Simulating the vibrational quantum dynamics of molecules using photonics.

Advances in control techniques for vibrational quantum states in molecules present new challenges for modelling such systems, which could be amenable to quantum simulation methods. Here, by exploiting a natural mapping between vibrations in molecules and photons in waveguides, we demonstrate a reprogrammable photonic chip as a versatile simulation platform for a range of quantum dynamic behaviour in different molecules. We begin by simulating the time evolution of vibrational excitations in the harmonic approximation for several four-atom molecules, including H2CS, SO3, HNCO, HFHF, N4 and P4. We then simulate coherent and dephased energy transport in the simplest model of the peptide bond in proteins-N-methylacetamide-and simulate thermal relaxation and the effect of anharmonicities in H2O. Finally, we use multi-photon statistics with a feedback control algorithm to iteratively identify quantum states that increase a particular dissociation pathway of NH3. These methods point to powerful new simulation tools for molecular quantum dynamics and the field of femtochemistry.

Compound-eye metasurface optics enabling a high-sensitivity, ultra-thin polarization camera.

Polarization imaging is key for various applications ranging from biology to machine vision because it can capture valuable optical information about imaged environments, which is usually absent in intensity and spectral content. Conventional polarization cameras rely on a traditional single-eye imaging system with rotating polarizers, cascaded optics, or micropolarizer-patterned image sensors. These cameras, however, have two common issues. The first is low sensitivity resulting from the limited light utilization efficiency of absorptive polarizers or cascaded optics. The other is the difficulty in device miniaturization due to the fact that these devices require at least an optical-path length equivalent to the lens's focal length. Here, we propose a polarization imaging system based on compound-eye metasurface optics and show how it enables the creation of a high-sensitivity, ultra-thin polarization camera. Our imaging system is composed of a typical image sensor and single metasurface layer for forming a vast number of images while sorting the polarization bases. Since this system is based on a filter-free, computational imaging scheme while dramatically reducing the optical-path length required for imaging, it overcomes both efficiency and size limitations of conventional polarization cameras. As a proof of concept, we demonstrated that our system improves the amount of detected light by a factor of ∼2, while reducing device thickness to ∼1/10 that of the most prevalent polarization cameras. Such a sensitive, compact, and passive device could pave the way toward the widespread adoption of polarization imaging in applications in which available light is limited and strict size constraints exist.

Optical frequency distribution using laser repeater stations with planar lightwave circuits.

We report a cascaded optical fiber link which connects laboratories in RIKEN, the University of Tokyo, and NTT within a 100-km region using a transfer light at 1397 nm, a subharmonic of the Sr clock frequency. The multiple cascaded link employing several laser repeater stations benefits from a wide feedback bandwidth for fiber noise compensation, which allows constructing optical lattice clock networks based on the master-slave configuration. We developed the laser repeater stations based on planar lightwave circuits to significantly reduce the interferometer noise for improved link stability. We implemented a 240-km-long cascaded link in a UTokyo-NTT-UTokyo loop using light sent from RIKEN via a 30-km-long link. In environments with large fiber noise, the link instability is 3 × 10-16 at an averaging time of 1 s and reaches 1 × 10-18 at 2,600 s.

Net-400-Gbps PS-PAM transmission using integrated AMUX-MZM.

Simple high-speed optical transmission technologies are desired for use in intra-and inter-datacenter networks. In this study, we demonstrate simple single-carrier intensity-modulated direct-detection (IMDD) transmissions at a net data rate of 400 Gbps (516.7 Gbps gross) over 20 km with a compact transmitter subassembly. The subassembly consists of a 2:1 analog multiplexer (AMUX) and an InP Mach-Zehnder modulator (MZM) placed close to each other and connected via wires. We employed 162-Gbaud single-carrier probabilistically shaped pulsed amplitude modulation (PS-PAM). The baseband signals with a bandwidth of around 81 GHz to drive the MZM were generated by a super-digital-to-analog converter (super-DAC) consisting of two sub-DACs and the AMUX. Digital nonlinear pre-distortion enabled us to transmit the signals with normalized generalized mutual information (NGMI) larger than the threshold of a soft-decision forward error correction (SD-FEC) code of 0.857. Truncation of the PS-PAM symbol distribution further enhanced performance. To the best of our knowledge, this is the first net-400-Gbps single-carrier IMDD transmission using a compact transmitter subassembly.

Isoflurane induces c-Fos expression in the area postrema of the rat.

INTRODUCTION: Volatile anesthetics are speculated to cause postoperative nausea and vomiting via stimulation of the chemoreceptor trigger zone (CTZ). However, the precise mechanism underlying the emetic action of these drugs is not well understood. In this study, we assessed whether isoflurane induced the expression of c-Fos, a neuronal activation marker, in the area postrema (AP), the locus of the CTZ, in rats, which do not have vomiting action. MATERIALS AND METHODS: Male rats were exposed to 1.3% isoflurane for 0-240 min, or to various concentrations of isoflurane (0, 1.3%, or 2.6%) for 120 min. Finally, the rats were exposed to 1.3% isoflurane for 120 min after ondansetron administration. After the treatments, immunohistochemistry of the rat AP was performed using c-Fos antibody staining. RESULTS: One-way analysis of variance showed that isoflurane exposure significantly increased c-Fos expression in the AP; however, the rats pretreated with 4 mg/kg ondansetron showed significantly decreased c-Fos expression. Moreover, we evaluated the effect of the anesthetic on inducing pica in the rats, and found that kaolin intake was not influenced by isoflurane exposure. CONCLUSION: Overall, these results suggest that isoflurane activates AP neurons and may be involved in the emetic mechanism of isoflurane. This study further suggests the feasibility of using rats as a model for studying emetic mechanisms of drugs, despite their lack of vomit action.

Demonstration of energy-saving membrane bioreactor (MBR) systems.

Membrane bioreactors (MBRs) have the advantages of achieving excellent effluent quality, a small footprint and smooth operation and maintenance. On the other hand, its high energy consumption remains a critical challenge for MBR application. Japan Sewage Works Agency has conducted a series of joint researches with several private companies since 2012 and developed four kinds of energy-saving MBR systems. Based on the results of long-term pilot-scale demonstrations, specific energy consumption (SEC) per unit treated effluent volume was calculated for each MBR system, resulting in all systems achieving SEC of 0.4 kWh/m3 or less. To meet an additional requirement for expanding MBR application, it is also necessary to establish the applicability of MBR systems to combined sewer systems, suffering from occasional inflow fluctuation caused by rainfall. The capability of temporary higher flux operation during and after rainy weather was also demonstrated with three of the four developed systems.

[Comparison of the Effect of Periarticular Infiltration Analgesia versus Sciatic Nerve Block for Total Knee Arthroplasty].

BACKGROUND: Sciatic nerve block (SNB) is widely used as a supplemental analgesia after total knee arthroplasty (TKA) combined with femoral nerve block (FNB). Despite its effectiveness, SNB often causes peroneal nerve paralysis, which makes it difficult to detect peroneal nerve injury by surgical process. Recently, periarticular infiltration analgesia (PIA) is reported that it provides analgesia without peroneal nerve paralysis. We conducted a retrospective analysis to compare the effectiveness of SNB and PIA. METHODS: This study was approved by the local institutional ethics committee; 17 patients undergoing TKA under general anesthesia with continuous femoral nerve block were enrolled in the study. All patients received continuous FNB. Nine patients received sciatic nerve block successively, while 8 patients received PIA around the time of insertion of artificial joint. Primary outcome measure was the frequency of peroneal nerve paralysis when the patients woke up. Secondary outcome measures included numerical rating scale (NRS) until postoperative day 3. RESULTS: While there were 6 patients who had peroneal nerve paralysis in the SNB group, none of them had it in the PIA group (P = 0.009). There were no significant differences of the NRSs between the two groups. CONCLUSIONS: PIA provided sufficient analgesia after TKA without peroneal nerve paralysis.

Linearity improvement of high-speed avalanche photodiodes using thin depleted absorber operating with higher order modulation format.

We present an avalanche photodiode (APD) with high-speed, high-responsivity and high-linearity operation to cope with higher order modulation format, such as pulse-amplitude modulation (PAM). A hybrid absorber configuration with thin depleted region which we newly employed successfully eliminates the space charge effect in the APD while maintaining high responsivity and operating speed. The fabricated APD shows an improved optical-input-electrical-output linearity for an optical input power over -8 dBm, and an optical receiver with this APD achieves both an error-free operation with a KP4 FEC and a high sensitivity of -17 dBm against a 28-Gbaud PAM4 signal.

Dexmedetomidine suppresses long-term potentiation in the hippocampal CA1 field of anesthetized rats.

PURPOSE: The aim of this study was to evaluate the effect of dexmedetomidine (DEX) on hippocampal synaptic activity in vivo. METHODS: The adult rats used for this study received a intraperitoneal bolus injection of 3, 10, 30, or 100 µg/kg of DEX or an equivalent volume of saline. Electrophysiological recording of the hippocampal CA1 region was initiated 20 min after drug administration. The results are expressed as the percentages of the population spike amplitude measured just before high-frequency stimulation (HFS). The electrophysiological data were analyzed with an area under the curve (AUC) of 10-60 min after HFS. Moreover, to investigate the sedative dose of DEX in rats, we recorded the duration of loss of spontaneous movement after the administration of each dose of DEX. RESULTS: Intraperitoneal administration of DEX at doses of 30 and 100 µg/kg induced a range of sedative effects. The AUC measurements were significantly lower in the 30 and 100 µg/kg groups than in those injected with vehicle (vehicle: 8.81 ± 0.49, n = 7; DEX 30 µg/kg: 6.02 ± 0.99, n = 6; DEX 100 µg/kg: 5.10 ± 0.43, n = 5; P < 0.05). CONCLUSION: The results of our in vivo study reveal that sedative doses of DEX impaired the induction of hippocampal long-term potentiation (LTP). These findings may signify a causal link between DEX-induced sedative action and hippocampal LTP suppression, providing a better understanding of the mechanisms underlying the DEX-induced sedative and/or amnestic effect.

Neonatal exposure to sevoflurane causes significant suppression of hippocampal long-term potentiation in postgrowth rats.

BACKGROUND: The inhaled anesthetic sevoflurane is commonly used for neonates in the clinical setting. Recent studies have indicated that exposure of neonatal rodents to sevoflurane causes acute widespread neurodegeneration and long-lasting neurocognitive dysfunction. Although acute toxic effects of sevoflurane on cellular viability in the hippocampus have been reported in some studies, little is known about the effects of neonatal sevoflurane exposure on long-term hippocampal synaptic plasticity, which has been implicated in the processes of learning and memory formation. Our study is the first to examine the long-term electrophysiological impact of neonatal exposure to a clinically relevant concentration of sevoflurane. METHODS: On postnatal day 7, rats were exposed to sevoflurane (1% or 2% for 2 hours) with oxygen. To eliminate the influence of blood gas abnormalities caused by sevoflurane-induced respiratory suppression, a group of rats were exposed to a high concentration of carbon dioxide (8% for 2 hours) to duplicate respiratory disturbances caused by 2% sevoflurane exposure. RESULTS: Exposure of neonatal rats to 2% sevoflurane for 2 hours caused significant suppression of long-term potentiation (LTP) induction in the postgrowth period. There was no significant difference between the control group and the CO2-exposed group in LTP induction, indicating that sevoflurane-induced LTP suppression was not caused by blood gas abnormalities. CONCLUSION: Our present findings indicate that neonatal exposure to sevoflurane at a higher concentration can cause alterations in the hippocampal synaptic plasticity that persists into adulthood.

[Anesthetic and perioperative management of a patient with uncontrolled thyrotoxicosis undergoing coronary artery bypass grafting surgery].

Uncontrolled hyperthyroidism is a risk factor of perioperative thyrotoxic crisis. We report a case of a 61-year-old woman with thyrotoxicosis diagnosed with unstable angina pectoris. She needed to have an early scheduled coronay artery bypass grafting surgery, because percutaneous intervention for the left main coronary artery in support of intra-aortic balloon pumping (IABP) resulted in failure. Tachycardia and hyperthermia were observed at admission to the ICU, and hemodynamic parameters suggested high-output heart failure. Preoperative management using antithyroid drug, inorganic iodine, corticosteroid and propranolol stabilized her hemodynamic condition, and then CABG was performed on ICU day 3. Intraoperative and postoperative use of landiolol, a short acting beta blocker, was useful for maintaining hemodynamic stability. Surgery was uneventfully completed and she was extubated on postoperative day 1 following IABP withdrawal. Appropriate preoperative management and perioperative use of the short acting beta blocker were useful for management of the patient with uncontrolled hyperthyroid state.

Silica-based, compact and variable-optical-attenuator integrated coherent receiver with stable optoelectronic coupling system.

We demonstrate a compact and variable-optical-attenuator (VOA) integrated coherent receiver with a silica-based planar lightwave circuit (PLC). To realize the compact receiver, we integrate a VOA in a single PLC chip with polarization beam splitters and optical 90-degree hybrids, and employ a stable optoelectronic coupling system consisting of micro lens arrays and photodiode (PD) subcarriers with high-speed right-angled signal lines. We integrate a VOA and a coherent receiver in a 27x40x6 mm package, and successfully demodulate a 128-Gbit/s polarization division multiplexed (PDM) quadrature phase shift keying (QPSK) signal with a VOA-assisted wide dynamic range of more than 30 dB.

Neonatal administration with dexmedetomidine does not impair the rat hippocampal synaptic plasticity later in adulthood.

BACKGROUND AND OBJECTIVE: The use of dexmedetomidine (DEX), a selective alpha-2 agonist, in pediatric practice is expanding as a result of its desirable properties. To clarify the long-term neurological consequences of neonatal administration of DEX, we investigated the long-term effects of neonatal administration of DEX on hippocampal synaptic activity. METHODS: The rat pups received a bolus intraperitoneal injection of either 5 or 10 µg·kg(-1) DEX, or an equivalent volume of vehicle on postnatal day 7 (P7). Nine weeks after administration, evoked potentials (population spike, PS) and long-term potentiation (LTP) in the hippocampal CA1 region of rats were studied in vivo. RESULTS: Dexmedetomidine had a considerable sedative effect at these doses with little respiratory depression on P7. Nine weeks after administration of DEX, the amplitude of PS in the two treated groups was similar to that in the control group. DEX-treated rats showed no impairment in the induction of LTP. Furthermore, the response in PS to the paired stimuli was not impaired by neonatal administration of DEX. CONCLUSION: These findings demonstrate that a single administration of DEX to rats on P7 preserves hippocampal synaptic plasticity as well as synaptic transmission later in life. In view of the some evidence that have demonstrated the permanent detrimental impact of commonly used anesthetics on neurological outcomes after neonatal exposure, our findings may suggest the relative safety of DEX administered as a sedative agent to neonatal animals with regard to the development of hippocampal synaptic functions.

Neural Schrödinger Equation: Physical Law as Deep Neural Network.

We show a new family of neural networks based on the Schrödinger equation (SE-NET). In this analogy, the trainable weights of the neural networks correspond to the physical quantities of the Schrödinger equation. These physical quantities can be trained using the complex-valued adjoint method. Since the propagation of the SE-NET can be described by the evolution of physical systems, its outputs can be computed by using a physical solver. The trained network is transferable to actual optical systems. As a demonstration, we implemented the SE-NET with the Crank-Nicolson finite difference method on Pytorch. From the results of numerical simulations, we found that the performance of the SE-NET becomes better when the SE-NET becomes wider and deeper. However, the training of the SE-NET was unstable due to gradient explosions when SE-NET becomes deeper. Therefore, we also introduced phase-only training, which only updates the phase of the potential field (refractive index) in the Schrödinger equation. This enables stable training even for the deep SE-NET model because the unitarity of the system is kept under the training. In addition, the SE-NET enables a joint optimization of physical structures and digital neural networks. As a demonstration, we performed a numerical demonstration of end-to-end machine learning (ML) with an optical frontend toward a compact spectrometer. Our results extend the application field of ML to hybrid physical-digital optimizations.

Neonatal isoflurane exposure disturbs granule cell migration in the rat dentate gyrus.

It has been reported that neonatal isoflurane exposure causes behavioral abnormalities following neurodegeneration in animals and gamma-aminobutyric acid type A (GABAA) receptor activation during the synaptogenesis is considered to be one possible trigger. Additionally, the inhibitory effect of excitatory GABAA receptor signaling on the granule cell (GC) migration in the neonatal rat dentate gyrus (DG) was reported in a febrile seizure model. Then, we hypothesized that neonatal isoflurane exposure, which activates GABAA receptor, causes GC migration disturbances in the neonatal rat. Rat pups were injected with 5-bromo-2'-deoxyuridine (BrdU) and divided into five treatment groups, and double immunofluorescent staining targeting BrdU and homeobox prospero-like protein 1 (Prox1) was performed to examine the localization of BrdU/Prox1 colabeled cells, and then the GC migration was assessed. As a result, we found that the ectopic migration of GC after 2% isoflurane exposure on postnatal day 7 significantly increased after P21. The number of hilar ectopic GCs was influenced by the concentration of isoflurane and the exposure day but not by carbon dioxide exposure. Our main finding is that neonatal isoflurane anesthesia disturbs the migration of GCs in the rat DG, which may be one possible mechanism underlying the neurotoxicity following neonatal isoflurane anesthesia.

Physical deep learning with biologically inspired training method: gradient-free approach for physical hardware.

Ever-growing demand for artificial intelligence has motivated research on unconventional computation based on physical devices. While such computation devices mimic brain-inspired analog information processing, the learning procedures still rely on methods optimized for digital processing such as backpropagation, which is not suitable for physical implementation. Here, we present physical deep learning by extending a biologically inspired training algorithm called direct feedback alignment. Unlike the original algorithm, the proposed method is based on random projection with alternative nonlinear activation. Thus, we can train a physical neural network without knowledge about the physical system and its gradient. In addition, we can emulate the computation for this training on scalable physical hardware. We demonstrate the proof-of-concept using an optoelectronic recurrent neural network called deep reservoir computer. We confirmed the potential for accelerated computation with competitive performance on benchmarks. Our results provide practical solutions for the training and acceleration of neuromorphic computation.

[Coagulation profiles following donor hepatectomy and implications for the risk of epidural hematoma associated with epidural anesthesia].

BACKGROUND: Continuous epidural analgesia has become an accepted technique used in laparotomy including liver resections. Although American Society of Regional Anesthesia and Pain Medicine recommends that epidural catheter be removed with prothrombin time-international normalized ratio (PT-INR) less than 1.5, it is possible that liver surgery causes coagulation disturbances. We examined the postoperative changes in coagulation profiles of living liver donors to elucidate whether hepatectomy increases the risk of epidural hematoma related to removal of epidural catheters or not. METHODS: From January 2007 to October 2009, 42 living liver related transplantations were performed in Hokkaido University Hospital. We reviewed the donor data including PT-INR obtained during perioperative days [preoperative, immediately postoperative, postoperative day 1, 3 and 7] and epidural catheter-related-complications, retrospectively. RESULTS: While in all donors values of PT-INR obtained during preoperative periods were within normal limits, 14 donors had a PT-INR over 1.5 during postoperative periods. There was no epidural hematoma case in this study. CONCLUSIONS: Our study suggested that hepatectomy increases the risk of epidural hematoma related to removal of epidural catheters, even in the living liver transplant donors with normal liver function.

Channel-allocation-adaptive WDM signal observation based on sequential ultrafast field sampling.

A novel technology for simultaneous WDM signal monitoring is presented based on ultrafast field sampling. Its flexibility regarding channel allocation and/or channel bandwidth is unique and attractive, as is its ultrafast nature. Two- and four-channel WDM signals, with the total bandwidth of 800 GHz, are successfully discriminated and observed with the proposed scheme.

Development of the reverse passive latex agglutination method for the detection and quantification of the genus Nitrospira in the wastewater treatment process.

This report describes a new immunological method for the detection and quantification of Nitrospira populations using the reverse passive latex agglutination (RPLA). The numbers of the genus Nitrospira have been quantified only by molecular biological techniques such as FISH and quantitative PCR to date. Using high-density latex particles and a specific polyclonal antibody, Nitrospira populations in the wastewater treatment process were quantified in the shortest 4 h of incubation. The minimum detectable number of Nitrospira cells was 7.0x10(5) (log(10) 5.85) cells/ml. It is thought that the RPLA method can quantify Nitrospira populations more simply, economically, and speedily than molecular biological techniques or the culture method, because this procedure has a simple protocol and does not require the use of specialized equipment, expensive reagents, or technical skill. Therefore it is applicable for use in the everyday control and maintenance of water quality in wastewater treatment facilities where equipment is not sufficient or in the field.

Influence of nitrous oxide on granule cell migration in the dentate gyrus of the neonatal rat.

For several decades, the neurotoxicities of anesthetics to the developing brain have been reported by many researchers focusing on various phenomena such as apoptosis, neurodegeneration, electrophysiological aberrations, and behavioral abnormalities. According to these reports, signals via N-methyl-D-aspartate receptors (NMDA-r) and/or γ-aminobutyric acid type A receptors (GABAA-r) are implicated in the anesthetic neurotoxicity. On the other hand, during brain development, NMDA-r and GABAA-r are also recognized to play primary roles in neural cell migration. Therefore, anesthetics exposed in this period may influence the neural cell migration of neonates, and increase the number of hilar ectopic granule cells, which are reported to be a cause of continuous neurological deficits. To examine this hypothesis, we investigated immunohistochemically granule cell distribution in the hippocampal dentate gyrus of Wistar/ST rats after nitrous oxide (N2O) exposure. At postnatal day (P) 6, 5-bromo-2'-deoxyuridine (BrdU) was administered to label newly generated cells. Then, rats were divided into groups (n = 6 each group), exposed to 50% N2O at P7, and evaluated at P21. As a result, we found that ectopic ratios (ratio of hilar/total granule cells generated at P6) were decreased in rats at P21 compared with those at P7, and increased in N2O exposed rats for over 120 min compared with the other groups. These results suggest that 50% N2O exposure for over 120 min increases the ratios of ectopic granule cells in the rat dentate gyrus.