Full-colour 3D holographic augmented-reality displays with metasurface waveguides.

Emerging spatial computing systems seamlessly superimpose digital information on the physical environment observed by a user, enabling transformative experiences across various domains, such as entertainment, education, communication and training1-3. However, the widespread adoption of augmented-reality (AR) displays has been limited due to the bulky projection optics of their light engines and their inability to accurately portray three-dimensional (3D) depth cues for virtual content, among other factors4,5. Here we introduce a holographic AR system that overcomes these challenges using a unique combination of inverse-designed full-colour metasurface gratings, a compact dispersion-compensating waveguide geometry and artificial-intelligence-driven holography algorithms. These elements are co-designed to eliminate the need for bulky collimation optics between the spatial light modulator and the waveguide and to present vibrant, full-colour, 3D AR content in a compact device form factor. To deliver unprecedented visual quality with our prototype, we develop an innovative image formation model that combines a physically accurate waveguide model with learned components that are automatically calibrated using camera feedback. Our unique co-design of a nanophotonic metasurface waveguide and artificial-intelligence-driven holographic algorithms represents a significant advancement in creating visually compelling 3D AR experiences in a compact wearable device.

Neural basis of opioid-induced respiratory depression and its rescue.

Opioid-induced respiratory depression (OIRD) causes death following an opioid overdose, yet the neurobiological mechanisms of this process are not well understood. Here, we show that neurons within the lateral parabrachial nucleus that express the µ-opioid receptor (PBL Oprm1 neurons) are involved in OIRD pathogenesis. PBL Oprm1 neuronal activity is tightly correlated with respiratory rate, and this correlation is abolished following morphine injection. Chemogenetic inactivation of PBL Oprm1 neurons mimics OIRD in mice, whereas their chemogenetic activation following morphine injection rescues respiratory rhythms to baseline levels. We identified several excitatory G protein-coupled receptors expressed by PBL Oprm1 neurons and show that agonists for these receptors restore breathing rates in mice experiencing OIRD. Thus, PBL Oprm1 neurons are critical for OIRD pathogenesis, providing a promising therapeutic target for treating OIRD in patients.

Amoebicidal effect of chlorine dioxide gas against pathogenic Naegleria fowleri and Acanthamoeba polyphaga.

The pathogenic free-living amoebae, Naegleria fowleri and Acanthamoeba polyphaga, are found in freshwater, soil, and unchlorinated or minimally chlorinated swimming pools. N. fowleri and A. polyphaga are becoming problematic as water leisure activities and drinking water are sources of infection. Chlorine dioxide (ClO2) gas is a potent disinfectant that is relatively harmless to humans at the concentration used for disinfection. In this study, we examined the amoebicidal effects of ClO2 gas on N. fowleri and A. polyphaga. These amoebae were exposed to ClO2 gas from a ready-to-use product (0.36 ppmv/h) for 12, 24, 36, and 48 h. Microscopic examination showed that the viability of N. fowleri and A. polyphaga was effectively inhibited by treatment with ClO2 gas in a time-dependent manner. The growth of N. fowleri and A. polyphaga exposed to ClO2 gas for 36 h was completely inhibited. In both cases, the mRNA levels of their respective actin genes were significantly reduced following treatment with ClO2 gas. ClO2 gas has an amoebicidal effect on N. fowleri and A. polyphaga. Therefore, ClO2 gas has been proposed as an effective agent for the prevention and control of pathogenic free-living amoeba contamination.

Current Status of Latent Tuberculosis Infection Treatment Among Pediatric Patients in Korea: Prescription and Treatment Completion.

BACKGROUND: The treatment of pediatric patients with latent tuberculosis infection (LTBI) is a crucial TB control strategy. LTBI is not a reportable communicable disease, and data regarding LTBI treatment in pediatric patients in Korea are scarce. This study aimed to investigate the prescription patterns and treatment completion rates among pediatric patients with LTBI in Korea by analyzing National Health reimbursement claims data. METHODS: We retrospectively analyzed outpatient prescription records for pediatric patients aged 18 or younger with LTBI-related diagnostic codes from 2016 to 2020. We compared the frequency of prescriptions for the standard treatment regimen (9 months of isoniazid [9H]) and an alternative treatment regimen (3 months of isoniazid plus rifampicin [3HR]). We also assessed the treatment incompletion rates by age group, treatment regimen, treatment duration, the level of medical facility, physician's specialty, and hospital location. We performed multivariable analysis to identify factors influencing treatment incompletion. RESULTS: Among the 11,362 patients who received LTBI treatment, 6,463 (56.9%) were prescribed the 9H regimen, while 4,899 (43.1%) received the 3HR regimen. Patients in the 3HR group were generally older than those in the 9H group. The proportion of 3HR regimen prescriptions significantly greater in the later period (2018-2020), in primary hospitals, under the management of non-pediatric specialists, and in metropolitan regions. The overall treatment incompletion rate was 39.7% (9H group: 46.9%, 3HR group: 30.3%). In the multivariable analysis, 9H regimen prescription was the strongest factor associated with treatment incompletion (adjusted odds ratio, 2.42; 95% confidence interval, 2.20-2.66; P < 0.001). Additionally, management in a primary hospital, a hospital's location in a non-metropolitan region, and management by a non-pediatric specialist were also significant risk factors for treatment incompletion. CONCLUSION: Our study results suggest that promoting the use of 3HR regimen prescriptions could be an effective strategy to enhance treatment completion. Physicians in primary hospitals, hospitals located in non-metropolitan regions, and physicians without a pediatric specialty require increased attention when administering LTBI treatment to pediatric patients to ensure treatment completion.

Antibiotics for Pediatric Patients With Laryngotracheobronchitis in Korea: A Nationwide Study Based on Administrative Data.

BACKGROUND: Antimicrobial resistance (AMR) is an important global public health concern in adults and children. Laryngotracheobronchitis (croup) is a common acute respiratory infection (ARI) among children, most often caused by a virus, and should not be treated with antibiotics. Reducing the usage of unnecessary antibiotics in ARI using an antimicrobial stewardship program (ASP) is an effective measure against AMR in children. This study investigates the antibiotic prescription pattern in pediatric patients with laryngotracheobronchitis in Korea. Our results will be useful to improve the ASP. METHODS: The data were obtained from the government agency Health Insurance Review and Assessment Service. We analyzed outpatient prescriptions issued to children ≤ 5 years of age with a first-listed diagnosis code for laryngotracheobronchitis, i.e., International Classification of Disease, 10th Revision, code J050 (croup), J040 (laryngitis), or J041 (tracheitis), during 2017-2020. For each prescription, demographic information and information about medical facilities visited (type of hospital, specialty of physician, location of hospital) were extracted. The overall antibiotic prescription rate was subsequently estimated, and multivariable analysis was conducted to determine the associated factors of antibiotic prescription. Prescribed antibiotics were described and classified into extended-spectrum penicillins, cephalosporin, and macrolides. RESULTS: Of 2,358,194 prescriptions reviewed, 829,172 (35.2%) contained antibiotics. In the multivariable analysis, management in a hospital was the strongest factor associated with antibiotic prescription (adjusted odds ratio [aOR], 22.33; 95% confidence interval [CI], 20.87-23.89; P < 0.001), followed by management in a clinic (aOR, 12.66; 95% CI, 11.83-13.54; P < 0.001) and management in a general hospital (aOR, 8.96; 95% CI, 8.37-9.59; P < 0.001). Antibiotic prescription was also significantly associated with patients who were ≤ 2 years of age, managed by a pediatric specialist, and treated at a hospital located in a non-metropolitan region. Overall, extended-spectrum penicillins were the most frequently prescribed (18.6%) antibiotics, followed by cephalosporins (9.4%) and macrolides (8.5%). CONCLUSION: The results of our study suggest that ASPs need to focus on physicians in hospitals, clinics, general hospitals, and pediatric specialties. Providing education programs to these groups to increase awareness of AMR and appropriate antibiotics use could be effective ASP policy and may help to reduce unnecessary prescriptions of antibiotics for laryngotracheobronchitis among pediatric patients and therefore potentially AMR in children in Korea.

Comedones and epidermal cysts on the abdominal skin of a dog occurring after a laparotomy.

An 8-year-old neutered male shih tzu dog underwent laparotomy for cystolithectomy. Ten days later, multiple various-sized cystic nodules were observed on the suture line and surrounding abdominal skin, although the surgical incision had healed well. Microscopically, various-sized cysts lined with thin walls of stratified squamous epithelium in the dermis were dilated and filled with keratin. Adnexal differentiation from the wall was not seen. Thus, the abdominal lesions were diagnosed as comedones and epidermal cysts. Herein, we describe the case of a dog with comedones and epidermal cysts on the abdominal skin after a laparotomy. Key clinical message: Multiple various-sized cystic lesions of the follicles are described. The implantation of epidermal fragments into the dermis by surgery may induce epidermal cysts and comedones in the skin of hyperadrenocorticism-affected dogs.

Comédons et kystes épidermiques sur la peau abdominale d'un chien survenant après une laparotomie. Un chien shih tzu mâle castré de 8 ans a subi une laparotomie pour cystolithectomie. Dix jours plus tard, de multiples nodules kystiques de différentes tailles ont été observés sur la ligne de suture et sur la peau abdominale environnante, bien que l'incision chirurgicale ait bien cicatrisé. Au microscope, des kystes de différentes tailles bordés de fines parois d'épithélium pavimenteux stratifié dans le derme étaient dilatés et remplis de kératine. Aucune différenciation annexielle par rapport à la paroi n'a été observée. Ainsi, les lésions abdominales ont été diagnostiquées comme des comédons et des kystes épidermiques. Nous décrivons ici le cas d'un chien présentant des comédons et des kystes épidermiques sur la peau abdominale après une laparotomie.Message clinique clé:De multiples lésions kystiques des follicules, de différentes tailles, sont décrites. L'implantation chirurgicale de fragments d'épiderme dans le derme peut provoquer des kystes épidermiques et des comédons dans la peau des chiens atteints d'hypercorticisme.(Traduit par Dr Serge Messier).

Alignment properties of a ferroelectric nematic liquid crystal on the rubbed substrates.

The orientation characteristics of FNLC-919, a new material with a ferroelectric nematic phase at room temperature, were investigated. Its alignment characteristics varied greatly depending on the relative rubbing direction on both substrates of a liquid crystal cell. In a cell where the two substrates were rubbed in the same direction, they were arranged homogeneously along the rubbing direction without domains or defects in the ferroelectric nematic phase. In a cell where the two substrates were rubbed in the anti-parallel direction, the two domains were twisted in the opposite direction. We quantitatively obtained the twisted direction and angle by matching the experimental data and calculation results using Jones matrix calculations. From the electro-optical experiment, it was confirmed that the polarization direction was opposite to the rubbing direction. In addition, the wavelength and temperature dependence of birefringence was measured for FNLC-919. In a cell where the rubbing direction between two substrates was 90°, two domains of opposite directions were observed in the nematic phase. When it becomes a ferroelectric nematic phase on cooling, the twist is determined to be only in one direction. The twist direction and angle were quantitatively obtained in the nematic and ferroelectric nematic phases. It was twisted more in the ferroelectric nematic phase than in the nematic phase.

Electro-optical synaptic characteristics of ferroelectric liquid crystals for artificial intelligence.

We propose electro-optical synaptic devices using surface-stabilized ferroelectric liquid crystals. Typical synaptic characteristics were observed for varying pulse time intervals, numbers of pulses, and signal voltages. Plasticity only occurred when pulses were applied at intervals shorter than the response time of the ferroelectric liquid crystal. Moreover, the plasticity increased with a higher pulse voltage and number of pulses. This demonstrates the importance of repeated learning. The synaptic weights required to make connections through learning in an artificial neural network can be determined by tuning the pulse signal. We discuss the high-speed computational potential of optical neuromorphic devices using liquid crystals.

Twenty-Five Year Trend Change in the Etiology of Pediatric Invasive Bacterial Infections in Korea, 1996-2020.

BACKGROUND: The coronavirus disease-2019 (COVID-19) pandemic has contributed to the change in the epidemiology of many infectious diseases. This study aimed to establish the pre-pandemic epidemiology of pediatric invasive bacterial infection (IBI). METHODS: A retrospective multicenter-based surveillance for pediatric IBIs has been maintained from 1996 to 2020 in Korea. IBIs caused by eight bacteria (Streptococcus pneumoniae, Haemophilus influenzae, Neisseria meningitidis, Staphylococcus aureus, Streptococcus agalactiae, Streptococcus pyogenes, Listeria monocytogenes, and Salmonella species) in immunocompetent children > 3 months of age were collected at 29 centers. The annual trend in the proportion of IBIs by each pathogen was analyzed. RESULTS: A total of 2,195 episodes were identified during the 25-year period between 1996 and 2020. S. pneumoniae (42.4%), S. aureus (22.1%), and Salmonella species (21.0%) were common in children 3 to 59 months of age. In children ≥ 5 years of age, S. aureus (58.1%), followed by Salmonella species (14.8%) and S. pneumoniae (12.2%) were common. Excluding the year 2020, there was a trend toward a decrease in the relative proportions of S. pneumoniae (rs = -0.430, P = 0.036), H. influenzae (rs = -0.922, P < 0.001), while trend toward an increase in the relative proportion of S. aureus (rs = 0.850, P < 0.001), S. agalactiae (rs = 0.615, P = 0.001), and S. pyogenes (rs = 0.554, P = 0.005). CONCLUSION: In the proportion of IBIs over a 24-year period between 1996 and 2019, we observed a decreasing trend for S. pneumoniae and H. influenzae and an increasing trend for S. aureus, S. agalactiae, and S. pyogenes in children > 3 months of age. These findings can be used as the baseline data to navigate the trend in the epidemiology of pediatric IBI in the post COVID-19 era.

Novel evaluation of upper-limb motor performance after stroke based on normal reaching movement model.

BACKGROUND: Upper-limb rehabilitation robots provide repetitive reaching movement training to post-stroke patients. Beyond a pre-determined set of movements, a robot-aided training protocol requires optimization to account for the individuals' unique motor characteristics. Therefore, an objective evaluation method should consider the pre-stroke motor performance of the affected arm to compare one's performance relative to normalcy. However, no study has attempted to evaluate performance based on an individual's normal performance. Herein, we present a novel method for evaluating upper limb motor performance after a stroke based on a normal reaching movement model. METHODS: To represent the normal reaching performance of individuals, we opted for three candidate models: (1) Fitts' law for the speed-accuracy relationship, (2) the Almanji model for the mouse-pointing task of cerebral palsy, and (3) our proposed model. We first obtained the kinematic data of healthy (n = 12) and post-stroke (n = 7) subjects with a robot to validate the model and evaluation method and conducted a pilot study with a group of post-stroke patients (n = 12) in a clinical setting. Using the models obtained from the reaching performance of the less-affected arm, we predicted the patients' normal reaching performance to set the standard for evaluating the affected arm. RESULTS: We verified that the proposed normal reaching model identifies the reaching of all healthy (n = 12) and less-affected arm (n = 19; 16 of them showed an R2 > 0.7) but did not identify erroneous reaching of the affected arm. Furthermore, our evaluation method intuitively and visually demonstrated the unique motor characteristics of the affected arms. CONCLUSIONS: The proposed method can be used to evaluate an individual's reaching characteristics based on an individuals normal reaching model. It has the potential to provide individualized training by prioritizing a set of reaching movements.

Clinical Importance of the Lateral Tarsal Strip Procedure by a Single Experienced Oculoplastic Surgeon: 8 Years of Experience in a Tertiary Medical Center (Cross-Sectional Study).

Lateral tarsal strip (LTS) is a simple surgical technique that can correct eyelid malposition. Clinical indications vary from involutional entropion and ectropion, lower eyelid laxity, and lower eyelid retraction to punctal and paralytic ectropion. Lateral tarsal strip mainly treats eyelid malposition by correcting horizontal laxity. Herein, the authors report the clinical indications for and effects of LTS. The authors retrospectively reviewed medical records of patients who underwent LTS by a single oculoplastic surgeon with 8 years of experience performing the procedure at Korea University Guro Hospital. The authors included 247 patients with 325 treated eyelids. Involutional entropion was the most common indication, accounting for 69 patients (27.94%) and 88 eyelids (27.08%). The second most common indication was lower eyelid laxity [n=44 patients (17.81%) and 68 eyelids (20.92%)]. Simultaneous surgery in addition to LTS was performed in 167 patients (67.6%) and 219 eyelids (67.4%); the most common was endoscopic dacryocystorhinostomy (DCR), which was performed in 50 patients (29.94%) and 80 eyelids (36.53%). Lateral tarsal strip can be performed alone or simultaneously with oculoplastic procedures for various indications. Overcorrection with fixation above the canthal angle is useful to reduce recurrence. This study aims to explain the clinical importance of the LTS procedure.

Chromatographic Method for Monitoring of Pesticide Residues and Risk Assessment for Herbal Decoctions Used in Traditional Korean Medicine Clinics.

The presence of pesticide residues in herbs and the herbal products derived from them raises serious health concerns. This study was conducted to investigate the residual pesticide concentrations and assess potential human health risks from herbal medicines used in traditional Korean medicine clinics. A total of 40 samples of herbal decoctions were collected from 10 external herbal dispensaries. The pesticide residues were analyzed by the multiresidue method for 320 different pesticides using liquid chromatography tandem mass spectrometry (LC-MS/MS) and gas chromatography tandem mass spectrometry (GC-MS/MS). As a result of the monitoring, carbendazim was detected at 0.01 and 0.03 µg/g in eight samples and no pesticide was detected in the other herbal decoctions. Carbendazim was set for each individual item as less than 0.05 µg/g in Paeoniae radix, less than 0.05 µg/g in Cassiae semen, less than 2.0 µg/g in Lycii fructus, and less than 10 µg/g in Schisandrae fructus (dried). Therefore, the results of this study suggested that the detected pesticide residues in herbal decoctions could not be considered as posing a serious health risk.

CLINICAL IMPLICATION OF RETINAL NERVE FIBER LAYER SCHISIS AND MACULAR FLUORESCEIN LEAKAGE IN PRIMARY IDIOPATHIC EPIRETINAL MEMBRANE.

PURPOSE: We evaluated the relationship between macular fluorescein leakage and retinal nerve fiber layer (RNFL) schisis and investigated the visual prognostic values after pars plana vitrectomy (PPV) and idiopathic epiretinal membrane removal. METHODS: We analyzed the correlations between preoperative optical coherence tomography (OCT) parameters and macular leakage. The final best-corrected visual acuity and central macular thickness were compared according to the presence or absence of macular leakage and RNFL schisis. RESULTS: In 80 eyes with idiopathic epiretinal membrane treated with PPV and membrane peeling, preoperative macular leakage was associated with the presence of preoperative RNFL schisis and inner nuclear layer microcysts. Eyes with both macular leakage and RNFL schisis showed worse postoperative best-corrected visual acuity than those without both factors. CONCLUSION: In the presence of macular fluorescein leakage and RNFL schisis, postoperative best-corrected visual acuity is worse, and improvements in the central macular thickness are greater than those in the absence of both factors.

Orbital subperiosteal hematoma associated with frontal and ethmoidal sinusitis.

BACKGROUND: We report a rare case of orbital subperiosteal hematoma associated with frontal and ethmoidal sinusitis. Common concerns involving the orbital subperiosteal space include abscess, hematoma and tumor. CASE PRESENTATION: A patient presented to our clinic with periorbital swelling and limited extraocular muscle movement in her left eye. Computed tomography revealed a superior subperiosteal mass with frontal and ethmoidal sinusitis. We diagnosed the patient with subperiosteal hematoma and surgical evacuation was performed via superior orbitotomy. Brown serous discharge was drained and biopsy demonstrated fibrin clots. The final diagnosis was orbital subperiosteal hematoma and the patient was discharged with symptoms resolved. CONCLUSION: Orbital subperiosteal hematoma is difficult to distinguish from abscess owing to its rarity and similar presentation. Computed tomography is helpful in diagnosis, and surgical evacuation during the early stages is essential to achieving a good outcome.

The Seroprevalence of SARS-CoV-2 in Children During Early COVID-19 Pandemic in Korea: A Nationwide, Population-Based Study.

BACKGROUND: Coronavirus disease 2019 (COVID-19) is often asymptomatic and associated with mild clinical symptoms in children. Social distancing measures have led to a relatively small number of confirmed COVID-19 cases in Korea than in other countries in the earlier pandemic phase. Previous seroprevalence studies in Korean adults before the introduction of COVID-19 vaccination campaign have shown a low antibody positivity rate. However, data on COVID-19 seroprevalence in Korean children remained scarce. In this study, we assessed the seroprevalence of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection in children in Korea. METHODS: Between December 2020 and March 2021, stratified serum samples were collected from children aged 0-18 years in 17 different regions across the country. The SARS-CoV-2 antibody test was conducted using an electro-chemiluminescence immunoassay (ECLIA) to detect the antibodies against nucleocapsid antigens of SARS-CoV-2. Samples that tested positive using the ECLIA were reflexed to an additional plaque reduction neutralization test (PRNT) for SARS-CoV-2. RESULTS: A total of 1,887 samples were collected. Excluding 21 samples collected from regional medical centers, 1,866 samples were included in the final analysis. Two samples (0.11%) were positive for the antibodies against nucleocapsid antigens of SARS-CoV-2. Both samples were shown to have neutralizing antibodies for SARS-CoV-2 via PRNT. CONCLUSION: After 1 year since the start of COVID-19 pandemic, the seroprevalence of SARS-CoV-2 among Korean children was 0.11%, which was lower than the adults (0.52%) in another study conducted during a similar period. In the early stages of the COVID-19 pandemic, the seroprevalence of SARS-CoV-2 in Korea was lower than those of other countries, which was presumed to be the consequence of a very strong social distancing measures.

Orbital Metastasis From Gastric Cancer Presenting as Orbital Cellulitis With Ptosis.

ABSTRACT: We report a rare case of orbital metastasis that originated from gastric carcinoma, which presented as orbital cellulitis with ptosis. Orbital metastasis accounts for about only 1% to 13% of orbital tumors. Orbital metastasis in orbital soft tissue or bony structures is very uncommon.A female patient with advanced gastric cancer with multiple metastases was referred to our clinic. She showed mild swelling and ptosis in her left eye. Contrast enhanced computed tomography imaging suggested orbital metastasis from gastric cancer in the superolateral aspect of the orbit. Based on her general condition and after consulting with an oncologist, we determined that fine needle biopsy and excisional biopsy for pathological diagnosis should not be performed as a therapeutic treatment.It is important to distinguish orbital metastasis from orbital cellulitis with ptosis especially for patients with family or personal history of cancer. Clinicians should collect a through medical history from patients and suggest contrast enhanced computed tomography for appropriate diagnosis. Assessing quality of life and aggressive treatment options is crucial for determining the best treatment for orbital metastasis.

Diffuse Large B-Cell Lymphoma Arising in the Lacrimal Sac.

ABSTRACT: The authors report a single case of diffuse large B-cell lymphoma arising in the lacrimal sac. Diffuse large B-cell lymphoma is a third most common primary ocular adnexal lymphoma, which is the most common primary ocular malignant disease in adults. A patient came to our clinic with epiphora and a growing mass in the lacrimal sac. Enhanced computed tomography imaging suggested the presence of a malignant tumor and surgical excision and biopsy were performed. A final diagnosis of diffuse large B-cell lymphoma was reached by immunohistological and immunochemical staining. Two months after surgery, diffuse large B-cell lymphoma relapse occurred in the lacrimal sac and the patient underwent 6 cycles of chemotherapy. Diffuse large B-cell lymphoma is a curable disease when diagnosed early, and aggressive biopsy during surgery of the lacrimal sac is necessary to diagnose diffuse large B-cell lymphoma in the early stage. It is important to distinguish diffuse large B-cell lymphoma from other lacrimal system diseases.

Crosstalk Correction for Color Filter Array Image Sensors Based on Lp-Regularized Multi-Channel Deconvolution.

In this paper, we propose a crosstalk correction method for color filter array (CFA) image sensors based on Lp-regularized multi-channel deconvolution. Most imaging systems with CFA exhibit a crosstalk phenomenon caused by the physical limitations of the image sensor. In general, this phenomenon produces both color degradation and spatial degradation, which are respectively called desaturation and blurring. To improve the color fidelity and the spatial resolution in crosstalk correction, the feasible solution of the ill-posed problem is regularized by image priors. First, the crosstalk problem with complex spatial and spectral degradation is formulated as a multi-channel degradation model. An objective function with a hyper-Laplacian prior is then designed for crosstalk correction. This approach enables the simultaneous improvement of the color fidelity and the sharpness restoration of the details without noise amplification. Furthermore, an efficient solver minimizes the objective function for crosstalk correction consisting of Lp regularization terms. The proposed method was verified on synthetic datasets according to various crosstalk and noise levels. Experimental results demonstrated that the proposed method outperforms the conventional methods in terms of the color peak signal-to-noise ratio and structural similarity index measure.

Color Demosaicing of RGBW Color Filter Array Based on Laplacian Pyramid.

In recent years, red, green, blue, and white (RGBW) color filter arrays (CFAs) have been developed to solve the problem of low-light conditions. In this paper, we propose a new color demosaicing algorithm for RGBW CFAs using a Laplacian pyramid. Because the white channel has a high correlation to the red, green, and blue channels, the white channel is interpolated first using each color difference channel. After we estimate the white channel, the red, green, and blue channels are interpolated using the Laplacian pyramid decomposition of the estimated white channel. Our proposed method using Laplacian pyramid restoration works with Canon-RGBW CFAs and any other periodic CFAs. The experimental results demonstrated that the proposed method shows superior performance compared with other conventional methods in terms of the color peak signal-to-noise ratio, structural similarity index measure, and average execution time.

Fiber-Optic Temperature Sensor Using Cholesteric Liquid Crystals on the Optical Fiber Ferrules.

Cholesteric liquid crystals (CLCs) can be applied to various physical and chemical sensors because their alignment structures are changed by external stimuli. Here, we propose a CLC device fabricated by vertically forming the helical axis of the CLC between the cross-sections of two optical fiber ferrules. An optical fiber temperature sensor was successfully implemented using the proposed optical fiber ferrule-based CLC device. A wideband wavelength-swept laser with a center wavelength of 1073 nm and scanning range of 220 nm was used as a light source to measure the variations in the reflection spectrum band according to the temperature change in the CLC cell. The wavelength variation of the reflection spectrum band according to the temperature applied to the CLC cell was reversible and changed linearly with a change in the temperature, and the long-wavelength edge variation rate according to the temperature change was -5.0 nm/°C. Additionally, as the temperature applied to the CLC cell increased, the reflection spectrum bandwidth gradually decreased; the reflection spectrum bandwidth varied at a rate of -1.89 nm/°C. The variations in the refractive indices with temperature were calculated from the band wavelengths of the reflection spectrum. The pitch at each temperature was calculated based on the refractive indices and it gradually decreased as the temperature increased.