120 research outputs found
Characterization and Compensation of the Residual Chirp in a Mach-Zehnder-Type Electro-Optical Intensity Modulator
We utilize various techniques to characterize the residual phase modulation
of a fiber-based Mach-Zehnder electro-optical intensity modulator. A heterodyne
technique is used to directly measure the phase change due to a given change in
intensity, thereby determining the chirp parameter of the device. This chirp
parameter is also measured by examining the ratio of sidebands for sinusoidal
amplitude modulation. Finally, the frequency chirp caused by an intensity pulse
on the nanosecond time scale is measured via the heterodyne signal. We show
that this chirp can be largely compensated with a separate phase modulator. The
various measurements of the chirp parameter are in reasonable agreement.Comment: 11 pages, 6 figure
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
Variations in mineralogy of dust in an ice core obtained from northwestern Greenland over the past 100 years
Our study is the first to demonstrate a
high-temporal-resolution record of mineral composition in a Greenland ice
core over the past 100 years. To reconstruct past variations in the sources
and transportation processes of mineral dust in northwestern Greenland, we
analysed the morphology and mineralogical composition of dust in the SIGMA-D
ice core from 1915 to 2013 using scanning electron microscopy (SEM) and
energy-dispersive X-ray spectroscopy (EDS). The results revealed that the
ice core dust consisted mainly of silicate minerals and that the composition
varied substantially on multi-decadal and inter-decadal scales, suggesting
that the ice core minerals originated from different geological sources in
different periods during the past 100 years. The multi-decadal variation
trend differed among mineral types. Kaolinite, which generally formed in
warm and humid climatic zones, was abundant in colder periods (1950–2004),
whereas mica, chlorite, feldspars, mafic minerals, and quartz, which
formed in arid, high-latitude, and local areas, were abundant in warmer
periods (1915–1949 and 2005–2013). Comparison to Greenland surface
temperature records indicates that multi-decadal variation in the relative
abundance of these minerals was likely affected by local temperature changes
in Greenland. Trajectory analysis shows that the minerals were transported
mainly from the western coast of Greenland in the two warming periods, which
was likely due to an increase in dust sourced from local ice-free areas as a
result of shorter snow/ice cover duration in the Greenland coastal region
during the melt season caused by recent warming. Meanwhile, ancient deposits
in northern Canada, which were formed in past warmer climates, seem to be the
best candidate during the colder period (1950–2004). Our results suggest
that SEM–EDS analysis can detect variations in ice core dust sources during
recent periods of low dust concentration.</p
Chronosequence of pedogenesis and Quaternary Paleoenvironment in Kunming Basin, Yunnan Province, China
Mineralogical composition of iron oxides in red- and yellow-colored soils from Southern Japan and Yunnan, China
Urinary Glycosaminoglycans in Patients with Hypothyroidism and in Healthy Subjects
Peer Reviewe
Determination of some toxic trace metals in Nigerian river and harbor water samples by neutron activation analysis
Phosphatidylglucoside Forms Specific Lipid Domains on the Outer Leaflet of the Plasma Membrane
Expression of Collagen IV .ALPHA.1 to .ALPHA.6 Chains in Basement Membranes of Odontogenic Tumors
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