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Environment and breast cancerand doctor. Youtube com naked girls. God and oral sex. Sexy female porn pics. Bisexual free porn russian video. Amar Pali Dubey Porn. Watch Random slits sampling HOT ♨ Movies Visualizing ocular vasculature is important in clinical ophthalmology because ocular circulation abnormalities are early signs of ocular diseases. Photoacoustic microscopy PAM images the ocular vasculature without using exogenous contrast agents, avoiding associated side effects. Moreover, 3D PAM Random slits sampling can be useful in understanding vessel-related eye disease. However, the complex structure of the multi-layered vessels still present challenges in evaluating ocular vasculature. In this study, we demonstrate a new method Random slits sampling evaluate blood circulation in the eye by combining in vivo PAM imaging and Random slits sampling ocular surface estimation Random slits sampling based on a machine learning algorithm: By using the developed estimation method, we were able to visualize the PA ocular vascular image intuitively and demonstrate layer-by-layer analysis of injured ocular vasculature. We believe that our method can provide more accurate evaluations of article source eye circulation in ophthalmic applications. Visualizing ocular vasculature is important in clinical ophthalmology because ischemia and neovascularization are early signs of various ocular diseases 1 Random slits sampling, 2. Conventionally, slit-lamp biomicroscopy is used to evaluate such disorders, but it is not able to show vessels clearly when the vasculature is accompanied by opaque scar tissue. Fluorescence angiography is also commonly used for ocular vascular imaging, but the injection of the required contrast agents can inflict pain and create potential complications. Optical coherence tomography OCTanother widely used tool nowadays, can provide high-resolution and volumetric images of both the ocular structure 3 and the vasculature by encoding the intensity variance resulting Random slits sampling blood flow 4. Photoacoustic microscopy PAM is an emerging imaging technology that also enables vasculature visualization in 3D 5 because of its innate depth-resolving imaging capability 6. PAM can provide an ocular vascular image based on the inherent optical absorbance of hemoglobin itself 7. Therefore, there is no side effect associated with exogenous contrast agent 89. Watch PORN Videos Teens nude boys cookie tube.

Busty asian rachel. Publisher's note: Springer Nature remains neutral with regard to jurisdictional claims in published maps and institutional affiliations. Jeong Hun Kim, Email: Chulhong Kim, Email: Sci Rep. Published online Jun Corresponding author. Received Jan 11; Accepted May To view a copy of this license, visit http: This article has been cited by other Random slits sampling in PMC.

Abstract Visualizing ocular vasculature is important in clinical ophthalmology because ocular circulation abnormalities are early signs of ocular diseases. Introduction Visualizing ocular vasculature is important in clinical ophthalmology because ischemia and neovascularization are early signs of various ocular diseases 12. Open in a separate window. Figure 1. Eye surface estimation based on random sample consensus RANSAC and vessel visualization We developed a RANSAC-based eye surface estimation method to reconstruct more intuitive ocular images than provided Random slits sampling conventional depth-encoded images and to analyze the ocular vasculature layer by layer.

Detailed descriptions of each process step are given in the following: Figure 2. Table 1 Averaged GPU processing time to estimate surface. Averaged processing time Memory allocation and copy ms Matching ms Required number of repeats 9.

Table 2 Representative average Random slits sampling standard deviation of the optimal parameters. Supra-surface vessel Random slits sampling enables temporal and quantitative evaluation of corneal neovascularization Random slits sampling have demonstrated isolation of vessels according to the surface estimated by the RANSAC-based algorithm.

Figure 3. Surface vessel isolation enables in vivo evaluation of choroidal and retinal vessels Because photoacoustic imaging techniques enable imaging deep structures 1617OR-PAM can visualize choroidal and retinal vessels beneath the sclera that forms the opaque outermost layer of an eyeball and prevents visualization of vessels underneath it.

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Figure 4. Animal preparation All animal experimental procedures were conducted following the laboratory animal protocol Random slits sampling by the institutional animal care and use committee of the Pohang University of Science and Technology POSTECH.

Quantification of corneal neovascularization To quantify the corneal neovascularization, we calculated the new vessel area considering the slope click the eye surface see Supplementary Fig. We assumed that the actual surface Random slits sampling the sphere, corresponding to each projected pixel, was flat to simplify the calculation: Electronic supplementary material Video S1 2.

Acknowledgements S.

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Author Random slits sampling S. Notes Competing Interests The authors Random slits sampling that they have no competing interests. References 1. Choroidal neovascularization in age-related macular read more is the cause?

Flammer J, et al. The impact of ocular blood flow in glaucoma. Progress in retinal and eye research. Lee C, et al. Stimulated penetrating keratoplasty using real-time virtual intraoperative surgical optical coherence tomography. Journal of biomedical optics. Multiplane spectroscopic whole-body photoacoustic imaging of small animals in vivo. Zhang Y, Random slits sampling al. Non-invasive multimodal functional imaging of the intestine with frozen micellar naphthalocyanines.

Nature nanotechnology. Functional optoacoustic imaging of moving objects using microsecond-delay acquisition of multispectral three-dimensional tomographic data.

Scientific reports 4 Label-free photoacoustic ophthalmic angiography. Optics letters.

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Photoacoustic ocular imaging. Jeon M, Kim C. Multimodal photoacoustic tomography. IEEE transactions on multimedia. Liu W, et al.

Wwwsexcom India Watch PORN Videos Nena nude. This two-stage procedure enables us to depositions in our model system. All simulation runs have jamming limit. The 1-d jamm- successful depositions are tried, the time increment for each ing coverage is exactly evaluated to be about 0. The time expressions in Eqs. In our RSA model, however, the standard theories in the discrete lattice model, e. This discrepancy indicates that particle geo- standard way as in Eq. Near the saturated jamming limit, almost all accessible areas are occupied by particles, and, the shape and distribution of very few remaining accessible areas will make an important role in further RSA processes. In summary, our new algorithm to simulate the RSA packing in the 2-dimensional narrow slit is found to be accurate and fast execution time to generate completely saturated jamming configurations for the systems of 0. We are currently in the progress for applying this new algorithm to investigate the RSA structural properties of both 2-d and 3-d slit model systems to compare with micro- canonical equilibrium systems. This work is supported by the grant as the dashed-line in this figure. SHS also wishes to thank to Mr. In the initial time regime, simulation results show the rapid increase in the coverage values, References suggesting that most particles get occupied in the initial RSA packing process. In the intermediate regime, after very steep 1. Renyi, A. A , , asymptotic regime where the coverage reaches near constant The RSA packing exhibits several interesting features 3. New York, E , 69, In contrast, PAM could visualize vessels even in the area of edema and opacity. The surface-based depth-encoded images enabled tracking of vessels on the same layer, and revealed that limbal vessels are interrupted in the area of the chemical burn Fig. Furthermore, neovascularization is shown above the estimated surface, and new vessels are growing upward along the same layer Fig. The isolation of supra-surface vessels enables temporal follow-up of corneal neovascularization at a glance and clearly describes its progression, which starts from the limbus and grows toward the corneal center Fig. Considering the distortion induced by projecting the curved surface to the image plane, we could calculate the actual area of cornel neovascularization and record its temporal progression Fig. A detailed description of calculating the area from the images is given in the Methods section. We also implemented the isolation of the corneal neovascularization and quantified the area after an acid burn see Supplementary Fig. Two of the three corneal neovascularization areas increased by more than 0. The burned areas are highlighted with white dashed circles. Because photoacoustic imaging techniques enable imaging deep structures 16 , 17 , OR-PAM can visualize choroidal and retinal vessels beneath the sclera that forms the opaque outermost layer of an eyeball and prevents visualization of vessels underneath it. To evaluate the capability of our PAM system to assess deep vessels, we prepared normal eyes, eyes after an alkali burn, and eyes after an acid burn. Conjunctival swelling in both eyes after chemical burns to a lesser extent in eyes after acid burn and hemorrhages in eyes after alkali burns made visualization of deep vessels even more difficult Fig. Surface-based depth-encoded PAM images can to some degree visualize choroidal and retinal vessels, but it is still difficult to evaluate them due to overlying limbal vessels and hemorrhages Fig. To confirm the depth of damages, histologic assessments were performed. The acid-burned eyes show intact layers of the retina and choroid, while the alkali-burned eyes show structural disintegration that extends deep into the full thickness of the retina Fig. These results well agree with the previously report results that acids are generally less harmful than alkalis because coagulated proteins prevent acid penetration The burned areas are highlighted with red dashed circles. However, due to the nature of random-based sampling, RANSAC cannot always find the optimal set from the input dataset. In other words, the center position and half-diameter of the eye estimated via RANSAC could change whenever we estimate the parameters again. This serious problem might lead to inconsistent and unreliable results in both visualization and segmentation. Increasing the number of iterations is needed to minimize the probability of the problem. As mentioned, the high precision of RANSAC-based estimation requires a large number of iterations and a long computation time, especially when 3D data is addressed, as in this study. The conventional depth-encoded image represents the signal depth from a scanning plane. This image might be helpful in understanding the 3D structure of flat samples, such as a mouse ear or cells 22 , 23 because the surface of the sample and the scanning plane are approximately parallel, but it is not easy to understand the structure when the sample surface is curved, like the ocular vasculature Fig. Taking a different approach, the surface-based depth-encoded image represents the signal depth from the estimated ocular surface, so it is easier to understand the ocular vasculature. In Fig. The color difference makes it clear that the limbal vessels are located on a higher layer than the other vessels. Hence, an estimation error could occur when applying our algorithm to human eye images. However, we expect that this problem can be solved by considering several parameters, such as the radius of the iris and the anterior choroid curvature, separately in the estimation process. Additional time for processing would be required. We have demonstrated temporal and quantitative analysis of corneal neovascularization. Because corneal neovascularization is present in most cases of blindness related to corneal disease 25 , it is important to assess its progression and treatment response. Conventionally, corneal neovascularization is evaluated with slit-lamp biomicroscopy or photographs taken during slit-lamp examinations 26 , However, the visibility largely depends on the quality of images, and even in good quality images some vessels are not visible when accompanied by opaque scar tissue Recently, fluorescein and indocyanine green angiography have been utilized in some studies 29 , but their invasiveness and the risks of serious adverse reactions have hindered their wide use Our system provides high contrast images without labeling and additionally provides automated, objective quantification of corneal neovascularization within a few seconds after image acquisition. With the help of the RANSAC-based algorithm, we can evaluate choroidal and retinal vessels that lie deep from the surface. Photoacoustic imaging is valuable in imaging deep structures, but analysis of reconstructed 3D volume images and conventionally depth-encoded images is not intuitive. The RANSAC-based algorithm enables layer by layer analysis of multi-layered structures with curvature, and the resultant images can demonstrate temporal changes to users intuitively, as shown in Fig. The peripheral choroid has not received much attention from ophthalmologists, despite the presence of a watershed zone in the far temporal sector of the human choroid The watershed zone suggests that damages such as an alkali burn inflicted on the peripheral retrograde choroidal arteries can lead to choroidal ischemia in the area from the ora serrata to the watershed zone. Despite its significance, assessment of the peripheral choroid from inside is time-consuming and troublesome: Visualizing the choroidal vessels requires a diopter lens to expand the angle of view and indocyanine green for angiography In comparison, by imaging from the outside, our approach facilitates peripheral choroid evaluation. We conducted in vivo photoacoustic imaging of anterior ocular vasculatures with the help of RANSAC-based ocular surface estimation algorithm. The algorithm proved very useful for evaluating multi-layered and curved structures such as eyes. We have demonstrated intuitively understandable layer-by-layer images reconstructed from 3D volume photoacoustic data of the anterior ocular vasculature. We believe that our approaches will help expand the applications of PAT in ophthalmology. The future direction of this study is to apply this technology to human eyes. However, besides the problem of the opaque sclera and the anatomical differences of the eyeballs, there are some additional problems that the imaging speed is too slow and the coupling medium should be used. We believe that by using the non-contact imaging method, the problems could be solved For photoacoustic irradiation, we used a Nd: The objective numerical aperture NA was 0. In addition, laser safety on the scleral surface was also considered Therefore, the maximum permissible pulse energy was calculated to be about nJ, which is about 6 times larger than the energy we used. All animal experimental procedures were conducted following the laboratory animal protocol approved by the institutional animal care and use committee of the Pohang University of Science and Technology POSTECH. Then, the mouse was placed on an animal stage with a silicon-heating pad to maintain the body temperature of the mice during imaging. We used ultrasound gel on the mouse eye as a coupling medium between the eye and a water tank. Alkali- and acid-burn injuries were performed on the right eyes. We imaged the eyes on days 0 control and after burn , 7, 14, and 21 after chemical burn to observe the healing process. To observe the reactions near the limbal blood vessels after the alkaline and acid burns, we imaged near the limbus, including limbal, iris and choroidal blood vessels. During PA imaging, we pressed the area around the eye slightly to make the area more visible. To quantify the corneal neovascularization, we calculated the new vessel area considering the slope of the eye surface see Supplementary Fig. Because the detected new vessels were usually located on the spherical eye surface, the actual area of the corneal vessels became distorted when they projected in a 2D image. We assumed that the actual surface on the sphere, corresponding to each projected pixel, was flat to simplify the calculation:. Finally, the corrected corneal new vessel area, A C N V , was calculated by. K of Seoul National University. All authors contributed critical readings of the manuscript. Seungwan Jeon and Hyun Beom Song contributed equally to this work. Electronic supplementary material. Publisher's note: Springer Nature remains neutral with regard to jurisdictional claims in published maps and institutional affiliations. Jeong Hun Kim, Email: Chulhong Kim, Email: Sci Rep. Published online Jun Corresponding author. Received Jan 11; Accepted May To view a copy of this license, visit http: This article has been cited by other articles in PMC. Abstract Visualizing ocular vasculature is important in clinical ophthalmology because ocular circulation abnormalities are early signs of ocular diseases. Introduction Visualizing ocular vasculature is important in clinical ophthalmology because ischemia and neovascularization are early signs of various ocular diseases 1 , 2. Our methods were based on atomic layer lithography combined with multiple layers of metal deposition and selective etching Here, the slit width was determined by using the atomic layer deposition ALD thickness in an optically opaque metal membrane. Our nanoslits had a 5-nm gap that extended up to the entire membrane, with a length of 0. This structure enabled us to achieve near-maximum field enhancement in the THz region. Our nanoslits had nanometre-wide metallic slits that extended along the entire length of the membrane, thus maintaining the uniform air gap throughout the length, as shown in the half-section schematic and top view presented in Fig. Nanoslits with gold film on the SiN x membrane were supported by the robust Si frame. The inset shows the nanogap in the metallic film. We first fabricated the nanoslits on the SiN x -coated Si substrate. Then, bulk Si was etched out through the back-side window, as presented in the schematic cross-sectional diagram in Fig. The fabrication details will be described in the methods section. Figure 1c shows a scanning electron microscopy SEM image of the top view of the nanoslits. The inset of Fig. In the optical image Fig. The optical transmission of white light through the nanogap indicated the clear formation of the nanogap, and the diffracted light of the longer wavelength was transmitted, whereas the transmission was null when the light was polarized along the slit direction. For this experiment, a mode-locked Ti: One of the beams impinged on the biased GaAs semiconductor crystal and emitted broadband THz from the metallic antenna patterned on the crystal. Then, THz was collected by a Si hemisphere and plane polarized before it was focused on the sample. The p-polarized THz pulses were normally focused on the nanogap slit. The THz time domain spectra were mathematically transformed into frequency domain spectra FDS via Fourier transformation. A Wollaston prism split the x- and y-polarized beam by using a balanced photodiode detector for the electric field amplitude measurement. The measurement was performed in both TM and TE modes; later, the enhancement of the normalized field amplitude was calculated by subtracting the transmission signal in the TE mode from that in the TM mode. Femtosecond laser pulses were divided for THz generation and detection. Broadband THz generated by the biased GaAs emitter was plane polarized, collimated and then focused on the nanoslits, and the transmitted beam was detected with a ZnTe crystal. A Wollaston prism separated the beam into two orthogonal, linearly polarized beams for the electric field amplitude measurement using a balanced photodiode detector. Figure 3a shows TDS data obtained from the gold nanoslits and the free space transmission from the aperture area, 0. The peak transmission amplitude through an array of 5-nm slits, which occupied only 0. In contrast, the direct THz transmission in the TE mode was less than 0. The shift indicated significant changes in the effective refractive indices. A typical reference and nanoslit sample used to measure TDS is presented on the right side of Fig. We obtained FDS, as shown in Fig. Figure 3b shows the field amplitude versus the frequency of the THz transmission from the nanoslits solid curve , which exhibits a similar trend as the free space dotted curve , thus indicating non-resonance transmission. The red dashed curve indicates the average field amplitude of the transmission of 10 samples. Furthermore, the field amplitudes were normalized to the free space transmission and are presented in Fig. The graph shows that the normalized field amplitude decreased with increasing frequency without any resonance. The non-resonance behaviour was attributed to the very high length-to-width ratio 1. We measured the far-field THz-TDS from free space and from the nanoslit sample with equal-sized apertures. This observation indicated that the effective thickness of the metal film was almost half that of the actual thickness, in agreement with an asymmetric shape with only half of the metal thickness forming the 5-nm gap. This result agreed with findings previously reported by S. Han et al. Higher field enhancement was observed at the lower frequency, which was almost ten thousand at approximately 0. In our setup, the minimum reliable frequency with which we could observe the drop in the field enhancement was 0. We believe that the enhancement was saturated beyond this frequency. The normalization was completed with the free space transmission through an aperture that was made with optically thick aluminium foil of the exact same size as the membrane. The experimental results of the 10 different samples are shown in the inset. To explain the very high field enhancement through the nanoslit without the substrate, we simply assumed that the nanoslit was a nanocapacitor that enabled the storage of a large charge. When THz waves pass through the nanoslits, the sidewalls of the slits act as nanocapacitors, owing to the oscillating opposite charge carrier concentrated around them. The charge density is proportional to the incident field and inversely proportional to the gap width. For narrow gaps, the charge density creates a very strong electric field that enhances the signal by several orders of magnitude relative to the incident electric field. The charges at the edges of the metallic slit oscillate with the alternation of the incident electric field and re-radiate the electromagnetic wave, where the gap acts as an antenna. The re-radiated power depends on the charge density or the electric field at the gap. By measuring the re-radiated electromagnetic waves, we estimated the field enhancement factor at the slit. The first experimental realization of a nonresonant field enhancement factor of nearly 1, was previously demonstrated with a nm-wide gold slit Our current measurement with 5-nm-wide nearly free-standing nanoslits is presented in Fig. Although our field enhancement factor was less than half of the resonant transmission through a slot antenna array with a nearly 1-nm gap, as reported by X. Chen et al. In our case, the gap width was a million times smaller than the wavelength; however, the length of the slit was of the same order as the wavelength. In order to analyse the substrate effects in transmission and the field enhancement factor, we performed TDS measurements with nanoslits on substrate and without substrate. The open black squares the amplitude was multiplied by 10 for comparability and the open red circles represent the transmission through the nanogap with and without substrate, respectively. The normalization was done separately with the transmission through the reference samples of Si substrate and free space aperture of the equal area. Our experimental results indicates the field enhancement increased by approximately 15 fold at 0. Some irregularities in transmission curve was also observed because of the grating modes when the slit array diffracted the incident radiation into the sample plane..

In vivo corneal neovascularization imaging by optical-resolution Random slits sampling microscopy. Random sample Random slits sampling Communications of the ACM. In vivo high-resolution 3D photoacoustic imaging of superficial vascular anatomy. Physics in medicine and biology. Remtulla S, Hallett P. A schematic eye for the mouse, and comparisons with the rat.

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Vision research. A robust model for simultaneously inducing corneal neovascularization and retinal gliosis in the mouse eye. Molecular Vision. Random slits sampling M, Kim C. Looking Deeper: Multimodal and contrast-enhanced photoacoustic imaging offer a clearer view within tissues for more accurate diagnosis.

IEEE pulse. Kim, J. Scientific Reports 6 Mead, M. Evaluation and initial management of patients with ocular and adnexal trauma in Principles and Practice of Ophthalmology ed. Daniel M. Albert — WB Saunders Philadelphia, A PDMS-based 2-axis waterproof scanner for photoacoustic microscopy. High-speed and high-SNR photoacoustic microscopy based on a galvanometer mirror in non-conducting liquid. Fast optical-resolution photoacoustic microscopy using a 2-axis water-proofing MEMS scanner.

Scientific reports 5 Yao J, Random slits sampling al. Double-illumination photoacoustic microscopy. Multiscale photoacoustic Random slits sampling using reversibly switchable bacterial click as a near-infrared photochromic probe. Nature methods. Retinal photoreceptor count, retinal surface area, and optic disc size in normal human eyes.

Ocular neovascularization: Dipping the sample in HF also etched the alumina between the metal, thereby exposing the air gap in the metal. To release the fully free-standing nanogap metal membrane for material transportation through the slits, the remaining thin Si Random slits sampling N 4 membrane was also etched out with reactive ion etching RIE. In most cases, after etching the nitride membrane, the gold membrane became unstable and collapsed.

The nanogaps either collapsed or, where the bridge-like structure survived, widened. Thus, we kept the robust nitride membrane to support the metallic source and increase the stability of see more nanogap for the THz experiments.

A large nonresonant electromagnetic field enhancement was experimentally realized with practically infinite gold nanoslits.

The large field enhancement in Random slits sampling nanogap region can be explained by the nanocapacitor Random slits sampling, and is formed as a result of the excitation of SPPs Random slits sampling the THz field is incident on the metal surface. The substrate-free nanoslits were fabricated using plug-and-lift-off and standard Si microfabrication techniques in which the gap width and uniformity were determined by atomic layer lithography.

The yield of such an ultra-thin nanoslit membrane depends on the strength Random slits sampling the metal microribbon, with negligible deformities due to temperature and pressure. The developed substrate-free nanoslits may be useful in studies of gap plasmonics, quantum tunnelling, nonlinear optics, and nanophotonics, for which high field enhancement is important.

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How to cite this article: Suwal, O. Nonresonant 10 4 Terahertz Field Enhancement with 5-nm Slits. Publisher's note: Springer Nature remains neutral with regard to jurisdictional claims in published maps Random slits sampling institutional affiliations. BK21 Random slits sampling ProgramA The authors declare no competing financial interests. Author Contributions D. All https://greek.planetlagu.host/video7230-hac.php reviewed the manuscript.

Dildos XXX Watch PORN Movies Transexual auckland. K of Seoul National University. All authors contributed critical readings of the manuscript. Seungwan Jeon and Hyun Beom Song contributed equally to this work. Electronic supplementary material. Publisher's note: Springer Nature remains neutral with regard to jurisdictional claims in published maps and institutional affiliations. Jeong Hun Kim, Email: Chulhong Kim, Email: Sci Rep. Published online Jun Corresponding author. Received Jan 11; Accepted May To view a copy of this license, visit http: This article has been cited by other articles in PMC. Abstract Visualizing ocular vasculature is important in clinical ophthalmology because ocular circulation abnormalities are early signs of ocular diseases. Introduction Visualizing ocular vasculature is important in clinical ophthalmology because ischemia and neovascularization are early signs of various ocular diseases 1 , 2. Open in a separate window. Figure 1. Eye surface estimation based on random sample consensus RANSAC and vessel visualization We developed a RANSAC-based eye surface estimation method to reconstruct more intuitive ocular images than provided by conventional depth-encoded images and to analyze the ocular vasculature layer by layer. Detailed descriptions of each process step are given in the following: Figure 2. Table 1 Averaged GPU processing time to estimate surface. Averaged processing time Memory allocation and copy ms Matching ms Required number of repeats 9. Table 2 Representative average and standard deviation of the optimal parameters. Supra-surface vessel isolation enables temporal and quantitative evaluation of corneal neovascularization We have demonstrated isolation of vessels according to the surface estimated by the RANSAC-based algorithm. Figure 3. Surface vessel isolation enables in vivo evaluation of choroidal and retinal vessels Because photoacoustic imaging techniques enable imaging deep structures 16 , 17 , OR-PAM can visualize choroidal and retinal vessels beneath the sclera that forms the opaque outermost layer of an eyeball and prevents visualization of vessels underneath it. Figure 4. Animal preparation All animal experimental procedures were conducted following the laboratory animal protocol approved by the institutional animal care and use committee of the Pohang University of Science and Technology POSTECH. Quantification of corneal neovascularization To quantify the corneal neovascularization, we calculated the new vessel area considering the slope of the eye surface see Supplementary Fig. We assumed that the actual surface on the sphere, corresponding to each projected pixel, was flat to simplify the calculation: Electronic supplementary material Video S1 2. Acknowledgements S. Author Contributions S. Notes Competing Interests The authors declare that they have no competing interests. References 1. Choroidal neovascularization in age-related macular degeneration—what is the cause? Flammer J, et al. The impact of ocular blood flow in glaucoma. Progress in retinal and eye research. Lee C, et al. Stimulated penetrating keratoplasty using real-time virtual intraoperative surgical optical coherence tomography. Journal of biomedical optics. Multiplane spectroscopic whole-body photoacoustic imaging of small animals in vivo. Zhang Y, et al. Non-invasive multimodal functional imaging of the intestine with frozen micellar naphthalocyanines. Nature nanotechnology. Functional optoacoustic imaging of moving objects using microsecond-delay acquisition of multispectral three-dimensional tomographic data. Scientific reports 4 Label-free photoacoustic ophthalmic angiography. Optics letters. Photoacoustic ocular imaging. Jeon M, Kim C. Multimodal photoacoustic tomography. IEEE transactions on multimedia. Liu W, et al. In vivo corneal neovascularization imaging by optical-resolution photoacoustic microscopy. Random sample consensus: Communications of the ACM. In vivo high-resolution 3D photoacoustic imaging of superficial vascular anatomy. Physics in medicine and biology. Remtulla S, Hallett P. A schematic eye for the mouse, and comparisons with the rat. Vision research. A robust model for simultaneously inducing corneal neovascularization and retinal gliosis in the mouse eye. Molecular Vision. Pramanik M, Kim C. Looking Deeper: Multimodal and contrast-enhanced photoacoustic imaging offer a clearer view within tissues for more accurate diagnosis. IEEE pulse. Kim, J. Scientific Reports 6 Mead, M. Evaluation and initial management of patients with ocular and adnexal trauma in Principles and Practice of Ophthalmology ed. Daniel M. Albert — WB Saunders Philadelphia, A PDMS-based 2-axis waterproof scanner for photoacoustic microscopy. High-speed and high-SNR photoacoustic microscopy based on a galvanometer mirror in non-conducting liquid. Fast optical-resolution photoacoustic microscopy using a 2-axis water-proofing MEMS scanner. Scientific reports 5 Yao J, et al. Double-illumination photoacoustic microscopy. For narrow gaps, the charge density creates a very strong electric field that enhances the signal by several orders of magnitude relative to the incident electric field. The charges at the edges of the metallic slit oscillate with the alternation of the incident electric field and re-radiate the electromagnetic wave, where the gap acts as an antenna. The re-radiated power depends on the charge density or the electric field at the gap. By measuring the re-radiated electromagnetic waves, we estimated the field enhancement factor at the slit. The first experimental realization of a nonresonant field enhancement factor of nearly 1, was previously demonstrated with a nm-wide gold slit Our current measurement with 5-nm-wide nearly free-standing nanoslits is presented in Fig. Although our field enhancement factor was less than half of the resonant transmission through a slot antenna array with a nearly 1-nm gap, as reported by X. Chen et al. In our case, the gap width was a million times smaller than the wavelength; however, the length of the slit was of the same order as the wavelength. In order to analyse the substrate effects in transmission and the field enhancement factor, we performed TDS measurements with nanoslits on substrate and without substrate. The open black squares the amplitude was multiplied by 10 for comparability and the open red circles represent the transmission through the nanogap with and without substrate, respectively. The normalization was done separately with the transmission through the reference samples of Si substrate and free space aperture of the equal area. Our experimental results indicates the field enhancement increased by approximately 15 fold at 0. Some irregularities in transmission curve was also observed because of the grating modes when the slit array diffracted the incident radiation into the sample plane. This results can be explained by poor coupling of THz wave among the evanescent modes because of higher refractive index of substrate The effective refractive index for substrate is given by. A schematic flow chart of the fabrication process is presented in Fig. We first fabricated the ALD nanogap in the metal on the Si substrate and then used atomic layer lithography and plugged and lifted off the excess metal by etching the sacrificial layer Finally, Al 2 O 3 and the SiO 2 layer were etched out, thereby releasing the air gap gold nanoslits. After the first metal layer Au: An Al 2 O 3 layer was deposited Fig. In ALD, Tri-methylaluminium and water vapour were sequentially pulsed through the chamber, with N 2 purging after each injection, until 19 cycles yielded 5-nm-thick Al 2 O 3. The lift-off of the second layer removed excess metal and opened up the ALD layer in between the first and second layers. The etchant also slightly etched Al 2 O 3 , and ultra-sonication and cleaning in acetone, methanol and deionized DI water were performed to remove residues at the nanogap. The back-side bulk silicon was selectively etched out Fig. The SiO 2 protected the nanogap and supported the etching of Si by preventing the metal-coated Si substrate from forming as an etch shield. The protective layer was later etched out by dipping it in HF solution, which also removed the bottom SiO 2 layer Fig. Dipping the sample in HF also etched the alumina between the metal, thereby exposing the air gap in the metal. To release the fully free-standing nanogap metal membrane for material transportation through the slits, the remaining thin Si 3 N 4 membrane was also etched out with reactive ion etching RIE. In most cases, after etching the nitride membrane, the gold membrane became unstable and collapsed. The nanogaps either collapsed or, where the bridge-like structure survived, widened. Thus, we kept the robust nitride membrane to support the metallic nanoslits and increase the stability of the nanogap for the THz experiments. A large nonresonant electromagnetic field enhancement was experimentally realized with practically infinite gold nanoslits. The large field enhancement in the nanogap region can be explained by the nanocapacitor model, and is formed as a result of the excitation of SPPs when the THz field is incident on the metal surface. The substrate-free nanoslits were fabricated using plug-and-lift-off and standard Si microfabrication techniques in which the gap width and uniformity were determined by atomic layer lithography. The yield of such an ultra-thin nanoslit membrane depends on the strength of the metal microribbon, with negligible deformities due to temperature and pressure. The developed substrate-free nanoslits may be useful in studies of gap plasmonics, quantum tunnelling, nonlinear optics, and nanophotonics, for which high field enhancement is important. How to cite this article: Suwal, O. Nonresonant 10 4 Terahertz Field Enhancement with 5-nm Slits. Publisher's note: Springer Nature remains neutral with regard to jurisdictional claims in published maps and institutional affiliations. BK21 Plus ProgramA The authors declare no competing financial interests. Author Contributions D. All authors reviewed the manuscript. Sci Rep. Published online Apr 3. Received Sep 22; Accepted Mar 2. This work is licensed under a Creative Commons Attribution 4. To view a copy of this license, visit http: This article has been cited by other articles in PMC. Abstract Transmission of Terahertz THz electromagnetic wave through a substrate is encumbered because of scattering, multiple reflections, absorption, and Fabry—Perot effects when the wave interacts with the substrate. Open in a separate window. Figure 1. Nanoslit sample description. Figure 2. Figure 3. THz transmission measurements through the gold nanoslits. Figure 4. Nanoslit fabrication flow chart. The time expressions in Eqs. In our RSA model, however, the standard theories in the discrete lattice model, e. This discrepancy indicates that particle geo- standard way as in Eq. Near the saturated jamming limit, almost all accessible areas are occupied by particles, and, the shape and distribution of very few remaining accessible areas will make an important role in further RSA processes. In summary, our new algorithm to simulate the RSA packing in the 2-dimensional narrow slit is found to be accurate and fast execution time to generate completely saturated jamming configurations for the systems of 0. We are currently in the progress for applying this new algorithm to investigate the RSA structural properties of both 2-d and 3-d slit model systems to compare with micro- canonical equilibrium systems. This work is supported by the grant as the dashed-line in this figure. SHS also wishes to thank to Mr. In the initial time regime, simulation results show the rapid increase in the coverage values, References suggesting that most particles get occupied in the initial RSA packing process. In the intermediate regime, after very steep 1. Renyi, A. A , , asymptotic regime where the coverage reaches near constant The RSA packing exhibits several interesting features 3. New York, E , 69, Torquato, S. E , 74, The power law exponent df can be determined from the As mentioned previously in Eq..

Sci Rep. Published online Apr 3. Received Sep 22; Https://nympho.planetlagu.host/video5357-nasah.php Mar Random slits sampling. This work is licensed under a Creative Commons Attribution 4. To view a copy of this license, visit http: This article has been cited by source articles in PMC.

Abstract Transmission of Terahertz THz electromagnetic wave through a substrate is encumbered because of scattering, multiple reflections, absorption, and Fabry—Perot effects when the wave interacts with the substrate.

Open in a separate window. Figure 1. Nanoslit sample description. Figure 2. Figure 3. THz transmission measurements through the gold nanoslits. Figure 4.

Nanoslit fabrication flow chart. Conclusion A large nonresonant electromagnetic Random slits sampling enhancement was experimentally realized with practically infinite gold nanoslits. Footnotes The authors declare no competing financial interests. References Ebbesen T. Extraordinary optical transmission through sub-wavelength hole arrays. Nature— Random slits sampling plasmonics. Nat Photonics 6— Terahertz quantum plasmonics of nanoslot antennas in nonlinear regime.

Nano Lett 15—, Optical antennas and plasmonics. Contemp Random slits sampling 50— Antennas for light. Nat Photonics 583—90 High-harmonic generation by resonant plasmon field enhancement. Design and optimization of a 3d pyramidal nanowaveguide with a square cross-section for plasmonic field enhancement for high harmonic generation.

Plasmonics 1099— Terahertz field enhancement via coherent superposition of the pulse sequences after a single optical-rectification crystal. Appl Phys Lett Near-field and sers enhancement from rough plasmonic nanoparticles. Phys Rev B 89 Metamaterial Random slits sampling.

Livestream Nude Watch Sex Movies Simtan Fucking. All simulation runs have jamming limit. The 1-d jamm- successful depositions are tried, the time increment for each ing coverage is exactly evaluated to be about 0. The time expressions in Eqs. In our RSA model, however, the standard theories in the discrete lattice model, e. This discrepancy indicates that particle geo- standard way as in Eq. Near the saturated jamming limit, almost all accessible areas are occupied by particles, and, the shape and distribution of very few remaining accessible areas will make an important role in further RSA processes. In summary, our new algorithm to simulate the RSA packing in the 2-dimensional narrow slit is found to be accurate and fast execution time to generate completely saturated jamming configurations for the systems of 0. We are currently in the progress for applying this new algorithm to investigate the RSA structural properties of both 2-d and 3-d slit model systems to compare with micro- canonical equilibrium systems. This work is supported by the grant as the dashed-line in this figure. SHS also wishes to thank to Mr. In the initial time regime, simulation results show the rapid increase in the coverage values, References suggesting that most particles get occupied in the initial RSA packing process. In the intermediate regime, after very steep 1. Renyi, A. A , , asymptotic regime where the coverage reaches near constant The RSA packing exhibits several interesting features 3. New York, E , 69, Torquato, S. This image might be helpful in understanding the 3D structure of flat samples, such as a mouse ear or cells 22 , 23 because the surface of the sample and the scanning plane are approximately parallel, but it is not easy to understand the structure when the sample surface is curved, like the ocular vasculature Fig. Taking a different approach, the surface-based depth-encoded image represents the signal depth from the estimated ocular surface, so it is easier to understand the ocular vasculature. In Fig. The color difference makes it clear that the limbal vessels are located on a higher layer than the other vessels. Hence, an estimation error could occur when applying our algorithm to human eye images. However, we expect that this problem can be solved by considering several parameters, such as the radius of the iris and the anterior choroid curvature, separately in the estimation process. Additional time for processing would be required. We have demonstrated temporal and quantitative analysis of corneal neovascularization. Because corneal neovascularization is present in most cases of blindness related to corneal disease 25 , it is important to assess its progression and treatment response. Conventionally, corneal neovascularization is evaluated with slit-lamp biomicroscopy or photographs taken during slit-lamp examinations 26 , However, the visibility largely depends on the quality of images, and even in good quality images some vessels are not visible when accompanied by opaque scar tissue Recently, fluorescein and indocyanine green angiography have been utilized in some studies 29 , but their invasiveness and the risks of serious adverse reactions have hindered their wide use Our system provides high contrast images without labeling and additionally provides automated, objective quantification of corneal neovascularization within a few seconds after image acquisition. With the help of the RANSAC-based algorithm, we can evaluate choroidal and retinal vessels that lie deep from the surface. Photoacoustic imaging is valuable in imaging deep structures, but analysis of reconstructed 3D volume images and conventionally depth-encoded images is not intuitive. The RANSAC-based algorithm enables layer by layer analysis of multi-layered structures with curvature, and the resultant images can demonstrate temporal changes to users intuitively, as shown in Fig. The peripheral choroid has not received much attention from ophthalmologists, despite the presence of a watershed zone in the far temporal sector of the human choroid The watershed zone suggests that damages such as an alkali burn inflicted on the peripheral retrograde choroidal arteries can lead to choroidal ischemia in the area from the ora serrata to the watershed zone. Despite its significance, assessment of the peripheral choroid from inside is time-consuming and troublesome: Visualizing the choroidal vessels requires a diopter lens to expand the angle of view and indocyanine green for angiography In comparison, by imaging from the outside, our approach facilitates peripheral choroid evaluation. We conducted in vivo photoacoustic imaging of anterior ocular vasculatures with the help of RANSAC-based ocular surface estimation algorithm. The algorithm proved very useful for evaluating multi-layered and curved structures such as eyes. We have demonstrated intuitively understandable layer-by-layer images reconstructed from 3D volume photoacoustic data of the anterior ocular vasculature. We believe that our approaches will help expand the applications of PAT in ophthalmology. The future direction of this study is to apply this technology to human eyes. However, besides the problem of the opaque sclera and the anatomical differences of the eyeballs, there are some additional problems that the imaging speed is too slow and the coupling medium should be used. We believe that by using the non-contact imaging method, the problems could be solved For photoacoustic irradiation, we used a Nd: The objective numerical aperture NA was 0. In addition, laser safety on the scleral surface was also considered Therefore, the maximum permissible pulse energy was calculated to be about nJ, which is about 6 times larger than the energy we used. All animal experimental procedures were conducted following the laboratory animal protocol approved by the institutional animal care and use committee of the Pohang University of Science and Technology POSTECH. Then, the mouse was placed on an animal stage with a silicon-heating pad to maintain the body temperature of the mice during imaging. We used ultrasound gel on the mouse eye as a coupling medium between the eye and a water tank. Alkali- and acid-burn injuries were performed on the right eyes. We imaged the eyes on days 0 control and after burn , 7, 14, and 21 after chemical burn to observe the healing process. To observe the reactions near the limbal blood vessels after the alkaline and acid burns, we imaged near the limbus, including limbal, iris and choroidal blood vessels. During PA imaging, we pressed the area around the eye slightly to make the area more visible. To quantify the corneal neovascularization, we calculated the new vessel area considering the slope of the eye surface see Supplementary Fig. Because the detected new vessels were usually located on the spherical eye surface, the actual area of the corneal vessels became distorted when they projected in a 2D image. We assumed that the actual surface on the sphere, corresponding to each projected pixel, was flat to simplify the calculation:. Finally, the corrected corneal new vessel area, A C N V , was calculated by. K of Seoul National University. All authors contributed critical readings of the manuscript. Seungwan Jeon and Hyun Beom Song contributed equally to this work. Electronic supplementary material. Publisher's note: Springer Nature remains neutral with regard to jurisdictional claims in published maps and institutional affiliations. Jeong Hun Kim, Email: Chulhong Kim, Email: Sci Rep. Published online Jun Corresponding author. Received Jan 11; Accepted May To view a copy of this license, visit http: This article has been cited by other articles in PMC. Abstract Visualizing ocular vasculature is important in clinical ophthalmology because ocular circulation abnormalities are early signs of ocular diseases. Introduction Visualizing ocular vasculature is important in clinical ophthalmology because ischemia and neovascularization are early signs of various ocular diseases 1 , 2. Open in a separate window. Figure 1. Eye surface estimation based on random sample consensus RANSAC and vessel visualization We developed a RANSAC-based eye surface estimation method to reconstruct more intuitive ocular images than provided by conventional depth-encoded images and to analyze the ocular vasculature layer by layer. Detailed descriptions of each process step are given in the following: Figure 2. Table 1 Averaged GPU processing time to estimate surface. Averaged processing time Memory allocation and copy ms Matching ms Required number of repeats 9. Table 2 Representative average and standard deviation of the optimal parameters. Supra-surface vessel isolation enables temporal and quantitative evaluation of corneal neovascularization We have demonstrated isolation of vessels according to the surface estimated by the RANSAC-based algorithm. Figure 3. Surface vessel isolation enables in vivo evaluation of choroidal and retinal vessels Because photoacoustic imaging techniques enable imaging deep structures 16 , 17 , OR-PAM can visualize choroidal and retinal vessels beneath the sclera that forms the opaque outermost layer of an eyeball and prevents visualization of vessels underneath it. Figure 4. Animal preparation All animal experimental procedures were conducted following the laboratory animal protocol approved by the institutional animal care and use committee of the Pohang University of Science and Technology POSTECH. Quantification of corneal neovascularization To quantify the corneal neovascularization, we calculated the new vessel area considering the slope of the eye surface see Supplementary Fig. We assumed that the actual surface on the sphere, corresponding to each projected pixel, was flat to simplify the calculation: Electronic supplementary material Video S1 2. Acknowledgements S. Author Contributions S. Notes Competing Interests The authors declare that they have no competing interests. References 1. Choroidal neovascularization in age-related macular degeneration—what is the cause? Flammer J, et al. The impact of ocular blood flow in glaucoma. Our nanoslits had a 5-nm gap that extended up to the entire membrane, with a length of 0. This structure enabled us to achieve near-maximum field enhancement in the THz region. Our nanoslits had nanometre-wide metallic slits that extended along the entire length of the membrane, thus maintaining the uniform air gap throughout the length, as shown in the half-section schematic and top view presented in Fig. Nanoslits with gold film on the SiN x membrane were supported by the robust Si frame. The inset shows the nanogap in the metallic film. We first fabricated the nanoslits on the SiN x -coated Si substrate. Then, bulk Si was etched out through the back-side window, as presented in the schematic cross-sectional diagram in Fig. The fabrication details will be described in the methods section. Figure 1c shows a scanning electron microscopy SEM image of the top view of the nanoslits. The inset of Fig. In the optical image Fig. The optical transmission of white light through the nanogap indicated the clear formation of the nanogap, and the diffracted light of the longer wavelength was transmitted, whereas the transmission was null when the light was polarized along the slit direction. For this experiment, a mode-locked Ti: One of the beams impinged on the biased GaAs semiconductor crystal and emitted broadband THz from the metallic antenna patterned on the crystal. Then, THz was collected by a Si hemisphere and plane polarized before it was focused on the sample. The p-polarized THz pulses were normally focused on the nanogap slit. The THz time domain spectra were mathematically transformed into frequency domain spectra FDS via Fourier transformation. A Wollaston prism split the x- and y-polarized beam by using a balanced photodiode detector for the electric field amplitude measurement. The measurement was performed in both TM and TE modes; later, the enhancement of the normalized field amplitude was calculated by subtracting the transmission signal in the TE mode from that in the TM mode. Femtosecond laser pulses were divided for THz generation and detection. Broadband THz generated by the biased GaAs emitter was plane polarized, collimated and then focused on the nanoslits, and the transmitted beam was detected with a ZnTe crystal. A Wollaston prism separated the beam into two orthogonal, linearly polarized beams for the electric field amplitude measurement using a balanced photodiode detector. Figure 3a shows TDS data obtained from the gold nanoslits and the free space transmission from the aperture area, 0. The peak transmission amplitude through an array of 5-nm slits, which occupied only 0. In contrast, the direct THz transmission in the TE mode was less than 0. The shift indicated significant changes in the effective refractive indices. A typical reference and nanoslit sample used to measure TDS is presented on the right side of Fig. We obtained FDS, as shown in Fig. Figure 3b shows the field amplitude versus the frequency of the THz transmission from the nanoslits solid curve , which exhibits a similar trend as the free space dotted curve , thus indicating non-resonance transmission. The red dashed curve indicates the average field amplitude of the transmission of 10 samples. Furthermore, the field amplitudes were normalized to the free space transmission and are presented in Fig. The graph shows that the normalized field amplitude decreased with increasing frequency without any resonance. The non-resonance behaviour was attributed to the very high length-to-width ratio 1. We measured the far-field THz-TDS from free space and from the nanoslit sample with equal-sized apertures. This observation indicated that the effective thickness of the metal film was almost half that of the actual thickness, in agreement with an asymmetric shape with only half of the metal thickness forming the 5-nm gap. This result agreed with findings previously reported by S. Han et al. Higher field enhancement was observed at the lower frequency, which was almost ten thousand at approximately 0. In our setup, the minimum reliable frequency with which we could observe the drop in the field enhancement was 0. We believe that the enhancement was saturated beyond this frequency. The normalization was completed with the free space transmission through an aperture that was made with optically thick aluminium foil of the exact same size as the membrane. The experimental results of the 10 different samples are shown in the inset. To explain the very high field enhancement through the nanoslit without the substrate, we simply assumed that the nanoslit was a nanocapacitor that enabled the storage of a large charge. When THz waves pass through the nanoslits, the sidewalls of the slits act as nanocapacitors, owing to the oscillating opposite charge carrier concentrated around them. The charge density is proportional to the incident field and inversely proportional to the gap width. For narrow gaps, the charge density creates a very strong electric field that enhances the signal by several orders of magnitude relative to the incident electric field. The charges at the edges of the metallic slit oscillate with the alternation of the incident electric field and re-radiate the electromagnetic wave, where the gap acts as an antenna. The re-radiated power depends on the charge density or the electric field at the gap. By measuring the re-radiated electromagnetic waves, we estimated the field enhancement factor at the slit. The first experimental realization of a nonresonant field enhancement factor of nearly 1, was previously demonstrated with a nm-wide gold slit Our current measurement with 5-nm-wide nearly free-standing nanoslits is presented in Fig. Although our field enhancement factor was less than half of the resonant transmission through a slot antenna array with a nearly 1-nm gap, as reported by X. Chen et al. In our case, the gap width was a million times smaller than the wavelength; however, the length of the slit was of the same order as the wavelength. In order to analyse the substrate effects in transmission and the field enhancement factor, we performed TDS measurements with nanoslits on substrate and without substrate. The open black squares the amplitude was multiplied by 10 for comparability and the open red circles represent the transmission through the nanogap with and without substrate, respectively. The normalization was done separately with the transmission through the reference samples of Si substrate and free space aperture of the equal area. Our experimental results indicates the field enhancement increased by approximately 15 fold at 0. Some irregularities in transmission curve was also observed because of the grating modes when the slit array diffracted the incident radiation into the sample plane. This results can be explained by poor coupling of THz wave among the evanescent modes because of higher refractive index of substrate The effective refractive index for substrate is given by..

Int J Antenn Random slits sampling Extraordinary sensitivity Random slits sampling by metasurfaces in terahertz detection of antibiotics. Sci Rep-Uk 5 Colossal absorption of molecules inside single terahertz nanoantennas. Nano Read article 13—, Nonlinear optics, active plasmonics and metamaterials with liquid crystals. Except for the one-dimensional case, there is no exact The first stage is the same as the standard RSA simulation analytic solution to the RSA problem because the com- of hard-core systems described elsewhere.

To avoid checking for non- dynamics. As an extremely useful diagnostic approach, the local neighborhood of the attempted particle displace- simulation results can provide essentially exact data for ment. This simple RSA method has a severe shortcoming precisely defined Random slits sampling systems.

Sex boobl Watch PORN Movies Milfr porn. Random sequential adsorption, Two-dimensional parking model, Hard-disc packing A parking configuration for cars or hard-rods of equal Feder7 first observed the characteristic power law of RSA length on an infinite line, popularly known as the random car kinetics at long time, parking problem, is the classical one-dimensional version of 1 — random sequential adsorption RSA process. It is worth noting that df indicates the number of length of a rod, the parking is full or jamming. During the degree of freedom for a given object, and, in the case of RSA process, particles are deposited at random positions, isotropic particles in the continuum media, df -values are one at each time step, with the restriction that overlapping equal to the dimensionality d of the system, i. In con- trast, the equilibrium fluids exhibit the Markovian stochastic In the present work we have employed the computation- properties, in which the final state has no memory effect ally efficient method to generate RSA configurations of from the initial state. In our simulations the length is reduced in of higher-order dimensions. The conventional periodic boundary quantitative relevance of higher dimensional RSA has been condition is applied to the fundamental box in the axial z- demonstrated in various research areas including proteins, direction to approximate an infinite system in the thermo- colloidal particles, polymer chains, granular materials, etc. Particles are placed randomly and sequential- Very recently, by employing both numerical and theoretical ly inside the simulation area until the saturation jamming methods, Torquato and his coworkers5 have made the limit is achieved. In order to speed up computations in our systematic investigation for the RSA packing in Euclidean RSA simulations, there were two stages involved to deter- space over six hyper-dimensional systems. Except for the one-dimensional case, there is no exact The first stage is the same as the standard RSA simulation analytic solution to the RSA problem because the com- of hard-core systems described elsewhere. To avoid checking for non- dynamics. As an extremely useful diagnostic approach, the local neighborhood of the attempted particle displace- simulation results can provide essentially exact data for ment. This simple RSA method has a severe shortcoming precisely defined model systems. In the near jamming stage, most of machine experiments. For instance, it was from the simu- the accessible area is blocked and only tiny disconnected lation result for the two-dimensional hard-disc system that regions are available for further deposition. To overcome such difficulties, in the second stage, we have employed the event-driven algorithm8 by dividing the simulation slit along the z-direction between successive particle positions. If the interior space between two particles is partly accessible, we reduce the size of the accessible area using the known geometries, and, then reevaluate the availability of depositions into this smaller area. Figure 1. To our knowledge, apart from the case of the 1-d car parking problem, this 2-d narrow slit packing is another techniques, e. Scale bar: PA, photoacoustic; MAP, maximum amplitude projection. We developed a RANSAC-based eye surface estimation method to reconstruct more intuitive ocular images than provided by conventional depth-encoded images and to analyze the ocular vasculature layer by layer. In using this method, to simplify the estimation we assumed that the mouse eye in the PA image had a perfect spherical structure centered at a specific position. Briefly, we randomly sampled sets of the eyeball center position and the half-diameter within specific random sampling ranges, then quantified how well the each set of parameters matched the acquired 3D PA data. After the matching processes, the random sampling ranges are reduced using the top 5 sets of parameters that best match the PA data. We repeated these processes to find the optimal center position and half-diameter. All of the above processes are divided into six steps: Except for the preprocessing and post-processing steps, the surface estimation is accelerated by a graphics processing unit GPU. Detailed descriptions of each process step are given in the following:. Step 1 Pre-processing the 3D PA image: To increase the signal-to-noise ratio, the PA data is passed through a digital band-pass filter centered at the ultrasound center frequency and is enveloped by Hilbert transformation. The enveloped 3D data is downsized to reduce the calculation time. Step 2 Parameter random sampling: The number of the parameter sets is chosen to best use the constant memory size in the GPU. The initial random sampling ranges are selected as follows:. In this study, c x and c y are set to be a half of the PA image size because the eye is normally imaged at the center of the OR-PAM image. These initial random sampling ranges are consistently applied to all images. Step 3 Matching: Then we calculate the matching score, S n , as follows:. Step 4 Renewing the random sampling ranges: The random sampling ranges in Equation 1 are renewed by using the extracted top 5 parameter sets as follows:. Step 5 Repeating: We next try the surface estimation from Step 2 to Step 5 ten times with a single PA dataset to find the average processing time and to evaluate the precision of our estimation algorithm. On average, for a single process of Step 3, it takes about 23, ms and ms of CPU and GPU processing, respectively, and requires 9. Considering the additional time to initialize and finish the GPU processing, the total average processing time is 2. In our estimation method, we used single precision, which has seven significant digits. Hence, the final precision is fixed to be 0. However, as the minimum voxel size in our PA image was 2. Note that we thresholded the background of all conventional depth-encoded and surface-based depth-encoded images using the PA intensity. Normally, limbal vessels are located above the choroidal and retinal vessels, and corneal new vessels, induced by an injury on the anterior segment, grow along the outer eye surface. We segment the supra-surface vessels by thresholding the surface-based depth-encoded image. We observe that only limbal vessels and episcleral vessels are detected in the supra-surface image. In addition, the corneal new vessels are also successfully segmented from the alkali-burned mouse eyes and described in the Results, Section 3. In this projection process, the PA signals below the estimated surface, r ' , are excluded to eliminate reverberation artifacts. This processing is useful when vessels are stacked at the same position on the image plane. As an example, consider an alkali burn. Such a burn is known to induce corneal neovascularization 15 on a different layer than that of the iris vessels. We inflicted an alkali burn to the eyes of mice, followed by evaluation with photographs and PAM images. The photograph on day 7 shows notable edema of the cornea and conjunctiva where the burn was given, and subsequent photographs show relief of the edema, leaving opacity behind Fig. Interrupted visualization of the limbal vessels in the photographs could either reflect vessels damaged by the chemical burn or reflect undamaged vessels merely blocked from visualization by the overlying edema and opacity. In addition, neovascularization is detected throughout in the follow-up PAM images, but it is difficult to specify the layer and quantify the neovascularization from the photographs. In contrast, PAM could visualize vessels even in the area of edema and opacity. The surface-based depth-encoded images enabled tracking of vessels on the same layer, and revealed that limbal vessels are interrupted in the area of the chemical burn Fig. Furthermore, neovascularization is shown above the estimated surface, and new vessels are growing upward along the same layer Fig. The isolation of supra-surface vessels enables temporal follow-up of corneal neovascularization at a glance and clearly describes its progression, which starts from the limbus and grows toward the corneal center Fig. Considering the distortion induced by projecting the curved surface to the image plane, we could calculate the actual area of cornel neovascularization and record its temporal progression Fig. A detailed description of calculating the area from the images is given in the Methods section. We also implemented the isolation of the corneal neovascularization and quantified the area after an acid burn see Supplementary Fig. Two of the three corneal neovascularization areas increased by more than 0. The burned areas are highlighted with white dashed circles. Because photoacoustic imaging techniques enable imaging deep structures 16 , 17 , OR-PAM can visualize choroidal and retinal vessels beneath the sclera that forms the opaque outermost layer of an eyeball and prevents visualization of vessels underneath it. To evaluate the capability of our PAM system to assess deep vessels, we prepared normal eyes, eyes after an alkali burn, and eyes after an acid burn. Conjunctival swelling in both eyes after chemical burns to a lesser extent in eyes after acid burn and hemorrhages in eyes after alkali burns made visualization of deep vessels even more difficult Fig. Surface-based depth-encoded PAM images can to some degree visualize choroidal and retinal vessels, but it is still difficult to evaluate them due to overlying limbal vessels and hemorrhages Fig. To confirm the depth of damages, histologic assessments were performed. The acid-burned eyes show intact layers of the retina and choroid, while the alkali-burned eyes show structural disintegration that extends deep into the full thickness of the retina Fig. These results well agree with the previously report results that acids are generally less harmful than alkalis because coagulated proteins prevent acid penetration The burned areas are highlighted with red dashed circles. However, due to the nature of random-based sampling, RANSAC cannot always find the optimal set from the input dataset. In other words, the center position and half-diameter of the eye estimated via RANSAC could change whenever we estimate the parameters again. This serious problem might lead to inconsistent and unreliable results in both visualization and segmentation. Increasing the number of iterations is needed to minimize the probability of the problem. As mentioned, the high precision of RANSAC-based estimation requires a large number of iterations and a long computation time, especially when 3D data is addressed, as in this study. The conventional depth-encoded image represents the signal depth from a scanning plane. This image might be helpful in understanding the 3D structure of flat samples, such as a mouse ear or cells 22 , 23 because the surface of the sample and the scanning plane are approximately parallel, but it is not easy to understand the structure when the sample surface is curved, like the ocular vasculature Fig. Taking a different approach, the surface-based depth-encoded image represents the signal depth from the estimated ocular surface, so it is easier to understand the ocular vasculature. In Fig. The color difference makes it clear that the limbal vessels are located on a higher layer than the other vessels. Hence, an estimation error could occur when applying our algorithm to human eye images. However, we expect that this problem can be solved by considering several parameters, such as the radius of the iris and the anterior choroid curvature, separately in the estimation process. Additional time for processing would be required. We have demonstrated temporal and quantitative analysis of corneal neovascularization. Because corneal neovascularization is present in most cases of blindness related to corneal disease 25 , it is important to assess its progression and treatment response. Conventionally, corneal neovascularization is evaluated with slit-lamp biomicroscopy or photographs taken during slit-lamp examinations 26 , However, the visibility largely depends on the quality of images, and even in good quality images some vessels are not visible when accompanied by opaque scar tissue Recently, fluorescein and indocyanine green angiography have been utilized in some studies 29 , but their invasiveness and the risks of serious adverse reactions have hindered their wide use Our system provides high contrast images without labeling and additionally provides automated, objective quantification of corneal neovascularization within a few seconds after image acquisition. With the help of the RANSAC-based algorithm, we can evaluate choroidal and retinal vessels that lie deep from the surface. Photoacoustic imaging is valuable in imaging deep structures, but analysis of reconstructed 3D volume images and conventionally depth-encoded images is not intuitive. The RANSAC-based algorithm enables layer by layer analysis of multi-layered structures with curvature, and the resultant images can demonstrate temporal changes to users intuitively, as shown in Fig. The peripheral choroid has not received much attention from ophthalmologists, despite the presence of a watershed zone in the far temporal sector of the human choroid Bahk et al. A prominent question is how large a THz field can be enhanced by using nanoslits. We assumed that a major obstacle is the substrate, which decreases the transmission and creates undesirable interactions between the gap and the substrate. Moreover, multiple reflections Fabry—Perot resonances from the substrate degrade the signal quality. However, to generate fully free-standing nanoslits, substantial fabrication challenges must be overcome to allow tolerance of internal and external stresses from the membrane itself. Here, we demonstrate the experimental realization of very large field enhancement by using gold nanoslits on a Si 3 N 4 membrane. Our methods were based on atomic layer lithography combined with multiple layers of metal deposition and selective etching Here, the slit width was determined by using the atomic layer deposition ALD thickness in an optically opaque metal membrane. Our nanoslits had a 5-nm gap that extended up to the entire membrane, with a length of 0. This structure enabled us to achieve near-maximum field enhancement in the THz region. Our nanoslits had nanometre-wide metallic slits that extended along the entire length of the membrane, thus maintaining the uniform air gap throughout the length, as shown in the half-section schematic and top view presented in Fig. Nanoslits with gold film on the SiN x membrane were supported by the robust Si frame. The inset shows the nanogap in the metallic film. We first fabricated the nanoslits on the SiN x -coated Si substrate. Then, bulk Si was etched out through the back-side window, as presented in the schematic cross-sectional diagram in Fig. The fabrication details will be described in the methods section. Figure 1c shows a scanning electron microscopy SEM image of the top view of the nanoslits. The inset of Fig. In the optical image Fig. The optical transmission of white light through the nanogap indicated the clear formation of the nanogap, and the diffracted light of the longer wavelength was transmitted, whereas the transmission was null when the light was polarized along the slit direction. For this experiment, a mode-locked Ti: One of the beams impinged on the biased GaAs semiconductor crystal and emitted broadband THz from the metallic antenna patterned on the crystal. Then, THz was collected by a Si hemisphere and plane polarized before it was focused on the sample. The p-polarized THz pulses were normally focused on the nanogap slit. The THz time domain spectra were mathematically transformed into frequency domain spectra FDS via Fourier transformation. A Wollaston prism split the x- and y-polarized beam by using a balanced photodiode detector for the electric field amplitude measurement. The measurement was performed in both TM and TE modes; later, the enhancement of the normalized field amplitude was calculated by subtracting the transmission signal in the TE mode from that in the TM mode. Femtosecond laser pulses were divided for THz generation and detection. Broadband THz generated by the biased GaAs emitter was plane polarized, collimated and then focused on the nanoslits, and the transmitted beam was detected with a ZnTe crystal. A Wollaston prism separated the beam into two orthogonal, linearly polarized beams for the electric field amplitude measurement using a balanced photodiode detector. Figure 3a shows TDS data obtained from the gold nanoslits and the free space transmission from the aperture area, 0. The peak transmission amplitude through an array of 5-nm slits, which occupied only 0. In contrast, the direct THz transmission in the TE mode was less than 0. The shift indicated significant changes in the effective refractive indices. A typical reference and nanoslit sample used to measure TDS is presented on the right side of Fig. We obtained FDS, as shown in Fig. Figure 3b shows the field amplitude versus the frequency of the THz transmission from the nanoslits solid curve , which exhibits a similar trend as the free space dotted curve , thus indicating non-resonance transmission. The red dashed curve indicates the average field amplitude of the transmission of 10 samples. Furthermore, the field amplitudes were normalized to the free space transmission and are presented in Fig. The graph shows that the normalized field amplitude decreased with increasing frequency without any resonance. The non-resonance behaviour was attributed to the very high length-to-width ratio 1. We measured the far-field THz-TDS from free space and from the nanoslit sample with equal-sized apertures. This observation indicated that the effective thickness of the metal film was almost half that of the actual thickness, in agreement with an asymmetric shape with only half of the metal thickness forming the 5-nm gap. This result agreed with findings previously reported by S. Han et al. Higher field enhancement was observed at the lower frequency, which was almost ten thousand at approximately 0. In our setup, the minimum reliable frequency with which we could observe the drop in the field enhancement was 0. We believe that the enhancement was saturated beyond this frequency. The normalization was completed with the free space transmission through an aperture that was made with optically thick aluminium foil of the exact same size as the membrane. The experimental results of the 10 different samples are shown in the inset. To explain the very high field enhancement through the nanoslit without the substrate, we simply assumed that the nanoslit was a nanocapacitor that enabled the storage of a large charge. When THz waves pass through the nanoslits, the sidewalls of the slits act as nanocapacitors, owing to the oscillating opposite charge carrier concentrated around them. The charge density is proportional to the incident field and inversely proportional to the gap width. For narrow gaps, the charge density creates a very strong electric field that enhances the signal by several orders of magnitude relative to the incident electric field. The charges at the edges of the metallic slit oscillate with the alternation of the incident electric field and re-radiate the electromagnetic wave, where the gap acts as an antenna. The re-radiated power depends on the charge density or the electric field at the gap. By measuring the re-radiated electromagnetic waves, we estimated the field enhancement factor at the slit. The first experimental realization of a nonresonant field enhancement factor of nearly 1, was previously demonstrated with a nm-wide gold slit Our current measurement with 5-nm-wide nearly free-standing nanoslits is presented in Fig. Although our field enhancement factor was less than half of the resonant transmission through a slot antenna array with a nearly 1-nm gap, as reported by X. Chen et al..

In the near jamming Random slits sampling, most of machine experiments. For instance, it was from Random slits sampling simu- the accessible area is blocked and only tiny disconnected lation result for the two-dimensional hard-disc system that regions are available for further deposition.

To overcome such difficulties, in the second stage, we have employed the event-driven algorithm8 by dividing the simulation slit along the z-direction between successive particle positions.

If Random slits sampling interior space between two particles is partly accessible, we reduce the size of the accessible area using the known geometries, and, then reevaluate the availability of depositions into this smaller area. Figure 1. To our knowledge, apart from the case of the 1-d car parking problem, this 2-d narrow slit packing is another techniques, e. This two-stage procedure enables us Random slits sampling depositions in our model system. All simulation runs have jamming limit.

The 1-d jamm- successful depositions are tried, the time increment for each ing coverage is exactly evaluated to be about 0. The time expressions in Eqs. In our RSA model, however, the standard theories in the discrete lattice model, e. This discrepancy indicates that particle geo- standard way as in Eq.

Random slits sampling

Near the saturated jamming limit, almost all accessible areas are occupied by particles, and, the shape and distribution of very few remaining accessible areas will make an important role in further RSA processes. In summary, our new algorithm to simulate the RSA packing in the 2-dimensional narrow slit is found to be accurate and fast execution time to generate completely saturated Random slits sampling configurations for the systems of 0.

Sexy Romantic Sex Videos. Skip to main content. Log In Sign Up. Viorel Chihaia. Notes Bull. Korean Chem. Random sequential adsorption, Two-dimensional parking model, Hard-disc packing A parking configuration for cars or hard-rods of equal Feder7 first observed the characteristic power law of RSA length on an infinite line, popularly known as Random slits sampling random car kinetics at long time, parking problem, is the classical one-dimensional version of 1 — random sequential adsorption RSA process.

It is worth noting that df indicates the number of length of a rod, the parking is full or jamming. During the degree of freedom for a given object, and, in the case of RSA process, particles are deposited at random positions, isotropic particles in the continuum media, df -values are one at each time step, with Random slits sampling restriction that overlapping equal to the dimensionality d of the system, i.

In con- trast, the equilibrium fluids exhibit the Markovian stochastic In the present work we have employed the computation- properties, in which the final state has no Random slits sampling effect ally efficient method to generate RSA configurations of from the initial state. In our simulations the length is reduced in of higher-order dimensions.

The conventional periodic boundary quantitative relevance "Random slits sampling" higher dimensional Random slits sampling has been condition is applied to the fundamental box in the axial z- demonstrated in various research areas including proteins, direction to approximate an infinite system in the thermo- colloidal particles, polymer chains, granular materials, etc.

Particles are placed randomly and sequential- Very recently, by employing both numerical and theoretical ly inside the simulation area until the saturation jamming methods, Torquato and his coworkers5 have made the limit is achieved. In order to speed up computations in our systematic investigation for the RSA packing in Read article Random slits sampling simulations, there were two stages involved to deter- space over six hyper-dimensional systems.

Except for the one-dimensional case, there is no exact The first stage is the same as the standard RSA simulation analytic solution to the RSA problem because the com- of hard-core systems described elsewhere. To avoid checking for non- dynamics.

As an extremely useful diagnostic approach, the local neighborhood of the attempted particle displace- simulation results can provide essentially exact data for ment. This simple RSA method has a severe shortcoming precisely Random slits sampling model systems. In the near jamming stage, most of machine experiments.

For instance, it was from the simu- the accessible area is blocked and only tiny disconnected lation result for the two-dimensional hard-disc system that regions are available Random slits sampling further deposition. To overcome such difficulties, in the second stage, we have employed the event-driven algorithm8 by dividing the simulation slit along the z-direction between successive particle positions.

If Random slits sampling interior space Random slits sampling two particles is partly accessible, we reduce Random slits sampling size of the accessible area using the known geometries, and, then reevaluate the availability of depositions into this smaller area. Figure 1. To our knowledge, apart from the case of the 1-d car parking problem, this 2-d narrow slit packing is another Random slits sampling, e.

Legs fuck Watch XXX Movies Chubbyh Porn. Visualizing ocular vasculature is important in clinical ophthalmology because ocular circulation abnormalities are early signs of ocular diseases. Photoacoustic microscopy PAM images the ocular vasculature without using exogenous contrast agents, avoiding associated side effects. Moreover, 3D PAM images can be useful in understanding vessel-related eye disease. However, the complex structure of the multi-layered vessels still present challenges in evaluating ocular vasculature. In this study, we demonstrate a new method to evaluate blood circulation in the eye by combining in vivo PAM imaging and an ocular surface estimation method based on a machine learning algorithm: By using the developed estimation method, we were able to visualize the PA ocular vascular image intuitively and demonstrate layer-by-layer analysis of injured ocular vasculature. We believe that our method can provide more accurate evaluations of the eye circulation in ophthalmic applications. Visualizing ocular vasculature is important in clinical ophthalmology because ischemia and neovascularization are early signs of various ocular diseases 1 , 2. Conventionally, slit-lamp biomicroscopy is used to evaluate such disorders, but it is not able to show vessels clearly when the vasculature is accompanied by opaque scar tissue. Fluorescence angiography is also commonly used for ocular vascular imaging, but the injection of the required contrast agents can inflict pain and create potential complications. Optical coherence tomography OCT , another widely used tool nowadays, can provide high-resolution and volumetric images of both the ocular structure 3 and the vasculature by encoding the intensity variance resulting from blood flow 4. Photoacoustic microscopy PAM is an emerging imaging technology that also enables vasculature visualization in 3D 5 because of its innate depth-resolving imaging capability 6. PAM can provide an ocular vascular image based on the inherent optical absorbance of hemoglobin itself 7. Therefore, there is no side effect associated with exogenous contrast agent 8 , 9. Moreover, PAM. As an example, consider corneal neovascularization, an excessive ingrowth of vessels into the cornea. In , W. Liu et al. However, the classical smoothing techniques like least squares regression smooth out all datasets, so the fitting could be unstable and fail to detect corneal neovascularization when many outliers, generated from the new vessels, are included in the dataset In addition to corneal neovascularization, existing depth-visualizing methods have problems in observing the deep ocular vessels on curved surfaces covered with other blood vessels or hemorrhages because they show only sliced images at a certain depth 13 or projected images 5. The existing visualization method shows only the projected image or the lateral slice image at a certain depth. Therefore, it is a problem to observe deep veins when the ocular blood vessels on the curved surface are obscured by other blood vessels or hemorrhages. This iterative parameter estimation can produce a very accurate model by computing only inliers, even if the number of outliers is significant With the estimated ocular center position and half-diameter, by using the distance from the estimated eye surface we can reconstruct more intuitive depth-encoded images of the ocular vasculature than conventional depth-encoded images. From such a surface-based depth-encoded image, we successfully segmented the corneal new vessels induced after a chemical burn on a mouse eye and quantified the area of the neovascularization. Moreover, we confirmed that our new method could identify changes in deep vessels, even when the area was covered by limbal vessels and hemorrhages. Finally, histological validation agreed well with the PA imaging results. A detailed description of the system is provided in the Methods section. The OR-PAM maximum amplitude projection MAP image clearly shows the iris and limbal blood vessels as well as the choroidal and retinal vessels underlying the sclera Fig. The vascular network matches well with the conventional microscopy image highlighted with arrows i and ii. However, in the conventional microscopy image, the choroidal vessels are rarely visible due to the low contrast highlighted with arrows iii. Scale bar: PA, photoacoustic; MAP, maximum amplitude projection. We developed a RANSAC-based eye surface estimation method to reconstruct more intuitive ocular images than provided by conventional depth-encoded images and to analyze the ocular vasculature layer by layer. In using this method, to simplify the estimation we assumed that the mouse eye in the PA image had a perfect spherical structure centered at a specific position. Briefly, we randomly sampled sets of the eyeball center position and the half-diameter within specific random sampling ranges, then quantified how well the each set of parameters matched the acquired 3D PA data. After the matching processes, the random sampling ranges are reduced using the top 5 sets of parameters that best match the PA data. We repeated these processes to find the optimal center position and half-diameter. All of the above processes are divided into six steps: Except for the preprocessing and post-processing steps, the surface estimation is accelerated by a graphics processing unit GPU. Detailed descriptions of each process step are given in the following:. Step 1 Pre-processing the 3D PA image: To increase the signal-to-noise ratio, the PA data is passed through a digital band-pass filter centered at the ultrasound center frequency and is enveloped by Hilbert transformation. The enveloped 3D data is downsized to reduce the calculation time. Step 2 Parameter random sampling: The number of the parameter sets is chosen to best use the constant memory size in the GPU. The initial random sampling ranges are selected as follows:. In this study, c x and c y are set to be a half of the PA image size because the eye is normally imaged at the center of the OR-PAM image. These initial random sampling ranges are consistently applied to all images. Step 3 Matching: Then we calculate the matching score, S n , as follows:. Step 4 Renewing the random sampling ranges: The random sampling ranges in Equation 1 are renewed by using the extracted top 5 parameter sets as follows:. Step 5 Repeating: We next try the surface estimation from Step 2 to Step 5 ten times with a single PA dataset to find the average processing time and to evaluate the precision of our estimation algorithm. On average, for a single process of Step 3, it takes about 23, ms and ms of CPU and GPU processing, respectively, and requires 9. Considering the additional time to initialize and finish the GPU processing, the total average processing time is 2. In our estimation method, we used single precision, which has seven significant digits. Hence, the final precision is fixed to be 0. However, as the minimum voxel size in our PA image was 2. Note that we thresholded the background of all conventional depth-encoded and surface-based depth-encoded images using the PA intensity. Normally, limbal vessels are located above the choroidal and retinal vessels, and corneal new vessels, induced by an injury on the anterior segment, grow along the outer eye surface. We segment the supra-surface vessels by thresholding the surface-based depth-encoded image. We observe that only limbal vessels and episcleral vessels are detected in the supra-surface image. In addition, the corneal new vessels are also successfully segmented from the alkali-burned mouse eyes and described in the Results, Section 3. In this projection process, the PA signals below the estimated surface, r ' , are excluded to eliminate reverberation artifacts. This processing is useful when vessels are stacked at the same position on the image plane. As an example, consider an alkali burn. Such a burn is known to induce corneal neovascularization 15 on a different layer than that of the iris vessels. We inflicted an alkali burn to the eyes of mice, followed by evaluation with photographs and PAM images. The photograph on day 7 shows notable edema of the cornea and conjunctiva where the burn was given, and subsequent photographs show relief of the edema, leaving opacity behind Fig. Interrupted visualization of the limbal vessels in the photographs could either reflect vessels damaged by the chemical burn or reflect undamaged vessels merely blocked from visualization by the overlying edema and opacity. In addition, neovascularization is detected throughout in the follow-up PAM images, but it is difficult to specify the layer and quantify the neovascularization from the photographs. In contrast, PAM could visualize vessels even in the area of edema and opacity. The surface-based depth-encoded images enabled tracking of vessels on the same layer, and revealed that limbal vessels are interrupted in the area of the chemical burn Fig. Furthermore, neovascularization is shown above the estimated surface, and new vessels are growing upward along the same layer Fig. The isolation of supra-surface vessels enables temporal follow-up of corneal neovascularization at a glance and clearly describes its progression, which starts from the limbus and grows toward the corneal center Fig. Considering the distortion induced by projecting the curved surface to the image plane, we could calculate the actual area of cornel neovascularization and record its temporal progression Fig. A detailed description of calculating the area from the images is given in the Methods section. We also implemented the isolation of the corneal neovascularization and quantified the area after an acid burn see Supplementary Fig. Two of the three corneal neovascularization areas increased by more than 0. The burned areas are highlighted with white dashed circles. In contrast, the direct THz transmission in the TE mode was less than 0. The shift indicated significant changes in the effective refractive indices. A typical reference and nanoslit sample used to measure TDS is presented on the right side of Fig. We obtained FDS, as shown in Fig. Figure 3b shows the field amplitude versus the frequency of the THz transmission from the nanoslits solid curve , which exhibits a similar trend as the free space dotted curve , thus indicating non-resonance transmission. The red dashed curve indicates the average field amplitude of the transmission of 10 samples. Furthermore, the field amplitudes were normalized to the free space transmission and are presented in Fig. The graph shows that the normalized field amplitude decreased with increasing frequency without any resonance. The non-resonance behaviour was attributed to the very high length-to-width ratio 1. We measured the far-field THz-TDS from free space and from the nanoslit sample with equal-sized apertures. This observation indicated that the effective thickness of the metal film was almost half that of the actual thickness, in agreement with an asymmetric shape with only half of the metal thickness forming the 5-nm gap. This result agreed with findings previously reported by S. Han et al. Higher field enhancement was observed at the lower frequency, which was almost ten thousand at approximately 0. In our setup, the minimum reliable frequency with which we could observe the drop in the field enhancement was 0. We believe that the enhancement was saturated beyond this frequency. The normalization was completed with the free space transmission through an aperture that was made with optically thick aluminium foil of the exact same size as the membrane. The experimental results of the 10 different samples are shown in the inset. To explain the very high field enhancement through the nanoslit without the substrate, we simply assumed that the nanoslit was a nanocapacitor that enabled the storage of a large charge. When THz waves pass through the nanoslits, the sidewalls of the slits act as nanocapacitors, owing to the oscillating opposite charge carrier concentrated around them. The charge density is proportional to the incident field and inversely proportional to the gap width. For narrow gaps, the charge density creates a very strong electric field that enhances the signal by several orders of magnitude relative to the incident electric field. The charges at the edges of the metallic slit oscillate with the alternation of the incident electric field and re-radiate the electromagnetic wave, where the gap acts as an antenna. The re-radiated power depends on the charge density or the electric field at the gap. By measuring the re-radiated electromagnetic waves, we estimated the field enhancement factor at the slit. The first experimental realization of a nonresonant field enhancement factor of nearly 1, was previously demonstrated with a nm-wide gold slit Our current measurement with 5-nm-wide nearly free-standing nanoslits is presented in Fig. Although our field enhancement factor was less than half of the resonant transmission through a slot antenna array with a nearly 1-nm gap, as reported by X. Chen et al. In our case, the gap width was a million times smaller than the wavelength; however, the length of the slit was of the same order as the wavelength. In order to analyse the substrate effects in transmission and the field enhancement factor, we performed TDS measurements with nanoslits on substrate and without substrate. The open black squares the amplitude was multiplied by 10 for comparability and the open red circles represent the transmission through the nanogap with and without substrate, respectively. The normalization was done separately with the transmission through the reference samples of Si substrate and free space aperture of the equal area. Our experimental results indicates the field enhancement increased by approximately 15 fold at 0. Some irregularities in transmission curve was also observed because of the grating modes when the slit array diffracted the incident radiation into the sample plane. This results can be explained by poor coupling of THz wave among the evanescent modes because of higher refractive index of substrate The effective refractive index for substrate is given by. A schematic flow chart of the fabrication process is presented in Fig. We first fabricated the ALD nanogap in the metal on the Si substrate and then used atomic layer lithography and plugged and lifted off the excess metal by etching the sacrificial layer Finally, Al 2 O 3 and the SiO 2 layer were etched out, thereby releasing the air gap gold nanoslits. After the first metal layer Au: An Al 2 O 3 layer was deposited Fig. In ALD, Tri-methylaluminium and water vapour were sequentially pulsed through the chamber, with N 2 purging after each injection, until 19 cycles yielded 5-nm-thick Al 2 O 3. The lift-off of the second layer removed excess metal and opened up the ALD layer in between the first and second layers. The etchant also slightly etched Al 2 O 3 , and ultra-sonication and cleaning in acetone, methanol and deionized DI water were performed to remove residues at the nanogap. The back-side bulk silicon was selectively etched out Fig. The SiO 2 protected the nanogap and supported the etching of Si by preventing the metal-coated Si substrate from forming as an etch shield. The protective layer was later etched out by dipping it in HF solution, which also removed the bottom SiO 2 layer Fig. Dipping the sample in HF also etched the alumina between the metal, thereby exposing the air gap in the metal. To release the fully free-standing nanogap metal membrane for material transportation through the slits, the remaining thin Si 3 N 4 membrane was also etched out with reactive ion etching RIE. In most cases, after etching the nitride membrane, the gold membrane became unstable and collapsed. The nanogaps either collapsed or, where the bridge-like structure survived, widened. Thus, we kept the robust nitride membrane to support the metallic nanoslits and increase the stability of the nanogap for the THz experiments. A large nonresonant electromagnetic field enhancement was experimentally realized with practically infinite gold nanoslits. The large field enhancement in the nanogap region can be explained by the nanocapacitor model, and is formed as a result of the excitation of SPPs when the THz field is incident on the metal surface. The substrate-free nanoslits were fabricated using plug-and-lift-off and standard Si microfabrication techniques in which the gap width and uniformity were determined by atomic layer lithography. The yield of such an ultra-thin nanoslit membrane depends on the strength of the metal microribbon, with negligible deformities due to temperature and pressure. The developed substrate-free nanoslits may be useful in studies of gap plasmonics, quantum tunnelling, nonlinear optics, and nanophotonics, for which high field enhancement is important. How to cite this article: Suwal, O. Nonresonant 10 4 Terahertz Field Enhancement with 5-nm Slits. We are currently in the progress for applying this new algorithm to investigate the RSA structural properties of both 2-d and 3-d slit model systems to compare with micro- canonical equilibrium systems. This work is supported by the grant as the dashed-line in this figure. SHS also wishes to thank to Mr. In the initial time regime, simulation results show the rapid increase in the coverage values, References suggesting that most particles get occupied in the initial RSA packing process. In the intermediate regime, after very steep 1. Renyi, A. A , , asymptotic regime where the coverage reaches near constant The RSA packing exhibits several interesting features 3. New York, E , 69, Torquato, S. E , 74, The power law exponent df can be determined from the As mentioned previously in Eq. In Random Heterogeneous Materials: Microstructure 1 , the jamming density approaches via the power law in the and Macroscopic Properties; Springer-Verlag: Feder, J. RSA model. From the slope of the log-log plot in Figure 8..

This two-stage procedure enables us to depositions in our model system. All simulation runs have jamming limit. The 1-d jamm- successful depositions are tried, the time increment for each ing coverage is exactly evaluated to be about Random slits sampling. The time expressions in Eqs. In our RSA model, however, the standard theories in the discrete lattice model, e. This discrepancy indicates that particle geo- standard way Random slits sampling in Eq.

Near the saturated jamming limit, almost all accessible areas are occupied by particles, and, the shape and distribution of very few remaining accessible areas will make an important role in further RSA processes. In summary, our new Random slits sampling to simulate the RSA packing in the 2-dimensional narrow slit is found to be accurate and fast execution time to generate completely saturated jamming configurations for the systems of 0. We are currently in the progress for applying this new algorithm to investigate the RSA structural properties of both 2-d and 3-d slit model systems to compare with micro- canonical equilibrium systems.

This work is supported by the grant as the dashed-line in this figure. SHS also wishes to thank to Mr. In the initial time regime, simulation results show the rapid increase in Random slits sampling coverage values, References suggesting that most particles get occupied in the initial RSA packing process. In the intermediate regime, after very steep 1.

Renyi, A. A, asymptotic regime where the coverage reaches near constant The RSA packing exhibits several interesting features 3. New York, E69, Torquato, S. E74, The power Random slits sampling exponent df can be determined from the As mentioned previously in Eq. In Random Heterogeneous Materials: Microstructure 1the jamming density approaches via the power Random slits sampling in the and Macroscopic Properties; Springer-Verlag: Feder, J.

RSA Random slits sampling. From the slope of the learn more here plot in Figure 8. C5, Download pdf. Remember me on this computer. Enter the email address you signed up with and we'll email you a reset link.

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