Study of the wear of dental composites using an atomic force microscope

This work presents a study of the wear of four dental composites (Concept, XRV, Maxxim, and Belleglass) which are in commercial use. The wear testing was performed using an Atomic Force Microscope (AFM). Several scanning techniques and various cantilevers were attempted. Finally use of a stainless steel cantilever with a tungsten bead attached resulted in quantifiable wear. AFM imaging in contact mode was used for evaluation of the wear tests. Wear rates are reported as volume per 100,000 scans. The AFM measured wear rates rank the tested composites from most to least wear as follows: Concept highest volume of wear XRV Maxxim BelleGlass least volume of wear. Micro-hardness measurements were also conducted

Prediction of cut-off frequency from the maximum slope of a transmittance scan of an ideal edge

This study has empirically shown that the maximum slope of an ideal edge scan in transmittance versus position is an excellent indicator of the cut-off frequency at which a microdensitometer system\u27s modulation transfer function goes to zero. It was found that numerical aperture of collection objective, scanning slit width and alignment, system focus, and sampling interval are parameters which must be carefully chosen and set-up when implementing or using this slope technique to check system performance

The focus group as a tool for health research: issues in design and analysis

The focus group is a technique for eliciting information from specific population subgroups. Issues addressed may be little known or relatively well known to the researcher. The method is most effectively used when the objective of the investigation is to elicit points of view of client or consumer groups which may differ from those of providers. Despite the frequency with which focus groups are used, few published materials describe the practical application of the method. This paper presents a detailed methodology for the conduct of focus groups and analysis of focusgroup data with the intention of improving its use among researchers and health-care professionals. Data from two studies, immunization compliance in West Africa, and barriers to use of prenatal-care services in Bolivia, are used as illustrative examples

OPC and Image Optimization Using Localized Frequency Analysis

A method of assist feature OPC layout is introduced using a frequency model-based approach. Through low-pass spatial frequency filtering of a mask function, the local influence of zero diffraction energy can be determined. By determining isofocal intensity threshold requirements of an imaging process, a mask equalizing function can be designed. This provides the basis for frequency model-based assist feature layout. By choosing assist bar parameters that meet the requirements of the equalizing function, through-pitch focus and dose matching is possible for large two dimensional mask fields. The concepts introduced also lead to additional assist feature options and design flexibility

The effects of transcranial direct current stimulation on within- and cross-paradigm transfer following multi-session backward recall training.

Transcranial direct current stimulation (tDCS) has been shown to enhance the efficacy and generalisation of working memory (WM) training, but there has been little systematic investigation into how coupling task-specific WM training with stimulation impacts more specifically on transfer to untrained tasks. This randomised controlled trial investigated the boundary conditions to transfer by testing firstly whether the benefits of training on backward digit recall (BDR) extend to untrained backward recall tasks and n-back tasks with different materials, and secondly which, if any, form of transfer is enhanced by tDCS. Forty-eight participants were allocated to one of three conditions: BDR training with anodal (10 min, 1 mA) or sham tDCS, or visual search training with sham tDCS, applied over the left dorsolateral prefrontal cortex. Transfer was assessed on within- (backward recall with digits, letters, and spatial locations) and cross-paradigm (n-back with digits and letters) transfer tests following three sessions of training and stimulation. On-task training gains were found, with transfer to other backward span but not n-back tasks. There was little evidence that tDCS enhanced on-task training or transfer. These findings indicate that training enhances paradigm-specific processes within WM, but that tDCS does not enhance these gains

Intact priors for gaze direction in adults with high-functioning autism spectrum conditions

This research was supported by the UK Medical Research Council under project code MC-A060-5PQ50 (Andrew J. Calder). IM was supported by a Leverhulme Trust Project Grant. CC was supported by an Australian Research Council Future Fellowship. SBC was supported by the MRC, the Wellcome Trust and the Autism Research Trust during the period of this work. The research was also supported by the National Institute for Health Research (NIHR) Collaboration for Leadership in Applied Health Research and Care East of England at Cambridgeshire and Peterborough NHS Foundation Trust

Análise morfométrica comparada entre Anuros endêmicos do Brasil e a espécie invasora Lithobates catesbeianus

Anfíbios são indicadores ambientais potencialmente confiáveis e eficientes. Estudos referentes a morfologia de leucócitos de anuros são limitados, com poucos estudos morfometricos disponíveis em literatura. O presente estudo empregou técnicas morfometricas para caracterizar leucócitos de anuros Neotropicais brasileiros selecionados e compara-los com a espécie exótica rã-touro (Lithobates catesbeianus), família Ranidae. Esfregaços sanguíneos de 28 espécimes pertencentes a seis gêneros diferentes (Hyla, Phyllomedusa, Hypsiboas, Scinax, Physalaemus e Proceratophrys) foram comparados com amostras de esfregacos de L. catesbeianus. A média do diâmetro dos leucócitos foi calculada por um software de análise de imagens. One-way e teste de Bonferroni foram utilizados para avaliação estatística. Linfócitos, neutrófilos, eosinófilos e basófilos mostraram-se significativamente menores que os valores de referência reportados em outros gêneros de anfíbios, incluindo Lithobathes; por outro lado, a média do diâmetro dos monócitos não demonstrou variação significativa entre os gêneros. Esse e o primeiro estudo de avaliação morfometrica de leucócitos em espécies de anuros brasileiros. Nossos resultados sugerem que a separação geográfica possivelmente influencia a morfometria leucocitaria.Amphibians are potentially reliable and efficient bioindicators. Existing anuran white blood cell morphology studies are limited, with only a few morphometric studies available. We employed morphometric techniques to characterize leukocytes of selected Neotropical anurans from Brazil and compare our findings with the exotic American Bullfrog (Lithobates catesbeianus), genus Ranidae. We compared blood smears of 28 specimens from six different genera (Hyla, Phyllomedusa, Hypsiboas, Scinax, Physalaemus, and Proceratophrys) with samples from L. catesbeianus. Leukocyte average diameter was calculated by an image analysis software. One-way analyses of variance and Bonferroni tests were used on statistical analyses. Lymphocytes, neutrophils, eosinophils, and basophils were significantly smaller than the reference ranges reported for other amphibian genera, including Lithobathes, whereas monocyte diameters did not differ significantly between genera. This is the first study to evaluate leukocyte morphometrics of Brazilian anuran species. Our findings suggest that geographical separation could possibly influence leukocyte morphometry

Personality influences the neural responses to viewing facial expressions of emotion

Cognitive research has long been aware of the relationship between individual differences in personality and performance on behavioural tasks. However, within the field of cognitive neuroscience, the way in which such differences manifest at a neural level has received relatively little attention. We review recent research addressing the relationship between personality traits and the neural response to viewing facial signals of emotion. In one section, we discuss work demonstrating the relationship between anxiety and the amygdala response to facial signals of threat. A second section considers research showing that individual differences in reward drive (behavioural activation system), a trait linked to aggression, influence the neural responsivity and connectivity between brain regions implicated in aggression when viewing facial signals of anger. Finally, we address recent criticisms of the correlational approach to fMRI analyses and conclude that when used appropriately, analyses examining the relationship between personality and brain activity provide a useful tool for understanding the neural basis of facial expression processing and emotion processing in general

A Two-Gene Balance Regulates Salmonella Typhimurium Tolerance in the Nematode Caenorhabditis elegans

Lysozymes are antimicrobial enzymes that perform a critical role in resisting infection in a wide-range of eukaryotes. However, using the nematode Caenorhabditis elegans as a model host we now demonstrate that deletion of the protist type lysozyme LYS-7 renders animals susceptible to killing by the fatal fungal human pathogen Cryptococcus neoformans, but, remarkably, enhances tolerance to the enteric bacteria Salmonella Typhimurium. This trade-off in immunological susceptibility in C. elegans is further mediated by the reciprocal activity of lys-7 and the tyrosine kinase abl-1. Together this implies a greater complexity in C. elegans innate immune function than previously thought