671 research outputs found
The analysis of structurally orthotropic shells by means of the compliance method Progress report, period ending 1 Jun. 1968
Linear shell theory elastic constant instability conditions for symmetrically loaded shells of revolutio
Comment on "Symmetries and Interaction Coefficients of Kelvin waves" [arXiv:1005.4575] by Lebedev and L'vov
We comment on the claim by Lebedev and L'vov [arXiv:1005.4575] that the
symmetry with respect to a tilt of a quantized vortex line does not yet
prohibit coupling between Kelvin waves and the large-scale slope of the line.
Ironically, the counterexample of an effective scattering vertex in the local
induction approximation (LIA) attempted by Lebedev and L'vov invalidates their
logic all by itself being a notoriously known example of how symmetries impose
stringent constraints on kelvon kinetics---not only the coupling in question
but the kinetics in general are absent within LIA. We further explain that the
mistake arises from confusing symmetry properties of a specific mathematical
representation in terms of the canonical vortex position field w(z) = x(z) +
iy(z), which explicitly breaks the tilt symmetry due to an arbitrary choice of
the z-axis, with those of the real physical system recovered in final
expressions.Comment: comment on arXiv:1005.4575, version accepted in JLTP with minimal
changes: abstract adde
The analysis of structurally orthotropic shells by means of the compliance method
Structurally orthotropic shells analyzed by compliance metho
On role of symmetries in Kelvin wave turbulence
E.V. Kozik and B.V. Svistunov (KS) paper "Symmetries and Interaction
Coefficients of Kelvin waves", arXiv:1006.1789v1, [cond-mat.other] 9 Jun 2010,
contains a comment on paper "Symmetries and Interaction coefficients of Kelvin
waves", V. V. Lebedev and V. S. L'vov, arXiv:1005.4575, 25 May 2010. It relies
mainly on the KS text "Geometric Symmetries in Superfluid Vortex Dynamics}",
arXiv:1006.0506v1 [cond-mat.other] 2 Jun 2010. The main claim of KS is that a
symmetry argument prevents linear in wavenumber infrared asymptotics of the
interaction vertex and thereby implies locality of the Kelvin wave spectrum
previously obtained by these authors. In the present note we reply to their
arguments. We conclude that there is neither proof of locality nor any
refutation of the possibility of linear asymptotic behavior of interaction
vertices in the texts of KS
Scale Separation Scheme for Simulating Superfluid Turbulence: Kelvin-Wave Cascade
A Kolmogorov-type cascade of Kelvin waves--the distortion waves on vortex
lines--plays a key part in the relaxation of superfluid turbulence at low
temperatures. We propose an efficient numeric scheme for simulating the Kelvin
wave cascade on a single vortex line. The idea is likely to be generalizable
for a full-scale simulation of different regimes of superfluid turbulence. With
the new scheme, we are able to unambiguously resolve the cascade spectrum
exponent, and thus to settle the controversy between recent simulations [1] and
recently developed analytic theory [2].
[1] W.F. Vinen, M. Tsubota and A. Mitani, Phys. Rev. Lett. 91, 135301 (2003).
[2] E.V. Kozik and B.V. Svistunov, Phys. Rev. Lett. 92, 035301 (2004).Comment: 4 pages, RevTe
Geometric Symmetries in Superfluid Vortex Dynamics
Dynamics of quantized vortex lines in a superfluid feature symmetries
associated with the geometric character of the complex-valued field,
, describing the instant shape of the line. Along with a
natural set of Noether's constants of motion, which---apart from their rather
specific expressions in terms of ---are nothing but components of the
total linear and angular momenta of the fluid, the geometric symmetry brings
about crucial consequences for kinetics of distortion waves on the vortex
lines---the Kelvin waves. It is the geometric symmetry that renders Kelvin-wave
cascade local in the wavenumber space. Similar considerations apply to other
systems with purely geometric degrees of freedom.Comment: 4 REVTeX pages, minor stylistic changes, references to recent related
preprints adde
The Impact of Host Variables and Tumor Necrosis Factor on the Gut Microbiome in a Mouse Model of Crohn\u27s Disease
Crohn’s Disease (CD) and Ulcerative Colitis (UC) are chronic, inflammatory conditions of the digestive tract that are collectively known as Inflammatory Bowel Disease (IBD). Currently, IBD has no cure and the exact mechanisms of disease development and progression are unknown. The gut microbiome is the collection of microbes that reside in the digestive tracts of humans and animals, and it has been shown to be associated with a variety of diseases, including IBD. Mouse models of colitis are often used to investigate the role of the gut microbiome in IBD. In this work, I investigated the role of tumor necrosis factor (TNF) on the gut microbiome in a mouse model of CD. Tumor necrosis factor is an inflammatory cytokine that plays a critical role in the inflammatory response. A common IBD treatment strategy is the use of TNF inhibitors. However, a subset of patients only responds to anti-TNF treatment for a limited time, while others do not respond at all. It is not fully understood how TNF, or TNF blockade, impacts the microbiome. Therefore, my overall objective was to determine how TNF and host variables impact the mouse gut microbiome during colitis. My hypotheses were that 1) Age, sex, and TNF affect the fecal microbiome of mice, and impact the severity of acute 2,4,6 trinitrobenzenesulfonic acid (TNBS) colitis. 2) TNF, sex and disease severity impact the microbiome in chronic TNBS colitis and the composition of the fecal microbiome will closely correlate with colitis severity. 3) Different mouse strains have a distinct fecal microbiome. To test my hypotheses, I induced acute and chronic TNBS colitis in WT mice and Tnf-/-mice. 16S rRNA gene sequencing, microbiome analysis, and multivariate analyses were used to determine the relationship of host factors to the gut microbiome. I found that TNF, age, and sex impact the gut microbiome in mice before and after colitis. Additionally, I identified specific microbes that are differentially abundant depending on TNF expression, GI site, as well as the mouse age, sex, strain, and vendor. This work highlights the importance of considering host factors in microbiome studies and provides important data to the literature concerning the role of the gut microbiome in IBD pathogenesis
Symmetries and Interaction coefficients of Kelvin waves
We considered symmetry restriction on the interaction coefficients of Kelvin
waves and demonstrated that linear in small wave vector asymptotic is not
forbidden, as one can expect by naive reasoning.Comment: 4 pages, submitted to J. of Low Temp. Phy
Foundations of linear inelastic shell theory progress report
Foundations of linear inelastic thin shell theor
Scanning Superfluid-Turbulence Cascade by Its Low-Temperature Cutoff
On the basis of recently proposed scenario of the transformation of the
Kolmogorov cascade into the Kelvin-wave cascade, we develop a theory of
low-temperature cutoff. The theory predicts a specific behavior of the
quantized vortex line density, , controlled by the frictional coefficient,
, responsible for the cutoff. The curve is
found to directly reflect the structure of the cascade, revealing four
qualitatively distinct wavenumber regions. Excellent agreement with recent
experiment by Walmsley {\it et al.} [arXiv:0710.1033]--in which has been
measured down to K--implies that the scenario of low-temperature
superfluid turbulence is now experimentally validated, and allows to quantify
the Kelvin-wave cascade spectrum.Comment: 4 pages, 2 figures, v2: extended introduction, the controversy with
the scenario by L'vov et al. [13] is discussed in conclusio
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