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Topic Review
Metastable Inner-Shell Molecular State
Metastable Innershell Molecular State (MIMS) is a class of ultra-high-energy short-lived molecules have the binding energy up to 1,000 times larger and bond length up to 100 times smaller than typical molecules. MIMS is formed by inner-shell electrons that are normally resistant to molecular formation. However, in stellar conditions, the inner-shell electrons become reactive to form molecular structures (MIMS) from combinations of all elements in the periodic table. MIMS upon dissociation can emit x-ray photons with energies up to 100 keV at extremely high conversion efficiencies from compression energy to photon energy. MIMS is predicted to exist and dominate radiation processes in extreme astrophysical environments, such as large planet cores, star interiors, and black hole and neutron star surroundings. There, MIMS is predicted to enable highly energy-efficient transformation of the stellar compression energy into the radiation energy. The right schematic illustration shows the proposed four stages of the K-shell MIMS (K-MIMS) formation and x-ray generation process. Stage I: Individual atoms are subjected to the stellar compression and ready for absorbing the compression energy. Stage II: The outer electron shells fuse together under increasing "stellar" pressure. Stage III: At the peak pressure, via pressure ionization K-shell orbits form the K-MIMS, which is vibrationally hot and encapsulated by a Rydberg-like pseudo-L-Shell structure. Stage IV: The K-MIMS cools down by ionizing ("boiling-off") a number of pseudo-L-shell electrons and subsequent optical decay by emitting an x-ray photon. The dissociated atoms return their original atoms states and are ready for absorbing the compression energy. MIMS also can be readily produced in laboratory and industrial environments, such as hypervelocity particle impact, laser fusion and z-machine. MIMS can be exploited for highly energy-efficient production of high intensity x-ray beams for a wide range of innovative applications, such as photolithography, x-ray lasers, and inertial fusion.
  • 658
  • 18 Oct 2022
Topic Review
Astrophotonic Spectrographs
Astrophotonics is the application of photonic technologies to channel, manipulate, and disperse light from one or more telescopes to achieve scientific objectives in astronomy in an efficient and cost-effective way. Utilizing photonic advantage for astronomical spectroscopy is a promising approach to miniaturizing the next generation of spectrometers for large telescopes. 
  • 655
  • 23 Jun 2021
Topic Review
Outline of Nanotechnology
The following outline is provided as an overview of and topical guide to nanotechnology: Nanotechnology is science, engineering, and technology conducted at the nanoscale, which is about 1 to 100 nanometers.
  • 654
  • 26 Oct 2022
Topic Review
ADM Energy
The ADM formalism (named for its authors Richard Arnowitt, Stanley Deser and Charles W. Misner) is a Hamiltonian formulation of general relativity that plays an important role in canonical quantum gravity and numerical relativity. It was first published in 1959. The comprehensive review of the formalism that the authors published in 1962 has been reprinted in the journal General Relativity and Gravitation, while the original papers can be found in the archives of Physical Review.
  • 653
  • 08 Nov 2022
Topic Review
Cell-to-Cell Communication and Information Transfer
Crucial events are generated by criticality, namely by the processes of phase transition from disorder to correlated disorder, affecting key organismal network functions. There is, as suggested by, “a subtle connection between informational exchange within and between networks and the complexity (non-simplicity) of those networks”. West and Grigolini replaced the term complexity with non-simplicity and explain their reasoning by stating that in physics it is easier to understand how phenomena function by the properties or characteristics that are missing, rather than those that are present.
  • 650
  • 22 Sep 2021
Topic Review
Equinox (Celestial Coordinates)
In astronomy, an equinox is either of two places on the celestial sphere at which the ecliptic intersects the celestial equator. Although there are two intersections of the ecliptic with the celestial equator, by convention, the equinox associated with the Sun's ascending node is used as the origin of celestial coordinate systems and referred to simply as "the equinox". In contrast to the common usage of spring/vernal and autumnal equinoxes, the celestial coordinate system equinox is a direction in space rather than a moment in time. In a cycle of about 25,800 years, the equinox moves westward with respect to the celestial sphere because of perturbing forces; therefore, in order to define a coordinate system, it is necessary to specify the date for which the equinox is chosen. This date should not be confused with the epoch. Astronomical objects show real movements such as orbital and proper motions, and the epoch defines the date for which the position of an object applies. Therefore, a complete specification of the coordinates for an astronomical object requires both the date of the equinox and of the epoch. The currently used standard equinox and epoch is J2000.0, which is January 1, 2000 at 12:00 TT. The prefix "J" indicates that it is a Julian epoch. The previous standard equinox and epoch was B1950.0, with the prefix "B" indicating it was a Besselian epoch. Before 1984 Besselian equinoxes and epochs were used. Since that time Julian equinoxes and epochs have been used.
  • 648
  • 02 Dec 2022
Topic Review
Naturalness
In physics, naturalness is the property that the dimensionless ratios between free parameters or physical constants appearing in a physical theory should take values "of order 1" and that free parameters are not fine-tuned. That is, a natural theory would have parameter ratios with values like 2.34 rather than 234000 or 0.000234. The requirement that satisfactory theories should be "natural" in this sense is a current of thought initiated around the 1960s in particle physics. It is a criterion that arises from the seeming non-naturalness of the standard model and the broader topics of the hierarchy problem, fine-tuning, and the anthropic principle. However it does tend to suggest a possible area of weakness or future development for current theories such as the Standard Model, where some parameters vary by many orders of magnitude, and which require extensive "fine-tuning" of their current values of the models concerned. The concern is that it is not yet clear whether these seemingly exact values we currently recognize, have arisen by chance (based upon the anthropic principle or similar) or whether they arise from a more advanced theory not yet developed, in which these turn out to be expected and well-explained, because of other factors not yet part of particle physics models. The concept of naturalness is not always compatible with Occam's razor, since many instances of "natural" theories have more parameters than "fine-tuned" theories such as the Standard Model. Naturalness in physics is closely related to the issue of fine-tuning, and over the past decade many scientists argued that the principle of naturalness is a specific application of Bayesian statistics. In the history of particle physics, the naturalness principle has given correct predictions three times - in the case of electron self-energy, pion mass difference and kaon mass difference.
  • 647
  • 28 Oct 2022
Topic Review
Types of Liquid Crystals
The liquid-crystalline state of matter (mesomorphic state, or mesophase) is intermediate between the crystalline and liquid states, simultaneously showing some of the anisotropic properties of solids and the fluidity of liquids. In this state, materials demonstrate a tendency to flow like liquids and have some properties similar to solids. LCs may be divided into two main classes, named thermotropics and lyotropics. The importance of liquid crystals, alongside with their technical applications, lies in their role as carriers of life. In fact, fully ordered solids are a dead matter, and fully disordered liquids are also dead. But liquid crystals, as partially ordered soft matter systems, bear all qualities that had been necessary for the emergence of life. Practically all biological structures show some features pf liquid crystalline ordering. 
  • 647
  • 15 Jun 2023
Topic Review
OCT Applications in GI Tract
Optical coherence tomography (OCT) is uniquely poised for advanced imaging in the gastrointestinal (GI) tract as it allows real-time, subsurface and wide-field evaluation at near-microscopic resolution, which may improve the current limitations or even obviate the need of superficial random biopsies in the surveillance of early neoplasias in the near future. OCT’s greatest impact so far in the GI tract has been in the study of the tubular esophagus owing to its accessibility, less bends and folds and allowance of balloon employment with optimal contact to aid circumferential imaging. Moreover, given the alarming rise in the incidence of Barrett's esophagus and its progression to adenocarcinoma in the U.S., OCT has helped identify pathological features that may guide future therapy and follow-up strategy. This review will explore the current uses of OCT in the gastrointestinal tract and future directions, particularly with non-endoscopic office-based capsule OCT and the use of artificial intelligence to aid in diagnoses.
  • 646
  • 06 Nov 2020
Topic Review
Perturbation
In astronomy, perturbation is the complex motion of a massive body subjected to forces other than the gravitational attraction of a single other massive body. The other forces can include a third (fourth, fifth, etc.) body, resistance, as from an atmosphere, and the off-center attraction of an oblate or otherwise misshapen body.
  • 645
  • 28 Oct 2022
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