1,667 research outputs found
A new species of <i>Testudinella</i> (Rotifera: Testudinellidae) From Qi’ao Island, Pearl River estuary, China
A new species of rotifer, Testudinella zhujiangensis sp. n. (Rotifera, Monogononta, Testudinellidae), is described from the littoral of an artificial brackish water lake and a mangrove swamp on Qi’ao Island of the Zhujiang/Pearl River estuary, Guangdong Province, south of China. It is closely related to Testudinella obscura ALTHAUS, 1957, but distinguished by its anterior truncated vase-shaped lorica, cross-sectional view, shallow inverted U-shaped foot opening, and small differences in the morphology of the trophi
Classification of Higher Dimensional Spacetimes
We algebraically classify some higher dimensional spacetimes, including a
number of vacuum solutions of the Einstein field equations which can represent
higher dimensional black holes. We discuss some consequences of this work.Comment: 16 pages, 1 Tabl
WZW-like Action for Heterotic String Field Theory
We complete the construction of the Neveu-Schwarz sector of heterotic string
field theory begun in hep-th/0406212 by giving a closed-form expression for the
action and gauge transformations. Just as the Wess-Zumino-Witten (WZW) action
for open superstring field theory can be constructed from pure-gauge fields in
bosonic open string field theory, our heterotic string field theory action is
constructed from pure-gauge fields in bosonic closed string field theory. The
construction involves a simple alternative form of the WZW action which is
consistent with the algebraic structures of closed string field theory.Comment: 22 pages, no figures, LaTeX2
Design and fabrication of a low cost implantable bladder pressure monitor
In the frame of the Flemish Community funded project Bioflex we developed and fabricated an implant for short term (< 7 days) bladder pressure monitoring, and diagnosis of incontinence. This implant is soft and flexible to prevent damaging the bladder's inner wall. It contains a standard flexible electronic circuit connected to a battery, which are embedded in surface treated silicone to enhance the biocompatibility and prevent salt deposition. This article describes the fabrication of the pill and the results of preliminary cytotoxicity tests. The electronic design and its tests, implantation and the result of the in-vivo experimentation will be presented in other articles
A perturbative analysis of tachyon condensation
Tachyon condensation in the open bosonic string is analyzed using a
perturbative expansion of the tachyon potential around the unstable D25-brane
vacuum. Using the leading terms in the tachyon potential, Pad\'e approximants
can apparently give the energy of the stable vacuum to arbitrarily good
accuracy. Level-truncation approximations up to level 10 for the coefficients
in the tachyon potential are extrapolated to higher levels and used to find
approximants for the full potential. At level 14 and above, the resulting
approximants give an energy less than -1 in units of the D25-brane tension, in
agreement with recent level-truncation results by Gaiotto and Rastelli. The
extrapolated energy continues to decrease below -1 until reaching a minimum
near level 26, after which the energy turns around and begins to approach -1
from below. Within the accuracy of this method, these results are completely
consistent with an energy which approaches -1 as the level of truncation is
taken to be arbitrarily large.Comment: 8 pages, 3 eps figures, Latex; v2: typo correcte
Tachyon cosmology with non-vanishing minimum potential: a unified model
We investigate the tachyon condensation process in the effective theory with
non-vanishing minimum potential and its implications to cosmology. It is shown
that the tachyon condensation on an unstable three-brane described by this
modified tachyon field theory leads to lower-dimensional branes (defects)
forming within a stable three-brane. Thus, in the cosmological background, we
can get well-behaved tachyon matter after tachyon inflation, (partially)
avoiding difficulties encountered in the original tachyon cosmological models.
This feature also implies that the tachyon inflated and reheated universe is
followed by a Chaplygin gas dark matter and dark energy universe. Hence, such
an unstable three-brane behaves quite like our universe, reproducing the key
features of the whole evolutionary history of the universe and providing a
unified description of inflaton, dark matter and dark energy in a very simple
single-scalar field model.Comment: 18 p
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