نتایج جستجو برای: magnetic matter
تعداد نتایج: 540637 فیلتر نتایج به سال:
INTRODUCTION : Magnetic susceptibility difference between brain gray and white matter results in strong phase contrast between these two types of tissues at high magnetic field strength (1, 2). Here, we report, for the first time, a surprising observation of tissue-level magnetic susceptibility anisotropy in the central nervous system (CNS) using a mouse model. Specifically, we propose a method...
We propose that accretion can induce a neutron star magnetic field decay because the ferromagnetic accreted matter screens the magnetic field of neutron star. Our model results suggest that: (i) the surface magnetic field decay is inversely correlated with the accretion mass in the X-ray binary accretion phase as∆M−0.4, (ii) the ‘Bottom Field Strength ’ of about 108 G can occur when the accrete...
Neutron stars may harbor the true ground state of matter in the form of strange quark matter. If present, this type of matter is expected to be a color superconductor, a consequence of quark pairing with respect to the color and flavor degrees of freedom. The stellar magnetic field threading the quark core becomes a color-magnetic admixture and, in the event that superconductivity is of type II...
Susceptibility tensor imaging (STI) is a recently developed MRI technique that allows quantitative determination of orientation-independent magnetic susceptibility parameters from the dependence of gradient echo signal phase on the orientation of biological tissues with respect to the main magnetic field. By modeling the magnetic susceptibility of each voxel as a symmetric rank-2 tensor, indivi...
We combine the idea of movement of magnetic flux tubes in the stellar interiors with the analysis of crustal physics of accreting neutron stars in lowand high-mass X-ray binaries to explain the bimodal magnetic field distribution of binary pulsars. We propose that this distribution may result from different crustal properties of neutron stars with different accretion rates and amounts of accret...
We report on the formation of surface instabilities in a layer of thermoreversible ferrogel when exposed to a vertical magnetic field. Both static and time dependent magnetic fields are employed. Under variations of temperature, the viscoelastic properties of our soft magnetic matter can be tuned. Stress relaxation experiments unveil a stretched exponential scaling of the shear modulus, with an...
Previous authors have shown that the transverse relaxivity R(2)* and frequency shifts that characterize gradient echo signal decay in magnetic resonance imaging are closely associated with the distribution of iron and myelin in the brain's white matter. In multiple sclerosis, iron accumulation in brain tissue may reflect a multiplicity of pathological processes. Hence, iron may have the unique ...
In the presence of arbitrarily large magnetic fields, matter composed of electrons and nuclei was known to be unstable if α or Z is too large. Here we prove that matter is stable if α < 0.06 and Zα2 < 0.04. One of the remaining unsolved problems connected with the stability of matter is the inclusion of arbitrary magnetic fields. The model is a caricature of QED which invites speculations about...
There have been many searches for magnetic monopoles in ight, but few for monopoles in matter. We have searched for magnetic monopoles in meteorites, schists, ferromanganese nodules, iron ores and other materials. The detector was a superconducting induction coil connected to a SQUID (Superconducting Quantum Interference Device) with a room temperature bore 15 cm in diameter. We tested a total ...
Ageing is associated with cognitive decline, with some studies indicating that this decline can be mostly accounted for by slowing of information processing speed. Whilst it is likely that this is associated with age-related changes in fronto-subcortical neuronal circuits, such changes are not visible on routine neuroimaging. We examined the integrity of this brain region using proton magnetic ...
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