Fully reconfigurable MEMS-based second-order coupled-resonator optical waveguide (CROW) with ultra-low tuning energy.

Integrated microring resonators are well suited for wavelength-filtering applications in optical signal processing, and cascaded microring resonators allow flexible filter design in coupled-resonator optical waveguide (CROW) configurations. However, the implementation of high-order cascaded microring resonators with high extinction ratios (ERs) remains challenging owing to stringent fabrication requirements and the need for precise resonator tunability. We present a fully integrated on-chip second-order CROW filter using silicon photonic microelectromechanical systems (MEMS) to adjust tunable directional couplers and a phase shifter using nanoscale mechanical out-of-plane waveguide displacement. The filter can be fully reconfigured with regard to both the ER and center wavelength. We experimentally demonstrated an ER exceeding 25 dB and continuous wavelength tuning across the full free spectral range of 0.123 nm for single microring resonator, and showed reconfigurability in second-order CROW by tuning the ER and resonant wavelength. The tuning energy for an individual silicon photonic MEMS phase shifter or tunable coupler is less than 22 pJ with sub-microwatt static power consumption, which is far better than conventional integrated phase shifters based on other physical modulation mechanisms.

Programmable MZI based on a silicon photonic MEMS-tunable delay line.

We report on a scalable and programmable integrated Mach-Zehnder interferometer (MZI) with a tunable free spectral range (FSR) and extinction ratio (ER). For the tunable path of the MZI, we designed and utilized a tunable delay line having high flexibility based on silicon photonic microelectromechanical systems (MEMS). By utilizing MEMS, the length of the delay line can be geometrically modified. In this way, there is no optical loss penalty other than the waveguide propagation loss as the number of tunable steps increases. Therefore, our device is more scalable in terms of optical loss than the previous approaches based on cascaded MZIs. In addition, the tuning energy required to reconfigure the length is only 8.46 pJ.

Low Power Coherent Ising Machine Based on Mechanical Kerr Nonlinearity.

Finding a reliable Ising machine for solving nondeterministic polynomial-class problems has attracted great attention in recent years, where an authentic system can be expanded with polynomial-scaled resources to find the ground state Ising Hamiltonian. In this Letter, we propose an extremely low power optomechanical coherent Ising machine based on a new enhanced symmetry breaking mechanism and highly nonlinear mechanical Kerr effect. The mechanical movement of an optomechanical actuator induced by the optical gradient force greatly increases the nonlinearity by a few orders and significantly reduces the power threshold using conventional structures capable of fabrication via photonic integrated circuit platforms. With the simple but strong bifurcation mechanism and remarkably low power requirement, our optomechanical spin model opens a path for chip-scale integration of large-size Ising machine implementations with great stability.

Assessment of sources variability of riverine particulate organic matter with land use and rainfall changes using a three-indicator (δ13C, δ15N, and C/N) Bayesian mixing model.

In intensive agricultural watersheds, riverine particulate organic matter (POM) may be transported from many sources such as rice paddies, crop uplands, forests, and livestock farming areas during rainy seasons. However, the impacts of land-use and rainfall changes on the POM sources are not well understood. In this study, changes in the sources of riverine POM were investigated in an agricultural area of Korea between 2014 and 2020/21. During this period, land-use and rainfall patterns changed dramatically. The δ13C, δ15N, and C/N of the POM sources as well as those of riverine POM were analyzed, and a stable isotope analysis in R (SIAR) model was utilized for source apportionment. There were differences in δ13C, δ15N, and C/N among the sources. For example, manure had higher δ13C (-22.6 ± 3.3‰) and δ15N (+10.6 ± 5.9‰) than soils (from -28.0 ± 0.8‰ to -25.1 ± 1.2‰ for δ13C and +3.6 ± 1.7‰ to +9.8 ± 1.4‰ for δ15N). For soils, the δ13C and δ15N were higher for upland soils, while C/N was greater for forest soils than for others. For riverine POM, the δ15N marginally changed; however, the δ13C and C/N increased from -26.1 ± 0.9‰ to -20.8 ± 5.3‰ and from +7.7 ± 1.7 to +18.8 ± 8.3 between 2014 and 2020/21, respectively. The SIAR model showed that the contributions of paddy (from 41.0% to 14.9%) and upland fields (from 48.1% to 23.7%) to riverine POM decreased between the periods due to decreased paddy area and the implementation of best management practice on upland fields, respectively. However, the contribution of forests (from 3.5% to 28.0%) and manure (from 7.4% to 33.5%) increased probably due to improper management of forest clear-cutting sites and livestock manure storage sites. The contributions of agricultural soils to riverine POM decreased in drier years. Our study suggests that land management rather than land-use area is critical in riverine POM management, particularly in wetter years.

Advances and challenges in intravital imaging of craniofacial and dental progenitor cells.

Craniofacial and appendicular bone homeostasis is dynamically regulated by a balance between bone formation and resorption by osteoblasts and osteoclasts, respectively. Despite the developments in multiple imaging techniques in bone biology, there are still technical challenges and limitations in the investigation of spatial/anatomical location of rare stem/progenitor cells and their molecular regulation in tooth and craniofacial bones of living animals. Recent advances in live animal imaging techniques for the craniofacial and dental apparatus can provide new insights in real time into bone stem/progenitor cell dynamics and function in vivo. Here, we review the current inventions and applications of the noninvasive intravital imaging technique and its practical uses and limitations in the analysis of stem/progenitor cells in craniofacial and dental apparatus in vivo. Furthermore, we also explore the potential applications of intravital microscopy in the dental field.

Sensory Interaction and Balancing Ability Evaluation of the Elderly Using a Simplified Force Plate System.

The Wii balance board (WBB) is a simplified force plate system used to evaluate the balancing ability of the elderly via a sensory interaction task to confirm a significant standing balance index. The accuracy of this system has been verified in previous studies. In this study, an instrumented and modified clinical test of sensory interaction on balance (i-mCTSIB) was performed on 84 elderly subjects, and the variables for center of pressure (CoP) were calculated using WBB for each task condition. The results indicate that the visual condition has a significant effect on the sway proprioceptive sensory variables with a foam condition as their complexity increases. In addition, the correlation between the variable and Berg Balance Scale was not confirmed since CTSIB is a sensory interaction on balance ability. Therefore, WBB can be used to evaluate balancing ability based on sensory interactions consisting of the surface condition.

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.

Decreasing maternal myostatin programs adult offspring bone strength in a mouse model of osteogenesis imperfecta.

During fetal development, the uterine environment can have effects on offspring bone architecture and integrity that persist into adulthood; however, the biochemical and molecular mechanisms remain unknown. Myostatin is a negative regulator of muscle mass. Parental myostatin deficiency (Mstntm1Sjl/+) increases muscle mass in wild-type offspring, suggesting an intrauterine programming effect. Here, we hypothesized that Mstntm1Sjl/+ dams would also confer increased bone strength. In wild-type offspring, maternal myostatin deficiency altered fetal growth and calvarial collagen content of newborn mice and conferred a lasting impact on bone geometry and biomechanical integrity of offspring at 4 mo of age, the age of peak bone mass. Second, we sought to apply maternal myostatin deficiency to a mouse model with osteogenesis imperfecta (Col1a2oim), a heritable connective tissue disorder caused by abnormalities in the structure and/or synthesis of type I collagen. Femora of male Col1a2oim/+ offspring from natural mating of Mstntm1Sjl/+ dams to Col1a2oim/+sires had a 15% increase in torsional ultimate strength, a 29% increase in tensile strength, and a 24% increase in energy to failure compared with age, sex, and genotype-matched offspring from natural mating of Col1a2oim/+ dams to Col1a2oim/+ sires. Finally, increased bone biomechanical strength of Col1a2oim/+ offspring that had been transferred into Mstntm1Sjl/+ dams as blastocysts demonstrated that the effects of maternal myostatin deficiency were conferred by the postimplantation environment. Thus, targeting the gestational environment, and specifically prenatal myostatin pathways, provides a potential therapeutic window and an approach for treating osteogenesis imperfecta.

Comparison of Bioactive Compounds and Antioxidant Activities of Maclura tricuspidata Fruit Extracts at Different Maturity Stages.

Abstract: Maclura tricuspidata fruit contains various bioactive compounds and has traditionally been used in folk medicine and as valuable food material in Korea. The composition and contents of bioactive compounds in the fruit can be influenced by its maturity stages. In this study, total phenol, total flavonoid, individual polyphenolic compounds, total carotenoids and antioxidant activities at four maturity stages of the fruit were determined. Polyphenolic compounds were analyzed using high-pressure liquid chromatography-quadrupole time-of-flight mass spectrometry (HPLC-QTOF-MS) and HPLC. Among 18 polyphenolic compounds identified in this study, five parishin derivatives (gastrodin, parishin A, B, C, E) were positively identified for the first time in this plant. These compounds were also validated and quantified using authentic standards. Parishin A was the most abundant component, followed by chlorogenic acid, gastrodin, eriodictyol glucoside, parishin C, parishin E and parishin B. The contents of all the polyphenolic compounds were higher at the immature and premature stages than at fully mature and overmature stages, while total carotenoid was found to be higher in the mature and overmature stages. Overall antioxidant activities by three different assays (DPPH, ABTS, FRAP) decreased as maturation progressed. Antioxidant properties of the fruit extract are suggested to be attributed to the polyphenols.

Soluble activin receptor type IIB decoy receptor differentially impacts murine osteogenesis imperfecta muscle function.

INTRODUCTION: Osteogenesis imperfecta (OI) is characterized by skeletal fragility and muscle weakness. In this study we investigated the effects of soluble activin type IIB receptor (sActRIIB-mFc) on muscle mass and function in 2 distinct mouse models of OI: osteogenesis imperfecta murine (oim) and +/G610C. METHODS: Wild-type (WT), +/G610C, and oim/oim mice were treated from 2 to 4 months of age with Tris-buffered saline (vehicle) or sActRIIB-mFc and their hindlimb muscles evaluated for mass, morphology, and contractile function. RESULTS: sActRIIB-mFc-treated WT, +/G610C, and oim/oim mice had increased hindlimb muscle weights and myofiber cross-sectional area compared with vehicle-treated counterparts. sActRIIB-mFc-treated oim/oim mice also exhibited increased contractile function relative to vehicle-treated counterparts. DISCUSSION: Blocking endogenous ActRIIB was effective at increasing muscle size in mouse models of OI, and increasing contractile function in oim/oim mice. ActRIIB inhibitors may provide a potential mutation-specific therapeutic option for compromised muscle function in OI. Muscle Nerve 57: 294-304, 2018.