52 research outputs found
Dynamics of vortex tangle without mutual friction in superfluid He
A recent experiment has shown that a tangle of quantized vortices in
superfluid He decayed even at mK temperatures where the normal fluid was
negligible and no mutual friction worked. Motivated by this experiment, this
work studies numerically the dynamics of the vortex tangle without the mutual
friction, thus showing that a self-similar cascade process, whereby large
vortex loops break up to smaller ones, proceeds in the vortex tangle and is
closely related with its free decay. This cascade process which may be covered
with the mutual friction at higher temperatures is just the one at zero
temperature Feynman proposed long ago. The full Biot-Savart calculation is made
for dilute vortices, while the localized induction approximation is used for a
dense tangle. The former finds the elementary scenario: the reconnection of the
vortices excites vortex waves along them and makes them kinked, which could be
suppressed if the mutual friction worked. The kinked parts reconnect with the
vortex they belong to, dividing into small loops. The latter simulation under
the localized induction approximation shows that such cascade process actually
proceeds self-similarly in a dense tangle and continues to make small vortices.
Considering that the vortices of the interatomic size no longer keep the
picture of vortex, the cascade process leads to the decay of the vortex line
density. The presence of the cascade process is supported also by investigating
the classification of the reconnection type and the size distribution of
vortices. The decay of the vortex line density is consistent with the solution
of the Vinen's equation which was originally derived on the basis of the idea
of homogeneous turbulence with the cascade process. The obtained result is
compared with the recent Vinen's theory.Comment: 16 pages, 16 figures, submitted to PR
Endoplasmic reticulum targeted GFP reveals ER organization in tobacco NT-1 cells during cell division
Author Posting. © The Authors, 2005. This is the author's version of the work. It is posted here by permission of Elsevier B.V. for personal use, not for redistribution. The definitive version was published in Plant Physiology and Biochemistry, doi:10.1016/j.plaphy.2006.03.003.The endoplasmic reticulum (ER) of plant cells undergoes a drastic reorganization
during cell division. In tobacco NT-1 cells that stably express a GFP construct targeted
to the ER, we have mapped the reorganization of ER that occurs during mitosis and
cytokinesis with confocal laser scanning microscopy. During division, the ER and
nuclear envelope do not vesiculate. Instead, tubules of ER accumulate around the
chromosomes after the nuclear envelope breaks down, with these tubules aligning parallel
to the microtubules of the mitotic spindle. In cytokinesis, the phragmoplast is
particularly rich in ER, and the transnuclear channels and invaginations present in many
interphase cells appear to develop from ER tubules trapped in the developing
phragmoplast. Drug studies, using oryzalin and latrunculin to disrupt the microtubules
and actin microfilaments respectively, demonstrate that during division, the arrangement
of ER is controlled by microtubules and not by actin, which is the reverse of the situation
in interphase cells.Funding for this project included NASA grant # NAGW-4984 to the North
Carolina NSCORT (NASA Specialized Center of Research and Training) (SLG, DAC,
NSA), NSF REU Site Grant #0243930 (NSA), a Sigma Xi Grant-in-Aid Award (SLG),
and Australian Research Council Discovery Grant no. DP0208806 (DAC)
Partitioning the Heritability of Tourette Syndrome and Obsessive Compulsive Disorder Reveals Differences in Genetic Architecture
The direct estimation of heritability from genome-wide common variant data as implemented in the program Genome-wide Complex Trait Analysis (GCTA) has provided a means to quantify heritability attributable to all interrogated variants. We have quantified the variance in liability to disease explained
Rate dependent finite deformation stress-strain behavior of an ethylene methacrylic acid copolymer and an ethylene methacrylic acid butyl acrylate copolymer
Castable Thermoplastic Urethane Elastomers I. Formulation and Applications as Removable Encapsulants
Accessory conidium production in three species of Harposporium and an evaluation of nematophagous members of the genus
A new species of Harposporium with two spore types isolated from the larva of a cerambycid beetle
The Reading Fluency and Comprehension of Fifth- and Sixth-Grade Struggling Readers Across Brief Tests of Various Intervention Approaches
Development Psychopathology in context: clinical setting
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