Finding a Noncrossing Steiner Forest in Plane Graphs Under a 2-Face Condition

Let G = (V,E) be a plane graph with nonnegative edge weights, and let be a family of k vertex sets , called nets. Then a noncrossing Steiner forest for in G is a set of k trees in G such that each tree connects all vertices, called terminals, in net N _i, any two trees in do not cross each other, and the sum of edge weights of all trees is minimum. In this paper we give an algorithm to find a noncrossing Steiner forest in a plane graph G for the case where all terminals in nets lie on any two of the face boundaries of G. The algorithm takes time if G has n vertices and each net contains a bounded number of terminals.     

Collective choice rules and collective rationality: a unified method of characterizations

The purpose of this paper is to investigate the relationship between collective rationality and permissible collective choice rules using a unified approach inspired by Bossert and Suzumura (J Econ Theory 138:311–320, 2008). We consider collective choice rules satisfying four axioms: unrestricted domain, strong Pareto, anonymity, and neutrality. A number of new classes of collective choice rules as well as the Pareto and Pareto extension rules are characterized under various concepts of collective rationality: acyclicity, transitivity, quasi-transitivity, semi-transitivity, and the interval order property. Further, new concepts of collective rationality, K-term acyclicity and K-term consistency, are proposed and the corresponding characterizations are provided.     

OVERSEAS MARKET INFORMATION AND FIRMS' EXPORT DECISIONS

This paper examines how firms' decision to start exporting is affected by the availability of information on export markets. Unlike existing studies that focus on information sharing among firms, we are interested in the information provided by firms' main bank. Specifically, using a unique data set containing information on both Japanese firms' export activities and the experience of their main bank (i.e., their top lender bank) in transacting with other exporting firms, we examine whether main banks act as a conduit of information on export markets. We find that information spillovers through main banks positively affect client firms' decision to start exporting (extensive margin), implying that information on foreign markets provided by banks substantially reduces the fixed entry cost of exporting. On the other hand, we do not find any evidence that information provided by banks has an effect on the export volume or on the growth rate of exports (intensive margin). Our results highlight that channels of information spillovers other than those examined in the literature so far may be of considerable importance. (JEL F10, F14, G21)     

汉初三族刑的变迁

汉初从秦朝继承而来的三族刑于吕后元年(前187年)被废除,吕后八年(前180年)吕后死后再次被制定,文帝元年(前179年)又再次被废除,文帝后元元年(前163年)至七年(前157年)之间又再次被制定.废除三族刑的背景有战国以来的三族刑废除论,以及解除秦朝苛法这一汉朝基本国策.相对于此,重新制定三族刑,则是由于通过对吕氏政权的政变及新垣平的大逆案件,重新认识到三族刑的威摄效果,以及废除三族刑并没有给国家带来实际益处.     

Testing for coefficient stability of AR(1) model when the null is an integrated or a stationary process

In this paper, we propose a new test for coefficient stability of an AR(1) model against the random coefficient autoregressive model of order 1 neither assuming a stationary nor a non-stationary process under the null hypothesis of a constant coefficient. The proposed test is obtained as a modification of the locally best invariant (LBI) test by Lee [(1998). Coefficient constancy test in a random coefficient autoregressive model. J. Statist. Plann. Inference 74, 93–101]. We examine finite sample properties of the proposed test by Monte Carlo experiments comparing with other existing tests, in particular, the LBI test by McCabe and Tremayne [(1995). Testing a time series for difference stationary. Ann. Statist. 23 (3), 1015–1028], which is for the null of a unit root process against the alternative of a stochastic unit root process.     

Effects of Customized Balance Exercises on Older Women Whose Balance Ability Has Deteriorated With Age

Falls represent a major public health problem for older adults, and loss of balance (LOS) abilities is one of the primary causes of falls. Previous studies have shown that balance training is effective in improving physical function and decreasing risk of falls. However, little attention has been given specifically to balance training in older adults with very poor balance. The purpose of this study was to determine the effect of a 12-week customized balance exercise program on LOS for community-dwelling older women with poor balance ability. Twenty-four older women with poor balance (composite maximum excursion [MXEcomp] score of less than 70% based on Limits of Stability) were divided into an exercise group and control group. After 12 weeks of balance exercises, mean MXEcomp improved (p < .05) from 58.6% to 79.0% in the exercise group. EPEcomp (composite endpoint excursion), RTcomp (composite reaction time), SVcomp3 (composite sway velocity on thick foam with the eyes open), UG (up and go) also improved, but the functional reach and other static balance indexes did not change. These results indicated that balance training allows older adults with poor balance to improve dynamic balance ability and potentially reduce risk for falls.     

Further results on the vecd operator and its applications

Abstract

In this paper, we consider the matrix vectorization operator termed the vecd operator, which has recently been introduced in the literature. This operator stacks up distinct elements of a symmetric matrix in a way that differs from that of the well-known vech operator; it stacks up not columns, but diagonals. We give further consideration to the vecd operator and related matrices, and derive their various useful properties. We provide some statistical applications of the vecd operator to illustrate its usefulness.     

Evaluating the Quality of Online Survey Data Collected in 2018 in the USA: Univariate,Bivariate, and Multivariate Analyses

Collecting survey data in Japan and the USA is difficult for many reasons, including the difficulty of creating complete sampling frames and low response rates. Online surveys, which collect data through online access panels and recruit members using nonprobability sampling, is becoming a popular alternative to traditional survey techniques, both in market and social science research. However, sociological researchers are hesitant to adopt online survey data collection techniques as it is unclear how representative such data are. This article examines the quality of online survey data by comparing online surveys with the two datasets collected using probability sampling, the American Community Survey and the General Social Survey. We conducted univariate, bivariate, and multivariate analyses and investigated whether similarities improve from the univariate analyses to bivariate relationships, and to bivariate relationships with controls. The results show that similarities improved from univariate to bivariate and multivariate analyses, but the results of bivariate and multivariate analyses did not differ. We concluded that data collected via volunteer‐based access panels yielded similar results to the benchmark data, especially when the relationships among variables are examined. We argue that automatically discrediting the data collected via volunteer‐based access panels is not good practice. With careful considerations of data quality, online survey data with nonprobability sampling could advance sociological research by giving researchers more freedom to ask questions at a relatively low cost, with a quick turnaround time, and more opportunities to conduct cross‐national research.     

On the relationship between the matrix operators,vech and vecd

We introduce a matrix operator, which we call “vecd” operator. This operator stacks up “diagonals” of a symmetric matrix. This operator is more convenient for some statistical analyses than the commonly used “vech” operator. We show an explicit relationship between the vecd and vech operators. Using this relationship, various properties of the vecd operator are derived. As applications of the vecd operator, we derive concise and explicit expressions of the Wald and score tests for equal variances of a multivariate normal distribution and for the diagonality of variance coefficient matrices in a multivariate generalized autoregressive conditional heteroscedastic (GARCH) model, respectively.