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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
  • 555
  • 25 Nov 2022
Topic Review
Synchrotron Light Source
A synchrotron light source is a source of electromagnetic radiation (EM) usually produced by a storage ring, for scientific and technical purposes. First observed in synchrotrons, synchrotron light is now produced by storage rings and other specialized particle accelerators, typically accelerating electrons. Once the high-energy electron beam has been generated, it is directed into auxiliary components such as bending magnets and insertion devices (undulators or wigglers) in storage rings and free electron lasers. These supply the strong magnetic fields perpendicular to the beam which are needed to convert high energy electrons into photons. The major applications of synchrotron light are in condensed matter physics, materials science, biology and medicine. A large fraction of experiments using synchrotron light involve probing the structure of matter from the sub-nanometer level of electronic structure to the micrometer and millimeter level important in medical imaging. An example of a practical industrial application is the manufacturing of microstructures by the LIGA process.
  • 555
  • 11 Oct 2022
Topic Review
Charge
In physics, a charge is any of many different quantities, such as the electric charge in electromagnetism or the color charge in quantum chromodynamics. Charges correspond to the time-invariant generators of a symmetry group, and specifically, to the generators that commute with the Hamiltonian. Charges are often denoted by the letter Q, and so the invariance of the charge corresponds to the vanishing commutator [math]\displaystyle{ [Q,H]=0 }[/math], where H is the Hamiltonian. Thus, charges are associated with conserved quantum numbers; these are the eigenvalues q of the generator Q.
  • 554
  • 14 Oct 2022
Topic Review
Magnetic Ag-Integrated Photocatalysts in Water Treatment
One of the great dangers facing humanity is the depletion of natural resources. For water specifically, the problem of shortage is all but gone. In 1960, only 9% of the world’s population was facing chronic water shortage issues, while nearly 50% of the global population has to manage moderate shortage, with around 10% of that population facing almost complete lack of water. Many measures have been employed to balance this ever-increasing threat, such as irrigated areas, groundwater utilization and reservoir storage, as this increase in water shortage does not only affect agriculture but human health itself as well and can even increase risks of diseases. The need for low-cost water treatment is especially evident in countries such as Pakistan, where the increased dependency on severely threatening contaminated water (by ~80% of the population) necessitates methods such as low-cost water filters for increased availability of affordable drinking water throughout the country. A magnetic/silver composite combines the advantages of magnetic properties with those of plasmonic nanoparticles, and these composites are able to perform well under UV and visible light, are effective against pollutants and pathogenic bacteria and can be easily separated from a solution with a simple magnet.
  • 553
  • 19 Jul 2022
Topic Review
Geant4-DNA Simulation Toolkit
The Geant4-DNA low energy extension of the Geant4 Monte Carlo (MC) toolkit is a continuously evolving MC simulation code permitting mechanistic studies of cellular radiobiological effects. Geant4-DNA considers the physical, chemical, and biological stages of the action of ionizing radiation (in the form of x- and γ-ray photons, electrons and β±-rays, hadrons, α-particles, and a set of heavier ions) in living cells towards a variety of applications ranging from predicting radiotherapy outcomes to radiation protection both on earth and in space.
  • 552
  • 19 Jan 2022
Topic Review
Transit of Venus, 1639
The first known observations and recording of a transit of Venus were made in 1639 by the English astronomers Jeremiah Horrocks and his friend and correspondent William Crabtree. The pair made their observations independently on 4 December that year (24 November under the Julian calendar then used in England); Horrocks from Carr House, then in the village of Much Hoole, Lancashire, and Crabtree from his home in Broughton, near Manchester. The friends, followers of the new astronomy of Johannes Kepler, were self-taught mathematical astronomers who had worked methodically to correct and improve Kepler's Rudolphine tables by observation and measurement. In 1639, Horrocks was the only astronomer to realise that a transit of Venus was imminent; others became aware of it only after the event when Horrocks's report of it was circulated. Although the friends both died within five years of making their observations, their ground-breaking work was influential in establishing the size of the Solar System; for this and their other achievements Horrocks and Crabtree, along with their correspondent William Gascoigne, are considered to be the founding fathers of British research astronomy.
  • 552
  • 06 Dec 2022
Biography
Gustav Heinrich Wiedemann
Gustav Heinrich Wiedemann (German pronunciation: [ˈhaɪ̯nʁɪç ˈɡʊsta(ː)f ˈviːdəman];[1][2]) FRS(For) HFRSE (2 October 1826 – 24 March 1899) was a German physicist and scientific author. Wiedemann was born in Berlin the son of a merchant who died two years later. Following the death of his mother in 1842 he lived with his grandparents.[3] After attending a private school as well
  • 552
  • 12 Dec 2022
Topic Review
Ursa Major Moving Group
The Ursa Major Moving Group, also known as Collinder 285 and the Ursa Major association, is the closest stellar moving group – a set of stars with common velocities in space and thought to have a common origin in space and time. In the case of the Ursa Major group, all the stars formed about 300 million years ago. Its core is located roughly 80 light years away and part of the Local Bubble. It is rich in bright stars including most of the stars of the Big Dipper.
  • 551
  • 14 Oct 2022
Topic Review
DUNE Experiment
The Deep Underground Neutrino Experiment (DUNE) is a neutrino experiment under construction, with a near detector at Fermilab and a far detector at the Sanford Underground Research Facility that will observe neutrinos produced at Fermilab. An intense beam of trillions of neutrinos from the production facility at Fermilab (in Illinois) will be sent over a distance of 1,300 kilometers (810 mi) with the goal of understanding the role of neutrinos in the universe. More than 1,000 collaborators work on the project. The experiment is designed for a 20-year period of data collection. The primary science objectives of DUNE are The science goals are so compelling that the 2014 Particle Physics Project Prioritization Panel (P5) ranked this as "the highest priority project in its timeframe" (recommendation 13). The importance of these goals has led to proposals for competing projects in other countries, particularly the Hyper-Kamiokande experiment in Japan, scheduled to begin data-taking in 2027. The DUNE project, overseen by Fermilab, has suffered delays to its schedule and growth of cost from less than $2B to $3B, leading to articles in the journals Science and Scientific American described the project as "troubled." As of 2022, the DUNE experiment has a neutrino-beam start-date in the early-2030's, and the project is now phased.
  • 550
  • 24 Oct 2022
Topic Review
Water Retention on Mathematical Surfaces
Water retention on mathematical surfaces is the catching of water in ponds on a surface of cells of various heights on a regular array such as a square lattice, where water is rained down on every cell in the system. The boundaries of the system are open and allow water to flow out. Water will be trapped in ponds, and eventually all ponds will fill to their maximum height, with any additional water flowing over spillways and out the boundaries of the system. The problem is to find the amount of water trapped or retained for a given surface. This has been studied extensively for two mathematical surfaces: magic squares and random surfaces. The model can also be applied to the triangular grid.
  • 549
  • 01 Nov 2022
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