4,365 research outputs found
Multiferroic properties of an \aa kermanite SrCoSiO single crystal in high magnetic fields
The magnetic and dielectric properties of \aa kermanite SrCoSiO
single crystals in high magnetic fields were investigated. We have observed
finite induced electric polarization along the c axis in high fields, wherein
all Co spins were forcibly aligned to the magnetic field direction. Existence
of the induced polarization in the spin-polarized state accompanied with the
finite slope in the magnetization curve suggests the possible role of the
orbital angular momenta in the excited states as its microscopic origin. The
emergence of the field-induced polarization without particular magnetic order
can be regarded as the magnetoelectric effects of the second order from the
symmetry point of view. A low magnetic field-driven electric polarization flip
induced by a rotating field, even at room temperature, has been successfully
demonstrated.Comment: 12 pages, 4 figure
Coffee inventory through orbital imagery
There are no author-identified significant results in this report
Anisotropic magnetic field responses of ferroelectric polarization in a trigonal multiferroic CuFe1-xAlxO2 (x=0.015)
We have investigated magnetic field dependences of a ferroelectric
incommensurate-helimagnetic order in a trigonal magneto-electric (ME)
multiferroic CuFe1-xAlxO2 with x=0.015, which exhibits the ferroelectric phase
as a ground state, by means of neutron diffraction, magnetization and
dielectric polarization measurements under magnetic fields applied along
various directions. From the present results, we have established the H-T
magnetic phase diagrams for the three principal directions of magnetic fields;
(i) parallel to the c axis, (ii) parallel to the helical axis, and (iii)
perpendicular to the c and the helical axes. While the previous dielectric
polarization (P) measurements on CuFe1-xGaxO2 with x=0.035 have demonstrated
that the magnetic field dependence of the `magnetic domain structure' results
in distinct magnetic field responses of P [S. Seki et al., Phys. Rev. Lett.,
103 237601 (2009)], the present study have revealed that the anisotropic
magnetic field dependence of the ferroelectric helimagnetic order `in each
magnetic domain' can be also a source of a variety of magnetic field responses
of P in CuFe1-xAxO2 systems (A=Al, Ga).Comment: 11 pages, 9 figures, accepted for publication in Phys. Rev.
Mevastatin reduces cartilage degradation in rabbit experimental osteoarthritis through inhibition of synovial inflammation
SummaryObjectiveTo examine the therapeutic efficacy of an HMG-CoA reductase inhibitor (statin) in rabbit osteoarthritis (OA) in vitro and in vivo.MethodsIn the presence or absence of mevastatin, rabbit chondrocytes and synoviocytes were incubated with Interleukin-1β (IL-1β), and analyzed by biochemical methods. Thirty-two mature rabbits that underwent bilateral anterior cruciate ligament transaction (ACLT) received six consecutive weekly intra-articular injections of mevastatin at three different concentrations or a control solution. All animals were sacrificed 6 weeks after ACLT, and the knee joints were assessed by morphological, histological, immunohistochemical, and biochemical methods.ResultsMevastatin inhibited IL-1β stimulation of gene expression of monocyte chemoattractant protein-1 (MCP-1) and matrix-metalloproteinases 3 (MMP-3), in synoviocytes but not chondrocytes. The levels of MCP-1 and MMP-3 productions in synoviocytes were significantly reduced by statin-treatment. In rabbit with OA, intra-articular injection of mevastatin significantly reduced cartilage degradation, as assessed by morphological and histological examinations. Synovial tissues of knees treated with mevastatin showed less severe inflammatory responses with reduced thickness of synovial cell lining and less infiltration of subsynovial CD68+monocyte lineage cells compared to untreated control knees. Relative mRNA expressions of MCP-1, IL-1β, MMP-3, and MMP-13 were reduced in synovial tissues, but not articular cartilage, of knees treated with mevastatin compared with untreated control knees.ConclusionDuring the development of experimental OA, intra-articular administration of HMG-CoA reductase inhibitor (statin) reduces inflammatory cell infiltration and matrix-degrading enzyme expression, thus limiting cartilage degradation
A geometrical approach to N=2 super Yang-Mills theory on the two dimensional lattice
We propose a discretization of two dimensional Euclidean Yang-Mills theories
with N=2 supersymmetry which preserves exactly both gauge invariance and an
element of supersymmetry. The approach starts from the twisted form of the
continuum super Yang Mills action which we show may be written in terms of two
real Kahler-Dirac fields whose components transform into each other under the
twisted supersymmetry. Once the theory is written in this geometrical language
it is straightforward to discretize by mapping the component tensor fields to
appropriate geometrical structures in the lattice and by replacing the
continuum exterior derivative and its adjoint by appropriate lattice covariant
difference operators. The lattice action is local and possesses a unique vacuum
state while the use of Kahler-Dirac fermions ensures the model does not exhibit
spectrum doubling.Comment: Minor typos fixed. Version to be published in JHE
Improvement in Cryogenic Stability of the Model Coil of the LHD Helical Coil by Lowering the Temperature
Helical coils of the Large Helical Device are pool-cooled superconducting magnets, in which propagation of a normal-zone has been observed several times at about 86% of the nominal current of 13.0 kA. It is planned to improve the cryogenic stability by lowering the inlet temperature. In order to estimate the effect, the cryogenic stability of a model coil of the helical coil was examined in saturated and subcooled helium. Liquid helium is supplied from the bottom of the model coil, and it is exhausted through the winding to the current-leads tank. The inlet helium is subcooled by a pre-cooler. A normal zone was initiated by a heater on the conductor at the bottom of the coil. In saturated helium of 4.4 K and 0.12 MPa, the minimum current to propagate over the next turn varies from 10.7 to 11.2 kA in the four cases that are without or with additional thermal shields, and before or after being subcooled. The difference is considered to be caused by the change of quality of saturated helium inside the winding or by the change of the wetted condition of the conductor surface. The minimum currents are higher at the lower temperatures in subcooled helium. It is raised up to 11.7 kA at 3.5 K of the temperature inside the winding. The propagation velocity at each minimum current is almost same. Namely, the propagation velocities at the same current are slower at the lower temperature in subcooled heliu
On the frequency and remnants of Hypernovae
Under the hypothesis that some fraction of massive stellar core collapses
give rise to unusually energetic events, termed hypernovae, I examine the
required rates assuming some fraction of such events yield gamma ray bursts. I
then discuss evidence from studies of pulsars and r-process nucleosynthesis
that independently suggests the existence of a class of unusually energetic
events. Finally I describe a scenario which links these different lines of
evidence as supporting the hypernova hypothesis.Comment: TeX, To appear in ApJ Letter
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