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Topic Review
Role of Gamma Ray Pulsars for MACE Telescope
Rapidly rotating neutron stars with very strong surface magnetic fields are observed to emit pulsed emission in the whole range of electromagnetic spectrum from radio to high-energy gamma rays. These so-called pulsars are known for their exceptional rotational stability. The radio emission from pulsars is generally believed to be powered by the rotational energy of neutron stars. More than 3000 pulsars have been currently known from radio observations; however, only about 10% are observed in the high-energy gamma ray band. The Fermi-LAT observations in the energy range above 100 MeV have discovered more than 300 pulsars. However, the origin of high-energy non-thermal radiation from pulsars is not completely understood and remains an active area of research. Researchers report a summary of observational features of the gamma ray pulsars and briefly discuss observability for the MACE gamma ray telescope, which has just started its regular science operation at Hanle in India. Six gamma ray pulsars, other than the well-known Crab and Geminga, are identified as probable candidates for MACE observations.
  • 285
  • 24 Aug 2023
Biography
Robert Spencer Stone
Robert Spencer Stone (5 June 1895 – 18 December 1966) was a Canadian American and pioneer in radiology, radiation therapy and radiation protection.[1] Robert Spencer Stone, M.D., LLD was born in Chatham, Kent County, Ontario the son of Spencer ‘Pen’ Stone and Flora Maude Campbell. The Pen Stone family consisted of children Robert, Thomas, John, and Elizabeth. R.S. Stone married Wilhemin
  • 420
  • 08 Dec 2022
Biography
Robert K. Logan
Robert K. Logan (born August 31, 1939), originally trained as a physicist, is a media ecologist. He received from MIT a BS in 1961 and a PhD in 1965 under the supervision of Francis E. Low. After two post-doctoral appointments as a Research Associate at the University of Illinois at Urbana-Champaign (1965-7) and the University of Toronto (1967-8), he became a physics professor in 1968 at Toro
  • 369
  • 27 Dec 2022
Biography
Robert Griffiths
Robert B. Griffiths (February 25, 1937) is an American physicist at Carnegie Mellon University. He is the originator of the consistent histories approach to quantum mechanics, which has since been developed by himself, Roland Omnès, Murray Gell-Mann, and James Hartle. Robert B. Griffiths was born in Etah, Uttar Pradesh in 1937 to Presbyterian missionaries. Griffiths attended Woodstock School
  • 549
  • 29 Dec 2022
Biography
Robert Bruce Lindsay
Robert Bruce Lindsay (1 January 1900 – 2 March 1985) was an United States physicist and physics professor, known for his prolific authorship of physics books in acoustics, and historical and philosophical analyses of physics.[1][2] R(obert) Bruce Lindsay's January 1, 1900 birth date hailed a new century. At the age of 20, he received both a BA and an MS in physics from Brown University. Bef
  • 563
  • 26 Dec 2022
Topic Review
Rigidity Theory
Rigidity theory, or topological constraint theory, is a tool for predicting properties of complex networks (such as glasses) based on their composition. It was introduced by James Charles Phillips in 1979 and 1981, and refined by Michael Thorpe in 1983. Inspired by the study of the stability of mechanical trusses as pioneered by James Clerk Maxwell, and by the seminal work on glass structure done by William Houlder Zachariasen, this theory reduces complex molecular networks to nodes (atoms, molecules, proteins, etc.) constrained by rods (chemical constraints), thus filtering out microscopic details that ultimately don't affect macroscopic properties. An equivalent theory was developed by P.K. Gupta A.R. Cooper in 1990, where rather than nodes representing atoms, they represented unit polytopes. An example of this would be the SiO tetrahedra in pure glassy silica. This style of analysis has applications in biology and chemistry, such as understanding adaptability in protein-protein interaction networks. Rigidity theory applied to the molecular networks arising from phenotypical expression of certain diseases may provide insights regarding their structure and function. In molecular networks, atoms can be constrained by radial 2-body bond-stretching constraints, which keep interatomic distances fixed, and angular 3-body bond-bending constraints, which keep angles fixed around their average values. As stated by Maxwell's criterion, a mechanical truss is isostatic when the number of constraints equals the number of degrees of freedom of the nodes. In this case, the truss is optimally constrained, being rigid but free of stress. This criterion has been applied by Phillips to molecular networks, which are called flexible, stressed-rigid or isostatic when the number of constraints per atoms is respectively lower, higher or equal to 3, the number of degrees of freedom per atom in a three-dimensional system. The same condition applies to random packing of spheres, which are isostatic at the jamming point. Typically, the conditions for glass formation will be optimal if the network is isostatic, which is for example the case for pure silica. Flexible systems show internal degrees of freedom, called floppy modes, whereas stressed-rigid ones are complexity locked by the high number of constraints and tend to crystallize instead of forming glass during a quick quenching.
  • 361
  • 09 Oct 2022
Topic Review
Rigid Templates for Fabricating 3D Nanostructures
Rigid templates are defined as opposed to soft templates, and are made of hard materials. Rigid templates have good chemical stability and mechanical rigidity, which are mostly used for the fabrication of nanostructure arrays. A wide choice of rigid templates is available, such as silicon, anodic aluminum oxide, carbon, silica spheres, biological structures, and so forth.
  • 844
  • 14 Jun 2022
Topic Review
Riemannian Metric and Lie Bracket in Computational Anatomy
Computational anatomy (CA) is the study of shape and form in medical imaging. The study of deformable shapes in computational anatomy rely on high-dimensional diffeomorphism groups [math]\displaystyle{ \varphi \in \operatorname{Diff}_V }[/math] which generate orbits of the form [math]\displaystyle{ \mathcal{M} \doteq \{ \varphi \cdot m \mid \varphi \in \operatorname{Diff}_V \} }[/math]. In CA, this orbit is in general considered a smooth Riemannian manifold since at every point of the manifold [math]\displaystyle{ m \in \mathcal{M} }[/math] there is an inner product inducing the norm [math]\displaystyle{ \| \cdot \|_m }[/math] on the tangent space that varies smoothly from point to point in the manifold of shapes [math]\displaystyle{ m \in \mathcal{M} }[/math]. This is generated by viewing the group of diffeomorphisms [math]\displaystyle{ \varphi \in \operatorname{Diff}_V }[/math] as a Riemannian manifold with [math]\displaystyle{ \| \cdot \|_\varphi }[/math], associated to the tangent space at [math]\displaystyle{ \varphi \in\operatorname{Diff}_V }[/math] . This induces the norm and metric on the orbit [math]\displaystyle{ m \in \mathcal{M} }[/math] under the action from the group of diffeomorphisms.
  • 447
  • 25 Oct 2022
Biography
Richard Garwin
Richard Lawrence Garwin (born April 19, 1928) is an United States physicist, widely known to be the author of the first hydrogen bomb design.[1][2] Garwin received his bachelor's degree from the Case Institute of Technology in 1947, and two years later his Ph.D. from the University of Chicago under the supervision of Enrico Fermi at the age of 21. Another of Fermi's students, Marvin L. Goldbe
  • 530
  • 25 Nov 2022
Biography
Richard Gaitskell
Richard Jeremy Gaitskell (born May 2, 1965) is a physicist and professor at Brown University, and a leading scientist in the search for particle dark matter.[1] He is co-founder, a principal investigator, and co-spokesperson of the Large Underground Xenon (LUX) experiment, which announced world-leading[2][3] first results on October 30, 2013. He is also a leading investigator in the new LUX-Zepl
  • 425
  • 09 Dec 2022
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