XVI. On the magnetism of iron arising from its rotation

1825 ◽  
Vol 115 ◽  
pp. 347-417 ◽  
Keyword(s):  
Magnetic Axis ◽  
Additional Test ◽  
Magnetic Needle ◽  
Simple Rotation ◽  
Careful Investigation

As the principles on which phenomena depend can only be discovered by a careful investigation of the circumstances attending every new fact which presents itself, its import­ance must not, in the first instance, be estimated by the magnitude of the effects produced, but by their peculiarity. However minute may be the effects, an inquiry into the laws which govern them, if unattended by any other, will have this advantage, that these laws will serve as an additional test of the correctness of the principles advanced for the ex­planation of the more striking phænomena, firmly establish­ing their truth, if the consequences of those principles, or being incompatible with them, pointing out their fallacy. Thus the severest test that the principle of gravitation has been subjected to, is the explanation of the minute irregula­rities in the planetary motions; and the coincidence of the observed irregularities with those deduced from the applica­tion of this principle would have established its truth beyond dispute, had any doubt previously remained. In the expe­riments which I am about to detail, the effects produced are of this minute character; but as they point out a species of action not hitherto observed, they will not, I trust, be consi­dered unimportant. It has been stated that different effects will be produced on iron, as regards its polarity, when struck, twisted, filed, or scoured in different positions, with respect to the magnetic axis or line of the dip; but I am not aware that it has ever been suspected that the simple rotation of iron, in different direc­tions, would have any effect on the manner in which the iron influenced a magnetic needle. This I have discovered to be the case; and that the laws which govern this peculiar action on the needle are so general and uniform, that I have no doubt their causes are as steady in their operation, as those to which the more striking phenomena of magnetism owe their origin. On observing these magnetical phenomena arising purely from rotation, it appeared to me that they might possibly indicate the cause of the earth's magnetism; and this was a further inducement to me thoroughly to investigate the circumstances connected with them. Before giving the particulars of these phenomena, it is necessary that I should mention how I was first led to observe them.

scholarly journals On the magnetism of iron arising from its rotation

1833 ◽  
Vol 2 ◽  
pp. 243-246
Keyword(s):  
Opposite Direction ◽  
Magnetic Axis ◽  
Iron Plate ◽  
Magnetic Action ◽  
Simple Rotation ◽  
The Revolution

The effects observed and described in this paper, although minute in themselves, appear, in the author’s opinion, to point out a species of magnetic action not hitherto described. It had long been well known that striking, twisting, or filing iron in different directions with regard to the magnetic axis, materially influenced its polarity ; but it does not appear to have been remarked, that the simple rotation of iron in different directions has any such influence. This, however, the author has ascertained to be the case ; and that the laws which govern this peculiar action are so regular, that there can remain no doubt of a corresponding regularity in their causes. The attention of the author was first drawn to these phenomena by some apparent anomalies in the magnetic action of an iron plate on the compass, observed in the course of a different investigation. In order to avoid or allow for the disturbing influence of partial magnetism in the iron, it became necessary to attend minutely to the position of certain points in its circumference, which corresponded to the maxima and minima of this magnetism. It was then found that these points were not constant, but shifted their position as the plate was made to revolve in its own plane ; or, in other words, that a plate which, in a given position, produced a certain deviation in a compass, no longer produced the same deviation after making an exact revolution in its own plane, although brought to rest, and every part of the apparatus restored precisely to its former place. It appeared from this that the revolution of the plate in its own plane had an influence on its power of deviating the needle independent of the partial magnetism of particular points in it ; and the justice of this idea was proved by giving it a rotation in an opposite direction, when the effect on the directive power was also reversed.

scholarly journals Experimental researches in electricity. Twenty-second series. 28. On the crystalline polarity of bismuth and other bodies, and on its relation to the magnetic form of force

1851 ◽  
Vol 5 ◽  
pp. 780-783
Keyword(s):  
Magnetic Field ◽  
Maximum Degree ◽  
Magnetic Axis ◽  
Horizontal Line ◽  
Line Parallel ◽  
Glass Tubes ◽  
Experimental Researches ◽  
Magnetic Needle ◽  
The Magnetic Field ◽  
External Form

In this paper the author states that in preparing small cylinders of bismuth by casting them in glass tubes, he had often been embarrassed by the anomalous magnetic results which they gave, and that having determined to investigate the matter closely, it ended in a reference of the effects to the crystalline condition of the bismuth, which may be thus briefly stated. If bismuth be crystallized in the ordinary way, and then a crystal, or a group of symmetric crystals, be selected and suspended in the magnetic field between horizontal poles, it immediately either points in a given direction, or vibrates about a given position, as a small magnetic needle would do, and if disturbed from this position it returns to it. On re-suspending the crystal so that the horizontal line which is transverse to the magnetic axis shall become the vertical line, the crystal then points with its maximum degree of force. If it be again re-suspended so that the line parallel to the magnetic axis be rendered vertical, the crystal loses all directive force. This line of direction, therefore, which tends to place itself parallel to the magnetic axis, the author calls the crystallic axis of the crystal. It is perpendicular, or nearly so, to the brightest and most perfect of the four cleavage planes of the crystal. It is the same for all crystals of bismuth. Whether this magnecrystallic axis is parallel or transverse to the magnetic axis, the bismuth is in both cases repelled from a single, or the stronger of two poles; its diamagnetic relations being in no way affected. If the crystal be broken up, or if it be fused and resolidified, and the metal then subjected to the action of the magnet, the diamagnetic phenomena remain, but the magnecrystallic results disappear, because of the confused and opposing crystalline condition of the various parts. If an ingot of bismuth be broken up and fragmentary plates selected which are crystallized uniformly throughout, these also point; the magnecrystallic axis being, as before, perpendicular to the chief plane of cleavage, and the external form, in this respect, of no consequence. The effect takes place when the crystal is surrounded by masses of bismuth, or when it is immersed in water, or in a solution of sulphate of iron, and with as much force, apparently, as if nothing intervened.

scholarly journals Report of magnetic experiments tried on board an iron steam-vessel, by order of the Right Hon. the Lords Commissioners of the Admiralty

1837 ◽  
Vol 3 ◽  
pp. 378-380
Keyword(s):  
Malleable Iron ◽  
The Right ◽  
The City ◽  
Magnetic Needle

This report commences with a description of the iron steam-vessel, the “Garryowen,” belonging to the City of Dublin Steam Packet Company, and built by the Messrs. Laird, of Liverpool. She is constructed of malleable iron, is 281 tons burthen, and draws only 5 1/4 feet water, although the weight of iron in the hull, machinery, &c. is 180 tons. This vessel was placed under the directions of the author, in Tarbert Bay, on the Shannon, on the 19th of October, 1835, for the purpose of investigating its local attractions on the compass. The methods which were adopted with that view are given ; together with tables of the results of the several experiments, and plans of the various parts of the Garryowen. The horizontal deflections of the magnetic needle at different situations in the vessel were observed, for the purpose of ascertaining the most advantageous place for a steering compass, and also for the application of Professor Barlow’s correcting plate : and the dip and intensity in these situations were, at the same time, noted.

scholarly journals Figures of merit for stellarators near the magnetic axis

2021 ◽  
Vol 87 (1) ◽  
Author(s):  
Matt Landreman
Keyword(s):  
Magnetic Field ◽  
Field Strength ◽  
Magnetic Axis ◽  
Configuration Design ◽  
New Paradigm ◽  
First Order ◽  
Figures Of Merit ◽  
Minor Radius ◽  
Error Field ◽  
Quantities Of Interest

A new paradigm for rapid stellarator configuration design has been recently demonstrated, in which the shapes of quasisymmetric or omnigenous flux surfaces are computed directly using an expansion in small distance from the magnetic axis. To further develop this approach, here we derive several other quantities of interest that can be rapidly computed from this near-axis expansion. First, the $\boldsymbol {\nabla }\boldsymbol {B}$ and $\boldsymbol {\nabla }\boldsymbol {\nabla }\boldsymbol {B}$ tensors are computed, which can be used for direct derivative-based optimization of electromagnetic coil shapes to achieve the desired magnetic configuration. Moreover, if the norm of these tensors is large compared with the field strength for a given magnetic field, the field must have a short length scale, suggesting it may be hard to produce with coils that are suitably far away. Second, we evaluate the minor radius at which the flux surface shapes would become singular, providing a lower bound on the achievable aspect ratio. This bound is also shown to be related to an equilibrium beta limit. Finally, for configurations that are constructed to achieve a desired magnetic field strength to first order in the expansion, we compute the error field that arises due to second-order terms.

scholarly journals Characterization and Quantification of Selenoprotein P: Challenges to Mass Spectrometry

2021 ◽  
Vol 22 (12) ◽  
pp. 6283
Author(s):  
Jérémy Lamarche ◽  
Luisa Ronga ◽  
Joanna Szpunar ◽  
Ryszard Lobinski
Keyword(s):  
Mass Spectrometry ◽  
State Of The Art ◽  
Animal Health ◽  
Primary Standard ◽  
Selenoprotein P ◽  
Primary Standards ◽  
Analytical Approaches ◽  
Careful Investigation ◽  
Accurate Quantification

Selenoprotein P (SELENOP) is an emerging marker of the nutritional status of selenium and of various diseases, however, its chemical characteristics still need to be investigated and methods for its accurate quantitation improved. SELENOP is unique among selenoproteins, as it contains multiple genetically encoded SeCys residues, whereas all the other characterized selenoproteins contain just one. SELENOP occurs in the form of multiple isoforms, truncated species and post-translationally modified variants which are relatively poorly characterized. The accurate quantification of SELENOP is contingent on the availability of specific primary standards and reference methods. Before recombinant SELENOP becomes available to be used as a primary standard, careful investigation of the characteristics of the SELENOP measured by electrospray MS and strict control of the recoveries at the various steps of the analytical procedures are strongly recommended. This review critically discusses the state-of-the-art of analytical approaches to the characterization and quantification of SELENOP. While immunoassays remain the standard for the determination of human and animal health status, because of their speed and simplicity, mass spectrometry techniques offer many attractive and complementary features that are highlighted and critically evaluated.

scholarly journals Additional Test Manoeuvres for Autonomous Inland Vessels

2020 ◽  
Vol 929 ◽  
pp. 012024
Author(s):  
G Peeters ◽  
G Yayla ◽  
M R Afzal ◽  
S Van Baelen ◽  
T Catoor ◽  
...  
Keyword(s):  
Additional Test

scholarly journals Direct construction of optimized stellarator shapes. Part 3. Omnigenity near the magnetic axis

2019 ◽  
Vol 85 (6) ◽  
Author(s):  
Gabriel G. Plunk ◽  
Matt Landreman ◽  
Per Helander
Keyword(s):  
Numerical Method ◽  
Plasma Phys ◽  
Magnetic Axis ◽  
Direct Construction ◽  
Numerical Construction ◽  
First Order

The condition of omnigenity is investigated, and applied to the near-axis expansion of Garren & Boozer (Phys. Fluids B, vol. 3 (10), 1991a, pp. 2805–2821). Due in part to the particular analyticity requirements of the near-axis expansion, we find that, excluding quasi-symmetric solutions, only one type of omnigenity, namely quasi-isodynamicity, can be satisfied at first order in the distance from the magnetic axis. Our construction provides a parameterization of the space of such solutions, and the cylindrical reformulation and numerical method of Landreman & Sengupta (J. Plasma Phys., vol. 84 (6), 2018, 905840616); Landreman et al. (J. Plasma Phys., vol. 85 (1), 2019, 905850103), enables their efficient numerical construction.

Acquired tracheo-oesophageal fistula in a child with unrecognised tracheal foreign body

2021 ◽  
Vol 14 (4) ◽  
pp. e240947
Author(s):  
Kanokpan Ruangnapa ◽  
Wanaporn Anuntaseree ◽  
Kantara Saelim ◽  
Pharsai Prasertsan
Keyword(s):  
Foreign Body ◽  
Young Children ◽  
Respiratory Symptoms ◽  
Growth Failure ◽  
Late Diagnosis ◽  
Feeding Intolerance ◽  
Recurrent Pneumonia ◽  
High Index Of Suspicion ◽  
Careful Investigation

We report the case of a 6-month-old girl who presented with recurrent pneumonia and growth failure. After full examination, she was diagnosed with long-standing, unrecognised tracheal foreign body, which was then successfully removed. However, her chronic respiratory symptoms did not improve, and she also had feeding intolerance. The persistence of symptoms indicated a second bronchoscopy and finally an acquired tracheo-oesophageal fistula was diagnosed. This case emphasises the challenges in diagnosis of an inhaled foreign body in young children. Late diagnosis of this condition can cause significant morbidities. A high index of suspicion and careful investigation are very important to prevent long-term complications.

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