16 research outputs found
Successive phase transitions and phase diagrams of the quasi-two-dimensional triangular antiferromagnet Rb4Mn(MoO4)3
Comprehensive experimental studies by magnetic, thermal and neutron
measurements have clarified that Rb4Mn(MoO4)3 is a model system of a quasi-2D
triangular Heisenberg antiferromagnet with an easy-axis anisotropy, exhibiting
successive transitions across an intermediate collinear phase. As a rare case
for geometrically frustrated magnetism, quantitative agreement between
experiment and theory is found for complete, anisotropic phase diagrams as well
as magnetic properties.Comment: 4 pages, 5 figure
Gait instability, ophthalmoplegia, and chorea with orofacial dyskinesia in a man with anti-Ri antibodies: a case report
A 79-year-old man was admitted for 2 weeks of dizziness, followed by diplopia, involuntary movement and progressive gait disturbances. Neurologic examination revealed horizontal and vertical gaze paresis, bilateral choreiform movement with orofacial dyskinesia, and limb/truncal ataxia. MRI revealed fluid-attenuated inversion recovery image-hyperintense signal abnormalities in the dorsal midbrain, pontine and medulla. Within another few days, the patient developed type II acute respiratory failure requiring artificial invasive ventilation. Because autoimmune encephalitis was suspected, he received intravenous immunoglobulin therapy followed by intravenous methylprednisolone, but only his ophthalmoplegia improved minimally. Serological tests were positive for anti-Ri onconeural antibodies. CT-guided mediastinal lymph node biopsy was performed and revealed small cell lung carcinoma. We report the rare manifestation of anti-Ri antibody-associated paraneoplastic neurological syndrome (PNS), and this case can alert us to the importance of respiratory management in this diverse neurologic disease. Furthermore, PNSs positive for anti-Ri antibodies should be added to the list of differential diagnoses of chorea with orofacial dyskinesia
Spin dynamics and spin freezing behavior in the two-dimensional antiferromagnet NiGaS revealed by Ga-NMR, NQR and SR measurements
We have performed Ga nuclear magnetic resonance (NMR) and nuclear
quadrupole resonance (NQR) and muon spin rotation/resonance on the quasi
two-dimensional antiferromagnet (AFM) NiGaS, in order to investigate
its spin dynamics and magnetic state at low temperatures. Although there exists
only one crystallographic site for Ga in NiGaS, we found two distinct
Ga signals by NMR and NQR. The origin of the two Ga signals is not fully
understood, but possibly due to stacking faults along the c axis which induce
additional broad Ga NMR and NQR signals with different local symmetries. We
found the novel spin freezing occurring at , at which the specific
heat shows a maximum, from a clear divergent behavior of the nuclear
spin-lattice relaxation rate and nuclear spin-spin relaxation rate
measured by Ga-NQR as well as the muon spin relaxation rate
. The main sharp NQR peaks exhibit a stronger tendency of divergence,
compared with the weak broader spectral peaks, indicating that the spin
freezing is intrinsic in NiGaS. The behavior of these relaxation rates
strongly suggests that the Ni spin fluctuations slow down towards ,
and the temperature range of the divergence is anomalously wider than that in a
conventional magnetic ordering. A broad structureless spectrum and
multi-component were observed below 2 K, indicating that a static
magnetic state with incommensurate magnetic correlations or inhomogeneously
distributed moments is realized at low temperatures. However, the wide
temperature region between 2 K and , where the NQR signal was not
observed, suggests that the Ni spins do not freeze immediately below , but keep fluctuating down to 2 K with the MHz frequency range.Comment: 14 pages, 14 figures. To appear in Phys. Rev.
Current situation regarding lead exposure in birds in Japan (2015-2018); lead exposure is still occurring
Birds of a number of species have died as a result of lead (Pb) poisoning, including many Steller's sea eagles (Haliaeetus pelagicus) and white-tailed sea eagles (Haliaeetus albicilla) in Hokkaido, the northernmost island of Japan. To address this issue, the use of any type of Pb ammunition for hunting of large animals was prohibited in Hokkaido in 2004. However, Pb poisoning is still being reported in this area, and there are few regulations regarding the use of Pb ammunition in other parts of Japan, where it has been reported that eagles and water birds have been exposed to Pb. This study was performed to accurately determine the current level of Pb exposure of birds found dead in the field or dead in the wild bird centers in Japan (June 2015-May 2018) and to identify the sources of Pb. Pb exposure was found to still be occurring in raptors and water birds in various parts of Japan. Twenty-six point five % and 5.9% of the recorded deaths of Steller's sea eagles and white-tailed sea eagles, respectively, were found to have been poisoned by Pb. In addition, Pb isotope ratio analysis showed that both Pb rifle bullets and Pb shot pellets cause Pb exposure in birds, and these endangered eagles are also exposed to Pb in Hokkaido due to the illegal use of Pb ammunition. Changing to Pb-free ammunition, such as copper (Cu) rifle bullets, steel shot pellets, or bismuth shot pellets, will be essential for the conservation of avian species in Japan