133,210 research outputs found
Ku-band field-effect power transistors
A single stage amplifier was developed using an 8 gate, 1200 micrometer width device to give a gain of 3.3 + or - 0.1 dB over the 14.4 to 15.4 GHz band with an output power of 0.48 W and 15% minimum efficiency with 0.255 W of input power. With two 8 gate devices combined and matched on the device carrier, using a lumped element format, a gain of 3 dB was attained over the 14.5 to 15.5 GHz band with a maximum efficiency of 9.9% for an output power of 0.8 W
A study of the ferromagnetic transition of in nanometer thick bilayers with , , Au and Cr: Signature of injected carriers in the pseudogap regime
The hypothesis regarding the existence of uncorrelated pre-formed pairs in
the pseudogap regime of superconducting is tested experimentally
using bilayers of and the itinerant ferromagnet . In
our study, we monitor the influence of on , the
ferromagnetic ordering temperature of . Here, is the temperature
of maximum dM/dT or dR/dT where M and R are the magnetization and resistance of
, respectively. We compare the results with similar measurements
carried out on bilayers of , and with
. We find that in bilayers made of underdoped 10 nm /5
nm , the values are shifted to lower temperatures by up to 6-8 K
as compared to K of the 5 nm thick reference film.
In contrast, in the other type of bilayers, which are not in the pseudogap
regime near , only a smaller shift of up to 2 K is observed. These
differences are discussed in terms of a proximity effect, where carriers from
the layer are injected into the layer and vice versa.
We suggest that correlated electrons in the pseudogap regime of
are responsible for the observed large shifts.Comment: 9 figure
Geometries for Possible Kinematics
The algebras for all possible Lorentzian and Euclidean kinematics with
isotropy except static ones are re-classified. The geometries
for algebras are presented by contraction approach. The relations among the
geometries are revealed. Almost all geometries fall into pairs. There exists correspondence in each pair. In the viewpoint of
differential geometry, there are only 9 geometries, which have right signature
and geometrical spatial isotropy. They are 3 relativistic geometries, 3
absolute-time geometries, and 3 absolute-space geometries.Comment: 40 pages, 7 figure
The relationship between corpus callosum size and forebrain volume
Using high-resolution in vivo magnetic resonance morphometry we measured forebrain volume (FBV), midsagittal size of the corpus callosum (CC) and four CC subareas in 120 young and healthy adults (49 women, 71 men). We found moderate linear and quadratic correlations, indicating that the CC and all CC subareas increase with FBV both in men and women (multiple r2 ranging from 0.10 to 0.28). Allometric equations revealed that these increases were less than proportional to FBV (r2 ranging from 0.02 to 0.30). Absolute CC measurements, as well as CC subareas relative to total CC or FBV (the latter measures termed the CC ratios), were further analyzed with regard to possible effects of handedness, gender, or handedness by gender interaction. Contrary to previous reports, left-handers did not show larger CC measurements compared to right-handers. The only apparent influence of gender was on the CC ratios, which were larger in women. However, smaller brains had larger CC ratios which were mainly independent of gender, a result of the less than proportional increase of callosal size with FBV. We suggest that the previously described gender differences in CC anatomy may be better explained by an underlying effect of brain size, with larger brains having relatively smaller callosa. This lends empirical support to the hypothesis that brain size may be an important factor influencing interhemispheric connectivity and lateralizatio
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