1,670 research outputs found
Rigidity of four-dimensional K\"ahler-Ricci solitons
In this article, we investigate four-dimensional gradient shrinking Ricci
solitons close to a K\"ahler model. The first theorem could be considered as a
rigidity result for the K\"ahler-Ricci soliton structure on (in the sense of Remark 1). Moreover, we show that if the
quotient of norm of the self-dual Weyl tensor and scalar curvature is close to
that on a K\"ahler metric in a specific sense, then the gradient Ricci soliton
must be either half-conformally flat or locally K\"ahler
Probabilistic control of HIV latency and transactivation by the Tat gene circuit
Copyright © 2020 National Academy of Sciences.The reservoir of HIV latently infected cells is the major obstacle for eradication of HIV infection. The âshock-and-killâ strategy proposed earlier aims to reduce the reservoir by activating cells out of latency. While the intracellular HIV Tat gene circuit is known to play important roles in controlling latency and its transactivation in HIV-infected cells, the detailed control mechanisms are not well understood. Here we study the mechanism of probabilistic control of the latent and the transactivated cell phenotypes of HIV-infected cells. We reconstructed the probability landscape, which is the probability distribution of the Tat gene circuit states, by directly computing the exact solution of the underlying chemical master equation. Results show that the Tat circuit exhibits a clear bimodal probability landscape (i.e., there are two distinct probability peaks, one associated with the latent cell phenotype and the other with the transactivated cell phenotype). We explore potential modifications to reactions in the Tat gene circuit for more effective transactivation of latent cells (i.e., the shock-and-kill strategy). Our results suggest that enhancing Tat acetylation can dramatically increase Tat and viral production, while increasing the Tatâtransactivation response binding affinity can transactivate latent cells more rapidly than other manipulations. Our results further explored the âblock and lockâ strategy toward a functional cure for HIV. Overall, our study demonstrates a general approach toward discovery of effective therapeutic strategies and druggable targets by examining control mechanisms of cell phenotype switching via exactly computed probability landscapes of reaction networks.info:eu-repo/semantics/publishedVersio
Bethe ansatz for the XXX-S chain with non-diagonal open boundaries
We consider the algebraic Bethe ansatz solution of the integrable and
isotropic XXX-S Heisenberg chain with non-diagonal open boundaries. We show
that the corresponding K-matrices are similar to diagonal matrices with the
help of suitable transformations independent of the spectral parameter. When
the boundary parameters satisfy certain constraints we are able to formulate
the diagonalization of the associated double-row transfer matrix by means of
the quantum inverse scattering method. This allows us to derive explicit
expressions for the eigenvalues and the corresponding Bethe ansatz equations.
We also present evidences that the eigenvectors can be build up in terms of
multiparticle states for arbitrary S.Comment: 62 page
Solution of the SU(N) Vertex Model with Non-Diagonal Open Boundaries
We diagonalize the double-row transfer matrix of the SU(N) vertex model for
certain classes of non-diagonal boundary conditions. We derive explicit
expressions for the corresponding eigenvectors and eigenvalues by means of the
algebraic Bethe ansatz approach.Comment: 10 page
Integrable spin-boson models descending from rational six-vertex models
We construct commuting transfer matrices for models describing the
interaction between a single quantum spin and a single bosonic mode using the
quantum inverse scattering framework. The transfer matrices are obtained from
certain inhomogeneous rational vertex models combining bosonic and spin
representations of SU(2), subject to non-diagonal toroidal and open boundary
conditions. Only open boundary conditions are found to lead to integrable
Hamiltonians combining both rotating and counter-rotating terms in the
interaction. If the boundary matrices can be brought to triangular form
simultaneously, the spectrum of the model can be obtained by means of the
algebraic Bethe ansatz after a suitable gauge transformation; the corresponding
Hamiltonians are found to be non-hermitian. Alternatively, a certain
quasi-classical limit of the transfer matrix is considered where hermitian
Hamiltonians are obtained as members of a family of commuting operators; their
diagonalization, however, remains an unsolved problem.Comment: 16 pages, 2 eps figure
Growth of carbon nanotubes on quasicrystalline alloys
We report on the synthesis of carbon nanotubes on quasicrystalline alloys.
Aligned multiwalled carbon nanotubes (MWNTs) on the conducting faces of
decagonal quasicrystals were synthesized using floating catalyst chemical vapor
deposition. The alignment of the nanotubes was found perpendicular to the
decagonal faces of the quasicrystals. A comparison between the growth and tube
quality has also been made between tubes grown on various quasicrystalline and
SiO2 substrates. While a significant MWNT growth was observed on decagonal
quasicrystalline substrate, there was no significant growth observed on
icosahedral quasicrystalline substrate. Raman spectroscopy and high resolution
transmission electron microscopy (HRTEM) results show high crystalline nature
of the nanotubes. Presence of continuous iron filled core in the nanotubes
grown on these substrates was also observed, which is typically not seen in
MWNTs grown using similar process on silicon and/or silicon dioxide substrates.
The study has important implications for understanding the growth mechanism of
MWNTs on conducting substrates which have potential applications as heat sinks
Mixed-instance querying: a lightweight integration architecture for data journalism
International audienceAs the world's affairs get increasingly more digital, timely production and consumption of news require to efficiently and quickly exploit heterogeneous data sources. Discussions with journalists revealed that content management tools currently at their disposal fall very short of expectations. We demonstrate TATOOINE, a lightweight data integration prototype, which allows to quickly set up integration queries across (very) heterogeneous data sources, capitalizing on the many data links (joins) available in this application domain. Our demonstration is based on scenarios we study in collaboration with Le Monde, France's major newspaper
Functional relations from the Yang-Baxter algebra: Eigenvalues of the XXZ model with non-diagonal twisted and open boundary conditions
In this work we consider a functional method in the theory of exactly
solvable models based on the Yang-Baxter algebra. Using this method we derive
the eigenvalues of the XXZ model with non-diagonal twisted and open boundary
conditions for general values of the anisotropy and boundary parameters.Comment: 26 page
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Organic Contaminant-Triggered Self-Healing Soil Mix Cut-Off Wall Materials Incorporating Oil Sorbents
Soil mix cut-off walls have been increasingly used for containment of organic contaminants in polluted land. However, the mixed soil is susceptible to deterioration due to aggressive environmental and mechanical stresses, leading to crack-originated damage and requiring costly maintenance. This paper proposed a novel approach to achieve self-healing properties of soil mix cut-off wall materials triggered by the ingress of organic contaminants. Oil sorbent polymers with high absorption and swelling capacities were incorporated in a cementitious grout and mixed with soil using a laboratory-scale auger setup. The self-healing performance results showed that 500 ”m-wide cracks could be bridged and blocked by the swollen oil sorbents, and that the permeability was reduced by almost an order of magnitude after the permeation of liquid paraffin. It was shown by micro-CT scan tests that the network formed by the swollen oil sorbents acted as attachments and binder, preventing the cracked mixed soil sample from crumbling, and that the oil sorbents swelled three times in volume and therefore occupied the air space and blocked the cracks in the matrix. These promising results exhibit the potential for the oil sorbents to provide soil mix cut-off walls in organically-contaminated land with self-healing properties and enhanced durability
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