HoloSR: deep learning-based super-resolution for real-time high-resolution computer-generated holograms.

This study presents HoloSR, a novel deep learning-based super-resolution approach designed to produce high-resolution computer-generated holograms from low-resolution RGBD images, enabling the real-time production of realistic three-dimensional images. The HoloSR combines the enhanced deep super-resolution network with resize and convolution layers, facilitating the direct generation of high-resolution computer-generated holograms without requiring additional interpolation. Various upscaling scales, extending up to ×4, are evaluated to assess the performance of our method. Quantitative metrics such as structural similarity and peak signal-to-noise ratio are employed to measure the quality of the reconstructed images. Our simulation and experimental results demonstrate that HoloSR successfully achieves super-resolution by generating high-resolution holograms from low-resolution RGBD inputs with supervised and unsupervised learning.

The Clinical Courses and Prognosis of Cirrhotic Patients after First Acute Decompensation: Prospective Cohort Study.

BACKGROUND: The European Foundation for the Study of Chronic Liver Failure (EF-CLIF) consortium suggested that the clinical courses after acute decompensation (AD) stratify the long-term prognosis: stable decompensated cirrhosis (SDC), unstable decompensated cirrhosis (UDC), pre acute-on-chronic liver failure (pre ACLF), and ACLF. However, previous studies included patients with a history of previous AD and had limitations associated with identifying the clinical factors related to prognosis after the first AD. METHOD: The prospective Korean Acute-on-Chronic Liver Failure (KACLiF) cohort included cirrhotic patients who were hospitalised with first AD between July 2015 and August 2018. We analysed the factors associated with readmission after the first AD and compared the characteristics and prognosis among each subgroup to evaluate the risk factors for the occurrence of pre ACLF after AD. RESULT: A total of 746 cirrhotic patients who were hospitalised with first AD were enrolled. The subgroups consisted of SDC (n = 565), UDC (n = 29), pre ACLF (n = 28), and ACLF (n = 124). Of note, pre ACLF showed a poorer prognosis than ACLF. The risk factors associated with readmission within 3 months of first AD were non-variceal gastrointestinal (GI) bleeding, hepatic encephalopathy (HE), and high MELD score. Viral aetiology was associated with the occurrence of pre ACLF compared with alcohol aetiology regardless of baseline liver function status. CONCLUSION: Cirrhotic patients with first AD who present as non-variceal GI bleeding and HE can easily relapse. Interestingly, the occurrence of AD with organ failure within 3 months of first AD (pre ACLF) has worse prognosis compared with the occurrence of organ failure at first AD (ACLF). In particular, cirrhotic patients with viral hepatitis with/without alcohol consumption showed poor prognosis compared to other aetiologies. Therefore, patients with ACLF after AD within 3 months should be treated more carefully and definitive treatment through LT should be considered.

Accelerating a spatially varying aberration correction of holographic displays with low-rank approximation.

Correction of spatially varying aberrations in holographic displays often requires intractable computational loads. In this Letter, we introduce a low-rank approximation method that decomposes sub-holograms into a small number of modes, thereby reformulating the computer-generated hologram calculation into a summation of a few convolutions. The low-rank approximation is carried out with two different algorithms: the Karhunen-Loeve transform as the optimum solution with respect to the mean-squared error criterion and a novel, to the best of our knowledge, optimization method to provide uniform image quality over the entire field of view. The proposed method is two orders of magnitude faster than the conventional point-wise integration method in our experimental setup, with comparable image quality.

Platelet-to-White Blood Cell Ratio Is Associated with Adverse Outcomes in Cirrhotic Patients with Acute Deterioration.

Background: The platelet-to-white blood cell ratio (PWR) is a hematologic marker of the systemic inflammatory response. Recently, the PWR was revealed to have a role as an independent prognostic factor for mortality in patients with hepatitis B virus (HBV)-related acute-on-chronic failure (ACLF) and HBV-related liver cirrhosis (LC) with acute decompensation (AD). However, the prognostic role of the PWR still needs to be investigated in LC patients with AD. In this study, we analyzed whether the PWR could stratify the risk of adverse outcomes (death or liver transplantation (LT)) in these patients. Methods: A prospective cohort of 1670 patients with AD of liver cirrhosis ((age: 55.2 ± 7.8, male = 1226 (73.4%)) was enrolled and evaluated for 28-day and overall adverse outcomes. Results: During a median follow-up of 8.0 months (range, 1.9−15.5 months), 424 (25.4%) patients had adverse outcomes (death = 377, LT = 47). The most common etiology of LC was alcohol use (69.7%). The adverse outcome rate was higher for patients with a PWR ≤ 12.1 than for those with a PWR > 12.1. A lower PWR level was a prognostic factor for 28-day adverse outcomes (PWR: hazard ratio 1.707, p = 0.034) when adjusted for the etiology of cirrhosis, infection, ACLF, and the MELD score. In the subgroup analysis, the PWR level stratified the risk of 28-day adverse outcomes regardless of the presence of ACLF or the main form of AD but not for those with bacterial infection. Conclusions: A lower PWR level was associated with 28-day adverse outcomes, indicating that the PWR level can be a useful and simple tool for stratifying the risk of 28-day adverse outcomes in LC patients with AD.

Expanding energy envelope in holographic display via mutually coherent multi-directional illumination.

Holographic display is considered as the most promising three-dimensional (3D) display due to its unique feature of reconstructing arbitrary wavefronts. However, the limited étendue, which hinders the immersive experience of observers, remains a major unresolved issue in holographic display technique. In this paper, we propose a novel approach to tweak the constraints of étendue by expanding the energy envelope in holographic display via mutually coherent multi-illumination. The proposed concept contains both a light source design for generating a mutually coherent multi-directional wave and a computer-generated hologram optimization framework for providing high-resolution 3D holograms. To verify the proposed approach, a benchtop prototype of a holographic near-eye display providing an intrinsic large exit-pupil is implemented. The experimental results clearly show that the exit-pupil is effectively expanded by four times and an appropriate viewpoint image is reconstructed according to the view position.

Learning-based compensation of spatially varying aberrations for holographic display [Invited].

We propose a hologram generation technique to compensate for spatially varying aberrations of holographic displays through machine learning. The image quality of the holographic display is severely degraded when there exist optical aberrations due to misalignment of optical elements or off-axis projection. One of the main advantages of holographic display is that aberrations can be compensated for without additional optical elements. Conventionally, computer-generated holograms for compensation are synthesized through a point-wise integration method, which requires large computational loads. Here, we propose to replace the integration with a combination of fast-Fourier-transform-based convolutions and forward computation of a deep neural network. The point-wise integration method took approximately 95.14 s to generate a hologram of 1024×1024pixels, while the proposed method took about 0.13 s, which corresponds to ×732 computation speed improvement. Furthermore, the aberration compensation by the proposed method is verified through experiments.

The flip-flop configuration of the PABP-dimer leads to switching of the translation function.

Poly(A)-binding protein (PABP) is a translation initiation factor that interacts with the poly(A) tail of mRNAs. PABP bound to poly(A) stimulates translation by interacting with the eukaryotic initiation factor 4G (eIF4G), which brings the 3' end of an mRNA close to its 5' m7G cap structure through consecutive interactions of the 3'-poly(A)-PABP-eIF4G-eIF4E-5' m7G cap. PABP is a highly abundant translation factor present in considerably larger quantities than mRNA and eIF4G in cells. However, it has not been elucidated how eIF4G, present in limited cellular concentrations, is not sequestered by mRNA-free PABP, present at high cellular concentrations, but associates with PABP complexed with the poly(A) tail of an mRNA. Here, we report that RNA-free PABPs dimerize with a head-to-head type configuration of PABP, which interferes in the interaction between PABP and eIF4G. We identified the domains of PABP responsible for PABP-PABP interaction. Poly(A) RNA was shown to convert the PABP-PABP complex into a poly(A)-PABP complex, with a head-to-tail-type configuration of PABP that facilitates the interaction between PABP and eIF4G. Lastly, we showed that the transition from the PABP dimer to the poly(A)-PABP complex is necessary for the translational activation function.

Optimization of computer-generated holograms featuring phase randomness control.

In this Letter, we introduce a computer-generated hologram (CGH) optimization technique that can control the randomness of the reconstructed phase. The phase randomness significantly affects the eyebox size and depth of field in holographic near-eye displays. Our proposal is to synthesize the CGH through the sum of two terms computed from the target scene with a random phase. We set a weighting pattern for summation as the optimization variable, which enables the CGH to reflect the random phase during optimization. We evaluate the proposed algorithm on single-depth and multi-depth contents, and the performance is validated via simulations and experiments.

Vision-correcting holographic display: evaluation of aberration correcting hologram.

Vision-correcting displays are key to achieving physical and physiological comforts to the users with refractive errors. Among such displays are holographic displays, which can provide a high-resolution vision-adaptive solution with complex wavefront modulation. However, none of the existing hologram rendering techniques have considered the optical properties of the human eye nor evaluated the significance of vision correction. Here, we introduce vision-correcting holographic display and hologram acquisition that integrates user-dependent prescriptions and a physical model of the optics, enabling the correction of on-axis and off-axis aberrations. Experimental and empirical evaluations of the vision-correcting holographic displays show the competence of holographic corrections over the conventional vision correction solutions.

Light source optimization for partially coherent holographic displays with consideration of speckle contrast, resolution, and depth of field.

Speckle reduction is an important topic in holographic displays as speckles not only reduce signal-to-noise ratio but also possess an eye-safety issue. Despite thorough exploration of speckle reduction methods using partially coherent light sources, the trade-off involved by the partial coherence has not been thoroughly discussed. Here, we introduce theoretical models that quantify the effects of partial coherence on the resolution and the speckle contrast. The theoretical models allow us to find an optimal light source that maximizes the speckle reduction while minimizing the decline of the other terms. We implement benchtop prototypes of partially coherent holographic displays using the optimal light source, and verify the theoretical models via simulation and experiment. We also present a criterion to evaluate the depth of field in partially coherent holographic displays. We conclude with a discussion about approximations and limitations inherent in the theoretical models.

Aberration-corrected full-color holographic augmented reality near-eye display using a Pancharatnam-Berry phase lens.

We present a full-color holographic augmented reality near-eye display using a Pancharatnam-Berry phase lens (PBP lens) and its aberration correction method. Monochromatic and chromatic aberrations of the PBP lens are corrected by utilizing complex wavefront modulation of the holographic display. A hologram calculation method incorporating the phase profile of the PBP lens is proposed to correct the monochromatic aberration. Moreover, the chromatic aberration is corrected by warping the image using the mapping function obtained from ray tracing. The proposed system is demonstrated with the benchtop prototype, and the experimental results show that the proposed system offers 50° field of view full-color holographic images without optical aberrations.

Speckle reduced holographic displays using tomographic synthesis.

Despite significant merit of depth representation, holographic displays have a considerable limitation: speckle. Here, we present speckle reduced holographic displays using an engineered light source with angle diversity for speckle reduction. The level of angle diversity is optimized with consideration of resolution, speckle contrast, and depth of field. To extend the depth of field sacrificed for speckle reduction, we apply tomographic synthesis, exploiting synchronization of a local illumination module and a tunable-focus lens. We implement a benchtop prototype to verify the proposed method, which reduces the speckle contrast averagely by 37.8% while preserving resolution and 4.0 diopter depth of field.

Speckle reduced holographic displays using tomographic synthesis: publisher's note.

This publisher's note contains corrections to Opt. Lett.45, 4686 (2020)OPLEDP0146-959210.1364/OL.399623.

Augmented reality near-eye display using Pancharatnam-Berry phase lenses.

An augmented reality (AR) near-eye display using Pancharatnam-Berry (PB) phase lenses is proposed. PB phase lenses provide different optical effects depending on the polarization state of the incident light. By exploiting this characteristic, it is possible to manufacture an AR combiner with a small form factor and a large numerical aperture value. The AR combiner adopted in the proposed system operates as a convex lens for right-handed circularly polarized light and operates as transparent glass for left-handed circularly polarized light. By merging this combiner with a transparent screen, such as diffuser-holographic optical elements (DHOEs), it is possible to make an AR near-eye display with a small form factor and a wide field of view. In addition, the proposed AR system compensates the chromatic aberration that occurs in PB phase lens by adopting three-layered DHOEs. The operating principle of the proposed system is covered, and its feasibility is verified with experiments and analysis.

Metastatic endophthalmitis and thyroid abscess complicating Klebsiella pneumoniae liver abscess.

The thyroid is resistant to infection due to its anatomical and physiological characteristics. We present a rare case of invasive liver abscess with metastatic thyroid abscess and endogenous endophthalmitis in a previously healthy 55-year-old female patient without diabetes or other medical illness. This report raises an important question of the virulence of Klebsiella pneumoniae as an increasingly common causative agent of liver abscess.

[A Case of Isolated Leptomeningeal Carcinomatosis from Advanced Gastric Cancer].

Leptomeningeal carcinomatosis (LMC) is rare metastatic form of gastric cancer. Most cases are diagnosed in the final stage after multiple distant metastasis. An 84-year-old woman was admitted with melena, headache and vomiting. Esophagogastroduodenoscopy showed an ulceroinfiltrating lesion at the stomach (Borrmann class III), and biopsy revealed a signet ring cell carcinoma. The abdominal-pelvic CT showed no evidence of metastasis. A sudden decrease of consciousness was noted, but the brain CT showed no active lesion while the brain MRI revealed enhancement of leptomeninges. A lumbar puncture was performed and the cerebrospinal fluid study revealed malignant neoplastic cells. With family consent, no further evaluation and treatment were administered and she died six weeks after the diagnosis of gastric cancer. We report an extremely rare case of a patient who initially presented with neurologic symptoms, and was diagnosed LMC from advanced gastric cancer without any evidence of metastasis in abdomen and pelvis.

Clinical features of Bednar's aphthae in infants.

PURPOSE: Although Bednar's aphthae are common and regress spontaneously, these lesions may lead to feeding intolerance and are often misdiagnosed, rendering examinations useless. This study sheds new light on the clinical features of Bednar's aphthae. METHODS: Sixteen neonates and infants were newly diagnosed with Bednar's aphthae via routine health check-ups in an outpatient clinic. Medical records were retrospectively reviewed, and the following parameters were analyzed; sex, gestational age, birth weight, mode of delivery, and perinatal problems. A physical examination was carried out during the next outpatient visit to examine the healing process and check for the existence of scars or complications. RESULTS: Initial presentation included changes in feeding habits (n=10), longer feeding time, reduced intake, and increased irritability. In 6 patients, Bednar's aphthae were discovered incidentally, without prior symptoms. Feeding posture and method of feeding are important causes of Bednar's aphthae. Eleven patients were fed in a horizontal position, whereas 5 patients were fed in a semiseated position. Fifteen patients were bottle-fed, whereas 1 patient was exclusively breastfed. After correcting the feeding position, the ulcerative lesions disappeared within 1 month of diagnosis. During the follow-up period, lesions did not recur in any of the patients. CONCLUSION: This study suggests that Bednar's aphthae are caused by mechanical pressure. A diagnosis of Bednar's aphthae should be considered when lesions are found on the palate of infants and when symptoms seem to be feeding related. Proper education of parents can both treat Bednar's aphthae and easily prevent its recurrence.

Adsorption characteristics of diclofenac and sulfamethoxazole to graphene oxide in aqueous solution.

The adsorptive properties of graphene oxide (GO) were characterized, and the binding energies of diclofenac (DCF) and sulfamethoxazole (SMX) on GO adsorption were predicted using molecular modeling. The adsorption behaviors of DCF and SMX were investigated in terms of GO dosage, contact time, and pH. Additionally, the effects of sonication on GO adsorption were examined. GO adsorption involves "oxygen-containing functional groups" (OCFGs) such as COOH, which exhibit negative charges over a wide range of pH values (pH 3-11). DCF (-18.8 kcal mol(-1)) had a more favorable binding energy on the GO surface than SMX (-15.9 kcal mol(-1)). Both DCF and SMX were removed from solution (adsorbed to GO), up to 35% and 12%, respectively, within 6h, and an increase in GO dosage enhanced the removal of DCF. Electrostatic repulsion occurred between dissociated DCF/SMX and the more negatively charged GO at basic pH (>pKa). The sonication of GO significantly improved the removal of DCF (75%) and SMX (30%) due to dispersion of exfoliated GO particles and the reduction of OCFGs on the GO surface. Both DCF and SMX in the adsorption isotherm were explained well by the Freundlich model. The results of this study can be used to maximize the adsorption capacities of micropollutants using GO in water treatment processes.

Degradation characteristics of metoprolol during UV/chlorination reaction and a factorial design optimization.

Metoprolol (MTP), a hypertension depressor, has been increasingly detected even after conventional water treatment processes. In this study, the removal of MTP was compared using chlorination (Cl2), UV-C photolysis, and UV/chlorination (Cl2/UV) reactions. The results showed that the UV/chlorination reaction was most effective for MTP removal. MTP removal during UV/chlorination reaction was optimized under various conditions of UV intensity (1.1-4.4 mW/cm(2)), chlorine dose (1-5 mg/L as Cl2), pH (2-9), and dissolved organic matter (DOM, 1-4 mgC/L) using a two-level factorial design with 16 experimental combinations of the four factors. Among the factors examined, DOM scavenging by OH radicals was the most dominant in terms of MTP removal during UV/chlorination reaction. The established model fit well with the experimental results using to various water samples including surface waters, filtered and tap water samples. The optimized conditions (UV intensity=4.4 mW/cm(2), [Cl2]=5 mg/L, pH 7, and [DOM]=0.8-1.1 mgC/L) of the model removed more than 78.9% of MTP for filtered water samples during UV/chlorination reaction. Using LC-MS/MS, five byproducts of MTP (molecular weight: 171, 211, 309, 313, and 341, respectively) were identified during UV/chlorination reaction. Based on this information, the MTP transformation mechanism during UV/chlorination was suggested. Our results imply that applying UV/chlorination process after filtration stage in the water treatment plant (WTP) would be the most appropriate for effective removal of MTP.

Adsorption characteristics of selected hydrophilic and hydrophobic micropollutants in water using activated carbon.

In this study, we investigated adsorption characteristics of nine selected micropollutants (six pharmaceuticals, two pesticides, and one endocrine disruptor) in water using an activated carbon. The effects of carbon dosage, contact time, pH, DOM (dissolved organic matter), and temperature on the adsorption removal of micropollutants were examined. Increasing carbon dosage and contact time enhanced the removal of micropollutants. Sorption coefficients of hydrophilic compounds (caffeine, acetaminophen, sulfamethoxazole, and sulfamethazine) fit a linear isotherm and hydrophobic compounds (naproxen, diclofenac, 2, 4-D, triclocarban, and atrazine) fit a Freundlich isotherm. The removal of hydrophobic pollutants and caffeine were independent of pH changes, but acetaminophen, sulfamethazine, and sulfamethoxazole were adsorbed by mainly electrostatic interaction with activated carbon and so were affected by pH. The decrease in adsorption removal in surface water samples was observed and this decrease was more significant for hydrophobic than hydrophilic compounds. The decline in the adsorption capacity in surface water samples is caused by the competitive inhibition of DOM with micropollutants onto activated carbon. Low temperature (5°C) also decreased the adsorption removal of micropollutants, and affected hydrophobic compounds more than hydrophilic compounds. The results obtained in this study can be applied to optimize the adsorption capacities of micropollutants using activated carbon in water treatment process.