On the critical mass of the collapse of a gaseous star in spherically symmetric and isentropic motion

Abstract The global visibility of a singularity as an end state of the gravitational collapse of a spherically symmetric pressureless cloud is investigated. We show the existence of a non-zero measured set of parameters: the total mass and the initial mean density of the collapsing cloud, giving rise to a physically strong globally visible singularity as the end state for a fixed velocity function. The existence of such a set indicates that such singularity is stable under small perturbation in the initial data causing its existence. This is true for marginally as well as non-marginally bound cases. The possibility of the presence of such suitable parameters in the astrophysical setup is then studied: 1) The singularities’ requirements at the center of the M87 galaxy and at the center of our galaxy (SgrA*) to be globally visible are discussed in terms of the initial size of the collapsing cloud forming them, presuming that such singularities are formed due to gravitational collapse. 2) The requirement for the primordial singularities formed due to a collapsing configuration after getting detached from the background universe, at the time of matter-dominated era just after the time of matter-radiation equality, to be globally visible, is discussed. 3) The scenario of the collapse of a neutron star after reaching a critical mass, which is achieved by accreting the supernova ejecta expelled by its binary companion core progenitor, is considered. The primary aim of this paper is to show that globally visible singularities can form in astrophysical setups under appropriate circumstances.

Download Full-text

Critical Psychology Reaching Critical Mass

Contemporary Psychology ◽

10.1037/002951 ◽

1996 ◽

Vol 41 (6) ◽

pp. 560-562

Author(s):

Isaac Prilleltensky

Keyword(s):

Critical Mass ◽

Critical Psychology

Download Full-text

Design of N-dimensional multiplierless spherically symmetric FIR digital filters by transformation

IEE Proceedings G (Electronic Circuits and Systems) ◽

10.1049/ip-g-1.1988.0030 ◽

1988 ◽

Vol 135 (5) ◽

pp. 203

Author(s):

C. Charalambous

Keyword(s):

Digital Filters ◽

Spherically Symmetric ◽

Fir Digital Filters

Download Full-text

EFFECT OF DIGITAL COMMUNITY TOWARDS DEMOCRACY PROCESS: DIGITAL PARTISIPATION ANALYSIS IN INDONESIA

Jurnal Good Governance ◽

10.32834/gg.v15i2.123 ◽

2020 ◽

Vol 15 (2) ◽

Author(s):

Alih Aji Nugroho

Keyword(s):

Public Policy ◽

Social Media ◽

Political Participation ◽

Public Space ◽

Rapid Development ◽

Critical Mass ◽

Digital Society ◽

Digital World ◽

Digital Community ◽

The Government

The world is entering a new phase of the digital era, including Indonesia. The unification of the real world and cyberspace is a sign, where the conditions of both can influence each other (Hyung Jun, 2018). The patterns of behavior and public relations in the virtual universe gave rise to new social interactions called the Digital Society. One part of Global Megatrends has also influenced public policy in Indonesia in recent years. Critical mass previously carried out conventionally is now a virtual movement. War of hashtags, petitions, and digital community comments are new tools and strategies for influencing policy. This paper attempts to analyze the extent of digital society's influence on public policy in Indonesia. As well as what public policy models are needed. Methodology used in this analysis is qualitative descriptive. Data collection through literature studies by critical mass digital recognition in Indonesia and trying to find a relationship between political participation through social media and democracy. By processing the pro and contra views regarding the selection of social media as a level of participation, this paper finds that there are overlapping interests that have the potential to distort the articulation of freedom of opinion and participation. - which is characteristic of a democratic state. The result is the rapid development of digital society which greatly influences the public policy process. Digital society imagines being able to participate formally in influencing policy in Indonesia. The democracy that developed in the digital society is cyberdemocracy. Public space in the digital world must be guaranteed security and its impact on the policies that will be determined. The recommendation given to the government is that a cyber data analyst is needed to oversee the issues that are developing in the digital world. Regulations related to the security of digital public spaces must be maximized. The government maximizes cooperation with related stakeholders.Keywords: Digital Society; Democracy; Public policy; Political Participation

Download Full-text

The Evolutionary Psychology of Scientific Publishing: Cost-Benefit Optimization of Players in the Game

10.32942/osf.io/nvpe2 ◽

2019 ◽

Author(s):

Milind Watve

Keyword(s):

Peer Review ◽

Current System ◽

Critical Mass ◽

Cost Benefit ◽

Active Role ◽

Scientific Publishing ◽

Collective Goal ◽

The Cost ◽

Collective Goals ◽

Innate Tendency

Peer reviewed scientific publishing is critical for communicating important findings, interpretations and theories in any branch of science. While the value of peer review is rarely doubted, much concern is being raised about the possible biases in the process. I argue here that most of the biases originate in the evolved innate tendency of every player to optimize one’s own cost benefits. Different players in the scientific publishing game have different cost-benefit optima. There are multiple conflicts between individual optima and collective goals. An analysis of the cost-benefit optima of every player in the scientific publishing game shows how and why biases originate. In the current system of publishing, by optimization considerations, the probability of publishing a ‘bad’ manuscript is relatively small but the probability of rejecting a ‘good’ manuscript is very high. By continuing with the current publishing structure, the global distribution of the scientific community would be increasingly clustered. Publication biases by gender, ethnicity, reputation, conformation and conformity will be increasingly common and revolutionary concepts increasingly difficult to publish. Ultimately, I explore the possibility of designing a peer review publishing system in which the conflicts between individual optimization and collective goal can be minimized. In such a system, if everyone behaves with maximum selfishness, biases would be minimized and the progress towards the collective goal would be faster and smoother. Changing towards such a system might prove difficult unless a critical mass of authors take an active role to revolutionize scientific publishing.

Download Full-text

A method for determining the natural moisture content of dentin in a clinical setting

Medical alphabet ◽

10.33667/2078-5631-2020-12-36-39 ◽

2020 ◽

Vol 1 (12) ◽

pp. 36-39

Author(s):

L. V. Iyashvili ◽

Yu. A. Vinnichenko ◽

A. V. Vinnichenko

Keyword(s):

Composite Material ◽

Moisture Content ◽

Computer Program ◽

Clinical Setting ◽

Quantitative Assessment ◽

Critical Mass ◽

Filling Material ◽

Adhesive Interaction ◽

Natural Moisture Content ◽

Hard Tissues

The purpose of the study is a quantitative assessment of the yield of dentinal fluid on the surface of the treated dentin of the tooth when restoring its structure with a composite filling material. To achieve this goal, digital images of the coronal parts of the teeth having formed carious cavities were used; virtual models of hard tissues of teeth recreated using specialized computer programs; A computer program that provides the ability to accurately determine the area of the treated dentin tooth. The results made it possible to draw the following conclusions: with an increase in the depth of the carious cavity, the amount of dentin fluid that can stand out on its surface (1–2 mm from the tooth cavity) sharply increases; with an increase in the area of the formed carious cavity (more than 30 mm2), the risk of release of a critical mass of dentinal fluid (more than 0.4 mg), which can adversely affect the strength of the adhesive interaction between the composite material and the hard tissues of the tooth, increases significantly; the same dynamics is observed with increasing time, at which there is the possibility of free exit of dentinal fluid to the surface of the cavity prepared for filling (more than 45 seconds).

Download Full-text