4,968 research outputs found
Fluctuation Theorems of Brownian Particles Controlled by a Maxwell's Demon
We study the stochastic dynamics of Brownian particles in a heat bath and
subject to an active feedback control by an external, Maxwell's demon-like
agent. The agent uses the information of the velocity of a particle and reduces
its thermal agitation by applying a force. The entropy of the particle and the
heat bath as a whole, thus, reduces. Entropy pumping [Phys. Rev. Lett. 93,
120602 (2004)] quantifies the entropy reduction. We discover that the entropy
pumping has a dual role of work and heat contributing to free energy changes
and entropy production of the open-system with the feedback control.
Generalized Jarzynski equality and fluctuation theorems for work functional and
entropy production are developed with the presence of the entropy pumping.Comment: 4 page
Two-dimensional heterogeneous photonic bandedge laser
We proposed and realized a two-dimensional (2D) photonic bandedge laser
surrounded by the photonic bandgap. The heterogeneous photonic crystal
structure consists of two triangular lattices of the same lattice constant with
different air hole radii. The photonic crystal laser was realized by
room-temperature optical pumping of air-bridge slabs of InGaAsP quantum wells
emitting at 1.55 micrometer. The lasing mode was identified from its spectral
positions and polarization directions. A low threshold incident pump power of
0.24mW was achieved. The measured characteristics of the photonic crystal
lasers closely agree with the results of real space and Fourier space
calculations based on the finite-difference time-domain method.Comment: 14 pages, 4 figure
Sonographic Detection of Intrathyroidal Branchial Cleft Cyst: A Case Report
We report here on an extremely rare case of an intrathyroidal branchial cleft cyst. Intrathyroidal branchial cleft cyst is rare disease entity and it has nonspecific findings on sonography, so the diagnosis of the lesion is very difficult. However, during aspiration, if pus-like materials are aspirated from a thyroid cyst, we should consider the possibility of intrathyroidal branchial cleft cyst in the differential diagnosis
Insight into highly conserved H1 subtype-specific epitopes in influenza virus hemagglutinin
Influenza viruses continuously undergo antigenic changes with gradual accumulation of mutations in hemagglutinin (HA) that is a major determinant in subtype specificity. The identification of conserved epitopes within specific HA subtypes gives an important clue for developing new vaccines and diagnostics. We produced and characterized nine monoclonal antibodies that showed significant neutralizing activities against H1 subtype influenza viruses, and determined the complex structure of HA derived from a 2009 pandemic virus A/Korea/01/2009 (KR01) and the Fab fragment from H1-specific monoclonal antibody GC0587. The overall structure of the complex was essentially identical to the previously determined KR01 HA-Fab0757 complex structure. Both Fab0587 and Fab0757 recognize readily accessible head regions of HA, revealing broadly shared and conserved antigenic determinants among H1 subtypes. The beta-strands constituted by Ser110-Glu115 and Lys169-Lys170 form H1 epitopes with distinct conformations from those of H1 and H3 HA sites. In particular, Glu112, Glu115, Lys169, and Lys171 that are highly conserved among H1 subtype HAs have close contacts with HCDR3 and LCDR3. The differences between Fab0587 and Fab0757 complexes reside mainly in HCDR3 and LCDR3, providing distinct antigenic determinants specific for 1918 pdm influenza strain. Our results demonstrate a potential key neutralizing epitope important for H1 subtype specificity in influenza virus
Local Hall effect in hybrid ferromagnetic/semiconductor devices
We have investigated the magnetoresistance of ferromagnet-semiconductor
devices in an InAs two-dimensional electron gas system in which the magnetic
field has a sinusoidal profile. The magnetoresistance of our device is large.
The longitudinal resistance has an additional contribution which is odd in
applied magnetic field. It becomes even negative at low temperature where the
transport is ballistic. Based on the numerical analysis, we confirmed that our
data can be explained in terms of the local Hall effect due to the profile of
negative and positive field regions. This device may be useful for future
spintronic applications.Comment: 4 pages with 4 fugures. Accepted for publication in Applied Physics
Letter
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