A systematic development of Jeans’ criterion with rotation for gravitational instabilities

2019 ◽  
Vol 12 (7) ◽  
pp. 1099-1108
Author(s):  
Kohl Gill ◽  
David J. Wollkind ◽  
Bonni J. Dichone
Keyword(s):  
Gravitational Instabilities ◽  
Jeans Criterion ◽  
Systematic Development

scholarly journals GRAVITOMAGNETIC INSTABILITIES IN ANISOTROPICALLY EXPANDING FLUIDS

2008 ◽  
Vol 23 (27n28) ◽  
pp. 4467-4484 ◽  
Author(s):  
KOSTAS KLEIDIS ◽  
APOSTOLOS KUIROUKIDIS ◽  
DEMETRIOS B. PAPADOPOULOS ◽  
LOUKAS VLAHOS
Keyword(s):  
Magnetic Field ◽  
Large Scale ◽  
Cosmological Models ◽  
Frw Universe ◽  
Curved Space ◽  
Gravitational Instabilities ◽  
Potential Formation ◽  
Jeans Criterion ◽  
General Relativistic ◽  
The Magnetic Field

Gravitational instabilities in a magnetized Friedman–Robertson–Walker (FRW) universe, in which the magnetic field was assumed to be too weak to destroy the isotropy of the model, are known and have been studied in the past. Accordingly, it became evident that the external magnetic field disfavors the perturbations' growth, suppressing the corresponding rate by an amount proportional to its strength. However, the spatial isotropy of the FRW universe is not compatible with the presence of large-scale magnetic fields. Therefore, in this paper we use the general-relativistic version of the (linearized) perturbed magnetohydrodynamic equations with and without resistivity, to discuss a generalized Jeans criterion and the potential formation of density condensations within a class of homogeneous and anisotropically expanding, self-gravitating, magnetized fluids in curved space–time. We find that, for a wide variety of anisotropic cosmological models, gravitomagnetic instabilities can lead to subhorizontal, magnetized condensations. In the nonresistive case, the power spectrum of the unstable cosmological perturbations suggests that most of the power is concentrated on large scales (small k), very close to the horizon. On the other hand, in a resistive medium, the critical wave-numbers so obtained, exhibit a delicate dependence on resistivity, resulting in the reduction of the corresponding Jeans lengths to smaller scales (well bellow the horizon) than the nonresistive ones, while increasing the range of cosmological models which admit such an instability.

Pengembangan Pembelajaran Model Blended Computer Based Learning (BCBL) Tentang Turunan Fungsi untuk Meningkatkan Kemandirian Belajar Siswa SMA

2019 ◽  
Vol 2 ◽  
Author(s):  
M. Safrudin ◽  
Sutaryat Trisnamansyah ◽  
Tb. Abin Syamsuddin Makmun ◽  
Deni Darmawan
Keyword(s):  
High Schools ◽  
Simulation Experiment ◽  
Computer Assisted ◽  
Development Stages ◽  
Computer Based Learning ◽  
Self Reliance ◽  
Computer Based ◽  
Systematic Development ◽  
Learner Activity

The aimed of this studied was developed learning through computer-assisted as BCBL. Result of this studied have been stated that: (a) the potential of five high schools in Karawang districts supported the implementation of BCBL development, (b) planning of BCBL development through a systematic development stages from preparation, production, simulation, experiment, and publication, (c) the implementation result of BCBL learning through revision tested were learner activity and higher autonomy. Keywords: BCBL; Independence Self-reliance; Student Competence.

scholarly journals Systematic Development of Patient Decision Aids: An Update from the IPDAS Collaboration

2021 ◽  
pp. 0272989X2110141
Author(s):  
Holly O. Witteman ◽  
Kristin G. Maki ◽  
Gratianne Vaisson ◽  
Jeanette Finderup ◽  
Krystina B. Lewis ◽  
...  
Keyword(s):  
Decision Aid ◽  
Decision Aids ◽  
Rapid Development ◽  
User Involvement ◽  
User Centered Design ◽  
Patient Decision Aid ◽  
Patient Decision Aids ◽  
Patient Decision ◽  
Development Processes ◽  
Systematic Development

Background The 2013 update of the evidence informing the quality dimensions behind the International Patient Decision Aid Standards (IPDAS) offered a model process for developers of patient decision aids. Objective To summarize and update the evidence used to inform the systematic development of patient decision aids from the IPDAS Collaboration. Methods To provide further details about design and development methods, we summarized findings from a subgroup ( n = 283 patient decision aid projects) in a recent systematic review of user involvement by Vaisson et al. Using a new measure of user-centeredness (UCD-11), we then rated the degree of user-centeredness reported in 66 articles describing patient decision aid development and citing the 2013 IPDAS update on systematic development. We contacted the 66 articles’ authors to request their self-reports of UCD-11 items. Results The 283 development processes varied substantially from minimal iteration cycles to more complex processes, with multiple iterations, needs assessments, and extensive involvement of end users. We summarized minimal, medium, and maximal processes from the data. Authors of 54 of 66 articles (82%) provided self-reported UCD-11 ratings. Self-reported scores were significantly higher than reviewer ratings (reviewers: mean [SD] = 6.45 [3.10]; authors: mean [SD] = 9.62 [1.16], P < 0.001). Conclusions Decision aid developers have embraced principles of user-centered design in the development of patient decision aids while also underreporting aspects of user involvement in publications about their tools. Templates may reduce the need for extensive development, and new approaches for rapid development of aids have been proposed when a more detailed approach is not feasible. We provide empirically derived benchmark processes and a reporting checklist to support developers in more fully describing their development processes. [Box: see text]

scholarly journals Systematic development of lectin conjugated microspheres for nose-to-brain delivery of rivastigmine for the treatment of Alzheimer’s disease

2021 ◽  
Vol 141 ◽  
pp. 111829
Author(s):  
Yang Gao ◽  
Waleed H. Almalki ◽  
Obaid Afzal ◽  
Sunil K. Panda ◽  
Imran Kazmi ◽  
...  
Keyword(s):  
Alzheimer’S Disease ◽  
Alzheimer's Disease ◽  
Brain Delivery ◽  
Systematic Development

scholarly journals Giant Molecular Cloud Formation at the Interface of Colliding Supershells in the Large Magellanic Cloud

2021 ◽  
Author(s):  
Kosuke Fujii ◽  
Norikazu Mizuno ◽  
J R Dawson ◽  
Tsuyoshi Inoue ◽  
Kazufumi Torii ◽  
...  
Keyword(s):  
Large Magellanic Cloud ◽  
Cloud Formation ◽  
Beam Size ◽  
Star Forming ◽  
Star Forming Regions ◽  
Long Baseline ◽  
Gravitational Instabilities ◽  
Atomic Medium ◽  
High Column ◽  
Compact Array

Abstract We investigate the H i envelope of the young, massive GMCs in the star-forming regions N48 and N49, which are located within the high column density H i ridge between two kpc-scale supergiant shells, LMC 4 and LMC 5. New long-baseline H i 21 cm line observations with the Australia Telescope Compact Array (ATCA) were combined with archival shorter baseline data and single dish data from the Parkes telescope, for a final synthesized beam size of 24.75″ by 20.48″, which corresponds to a spatial resolution of ∼ 6 pc in the LMC. It is newly revealed that the H i gas is highly filamentary, and that the molecular clumps are distributed along filamentary H i features. In total 39 filamentary features are identified and their typical width is ∼ 21 (8–49) [pc]. We propose a scenario in which the GMCs were formed via gravitational instabilities in atomic gas which was initially accumulated by the two shells and then further compressed by their collision. This suggests that GMC formation involves the filamentary nature of the atomic medium.

scholarly journals The Effects of Metallicity and Grain Size on Gravitational Instabilities in Protoplanetary Disks

2005 ◽  
Vol 636 (2) ◽  
pp. L149-L152 ◽  
Author(s):  
Kai Cai ◽  
Richard H. Durisen ◽  
Scott Michael ◽  
Aaron C. Boley ◽  
Annie C. Mejía ◽  
...  
Keyword(s):  
Grain Size ◽  
Protoplanetary Disks ◽  
Gravitational Instabilities

scholarly journals Structure Formation in Anisotropic Disks

2006 ◽  
Vol 2 (S235) ◽  
pp. 143-143
Author(s):  
Eduard Vorobyov ◽  
Christian Theis
Keyword(s):  
Stability Analysis ◽  
Linear Stability ◽  
Linear Stability Analysis ◽  
Disk Galaxies ◽  
Structural Elements ◽  
Small Perturbations ◽  
Gravitational Instabilities ◽  
Hydrodynamical Simulations ◽  
Axisymmetric Structures ◽  
Insight Into

The majority of normal disk galaxies are characterized by non-axisymmetric structures like spirals or bars. These structural elements have been widely discussed in the literature as a result of gravitational instabilities which are connected to growing density waves or global instabilities of disks. A first insight into the properties of galactic discs was provided by linear stability analysis. However, a disadvantage of linear stability analysis remained its restriction to small perturbations, both in amplitude and wavelength. Thus, numerical simulations, especially hydrodynamical and stellar-hydrodynamical simulations became a primary tool for the analysis of galactic evolution.

Sign in / Sign up

Export Citation Format

Share Document