66 research outputs found
Slopes of smooth curves on Fano manifolds
Ross and Thomas introduced the concept of slope stability to study
K-stability, which has conjectural relation with the existence of constant
scalar curvature K\"ahler metric. This paper presents a study of slope
stability of Fano manifolds of dimension with respect to smooth
curves. The question turns out to be easy for curves of genus and the
interest lies in the case of smooth rational curves. Our main result classifies
completely the cases when a polarized Fano manifold is not slope
stable with respect to a smooth curve. Our result also states that a Fano
threefold with Picard number 1 is slope stable with respect to every smooth
curve unless is the projective space.Comment: 13 pages, Theorems in the original version were modified. This paper
will be published in the Bulletin of the London Mathematical Societ
Cylinders in del Pezzo surfaces
On del Pezzo surfaces, we study effective ample -divisors such
that the complements of their supports are isomorphic to -bundles
over smooth affine curves.Comment: 33 pages. Gaps in the proofs of Theorems 4.1.1 and 4.1.3 in the
previous version have been filled u
Cell Deformation by Single-beam Acoustic Trapping: A Promising Tool for Measurements of Cell Mechanics
We demonstrate a noncontact single-beam acoustic trapping method for the quantification of the mechanical properties of a single suspended cell with label-free. Experimentally results show that the single-beam acoustic trapping force results in morphological deformation of a trapped cell. While a cancer cell was trapped in an acoustic beam focus, the morphological changes of the immobilized cell were monitored using bright-field imaging. The cell deformability was then compared with that of a trapped polystyrene microbead as a function of the applied acoustic pressure for a better understanding of the relationship between the pressure and degree of cell deformation. Cell deformation was found to become more pronounced as higher pressure levels were applied. Furthermore, to determine if this acoustic trapping method can be exploited in quantifying the cell mechanics in a suspension and in a non-contact manner, the deformability levels of breast cancer cells with different degrees of invasiveness due to acoustic trapping were compared. It was found that highly-invasive breast cancer cells exhibited greater deformability than weakly-invasive breast cancer cells. These results clearly demonstrate that the single-beam acoustic trapping technique is a promising tool for non-contact quantitative assessments of the mechanical properties of single cells in suspensions with label-free.1
Deep Learning-based Synthetic High-Resolution In-Depth Imaging Using an Attachable Dual-element Endoscopic Ultrasound Probe
Endoscopic ultrasound (EUS) imaging has a trade-off between resolution and
penetration depth. By considering the in-vivo characteristics of human organs,
it is necessary to provide clinicians with appropriate hardware specifications
for precise diagnosis. Recently, super-resolution (SR) ultrasound imaging
studies, including the SR task in deep learning fields, have been reported for
enhancing ultrasound images. However, most of those studies did not consider
ultrasound imaging natures, but rather they were conventional SR techniques
based on downsampling of ultrasound images. In this study, we propose a novel
deep learning-based high-resolution in-depth imaging probe capable of offering
low- and high-frequency ultrasound image pairs. We developed an attachable
dual-element EUS probe with customized low- and high-frequency ultrasound
transducers under small hardware constraints. We also designed a special geared
structure to enable the same image plane. The proposed system was evaluated
with a wire phantom and a tissue-mimicking phantom. After the evaluation, 442
ultrasound image pairs from the tissue-mimicking phantom were acquired. We then
applied several deep learning models to obtain synthetic high-resolution
in-depth images, thus demonstrating the feasibility of our approach for
clinical unmet needs. Furthermore, we quantitatively and qualitatively analyzed
the results to find a suitable deep-learning model for our task. The obtained
results demonstrate that our proposed dual-element EUS probe with an
image-to-image translation network has the potential to provide synthetic
high-frequency ultrasound images deep inside tissues.Comment: 10 pages, 9 figure
Multimodal endoscopic system based on multispectral and photometric stereo imaging and analysis
We propose a multimodal endoscopic system based on white light (WL), multispectral (MS), and photometric stereo (PS) imaging for the examination of colorectal cancer (CRC). Recently, the enhancement of the diagnostic accuracy of CRC colonoscopy has been reported; however, tumor diagnosis for a variety of lesion types remains challenging using current endoscopy. In this study, we demonstrate that our developed system can simultaneously discriminate tumor distributions and provide three-dimensional (3D) morphological information about the colon surface using the WL, MS, and PS imaging modalities. The results demonstrate that the proposed system has considerable potential for CRC diagnosis. © 2019, OSA - The Optical Society. All rights reserved.1
Non-invasive measurement of hemodynamic change during 8 MHz transcranial focused ultrasound stimulation using near-infrared spectroscopy
Background: Transcranial focused ultrasound (tFUS) attracts wide attention in neuroscience as an effective noninvasive approach to modulate brain circuits. In spite of this, the effects of tFUS on the brain is still unclear, and further investigation is needed. The present study proposes to use near-infrared spectroscopy (NIRS) to observe cerebral hemodynamic change caused by tFUS in a noninvasive manner. Results: The results show a transient increase of oxyhemoglobin and decrease of deoxyhemoglobin concentration in the mouse model induced by ultrasound stimulation of the somatosensory cortex with a frequency of 8 MHz but not in sham. In addition, the amplitude of hemodynamics change can be related to the peak intensity of the acoustic wave. Conclusion: High frequency 8 MHz ultrasound was shown to induce hemodynamic changes measured using NIRS through the intact mouse head. The implementation of NIRS offers the possibility of investigating brain response noninvasively for different tFUS parameters through cerebral hemodynamic change. © 2019 The Author(s).1
Smartphone-based multispectral imaging: system development and potential for mobile skin diagnosis
We investigate the potential of mobile smartphone-based multispectral imaging for the quantitative diagnosis and management of skin lesions. Recently, various mobile devices such as a smartphone have emerged as healthcare tools. They have been applied for the early diagnosis of nonmalignant and malignant skin diseases. Particularly, when they are combined with an advanced optical imaging technique such as multispectral imaging and analysis, it would be beneficial for the early diagnosis of such skin diseases and for further quantitative prognosis monitoring after treatment at home. Thus, we demonstrate here the development of a smartphone-based multispectral imaging system with high portability and its potential for mobile skin diagnosis. The results suggest that smartphone-based multispectral imaging and analysis has great potential as a healthcare tool for quantitative mobile skin diagnosis. © 2016 Optical Society of America.1
Smartphone-based multispectral imaging and machine-learning based analysis for discrimination between seborrheic dermatitis and psoriasis on the scalp
For appropriate treatment, accurate discrimination between seborrheic dermatitis and psoriasis in a timely manner is crucial to avoid complications. However, when they occur on the scalp, differential diagnosis can be challenging using conventional dermascopes. Thus, we employed smartphone-based multispectral imaging and analysis to discriminate between them with high accuracy. A smartphone-based multispectral imaging system, suited for scalp disease diagnosis, was redesigned. We compared the outcomes obtained using machine learning-based and conventional spectral classification methods to achieve better discrimination. The results demonstrated that smartphone-based multispectral imaging and analysis has great potential for discriminating between these diseases. © 2019 Optical Society of America.1
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