Look-Up Table based FHE System for Privacy Preserving Anomaly Detection in Smart Grids

In advanced metering infrastructure (AMI), the customers\u27 power consumption data is considered private but needs to be revealed to data-driven attack detection frameworks. In this paper, we present a system for privacy-preserving anomaly-based data falsification attack detection over fully homomorphic encrypted (FHE) data, which enables computations required for the attack detection over encrypted individual customer smart meter\u27s data. Specifically, we propose a homomorphic look-up table (LUT) based FHE approach that supports privacy preserving anomaly detection between the utility, customer, and multiple partied providing security services. In the LUTs, the data pairs of input and output values for each function required by the anomaly detection framework are stored to enable arbitrary arithmetic calculations over FHE. Furthermore, we adopt a private information retrieval (PIR) approach with FHE to enable approximate search with LUTs, which reduces the execution time of the attack detection service while protecting private information. Besides, we show that by adjusting the significant digits of inputs and outputs in our LUT, we can control the detection accuracy and execution time of the attack detection, even while using FHE. Our experiments confirmed that our proposed method is able to detect the injection of false power consumption in the range of 11-17 secs of execution time, depending on detection accuracy

大規模診療情報データベースを用いた臨床疫学研究におけるリスク調整手法の検討

学位の種別: 課程博士審査委員会委員 : （主査）東京大学教授 大江 和彦, 東京大学准教授 仲上 豪二朗, 東京大学教授 長瀬 隆英, 東京大学准教授 中島 勤, 東京大学講師 冨尾 淳University of Tokyo(東京大学

Privacy-Preserving Data Falsification Detection in Smart Grids using Elliptic Curve Cryptography and Homomorphic Encryption

In an advanced metering infrastructure (AMI), the electric utility collects power consumption data from smart meters to improve energy optimization and provides detailed information on power consumption to electric utility customers. However, AMI is vulnerable to data falsification attacks, which organized adversaries can launch. Such attacks can be detected by analyzing customers\u27 fine-grained power consumption data; however, analyzing customers\u27 private data violates the customers\u27 privacy. Although homomorphic encryption-based schemes have been proposed to tackle the problem, the disadvantage is a long execution time. This paper proposes a new privacy-preserving data falsification detection scheme to shorten the execution time. We adopt elliptic curve cryptography (ECC) based on homomorphic encryption (HE) without revealing customer power consumption data. HE is a form of encryption that permits users to perform computations on the encrypted data without decryption. Through ECC, we can achieve light computation. Our experimental evaluation showed that our proposed scheme successfully achieved 18 times faster than the CKKS scheme, a common HE scheme

Artificial colloids versus human albumin for the treatment of ovarian hyperstimulation syndrome: A retrospective cohort study

Background: The optimal colloid solution for the treatment of ovarian hyperstimulation syndrome (OHSS) remains to be established. Objective: We aimed to compare artificial colloids (AC) with human albumin (HA) for the treatment of OHSS. Materials and Methods: In this retrospective cohort study, data for OHSS participants were collected from a national inpatient database in Japan. The participants received intravenous fluid management with AC (n = 156) or HA (n = 127). We compared the two groups in terms of the length of stay, development of post-treatment complications, and termination surgery. Results: In multivariable linear regression analyses for log-transformed length of stay with reference to the OHSS participants receiving AC, the regression coefficient (95% confidence interval) in participants receiving HA was 0.03 (-0.04-0.09, p = 0.42). Thromboembolism occurred in two participants in the HA group and three participants in the AC group. Two participants in the HA group suffered renal failure during hospitalization. No participants underwent termination surgery in the two groups. Conclusions: The present results showed comparable efficacy between AC and HA for the treatment of OHSS. There were no significant differences in post-treatment complications between the two groups. Key words: Ovarian hyperstimulation syndrome, Treatment, Colloid, Length of stay

人工膝関節置換術後の関節周囲感染が疑われる症例の発生頻度は、術中麻酔維持使用薬剤の選択と関連するか（プロポフォールによる全静脈麻酔と、セボフルランでの麻酔維持での比較）：後ろ向きコホート研究

PURPOSE: Periprosthetic joint infection is a serious complication of total knee arthroplasty. Though there are many factors that might increase its risk, the use of propofol for maintaining general anesthesia could theoretically increase the incidence of infection because of its lipid component that supports bacterial growth. Nevertheless, the relationship between anesthetic maintenance agents and the occurrence of periprosthetic joint infection remains uncertain. The purpose of this study was to compare the incidence of suspected early-onset periprosthetic joint infection between patients undergoing total knee arthroplasty under propofol vs sevoflurane anesthesia. METHODS: We conducted a retrospective cohort study of patients in the national inpatient Diagnosis Procedure Combination database in Japan who underwent total knee arthroplasty. Suspected periprosthetic joint infection was surrogately defined as the need for arthrocentesis or debridement within 30 days of surgery. Propensity score matching was performed between patients who received either propofol or sevoflurane for anesthetic maintenance to determine the proportion of those with infection. RESULTS: Eligible patients (n = 21,899) were categorized into either the propofol (n = 7,439) or sevoflurane (n = 14,460) groups. In the 5,140 propensity-matched patient pairs, there was no significant difference in the proportion of arthrocentesis or debridement [1.3% propofol vs 1.7% sevoflurane; respectively (relative risk, 0.76; 95% CI, 0.55 to 1.04; P = 0.10)] between the groups. The mean (SD) length of stay in the propofol group was significantly longer than in the sevoflurane group [32.5 (18.4) days vs 31.4 (14.4) days, respectively; mean difference, 1.1; 95% CI, 0.5 to 1.8; P < 0.001]. CONCLUSION: Propensity score analysis suggested no significant association between the choice of anesthetic maintenance agent and the occurrence of suspected early-onset periprosthetic joint infection in patients undergoing total knee arthroplasty.博士（医学）・甲第700号・平成31年3月15日© Canadian Anesthesiologists' Society 2018This is a post-peer-review, pre-copyedit version of an article published in Canadian journal of anaesthesia. The final authenticated version is available online at: http://dx.doi.org/10.1007/s12630-018-1139-6

経動脈的化学塞栓術における予防的抗菌薬と肝膿瘍発症の関連 : 後方視的コホート研究

Objectives: Clinical evidence on prophylactic antibiotics for transarterial chemoembolization (TACE) to prevent liver abscess is limited because liver abscess is a rare event. This study aimed to analyse the association between prophylactic antibiotic use for TACE and the occurrence of liver abscess after TACE. Methods: Using the nationwide Diagnosis Procedure Combination database in Japan, we retrospectively identified patients who underwent TACE for hepatic cancer between July 2010 and March 2017. The primary outcome was liver abscess requiring procedural intervention within 30 days of TACE. Secondary outcomes included 30-day in-hospital mortality and length of stay. Propensity score matching was performed to adjust for potential confounding factors and compare outcomes between patients with and without prophylactic antibiotics. Results: Among 167 544 eligible patients, 134 712 received antibiotics and 32 832 did not. In the matched cohort of 29 211 pairs, the proportion of patients with liver abscess requiring procedural intervention was significantly lower in the antibiotics group than in the no-antibiotics group (0.08% vs. 0.22%, p 0.001; relative risk (95% confidence interval), 0.35 (0.22-0.57); absolute risk reduction, 0.0014 (0.0008-0.0021); and number needed to treat, 696 (476-1223)). There was no significant difference in 30-day in-hospital mortality between the groups. The length of stay was longer in the antibiotics group than in the no-antibiotics group (median, 10 vs. 9 days, p < 0.001). Conclusions: Prophylactic antibiotic use in patients undergoing TACE was associated with a reduced occurrence of liver abscess requiring procedural intervention.博士（医学）・甲第794号・令和3年6月25日Copyright © 2021 The Author(s). Published by Elsevier Ltd.. All rights reserved

心室中隔欠損症に対する小児心臓カテーテル検査における麻酔方法と重症合併症の関連

Pediatric cardiac catheterization requires unconsciousness and immobilization through general anesthesia or sedation. This study aimed to compare the occurrence of severe complications in pediatric diagnostic cardiac catheterization for ventricular septal defect between general anesthesia and sedation performed under similar institutional environments. Using the Japanese Diagnosis Procedure Combination database, we retrospectively identified pediatric patients (aged <2 years) who underwent diagnostic cardiac catheterization for ventricular septal defect between July 2010 and March 2019. The composite outcome was the occurrence of severe complications, including catecholamine use and intensive care unit admission, within seven days after catheterization. Overlap weighting based on propensity scores was used to adjust for patient- and hospital-level confounding factors. We identified 3159 patients from 87 hospitals, including 930 under general anesthesia and 2229 under sedation. The patient- and hospital-level baseline characteristics differed between the groups. After adjustment, the proportion of patients with severe complications was significantly higher in the general anesthesia group than in the sedation group (2.4% vs. 0.6%; risk difference, 1.8% [95% confidence interval, 0.93–2.6%]). Severe complications occurred more frequently in the general anesthesia group than in the sedation group. Further research on anesthetic methods is necessary to assess the safety and accuracy of pediatric diagnostic cardiac catheterization.博士（医学）・甲第867号・令和5年3月15

Psychiatric intervention and repeated admission to emergency centres due to drug overdose

Self-harm, with or without suicidal intent, substantially increases the risk of future suicide and is known to be the strongest predictor of completed suicide. Furthermore, repetition of self-harm is common: 16% of patients who self-harmed were found to repeat a similar episode within 1 year. Repetition of self-harm increases the risk of completed suicide. One study found overdose to be the most prevalent type of suicide attempt that required admission, and approximately 80% of self-harm episodes have been reported to involve overdose. It is therefore necessary to prevent the repetition of self-harm by drug overdose. According to clinical guidelines on the management of self-harm published in 2004, it is recommended that every patient presenting to hospital with self-harm should undergo a psychosocial assessment by specialists before being discharged. Despite this recommendation, some studies have found that many patients, especially those with repeated self-harm did not actually receive such assessments. That would suggest that the guideline has not been widely used – possibly because it was not based on firm evidence. There is a lack of data on the influence of psychosocial assessments on preventing repetition of self-harm. Some studies have suggested that such assessments do have an influence, but they were based on a small sample size or on a small number of highly advanced institutions. The present study focused on patients with drug overdose who were admitted to emergency centres. Using a national in-patient database in Japan, it aimed to investigate whether psychiatric intervention before discharge was associated with reduced patient readmissions with drug overdose.UTokyo Research掲載「過量服薬による入院患者と精神科医による診察の関係」 URI: http://www.u-tokyo.ac.jp/ja/utokyo-research/research-news/psychiatric-intervention-and-repeated-emergency-admission-due-to-drug-overdose.htmlUTokyo Research "Psychiatric intervention and repeated emergency admission due to drug overdose" URI: http://www.u-tokyo.ac.jp/en/utokyo-research/research-news/psychiatric-intervention-and-repeated-emergency-admission-due-to-drug-overdose.htm