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Background
Saccadic eye movements align the two eyes precisely to foveate a target. Trial-by-trial variance of eye movement is always observed within an identical experimental condition. This has often been treated as experimental error without addressing its significance. The present study examined statistical linkages between the two eyes’ movements, namely interocular yoking, for the variance of eye position and velocity.Methods
Horizontal saccadic movements were recorded from twelve right-eye-dominant subjects while they decided on saccade direction in Go-Only sessions and on both saccade execution and direction in Go/NoGo sessions. We used infrared corneal reflection to record simultaneously and independently the movement of each eye. Quantitative measures of yoking were provided by mutual information analysis of eye position or velocity, which is sensitive to both linear and non-linear relationships between the eyes’ movements. Our mutual information analysis relied on the variance of the eyes movements in each experimental condition. The range of movements for each eye varies for different conditions so yoking was further studied by comparing GO-Only vs. Go/NoGo sessions, leftward vs. rightward saccades.Results
Mutual information analysis showed that velocity yoking preceded positional yoking. Cognitive load increased trial variances of velocity with no increase in velocity yoking, suggesting that cognitive load may alter neural processes in areas to which oculomotor control is not tightly linked. The comparison between experimental conditions showed that interocular linkage in velocity variance of the right eye lagged that of the left eye during saccades.Conclusions
We conclude quantitative measure of interocular yoking based on trial-to-trial variance within a condition, as well as variance between conditions, provides a powerful tool for studying the binocular movement mechanism.23.
Benjamin D. Shogan Daniel P. Smith Aaron I. Packman Scott T. Kelley Emily M Landon Seema Bhangar Gary J. Vora Rachael M. Jones Kevin Keegan Brent Stephens Tiffanie Ramos Benjamin C. Kirkup Jr. Hal Levin Mariana Rosenthal Betsy Foxman Eugene B. Chang Jeffrey Siegel Sarah Cobey Gary An John C. Alverdy Paula J. Olsiewski Mark O. Martin Rachel Marrs Mark Hernandez Scott Christley Michael Morowitz Stephen Weber Jack Gilbert 《Standards in genomic sciences》2013,8(3):571-579
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Optical mapping of bacterial chromosomes provides an unambiguous low-resolution sequence scaffold of the entire chromosome. In comparison to some techniques, such as pulse field gel electrophoresis, cost and throughput limit the application of this technique outside of genome finishing. We have demonstrated the production of multiple bacterial maps using a single set of consumables; this significantly reduces the time and expense of map production. 相似文献
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McQueary CN Kirkup BC Si Y Barlow M Actis LA Craft DW Zurawski DV 《Journal of microbiology (Seoul, Korea)》2012,50(3):434-443
Acinetobacter baumannii is a nosocomial bacterial pathogen, and infections attributed to this species are further complicated by a remarkable ability to acquire antimicrobial resistance genes and to survive in a desiccated state. While the antibiotic resistance and biofilm formation of A. baumannii is well-documented, less is known about the virulence attributes of this organism. Recent studies reported A. baumannii strains display a motility phenotype, which appears to be partially dependent upon Type IV pili, autoinducer molecules, and the response to blue light. In this study, we wanted to determine the prevalence of this trait in genetically diverse clinical isolates, and any additional required factors, and environmental cues that regulate motility. When strains are subjected to a wide array of stress conditions, A. baumannii motility is significantly reduced. In contrast, when extracellular iron is provided or salinity is reduced, motility is significantly enhanced. We further investigated whether the genes required for the production of lipopolysaccharide (lpsB) and K1 capsule (epsA/ptk) are required for motility as demonstrated in other Gram-negative bacteria. Transposon mutagenesis resulted in reduced motility by the insertion derivatives of each of these genes. The presence of the parental allele provided in trans, in the insertion mutant background, could only restore motility in the lpsB mutant. The production of core LPS directly contributes to the motility phenotype, while capsular polysaccharide may have an indirect effect. Further, the data suggest motility is regulated by extracellular conditions, indicating that A. baumannii is actively sensing the environment and responding accordingly. 相似文献
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Andreas A Ioannides Peter BC Fenwick Elina Pitri Lichan Liu 《Nonlinear biomedical physics》2010,4(Z1):S11
Background
Identifying eye movement related areas in the frontal lobe has a long history, with microstimulation in monkeys producing the most clear-cut results. For humans, however, there is still no consensus about the location and the extent of the frontal eye field (FEF). There is also no simple non-invasive method for unambiguously defining the FEF in individual subjects, a prerequisite for clinical applications. Here we explore the use of magnetoencephalography (MEG) for the non-invasive identification and characterization of FEF activity in an individual subject.Methods
We mapped human brain activity before, during and after saccades by applying tomographic analysis to MEG data. Statistical parametric maps and circular statistics produced plausible FEF loci, but no unambiguous definition for individual subjects. Here we first computed the spectral decomposition and correlation with electrooculogram (EOG) of the tomographic brain activations. For each of these two measures statistical comparisons were made between different saccades.Results
In this paper, we first review the frontal cortex activations identified in earlier animal and human studies and place the putative human FEFs in a well-defined anatomical framework. This framework is then used as reference for describing the results of new Fourier analysis of the tomographic solutions comparing active saccade tasks and their controls. The most consistent change in the dorsal frontal cortex was at the putative left FEF, for both saccades to the left and right. The asymmetric result is consistent with the 1-way callosal traffic theory. We also showed that the new correlation analysis had its most consistent change in the contralateral putative FEF. This result was obtained for EOG latencies before saccade onset with delays of a few hundreds of milliseconds (FEF activity leading the EOG) and only for visual cues signaling the execution of a saccade in a previously defined saccade direction.Conclusions
The FEF definition derived from microstimulation describes only one of the areas in the dorsal lateral frontal lobe that act together to plan, prepare and execute a saccade. The definition and characterization of these areas in an individual subject can be obtained from non-invasive MEG measurements.27.
Sundeep Dugar Michael P. Kirkup John W. Clader Sue-Ing Lin Razia Rizvi Mark E. Snow Harry R. Davis Jr. Stuart W. McCombie 《Bioorganic & medicinal chemistry letters》1995,5(24):2947-2952
Our search for potent cholesterol absorption inhibitors led to the discovery of the β-lactam SCH 48461. Structure activity relationship studies prompted us to this study of γ-lactams, ring homologs of β-lactam SCH 48461, to determine their potential as cholesterol absorption inhibitors. The results indicate that the γ-lactams have moderate cholesterol absorption inhibitory properties. 相似文献
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4β-Hydroxydictyodial A and 18,O-dihydro-4β-hydroxydictyodial A 18-acetate are two minor aldehydic diterpenes in the brown alga Dictyota crenulata. 1H NMR and lanthanide-induced chemical shift studies indicate that the relative stereochemistry of both compounds is 2R*, 3R*, 4S*, 10S*. 相似文献
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S. J. Mayo R. Allkin W. Baker V. Blagoderov I. Brake B. Clark R. Govaerts C. Godfray A. Haigh R. Hand K. Harman M. Jackson N. Kilian D. W. Kirkup I. Kitching S. Knapp G. P. Lewis P. Malcolm E. von Raab-Straube D. M. Roberts M. Scoble D. A. Simpson C. Smith V. Smith S. Villalba L. Walley P. Wilkin 《Kew Bulletin》2008,63(1):1-16
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Daniel Smith John Alverdy Gary An Maureen Coleman Sylvia Garcia-Houchins Jessica Green Kevin Keegan Scott T. Kelley Benjamin C. Kirkup Larry Kociolek Hal Levin Emily Landon Paula Olsiewski Rob Knight Jeffrey Siegel Stephen Weber Jack Gilbert 《Standards in genomic sciences》2013,8(1):112-117
This report details the outcome of the 1st Hospital Microbiome Project workshop held on June 7th-8th, 2012 at the University of Chicago, USA. The workshop was arranged to determine the most appropriate sampling strategy and approach to building science measurement to characterize the development of a microbial community within a new hospital pavilion being built at the University of Chicago Medical Center. The workshop made several recommendations and led to the development of a full proposal to the Alfred P. Sloan Foundation as well as to the creation of the Hospital Microbiome Consortium. 相似文献