Degradation modeling based on gamma process models with random effects

The random effects in a gamma process are introduced in terms of its scale parameter. However, the scale parameter affects both its mean and variance. Hence, the variation of the degradation rates and the within degradation increments are expected to be large. For some products, the random effects affect just the rate or just the volatility of the process. Thus, two modifications of the parameters' structure of the gamma process are proposed. One implies that the random effects affect just the volatility and the second just the rate. A Bayesian estimation approach is provided and implemented in two case studies.     

A class of beta regression models with multiplicative log-normal measurement errors

In this article, we propose a beta regression model with multiplicative log-normal measurement errors. Three estimation methods are presented, namely, naive, calibration regression, and pseudo likelihood. The nuisance parameters are estimated from a system of estimation equations using replicated data and these estimates are used to propose a pseudo likelihood function. A simulation study was performed to assess some properties of the proposed methods. Results from an example with a real dataset, including diagnostic tools, are also reported.     

Adaptation and Validation of the Polymorphous Prejudice Scale (PPS) - A Short Form In a Sample of Heterosexual Chilean College Students

ABSTRACT. Objectives: The purpose of this article is to present the psychometric characteristics of a short form of the Polymorphous Prejudice Scale (PPS; Massey, 2009), which was adapted and validated in a heterosexual Chilean population. PPS is a multidimensional measure of sexual prejudice. Methods: A nonprobabilistic (convenience) sample consisted of 422 college students. Results: Findings reveal a shortened 16-item form, grouped in four subscales, with all of the items referring to new forms of sexual prejudice. The findings showed differences based on gender, religiosity and geographic location, as hypothesized. Conclusions: Results are discussed in relation to the strengths and weaknesses of the short form of the PPS.     

Correction to: Comparison of joint control schemes for multivariate normal i.i.d. output

AStA Advances in Statistical Analysis - In the original paper, we incorrectly stated that...     

Ecological and genetic consequences of fragmentation in a semiarid Mediterranean urban forest

Urbanization threatens biodiversity worldwide and is expected to increase in the future. This involves intensification of fragmentation and increase of urban forest remnants. Thus, it is important to understand the functioning of these patches for the preservation of local biodiversity. Mutualistic interactions such as seed dispersal have a key role in the dynamics of plant populations and could help to mitigate the negative effects of fragmentation on wild plant populations. In this context, we have used the mastic Pistacia lentiscus, a common Mediterranean shrub, as a model to study the interaction between seed dispersal by birds and the local genetic diversity of individuals in a highly fragmented semiarid forestry area of the Iberian Southeast (Murcia, Spain). Results reveal a high genetic diversity and a lack of differentiation between shrub patches of P. lentiscus in the area, probably as a result of a strong, but rather recent fragmentation, and an apparently poor contribution of birds to the dispersal of Pistacia seeds. However, the existence of latent impacts cannot be discarded, since at least one of the patches shows some signs of inbreeding.     

The Grand Challenge of Reducing Gender and Racial/Ethnic Disparities in Service Access and Needs Among Adults with Alcohol Misuse

This study examined the impact of the Affordable Care Act (ACA) on gender and racial and ethnic disparities in accessing and using behavioral health services among a national sample of adults who reported heavy or binge alcohol use (n = 52,496) and those with alcohol use disorder (AUD; n = 22,966). Difference-in-differences models estimated service-related disparities before (2008–2009) and after (2011–2014) health care reform. A subanalysis was conducted before (2011–2013) and after (2014) full implementation of the ACA. Asian subgroups among respondents with heavy or binge drinking were excluded from substance use disorder (SUD) treatment and unmet need outcome models due to insufficient cell size. Among heavy or binge drinkers, unmet SUD treatment need decreased among Black women and increased among Black men. Mental health (MH) treatment decreased among Asian men, whereas unmet MH treatment need decreased among Hispanic men. MH treatment increased among Hispanic women with AUD. Although there were improvements in service use and access among Black and Hispanic women and Hispanic men, there were setbacks among Black and Asian men. Implications for social workers are discussed.     

Bivariate degradation modelling with marginal heterogeneous stochastic processes

In this paper, we consider that the degradation of two performance characteristics of a product can be modelled by stochastic processes and jointly by copula functions, but different stochastic processes govern the behaviour of each performance characteristic (PC) degradation. Different heterogeneous and homogeneous models are presented considering copula functions and different combinations of the most used stochastic processes in degradation analysis as marginal distributions. This is an important aspect to consider because the behaviour of the degradation of each PC may be different in its nature. As the joint distributions of the proposed models result in complex distributions, the estimation of the parameters of interest is performed via MCMC. A simulation study is performed to compare heterogeneous and homogeneous models. In addition, the proposed models are implemented to crack propagation data of two terminals of an electronic device, and some insights are provided about the product reliability under heterogeneous models.     

The influence of nutritional factors on prostate cancer incidence and aggressiveness

There is an increasing evidence for a link between nutrition, lifestyle and prostate cancer (PCa) development and/or progression of disease. The objective of this study was to examine the association between dietary factors and PCa incidence and aggressiveness in a case-control study. After the analysis of the anatomic pathology, subjects were classified in patients with PCa (n?=?157) and controls (n?=?158). Clinical data including Gleason score, PSA values and biopsy results, were compiled. Frequencies of food consumption and sociodemographic data were also obtained. The results showed that physical activity was significantly higher in control (p?p?=?.041) and fish (p?=?.041) intakes. Moreover, there was a significant reduction in risk (p?=?.029) in cases with a higher fruits and vegetables intakes. A decreased risk of aggressive PCa was associated with fruits, vegetables, legumes and fish intakes. However, these relationships were not statistically significant when data were adjusted for covariates. In conclusion, this study found an inverse association between PCa risk and the intake of fruits and vegetables, fish and nuts. The results suggested that a diet with higher intakes of these foods as Mediterranean diet may lower the risk of PCa in the studied population. As dietary factors are modifiable, identifying food groups or dietary patterns that modulate the risk of PCa and its aggressiveness can offer effective and practical strategies for its primary prevention.     

PI3K pathway and Bcl-2 family. Clinicopathological features in prostate cancer

The phosphatidylinositol 3-kinase (PI3K)/AKT/mTOR pathways and Bcl-2 family play a central role in prostate cancer (PC). The aim was to determine influence in the biochemical progression in PC. To evaluate the association between clinic pathological and immunohistochemical variables, Spearman’s test was performed. Log-rank test and Kaplan–Meier curves were used for survival comparisons. To explore the correlation of the studied immunohistochemical parameters and the established prognostic variables with biochemical progression, univariate and multivariate Cox proportional Hazard regression analyses were performed. Spearman analysis showed correlation between stroma expression and tumor expression of PI3K with biochemical progression (p?=?.009, p?=?.004), respectively, and tumor immunohistochemical score with biochemical progression (p?=?.051). In the multivariate Cox regression model, only PI3K was retained as independent predictors of biochemical progression. In stroma expression, PI3K is (HR 0.172, 95% CI 0.065–0.452, p?=?.000); tumor expression, PI3K is (HR 0.087, 95% CI 0.026–0.293, p?=?.000), and tumor immunohistochemical score (HR 0.382, 95% CI 0.209–0.697 p?=?.002). Our results suggest a role for prostatic expression of PI3K was prognostic markers for PC. PI3K/AKT/mTOR and Bcl-2 family are becoming an important therapeutic target and predictive biomarkers of onset and progression of PC.     

Mechanisms Linking Self-Regulation and Sexual Behaviors in Never-Married Young Adults

Little is known about specific mechanisms linking self-regulation to sexual risk taking. The present study considered four possibilities in emerging adulthood: sexual self-restraint, consideration of future consequences, substance use, and romantic competence. Never-married young adults (N = 274), ages 18 to 24, responded to anonymous Internet surveys (60.2% female, 78.8% European American, 66.3% university students). The effects of self-regulation were primarily indirect but varied by sexual behavior, suggesting that high self-regulation limits sexual risk via high sexual self-restraint and low substance use. High regulation was linked to multiple sexual partners and high-risk practices risk via high romantic competence, high self-regulation was linked to multiple sexual partners and high risk practices.