Photon counting Raman spectroscopy: a benchmarking study vs surface plasmon enhancement.

We demonstrate a single-photon counting Raman spectroscope and benchmark it against conventional and surface-enhanced Raman spectroscopy. For direct comparison without ambiguity, we use the same solutions of Rhodamine 6G and a common optical setup with either a spectrometer or an acousto-optic tunable filter, whereas the surface enhancement is realized with immobilized Ag nanoparticles. Our results find that the single photon counting significantly elevates the detection sensitivity by up to eight orders of magnitude, arriving at a comparable level of surface-enhanced Raman spectroscopy. Another significant advantage is with the time-resolving measurement, where we demonstrate time-gated and time-correlated single-photon counting with sub-nanosecond resolution. It offers insights into the samples' transient responses and enables the isolation of Raman scattering from fluorescence signals.

Invertible all-optical logic gate on chip.

We demonstrate an invertible all-optical gate on chip, with the roles of control and signal switchable by slightly adjusting their relative arrival time at the gate. It is based on the quantum Zeno blockade (QZB) driven by sum-frequency generation (SFG) in a periodically poled lithium niobate microring resonator. For two nearly identical nanosecond pulses, the later arriving pulse is modulated by the earlier arriving one, resulting in 2.4 and 3.9 power extinction between the two, respectively, when their peak powers are 1 mW and 2 mW, respectively. Our results, while to be improved and enriched, herald a new, to the best of our knowledge, paradigm of logical gates and circuits for exotic applications.

Broadband frequency comb generation through cascaded quadratic nonlinearity in thin-film lithium niobate microresonators.

Broadband frequency comb generation through cascaded quadratic nonlinearity remains experimentally untapped in free-space cavities with bulk χ(2) materials mainly due to the high threshold power and restricted ability of dispersion engineering. Thin-film lithium niobate (LN) is a good platform for nonlinear optics due to the tight mode confinement in a nano-dimensional waveguide, the ease of dispersion engineering, large quadratic nonlinearities, and flexible phase matching via periodic poling. Here we demonstrate broadband frequency comb generation through dispersion engineering in a thin-film LN microresonator. Bandwidths of 150 nm (80 nm) and 25 nm (12 nm) for center wavelengths at 1560 and 780 nm are achieved, respectively, in a cavity-enhanced second-harmonic generation (doubly resonant optical parametric oscillator). Our demonstration paves the way for pure quadratic soliton generation, which is a great complement to dissipative Kerr soliton frequency combs for extended interesting nonlinear applications.

How do probiotics alleviate constipation? A narrative review of mechanisms.

Constipation is a common gastrointestinal condition, which may occur at any age and affects countless people. The search for new treatments for constipation is ongoing as current drug treatments fail to provide fully satisfactory results. In recent years, probiotics have attracted much attention because of their demonstrated therapeutic efficacy and fewer side effects than pharmaceutical products. Many studies attempted to answer the question of how probiotics can alleviate constipation. It has been shown that different probiotic strains can alleviate constipation by different mechanisms. The mechanisms on probiotics in relieving constipation were associated with various aspects, including regulation of the gut microbiota composition, the level of short-chain fatty acids, aquaporin expression levels, neurotransmitters and hormone levels, inflammation, the intestinal environmental metabolic status, neurotrophic factor levels and the body's antioxidant levels. This paper summarizes the perception of the mechanisms on probiotics in relieving constipation and provides some suggestions on new research directions.

Insisting on help, facing challenges, and maintaining balance: The lived experiences of caregivers raising a child with developmental delay in the remote islands of Kinmen.

PURPOSE: To explore the lived experiences of the caregivers of children with developmental delay (DD) on the remote island of Kinmen, Taiwan. DESIGN AND METHODS: This descriptive phenomenological study included 14 caregivers of 16 children with DD recruited from Kinmen, Taiwan. Data were collected from September 2020 to February 2021 with face-to-face semi-structured interviews, which were transcribed verbatim and analyzed using thematic analysis. RESULTS: Twelve caregivers were mothers; there was one father and one grandmother. Their mean age was 37.93 ± 5.17 years. The mean age of the children was 3.90 ± 1.49 years; 11 were male (69%). As we began our study, the COVID-19 pandemic occurred, which influenced two of the three themes: (1) focusing on their child's delayed development, which involved seeking a diagnosis and blaming themselves; (2) facing barriers to caring a child with DD on a remote island, which included ostracization of their child and limited off-island medical resources, especially during COVID-19; and (3) maintaining a healthy life balance, which involved protecting their child from physical or spiritual harm, including exposure to COVID-19, and reflecting on their strengths. CONCLUSIONS: Our findings highlight the challenges of caring for a child with DD in the Kinmen islands of Taiwan, and the impact of the COVID-19 pandemic. PRACTICAL IMPLICATIONS: Healthcare professionals are encouraged to provide caregivers of children with DD living in remote, island communities an opportunity to share their caregiving experiences and provide strategies for obtaining medical care, which could help reduce caregiver burden.

Single-pixel image reconstruction using coherent nonlinear optics.

We propose and experimentally demonstrate a novel, to the best of our knowledge, hybrid optoelectronic system that utilizes mode-selective frequency upconversion, single-pixel detection, and a deep neural network to achieve the reliable reconstruction of two-dimensional (2D) images from a noise-contaminated database of handwritten digits. Our system is designed to maximize the multi-scale structural similarity index measure (MS-SSIM) and minimize the mean absolute error (MAE) during the training process. Through extensive evaluation, we have observed that the reconstructed images exhibit high-quality results, with a peak signal-to-noise ratio (PSNR) reaching approximately 20 dB and a structural similarity index measure (SSIM) of around 0.85. These impressive metrics demonstrate the effectiveness and fidelity of our image reconstruction technique. The versatility of our approach allows its application in various fields, including Lidar, compressive imaging, volumetric reconstruction, and so on.

Characterization and Genomic Analysis of ɸSHP3, a New Transposable Bacteriophage Infecting Stenotrophomonas maltophilia.

This study describes a novel transposable bacteriophage, ɸSHP3, continuously released by Stenotrophomonas maltophilia strain c31. Morphological observation and genomic analysis revealed that ɸSHP3 is a siphovirus with a 37,611-bp genome that encodes 51 putative proteins. Genomic comparisons indicated that ɸSHP3 is a B3-like transposable phage. Its genome configuration is similar to that of Pseudomonas phage B3, except for the DNA modification module. Similar to B3-like phages, the putative transposase B of ɸSHP3 is a homolog of the type two secretion component ExeA, which is proposed to serve as a potential virulence factor. Moreover, most proteins of ɸSHP3 have homologs in transposable phages, but only ɸSHP3 carries an RdgC-like protein encoded by gene 3, which exhibits exonuclease activity in vitro Two genes and their promoters coding for ɸSHP3 regulatory proteins were identified and appear to control the lytic-lysogenic switch. One of the proteins represses one promoter activity and confers immunity to ɸSHP3 superinfection in vivo The short regulatory region, in addition to the canonical bacterial promoter sequences, displays one LexA and two CpxR recognition sequences. This suggests that LexA and the CpxR/CpxA two-component system might be involved in the control of the ɸSHP3 genetic switch.IMPORTANCES. maltophilia is an emerging global pathogenic bacterium that displays genetic diversity in both environmental and clinical strains. Transposable phages have long been known to improve the genetic diversity of bacterial strains by transposition. More than a dozen phages of S. maltophilia have been characterized. However, no transposable phage infecting S. maltophilia has been reported to date. Characterization of the first transposable phage, ɸSHP3, from S. maltophilia will contribute to our understanding of host-phage interactions and genetic diversity, especially the interchange of genetic materials among S. maltophilia.

Single-photon vibrometry.

We propose and demonstrate a single-photon sensitive technique for optical vibrometry. It uses high speed photon counting to sample the modulated backscattering from a vibrating target. Designed for remote vibration sensing with ultralow photon flux, we show that this technique can detect small displacements down to 110 nm and resolve vibration frequencies from DC up to several kilohertz, with ≤0.01 detected photons per pulse. This single-photon sensitive optical vibrometry may find important applications in acousto-optic sensing and imaging, especially in photon-starved environments.

Super-resolution optical classifier with high photon efficiency.

We propose and demonstrate a photon-efficient optical classifier to overcome the Rayleigh limit in spatial resolution. It utilizes mode-selective sum-frequency generation and single-pixel photon detection to resolve closely spaced incoherent sources based on photon counting statistics. Super-resolving and photon efficient, this technique can find applications in microscopy, light detection and ranging, and astrophysics.

Single-pixel pattern recognition with coherent nonlinear optics.

In this Letter, we propose and experimentally demonstrate a nonlinear-optics approach to pattern recognition with single-pixel imaging and a deep neural network. It employs mode-selective image up-conversion to project a raw image onto a set of coherent spatial modes, whereby its signature features are extracted optically in a nonlinear manner. With 40 projection modes, the classification accuracy reaches a high value of 99.49% for the modified national institute of standards and technology handwritten digit images, and up to 95.32%, even when they are mixed with strong noise. Our experiment harnesses rich coherent processes in nonlinear optics for efficient machine learning, with potential applications in online classification of large-size images, fast lidar data analyses, complex pattern recognition, and so on.

Efficient and highly tunable second-harmonic generation in Z-cut periodically poled lithium niobate nanowaveguides.

Thin-film lithium-niobate-on-insulator (LNOI) has emerged as a superior integrated-photonics platform for linear, nonlinear, and electro-optics. Here we combine quasi-phase-matching, dispersion engineering, and tight mode confinement to realize nonlinear parametric processes with both high efficiency and wide wavelength tunability. On a millimeter-long, Z-cut LNOI waveguide, we demonstrate efficient (1900±500%W-1cm-2) and highly tunable (-1.71nm/K) second-harmonic generation from 1530 to 1583 nm by type-0 quasi-phase-matching. Our technique is applicable to optical harmonic generation, quantum light sources, frequency conversion, and many other photonic information processes across visible to mid-IR spectral bands.

Ultrabright Quantum Photon Sources on Chip.

Quantum photon sources of high rate, brightness, and purity are increasingly desirable as quantum information systems are quickly scaled up and applied to many fields. Using a periodically poled lithium niobate microresonator on chip, we demonstrate photon-pair generation at high rates of 8.5 and 36.3 MHz using only 3.4 and 13.4 µW pump power, respectively, marking orders of magnitude improvement over the state of the art, across all material platforms. These results constitute the first direct measurement of the device's giant single photon nonlinearity. The measured coincidence to accidental ratio is well above 100 at those high rates and reaches 14682±4427 at a lower pump power. The same chip enables heralded single-photon generation at tens of megahertz rates, each with low autocorrelation g_{H}^{(2)}(0)=0.008 and 0.097 for the microwatt pumps, which marks a new milestone. Such distinct performance, facilitated by the chip device's noiseless and giant optical nonlinearity, will contribute to the forthcoming pervasive adoption of quantum optical information technologies.

Production of a specific monoclonal antibody for 1-naphthol based on novel hapten strategy and development of an easy-to-use ELISA in urine samples.

1-naphthol (1-NAP) is the main metabolite of pesticide carbaryl and naphthalene, and is also a genotoxic and carcinogenic intermediate in the synthesis of organic compound, dyes, pigment and pharmaceutical industry. In this work, two novel haptens were designed and synthesized for developing a competitive indirect enzyme-linked immunosorbent assay (ciELISA) method for 1-NAP in urine samples. The assay showed a limit of detection of 2.21 ng/mL and working range from 4.02 ng/mL to 31.25 ng/mL for 1-NAP in optimized working buffer. The matrix effect of samples was eliminated via 15-fold dilution of optimized working buffer. Good average recoveries (102.4%-123.4%) with a coefficient of variation from 11.7% to 14.7% was obtained for spiked urine samples. Subsequent instrument verification test showed good correlation between the results of ciELISA and high-performance liquid chromatography. The developed ciELISA is a high-throughput tool to monitor 1-NAP in urine, which can provide technical support for the establishment of biological exposure level for the exposure to carbaryl, naphthalene and other related pollutants.

Maternal Caregiving for Children Newly Diagnosed with Acute Lymphoblastic Leukemia: Traditional Chinese Mothering as the Double-Edged Sword.

AIMS AND OBJECTIVES: To explore the meaning of maternal caregiving in the Chinese culture for children newly diagnosed with acute lymphocytic leukemia (ALL). BACKGROUND: Recurrence of and death associated with ALL remain the main concerns for mothers. Mothers experience guilt and anxiety towards their child's cancer. DESIGN: Descriptive phenomenological study. METHODS: Twelve mothers were recruited from a medical centre in Central Taiwan. The mothers were primary caregivers for their child diagnosed as having ALL in the past 3 months to 1 year. Data were collected through semi-structured interviews and analysed using Colaizzi's method. RESULTS: Four main themes emerged: feeling this world crashing by knowing the diagnosis, feeling the double-edged sword of mothering, worrying about potential risks for their vulnerable child, and passing through difficulties with power of support. CONCLUSIONS: Most mothers felt this world crashing due to potential loss of their child and seeing their child's suffering. The mother was blamed for her child's cancer but was also required to shoulder all caregiving for their child. The mothers needed to compromise their lives to protect their child from potential infection. Perceived power of support helped the mothers overcome difficulties. RELEVANCE TO CLINICAL PRACTICE: Findings support that nurses encouraging mothers to tell their stories, regardless of culture, will facilitate healing. Establishing trust and providing support from nurses, physicians, psychologists and social workers will lead mothers' readiness to deal with care of their sick child. Increasing visiting time for parental support for children hospitalized in the PICU is suggested as well.

Influence of virtual keyboard design and usage posture on typing performance and muscle activity during tablet interaction.

This study aimed to determine the effects of virtual keyboard designs and postures on task performance and muscle activity during tablet use. Eighteen healthy adults were randomly assigned to one of three postures (DESK, LAP, BED) to complete six sessions of 60-minute typing on a tablet with three virtual keyboards (STD, WIDE, SPLIT) twice in an experimental laboratory. Keystroke dynamics and muscle activity of the forearm and neck-shoulder regions were measured by electromyography. The split virtual keyboard was found to be associated with faster typing speed (SPLIT vs STD, p = .015; SPLIT vs WIDE, p < .001) and decreased muscle activity of extensor digitorum communis (SPLIT vs STD, p = .021). Lap posture was associated with faster typing speed (p = .018) and higher forearm muscle activity (p < .05). Typing performance decreased (p < .001) with elevated neck extensor muscle activity (p = .042) when the task duration prolonged. The split virtual keyboard showed potential to improve tablet ergonomics under various postures. Practitioner Summary: Tablets have become widely used for a variety of tasks and have gradually expanded into the realm of mobile productivity and education. Adequate designs of virtual keyboards for tablets show the potential for increased task performance and decreased muscle activity pertinent to typing activity and posture constraints imposed by non-traditional work positions. Abbreviations: WPM: words per minute; IKI: inter-key press interval; EMG: electromyography; EDC: extensor digitorum communis; FDS: flexor digitorum superficialis; CES: cervical erector spinae; UT: upper trapezius; EA: electrical activity; MVC: maximum voluntary contraction; APDF: amplitude probability distribution function.

Shame, Suffering, and Believing in the Family: The Experiences of Grandmothers of a Grandchild With a Developmental Delay or Disability in the Context of Chinese Culture.

Grandparents are primary resources of caregiving support for parents worldwide, regardless of the cultural background. In Chinese societies, grandmothers often fill the role of supportive caregiver. However, a knowledge gap in the literature exists about how Chinese culture influences caregiving for grandmothers of grandchildren with a disability, particularly in Taiwan. This phenomenological study explored the lived experience of grandmothers caring for a grandchild with a developmental delay or disability in the context of Chinese culture. Twenty-five grandmothers were interviewed. When grandmothers learned of their grandchild's disability, they experienced suffering, which was compounded by the stigma attached to persons with a disability in Chinese cultures, and they also experienced shame and fear of social rejection. Grandmothers' belief in the importance of family gave meaning to their suffering and prompted them to find new ways to deal with everyday difficulties. These findings can guide nurses and health care professionals responsible for supporting grandmothers caring for a child with a disability in the context of Chinese culture.

High-extinction electro-optic modulation on lithium niobate thin film.

Integrated nanophotonics using lithium-niobate-on-insulator promises much-awaited solutions for scalable photonics techniques. One of its core functions is electro-optic modulation, which currently suffers limited extinction (<30 dB) due to inevitable fabrication errors. We exploit a cascaded Mach-Zehnder interferometry design to offset those errors, demonstrating up to 53 dB modulation extinction for a wide range of wavelengths between 1500 nm and 1600 nm. Together, its favorable features of chip integration, high extinction, good stability, and being broadband may prove valuable in a plethora of flourishing photonics applications.

Mode-selective image upconversion.

We study selective upconversion of optical signals according to their detailed transverse electromagnetic modes and demonstrate its proof of operation in a nonlinear crystal. The mode selectivity is achieved by preparing the pump wave in an optimized spatial profile to drive the upconversion. For signals in the Laguerre-Gaussian modes, we show that a mode can be converted with up to 60 times higher efficiency than an overlapping, but orthogonal, mode. This nonlinear optical approach may find applications in compressive imaging, pattern recognition, quantum communications, and others, where the existing linear optical methods are limited.

Mode selective up-conversion detection for LIDAR applications.

We study mode selective up-conversion detection as a viable approach to improving signal-to-noise and ranging resolution in LIDAR applications. It involves pumping a nonlinear waveguide at the edge of phase matching with picosecond pulses, so that only the backscattered signal photons in a single or few desirable time-frequency modes are efficiently up-converted while the broadband background noise in all other modes is rejected. We demonstrate a 41-dB increase in the signal-to-noise ratio for single-photon counting compared to that of direct detection using a commercial InGaAs single-photon detector, while achieving sub-millimeter ranging resolution with few detected photons. The proposed technique implies new LIDAR capabilities for ranging and imaging.

Programmable quantum random number generator without postprocessing.

We demonstrate a viable source of unbiased quantum random numbers whose statistical properties can be arbitrarily programmed without the need for any postprocessing such as randomness distillation or distribution transformation. It is based on measuring the arrival time of single photons in shaped temporal modes that are tailored with an electro-optical modulator. We show that quantum random numbers can be created directly in customized probability distributions and pass all randomness tests of the NIST and Dieharder test suites without any randomness extraction. The min-entropies of such generated random numbers are measured close to the theoretical limits, indicating their near-ideal statistics and ultrahigh purity. Easy to implement and arbitrarily programmable, this technique can find versatile uses in a multitude of data analysis areas.