520 research outputs found
Brain MRI segmentation and lesion detection using generalized Gaussian and Rician modeling
In this paper we propose a mixed noise modeling so as to segment the brain and to detect lesion. Indeed, accurate segmentation of multimodal (T1, T2 and Flair) brain MR images is of great interest for many brain disorders but requires to efficiently manage multivariate correlated noise between available modalities. We addressed this problem in1 by proposing an entirely unsupervised segmentation scheme, taking into account multivariate Gaussian noise, imaging artifacts,intrinsic tissue variation and partial volume effects in a Bayesian framework. Nevertheless, tissue classification remains a challenging task especially when one addresses the lesion detection during segmentation process2 as we did. In order to improve brain segmentation into White and Gray Matter (resp. WM and GM) and cerebro-spinal fluid (CSF), we propose to fit a Rician (RC) density distribution for CSF whereas Generalized Gaussian (GG) models are used to fit the likelihood between model and data corresponding to WM and GM. In this way, we present in this paper promising results showing that in a multimodal segmentation-detection scheme, this model fits better with the data and increases lesion detection rate. One of the main challenges consists in being able to take into account various pdf (Gaussian and non- Gaussian) for correlated noise between modalities and to show that lesion-detection is then clearly improved, probably because non-Gaussian noise better fits to the physic of MRI image acquisition
Using genotyping-by-sequencing to understand Musa diversity
Poster presented at Plant and Animal Genome, PAG XXII. San Diego (USA), 11-15 Jan 201
Retrieval of publications addressing shared decision making: an evaluation of full-text searches on medical journal websites.
BACKGROUND: Full-text searches of articles increase the recall, defined by the proportion of relevant publications that are retrieved. However, this method is rarely used in medical research due to resource constraints. For the purpose of a systematic review of publications addressing shared decision making, a full-text search method was required to retrieve publications where shared decision making does not appear in the title or abstract.
OBJECTIVE: The objective of our study was to assess the efficiency and reliability of full-text searches in major medical journals for identifying shared decision making publications.
METHODS: A full-text search was performed on the websites of 15 high-impact journals in general internal medicine to look up publications of any type from 1996-2011 containing the phrase "shared decision making". The search method was compared with a PubMed search of titles and abstracts only. The full-text search was further validated by requesting all publications from the same time period from the individual journal publishers and searching through the collected dataset.
RESULTS: The full-text search for "shared decision making" on journal websites identified 1286 publications in 15 journals compared to 119 through the PubMed search. The search within the publisher-provided publications of 6 journals identified 613 publications compared to 646 with the full-text search on the respective journal websites. The concordance rate was 94.3% between both full-text searches.
CONCLUSIONS: Full-text searching on medical journal websites is an efficient and reliable way to identify relevant articles in the field of shared decision making for review or other purposes. It may be more widely used in biomedical research in other fields in the future, with the collaboration of publishers and journals toward open-access data
Squeezing enhancement by damping in a driven atom-cavity system
In a driven atom-cavity coupled system in which the two-level atom is driven
by a classical field, the cavity mode which should be in a coherent state in
the absence of its reservoir, can be squeezed by coupling to its reservoir. The
squeezing effect is enhanced as the damping rate of the cavity is increased to
some extent.Comment: 3 pages and 3 figure
Publication trends of shared decision making in 15 high impact medical journals: a full-text review with bibliometric analysis.
BACKGROUND: Shared Decision Making (SDM) is increasingly advocated as a model for medical decision making. However, there is still low use of SDM in clinical practice. High impact factor journals might represent an efficient way for its dissemination. We aimed to identify and characterize publication trends of SDM in 15 high impact medical journals.
METHODS: We selected the 15 general and internal medicine journals with the highest impact factor publishing original articles, letters and editorials. We retrieved publications from 1996 to 2011 through the full-text search function on each journal website and abstracted bibliometric data. We included publications of any type containing the phrase "shared decision making" or five other variants in their abstract or full text. These were referred to as SDM publications. A polynomial Poisson regression model with logarithmic link function was used to assess the evolution across the period of the number of SDM publications according to publication characteristics.
RESULTS: We identified 1285 SDM publications out of 229,179 publications in 15 journals from 1996 to 2011. The absolute number of SDM publications by journal ranged from 2 to 273 over 16 years. SDM publications increased both in absolute and relative numbers per year, from 46 (0.32% relative to all publications from the 15 journals) in 1996 to 165 (1.17%) in 2011. This growth was exponential (P < 0.01). We found fewer research publications (465, 36.2% of all SDM publications) than non-research publications, which included non-systematic reviews, letters, and editorials. The increase of research publications across time was linear. Full-text search retrieved ten times more SDM publications than a similar PubMed search (1285 vs. 119 respectively).
CONCLUSION: This review in full-text showed that SDM publications increased exponentially in major medical journals from 1996 to 2011. This growth might reflect an increased dissemination of the SDM concept to the medical community
State Transition Algorithm
In terms of the concepts of state and state transition, a new heuristic
random search algorithm named state transition algorithm is proposed. For
continuous function optimization problems, four special transformation
operators called rotation, translation, expansion and axesion are designed.
Adjusting measures of the transformations are mainly studied to keep the
balance of exploration and exploitation. Convergence analysis is also discussed
about the algorithm based on random search theory. In the meanwhile, to
strengthen the search ability in high dimensional space, communication strategy
is introduced into the basic algorithm and intermittent exchange is presented
to prevent premature convergence. Finally, experiments are carried out for the
algorithms. With 10 common benchmark unconstrained continuous functions used to
test the performance, the results show that state transition algorithms are
promising algorithms due to their good global search capability and convergence
property when compared with some popular algorithms.Comment: 18 pages, 28 figure
Analysis of stellar spectra with 3D and NLTE models
Models of radiation transport in stellar atmospheres are the hinge of modern
astrophysics. Our knowledge of stars, stellar populations, and galaxies is only
as good as the theoretical models, which are used for the interpretation of
their observed spectra, photometric magnitudes, and spectral energy
distributions. I describe recent advances in the field of stellar atmosphere
modelling for late-type stars. Various aspects of radiation transport with 1D
hydrostatic, LTE, NLTE, and 3D radiative-hydrodynamical models are briefly
reviewed.Comment: 21 pages, accepted for publication as a chapter in "Determination of
Atmospheric Parameters of B, A, F and G Type Stars", Springer (2014), eds. E.
Niemczura, B. Smalley, W. Pyc
Potentiation of thrombus instability: a contributory mechanism to the effectiveness of antithrombotic medications
© The Author(s) 2018The stability of an arterial thrombus, determined by its structure and ability to resist endogenous fibrinolysis, is a major determinant of the extent of infarction that results from coronary or cerebrovascular thrombosis. There is ample evidence from both laboratory and clinical studies to suggest that in addition to inhibiting platelet aggregation, antithrombotic medications have shear-dependent effects, potentiating thrombus fragility and/or enhancing endogenous fibrinolysis. Such shear-dependent effects, potentiating the fragility of the growing thrombus and/or enhancing endogenous thrombolytic activity, likely contribute to the clinical effectiveness of such medications. It is not clear how much these effects relate to the measured inhibition of platelet aggregation in response to specific agonists. These effects are observable only with techniques that subject the growing thrombus to arterial flow and shear conditions. The effects of antithrombotic medications on thrombus stability and ways of assessing this are reviewed herein, and it is proposed that thrombus stability could become a new target for pharmacological intervention.Peer reviewedFinal Published versio
Existence and stability of hole solutions to complex Ginzburg-Landau equations
We consider the existence and stability of the hole, or dark soliton,
solution to a Ginzburg-Landau perturbation of the defocusing nonlinear
Schroedinger equation (NLS), and to the nearly real complex Ginzburg-Landau
equation (CGL). By using dynamical systems techniques, it is shown that the
dark soliton can persist as either a regular perturbation or a singular
perturbation of that which exists for the NLS. When considering the stability
of the soliton, a major difficulty which must be overcome is that eigenvalues
may bifurcate out of the continuous spectrum, i.e., an edge bifurcation may
occur. Since the continuous spectrum for the NLS covers the imaginary axis, and
since for the CGL it touches the origin, such a bifurcation may lead to an
unstable wave. An additional important consideration is that an edge
bifurcation can happen even if there are no eigenvalues embedded in the
continuous spectrum. Building on and refining ideas first presented in Kapitula
and Sandstede (Physica D, 1998) and Kapitula (SIAM J. Math. Anal., 1999), we
show that when the wave persists as a regular perturbation, at most three
eigenvalues will bifurcate out of the continuous spectrum. Furthermore, we
precisely track these bifurcating eigenvalues, and thus are able to give
conditions for which the perturbed wave will be stable. For the NLS the results
are an improvement and refinement of previous work, while the results for the
CGL are new. The techniques presented are very general and are therefore
applicable to a much larger class of problems than those considered here.Comment: 41 pages, 4 figures, submitte
The disulphide isomerase DsbC cooperates with the oxidase DsbA in a DsbD-independent manner
In Escherichia coli , DsbA introduces disulphide bonds into secreted proteins. DsbA is recycled by DsbB, which generates disulphides from quinone reduction. DsbA is not known to have any proofreading activity and can form incorrect disulphides in proteins with multiple cysteines. These incorrect disulphides are thought to be corrected by a protein disulphide isomerase, DsbC, which is kept in the reduced and active configuration by DsbD. The DsbC/DsbD isomerization pathway is considered to be isolated from the DsbA/DsbB pathway. We show that the DsbC and DsbA pathways are more intimately connected than previously thought. dsbA - dsbC - mutants have a number of phenotypes not exhibited by either dsbA - , dsbC - or dsbA - dsbD - mutations: they exhibit an increased permeability of the outer membrane, are resistant to the lambdoid phage φ80, and are unable to assemble the maltoporin LamB. Using differential two-dimensional liquid chromatographic tandem mass spectrometry/mass spectrometry analysis, we estimated the abundance of about 130 secreted proteins in various dsb - strains. dsbA - dsbC - mutants exhibit unique changes at the protein level that are not exhibited by dsbA - dsbD - mutants. Our data indicate that DsbC can assist DsbA in a DsbD-independent manner to oxidatively fold envelope proteins. The view that DsbC's function is limited to the disulphide isomerization pathway should therefore be reinterpreted.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/72894/1/MMI_6030_sm_Tables_S1-S4.pdfhttp://deepblue.lib.umich.edu/bitstream/2027.42/72894/2/MMI_tables_s1-s4.pdfhttp://deepblue.lib.umich.edu/bitstream/2027.42/72894/3/j.1365-2958.2007.06030.x.pd
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