scholarly journals Improving Multiphoton Microscopy by Combining Spherical Aberration Patterns and Variable Axicons

Photonics ◽  
2021 ◽  
Vol 8 (12) ◽  
pp. 573
Author(s):  
Juan M. Bueno ◽  
Geovanni Hernández ◽  
Martin Skorsetz ◽  
Pablo Artal
Keyword(s):  
High Resolution ◽  
Spherical Aberration ◽  
Multiphoton Microscopy ◽  
Biological Tissues ◽  
Optical Sectioning ◽  
Established Method ◽  
Non Invasive ◽  
Microscopy Images ◽  
Better Than

Multiphoton (MP) microscopy is a well-established method for the non-invasive imaging of biological tissues. However, its optical sectioning capabilities are reduced due to specimen-induced aberrations. Both the manipulation of spherical aberration (SA) and the use of axicons have been reported to be useful techniques to bypass this limitation. We propose the combination of SA patterns and variable axicons to further improve the quality of MP microscopy images. This approach provides enhanced images at different depth locations whose quality is better than those corresponding to the use of SA or axicons separately. Thus, the procedure proposed herein facilitates the visualization of details and increases the depth observable at high resolution.

scholarly journals Comparison between ultra-high-resolution computed tomographic angiography and conventional computed tomographic angiography in the visualization of the subcallosal artery

2021 ◽  
Vol 12 ◽  
pp. 528
Author(s):  
Yoshimichi Sato ◽  
Toshiki Endo ◽  
Shingo Kayano ◽  
Hitoshi Nemoto ◽  
Kazuki Shimada ◽  
...  
Keyword(s):  
High Resolution ◽  
Evaluation Method ◽  
Computed Tomographic Angiography ◽  
Anterior Communicating Artery ◽  
Exact Test ◽  
Computed Tomographic ◽  
Small X ◽  
Tomographic Angiography ◽  
Better Than

Background: The subcallosal artery (ScA) is a single dominant artery arising from the anterior communicating artery. Its injury causes amnesia and cognitive disturbance. The conventional computed tomographic angiography (C-CTA) is a common evaluation method of the intracranial artery. However, to image tinny perforating arteries such as the ScA is technically demanding for C-CTA. The purpose of this study is to investigate whether the ultra-high-resolution CTA (UHR-CTA) could image the ScA better than C-CTA. UHR-CTA became available in clinical practice in 2017. Its novel features are the improvement of the detector system and a small X-ray focus. Methods: Between April 2019 and May 2020, 77 and 49 patients who underwent intracranial UHR-CTA and C-CTA, respectively, were enrolled in this study. Two board-certified neurosurgeons participated as observers to identify the ScA based on UHR-CTA and C-CTA images. Results: UHR-CTA and C-CTA detected the ScA in 56–58% and 30–40% of the patients, respectively. In visualization of the ScA, UHR-CTA was better than C-CTA (P < 0.05, Fisher’s exact test). Between the two observers, the Cohen’s kappa coefficient was 0.77 for UHR-CTA and 0.78 for C-CTA. Conclusions: UHR-CTA is a simple and accessible method to evaluate intracranial vasculature. Visualization of the ScA with UHR-CTA was better than that with C-CTA. The high quality of UHR-CTA could provide useful information in the neurosurgery field.

scholarly journals Non-invasive imaging of tau-targeted probe uptake by whole brain multi-spectral optoacoustic tomography

2021 ◽  
Author(s):  
Patrick Vagenknecht ◽  
Maiko Ono ◽  
Artur Luzgin ◽  
Bin Ji ◽  
Makoto Higuchi ◽  
...  
Keyword(s):  
High Resolution ◽  
Progressive Supranuclear Palsy ◽  
Brain Imaging ◽  
Ex Vivo ◽  
Multiphoton Microscopy ◽  
Corticobasal Degeneration ◽  
Alzheimers Disease ◽  
Whole Brain ◽  
Optoacoustic Tomography ◽  
Non Invasive

Aim: Abnormal tau accumulation plays an important role in tauopathy diseases such as Alzheimers disease and Frontotemporal dementia. There is a need for high-resolution imaging of tau deposits at the whole brain scale in animal models. Here, we demonstrate non-invasive whole brain imaging of tau-targeted PBB5 probe in P301L model of 4-repeat tau at 130 μm resolution using volumetric multi-spectral optoacoustic tomography (vMSOT). Methods: The binding properties of a panel of imaging probes to amyloid-β, 4-repeat K18 tau fibrils were assessed by using Thioflavin T assay and surface plasmon resonance assay. We identified the probe PBB5 suitable for vMSOT tau imaging. The imaging performance was first evaluated using postmortem human brain tissues from patients with Alzheimers disease, corticobasal degeneration and progressive supranuclear palsy. Concurrent vMSOT and epi-fluorescence imaging of in vivo PBB5 targeting (i.v.) was performed in P301L and non-transgenic littermate mice. Ex vivo measurements on excised brains along with multiphoton microscopy and immunofluorescence staining of tissue sections were performed for validation. The spectrally-unmixed vMSOT data was registered with MRI atlas for volume-of-interest analysis. Results: PBB5 showed specific binding to recombinant K18 tau fibrils, AD brain tissue homogenate by competitive binding against [11C]PBB3 and to tau deposits (AT-8 positive) in post-mortem corticobasal degeneration and progressive supranuclear palsy brain. i.v. administration of PBB5 in P301L mice led to retention of the probe in tau-laden cortex and hippocampus in contrast to wild-type animals, as also confirmed by ex vivo vMSOT, epi-fluorescence and multiphoton microscopy results. Conclusion: vMSOT with PBB5 facilitates novel 3D whole brain imaging of tau in P301L animal model with high-resolution for future mechanistic studies and monitoring of putative treatments targeting tau.

Development of an Ultra - High - Resolution Low Voltage(LV) SEM with an Optimized “in-lens” Design

1990 ◽  
Vol 48 (1) ◽  
pp. 388-389
Author(s):  
Takashi Nagatani ◽  
Mitsugu Sato ◽  
Masako OSUMI
Keyword(s):  
High Resolution ◽  
Low Voltage ◽  
Collection Efficiency ◽  
Spherical Aberration ◽  
Chromatic Aberration ◽  
Spot Size ◽  
Objective Lens ◽  
Tilting Angle ◽  
Working Distance ◽  
Better Than

An “in-lens” type FESEM, Hitachi S-900, developed as an ultra high resolution SEM having 0.7nm resolution at 30kV(Nagatani et al 1986), was modified for better performance at low beam energy(about 5kV or below) with small aberrations of ths objective lens and dual specimen position design. This is in responce to the recent upsurge of interest in using the LVSEM, which enables us hopefully to observe the surface topography of uncoated samples directly with maximum fidelity(Pawley 1987).The actual visibility of the minute topographical details depends upon not anly the spot size of the scanning beam but also physics of interaction between impinging electrons and solid sample(Joy 1989). However, the resolution can never be better than the spot size. Then, it would seem logical to specify the spot size first when designing a high resolution SEM. As discussed earlier(Crewe 1985; Nagatani et al 1987), the spot size of the beam is mainly limited by spherical aberration of the objective lens and diffraction at high voltage(about 10 kV and above). On the other hand, chromatic aberration and diffraction are the dominant factors at low voltages(about 5kV or below). Source size of a cold field emission is so small that we could neglect it for simplicity.In general, chromatic aberration can be smaller at higher excitation of a narrow gap objective pole-piece, which also made the working distance short. Therefore, some compromise is necessary among minimized aberrations, required specimen size, stage traverse and tilting angle etc. In practice, tolerable distortion of the image at low magnification and collection efficiency of the secondary electrons are another factors to be considered in designing the instrument. By taking these factors in simulation, an optimized objective lens was designed as shown in Table 1.

Electron momentum density of hexagonal Zn studied by high-resolution Compton scattering

2021 ◽  
Vol 28 (1) ◽  
pp. 188-195
Author(s):  
Marek Brancewicz ◽  
Andrzej Andrejczuk ◽  
Eugeniusz Żukowski ◽  
Ludwik Dobrzyński ◽  
Yoshiharu Sakurai ◽  
...  
Keyword(s):  
High Resolution ◽  
Density Functional ◽  
Momentum Density ◽  
High Symmetry ◽  
Functional Theory ◽  
High Resolution Data ◽  
Electron Momentum ◽  
Electron Momentum Density ◽  
Better Than

High-resolution (0.12 a.u.) electron momentum density projections (Compton profiles) of a hexagonal Zn single crystal have been measured along five high-symmetry directions in reciprocal space. The experiment was performed with the use of 115.6 keV synchrotron radiation on the BL08W station at SPring-8. The quality of the measured Compton profiles is significantly better than that of previous medium- and high-resolution data. The experimental data were compared with the corresponding theoretical Korringa–Kohn–Rostoker (KKR) and density functional theory (DFT) calculations. Some minor and major differences between the two theoretical band-structure calculations have been observed. However, the good quality experimental results indicate their better agreement with DFT.

scholarly journals DETERMINATION OF THE OPTIMAL SCANNING STEP FOR EVALUATION OF IMAGE RECONSTRUCTION QUALITY IN MAGNETOACOUSTIC TOMOGRAPHY WITH MAGNETIC INDUCTION

2019 ◽  
Vol 9 (4) ◽  
pp. 38-42
Author(s):  
Adam Ryszard Żywica ◽  
Marcin Ziółkowski
Keyword(s):  
Image Reconstruction ◽  
Magnetic Induction ◽  
Imaging Modality ◽  
Biological Tissues ◽  
Non Invasive ◽  
Scanning Step ◽  
Reconstruction Quality ◽  
Complex Shapes

Magnetoacoustic Tomography with Magnetic Induction (MAT-MI) is a new hybrid imaging modality especially dedicated for non-invasive electrical conductivity imaging of low-conductivity objects such as e.g. biological tissues. The purpose of the present paper is to determine the optimal scanning step assuring the best quality of image reconstruction. In order to resolve this problem a special image reconstruction quality indicator based on binarization has been applied. Taking into account different numbers of measuring points and various image processing algorithms, the conditions allowing successful image reconstruction have been provided in the paper. Finally, the image reconstruction examples for objects’ complex shapes have been analyzed.

scholarly journals IMAGE QUALITY ASSESSMENT OF HIGH-RESOLUTION SATELLITE IMAGES WITH MTF-BASED FUZZY COMPREHENSIVE EVALUATION METHOD

2018 ◽  
Vol XLII-3 ◽  
pp. 1907-1914 ◽  
Author(s):  
Z. Wu ◽  
Z. Luo ◽  
Y. Zhang ◽  
F. Guo ◽  
L. He
Keyword(s):  
High Resolution ◽  
Image Quality ◽  
Evaluation Method ◽  
Comprehensive Evaluation ◽  
Fuzzy Comprehensive Evaluation ◽  
Fuzzy Evaluation ◽  
Fuzzy Comprehensive Evaluation Method ◽  
Comprehensive Evaluation Method ◽  
Better Than

A Modulation Transfer Function (MTF)-based fuzzy comprehensive evaluation method was proposed in this paper for the purpose of evaluating high-resolution satellite image quality. To establish the factor set, two MTF features and seven radiant features were extracted from the knife-edge region of image patch, which included Nyquist, MTF0.5, entropy, peak signal to noise ratio (PSNR), average difference, edge intensity, average gradient, contrast and ground spatial distance (GSD). After analyzing the statistical distribution of above features, a fuzzy evaluation threshold table and fuzzy evaluation membership functions was established. The experiments for comprehensive quality assessment of different natural and artificial objects was done with GF2 image patches. The results showed that the calibration field image has the highest quality scores. The water image has closest image quality to the calibration field, quality of building image is a little poor than water image, but much higher than farmland image. In order to test the influence of different features on quality evaluation, the experiment with different weights were tested on GF2 and SPOT7 images. The results showed that different weights correspond different evaluating effectiveness. In the case of setting up the weights of edge features and GSD, the image quality of GF2 is better than SPOT7. However, when setting MTF and PSNR as main factor, the image quality of SPOT7 is better than GF2.

scholarly journals Dilated Convolution with Dilated GRU for Music Source Separation

2019 ◽  
Author(s):  
Jen-Yu Liu ◽  
Yi-Hsuan Yang
Keyword(s):  
High Resolution ◽  
Source Separation ◽  
Receptive Fields ◽  
Audio Signals ◽  
Sound Sources ◽  
Dilated Convolution ◽  
Proposed Model ◽  
Music Audio ◽  
Better Than

Stacked dilated convolutions used in Wavenet have been shown effective for generating high-quality audios. By replacing pooling/striding with dilation in convolution layers, they can preserve high-resolution information and still reach distant locations. Producing high-resolution predictions is also crucial in music source separation, whose goal is to separate different sound sources while maintain the quality of the separated sounds. Therefore, in this paper, we use stacked dilated convolutions as the backbone for music source separation. Although stacked dilated convolutions can reach wider context than standard convolutions do, their effective receptive fields are still fixed and might not be wide enough for complex music audio signals. To reach even further information at remote locations, we propose to combine a dilated convolution with a modified GRU called Dilated GRU to form a block. A Dilated GRU receives information from k-step before instead of the previous step for a fixed k. This modification allows a GRU unit to reach a location with fewer recurrent steps and run faster because it can execute in parallel partially. We show that the proposed model with a stack of such blocks performs equally well or better than the state-of-the-art for separating both vocals and accompaniment.

High Resolution Investigation of Stacking Fault Density by HRXRD and STEM

2019 ◽  
Vol 963 ◽  
pp. 346-349 ◽  
Author(s):  
Eric G. Barbagiovanni ◽  
Alessandra Alberti ◽  
Corrado Bongiorno ◽  
Emanuele Smecca ◽  
Massimo Zimbone ◽  
...  
Keyword(s):  
Growth Rate ◽  
High Resolution ◽  
Photo Luminescence ◽  
X Ray Diffraction ◽  
Transmission Electron ◽  
Scanning Transmission ◽  
Cubic Silicon Carbide ◽  
Koh Etching ◽  
Microscopy Images

The effect of varying growth rate on the formation of defects in homo-epitaxially grown cubic silicon carbide (3C-SiC) is studied. Three growth rates are considered (30, 60 and 90 μm/hr) demonstrating that as the growth rate increases the density of point defects, as demonstrated by photo- luminescence, and stacking faults (SFs), as measured by a KOH etching procedure, increase. Scanning transmission electron microscopy images demonstrate generation, annihilation and closure of SFs as a function film thickness. High resolution X-ray diffraction is used to uncover the higher quality of homo-epitaxial with respect hetero-epitaxial films through the examination of the sample mosaicity and SF density.

A High Resolution Scanning Microscope

1968 ◽  
Vol 26 ◽  
pp. 356-357
Author(s):  
A. V. Crewe ◽  
J. Wall ◽  
L. M. Welter
Keyword(s):  
High Resolution ◽  
Field Emission ◽  
Spherical Aberration ◽  
Focal Length ◽  
Spot Size ◽  
Emission Source ◽  
Field Of View ◽  
Scanning Microscope ◽  
Magnetic Lens ◽  
High Quality

A scanning microscope using a field emission source has been described elsewhere. This microscope has now been improved by replacing the single magnetic lens with a high quality lens of the type described by Ruska. This lens has a focal length of 1 mm and a spherical aberration coefficient of 0.5 mm. The final spot size, and therefore the microscope resolution, is limited by the aberration of this lens to about 6 Å.The lens has been constructed very carefully, maintaining a tolerance of + 1 μ on all critical surfaces. The gun is prealigned on the lens to form a compact unit. The only mechanical adjustments are those which control the specimen and the tip positions. The microscope can be used in two modes. With the lens off and the gun focused on the specimen, the resolution is 250 Å over an undistorted field of view of 2 mm. With the lens on,the resolution is 20 Å or better over a field of view of 40 microns. The magnification can be accurately varied by attenuating the raster current.

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