292,454 research outputs found
Hare-lip surgery in the history of traditional Chinese medicine
There have been a few articles published in Chinese and English on hare-lip
surgery in the history of traditional Chinese medicine. They are brief and some of
them are inaccurate, although two recent English articles on this subject have
presented an adequate picture on some aspects.' This article offers unreported
information and evidence of both congenital and traumatic hare-lip surgery in the
history of traditional Chinese medicine and also clarifies and corrects some of the
facts and mistakes that have appeared in works previously published either in Chinese
or English
Influence of Overdrying on Dimensional Stability and Certain Strength Properties of Paper
In the past, the consequences of overdrying have been examined with the drying theory. This study was designed to look at the effects of overdrying on handsheets. Comparison of the dimensional change and strength properties was made between two sets of handsheets, one conditioned in the humidity room and the other overdried at 90°C for four hours. The handsheets used in this experiment were made from five types of furnishes: Hardwood Kraft, Softwood Kraft, Hardwood Kraft and Softwood Kraft combination, and two different percentages of TiO2 added to Softwood Kraft. The dimensional stability was measured by the Neenah Expansimeter. The Tappi Standard Testing Procedures were used to test the physical properties to the handsheets. The results of this study showed that overdrying improved the dimensional stability and tensile strength, yet reduced a certain amount of mullen, tear and fold in handsheets
Comment on ``Signal of Quark Deconfinement in the Timing Structure of Pulsar Spin-Down''
This is a comment on a paper by Glendenning, Pei, and Weber (Phys. Rev.
Lett., 79, 1603, 1997), where the authors gave an incorrect estimate of the
event rate and neglected the important gravitational energy release. Previous
work on the same subject is reviewed, and a new suggestion is made to link
quark-hadron phase transitions with soft gamma-ray repeaters.Comment: 4 pages; to appear in Phys. Rev. Let
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Partial CFD models of cardiovascular stents
Copyright @ 2002 Wiley BlackwellThis paper outlines the use of a partial CFD stent model in order to improve discretisation of important small features. The effects of mesh size on the performance measure are investigated. The results are compared with those from full models and also comparisons with clinical trials are made. It is shown that partial models provide a better approximation to reality than full models when using modest PC workstation resources. The general conclusion is that computer-based design of medical devices must take into account the variations in geometry between patients by means of, for example, a flat performance curve against noise
Triplicity of Quarks and Leptons
Quarks come in three colors and have electric charges in multiples of
one-third. There are also three families of quarks and leptons. Whereas the
first two properties can be understood in terms of unification symmetries such
as SU(5), SO(10), or E_6, why there should only be three families remains a
mystery. I propose how all three properties involving the number three are
connected in a fivefold application of the gauge symmetry SU(3).Comment: 10 pages, including 2 figure
A Bi-Hamiltonian Formulation for Triangular Systems by Perturbations
A bi-Hamiltonian formulation is proposed for triangular systems resulted by
perturbations around solutions, from which infinitely many symmetries and
conserved functionals of triangular systems can be explicitly constructed,
provided that one operator of the Hamiltonian pair is invertible. Through our
formulation, four examples of triangular systems are exhibited, which also show
that bi-Hamiltonian systems in both lower dimensions and higher dimensions are
many and varied. Two of four examples give local 2+1 dimensional bi-Hamiltonian
systems and illustrate that multi-scale perturbations can lead to
higher-dimensional bi-Hamiltonian systems.Comment: 16 pages, to appear in J. Math. Phy
Form Invariance of the Neutrino Mass Matrix
Consider the most general Majorana neutrino mass matrix . Motivated by present neutrino-oscillation data, much theoretical effort is
directed at reducing it to a specific texture in terms of a small number of
parameters. This procedure is often {\it ad hoc}. I propose instead that for
any one may choose, it should satisfy the condition , where is a specific unitary matrix such that
represents a well-defined discrete symmetry in the basis,
being a particular integer not necessarily equal to one. I illustrate this
idea with a number of examples, including the realistic case of an inverted
hierarchy of neutrino masses.Comment: Version to appear in PR
The Steady-State Response of a Class of Dynamical Systems to Stochastic Excitation
In this paper a class of coupled nonlinear dynamical systems subjected to stochastic excitation is considered. It is shown how the exact steady-state probability density function for this class of systems can be constructed. The result is then applied to some classical oscillator problems
Deformations of Closed Strings and Topological Open Membranes
We study deformations of topological closed strings. A well-known example is
the perturbation of a topological closed string by itself, where the
associative OPE product is deformed, and which is governed by the WDVV
equations. Our main interest will be closed strings that arise as the boundary
theory for topological open membranes, where the boundary string is deformed by
the bulk membrane operators. The main example is the topological open membrane
theory with a nonzero 3-form field in the bulk. In this case the Lie bracket of
the current algebra is deformed, leading in general to a correction of the
Jacobi identity. We identify these deformations in terms of deformation theory.
To this end we describe the deformation of the algebraic structure of the
closed string, given by the BRST operator, the associative product and the Lie
bracket. Quite remarkably, we find that there are three classes of deformations
for the closed string, two of which are exemplified by the WDVV theory and the
topological open membrane. The third class remains largely mysterious, as we
have no explicit example.Comment: 50 pages, LaTeX; V2: minor changes, 2 references added, V3: typos
corrected, signs added, modified discussion on higher correlator
Calcified amorphous tumor: A rare cause of central retinal artery occlusion.
PurposeWe report the case of a central retinal artery occlusion secondary to presumed embolus from a calcified amorphous tumor of the heart, a very rare non-neoplastic cardiac mass.ObservationsA 60-year-old female presented with acute unilateral vision loss of the left eye. Examination revealed hand motion visual acuity of the left eye and a left relative afferent pupillary defect. Fundoscopy showed whitening of the macula with a cherry red spot, consistent with a central retinal artery occlusion. Initial workup was unremarkable, including hypercoagulability labs, magnetic resonance imaging of the brain, and magnetic resonance angiography of the head and neck. Transthoracic echocardiogram (TTE) showed calcification of the mitral valve but no masses. Subsequently, transesophageal echocardiogram (TEE) was performed, which revealed a mobile calcified amorphous tumor of the heart.ConclusionsCalcified amorphous tumor of the heart is a very rare cardiac mass that may cause retinal artery occlusion. TEE is a more sensitive imaging modality to assess for potential cardio-embolic sources if TTE is unrevealing
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