12,598 research outputs found
Near-field spectroscopy of bimodal size distribution of InAs/AlGaAs quantum dots
We report on high-resolution photoluminescence (PL) spectroscopy of spatial
structure of InAs/AlGaAs quantum dots (QDs) by using a near-field scanning
optical microscope (NSOM). The double-peaked distribution of PL spectra is
clearly observed, which is associated with the bimodal size distribution of
single QDs. In particular, the size difference of single QDs, represented by
the doublet spectral distribution, can be directly observed by the NSOM images
of PL.Comment: 3pages, 3figue
Graft versus host disease (GVHD) after BN to LEW compared to LEW to BN rat intestinal transplantation under FK 506
Lymphocyte traffic and graft-versus-host disease after fully allogeneic small bowel transplantation
Controlling quasiparticle excitations in a trapped Bose-Einstein condensate
We describe an approach to quantum control of the quasiparticle excitations
in a trapped Bose-Einstein condensate based on adiabatic and diabatic changes
in the trap anisotropy. We describe our approach in the context of Landau-Zener
transition at the avoided crossings in the quasiparticle excitation spectrum.
We show that there can be population oscillation between different modes at the
specific aspect ratios of the trapping potential at which the mode energies are
almost degenerate. These effects may have implications in the expansion of an
excited condensate as well as the dynamics of a moving condensate in an atomic
wave guide with a varying width
Bell inequality for pairs of particle-number-superselection-rule restricted states
Proposals for Bell inequality tests on systems restricted by superselection
rules often require operations that are difficult to implement in practice. In
this paper, we derive a new Bell inequality, where pairs of states are used to
by-pass the superselection rule. In particular, we focus on mode entanglement
of an arbitrary number of massive particles and show that our Bell inequality
detects the entanglement in the pair when other inequalities fail. However, as
the number of particles in the system increases, the violation of our Bell
inequality decreases due to the restriction in the measurement space caused by
the superselection rule. This Bell test can be implemented using techniques
that are routinely used in current experiments.Comment: 9 pages, 6 figures; v2 is the published versio
Detection of volatile organic compounds (VOCs) using an optical fibre long period grating with a calixarene anchored mesoporous thin film
A long period grating (LPG) modified with a mesoporous film infused with a functional compound, calix[4]arene, was employed for the detection of volatile organic compounds (VOCs). The mesoporous film consisted of an inorganic part, of SiO2 nanoparticles (NPs) along with an organic moiety of poly(allylamine hydrochloride) polycation PAH, which was finally infused with functional compound, p-sulphanatocalix[4]arene (CA[4]). The LPG sensor was designed to operate at the phase matching turning point to provide the highest sensitivity. The sensing mechanism is based on the measurement of the refractive index (RI) change induced by the complexion of the VOCs with calix[4]arene (CA). The LPG modified with 5 cycles of (SiO2 NPs/PAH)5PAA responded to exposure to chloroform and benzene vapours. The sensitivity to humidity as an interfering parameter was also investigated
Dynamics of Helping Behavior and Networks in a Small World
To investigate an effect of social interaction on the bystanders'
intervention in emergency situations a rescue model was introduced which
includes the effects of the victim's acquaintance with bystanders and those
among bystanders from a network perspective. This model reproduces the
experimental result that the helping rate (success rate in our model) tends to
decrease although the number of bystanders increases. And the interaction
among homogeneous bystanders results in the emergence of hubs in a helping
network. For more realistic consideration it is assumed that the agents are
located on a one-dimensional lattice (ring), then the randomness
is introduced: the random bystanders are randomly chosen from a whole
population and the near bystanders are chosen in the nearest order to
the victim. We find that there appears another peak of the network density in
the vicinity of and due to the cooperative and competitive
interaction between the near and random bystanders.Comment: 13 pages, 8 figure
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