scholarly journals A new look at the Bondi-Sachs energy-momentum

2021 ◽  
Author(s):  
Jörg Frauendiener ◽  
Chris Stevens
Keyword(s):  
Unit Sphere ◽  
Gauss Curvature ◽  
Null Infinity ◽  
Conformally Invariant ◽  
Lorentzian Metric ◽  
Correct Definition ◽  
Ghp Formalism ◽  
Bondi Mass ◽  
Definition Of ◽  
Bondi Energy

Abstract How does one compute the Bondi mass on an arbitrary cut of null infinity I when it is not presented in a Bondi system? What then is the correct definition of the mass aspect? How does one normalise an asymptotic translation computed on a cut which is not equipped with the unit-sphere metric? These are questions which need to be answered if one wants to calculate the Bondi-Sachs energy-momentum for a space-time which has been determined numerically. Under such conditions there is not much control over the presentation of I so that most of the available formulations of the Bondi energy-momentum simply do not apply. The purpose of this article is to provide the necessary background for a manifestly conformally invariant and gauge independent formulation of the Bondi energy-momentum. To this end we introduce a conformally invariant version of the GHP formalism to rephrase all the well-known formulae. This leads us to natural definitions for the space of asymptotic translations with its Lorentzian metric, for the Bondi news and the mass-aspect. A major role in these developments is played by the “co-curvature”, a naturally appearing quantity closely related to the Gauß curvature on a cut of I.

scholarly journals ADM MASS, BONDI MASS, AND ENERGY CONSERVATION IN TWO-DIMENSIONAL DILATON GRAVITIES

1996 ◽  
Vol 11 (03) ◽  
pp. 553-561 ◽  
Author(s):  
WON T. KIM ◽  
JULIAN LEE
Keyword(s):  
Boundary Condition ◽  
Energy Conservation ◽  
Radiation Energy ◽  
Two Dimensional ◽  
Dilaton Gravity ◽  
Null Infinity ◽  
Adm Mass ◽  
Stress Energy ◽  
Bondi Mass ◽  
Definition Of

We show how a stress-energy pseudotensor can be constructed in two-dimensional dilaton gravity theories (classical, CGHS and RST) and derive from it the expression for the ADM mass in these theories. We compare this expression with the ones in the literature obtained by other methods. We define the Bondi mass for these theories by using the pseudotensor formalism. The resulting expression is the generalization of the expression for the ADM mass. The boundary condition needed for the energy conservation is also investigated. It is shown that under appropriate boundary conditions, our definition of the Bondi mass is exactly the ADM mass minus the matter radiation energy at null infinity.

scholarly journals Null infinity as an open Hamiltonian system

2021 ◽  
Vol 2021 (4) ◽  
Author(s):  
Wolfgang Wieland
Keyword(s):  
Free Energy ◽  
Phase Space ◽  
Hamiltonian Formulation ◽  
Time Dependent ◽  
Null Infinity ◽  
Null Tetrad ◽  
Bondi Mass ◽  
New Interpretation ◽  
Background Fields ◽  
Bondi Energy

Abstract When a system emits gravitational radiation, the Bondi mass decreases. If the Bondi energy is Hamiltonian, it can thus only be a time-dependent Hamiltonian. In this paper, we show that the Bondi energy can be understood as a time-dependent Hamiltonian on the covariant phase space. Our derivation starts from the Hamiltonian formulation in domains with boundaries that are null. We introduce the most general boundary conditions on a generic such null boundary, and compute quasi-local charges for boosts, energy and angular momentum. Initially, these domains are at finite distance, such that there is a natural IR regulator. To remove the IR regulator, we introduce a double null foliation together with an adapted Newman-Penrose null tetrad. Both null directions are surface orthogonal. We study the falloff conditions for such specific null foliations and take the limit to null infinity. At null infinity, we recover the Bondi mass and the usual covariant phase space for the two radiative modes at the full non-perturbative level. Apart from technical results, the framework gives two important physical insights. First of all, it explains the physical significance of the corner term that is added in the Wald-Zoupas framework to render the quasi-conserved charges integrable. The term to be added is simply the derivative of the Hamiltonian with respect to the background fields that drive the time-dependence of the Hamiltonian. Secondly, we propose a new interpretation of the Bondi mass as the thermodynamical free energy of gravitational edge modes at future null infinity. The Bondi mass law is then simply the statement that the free energy always decreases on its way towards thermal equilibrium.

scholarly journals “I’ve Heard of It, Yes, but I Can’t Remember What Exactly It Was”—A Qualitative Study on Awareness, Knowledge, and Use of the UV Index

2021 ◽  
Vol 18 (4) ◽  
pp. 1615
Author(s):  
Katharina Diehl ◽  
Tatiana Görig ◽  
Charlotte Jansen ◽  
Maike Carola Hruby ◽  
Annette B. Pfahlberg ◽  
...  
Keyword(s):  
Qualitative Study ◽  
Qualitative Content Analysis ◽  
Sun Protection ◽  
Structured Interviews ◽  
Protection Factor ◽  
Protection Measures ◽  
Uv Index ◽  
Correct Definition ◽  
Definition Of

Pharmacists and pharmaceutical technicians play an important role in counselling customers regarding sunscreen use and sun protection measures. A potentially helpful tool that can be used during counselling is the ultraviolet index (UVI), which informs individuals when and what sun protection measures are needed at a specific place and time. Our aim in this qualitative study was to explore awareness, knowledge, and use of the UVI during counselling in pharmacies. We used semi-structured interviews with pharmacists and pharmaceutical technicians (n = 20) to answer our research questions. Interviews were audiotaped, transcribed verbatim, and analyzed using qualitative content analysis. During the interviews pharmacists and pharmaceutical technicians revealed a lot of uncertainty and lack of knowledge regarding the UVI. Eight professionals were able to give a correct definition of UVI. Amongst others, the UVI was confused with sun protection factor. Overall, the UVI was hardly used during the counselling of customers. The UVI was developed to provide guidance when which type of sun protection is required to avoid detrimental effects of ultraviolet radiation. For effective implementation, both the general population and health professionals (e.g., pharmacists) have to increase their knowledge about the UVI. This would strengthen its use during professional counselling in pharmacies and may help to reduce the incidence of skin cancer over the long term.

Infodemic surrounding COVID-19: Can LIS students recognize and categorize “problematic information” types on social media?

2021 ◽  
Vol ahead-of-print (ahead-of-print) ◽  
Author(s):  
Shamima Yesmin ◽  
S.M. Zabed Ahmed
Keyword(s):  
Social Media ◽  
Online Survey ◽  
Information Science ◽  
Wrong Answer ◽  
Student Groups ◽  
Content Type ◽  
Correct Definition ◽  
Significant Difference ◽  
Definition Of ◽  
And Task

Purpose The purpose of this paper is to investigate Library and Information Science (LIS) students’ understanding of infodemic and related terminologies and their ability to categorize COVID-19-related problematic information types using examples from social media platforms. Design/methodology/approach The participants of this study were LIS students from a public-funded university located at the south coast of Bangladesh. An online survey was conducted which, in addition to demographic and study information, asked students to identify the correct definition of infodemic and related terminologies and to categorize the COVID-related problematic social media posts based on their inherent problem characteristics. The correct answer for each definition and task question was assigned a score of “1”, whereas the wrong answer was coded as “0”. The percentages of correctness score for total and each category of definition and task-specific questions were computed. The independent sample t-test and ANOVA were run to examine the differences in total and category-specific scores between student groups. Findings The findings revealed that students’ knowledge concerning the definition of infodemic and related terminologies and the categorization of COVID-19-related problematic social media posts was poor. There was no significant difference in correctness scores between student groups in terms of gender, age and study levels. Originality/value To the best of the authors’ knowledge, this is the first time an effort was made to understand LIS students’ recognition and classification of problematic information. The findings can assist LIS departments in revising and improving the existing information literacy curriculum for students.

scholarly journals Estimation of the return period of rockfalls according to the block size

2016 ◽  
Author(s):  
Valerio De Biagi ◽  
Maria Lia Napoli ◽  
Monica Barbero ◽  
Daniele Peila
Keyword(s):  
Return Period ◽  
Statistical Approach ◽  
Historical Data ◽  
Risk Estimation ◽  
Block Size ◽  
Return Time ◽  
Correct Definition ◽  
Protection Devices ◽  
Definition Of ◽  
Rockfall Protection

Abstract. With reference to the rockfall risk estimation and the planning of rockfall protection devices one of the most critical and most discussed problems is the correct definition of the design block taking into account its return period. In this paper, a methodology for the assessment of the design block linked with its return time is proposed and discussed, following a statistical approach. The procedure is based on the survey of the blocks already detached from the slope and accumulated at the foot of the slope and the available historical data.

scholarly journals Signs of the concept of „conflict of interest” in the judicial practice of Ukraine

2021 ◽  
pp. 56-60
Author(s):  
Zoia Zahynei-Zabolotenko ◽  
◽  
Pavlo Demiak ◽  
Keyword(s):  
Supreme Court ◽  
Conflict Of Interest ◽  
Private Interest ◽  
Judicial Practice ◽  
Government Functions ◽  
Correct Definition ◽  
Definition Of ◽  
Administrative Responsibility

This article is about the problem of understanding the concept „conflict of interest” and its characteristics in the legal positions of Administrative Court of Cassation as a part of Supreme Court of Ukraine. From the article we can understand that these legal positions touch the correct definition of characteristics of private interest, potential and real conflict of interest, finding out people who are subordinated to a person who is authorized to perform state or local self-government functions, and it can causes potential or real conflict of interest. These legal positions can be used in bringing the guilty persons to administrative responsibility under the Code of Administrative Offenses.

scholarly journals Land dispute as an object of arbitration process

2021 ◽  
Vol 39 (3) ◽  
pp. 118-122
Author(s):  
M. A. Magomedova ◽  
Keyword(s):  
Russian Federation ◽  
Structural Elements ◽  
Legal Concept ◽  
Land Dispute ◽  
Correct Definition ◽  
Arbitration Process ◽  
The Subject ◽  
The Russian Federation ◽  
Characteristic Features ◽  
Definition Of

In the current legislation of the Russian Federation, there is no concept of a land dispute, which causes difficulties in determining the competence of an arbitration court in cases in which the object of the dispute is land. The article analyzes the general legal concept of a dispute and the sectoral concept of a land dispute developed by scientists. The author identified the characteristic features of a land dispute and its structural elements. The work reveals the influence of the structural elements of the land dispute on the type of production in which the dispute will be considered. In addition, the author concludes that the correct definition of the structural elements of the land dispute enables the arbitration court to determine the appropriate persons participating in the case, the subject of proof, the relevance and admissibility of evidence, and ultimately make a lawful and wellgrounded court decision.

scholarly journals Assessment of physicians’ and medical majors’ knowledge of asthma basics: Current results of the ASSA-II study

2019 ◽  
Vol 5 (2) ◽  
pp. 79-88
Author(s):  
Roman A. Bontsevich ◽  
Alina V. Mikhno ◽  
Oksana V. Dudchenko ◽  
Galina A. Batisheva ◽  
Galina G. Prozorova ◽  
...  
Keyword(s):  
Medical Students ◽  
Continuous Improvement ◽  
Clinical Picture ◽  
Basic Knowledge ◽  
Economic Damage ◽  
Asthma Therapy ◽  
Delivery Device ◽  
Laboratory Markers ◽  
Correct Definition ◽  
Definition Of

Introduction: Bronchial asthma is a disease characterized by chronic inflammation of the airways. At present, about 235-300 million people suffer from asthma, and this number continues to grow. This pathology is also common in children. It causes significant social and economic damage worldwide. Severe forms of asthma are difficult to treat. Thus, a continuous improvement of doctors’ knowledge in this field is of great importance. Methods: The analysis of an anonymous survey of physicians and senior medical students was used in the research. Results: The study revealed both an average level of basic knowledge in asthma etiology and pathogenesis among the physicians and senior medical students and the significant differences in their knowledge regarding clinical picture and treatment of asthma. Only 49.2% of students and 56.0% of doctors were able to choose the correct definition of asthma from the suggested answers; 65.7% of students and 69.9% of doctors correctly indicated the main clinical and laboratory markers of asthma; 60.2% of students and 91.0% of doctors determined the correct combination of drugs in one delivery device; and 75.9% of students and 91.2% of doctors selected the correct basic asthma therapy depending on the severity. Conclusion: Basing on the results obtained it was recommended to introduce additional educational activities on the diagnosis and therapy of asthma among medical majors and physicians.

scholarly journals Distant Psychological Violence: Prospects for Improvement of Criminal Legislation

2021 ◽  
Vol 11 (4) ◽  
pp. 64-76
Author(s):  
I.N. Mosechkin
Keyword(s):  
Cyber Bullying ◽  
Legal Issues ◽  
Psychological Violence ◽  
The Public ◽  
Cyber Harassment ◽  
Correct Definition ◽  
Foreign Law ◽  
Comparative Review ◽  
Definition Of ◽  
Criminal Legislation

The article researches the legal issues of protection from various forms of distant psychological violence arising in electronic communication. The study aims to assess the public danger of cyber-bullying, cyber-stalking and cyber-harassment among potential and real victims in order to develop recommendations for improvement of domestic legislature. The main results of the study have been obtained by surveying 207 individuals and by means of comparative review of domestic and foreign law. The results indicate that distant violence does take place, but its assessment by legislators and the public is highly controversial. Cyber-harassment is commonly seen as a more dangerous phenomenon than cyber-bullying or cyber-stalking, which raises a question of its criminalization in the law. This necessitates a correct definition of sexual harassment in distant form as there are risks of either intruding into the field of socially acceptable behavior or overlooking the socially unacceptable ones.

scholarly journals The grounds for initiation of service-related objects of patent law in the system of the MIA of Russia

2021 ◽  
Vol 2021 (3) ◽  
pp. 44-51
Author(s):  
Aleksandr Molchanov ◽  
Elizaveta Zaytseva
Keyword(s):  
Industrial Design ◽  
Patent Law ◽  
Controversial Issues ◽  
Utility Model ◽  
Legal Regime ◽  
Legal Norms ◽  
Correct Definition ◽  
Internal Affairs ◽  
The Moment ◽  
Definition Of

The article is devoted to the study of the grounds for initiation of service-related objects of patent law in the system of the Ministry of the Internal Affairs of Russia. The authors define the conditions necessary for the recognition of the service-related character of an invention, utility model, or industrial design. This is especially important for the correct definition of the legal regime of the created results and the application of legal consequences to the relations arising between the subjects. The purpose of the work is to analyse the grounds for initiation of service-related objects in the system of the Ministry of the Internal Affairs of Russia. As a result of the study, the legal relationships between the subjects of patent law in the system of the Ministry of the Internal Affairs of Russia, the grounds for their occurrence and the specifics are analysed, the question of the relationships between the moment of creation of the service-related product and the period of validity of the working contract between the author and the employer are determined, the procedure of distributing intellectual rights to service-related products, including those created as a result of the joint creative activity of several persons are clarified, other conditions and criteria for vesting an invention, utility model, industrial design with a service-related character are determined. As a separate basis, a civil law contract is highlighted, which has essential importance in the implementation of service-related objects of patent law in the system of the Ministry of the Internal Affairs of Russia. The analysis of legal norms revealed the lack of the legally fixed list of the grounds for the initiation of service-related objects of patent law, and therefore a number of controversial issues arising in practice require additional clarification.

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