An Improved Test for Continuous Local Martingales

We present a new test for the “continuous martingale hypothesis”. That is, a test for the hypothesis that observed data are from a process which is a continuous local martingale. The basis of the test is an embedded random walk at first passage times, obtained from the well-known representation of a continuous local martingale as a continuous time-change of Brownian motion. With a variety of simulated diffusion processes our new test shows higher power than existing tests using either the crossing tree or the quadratic variation, including the situation where non-negligible drift is present. The power of the test in the presence of jumps is also explored with a variety of simulated jump diffusion processes. The test is also applied to two sequences of high-frequency foreign exchange trade-by-trade data. In both cases the continuous martingale hypothesis is rejected at times less than hourly and we identify significant dependence in price movements at these small scales.     

On a Class of Distributions Defined by the Relationship Between Their Density and Distribution Functions

Knowledge concerning the family of univariate continuous distributions with density function f and distribution function F defined through the relation f(x) = F ^α(x)(1 ? F(x))^β, α, β ? , is reviewed and modestly extended. Symmetry, modality, tail behavior, order statistics, shape properties based on the mode, L-moments, and—for the first time—transformations between members of the family are the general properties considered. Fully tractable special cases include all the complementary beta distributions (including uniform, power law and cosine distributions), the logistic, exponential and Pareto distributions, the Student t distribution on 2 degrees of freedom and, newly, the distribution corresponding to α = β = 5/2. The logistic distribution is central to some of the developments of the article.     

Effect of pavement and water deficit on biomass allocation and whole-tree transpiration in two contrasting urban tree species

Urban Ecosystems - Aiming to explore the species-specific responses of biomass allocation and whole-tree transpiration in urban trees to pavement and drought, a field manipulation experiment grew...     

Sex Work in a Digital Era

In recent years, scholars have begun to investigate the role of digital technologies, namely the Internet, in facilitating growth in sexual commerce. Recent studies investigate the ways the Internet shapes the experiences of sex workers and how sex workers use the Internet to maximize profits and reduce risk exposure. Overall, scholars strategically frame sex work in a digital era in terms of affordances. In doing so, they can note the positive changes in the work experiences of these workers. However, I argue that this literature is altogether too optimistic, and in focusing primarily on the affordances of Internet‐based sex work, these scholars neglect the new dangers that emerge online. In addition, by focusing only on the online practices of escorts, these scholars paint a homogenized portrait of digital sex work and neglect the diversity of labor performed by sex workers. This literature also neglects the diversity among sex workers themselves (e.g., race, ethnicity, class, gender, age, and ability). In order to address these limitations, I make nine specific suggestions for future lines of inquiry.     

Impulsivity as a Risk Factor for HIV Transmission in Men Who Have Sex with Men: A Delay Discounting Approach

Delay discounting (DD) is a measure of impulsivity that describes the subjective decline in value of a consequence as the delay to that consequence increases. We sought to assess whether the results of a monetary DD task would be predictive of sexual risk-taking in a group of Internet-using men who have sex with men (MSM). 1402 participants completed an online survey that included questions about the participant’s demographics, sexual history and behavior, drug use, sexual compulsivity, and a monetary DD task. High DD was associated with increased odds of reporting >2 UAI partners in the past 12 months [aOR = 1.5 (1.1–2.1)]. Future studies should examine the utility of DD as a predictor of risky sexual behavior, as well as explore the possibility of HIV prevention interventions targeting DD.     

How to conduct a Narrative Policy Framework study

The Narrative Policy Framework has a growing number of researchers seeking to apply the framework in policy process scholarship. This article is intended to assist those interested in conducting an NPF study that is ‘clear enough to be wrong’ (Sabatier, 2000). While graduate programs offer critical methodological training, this article focuses on the specific application of the NPF to research inquiries about the role of policy narratives in the policy process. We approach our discussion by examining various decisions in the research process and include a detailed discussion of specifying the model and obtaining narrative data. We also point out areas for further investigation.     

Predicting Condom Use Outcomes via the Information Motivation Behavioral Skills Model: An Analysis of Young Black Men

Objectives: This study examines the relationships between information motivation behavioral skills model constructs and their associations with consistent condom use and condom use problems among young Black men. Methods: The authors use baseline data collected from 702 participants in a randomized controlled trial. Analyses involved path modeling and bootstrapped standard errors to estimate associations. Results: Motivation had the largest association with consistent condom use, whereas condom application skills had the largest association with condom use problems. Conclusion: Motivation is the most important predictor of consistent condom use, whereas condom application skills are the most important predictor of condom use problems.     

Children of prisoners: exploring the impact of families' reappraisal of the role and status of the imprisoned parent on children's coping strategies

Qualitative data from a larger study on the impact of parental imprisonment in four countries found that children of prisoners face fundamentally similar psychological and social challenges. The ways that children cope, however, are influenced by the interpretative frame adopted by the adults around them, and by how issues of parental imprisonment are talked about in their families. This article argues that families have to reappraise their view of the imprisoned parent and then decide on their policy for how to deal with this publicly. Their approach may be based on openness and honesty or may emphasise privacy and secrecy, or a combination of these. Children are likely to be influenced by their parents'/carers' views, although these may cause conflict for them. Where parents/carers retain a positive view of the imprisoned parent, children are likely to benefit; where parents/carers feel issues of shame and stigma acutely, this is likely to be transmitted to their children. This is important for social workers and practitioners involved in supporting prisoners' families and for parenting programmes.