Cut Tree Construction from Massive Graphs

The construction of cut trees (also known as Gomory-Hu trees) for a given graph enables the minimum-cut size of the original graph to be obtained for any pair of vertices. Cut trees are a powerful back-end for graph management and mining, as they support various procedures related to the minimum cut, maximum flow, and connectivity. However, the crucial drawback with cut trees is the computational cost of their construction. In theory, a cut tree is built by applying a maximum flow algorithm for $n$ times, where $n$ is the number of vertices. Therefore, naive implementations of this approach result in cubic time complexity, which is obviously too slow for today's large-scale graphs. To address this issue, in the present study, we propose a new cut-tree construction algorithm tailored to real-world networks. Using a series of experiments, we demonstrate that the proposed algorithm is several orders of magnitude faster than previous algorithms and it can construct cut trees for billion-scale graphs.Comment: Short version will appear at ICDM'1

On the Power of Tree-Depth for Fully Polynomial FPT Algorithms

There are many classical problems in P whose time complexities have not been improved over the past decades. Recent studies of "Hardness in P" have revealed that, for several of such problems, the current fastest algorithm is the best possible under some complexity assumptions. To bypass this difficulty, the concept of "FPT inside P" has been introduced. For a problem with the current best time complexity O(n^c), the goal is to design an algorithm running in k^{O(1)}n^{c\u27} time for a parameter k and a constant c\u27<c. In this paper, we investigate the complexity of graph problems in P parameterized by tree-depth, a graph parameter related to tree-width. We show that a simple divide-and-conquer method can solve many graph problems, including Weighted Matching, Negative Cycle Detection, Minimum Weight Cycle, Replacement Paths, and 2-hop Cover, in O(td m) time or O(td (m+nlog n)) time, where td is the tree-depth of the input graph. Because any graph of tree-width tw has tree-depth at most (tw+1)log_2 n, our algorithms also run in O(tw mlog n) time or O(tw (m+nlog n)log n) time. These results match or improve the previous best algorithms parameterized by tree-width. Especially, we solve an open problem of fully polynomial FPT algorithm for Weighted Matching parameterized by tree-width posed by Fomin et al. (SODA 2017)

Time-varying Fiscal Multipliers Identified by Systematic Component: A Bayesian Approach to TVP-SVAR model

Abstract This study estimates time varying fiscal multipliers from the aspect of fiscal policy rules derived from the systematic component along the line of “Agnostic Identification Procedure” proposed by Caldara and Kamps (2017) for the US economy between 1952:Q1-2018:Q1. To do so, we adopt time-varying parameter structural vector autoregressive (TVP-SVAR) with MCMC procedure by a Bayesian approach, and identify both of government spending and tax cut shocks using the zero and sign restrictions method proposed by Arias, Rubio-Ramirez and Waggoner (2018). And we compare those values with time varying version identified by standard sign restriction along the line of Mountford and Uhlig (2009). Our estimation reports that time-varying fiscal multipliers of output by government spending rule could be nearly double for one year but decline to unity after eight years, and seem to have been very stable for long terms such as sixty years. By contrast, those of tax cut rule are more fluctuate and negative for long run except the 1990’s

Thrombocytopenia in pegylated interferon and ribavirin combination therapy for chronic hepatitis C

BACKGROUND: This study aimed to examine the therapeutic effect and prognostic indicators of pegylated interferon (PEG-IFN) and ribavirin (RBV) combination therapy in thrombocytopenic patients with chronic hepatitis C, hepatitis C virus (HCV)-related cirrhosis, and those who underwent splenectomy or partial splenic embolization (PSE). METHODS: Of 326 patients with HCV-related chronic liver disease (252 with genotype 1b and 74 with genotype 2a/2b) treated with PEG-IFN/RBV, 90 were diagnosed with cirrhosis. RESULTS: Regardless of the degree of thrombocytopenia, the administration rate was significantly higher in the splenectomy/PSE group compared to the cirrhosis group. However, in patients with genotype 1b, the sustained virological response (SVR) rate was significantly lower in the cirrhosis and the splenectomy/PSE groups compared to the chronic hepatitis group. No cirrhotic patients with platelets less than 80,000 achieved an SVR. Patients with genotype 2a/2b were more likely to achieve an SVR than genotype 1b. Prognostic factors for SVR in patients with genotype 1b included the absence of esophageal and gastric varices, high serum ALT, low AST/ALT ratio, and the major homo type of the IL28B gene. Splenectomy- or PSE-facilitated induction of IFN in patients with genotype 2a/2b was more likely to achieve an SVR by an IFN dose maintenance regimen. Patients with genotype 1b have a low SVR regardless of splenectomy/PSE. In particular, patients with a hetero/minor type of IL28B did not have an SVR. CONCLUSIONS: Splenectomy/PSE for IFN therapy should be performed in patients expected to achieve a treatment response, considering their genotype and IL28B

Adaptive Optics Rest-Frame V-band Imaging of Lyman Break Galaxies at z~3: High-surface Density Disk-like Galaxies ?

In order to reveal the rest-frame V-band morphology of galaxies at z~3, we conducted AO-assisted K-band imaging observations of z~3 LBGs with Mv*-0.5 to Mv*+3.0 mag. LBGs brighter than Mv* have larger rHL (0.40") than the fainter LBGs (0.23") on average, and there is no bright LBGs with a small rHL. The LBGs brighter than Mv* have red rest-frame U-V colors (average of 0.2 mag) and most of the fainter LBGs show blue rest-frame U-V colors (average of -0.4 mag). The K-band peaks of some of the LBGs brighter than K=22.0 mag show significant shift from those in the optical images. The images of all but one of the LBGs with K<21.5 mag are fitted well with Sersic profile with n index less than 2, similar to disk galaxies in the local universe. Assuming that the LBGs have a disk-shape, we compared their size-luminosity and size-stellar mass relation with those of z=0 and z=1 disk galaxies. The LBGs are brighter than z=0 and z=1 disk galaxies at the same effective radius. The rest-frame V-band surface brightness of the LBGs are 2.2-2.9 mag and 1.2-1.9 mag brighter than the disk galaxies at z=0 and z=1, respectively. The size-stellar mass relation of the LBGs shows that the effective radii of the LBGs do not depend on their stellar mass. For the LBGs brighter than Mv*, the average surface stellar mass density is 3-6 times larger than those of the z=0 and z=1 disk galaxies. We also examine the profiles of the serendipitously observed DRGs. They are also fitted with the Sersic profiles with n<2. The implications of the dominance of n<2 population among galaxies at z~3 and the presence of the high surface stellar mass density disk systems are discussed.Comment: Accepted for publication in Astrophysical Journal Supplement. 38 pages, 26 postscript figures. Original version with high resolution figures is available from http://www.naoj.org/staff/akiyama/papers/LBG_AO.pd

Development, Characteristics and Durability of Dye-Sensitized Solar Cell

The DSSC 120 x 120 mm square sub-module with high conversion efficiency, excellent high temperature durability was fabricated using the new ruthenium-complex dye J2 which was developed by us, most appropriate Ti02 nano-particles, suited electrolyte containing iodine, the improved sealant, protective material of collecting grids. By assembling many sub-modules, large size of modules and also see-through type DSSC modules were developed. By the study of characteristics of DSSC on the incident angle of light and temperature, the advantage of DSSC has been discussed comparing with other Si solar cells

Consumer Policy and Market Norms: Routes of socioeconomic development abstracted from literature concerning consumer fraud and product safety (Japanese)

In recent years, the evaluation of the public-private partnership (PPP) has been an important issue in discussions relating to public service reform. The increasing trend of an overwhelming number of public services being provided through the private sector lies in the government's traditional approach of outsourcing. Meanwhile, new methods of using the private sector such as the private finance initiative (PFI), the designated manager system, and market testing also draw attention, but it appears that the introduction of these methods into local governments is not always a smooth process. While an effort is being made to overcome the institutional restrictions and problems associated with the introduction of these initiatives, differing attitudes of local governments toward the promotion of PPPs seem to have a significant impact. This paper aims to analyze and evaluate PPPs from an empirical perspective, looking at the public services that the government outsourced to private companies in various forms and then deriving policy implications. This paper consists of the following four studies: I. Factors for promoting PPP in local governments (YAMAUCHI Naoto, ISHIDA Yu, OKUYAMA Naoko) II. Does government spending trigger private contributions? (MATSUNAGA Yoshiho, OKUYAMA Naoko) III. Evaluation of PPPs in home-visit nursing care services (SUZUKI Wataru, HOTTA Satoko) IV. Outsourcing of waste collection and factors for its promotion (IWATA Kenji)

Prognostic impact of adjuvant endocrine therapy for estrogen receptor-positive and HER2-negative T1a/bN0M0 breast cancer

Purpose Mammography screening has increased the detection of subcentimeter breast cancers. The prognosis for estrogen receptor (ER)-positive and human epidermal growth factor receptor 2 (HER2)-negative T1a/bN0M0 breast cancers is excellent; however, the necessity of adjuvant endocrine therapy (ET) is uncertain. Methods We evaluated the effectiveness of adjuvant ET in patients with ER-positive and HER2-negative T1a/bN0M0 breast cancer who underwent surgery from 2008 to 2012. Standard ET was administrated after surgery. The primary endpoint was the cumulative incidence of distant metastasis. All statistical tests were 2-sided. Results Adjuvant ET was administered to 3991 (83%) of the 4758 eligible patients (1202 T1a [25.3%] and 3556 T1b [74.7%], diseases). The median follow-up period was 9.2 years. The 9-year cumulative incidence of distant metastasis was 1.5% with ET and 2.6% without ET (adjusted subdistribution hazard ratio [sHR], 0.54; 95% CI, 0.32–0.93). In multivariate analysis, the independent risk factors for distant metastasis were no history of ET, mastectomy, high-grade, and lymphatic invasion. The 9-year overall survival was 97.0% and 94.4% with and without ET, respectively (adjusted HR, 0.57; 95% CI, 0.39–0.83). In addition, adjuvant ET reduced the incidence of ipsilateral and contralateral breast cancer (9-year rates; 1.1% vs. 6.9%; sHR, 0.17, and 1.9% vs. 5.2%; sHR, 0.33). Conclusions The prognosis was favorable in patients with ER-positive and HER2-negative T1a/bN0M0 breast cancer. Furthermore, adjuvant ET reduced the incidence of distant metastasis with minimal absolute risk difference. These findings support considering the omission of adjuvant ET, especially for patients with low-grade and no lymphatic invasion disease

Atrial Fibrillation Detection and Ischemic Stroke Recurrence in Cryptogenic Stroke: A Retrospective, Multicenter, Observational Study

Todo K., Okazaki S., Doijiri R., et al. Atrial Fibrillation Detection and Ischemic Stroke Recurrence in Cryptogenic Stroke: A Retrospective, Multicenter, Observational Study. Journal of the American Heart Association 13, e031508 (2024); https://doi.org/10.1161/JAHA.123.031508.BACKGROUND: Atrial fibrillation (AF) is known to be a strong risk factor for stroke. However, the risk of stroke recurrence in patients with cryptogenic stroke with AF detected after stroke by an insertable cardiac monitor (ICM) is not well known. We sought to evaluate the risk of ischemic stroke recurrence in patients with cryptogenic stroke with and without ICM-detected AF. METHODS AND RESULTS: We retrospectively reviewed patients with cryptogenic stroke who underwent ICM implantation at 8 stroke centers in Japan. Cox regression models were developed using landmark analysis and time-dependent analysis. We set the target sample size at 300 patients based on our estimate of the annualized incidence of ischemic stroke recurrence to be 3% in patients without AF detection and 9% in patients with AF detection. Of the 370 patients, 121 were found to have AF, and 110 received anticoagulation therapy after AF detection. The incidence of ischemic stroke recurrence was 4.0% in 249 patients without AF detection and 5.8% in 121 patients with AF detection (P=0.45). In a landmark analysis, the risk of ischemic stroke recurrence was not higher in patients with AF detected ≤90 days than in those without (hazard ratio, 1.47 [95% CI, 0.41–5.28]). In a time-dependent analysis, the risk of ischemic stroke recurrence did not increase after AF detection (hazard ratio, 1.77 [95% CI, 0.70–4.47]). CONCLUSIONS: The risk of ischemic stroke recurrence in patients with cryptogenic stroke with ICM-detected AF, 90% of whom were subsequently anticoagulated, was not higher than in those without ICM-detected AF