1,724 research outputs found
Slave spin cluster mean field theory away from half-filling: Application to the Hubbard and the extended Hubbard Model
A new slave-spin representation of fermion operators has recently been
proposed for the half-filled Hubbard model. We show that with the addition of a
gauge variable, the formalism can be extended to finite doping. The resulting
spin problem can be solved using the cluster mean-field approximation. This
approximation takes short-range correlations into account by exact
diagonalization on the cluster, whereas long-range correlations beyond the size
of clusters are treated at the mean-field level. In the limit where the cluster
has only one site and the interaction strength is infinite, this approach
reduces to the Gutzwiller approximation. There are some qualitative differences
when the size of the cluster is finite. We first compute the critical for
the Mott transition as a function of a frustrating second-neighbor interaction
on lattices relevant for various correlated systems, namely the cobaltites, the
layered organic superconductors and the high-temperature superconductors. For
the triangular lattice, we also study the extended Hubbard model with
nearest-neighbor repulsion. In additionto a uniform metallic state, we find a
charge density wave in a broad doping regime,
including commensurate ones. We find that in the large limit, intersite
Coulomb repulsion strongly suppresses the single-particle weight of the
metallic state.Comment: 10 pages, 11 figures, submitted to PR
Supersolidity, entropy and frustration
We study the properties of t-t'-V model of hard-core bosons on the triangular
lattice that can be realized in optical lattices. By mapping to the spin-1/2
XXZ model in a field, we determine the phase diagram of the t-V model where the
supersolid characterized by the ordering pattern (x,x,-2x') ("ferrimagnetic" or
SS A) is a ground state for chemical potential \mu >3V. By turning on either
temperature or t' at half-filling \mu =3V, we find a first order transition
from SS A to the elusive supersolid characterized by the (x,-x,0) ordering
pattern ("antiferromagnetic" or SS C). In addition, we find a large region
where a superfluid phase becomes a solid upon raising temperature at fixed
chemical potential. This is an analog of the Pomeranchuk effect driven by the
large entropic effects associated with geometric frustration on the triangular
lattice.Comment: 4 pages, igures, LaTe
Orbital-Selective Mott transition out of band degeneracy lifting
We outline a general mechanism for Orbital-selective Mott transition (OSMT),
the coexistence of both itinerant and localized conduction electrons, and show
how it can take place in a wide range of realistic situations, even for bands
of identical width and correlation, provided a crystal field splits the energy
levels in manifolds with different degeneracies and the exchange coupling is
large enough to reduce orbital fluctuations. The mechanism relies on the
different kinetic energy in manifolds with different degeneracy. This phase has
Curie-Weiss susceptibility and non Fermi-liquid behavior, which disappear at a
critical doping, all of which is reminiscent of the physics of the pnictides.Comment: Published versio
Bridging the gap between 3D navigation and semantic search. The INCEPTION platform
The paper presents the main outcomes and future development of the INCEPTION project, “Inclusive Cultural Heritage in Europe through 3D semantic modelling”, funded by the European Commission under the Horizon 2020 Work Programme Europe in a changing world – inclusive, innovative and reflective Societies (Call Reflective-7-2014, Advanced 3D modelling for accessing and understanding European cultural assets) and completed in May 2019. In particular, the key-targeted project achievement will be presented: a specific cloud-based platform conceived to accomplish the main objectives of accessing, understanding and strengthening European Cultural Heritage by means of enriched 3D models. The need for digital data interpretation, in addition to documentation, guided the overall process of the cross-disciplinary work methodology, based on new methods and tools for 3D surveying and H-BIM modelling, new approaches and methodologies for Cultural Heritage 3D data inclusive access and exploitation by means of the Platform
Bridging the gap between 3D navigation and semantic search. The INCEPTION platform
The paper presents the main outcomes and future development of the INCEPTION project, “Inclusive Cultural Heritage in Europe through 3D semantic modelling”, funded by the European Commission under the Horizon 2020 Work Programme Europe in a changing world – inclusive, innovative and reflective Societies (Call Reflective-7-2014, Advanced 3D modelling for accessing and understanding European cultural assets) and completed in May 2019. In particular, the key-targeted project achievement will be presented: a specific cloud-based platform conceived to accomplish the main objectives of accessing, understanding and strengthening European Cultural Heritage by means of enriched 3D models. The need for digital data interpretation, in addition to documentation, guided the overall process of the cross-disciplinary work methodology, based on new methods and tools for 3D surveying and H-BIM modelling, new approaches and methodologies for Cultural Heritage 3D data inclusive access and exploitation by means of the Platform
Antioxidative potential of a combined therapy of anti TNFα and Zn acetate in experimental colitis.
AIM: To evaluate whether combination therapy with anti-tumour necrosis factor α
(TNFα) antibody and Zn acetate is beneficial in dextran sodium sulphate (DSS)
colitis.
METHODS: Colitis was induced in CD1-Swiss mice with 5% DSS for 7 d. The
experimental mice were then randomised into the following subgroups: standard
diet + DSS treated (induced colitis group); standard diet + DSS + subcutaneous 25
μg anti-TNFα treated group; Zn acetate treated group + DSS + subcutaneous 25 μg
anti-TNFα; standard diet + DSS + subcutaneous 6.25 μg anti-TNFα treated group and
Zn acetate treated group + DSS + subcutaneous 6.25 μg anti-TNFα. Each group of
mice was matched with a similar group of sham control animals. Macroscopic and
histological features were scored blindly. Homogenates of the colonic mucosa were
assessed for myeloperoxidase activity as a biochemical marker of inflammation and
DNA adducts (8OH-dG) as a measure of oxidative damage.
RESULTS: DSS produced submucosal erosions, ulcers, inflammatory cell infiltration
and cryptic abscesses which were reduced in both groups of mice receiving either
anti-TNFα alone or combined with zinc. The effect was more pronounced in the
latter group (vs Zn diet, P < 0.02). Myeloperoxidase activity (vs controls, P <
0.02) and DNA adducts, greatly elevated in the DSS fed colitis group (vs
controls, P < 0.05), were significantly reduced in the treated groups, with a
more remarkable effect in the group receiving combined therapy (vs standard diet,
P < 0.04).
CONCLUSION: DSS induces colonic inflammation which is modulated by the
administration of anti-TNFα. Combining anti-TNFα with Zn acetate offers marginal
benefit in colitis severity
Semantic Web Technologies Meet BIM for Accessing and Understanding Cultural Heritage
Within the EU funded project INCEPTION – Inclusive Cultural Heritage in Europe through 3D semantic modelling, the key-targeted achievement is the development of a specific cloud based platform, in order to accomplish the main objectives of accessing, understanding and strengthening European Cultural Heritage by means of enriched 3D models. The whole INCEPTION project is based on the close connection between state-of-the-art architectural modeling technologies (BIM, Building Information Modeling) and the latest cutting-edge web technologies. The platform is grounded on semantic web technologies and makes extensive use of WebGL and RESTful APIs, in order to enrich heritage 3D models by using Semantic Web standards. The INCEPTION platform will be a space for interchange of information and for the dialogue among professionals, students, scholars, curators, non-expert users, etc. Furthermore, the Semantic Web structure interlinks the platform with external Cultural Heritage available linked data and makes it gradually enhanced by specific flexible data structures provided as project specific ontologies.
The paper will describe solutions based on the match between BIM, Cloud and Semantic Web
Solid lipid nanoparticles incorporating melatonin as new model for sustained oral and transdermal delivery systems
DNA structure directs positioning of the mitochondrial genome packaging protein Abf2p
The mitochondrial genome (mtDNA) is assembled into nucleo-protein structures termed nucleoids and maintained differently compared to nuclear DNA, the involved molecular basis remaining poorly understood. In yeast (Saccharomyces cerevisiae), mtDNA is a similar to 80 kbp linear molecule and Abf2p, a double HMG-box protein, packages and maintains it. The protein binds DNA in a non-sequence-specific manner, but displays a distinct 'phased-binding' at specific DNA sequences containing poly-adenine tracts (A-tracts). We present here two crystal structures of Abf2p in complex with mtDNA-derived fragments bearing A-tracts. Each HMG-box of Abf2p induces a 90. bend in the contacted DNA, causing an overall U-turn. Together with previous data, this suggests that U-turn formation is the universal mechanism underlying mtDNA compaction induced by HMG-box proteins. Combining this structural information with mutational, biophysical and computational analyses, we reveal a unique DNA binding mechanism for Abf2p where a characteristic N-terminal flag and helix are crucial for mtDNA maintenance. Additionally, we provide the molecular basis for A-tract mediated exclusion of Abf2p binding. Due to high prevalence of Atracts in yeast mtDNA, this has critical relevance for nucleoid architecture. Therefore, an unprecedented A-tract mediated protein positioning mechanism regulates DNA packaging proteins in the mitochondria, and in combination with DNA-bending and U-turn formation, governs mtDNA compaction
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