Integrated frequency-modulated optical parametric oscillator.

Optical frequency combs have revolutionized precision measurement, time-keeping and molecular spectroscopy1-7. A substantial effort has developed around 'microcombs': integrating comb-generating technologies into compact photonic platforms5,7-9. Current approaches for generating these microcombs involve either the electro-optic10 or Kerr mechanisms11. Despite rapid progress, maintaining high efficiency and wide bandwidth remains challenging. Here we introduce a previously unknown class of microcomb-an integrated device that combines electro-optics and parametric amplification to yield a frequency-modulated optical parametric oscillator (FM-OPO). In contrast to the other solutions, it does not form pulses but maintains operational simplicity and highly efficient pump power use with an output resembling a frequency-modulated laser12. We outline the working principles of our device and demonstrate it by fabricating the complete optical system in thin-film lithium niobate. We measure pump-to-comb internal conversion efficiency exceeding 93% (34% out-coupled) over a nearly flat-top spectral distribution spanning about 200 modes (over 1 THz). Compared with an electro-optic comb, the cavity dispersion rather than loss determines the FM-OPO bandwidth, enabling broadband combs with a smaller radio-frequency modulation power. The FM-OPO microcomb offers robust operational dynamics, high efficiency and broad bandwidth, promising compact precision tools for metrology, spectroscopy, telecommunications, sensing and computing.

Single-mode squeezed-light generation and tomography with an integrated optical parametric oscillator.

Quantum optical technologies promise advances in sensing, computing, and communication. A key resource is squeezed light, where quantum noise is redistributed between optical quadratures. We introduce a monolithic, chip-scale platform that exploits the χ(2) nonlinearity of a thin-film lithium niobate (TFLN) resonator device to efficiently generate squeezed states of light. Our system integrates all essential components-except for the laser and two detectors-on a single chip with an area of one square centimeter, reducing the size, operational complexity, and power consumption associated with conventional setups. Using the balanced homodyne measurement subsystem that we implemented on the same chip, we measure a squeezing of 0.55 decibels and an anti-squeezing of 1.55 decibels. We use 20 milliwatts of input power to generate the parametric oscillator pump field by using second harmonic generation on the same chip. Our work represents a step toward compact and efficient quantum optical systems posed to leverage the rapid advances in integrated nonlinear and quantum photonics.

The Factors Affecting Longitudinal Course of Posttraumatic Stress Disorder Symptoms in Sexual Assault Victims.

OBJECTIVE: This study aimed to identify the factors affecting posttraumatic stress disorder (PTSD) symptom remission prospectively through a 1-year follow-up of sexual assault (SA) victims. METHODS: A total 65 female SA victims who visited the crisis intervention center were included. Self-administered questionnaires regarding PTSD symptoms and PTSD related prognostic factors were conducted at both recruitment (T1) and 1 year after recruitment (T2). The multivariate analyses were used to determine the significant predictors of PTSD remission/non-remission state 1 year after SA. RESULTS: In logistic regression analysis, both anxiety and secondary victimization were identified as significant factors explaining the results on PTSD remission/non-remission state at T2 (Beck's Anxiety Inventory [BAI], p=0.003; Secondary Victimization Questionnaire, p=0.024). In a linear mixed analysis, both depression and anxiety were found to be significant variables leading to changes in Posttraumatic Diagnostic Scale for Diagnostic and Statistical Manual of Mental Disorders, Fifth Edition from T1 to T2 (BAI, p<0.001; Center for Epidemiological Studies Depression Scale, p<0.001). CONCLUSION: Depression, anxiety symptoms, and secondary victimization after SA were associated with PTSD symptom non-remission 1 year after SA.

Association of the Comprehensive Attention Test and the Korean Wechsler Intelligence Scale for Children-Fourth Edition in Children and Adolescents With Attention-Deficit/Hyperactivity Disorder.

Objectives: This study aimed to investigate the correlation between the Comprehensive Attention Test, Korean-Wechsler Intelligence Scale for Children-Fourth Edition, and Attention-Deficit/Hyperactivity Disorder (ADHD) Rating Scale-IV scores in children and adolescents with ADHD. Methods: Fifty-five children and adolescents diagnosed with ADHD and not taking psychiatric medications were included in this retrospective study. A correlation analysis was performed. Results: Although simple visual and auditory selective attention have diagnostic value in traditional continuous performance tests, this study revealed that inhibition-sustained attention and interference-selective attention are also effective in evaluating ADHD. Furthermore, the correlation between the attention and intelligence test scores varied depending on the use of visual or auditory stimuli. Conclusion: The findings of this study contribute to clarifying our understanding of the cognitive characteristics of children and adolescents with ADHD and can be used in future research.

Integrated quantum optical phase sensor in thin film lithium niobate.

The quantum noise of light, attributed to the random arrival time of photons from a coherent light source, fundamentally limits optical phase sensors. An engineered source of squeezed states suppresses this noise and allows phase detection sensitivity beyond the quantum noise limit (QNL). We need ways to use quantum light within deployable quantum sensors. Here we present a photonic integrated circuit in thin-film lithium niobate that meets these requirements. We use the second-order nonlinearity to produce a squeezed state at the same frequency as the pump light and realize circuit control and sensing with electro-optics. Using 26.2 milliwatts of optical power, we measure (2.7 ± 0.2)% squeezing and apply it to increase the signal-to-noise ratio of phase measurement. We anticipate that photonic systems like this, which operate with low power and integrate all of the needed functionality on a single die, will open new opportunities for quantum optical sensing.

Experimentally realized in situ backpropagation for deep learning in photonic neural networks.

Integrated photonic neural networks provide a promising platform for energy-efficient, high-throughput machine learning with extensive scientific and commercial applications. Photonic neural networks efficiently transform optically encoded inputs using Mach-Zehnder interferometer mesh networks interleaved with nonlinearities. We experimentally trained a three-layer, four-port silicon photonic neural network with programmable phase shifters and optical power monitoring to solve classification tasks using "in situ backpropagation," a photonic analog of the most popular method to train conventional neural networks. We measured backpropagated gradients for phase-shifter voltages by interfering forward- and backward-propagating light and simulated in situ backpropagation for 64-port photonic neural networks trained on MNIST image recognition given errors. All experiments performed comparably to digital simulations ([Formula: see text]94% test accuracy), and energy scaling analysis indicated a route to scalable machine learning.

High-efficiency second harmonic generation of blue light on thin-film lithium niobate.

The strength of interactions between photons in a χ(2) nonlinear optical waveguide increases at shorter wavelengths. These larger interactions enable coherent spectral translation and light generation at a lower power, over a broader bandwidth, and in a smaller device: all of which open the door to new technologies spanning fields from classical to quantum optics. Stronger interactions may also grant access to new regimes of quantum optics to be explored at the few-photon level. One promising platform that could enable these advances is thin-film lithium niobate (TFLN), due to its broad optical transparency window and possibility for quasi-phase matching and dispersion engineering. In this Letter, we demonstrate second harmonic generation of blue light on an integrated thin-film lithium niobate waveguide and observe a conversion efficiency of η0 = 33, 000%/W-cm2, significantly exceeding previous demonstrations.

Distributed associative memory network with memory refreshing loss.

Despite recent progress in memory augmented neural network (MANN) research, associative memory networks with a single external memory still show limited performance on complex relational reasoning tasks. Especially the content-based addressable memory networks often fail to encode input data into rich enough representation for relational reasoning and this limits the relation modeling performance of MANN for long temporal sequence data. To address these problems, here we introduce a novel Distributed Associative Memory architecture (DAM) with Memory Refreshing Loss (MRL) which enhances the relation reasoning performance of MANN. Inspired by how the human brain works, our framework encodes data with distributed representation across multiple memory blocks and repeatedly refreshes the contents for enhanced memorization similar to the rehearsal process of the brain. For this procedure, we replace a single external memory with a set of multiple smaller associative memory blocks and update these sub-memory blocks simultaneously and independently for the distributed representation of input data. Moreover, we propose MRL which assists a task's target objective while learning relational information existing in data. MRL enables MANN to reinforce an association between input data and task objective by reproducing stochastically sampled input data from stored memory contents. With this procedure, MANN further enriches the stored representations with relational information. In experiments, we apply our approaches to Differential Neural Computer (DNC), which is one of the representative content-based addressing memory models and achieves the state-of-the-art performance on both memorization and relational reasoning tasks.

A Review of Cognitive and Behavioral Interventions for Tic Disorder.

OBJECTIVES: Tic disorder is a neurodevelopmental disorder characterized by multiple involuntary movements of muscles or vocalization. Although tic symptoms subside as the patient ages, some patients suffer from significant functional impairments related to severe tic symptoms. This manuscript aimed to review the latest scientific evidences for the effect of cognitive-behavioral interventions on tic disorder. METHODS: The relevant studies were identified by searching medical research databases. We focused our search on studies published between 2000 and 2020 in order to reflect the latest scientific evidence. A total of 821 articles were identified in the initial database search and 27 articles were finally included for the review after the exclusion of duplicated and irrelevant articles. RESULTS: Behavioral therapies including habit reversal training, Comprehensive Behavioral Intervention for Tics, and exposure and response prevention were the most widely studied interventions for tic disorder and are recommended as first-line treatments for tic disorders with high confidence. Cognitive psychophysiologic approaches were also reported to be effective. CONCLUSION: Further studies are needed to support the future treatment of tics with low-cost and more widely available treatments, in order to ensure better treatment outcomes.

Cascaded optical resonator-based programmable photonic integrated circuits.

Programmable photonic integrated circuits have mainly been developed based on the single wavelength channel operation of fundamental building blocks consisting of Mach-Zehnder interferometers (MZIs) with tunable phase shifters. We propose and study optical circuit models consisting of cascaded optical resonators that enable the independent operation of multiple wavelength channels in a more compact footprint than the conventional MZIs. By adopting experimental values reported for silicon micro-ring resonators, the fidelities of different types of 2×2 unitary transformations and higher-dimensional unitary transformations are examined by employing the Reck algorithm and the Clements algorithm.

A Brief Depression and Anxiety Rating Scale for Sexual Violence Victims.

OBJECTIVE: This study aimed to develop a brief self-report measure of depressive and anxiety symptoms in victims of sexual violence. METHODS: The sample, which consisted of 215 victims and 255 healthy controls, was recruited between December 2016 and November 2018 from eight Sunflower Centers. Eligible items were selected from existing scales of depression (CES-DC and CES-D) and anxiety (SAI-C and BAI) symptoms by item-total correlation coefficients and item response theory (IRT) analysis. Internal consistency coefficients were computed and the receiver operating characteristics curve was inspected to assess the validity of the brief scale and determine optimal cutoff scores. RESULTS: The brief scales showed high internal consistency across all age groups. The optimal cutoff score of brief depression scale was 1.5 for children, 2.5 for adolescents, and 2.5 for the adults. That of brief anxiety scale was 8.5, 6.5, and 3.5, respectively. CONCLUSION: The results underscore the need for age-appropriate screening measures of depressive and anxiety symptoms in victims of sexual violence.

Hot-Rolling and a Subsequent Direct-Quenching Process Enable Superior High-Cycle Fatigue Resistance in Ultra-High Strength Low Alloy Steels.

The current study investigated the effect of hot rolling reduction rate of ultra-high strength low alloy steel manufactured via the direct quenching process on microstructure, tensile and high-cycle fatigue properties of the alloy. In order to control the reduction rate of ultra-high strength steels (UHSSs) differently, the steels were produced with two different thicknesses, 6 mm (46.2%-reduction rate, A) and 15 mm (11.5%-reduction rate, B). Then, the two alloys were directly quenched under the same conditions. Both the UHSSs showed martensite in the near surface region and auto-tempered martensite and bainite in the center region. Tensile results showed that alloy A with higher fraction of finer martensite had higher yield strength by about 180 MPa (1523 MPa) than alloy B. The alloy A was also found to possess a higher tensile strength (~2.1 GPa) than alloy B. In addition, alloy A had higher strength than B, and the elongation of A was about 4% higher than that of alloy B. High-cycle fatigue results showed that the fatigue limits of alloys A and B were 1125 MPa and 1025 MPa, respectively. This means that alloy A is excellent not only in strength but also high-cycle fatigue resistance. Based on the above results, the correlation between the microstructure and deformation behaviors were also discussed.

Universal inherent fluctuations in statistical counting of large particles in slurry used for semiconductor manufacturing.

In the chemical mechanical polishing process of semiconductor manufacturing, the concentration of 'large' particles ([Formula: see text]0.5 µm) in the slurry, which is considerably larger in size than the main abrasives ([Formula: see text] 0.1 µm), is a critical parameter that strongly influences manufacturing defects, yields, and reliabilities of large-scale-integrated circuits. Various instruments, so-called particle counters, based on light scattering, light extinction, and holography techniques have been developed to measure and monitor the large particle concentration in semiconductor fabs in real time. However, sizeable fluctuation in the measured particle concentration complicates the statistical process control in the fabs worldwide. Here, we show that an inherent fluctuation exists in the counting of large particles, which is universal, independent of instrument type, and quantitatively determined by the instrument's operation parameters. We analytically derive a statistical theory of the fluctuation based on Poisson statistics and validate the theory through experiments and Monte-Carlo simulation. Furthermore, we provide a strategy to enhance the measurement accuracy by statistically adjusting the instrumental parameters commonly involved in the particle counters. The present results and analyses could be useful for statistical process control in semiconductor fabs to prevent large particle-induced defects such as micro-scratches and pits on wafers.

Polymorphism in the Promoter Region of SEMA5A Is Associated with Sociality Traits in Korean Subjects with Autism Spectrum Disorders.

In this study, we evaluated the association between autism spectrum disorders (ASDs) and 10 single-nucleotide polymorphisms (SNPs) in the 5' region of the semaphorin 5A gene (SEMA5A) for 250 Korean trios including children with ASDs. Family-based association testing and haplotype analysis revealed a statistically significant association between rs194085 and multiple sociality traits with Korean ASDs in the dominant model (p<0.001, corrected p=0.035). This indicates that genetic variations in the 5' region of SEMA5A play a role in the genetic predisposition to sociality traits in Korean ASDs.

Genetic association analyses of neuregulin 1 gene polymorphism with endopheontype for sociality of Korean autism spectrum disorders family.

To determine the genetic association between qualitative and quantitative traits of autism spectrum disorder (ASD) and neuregulin 1 (NRG1)-a schizophrenia candidate gene-we examined six single nucleotide polymorphisms (SNPs) in NRG1 using a family-based association test (FBAT) in Korean families with ASD. rs35753505 and rs6994992 SNPs in NRG1 revealed a statistically significant family-based association with three quantitative traits for sociality.

Application of a combined three-stage system for reclamation of tunnel construction wastewater.

A combined three-stage system, (1) coagulation (2) zeocarbon filtration and (3) membrane filtration, a combination of microfiltration (MF) and reverse osmosis (RO), was investigated for reclamation of tunnel construction wastewater having a salinity of 10.8-12.9‰ and a concentration of suspended solids (SS) in the range of 264-1084 mg/L. The initial stages - coagulation, zeocarbon filtration and MF - served as a precursor to RO membrane filtration to successfully reduce water contaminants to less than 0.2 nephelometric turbidity units (NTU) of turbidity, thereby minimizing the potential for fouling. The RO system subsequently removed over 99% of remaining pollutants including ionic substances, resulting in less than 0.02 NTU turbidity, less than 0.04 mg/L total nitrogen (TN) and less than 0.01 mg/L total phosphorus (TP). Also, addition of an RO system markedly reduced high salt concentrations (high chloride (Cl(-)) concentrations) in the wastewater, exceeding 99% salt elimination. Thus, reclaimed water from our combined system met and exceeded currently regulatory quality standards for wastewater reuse (turbidity ≤ 2.0 NTU; TN ≤ 10 mg/L; TP ≤ 0.5 mg/L; Cl(-) ≤ 250 mg/L).

Detection of earthquake-induced damage in a framed structure using a finite element model updating procedure.

Damage of a 5-story framed structure was identified from two types of measured data, which are frequency response functions (FRF) and natural frequencies, using a finite element (FE) model updating procedure. In this study, a procedure to determine the appropriate weightings for different groups of observations was proposed. In addition, a modified frame element which included rotational springs was used to construct the FE model for updating to represent concentrated damage at the member ends (a formulation for plastic hinges in framed structures subjected to strong earthquakes). The results of the model updating and subsequent damage detection when the rotational springs (RS model) were used were compared with those obtained using the conventional frame elements (FS model). Comparisons indicated that the RS model gave more accurate results than the FS model. That is, the errors in the natural frequencies of the updated models were smaller, and the identified damage showed clearer distinctions between damaged and undamaged members and was more consistent with observed damage.

No association of the norepinephrine transporter gene (SLC6A2) and cognitive and behavioural phenotypes of patients with autism spectrum disorder.

We examined the association between the norepinephrine transporter (SLC6A2) gene and autism spectrum disorder (ASD) in a Korean population. In addition, we investigated which phenotypes of ASD are best attributed to the genotype of SLC6A2. A total of 184 subjects with ASD, their 156 unaffected siblings and both biological parents were recruited through university hospitals. We used the Autism Diagnostic Interview-Revised, the Aberrant Behaviour Checklist (ABC), the Child Behaviour Checklist (CBCL), the Stroop Colour-Word Interference Test and the Wisconsin Card Sorting Test (WCST) as quantitative measures of the ASD phenotypes. The associations between the quantitative measures and specific single-nucleotide polymorphisms (SNPs) were tested with linear regression analyses. We did not find any evidence of the over-transmission of either allele of the 10SLC6A2 SNPs in the DFAM test. At an empirical p value <0.05, findings that were consistent between the linear regression analyses and the QFAM tests were the positive associations between the A allele of rs36020 and attention problems on the CBCL and stereotypical behaviours on the ABC and between the C allele of rs1814270 and the number of trials required to complete the first WCST category. However, these associations did not remain after correction for multiple testing. The study results of this study do not support the association between the SLC6A2 and the diagnosis or phenotype of ASD. However, the study must be replicated in larger populations and with using more genetic markers.

Clinical characteristics of patients who have recovered from schizophrenia: the role of empathy and positive-self schema.

AIM: This article compares the socio-demographic and clinical characteristics of patients with schizophrenia who recovered with those who achieved remission. METHODS: Participants were classified based on predetermined criteria for recovery and remission. Data on demographic characteristics, information on duration of untreated psychosis, and assessments of current and historical symptom profiles and socio-occupational functioning emerged from careful chart review and direct interviews. Cross-sectional assessments of clinical variables were derived from the Positive and Negative Syndrome Scale, the Scale for the Assessment of Negative Symptoms, the Personal and Social Performance Scale, the Social Functioning Questionnaire, the Schizophrenia Cognition Rating Scale (ScoRS), the Basic Empathy Scale, and the Brief Core Schema Scales (BCSS). RESULTS: We found no significant differences between recovered and remitted groups with respect to demographic variables or duration of untreated psychosis. Cognitive and total empathy scores, positive-self schema score on the BCSS, and global score on the ScoRS were significantly higher in the recovered than the remitted group. Furthermore, patients with good levels of empathy and positive-self schema and intact neurocognitive functioning were more likely to achieve recovery. CONCLUSION: These results suggest that empathy, positive-self schema and neurocognitive functioning may serve as important clinical characteristics distinguishing those patients who have recovered from those who have achieved only remission.