9 research outputs found
Optical force-induced nonlinearity and self-guiding of light in human red blood cell suspensions
Osmotic conditions play an important role in the cell properties of human red
blood cells (RBCs), which are crucial for the pathological analysis of some
blood diseases such as malaria. Over the past decades, numerous efforts have
mainly focused on the study of the RBC biomechanical properties that arise from
the unique deformability of erythrocytes. Here, we demonstrate nonlinear
optical effects from human RBCs suspended in different osmotic solutions.
Specifically, we observe self-trapping and scattering-resistant nonlinear
propagation of a laser beam through RBC suspensions under all three osmotic
conditions, where the strength of the optical nonlinearity increases with
osmotic pressure on the cells. This tunable nonlinearity is attributed to
optical forces, particularly the forward scattering and gradient forces.
Interestingly, in aged blood samples (with lysed cells), a notably different
nonlinear behavior is observed due to the presence of free hemoglobin. We use a
theoretical model with an optical force-mediated nonlocal nonlinearity to
explain the experimental observations. Our work on light self-guiding through
scattering bio-soft-matter may introduce new photonic tools for noninvasive
biomedical imaging and medical diagnosis.Comment: 20 Pages, 5 figures, accepted for publication in Light, Science &
Applicatio
A Search for Extended Ultraviolet Disk (XUV-disk) Galaxies in the Local Universe
We have initiated a search for extended ultraviolet disk (XUV-disk) galaxies
in the local universe. Herein, we compare GALEX UV and visible--NIR images of
189 nearby (D40 Mpc) S0--Sm galaxies included in the GALEX Atlas of Nearby
Galaxies and present the first catalogue of XUV-disk galaxies. We find that
XUV-disk galaxies are surprisingly common but have varied relative (UV/optical)
extent and morphology. Type~1 objects (\ga20% incidence) have structured,
UV-bright/optically-faint emission features in the outer disk, beyond the
traditional star formation threshold. Type~2 XUV-disk galaxies (10%
incidence) exhibit an exceptionally large,
UV-bright/optically-low-surface-brightness (LSB) zone having blue
outside the effective extent of the inner, older stellar population, but not
reaching extreme galactocentric distance. If the activity occuring in XUV-disks
is episodic, a higher fraction of present-day spirals could be influenced by
such outer disk star formation. Type~1 disks are associated with spirals of all
types, whereas Type~2 XUV-disks are predominantly found in late-type spirals.
Type~2 XUV-disks are forming stars quickly enough to double their [presently
low] stellar mass in the next Gyr (assuming a constant SF rate). XUV-disk
galaxies of both types are systematically more gas-rich than the general galaxy
population. Minor external perturbation may stimulate XUV-disk incidence, at
least for Type~1 objects. XUV-disks are the most actively evolving galaxies
growing via inside-out disk formation in the current epoch, and may constitute
a segment of the galaxy population experiencing significant, continued gas
accretion from the intergalactic medium or neighboring objects.Comment: 83 pages, 16 figures, 2 tables. Appearing in the GALEX special issue
of ApJS. (A version with high quality figures and proof corrections can be
found at http://www.journals.uchicago.edu/toc/apjs/173/2
The 2MASS Redshift Survey - Description and Data Release
We present the results of the 2MASS Redshift Survey (2MRS), a ten-year
project to map the full three-dimensional distribution of galaxies in the
nearby Universe. The 2 Micron All-Sky Survey (2MASS) was completed in 2003 and
its final data products, including an extended source catalog (XSC), are
available on-line. The 2MASS XSC contains nearly a million galaxies with Ks <=
13.5 mag and is essentially complete and mostly unaffected by interstellar
extinction and stellar confusion down to a galactic latitude of |b|=5 deg for
bright galaxies. Near-infrared wavelengths are sensitive to the old stellar
populations that dominate galaxy masses, making 2MASS an excellent starting
point to study the distribution of matter in the nearby Universe.
We selected a sample of 44,599 2MASS galaxies with Ks =5
deg (>= 8 deg towards the Galactic bulge) as the input catalog for our survey.
We obtained spectroscopic observations for 11,000 galaxies and used
previously-obtained velocities for the remainder of the sample to generate a
redshift catalog that is 97.6% complete to well-defined limits and covers 91%
of the sky. This provides an unprecedented census of galaxy (baryonic mass)
concentrations within 300 Mpc.
Earlier versions of our survey have been used in a number of publications
that have studied the bulk motion of the Local Group, mapped the density and
peculiar velocity fields out to 50 Mpc, detected galaxy groups, and estimated
the values of several cosmological parameters.
Additionally, we present morphological types for a nearly-complete sub-sample
of 20,860 galaxies with Ks = 10 deg.Comment: Accepted for publication in The Astrophysical Journal Supplement
Series. The 2MRS catalogs and a version of the paper with higher-resolution
figures can be found at http://tdc-www.harvard.edu/2mrs
Recommended from our members
Optical force-induced nonlinearity and self-guiding of light in human red blood cell suspensions.
Osmotic conditions play an important role in the cell properties of human red blood cells (RBCs), which are crucial for the pathological analysis of some blood diseases such as malaria. Over the past decades, numerous efforts have mainly focused on the study of the RBC biomechanical properties that arise from the unique deformability of erythrocytes. Here, we demonstrate nonlinear optical effects from human RBCs suspended in different osmotic solutions. Specifically, we observe self-trapping and scattering-resistant nonlinear propagation of a laser beam through RBC suspensions under all three osmotic conditions, where the strength of the optical nonlinearity increases with osmotic pressure on the cells. This tunable nonlinearity is attributed to optical forces, particularly the forward-scattering and gradient forces. Interestingly, in aged blood samples (with lysed cells), a notably different nonlinear behavior is observed due to the presence of free hemoglobin. We use a theoretical model with an optical force-mediated nonlocal nonlinearity to explain the experimental observations. Our work on light self-guiding through scattering bio-soft-matter may introduce new photonic tools for noninvasive biomedical imaging and medical diagnosis
Optical force-induced nonlinearity and self-guiding of light in human red blood cell suspensions
Osmotic conditions play an important role in the cell properties of human red blood cells (RBCs), which are crucial for the pathological analysis of some blood diseases such as malaria. Over the past decades, numerous efforts have mainly focused on the study of the RBC biomechanical properties that arise from the unique deformability of erythrocytes. Here, we demonstrate nonlinear optical effects from human RBCs suspended in different osmotic solutions. Specifically, we observe self-trapping and scattering-resistant nonlinear propagation of a laser beam through RBC suspensions under all three osmotic conditions, where the strength of the optical nonlinearity increases with osmotic pressure on the cells. This tunable nonlinearity is attributed to optical forces, particularly the forward-scattering and gradient forces. Interestingly, in aged blood samples (with lysed cells), a notably different nonlinear behavior is observed due to the presence of free hemoglobin. We use a theoretical model with an optical force-mediated nonlocal nonlinearity to explain the experimental observations. Our work on light self-guiding through scattering bio-soft-matter may introduce new photonic tools for noninvasive biomedical imaging and medical diagnosis.Funding Agencies|NIH (USA); NSF (USA); ARO (USA); National Key R&D Program of China [2017YFA0303800]; National Natural Science Foundation of China [91750204, 11504184, 11604058]; NSERC; Canada Research Chair Program (Canada); Government of the Russian Federation through the ITMO Fellowship and Professorship Program [074-U 01]; 1000 Talents Sichuan Program in China</p
Light-Guiding in Red Blood Cell Suspensions
International audienceSpecial Issue: Optics in 201