurious peak in the central region when the force is calculated with the HO expansion. Conclusions. For an analytical model, the CylSP method with an inner cutoff radius of interpolation Rmin as calculated by the AGAMA software, is preferred due to its accuracy. For snapshots or N-body realizations not including a disk or a bar component, a detailed comparison between these two methods is needed if a density model other than the Dehnen model is used. For multicomponent systems, including a disk and a bar, the CylSP method is preferable.

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Klaus, Manuel P., Gerda C. Wyssen, Sebastian M. Frank, Wilhelm M. Malloni, Mark W. Greenlee, and Fred W. Mast. "Vestibular Stimulation Modulates Neural Correlates of Own-body Mental Imagery." Journal of Cognitive Neuroscience 32, no. 3 (March 2020): 484–96. http://dx.doi.org/10.1162/jocn_a_01496.

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There is growing evidence that vestibular information is not only involved in reflexive eye movements and the control of posture but it also plays an important role in higher order cognitive processes. Previous behavioral research has shown that concomitant vestibular stimuli influence performance in tasks that involve imagined self-rotations. These results suggest that imagined and perceived body rotations share common mechanisms. However, the nature and specificity of these effects remain largely unknown. Here, we investigated the neural mechanisms underlying this vestibulocognitive interaction. Participants ( n = 20) solved an imagined self-rotation task during caloric vestibular stimulation. We found robust main effects of caloric vestibular stimulation in the core region of the vestibular network, including the rolandic operculum and insula bilaterally, and of the cognitive task in parietal and frontal regions. Interestingly, we found an interaction of stimulation and task in the left inferior parietal lobe, suggesting that this region represents the modulation of imagined body rotations by vestibular input. This result provides evidence that the inferior parietal lobe plays a crucial role in the neural integration of mental and physical body rotation.

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Qin, Wenxia, Lydia Wunderley, Anne L. Barrett, Stephen High, and Philip G. Woodman. "The Charcot Marie Tooth disease protein LITAF is a zinc-binding monotopic membrane protein." Biochemical Journal 473, no. 21 (October 27, 2016): 3965–78. http://dx.doi.org/10.1042/bcj20160657.

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LITAF (LPS-induced TNF-activating factor) is an endosome-associated integral membrane protein important for multivesicular body sorting. Several mutations in LITAF cause autosomal-dominant Charcot Marie Tooth disease type 1C. These mutations map to a highly conserved C-terminal region, termed the LITAF domain, which includes a 22 residue hydrophobic sequence and flanking cysteine-rich regions that contain peptide motifs found in zinc fingers. Although the LITAF domain is thought to be responsible for membrane integration, the membrane topology of LITAF has not been established. Here, we have investigated whether LITAF is a tail-anchored (TA) membrane-spanning protein or monotopic membrane protein. When translated in vitro, LITAF integrates poorly into ER-derived microsomes compared with Sec61β, a bona fide TA protein. Furthermore, introduction of N-linked glycosylation reporters shows that neither the N-terminal nor C-terminal domains of LITAF translocate into the ER lumen. Expression in cells of an LITAF construct containing C-terminal glycosylation sites confirms that LITAF is not a TA protein in cells. Finally, an immunofluorescence-based latency assay showed that both the N- and C-termini of LITAF are exposed to the cytoplasm. Recombinant LITAF contains 1 mol/mol zinc, while mutation of predicted zinc-binding residues disrupts LITAF membrane association. Hence, we conclude that LITAF is a monotopic membrane protein whose membrane integration is stabilised by a zinc finger. The related human protein, CDIP1 (cell death involved p53 target 1), displays identical membrane topology, suggesting that this mode of membrane integration is conserved in LITAF family proteins.

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Regenbogen, Christina, John Axelsson, Julie Lasselin, Danja K. Porada, Tina Sundelin, Moa G. Peter, Mats Lekander, Johan N. Lundström, and Mats J. Olsson. "Behavioral and neural correlates to multisensory detection of sick humans." Proceedings of the National Academy of Sciences 114, no. 24 (May 22, 2017): 6400–6405. http://dx.doi.org/10.1073/pnas.1617357114.

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Throughout human evolution, infectious diseases have been a primary cause of death. Detection of subtle cues indicating sickness and avoidance of sick conspecifics would therefore be an adaptive way of coping with an environment fraught with pathogens. This study determines how humans perceive and integrate early cues of sickness in conspecifics sampled just hours after the induction of immune system activation, and the underlying neural mechanisms for this detection. In a double-blind placebo-controlled crossover design, the immune system in 22 sample donors was transiently activated with an endotoxin injection [lipopolysaccharide (LPS)]. Facial photographs and body odor samples were taken from the same donors when “sick” (LPS-injected) and when “healthy” (saline-injected) and subsequently were presented to a separate group of participants (n = 30) who rated their liking of the presented person during fMRI scanning. Faces were less socially desirable when sick, and sick body odors tended to lower liking of the faces. Sickness status presented by odor and facial photograph resulted in increased neural activation of odor- and face-perception networks, respectively. A superadditive effect of olfactory–visual integration of sickness cues was found in the intraparietal sulcus, which was functionally connected to core areas of multisensory integration in the superior temporal sulcus and orbitofrontal cortex. Taken together, the results outline a disease-avoidance model in which neural mechanisms involved in the detection of disease cues and multisensory integration are vital parts.

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Journal articles on the topic 'N-body integration'

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