'A travel cost analysis of the value of Carnarvon Gorge National Park for recreational use': reprise

Resource /Energy Economics and Policy,

Dispersion processes

We study a synchronous dispersion process in which $M$ particles are initially placed at a distinguished origin vertex of a graph $G$. At each time step, at each vertex $v$ occupied by more than one particle at the beginning of this step, each of these particles moves to a neighbour of $v$ chosen independently and uniformly at random. The dispersion process ends once the particles have all stopped moving, i.e. at the first step at which each vertex is occupied by at most one particle. For the complete graph $K_n$ and star graph $S_n$, we show that for any constant $\delta>1$, with high probability, if $M \le n/2(1-\delta)$, then the process finishes in $O(\log n)$ steps, whereas if $M \ge n/2(1+\delta)$, then the process needs $e^{\Omega(n)}$ steps to complete (if ever). We also show that an analogous lazy variant of the process exhibits the same behaviour but for higher thresholds, allowing faster dispersion of more particles. For paths, trees, grids, hypercubes and Cayley graphs of large enough sizes (in terms of $M$) we give bounds on the time to finish and the maximum distance traveled from the origin as a function of the number of particles $M$

Why do we invest ethically?

Analysis in this paper has proposed three potential motives for ethical investment - financial returns, non-wealth returns and social change. The motives are developed from the literature and illustrated in the context of a 'best of sector' fund and a socially screened fund. We find that the proposed motives are neither exhaustive nor exclusive and one single motive will not explain the behaviour of all ethical investors. There may be a trade-off between financial and psychic returns for some investors. The trade-off for consumption-investors is expected to be close to zero (total utility is maximised with small levels of ethical investment in the fun of participation model) and is expected to vary with the ethical intensity of investment-investors, as shown when we include ethical intensity into the investor's utility function. Psychic return can also be viewed as an increase in happiness and this approach would lend itself to empirical testing to increase our understanding of why we invest ethically

Understanding Health Risks for Adolescents in Protective Custody

Children in child welfare protective custody (e.g., foster care) are known to have increased health concerns compared to children not in protective custody. The poor health documented for children in protective custody persists well into adulthood; young adults who emancipate from protective custody report poorer health, lower quality of life, and increased health risk behaviors compared to young adults in the general population. This includes increased mental health concerns, substance use, sexually transmitted infections, unintended pregnancy, and HIV diagnosis. Identifying youth in protective custody with mental health concerns, chronic medical conditions, and increased health risk behaviors while they remain in custody would provide the opportunity to target prevention and intervention efforts to curtail poor health outcomes while youth are still connected to health and social services. This study leveraged linked electronic health records and child welfare administrative records for 351 youth ages 15 and older to identify young people in custody who were experiencing mental health conditions, chronic medical conditions, and health risk behaviors (e.g., substance use, sexual risk). Results indicate that 41.6% of youth have a mental health diagnosis, with depression and behavior disorders most common. Additionally, 41.3% of youth experience chronic medical conditions, primarily allergies, obesity, and vision and hearing concerns. Finally, 39.6% of youth use substances and 37.0% engage in risky sexual behaviors. Predictors of health risks were examined. Those findings indicate that women, those with longer lengths of stay and more times in custody, and those in independent living and conjugate care settings are at greatest risk for mental health conditions, chronic medical conditions, and health risk behaviors. Results suggest a need to ensure that youth remain connected to health and mental health safety nets, with particular attention needed for adolescents in care for longer and/or those placed in non-family style settings. Understanding who is at risk is critical for developing interventions and policies to target youth who are most vulnerable for increased health concerns that can be implemented while they are in custody and are available to receive services

Linear State-Space Model with Time-Varying Dynamics

This paper introduces a linear state-space model with time-varying dynamics. The time dependency is obtained by forming the state dynamics matrix as a time-varying linear combination of a set of matrices. The time dependency of the weights in the linear combination is modelled by another linear Gaussian dynamical model allowing the model to learn how the dynamics of the process changes. Previous approaches have used switching models which have a small set of possible state dynamics matrices and the model selects one of those matrices at each time, thus jumping between them. Our model forms the dynamics as a linear combination and the changes can be smooth and more continuous. The model is motivated by physical processes which are described by linear partial differential equations whose parameters vary in time. An example of such a process could be a temperature field whose evolution is driven by a varying wind direction. The posterior inference is performed using variational Bayesian approximation. The experiments on stochastic advection-diffusion processes and real-world weather processes show that the model with time-varying dynamics can outperform previously introduced approaches.Comment: The final publication is available at Springer via http://dx.doi.org/10.1007/978-3-662-44851-9_2

Photographs of Botanists

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Adolescents Occupational and Educational Goals: A Test of Reciprocal Relations

During adolescence, young people’s future aspirations and expectations begin to crystallize, especially in the domains of education and occupation. Much of the research in this area has emphasized development within a particular domain (e.g., education) and relations between aspirations and expectations across domains remain largely unexplored, resulting in a lack of information on how goals develop in tandem and affect each other. It is also unclear whether these developmental processes differ by gender and socioeconomic status. We tested reciprocal effects between occupational and educational goals using a longitudinal sample of 636 adolescents (52% boys). Results from dynamic systems models indicated change in occupational and educational goals across high school. For all youth, occupational aspirations predicted change in occupational expectations. Educational expectations predicted change in occupational aspirations for youth in high but not low parent education groups, and occupational expectations predicted change in educational expectations for girls but not boys

Who Speaks for Me?: Addressing Variability in Informed Consent Practices for Minimal Risk Research Involving Foster Youth

Background: Youth in protective custody (i.e., foster care) are at higher risk for poorer physical and mental health outcomes compared with those who are not. These differences may be due in part to the lack of research on the population to create evidence-based recommendations for health care delivery. A potential contributor to this lack of research is difficulties in obtaining informed consent for empirical studies in this population. The objective of this study was to describe the approaches to obtaining informed consent in minimal risk studies of foster youth and provide recommendations for future requirements. Methods: We conducted a systematic review of the literature to characterize the informed consent approaches in published minimal risk research involving youth in foster care. We searched PubMed, CINAHL, PsychINFO, Embase, ERIC, Scopus, and EBMR. Inclusion criteria were: studies conducted in the United States, included current foster youth, minimal risk, peer reviewed, and published in English. Full text was reviewed, and individuals required to consent and assent were extracted. Results: Forty-nine publications from 33 studies were identified. Studies required 0 to 3 individuals to consent. Individuals required to give consent included case workers (16, 48%), foster caregivers (12, 36%), biological parents (7, 21%), judges (5, 15%), and guardian ad litems (2, 6%). Twenty-nine (88%) studies required the youth’s assent. The studies used 14 different combinations of individuals. One (3%) study utilized a waiver of consent. Conclusions: There is no consistent approach for obtaining informed consent for foster youth to participate in minimal risk research. Consent should ideally involve individuals with legal authority and knowledge of the individual youth’s interests and should not be burdensome. Consensus regarding consent requirements may facilitate research involving foster youth