Correlation between layer thickness and periodicity of long polytypes in silicon carbide

The layer widths and repeat spacing of long-period polytypes (LPPs) have been determined using synchrotron radiation source (SRS) X-ray diffraction topography (XRDT). This method has proved to be a powerful tool in investigating the spatial extent of one-dimensional disorder (1DD), long-period polytypes (LPPs) and the boundaries of polytype layers in silicon carbide (SiC). The resulting neighbourhood coalescence models have confirmed the validity of the sandwich rule even in the limit of two arbitrarily long LPPs, as well as the unique nature of the 6H polytype. A significant empirical trend is reported here that relates the thickness of LPP layers to the periodicity of the repeat stacking sequence measured on the topographs. A good correlation between the data suggests that this behaviour is governed by a simple mathematical expression t = kNn. Values for k and n have been determined that relate the polytype thickness (t in microns) to the number of hexagonal layers (N) in the polytype stacking repeat. These values can be used to prompt questions about the limits of polytypism and disorder in SiC

National Identity and Attitudes toward Immigrants: The Role of Social Comparison and Perceptions of Competition

Research has long demonstrated that negative types of national attachment, like nationalism, are related to relatively more negative intergroup attitudes while more positive forms of national identity, like patriotism, are either related to relatively more positive attitudes or unrelated. Most of this research has been conducted using individual difference measures of national identity. This series of studies seeks to test the difference between nationalism and patriotism empirically, by examining the idea that the presence of social comparison is what separates nationalism from patriotism. Further, the literature suggests that perceptions of competition between groups are an important factor in determining intergroup relations. Therefore, I am also interested in exploring the potential mediational role of perceptions of competition. In four studies, my goals were: (1) to determine whether the previously demonstrated relations between individual differences in nationalism and patriotism and attitudes toward immigrants would replicate; (2) to determine whether making social comparisons (downward versus upward) affects participants attitudes toward immigrants, and whether these parallel the effects found for individual differences in nationalism; and (3) to examine the potential meditational role of perceived competition. Study 1 is a correlational study examining nationalism and patriotism as predictors of attitudes and emotions toward immigrants. In Study 2, I introduce a social comparison manipulation to determine if making downward social comparisons (comparing one’s nation to another nation that is considered worse off) between one’s nation and another lead to less positive intergroup attitudes. In Studies 3a and 3b, I attempt to replicate Study 2, and also examine the effects of upward social comparison (comparing one’s nation to another nation that is considered better off). Across the studies, my results suggest that making downward social comparisons results in relatively less favorable attitudes toward immigrants. I also found some support for the idea that these relations are mediated by perceptions of competition between immigrants and other Canadians. Finally, I consistently replicated previous findings that the nationalism individual difference variable predicted relatively less positive intergroup attitudes while patriotism was either related to relatively more positive intergroup attitudes or unrelated to attitudes. Implications for national identity theory as well as immigrants and immigration to Canada are discussed

A reliable method for enrichment of neutrophils from peripheral blood in barramundi (Lates calcarifer)

Neutrophils are a short-lived, terminally differentiated, innate immune cell, that are critical first responders during infection. Research into neutrophil-pathogen interactions in fish has primarily employed cells derived from the pro-nephros and nephros. Since these sites are also the location of neutrophil and other immune cell development, there may be some ambiguity in maturation and functional ability of these cells, and difficulty in differentiating the effects of neutrophils from those of macrophages and monocytes. In contrast, peripheral blood circulating neutrophils are mature and ready to respond, thus it may be more physiologically relevant to use these cells for immune studies when evaluating interactions with blood-borne pathogens. The enrichment of tropical, euryhaline fish blood cells cannot follow classic mammalian enrichment methods for several reasons: Fish have nucleated red blood cells (RBC's), a high number of reticulocytes, a very low number of granulocytic leukocytes and an osmotic tolerance, rendering techniques such as water lysis ineffective. Enrichment of neutrophils, while minimizing RBC contamination, is imperative for studies where luminescence or fluorescence signals may be confounded by background from an overabundance of RBC's. We have optimized a method for enriching neutrophils from peripheral blood, with an initial settlement step employing 6% dextran (Mr 450,000–650,000), for 30–60 min at room temperature, followed by density separation on an 8-step Percoll density gradient. This method provides a cell suspension comprising 20–50% neutrophils, free of contamination from reticulocytes. These are then suitable for luminometric or fluorometric downstream analyses

Functional connectivity classification of autism identifies highly predictive brain features but falls short of biomarker standards

AbstractObjectivesAutism spectrum disorders (ASD) are diagnosed based on early-manifesting clinical symptoms, including markedly impaired social communication. We assessed the viability of resting-state functional MRI (rs-fMRI) connectivity measures as diagnostic biomarkers for ASD and investigated which connectivity features are predictive of a diagnosis.MethodsRs-fMRI scans from 59 high functioning males with ASD and 59 age- and IQ-matched typically developing (TD) males were used to build a series of machine learning classifiers. Classification features were obtained using 3 sets of brain regions. Another set of classifiers was built from participants' scores on behavioral metrics. An additional age and IQ-matched cohort of 178 individuals (89 ASD; 89 TD) from the Autism Brain Imaging Data Exchange (ABIDE) open-access dataset (http://fcon_1000.projects.nitrc.org/indi/abide/) were included for replication.ResultsHigh classification accuracy was achieved through several rs-fMRI methods (peak accuracy 76.67%). However, classification via behavioral measures consistently surpassed rs-fMRI classifiers (peak accuracy 95.19%). The class probability estimates, P(ASD|fMRI data), from brain-based classifiers significantly correlated with scores on a measure of social functioning, the Social Responsiveness Scale (SRS), as did the most informative features from 2 of the 3 sets of brain-based features. The most informative connections predominantly originated from regions strongly associated with social functioning.ConclusionsWhile individuals can be classified as having ASD with statistically significant accuracy from their rs-fMRI scans alone, this method falls short of biomarker standards. Classification methods provided further evidence that ASD functional connectivity is characterized by dysfunction of large-scale functional networks, particularly those involved in social information processing

Lost Gems: Identifying Rare and Unusual Monographs in a University\u27s Circulating Collection

Identifying and evaluating the oldest published content held by the library using a set of transfer criteria provided a means to systematically evaluate and, if necessary, move rare or unusual content into a more secure location. The process enabled us to correct cataloging errors, identify and address items with condition issues, be familiar with the library\u27s unique holdings and finally, to identify and add content distinctly associated with EMU\u27s history to the University Archives and Special Collections

The implicit relational assessment procedure: emerging reliability and validity data

The Implicit Relational Assessment Procedure (IRAP) is a measure of ‘implicit cognition' developed on the basis of a contemporary behavioural analysis of language and cognition. The IRAP has now been applied to a range of foci over five years of published research. A frequently-cited caveat in publications to date is the need for further research to gauge the reliability and validity of the IRAP as an implicit measure. This review paper will provide a critical synthesis of available evidence for reliability and validity. The review applies a multifaceted test-theory approach to validity, and reliability is assessed through meta-analysis of published data. The discussion critically considers reviewed IRAP evidence with reference to the extant literature on alternative implicit measures, limitations of studies to date, and consideration of broader conceptual issues