Examining the locus of age effects on complex span tasks.

To investigate the locus of age effects on complex span tasks, the authors evaluated the contributions of working memory functions and processing speed. Age differences were found in measures of storage capacity, language processing speed, and lower level speed. Statistically controlling for each of these in hierarchical regressions substantially reduced, but did not eliminate, the complex span age effect. Accounting for lower level speed and storage, however, removed essentially the entire age effect, suggesting that both functions play important and independent roles. Additional evidence for the role of storage capacity was the absence of complex span age differences with span size calibrated to individual word span performance. Explanations for age differences based on inhibition and concurrent task performance were not supported. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

A Toxicology Suite Adapted for Comparing Parallel Toxicity Responses of Model Human Lung Cells to Diesel Exhaust Particles and Their Extracts

Epidemiological studies have shown that exposure to airborne particulate matter (PM) can be an important risk factor for some common respiratory diseases. While many studies have shown that PM exposures are associated with inflammatory reactions, the role of specific cellular responses in the manifestation of primary hypersensitivities and the progression of respiratory diseases remains unclear. In order to better understand mechanisms by which PM can exert adverse health effects, more robust approaches to support in vitro studies are warranted. In response to this need, a group of accepted toxicology assays was adapted to create an analytical suite for screening and evaluating the effects of important, ubiquitous atmospheric pollutants on two model human lung cell lines (epithelial and immature macrophage). To demonstrate the utility of this suite, responses to intact diesel exhaust particles (DEP) and mass-based equivalent doses of their organic extracts were examined. Results suggest that extracts have the potential to induce greater biological responses than those associated with their colloidal counterpart. Additionally, macrophage cells appear to be more susceptible to the cytotoxic effects of both intact DEP and their organic extract, than epithelial cells tested in parallel. As designed, the suite provided a more robust basis for characterizing toxicity mechanisms than the analysis of any individual assay. Findings suggest that cellular responses to PM are cell line dependent, and show that the collection and preparation of PM and/or their extracts have the potential to impact cellular responses relevant to screening fundamental elements of respiratory toxicity.

Copyright 2015 American Association for Aerosol Research     

Effects of source coherence and aperture array geometry on optical sectioning strength in direct-view microscopy

Laser sources offer a possible solution to the problem of low light throughput in direct-view microscopes (DVMs). However, coherent source DVMs have been shown to suffer from problems such as increased sidelobes in the depth response because of coherent cross talk between neighboring apertures. We explore theoretically how source coherence affects the depth responses of DVMs by employing various aperture spacings and number of apertures. We show that, contrary to expectation, closely spaced apertures can result in decreased full width at half-maximum of the depth response curve. We explain this as an effect of destructive interference when cross talk between neighboring apertures occurs. Using apertures arranged in a square grid as an example, we move on to show that the use of aperture arrays that consist of regularly arranged apertures can accentuate the problematic sidelobes of the depth response. We show that arranging pinholes in a rectangular grid rather than a square grid can improve the optical sectioning strength significantly. Finally, by examination of the depth responses corresponding to the infinite-pinhole-array limit, we make some general statements about source coherence and the characteristics of arrays that are likely to perform well.     

Theory of spatiochromatic image encoding and feature extraction

We consider how to interpret, filter, and cross-correlate complex-value color (hue and saturation) images by using a single discrete Fourier transform: the spatiochromatic discrete Fourier transform. The model defines new types of spatiochromatic oriented sinusoidal gratings, termed rainbow gratings, which encode the variation of color over space. We demonstrate how color-opponent detectors observed within the vertebrate visual system can be easily defined by linear filters within this representation. This model also allows us to filter and detect both spatial and chromatic patterns in images by using a single cross-correlation procedure. In doing so, we explore a new form of the Cauchy-Schwartz inequality applied to complex-valued scalar products. Results demonstrate the power of this form of spatiochromatic matched filtering in detecting signals embedded in such a significant amount of noise that they are not visible to the unaided human eye.     

Insertion element IS3-based PCR method for subtyping Escherichia coli O157:H7

An Escherichia coli O157:H7 subtyping method based on PCR amplification of variable DNA sequences between the repetitive element IS3 was developed. Template DNA was prepared by boiling cells in Chelex. Two separate IS3 PCR amplifications were performed for each isolate: one with a single primer (primer IS3A) and one with two primers (primers IS3A and IS3B). The IS3 PCR subtyping method was applied to 35 epidemiologically related and unrelated E. coli O157:H7 isolates that had been previously characterized by pulsed-field gel electrophoresis (PFGE). PFGE identified 25 different subtypes (difference of one or more bands). PCR with single primer IS3A and primer pair IS3A-IS3B identified 6 and 14 different subtypes, respectively. By combining the results of the two PCR amplifications, 15 different IS3 PCR subtypes were identified. While not as sensitive as PFGE, IS3 PCR subtyping grouped all outbreak-related isolates. IS3 PCR banding patterns were reproducible between amplifications and between subcultures. IS3 PCR could serve as a simple, rapid screening method for the identification of unrelated E. coli O157:H7 isolates.