Discrete solitons and nonlinear surface modes in semi-infinite waveguide arrays

We discuss the formation of self-trapped localized states near the edge of a semi-infinite array of nonlinear waveguides. We study a crossover from nonlinear surface states to discrete solitons by analyzing the families of odd and even modes centered at different distances from the surface, and reveal the physical mechanism of the nonlinearity-induced stabilization of surface modes.Comment: 4 double-column pages, 5 figures, submitted to Optics Letter

Attentional Bias to Body-Related Stimuli in Younger and Middle-Aged Females: The Role of Eating Disorders and Thin Ideal Priming

Research has shown individuals with an eating disorder selectively attend to stimuli related to their concerns, and this attentional component might be one way in which eating disorders are maintained. Research using a variant of the Stroop task has demonstrated that women with an eating disorder have a stronger Stroop interference effect for words related to body shape than controls. The conclusion is individuals with an eating disorder have an information processing bias for stimuli related to their disorder, and thus, slower responses. A main objective of this study was to investigate this effect in both younger and middle age females. In Experiment 1, younger and middle age females with an eating disorder were compared with females without an eating disorder. In Experiment 2, younger and middle age females who had been exposed to thin media images were compared with females exposed to control images. The predictions were reflected through the color naming of body related words in a variation of the Stroop task. Computer mouse tracking was used to examine processing in both experiments. I predicted participants with an eating disorder (Experiment 1) or those exposed to the thin ideal prime (Experiment 2) would be more distracted by the presence of body related words relative to the controls. In both experiments, the middle age participants took longer to complete the task than the younger participants. In Experiment 1, age differences interacted with the eating disorder, a new finding with important implications. The RT data from the priming manipulation in Experiment 2 suggested that the thin prime facilitated responses to the body related words, opposite from the predictions. However, when examining the raw trajectory data using mouse tracking, age differences and interactions with prime began to emerge. The results showed, when looking at the role of an eating disorder in Experiment 1, middle age females with an eating disorder exhibited large attentional deficits. In Experiment

The Effect of Priming a Thin Ideal on the Subsequent Perception of Conceptually Related Body Image Words

There is a substantial amount of empirical evidence in support of the claim that the thin ideal portrayed by the mass media leads to body image dissatisfaction. Furthermore, a disturbance in the perception of body image is an essential feature of eating disorders. The Stroop task has been adapted to provide a measure of selective processing for body image related words in eating disordered individuals. Building upon this previous work, the present study was designed to examine the effect of priming the thin ideal on the subsequent perception of body image related words in participants without an eating disorder. In both Experiments 1 and 2, half of the participants were primed by viewing slim female models, and half by viewing advertisements for gender-neutral shoes. In Experiment 1, all participants completed a Stroop task for three categories of stimuli: neutral words (BOOKS), shoe words (CLOGS), and body image words (THIGHS). It was hypothesized that the group primed with the thin ideal would exhibit delayed color-naming times for the body image words relative to the group primed with gender-neutral shoe ads. In Experiment 2, the eye-tracking paradigm was used to further investigate the hypothesized priming effect. In particular, this paradigm was chosen for its ability to provide fine-grained temporal information in order to examine how the predicted effect unfolds over time. It was hypothesized that participants primed by the thin ideal would spend more time fixating body image related distractor words relative to the group primed with gender-neutral shoe ads. The results demonstrate a pattern that is consistent with the predictions, but the analyses failed to reach significance. While the lack of findings is disappointing, it was encouraging to discover that the eye-tracking paradigm is a sound methodology for investigating information processing in studies with clinical implications. The results of this study encourage future research using the eye-tracking methodology for investigations of information-p

Attentional Bias to Body-Related Stimuli in Younger and Middle-Aged Females: The Role of Eating Disorders and Thin Ideal Priming

Research has shown individuals with an eating disorder selectively attend to stimuli related to their concerns, and this attentional component might be one way in which eating disorders are maintained. Research using a variant of the Stroop task has demonstrated that women with an eating disorder have a stronger Stroop interference effect for words related to body shape than controls. The conclusion is individuals with an eating disorder have an information processing bias for stimuli related to their disorder, and thus, slower responses. A main objective of this study was to investigate this effect in both younger and middle age females. In Experiment 1, younger and middle age females with an eating disorder were compared with females without an eating disorder. In Experiment 2, younger and middle age females who had been exposed to thin media images were compared with females exposed to control images. The predictions were reflected through the color naming of body related words in a variation of the Stroop task. Computer mouse tracking was used to examine processing in both experiments. I predicted participants with an eating disorder (Experiment 1) or those exposed to the thin ideal prime (Experiment 2) would be more distracted by the presence of body related words relative to the controls. In both experiments, the middle age participants took longer to complete the task than the younger participants. In Experiment 1, age differences interacted with the eating disorder, a new finding with important implications. The RT data from the priming manipulation in Experiment 2 suggested that the thin prime facilitated responses to the body related words, opposite from the predictions. However, when examining the raw trajectory data using mouse tracking, age differences and interactions with prime began to emerge. The results showed, when looking at the role of an eating disorder in Experiment 1, middle age females with an eating disorder exhibited large attentional deficits. In Experiment

Structure of nearshore fish assemblages in relation to varying levels of habitat complexity

Thesis (M.S.) University of Alaska Fairbanks, 2007Complex kelp and rocky habitats can be beneficial to fishes, however, their use of these habitats is poorly understood in northern latitudes. This study examined nearshore kelp habitats to examine the potential effects of kelp density and substrate topography on nearshore fish communities in Kachemak Bay, Alaska. Fish were collected from multiple sand, understory kelp, and understory and canopy kelp sites, along with kelp and substrate complexity measurements. Standard Monitoring Units for the Recruitment of Fish (SMURFs), light traps, shrimp pots, and SCUBA visual surveys were all employed in these collections. Relative fish abundance and community composition varied temporally in all habitats. The dominant fish families were gadids, pleuronectids, hexagrammids, and sebastids. Habitat use differed significantly temporally and spatially in relation to size class. These differences were family specific. Community analysis of the dominant fish families showed that different habitat complexities supported distinct fish assemblages. Low complexity sand habitats were particularly important for juvenile pleuronectids in this region and complex nearshore kelp habitats may be essential fish habitat for juvenile Pacific cod. Although these high complexity nearshore environments may be challenging to sample, they support large fish assemblages and may be essential to a variety of fish families and species

Mouse-Tracking Reveals When the Stroop Effect Happens.

We examined the continuous dynamics of the Stroop task using mouse-tracking. Participants moved the computer mouse to indicate the color of words presented on the computer screen in both congruent (blue in blue font) and incongruent (blue in yellow font) conditions. Mouse-tracking data revealed significant differences in reaction times, spatial attraction, and velocity. In the Stroop effect, word reading and color processing influenced performance, but they did so differently: Word reading influenced the early part of the mouse trajectory, but color processing influenced later parts. The data provide important new information about the real time processing dynamics underlying the effect

Mouse-Tracking Reveals When the Stroop Effect Happens.

We examined the continuous dynamics of the Stroop task using mouse-tracking. Participants moved the computer mouse to indicate the color of words presented on the computer screen in both congruent (blue in blue font) and incongruent (blue in yellow font) conditions. Mouse-tracking data revealed significant differences in reaction times, spatial attraction, and velocity. In the Stroop effect, word reading and color processing influenced performance, but they did so differently: Word reading influenced the early part of the mouse trajectory, but color processing influenced later parts. The data provide important new information about the real time processing dynamics underlying the effect

The calorically restricted ketogenic diet, an effective alternative therapy for malignant brain cancer

BACKGROUND: Malignant brain cancer persists as a major disease of morbidity and mortality in adults and is the second leading cause of cancer death in children. Many current therapies for malignant brain tumors fail to provide long-term management because they ineffectively target tumor cells while negatively impacting the health and vitality of normal brain cells. In contrast to brain tumor cells, which lack metabolic flexibility and are largely dependent on glucose for growth and survival, normal brain cells can metabolize both glucose and ketone bodies for energy. This study evaluated the efficacy of KetoCal(®), a new nutritionally balanced high fat/low carbohydrate ketogenic diet for children with epilepsy, on the growth and vascularity of a malignant mouse astrocytoma (CT-2A) and a human malignant glioma (U87-MG). METHODS: Adult mice were implanted orthotopically with the malignant brain tumors and KetoCal(® )was administered to the mice in either unrestricted amounts or in restricted amounts to reduce total caloric intake according to the manufacturers recommendation for children with refractory epilepsy. The effects KetoCal(® )on tumor growth, vascularity, and mouse survival were compared with that of an unrestricted high carbohydrate standard diet. RESULTS: KetoCal(® )administered in restricted amounts significantly decreased the intracerebral growth of the CT-2A and U87-MG tumors by about 65% and 35%, respectively, and significantly enhanced health and survival relative to that of the control groups receiving the standard low fat/high carbohydrate diet. The restricted KetoCal(® )diet reduced plasma glucose levels while elevating plasma ketone body (β-hydroxybutyrate) levels. Tumor microvessel density was less in the calorically restricted KetoCal(® )groups than in the calorically unrestricted control groups. Moreover, gene expression for the mitochondrial enzymes, β-hydroxybutyrate dehydrogenase and succinyl-CoA: 3-ketoacid CoA transferase, was lower in the tumors than in the contralateral normal brain suggesting that these brain tumors have reduced ability to metabolize ketone bodies for energy. CONCLUSION: The results indicate that KetoCal(® )has anti-tumor and anti-angiogenic effects in experimental mouse and human brain tumors when administered in restricted amounts. The therapeutic effect of KetoCal(® )for brain cancer management was due largely to the reduction of total caloric content, which reduces circulating glucose required for rapid tumor growth. A dependency on glucose for energy together with defects in ketone body metabolism largely account for why the brain tumors grow minimally on either a ketogenic-restricted diet or on a standard-restricted diet. Genes for ketone body metabolism should be useful for screening brain tumors that could be targeted with calorically restricted high fat/low carbohydrate ketogenic diets. This preclinical study indicates that restricted KetoCal(® )is a safe and effective diet therapy and should be considered as an alternative therapeutic option for malignant brain cancer

A review of exposure assessment methods for epidemiological studies of health effects related to industrially contaminated sites

BACKGROUND: this paper is based upon work from COST Action ICSHNet. Health risks related to living close to industrially contaminated sites (ICSs) are a public concern. Toxicology-based risk assessment of single contaminants is the main approach to assess health risks, but epidemiological studies which investigate the relationships between exposure and health directly in the affected population have contributed important evidence. Limitations in exposure assessment have substantially contributed to uncertainty about associations found in epidemiological studies. OBJECTIVES: to examine exposure assessment methods that have been used in epidemiological studies on ICSs and to provide recommendations for improved exposure assessment in epidemiological studies by comparing exposure assessment methods in epidemiological studies and risk assessments. METHODS: after defining the multi-media framework of exposure related to ICSs, we discussed selected multi-media models applied in Europe. We provided an overview of exposure assessment in 54 epidemiological studies from a systematic review of hazardous waste sites; a systematic review of 41 epidemiological studies on incinerators and 52 additional studies on ICSs and health identified for this review. RESULTS: we identified 10 multi-media models used in Europe primarily for risk assessment. Recent models incorporated estimation of internal biomarker levels. Predictions of the models differ particularly for the routes ‘indoor air inhalation’ and ‘vegetable consumption’. Virtually all of the 54 hazardous waste studies used proximity indicators of exposure, based on municipality or zip code of residence (28 studies) or distance to a contaminated site (25 studies). One study used human biomonitoring. In virtually all epidemiological studies, actual land use was ignored. In the 52 additional studies on contaminated sites, proximity indicators were applied in 39 studies, air pollution dispersion modelling in 6 studies, and human biomonitoring in 9 studies. Exposure assessment in epidemiological studies on incinerators included indicators (presence of source in municipality and distance to the incinerator) and air dispersion modelling. Environmental multi-media modelling methods were not applied in any of the three groups of studies. CONCLUSIONS: recommendations for refined exposure assessment in epidemiological studies included the use of more sophisticated exposure metrics instead of simple proximity indicators where feasible, as distance from a source results in misclassification of exposure as it ignores key determinants of environmental fate and transport, source characteristics, land use, and human consumption behaviour. More validation studies using personal exposure or human biomonitoring are needed to assess misclassification of exposure. Exposure assessment should take more advantage of the detailed multi-media exposure assessment procedures developed for risk assessment. The use of indicators can be substantially improved by linking definition of zones of exposure to existing knowledge of extent of dispersion. Studies should incorporate more often land use and individual behaviour