7,210 research outputs found
Structured illumination microscopy with unknown patterns and a statistical prior
Structured illumination microscopy (SIM) improves resolution by
down-modulating high-frequency information of an object to fit within the
passband of the optical system. Generally, the reconstruction process requires
prior knowledge of the illumination patterns, which implies a well-calibrated
and aberration-free system. Here, we propose a new \textit{algorithmic
self-calibration} strategy for SIM that does not need to know the exact
patterns {\it a priori}, but only their covariance. The algorithm, termed
PE-SIMS, includes a Pattern-Estimation (PE) step requiring the uniformity of
the sum of the illumination patterns and a SIM reconstruction procedure using a
Statistical prior (SIMS). Additionally, we perform a pixel reassignment process
(SIMS-PR) to enhance the reconstruction quality. We achieve 2 better
resolution than a conventional widefield microscope, while remaining
insensitive to aberration-induced pattern distortion and robust against
parameter tuning
Thermoelectric Transport in Holographic Quantum Matter under Shear Strain
We study the thermoelectric transport under shear strain in two spatial
dimensional quantum matter using the holographic duality. General analytic
formulae for the DC thermoelectric conductivities subjected to finite shear
strain are obtained in terms of the black hole horizon data. Off-diagonal terms
in the conductivity matrix appear also at zero magnetic field, resembling an
emergent electronic nematicity which cannot nevertheless be identified with the
presence of an anomalous Hall effect. For an explicit model study, we
numerically construct a family of strained black holes and obtain the
corresponding nonlinear stress-strain curves. We then compute all electric,
thermoelectric, and thermal conductivities and discuss the effects of strain.
While the shear elastic deformation does not affect the temperature dependence
of thermoelectric and thermal conductivities quantitatively, it can strongly
change the behavior of the electric conductivity. For both shear hardening and
softening cases, we find a clear metal-insulator transition driven by the shear
deformation. Moreover, the violation of the previously conjectured thermal
conductivity bound is observed for large shear deformation.Comment: 35 pages, 13 figure
Computational illumination for high-speed in vitro Fourier ptychographic microscopy
We demonstrate a new computational illumination technique that achieves large
space-bandwidth-time product, for quantitative phase imaging of unstained live
samples in vitro. Microscope lenses can have either large field of view (FOV)
or high resolution, not both. Fourier ptychographic microscopy (FPM) is a new
computational imaging technique that circumvents this limit by fusing
information from multiple images taken with different illumination angles. The
result is a gigapixel-scale image having both wide FOV and high resolution,
i.e. large space-bandwidth product (SBP). FPM has enormous potential for
revolutionizing microscopy and has already found application in digital
pathology. However, it suffers from long acquisition times (on the order of
minutes), limiting throughput. Faster capture times would not only improve
imaging speed, but also allow studies of live samples, where motion artifacts
degrade results. In contrast to fixed (e.g. pathology) slides, live samples are
continuously evolving at various spatial and temporal scales. Here, we present
a new source coding scheme, along with real-time hardware control, to achieve
0.8 NA resolution across a 4x FOV with sub-second capture times. We propose an
improved algorithm and new initialization scheme, which allow robust phase
reconstruction over long time-lapse experiments. We present the first FPM
results for both growing and confluent in vitro cell cultures, capturing videos
of subcellular dynamical phenomena in popular cell lines undergoing division
and migration. Our method opens up FPM to applications with live samples, for
observing rare events in both space and time
Removal of sulfamethoxazole and sulfapyridine by carbon nanotubes in fixed-bed columns
Sulfamethoxazole (SMX) and sulfapyridine (SPY), two representative sulfonamide antibiotics, have gained increasing attention because of the ecological risks these substances pose to plants, animals, and humans. This work systematically investigated the removal of SMX and SPY by carbon nanotubes (CNTs) in fixed-bed columns under a broad range of conditions including: CNT incorporation method, solution pH, bed depth, adsorbent dosage, adsorbate initial concentration, and flow rate. Fixed-bed experiments showed that pH is a key factor that affects the adsorption capacity of antibiotics to CNTs. The Bed Depth Service Time model describes well the relationship between service time and bed depth and can be used to design appropriate column parameters. During fixed-bed regeneration, small amounts of SMX (3%) and SPY (9%) were irreversibly bonded to the CNT/sand porous media, thus reducing the column capacity for subsequent reuse from 67.9 to 50.4 mg g−1 for SMX and from 91.9 to 72.9 mg g−1 for SPY. The reduced column capacity resulted from the decrease in available adsorption sites and resulting repulsion (i.e., blocking) of incoming antibiotics from those previously adsorbed. Findings from this study demonstrate that fixed-bed columns packed with CNTs can be efficiently used and regenerated to remove antibiotics from water
BiRA-Net: Bilinear Attention Net for Diabetic Retinopathy Grading
Diabetic retinopathy (DR) is a common retinal disease that leads to
blindness. For diagnosis purposes, DR image grading aims to provide automatic
DR grade classification, which is not addressed in conventional research
methods of binary DR image classification. Small objects in the eye images,
like lesions and microaneurysms, are essential to DR grading in medical
imaging, but they could easily be influenced by other objects. To address these
challenges, we propose a new deep learning architecture, called BiRA-Net, which
combines the attention model for feature extraction and bilinear model for
fine-grained classification. Furthermore, in considering the distance between
different grades of different DR categories, we propose a new loss function,
called grading loss, which leads to improved training convergence of the
proposed approach. Experimental results are provided to demonstrate the
superior performance of the proposed approach.Comment: Accepted at ICIP 201
Review on Electrical Installations and Lightning Protection Measures for High-rise Building
Lightning protection technology is widely used in electrical construction industry by protecting the buildings and its internal electrical infrastructure. Further researches on lightning protection technology are crucial due to the complexity of high-rise building internal electrical design and existence of some problem in current lightning protection technology. Lightning protection system will be more mature along with the development of technology, contributing to better prevention, ensures the safety of people’s lives and reduce the impact of economic loss caused by lightning. This article will focus on the analysis of electrical installations and lightning protection measures of high-rise building for future references
Breaking rotations without violating the KSS viscosity bound
We revisit the computation of the shear viscosity to entropy ratio in a
holographic p-wave superfluid model, focusing on the role of rotational
symmetry breaking. We study the interplay between explicit and spontaneous
symmetry breaking and derive a simple horizon formula for , which is
valid also in the presence of explicit breaking of rotations and is in perfect
agreement with the numerical data. We observe that a source which explicitly
breaks rotational invariance suppresses the value of in the broken
phase, competing against the effects of spontaneous symmetry breaking. However,
always reaches a constant value in the limit of zero temperature,
which is never smaller than the Kovtun-Son-Starinets (KSS) bound, .
This behavior appears to be in contrast with previous holographic anisotropic
models which found a power-law vanishing of at small temperature. This
difference is shown to arise from the properties of the near-horizon geometry
in the extremal limit. Thus, our construction shows that the breaking of
rotations itself does not necessarily imply a violation of the KSS bound.Comment: 20 pages, 7 figure
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