A Necessary Condition for the Strong Oracle Property

A problem of using a non‐convex penalty for sparse regression is that there are multiple local minima of the penalized sum of squared residuals, and it is not known which one is a good estimator. The aim of this paper is to give a guide to design a non‐convex penalty that has the strong oracle property. Here, the strong oracle property means that the oracle estimator is the unique local minimum of the objective function. We summarize three definitions of the oracle property – the global, weak and strong oracle properties. Then, we give sufficient conditions for the weak oracle property, which means that the oracle estimator becomes a local minimum. We give an example of non‐convex penalties that possess the weak oracle property but not the strong oracle property. Finally, we give a necessary condition for the strong oracle property.     

A nonparametric hypothesis test for heteroscedasticity

In this paper, a hypothesis test for heteroscedasticity is proposed in a nonparametric regression model. The test statistic, which uses the residuals from a nonparametric fit of the mean function, is based on an adaptation of the well-known Levene's test. Using the recent theory for analysis of variance when the number of factor levels goes to infinity, the asymptotic distribution of the test statistic is established under the null hypothesis of homocedasticity and under local alternatives. Simulations suggest that the proposed test performs well in several situations, especially when the variance is a nonlinear function of the predictor.     

Effects of a ball-backrest chair on the muscles associated with upper crossed syndrome when working at a VDT

This study examined the effect of a ball-backrest chair on the weakness and tightness of muscles associated with upper crossed syndrome when working at a visual display terminal (VDT). The surface electromyography (EMG) was recorded from the serratus anterior, middle trapezius, and upper trapezius muscles of 20 adults as they performed VDT work, which are known as the weakened and tightened muscles of upper crossed syndrome. The recorded signals were averaged and normalized to the mean amplitude of the EMG signal obtained during submaximal reference voluntary contractions. The significance of differences between the use of a general-purpose backrest and a ball backrest was tested by paired t-test, with the significance cutoff set at alpha=0.05. The activities of the serratus anterior and middle trapezius muscles increased and that of the upper trapezius muscle decreased when sitting in a ball-backrest chair compared to when sitting in a chair with a general-purpose backrest (p<0.05). These results indicate that the use of a ball-backrest chair reduces the risk of patients with upper crossed syndrome developing muscles soreness or injury related to overuse when working at a VDT.     

Urge to Gamble in Problem Gamblers Exposed to a Casino Environment

Cue-reactivity has received increased attention in addiction research, though not for gambling in particular. We examined cue reactivity in 18 problem gamblers by accompanying them to a gaming casino and measuring their subjective urge to gamble over a 1-h period. Half of the sample was additionally exposed to a gambling-specific negative mood induction (NMI) manipulation via guided imagery. Overall, about two-thirds of the sample reported moderate to high-gambling urges during the casino exposure. Additionally, the NMI reduced cue-reactivity. Finally, gambling urges in both groups decreased over the course of the exposure sessions. These findings suggest that a majority of problem gamblers experience the urge to gamble when exposed to gambling cues and that the intensity of these urges decrease with time, especially in the presence of a gambling-relevant NMI. Cue exposure should be studied further as a potential tool in the treatment of problem gambling.     

The life-course origins of mastery among older people

In this article, we aim to identify the sources of mastery--the understanding that individuals hold about their ability to control the circumstances of their lives. The sample for our inquiry was drawn from the Medicare beneficiary files of people 65 and older living in Washington, DC, and two adjoining Maryland counties. We find that past circumstances, particularly those reflecting status attainment and early exposure to intractable hardships, converge with stressors experienced in late life to influence elders' level of mastery. The impact of past conditions, however, does not necessarily directly affect the current mastery of older people. Instead, the effect of prior experiences on current mastery is mediated by what we refer to as life-course mastery: one's belief that one has directed and managed the trajectories that connect one's past to the present. Our analyses show that life-course mastery largely serves as the mediating channel through which individuals connect their past to their present.     

Integrative Cycle Scheduling Approach for a Capacitated Flexible Assembly System*

This study revisits the traditional single stage, multi-item, capacitated lot-sizing problem (CLSP) with a new integrative focus on problem structuring. Unlike past research, we develop integrative cycle scheduling approaches which simultaneously address lot-sizing, capacity, and sequencing issues. Our purposes are to (1) explore the effect of sequencing on inventory levels, (2) examine the problem of infeasibility in the economic lot scheduling problem (ELSP), and (3) provide a simple methodology of generating low-cost cycle schedules in an environment with discrete shipping, dynamic demands, limited capacity, zero setup cost, and sequence-independent setup times. Our procedures are compared to benchmark cycle scheduling approaches in terms of both inventory cost and computation time under different demand scenarios, using the operating data from a flexible assembly system (FAS) at the Ford Motor Company's Sandusky, Ohio plant.     

Issue Information

In 2017, the number of applications for care orders in England and Wales was the highest ever recorded at 14,207. This is a significant factor, contributing to the rise in the number of children who are looked after, which is at the highest level since 1985. The authors reflect on the recently published Care Crisis Review 2018, a sector‐led review, which examines the reasons for the rise in care proceedings and the number of children in care. The review sought to identify changes to policy and practice within local authorities and the family justice system, in an attempt to divert cases away from the family courts and to reduce the number of children in care, where it is safe to do so. Whilst the legislative framework is largely effective and the system generally works well, there is insufficient funding and resources to meet the needs of children and their families when they seek help, regardless of whether this is at an early stage or when they are in crisis and most in need of care and protection.     

We Don’t Belong Here: Adolescents of North Korean Refugee Families and Their Suicidal Behaviors

Despite the increasing number of studies that examine the link between immigration and suicide in Korean youths, most have focused on self-harming behaviours among adolescents in multicultural families, while much less attention has been directed towards those in North Korean (NK) refugee families. This paper addresses this gap by comparing three determinants of suicidal behaviours across three groups of Korean adolescents. Data are drawn from the KYRBS, a nationally representative sample of students in middle and high schools, and the results indicate that NK youths were 87.2 per cent more likely to have suicidal ideation than their South Korean peers, that they are 3.7 times more likely to experience suicidal plans and 4.1 times more likely to attempt suicide. These results clearly suggest that immigrant youths, including NK refugees, are confronting significant difficulties with assimilation, and those disadvantages lead to a higher propensity of self-threatening behaviours.     

Social investment effects of public education,health care,and welfare service expenditures on economic growth

The purpose of this study is to theoretically and empirically examine whether public spending in education, health care, and welfare service operates as a fruitful investment in welfare states, which has been implied in the literature of social investment arguments. Based on comprehensive review of existing literature, this study suggested a tripartite mechanism of social investment effect of such spending, that is “enhancement of human capital,” “support for labor force participation,” and “job creation.” To find the empirical evidence, a pooled time‐series cross‐section analysis was conducted with the data of 15 advanced welfare states from 1980 to 2015 using estimation technique of fixed‐effect model. The results confirmed that public spending in education, health care, and welfare service had a positive medium‐term as well as long‐term effect on economic performance, while cash‐type welfare spending had an obscure or no visible effect on economy. Government consumption that is a proxy and control variable of size of the welfare state showed a positive effect on real GDP in the medium term but a negative effect in the long run. In conclusion, this study suggests that reinforcing social services should be recognized and dealt with as essence of social investment strategy.