SUMMARY / RELATED TOPICS

Magnetic susceptibility

In electromagnetism, the magnetic susceptibility is a measure of how much a material will become magnetized in an applied magnetic field. Mathematically, it is the ratio of magnetization M to the applied magnetizing field intensity H; this allows a simple classification of most materials' response to an applied magnetic field into two categories: an alignment with the magnetic field, χ > 0, called paramagnetism, or an alignment against the field, χ < 0, called diamagnetism. This alignment has several effects. First, the magnetic susceptibility indicates whether a material is attracted into or repelled out of a magnetic field. Paramagnetic materials align with the field, so are attracted to the magnetic field. Diamagnetic materials are anti-aligned. Second, on top of the applied field, the magnetic moment of the material adds its own magnetic field, causing the field lines to concentrate in paramagnetism, or be excluded in diamagnetism. Quantitative measures of the magnetic susceptibility provide insights into the structure of materials, providing insight into bonding and energy levels.

Furthermore, it is used in geology for paleomagnetic studies and structural geology. Fundamentally, the magnetic moment of materials comes from the magnetism of the particles they are made of; this is dominated by the magnetic moments of electrons. Electrons are present in all materials, but without any external magnetic field, the magnetic moments of the electrons are either paired up or random so that the overall magnetism is zero; the fundamental reasons why the magnetic moments of the electrons line up or do not are complex and cannot be explained by classical physics. However, a useful simplification is to measure the magnetic susceptibility of a material and apply the macroscopic form of Maxwell's equations; this allows classical physics to make useful predictions while avoiding the underlying quantum mechanical details. Magnetic susceptibility is a dimensionless proportionality constant that indicates the degree of magnetization of a material in response to an applied magnetic field. A related term is the proportion between magnetic moment and magnetic flux density.

A related parameter is the permeability, which expresses the total magnetization of material and volume. The volume magnetic susceptibility, represented by the symbol χv, is defined in the International System of Units — in other systems there may be additional constants — by the following relationship: M = χ v H. Here M is the magnetization of the material, measured in amperes per meter, H is the magnetic field strength measured in amperes per meter.χv is therefore a dimensionless quantity. Using SI units, the magnetic induction B is related to H by the relationship B = μ 0 = μ 0 H = μ H where μ0 is the vacuum permeability, is the relative permeability of the material, thus the volume magnetic susceptibility χv and the magnetic permeability μ are related by the following formula: μ = μ 0. Sometimes an auxiliary quantity called intensity of magnetization I and measured in teslas, is defined as I = μ 0 M; this allows an alternative description of all magnetization phenomena in terms of the quantities I and B, as opposed to the used M and H.

There are two other measures of susceptibility, the mass magnetic susceptibility, measured in m3/kg and the molar magnetic susceptibility measured in m3/mol that are defined below, where ρ is the density in kg/m3 and M is molar mass in kg/mol: χ mass = χ v ρ. Note that the definitions above are according to SI conventions. However, many tables of magnetic susceptibility give cgs values; these units rely on a different definition of the permeability of free space: B cgs = H cgs + 4 π M cgs = H cgs {\displaystyle \mathbf ^\ =\ \mathbf ^+4\pi

Shock Illustrated

Shock Illustrated was an American black and white magazine published by EC Comics from late 1955 to early 1956. Part of EC's Picto-Fiction line, each magazine featured three to five stories; the artists drew one to four panels per page with the text overlaid onto the artwork. The first issue appeared with a cover date of September–October 1955 and featured three psychology-themed stories, similar in theme to the comic Psychoanalysis published by EC in 1955. Starting with the second issue this type of story was reduced to one per issue, with the remaining stories being similar in theme to those that appeared in EC's comic Shock SuspenStories. Shock Illustrated ran for a total of three issues; the Picto-Fiction magazines lost money from the start, when EC's distributor went bankrupt, the company had no choice but to cancel the prints. The third issue of this magazine is known as the rarest EC publication of all time. Although all 250,000 copies had been printed, publisher Bill Gaines lacked the funds to bind them, all but 100 copies were destroyed.

The editor of Shock Illustrated was Al Feldstein. In addition to those stories credited to him, Feldstein wrote under the pseudonym Alfred E. Neuman. Feldstein included multiple retellings of previous stories, a move suggested by Gaines; this included "A Question of Time" and "Dead Right" in the second issue and "Curiosity Killed" in the third issue. Contributing writers included Jack Oleck, Robert Bernstein, John Larner, Daniel Keyes. Artists featured in Shock Illustrated included Jack Kamen, Rudy Nappi, Reed Crandall, George Evans, Al Williamson, Angelo Torres and Graham Ingels. Shock Illustrated was reprinted along with the other Picto-Fiction magazines in hardbound volumes by Russ Cochran for the first time in 2006 as the final part of his Complete EC Library. With these reprints, published for the first time, was the fourth issue of the title, produced but never printed. Terror Illustrated "Lipstick Traces" by Bhob Stewart

USS Action

USS Action was the lead ship of the Action-class patrol boats acquired by the United States Navy for the task of patrolling American coastal waters during World War II. She is the only ship to bear this name. Action was laid down as January 1942 by the Collingwood Shipyards Ltd.. Collingwood, Canada. After she had been fitted out at Boston, Action reported to the Commander, Eastern Sea Frontier, on 23 February 1943, she assumed escort and patrol duty. Throughout the rest of 1943, all of 1944, the first half o'f 1945, Action escorted convoys between New York and Guantanamo Bay, Cuba, her next assignment was to patrol the waters in the vicinity of New York and the Narragansett Bay area. Following the surrender of Germany, Action arrived at the Charleston Navy Yard on 28 June 1945. In October 1946, Action was transferred to the Maritime Commission for disposal. List of United States Navy ships Patrol boat This article incorporates text from the public domain Dictionary of American Naval Fighting Ships.

The entry can be found here. NavSource Online: Gunboat Photo Archive – Action ex-HMS Comfrey ex-CN-304