Two kinds of abstraction in schizophrenia : a thesis presented in partial fulfilment of the requirements for the degree of Master of Arts in Psychology at Massey University

An impairment in abstracting ability has frequently been proposed as a reason for schizophrenic thought disorder. The performance of hospitalized chronic paranoid schizophrenics and non-paranoid schizophrenics were compared to a normal control group on two types of abstraction; a traditional conceptual abstraction task (similarities, Trunnell, 1964) and an inferential abstraction task (relational abstraction, Bransford, Barclay & Franks, 1972). These two measures allowed a differential interpretation of the nature of the abstraction impairment in schizophrenia. The two clinical groups did not significantly differ on the traditional hierarchical measure of abstraction. Performance of both schizophrenic groups, however, differed significantly from that of controls in that schizophrenic subjects employed less abstract concepts to classify items in this task. On the second measure of abstraction no significant differences were found between schizophrenic subjects and the control group. Differences between paranoid and non-paranoid subjects did not reach significance on this task but there was some indication that each of these schizophrenic sub-groups used different cognitive strategies on this measure. Paranoid schizophrenics appeared not to elaborate information beyond its original form. The non-paranoids, on the other hand, appeared to elaborate stimulus material but were confused between inferential and original information. The present results indicate that chronic paranoid schizophrenics have a different type of abstraction impairment to chronic non-paranoid schizophrenics on the inferential conceptual abstraction task. These findings indicate the utility of using two indices of abstraction and the importance of not treating schizophrenics as a homogeneous group

The UK Women's Cohort Study: comparison of vegetarians, fish-eaters and meat-eaters

Background: This paper describes the development of the UK Women's Cohort Study and presents cohort baseline characteristics. Methods: In total, 35 372 women, aged 35–69 years at recruitment, were selected to ensure a wide range of dietary intakes. Diet was assessed by a 217-item food-frequency questionnaire (FFQ). Detailed lifestyle information was collected by postal questionnaire. Vegetarians, fish-eaters and meat-eaters were compared. Results: The cohort women are mainly white, well-educated, middle-class and married with children. They are health-conscious with only 11% current smokers and 58% taking dietary supplements. Twenty-eight per cent of subjects self-report as being vegetarian and 1% as vegan. However, only 18% are defined as 'vegetarian' from the FFQ. Fat provides 32% of energy; vitamin and mineral intakes are high, with a broad range of intakes. Meat-eaters are older, with a higher body mass index (BMI) and the lowest intakes of carbohydrate, fibre, vitamin C, folate, iron and calcium. Other fish-eaters are similar to vegetarians. Vegetarians have the lowest intakes of protein, fat and saturated fat. Oily fish-eaters have the lowest BMI; are the least likely to smoke or use full-fat milk; and are the most likely to use dietary supplements and consume the most fruit and vegetables. Oily fish-eaters have the highest total energy intake and vegetarians the lowest. Semi-skimmed milk, bread, potatoes, wine, bananas and muesli are important contributors to energy for all groups

Overconfidence vs. Market Efficiency in the National Football League

A question of increasing interest to researchers in a variety of fields is whether the incentives and experience present in many "real world" settings mitigate judgment and decision-making biases. To investigate this question, we analyze the decision making of National Football League teams during their annual player draft. This is a domain in which incentives are exceedingly high and the opportunities for learning rich. It is also a domain in which multiple psychological factors suggest teams may overvalue the "right to choose" in the draft -- non-regressive predictions, overconfidence, the winner's curse and false consensus all suggest a bias in this direction. Using archival data on draft-day trades, player performance and compensation, we compare the market value of draft picks with the historical value of drafted players. We find that top draft picks are overvalued in a manner that is inconsistent with rational expectations and efficient markets and consistent with psychological research.

The impact of imprecisely measured covariates on estimating gene-environment interactions

BACKGROUND The effects of measurement error in epidemiological exposures and confounders on estimated effects of exposure are well described, but the effects on estimates for gene-environment interactions has received rather less attention. In particular, the effects of confounder measurement error on gene-environment interactions are unknown. METHODS We investigate these effects using simulated data and illustrate our results with a practical example in nutrition epidemiology. RESULTS We show that the interaction regression coefficient is unchanged by confounder measurement error under certain conditions, but biased by exposure measurement error. We also confirm that confounder measurement error can lead to estimated effects of exposure biased either towards or away from the null, depending on the correlation structure, with associated effects on type II errors. CONCLUSION Whilst measurement error in confounders does not lead to bias in interaction coefficients, it may still lead to bias in the estimated effects of exposure. There may still be cost implications for epidemiological studies that need to calibrate all error-prone covariates against a valid reference, in addition to the exposure, to reduce the effects of confounder measurement erro

Arginine kinetics are altered in a pilot sample of adolescents and young adults with Barth syndrome

Barth syndrome (BTHS) is a rare, X-linked cardiomyopathy that is characterized by abnormalities in glucose and lipid metabolism, with less known regarding amino acid metabolism. This pilot study characterized whole-body arginine kinetics and found lower arginine rate of appearance into plasma (0.69 ± 0.09 vs. 0.88 ± 0.06 μmol/kgFFM/min

Spatial imaging of modifications to fluorescence lifetime and intensity by individual Ag nanoparticles

Highly ordered periodic arrays of silver nanoparticles have been fabricated which exhibit surface plasmon resonances in the visible spectrum. We demonstrate the ability of these structures to alter the fluorescence properties of vicinal dye molecules by providing an additional radiative decay channel. Using fluorescence lifetime imaging microscopy (FLIM), we have created high resolution spatial maps of the molecular lifetime components; these show an order of magnitude increase in decay rate from a localized volume around the nanoparticles, resulting in a commensurate enhancement in the fluorescence emission intensity.Comment: 3 pages, 2 figures, submitted Applied Physics Letter

Plasmonic engineering of metal nanoparticles for enhanced fluorescence and Raman scattering

We have investigated the effects of tuning the localized surface plasmon resonances (LSPRs) of silver nanoparticles on the fluorescence intensity, lifetime, and Raman signal from nearby fluorophores. The presence of a metallic structure can alter the optical properties of a molecule by increasing the excitation field, and by modifying radiative and non-radiative decay mechanisms. By careful choice of experimental parameters we have been able to decouple these effects. We observe a four-fold increase in fluorescence enhancement and an almost 30-fold increase in decay rate from arrays of Ag nanoparticles, when the LSPR is tuned to the emission wavelength of a locally situated fluorophore. This is consistent with a greatly increased efficiency for energy transfer from fluorescence to surface plasmons. Additionally, surface enhanced Raman scattering (SERS) measurements show a maximum enhancement occurs when both the incident laser light and the Raman signal are near resonance with the plasmon energy. Spatial mapping of the SERS signal from a nanoparticle array reveals highly localized differences in the excitation field resulting from small differences in the LSPR energy.Comment: Submitted to Plasmonics (Springer

Convergence of the kk-Means Minimization Problem using Γ\Gamma-Convergence

The $k$-means method is an iterative clustering algorithm which associates each observation with one of $k$ clusters. It traditionally employs cluster centers in the same space as the observed data. By relaxing this requirement, it is possible to apply the $k$-means method to infinite dimensional problems, for example multiple target tracking and smoothing problems in the presence of unknown data association. Via a $\Gamma$-convergence argument, the associated optimization problem is shown to converge in the sense that both the $k$-means minimum and minimizers converge in the large data limit to quantities which depend upon the observed data only through its distribution. The theory is supplemented with two examples to demonstrate the range of problems now accessible by the $k$-means method. The first example combines a non-parametric smoothing problem with unknown data association. The second addresses tracking using sparse data from a network of passive sensors