TCP/IP スタック ニ オケル チェックサムケイサン ノ GPU オフロード ニ ヨル セイノウ コウジョウ シュホウ

Ethernet Jumbo Frameの登場により、特にデータセンタなどの閉じたネットワーク環境において送受信されるフレームサイズが増大している。フレームサイズの増大に伴い、TCP/IPスタックにおけるチェックサム計算に要するCPU負荷が増大する。本報告では、大きな帯域幅のメモリをもつGraphics Processing Unit (GPU)にチェックサム計算をオフロードすることにより、CPU負荷を削減し、データ転送スループットを向上させる手法を提案する。具体的には、CPU-GPU間のパケット転送効率を向上させるためのパケットキューイング手法、及び、GPU上で複数のパケットを同時処理するためのGPUマルチプロセッサを用いたパケット分散処理手法の2つを提案する。ユーザランドで動作するチェックサム計算の簡易実装により性能を評価し、チェックサム計算のGPUオフロードによって、データ転送性能が最大で13%向上することを示す。The size of ethernet frames is becoming larger and larger due to the utilization of Ethernet Jumbo Frame option, especially in closed network environment such as data center networks. Increasing frame size would cause the large overhead for checksum calculation in TCP /IP protocol processing, that increase the CPU load. In this report we propose the scheme for decreasing CPU load and improving data transmission throughput by offloading checksum calculation to Graphics Processing Unit (GPU). Our scheme consists of the following two methods: packet queueing method to improve the packet transmission throughput between CPU and GPU, and the packet processing method exploiting the advantage of GPU's multiprocessor architecture. We evaluate the performance of the proposed scheme by simple experiments using the user-land implementation and confirm that the proposed scheme can improve the TCP data transmission throughput by 13 %, that is almost the same as the case when the checksum calculation is canceled.坪内佑樹, 長谷川剛, 谷口義明, 中野博隆, 松岡茂登「TCP/IPスタックにおけるチェックサム計算のGPUオフロードによる性能向上手法」『電子情報通信学会技術研究報告』Vol.113, No.244、pp.67-72、電子情報通信学会、201

Time-dependent changes in the microenvironment of injured spinal cord affects the therapeutic potential of neural stem cell transplantation for spinal cord injury

Abstract Background The transplantation of neural stem/progenitor cells (NS/PCs) at the sub-acute phase of spinal cord injury, but not at the chronic phase, can promote functional recovery. However, the reasons for this difference and whether it involves the survival and/or fate of grafted cells under these two conditions remain unclear. To address this question, NS/PC transplantation was performed after contusive spinal cord injury in adult mice at the sub-acute and chronic phases. Results Quantitative analyses using bio-imaging, which can noninvasively detect surviving grafted cells in living animals, revealed no significant difference in the survival rate of grafted cells between the sub-acute and chronic transplantation groups. Additionally, immunohistology revealed no significant difference in the differentiation phenotypes of grafted cells between the two groups. Microarray analysis revealed no significant differences in the expression of genes encoding inflammatory cytokines or growth factors, which affect the survival and/or fate of grafted cells, in the injured spinal cord between the sub-acute and chronic phases. By contrast, the distribution of chronically grafted NS/PCs was restricted compared to NS/PCs grafted at the sub-acute phase because a more prominent glial scar located around the lesion epicenter enclosed the grafted cells. Furthermore, microarray and histological analysis revealed that the infiltration of macrophages, especially M2 macrophages, which have anti-inflammatory role, was significantly higher at the sub-acute phase than the chronic phase. Ultimately, NS/PCs that were transplanted in the sub-acute phase, but not the chronic phase, promoted functional recovery compared with the vehicle control group. Conclusions The extent of glial scar formation and the characteristics of inflammation is the most remarkable difference in the injured spinal cord microenvironment between the sub-acute and chronic phases. To achieve functional recovery by NS/PC transplantation in cases at the chronic phase, modification of the microenvironment of the injured spinal cord focusing on glial scar formation and inflammatory phenotype should be considered.</p

MRI characterization of paranodal junction failure and related spinal cord changes in mice.

The paranodal junction is a specialized axon-glia contact zone that is important for normal neuronal activity and behavioral locomotor function in the central nervous system (CNS). Histological examination has been the only method for detecting pathological paranodal junction conditions. Recently, diffusion tensor MRI (DTI) has been used to detect microstructural changes in various CNS diseases. This study was conducted to determine whether MRI and DTI could detect structural changes in the paranodal junctions of the spinal cord in cerebroside sulfotransferase knock-out (CST-KO) mice. Here, we showed that high-resolution MRI and DTI characteristics can reflect paranodal junction failure in CST-KO mice. We found significantly lower T1 times and significantly higher T2 times in the spinal cord MRIs of CST-KO mice as compared to wild-type (WT) mice. Spinal cord DTI showed significantly lower axial diffusivity and significantly higher radial diffusivity in CST-KO mice as compared to WT mice. In contrast, the histological differences in the paranodal junctions of WT and CST-KO mice were so subtle that electron microscopy or immunohistological analyses were necessary to detect them. We also measured gait disturbance in the CST-KO mice, and determined the conduction latency by electrophysiology. These findings demonstrate the potential of using MRI and DTI to evaluate white matter disorders that involve paranodal junction failure

コウシジョウ ニ ハイチ シタ バイナリセンサ オ モチイタ ホコウシャスウ スイテイ シュホウ

藤井崇渡, 谷口義明, 長谷川剛, 松岡茂登「格子状に配置したバイナリセンサを用いた歩行者数推定手法」『電子情報通信学会技術研究報告』Vol.113, No.472、pp.67-72、電子情報通信学会、201

Controlling Immune Rejection Is a Fail-Safe System against Potential Tumorigenicity after Human iPSC-Derived Neural Stem Cell Transplantation

<div><p>Our previous work reported functional recovery after transplantation of mouse and human induced pluripotent stem cell-derived neural stem/progenitor cells (hiPSC-NS/PCs) into rodent models of spinal cord injury (SCI). Although hiPSC-NS/PCs proved useful for the treatment of SCI, the tumorigenicity of the transplanted cells must be resolved before they can be used in clinical applications. The current study sought to determine the feasibility of ablation of the tumors formed after hiPSC-NS/PC transplantation through immunoregulation. Tumorigenic hiPSC-NS/PCs were transplanted into the intact spinal cords of immunocompetent BALB/cA mice with or without immunosuppressant treatment. <i>In vivo</i> bioluminescence imaging was used to evaluate the chronological survival and growth of the transplanted cells. The graft survival rate was 0% in the group without immunosuppressants versus 100% in the group with immunosuppressants. Most of the mice that received immunosuppressants exhibited hind-limb paralysis owing to tumor growth at 3 months after iPSC-NS/PC transplantation. Histological analysis showed that the tumors shared certain characteristics with low-grade gliomas rather than with teratomas. After confirming the progression of the tumors in immunosuppressed mice, the immunosuppressant agents were discontinued, resulting in the complete rejection of iPSC-NS/PC-derived masses within 42 days after drug cessation. In accordance with the tumor rejection, hind-limb motor function was recovered in all of the mice. Moreover, infiltration of microglia and lymphocytes was observed during the course of tumor rejection, along with apoptosis of iPSC-NS/PC-generated cells. Thus, immune rejection can be used as a fail-safe system against potential tumorigenicity after transplantation of iPSC-NS/PCs to treat SCI.</p></div