Conditions of Slope-Rotatability for Third-Order Polynomial Regression Models

In experimental design for response surface analysis, it is sometimes of interest to estimate the difference of responses at two points. If differences at points close together are involved, the design that reliably estimates the slope of the response surface is important. In particular, Hader and Park (1978 Hader , R. J. , Park , S. H. ( 1978 ). Slope-rotatable central composite designs . Technometrics 20 : 413 – 417 .[Taylor & Francis Online], [Web of Science ®] , [Google Scholar]) suggested the concept of slope-rotatability and studied slope rotatable central composite designs. Until now, many response surface designs including central composite designs have been suggested for fitting second order response surface models. However, we often need to fit third-order polynomial regression models. In this article, we suggest extended central composite designs (ECCDs) to fit third-order models and find the necessary and sufficient conditions for slope-rotatability over all directions in the third-order polynomial models.     

Estimating LAD Regression Coefficients with Best Subset Points

We propose a simple algorithm for estimating LAD (least-sum of absolute deviations) regression coefficients. The algorithm finds the best subset points to use to obtain the global optimizer in the series of a backtracking process by narrowing down the search space. Hence, the computational complexity reduces to a practical level. To evaluate the performance of the algorithm for LAD regression, we conducted simulation studies. The results showed that the algorithm is very competitive in terms of computation times required to get the same or similar results in comparison with other methods even when heavy censoring is given. Moreover, because the algorithm is quite simple and easy to understand, it can be implemented easily for various objective functions that are the variations of LAD.     

Sexual Debut and Mental Health Among South Korean Adolescents

Numerous studies have demonstrated the negative influence of sexual debut during adolescence on mental health outcomes. This article contributes to this literature by investigating whether sexual debut has negative effects on mental health among South Korean adolescents and whether the timing of adolescent sexual debut matters. Drawing on longitudinal data from a nationally representative survey, we first predicted mental health outcomes at one year after high school graduation using first sexual intercourse that had occurred before the outcomes were measured. In a second statistical model, adolescent sexual debut was defined as first coitus that had occurred before high school graduation. Sexual debut was associated with an increase in problematic aggressive behaviors for both genders. In contrast, only girls experienced a rise in depressive symptoms after becoming sexually active. For girls, having sex before high school graduation was correlated with worse mental health outcomes to the extent that sexual debut even enhanced the risk of suicidal ideation. We concluded that the negative effects of sexual activity among South Korean adolescents are attributable mainly to the sexually conservative atmosphere and gendered sexuality in that country.     

Analytical binomial lookback options with double-exponential jumps

We study the problem of the convergence of the adjusted binomial lookback option in double-exponential jump diffusion models. By using the results of [Dai, M., (2000). A modified binomial tree method for currency lookback options. Acta Mathematica Sinica, 16, 445–454; Kou, S., & Wang, H. (2004). Option pricing under a double exponential jump diffusion model. Management Science, 50, 1178–1192] and [Park, H.S., Kim, K.I., & Qian, X. (2009). A Mathematical modeling for the Lookback option with jump diffusion using Binomial tree method. Journal of Computational and Applied Mathematics, preprint], we show the equivalence between the adjusted binomial tree method and the explicit difference scheme. The convergence is also theoretically proved through the notion of viscosity solution. Numerical results coincide with the theoretical results.     

Does Radical Partisan Politics Affect National Income Distributions? Congressional Polarization and Income Inequality in the United States, 1913–2008*

Recent research indicates that political polarization in Congress and income inequality share a closely linked positive association. But virtually no studies examine the direction of influence between these variables as it is assumed that income inequality causes political polarization. The major purpose of this investigation is to examine the temporal causal ordering of these variables. Methods. This study constructs a time series national‐level data set with information for the years 1913 to 2008. Vector autoregression and granger causality tests are utilized to explore the temporal causal ordering of congressional polarization and the income share of the top 0.1, 1.0, 5.0, and 10.0 percent of earners in the United States. Autoregressive conditional heteroskedasticity regressions are also employed to assess the strength of the association between congressional polarization and top incomes net of relevant control variables. Results. The findings indicate that the past values of congressional polarization are better predictors of top income shares than vice versa. The results also demonstrate that polarization in the House of Representatives produces a more consistent and robust connection with top incomes than polarization in the Senate. Lastly, congressional polarization only produces robust associations with the income share of the top 0.1 and 1.0 percent of earners but not for the top 5.0 and 10.0 percent. Conclusion. While the Senate possesses more powerful negative agenda control procedures to stifle the legislative processes vis‐à‐vis the House, it is polarization in the latter that returns the more robust associations with income inequality.     

A robust support vector machine for labeling errors

Support vector machine (SVM) is sparse in that its classifier is expressed as a linear combination of only a few support vectors (SVs). Whenever an outlier is included as an SV in the classifier, the outlier may have serious impact on the estimated decision function. In this article, we propose a robust loss function that is convex. Our learning algorithm is more robust to outliers than SVM. Also the convexity of our loss function permits an efficient solution path algorithm. Through simulated and real data analysis, we illustrate that our method can be useful in the presence of labeling errors.     

Daily use of sildenafil 50mg at night effectively ameliorates nocturia in patients with lower urinary tract symptoms associated with benign prostatic hyperplasia: an exploratory multicenter,double-blind,randomized, placebo-controlled study

Purpose: To compare the efficacy and safety of sildenafil 25?mg qd, 25?mg bid or 50?mg qd – on treating lower urinary tract symptoms with benign prostatic hyperplasia (LUTS/BPH).

Materials and methods: Men aged?>?45 years with LUTS/BPH were randomly assigned to receive sildenafil 25?mg qd (n?=?42), bid (n?=?41), 50?mg qd (n?=?38) or placebo (n?=?41) for 8 weeks. Changes from baseline in International Prostate Symptom Score (I-PSS), maximum urinary flow rate (Qmax) and postvoid residual urine volume (PVR) were assessed at week 4 and week 8.

Results: Sildenafil 25?mg qd (-7.3?±?5.8) and 25?mg bid (-7.0?±?5.7) exhibited significant improvements of I-PSS compared to placebo (-5.2?±?6.4) (p?=?0.020, 0.025, respectively). In particular, voiding domain was more affected than storage domain. Only sildenafil 50?mg qd improved nocturia significantly (versus placebo, p?=?0.027). Quality of life score was improved in all treatment groups. Q_max and PVR did not change significantly in all groups. All regimens were well tolerated.

Conclusions: Sildenafil 25?mg qd, 25?mg bid and 50?mg qd are safe and effective to improve LUTS/BPH in long term, along with coexisting ED. In particular, nocturia is most well-controlled by 50?mg qd.     

When Do People Speak Out? Integrating the Spiral of Silence and the Situational Theory of Problem Solving

Combining spiral of silence theory with the situational theory of problem solving, this study explores the extent to which publics differ in their willingness to express their opinions in hostile social situations. Based on analysis of a survey among 369 college students about their willingness to express opinions on 2 controversial topics (gun possession and climate change), 3 key findings emerge: (a) Fear of isolation suppresses people's willingness to express their opinions in public; (b) active publics are more likely than other types of publics to express their opinions; and (c) there is no interaction effect between fear of isolation and types of publics. In addition to several theoretical contributions, the findings provide public relations practitioners with a model for predicting which types of publics would be more or less likely to express their opinion.     

Governing universal health insurance in Korea and Taiwan

This article examines policy responses to the rising costs of healthcare in the Republic of Korea and Taiwan from a governance perspective. It tries to answer why the two countries responded differently to a similar set of challenges facing their National Health Insurance (NHI). While Taiwan – in an attempt to contain costs – introduced a global budgeting system, Korea failed to do so. Governments in both countries attempted to establish a new mode of governance, bringing multiple stakeholders to health policy making in order to build social consensus. But the Korean government, as this article shows, could not resolve its policy deadlock because of a loss of trust between the government and the medical profession, caused by the separation reform of 2001. Even though Taiwan was better able than Korea to address the financial challenges of its NHI, the new mode of health governance is still on shaky ground. This article argues that because neither government now enjoys the exclusive power over health policy that they once did under the developmental state, it is essential to find a way in which different stakeholders can make the necessary compromises that will enable the NHI to run on a sustainable path for the future.