368 research outputs found
Magnons and electromagnons in a spin-lattice-coupled frustrated magnet CuFeO2 as seen via inelastic neutron scattering
We have investigated spin-wave excitations in a four-sublattice (4SL)
magnetic ground state of a frustrated magnet CuFeO2, in which `electromagnon'
(electric-field-active magnon) excitation has been discovered by recent
terahertz time-domain spectroscopy [Seki et al. Phys. Rev. Lett. 105 097207
(2010)]. In previous study, we have identified two spin-wave branches in the
4SL phase by means of inelastic neutron scattering measurements under applied
uniaxial pressure. [T. Nakajima et al. J. Phys. Soc. Jpn. 80 014714 (2011) ] In
the present study, we have performed high-energy-resolution inelastic neutron
scattering measurements in the 4SL phase, resolving fine structures of the
lower-energy spin-wave branch near the zone center. Taking account of the
spin-driven lattice distortions in the 4SL phase, we have developed a model
Hamiltonian to describe the spin-wave excitations. The determined Hamiltonian
parameters have successfully reproduced the spin-wave dispersion relations and
intensity maps obtained in the inelastic neutron scattering measurements. The
results of the spin-wave analysis have also revealed physical pictures of the
magnon and electromagnon modes in the 4SL phase, suggesting that collinear and
noncollinear characters of the two spin-wave modes are the keys to understand
the dynamical coupling between the spins and electric dipole moments in this
system.Comment: 8 pages, 6 figure
Should prophylactic thrombolysis be routine in clinical practice? Evidence from an autopsy case of septicemia
BACKGROUND: Central venous catheters provide easy access for intravenous infusion and nutrition, but they can bring about complications such as catheter-related infections. Infected central venous catheters often cause nosocomial bloodstream infections with high morbidity and mortality. However, most of the morphological data that have been published are derived from in vitro and in vivo studies and few reports of direct evidence obtained from patient-derived samples have been described. Here we present visual evidence of catheter-related candidemia. To our knowledge, this is the first reported conventional histopathological evidence of a Candida-infected intraluminal thrombus in a patient’s central venous catheter. CASE PRESENTATION: A 62-year-old Japanese female with obstructive jaundice, gastrointestinal bleeding, and liver metastasis from pancreatic head cancer was given an implantable subcutaneous central venous port for nutrition and chemotherapy administration. High fever ensued on day 16 after the central venous port insertion and blood cultures revealed Candida albicans. Although the patient was given 300 mg/day of fosfluconazole according to the suggestion of the infection control team, she died from respiratory failure. Postmortem computed tomography revealed findings consistent with acute respiratory distress syndrome, suggesting that the patient’s course was complicated by catheter-related sepsis. Autopsy revealed a subcutaneous abscess around the port, from which C. albicans was cultured. However, no catheter-adherent thrombus, thrombosis of the great central veins, or endocardial vegetations were detected in the patient. Histological analysis revealed scattered abscesses in several organs including lungs and kidneys. Hyaline membrane formation and Candida colonies were found in the lungs. The central venous port tube, together with the part of the subclavian vein into which it had been inserted, was involved in an intraluminal fibrin thrombus containing neutrophils and macrophages, indicating that the thrombus existed while the patient was alive. Histopathological examination following use of the periodic acid-Schiff reagent and the Grocott stain revealed scattered Candida in the thrombus. CONCLUSIONS: Prophylactic thrombolysis should be encouraged to prevent central venous catheter-related candidiasis in clinical practice
High-Pressure Suppression of Long Range Magnetic Order in the Triangular Lattice Antiferromagnet CuFeO2
We succeeded in observing pressure-suppressed magnetic long range ordering
(LRO) in the triangular lattice antiferromagnet CuFeO, using neutron
diffraction experiments under an isotropic pressure. The magnetic LRO of the
four-sublattice ground state under ambient pressure in CuFeO almost
disappears at the high pressure of 7.9 GPa, and is replaced by an
incommensurate order with temperature-independent wave number of (0.192 0.192
1.5). The incommensurate wave number observed at 7.9 GPa corresponds to that
observed just above the temperature at which lattice distortion and magnetic
LRO simultaneously occur under ambient pressure. Therefore, the long-range
magnetic ordering disappears because the high pressure suppressed the lattice
distortion that otherwise relieves spin frustration and leads the spin system
to LRO.Comment: 4 pages, 3 figure
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