Yes, it turns: experimental evidence of pearl rotation during its formation

Cultured pearls are human creations formed by inserting a nucleus and a small piece of mantle tissue into a living shelled mollusc, usually a pearl oyster. Although many pearl observations intuitively suggest a possible rotation of the nucleated pearl inside the oyster, no experimental demonstration of such a movement has ever been done. This can be explained by the difficulty of observation of such a phenomenon in the tissues of a living animal. To investigate this question of pearl rotation, a magnetometer system was specifically engineered to register magnetic field variations with magnetic sensors from movements of a magnetic nucleus inserted in the pearl oyster. We demonstrated that a continuous movement of the nucleus inside the oyster starts after a minimum of 40 days post-grafting and continues until the pearl harvest. We measured a mean angular speed of 1.27° min −1 calculated for four different oysters. Rotation variability was observed among oysters and may be correlated to pearl shape and defects. Nature's ability to generate so amazingly complex structures like a pearl has delivered one of its secrets.

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A broadband two axis flux-gate magnetometer

Annals of Geophysics ◽

10.4401/ag-4356 ◽

1998 ◽

Vol 41 (3) ◽

Author(s):

P. Palangio

Keyword(s):

Magnetic Field ◽

Low Frequency ◽

High Sensitivity ◽

Magnetic Sensors ◽

Frequency Range ◽

Field Station ◽

Low Weight ◽

Highly Sensitive ◽

Flux Gate ◽

Magnetic Field Variations

A broadband two axis flux-gate magnetometer was developed to obtain high sensitivity in magnetotelluric measurements. In magnetotelluric sounding, natural low frequency electromagnetic fields are used to estimate the conductivity of the Earth's interior. Because variations in the natural magnetic field have small amplitude(10-100 pT) in the frequency range 1 Hz to 100 Hz, highly sensitive magnetic sensors are required. In magnetotelluric measurements two long and heavy solenoids, which must be installed, in the field station, perpendicular to each other (north-south and east-west) and levelled in the horizontal plane are used. The coil is a critical component in magnetotelluric measurements because very slight motions create noise voltages, particularly troublesome in wooded areas; generally the installation takes place in a shallow trench. Moreover the coil records the derivative of the variations rather than the magnetic field variations, consequently the transfer function (amplitude and phase) of this sensor is not constant throughout the frequency range 0.001-100 Hz. The instrument, developed at L'Aquila Geomagnetic Observatory, has a flat response in both amplitude and phase in the frequency band DC-100 Hz, in addition it has low weight, low power, small volume and it is easier to install in the field than induction magnetometers. The sensivity of this magnetometer is 10 pT rms.

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REDUCTION OF THE FIELD SPECTRAL LINEWIDTH IN A QUANTUM-BOX SEMICONDUCTOR LASER AND ITS EXPERIMENTAL DEMONSTRATION USING A QUANTUM WELL LASER IN A HIGH MAGNETIC FIELD

Le Journal de Physique Colloques ◽

10.1051/jphyscol:1987558 ◽

1987 ◽

Vol 48 (C5) ◽

pp. C5-271-C5-274

Author(s):

Y. ARAKAWA ◽

K. VAHALA ◽

A. YARIV

Keyword(s):

Magnetic Field ◽

Quantum Well ◽

Semiconductor Laser ◽

High Magnetic Field ◽

Experimental Demonstration ◽

Quantum Well Laser ◽

Spectral Linewidth

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Magnetic Emission Mapping for Passive Integrated Components Characterisation

ISTFA 2003: Conference Proceedings from the 29th International Symposium for Testing and Failure Analysis ◽

10.31399/asm.cp.istfa2003p0440 ◽

2003 ◽

Author(s):

O. Crépel ◽

Y. Bouttement ◽

P. Descamps ◽

C. Goupil ◽

P. Perdu ◽

...

Keyword(s):

Magnetic Field ◽

Mobile Phone ◽

Printed Circuit Board ◽

Magnetic Sensors ◽

Circuit Board ◽

Magnetic Disturbance ◽

Passive Components ◽

Printed Circuit ◽

Integrated Inductor ◽

The Magnetic Field

Abstract We developed a system and a method to characterize the magnetic field induced by circuit board and electronic component, especially integrated inductor, with magnetic sensors. The different magnetic sensors are presented and several applications using this method are discussed. Particularly, in several semiconductor applications (e.g. Mobile phone), active dies are integrated with passive components. To minimize magnetic disturbance, arbitrary margin distances are used. We present a system to characterize precisely the magnetic emission to insure that the margin is sufficient and to reduce the size of the printed circuit board.

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Relationship between auroral oval poleward boundary intensifications and magnetic field variations in the solar wind

Geomagnetism and Aeronomy ◽

10.1134/s0016793216030105 ◽

2016 ◽

Vol 56 (3) ◽

pp. 268-275

Author(s):

I. A. Kornilov ◽

T. A. Kornilova ◽

I. V. Golovchanskaya

Keyword(s):

Magnetic Field ◽

Solar Wind ◽

Auroral Oval ◽

Magnetic Field Variations

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Dynamics of a disc in a nematic liquid crystal

Soft Matter ◽

10.1039/c5sm02333e ◽

2016 ◽

Vol 12 (4) ◽

pp. 1279-1294 ◽

Cited By ~ 11

Author(s):

Alena Antipova ◽

Colin Denniston

Keyword(s):

Magnetic Field ◽

Liquid Crystal ◽

Numerical Simulations ◽

Nematic Liquid Crystal ◽

Weak Magnetic Field ◽

Angular Speed ◽

The Magnetic Field

We explain the motion of a micron-sized ferromagnetic disc immersed in a nematic liquid crystal under the action of a weak magnetic field using numerical simulations. We show that the disc's behaviour can be controlled by the angular speed of the magnetic field and its magnitude.

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MICROWAVE ABSORPTION STUDIES ON HIGH-Tc SUPERCONDUCTORS AND RELATED MATERIALS II: Electron Spin Resonance of DPPH Coated on Y1Ba2Cu3Oy as A Probe of Magnetic Field Variations

Modern Physics Letters B ◽

10.1142/s0217984991000964 ◽

1991 ◽

Vol 05 (11) ◽

pp. 779-787

Author(s):

K. SUGAWARA ◽

D.J. BAAR ◽

Y. SHIOHARA ◽

S. TANAKA

Keyword(s):

Magnetic Field ◽

Temporal Variations ◽

Zero Field ◽

High Tc ◽

Spin Resonance ◽

Absorption Studies ◽

Powder Particles ◽

Increasing Temperature ◽

Linewidth Broadening ◽

Magnetic Field Variations

The ESR linewidth (∆H pp ) of DPPH coated on the surface of powder specimens of Y 1 Ba 2 Cu 3 O y has been studied under various magnetic field and temperature conditions. ∆H pp increases substantially with decreasing temperature in the field cooled case, whereas almost no linewidth broadening was found in the zero field cooled case. ∆H pp was found to be sensitive to the applied magnetic field. This effect was very pronounced at temperatures lower than 40 K, but decreased strongly with increasing temperature. The broadening of the resonance lineshape has been attributed to spatial and temporal variations of the fluxon distribution in the powder particles.

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Modified Moore–Gibson–Thompson photo-thermoelastic model for a rotating semiconductor half-space subjected to a magnetic field

International Journal of Modern Physics C ◽

10.1142/s0129183121501631 ◽

2021 ◽

pp. 2150163

Author(s):

A. E. Abouelregal ◽

Hijaz Ahmad ◽

S. K. Elagan ◽

Nawal A. Alshehri

Keyword(s):

Magnetic Field ◽

Half Space ◽

Plasma Waves ◽

Angular Speed ◽

Semiconducting Materials ◽

Thermoelastic Model ◽

Mode Method ◽

Heat Transport Equation ◽

Effects Of Rotation ◽

Improved Model

This paper focuses on studying thermal, elastic and coupled plasma waves, in the sense of a photo-thermal process transport within an infinite semiconductor medium. In order to study photo-thermal interactions in two-dimensional semiconducting materials, a new mathematical model based on the Moore–Gibson–Thompson equation (MGTE) is implemented. The MGTE model involving the Green–Naghdi model of type III as well as the heat transport equation proposed by Lord and Shulman. We consider the semi-conductor half-space is rotated at a uniform angular speed and magnetized. The analysis of the distribution of thermophysical fields has been extracted by a normal mode method, represented graphically and discussed. The results predicted by the new and improved model have been compared with the generalized and classic ones. In addition, all field quantities have been examined for effects of rotation, a lifetime of the photo-generated, and the applied magnetic field.

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A Feasibility Study of a Noncontact Torque Sensor with Multiple Hall Sensors

Journal of Sensors ◽

10.1155/2015/126935 ◽

2015 ◽

Vol 2015 ◽

pp. 1-6 ◽

Cited By ~ 3

Author(s):

Kyungshik Lee ◽

Chongdu Cho

Keyword(s):

Magnetic Field ◽

Permanent Magnets ◽

Power Transmission ◽

Magnetic Sensors ◽

Torque Sensor ◽

Torque Measurement ◽

Test Range ◽

Variable Power ◽

Hall Sensors ◽

The Magnetic Field

The feasibility of a noncontact sensor is investigated. This type of sensor can potentially be used for torque measurement in a speed-variable power transmission system. Torque can be read by examining the phase difference between two induction signals from respective magnetic sensors that detect the magnetic field intensity of permanent magnets mounted on the surface of a shaft in rotation. A real-time measuring algorithm that includes filtering and calibration is adopted to measure the torque magnitude. It is shown that this new torque sensor can perform well under rotation speeds ranging from 300 rpm to 500 rpm. As an interim report rather than a complete development, this work demonstrates the feasibility of noncontact torque measurement by monitoring a magnetic field. The result shows an error of less than 2% within the full test range, which is a sufficient competitive performance for commercial sensors. The price is very low compared to competitors in the marketplace, and the device does not require special handling of the shaft of the surface.

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