In vivo visualization of burn depth in skin tissue of rats using hemoglobin parameters estimated by diffuse reflectance spectral imaging.

Significance: Burn injuries represent a global public health problem that kills an estimated 180,000 people annually. Non-fatal burns result in prolonged hospitalization, disfigurement, and disability. The most common, convenient, and widely used method for assessing burn depth is physical or visual examination, but the accuracy of this method is reportedly poor (60% to 75%). Rapid, correct assessment of burn depth is very important for the optimal management and treatment of burn patients. New methods of burn depth assessment that are inexpensive, simple, rapid, non-contact, and non-invasive are therefore needed. Aim: The aim of this study was to propose an approach to visualize the spatial distribution of burn depth using hemoglobin parameters estimated from spectral diffuse reflectance imaging and to demonstrate the feasibility of the proposed approach for differentiating burn depth in a rat model of scald burn injury. Approach: The new approach to creating a spatial map of burn depth was based on canonical discriminant analysis (CDA) of total hemoglobin concentration, tissue oxygen saturation, and methemoglobin saturation as estimated from spectral diffuse reflectance images. Burns of three different degrees of severity were created in rat dorsal skin by 10-s exposure to water maintained at 70°C, 78°C, and 98°C, respectively. Spectral images for dorsal regions were acquired under anesthesia immediately after burn injury and at 24 h, 48 h, and 72 h after injury. Results: Most areas of images in the group with skin exposed to 70°C water and 98°C water were classified as 70°C burn and 98°C burn, respectively. In contrast, no significant difference between areas classified as 78°C burn and 98°C burn from 24 h to 72 h was evident in the group with skin exposed to 78°C water, suggesting that burn depth was heterogeneous. Conclusions: The proposed approach combining diffuse reflectance spectral imaging and CDA appears promising for differentiating 70°C burns from 78°C burns and 98°C burns, and 98°C burns from 70°C burns and 78°C burns at 24 to 72 h after burn injury in a rat model of scald burn injury.

Digital holography without a dark room environment: extraction of interference fringes by using deep learning.

When obtaining digital holograms, dark rooms are used to prevent the influence of natural light on the formation of holograms. Further, in recent years, researchers have actively studied machine learning techniques such as deep learning to resolve image-related problems. In this study, we obtained a pair of holograms influenced by natural light and holograms unaffected by natural light, and trained U-Net to perform image transformation to remove the effects of natural light from holograms. Thus, this study aimed to propose a method for eliminating the effects of natural light from holograms by using the U-Net we trained. To verify the effectiveness of the proposed method, we evaluated the image quality of the reconstructed image of holograms before and after image processing by U-Net. The results showed that the peak signal-to-noise ratio (PSNR) increased by 7.38 [dB] after processing by U-Net. Additionally, the structural similarity index (SSIM) increased by 0.0453 after processing by U-Net. This study confirmed that in digital holography, holograms can be acquired without the use of a dark room and that the method proposed in this study can eliminate the effects of natural light and produce high-quality reconstructed images.

Image quality improvement of random phase-free holograms by addressing the cause of ringing artifacts.

Holographic projectors utilize holography techniques, although there are several barriers to realizing holographic projections. One such challenge is the deterioration of the hologram image quality caused by speckle noise and ringing artifacts. Several methods designed to reduce the speckle noise and ringing artifacts have been proposed. However, these methods require multiple diffraction calculations and a significant amount of computational time. In this paper, we reveal that ringing artifacts are due to object light being recorded on the edge of the hologram and that the high-frequency component of the original image leaks outside of the recording area of the hologram when the random phase-free method is used. Therefore, this study proposes an object light centering method that prevents object light from being recorded on the edge of the hologram and prevents the high-frequency component of the original image from leaking outside the recording area of the hologram, which removes the ringing artifact and extends the random phase-free method to an off-axis hologram.

Histone H2A insufficiency causes chromosomal segregation defects due to anaphase chromosome bridge formation at rDNA repeats in fission yeast.

The nucleosome, composed of DNA and a histone core, is the basic structural unit of chromatin. The fission yeast Schizosaccharomyces pombe has two genes of histone H2A, hta1+ and hta2+; these genes encode two protein species of histone H2A (H2Aα and H2Aß, respectively), which differ in three amino acid residues, and only hta2+ is upregulated during meiosis. However, it is unknown whether S. pombe H2Aα and H2Aß have functional differences. Therefore, in this study, we examined the possible functional differences between H2Aα and H2Aß during meiosis in S. pombe. We found that deletion of hta2+, but not hta1+, causes defects in chromosome segregation and spore formation during meiosis. Meiotic defects in hta2+ deletion cells were rescued by expressing additional copies of hta1+ or by expressing hta1+ from the hta2 promoter. This indicated that the defects were caused by insufficient amounts of histone H2A, and not by the amino acid residue differences between H2Aα and H2Aß. Microscopic observation attributed the chromosome segregation defects to anaphase bridge formation in a chromosomal region at the repeats of ribosomal RNA genes (rDNA repeats). These results suggest that histone H2A insufficiency affects the chromatin structures of rDNA repeats, leading to chromosome missegregation in S. pombe.

Miniature holographic projector with cloud computing capability.

A fully functional miniaturized projection head below 5 cm3 is presented, using computer-generated holograms dynamically displayed on a liquid-crystal spatial light modulator. Spatial division of the modulator is used for color projection without color breakup, and specially designed, anti-reflection coated prisms ensure simple light paths with small losses. Real-time calculations are performed on a remote server with on-the-fly compression of holographic fringes. Cloud computing allows 1 W of local electrical power usage and apparent image brightness equivalent to 15-500 lm/W efficiency, depending on the displayed content. The properties of the projector allow future applications in handheld displays.

Simple Isolation of Single Cell: Thin Glass Microfluidic Device for Observation of Isolated Single Euglena gracilis Cells.

Single cell analysis has gained attention as a means to investigate the heterogeneity of cells and amplify a cell with desired characteristics. However, obtaining a single cell from a large number of cells remains difficult because preparation of single-cell samples relies on conventional techniques such as pipetting that are labor intensive. In this study, we developed a system combining a 0.6-mm thin glass microfluidic device and machine vision approach to isolate single Euglena gracilis cells, as a model of microorganism with mobility, in a small/thin glass chamber. A single E. gracilis cell in a chamber was cultured for 4 days to monitor its multiplication. With this system, we successfully simplified preparation of single cells of interest and determined that it is possible to combine it with other analytical techniques to observe single cells continuously.

Convolutional neural network-based data page classification for holographic memory.

We propose a deep-learning-based classification of data pages used in holographic memory. We numerically investigated the classification performance of a conventional multilayer perceptron (MLP) and a deep neural network, under the condition that reconstructed page data are contaminated by some noise and are randomly laterally shifted. When data pages are randomly laterally shifted, the MLP was found to have a classification accuracy of 93.02%, whereas the deep neural network was able to classify data pages at an accuracy of 99.98%. The accuracy of the deep neural network is 2 orders of magnitude better than the MLP.

Autoencoder-based holographic image restoration.

We propose a holographic image restoration method using an autoencoder, which is an artificial neural network. Because holographic reconstructed images are often contaminated by direct light, conjugate light, and speckle noise, the discrimination of reconstructed images may be difficult. In this paper, we demonstrate the restoration of reconstructed images from holograms that record page data in holographic memory and quick response codes by using the proposed method.

Speeding up image quality improvement in random phase-free holograms using ringing artifact characteristics.

A holographic projector utilizes holography techniques. However, there are several barriers to realizing holographic projections. One is deterioration of hologram image quality caused by speckle noise and ringing artifacts. The combination of the random phase-free method and the Gerchberg-Saxton (GS) algorithm has improved the image quality of holograms. However, the GS algorithm requires significant computation time. We propose faster methods for image quality improvement of random phase-free holograms using the characteristics of ringing artifacts.

Fission yeast APC/C activators Slp1 and Fzr1 sequentially trigger two consecutive nuclear divisions during meiosis.

In meiosis, two rounds of nuclear division occur consecutively without DNA replication between the divisions. We isolated a fission yeast mutant in which the nucleus divides only once to generate two spores, as opposed to four, in meiosis. In this mutant, we found that the initiation codon of the slp1+ gene is converted to ATA, producing a reduced amount of Slp1. As a member of the Fizzy family of anaphase-promoting complex/cyclosome (APC/C) activators, Slp1 is essential for vegetative growth; however, the mutant allele shows a phenotype only in meiosis. Slp1 insufficiency delays degradation of maturation-promoting factor at the first meiotic division, and another APC/C activator, Fzr1, which acts late in meiosis, terminates meiosis immediately after the delayed first division to produce two viable spores.

Holographic microinformation hiding.

We propose a holographic microinformation hiding scheme in which the embedding information to be embedded is small and imperceptible to the human eyes. This scheme converts the embedding information into a complex amplitude via scaled diffraction. The complex amplitude of the reduced embedding information is added to the complex amplitude of the host image, followed by conversion to a hologram. The reduced embedded information is inconspicuous from the hologram during the reconstruction process; however, the reduction leads to the degradation of the embedded image quality. Therefore, to improve the quality of the embedded image quality, we employ iterative optimization and the time averaging effect of multiple holograms.

Color computer-generated hologram generation using the random phase-free method and color space conversion.

We propose two calculation methods of generating color computer-generated holograms (CGHs) with the random phase-free method and color space conversion in order to improve the image quality and accelerate the calculation. The random phase-free method improves the image quality in monochrome CGH, but it is not performed in color CGH. We first aimed to improve the image quality of color CGH using the random phase-free method and then to accelerate the color CGH generation with a combination of the random phase-free method and color space conversion method, which accelerates the color CGH calculation due to down-sampling of the color components converted by color space conversion. To overcome the problem of image quality degradation that occurs due to the down-sampling of random phases, the combination of the random phase-free method and color space conversion method improves the quality of reconstructed images and accelerates the color CGH calculation. We demonstrated the effectiveness of the proposed method in simulation, and in this paper discuss its application to lensless zoomable holographic projection.

Holographic multi-projection using the random phase-free method.

We demonstrated holographic multi-projection using the random phase-free method and the iterative method. Holographic multi-projection is a method of projecting multiple different images focused on different screens at the same time. The random phase-free method succeeded in improving the image quality. By applying the iterative method to the random phase-free method, the image quality was improved further. The results of our numerical reconstruction and optical experiments confirm that the proposed method improves the image quality. The peak signal-to-noise ratios of the reconstructed images using the proposed method and the conventional method are 30.66 and 13.61 dB, respectively.

Meiotic cohesin-based chromosome structure is essential for homologous chromosome pairing in Schizosaccharomyces pombe.

Chromosome structure is dramatically altered upon entering meiosis to establish chromosomal architectures necessary for the successful progression of meiosis-specific events. An early meiotic event involves the replacement of the non-SMC mitotic cohesins with their meiotic equivalents in most part of the chromosome, forming an axis on meiotic chromosomes. We previously demonstrated that the meiotic cohesin complex is required for chromosome compaction during meiotic prophase in the fission yeast Schizosaccharomyces pombe. These studies revealed that chromosomes are elongated in the absence of the meiotic cohesin subunit Rec8 and shortened in the absence of the cohesin-associated protein Pds5. In this study, using super-resolution structured illumination microscopy, we found that Rec8 forms a linear axis on chromosomes, which is required for the organized axial structure of chromatin during meiotic prophase. In the absence of Pds5, the Rec8 axis is shortened whereas chromosomes are widened. In rec8 or pds5 mutants, the frequency of homologous chromosome pairing is reduced. Thus, Rec8 and Pds5 play an essential role in building a platform to support the chromosome architecture necessary for the spatial alignment of homologous chromosomes.

Random phase-free kinoform for large objects.

We propose a random phase-free kinoform for large objects. When not using the random phase in kinoform calculation, the reconstructed images from the kinoform are heavy degraded, like edge-only preserved images. In addition, the kinoform cannot record an entire object that exceeds the kinoform size because the object light does not widely spread. In order to avoid this degradation and to widely spread the object light, the random phase is applied to the kinoform calculation; however, the reconstructed image is contaminated by speckle noise. In this paper, we overcome this problem by using our random phase-free method and error diffusion method.