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

Generating Shuttling Procedures for Constrained Silicon Quantum Dot Array

In silicon quantum computers, a single electron is trapped in a microstructure called a quantum dot, and its spin is used as a qubit. For large-scale integration of qubits, we previously proposed an approach of arranging the quantum dots in a two-dimensional array and sharing a control gate in a row or column of the array. In our array, the shuttling of electrons is a useful technique to operate the target qubit independently and avoid crosstalk. However, since the shuttling is also conducted using shared control gates, the movement of qubits is complexly constrained. We therefore propose a formal model on the basis of state transition systems to describe those constraints and operation procedures on the array. We also present an approach to generate operation procedures under the constraints. Utilizing this approach, we present a concrete method for our 16 $\times$ 8 quantum dot array. By implementing the proposed method as a quantum compiler, we confirmed that it is possible to generate operation procedures in a practical amount of time for arbitrary quantum circuits. We also demonstrated that crosstalk can be avoided by shuttling and that the fidelity in that case is higher than when crosstalk is not avoided

Determination of the reference value and systematic bias of the functional reach test in Japanese elderly people by meta-analysis

AbstractBackground/PurposeThe functional reach test (FRT), which was developed as a clinical balance assessment tool, has been widely used as a fall risk assessment tool in elderly people. The aim of the present study was to investigate the reference value and the presence of systematic bias in the FRT using the methodology of meta-analysis in community-dwelling elderly people.MethodsRelevant research articles were sought from electronic databases: MEDLINE, EMBASE, Cumulative Index to Nursing and Allied Health Literature (CINAHL) and Igakucyuouzasshi. The search was conducted from January 1990 to August 2011, and the terms “functional reach” and “elderly” were used in combination in the search. The searches were limited to peer-reviewed research articles involving Japanese elderly people with good functioning, aged 60 years and older. Weighted means were calculated for the reference value of FRT by a fixed effect model and a random effect model. Furthermore, weighted least squares regression was performed to determine the presence of systematic bias in the reference value of FRT.ResultsA total of 19 articles fulfilled the inclusion criteria, including 4274 participants whose mean age ranged from 69.0 to 81.4 years. The reference value of FRT was 29.44 cm (95% confidence interval: 27.60–31.27 cm) using the random-effect model, since the reference value using the fixed-effect model was found to have significant heterogeneity. Furthermore, multivariate weighted least squares regression was performed, and sex, age, height, and measurement method (one-arm or two-arm reach) were all independently associated with the FRT value (multiple R2 = 0.295, χ2 = 76.6, p < 0.001).ConclusionsSince participants' characteristics (sex, age, and height) and measurement method are probably related to systematic error in the FRT, judgment of physical function in elderly people using only the reference value determined in this study may have limitations

The Impact of Tofogliflozin on Physiological and Hormonal Function, Serum Electrolytes, and Cardiac Diastolic Function in Elderly Japanese Patients with Type 2 Diabetes Mellitus

The sodium glucose transporter 2 (SGLT2) inhibitor tofogliflozin is a glucose-lowering drug that causes the excretion of surplus glucose by inhibiting SGLT2. Because of tofogliflozin’s osmotic diuresis mechanism, patients’ serum electrolytes, body fluid levels, and cardiac function must be monitored. We retrospectively analyzed the cases of 64 elderly Japanese patients with type 2 diabetes mellitus (T2DM) who received tofogliflozin for 3 months. Their HbA1c, serum electrolytes (sodium, potassium, chloride), hematocrit, brain natriuretic peptide (cardiac volume load marker) and renin and aldosterone (RAA; an index of regulatory hormones involved in body fluid retention) were continuously monitored during the investigation period. Renal function and cardiac function (by echocardiography) were assessed throughout the period. HbA1c significantly decreased (β1=−0.341, p<0.0001, linear regression analysis [LRA]). Most of the hormonal, electrolyte, and physiological parameters were maintained throughout the study period. In these circumstances, E/e’ tended to decrease (β1=−0.382, p=0.13, LRA). Compared to the baseline, E/e’ was significantly decreased at 1 and 3 months (p<0.01, p<0.05). In the higher E/e’ group (E/e’≥10, n=34), E/e’ decreased significantly (β1=−0.63, p<0.05, LRA). ΔE/e’ was correlated with body-weight change during treatment (r=0.64, p<0.01). The 3-month tofogliflozin treatment improved glycemic control and diastolic function represented by E/e’ in T2DM patients, without affecting serum electrolytes, renal function, or RAA. No negative impacts on the patients were observed. Three-month tofogliflozin treatment lowered glucose and improved cardiac diastolic function

SHISA6 Confers Resistance to Differentiation-Promoting Wnt/β-Catenin Signaling in Mouse Spermatogenic Stem Cells

In the seminiferous tubules of mouse testes, a population of glial cell line-derived neurotrophic factor family receptor alpha 1 (GFRα1)-positive spermatogonia harbors the stem cell functionality and supports continual spermatogenesis, likely independent of asymmetric division or definitive niche control. Here, we show that activation of Wnt/β-catenin signaling promotes spermatogonial differentiation and reduces the GFRα1+ cell pool. We further discovered that SHISA6 is a cell-autonomous Wnt inhibitor that is expressed in a restricted subset of GFRα1+ cells and confers resistance to the Wnt/β-catenin signaling. Shisa6+ cells appear to show stem cell-related characteristics, conjectured from the morphology and long-term fates of T (Brachyury)+ cells that are found largely overlapped with Shisa6+ cells. This study proposes a generic mechanism of stem cell regulation in a facultative (or open) niche environment, with which different levels of a cell-autonomous inhibitor (SHISA6, in this case) generates heterogeneous resistance to widely distributed differentiation-promoting extracellular signaling, such as WNTs