Hidden Markov Models with mixtures as emission distributions

In unsupervised classification, Hidden Markov Models (HMM) are used to account for a neighborhood structure between observations. The emission distributions are often supposed to belong to some parametric family. In this paper, a semiparametric model where the emission distributions are a mixture of parametric distributions is proposed to get a higher flexibility. We show that the standard EM algorithm can be adapted to infer the model parameters. For the initialization step, starting from a large number of components, a hierarchical method to combine them into the hidden states is proposed. Three likelihood-based criteria to select the components to be combined are discussed. To estimate the number of hidden states, BIC-like criteria are derived. A simulation study is carried out both to determine the best combination between the combining criteria and the model selection criteria and to evaluate the accuracy of classification. The proposed method is also illustrated using a biological dataset from the model plant Arabidopsis thaliana. A R package HMMmix is freely available on the CRAN.     

Vyāghranomics in space and time: Estimating habitat threats for Bengal,Indochinese, Malayan and Sumatran tigers

The wild tiger population in tropical Asia has dropped from about 100,000 to 3500 in the last century, and the need to conserve tiger habitats poses a challenge for the Global Tiger Recovery Program. This paper develops and uses a high-resolution monthly forest clearing database for 74 tiger habitat areas in ten countries to investigate habitat threats for Bengal, Indochinese, Malayan and Sumatran tigers. The econometric model links forest habitat loss and forest clearing to profitability calculations that are affected by market expectations, environmental conditions and evolving patterns of settlement, among others. It uses new spatial panel estimation methods that allow for temporal and spatial autocorrelation. The econometric results emphasize the role of short-run market variables, including the exchange rate, real interest rate and prices of agricultural products in forest clearing, with considerable variation in the estimated timing for response and impact elasticities across countries. The results highlight a critical message for the conservation policy community: Changes in world agricultural-product markets and national financial policies have significant, measurable effects on tropical forest clearing, with variable time lags and degrees of responsiveness across countries. Measuring these effects and pinpointing areas at risk can provide valuable guidance for policymakers, conservation managers, and donor institutions.     

The impact of a national strategy to increase physical activity among older adults on national organizations

This study was designed to evaluate the impact of the National Blueprint (NB) on the policies, programs, and organizational culture of selected national organizations. The theoretical model selected to assess the impact of the NB on organizational behavior was Burke's system theory of organizational change. Three organizations, AARP, the American College of Sports Medicine (ACSM), and the Administration on Aging (AoA), were selected for the study. Two individuals in each of these organizations were selected for interview. Semistructured interviews and document reviews were used in the data-collection process. Findings showed that the publication and establishment of the NB resulted in changes in the operating procedures of AARP, ACSM, and AoA. The results were broadly consistent with Burke's system theory of organizational change. The publication of the NB was shown to affect the behavior of organizational leaders, organizational culture, policies, programs, and individual and organizational performance. The new information generated has increased our understanding of the impact of health campaigns on organizational behavior.     

Issues in Complementary Health Insurance in Belgium

This article attempts to assess the increasing role of complementary social insurance in healthcare in Belgium. As different players attempt to fill in the lacunae of the statutory social security scheme, the demarcation of their sphere of action and of their mutual relationship is becoming problematic. It is therefore interesting to see the evolution of solidarity and selectivity. The analysis of both categories and products in complementary health insurance indicates the limitations and the bottlenecks in coming years for the social security scheme on the one hand and complementary social insurance on the other.     

Servant Leadership: A systematic review and call for future research

Notwithstanding the proliferation of servant leadership studies with over 100 articles published in the last four years alone, a lack of coherence and clarity around the construct has impeded its theory development. We provide an integrative and comprehensive review of the 285 articles on servant leadership spanning 20?years (1998–2018), and in so doing extend the field in four different ways. First, we provide a conceptual clarity of servant leadership vis-à-vis other value-based leadership approaches and offer a new definition of servant leadership. Second, we evaluate 16 existing measures of servant leadership in light of their respective rigor of scale construction and validation. Third, we map the theoretical and nomological network of servant leadership in relation to its antecedents, outcomes, moderators, mediators. We finally conclude by presenting a detailed future research agenda to bring the field forward encompassing both theoretical and empirical advancement. All in all, our review paints a holistic picture of where the literature has been and where it should go into the future.     

Physical and mental health inequalities between native and immigrant Swedes

To study health inequalities between native and immigrant Swedes, we investigated differences in self‐rated health (SRH), mental wellbeing (MW), common symptoms (CS), and persistent illness (PI), and if socioeconomic status (SES), negative status inconsistency, or social support could account for such differences. A secondary analysis was conducted on questionnaire data from a random adult population sample of 4,023 individuals and register data from Statistics Sweden. χ² tests and binary logistic regressions were used to identify health differences and study these after accounting for explanatory variables. Compared with natives, immigrants more commonly reported negative status inconsistency, poorer SES, and poorer social support as well as poor SRH, very poor MW, and high level of CS but not PI. Significant differences were accounted for by work‐related factors and social support. We encourage future research to address how pre‐ and peri‐migration factors relate to immigrants’ post‐migration SES, social support, and health status.

Policy Implications

• Given the relationship between work‐related factors (employment status, hours worked per week, and income) and all health outcomes in this study, labour market interventions that facilitate the integration of immigrants into the labour market, and into occupations that better correspond with their capacity, will arguably have public health benefits.
• Feelings of loneliness was, in our study, important in accounting for immigrants’ poorer self‐rated health compared with natives’. Therefore, we endorse interventions that facilitate immigrants’ social networking and integration and thereby reduce feelings of loneliness.
• Common physical and mental symptoms may be important indicators of health and we, thus, suggest these to be taken into account when developing ill‐health prevention programmes.

     

Patterns of Sexual Experience Among Urban Latino and African American Ninth Grade Students

This analysis assessed patterns of sexual experience, the order in which behaviors were initiated, and associated factors, among Latino and African American ninth grade students (average age 15.2) who self-administered audio-computer-assisted surveys on netbooks in classes at 10 Los Angeles–area public high schools. Lifetime experiences with vaginal and oral sex were most common (19% and 16%, respectively); fewer reported anal sex (6%). Of the 23% reporting any sex, 91% fell into four categories: 36% reporting both oral and vaginal sex; 23% vaginal only; 18% all three; and 13% oral only. Most sexually experienced students (88%) initiated with vaginal or oral sex (46% vaginal, 33% oral, 9% both same day). No dominant pathway of sexual onset emerged for those reporting all three types of sex. We found no evidence that oral or anal sex substituted for or delayed vaginal sex. Males, those with a current partner, and those reporting multiple partners were more likely than others to report all three sexual behaviors versus vaginal only (odds ratios [ORs] 2.0, 1.5, 3.0; p = .02, .06, < .01, respectively). Although vaginal intercourse dominated their early sexual behavior, one-fifth of sexually experienced students reported anal intercourse, highlighting the need for specific prevention messages surrounding this higher-risk behavior.     

“Hedge Your Bets”: Technology’s Role in Young Gay Men’s Relationship Challenges

Technology is playing an increasingly pervasive role among young gay men in the process of meeting potential romantic or sexual partners. We investigated challenges posed by technology related to young gay men’s relationships. Focus groups (n = 9) of young gay men aged 18–24 (n = 43) were transcribed verbatim, and thematic analysis was used to identify two major themes regarding challenges to relationship development and maintenance. Subthemes include unrealistic expectations of relationships, inauthentic self-presentation online, sexual primacy over romance, increased opportunities for infidelity, and jealousy. The implications of this study for sexual education and sexual health promotion are discussed.