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Topic Review
VSOP (Planets)
The semi-analytic planetary theory VSOP (French: Variations Séculaires des Orbites Planétaires) is a mathematical model describing long-term changes (secular variation) in the orbits of the planets Mercury to Neptune. The earliest modern scientific model considered only the gravitational attraction between the Sun and each planet, with the resulting orbits being unvarying Keplerian ellipses. In reality, all the planets exert slight forces on each other, causing slow changes in the shape and orientation of these ellipses. Increasingly complex analytical models have been made of these deviations, as well as efficient and accurate numerical approximation methods. VSOP was developed and is maintained (updated with the latest data) by the scientists at the Bureau des Longitudes in Paris. The first version, VSOP82, computed only the orbital elements at any moment. An updated version, VSOP87, computed the positions of the planets directly at any moment, as well as their orbital elements with improved accuracy. At present, the difference between computational predictions and observations is so small that the model seems essentially complete in its physical principles. Such hypothetical deviations are often referred to as post-Keplerian effects.
  • 506
  • 28 Nov 2022
Biography
Erich Kretschmann
Erich Justus Kretschmann (14 July 1887 – 1973) was a Germany physicist.[1] Kretschmann was born in Berlin. He obtained his PhD at Berlin University in 1914 with his dissertation entitled "Eine Theorie der Schwerkraft im Rahmen der ursprünglichen Einsteinschen Relativitätstheorie"[2] (A theory of gravity in the framework of the original Einstein theory of relativity). His advisors were Max
  • 505
  • 08 Dec 2022
Topic Review
Types of Compton Cameras
A Compton camera is a promising γ-ray detector that operates in the wide energy range of a few tens of keV to MeV. The γ-ray detection method of a Compton camera is based on Compton scattering kinematics, which is used to determine the direction and energy of the γ-rays without using a mechanical collimator. Although the Compton camera was originally designed for astrophysical applications, it was later applied in medical imaging as well. Moreover, its application in environmental radiation measurements is also under study.
  • 505
  • 18 Oct 2022
Topic Review
Polymer-Based Sensors
Due to the wide application of wearable electronic devices in daily life, research into flexible electronics has become very attractive. Various polymer-based sensors have emerged with great sensing performance and excellent extensibility. It is well known that different structural designs each confer their own unique, great impacts on the properties of materials. For polymer-based pressure/strain sensors, different structural designs determine different response-sensing mechanisms, thus showing their unique advantages and characteristics. 
  • 505
  • 23 Feb 2023
Topic Review
Multiphysics Data for Mineral Exploration
Different geophysical methods provide information about various physical properties of rock formations and mineralization. In many cases, this information is mutually complementary. At the same time, inversion of the data for a particular survey is subject to considerable uncertainty and ambiguity as to causative body geometry and intrinsic physical property contrast. One productive approach to reducing uncertainty is to jointly invert several types of data. Non-uniqueness can also be reduced by incorporating additional information derived from available geological and/or geophysical data in the survey area to reduce the searching space for the solution. This additional information can be incorporated in the form of a joint inversion of multiphysics data. 
  • 503
  • 13 Jul 2021
Topic Review
Canis Major
Canis Major, Latin for "Greater Dog," is one of the most prominent constellations in the southern celestial hemisphere. Often depicted as one of Orion's hunting dogs in Greek mythology, Canis Major is best known for its brightest star, Sirius, also called the Dog Star, which is the brightest star in the night sky. With its distinctive shape and rich cultural significance, Canis Major has fascinated astronomers and storytellers throughout history.
  • 503
  • 29 Feb 2024
Biography
Carl Eckart
Carl Henry Eckart (May 4, 1902 in St. Louis, Missouri – October 23, 1973 in La Jolla, California ) was an United States physicist, physical oceanographer, geophysicist, and administrator. He co-developed the Wigner–Eckart theorem and is also known for the Eckart conditions in quantum mechanics,[1] and the Eckart–Young theorem in linear algebra.[2] Eckart began college in 1919 at Washing
  • 503
  • 14 Dec 2022
Biography
Karl Wirtz
Karl Eugen Julius Wirtz (24 April 1910 – 12 February 1994) was a German nuclear physicist, born in Cologne. He was arrested by the allied British and American Armed Forces and incarcerated at Farm Hall for six months in 1945 under Operation Epsilon. From 1929 to 1934, Wirtz studied physics, chemistry, and mathematics at the University of Bonn, the Albert Ludwigs University of Freiburg, and
  • 502
  • 08 Dec 2022
Biography
Yuri Raizer
Yuri Raizer was born in 1927 in Kharkov, Ukraine. He graduated from the Leningrad Polytechnic Institute in 1949, and became Doctor of Sciences (Physics and Mathematics) in 1959, full professor in 1968, and Honored Scientist of the Russian Federation in 2002. He was a chief researcher at the Institute for Problems in Mechanics of the Russian Academy of Sciences, and Honored Professor of the Mosco
  • 501
  • 29 Aug 2022
Topic Review
Radiography of Cultural Objects
The radiography of cultural objects is the use of radiography to understand intrinsic details about objects. Most commonly this involves X-rays of paintings to reveal underdrawing, pentimenti alterations in the course of painting or by later restorers, and sometimes previous paintings on the support. Many pigments such as lead white show well in radiographs. X-ray spectromicroscopy has also been used to analyse the reactions of pigments in paintings. For example, in analysing colour degradation in the paintings of van Gogh. These processes can reveal various details about objects that are not visible to the naked eye. This information, which includes structural elements, aids conservators as they assess object condition and consider treatment plans. For three dimensional objects, the computed tomography (CT) has become a common tool, which when combined with analysis can, for example, "digitally unroll" or unfold and make possible the reading of fragile scrolls, books, or sealed correspondence.
  • 501
  • 10 Oct 2022
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