A portable apparatus for measuring the magnetic field strength in an electromagnetic wave

A portable apparatus is described which is capable of measuring directly, by means of a loop aerial, the magnetic field in an electromagnetic wave. Accurate measurements are possible of magnetic fields corresponding to field strengths of 0·2 millivolts per metre. Special means of providing small known calibrating E. M. F. S are described. The apparatus can be used to measure signals over the range 6 microvolts to 300 millivolts. Used in conjunction with a small portable vertical aerial, field strengths down to 2 microvolts per metre can be measured.

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Programmable shunt valve interactions with osseointegrated hearing devices

Journal of Neurosurgery Pediatrics ◽

10.3171/2016.11.peds16501 ◽

2017 ◽

Vol 19 (4) ◽

pp. 384-390

Author(s):

Matthew J. Pierson ◽

Daniel Wehrmann ◽

J. Andrew Albers ◽

Najib E. El Tecle ◽

Dary Costa ◽

...

Keyword(s):

Magnetic Field ◽

Field Strength ◽

Magnetic Field Strength ◽

Shunt Valve ◽

Vp Shunt ◽

Magnetic Attachment ◽

Hearing Devices ◽

Programmable Valves ◽

The Magnetic Field ◽

Field Strengths

OBJECTIVE Patients with ventriculoperitoneal (VP) shunts with programmable valves who would benefit from osseointegrated hearing devices (OIHDs) represent a unique population. The aim of this study was to evaluate the magnetic field strengths of 4 OIHDs and their interactions with 5 programmable VP shunt valves. METHODS Magnetic field strength was measured as a function of distance for each hearing device (Cochlear Baha 5, Cochlear Baha BP110, Oticon Ponto Plus Power, and Medtronic Sophono) in the following modes: inactive, active in quiet, and active in 60 decibels of background noise in the sound booth. The hearing devices were introduced to each shunt valve (Aesculap proGAV, Aesculap proGAV 2.0, Codman Hakim, Codman Certas, and Medtronic Strata II) also as a function of distance in these identical 3 settings. Each trial was repeated 5 times. Between each trial, the valves were assessed for a change in setting. Finally, using a skull model, the devices were introduced to each other in standard anatomical locations and the valves were assessed for a change in settings. RESULTS The maximum magnetic field strengths generated by the Cochlear Baha 5, BP110, and Oticon OIHDs were 1.1, 36.2, and 48.7 gauss (G), respectively. The maximum strength generated by the Sophono device was > 800 G. The magnetic field strength of the hearing devices decreased markedly with increasing distance from the device. The strength of the Sophono's magnetic attachment decreased to 34.8 G at 5 mm. The Codman Hakim, Codman Certas, and Medtronic Strata II valve settings changed when rotating the valves next to the Sophono abutment. No other changes in valve settings occurred in the distance or anatomical models for any other trials. CONCLUSIONS This is the first study evaluating the interaction between OIHDs and programmable VP shunt valves. The findings suggest that it is safe to use these devices together without having to switch to a nonprogrammable valve or move the shunt valve to a more distant location. Still, care should be taken if the Sophono device is used to ensure that the valve is ≥ 5 mm away from the magnetic attachment.

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The connection of fine-structure photospheric features in active regions with magnetic fields

Symposium - International Astronomical Union ◽

10.1017/s0074180900021513 ◽

1968 ◽

Vol 35 ◽

pp. 201-201

Author(s):

N. V. Steshenko

Keyword(s):

Magnetic Field ◽

Fine Structure ◽

High Resolution ◽

Magnetic Fields ◽

Field Strength ◽

Magnetic Field Strength ◽

Active Regions ◽

Transverse Magnetic ◽

List Type ◽

The Magnetic Field

1.The fine structure of the proton sunspot group of July 4–8, 1966 was studied on the basis of high-resolution heliograms. The comparison of the orientation between penumbral filaments and the transverse magnetic fields (observed by A.B. Severny and T.T. Tsap) shows that the direction of the filaments coincides in general with that of the magnetic field.2.Measurements of the magnetic fields of smallest pores (1·5″-2″) showed that the pores are always connected with strong magnetic field (in average 1400 gauss), which is localized at the same small area as the pore.3.Magnetic fields of faculae are concentrated in small elements with the dimension not exceeding 1·5″-3″. Magnetic-field strength H|| of about 45% of facular granules is within the limits of photographic measuring errors (approximately 25 gauss). For a quarter of all facular granules the strength H|| is from 25–50 gauss; about 30% of facular granules have H|| > 50 gauss, and sometimes there appear faculae with field strength of about 200 gauss. The magnetic-field strength of facular granules, which are found directly above spots, is 10–20 times less than the field strength of spots. This field is 80–210 gauss only.4.All observational data mentioned above show that the appearance of the fine-structure features in active regions is directly connected with the fine structure of magnetic field of different strength and different orientation. The study of high-resolution heliograms gives additional information about the fine structure of the magnetic field.

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Fluctuations of the magnetic-field strength of sunspots within one day

Symposium - International Astronomical Union ◽

10.1017/s0074180900021549 ◽

1968 ◽

Vol 35 ◽

pp. 214-214

Author(s):

H. Künzel

Keyword(s):

Magnetic Field ◽

Field Strength ◽

Magnetic Field Strength ◽

General Tendency ◽

Mean Error ◽

The Mean ◽

Short Time ◽

The Magnetic Field ◽

Field Strengths

In the period of May-June 1965, the magnetic-field strengths of twenty sunspots were measured in order to investigate fluctuations within one day. The results of spectrograms, which were taken in the interval of one hour, are given in graphs. The mean error of one value has the size of ± 169 gauss. The graphs show the general tendency in the behaviour of field strength. Fluctuations of magnetic-field strength up to 800 gauss within a few hours were found. The short-time fluctuations shown in the graphs are mostly smaller than the mean error and therefore probably not real.For more details see Astron. Nachr., 289 (1967), 233.

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On the magnetic-field configuration in sunspots

Symposium - International Astronomical Union ◽

10.1017/s0074180900021525 ◽

1968 ◽

Vol 35 ◽

pp. 202-210

Author(s):

O. Kjeldseth Moe

Keyword(s):

Magnetic Field ◽

Magnetic Fields ◽

Field Strength ◽

Magnetic Field Strength ◽

Solar Disk ◽

Field Configuration ◽

Solar Observatory ◽

Line Profiles ◽

Magnetic Field Configuration ◽

The Magnetic Field

During 1963–67 observations of the magnetic fields in sunspots have been obtained at the Oslo Solar Observatory. For the largest spots the detailed distribution of the magnetic-field strength is found. Based on calculations of line profiles made by the author (Kjeldseth Moe, 1967) also the direction of the magnetic field is derived. Observations of the magnetic field of the same spot at several positions on the solar disk give further information regarding the magnetic-field configuration. Our results are in fair agreement with those of Bumba (1962).

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PENGARUH MEDAN MAGNET TERHADAP DIAMETER PERKECAMBAHAN KACANG HIJAU

Jurnal Fisika : Fisika Sains dan Aplikasinya ◽

10.35508/fisa.v5i1.2030 ◽

2020 ◽

Vol 5 (1) ◽

pp. 66-70

Author(s):

Aditya Vethra Prasetyo

Keyword(s):

Magnetic Field ◽

Magnetic Fields ◽

Field Strength ◽

Magnetic Field Strength ◽

Green Bean ◽

Green Beans ◽

Bean Sprout ◽

Randomized Design ◽

Completely Randomized Design ◽

The Magnetic Field

Abstrak Penelitian yang dilakukan berjudul “Pengaruh Medan Magnet Terhadap Diameter Perkecambahan Kacang Hijau”. Penelitian ini bertujuan untuk mengetahui pengaruh medan magnet terhadap diameter perkecambahan kacang hijau. Penelitian ini disusun dalam Rancangan Acak Lengkap (RAL) dengan satu faktor, yaitu kuat medan magnet dalam waktu yang sama yang terdiri dari kontrol (0 mT), 5,3 mT, 10,7 mT, 16,1 mT, 21,5 mT. Parameter yang diukur adalah diameter batang kecambah kacang hijau. Data dianalisis ragam dilanjutkan dengan uji DMRT pada taraf α = 5%. Hasil penelitian menunjukkan bahwa pemaparan medan magnet mempengaruhi diameter batang kecambah kacang hijau. Perlakuan yang menyebabkan perkembangan diameter batang terbesar adalah 21,5 mT. Kata kunci: kacang hijau, medan magnet, diameter Abstract The study was conducted entitled "The Effect of Magnetic Fields on the Diameter of Green Bean Germination". This study aims to determine the effect of the magnetic field on the diameter of green bean germination. This research was arranged in a Completely Randomized Design (CRD) with one factor, namely magnetic field strength at the same time consisting of controls (0 mT), 5.3 mT, 10.7 mT, 16.1 mT, 21.5 mT . The parameter measured is the diameter of the green bean sprout stem. Data were analyzed by continued variance with DMRT test at α = 5%. The results showed that exposure to the magnetic field affected the diameter of the green bean sprout stem. The treatment that caused the largest stem diameter development was 21.5 mT. Keywords: green beans, magnetic field, diameter

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Eindimensionale Plasmaströmung in gekreuzten elektrischen und magnetischen Feldern

Zeitschrift für Naturforschung A ◽

10.1515/zna-1965-0805 ◽

1965 ◽

Vol 20 (8) ◽

pp. 1019-1026 ◽

Cited By ~ 1

Author(s):

E. Rebhan

Keyword(s):

Magnetic Field ◽

Magnetic Fields ◽

Field Strength ◽

Shock Front ◽

Magnetic Field Strength ◽

Plasma Flow ◽

One Dimensional ◽

Electric And Magnetic Fields ◽

The Magnetic Field ◽

Steady Shock

An investigation was made of a steady, one-dimensional plasma flow in crossed electric and magnetic fields. The interaction between the flow and the fields causes various flow types. In general, the flow is either supersonic or subsonic in the entire channel. Under certain circumstances, however, a transsonic flow may develop. Finally, flows exist with a steady shock front, the position and strength of which depend on the magnetic field strength and the pressure at the end of the tube.

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On the Configuration of the Magnetic Field of β CrB

International Astronomical Union Colloquium ◽

10.1017/s0252921100080933 ◽

1976 ◽

Vol 32 ◽

pp. 613-622

Author(s):

I.A. Aslanov ◽

Yu.S. Rustamov

Keyword(s):

Magnetic Field ◽

Field Strength ◽

Radial Velocity ◽

Magnetic Field Strength ◽

Complex Shape ◽

Rotation Period ◽

Field Variation ◽

Magnetic Field Variation ◽

Secular Variations ◽

The Magnetic Field

SummaryMeasurements of the radial velocities and magnetic field strength of β CrB were carried out. It is shown that there is a variability with the rotation period different for various elements. The curve of the magnetic field variation measured from lines of 5 different elements: FeI, CrI, CrII, TiII, ScII and CaI has a complex shape specific for each element. This may be due to the presence of magnetic spots on the stellar surface. A comparison with the radial velocity curves suggests the presence of a least 4 spots of Ti and Cr coinciding with magnetic spots. A change of the magnetic field with optical depth is shown. The curve of the Heffvariation with the rotation period is given. A possibility of secular variations of the magnetic field is shown.

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The effects of magnetic field strength on the properties of wind generated from hot accretion flow

Astronomy and Astrophysics ◽

10.1051/0004-6361/201832985 ◽

2018 ◽

Vol 615 ◽

pp. A35 ◽

Cited By ~ 10

Author(s):

De-Fu Bu ◽

Amin Mosallanezhad

Keyword(s):

Magnetic Field ◽

Field Strength ◽

Pressure Gradient ◽

Magnetic Field Strength ◽

Magnetic Pressure ◽

Gas Pressure ◽

Accretion Flow ◽

Accretion Flows ◽

Black Hole Accretion ◽

The Magnetic Field

Context. Observations indicate that wind can be generated in hot accretion flow. Wind generated from weakly magnetized accretion flow has been studied. However, the properties of wind generated from strongly magnetized hot accretion flow have not been studied. Aims. In this paper, we study the properties of wind generated from both weakly and strongly magnetized accretion flow. We focus on how the magnetic field strength affects the wind properties. Methods. We solve steady-state two-dimensional magnetohydrodynamic equations of black hole accretion in the presence of a largescale magnetic field. We assume self-similarity in radial direction. The magnetic field is assumed to be evenly symmetric with the equatorial plane. Results. We find that wind exists in both weakly and strongly magnetized accretion flows. When the magnetic field is weak (magnetic pressure is more than two orders of magnitude smaller than gas pressure), wind is driven by gas pressure gradient and centrifugal forces. When the magnetic field is strong (magnetic pressure is slightly smaller than gas pressure), wind is driven by gas pressure gradient and magnetic pressure gradient forces. The power of wind in the strongly magnetized case is just slightly larger than that in the weakly magnetized case. The power of wind lies in a range PW ~ 10−4–10−3 Ṁinc2, with Ṁin and c being mass inflow rate and speed of light, respectively. The possible role of wind in active galactic nuclei feedback is briefly discussed.

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COMPARISON OF CARDIAC MAGNETIC FIELD DISTRIBUTIONS DURING DEPOLARIZATION AND REPOLARIZATION

International Journal of Bifurcation and Chaos ◽

10.1142/s0218127403008971 ◽

2003 ◽

Vol 13 (12) ◽

pp. 3783-3789 ◽

Cited By ~ 4

Author(s):

F. E. SMITH ◽

P. LANGLEY ◽

L. TRAHMS ◽

U. STEINHOFF ◽

J. P. BOURKE ◽

...

Keyword(s):

Magnetic Field ◽

Field Strength ◽

Magnetic Field Strength ◽

Field Distribution ◽

Normal Subjects ◽

The Body ◽

Magnetic Field Distribution ◽

T Wave ◽

High Magnetic Field Strength ◽

The Magnetic Field

Multichannel magnetocardiography measures the magnetic field distribution of the human heart noninvasively from many sites over the body surface. Multichannel magnetocardiogram (MCG) analysis enables regional temporal differences in the distribution of cardiac magnetic field strength during depolarization and repolarization to be identified, allowing estimation of the global and local inhomogeneity of the cardiac activation process. The aim of this study was to compare the spatial distribution of cardiac magnetic field strength during ventricular depolarization and repolarization in both normal subjects and patients with cardiac abnormalities, obtaining amplitude measurements by magnetocardiography. MCGs were recorded at 49 sites over the heart from three normal subjects and two patients with inverted T-wave conditions. The magnetic field intensity during depolarization and repolarization was measured automatically for each channel and displayed spatially as contour maps. A Pearson correlation was used to determine the spatial relationship between the variables. For normal subjects, magnetic field strength maps during depolarization (R-wave) showed two asymmetric regions of magnetic field strength with a high positive value in the lower half of the chest and a high negative value above this. The regions of high R-wave amplitude corresponded spatially to concentrated asymmetric regions of high magnetic field strength during repolarization (T-wave). Pearson-r correlation coefficients of 0.7 (p<0.01), 0.8 (p<0.01) and 0.9 (p<0.01) were obtained from this analysis for the three normal subjects. A negative correlation coefficient of -0.7 (p<0.01) was obtained for one of the subjects with inverted T-wave abnormalities, suggesting similar but inverted magnetic field and current distributions to normal subjects. Even with the high correlation values in these four subjects, the MCG was able to identify differences in the distribution of magnetic field strength, with a shift in the T-wave relative to the R-wave. The measurement of cardiac magnetic field distribution during depolarization and repolarization of normal subjects and patients with clinical abnormalities should enable the improvement of theoretical models for the explanation of the cardiac depolarization and repolarization processes.

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