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Could a change in magnetic field geometry cause the break in the wind activity relation?

Could a change in magnetic field geometry cause the break in the wind activity relation?

solar CME-flare relation cannot be extrapolated all the way to active stars (Drake et al. 2013). Drake et al. (2013) suggested that there might not be a one-to-one relation between observed stellar X-ray flares and CMEs. They argue that on active stars, CMEs are more strongly confined, and so fewer of them are produced for any given number of X-ray flares. This stronger confinement could be caused by the noticeable differences between the solar and stellar magnetic field characteristics. What we have shown here is that indeed the most active stars seem to have more toroidal large-scale magnetic field topologies. Numerical modelling efforts would hopefully be able to shed light on whether the large-scale toroidal fields could indeed result in more confined CMEs.

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Could a change in magnetic field geometry cause the break
in the wind-activity relation?

Could a change in magnetic field geometry cause the break in the wind-activity relation?

diction to the results found by Wood et al. for active stars such as π 1 UMa and ξ Boo A. A possibility for this disagreement is that the solar CME-flare relation cannot be extrapolated all the way to active stars (Drake et al. 2013). Drake et al. (2013) suggested that there might not be a one-to-one relation between observed stellar X-ray flares and CMEs. They argue that on active stars, CMEs are more strongly confined, and so fewer of them are produced for any given number of X-ray flares. This stronger confinement could be caused by the noticeable differences between the solar and stellar magnetic field characteristics. What we have shown here is that indeed the most active stars seem to have more toroidal large-scale magnetic field topologies. Numerical modelling efforts would hopefully be able to shed light on whether the large-scale toroidal fields could indeed result in more confined CMEs.

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Measurement of Impurity Emission Intensity Distribution in the Edge Region of LHD and Its Relation with Magnetic Field Structure

Measurement of Impurity Emission Intensity Distribution in the Edge Region of LHD and Its Relation with Magnetic Field Structure

In order to study impurity emission distribution and its relation to the edge magnetic field structure, carbon emis- sion intensities and the 2D distributions have been mea- sured. It is revealed that density dependence of impurity emission intensities is different for different charge states and different magnetic field configurations. The results are interpreted as due to the change of background plasma temperature and density profiles caused by magnetic con- figuration. It is also found that the 2D impurity emission distributions change significantly depending on the charge states and magnetic field configurations. These results sug- gest the important role of magnetic field structure on the impurity emission and transport.

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The relation between stellar magnetic field geometry and chromospheric activity cycles – II. The rapid 120-day magnetic cycle of τ Bootis

The relation between stellar magnetic field geometry and chromospheric activity cycles – II. The rapid 120-day magnetic cycle of τ Bootis

One of the aims of the BCool programme is to search for cycles in other stars and to understand how similar they are to the Sun. In this paper, we aim to monitor the evolution of τ Boo’s large-scale magnetic field using high-cadence observations covering its chromospheric activity maximum. For the first time, we detect a polarity switch that is in phase with τ Boo’s 120-day chromospheric activity maximum and its inferred X-ray activity cycle maximum. This means that τ Boo has a very fast magnetic cycle of only 240 days. At activity maximum τ Boo’s large-scale field geometry is very similar to the Sun at activity maximum: it is complex and there is a weak dipolar component. In contrast, we also see the emergence of a strong toroidal component which has not been observed on the Sun, and a potentially overlapping butterfly pattern where the next cycle begins before the previous one has finished.

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The relation between stellar magnetic field geometry and chromospheric activity cycles - I. The highly variable field of Eps Eridani at activity minimum

The relation between stellar magnetic field geometry and chromospheric activity cycles - I. The highly variable field of Eps Eridani at activity minimum

Over a period of approximately 5 months, Eridani’s large-scale field evolves (as shown in Fig. 2 and Table 3) with decreasing S- index. The most dramatic changes are seen in the rapid emergence of an axisymmetric toroidal field. This is indicated by the colour of the points in Fig. 2 changing from red at 2014.71 (map 1) to green at 2014.98 (map 3). The field is notably more complex than a simple dipole at all epochs with significant amounts of the mag- netic energy being contained in higher order modes. The poloidal component is approximately 50 per cent dipolar (with values rang- ing from 43 per cent at 2014.71 to 56 per cent at 2014.84), with additional contributions from the quadrupolar (with an average of 20 per cent) and octupolar components (which are typically of the order of 20 per cent) and higher order modes l > 3. The axisymme- try of the large-scale field is quite constant with an average value of 35 per cent.

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On Quasi-biennial oscillations in chromospheric macrospicules and their potential relation to global solar magnetic field

On Quasi-biennial oscillations in chromospheric macrospicules and their potential relation to global solar magnetic field

This study aims to provide further evidence for the potential influence of the global solar magnetic field on localized chromospheric jets, the macrospicules (MS). To find a connection between the long-term variation of properties of MS and other solar activity proxies, including, e.g., the temporal variation of the frequency shift of solar global oscillations, sunspot area, etc., a database overarching seven years of observations was compiled. This database contains 362 MS, based on observations at the 30.4 nm of the Atmospheric Imaging Assembly on board the Solar Dynamics Observatory. Three of the five investigated physical properties of MS show a clear long-term temporal variation after smoothing the raw data. Wavelet analysis of the temporal variation of maximum length, maximum area, and average velocity is carried out. The results reveal a strong pattern of periodicities at around 2 years (also referred to as quasi-biennial oscillations—QBOs). A comparison with solar activity proxies that also possess the properties of QBOs provides some interesting features: the minima and maxima of QBOs of MS properties occur at around the same epoch as the minima and maxima of these activity proxies. For most of the time span investigated, the oscillations are out of phase. This out-of-phase behavior was also corroborated by a cross-correlation analysis. These results suggest that the physical processes that generate and drive the long-term evolution of the global solar activity proxies may be coupled to the short-term local physical processes driving the macrospicules, and, therefore modulate the properties of local dynamics.

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The relation between stellar magnetic field geometry and chromospheric activity cycles   II The rapid 120 day magnetic cycle of τ Bootis

The relation between stellar magnetic field geometry and chromospheric activity cycles II The rapid 120 day magnetic cycle of τ Bootis

Saikia et al. 2016). The second similarity is that there is a strong decrease in the dipolar component after the polarity switch, which then rises again over the following 1.5 months after activity maxi- mum. The Sun shows a similar trend as reported in fig. 1 of DeRosa et al. (2012), though over a longer time period than that for τ Boo. Interestingly, after the polarity switch, there is an emergence of a significant toroidal field which decreases during the 1.5 months after activity maximum. Currently, there are no comparable obser- vations of the Sun’s toroidal field but if the Sun’s large-scale field is similar to τ Boo’s large-scale field, it should exhibit similar field characteristics. An analysis using vector synoptic maps of the Sun would be very insightful (Vidotto 2016). In the case of the Sun, the quadrupolar field is an order of magnitude larger than the dipolar field, which is in contrast to what we observe on τ Boo. The main polarity switch that we have observed is from negative to positive polarity field that occurs just before activity maximum. The emer- gence of an additional magnetic spot with negative polarity after activity maximum (e.g.at polar regions in Maps 2–4) resembles an overlapping butterfly diagram, where one cycle starts before the previous one has finished, in contrast to the well-separated butter- fly diagram observed on the Sun. More observations of τ Boo are needed to confirm this.

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A theory about induced electric current and heating in plasma

A theory about induced electric current and heating in plasma

The traditional generalized Ohm’s law in MHD (Magnetohydrodynamics) does not explicitly present the relation of electric currents and electric fields in fully ionized plasma, and leads to some unexpected concepts, such as “the magnetic frozen-in plasma”, magnetic recon- nection etc. In the single fluid model, the action between electric current and magnetic field is not considered. In the two-fluid model, the derivation is based on the two dynamic equa- tions of ions and electrons. The electric current in traditional generalized Ohm’s law depends on the velocities of the plasma, which should be decided by the two dynamic equations. However, the plasma velocity, eventually not free, is in- appropriately considered as free parameter in the traditional generalized Ohm’s law. In the present paper, we solve the balance equation that can give exact solution of the velocities of electrons and ions, and then derive the electric current in fully ionized plasma. In the case ig- noring boundary condition, there is no electric current in the plane perpendicular to the mag- netic field when external forces are ignored. The electric field in the plane perpendicular to magnetic field do not contribute to the electric currents, so do the induced electric field from the motion of the plasma across magnetic field. The lack of induced electric current will keep magnetic field in space unaffected. The velocity of the bulk velocity of the plasma perpendicular to magnetic field is not free, it is decided by electromagnetic field and the external forces. We conclude that the bulk velocity of the fully ionized plasma is not coupled with the magnetic field. The motion of the plasma do not change the magnetic field in space, but the plasma will be confined by magnetic field. Due to the con- finement of magnetic field, the plasma kinetic

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Study of Flare Related Intense Geomagnetic Storms with Solar Radio Burst and JIMF

Study of Flare Related Intense Geomagnetic Storms with Solar Radio Burst and JIMF

From our study we have found that 82.45% X and M-Class X- Ray solar flare related intense geomagnetic storms are associated with halo and partial halo coronal mass ejections. 71.92% X and M-Class X-Ray solar flare related intense geomagnetic storms are associated with solar radio bursts. From the study of X and M-Class X-Ray solar flare related intense geomagnetic storms with jump in interplanetary magnetic field ,large positive co-relation with co-relation co- efficient, 0.71 has been found between magnitude of X and M- Class X-Ray solar flare related intense geomagnetic storms and peak values of associated jump in interplanetary magnetic field, 0.69 between magnitude of X and M-class X-Ray solar flare related intense geomagnetic storms and magnitude of jump in interplanetary magnetic fields. From these results it is concluded that coronal mass ejections, solar radio bursts and associated JIMF events are responsible to generate X and M Class X-ray solar flare related intense geomagnetic storms.

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Measurement of Magnetic Field from Electrical Appliances in EEE Classrooms of Southeast University Bangladesh

Measurement of Magnetic Field from Electrical Appliances in EEE Classrooms of Southeast University Bangladesh

In classroom MC 408, it has been observed that the (i) room temperature and the electric voltage supplied in Air Conditioners might be different: therefore, the EF and MF varied. (ii) There might be some problems in measurement using the EMF meter. In classroom MC 411, it has been observed that the (i) there were some problems to measure the accurate magnetic field and electric field because some pillars were situated beside the socket switch and distribution board. The magnitude of those measurements for these fields in meter was fluctuating which was confusing. In classroom MC 413, it has been observed that (i) there were not sufficient space around the Air Conditioner and so there were some problems to measure the accurate magnetic field and electric field and (ii) The scale was too short to measure the right side of the AC. From classroom MC 504, it has been observed that the (i) there were not sufficient space in that lab and so there were some problems to measure the accurate magnetic field and electric field threshold distance near the AC. From classroom MC 507, it has been observed that the (i) there were not sufficient space in that lab and so there were some problems to measure the accurate magnetic field and electric field distance and (ii) there were some problems taking reading with the switch. From classroom MC 509, it has been observed that it was difficult to measure the right side of the switch board and socket board because they were situated beside the pillar. From classroom 405, it has been observed that the (i) every element were close to each other for that reason it is difficult to get required value of EF and

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Advanced Panspermia of Origin of Life and Evolution

Advanced Panspermia of Origin of Life and Evolution

Deoxyribonucleic acid (DNA) is a molecule that contains the biological instructions that make each species unique. DNA, along with the instructions it contains, is passed from adult organisms to their offspring during reproduction. DNA is the most famous molecule of heredity. The foetus’s neural network serves as antenna. It tunes into fluctuations in Earth's magnetic field. The imprinting of the neural antennae depends on genetic heredity. This gives us our basic congenital personality. If a certain planet in a parent's planetary configuration at his birth time was placed in a particular zodiacal sign, the child also is born with a similar planetary placement. The percentage of similarities of planets’ places depends on the number of same planets’ occupation in similar signs similar to the number of bands matching in DNA fingerprinting [13]. French statistician and scientist Michel Gauquelin's work, in which human biological clocks keep time with the planets. Gauquelin's studies, which showed striking planetary similarities in the birth charts of parents and their children, comprise the strongest scientific evidence in support of ‘Advanced Panspermia Hypothesis of Origin of life’ to date.

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Electromagnetic fields in coupled cavities.

Electromagnetic fields in coupled cavities.

An electromagnetic field vector function, as defined by Helmhotz, can be represented by the sura of an irrotational function and a.solenoidal function. This concept was first applied to the theory of cavity reso­ nators by Slater [ 1] . However, he considered that on-iy the electric field in the cavity consists of both irrotational as well as 'solenoidal fields; that the magnetic field, on the other hand, has no irrotational part. later, .Teichmann and Y/igner [2] pointed out that ■ a complete expansion of electromagnetic field should include the irrotational magnetic field which w a s found', to be inversely proportional to its frequency Basing on this suggestion, Kurokawa [3] gave a proof that for a complete expansion of electromagnetic field it is neces­ sary to* add the irrotational component in the magnetic field. He asserted that if the irrotational component was neglected, there would be no' magnetic field through the opening of the cavity at all when the cavity is coupled.to a waveguide through an iris.

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Observation of linear and quadratic magnetic field dependence of magneto photocurrents in InAs/GaSb superlattice

Observation of linear and quadratic magnetic field dependence of magneto photocurrents in InAs/GaSb superlattice

MPE has been observed in InGaAs/InAlAs two- dimensional electron gas, GaAs/AlGaAs quantum well, graphene and so on [5-7]. By comparison, the InAs/GaSb type II supperlattice has some advantages in investigat- ing spin transport and fabricating spintronic devices for its properties of large SOI in InAs and GaSb, relatively high carrier mobility in InAs and peculiar energy band structure [8,9]. Previously, the InAs/GaSb type II super- lattice has been extensively researched as an infrared detector. The studies have been mainly focused on carrier recombination, interface properties, tailoring of energy bands and so on [10-17]. The zero-field spin splitting has also been observed in InAs/GaSb quantum wells by Shubnikov-de-Haas oscillation [18], while the inves- tigations on the magneto-photo effect is seldom con- cerned. In the present paper, we investigate the MPE in the InAs/GaSb type II supperlattice. Unlike the previ- ous researches of the magnetic field strength dependence of the photocurrents, we mainly focus on the magnetic field direction dependence of the photocurrents in this structure. By varying magnetic field direction in or out of the sample plane, we observed linear and quadratic magnetic field dependence of the photocurrents, respec- tively. More information about excitation and relaxation

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Magnetic annihilation and reconnection

Magnetic annihilation and reconnection

The first reconnection model which is an exact solution o f the resistive and viscous MHD equations was investigated by Parker (1973) and Sonnerup & Priest (1975). As shown in figure 1.4b, they supposed the field lines to be straight, ie B = 0,0), and carried together by the stagnation-point flow v = ( £ , — y, 0). The induction equation can then be solved for the magnetic field and the equation o f motion for the plasma pressure. This model is similar to the Sweet-Parker model in that the incoming flow o f plasma prevents the outward diffusion o f the current sheet and maintains a constant magnetic gradient. Since field lines cancel exactly within the diffusion region and no magnetic flux is expelled outwards, then this is termed magnetic annihilation.

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Measuring the formation energy barrier of skyrmions in zinc substituted Cu2OSeO3

Measuring the formation energy barrier of skyrmions in zinc substituted Cu2OSeO3

Topological states of matter are the subject of extensive interest in condensed matter physics [1–4]. One such state, the skyrmion lattice, consists of topologically protected nanoscale magnetic solitons that form a hexagonal lattice [5]. Skyrmion lattices usually form only in a small region of magnetic field and temperature just below the magnetic-ordering temper- ature, and are typically stabilized by competition between the Dzyaloshinskii-Moriya interaction (DMI), symmetric ex- change, and thermal fluctuations [4]. This state was first discovered in the noncentrosymmetric metallic compound MnSi that crystallizes in the P2 1 3 space group [6], and has

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The energy budget of stellar magnetic fields: comparing non-potential simulations and observations

The energy budget of stellar magnetic fields: comparing non-potential simulations and observations

The magnetic activity of solar-like stars underpins both their high- energy coronal emission and also their angular momentum evolution through the action of their hot, magnetically channelled winds. Our understanding of this activity is based on what we have learned about the Sun. Solar activity phenomena, e.g. sunspots, prominences, and coronal holes, are mainly driven by the Sun’s magnetic field and show a cyclic behaviour. During the activity cycle, the large-scale field of the Sun develops from an axisymmetric dipole (see e.g. Ossendrijver 2003) to a more chaotic small-scale structured field, covering mid- to low latitudes and then back to a reversed dipole. DeRosa, Brun & Hoeksema (2012) confirmed that the dipole com- ponent follows the activity cycle in antiphase, while the quadrupole

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April 2000 magnetic storm: Solar wind driver and magnetospheric response

April 2000 magnetic storm: Solar wind driver and magnetospheric response

onboard SOHO first observed a halo CME on 4 April 2000 at 1632 UT. This CME caused a strong magnetic storm at the Earth 2 days later. The initial observations were made after a 90 min data gap, when the leading edge had already left the C2 field of view. The coronagraph images show that most of the CME material was centered over the west limb. The plane-of-the-sky speed was reported to be 1188 km/s (SOHO/LASCO CME catalog (http://cdaweb.gsfc.nasa. gov)). This CME event was associated also with other types of solar activity: GOES-8 satellite recorded a C9.7 class flare in the NOAA active region 8933 (N18W58) at 1524 UT. Also H-alpha images from Holloman AFB, New Mexico, showed a disappearance of a large filament pre- ceding the CME onset. The filament was located near the northwest limb (N25W55) and it extended vertically along the surface of the Sun. The filament activation started at 1441 UT and continued until 1535 UT.

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Measurement of Electron Return Effect and Skin Dose Reduction by a Bolus in an Anthropomorphic Physical Phantom under a Magnetic Resonance Guided Linear Accelerator (MR LINAC) System

Measurement of Electron Return Effect and Skin Dose Reduction by a Bolus in an Anthropomorphic Physical Phantom under a Magnetic Resonance Guided Linear Accelerator (MR LINAC) System

which are reported to maximize ERE [4]. The illustrative treatment plans were generated for the four phantom setups (Figure 1) using unblocked thoracic fields of 7 MV beam in a 1.5 T magnetic field. The bolus was simulated as water in the plans. The prescribed dose was 3000 cGy in 10 fractions. The dose was normalized at the midline of the upper torso in the phantom. Planned monitor unit (MU) were 126 MU (AP) and 163 MU (PA) for the adult male phantom and 114 MU (AP) and 203 MU (PA) for the adult female phantom with breast attachments. The MU settings were identical for the plans with and without bo- lus. Higher MU for PA beam were used because the location of beam CAX was fixed at 13 cm above the couch top within the phantom of 18 cm thickness while both beams are equally weighted.

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Design of Miniature Coil to Generate Uniform Magnetic Field

Design of Miniature Coil to Generate Uniform Magnetic Field

Abstract—In various technological and scientific applications, different types of coil systems are being used to produce uniform alternating magnetic field. The dimensions of these coil systems are considerably larger than the volume of interest. There is a necessity to reduce the dimension of the coil system without sacrificing the extent of uniformity of the magnetic field. This problem has a wide audience and still remains as a topic of contemporary research in the development of miniaturized devices especially for calorimetric measurements of nano-particles, cancer therapy, and detection of minute surface defects by eddy current probes, etc. In this paper we present how we can modify the shape of a miniature solenoid to produce uniform magnetic field. A Genetic algorithm has been implemented to get the optimum dimension of the miniature solenoid. Our distinct shape design has achieved 97% uniformity for a 60% volume of interest.

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Electron spin resonance studies of ferric iron in cordierite.

Electron spin resonance studies of ferric iron in cordierite.

silica-glass samples containing known amounts of Fe and found that this ion is responsible for an intense resonance at g = 4 ,2 7 . More recent work in large crystalline fields includes the work on amethyst by Barry et al (1965), on ferrichrome 'A* by Wickman et al (1965) and on andalusite by Holuj (1 9 6 5 ). In the first two cases the results were interpreted as arising from a large E term in the spin Hamiltonian. In these cases the magnetic axes were not defined in the manner described on page 17, which accounts for E / B > | as observed by these workers.

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