292 research outputs found
Defocus test and defocus correction in full-field optical coherence tomography
We report experimental evidence and correction of defocus in full-field OCT
of biological samples due to mismatch of the refractive index of biological
tissues and water. Via a metric based on the image quality, we demonstrate that
we are able to compensate this index-induced defocus and to recover a sharp
image in depth.Comment: 7 pages, 3 figures, minor changes, 1 figure adde
Effects of Minijets on Hadronic Spectra and Azimuthal Harmonics in Au-Au Collisions at 200 GeV
The production of hadrons in heavy-ion collisions at RHIC in the low
transverse-momentum () region is investigated in the recombination model
with emphasis on the effects of minijets on the azimuthal anisotropy. Since the
study is mainly on the hadronization of partons at late time, the fluid picture
is not used to trace the evolution of the system. The inclusive distributions
at low are determined as the recombination products of thermal partons.
The dependencies of both pion and proton have a common exponential factor
apart from other dissimilar kinematic and resonance factors, because they are
inherited from the same pool of thermal partons. Instead of the usual
description based on hydrodynamics, the azimuthal anisotropy of the produced
hadrons is explained as the consequence of the effects of minijets, either
indirectly through the recombination of enhanced thermal partons in the
vicinity of the trajectories of the semihard partons, or directly through
thermal-shower recombination. Although our investigation is focussed on the
single-particle distribution at midrapidity, we give reasons why a component in
that distribution can be identified with the ridge, which together with the
second harmonic is due to the semihard partons created near the medium
surface that lead to calculable anisotropy in . It is shown that the
higher azimuthal harmonics, , can also be well reproduced without
reference to flow. The and centrality dependencies of the higher
harmonics are prescribed by the interplay between TT and TS recombination
components. The implication of the success of this drastic departure from the
conventional approach is discussed.Comment: 28 pages and 8 figures, more discussions and references adde
Phase Modulation at 125 kHz in a Michelson Interferometer Using an Inexpensive Piezoelectric Stack Driven at Resonance
Fast phase modulation has been achieved in a Michelson interferometer by attaching a lightweight reference mirror to a piezoelectric stack and driving the stack at a resonance frequency of about 125 kHz. The electrical behavior of the piezo stack and the mechanical properties of the piezo-mirror arrangement are described. A displacement amplitude at resonance of about 350 nm was achieved using a standard function generator. Phase drift in the interferometer and piezo wobble were readily circumvented. This approach to phase modulation is less expensive by a factor of roughly 50 than one based on an electro-optic effect
Paclitaxel Drug-Coated Balloon Angioplasty Suppresses Progression and Inflammation of Experimental Atherosclerosis in Rabbits
Paclitaxel drug-coated balloons (DCBs) reduce restenosis, but their overall safety has recently raised concerns. This study hypothesized that DCBs could lessen inflammation and reduce plaque progression. Using 25 rabbits with cholesterol feeding- and balloon injury-induced lesions, DCB-percutaneous transluminal angioplasty (PTA), plain PTA, or sham-PTA (balloon insertion without inflation) was investigated using serial intravascular near-infrared fluorescence−optical coherence tomography and serial intravascular ultrasound. In these experiments, DCB-PTA reduced inflammation and plaque burden in nonobstructive lesions compared with PTA or sham-PTA. These findings indicated the potential for DCBs to serve safely as regional anti-atherosclerosis therapy
Distensibility of Small Pulmonary Blood Vessels 1
Although vasomotor activity in small pulmonary vessels has been studied extensively in the past, using the concept of resistance to flow, information on the distensibility of these vessels is very sparse. In Introduction The concept of resistance to flow has been extensively used in the past to study vasomotion in the pulmonary vascular bed of man and animals. These previous studies have provided useful information on the responses of the small pulmonary vessels (i.e., pulmonary "resistance" vessels) in various disease states and/or during administration of various drug
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