1,335 research outputs found
Nonlinear delamination buckling and expansion of functionally graded laminated piezoelectric composite shells
AbstractIn this paper, an analytical method is presented to investigate the nonlinear buckling and expansion behaviors of local delaminations near the surface of functionally graded laminated piezoelectric composite shells subjected to the thermal, electrical and mechanical loads, where the mid-plane nonlinear geometrical relation of delaminations is considered. In examples, the effects of thermal loading, electric field strength, the stacking patterns of functionally graded laminated piezoelectric composite shells and the patterns of delaminations on the critical axial loading of locally delaminated buckling are described and discussed. Finally, the possible growth directions of local buckling for delaminated sub-shells are described by calculating the expanding forces along the length and short axis of the delaminated sub-shells
Kinetic Parameters Evaluation for Isoprene Mixed with Aluminum Oxide
AbstractWe analyzed the basic hazard characteristics for isoprene in the manufacturing process by evaluating the runaway reaction, kinetic parameters and safety parameters in this study. Experiments were carried out by calculating the thermal decomposition reactions for isoprene and mixed with aluminum oxide in non-isothermal conditions by differential scanning calorimetry (DSC). Afterwards results indicated that isoprene had a conjugated double bond of unstable structure, and therefore it was prone to produce exothermic reaction during the process of polymerization. Aluminum oxide was applied to mix with isoprene, which could increase the heat release rate. Based on the results, safety information should be provided to government and relevant industries for prevention the accident occur in relevant plants
A Lanczos algorithm for linear response
An iterative algorithm is presented for solving the RPA equations of linear
response. The method optimally computes the energy-weighted moments of the
strength function, allowing one to match the computational effort to the
intrinsic accuracy of the basic mean-field approximation, avoiding the problem
of solving very large matrices. For local interactions, the computational
effort for the method scales with the number of particles N_p as O(N_p^3).Comment: 12 pages including 3 figures; Late
Infrared spectroscopy of NaCl(CH3OH)n complexes in helium nanodroplets
Infrared (IR) spectra of complexes between NaCl and methanol have been recorded for the first time. These complexes were formed in liquid helium nanodroplets by consecutive pick-up of NaCl and CH3OH molecules. For the smallest NaCl(CH3OH)n complexes where n = 1-3, the IR data suggest that the lowest energy isomer is the primary product in each case. The predominant contribution to the binding comes from ionic hydrogen bonds between the OH in each methanol molecule and the chloride ion in the NaCl, as established by the large red-shift of the OH stretching bands compared with the isolated CH3OH molecule. For n ≥ 4 there is a dramatic shift from discrete vibrational bands to very broad absorption envelopes, suggesting a profound change in the structural landscape and, in particular, access to multiple low-energy isomers
Pregnancy Reprograms the Epigenome of Mammary Epithelial Cells and Blocks the Development of Premalignant Lesions
Pregnancy causes a series of cellular and molecular changes in mammary epithelial cells (MECs) of female adults. In addition, pregnancy can also modify the predisposition of rodent and human MECs to initiate oncogenesis. Here, we investigate how pregnancy reprograms enhancer chromatin in the mammary epithelium of mice and influences the transcriptional output of the oncogenic transcription factor cMYC. We find that pregnancy induces an expansion of the active cis-regulatory landscape of MECs, which influences the activation of pregnancy-related programs during re-exposure to pregnancy hormones in vivo and in vitro. Using inducible cMYC overexpression, we demonstrate that post-pregnancy MECs are resistant to the downstream molecular programs induced by cMYC, a response that blunts carcinoma initiation, but does not perturb the normal pregnancy-induced epigenomic landscape. cMYC overexpression drives post-pregnancy MECs into a senescence-like state, and perturbations of this state increase malignant phenotypic changes. Taken together, our findings provide further insight into the cell-autonomous signals in post-pregnancy MECs that underpin the regulation of gene expression, cellular activation, and resistance to malignant development
Safety and Toxicity of Catheter Gene Delivery to the Pulmonary Vasculature in a Patient with Metastatic Melanoma
Overview summary Transcatheter delivery of HLA-B7 DNA and cationic liposomes into a segment of a pulmonary artery was safely performed in 1 patient with tumor nodules in the lung. No immunologic or organ toxicities were observed. Percutaneous catheter gene delivery has been performed in humans. Further refinements of this approach may lead to useful treatments for a variety of human diseases.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/63196/1/hum.1994.5.9-1089.pd
Higgs Bundles, Gauge Theories and Quantum Groups
The appearance of the Bethe Ansatz equation for the Nonlinear Schr\"{o}dinger
equation in the equivariant integration over the moduli space of Higgs bundles
is revisited. We argue that the wave functions of the corresponding
two-dimensional topological U(N) gauge theory reproduce quantum wave functions
of the Nonlinear Schr\"{o}dinger equation in the -particle sector. This
implies the full equivalence between the above gauge theory and the
-particle sub-sector of the quantum theory of Nonlinear Schr\"{o}dinger
equation. This also implies the explicit correspondence between the gauge
theory and the representation theory of degenerate double affine Hecke algebra.
We propose similar construction based on the gauged WZW model leading to
the representation theory of the double affine Hecke algebra. The relation with
the Nahm transform and the geometric Langlands correspondence is briefly
discussed.Comment: 48 pages, typos corrected, one reference adde
Quantum field theory of metallic spin glasses
We introduce an effective field theory for the vicinity of a zero temperature
quantum transition between a metallic spin glass (``spin density glass'') and a
metallic quantum paramagnet. Following a mean field analysis, we perform a
perturbative renormalization-group study and find that the critical properties
are dominated by static disorder-induced fluctuations, and that dynamic
quantum-mechanical effects are dangerously irrelevant. A Gaussian fixed point
is stable for a finite range of couplings for spatial dimensionality ,
but disorder effects always lead to runaway flows to strong coupling for . Scaling hypotheses for a {\em static\/} strong-coupling critical field
theory are proposed. The non-linear susceptibility has an anomalously weak
singularity at such a critical point. Although motivated by a perturbative
study of metallic spin glasses, the scaling hypotheses are more general, and
could apply to other quantum spin glass to paramagnet transitions.Comment: 16 pages, REVTEX 3.0, 2 postscript figures; version contains
reference to related work in cond-mat/950412
On Vanishing Theorems For Vector Bundle Valued p-Forms And Their Applications
Let be a strictly increasing function
with . We unify the concepts of -harmonic maps, minimal
hypersurfaces, maximal spacelike hypersurfaces, and Yang-Mills Fields, and
introduce -Yang-Mills fields, -degree, -lower degree, and generalized
Yang-Mills-Born-Infeld fields (with the plus sign or with the minus sign) on
manifolds. When and
the -Yang-Mills field becomes an ordinary Yang-Mills field,
-Yang-Mills field, a generalized Yang-Mills-Born-Infeld field with the plus
sign, and a generalized Yang-Mills-Born-Infeld field with the minus sign on a
manifold respectively. We also introduce the energy functional (resp.
-Yang-Mills functional) and derive the first variational formula of the
energy functional (resp. -Yang-Mills functional) with
applications. In a more general frame, we use a unified method to study the
stress-energy tensors that arise from calculating the rate of change of various
functionals when the metric of the domain or base manifold is changed. These
stress-energy tensors, linked to -conservation laws yield monotonicity
formulae. A "macroscopic" version of these monotonicity inequalities enables us
to derive some Liouville type results and vanishing theorems for forms with
values in vector bundles, and to investigate constant Dirichlet boundary value
problems for 1-forms. In particular, we obtain Liouville theorems for
harmonic maps (e.g. -harmonic maps), and Yang-Mills fields (e.g.
generalized Yang-Mills-Born-Infeld fields on manifolds). We also obtain
generalized Chern type results for constant mean curvature type equations for
forms on and on manifolds with the global doubling property
by a different approach. The case and is due to Chern.Comment: 1. This is a revised version with several new sections and an
appendix that will appear in Communications in Mathematical Physics. 2. A
"microscopic" approach to some of these monotonicity formulae leads to
celebrated blow-up techniques and regularity theory in geometric measure
theory. 3. Our unique solution of the Dirichlet problems generalizes the work
of Karcher and Wood on harmonic map
Polycyclic aromatic hydrocarbons in the dwarf galaxy IC 10
Infrared observations from the Spitzer Space Telescope archive are used to
study the dust component of the interstellar medium in the IC~10 irregular
galaxy. Dust distribution in the galaxy is compared to the distributions of
H and [SII] emission, neutral hydrogen and CO clouds, and ionizing
radiation sources. The distribution of polycyclic aromatic hydrocarbons (PAH)
in the galaxy is shown to be highly non-uniform with the mass fraction of these
particles in the total dust mass reaching 4%. PAHs tend to avoid bright HII
regions and correlate well with atomic and molecular gas. This pattern suggests
that PAHs form in the dense interstellar gas. We propose that the significant
decrease of the PAH abundance at low metallicity is observed not only globally
(at the level of entire galaxies), but also locally (at least, at the level of
individual HII regions). We compare the distribution of the PAH mass fraction
to the distribution of high-velocity features, that we have detected earlier in
wings of H and SII lines, over the entire available galaxy area. No
conclusive evidence for shock destruction of PAHs in the IC~10 galaxy could be
found.Comment: Accepted for publication in Astronomy Report
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