14,144 research outputs found
Fluxon Dynamics of a Long Josephson Junction with Two-gap Superconductors
We investigate the phase dynamics of a long Josephson junction (LJJ) with
two-gap superconductors. In this junction, two channels for tunneling between
the adjacent superconductor (S) layers as well as one interband channel within
each S layer are available for a Cooper pair. Due to the interplay between the
conventional and interband Josephson effects, the LJJ can exhibit unusual phase
dynamics. Accounting for excitation of a stable 2-phase texture arising
from the interband Josephson effect, we find that the critical current between
the S layers may become both spatially and temporally modulated. The spatial
critical current modulation behaves as either a potential well or barrier,
depending on the symmetry of superconducting order parameter, and modifies the
Josephson vortex trajectories. We find that these changes in phase dynamics
result in emission of electromagnetic waves as the Josephson vortex passes
through the region of the 2-phase texture. We discuss the effects of this
radiation emission on the current-voltage characteristics of the junction.Comment: 14 pages, 6 figure
Vascular remodeling of the mouse yolk sac requires hemodynamic force
The embryonic heart and vessels are dynamic and form and remodel while functional. Much has been learned about the genetic
mechanisms underlying the development of the cardiovascular system, but we are just beginning to understand how changes in
heart and vessel structure are influenced by hemodynamic forces such as shear stress. Recent work has shown that vessel
remodeling in the mouse yolk sac is secondarily effected when cardiac function is reduced or absent. These findings indicate that
proper circulation is required for vessel remodeling, but have not defined whether the role of circulation is to provide mechanical
cues, to deliver oxygen or to circulate signaling molecules. Here, we used time-lapse confocal microscopy to determine the role of
fluid-derived forces in vessel remodeling in the developing murine yolk sac. Novel methods were used to characterize flows in
normal embryos and in embryos with impaired contractility (Mlc2a^(–/–)). We found abnormal plasma and erythroblast circulation in
these embryos, which led us to hypothesize that the entry of erythroblasts into circulation is a key event in triggering vessel
remodeling. We tested this by sequestering erythroblasts in the blood islands, thereby lowering the hematocrit and reducing shear
stress, and found that vessel remodeling and the expression of eNOS (Nos3) depends on erythroblast flow. Further, we rescued
remodeling defects and eNOS expression in low-hematocrit embryos by restoring the viscosity of the blood. These data show that
hemodynamic force is necessary and sufficient to induce vessel remodeling in the mammalian yolk sa
ESR Study of (C_5H_{12}N)_2CuBr_4
ESR studies at 9.27, 95.4, and 289.7 GHz have been performed on
(CHN)CuBr down to 3.7 K. The 9.27 GHz data were acquired
with a single crystal and do not indicate the presence of any structural
transitions. The high frequency data were collected with a polycrystalline
sample and resolved two absorbances, consistent with two crystallographic
orientations of the magnetic sites and with earlier ESR studies performed at
300 K. Below T, our data confirm the presence of a spin singlet
ground state.Comment: 2 pages, 4 figs., submitted 23rd International Conference on Low
Temperature Physics (LT-23), Aug. 200
A proof of uniqueness of the Gurarii space
We present a short and elementary proof of isometric uniqueness of the
Gurarii space.Comment: 6 pages, some improvements incorporate
DNA Vaccines Encoding Antigen Targeted to MHC Class II Induce Influenza-Specific CD8+ T Cell Responses, Enabling Faster Resolution of Influenza Disease
Current influenza vaccines are effective but imperfect, failing to cover against emerging strains of virus and requiring seasonal administration to protect against new strains. A key step to improving influenza vaccines is to improve our understanding of vaccine induced protection. Whilst it is clear that antibodies play a protective role, vaccine induced CD8+ T cells can improve protection. To further explore the role of CD8+ T cells we used a DNA vaccine that encodes antigen dimerised to an immune cell targeting module. Immunising CB6F1 mice with the DNA vaccine in a heterologous prime boost regime with the seasonal protein vaccine improved the resolution of influenza disease compared to protein alone. This improved disease resolution was dependent on CD8+ T cells. However, DNA vaccine regimes that induced CD8+ T cells alone were not protective and did not boost the protection provided by protein. The MHC targeting module used was an anti-I-Ed single chain antibody specific to the BALB/c strain of mice. To test the role of MHC targeting we compared the response between BALB/c, C57BL/6 mice and an F1 cross of the two strains (CB6F1). BALB/c mice were protected, C57BL/6 were not and the F1 had an intermediate phenotype; showing that the targeting of antigen is important in the response. Based on these findings, and in agreement with other studies using different vaccines, we conclude that in addition to antibody, inducing a protective CD8 response is important in future influenza vaccines
Decay of weak solutions to the 2D dissipative quasi-geostrophic equation
We address the decay of the norm of weak solutions to the 2D dissipative
quasi-geostrophic equation. When the initial data is in only, we prove
that the norm tends to zero but with no uniform rate, that is, there are
solutions with arbitrarily slow decay. For the initial data in ,
with , we are able to obtain a uniform decay rate in . We
also prove that when the norm of the initial data
is small enough, the norms, for have uniform
decay rates. This result allows us to prove decay for the norms, for , when the initial data is in .Comment: A paragraph describing work by Carrillo and Ferreira proving results
directly related to the ones in this paper is added in the Introduction. Rest
of the article remains unchange
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