1,778 research outputs found
Magnon topology and thermal Hall effect in trimerized triangular lattice antiferromagnet
The non-trivial magnon band topology and its consequent responses have been
extensively studied in two-dimensional magnetisms. However, the triangular
lattice antiferromagnet (TLAF), the best-known frustrated two-dimensional
magnet, has received less attention than the closely related Kagome system,
because of the spin-chirality cancellation in the umbrella ground state of the
undistorted TLAF. In this work, we study the band topology and the thermal Hall
effect (THE) of the TLAF with (anti-)trimerization distortion under the
external perpendicular magnetic field using the linearized spin wave theory. We
show that the spin-chirality cancellation is removed in such case, giving rise
to the non-trivial magnon band topology and the finite THE. Moreover, the
magnon bands exhibit band topology transitions tuned by the magnetic field. We
demonstrate that such transitions are accompanied by the logarithmic divergence
of the first derivative of the thermal Hall conductivity. Finally, we examine
the above consequences by calculating the THE in the hexagonal manganite
YMnO, well known to have anti-trimerization.Comment: 6 + 7 pages, 3 + 5 figures, 0 + 1 table; Journal reference adde
The widths of quarkonia in quark gluon plasma
Recent lattice calculations showed that the quarkonia will survive beyond the
phase transition temperature, and will dissolve at different temperatures
depending on the type of the quarkonium. In this work, we calculate the thermal
width of the quarkonium at finite temperature before it dissolves into open
heavy quarks. The input of the calculation are the parton quarkonium
dissociation cross section to NLO in QCD, the quarkonium wave function in a
temperature-dependent potential from lattice QCD, and a thermal distribution of
partons with thermal masses. We find that for the J/psi, the total thermal
width above 1.4 Tc becomes larger than 100 to 250 MeV, depending on the
effective thermal masses of the quark and gluon, which we take between 400 to
600 MeV. Such a width corresponds to an effective dissociation cross section by
gluons between 1.5 to 3.5 mb and by quarks 1 to 2 mb at 1.4 Tc. However, at
similar temperatures, we find a much smaller thermal width and effective cross
section for the upsilon.Comment: 7 pages, 13 figures, 2 tables, version to be published in Phys. Rev.
Use of Inhaled Iloprost in an Infant With Bronchopulmonary Dysplasia and Pulmonary Artery Hypertension
Pulmonary artery hypertension is a common cardiovascular complication in preterm infants with bronchopulmonary dysplasia which is associated with increased morbidity and mortality. Inhaled iloprost is used as a therapeutic option in pulmonary hypertension, especially in adults. There have been but a few reports on the use of iloprost for neonates and infants. We report the case of a 5 month-old-male infant who received neonatal intensive care for 4 months due to respiratory distress syndrome and prematurity, during which he developed bronchopulmonary dysplasia. Echocardiography showed severe pulmonary hypertension. The initial treatment included respiratory support with high frequency oscillatory ventilation (HFOV); however, his clinical condition did not improve. Inhaled iloprost with sildenafil, an oral phosphodiesterase-5 inhibitor, was thus used. With the administration of iloprost and sildenafil, his condition improved and he was weaned from oxygen. Our clinical experience suggests that iloprost is a promising therapy for pulmonary hypertension, especially when inhaled nitric oxide is unavailable
J/psi hadron interaction in vacuum and in QGP
Motivated by the recent lattice data that will survive up to
1.6, we calculate the thermal width of at finite temperature in
perturbative QCD. The inputs of the calculation are the parton quarkonium
dissociation cross sections at the NLO in QCD, which were previously obtained
by Song and Lee, and a gaussian charmonium wave function, whose size were
fitted to an estimate by Wong by solving the schrodinger equation for
charmonium in a potential extracted from the lattice at finite temperature. We
find that the total thermal width above 1.4 becomes larger than 100 to 200
MeV, depending on the effective thermal masses of the quark and gluon, which we
take it to vary from 600 to 400 MeV.Comment: 4 pages, Talk at Quark Matter 200
Quantum Optical Induced-Coherence Tomography by a Hybrid Interferometer
Quantum interferometry based on induced-coherence phenomena has demonstrated
the possibility of undetected-photon measurements. Perturbation in the optical
path of probe photons can be detected by interference signals generated by
quantum mechanically correlated twin photons propagating through a different
path, possibly at a different wavelength. To the best of our knowledge, this
work demonstrates for the first time a hybrid-type induced-coherence
interferometer that incorporates a Mach-Zehnder-type interferometer for visible
photons and a Michelson-type interferometer for infrared photons, based on
double-pass pumped spontaneous parametric down-conversion. This configuration
enables infrared optical measurements via the detection of near-visible photons
and provides methods for characterizing the quality of measurements by
identifying photon pairs of different origins. The results verify that the
induced-coherence interference visibility is approximately the same as the
heralding efficiencies between twin photons along the relevant spatial modes.
Applications to both time-domain and frequency-domain quantum-optical
induced-coherence tomography for three-dimensional test structures are
demonstrated. The results prove the feasibility of practical undetected-photon
sensing and imaging techniques based on the presented structure
Measurement of the Background Activities of a 100Mo-enriched powder sample for AMoRE crystal material using a single high purity germanium detector
The Advanced Molybdenum-based Rare process Experiment (AMoRE) searches for
neutrino-less double-beta (0{\nu}\b{eta}\b{eta}) decay of 100Mo in enriched
molybdate crystals. The AMoRE crystals must have low levels of radioactive
contamination to achieve low background signals with energies near the Q-value
of the 100Mo 0{\nu}\b{eta}\b{eta} decay. To produce low-activity crystals,
radioactive contaminants in the raw materials used to form the crystals must be
controlled and quantified. 100EnrMoO3 powder, which is enriched in the 100Mo
isotope, is of particular interest as it is the source of 100Mo in the
crystals. A high-purity germanium detector having 100% relative efficiency,
named CC1, is being operated in the Yangyang underground laboratory. Using CC1,
we collected a gamma spectrum from a 1.6-kg 100EnrMoO3 powder sample enriched
to 96.4% in 100Mo. Activities were analyzed for the isotopes 228Ac, 228Th,
226Ra, and 40K. They are long-lived naturally occurring isotopes that can
produce background signals in the region of interest for AMoRE. Activities of
both 228Ac and 228Th were < 1.0 mBq/kg at 90% confidence level (C.L.). The
activity of 226Ra was measured to be 5.1 \pm 0.4 (stat) \pm 2.2 (syst) mBq/kg.
The 40K activity was found as < 16.4 mBq/kg at 90% C.L.Comment: 20 pages, 6 figures, 5 table
Elimination of Chrysanthemum stunt viroid (CSVd) from Meristem Tip Culture Combined with Prolonged Cold Treatment
Chrysanthemum production in Korea has recently been greatly affected by the spread of Chrysanthemum stunt viroid (CSVd) infection, necessitating the use of CSVd-free stocks to ensure successful chrysanthemum cultivation. We investigated the effects of low temperature (4°C), antiviral chemicals (ribavirin and amantadine) and a combination of these treatments on CSVd elimination by meristem tip cultures using plantlets that originated from CSVd-infected chrysanthemum ‘Ency’. Neither antiviral agents led to CSVd elimination, despite the suppression of meristem tip growth in a concentration dependent manner. However, the CSVd elimination rate increased up to 42.8% when meristem tips were excised after storage at 4°C for two months. The most effective results were obtained from a combination of low temperature for three months at 4°C followed by meristem tip culture on media containing 50 and 100 mgL-1 ribavirin. These results suggest that antiviral agents can also be useful for CSVd elimination if their treatment is combined with prolonged periods of low temperature. This is the first report of eradication of viroids from spray type chrysanthemum bred in Korea
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