Cytosine methylation at CpG dinucleotides is a semistable epigenetic marker critical to the normal development of vertebrates. Abnormal levels of methylation are associated with a host of human diseases and disorders, and many diagnostic tools have been developed based on analysis of methylation in tissue samples. Methylation is governed by a complex set of dynamic processes and has been observed to exhibit cyclical gains and losses, leading to the development of stochastic models of its inheritance. Many such models have assumed independence between sites and have largely focused on the proportion of methylation present in a sample, ignoring the diversity that exists in individual patterns. When analyzed at a single-base resolution, methylation patterns exhibit strong evidence of spatial dependence, and a recently proposed neighboring sites model which incorporates dependence between pairs of adjacent CpG sites has offered significant improvements over independent models. CpG sites are non-uniformly distributed throughout the genome, and the number of bases separating ""adjacent"" sites can vary greatly. In this paper, we develop and test an extension of this neighboring sites model which places a distance-dependent weight on the association between each pair of neighboring sites. Models are compared with regard to their ability to produce simulations that are statistically similar to biological data. We find that the distance-weighted model offers substantive improvements over distance-blind approaches to modeling the dependence structure, particularly in cases where firm boundaries between methylated and unmethylated regions exist in the data. / acase@tulane.edu

Trauma literature demonstrates that sexually abused youth are at risk for psychopathology and adjustment problems, including Posttraumatic Stress Disorder (PTSD; e.g. Yancey, & Hansen, 2010). Dissociation is a response to a traumatic event that may be adaptive within the traumatic experience; however, persistent trauma-specific dissociation can impair affect regulation and cognitive skills and increase risk for PTSD (e.g. Kaplow, Dodge, Amaya-Jackson, & Saxe, 2005). The current study aimed to confirm the relationship between dissociation and posttraumatic stress symptoms (PTSS) and examine the potential moderating effect of abuse-related support from the non-offending caregiver, the single best predictor of resilience after sexual abuse. The study sample included 52 sexually abused youth ages 8-16 years (M = 12.94, SD = 2.18) who were predominantly female (85%) and African American (62%). It was hypothesized that (1) dissociation during a forensic interview would predict PTSS and (2) low levels of caregiver support would strengthen the magnitude of the association between dissociation and PTSS compared to high levels of caregiver support. Findings confirmed the first hypothesis such that participants who reported more symptoms of dissociation in response to a forensic interview were at higher risk for PTSS. However, caregiver support did not moderate this relationship. Exploratory analyses examining the differential impact of caregiver support and caregiver blame also revealed no moderating effects. However, youth of caregivers reporting more blame of the child and/or less blame of the perpetrator were at higher risk of PTSS. These results provide support for guidelines recommending forensic interviewers include screening for dissociation and PTSS, as well as caregiver responses to disclosure. Importantly, the caregiver’s attributions of blame may be relevant points of intervention when targeting resilience among sexually abused youth. / acase@tulane.edu

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Ecomaps (drawing-based assessments of social networks) were administered to primary school-aged children in order to ascertain whether Ecomaps might be useful in universal screening. Participants included 61 children (40.9% female) aged six to ten (M = 7.39, SD = 1.19), Kindergarten through third grade students in a predominantly African American (89.5%) public charter school in New Orleans. The study hypothesis was that children who report experiencing higher levels of social support and lower levels of social stress (derived from Ecomap index of Support-Stress balance) would have better social-emotional, behavioral, and academic outcomes than children who report lower levels of support and higher levels of stress. Ecomaps were administered to all participants and correlated with school-based archival data, including results of the Behavior Assessment System for Children, 2nd Edition (BASC-2), school behavior grades, and academic records. Stress-support indices from Ecomaps were significantly correlated with social-emotional and behavioral outcomes, but correlations with academic outcomes were not significant, providing partial support for the study’s hypothesis. Based on these findings, Ecomaps might be used as self-report measures to identify children at risk for, or currently experiencing, social-emotional or behavioral problems. This measure could be helpful to school psychologists and other school-based mental health professionals who are attempting to understand and respond to the strengths and needs of the children in their care. / acase@tulane.edu

The effects of age/maturation, grade, amount of school exposure, and early or late entry into school, on mathematics and executive function skills of pre-kindergarten and kindergarten students was examined. The sample consists of four-and five-year olds from low-income ethnic minority families enrolled in pre-kindergarten (pre-K) (n = 42) and kindergarten (n = 40). Assessments of mathematics competency and executive function were conducted by trained researchers in the fall of the school year. Regression analyses were conducted to test the effects of age/maturation and amount of schooling, while independent samples t-test were used to examine late versus early entry into school, the value of pre-K attendance, and if grade level matters. The findings revealed that there is a maturation effect to an extent in the beginning of the preschool year. The importance of school exposure (pre-K attendance) and early entry was also confirmed. A future longitudinal study needs to be conducted that follows the same cohort from pre-K to adulthood in order to find the long term effects underlying this debate. / acase@tulane.edu

Currently, most contact lenses are made with a silicone hydrogel (Si-Hy) blend that provides softness for comfort as well as high oxygen permeability. Silicone hydrogel lenses have both hydrophilic and hydrophobic areas, and the natural hydrophobicity of the material contributes to biofouling, which is the adsorption of proteins and lipids from the tear film of the eye. Published in vitro investigations into the quantity and spatial distribution of lipids deposited on contact lenses usually involve the use of artificial tear fluid (ATF) that is not changed or replenished over the course of the experiments. Yet, the natural tear film is constantly replenished by the meibomian and lacrimal glands. The intent of this study was to investigate the significance of replenishing the ATF over the study period on lipid absorption profiles and quantities. In part one, fluorescence confocal microscopy was used to observe the penetration profiles of lipids into nine different Si-Hy lenses. In part two, radiolabeling was used to quantify the amount of lipid absorbed by nine different Si-Hy lenses. Using a non-static exposure method was found to allow more absorption of cholesterol than the static method. The non-static method also provided more differentiation between lens types and brands in lipid absorption profiles and amounts than the static method. / acase@tulane.edu

Perception and action are coupled via bidirectional relationships between sensory and motor systems. Motor systems influence sensory areas by imparting a feedforward influence on sensory processing termed “motor efference copy†(MEC). MEC is suggested to occur in humans because speech preparation and production modulate neural measures of auditory cortical activity. However, it is not known if MEC can affect auditory perception. We tested the hypothesis that during speech preparation auditory thresholds will increase relative to a control condition, and that the increase would be most evident for frequencies that match the upcoming vocal response. Participants performed trials in a speech condition that contained a visual cue indicating a vocal response to prepare (one of two frequencies), followed by a go signal to speak. To determine threshold shifts, voice-matched or -mismatched pure tones were presented at one of three time points between the cue and target. The control condition was the same except the visual cues did not specify a response and subjects did not speak. For each participant, we measured f0 thresholds in isolation from the task in order to establish baselines. Results indicated that auditory thresholds were highest during speech preparation, relative to baselines and a non-speech control condition, especially at suprathreshold levels. Thresholds for tones that matched the frequency of planned responses gradually increased over time, but sharply declined for the mismatched tones shortly before targets. Findings support the hypothesis that MEC influences auditory perception by modulating thresholds during speech preparation, with some specificity relative to the planned response. The threshold increase in tasks vs. baseline may reflect attentional demands of the tasks. / acase@tulane.edu

Transition metal oxides have attracted widespread attention due to their broad range of fascinating exotic phenomena such as multiferroicity, superconductivity, colossal magnetoresistance and metal-to-insulator transition. Due to the interplay between spin, charge, lattice and orbital degrees of freedom of strongly correlated d electrons, these physical properties are extremely sensitive to the external perturbations such as magnetic field, charge carrier doping and pressure, which provide a unique chance in search for novel exotic quantum states. Ruthenate systems are a typical strongly correlated system, with rich ordered states and their properties are extremely sensitive to external stimuli. Recently, the experimental observation of spin-orbit coupling induced Mott insulator in Sr2IrO4 as well as the theoretical prediction of topological insulating state in other iridates, have attracted tremendous interest in the physics of strong correlation and spin-orbit coupling in 4d/5d compounds. We observe an itinerant ferromagnetic ground state of Ca2RuO4 film in stark contrast to the Mott-insulating state in bulk Ca2RuO4. We have also established the epitaxial strain effect on the transport and magnetic properties for the (Ca,Sr)2RuO4 thin films. For Sr2IrO4 thin films, we will show that the Jeff = 1/2 moment orientation can be modulated by epitaxial strain. In addition, we discovered novel Ba7Ir3O13+x thin films which exhibit colossal permittivity. / acase@tulane.edu

Although White Americans experience less frequent and less severe forms of discrimination than racial minorities (Schmitt & Branscombe, 2002), White Americans may actually be more likely to make claims of discrimination compared to racial minorities (Goldman, 2001). The present research investigated evaluations of White and Black American discrimination claimants’ political views and prejudicial attitudes. Across two studies, a White American target was evaluated as more politically conservative when claiming discrimination compared to a control condition. In contrast, a Black American target was evaluated as more politically liberal when claiming discrimination compared to a control condition. Both the White and Black American target were evaluated as more prejudiced against the outgroup when claiming discrimination, however the increase in prejudice evaluations was more pronounced for the White American target. The present research suggests that lay individuals make distinct inferences about the political views and prejudicial attitudes of White versus Black American discrimination claimants. / acase@tulane.edu

Although the evolutionary implications of natural differences in flow regime have been well-studied, the evolutionary implications of anthropogenic modification of flow regime are not well understood. To begin to characterize the evolutionary consequences of dam construction for small stream fishes, I conducted four related studies focused on the blacktail shiner (Cyprinella venusta). First, to characterize natural variation in body shape related to stream characteristics, I assessed the extent to which body shape corresponded to three environmental factors, phylogeny, and body size. Morphology was predominantly associated with variation in mean annual runoff; phylogeny was also a strong predictor of morphology. In contrast to previous studies that emphasize the importance of water velocity, these findings indicate that morphological variation is tightly linked to more complex aspects of hydrology and evolutionary history. Second, to initially characterize variation in body shape associated with dam construction, I compared the body shape of C. venusta from pairs of river and reservoir sites. River populations differ from reservoir populations in several aspects of morphology, demonstrating that reservoir characteristics drive changes in the morphology fish populations. Third, to characterize the pace and trajectory of phenotypic responses to impoundment, I examined a chronosequence of museum specimens originating from a reservoir and nearby stream. The rate of change in larger individuals was greatest in the first 15 years following impoundment, with less pronounced shifts in smaller individuals and no shift in the morphology of stream individuals. These results indicate that morphological responses to impoundment are decadal-scale and attenuate. Fourth, to determine if impoundment-related morphological shifts are genetically determined and are functionally significant, I conducted swimming performance trials with common garden C. venusta originating from reservoir and stream parents. Common garden juveniles exhibited differences in morphology similar to those between wild-caught individuals, indicating that morphological divergence following impoundment is an outcome of rapid evolutionary change. Offspring did not differ in swimming performance, suggesting that morphological evolution may be driven by reproductive or trophic shifts following impoundment. Together, these studies demonstrate that impoundment is a potent evolutionary force on fishes, but the mechanisms by which it does so remain relatively unknown. / acase@tulane.edu