Biomedical subjects

Eun-Ah Kim

Publications and source records attributed to Eun-Ah Kim.

6 recordsLinked to original sources

PubMed2006

Aharanov-Bohm interference and fractional statistics in a quantum Hall interferometer.

We compute the temperature, voltage, and magnetic field dependences of the conductance oscillations of a model interferometer designed to measure the fractional statistics of the quasiparticles in the fractional quantum Hall effect. The geometry is the same as that used in recent experiments. With appropriate assumptions concerning the relative areas of the inner and outer rings of the interferometer, we find the theoretical results, including the existence of super periodic Aharonov-Bohm oscillations, to be in remarkably good agreement with experiment. We then make additional experimental predictions with no adjustable parameters which, if verified, would confirm the proposed interpretation of the experiment as a measurement of fractional statistics.

Journal Article↗

PubMed2005

Signatures of fractional statistics in noise experiments in quantum Hall fluids.

The elementary excitations of fractional quantum Hall (FQH) fluids are vortices with fractional statistics. Yet, this fundamental prediction has remained an open experimental challenge. Here we show that the cross-current noise in a three-terminal tunneling experiment of a two dimensional electron gas in the FQH regime can be used to detect directly the statistical angle of the excitations of these topological quantum fluids. We show that the noise also reveals signatures of exclusion statistics and of fractional charge. The vortices of Laughlin states should exhibit a bunching effect, while for higher states in the Jain sequences they should exhibit an "antibunching" effect.

Journal Article↗

PubMed2005

Rat model of platelet-activating factor-induced rhinosinusitis.

Platelet-activating factor (PAF) is known to be a potent inflammatory mediator, especially in allergic inflammation. However, the exact role of PAF in the pathogenesis of rhinosinusitis has not been clearly established. To understand the role of PAF in the pathogenesis of rhinosinusitis, it is necessary to develop an animal model of PAF-induced rhinosinusitis. The aim of this study was to develop a rat model of rhinosinusitis induced by intranasally applied PAF. Fifty microliters of 16 microg/mL PAF was applied intranasally through each naris in 4-week-old Sprague-Dawley rats, and the same amount of vehicle was applied in control rats. At 1, 3, or 5 days, the animals were painlessly sacrificed, and the nasal cavity and sinuses were prepared for histologic investigation. The histologic sections were examined in a blind manner for the appearance of neutrophil clusters in the sinonasal air space, and the numbers of eosinophils, areas of epithelial loss, goblet cells, and inducible nitric oxide synthase (iNOS)-positive inflammatory cells in the mucosa. Neutrophil clusters were observed in the air space, and the number of eosinophils, areas of epithelial loss, goblet cells, and iNOS-positive inflammatory cells in the mucosa were increased significantly in the PAF-applied rats. The amount of inflammation varied according to the time interval, showing a peak at day 3. We conclude that intranasally applied PAF induces rhinosinusitis in rats. The histologic evidence of rhinosinusitis revealed the appearance of neutrophil clusters in the sinonasal air space, infiltration of eosinophils and iNOS-positive inflammatory cells in the mucosa, areas of epithelial loss, and goblet cell hyperplasia in the epithelium. This rat model of PAF-induced rhinosinusitis may be applied for better understanding of the role of PAF in the pathogenesis of rhinosinusitis.

Administration, Intranasal↗

PubMed2005

Fibrovascularization of intraorbital hydroxyapatite-coated alumina sphere in rabbits.

We investigated the fibrovascular ingrowth and fibrovascular tissue maturation of hydroxyapatite-coated, porous alumina sphere (Alumina sphere) in comparison with the hydroxyapatite sphere (HAp sphere) in rabbits. Alumina spheres and HAp spheres were implanted in the left orbits of 42 New Zealand white rabbits after enucleation. Fibrovascular ingrowth and maturation were graded from 1 to 5 at postoperative 1, 2, 3, 4, 8, 12 and 24 weeks. We defined 4 phases: postoperative 1-2 weeks as phase I, 3-4 weeks as phase II, 8-12 weeks as phase III, and 24 weeks as phase IV. The grade was analyzed at each phases. There was no significant difference in fibrovascular ingrowth and maturation between the two groups at all 4 phases, except phase II at which the Alumina sphere showed significantly lower maturation grade (p<0.05). We concluded that the Alumina sphere is an ideal orbital implant material and an ideal substitute for the HAp sphere in clinical practice.

Aluminum Oxide↗

PubMed2004

Cooper-pair tunneling in junctions of singlet quantum Hall States and superconductors.

We propose tunnel junctions of a Hall bar and a superconducting lead for observing Cooper-pair tunneling into singlet fractional quantum Hall edge states. These tunnel junctions provide a natural means of extracting precise information of the spin polarization and the filling factor of the state. The low energy regime of one of the setups is governed by a novel quantum entangled fixed point.

Journal Article↗

PubMed2003

Double point contact in quantum Hall line junctions.

We show that multiple point contacts on a barrier separating two laterally coupled quantum Hall fluids induce Aharonov-Bohm (AB) oscillations in the tunneling conductance. These quantum coherence effects provide new evidence for the Luttinger liquid behavior of the edge states of quantum Hall fluids. For a two point contact, we identify coherent and incoherent regimes determined by the relative magnitude of their separation and the temperature. We analyze both regimes in the strong and weak tunneling amplitude limits as well as their temperature dependence. We find that the tunneling conductance should exhibit AB oscillations in the coherent regime, both at strong and weak tunneling amplitudes with the same period but with different functional form.

Journal Article↗