scholarly journals Projectively Invariant Equations of Gravitation

2020 ◽  
Author(s):  
Leonid Verozub
Keyword(s):  
Gravitational Field ◽  
Mass Energy ◽  
Physical Consequences ◽  
Correct Expression

The paper considers the physical consequences of bimetric geodesically (pro jectively) invariant equations of gravitation. The correct expression for the energy- impulse tensor of the gravitational field is obtained and with its help the key role of the gravitational defect of mass-energy for the energy of the newborn universe is shown..

SPACE–TIME ENERGY–MOMENTUM, THE OBSERVER AND UNCERTAINTY IN GENERAL RELATIVITY

2010 ◽  
Vol 19 (14) ◽  
pp. 2353-2359 ◽  
Author(s):  
F. I. COOPERSTOCK ◽  
M. J. DUPRE
Keyword(s):  
General Relativity ◽  
Gravitational Field ◽  
Uncertainty Principle ◽  
Ricci Tensor ◽  
Space Time ◽  
Energy Integral ◽  
New Approach ◽  
Extended Space ◽  
Energy And Momentum

In this essay, we introduce a new approach to energy–momentum in general relativity. Space–time, as opposed to space, is recognized as the necessary arena for its examination, leading us to define new extended space–time energy and momentum constructs. From local and global considerations, we conclude that the Ricci tensor is the required element for a localized expression of energy–momentum to include the gravitational field. We present and rationalize a fully invariant extended expression for space–time energy, guided by Tolman's well-known energy integral for an arbitrary bounded stationary system. This raises fundamental issues which we discuss. The role of the observer emerges naturally and we are led to an extension of the uncertainty principle to general relativity, of particular relevance to ultra-strong gravity.

scholarly journals PARAMETRIC NONHOLONOMIC FRAME TRANSFORMS AND EXACT SOLUTIONS IN GRAVITY

2007 ◽  
Vol 04 (08) ◽  
pp. 1285-1334 ◽  
Author(s):  
SERGIU I. VACARU
Keyword(s):  
Gravitational Field ◽  
Exact Solutions ◽  
General Scheme ◽  
Nonlinear Partial Differential Equations ◽  
Killing Vector ◽  
Field Equations ◽  
Finsler Spaces ◽  
Gravitational Field Equations ◽  
Pp Wave ◽  
Physical Consequences

A generalized geometric method is developed for constructing exact solutions of gravitational field equations in Einstein theory and generalizations. First, we apply the formalism of nonholonomic frame deformations (formally considered for nonholonomic manifolds and Finsler spaces) when the gravitational field equations transform into systems of nonlinear partial differential equations which can be integrated in general form. The new classes of solutions are defined by generic off-diagonal metrics depending on integration functions on one, two and three (or three and four) variables if we consider four (or five) dimensional spacetimes. Second, we use a general scheme when one (two) parameter families of exact solutions are defined by any source-free solutions of Einstein's equations with one (two) Killing vector field(s). A successive iteration procedure results in new classes of solutions characterized by an infinite number of parameters for a non-Abelian group involving arbitrary functions on one variable. Five classes of exact off-diagonal solutions are constructed in vacuum Einstein and in string gravity describing solitonic pp-wave interactions. We explore possible physical consequences of such solutions derived from primary Schwarzschild or pp-wave metrics.

scholarly journals The Role of Non-tidal Atmospheric Loading in the Task of Gravity Field Estimation by Inter-Satellite Measurements

2021 ◽  
Author(s):  
I. O. Skakun ◽  
V. V. Mitrikas ◽  
V. V. Ianishevskii
Keyword(s):  
Gravitational Field ◽  
Gravity Field ◽  
Satellite Measurements ◽  
Atmospheric Loading ◽  
Field Estimation ◽  
Tidal Variations ◽  
Grace Mission ◽  
Monthly Variations ◽  
Water Height

AbstractThe paper reviews models of tidal and non-tidal variations of the Earth's gravitational field. Proposing an algorithm for the estimation of the Stokes coefficients based on inter-satellite measurements of low-orbit spacecrafts. By processing measurements of the GRACE mission, we obtained experimental estimates of gravity field monthly variations. The analysis of these values was carried out by calculating the change in the equivalent water height for a given area.

scholarly journals LANGUAGE CLICHÉS IN THE METHODOLOGY OF TEACHING RUSSIAN AS A FOREIGN LANGUAGE

2021 ◽  
Vol 10 (34) ◽  
Author(s):  
S.V PETROV ◽  
Keyword(s):  
Foreign Language ◽  
Foreign Students ◽  
Foreign Languages ◽  
Linguistic Terms ◽  
Correct Expression ◽  
Practice Of Teaching

The purpose of this study is to determine the role of language clichés in the practice of teaching foreign languages and, in particular, Russian as a foreign language. In the course of the study, the relevant features of language clichés were identified, including those that distinguish them from phraseological units; the classification of language clichés by the functions of language expressions is made; and the methodology for them in relation to a foreign audience is described. In addition, it was found that the use of clichés as the most stable reproducible linguistic terms in a foreign language, helps to avoid errors associated with the wrong lexical collocation, and also contributes to a more correct expression of thoughts for a given language which in turn makes the communication more effective and responsive to the communicative tasks of its participants. In this regard, language clichés should be paid a special attention, both by researchers and teachers, in this case working with foreigners. It should be kept in mind that there might be no such fixed phrases in the language of foreign students, or they can have a different structure, which means that in many times students cannot independently recognize and purposefully memorize such units; that is why all the necessary semantic work with such language clichés should be carried out in class.

scholarly journals Role of the esc+ gene product in ensuring the selective expression of segment-specific homeotic genes in Drosophila

Development ◽  
1983 ◽  
Vol 76 (1) ◽  
pp. 297-331
Author(s):  
Gary Struhl
Keyword(s):  
Gene Product ◽  
The Body ◽  
Homeotic Genes ◽  
Bithorax Complex ◽  
Sex Combs Reduced ◽  
Sex Combs ◽  
Correct Determination ◽  
Correct Expression

The product of the extra sex combs+ (esc+) gene is required during embryogenesis for the correct determination of segments in Drosophila. If this product is absent, most segments develop like the normal eighth abdominal segment. Here, I extend previous results (Struhl, 1981a) showing that this phenotype results in large part from indiscriminate expression of the bithorax-complex genes which are normally active only in particular segments of the thorax and abdomen. In addition, I test whether the esc+ gene product is required for the correct expression of other homeotic genes. First, I have examined two genes of the Antennapedia-complex (Sex combs reduced+ and Antennapedia+): I find that both genes are normally required in only some of the body segments, but that in the absence of the esc+ gene product, both appear to function adventitiously in other segments. Second, comparing esc+ and esc− embryos lacking both these genes as well as the bithorax-complex, I find that additional homeotic genes (possibly those normally involved in specifying head segments) appear to be expressed indiscriminately when the esc+ gene product is absent. Finally, I present evidence that the products of the esc+ gene and the Polycomb+ gene (a second gene required for the correct regulation of the bithorax-complex) act independently. On the basis of these results, I propose a tentative outline of the roles and realms of action of all of these genes.

scholarly journals Role of Psychological and Social Security in Predicting Depression Among Women Living in the Homeless Shelters of Tehran

2020 ◽  
Vol 6 (4) ◽  
pp. 213-222
Author(s):  
Afsaneh Khadivi-Zand ◽  
◽  
Anahita Khodabakhshi-Koolaee ◽  
Mohammad Reza Falsafinejad ◽  
◽  
...  
Keyword(s):  
Social Security ◽  
Mental Health Professionals ◽  
Negative Relationship ◽  
Homeless People ◽  
Psychiatric Nurses ◽  
Homeless Shelters ◽  
Cluster Sampling ◽  
Research Population ◽  
Physical Consequences

Background: Homelessness is a common phenomenon in all human societies and leads to many social, psychological, and physical consequences for the homeless people and society. This study aimed to determine the role of psychological and social security in predicting depression among women living in the homeless shelters of Tehran. Methods: It was a descriptive correlational study. The research population included all women living in the homeless shelters of Tehran, in 2020. The subjects were selected using random, multistage cluster sampling. Two homeless shelters were selected. The final sample included 150 women. The data were collected using the security-insecurity inventory and the Beck depression inventory. The collected data were analyzed using the multiple regression analysis in SPSS V. 22. Results: The results showed that the feeling of psychological security predicts depression in women (R=0.48). Also, 23% of the variances in depression were explained by psychological security. Therefore, psychological security can predict depression (with 99% confidence) in these women. Moreover, the feeling of social security can predict the rate of depression in women (MR=-0.55). This implies that approximately 30% of the variances of depression can be explained by social security. The beta coefficient for social security was -0.55. Accordingly, social security can predict depression (with 99% confidence) in women living in homeless shelters. The negative signs of the beta coefficients indicated a negative relationship between the predictor and the criterion variables. In other words, the higher the psychological and social security, the lower the rate of depression in women. Conclusion: This study showed that the psychological and social security levels of these women were correlated with the degree of depression experienced. Using the insights from this study, counselors, psychiatric nurses, and other mental health professionals are suggested to create a friendly and safe environment for clients to express their feelings and lessen their depression.

The Annotated Manuscript

2017 ◽  
Author(s):  
Hanoch Gutfreund ◽  
Jürgen Renn
Keyword(s):  
Gravitational Field ◽  
General Theory ◽  
Equations Of Motion ◽  
Special Theory ◽  
Material Point ◽  
Theory Of Relativity ◽  
General Theory Of Relativity ◽  
Field Equations ◽  
Theory Of Gravitation

This section presents annotations of the manuscript of Albert Einstein's canonical 1916 paper on the general theory of relativity. It begins with a discussion of the foundation of the general theory of relativity, taking into account Einstein's fundamental considerations on the postulate of relativity, and more specifically why he went beyond the special theory of relativity. It then considers the spacetime continuum, explaining the role of coordinates in the new theory of gravitation. It also describes tensors of the second and higher ranks, multiplication of tensors, the equation of the geodetic line, the formation of tensors by differentiation, equations of motion of a material point in the gravitational field, the general form of the field equations of gravitation, and the laws of conservation in the general case. Finally, the behavior of rods and clocks in the static gravitational field is examined.

scholarly journals Gravitating Disks Around Black Holes

2009 ◽  
Vol 5 (S267) ◽  
pp. 332-332
Author(s):  
Vladimír Karas ◽  
Ladislav Šubr
Keyword(s):  
Black Holes ◽  
Black Hole ◽  
Gravitational Field ◽  
Relativistic Effects ◽  
Einstein Equations ◽  
Axially Symmetric ◽  
Disk System ◽  
Massive Black Hole ◽  
Black Hole Binary

AbstractFluid disks and tori around black holes are discussed within different approaches and with the emphasis on the role of disk gravity. We first review the prospects for investigating the gravitational field of a black hole–disk system by analytical solutions of stationary, axially symmetric Einstein equations. More detailed considerations are focused on the middle and outer parts of extended disk-like configurations where relativistic effects are small and the Newtonian description is adequate. As an example, we investigate the case of a torus near a massive black hole that is a member of the black-hole binary system.

ON TOLMAN'S MASS-ENERGY RELATION AND A NEW TOLMAN-TYPE RELATION

1989 ◽  
Vol 04 (02) ◽  
pp. 327-334
Author(s):  
B. M. BARKER ◽  
R. F. O'CONNELL
Keyword(s):  
Gravitational Field ◽  
Coordinate System ◽  
Energy Relation ◽  
Mass Energy ◽  
Schwarzschild Solution ◽  
Metric Tensor ◽  
Harmonic Coordinates ◽  
Isotropic Coordinates ◽  
Special Cases ◽  
Type Relation

Tolman derived the mass-energy relation [Formula: see text] using a particular choice of coordinates, viz. the Schwarzschild solution for the metric tensor in isotropic coordinates for a body of mass m at rest at the origin. Here we show that this relation retains the same form for the case of a very general coordinate system. The latter includes the Schwarzschild and harmonic coordinates as special cases. In addition, we give a new Tolman-type relation [Formula: see text]. The quantities [Formula: see text] and [Formula: see text] are the energy-momentum densities for matter and the gravitational field, respectively.

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