scholarly journals Dynamical evolution of voids with surrounding gravitational tidal field

2021 ◽  
Vol 503 (2) ◽  
pp. 2804-2813
Author(s):  
Mutsumi Minoguchi ◽  
Atsushi J Nishizawa ◽  
Tsutomu T Takeuchi ◽  
Naoshi Sugiyama
Keyword(s):  
Time Variation ◽  
Voronoi Tessellation ◽  
Dynamical Evolution ◽  
Watershed Algorithm ◽  
Quadrupole Field ◽  
Positive Correlation ◽  
Non Linear ◽  
Particle Exchange ◽  
Void Shape ◽  
Tidal Response

ABSTRACT The void ellipticity distribution today can be well explained by the tidal field. Going a step further from the overall distribution, we investigate individuality on the tidal response of void shape in non-linear dynamical evolution. We perform an N-body simulation and trace individual voids using particle ID. The voids are defined based on Voronoi tessellation and watershed algorithm, using public code vide. A positive correlation is found between the time variation of void ellipticity and tidal field around a void if the void maintains its constituent particles. Such voids tend to have smaller mass densities. Conversely, not a few voids significantly deform by particle exchange, rather than the tidal field. Those voids may prevent us from correctly probing a quadrupole field of gravity out of a void shape.

scholarly journals Evolution of supernovae-driven superbubbles with conduction and cooling

2019 ◽  
Vol 490 (2) ◽  
pp. 1961-1990 ◽  
Author(s):  
Kareem El-Badry ◽  
Eve C Ostriker ◽  
Chang-Goo Kim ◽  
Eliot Quataert ◽  
Daniel R Weisz
Keyword(s):  
Cooling Rate ◽  
Evaporation Rate ◽  
Mass Density ◽  
Dynamical Evolution ◽  
Effective Diffusivity ◽  
Blast Waves ◽  
Conductive Heat ◽  
Hydrodynamic Simulations ◽  
Non Linear ◽  
Order Of Magnitude

ABSTRACT We use spherically symmetric hydrodynamic simulations to study the dynamical evolution and internal structure of superbubbles (SBs) driven by clustered supernovae (SNe), focusing on the effects of thermal conduction and cooling in the interface between the hot bubble interior and cooled shell. Our simulations employ an effective diffusivity to account for turbulent mixing from non-linear instabilities that are not captured in 1D. The conductive heat flux into the shell is balanced by a combination of cooling in the interface and evaporation of shell gas into the bubble interior. This evaporation increases the density, and decreases the temperature, of the SB interior by more than an order of magnitude relative to simulations without conduction. However, most of the energy conducted into the interface is immediately lost to cooling, reducing the evaporative mass flux required to balance conduction. As a result, the evaporation rate is typically a factor of ∼3–30 lower than predicted by the classical similarity solution of (Weaver et al. 1977), which neglects cooling. Blast waves from the first ∼30 SNe remain supersonic in the SB interior because reduced evaporation from the interface lowers the mass they sweep up in the hot interior. Updating the Weaver solution to include cooling, we construct a new analytic model to predict the cooling rate, evaporation rate, and temporal evolution of SBs. The cooling rate, and hence the hot gas mass, momentum, and energy delivered by SBs, is set by the ambient interstellar mass density and the efficiency of non-linear mixing at the bubble–shell interface.

scholarly journals Non-linear description of massive neutrinos in the framework of large-scale structure formation

2014 ◽  
Vol 11 (S308) ◽  
pp. 121-124
Author(s):  
Hélène Dupuy
Keyword(s):  
Large Scale ◽  
Cold Dark Matter ◽  
Dynamical Evolution ◽  
Large Scale Structure ◽  
Scale Structure ◽  
Linear Regime ◽  
Non Linear ◽  
Massive Neutrinos ◽  
Single Flow ◽  
The Universe

AbstractThere is now no doubt that neutrinos are massive particles fully involved in the non-linear growth of the large-scale structure of the universe. A problem is that they are particularly difficult to include in cosmological models because the equations describing their behavior in the non-linear regime are cumbersome and difficult to handle. In this manuscript I present a new method allowing to deal with massive neutrinos in a very simple way, based on basic conservation laws. This method is still valid in the non-linear regime. The key idea is to describe neutrinos as a collection of single-flow fluids instead of seeing them as a single hot multi-flow fluid. In this framework, the time evolution of neutrinos is encoded in fluid equations describing macroscopic fields, just as what is done for cold dark matter. Although valid up to shell-crossing only, this approach is a further step towards a fully non-linear treatment of the dynamical evolution of neutrinos in the framework of large-scale structure growth.

scholarly journals Independently together: subthalamic theta and beta opposite roles in predicting Parkinson’s tremor

2020 ◽  
Vol 2 (2) ◽  
Author(s):  
Nir Asch ◽  
Yehuda Herschman ◽  
Rotem Maoz ◽  
Carmel R Auerbach-Asch ◽  
Dan Valsky ◽  
...  
Keyword(s):  
Parkinson’S Disease ◽  
Parkinson's Disease ◽  
Deep Brain Stimulation ◽  
Negative Correlation ◽  
Brain Stimulation ◽  
Significant Negative Correlation ◽  
Positive Correlation ◽  
Resting Tremor ◽  
Non Linear ◽  
Deep Brain

Abstract Tremor is a core feature of Parkinson’s disease and the most easily recognized Parkinsonian sign. Nonetheless, its pathophysiology remains poorly understood. Here, we show that multispectral spiking activity in the posterior-dorso-lateral oscillatory (motor) region of the subthalamic nucleus distinguishes resting tremor from the other Parkinsonian motor signs and strongly correlates with its severity. We evaluated microelectrode-spiking activity from the subthalamic dorsolateral oscillatory region of 70 Parkinson’s disease patients who underwent deep brain stimulation surgery (114 subthalamic nuclei, 166 electrode trajectories). We then investigated the relationship between patients’ clinical Unified Parkinson’s Disease Rating Scale score and their peak theta (4–7 Hz) and beta (13–30 Hz) powers. We found a positive correlation between resting tremor and theta activity (r = 0.41, P < 0.01) and a non-significant negative correlation with beta activity (r = −0.2, P = 0.5). Hypothesizing that the two neuronal frequencies mask each other’s relationship with resting tremor, we created a non-linear model of their proportional spectral powers and investigated its relationship with resting tremor. As hypothesized, patients’ proportional scores correlated better than either theta or beta alone (r = 0.54, P < 0.001). However, theta and beta oscillations were frequently temporally correlated (38/70 patients manifested significant positive temporal correlations and 1/70 exhibited significant negative correlation between the two frequency bands). When comparing theta and beta temporal relationship (r θ β) to patients’ resting tremor scores, we found a significant negative correlation between the two (r = −0.38, P < 0.01). Patients manifesting a positive correlation between the two bands (i.e. theta and beta were likely to appear simultaneously) were found to have lower resting tremor scores than those with near-zero correlation values (i.e. theta and beta were likely to appear separately). We therefore created a new model incorporating patients’ proportional theta–beta power and r θ βscores to obtain an improved neural correlate of resting tremor (r = 0.62, P < 0.001). We then used the Akaike and Bayesian information criteria for model selection and found the multispectral model, incorporating theta–beta proportional power and their correlation, to be the best fitting model, with 0.96 and 0.89 probabilities, respectively. Here we found that as theta increases, beta decreases and the two appear separately—resting tremor is worsened. Our results therefore show that theta and beta convey information about resting tremor in opposite ways. Furthermore, the finding that theta and beta coactivity is negatively correlated with resting tremor suggests that theta–beta non-linear scale may be a valuable biomarker for Parkinson’s resting tremor in future adaptive deep brain stimulation techniques.

Waveboard Artifacts Generate Ghost Resonances Consistent with Equations for Predicting Ion Motion in Commercial Quadrupole Ion Traps

2005 ◽  
Vol 11 (1) ◽  
pp. 15-21 ◽  
Author(s):  
Kwenga F. Sichilongo ◽  
Bert C. Lynn
Keyword(s):  
Ion Trap ◽  
Ion Traps ◽  
Quadrupole Ion Trap ◽  
Stability Diagram ◽  
Two Dimensional ◽  
Quadrupole Field ◽  
Non Linear ◽  
Contour Plots ◽  
The Stability ◽  
Contour Surface

Real-time experiments involving fragmentation of the precursor molecular ion of n-butylbenzene ( m/z 134) to produce product ions C7H+7 ( m/z 91) and C7H+8 ( m/z 92), were used to observe the motion of ions in a commercial quadrupole ion trap. Initially, ghost resonance peaks were observed for excitation of the precursor ion at qz values of 0.4 and 0.5 on the qz axis of the stability diagram. Further experiments involving the generation of two-dimensional contour plots confirmed that these ghost peaks, which were in agreement with mathematical equations describing the motion of ions in a quadrupole field, arose due to waveboard artifacts. Two-dimensional contour surface plots showed non-linear secular frequency canyons from a qz value of 0.5 to higher values corresponding with higher drive radio frequency (rf) voltages on the stability diagram. This observation confirmed that ions are subjected to non-linear effects in this mass scan range. The octapole and hexapole field lines were observed at qz values of 0.65 and 0.78, respectively.

scholarly journals Theoretical Models for the Galaxy Angular Correlation Function

1988 ◽  
Vol 130 ◽  
pp. 556-556
Author(s):  
H.M.P. Couchman ◽  
J.R. Bond
Keyword(s):  
Correlation Function ◽  
Observational Data ◽  
Angular Correlation ◽  
Initial Conditions ◽  
Dynamical Evolution ◽  
Theoretical Models ◽  
Linear Evolution ◽  
Non Linear ◽  
The Galaxy ◽  
Angular Correlation Function

The spatial two point galaxy correlation function, ξ(r), is, at present, the most useful statistic for comparing theoretical models to observational data. We have derived expressions for the dynamical evolution of ξ for structures arising from Gaussian initial conditions under the assumption that non-linear evolution may be described by the Zel'dovich approximation. The observed angular correlation function, w(θ), places constraints on the spectrum of initial fluctuations on large scales.

HADRONIC MODELING OF AGN VARIABILITY

2012 ◽  
Vol 08 ◽  
pp. 293-298 ◽  
Author(s):  
FELIX SPANIER ◽  
MATTHIAS WEIDINGER
Keyword(s):  
Time Variation ◽  
Gamma Ray ◽  
Time Dependent ◽  
Emission Scenarios ◽  
Linear Processes ◽  
Bl Lac Objects ◽  
Variation Patterns ◽  
Bl Lac ◽  
Non Linear ◽  
Emission Models

The ongoing search for extragalactic gamma-ray sources reveals more and more blazars not classified as high-peaked BL Lac objects. These sources may not be understood in the context of purely leptonic emission models. In the present paper we study lepto-hadronic emission models, especially their time variation patterns. Since a number of non-linear processes are involved, timing relations are far more complex than in purely leptonic models and might eventually be used to discriminate different emission scenarios. First complete time dependent applications to 3C279 and 3C454.3 are presented.

B. The Non-Linear Calculations for Pulsating Stars

1967 ◽  
Vol 28 ◽  
pp. 105-176
Author(s):  
Robert F. Christy
Keyword(s):  
Major Part ◽  
Afternoon Session ◽  
Discussion Session ◽  
Pulsating Stars ◽  
Fourth Symposium ◽  
Non Linear ◽  
Considerable Discussion ◽  
Informal Approach ◽  
Preceding Session

(Ed. note: The custom in these Symposia has been to have a summary-introductory presentation which lasts about 1 to 1.5 hours, during which discussion from the floor is minor and usually directed at technical clarification. The remainder of the session is then devoted to discussion of the whole subject, oriented around the summary-introduction. The preceding session, I-A, at Nice, followed this pattern. Christy suggested that we might experiment in his presentation with a much more informal approach, allowing considerable discussion of the points raised in the summary-introduction during its presentation, with perhaps the entire morning spent in this way, reserving the afternoon session for discussion only. At Varenna, in the Fourth Symposium, several of the summaryintroductory papers presented from the astronomical viewpoint had been so full of concepts unfamiliar to a number of the aerodynamicists-physicists present, that a major part of the following discussion session had been devoted to simply clarifying concepts and then repeating a considerable amount of what had been summarized. So, always looking for alternatives which help to increase the understanding between the different disciplines by introducing clarification of concept as expeditiously as possible, we tried Christy's suggestion. Thus you will find the pattern of the following different from that in session I-A. I am much indebted to Christy for extensive collaboration in editing the resulting combined presentation and discussion. As always, however, I have taken upon myself the responsibility for the final editing, and so all shortcomings are on my head.)

Statistical results on discovered near-Earth asteroids

1999 ◽  
Vol 173 ◽  
pp. 81-86
Author(s):  
S. Berinde
Keyword(s):  
Dynamical Evolution ◽  
Minor Planet ◽  
Orbital Elements ◽  
The Earth ◽  
Near Earth Asteroids ◽  
Statistical Results

AbstractThe first part of this paper gives a recent overview (until July 1st, 1998) of the Near-Earth Asteroids (NEAs) database stored at Minor Planet Center. Some statistical interpretations point out strong observational biases in the population of discovered NEAs, due to the preferential discoveries, depending on the objects’ distances and sizes. It is known that many newly discovered NEAs have no accurately determinated orbits because of the lack of observations. Consequently, it is hard to speak about future encounters and collisions with the Earth in terms of mutual distances between bodies. Because the dynamical evolution of asteroids’ orbits is less sensitive to the improvement of their orbital elements, we introduced a new subclass of NEAs named Earth-encounter asteroids in order to describe more reliably the potentially dangerous bodies as impactors with the Earth. So, we pay attention at those asteroids having an encounter between their orbits and that of the Earth within 100 years, trying to classify these encounters.

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