scholarly journals Testing Gravitational Theories in the Field of the Earth with the SaToR-G Experiment

Universe ◽  
2021 ◽  
Vol 7 (6) ◽  
pp. 192
Author(s):  
David Lucchesi ◽  
Luciano Anselmo ◽  
Massimo Bassan ◽  
Marco Lucente ◽  
Carmelo Magnafico ◽  
...  
Keyword(s):  
General Relativity ◽  
State Of The Art ◽  
Current Knowledge ◽  
Slow Motion ◽  
Weak Field ◽  
New Physics ◽  
The State ◽  
The Earth ◽  
Gravitational Theories ◽  
Theories Of Gravitation

A new satellite-based experiment in the field of gravitation, SaToR-G, is presented. It aims to compare the predictions of different theories of gravitation in the limit of weak-field and slow-motion. The ultimate goal of SaToR-G is searching for possible “new physics” beyond General Relativity, which represent the state-of-the-art of our current knowledge of gravitational physics. A key role in the above perspective is the theoretical and experimental framework that confines our work. To this end, we will exploit as much as possible the classical framework suggested by R.H. Dicke over fifty years ago.

scholarly journals Is the diversity of the Beach Flies adequately known? Some notes on the state of the art of current knowledge (Diptera: Canacidae)

2015 ◽  
pp. 99-111
Author(s):  
Lorenzo Munari
Keyword(s):  
Bay Of Bengal ◽  
State Of The Art ◽  
Current Knowledge ◽  
Neotropical Region ◽  
West African ◽  
The State ◽  
South American ◽  
The West ◽  
Scientific Institutions ◽  
The World

An overview of the major zoogeographical gaps in our knowledge of the world beach flies (subfamilies Apetaeninae, Horaismopterinae, Pelomyiinae, and Tethininae) is provided. The identified areas treated in this work are as follows: the subarctic Beringia, the South American circum-Antarctic islands, the Neotropical Region south of the equator, most of the West African seacoasts, the huge area ranging from India, across the Bay of Bengal, to Sumatra and Java, and most of Australia. Apart from the inhospitable northernmost and southernmost areas of the planet, which feature a real very low biodiversity, the remaining vast areas dealt with in this work woefully suffer a dramatic paucity of field collections, as well as of previously collected materials preserved in scientific institutions. This might seem a truism that, however, must be emphasized in order to unequivocally identify the geographic areas that need to be further investigated

scholarly journals The State of the Art in Methodologies of Course Recommender Systems—A Review of Recent Research

Data ◽  
2021 ◽  
Vol 6 (2) ◽  
pp. 18
Author(s):  
Deepani B. Guruge ◽  
Rajan Kadel ◽  
Sharly J. Halder
Keyword(s):  
Recommender Systems ◽  
State Of The Art ◽  
Current Knowledge ◽  
Research Literature ◽  
The State ◽  
Knowledge Based ◽  
Emerging Trends ◽  
Wide Range ◽  
Research Findings ◽  
Research Outcome

In recent years, education institutions have offered a wide range of course selections with overlaps. This presents significant challenges to students in selecting successful courses that match their current knowledge and personal goals. Although many studies have been conducted on Recommender Systems (RS), a review of methodologies used in course RS is still insufficiently explored. To fill this literature gap, this paper presents the state of the art of methodologies used in course RS along with the summary of the types of data sources used to evaluate these techniques. This review aims to recognize emerging trends in course RS techniques in recent research literature to deliver insights for researchers for further investigation. We provide a systematic review process followed by research findings on the current methodologies implemented in different course RS in selected research journals such as: collaborative, content-based, knowledge-based, Data Mining (DM), hybrid, statistical and Conversational RS (CRS). This study analyzed publications between 2016 and June 2020, in three repositories; IEEE Xplore, ACM, and Google Scholar. These papers were explored and classified based on the methodology used in recommending courses. This review has revealed that there is a growing popularity in hybrid course RS and followed by DM techniques in recent publications. However, few CRS-based course RS were present in the selected publications. Finally, we discussed future avenues based on the research outcome, which might lead to next-generation course RS.

Palaeolithic Archaeology in the Mongolian People's Republic; A Report on the state of the art.

1984 ◽  
Vol 50 ◽  
pp. 23-34 ◽  
Author(s):  
Myra Shackley
Keyword(s):  
Late Pleistocene ◽  
State Of The Art ◽  
Current Knowledge ◽  
Northern China ◽  
The State ◽  
Short Paper ◽  
Middle Palaeolithic ◽  
Form Part ◽  
Palaeolithic Archaeology

This short paper summarizes current knowledge concerning the palaeolithic archaeology of the Mongolian People's Republic (‘Outer Mongolia’), although the paucity of well-documented assemblages and stratified sites makes it impossible to do more than comment on the nature of the material. A few early sites can be assigned to the Acheulean technocomplex and the Kazantsevo interglacial, but there is a more extensive group of surface middle palaeolithic assemblages in the Altai-Gobi area with close and dated typological parallels in northern China. At some of these localities, for example Arts Bogd in the southern Gobi, the first beginnings of the microblade tradition which characterizes the later Shabarakh complex of sites may be seen. These later sites, which form part of a remarkably uniform circumpolar epipalaeolithic dating to between 20–11,000 BP, are associated with the gradual Late Pleistocene desertification of the Gobi.

scholarly journals Analytic approximations in GR and gravitational waves

2019 ◽  
Vol 28 (06) ◽  
pp. 1930011 ◽  
Author(s):  
Luc Blanchet
Keyword(s):  
Binary Systems ◽  
State Of The Art ◽  
Equations Of Motion ◽  
Slow Motion ◽  
Weak Field ◽  
Analytic Approximation ◽  
Compact Binary ◽  
Recent Developments ◽  
Motion Approximation ◽  
Self Force

Analytic approximation methods in general relativity play a very important role when analyzing the gravitational wave signals recently discovered by the LIGO and Virgo detectors. In this contribution, we present the state of the art and some recent developments in the famous post-Newtonian (PN) or slow-motion approximation, which has successfully computed the equations of motion and the early inspiral phase of compact binary systems. We discuss also some interesting interfaces between the PN and the gravitational self-force (GSF) approach based on black-hole perturbation theory, and between PN and the post-Minkowskian (PM) approximation, namely a nonlinearity expansion valid for weak field and possibly fast-moving sources.

scholarly journals Probing Gravitational Theories with Eccentric Eclipsing Detached Binary Stars

2014 ◽  
Vol 1 (1) ◽  
pp. 255-258
Author(s):  
Leopoldo Milano ◽  
Rosario De Rosa ◽  
Mariafelicia De Laurentis ◽  
Fabio Garufi
Keyword(s):  
General Relativity ◽  
Binary Stars ◽  
Variance Analysis ◽  
Period Variation ◽  
Apsidal Motion ◽  
Gravitational Theories ◽  
Theories Of Gravitation

In this paper, we compare the effects of different theories of gravitation on the apsidal motion of eccentric eclipsing detached binary stars. The comparison is performed by using the formalism of the post-Newtonian parametrization to calculate the theoretical advance at periastron and compare it to the observed one, after having considered the effects of the structure and rotation of the involved stars. A variance analysis on the results of this comparison shows that no signicant difference can be found due to the effect of the different theories under test with respect to the standard general relativity (GR). It will be possible to observe differences, as we would expect, by checking the observed period variation on a much larger lapse of time.

scholarly journals Topical problems in the theory of planet formation: formation of planetesimals

2019 ◽  
pp. 104-121
Author(s):  
A. B. Makalkin ◽  
I. N. Ziglina ◽  
M. E. Artyushkova
Keyword(s):  
Planet Formation ◽  
State Of The Art ◽  
The State ◽  
Special Focus ◽  
Formation Theory ◽  
History Of Development ◽  
The Earth ◽  
History Of ◽  
Academy Of Sciences ◽  
Schmidt Institute

The development of the Earth’s and planets formation theory over 70 years is considered with a special focus on the history of development of this theory at the Schmidt Institute of Physics of the Earth of the Russian Academy of Sciences (IPE RAS) where this direction of research was founded by Otto Schmidt. The state of the art of the theory is outlined. In particular, the planetesimals formation problem currently belonging to the key unsolved issues in the theory of planet formation is discussed. Recent results of the studies aimed at solving this problem at IPE RAS are presented.

scholarly journals PHENOMENOLOGICAL CONSTRAINTS ON THE KEHAGIAS–SFETSOS SOLUTION IN THE HOŘAVA–LIFSHITZ GRAVITY FROM SOLAR SYSTEM ORBITAL MOTIONS

2010 ◽  
Vol 25 (29) ◽  
pp. 5399-5408 ◽  
Author(s):  
L. IORIO ◽  
M. L. RUGGIERO
Keyword(s):  
General Relativity ◽  
Black Hole ◽  
Solar System ◽  
Slow Motion ◽  
Analytical Form ◽  
Weak Field ◽  
Schwarzschild Black Hole ◽  
Anomalous Acceleration ◽  
Motion Approximation ◽  
General Relativistic

We focus on Hořava–Lifshitz (HL) theory of gravity, and, in particular, on the Kehagias and Sfetsos's solution that is the analog of Schwarzschild black hole of General Relativity. In the weak-field and slow-motion approximation, we analytically work out the secular precession of the longitude of the pericentre ϖ of a test particle induced by this solution. Its analytical form is different from that of the general relativistic Einstein's pericentre precession. Then, we compare it to the latest determinations of the corrections [Formula: see text] to the standard Newtonian/Einsteinian planetary perihelion precessions recently estimated by E. V. Pitjeva with the EPM2008 ephemerides. It turns out that the planets of the solar system, taken singularly one at a time, allow one to put lower bounds on the adimensional HL parameter ψ0 of the order of 10-12(Mercury)-10-24 (Pluto). They are not able to account for the Pioneer anomalous acceleration for r > 20 AU.

scholarly journals Long-term Earth Orientation Monitoring Using Various Techniques

2000 ◽  
Vol 178 ◽  
pp. 337-344
Author(s):  
D. Gambis
Keyword(s):  
Polar Motion ◽  
State Of The Art ◽  
The State ◽  
Central Bureau ◽  
Earth Orientation ◽  
The Earth ◽  
Individual Contributions ◽  
Composite Series

AbstractA continuous composite series of polar motion components extending from 1846 until now called EOP (IERS) C01 is available at the Earth Orientation Section of the Central Bureau of the IERS. This series is the basis of the IERS system. It relies on different series derived from optical astrometry until 1972 and geodetic techniques since. It is given at 0.1 year intervals (1846–1889) and 0.05 year intervals (1890-now). Its accuracy has dramatically improved from 100 mas in 1846 to about 0.2 mas at present.Now the IERS combined solutions involve mainly the contributions of VLBI, GPS and SLR techniques. It is regularly recomputed to take advantage of the improvement of the various recent individual contributions and of the refinement of the analyses procedures.The objective of this paper is to describe this long-term polar motion series and to present the evolution and the state of the art of the multi-technique EOP combined solutions and the predictions regularly computed at the IERS/CB.

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