Ethics, Logs and Videotape: Ethics in Large Scale User Trials and User Generated Content. Workshop organized at CHI'11.

Mobile Life CentreMobile 2.

Indifference to Difference: Factors Related to Recognizing and Responding to Students with Symptoms of Depression

Depression is a significant problem in university students, and the majority of students who identify as depressed are not receiving treatment (American College Health Association, 2013). In response to the significant underutilization of treatment amongst depressed college students, colleges and universities recently have begun to depend on fellow students, faculty, and staff to recognize and respond to at-risk students. These campus community members are often on the “front lines” of dealing with troubled students (Kitzrow, 2009). However, research has not kept up with the increasing practice of using laypeople to identify and make appropriate referrals, so the variables influencing the effectiveness of this practice are unknown. Therefore, the purpose of the study was to explore specific variables hypothesized to impact student, faculty, and staff members’ recognition and response to a hypothetical student’s depression symptoms. Using a theoretical framework informed by mental health literacy (Jorm, 2000), the research utilized a pilot study to develop three vignettes that differed by depression severity. The larger dissertation study was implemented with 1,625 university students, faculty, and staff to investigate the relations between the vignette depression severity, demographic factors, perceived severity of depression, and response behaviors. Results indicated that the university community could distinguish between differing presentations of depression, and could differentially select responses to a hypothetical depressed student which were consistent with their perceived depression severity. In addition, consistent with previous research, men and people with no prior mental health experience reported responding with less intensity relative to women and those with certain mental health experience. Findings are explored in the context of a university that experienced a recent tragedy. The study concludes with a discussion of implications for policy and future research

Cell-Type Specific Changes in Glial Morphology and Glucocorticoid Expression During Stress and Aging in the Medial Prefrontal Cortex.

Repeated exposure to stressors is known to produce large-scale remodeling of neurons within the prefrontal cortex (PFC). Recent work suggests stress-related forms of structural plasticity can interact with aging to drive distinct patterns of pyramidal cell morphological changes. However, little is known about how other cellular components within PFC might be affected by these challenges. Here, we examined the effects of stress exposure and aging on medial prefrontal cortical glial subpopulations. Interestingly, we found no changes in glial morphology with stress exposure but a profound morphological change with aging. Furthermore, we found an upregulation of non-nuclear glucocorticoid receptors (GR) with aging, while nuclear levels remained largely unaffected. Both changes are selective for microglia, with no stress or aging effect found in astrocytes. Lastly, we show that the changes found within microglia inversely correlated with the density of dendritic spines on layer III pyramidal cells. These findings suggest microglia play a selective role in synaptic health within the aging brain

Microeconomic Heterogeneity and Macroeconomic Policy

This dissertation is part of a growing body of research studying the implications of micro heterogeneity - differences between different types of households and workers - for macro economic policy. By incorporating heterogeneity into monetary and fiscal policy frameworks, I am able to study both the distributional consequences of policy and uncover ways in which differences between households change policy transmission mechanisms. In the first chapter, I show that growing differences across the income distribution in workers' substitutability with capital alters the strength of a key monetary policy transmission mechanism. In the second chapter, I highlight and measure a new trade-off between redistribution policies and long-run investment stemming from differences in households' propensity to save out of permanent income. In the third chapter, joint with Jennifer La'O, we show that when the degree of labor income inequality changes over the business cycle, and fiscal policy is unable to respond to these changes, optimal monetary policy should take this inequality into account. Chapter 1 examines how heterogeneity in worker substitutability with capital affects the labor income channel of monetary policy. Empirically, I show that workers performing routine tasks see smaller labor income gains than other workers following a monetary expansion and have higher marginal propensities to consume (MPC). I show that this relationship dampens the role that the labor market plays in monetary policy transmission. I embed capital-task complementarity in a medium-scale HANK model calibrated to match the respective capital-labor elasticities and labor shares of routine and non-routine workers. This worker heterogeneity reduces the size of the labor income channel 25 percent. Chapter 2 studies the trade-offs associated with income redistribution in an overlapping generations model in which savings rates increase with permanent income. By transferring resources from high savers to low savers, redistribution lowers aggregate savings, and depresses investment. I derive sufficient conditions under which this savings behavior generates a welfare trade-off between permanent income redistribution and capital accumulation in the short and long run. I quantify the size of this trade-off in two ways. First, I derive a sufficient statistic formula for the impact of this channel on welfare, and estimate the formula using U.S. household panel data. When redistribution is done with a labor income tax, the welfare costs associated with my channel are around 1/3 the size of those associated with labor supply distortions. Second, I solve a quantitative overlapping generations model with un-insurable idiosyncratic earnings risk in which savings rates increase with permanent income calibrated to the U.S. in 2019. In this setting, I find that around 17 percent of the trade-off between labor income redistribution and average consumption can be attributed to my channel. In Chapter 3, joint with Jennifer La'O, we study optimalmonetary policy in a dynamic, general equilibrium economy with heterogeneous agents. All heterogeneity is ex-ante: workers differ in type-specific, state-contingent labor productivity, yet markets are complete. The fiscal authority has access to a uniform, state-contingent lump-sum tax (or transfer), but linear taxes are restricted to be non-state contingent. We derive sufficient conditions under which implementing flexible-price allocations is optimal. We show that such allocations are not optimal when the relative labor income distribution varies with the business cycle; in such cases, optimal monetary policy implements a state-contingent mark-up that co-moves positively with a sufficient statistic for labor income inequality

Analyzing and mapping fish assemblages off central California, USA

This study describes fish assemblages and their spatial patterns off the coast of California from Point Arena to Point Sal, by combining the results of the multivariate analyses of several fisheries datasets with a geographic information system. In order to provide comprehensive spatial coverage for the areas of inshore, continental shelf, and continental slope, three fisheries datasets were analyzed: 1) Inshore: the California Department of Fish and Game dataset of fishery-dependent commercial passenger fishing vessel trips that targeted rockfish; 2) Continental Shelf: the National Marine Fisheries Service (NMFS) fishery-independent bottom trawls; and 3) Continental Slope: the NMFS fishery-independent bottom trawls on the continental slope. One-hundred seven species were analyzed. These species represented those captured in at least 5% of the fishing trips or trawls in at least one of the three data sets. We analyzed each of the three datasets separately, and the three sets of results were combined to define 28 species assemblages and 23 site groups. A species assemblage consisted of species caught together, whereas a site group consisted of fishing trips or trawl locations that tended to have the same species assemblages. At the scale of these datasets, 97% of all site groups were significantly segregated by depth

Evaluation of multi-segmental kinematic modelling in the paediatric foot using three concurrent foot models

Background: Various foot models are used in the analysis of foot motion during gait and selection of the appropriate model can be difficult. The clinical utility of a model is dependent on the repeatability of the data as well as an understanding of the expected error in the process of data collection. Kinematic assessment of the paediatric foot is challenging and little is reported about multi-segment foot models in this population. The aim of this study was to examine three foot models and establish their concurrent test-retest repeatability in evaluation of paediatric foot motion during gait. Methods: 3DFoot, Kinfoot and the Oxford Foot Model (OFM) were applied concurrently to the right foot and lower limb of 14 children on two testing sessions. Angular data for foot segments were extracted at gait cycle events and peaks and compared between sessions by intraclass correlation coefficient (ICC) with 95% confidence intervals (95% CI) and standard error of measurement (SEM). Results: All foot models demonstrated moderate repeatability: OFM (ICC 0.55, 95% CI 0.16 to 0.77), 3DFoot (ICC 0.47, 95% CI 0.15 to 0.64) and Kinfoot (ICC 0.43, 95% CI −0.03 to 0.59). On the basis of a cut-off of 5°, acceptable mean error over repeated sessions was observed for OFM (SEM 4.61° ± 2.86°) and 3DFoot (SEM 3.88° ± 2.18°) but not for Kinfoot (SEM 5.08° ± 1.53°). Reliability of segmental kinematics varied, with low repeatability (ICC < 0.4) found for 14.3% of OFM angles, 22.7% of 3DFoot angles and 37.6% of Kinfoot angles. SEM greater than 5° was found in 26.2% of OFM, 15.2% of 3DFoot, and 43.8% of Kinfoot segmental angles. Conclusion: Findings from this work have demonstrated that segmental foot kinematics are repeatable in the paediatric foot but the level of repeatability and error varies across the segments of the different models. Information on repeatability and test-retest errors of three-dimensional foot models can better inform clinical assessment and advance understanding of foot motion during gait

A systematic review of digital interventions for improving the diet and physical activity behaviors of adolescents

Many adolescents have poor diet and physical activity behaviors, which can lead to the development of noncommunicable diseases in later life. Digital platforms offer inexpensive means of delivering health interventions, but little is known about their effectiveness. This systematic review was conducted to synthesize evidence on the effectiveness of digital interventions to improve diet quality and increase physical activity in adolescents, to effective intervention components and to assess the cost-effectiveness of these interventions. Following a systematic search, abstracts were assessed against inclusion criteria, and data extraction and quality assessment were performed for included studies. Data were analyzed to identify key features that are associated with significant improvement in behavior. A total of 27 studies met inclusion criteria. Most (n = 15) were Web site interventions. Other delivery methods were text messages, games, multicomponent interventions, emails, and social media. Significant behavior change was often seen when interventions included education, goal setting, self-monitoring, and parental involvement. None of the publications reported cost-effectiveness. Due to heterogeneity of studies, meta-analysis was not feasible.It is possible to effect significant health behavior change in adolescents through digital interventions that incorporate education, goal setting, self-monitoring, and parental involvement. Most of the evidence relates to Web sites and further research into alternate media is needed, and longer term outcomes should be evaluated. There is a paucity of data on the cost-effectiveness of digital health interventions, and future trials should report these data