4,319 research outputs found
Probing polymer chain constraint and synergistic effects in nylon 6-clay nanocomposites and nylon 6-silica flake sub-micro composites with nanomechanics
In this study, we report that a synergistic effect exists in the surface mechanical properties of nylon 6âclay nanocomposites (NC) that can be shown by nanomechanical testing. The hardness, elastic modulus, and nanoindentation creep behavior of nylon 6 and its nanocomposites with different filler loading produced by melt compounding were contrasted to those of model nylon 6 sub-microcomposites (SMC) reinforced by sub-micro-thick silica flakes in which constraint cannot occur due to the difference in filler geometry. Polymer chain constraint was assessed by the analysis of nanoindentation creep data. Time-dependent creep decreased with increasing the filler loading in the NC consistent with the clay platelets exerting a constraint effect on the polymer chains which increases with filler loading. In contrast, there was no evidence of any reduced time-dependent creep for the SMC samples, consistent with a lack of constraint expected due to much lower aspect ratio of the silica flake
Six DOF Motion Estimation for Teleoperated Flexible Endoscopes Using Optical Flow: A Comparative Study
Colorectal cancer is one of the leading causes of cancer-related deaths worldwide, although it can be effectively treated if detected early. Teleoperated flexible endoscopes are an emerging technology to promote participation in these preventive screenings. Real-time pose estimation is therefore essential to enable feedback to the robotic endoscope's control system. Vision-based endoscope localization approaches are a promising avenue, since they do not require extra sensors on board the endoscopes. In this work, we compare several state-of-the-art algorithms for computing the image motion (optical flow), which is then used with a supervised learning strategy to provide an accurate estimate of the 6 degree of freedom endoscope motion. The method is validated using a robotically actuated endoscope in a human colon simulator, and represents a preliminary effort towards testing with clinical video data
Exploring Aspects of Strategic Management for a Small Plant Bakery
This paper explores the use some aspects of strategic management in order to inform a small plant bakery. We briefly review key theories underpinning business strategy and its implementation. A small plant bakery in the UK was analysed, identifying its Critical Success Factors (CSF) and Key Performance Indicators (KPI) comparing these with previous periods and other successful bakery businesses. Furthermore, the case study strategy is used to guide this research. We seek to determine if critical success factors and key performance indicators can be used to improve strategic direction, performance and prioritise new investment. Together with reviewing the small plant bakeryâs employeeâs opinions of how they feel the small plant bakery is achieving on its strategy and CSFâs. The findings of this research are described and further refinements for future research are proposed
Optimization viewpoint on Kalman smoothing, with applications to robust and sparse estimation
In this paper, we present the optimization formulation of the Kalman
filtering and smoothing problems, and use this perspective to develop a variety
of extensions and applications. We first formulate classic Kalman smoothing as
a least squares problem, highlight special structure, and show that the classic
filtering and smoothing algorithms are equivalent to a particular algorithm for
solving this problem. Once this equivalence is established, we present
extensions of Kalman smoothing to systems with nonlinear process and
measurement models, systems with linear and nonlinear inequality constraints,
systems with outliers in the measurements or sudden changes in the state, and
systems where the sparsity of the state sequence must be accounted for. All
extensions preserve the computational efficiency of the classic algorithms, and
most of the extensions are illustrated with numerical examples, which are part
of an open source Kalman smoothing Matlab/Octave package.Comment: 46 pages, 11 figure
Human-specific CpG 'beacons' identify human-specific prefrontal cortex H3K4me3 chromatin peaks.
Background: Targeted recruitment of chromatin-modifying enzymes to clusters of CpG dinucleotides contributes toward the formation of accessible chromatin. By interprimate comparison we previously identified the set of nonpolymorphic human-specific CpGs (CpG 'beacons') and revealed that these loci were enriched for human disease traits. Due to their human-specific CpG density change, extreme CpG 'beacon' clusters (â„20 CpG beacons/kb) were predicted to identify permissive chromatin peaks within the human genome. Aim: We set out to explore these sequence-defined regions for evidence of an active chromatin signature. Results: Using available comparative primate epigenomic data from neurons of the prefrontal cortex, we show that these CpG 'beacon' clusters are indeed enriched for being human-specific H3K4me3 peaks (Ï(2): p < 2.2 Ă 10(-16)) and thus predictive of permissive chromatin states. These sequence regions had a higher predictive value than previous selective analyses. We also show that both human-specific H3K4me3 and CpG 'beacon' clusters are increased within current and ancestral telomeric regions, supporting an association with recombination, which is higher towards the distal ends of chromosomes. Conclusion: Therefore, CpG-focused comparative sequence analysis can precisely pinpoint chromatin structures that contribute to the human-specific phenotype and further supports an integrated approach in genomic and epigenomic studies
Timing and Outcomes of an IndicationâOnly Use of Intravenous Cannulation During Spontaneous Labor
Peer Reviewedhttps://deepblue.lib.umich.edu/bitstream/2027.42/155888/1/jmwh13046_am.pdfhttps://deepblue.lib.umich.edu/bitstream/2027.42/155888/2/jmwh13046.pd
Radiographic Image Enhancement by Wiener Decorrelation
The primary focus of the application of image processing to radiography is the problem of segmentation. The general segmentation problem has been attacked on a broad front [1, 2], and thresholding, in particular, is a popular method [1, 3-6]. Unfortunately, geometric unsharpness destroys the crisp edges needed for unambiguous decisions, and this difficulty can be considered a problem in filtering in which the object is to devise a high-pass (sharpening) filter. This approach has been studied for more than 20 years [7-13]
Distances from Surface Brightness Fluctuations
The practice of measuring galaxy distances from their spatial fluctuations in
surface brightness is now a decade old. While several past articles have
included some review material, this is the first intended as a comprehensive
review of the surface brightness fluctuation (SBF) method. The method is
conceptually quite simple, the basic idea being that nearby (but unresolved)
star clusters and galaxies appear "bumpy", while more distant ones appear
smooth. This is quantified via a measurement of the amplitude of the Poisson
fluctuations in the number of unresolved stars encompassed by a CCD pixel
(usually in an image of an elliptical galaxy). Here, we describe the technical
details and difficulties involved in making SBF measurements, discuss
theoretical and empirical calibrations of the method, and review the numerous
applications of the method from the ground and space, in the optical and
near-infrared. We include discussions of stellar population effects and the
"universality" of the SBF standard candle. A final section considers the future
of the method.Comment: Invited review article to appear in: `Post-Hipparcos Cosmic Candles',
A. Heck & F. Caputo (Eds), Kluwer Academic Publ., Dordrecht, in press. 22
pages, including 3 postscript figures; uses Kluwer's crckapb.sty LaTex macro
file, enclose
Human-specific CpG "beacons" identify loci associated with human-specific traits and disease.
Regulatory change has long been hypothesized to drive the delineation of the human phenotype from other closely related primates. Here we provide evidence that CpG dinucleotides play a special role in this process. CpGs enable epigenome variability via DNA methylation, and this epigenetic mark functions as a regulatory mechanism. Therefore, species-specific CpGs may influence species-specific regulation. We report non-polymorphic species-specific CpG dinucleotides (termed "CpG beacons") as a distinct genomic feature associated with CpG island (CGI) evolution, human traits and disease. Using an inter-primate comparison, we identified 21 extreme CpG beacon clusters (â„ 20/kb peaks, empirical p < 1.0 Ă 10(-3)) in humans, which include associations with four monogenic developmental and neurological disease related genes (Benjamini-Hochberg corrected p = 6.03 Ă 10(-3)). We also demonstrate that beacon-mediated CpG density gain in CGIs correlates with reduced methylation in these species in orthologous CGIs over time, via human, chimpanzee and macaque MeDIP-seq. Therefore mapping into both the genomic and epigenomic space the identified CpG beacon clusters define points of intersection where a substantial two-way interaction between genetic sequence and epigenetic state has occurred. Taken together, our data support a model for CpG beacons to contribute to CGI evolution from genesis to tissue-specific to constitutively active CGIs
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