212 research outputs found
Tracking Single Particles using Surface Plasmon Leakage Radiation Speckle
Label free tracking of small bio-particles such as proteins or viruses is of
great utility in the study of biological processes, however such experiments
are frequently hindered by weak signal strengths and a susceptibility to
scattering impurities. To overcome these problems we here propose a novel
technique leveraging the enhanced sensitivity of both interferometric detection
and the strong field confinement of surface plasmons. Specifically, we show
that interference between the field scattered by an analyte particle and a
speckle reference field, derived from random scattering of surface plasmons
propagating on a rough metal film, enables particle tracking with
sub-wavelength accuracy. We present the analytic framework of our technique and
verify its robustness to noise through Monte Carlo simulations.Comment: Journal of Lightwave Technolog
Multivariate analysis of Brillouin imaging data by supervised and unsupervised learning
Brillouin imaging relies on the reliable extraction of subtle spectral
information from hyperspectral datasets. To date, the mainstream practice has
been using line fitting of spectral features to retrieve the average peak shift
and linewidth parameters. Good results, however, depend heavily on sufficient
SNR and may not be applicable in complex samples that consist of spectral
mixtures. In this work, we thus propose the use of various multivariate
algorithms that can be used to perform supervised or unsupervised analysis of
the hyperspectral data, with which we explore advanced image analysis
applications, namely unmixing, classification and segmentation in a phantom and
live cells. The resulting images are shown to provide more contrast and detail,
and obtained on a timescale faster than fitting. The estimated spectral
parameters are consistent with those calculated from pure fitting
Gendered nationalism : the gender gap in support for the Scottish National Party
Recent major surveys of the Scottish electorate and of Scottish National Party (SNP) members have revealed a distinct gender gap in support for the party. Men are markedly more likely than women to vote for the SNP and they comprise more than two-thirds of its membership. In this article, we use data from those surveys to test various possible explanations for the disproportionately male support for the SNP. While popular accounts have focused on the gendered appeal of recent leaders and on the party’s fluctuating efforts at achieving gender equality in its parliamentary representation, we find much stronger support for a different explanation. Women are less inclined to support and to join the SNP because they are markedly less supportive of its central objective of independence for Scotland. Since men and women barely differ in their reported national identities, the origins of this gender gap in support for independence presents a puzzle for further research
Quantification of plaque stiffness by Brillouin microscopy in experimental thin cap fibroatheroma
Plaques vulnerable to rupture are characterized by a thin and stiff fibrous cap overlaying a soft lipid-rich necrotic core. The ability to measure local plaque stiffness directly to quantify plaque stress and predict rupture potential would be very attractive, but no current technology does so. This study seeks to validate the use of Brillouin microscopy to measure the Brillouin frequency shift, which is related to stiffness, within vulnerable plaques. The left carotid artery of an ApoE-/- mouse was instrumented with a cuff that induced vulnerable plaque development in nine weeks. Adjacent histological sections from the instrumented and control arteries were stained for either lipids or collagen content, or imaged with confocal Brillouin microscopy. Mean Brillouin frequency shift was 15.79±0.09 GHz in the plaque compared with 16.24±0.15 (p \u3c 0.002) and 17.16±0.56 GHz (p \u3c 0.002) in the media of the diseased and control vessel sections, respectively. In addition, frequency shift exhibited a strong inverse correlation with lipid area of 20.67±0.06 (p \u3c 0.01) and strong direct correlation with collagen area of 0.71±0.15 (p \u3c 0.05). This is the first study, to the best of our knowledge, to apply Brillouin spectroscopy to quantify atherosclerotic plaque stiffness, which motivates combining this technology with intravascular imaging to improve detection of vulnerable plaques in patients
Antibiotic dosing in the 'at risk' critically ill patient: Linking pathophysiology with pharmacokinetics/pharmacodynamics in sepsis and trauma patients
Background: Critical illness, mediated by trauma or sepsis, can lead to physiological changes that alter the pharmacokinetics of antibiotics and may result in sub-therapeutic concentrations at the sites of infection. The first aim of this project is to identify the clinical characteristics of critically ill patients with significant trauma that have been recently admitted to ICU that may predict the dosing requirements for the antibiotic, cefazolin. The second aim of this is to identify the clinical characteristics of critically ill patients with sepsis that may predict the dosing requirements for the combination antibiotic, piperacillin-tazobactam
Adaptive multiphoton endomicroscope incorporating a polarization-maintaining multicore optical fiber
Genome-wide changes in genetic diversity in a population of Myotis lucifugus affected by white-nose syndrome
Novel pathogens can cause massive declines in populations, and even extirpation of hosts. But disease can also act as a selective pressure on survivors, driving the evolution of resistance or tolerance. Bat white-nose syndrome (WNS) is a rapidly spreading wildlife disease in North America. The fungus causing the disease invades skin tissues of hibernating bats, resulting in disruption of hibernation behavior, premature energy depletion, and subsequent death. We used whole-genome sequencing to investigate changes in allele frequencies within a population of Myotis lucifugus in eastern North America to search for genetic resistance to WNS. Our results show low F-ST values within the population across time, i.e., prior to WNS (Pre-WNS) compared to the population that has survived WNS (Post-WNS). However, when dividing the population with a geographical cut-off between the states of Pennsylvania and New York, a sharp increase in values on scaffold GL429776 is evident in the Post-WNS samples. Genes present in the diverged area are associated with thermoregulation and promotion of brown fat production. Thus, although WNS may not have subjected the entire M. lucifugus population to selective pressure, it may have selected for specific alleles in Pennsylvania through decreased gene flow within the population. However, the persistence of remnant sub-populations in the aftermath of WNS is likely due to multiple factors in bat life history.Peer reviewe
Molecular epidemiological analysis of Escherichia coli sequence type ST131 (O25:H4) and bla CTX-M-15among extended-spectrum-β- lactamase-producing E. coli from the United States, 2000 to 2009
Escherichia coli sequence type ST131 (from phylogenetic group B2), often carrying the extended-spectrum-β-lactamase (ESBL) gene bla , is an emerging globally disseminated pathogen that has received comparatively little attention in the United States. Accordingly, a convenience sample of 351 ESBL-producing E. coli isolates from 15 U.S. centers (collected in 2000 to 2009) underwent PCR-based phylotyping and detection of ST131 and bla . A total of 200 isolates, comprising 4 groups of 50 isolates each that were (i) bla negative non-ST131, (ii) bla positive non-ST131, (iii) bla negative ST131, or (iv) bla positive ST131, also underwent virulence genotyping, antimicrobial susceptibility testing, and pulsed-field gel electrophoresis (PFGE). Overall, 201 (57%) isolates exhibited bla , whereas 165 (47%) were ST131. ST131 accounted for 56% of bla -positive-versus 35% of bla -negative isolates (
A physical map of Brassica oleracea shows complexity of chromosomal changes following recursive paleopolyploidizations
<p>Abstract</p> <p>Background</p> <p>Evolution of the Brassica species has been recursively affected by polyploidy events, and comparison to their relative, <it>Arabidopsis thaliana</it>, provides means to explore their genomic complexity.</p> <p>Results</p> <p>A genome-wide physical map of a rapid-cycling strain of <it>B. oleracea </it>was constructed by integrating high-information-content fingerprinting (HICF) of Bacterial Artificial Chromosome (BAC) clones with hybridization to sequence-tagged probes. Using 2907 contigs of two or more BACs, we performed several lines of comparative genomic analysis. Interspecific DNA synteny is much better preserved in euchromatin than heterochromatin, showing the qualitative difference in evolution of these respective genomic domains. About 67% of contigs can be aligned to the Arabidopsis genome, with 96.5% corresponding to euchromatic regions, and 3.5% (shown to contain repetitive sequences) to pericentromeric regions. Overgo probe hybridization data showed that contigs aligned to Arabidopsis euchromatin contain ~80% of low-copy-number genes, while genes with high copy number are much more frequently associated with pericentromeric regions. We identified 39 interchromosomal breakpoints during the diversification of <it>B. oleracea </it>and <it>Arabidopsis thaliana</it>, a relatively high level of genomic change since their divergence. Comparison of the <it>B. oleracea </it>physical map with Arabidopsis and other available eudicot genomes showed appreciable 'shadowing' produced by more ancient polyploidies, resulting in a web of relatedness among contigs which increased genomic complexity.</p> <p>Conclusions</p> <p>A high-resolution genetically-anchored physical map sheds light on Brassica genome organization and advances positional cloning of specific genes, and may help to validate genome sequence assembly and alignment to chromosomes.</p> <p>All the physical mapping data is freely shared at a WebFPC site (<url>http://lulu.pgml.uga.edu/fpc/WebAGCoL/brassica/WebFPC/</url>; Temporarily password-protected: account: pgml; password: 123qwe123.</p
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