Nonessentiality of Reservoir’s Fading Memory for Universality of Reservoir Computing

This article describes a novel sufficient condition concerning approximations with reservoir computing (RC). Recently, RC using a physical system as the reservoir has attracted attention. Because many physical systems are modeled as state-space systems, it is necessary to guarantee the approximations given by reservoirs represented as nonlinear state-space systems. There are two problems with existing approaches: a reservoir must have a property called fading memory and must be represented as a set of maps between input and output signals on the bi-infinite-time (BIT) interval. These two conditions are too strict for reservoirs represented as nonlinear state-space systems as they require the reservoir to have a unique equilibrium state for the zero input. This article proposes an approach that employs operators from right-infinite-time (RIT) inputs to RIT outputs. Furthermore, we develop a novel extension of the Stone–Weierstrass theorem to handle discontinuous functions. To apply the extended theorem, we define functionals corresponding to operators and introduce a metric on the domain of the functionals. The resulting sufficient condition does not require the reservoir to have fading memory or continuity with respect to inputs and time. Therefore, our result guarantees the approximations with very common reservoirs and provides a rationale for physical RC. We present an example of a physical reservoir without fading memory. With the example reservoir, the RC model successfully approximates NARMA10, a benchmark task for time series predictions.journal articl

Controllability Maximization of Network Systems: Gradient Computation Based on Offline Data

In the field of network systems, controllability maximization has become more important in terms of efficient control. When an exact model of a network system is not available, data-driven approaches are useful. In this paper, we establish a framework for maximizing the controllability of networked systems by using off-line data. In particular, the maximization with respect to the network topology of the network system is addressed. First, we develop a data-driven method for solving the Lyapunov equation which describes the properties of a system different from the system associated with the data. Second, based on this result, we derive a data-driven method for computing the gradient of a controllability measure (the trace of the controllability Gramian) with respect to the network topology of the network system. Finally, we show that our gradient computation can be used for controllability maximization based on off-line data. The effectiveness of the data-driven methods is numerically demonstrated

Default detection in demand response based on block-sparse structure

節電未達者を検出する新アルゴリズム、性能が10倍以上に --節電参加者の性質を組み込むことで大幅な効率化に成功 --.京都大学プレスリリース. 2024-11-01.Demand response (DR) is the change in electric consumption by prompting consumers to change their normal consumption patterns in response to financial incentives. In various forms of DR, the contract-based DR is a framework to achieve a certain reduction by the contract with individual participants for their reduction. However, in practice, it is inevitable to encounter a default, implying that some of the participants fail contracted reduction owing to an unexpected event. This study develops a method to detect defaulting participants in contract-based DR. The method iterates two steps: estimating the most suspicious participant and inspecting its smart meter. By utilizing block-sparse structures in the detection problem, it can exactly determine the defaulting participants with a small number of inspections. The performance is evaluated by simulation, which indicates that our method has much higher performance than the conventional method in the sense that the number of inspections approximately 96.8% fewer than that of the conventional one

Deletion of both p62 and Nrf2 spontaneously results in the development of nonalcoholic steatohepatitis

Nonalcoholic steatohepatitis (NASH) is one of the leading causes of chronic liver disease worldwide. However, details of pathogenetic mechanisms remain unknown. Deletion of both p62/Sqstm1 and Nrf2 genes spontaneously led to the development of NASH in mice fed a normal chow and was associated with liver tumorigenesis. The pathogenetic mechanism (s) underlying the NASH development was investigated in p62:Nrf2 double-knockout (DKO) mice. DKO mice showed massive hepatomegaly and steatohepatitis with fat accumulation and had hyperphagia-induced obesity coupled with insulin resistance and adipokine imbalance. They also showed dysbiosis associated with an increased proportion of gram-negative bacteria species and an increased lipopolysaccharide (LPS) level in feces. Intestinal permeability was elevated in association with both epithelial damage and decreased expression levels of tight junction protein zona occludens-1, and thereby LPS levels were increased in serum. For Kupffer cells, the foreign body phagocytic capacity was decreased in magnetic resonance imaging, and the proportion of M1 cells was increased in DKO mice. In vitro experiments showed that the inflammatory response was accelerated in the p62:Nrf2 double-deficient Kupffer cells when challenged with a low dose of LPS. Diet restriction improved the hepatic conditions of NASH in association with improved dysbiosis and decreased LPS levels. The results suggest that in DKO mice, activation of innate immunity by excessive LPS flux from the intestines, occurring both within and outside the liver, is central to the development of hepatic damage in the form of NASH

Laparoscopic Hepatectomy: Current State in Japan Based on the 4th Nationwide Questionnaire

Purpose. Since laparoscopic hepatectomy (LH) became covered by national health insurance in April 2010 in Japan, the numbers of applied cases and institutions performing it have increased and the indication has expanded. We surveyed the current state and safety of LH in Japan. Methods. A questionnaire survey was performed in 41 institutions related to the Japanese Endoscopic Liver Surgery Study Group and 747 institutions certified by the Japanese Society of Gastroenterological Surgery, and responses concerning all 2962 cases of LH performed by August 2011 were obtained. Results. The surgical procedure employed was hemihepatectomy in 234 (8%), segmentectomy in 88 (3%), left lateral segmentectomy in 434 (15%), segmentectomy in 156 (5%), and partial resection in 1504 (51%) cases. The approach was pure laparoscopy in 1835 (63%), hand-assisted laparoscopic surgery in 201 (7%), and laparoscopy-assisted surgery in 926 (31%). Regarding perioperative complications, surgery was switched to laparotomy in 59 (2.0%), reoperation was performed in 4 (0.1%), and surgery-related death occurred in 2 (0.07%). Intraoperative accidents occurred in 68 (2.3%), and postoperative complications developed in 94 (3.2%). Conclusions. When the selection of cases is appropriate, LH for liver diseases can be safely performed

Long-term Survival of Patients with Cholangiolocellular Carcinoma After Curative Hepatectomy

BACKGROUND: Cholangiolocellular carcinoma (CoCC) has distinct pathological characteristics, and CoCC is considered to originate from hepatic progenitor or stem cells. However, the surgical outcome of CoCC has not been clarified in detail. METHODS: We retrospectively studied 275 patients with intrahepatic cholangiocarcinoma (ICC) who underwent hepatectomy between 1990 and 2011. Surgical outcomes were compared between 29 patients with CoCC and 130 patients with mass-forming (MF) type ICC since all patients with CoCC showed MF type on macroscopic findings. RESULTS: The number of patients with chronic liver disease was significantly higher in the CoCC group than in the ICC group. The number of patients with abnormal levels of CA19-9 was significantly lower in the CoCC group than in the ICC group. Portal vein invasion and intrahepatic metastasis were significantly lower in patients with CoCC group than in the ICC group. In the CoCC group, 15 of 28 patients survived for more than 5 years after curative surgery whereas 15 of 102 patients with ICC survived for more than 5 years after curative surgery. The 5-year survival rate was significantly higher in patients with CoCC (75 %) than in patients with ICC (33 %, p = 0.0005). Multivariate analysis showed CoCC, absence of portal vein invasion or hepatic vein invasion, and absence of intrahepatic metastasis to be significant independent prognostic factors for overall survival in patients with MF-type ICC and CoCC. CONCLUSIONS: CoCC is rare, but patients with CoCC had special characteristics with favorable long-term survival due to its less invasive histopathologic characteristics

Gender difference in development of steatohepatitis in p62/Sqstm1 and Nrf2 double-knockout mice

journal articl

Urinary Levels of Titin-N Fragment a Skeletal Muscle Damage Marker are Increased in Subjects with Nonalcoholic Fatty Liver Disease

journal articl

Genomic characterization of biliary tract cancers identifies driver genes and predisposing mutations

Background & Aims Biliary tract cancers (BTCs) are clinically and pathologically heterogeneous and respond poorly to treatment. Genomic profiling can offer a clearer understanding of their carcinogenesis, classification and treatment strategy. We performed large-scale genome sequencing analyses on BTCs to investigate their somatic and germline driver events and characterize their genomic landscape. Methods We analyzed 412 BTC samples from Japanese and Italian populations, 107 by whole-exome sequencing (WES), 39 by whole-genome sequencing (WGS), and a further 266 samples by targeted sequencing. The subtypes were 136 intrahepatic cholangiocarcinomas (ICCs), 101 distal cholangiocarcinomas (DCCs), 109 peri-hilar type cholangiocarcinomas (PHCs), and 66 gallbladder or cystic duct cancers (GBCs/CDCs). We identified somatic alterations and searched for driver genes in BTCs, finding pathogenic germline variants of cancer-predisposing genes. We predicted cell-of-origin for BTCs by combining somatic mutation patterns and epigenetic features. Results We identified 32 significantly and commonly mutated genes including TP53 , KRAS , SMAD4 , NF1 , ARID1A , PBRM1 , and ATR , some of which negatively affected patient prognosis. A novel deletion of MUC17 at 7q22.1 affected patient prognosis. Cell-of-origin predictions using WGS and epigenetic features suggest hepatocyte-origin of hepatitis-related ICCs. Deleterious germline mutations of cancer-predisposing genes such as BRCA1 , BRCA2 , RAD51D , MLH1 , or MSH2 were detected in 11% (16/146) of BTC patients. Conclusions BTCs have distinct genetic features including somatic events and germline predisposition. These findings could be useful to establish treatment and diagnostic strategies for BTCs based on genetic information. Lay summary We here analyzed genomic features of 412 BTC samples from Japanese and Italian populations. A total of 32 significantly and commonly mutated genes were identified, some of which negatively affected patient prognosis, including a novel deletion of MUC17 at 7q22.1 . Cell-of-origin predictions using WGS and epigenetic features suggest hepatocyte-origin of hepatitis-related ICCs. Deleterious germline mutations of cancer-predisposing genes were detected in 11% of patients with BTC. BTCs have distinct genetic features including somatic events and germline predisposition