3,979 research outputs found
Googling the Coronary: Fiberoptics and a Computer Provide the AnswersââEditorials published in JACC: Cardiovascular Imaging reflect the views of the authors and do not necessarily represent the views of JACC: Cardiovascular Imaging or the American College of Cardiology.
Does More And Better Information Enhance Student Performance On Marketing Projects?
There is some controversy over the amount of guidance students need to complete course projects. One school of thought argues that students should have maximum information at their disposal, resulting in a better learning process and thus a better project. The other school of thought suggests that by giving the students too much guidance, the professor is stifling their creativity and original thought. This research examines both scenarios. The results indicate that minimum information provided by the professor encourages students to learn more. However, should the professor decide to provide the students with additional information, such information should be developed by the professor
POWERLIB: SAS/IML Software for Computing Power in Multivariate Linear Models
The POWERLIB SAS/IML software provides convenient power calculations for a wide range of multivariate linear models with Gaussian errors. The software includes the Box, Geisser-Greenhouse, Huynh-Feldt, and uncorrected tests in the "univariate" approach to repeated measures (UNIREP), the Hotelling Lawley Trace, Pillai-Bartlett Trace, and Wilks Lambda tests in "multivariate" approach (MULTIREP), as well as a limited but useful range of mixed models. The familiar univariate linear model with Gaussian errors is an important special case. For estimated covariance, the software provides confidence limits for the resulting estimated power. All power and confidence limits values can be output to a SAS dataset, which can be used to easily produce plots and tables for manuscripts.
A perspective on the potential problems with aspirin as an antithrombotic agent: a comparison of studies in an animal model with clinical trials
AbstractAspirin is the most widely prescribed agent to reduce the platelet-mediated contributions to atherosclerosis, coronary thrombosis and restenosis after angioplasty. While aspirin treatment has led to significant reductions in morbidity and mortality in many clinical trials, there are several scenarios in which aspirin may fail to provide a full antithrombotic benefit. The cyclic flow model of experimental coronary thrombosis suggests that elevations of plasma catecholamines, high shear forces acting on the platelets in the stenosed lumen and the presence of multiple, input stimuli can activate platelets through different mechanisms that may lead to thrombosis despite aspirin therapy. Aspirin therapy is limited because it only blocks some of the input stimuli, leaving aspirin-independent pathways through which coronary thrombosis can be precipitated. These include thrombin and thrombogenic arterial wall substrates such as tissue factor. New agents that block the adenosine diphosphate (ADP) receptor, or regulate platelet free cytosolic calcium, such as direct nitric oxide donors, may be more potent overall than aspirin. Agents that block the platelet integrin GPIIb-IIIa receptor inhibit the binding of fibrinogen to platelets regardless of which input stimuli activate the platelet and, thus, as demonstrated in the cyclic flow model, would be much more potent than aspirin as an antithrombotic agent. The cyclic flow model has been useful in predicting which agents are likely to be of benefit in clinical trials
Methods and Apparatus for In Vivo Identification and Characterization of Vulnerable Atherosclerotic Plaques
Methods and apparatus for analyzing the chemical composition of vulnerable plaques with an intravascular catheter having a near-infrared light source, a fiber-optic probe, a mechanism for directing the light from the light source into a blood vessel, and detectors for detecting light reflected or scattered by the tissue. The light source may be a tunable laser, and may transmit an incident beam having a wavelength ranging from 1400 to 4100 nm. A computer may be included to receive and process the spectral data in the analysis of the vulnerable plaques. A catheter system may be configured to provide near-IR spectrometric imaging of arteries to non-destructively locate and determine lipid pool and fibrous cap size and composition. Additionally, mediators and cellular components may be also determined that are typically associated with vulnerable plaques which have an increased risk of rupture. The lipid pool, fibrous cap, and inflammatory response may serve as an in vivo marker for vulnerable atherosclerotic plaques. Methods are further provided for prospectively identifying and characterizing vulnerable plaques which may include the steps of focusing near-IR light onto a blood vessel wall; detecting the scattered light in the region; and analyzing the resulting spectra across the full preselected wavelength range, particularly in the ranges that include identifying peaks for vulnerable plaque constituents
Theory of transient chimeras in finite Sakaguchi-Kuramoto networks
Chimera states are a phenomenon in which order and disorder can co-exist
within a network that is fully homogeneous. Precisely how transient chimeras
emerge in finite networks of Kuramoto oscillators with phase-lag remains
unclear. Utilizing an operator-based framework to study nonlinear oscillator
networks at finite scale, we reveal the spatiotemporal impact of the adjacency
matrix eigenvectors on the Sakaguchi-Kuramoto dynamics. We identify a specific
condition for the emergence of transient chimeras in these finite networks: the
eigenvectors of the network adjacency matrix create a combination of a zero
phase-offset mode and low spatial frequency waves traveling in opposite
directions. This combination of eigenvectors leads directly to the coherent and
incoherent clusters in the chimera. This approach provides two specific
analytical predictions: (1) a precise formula predicting the combination of
connectivity and phase-lag that creates transient chimeras, (2) a mathematical
procedure for rewiring arbitrary networks to produce transient chimeras
Sustained-release verapamil blunts the morning hemodynamic surge during daily activity: A randomized trial
Variations in the predicted spatial distribution of atmospheric nitrogen deposition and their impact on carbon uptake by terrestrial ecosystems
Widespread mobilization of nitrogen into the atmosphere from industry, agriculture, and biomass burning and its subsequent deposition have the potential to alleviate nitrogen limitation of productivity in terrestrial ecosystems, and may contribute to enhanced terrestrial carbon uptake. To evaluate the importance of the spatial distribution of nitrogen deposition for carbon uptake and to better quantify its magnitude and uncertainty NOy-N deposition fields from five different three-dimensional chemical models, GCTM, GRANTOUR, IMAGES, MOGUNTIA, and ECHAM were used to drive NDEP, a perturbation model of terrestrial carbon uptake. Differences in atmospheric sources of NOx-N, transport, resolution, and representation of chemistry, contribute to the distinct spatial patterns of nitrogen deposition on the global land surface; these differences lead to distinct patterns of carbon uptake that vary between 0.7 and 1.3 Gt C yrâ1 globally. Less than 10% of the nitrogen was deposited on forests which were most able to respond with increased carbon storage because of the wide C:N ratio of wood as well as its long lifetime. Addition of NHx-N to NOy-N deposition, increased global terrestrial carbon storage to between 1.5 and 2.0 Gt C yrâ1, while the âmissing terrestrial sinkâ is quite similar in magnitude. Thus global air pollution appears to be an important influence on the global carbon cycle. If N fertilization of the terrestrial biosphere accounts for the âmissingâ C sink or a substantial portion of it, we would expect significant reductions in its magnitude over the next century as terrestrial ecosystems become N saturated and O3 pollution expands
848-4 Noninvasive characterization of carotid plaque inflammation in humans with FDG-positron emission tomography
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