scholarly journals Geomagnetic field influences upward movement of young Chinook salmon emerging from nests

2018 ◽  
Vol 14 (2) ◽  
pp. 20170752 ◽  
Author(s):  
Nathan F. Putman ◽  
Michelle M. Scanlan ◽  
Amanda M. Pollock ◽  
Joseph P. O'Neil ◽  
Ryan B. Couture ◽  
...  
Keyword(s):  
Magnetic Field ◽  
Chinook Salmon ◽  
Geomagnetic Field ◽  
Oncorhynchus Tshawytscha ◽  
Dimensional Space ◽  
Spatial Scales ◽  
Vertical Component ◽  
Life Cycles ◽  
Upward Movement ◽  
The Magnetic Field

Organisms use a variety of environmental cues to orient their movements in three-dimensional space. Here, we show that the upward movement of young Chinook salmon ( Oncorhynchus tshawytscha ) emerging from gravel nests is influenced by the geomagnetic field. Fish in the ambient geomagnetic field travelled farther upwards through substrate than did fish tested in a field with the vertical component inverted. This suggests that the magnetic field is one of several factors that influences emergence from the gravel, possibly by serving as an orientation cue that helps fish determine which way is up. Moreover, our work indicates that the Oncorhynchus species are sensitive to the magnetic field throughout their life cycles, and that it guides their movements across a range of spatial scales and habitats.

scholarly journals Relationship between plasma flow Doppler velocities and magnetic field parameters during the appearance of active regions at the solar photospheric level

10.12737/7155 ◽  
2015 ◽  
Vol 1 (1) ◽  
pp. 75-84
Author(s):  
Анна Хлыстова ◽  
Anna Khlystova
Keyword(s):  
Magnetic Field ◽  
Plasma Flow ◽  
Spatial Scales ◽  
Vertical Component ◽  
Active Regions ◽  
Solar Disc ◽  
Doppler Imager ◽  
Photospheric Level ◽  
Using Data ◽  
The Magnetic Field

Using data obtained with the Michelson Doppler Imager (MDI) onboard the Solar and Heliospheric Observatory (SOHO), we have conducted a statistical study of the relationship between plasma flow Doppler velocities and magnetic field parameters during the appearance of active regions at the solar photospheric level. We have examined 224 emerging active regions having different spatial scales and positions on the solar disc. The following relationships have been analysed: 1) those between the negative Doppler velocities and the position of active regions emerging on the solar disc; 2) those between the negative and positive Doppler velocities and the magnetic field parameters in the ac-tive regions emerging near the solar disc centre (the vertical component); 3) those between the negative and positive Doppler velocities and the magnetic field pa-rameters in the active regions emerging near the limb (the horizontal component); 4) those between the mag-netic flux growth rate and the strength of emerging magnetic fields; 5) those between the Doppler velocities and the magnetic field parameters during the first hours after the appearance of active regions with the total unsigned magnetic flux at the peak of their development.

scholarly journals Mapping of steady-state electric fields and convective drifts in geomagnetic fields – Part 1: Elementary models

2016 ◽  
Vol 34 (1) ◽  
pp. 55-65 ◽  
Author(s):  
A. D. M. Walker ◽  
G. J. Sofko
Keyword(s):  
Magnetic Field ◽  
Steady State ◽  
Electric Field ◽  
Electric Fields ◽  
Magnetic Field Line ◽  
Geomagnetic Field ◽  
Geomagnetic Field Models ◽  
Spatial Derivatives ◽  
Field Lines ◽  
The Magnetic Field

Abstract. When studying magnetospheric convection, it is often necessary to map the steady-state electric field, measured at some point on a magnetic field line, to a magnetically conjugate point in the other hemisphere, or the equatorial plane, or at the position of a satellite. Such mapping is relatively easy in a dipole field although the appropriate formulae are not easily accessible. They are derived and reviewed here with some examples. It is not possible to derive such formulae in more realistic geomagnetic field models. A new method is described in this paper for accurate mapping of electric fields along field lines, which can be used for any field model in which the magnetic field and its spatial derivatives can be computed. From the spatial derivatives of the magnetic field three first order differential equations are derived for the components of the normalized element of separation of two closely spaced field lines. These can be integrated along with the magnetic field tracing equations and Faraday's law used to obtain the electric field as a function of distance measured along the magnetic field line. The method is tested in a simple model consisting of a dipole field plus a magnetotail model. The method is shown to be accurate, convenient, and suitable for use with more realistic geomagnetic field models.

scholarly journals Reversals in the large-scale αΩ-dynamo with memory

2015 ◽  
Vol 22 (4) ◽  
pp. 361-369 ◽  
Author(s):  
L. K. Feschenko ◽  
G. M. Vodinchar
Keyword(s):  
Magnetic Field ◽  
Power Law ◽  
Geomagnetic Field ◽  
Large Scale ◽  
Magnetic Polarity ◽  
Power Law Model ◽  
The Real ◽  
Geomagnetic Polarity ◽  
With Memory ◽  
The Magnetic Field

Abstract. Inversion of the magnetic field in a model of large-scale αΩ-dynamo with α-effect with stochastic memory is under investigation. The model allows us to reproduce the main features of the geomagnetic field reversals. It was established that the polarity intervals in the model are distributed according to the power law. Model magnetic polarity timescale is fractal. Its dimension is consistent with the dimension of the real geomagnetic polarity timescale.

scholarly journals Properties of the inner penumbral boundary and temporal evolution of a decaying sunspot

2018 ◽  
Vol 620 ◽  
pp. A191 ◽  
Author(s):  
M. Benko ◽  
S. J. González Manrique ◽  
H. Balthasar ◽  
P. Gömöry ◽  
C. Kuckein ◽  
...  
Keyword(s):  
Magnetic Field ◽  
Magnetic Flux ◽  
Temporal Evolution ◽  
Vertical Component ◽  
Field Vector ◽  
Linear Increase ◽  
Vertical Magnetic Field ◽  
Magnetic Diffusion ◽  
The Magnetic Field ◽  
Linear Decay

Context. It has been empirically determined that the umbra-penumbra boundaries of stable sunspots are characterized by a constant value of the vertical magnetic field. Aims. We analyzed the evolution of the photospheric magnetic field properties of a decaying sunspot belonging to NOAA 11277 between August 28–September 3, 2011. The observations were acquired with the spectropolarimeter on-board of the Hinode satellite. We aim to prove the validity of the constant vertical magnetic-field boundary between the umbra and penumbra in decaying sunspots. Methods. A spectral-line inversion technique was used to infer the magnetic field vector from the full-Stokes profiles. In total, eight maps were inverted and the variation of the magnetic properties in time were quantified using linear or quadratic fits. Results. We find a linear decay of the umbral vertical magnetic field, magnetic flux, and area. The penumbra showed a linear increase of the vertical magnetic field and a sharp decay of the magnetic flux. In addition, the penumbral area quadratically decayed. The vertical component of the magnetic field is weaker on the umbra-penumbra boundary of the studied decaying sunspot compared to stable sunspots. Its value seem to be steadily decreasing during the decay phase. Moreover, at any time of the sunspot decay shown, the inner penumbra boundary does not match with a constant value of the vertical magnetic field, contrary to what is seen in stable sunspots. Conclusions. During the decaying phase of the studied sunspot, the umbra does not have a sufficiently strong vertical component of the magnetic field and is thus unstable and prone to be disintegrated by convection or magnetic diffusion. No constant value of the vertical magnetic field is found for the inner penumbral boundary.

scholarly journals Magnetotaxis as a Means for Nanofabrication

2014 ◽  
Vol 23 (01n02) ◽  
pp. 1450008
Author(s):  
Isaac Macwan ◽  
Zihe Zhao ◽  
Omar Sobh ◽  
Jinnque Rho ◽  
Ausif Mahmood ◽  
...  
Keyword(s):  
Magnetic Field ◽  
Geomagnetic Field ◽  
Semiconductor Manufacturing ◽  
Magnetic Field Intensity ◽  
Magnetotactic Bacteria ◽  
Semiconductor Substrate ◽  
Field Lines ◽  
A Chain ◽  
Magnetospirillum Magneticum ◽  
The Magnetic Field

Magnetotactic bacteria (MTB), discovered in early 1970s contain single-domain crystals of magnetite ( Fe 3 O 4) called magnetosomes that tend to form a chain like structure from the proximal to the distal pole along the long axis of the cell. The ability of these bacteria to sense the magnetic field for displacement, also called magnetotaxis, arises from the magnetic dipole moment of this chain of magnetosomes. In aquatic habitats, these organisms sense the geomagnetic field and traverse the oxic-anoxic interface for optimal oxygen concentration along the field lines. Here we report an elegant use of MTB where magnetotaxis of Magnetospirillum magneticum (classified as AMB-1) could be utilized for controlled navigation over a semiconductor substrate for selective deposition. We examined 50mm long coils made out of 18AWG and 20AWG copper conductors having diameters of 5mm, 10mm and 20mm for magnetic field intensity and heat generation. Based on the COMSOL simulations and experimental data, it is recognized that a compound semiconductor manufacturing technology involving bacterial carriers and carbon-based materials such as graphene and carbon nanotubes would be a desirable choice in the future.

scholarly journals Possible influence of variations in the geomagnetic field on migration paths of snow buntings

2019 ◽  
Vol 19 (2) ◽  
pp. 195-201
Author(s):  
Chris M. Hall ◽  
Magnar G. Johnsen
Keyword(s):  
Magnetic Field ◽  
Geomagnetic Field ◽  
Flight Time ◽  
Short Term ◽  
Breeding Grounds ◽  
Declining Populations ◽  
Plectrophenax Nivalis ◽  
The Individual ◽  
Magnetic North ◽  
The Magnetic Field

AbstractA hypothesis is proposed wherein changes in the Earth's magnetic field affect the migratory paths of snow buntings (Plectrophenax nivalis), and in particular from wintering grounds in the Russian/Ukrainian steppes to breeding grounds on Svalbard and with a typical stopover in Finnmark in northern Norway. If one were to assume ignorance of the secular movement of the magnetic north pole approximately 1500 km northwards between 1908 and 2020, the magnetoreceptor contribution to snow buntings' navigation would result in winter-to-summer migratory paths progressively further to the East. In turn, this could be a contributing factor to declining populations in Finnmark and favouring a more frequent flightpath over the Kola Peninsula. On the other hand, short-term perturbations in the magnetic field (i.e. induced by solar activity) and therefore existing for a relatively small proportion of the flight time (if at all) for the individual migrations legs seem unlikely to influence the stopover locations significantly. Even so, these space-weather induced variations cannot be disregarded, particularly for success in reaching Svalbard.

Effects of Electromagnetic Fields on the Quantum Yield of Free Radicals in Cryptochrome

2019 ◽  
Vol 953 ◽  
pp. 127-132
Author(s):  
Yu Ling Chen ◽  
Du Yan Geng ◽  
Chuan Fang Chen
Keyword(s):  
Magnetic Field ◽  
Electromagnetic Field ◽  
Free Radicals ◽  
Free Radical ◽  
Quantum Yield ◽  
Electromagnetic Fields ◽  
Applied Magnetic Field ◽  
Geomagnetic Field ◽  
Quantum Biology ◽  
The Magnetic Field

In this paper, the effects of the quantum yield of free radicals in cryptochrome exposed to different electromagnetic fields were studied through the quantum biology. The results showed that the spikes characteristics was produced in the free radicals in cryptochrome, when it exposed to the applied magnetic field (ω = 50 Hz, B0 = 50 μT). The spikes produced by the electromagnetic field was independent of the changes of polar θ. When the frequency of the magnetic field increased, the spikes characteristics produced in unit time also increased. These results showed that the environmental electromagnetic field could affect the response of organisms to the geomagnetic field by influencing the quantum yield in the mechanism of free radical pair.It provided a basis for studying the influence of environmental electromagnetic field on biology, especially the navigation of biological magnetism.

scholarly journals Spatial scales and locality of magnetic helicity

2020 ◽  
Vol 635 ◽  
pp. A95 ◽  
Author(s):  
C. Prior ◽  
G. Hawkes ◽  
M. A. Berger
Keyword(s):  
Magnetic Field ◽  
Active Region ◽  
Spectral Methods ◽  
Wavelet Decomposition ◽  
Spatial Scales ◽  
Solar Interior ◽  
Magnetic Helicity ◽  
Clear Correlation ◽  
Arbitrary Boundary ◽  
The Magnetic Field

Context. Magnetic helicity is approximately conserved in resistive magnetohydrodynamic models. It quantifies the entanglement of the magnetic field within the plasma. The transport and removal of helicity is crucial in both dynamo development in the solar interior and active region evolution in the solar corona. This transport typically leads to highly inhomogeneous distributions of entanglement. Aims. There exists no consistent systematic means of decomposing helicity over varying spatial scales and in localised regions. Spectral helicity decompositions can be used in periodic domains and is fruitful for the analysis of homogeneous phenomena. This paper aims to develop methods for analysing the evolution of magnetic field topology in non-homogeneous systems. Methods. The method of multi-resolution wavelet decomposition is applied to the magnetic field. It is demonstrated how this decomposition can further be applied to various quantities associated with magnetic helicity, including the field line helicity. We use a geometrical definition of helicity, which allows these quantities to be calculated for fields with arbitrary boundary conditions. Results. It is shown that the multi-resolution decomposition of helicity has the crucial property of local additivity. We demonstrate a general linear energy-topology conservation law, which significantly generalises the two-point correlation decomposition used in the analysis of homogeneous turbulence and periodic fields. The localisation property of the wavelet representation is shown to characterise inhomogeneous distributions, which a Fourier representation cannot. Using an analytic representation of a resistive braided field relaxation, we demonstrate a clear correlation between the variations in energy at various length scales and the variations in helicity at the same spatial scales. Its application to helicity flows in a surface flux transport model show how various contributions to the global helicity input from active region field evolution and polar field development are naturally separated by this representation. Conclusions. The multi-resolution wavelet decomposition can be used to analyse the evolution of helicity in magnetic fields in a manner which is consistently additive. This method has the advantage over more established spectral methods in that it clearly characterises the inhomogeneous nature of helicity flows where spectral methods cannot. Further, its applicability in aperiodic models significantly increases the range of potential applications.

AN ANALYTICAL SOLUTION OF THE COSMIC RAYS TRANSPORT EQUATION IN THE PRESENCE OF THE GEOMAGNETIC FIELD

2002 ◽  
Vol 17 (12n13) ◽  
pp. 1645-1653
Author(s):  
MARINA GIBILISCO
Keyword(s):  
Magnetic Field ◽  
Cosmic Rays ◽  
Analytical Solution ◽  
Transport Equation ◽  
Geomagnetic Field ◽  
The Earth ◽  
Factorization Technique ◽  
Diffusion Motion ◽  
Geomagnetic Fields ◽  
The Magnetic Field

In this work, I study the propagation of cosmic rays inside the magnetic field of the Earth, at distances d ≤ 500 Km from its surface; at these distances, the geomagnetic field deeply influences the diffusion motion of the particles. I compare the different effects of the interplanetary and of the geomagnetic fields, by also discussing their role inside the cosmic rays transport equation; finally, I present an analytical method to solve such an equation through a factorization technique.

scholarly journals Enhancing Performance of Magnetic Field Based Indoor Localization Using Magnetic Patterns from Multiple Smartphones

Sensors ◽  
2020 ◽  
Vol 20 (9) ◽  
pp. 2704 ◽  
Author(s):  
Imran Ashraf ◽  
Soojung Hur ◽  
Yongwan Park
Keyword(s):  
Magnetic Field ◽  
Geomagnetic Field ◽  
Field Data ◽  
Performance Comparison ◽  
Magnetic Sensors ◽  
Location Based Services ◽  
Field Pattern ◽  
Magnetic Field Data ◽  
Localization Performance ◽  
The Magnetic Field

Wide expansion of smartphones triggered a rapid demand for precise localization that can meet the requirements of location-based services. Although the global positioning system is widely used for outdoor positioning, it cannot provide the same accuracy for the indoor. As a result, many alternative indoor positioning technologies like Wi-Fi, Bluetooth Low Energy (BLE), and geomagnetic field localization have been investigated during the last few years. Today smartphones possess a rich variety of embedded sensors like accelerometer, gyroscope, and magnetometer that can facilitate estimating the current location of the user. Traditional geomagnetic field-based fingerprint localization, although it shows promising results, it is limited by the fact that various smartphones have embedded magnetic sensors from different manufacturers and the magnetic field strength that is measured from these smartphones vary significantly. Consequently, the localization performance from various smartphones is different even when the same localization approach is used. So devising an approach that can provide similar performance with various smartphones is a big challenge. Contrary to previous works that build the fingerprint database from the geomagnetic field data of a single smartphone, this study proposes using the geomagnetic field data collected from multiple smartphones to make the geomagnetic field pattern (MP) database. Many experiments are carried out to analyze the performance of the proposed approach with various smartphones. Additionally, a lightweight threshold technique is proposed that can detect user motion using the acceleration data. Results demonstrate that the localization performance for four different smartphones is almost identical when tested with the database made using the magnetic field data from multiple smartphones than that of which considers the magnetic field data from only one smartphone. Moreover, the performance comparison with previous research indicates that the overall performance of smartphones is improved.

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