Mixed-Mode Oscillations Due to a Singular Hopf Bifurcation in a Forest Pest Model

In a forest pest model, young trees are distinguished from old trees. The pest feeds on old trees. The pest grows on a fast scale, the young trees on an intermediate scale, and the old trees on a slow scale. A combination of a singular Hopf bifurcation and a “weak return” mechanism, characterized by a small change in one of the variables, determines the features of the mixed-mode oscillations. Period-doubling and saddle-node bifurcations lead to closed families (called isolas) of periodic solutions in a bifurcation corresponding to a singular Hopf bifurcation.     

Prosodic Modification and Vocal Adjustments in Mothers' Speech During Face‐to‐face Interaction with Their Two‐ to Four‐month‐old Infants: A Double Video Study

The purpose of this study was to examine 32 mothers' sensitivity to social contingency during face‐to‐face interaction with their two‐ to four‐month‐old infants in a closed circuit TV set‐up. Prosodic qualities and vocal sounds in mother's infant‐directed (ID) speech during sequences of live interaction were compared to sequences where expressive behaviours were decoupled by presenting either the mothers (Replay 2) or the infants (Replay 1) with a replay record of the partners' former behaviour in a Live 1–Replay 1–Live 2–Replay 2–Live 3 design. Overall, the mothers produced significantly higher amount of ID speech during the live sequences. Compared to the Live 1 sequence, there was a significant reduction in mothers' ID speech during both replay sequences. However, the mothers only recovered ID speech after the Replay 2 sequence, not after the Replay 1. These findings suggest that the emotions signalled by the mothers' ID speech is affected by the contingency of the infant responses.     

Child Labour in West Africa: Different Work – Different Vulnerabilities

Based on data from four different surveys – street children in Accra, Ghana; street children in Bamako, Mali; children and youth in alluvial-diamond production in Kono district, Sierra Leone; and war-affected children in Voinjama district, Liberia – this article analyzes how children and youth seek to use different economic strategies to shape their lives. In each of these cases, child labour is a consequence of poverty, steep school fees and the family need for the income that the children can earn. The results show school attendance among the children is low, and lowest among the street children and highest among the children in Voinjama who have recently returned after the war. All the children in this article live under difficult circumstances, but those working in the mines, or living a life as street children are particularly prone to respectively physical and mental stress. The type of labour performed in the alluvial diamond mines is extremely hard and repetitive. The life of a street child in West Africa is also very hard. It is a life that only the boldest and bravest will endure. The most fortunate ones are the returnee children in Voinjama. They have survived the Liberian civil war with their family or family-related networks intact. The children in the study are not just passive victims of structures and actions they do not comprehend, but also people who try to adapt to a situation where education is less an option than it used to be. Faced with these constraints the children, either as miners or as street children, try to assume responsibility for their lives by the choice of the economic strategy that they are currently using. The study also indicates that efforts to support these groups should pay more attention to their lived realities of work and migration.     

New perspectives on board research: changing the research agenda

Scholars and practitioners have recently devoted considerable attention to boards of directors, but far more research is needed. We still know little about how boards actually work and how their behavior may be improved to contribute to value creation. During more than two decades agency theory has been the dominant theory in studies about boards of directors. When relaxing some of the assumptions in agency theory several new pathways for new research arise. To present new perspectives on board research we follow in this essay some of the pathways arising from relaxing agency theory assumptions about complete contracts. Alternative theoretical approaches, research questions and methods are suggested.     

Agencification and Location: Does Agency Site Matter?

Two decades of New Public Management have placed agencifiction high on the agenda of administrative policy-makers. However, agencification (and de-agencification) has been one of the enduring themes of public administration. Agencies organized at arm’s length from ministerial departments have fairly often been located outside of the capital or political centre. Although practitioners tend to assign some weight to central versus peripheral location as regards political-administrative behavior, this relationship has been almost totally ignored by scholars in the field. In this paper, based on a large-N elite survey, we show that agency autonomy, agency influence and inter-institutional coordination seem to be relatively unaffected by agency site. This study also specifies some conditions under which this finding is valid.     

Examining the trajectories of children providing care for adults in rural Kenya: Implications for service delivery

Research on caregiving children tends to be limited to children's caregiving experiences of parents with a specific disease or disability. This has led to a common perception that children's caregiving is a single, uniform and often long-term experience. Whilst this is most certainly the case for many children in economically more advanced countries, this may not hold true in rural Africa, where poverty and AIDS can have significant knock-on effects on entire families and communities. This paper seeks to develop a more complex understanding of children's caring experiences by asking children whom they have cared for over time and explore the different pathways that lead to their caregiving at different stages of their lives. The study reports on qualitative data collected from 48 caregiving children and 10 adults in the Bondo district of western Kenya in 2007. A multi-method approach was adapted, with historical profiles, Photovoice and draw-and-write essays complementing 34 individual interviews and 2 group discussions. A thematic network analysis revealed that children's caregiving was not confined to a single experience. Children were observed to provide care for a number of different family and community members for varying periods of time and intensities. Although their living arrangements and life circumstances often gave them little choice but to care, a social recognition of children's capacity to provide care for fragile adults, helped the children construct an identity, which both children and adults drew on to rationalise children's continued and multiple caring experiences. The study concludes that agencies and community members looking to support caregiving children need to consider their care trajectories — including whom they care for as well as the order, intensity, location and duration of their past and likely future caring responsibilities.     

Are transformational and laissez-faire leadership related to state anxiety among subordinates? A two-wave prospective study of forward and reverse associations

ABSTRACT

The aim of this study was to determine the direction of associations between perceived leadership styles of an immediate leader and state anxiety among subordinates using time-lagged data from a large and heterogeneous probability sample of Norwegian employees. It was hypothesised that high levels of transformational leadership would be associated with a decrease, whereas high levels of laissez-faire leadership would be associated with an increase, in subsequent levels of anxiety. Reciprocal associations were also expected in that higher levels of anxiety were hypothesised to be related to subsequent increase in reports of laissez-faire, and decrease in reported exposure to transformational leadership. The sample comprised 1149 Norwegian employees. The design was a two-wave full panel study with a six-month time interval between the baseline and follow-up assessments. Contrary to hypotheses, neither transformational nor laissez-faire leadership were significantly related to subsequent levels of state anxiety. In support of hypotheses, baseline low levels of state anxiety were associated with reporting the immediate leader as less transformational and more laissez-faire six months later. In conclusion, the findings challenge theoretical models that explain leadership as a one-way superior–subordinate influence process.     

Disordered Gambling Prevalence: Methodological Innovations in a General Danish Population Survey

We study Danish adult gambling behavior with an emphasis on discovering patterns relevant to public health forecasting and economic welfare assessment of policy. Methodological innovations include measurement of formative in addition to reflective constructs, estimation of prospective risk for developing gambling disorder rather than risk of being falsely negatively diagnosed, analysis with attention to sample weights and correction for sample selection bias, estimation of the impact of trigger questions on prevalence estimates and sample characteristics, and distinguishing between total and marginal effects of risk-indicating factors. The most significant novelty in our design is that nobody was excluded on the basis of their response to a ‘trigger’ or ‘gateway’ question about previous gambling history. Our sample consists of 8405 adult Danes. We administered the Focal Adult Gambling Screen to all subjects and estimate prospective risk for disordered gambling. We find that 87.6% of the population is indicated for no detectable risk, 5.4% is indicated for early risk, 1.7% is indicated for intermediate risk, 2.6% is indicated for advanced risk, and 2.6% is indicated for disordered gambling. Correcting for sample weights and controlling for sample selection has a significant effect on prevalence rates. Although these estimates of the ‘at risk’ fraction of the population are significantly higher than conventionally reported, we infer a significant decrease in overall prevalence rates of detectable risk with these corrections, since gambling behavior is positively correlated with the decision to participate in gambling surveys. We also find that imposing a threshold gambling history leads to underestimation of the prevalence of gambling problems.     

Subjective Economic Status in Adolescence: Determinants and Associations with Mental Health in the Norwegian Youth@Hordaland Study

We aimed to identify factors associated with perceived economic well-being (PEWB), and examine its association with symptoms of depression and attention-deficit/hyperactivity disorder. In the Norwegian youth@hordaland study, 9166 16–19-year-olds provided information on perceived economic well-being and relevant covariates. Information about families’ income-to-needs was obtained from tax return forms. Adolescents in households with a low income-to-needs ratio, with non-working parents, and in single-parent households were more likely to report poor PEWB. Adolescents with poor PEWB reported more symptoms of depression and ADHD, also after adjusting for covariates, including income-to-needs. There was a significant indirect effect of income-to-needs on mental health problems though PEWB. The current study demonstrates the role of PEWB as a contributor in the pathway from social inequalities to disparities in mental health.