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Hardware acceleration of deep learning using analog non-volatile memory (NVM) requires large arrays with high device yield, high accuracy Multiply-ACcumulate (MAC) operations, and routing frameworks for implementing arbitrary deep neural network (DNN) topologies. In this article, we present a 14-nm test-chip for Analog AI inference--it contains multiple arrays of phase change memory (PCM)-devices, each array capable of storing 512 x 512 unique DNN weights and executing massively parallel MAC operations at the location of the data. DNN excitations are transported across the chip using a duration representation on a parallel and reconfigurable 2-D mesh. To accurately transfer inference models to the chip, we describe a closed-loop tuning (CLT) algorithm that programs the four PCM conductances in each weight, achieving

Neuromorphic computing using analog non-volatile memory (NVM) devices has been the subject of various studies due to its potential ability to achieve extremely low power consumption less than that of traditional von Neumann architecture. However, using NVM devices, such as phase change memory (PCM) and resistive-RAM devices, presents various challenges, such as limitations in the number of conductance steps and device variability resulting from process variation and electro/thermo-dynamics. Limitations in the number of conductance steps and device variability could reduce the accuracy of neural network training. It is necessary to quantitatively analyze the effect of the number of conductance steps and synaptic device variability on the accuracy of neural network training and assess requirements for NVM devices to make NVM-based neuromorphic computing successful. We conducted the analysis using simulations focusing on a spiking neural network (SNN) based restricted Boltzmann machine (RBM) with PCM devices using the PCM-refresh method. The results of our quantitative simulation, which used the MNIST dataset, showed that having more than 500 conductance steps achieves comparable performance to that when there are more than 1000 conductance steps. We also found that less than 10% conductance update variation in the synaptic devices is required to achieve the comparable accuracy with the no variation case. These results can provide guidelines for designing and optimizing a synaptic device for realizing NVM-based neuromorphic computing.

Dense crossbar arrays of non-volatile memory (NVM) devices represent one possible path for implementing massively-parallel and highly energy-efficient neuromorphic computing systems. We first review recent advances in the application of NVM devices to three computing paradigms: spiking neural networks (SNNs), deep neural networks (DNNs), and ‘Memcomputing’. In SNNs, NVM synaptic connections are updated by a local learning rule such as spike-timing-dependent-plasticity, a computational approach directly inspired by biology. For DNNs, NVM arrays can represent matrices of synaptic weights, implementing the matrix–vector multiplication needed for algorithms such as backpropagation in an analog yet massively-parallel fashion. This approach could provide significant improvements in power and speed compared to GPU-based DNN training, for applications of commercial significance. We then survey recent research in which different types of NVM devices – including phase change memory, conductive-bridging RAM, filamentary and non-filamentary RRAM, and other NVMs – have been proposed, either as a synapse or as a neuron, for use within a neuromorphic computing application. The relevant virtues and limitations of these devices are assessed, in terms of properties such as conductance dynamic range, (non)linearity and (a)symmetry of conductance response, retention, endurance, required switching power, and device variability.

A fully silicon-integrated restricted Boltzmann machine (RBM) with event-driven contrastive divergence (eCD) algorithm is implemented using novel stochastic leaky integrate-and-fire (LIF) neuron circuits and 6-transistor/2- PCM-resistor (6T2R) unit cells on 90-nm CMOS technology. A bidirectional asynchronous spiking signaling scheme over an analog-weighted phase change memory (PCM) crossbar enables spike-timing-dependent plasticity (STDP) as a local weight update rule. This results in concurrent massively- parallel neuronal computation for low-power on-chip training and inference. Experimental image classification using 100 handwritten digit images from the MNIST database demonstrates 92% training accuracy. SPICE simulation abstracted from the fabricated design indicates 8.95 power. A projection to 28-nm technology gives 5.39 pJ per synaptic operation.

Neuromorphic circuits with nonvolatile memory crossbar arrays can train and inference neural networks in a highly power-efficient manner, which can be a solution to overcome the von Neumann bottleneck. This paper proposes a scalable multi-core spiking neuromorphic system architecture that can support a large-scale multi-layer neural network larger than a network supported by a computing system with a single neuromorphic circuit core. To simplify the inter-core communication, neuromorphic cores communicate only by sending and receiving spikes. Deep networks can be easily formed on this architecture by connecting multiple cores. The neuromorphic cores are trained on-chip by backpropagation, which is a well-known and sophisticated algorithm for training neural networks in software. We made modifications to the traditional backpropagation algorithm to propagate errors and update weights by spikes on the spiking neuromorphic cores of a computing system using our architecture. The proposed algorithm was evaluated by an spike event-based neuromorphic circuit simulator using three datasets. Cancer1 and Thyroid1 were used for a small network evaluation, which results showed better test error than previous studies, and MNIST was used to evaluate a large realistic neural network.

Phase change memory (PCM) is arguably one of the most promising non-volatile memories which can be used in neuromorphic applications. When we use PCM as analog synaptic elements, non-ideality impact should be carefully taken into account. In this paper, we investigate the impact of such non-ideality items as nonlinear weight update and resistance drift on training accuracy in a spiking restricted Boltzmann machine (RBM). In addition to ideal PCM model, actual measurement-based PCM characteristics is used for this study. The resistance drift affects training accuracy, especially in a widely distributed read interval time caused by spatial and temporal sparse spike activities during training in spiking RBM. Our simulation results show that the training accuracy worsens with the increase of the weight-update nonlinearity or the resistance-drift coefficient. However, the results also suggest we can expect more than 8.95% improvement in training accuracy. This potential improvement will be possible if we use linearity-improved confined PCM cells whose median resistance drift coefficient is 0.005, compared to the resistance drift coefficient of more than 0.02 in typical existing PCM cells.

In extremely energy-efficient neuromorphic computing using analog non-volatile memory (NVM) devices, device variability arises due to process variation and electro/thermo-dynamics of NVM devices, such as phase change memory and resistive-RAM. Thus, for realizing NVM-based neuromorphic computing, it is important to quantitatively analyze the impact of synaptic device variability on neural network training accuracy and assess requirements for NVM devices. We investigated the analysis using simulations focusing on a spiking neural network (SNN)-based restricted Boltzmann machine (RBM). MNIST dataset simulation results revealed that more than 500 steps of conductance achieve comparable performance to the previous study of software-based simulation on SNN-based RBM. We also observed that at least a less than 10% of variation in conductance update for each synaptic device is required for achieving comparable performance to the result with no variation. These results provide baselines for designing and optimizing the characteristics of NVM devices.

This work demonstrates the first fabricated 1 Mb nonvolatile TCAM using 2-transistor/2-resistive-storage (2T-2R) cells to achieve >10× smaller cell size than SRAM-based TCAMs at the same technology node. The test chip was designed and fabricated in IBM 90 nm CMOS technology and mushroom phase-change memory (PCM) technology. The primary challenge for enabling reliable array operation with such aggressive cell is presented, namely, severely degraded sensing margin due to significantly lower ON/OFF ratio of resistive memories (~102 for PCM) than that of traditional MOSFETs (>105 ). To address this challenge, two enabling techniques were developed and implemented in hardware: 1) two-bit encoding and 2) a clocked self-referenced sensing scheme (CSRSS). In addition, the two-bit encoding can also improve algorithmic mapping by effectively compressing TCAM entries. The 1 Mb chip demonstrates reliable low voltage search operation (VDDmin ~750 mV) and a match delay of 1.9 ns under nominal operating conditions.

We report on the spurious suppression effect in low-microwave power transmitters by high temperature superconducting (HTS) bandpass filters (BPFs) which are promising for devices requiring BPFs with high-frequency selectivity. Some of the major issues on the power BPFs with HTS planar circuits for wireless communication applications are reviewed. As a case study for the HTS filter and its spurious suppression effect, this paper describes an example of the measured power spectrum density (PSD) on the suppression effect by one of our developed power BPFs with YBCO films for the 5 GHz band. It was designed with equivalent cascade resonators of 16 poles. We demonstrated the effect by HTS power filter in a power amplifier for the 5 GHz band.

Lanthanum-modified lead zirconate titanate and lead zirconate titanate epitaxial films with (100) and (111) orientations were grown respectively on (100) and (111) niobium, lending conductivity to strontium titanate through chemical solution deposition. This study investigated changes in the ordinary and extraordinary refractive index no and ne induced in these films by an electric field using the prism-coupling method. In the (100) epitaxial PZT 30/70 film, anisotropic electro-optic effects arise from the Pockels effect. The isotropic electro-optic effect, which is no = ne , was achieved on (100) epitaxial PLZT 8/65/35 and PZT 70/30 films.

Electrooptic (EO) properties and propagation losses of the lead zirconate titanate (PZT) films grown on silicon (Si) substrates have been investigated. PZT films were prepared on Si substrates by chemical solution method. Refractive index changes and propagation losses of PZT films were evaluated by prism coupling method. A (100)-oriented 8.9-µm-thick epitaxial PZT film grown on a Si substrate with strontium ruthenium oxide/ceria/yttria-stabilized zirconia (SRO/CeO2/YSZ) epitaxial buffer layer was found to have large EO effect and very low propagation loss. Propagation of an infrared light with a wavelength of 1550 nm into a PZT film on Si substrate was successfully confirmed.

In the epitaxial (Pb1−x , La x )(Zr1−y , Ti y )1−x/4O3 [PLZT] films, the composition dependence of the refractive index and electric-optic (EO) coefficient near the morphotropic phase boundary (MPB) composition was investigated. A (100/001)-oriented PLZT 10/65/35 epitaxial film is found to have isotropic optical properties. Highly (100/001)-oriented epitaxial PLZT films with compositions near the MPB on Nb–SrTiO3 substrates were fabricated using a sol–gel process. The value of birefringence from 4 × 10−3 to 5 × 10−4 in PLZT epitaxial film was smaller than that of lithium niobate single crystal. The refractive index decreases with increasing lanthanum content. The difference in the refractive index obtained depended upon the lanthanum content up to 2%. This value is adequate for fabrication of waveguide structures. The EO coefficient of PLZT 9/65/35 thin films was 45 pm/V, which is larger than that of lithium niobate single crystal. A very small polarization dependence of the EO coefficient was also observed.

We demonstrate a neuromorphic core with 64k-cell phase change memory (PCM) synaptic array (256 axons by 256 dendrites) with in-situ learning capability. 256 configurable on-chip neuron circuits perform leaky integrate and fire (LIF) and synaptic weight update based on spike-timing dependent plasticity (STDP). 2T-1R PCM unit cell design separates LIF and STDP learning paths, minimizing neuron circuit size. The circuit implementation of STDP learning algorithm along with 2T-1R structure enables both LIF and STDP learning to operate asynchronously and simultaneously within the array, avoiding additional complication and power consumption associated with timing schemes. We show hardware demonstration of in-situ learning with large representational capacity, enabled by large array size and analog synaptic weights of PCM cells.

Purpose The external traction hooks of the intraoral splint used in the rigid external distraction (RED) system for maxillary distraction osteogenesis interfere with the surgical procedures. The purpose of this study is to introduce an innovative splint fixation method for maxillary distraction osteogenesis with Locking Attachments and evaluate their advantages, such as reduction of operating time compared with the traditional intraoral splint method. Patients and Methods Retrospective comparison of operative times of maxillary Le Fort I osteotomy procedures was carried out with the traditional protocol using the intraoral splint cemented to the maxillary dentition (n = 14), and a removable intraoral splint that is inserted postsurgically (n = 14). Operative procedure times were compared and analyzed statistically using the data extracted from the surgical records. Results There were no complications inserting the removable splint postsurgically, including pain, discomfort, or time-consuming procedure. Stable and secure splint fixation was obtained before the distraction procedure and the desired treatment goals were obtained in all patients. The total operative procedure times were significantly reduced in the Locking Attachments group by 24% to 41% (approximately 65 minutes) compared with earlier operations involving the conventional splints (P Conclusions Maxillary distraction osteogenesis with the Locking Attachments is a highly effective fixation approach to manage severe hypoplastic maxilla, eliminating lip constraints resulting from scarring and allowing for easier, more deliberate and careful dissection. The use of the Locking Attachments is reliable in craniofacial surgery and has proved to be advantageous in the reduction of the operating time and surgical risks.

The electrooptic (EO) properties of light propagated through lead zirconate titanate (PZT) films prepared on silicon (Si) substrates were successfully evaluated. Polycrystalline, {101}-oriented and {100}-oriented epitaxial PZT films with a thickness of approximately 2 µm were prepared on various types of Si substrate by chemical solution deposition. The anisotropic EO effect was observed in the polycrystalline and {101}-oriented PZT films. The in-plane and out-of-plane refractive indices of the {100}-oriented epitaxial PZT films changed with the type of substrate. The EO effect of the {100}-oriented epitaxial PZT film grown on a Si substrate was found to be more isotropic than those of the polycrystalline and {101}-oriented PZT films. The largest EO coefficients (re=54 pm/V and rc=60 pm/V) were obtained in the {101}-oriented PZT film on the Si substrate.

日本歯周病学会会員の現在の喫煙状況および喫煙に関する考えを把握するために評議員を対象として質問調査を行なった。質問票を郵送し回答の上同封の封筒による返送を求め, その結果を分析した。回答が返送されたのは231名中145名で返送率は63%であった。年齢は40—50代が多く74%を占めた。所属は大学教員68%, 開業医25%, 勤務医4%, その他3%であった。喫煙状況については現在喫煙者13%, 元喫煙者39%, 非喫煙者48%であった。ニコチンの依存性については90%が肯定的であった。多くの疾患に喫煙が関連していると認識されており, 喫煙と歯周病との関連については94%が肯定的な考えを示した。歯科医師は禁煙指導をすべきという意見に80%以上の賛成が得られたが, 一方で禁煙指導の知識は十分とは言えないとする回答が43%であった。歯周病専門医の資格要件を非喫煙者とすることに賛成が79%を占めた。臨床医の約半数が患者の喫煙状況についての把握をしていた。喫煙状況は初診時に確認していることが多かった。また, 80%が重症な歯周病患者に喫煙者が多いと感じており, 88%が喫煙者は歯周治療で治りにくいと感じていることが示された。以上より, 回答が得られた集団では喫煙の歯周病への為害性を認識しており, 現在の喫煙率は比較的低いことが示された。また, 歯周病患者への禁煙指導の必要性を認識しつつも, 指導のための知識が不足している可能性が示唆された。

Epitaxial Pb(Mg1/3Nb2/3)O3-PbTiO3 (PMN-PT) thin films for electrooptic applications were fabricated on a Si substrate using buffer layers. The PMN-PT/SrRuO3/SrTiO3/(La,Sr)CoO3/CeO2 /YSZ/Si hetrostructure was fabricated by pulsed laser deposition. A PMN-PT thin film with a thickness of 2μm was successfully deposited. The optical characteristics of PMN-PT epitaxial film were measured by prism coupling method. The morphology of the PMN-PT films was drastically improved by introducing a mask between the target and substrate during the deposition. The PMN-PT thin film showed a columnar structure, where the width of each column was approximately 180nm. A refractive index of 2.48 with zero bias voltage was obtained for the epitaxial PMN-PT thin film using the prism coupler method.

Post-traumatic hyperplasia of the mandibular condyle is a relatively rare condition associated with facial asymmetry accompanied by mandibular deviation and malocclusion. We report a case of right condylar hyperplasia that occurred after a traffic-related injury. The patient was a 32-year-old man who presented with asymmetry of the lower part of the face and malocclusion with mandibular deviation to the left. Radiographic examination revealed marked enlargement of the right mandibular condyle. Resection of the lesion was performed, and the remaining portion of the condyle was trimmed and contoured. Postoperative CT scans revealed new bone formation anterior to the condyle. Although there is a risk of recurrence, facial symmetry and good occlusion have been maintained for 4 years after operation.

Lead lanthanum zirconate titanate (PLZT) film with an array of air-holes was successfully fabricated on a platinum-deposited (0 0 1) magnesium oxide substrate using a sol–gel method with a resist mold. A PLZT precursor solution was cast into a mold with resist pillars patterned using electron-beam lithography. After removing the resist pillars and applying a firing process, a PLZT ceramic film with air-holes was obtained. The patterned PLZT film was grown epitaxially on the substrate. Reflection peaks were also observed by optical measurement of PLZT film with a hexagonal array of air-holes. The frequency range of the reflection peaks coincided with that of the calculated photonic band structures. We consider that this periodic structure and process are suitable for preparing tunable photonic crystals.

The aim of this study was to develop a novel cultured mucosal membrane that was facile to prepare and easy to handle, and that could be applied to mucosal defects in the oral cavity. Human oral keratinocytes and fibroblasts were prepared from the oral mucosa. We made the following two types of cultured mucosal cell sheets: a monolayer sheet of keratinocytes cultured on a collagen membrane (K-S) and a double-layered sheet of keratinocytes and fibroblasts on a collagen membrane (KF-S). A collagen membrane was used as a control. Each type of sheet was transplanted onto dorsal skin defects of nude mice. The wound area was measured for the assessment of wound contraction and a specimen was harvested for histologic evaluation 1 week and 4 weeks after grafting. Wound contraction was minimal with KF-S grafts. Although histologic examination showed normal differentiation of the epithelium in all graft types, the involucrin expression pattern of KFS was most similar to that of normal epithelium. These results indicate that a double-layered sheet of keratinocytes and fibroblasts cultured on a collagen membrane may facilitate epithelial healing and prevent wound contraction.

Considerable progress has recently been made in nose correction techniques in the field of cleft lip surgery. However, surgical repair alone cannot solve the multiple problems associated with wide clefts of the lip and severe deformity of the nose. Presurgical nasoalveolar molding (PNAM) technique for patients with clefts was described by Grayson et al.(1999). This treatment's objectives are non-surgical correction of the nose and alveolar processes, including repositioning the deformed alar cartilages, lengthening of deficient columella, and reduction of the alveolar cleft gap by using Hotz-type palatal molding plates with acrylic nasal stents and surgical adhesive tapes that are applied to the cheeks during the neonatal period. In this paper, we describe our experience with primary management using PNAM in 12 infants with unilateral cleft lip and palate. All cases showed elongation of the columella and reduction of the alveolar cleft gap before primary surgical repair of the lip and nose, which suggested that PNAM is useful for promoting presurgical morphological improvement.

Cheilitis granulomatosa (CG) is a chronic inflammatory disorder of unknown etiology. Various types of symptomatic therapy have been used to manage CG, with varying success. Recently, CG has been considered part of a new concept of disease referred to as “orofacial granulomatosis”. We report on a 40-year-old woman with persistent CG of the upper and lower lips that was successfully managed by local injection of dexamethasone. Treatment consisted of local injection of 4 mg dexamethasone diluted with lidocaine hydrochloride, administered at intervals of 1 to 4 weeks over the course of 7 months. After 5 months of treatment, both the upper and lower lips of the patient appeared normal. On follow-up at 1 year, the patient's lips remained normal in shape and contour.

Purpose: We present a 17-year follow-up of an unusual patient with median cleft of the lower lip, mandible, and tongue with a flexion contracture. Conclusion: Timing of the mandibular reconstruction needs to take into account growth of the mandible and masticatory function. In this case, fixation of the mandible performed at the age of 6 years 6 months and reconstruction carried out at 7 years 8 months of age resulted in satisfactory occlusion and masticatory function.

A new type of cultured mucosa was developed as a mucosal substitute. This composite cultured oral mucosa (CCOM) was composed of (1) a lamina propria in which fibroblasts were embedded in contacted collagen gel and honeycomb structured collagen sponge and (2) stratified epithelial cell layers on the surface of the cultured lamina propria. CCOM had a well-stratified and differentiated epithelial cell layer, and its involucrin and laminin expression resembled that of normal oral mucosa. Desmosomes were recognizable with transmission electron microscopic examination. In the lamina propria, contracted collagen gel had pooled away from the sponge wall, leaving a sparse structure inside the collagen sponge. Transplantation of CCOM to nude mice was performed by creating full-thickness wound and then applying CCOM (n = 12). Murine skin allograft (n = 4) and no-graft conditions (n = 5) served as controls. The mice were sacrificed for histological evaluation and assessed for wound contraction 28 days after transplantation. The epithelium of the CCOM-treated group had five to 10 cell layers, and the dermis contained many fibroblasts and a large amount of collagen bundles. The wound contraction of the CCOM-treated group was statistically less than that of the no-graft group. These results indicate that CCOM has barrier functions against various stresses and can induce a fibrovascular ingrowth from the surrounding wound bed, and that CCOM could be applied in a clinical setting.

We had participated in the charitable operation for the patients with cleft lip and palate and technical suidance in Vietnam in 1998 for 2 weeks. The project was a part of the activities of the Japanese Cleft Palate Foundation, which were performed as part of the Official Development Assistance (ODA) of Japan, and was aided by state subsidy of the Ministry of Posts and Telecommunications, the Ministry of Foreign Affairs and the Ministry of Education and so on. Our team consisted of members of Tokyo Dental College, Iwate Medical University, Dalhousie University, and our university. The hospital we visited was Odonto-Maxillo-Facial Center in Ho Chi Min City, which had 7 clinical departments, 36 dental units, 60 beds in ward, and 75 doctors in total. This hospital dealt with all kinds of disease in connection with oral and maxillo-facial area including dental caries, periodontal disease, maxillo-facial injuries, and maxillo-facial anomalies. Forty-five patients with cleft lip and palate were operated on during our stay in Vietnam. The age of these patients was higher than that in medical advanced countries because of economic problems and insufficient medical institutions. In some cases, surgery was performed in collaboration with local doctors, which means technical suidance leads to more effective treatment.

This paper reports a fabrication process of pulse wave sensor and detection result of pulse wave using the ring-shaped sensor, which has ring-shaped photodiode. An LED is located at the center of a photodiode. This structure achieved noninvasive detection of the pulse wave and does not have the directivity. Therefore, the ring-shaped sensor is expected to reduce noises of body motion (motion artifacts). We evaluated the characteristics of the photodiode and detected the pulse wave using the fabricated sensor. As a result, the ring-shaped sensor can detect the pulse wave. Furthermore, detection of the pulse wave can be applied to measure the pulse wave velocity (PWV).

Epitaxial (Pb 1-x , La x )(Zr 1-y , Ti y ) 1-x/4 O 3 [PLZT] films composition dependence of the refractive index and electric-optic (EO) coefficient near the morphotropic phase boundary (MPB) composition was investigated. A (100/001)-oriented PLZT 9/65/35 epitaxial film is found to have isotropic optical properties. Highly (100/001)-oriented epitaxial PLZT films with compositions near the MPB on Nb-SrTiO 3 substrates were fabricated using a sol-gel process. The refractive index decreases with increasing lanthanum content. The difference in the refractive index obtained depended upon the lanthanum content up to 2 %. This value is adequate for fabrication of waveguide structures. The value of birefringence from 4×10 -3 to 5×10 -4 in PLZT epitaxial film was smaller than that of lithium niobate single crystal. The EO coefficient of PLZT 9/65/35 thin films was 45 pm/V, which is larger than that of lithium niobate single crystal. A very small polarization dependence of the EO coefficient was also observed.