On the asymptotic behaviour of the recursive Nadaraya–Watson estimator associated with the recursive sliced inverse regression method

We investigate the asymptotic behaviour of the recursive Nadaraya–Watson estimator for the estimation of the regression function in a semiparametric regression model. On the one hand, we make use of the recursive version of the sliced inverse regression method for the estimation of the unknown parameter of the model. On the other hand, we implement a recursive Nadaraya–Watson procedure for the estimation of the regression function which takes into account the previous estimation of the parameter of the semiparametric regression model. We establish the almost sure convergence as well as the asymptotic normality for our Nadaraya–Watson estimate. We also illustrate our semiparametric estimation procedure on simulated data.     

On approximations via convolution-defined mixture models

An often-cited fact regarding mixing or mixture distributions is that their density functions are able to approximate the density function of any unknown distribution to arbitrary degrees of accuracy, provided that the mixing or mixture distribution is sufficiently complex. This fact is often not made concrete. We investigate and review theorems that provide approximation bounds for mixing distributions. Connections between the approximation bounds of mixing distributions and estimation bounds for the maximum likelihood estimator of finite mixtures of location-scale distributions are reviewed.     

Stakeholder Green Pressure and New Product Performance in Emerging Countries: A Cross-country Study

Despite the burgeoning literature on stakeholder green pressure, research is scarce on how it influences eco-product innovation and new product performance. This article examines stakeholder green pressures as antecedents of eco-product innovation and new product performance in firms operating in resource-constrained countries. Using data gathered from surveys in Vietnam (N = 183) and Ghana (N = 217), we find that the positive effects of stakeholder green pressures on new product performance are serially mediated by environmental sustainability orientation and eco-product innovation. Our findings contribute to ongoing efforts to clarify the mechanisms channelling stakeholder pressures into new product performance in resource-constrained environments.     

A Hybrid Geometric Phase II/III Clinical Trial Design based on Treatment Failure Time and Toxicity

The problem of comparing several experimental treatments to a standard arises frequently in medical research. Various multi-stage randomized phase II/III designs have been proposed that select one or more promising experimental treatments and compare them to the standard while controlling overall Type I and Type II error rates. This paper addresses phase II/III settings where the joint goals are to increase the average time to treatment failure and control the probability of toxicity while accounting for patient heterogeneity. We are motivated by the desire to construct a feasible design for a trial of four chemotherapy combinations for treating a family of rare pediatric brain tumors. We present a hybrid two-stage design based on two-dimensional treatment effect parameters. A targeted parameter set is constructed from elicited parameter pairs considered to be equally desirable. Bayesian regression models for failure time and the probability of toxicity as functions of treatment and prognostic covariates are used to define two-dimensional covariate-adjusted treatment effect parameter sets. Decisions at each stage of the trial are based on the ratio of posterior probabilities of the alternative and null covariate-adjusted parameter sets. Design parameters are chosen to minimize expected sample size subject to frequentist error constraints. The design is illustrated by application to the brain tumor trial.     

Vietnamese American sexual behaviors & HIV infection

This brief report presents some preliminary findings of an on‐going ethnosexual field study of Vietnamese American sexual behaviors in Orange County, California, and indicates how they may be related to HIV infection. The primary objective of the study is to gather data on those sexual behaviors having the highest likelihood of transmitting the AIDS virus. The field research data indicate that in the ‘Vietnamese American population, highly acculturated Vietnamese homosexual men, whose partner preference is primarily for Anglo men with whom they play both sexual roles in anal intercourse, appear at present to be at highest risk for HIV infection. Transmission of the AIDS virus within the Vietnamese American population may be facilitated by Vietnamese American men who practice unsafe sex with both Anglo and Vietnamese men. The field research data also indicate that a potential exists for the spread of HIV into the heterosexual population through the sexual activity of Vietnamese men with non‐Vietnamese female prostitutes in California and Mexico, and through the sexual activity of ‘Vietnamese men with Thai and Vietnamese prostitutes in Thailand and Vietnam while on return visits to Southeast Asia.     

Students‘ perceptions of professional social work ethics and the need for the development of competence-based ethics standards in undergraduate training program in Vietnam

As a newly recognized profession in Vietnam over the last two decades social work has undergone significant development, both in training and practice. However, there are many challenges in its professionalization, in which ethics plays a key role. This article presents the key findings of a study about students‘ perceptions of ethics and developing competence-based ethical standards in social work programs. It first analyses the students‘ attitudes and understanding of professional ethics. Second, it clarifies the situation of ethics education in training institutions. Finally, it provides suggestions for the implementation of social work competence-based ethical standards for Vietnam and beyond.     

Bridging help-seeking options to Vietnamese Americans with parent–child conflict and depressive symptoms

To help practitioners bridge services to their clients who face family problems, this research aims to identify help-seeking behaviors among Vietnamese Americans who have experienced parent–child conflict and depression. The 2008 Asian Survey found that 46.3% of 572 Vietnamese Americans experienced parent–child conflict and 30.2% reported depressive symptoms. Having parent–child conflicts or depressive symptoms did not predict help-seeking from mental health professionals. Logistic regression results show that having parent–child conflict would increase the likelihood by 81.7% of a thinking that the problem will be naturally resolved; having depressive symptoms would increase the likelihood of seeking help from herbalists by 1.718 times and from medical doctors by 39.7%. Service strategies should include offering educational programs by multidisciplinary professionals with a focus on the natural aspect of building parent–child bonding.     

Multiple criteria approach for solving feeder assignment and assembly sequence problem in PCB assembly

The feeder assignment and assembly sequence problem in printed circuit board (PCB) assembly with the twin objectives of minimizing magazine travel time and minimizing board travel time is presented in this study. The problem uses Dynamic Pick-and-Place (DPP) model where robot arm, board and magazine move together with different speeds based on relative coordinates between consecutive assembled points. The difficulty of the problem is that the feeder assignment depends on assembly sequence and vice versa. A new approach is proposed to improve the existing approaches. The trade-off between two strategies, assembly by area and assembly by component types, can give better results. The numerical experiments proved the efficiency of the new algorithm.     

A primal-dual approximation algorithm for the Asymmetric Prize-Collecting TSP

We present a primal-dual ?log(n)?-approximation algorithm for the version of the asymmetric prize collecting traveling salesman problem, where the objective is to find a directed tour that visits a subset of vertices such that the length of the tour plus the sum of penalties associated with vertices not in the tour is as small as possible. The previous algorithm for the problem (V.H. Nguyen and T.T Nguyen in Int. J. Math. Oper. Res. 4(3):294–301, 2012) which is not combinatorial, is based on the Held-Karp relaxation and heuristic methods such as the Frieze et al.’s heuristic (Frieze et al. in Networks 12:23–39, 1982) or the recent Asadpour et al.’s heuristic for the ATSP (Asadpour et al. in 21st ACM-SIAM symposium on discrete algorithms, 2010). Depending on which of the two heuristics is used, it gives respectively 1+?log(n)? and $3+ 8\frac{\log(n)}{\log(\log(n))}$ as an approximation ratio. Our algorithm achieves an approximation ratio of ?log(n)? which is weaker than $3+ 8\frac{\log(n)}{\log(\log(n))}$ but represents the first combinatorial approximation algorithm for the Asymmetric Prize-Collecting TSP.